RU2776700C1 - Limestone kiln and method for heat supply to it - Google Patents

Abstract

FIELD: industrial equipment.

SUBSTANCE: group of inventions relates to a limestone kiln and a method for supplying heat to it. The kiln includes a kiln chamber (1), a heat supply device and a fan for supplying combustion air (2). In this case, the combustion air supply pipe (21) is connected between the combustion air supply fan (2) and the kiln chamber (1). A combustion air shut-off valve (22) is made on the combustion air supply pipe (21). The heat supply device includes a fuel supply device and a group of sprayers (3). The group of sprayers (3) is connected to the inner cavity of the kiln chamber (1). The sprayer group (3) consists of a total of N sprayers (31). In this case, the fuel supply device includes a coal gas supply device (4) and a pulverized coal supply device (5). The coal gas supply device (4) includes an annular coal gas supply pipe (401) and N outlet pipes for coal gas supply (402) connected to an annular coal gas supply pipe (401). Each outlet pipe for coal gas supply (402) is connected to the supply inlet end of one sprayer (31). The pulverized coal supply device (5) includes an annular pipe for the supply of pulverized coal (501) and N outlet pipes for the supply of pulverized coal (502) connected to an annular pipe for the supply of pulverized coal (501). Each outlet pipe for the supply of pulverized coal (502) is connected to the feed inlet of one sprayer (31). Thus, the coal gas supply device (4) and the pulverized coal supply device (5) share a group of sprayers (3). On each outlet pipe for the supply of coal gas (402) there is a control valve of the outlet pipe for the supply of coal gas (403). On each outlet pipe for the supply of pulverized coal (502) there is a control valve of the outlet pipe for the supply of pulverized coal (503). A flow meter (311) is made on the sprayer (31). The first combustion heat sensor (404) and the first pressure sensor (405) are respectively located on the annular coal gas supply pipe (401). The second combustion heat sensor (504) is located on the annular pipe for supplying pulverized coal (501). In this case, the second pressure sensor (11) is made inside the kiln chamber (1). The cross section of the kiln chamber is sequentially divided radially into several annular heat supply zones. The sprayer group (3) includes several spray matrices. Each matrix of sprayers is respectively located in one annular zone of heat supply. Each matrix of sprayers includes several sprayers (31) evenly distributed around the circumference.

EFFECT: increase in the productivity of the kiln.

26 cl, 13 dwg

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority over the Chinese patent application No. 201910340082.7, titled "LIMESTONE KILN AND METHOD OF SUPPLYING HEAT TO THEM", filed with the China Patent Office on April 25, 2019, the entire content of which is hereby incorporated by reference.

FIELD OF TECHNOLOGY

[0002] The application relates to the field of limestone kiln technology, in particular to a limestone kiln and a method of supplying heat thereto.

BACKGROUND OF THE INVENTION

[0003] The limestone kiln is the main equipment in the lime production process. The limestone raw material is heated to 1100° C. in a limestone kiln and calcined to produce a finished lime product. Fuels used in limestone calcination typically include coal gas and pulverized coal. Due to the different combustion characteristics of coal gas and pulverized coal, for a particular limestone kiln, the type of fuel used is generally fixed.

[0004] FIG. 1 is a schematic view showing the structure of a known limestone kiln which includes a kiln chamber 1 and a heat supply device including an annular fuel supply pipe 2' and a plurality of atomizers 31 connected to an annular fuel supply pipe 2'. Each atomizer 31 is placed at regular intervals across the cross-section of the calcination zone of the kiln chamber 1 to form a group of atomizers 3. Each atomizer 31 in the group of atomizers 3 is connected to the interior cavity of the kiln chamber 1. The raw material, which is limestone, is loaded from the top of the kiln chamber 1, fuel is distributed to each atomizer 31 from the annular fuel supply pipe 2', through each atomizer 31, the fuel is evenly distributed in the interior cavity of the furnace chamber 1, and at the same time, combustion air is supplied to the interior cavity of the furnace chamber 1. The limestone raw material is calcined and decomposed to form calcium oxide and carbon dioxide exhaust gas by the action of combustion and heat generation by coal gas, and the carbon dioxide exhaust gas is discharged from the top of the furnace chamber 1. Under the influence of cooling air at the bottom of the furnace chamber 1 , the temperature of the finished calcium oxide product is reduced to the predetermined material discharge temperature, and then the finished calcium oxide product is discharged from the bottom of the kiln chamber 1 to complete the production of quicklime.

[0005] Because the known limestone kiln can only use coal gas or pulverized coal, and the heating medium fuel is the only one, the process adaptability of the limestone kiln is low. In addition, although each pulverizer 31 in the group of pulverizers 3 is placed at regular intervals across the cross section of the calcining zone of the kiln chamber 1, the problem of uneven heat supply of the known limestone kiln remains unsolved, so that burnt lime occurs in the high temperature region, and in the low temperature region, underburning of lime occurs, which affects the quality of the products of the limestone kiln. The above factors greatly limit the performance of the limestone kiln.

BRIEF DESCRIPTION OF THE INVENTION

[0006] In order to solve the problem associated with the low productivity of the existing limestone kiln, the invention provides a limestone kiln and a method for supplying heat thereto.

[0007] According to a first aspect, the application provides a limestone kiln including a kiln chamber, a heat supply device, and a combustion air supply fan, wherein a combustion air supply pipe is connected between the combustion air supply fan and the kiln chamber, on the combustion air supply pipe a combustion air shut-off valve is made, the heat supply device includes a fuel supply device and a group of atomizers, a group of atomizers is connected to the internal cavity of the furnace chamber, atomizer group consists of a total of N atomizers, the fuel supply device includes a coal gas supply device and a pulverized coal supply device, the coal gas supply device includes an annular coal gas supply pipe and N coal gas discharge pipes connected to the coal gas supply annular pipe, each coal gas discharge pipe is connected to the supply inlet end of one atomizer, the pulverized includes an annular pulverized coal supply pipe and N pulverized coal discharge pipes connected to the annular pulverized coal supply pipe, and each pulverized coal discharge pipe is connected to the supply inlet end of one atomizer, so that the coal gas supply device and the device pulverized coal feeds share a group of atomizers; each coal gas discharge pipe has a coal gas discharge pipe control valve, and each pulverized coal discharge pipe has a pulverized coal discharge pipe control valve; a flow meter is made on the atomizer; a first calorific value sensor and a first pressure sensor are respectively disposed on the annular coal gas supply pipe, a second calorific value sensor is disposed on the annular pulverized coal supply pipe, and a second pressure sensor is disposed inside the furnace chamber; the cross section of the furnace chamber is sequentially divided in the radial direction into several annular heat supply zones, the atomizer group includes several atomizer arrays, each atomizer matrix is respectively located in one annular heat supply zone, and each atomizer matrix includes several atomizers uniformly distributed around the circumference.

[0008] In combination with the first aspect, in the first possible embodiment of the first aspect, the atomizer includes an atomizer body, a supply inlet and a supply outlet are respectively provided at the two ends of the atomizer body, the atomizer body includes an inner pipe body and an outer pipe body inserted with external side of the inner pipe body, inside the inner pipe body there is an internal fuel channel, an annular external fuel channel is formed between the inner pipe body and the outer pipe body, several groups of bypass holes are located at certain intervals in the axial direction on the section of the outer pipe body near the supply outlet , the bypass hole group includes a plurality of bypass through holes uniformly distributed around the circumference, and the bypass through hole is a downwardly oblique through hole.

[0009] In combination with the first aspect or the first possible embodiment of the first aspect, in the second possible embodiment of the first aspect, the fuel supply apparatus further includes N fuel switches, each fuel switch includes a coal gas supply inlet, a pulverized coal supply inlet and a fuel outlet, wherein the coal gas inlet is connected to the coal gas outlet pipe, the pulverized coal inlet is connected to the pulverized coal outlet, the fuel outlet is connected to the supply inlet end of the atomizer. , at the inlet for supplying coal gas and the inlet for supplying pulverized coal, valve bodies are respectively provided; the coal gas supply device further includes a coal gas supply fan, the coal gas supply fan is connected to the annular coal gas supply pipe by a coal gas transport pipeline, and a coal gas shut-off valve is provided on the coal gas transport pipeline; the pulverized coal supply device further includes a pulverized coal supply fan, the pulverized coal supply fan is connected to the annular pulverized coal supply pipe via the pulverized coal transportation pipeline, and the pulverized coal transportation pipeline has a pulverized coal shut-off valve.

[0010] In combination with the second possible embodiment of the first aspect, in the third possible embodiment of the first aspect, the fuel supply device further includes a nitrogen purge device comprising a compressed nitrogen reservoir and an annular nitrogen supply pipe, wherein the annular nitrogen supply pipe is connected with N discharge pipes for supplying nitrogen, on the N discharge pipes for supplying nitrogen, respectively, a control valve of the discharge pipe for supplying nitrogen is provided, the compressed nitrogen tank and the annular nitrogen supply pipe are connected by a nitrogen transport pipeline, and a nitrogen shut-off valve is provided on the nitrogen transport pipeline ; the fuel switch further includes a nitrogen supply inlet, the nitrogen supply inlet is connected to the nitrogen supply outlet pipe, and only one of the coal gas supply inlet, the pulverized coal supply inlet, and the nitrogen supply inlet is connected to the outlet at the same time. a fuel supply port by adjusting each valve body; when the nitrogen shut-off valve and the valve body at the nitrogen supply inlet are opened, the residual coal gas or pulverized coal in the fuel switch is purged with nitrogen into the atomizer.

[0011] In combination with the third possible embodiment of the first aspect, in the fourth possible embodiment of the first aspect, the valve body includes a rigid O-ring, a sealing plug, and a return spring; in the center inside the fuel switch, a fixed support steel body is made; rigid sealing rings are respectively fixed around the perimeter of the pipe holes of the coal gas inlet, the pulverized coal inlet, and the nitrogen inlet; one end of the return spring is connected to the supporting steel case, and the other end of the return spring is connected to the sealing plug; when the seal plug is pressurized from the internal cavity of the fuel switch, the seal plug is firmly pressed against the rigid sealing ring, so that the valve body is in the closed state; when pressure is applied to the seal plug from the outside of the fuel selector, the return spring is compressed and the seal plug and the hard seal ring are separated so that the valve body is in the open state.

[0012] In combination with the third exemplary embodiment of the first aspect or the fourth exemplary embodiment of the first aspect, in the fifth exemplary embodiment of the first aspect, the coal gas supply apparatus further includes a coal gas return line, on which a coal gas check valve is mounted, wherein the outlet the end of the coal gas return pipeline is connected to the inlet end of the coal gas supply fan, the inlet end of the coal gas return pipeline is connected to the coal gas transport pipeline, the inlet end of the coal gas return pipeline is located between the coal gas shut-off valve and the outlet end of the coal gas supply fan, and when the coal gas check valve is opened, the coal gas supply air circulates between the coal gas return pipe and the coal gas supply fan to depressurize the coal gas supply fan.

[0013] In combination with the fifth possible embodiment of the first aspect, in the sixth possible embodiment of the first aspect, the pulverized coal supply apparatus further includes a pulverized coal return line on which a pulverized coal check valve is mounted, wherein the outlet end of the pulverized coal return line is connected to the inlet end of the pulverized coal supply fan, the inlet end of the pulverized coal return pipeline is connected to the pulverized coal conveying pipeline, the inlet end of the pulverized coal return pipeline is located between the pulverized coal shut-off valve and the outlet end of the pulverized coal supply fan, and when the pulverized coal check valve is opened, the pulverized coal supply air circulates between the pulverized coal return pipe and the pulverized coal supply fan to depressurize the pulverized coal supply fan.

[0014] According to a second aspect, the present application provides a method for supplying heat to a limestone kiln, the limestone kiln according to the first aspect or the first possible embodiment of the first aspect, the method includes the following steps:

[0015] When the pressure difference between the first pressure sensor and the second pressure sensor is greater than or equal to the minimum furnace inlet pressure, the N pulverized coal outlet pipe control valves are closed, and the N coal gas outlet pipe control valves are opened, so that all N atomizers supply coal gas as fuel to the furnace chamber;

[0016] calculating the average amount of coal gas supply W _ij of each nozzle in the annular heat input zone, and adjusting the opening degree of each control valve of the coal gas discharge pipe to match the measured value S _ij of the flow meter with W _ij ;

[0017] when the pressure drop is less than the minimum furnace inlet pressure, the switching number N _m is calculated; N _m is the theoretical number of atomizers needed to switch the fuel medium;

N_x

N;[0018] The N _x control valves of the coal gas discharge pipes are closed, and respectively, the N _x control valves of the pulverized coal discharge pipes are opened, thus the fuel supplied by the N _x nozzles in the nozzle group is switched from coal gas to pulverized gas. coal, N _x is the actual number of atomizers needed to switch the fuel medium, and N _m

N _x

N;

[0019] The fuel input amount T _ij of each atomizer in the annular heat input zone is calculated, and the opening degrees of the N _x pulverized coal outlet pipe control valves and the other NN _x coal gas outlet pipe control valves are adjusted to match the measured value S _ij flowmeter with T _ij ; and

[0020] The combustion air shut-off valve opens and the operation frequency of the combustion air supply fan increases to match the amount of combustion air entering the furnace with the total amount of fuel, and the switching process is completed.

[0021] In some embodiments of the invention, the calculation of the number of switches N _m includes:

[0022] calculating the maximum number of coal gas atomizers N _q allowed in a group of atomizers at the current pressure P ₁ in the annular coal gas supply pipe according to the pressure difference between the first pressure sensor and the second pressure sensor; and

[0023] calculating the difference value between the total number of nozzles N and the maximum number of coal gas nozzles N _q to obtain the number of switchings N _m .

[0024] In some embodiments of the invention, the maximum number of coal gas atomizers N _q is calculated according to the formula below:

[0025] where ρ is the density of the coal gas, ν _i is the calculated flow rate of the coal gas atomizer, h _t is the drag coefficient of the annular coal gas supply pipe, h _i is the drag coefficient of the coal gas discharge pipe, P ₁ is the pressure in the annular coal gas pipe measured by the first pressure sensor, P ₂ is the pressure inside the furnace chamber measured by the second pressure sensor, and α is a correction factor related to the size of the limestone particles in the furnace chamber.

[0026] In some embodiments of the invention, the method further includes:

[0027] presetting several modes of uniform heat supply in accordance with the total number of nozzles N included in the group of nozzles, and the location of each nozzle in the cross section of the furnace chamber; the uniform heat supply mode indicates the position of the nozzle required to switch the fuel medium and the actual number of nozzles N _x in the nozzle group when N _m is within the specified value range.

[0028] In some embodiments of the invention, after calculating the number of switches N _m , the method further includes:

[0029] determining the target mode of uniform heat supply corresponding to the range of values of N _m ;

[0030] and switching the fuel medium of the N _x atomizers in the corresponding position from coal gas to pulverized coal in accordance with the indication of the target mode of uniform heat supply.

[0031] In some embodiments of the invention, the method further includes:

[0032] pre-labeling each sprayer in a group of sprayers;

[0033] setting an appropriate relationship between a range of N _m values and a set of atomizers in the matrix to obtain a uniform heat supply mode; and the matrix atomizer set contains marks of the N _x nozzles in the matrix atomizer set requiring fuel medium switching.

[0034] In some embodiments of the invention, the method further includes:

[0035] when a plurality of uniform heat input modes are preset, determining a uniform heat input threshold value N _y ;

[0036] when the range of values is (N _y , N], N _x is N, therefore, the even heat supply mode is pulverized coal heat supply;

N_y, следовательно, режим равномерного подвода тепла представляет собой комбинированный подвод тепла с применением угольного газа и пылевидного угля;[0037] when the range of values is (0, N _y ] being 0<N _x

N _y , therefore, the uniform heat supply mode is a combined heat supply using coal gas and pulverized coal;

[0038] and when the value range is 0, N _x is 0, therefore, the uniform heat supply mode is the heat supply using coal gas.

[0039] In some embodiments, the total heat input Q _i of the annular heat input zone is:

[0040] where Q ₁ is the total amount of heat input by the first annular heat input zone, the first annular heat input zone is at the center of the cross section of the furnace chamber; Q is the theoretical amount of heat input required to fire the material at a certain cross-sectional height of the kiln chamber; 5 is the heat transfer coefficient between flue gas and material in a limestone kiln; k _1i is the proportionality factor of the heat input between the first annular heat input zone and the i ^th annular heat input zone; Y is the number of annular heat supply zones.

[0041] In some embodiments of the invention, the average amount of supplied coal gas W _ij each nozzle in the annular heat supply zone is calculated according to the formula below:

j

X_i, и 1

i

Y.[0042] where Q _i is the total heat input of the annular heat input zone, X _i is the number of nozzles included in the annular heat input zone, h ₁ is the specific calorific value of the coal gas measured by the first calorific value sensor, 1

j

X _i , and 1

i

Y.

[0043] In some embodiments of the invention, the amount of fuel supplied T _ij of each nozzle in the annular heat supply zone is calculated according to the formula below:

j

X_i, и 1

i

Y.[0044] where M _i is the average amount of heat input of each atomizer in the annular heat input zone; Q _i is the total heat input of the annular heat input zone; X _i is the number of atomizers included in the annular heat supply zone; h=h ₂ for nozzles corresponding to the N _x control valves of the pulverized coal outlet pipes in the open state; h=h ₁ for nozzles corresponding to other NN _x charcoal gas outlet pipe control valves when open; where h ₁ is the specific calorific value of coal gas measured by the first calorific value sensor, hi is the specific calorific value of pulverized coal measured by the second calorific value sensor, 1

j

X _i , and 1

i

Y.

[0045] Regarding the scheme of the second aspect, the fuel supply device includes a coal gas supply device and a pulverized coal supply device, a coal gas supply device and a pulverized coal supply device independent of each other share a group of atomizers, each atomizer in the atomizer group is connected to one exhaust pipe for supplying coal gas and one exhaust pipe for supplying pulverized coal, respectively, thus the fuel medium supplied by each atomizer can be switched between coal gas and pulverized coal. During the initial heat input, the first pressure sensor is used to measure the pressure in the annular coal gas supply pipe, and the second pressure sensor is used to measure the pressure inside the furnace chamber. A pressure difference between the two sensors greater than or equal to the minimum furnace inlet pressure indicates that the coal gas supply is sufficient and coal gas heat supply is preferably applied. The average amount of coal gas supply W _ij of each nozzle in the annular heat supply zone is calculated, and the degree of opening of each control valve of the coal gas discharge pipe is adjusted to ensure that the measured value S _ij of the flow meter matches W _ij , thus guaranteeing the uniformity and accuracy of supply heat in the cross section of the furnace chamber.

[0046] During heat supply, the pressure difference between the first pressure sensor and the second pressure sensor is less than the minimum furnace inlet pressure, indicating that the pressure of the coal gas fluctuates, so that the pressure of the coal gas supply pipe network is too low, and the pressure of the coal gas is not sufficient to allow entry into the furnace. Under such conditions, it is necessary to start the combined heat supply using coal gas and pulverized coal, calculate the theoretical number of switchings N _m , then close N _x coal gas control valves in the coal gas supply device, and open N _x pulverized coal control valves in the pulverized coal supply device. coal, while N _x is greater than or equal to N _m . Accordingly, the fuel medium of at least N _m nozzles in the nozzle group is switched from raw coal gas to pulverized coal, as long as it is ensured that the coal gas in other NN _x nozzles in the nozzle group can be supplied to the interior of the furnace chamber. at a flow rate not less than specified in the specification, thus automatically switching the fuel medium of the specified atomizer in accordance with the pressure of the coal gas. Therefore, assuming that heat supply using coal gas is the first choice, according to the application, stable operation of the limestone kiln under the condition of low pressure of coal gas can be ensured, sufficient supply of the fuel medium to the kiln chamber can be ensured, and the fuel medium can be switched limestone kiln, which is not the only one, thus improving the production stability and adaptability of the limestone kiln, and facilitating the continuous and highly efficient production of the limestone kiln. Moreover, according to the diagram, the cross section of the limestone kiln is divided into several heat input zones in the radial direction, and the total heat input required for each heat input zone is obtained according to the difference in the heat output amount of each heat input zone, thus accurately calculated and ensure the amount of fuel supply required by each independent atomizer, accurate heat supply is realized, materials at different positions on the same horizontal cross-section of the kiln chamber are heated evenly, overburning or underburning of lime is prevented, and the product quality of the limestone kiln is improved . Therefore, the application can significantly improve the productivity of the limestone kiln.

[0047] According to a third aspect, the present application provides a method for supplying heat to a limestone kiln, the limestone kiln according to the sixth possible embodiment of the first aspect, the method including the following steps:

[0048] when the pressure difference between the first pressure sensor and the second pressure sensor is greater than or equal to the minimum furnace inlet pressure, the coal gas heat supply mode is preferably started to supply coal gas as fuel to the furnace chamber by all N nozzles; charcoal gas heat supply mode is as follows: charcoal gas shut-off valve, coal gas fan and valve body at the inlet port for coal gas supply N fuel switches, all open, pulverized coal shut-off valve and valve body at the inlet the pulverized coal inlet N fuel switches, all closed, the pulverized coal fan in the ready-to-operate state, and the nitrogen shut-off valve and nitrogen inlet valve bodies N fuel switches, all closed; the coal gas check valve is in the closed state, and the pulverized coal check valve is in the open state; and N coal gas outlet pipe control valves, N pulverized coal outlet pipe control valves, and N nitrogen outlet pipe control valves, all open;

[0049] the average amount of coal gas supply W _ij of each nozzle in the annular heat input zone is calculated, and the opening degree of each control valve of the coal gas discharge pipe is adjusted to match the measured value S _ij of the flow meter with W _ij ;

[0050] when the pressure drop is less than the minimum furnace inlet pressure, the switching number N _m is calculated; N _m is the theoretical number of atomizers needed to switch the fuel medium;

N_x

N;[0051] the uniform heat mode to be started is determined, where the uniform heat mode is used to indicate the position of the nozzle required to switch the fuel medium and the actual number of nozzles N _x in the nozzle group when N _m is within the specified range of values , and N _m

N _x

N;

[0052] after starting the uniform heat supply mode, the amount of fuel supplied T _ij of each atomizer in the annular heat supply zone is calculated;

[0053] The opening degrees of the control valves of the pulverized coal supply pipes at the positions corresponding to N _x nozzles are adjusted, and the opening degrees of the control valves of the coal gas discharge pipes corresponding to other NN _x nozzles are adjusted so that the measured value S _ij of the flow meter corresponds to T _ij ; and

[0054] The combustion air shut-off valve opens and the operation frequency of the combustion air supply fan increases to match the amount of combustion air entering the furnace with the total amount of fuel, and the switching process is completed.

[0055] In some embodiments of the invention, the method further includes:

[0056] determining a uniform heat input threshold value N _y according to the total number of atomizers N included in the atomizer group and the location of each atomizer in a cross section of the furnace chamber;

[0057] when the range of values is (N _y , N], N _x is N, therefore, the even heat supply mode is pulverized coal heat supply;

N_y, следовательно, режим равномерного подвода тепла представляет собой комбинированный подвод тепла с применением угольного газа и пылевидного угля;[0058] when the range of values is (0, N _y ] being 0<N _x

N _y , therefore, the uniform heat supply mode is a combined heat supply using coal gas and pulverized coal;

[0059] and when the range of values is 0, N _x is 0, therefore, the uniform heat supply mode is heat supply using coal gas.

[0060] In some embodiments, when the uniform heat input mode is pulverized coal heat input, the uniform heat input mode is started as follows:

[0061] the valve body at the charcoal gas inlet of the N fuel switches and the charcoal gas shut-off valve are successively closed, the charcoal gas check valve is opened at the same time, and the charcoal gas ventilator is placed in a ready-to-operate state;

[0062] The nitrogen shut-off valve and the valve body at the nitrogen supply inlet of the N fuel switches are opened in sequence, and after the residual pulverized carbon in the fuel switch is blown into the atomizer with nitrogen, the valve body at the nitrogen supply inlet of the N fuel switches and the shut-off valve are successively closed nitrogen; and

[0063] The pulverized coal check valve closes, the operating frequency of the pulverized coal supply fan increases, and when the pressure of the pulverized coal reaches the required value at the furnace inlet, the pulverized coal shut-off valve and the valve body at the pulverized coal supply inlet N fuel switches are opened in sequence Thus, the pulverized coal passes through the pulverized coal conveying pipeline, the annular pulverized coal supply pipe, N pulverized coal outlet pipes, the pulverized coal inlet and the fuel outlet of N fuel switches and N atomizers in succession, and enters into the interior cavity of the furnace chamber, so that the mode of uniform heat supply starts.

[0064] In some embodiments, when the uniform heat input mode is a combined heat input using coal gas and pulverized coal, the uniform heat input mode is started as follows:

[0065] Close the pulverized coal discharge pipe control valve and the nitrogen supply discharge pipe control valve corresponding to the remaining NN _x nozzles, and at the same time close the coal gas discharge pipe control valve at the position corresponding to N _x nozzles, and closing the valve body at the inlet for supplying coal gas in the fuel switch in a position corresponding to N _x nozzles;

[0066] The nitrogen shut-off valve and the valve body at the nitrogen inlet of the fuel switch are opened in sequence at the position corresponding to N _x atomizers, and after the residual carbon gas in the fuel switch is purged with nitrogen into the atomizer, the valve body at the nitrogen inlet is sequentially closed a fuel selector in the position corresponding to N _x atomizers and a nitrogen shut-off valve; and

[0067] The pulverized coal check valve is closed, the operating frequency of the pulverized coal supply fan is increased, and when the pressure of the pulverized coal reaches the required value at the furnace inlet, the pulverized coal shut-off valve and the valve body at the pulverized coal supply inlet of the fuel switch are opened in succession. position corresponding to N _x atomizers, so that the pulverized coal passes through the pulverized coal conveying pipeline, the annular pulverized coal supply pipe, the N _x pulverized coal discharge pipes, the pulverized coal supply inlet and the N _x fuel outlet fuel switches, and N _x atomizers and enters the inner cavity of the furnace chamber.

[0068] In some embodiments of the invention, the calculation of the number of switches N _m includes:

[0069] calculating the maximum number of coal gas atomizers N _q allowed in a group of atomizers at the current pressure in the annular coal gas supply pipe according to the pressure difference between the first pressure sensor and the second pressure sensor; and

[0070] calculating the difference value between the total number of nozzles N and the maximum number of coal gas nozzles N _q to obtain the number of switchings N _m .

[0071] In some embodiments of the invention, the maximum number of coal gas atomizers N _q is calculated according to the formula below:

[0072] where ρ is the density of the coal gas, ν _l is the calculated flow rate of the coal gas atomizer, h _t is the resistance coefficient of the annular coal gas supply pipe, h _i is the resistance coefficient of the coal gas discharge pipe, P ₁ is the pressure in the annular coal gas pipe measured by the first pressure sensor, P ₂ is the pressure inside the furnace chamber measured by the second pressure sensor, and α is a correction factor related to the size of the limestone particles in the furnace chamber.

[0073] In some embodiments, the total heat input Q _i of the annular heat input zone is:

[0074] where Q1 is the total heat input of the first annular heat input zone, the first annular heat input zone is at the center of the cross section of the furnace chamber; Q is the theoretical amount of heat input required to fire the material at a certain cross-sectional height of the kiln chamber; δ is the heat transfer coefficient between combustion and flue gas and material in the limestone kiln; k1i is a proportionality factor for heat input between the first annular heat input zone i ^th annular heat input zone; Y is the number of annular heat supply zones.

[0075] In some embodiments of the invention, the average amount of supplied coal gas W _ij each nozzle in the annular heat supply zone is calculated according to the formula below:

j

X_i, и 1

i

Y.[0076] where Q _i is the total heat input of the annular heat input zone, X _i is the number of nozzles included in the annular heat input zone, h ₁ is the specific calorific value of the coal gas measured by the first calorific value sensor, 1

j

X _i , and 1

i

Y.

[0077] In some embodiments of the invention, the amount of fuel supplied T _ij of each nozzle in the annular heat supply zone is calculated according to the formula below:

j

X_i, и 1

i

Y.[0078] where M _i is the average amount of heat input of each atomizer in the annular heat input zone; Q _i is the total heat input of the annular heat input zone; X _i is the number of atomizers included in the annular heat supply zone; h=h ₂ for N _x nozzles in the open position and h=h ₁ for other NN _x nozzles; wherein h ₁ is the specific calorific value of coal gas measured by the first calorific value sensor, h ₂ is the specific calorific value of pulverized coal measured by the second calorific value sensor, 1

j

X _i , and 1

i

Y.

[0079] Regarding the scheme of the third aspect, the coal gas supply device and the pulverized coal supply device are used in parallel, and the limestone kiln fuel switching control is performed by the fuel switch. During the initial heat input, the first pressure sensor is used to measure the pressure in the annular coal gas supply pipe, and the second pressure sensor is used to measure the pressure inside the furnace chamber. A pressure difference between the two sensors greater than or equal to the minimum furnace inlet pressure indicates that the coal gas supply is sufficient and the coal gas heat supply mode is predominantly applied. The average amount of coal gas supply W _ij of each nozzle in the annular heat supply zone is calculated, and the degree of opening of each control valve of the coal gas discharge pipe is adjusted to ensure that the measured value S _ij of the flow meter matches W _ij , thus guaranteeing the uniformity and accuracy of supply heat in the cross section of the furnace chamber.

[0080] After starting the coal gas heat supply mode, the pressure difference between the first pressure sensor and the second pressure sensor, less than the minimum furnace inlet pressure, indicates that the pressure of the coal gas fluctuates, so that the pressure in the supply pipe network of coal gas is too low and the pressure of coal gas is not sufficient to allow entry into the furnace. Under such conditions, the heat supply mode is switched. The theoretical number of switching N _m is calculated, and the mode of uniform heat supply is determined, which is necessary for starting in the future. The mode of uniform heat supply is pre-set according to the total number of nozzles N included in the group of nozzles, and the location of each nozzle in the cross section of the furnace chamber, taking into account the uniformity of heat supply to the chamber. While calculating N _m , the position of the atomizer required to switch the fuel medium corresponding to the range of values to which N _m belongs and the actual number of atomizers N _x can be detected. Valve bodies are formed on the coal gas inlet, the pulverized coal inlet, and the nitrogen inlet in the fuel switch, respectively. Only one valve body is open at a time, and the other valve bodies are in the closed state, thus preventing coal gas from entering the pulverized coal supply ring pipe or pulverized coal from entering the coal gas ring supply pipe as a result of mutual communication, and at the same time can be mixing of the fuel caused by the return of the fuel to the furnace chamber is prevented, thus realizing effective cut-off of coal gas and pulverized coal. The pulverized coal supply device and the coal gas supply device are combined and isolated by a fuel switch. By controlling the opening and closing state of each valve in the limestone kiln and the working state of the fan, the fuel medium of the limestone kiln can be switched quickly, automatically and flexibly, a variety of heat supply modes are realized, therefore, the disadvantages of one type of supply fuel are eliminated. heat and low technological adaptability. In addition, according to the diagram, the cross section of the limestone kiln is divided into several heat input zones in the radial direction, and the total amount of heat input required for each heat input zone is obtained in accordance with the difference in the heat output amount of each heat input zone, thus the amount of fuel supplied required by each independent atomizer is accurately calculated and provided, accurate heat supply is realized, materials are heated uniformly in different positions on the same horizontal cross section of the furnace chamber, overburning or underburning of lime is prevented. Thus, the product quality of the limestone kiln is improved, and therefore the application can greatly improve the productivity of the limestone kiln.

BRIEF DESCRIPTION OF THE DRAWINGS

[0081] In order to more clearly illustrate the technical scheme of the present application, the drawings required in the embodiments of the invention will be briefly presented below. Obviously, other drawings can also be obtained from these drawings by those skilled in the art, without involving creative efforts.

[0082] FIG. 1 is a schematic diagram showing the construction of an existing limestone kiln;

[0083] FIG. 2 is a schematic view showing the overall structure of the limestone kiln shown in Embodiment 1 of the present application;

[0084] FIG. 3 is a structural view of the heat input device of the limestone kiln shown in Embodiment 1 of the present application;

[0085] FIG. 4 is a sectional view of the annular heat supply zone in cross section of the furnace chamber shown in Embodiment 1 of the present application;

[0086] FIG. 5 is a cross-sectional view of the placement of each nozzle in the furnace chamber in the group of nozzles shown in Embodiment 1 of the present application;

[0087] FIG. 6 is a view of the placement of the coal gas atomizer and the pulverized coal atomizer in each uniform heat supply mode shown in Embodiment 1 of the present application;

[0088] FIG. 7 is a schematic view showing the general construction of the limestone kiln shown in Embodiment 3 of the present application;

[0089] FIG. 8 is a schematic view showing a partial construction of the limestone kiln shown in Embodiment 3 of the present application;

[0090] FIG. 9 is a schematic view showing the structure of the fuel switch shown in Embodiment 3 of the present application;

[0091] FIG. 10 is a schematic view showing the structure of another fuel switch shown in Embodiment 3 of the present application;

[0092] FIG. 11 is a schematic view showing the structure of the atomizer body shown in Embodiment 5 of the present application;

[0093] FIG. 12 is a circular cross-section of a portion of the atomizer body near the outlet of Embodiment 5 of the present application;

[0094] FIG. 13 is a schematic representation of the dispersion range of the nebulizer shown in Embodiment 5 of the present application.

DETAILED DESCRIPTION OF EMBODIMENTS

[0095] The following is a more detailed description of the technical solution with embodiments of the present application and the accompanying drawings for a more detailed explanation of the technical solution of the present application to specialists in this field of technology.

[0096] As shown in FIG. 2 and FIG. 3, the first embodiment of the present application provides a limestone kiln, which includes a kiln chamber 1, a heat supply device and a fan for supplying combustion air 2. The heat supply device is used to supply and transport the fuel required for burning limestone to the kiln chamber 1, and the combustion air supply pipe 21 connects the combustion air supply fan 2 and the furnace chamber 1 to each other. The combustion air supply pipe 21 is provided with a combustion air shut-off valve 22, so that when the combustion air supply fan 2 is started and the combustion air shut-off valve 22 is opened, the combustion air enters the interior of the furnace chamber 1 through the combustion air supply pipe 21, thereby ensuring the intake of combustion air to carry out the combustion of fuel and release heat.

[0097] In particular, in the embodiment, the heat supply device includes a fuel supply device and a nozzle group 3 communicating with the interior of the furnace chamber 1. The nozzle group 3 is used to supply fuel supplied by the fuel supply device to the interior of the furnace chamber 1 , while the group of nozzles 3 has N nozzles 31, that is, the total number of nozzles 31 included in the group of nozzles 3 is N. The fuel supply device includes a coal gas supply device 4 and a pulverized coal supply device 5. The coal gas supply device 4 contains an annular a coal gas supply pipe 401 and N coal gas discharge pipes 402 in communication with an annular coal gas supply pipe 401, each coal gas discharge pipe 402 in communication with a supply inlet end of one atomizer 31. The pulverized coal supply device 5 comprises annular pulverized coal supply pipe 501 and N outlet pipes pulverized coal supply pipe 502 connected to an annular pulverized coal supply pipe 501, each pulverized coal discharge pipe 502 communicating with a feeding inlet end of one atomizer 31, so that the coal gas supply device 4 and the pulverized coal supply device 5 share the system 3. Each coal gas discharge pipe 402 is equipped with a coal gas discharge pipe control valve 403, and each pulverized coal discharge pipe 502 is equipped with a pulverized coal discharge pipe control valve 503. A flow meter 311 is provided on the atomizer 31. First the calorific value sensor 404 and the first pressure sensor 405 are respectively located on the annular coal gas supply pipe 401, the second calorific value sensor 504 is located on the annular pulverized coal supply pipe 501, and the second pressure sensor 11 is provided inside the furnace chamber 1.

[0098] Known limestone kilns can only use coal gas or pulverized coal. When it becomes necessary to change the type of fuel, it is necessary to change the heat supply system of the limestone kiln, which reduces the versatility of its application. In addition, for a limestone kiln used in a metallurgical plant, the cost of coal gas as a by-product of iron, steel, etc. production processes is low, but the supply of such fuel is unstable, and therefore the amount of coal gas and its calorific value are often fluctuate greatly, so it is difficult to guarantee the stability of production when using coal gas as the only fuel. However, the cost of lime production increases when pulverized coal is used as the sole fuel. Thus, in the known limestone kiln, one type of fuel is used, and it is not possible to use different types of fuel depending on the operating conditions in the steel plant, resulting in low production adaptability and low productivity of the limestone kiln.

[0099] According to an embodiment, based on the construction of the limestone kiln shown in FIG. 1, the heat supply device includes a coal gas supply device and a pulverized coal supply device arranged in parallel, wherein the coal gas supply device and the pulverized coal supply device independently use a nozzle group 3, and a number of nozzles 31 connected to the exhaust pipes. for supplying coal gas 402 and outlet pipes for supplying pulverized coal 502, in the group of nozzles 3 is N nozzles. Wherein, each nozzle 31 in the group of nozzles 3 respectively communicates with one coal gas outlet pipe 402 and one pulverized coal outlet pipe 502, wherein the coal gas outlet pipe control valve 403 and the pulverized coal outlet pipe control valve 503 related to the same atomizer 31 are not opened at the same time, so that communication between the coal gas outlet pipe 402 and the pulverized coal outlet pipe 502 is eliminated, and it is ensured that each atomizer 31 atomizes the coal gas and the pulverized coal without mixing them with each other. with a friend.

[00100] The nozzles 31 operate as follows when the pulverized coal discharge pipe control valve 503 located on the pulverized coal discharge pipe 502 connected to one nozzle 31 is closed, and the coal gas discharge pipe control valve 403 located on the discharge pipe for supplying coal gas 402, which communicates with one atomizer 31, is open, the fuel medium transported by the atomizer 31 is coal gas; when the coal gas outlet pipe control valve 403 located on the coal gas outlet pipe 402 connected to one nozzle 31 is closed and the pulverized coal outlet pipe control valve 503 located on the pulverized coal outlet pipe 502, communicating with one atomizer 31 is open, the fuel medium supplied by the atomizer 31 is pulverized coal. In the embodiment, by controlling the opening and closing of the coal gas outlet pipe control valve 403 and the pulverized coal outlet pipe control valve 503, the fuel medium supply of each nozzle 31 can be easily controlled to select between coal gas and pulverized coal, which can effectively solve problems of the known limestone kiln using a single fuel source, moreover, flexible switching of the fuel medium according to the production operating conditions of the limestone kiln is achieved, and the production adaptability of the kiln is improved.

[00101] Compared with pulverized coal fuel, coal gas fuel, which is a by-product of the production of iron, steel, and the like, has the advantages of low cost and simple combustion apparatus. Therefore, according to the inventive solution, when the pressure of the coal gas meets the kiln inlet conditions, the coal gas fuel is used as the preferred fuel in the initial heat supply in the limestone kiln. At the initial heat supply, the pressure P1 in the annular coal gas supply pipe is measured by the first pressure sensor 405, and the pressure P2 inside the furnace chamber is measured by the second pressure sensor 11. When the pressure difference ΔP between the sensors is greater than or equal to the minimum furnace inlet pressure ΔPmin, it means that a sufficient supply of coal gas is achieved, which satisfies the condition at the inlet of the furnace, therefore, the supply of coal gas is preferable. In the coal gas supply process, if it is found that the pressure difference ΔP is less than the minimum furnace inlet pressure ΔPmin, it indicates that the coal gas pressure fluctuates, resulting in the pressure in the coal gas pipeline network is too low and the coal gas pressure is not enough to oven entrance. Thus, the fuel medium conveyed by several or all of the atomizers 31 in the atomizer group 3 can be switched from coal gas to pulverized coal, thereby ensuring stable operation of the limestone kiln.

[00102] Regarding the known limestone kiln shown in FIG. 1, the Applicant has found in industrial practice that, on the one hand, the Darcy coefficient of each atomizer is not constant due to the differences between each atomizer occurring during the manufacturing process and the different mounting positions of each atomizer, so that the fuel is unevenly distributed between the atomizers, and the defect associated with unevenness cannot be corrected due to the lack of the necessary means of detection and adjustment, which leads to an uneven distribution of fuel over the cross section of the furnace chamber. On the other hand, theoretically, the heat transfer in each part of the cross section of the furnace chamber is different, and accordingly, in order to maintain the same temperature, the theoretical amount of heat input required for each part of the cross section of the furnace chamber is different. Heat transfer in the central part of the cross-section of the furnace chamber is minimal, and, theoretically, the required amount of heat input is also minimal; however, the maximum heat transfer area and the maximum heat transfer value are achieved at the edges of the cross section of the furnace chamber, so the theoretical amount of heat input is also maximum. Due to the limitation of factors in two aspects, even if each pulverizer 31 in the pulverizer group 3 is uniformly distributed over the cross section of the kiln chamber 1, accurate and uniform heat supply to the limestone kiln cannot be ensured.

[00103] For this reason, the cross section of the furnace chamber 1 in the embodiment is successively divided into a plurality of annular heat supply zones in the radial direction. For example, in FIG. 4 the furnace chamber is successively divided into 4 annular heat supply zones distributed from the inside to the outside, namely R1, R2, R3 and R4, with the zone R1 located in the center of the cross section of the furnace chamber 1 and the zone R4 located at the edge of the cross section of the furnace chamber 1 As shown in FIG. 5, a group of nebulizers 3 comprises a plurality of nebulizer arrays, each nebulizer array being respectively disposed in one annular heat supply zone, and each nebulizer array comprising a plurality of nebulizers 31 uniformly distributed around the circumference. For example, in FIG. 5, the matrix of atomizers in the annular heat supply zone R1 contains 1 atomizer 31, the matrix of atomizers in the annular heat supply zone R2 contains 8 atomizers 31, the matrix of atomizers in the annular heat supply zone R3 contains 8 atomizers 31, the matrix of atomizers in the annular heat supply zone R4 contains 16 there are 31 nozzles, and in total there are 33 nozzles in the group of nozzles 3, i.e. N=33.

[00104] After dividing into annular heat input zones, the total amount of heat input Qi required in each annular heat input zone can be accurately determined according to the difference in the heat output amount of each zone. The amount of fuel supplied by each atomizer 31 can be finely adjusted by matching the first calorific value sensor 404, the second calorific value sensor 504, the coal gas discharge pipe control valve 403, the pulverized coal discharge pipe control valve 503, and the flow meter 311. Each nebulizer 31 in nebulizer group 3 may be pre-numbered, for example, in the form qij, where i is a serial number representing the annular heat supply zone, and j is a serial number representing the nebulizer in the matrix of nebulizers in this zone, for example, the nebulizer number q23 in zone R2 is identified as nozzle number three in the second annular heat input zone (R2), which facilitates accurate recognition and control of each nozzle 31.

[00105] Taking the nozzle number q23 in the annular heat supply zone R2 as an example, then the total heat input in the annular heat input zone R2 is Q ₂ , and the matrix of nozzles in the zone R2 includes 8 nozzles 31, then, on average , the amount of heat supplied by each atomizer 31 is S ₂ =Q ₂ /8. The first calorific value sensor 404 is used to measure the specific calorific value of coal gas h ₁ and the second calorific value sensor 504 is used to measure the specific calorific value of pulverized coal h ₂ . When the atomizer number q23 supplies coal gas as a fuel, the amount of fuel supplied is T ₂₃ =S ₂ /h ₁ , so the opening degree of the control valve of the coal gas outlet pipe 403 corresponding to the atomizer q23 is adjusted so that the measured value S ₂₃ flow meter 311 atomizer q23 could be consistent with the value of T ₂₃ . If the atomizer number q23 supplies pulverized coal as a fuel, the amount of fuel supplied is T ₂₃ =S ₂ /h ₂ , thus the opening degree of the control valve of the pulverized coal supply pipe 503 corresponding to the atomizer q23 is adjusted to be able to match the measured value S ₂₃ by the flow meter 311 sprayer q23 with the value of T ₂₃ . From this, it can be seen that according to the proposed solution, the amount of fuel supply required for each atomizer 31 can be precisely determined according to the difference in the heat output amount of each annular heat supply zone, so that the productivity of the limestone kiln is improved and an accurate and uniform heat supply. In practical application, the limestone kiln according to the embodiment may further comprise a computer control unit configured to execute the program steps described in the second embodiment below.

[00106] The second embodiment of the proposed solution specifically provides a method for supplying heat to a limestone kiln implemented for the limestone kiln of the first embodiment. The method includes the program steps listed below.

[00107] Step S101, when the pressure difference between the first pressure sensor and the second pressure sensor is greater than or equal to the minimum furnace inlet pressure, the N pulverized coal outlet pipe control valves are closed and the N coal gas outlet pipe control valves are opened, so that all N atomizers supply coal gas fuel to the furnace chamber.

[00108] The pressure P1 in the annular coal gas supply pipe is detected by the first pressure sensor 405, and the pressure inside the furnace chamber P2 is detected by the second pressure sensor 11, the pressure difference being ΔP=P1-P2. The pressure drop ΔP is a key parameter for assessing whether the pressure of the coal gas satisfies the supply condition to the furnace. It is then judged whether the pressure difference ΔP is greater than or equal to the minimum furnace inlet pressure ΔPmin. If the value of ΔP is greater than or equal to the value of ΔPmin, the pressure of the coal gas satisfies the furnace supply condition, and the coal gas heat supply mode is preferably started. The coal gas heat supply mode is that all N control valves of the coal gas discharge pipe 503 are in the closed state, and all N control valves of the coal gas discharge pipe 403 are in the open state.

[00109] Step S102, calculating the average amount of coal gas supply Wij from each nozzle in the annular heat supply zone, and adjusting the opening degree of each control valve of the coal gas supply bypass pipe to match the value Sij measured by the flow meter with the average amount of coal gas supplied Wij.

[00110] In the coal gas heat supply mode, all N nozzles 31 supply coal gas to the furnace chamber 1, respectively, the fuel medium of each nozzle is the same. The average amount of supplied coal gas Wij from each nozzle in the annular heat supply zone is calculated by the following formula:

j

X_i, 1

i

Y, Y - количество кольцевых зон подвода тепла. Для зон подвода тепла, разделенных как показано на рис. 5, в зоне R1 количество распылителей X₁=1, в зоне R2 количество распылителей Х₂=8, в зоне R3 количество распылителей Х₃=8, в зоне R4 количество распылителей Х₄=16.[00111] Qi is the total amount of heat supplied to the annular heat supply zone, X _i is the number of atomizers included in the annular heat supply zone, h ₁ is the specific calorific value of coal gas measured by the first calorific value sensor, 1

j

X _i , 1

i

Y, Y - the number of annular zones of heat supply. For heat supply zones divided as shown in fig. 5, in zone R1, the number of nozzles X ₁ =1, in zone R2, the number of nozzles X ₂ =8, in zone R3, the number of nozzles X ₃ =8, in zone R4, the number of nozzles X ₄ =16.

[00112] The total amount of heat Q _i supplied to the annular heat supply zone is:

[00113] In the formula, Q1 is the total amount of heat supplied to the first annular heat input zone, with the first annular heat input zone located in the center of the cross section of the furnace chamber; Q is the theoretical amount of heat input required during firing of the material at a certain height of the cross section of the furnace chamber; δ is the heat transfer coefficient between the flue gas and the material in the limestone kiln; k _1i - coefficient of proportionality of the heat supply between the first annular heat supply zone and the i-th annular heat supply zone. Since the first annular heat input zone (R1) is located in the center of the cross section of the furnace chamber 1 with a minimum amount of heat output, it is preferable to use it as a reference zone for calculating the total heat input Qi of other annular heat input zones where i is greater than 1.

[00114] For the four annular heat input zones shown in FIG. 4, namely R1-R4, the total amount of heat supplied to each zone is respectively calculated by the following formula:

[00115] In the formula, k ₁₂ is the coefficient of proportionality of the heat input between the zones R1 and R2. Since the zones R1 and R2 differ in position and amount of heat transfer in the cross section of the furnace chamber, the total amount of heat input required for each of them is different, k ₁₂ is the proportionality factor used to represent these differences, which is 1.15-1 ,3.

[00116] k ₁₃ - coefficient of proportionality of heat supply between zones R1 and R3. Since the zones R1 and R3 differ in position and amount of heat transfer in the cross section of the furnace chamber, the total amount of heat input required for each of them is different, k ₁₃ is the proportionality factor used to represent these differences, which is 1.3-1 ,5.

[00117] k ₁₄ - coefficient of proportionality of the heat supply between the zones R1 and R4. Since the zones R1 and R4 differ in position and in the amount of heat transfer in the cross section of the furnace chamber, the total amount of heat input required for each of them is different. k ₁₄ is the proportionality factor used to represent these differences, which is 1.5-1.75.

[00118] After calculating the average amount of coal gas supply Wij from each nozzle in the annular heat supply zone, the opening degree of the coal gas discharge pipe control valve 403 corresponding to each nozzle 31 in the annular zone can be synchronized to match the measured value Sij by the flow meter of each nebulizer 31 with a value of Wij, which will provide fine adjustment of the heat input in the mode of heat input using coal gas. It should be noted that the method of dividing the annular heat supply zone is not limited to the embodiment and FIG. 4, so that the factor k1i can be selected according to the specific zone division method. In other possible embodiments, the corresponding annular heat input zone in the central part or along the edge of the cross section of the furnace chamber can also be used as a reference zone to obtain a differential proportionality factor between the reference zone and other annular heat input zones.

[00119] Step S103, when the pressure difference is less than the minimum furnace inlet pressure, the switching number Nm is calculated; Nm is the theoretical number of atomizers needed to switch the fuel medium.

[00120] After starting the coal gas heat supply mode, it is necessary to determine in real time whether the pressure difference ΔP is greater than or equal to the minimum furnace inlet pressure ΔPmin. If the pressure difference ΔP is greater than or equal to ΔPmin, the coal gas pressure satisfies the furnace entry condition, and the current state of coal gas supply is maintained; if the pressure difference ΔP is less than the minimum furnace inlet pressure ΔPmin, this indicates that the pressure in the coal gas network is not enough to support the furnace inlet, and it is necessary to partially or completely switch the fuel medium in the atomizer 31 from coal gas to pulverized coal.

[00121] In addition, when the coal gas pressure does not satisfy the furnace entry condition, the maximum number of coal gas nozzles Nq allowed in the nozzle group 3 at the current pressure P1 of the coal gas supply ring pipe can be calculated according to the pressure difference ΔP, and a difference value between the total number of nozzles N included in the nozzle group 3 and the maximum number of coal gas nozzles Nq is calculated to calculate the switching number Nm, that is, Nm=N-Nq.

[00122] According to the theory of hydromechanics, the pressure drop in the pipe for supplying coal gas is calculated by the formula (a):

[00123] In formula (a), ρ is the density of the coal gas; ν _t - the flow rate of coal gas in the annular pipe for supplying coal gas; ν _i - calculated flow rate of coal gas sprayer; h _t is the coefficient of resistance of the annular pipe for supplying coal gas; h _i - coefficient of resistance of the outlet pipe for supplying coal gas. In the heat supply apparatus of the limestone kiln, since the flow rate of coal gas is large, more than 20 m/s, in operation, the liquid in the pipe is in a zone of excessive turbulence. Under such conditions, h _t and h _i are two constants, independent of the flow rate of coal gas.

[00124] Because the geometric size and the like of each nozzle 31 is the same, the flow rate of the coal gas of each nozzle 31 is the same. The flow rate ν _t of coal gas in an annular coal gas supply pipe can be calculated from the following formula (b):

[00125] Thus, the following can be additionally obtained:

[00126] The maximum number of charcoal gas nozzles Nq allowed in the nozzle group 3 can be obtained from the formula (c) as follows:

[00127] Applicant has found in practice that, unlike other incinerators, the atomizer 31 of the lime kiln is generally positioned to be submerged in a layer of limestone material. The fuel burns directly in the material layer, which means that when the fuel is ejected from the atomizer 31, it is necessary not only to overcome the resistance of the pipeline, but also to overcome the resistance of an additional layer of material. The resistance of the material layer to the fuel is related to the particle size and porosity of the material under the atomizer 31. In the operating condition of the limestone kiln, the material in the atomizer 31 is a mixture of limestone raw material and calcium oxide powder, so it is difficult to accurately calculate the appropriate resistance value. In order to ensure that the flow rate at which the fuel is injected from the atomizer 31 is not less than the design requirements, the formula (d) of the embodiment is multiplied by one correction factor α relating to the particle size of the limestone material. In particular, this is shown in formula (e), where the values of the correction factor α, obtained on the basis of practical production experience, are less than 1.

[00128] In this case, the correction factor is related to the particle size of the limestone material, and the specific value of the correction factor can be indicated as shown in the following table 1.

[00129] Since Nq can only be an integer, and to ensure that the flow rate of coal gas in the atomizer is not less than the design requirements, the value of Nq calculated by formula (e) is rounded down to obtain formula (e):

[00130] The maximum number of carbon gas nozzles Nq allowed in the nozzle group 3 is calculated by formula (f), and then the theoretical switching number Nm is calculated by the formula Nm=N-Nq.

Nx

N.[00131] Step S104, the Nx coal gas discharge pipe control valves are closed and, accordingly, the Nx pulverized coal discharge pipe control valves are opened, so that the fuel supplied by the Nx atomizers in the atomizer group is switched from coal gas to pulverized coal. Nx is the actual number of atomizers needed to switch the fuel medium and Nm

Nx

N.

[00132] In the course of operation in the coal gas heat input mode, if it is found that the pressure difference ΔP is less than the minimum furnace inlet pressure ΔPmin, it is necessary to calculate the theoretical switching number Nm, then Nx of the control valves of the coal gas discharge pipe 403 in the coal gas supply device are closed, and Nx control valves of the pulverized coal supply outlet pipe 503 in the pulverized coal supply device are opened, with Nx greater than or equal to Nm. Thus, the fuel medium in at least Nm nozzles 31 in nozzle group 3 is switched from raw coal gas to pulverized coal, while ensuring that the coal gas in other N-Nx nozzles 31 in nozzle group 3 can be injected into the furnace chamber. 1 at a flow rate not less than required by design, thereby automatically switching the fuel medium in said atomizer 31 in accordance with the pressure of the coal gas. Thus, based on the above optimization of heat supply using only coal gas, according to the invention, stable operation of the limestone kiln under the low pressure of coal gas can be ensured, furthermore, sufficient supply of the fuel medium to the kiln chamber is ensured, production stability is improved, and technological adaptability of the limestone kiln, simplifies the continuous high-efficiency production of the lime kiln, and improves the productivity of the lime kiln.

[00133] However, in the embodiment in which different fuels are used to provide combined heat input, when part of the nozzles in the nozzle group 3 supplies coal gas, and the other part of the nozzles supplies pulverized coal, due to the difference in heat supply characteristics, such as intensity heating and operating range of various fuel media, there is a large temperature difference when heat is supplied by atomizers in different parts of the kiln chamber 1, and the temperature distribution inside the kiln chamber 1 is not uniform, which affects the product quality in the limestone kiln.

[00134] In this regard, according to the embodiment, the method further includes: pre-setting several modes of uniform heat supply in accordance with the total number of nozzles N included in the group of nozzles 3, and the distribution of each nozzle 31 over the cross section of the furnace chamber 1. Mode uniform heat supply is designed to indicate the position of the atomizer required to switch the fuel medium, and the actual number Nx of the atomizer in the atomizer group 3, when N _m is within the specified range of values. The target mode of uniform heat supply is determined corresponding to the range of values in which Nm is located, and then the fuel medium in Nx atomizers in the corresponding positions is switched from coal gas to pulverized coal in accordance with the target mode of uniform heat supply.

[00135] When multiple uniform heat input modes are predetermined, it is first necessary to determine the uniform heat input threshold Ny. The uniform heat input threshold Ny can be determined according to the total number of nozzles N and the distribution of each nozzle over the cross section of the furnace chamber, etc. When Nm is larger than Ny, the uniformity of the temperature distribution in the furnace chamber cannot be ensured if a combined heat supply using coal gas and pulverized coal is applied.

[00136] When the range of values is (Ny, N], Nx is N, the uniform heat supply mode is pulverized coal supply.

Ny, режим равномерного подвода тепла представляет собой комбинированный подвод тепла с применением угольного газа и пылевидного угля.[00137] When the range of values is (0, Ny], 0 Nx

Ny, the uniform heat supply mode is a combined heat supply using coal gas and pulverized coal.

[00138] When the value range is 0, Nx is 0, the uniform heat supply mode is the supply of coal gas.

[00139] FIG. 5 shows, by way of example, a nebulizer group 3 comprising thirty-three nebulizers 31 in an array of nebulizers, respectively arranged in four annular heat supply zones. The matrix of atomizers in the first annular heat supply zone R1 contains one atomizer 31, the matrix of atomizers in the second annular heat supply zone R2 contains eight atomizers 31, the matrix of atomizers in the third annular heat supply zone R3 contains eight atomizers 31, the matrix of atomizers in the fourth annular heat supply zone R4 includes sixteen nozzles 31, and the design allows thirty-three nozzles 31 to be evenly distributed over the cross section of the furnace chamber 1, thereby contributing to an even temperature distribution in the furnace chamber. With regard to the distribution structure of the spray group 3, the embodiment shows seven uniform heat input modes as shown in the following Table 2. heat using coal gas, uniform heat supply modes 2 to 6 are combined heat input modes using coal gas and pulverized coal, and uniform heat input mode 7 is a heat input mode using pulverized coal.

[00140] When Nm=0, this corresponds to uniform heat supply mode 1 as shown in FIG. 6(a). In uniform heat supply mode 1, the number of coal gas nozzles is 33, and the number of pulverized coal nozzles is 0, i.e. Nx=0, therefore, the heat supply mode is performed using coal gas as the only fuel medium.

[00141] When Nm=1, this corresponds to uniform heat supply mode 2 as shown in FIG. 6(b) In the uniform heat input mode 2, the number of coal gas nozzles is 32, and the number of pulverized coal nozzles is 1, i.e. Nx=1, so one pulverized coal atomizer is located at the center of the first annular heat supply zone (ie, the position of the atomizer at which the fuel medium needs to be switched).

[00142] When 1<Nm≤4, this corresponds to uniform heat supply mode 3 as shown in FIG. 6(c). In uniform heat supply mode 3, the number of coal gas atomizers is 29 and the number of pulverized coal atomizers is 4, that is, Nx=4, so the pulverized coal atomizers are spaced in the atomizer array in the second annular heat supply zone.

[00143] When Nm=5, this corresponds to uniform heat supply mode 4 as shown in FIG. 6(d). In uniform heat supply mode 4, the number of coal gas nozzles is 28, and the number of pulverized coal nozzles is 5, i. e. Nx=5. Four pulverized coal atomizers are distributed at intervals in a matrix of atomizers in the third annular heat supply zone, and a fifth pulverized coal atomizer is located in the center of the first annular heat input zone.

[00144] When 5<N _m ≤8, this corresponds to uniform heat supply mode 5 as shown in FIG. 6(e). In the uniform heat supply mode 5, the number of coal gas nozzles is 25, and the number of pulverized coal nozzles is 8, i.e. Nx=8. The pulverized coal atomizers are all eight atomizers in the atomizer array in the second annular heat input zone.

[00145] When Nm=9, this corresponds to uniform heat supply mode 6 as shown in FIG. 6(f). In the uniform heat supply mode 6, the number of coal gas nozzles is 24 and the number of pulverized coal nozzles is 9, i. e. Nx=9. Eight pulverized coal nozzles are all nozzles in the matrix of nozzles in the third annular heat supply zone, and the ninth pulverized coal nozzle is located in the center of the first annular heat input zone.

33, то есть Nm больше, чем пороговое значение равномерного подвода тепла Ny, это соответствует режиму 7 равномерного подвода тепла, как показано на фиг. 6 (g). В режиме 7 равномерного подвода тепла количество распылителей угольного газа составляет 0, а количество распылителей пылевидного угля равно 33, то есть Nx=33. Когда давление угольного газа слишком низкое, максимальное количество распылителей угольного газа Nq, разрешенное в группе распылителей 3, мало, и в случае включения режима комбинированного подвода тепла с применением угольного газа и пылевидного угля, однородность температуры в камере печи 1 не может быть обеспечена, поэтому выбирается режим подвода тепла с применением только пылевидного угля в качестве единственной топливной среды.[00146] When 9<N _m

33, that is, Nm is greater than the uniform heat input threshold Ny, this corresponds to the uniform heat input mode 7 as shown in FIG. 6(g). In the uniform heat supply mode 7, the number of coal gas nozzles is 0 and the number of pulverized coal nozzles is 33, that is, Nx=33. When the charcoal gas pressure is too low, the maximum number of charcoal gas nozzles Nq allowed in the 3 nozzle group is small, and if the combined heat supply using coal gas and pulverized coal is turned on, the temperature uniformity in the furnace chamber 1 cannot be ensured, so the heat supply mode is selected using only pulverized coal as the only fuel medium.

[00147] It should be noted that the embodiment and FIG. 6 show alternate modes of uniform heat input when 33 nozzles are distributed according to FIG. 5. For different distribution configurations of atomizer groups, the uniform heat supply threshold can be determined adaptively according to actual conditions, and the appropriate uniform heat supply mode can be set, which is not limited to the present application.

[00148] In order to facilitate uniform heat mode control, in other alternative embodiments, the method further includes: pre-labeling each atomizer in a group of atomizers; and establishing an appropriate relationship between the range of Nm values and the set of nozzles in the matrix to achieve a uniform heat supply mode, while the set of nozzles in the matrix contains Nx marked nozzles included in the group of nozzles that require switching the fuel medium. For example, as shown in FIG. 5, each atomizer can be labeled sequentially according to the distribution of the atomizer array, the atomizer matrix in the first annular heat supply zone is numbered q11, the atomizers in the second annular heat input zone are labeled q21-q28 in clockwise order, the atomizers in the third annular zone the heat inputs are labeled q31-q38 clockwise in sequence, and the atomizers in the fourth annular heat input zone are labeled q41-q416 clockwise.

[00149] According to the example shown in FIG. 6, the uniform heat supply mode can be expressed as follows:

[00150] uniform heat supply mode 1 is the corresponding ratio between Nm=0 and {empty set};

[00151] uniform heat supply mode 2 is the corresponding ratio between Nm=1 and {q11};

[00152] uniform heat supply mode 3 is the corresponding relationship between 1<N _m ≤4 and {q21, q23, q25, q27};

[00153] uniform heat supply mode 4 is the corresponding ratio between Nm=5 and {q11, q31, q33, q35, q37};

[00154] uniform heat supply mode 5 is the corresponding relationship between 5<N _m ≤8 and {q21, q22, q23, q24, q25, q26, q27, q28};

[00155] uniform heat supply mode 6 is the corresponding ratio between N _m =9 and {q11, q31, q32, q33, q34, q35, q36, q37, q38};

[00156] uniform heat supply mode 7 is the corresponding relationship between 9<N _m ≤33 and {universal set}.

[00157] For example, when Nm=3, uniform heat supply mode 3 is started. The corresponding set of nozzles in the matrix is defined as {q21, q23, q25, q27}, the charcoal gas discharge pipe control valves 403 corresponding to the nozzles designated q21, q23, q25, and q27 in nozzle group 3 are closed, and the discharge pipe control valves for pulverized coal supply 503 corresponding to the nozzles marked q21, q23, q25 and q27 in nozzle group 3 are opened so that the fuel medium in the nozzles marked q21, q23, q25 and q27 switches from coal gas to pulverized coal, and the nozzles, corresponding markings not included in the set of nozzles in the matrix {q21,q23,q25,q27} continue to transport coal gas.

[00158] Step S105, calculating the fuel supply amount T _ij for each atomizer in the annular heat input zone, and adjusting the opening degrees N _x of the pulverized coal discharge pipe control valve and the other NN _x coal gas discharge pipe control valve to match the measured flow meter value S _ij with value T _ij .

[00159] Based on the method for calculating the total amount of heat input Qi in each annular heat input zone shown in step S102, the fuel supply amount T _ij of each atomizer in the annular heat input zone is calculated by the following formula, in which the fuel is coal gas or pulverized coal:

j

X_i, и 1

i

Y.[00160] In the formula, Mi is the average amount of heat supplied by each atomizer in the annular heat supply zone; Qi is the total amount of heat input in the annular heat supply zone; Xi is the number of atomizers included in the annular heat supply zone; h=h2 for nozzles corresponding to Nx pulverized coal outlet pipe control valves when open; h=h1 for nozzles corresponding to other N-Nx charcoal gas outlet pipe control valves when open; where h1 is the specific calorific value of coal gas measured by the first calorific value sensor, h2 is the specific calorific value of pulverized coal measured by the second calorific value sensor, 1

j

X _i , and 1

i

Y.

[00161] The above uniform heat input mode 4 is taken as an example for illustration, wherein the uniform heat input mode 4 indicates the position of the atomizer at which the fuel medium is to be switched and the actual number of atomizers Nx, and Nx=5, with 5 atomizers supplying pulverized coal into the furnace chamber. The amount of fuel Tij supplied to 5 nozzles (numbered q11, q31, q33, q35, q37, respectively) at the respective positions, that is, the amount of pulverized coal supplied, is calculated. When the amount of fuel supplied to the atomizer q11 is T11, the opening degree of the pulverized coal discharge pipe control valve 503 corresponding to the atomizer q11 is adjusted so that the value S11 of the atomizer q11 measured by the flow meter matches the value of T11. The pulverized coal flows of the sprayers q31, q33, q35 and q37 are regulated in a similar way. Meanwhile, for other N-Nx atomizers that are not in the {q11, q31, q33, q35, q37} atomizer set such as q32, its fuel is still coal gas. The fuel supply amount is calculated as T32, namely, the coal gas supply amount, and the opening degree of the coal gas discharge pipe control valve 403 corresponding to the atomizer q32 is adjusted so that the atomizer q32 measured value S32 of the atomizer q32 corresponds to the value of T32. Similarly, the flow of coal gas of the other N-Nx-1 nebulizer is controlled so that the entire group of nebulizers 3 provides accurate heat to the furnace chamber 1.

[00162] Step S106, opening the combustion air shut-off valve and increasing the operating frequency of the combustion air supply fan to match the amount of combustion air entering the furnace with the total amount of fuel, and ending the switching mode.

[00163] When the fuel flow of each atomizer 31 in atomizer group 3 is fully adjusted, the operating frequency of the combustion air supply fan 2 is increased to start the combustion air supply fan 2. The combustion air shut-off valve 22 is opened so that combustion air enters the internal the cavity of the furnace chamber 1 through the combustion air supply pipe 21, while the amount of combustion air coincides with the total amount of fuel supplied by N nozzles in the nozzle group 3, after which the fuel switching process of the nozzle group 3 is completed. Limestone in the kiln chamber 1 can be fired to obtain the finished product - lime.

[00164] According to the embodiment, based on the fact that the coal gas supply is preferable, according to the invention, stable operation of the limestone kiln under the conditions of low pressure of coal gas, sufficient supply of the fuel medium to the furnace chamber, and switching of the fuel medium to limestone kiln, so that the production stability and process adaptability of the limestone kiln are improved, and the continuous and highly efficient performance of the limestone kiln is achieved. In addition, according to the diagram, the cross section of the limestone kiln is divided into several heat input zones along the radial direction, and the total amount of heat input required for each heat input zone is determined according to the difference in the amount of heat dissipation of each heat input zone, and the like. , so that the amount of fuel needed for each independent atomizer is accurately calculated, and accurate heat supply is realized, materials at different positions on the same horizontal cross section of the kiln chamber are evenly heated, overburning or underburning of limestone is prevented, and the quality of the limestone calcination product is improved . Thus, the scheme can significantly improve the performance of the limestone kiln.

[00165] As shown in FIG. 7-9, Embodiment 3 discloses another limestone kiln based on the limestone kiln structure of Embodiment 1, the fuel supply device further comprises N fuel switches 6, where the fuel switches 6 correspond to identical atomizers 31. FIG. 7-9 shows the connection diagram of only one group of fuel switch 6 and atomizer 31, and the connection diagram of the remaining N-1 groups of fuel switch 6 and atomizers 31 is identical, so these circuits are not shown in the figures. The fuel switch 6 is used to combine and separate the coal gas supply device 4 and the pulverized coal supply device 5, ensuring that the fuel in the limestone kiln is switched from coal gas to pulverized coal and from pulverized coal to coal gas, and ensuring that there is no mixed flow between coal gas and pulverized coal in a lime kiln. The limestone raw material is loaded into the kiln chamber 1 through the distributor 8, the atomizer 31 is used to spray the switchable fuel (coal gas or pulverized coal) into the kiln chamber 1, and then the combustion air cut-off valve 22 is opened, so that the combustion air transported by the fan to supply air combustion 2 enters the kiln chamber 1 through the combustion air supply pipe 21, and the fuel is burned to supply heat for burning limestone to produce finished lime.

[00166] Each fuel switch 6 includes a coal gas supply inlet 61, a pulverized coal supply inlet 62, and a fuel supply outlet 64, wherein the coal gas supply inlet 61 is in communication with the coal gas supply outlet pipe 402, the pulverized coal supply inlet 62 communicates with the pulverized coal supply discharge pipe 502, the fuel supply outlet 64 communicates with the feed inlet end of the atomizer 31, the coal gas supply inlet 61 and the pulverized coal supply inlet 62 are respectively provided with housings valves 65. The coal gas supply device 4 further comprises a coal gas supply fan 406, which communicates with the annular coal gas supply pipe 401 through a coal gas transport pipeline 407 provided with a coal gas shut-off valve 408. The pulverized coal supply device 5 further comprises m is a pulverized coal supply fan 505 which communicates with an annular pulverized coal supply pipe 501 through a pulverized coal conveyance line 506 provided with a pulverized coal shut-off valve 507.

[00167] In the coal gas supply pipe, the coal gas supply fan 406, the coal gas transport pipeline 407, and the annular coal gas supply pipe 401 form the main coal gas supply pipe. The N coal gas supply lines are formed by annular coal gas supply pipes 401, and the coal gas supply line includes a coal gas discharge pipe 402, a fuel switch 6, and an atomizer 31 arranged in series with each other. When the coal gas shut-off valve 408 is in the open state and the coal gas supply fan 406 operates in the standard mode, coal gas can pass through the main coal gas supply pipe and the N coal gas supply lines, so that the coal gas is transported to the furnace chamber 1. When the coal gas shut-off valve 408 is in the closed state and the operating frequency of the coal gas supply fan 406 is below the operational state, the entire coal gas supply pipe is shut off and no more coal gas is supplied to the furnace chamber 1.

[00168] Similarly, in the pulverized coal supply pipe, the pulverized coal supply fan 505, the pulverized coal conveyance line 506, and the annular pulverized coal supply pipe 501 form the main pulverized coal supply pipe. The N pulverized coal supply lines are formed by annular pulverized coal supply pipes 501, and the pulverized coal supply line includes a pulverized coal supply outlet pipe 502, a fuel switch 6, and an atomizer 31 arranged in series with each other. When the pulverized coal shut-off valve 507 is open and the pulverized coal supply fan 505 operates in the standard mode, the pulverized coal can pass through the main pulverized coal supply pipe and the N pulverized coal supply lines, so that the pulverized coal is transported to the furnace chamber 1. When the pulverized coal shut-off valve 507 is in the closed state and the operating frequency of the pulverized coal supply fan 505 is lower than the operational state, the entire pulverized coal supply pipe is shut off, and no more pulverized coal is supplied to the furnace chamber 1.

[00169] Referring to FIG. 9, using the pulverized coal supplied by the atomizer 31 to the furnace chamber 1 as an example, the operation of the fuel switch 6 is explained. that the pulverized coal cannot enter from the pulverized coal discharge pipe 502 into the coal gas supply pipe through the coal gas inlet 61, thereby preventing the pulverized coal and coal gas from mixing. At this point, only the pulverized coal supply inlet 62 communicates with the fuel outlet 64, and the pulverized coal enters from the pulverized coal supply inlet 62, passes through the fuel outlet 64, and enters the atomizer 31. At the same time, , only the coal gas supply inlet 61 or the pulverized coal supply inlet 62 communicates with the fuel outlet 64, thereby isolating the pulverized coal from the coal gas. The valve body 65 may be a solenoid or flow control valve body of other types and designs, which is not limited to use.

[00170] Since the cross-sectional area of the fuel switch 6 is larger than the diameter of the corresponding inlet (coal gas inlet 61, pulverized coal inlet 62, and nitrogen inlet 63), a small amount of fuel may exit the outlet to supply fuel 64, which may result in residual fuel in the fuel switch 6. In addition, since the fuel supply outlet 64, atomizer 31 and furnace chamber 1 communicate with each other, it is also possible that fuel from the furnace chamber 1 flows back into fuel switch 6. For example, when it is required to switch the fuel in the limestone kiln from coal gas to pulverized coal, since residual coal gas may remain in the fuel switch 6, when the valve body 65 on the pulverized coal supply inlet 62 is opened, the residual coal gas can enter the pulverized coal supply pipe and from the pulverized coal supply inlet 62, resulting in mixing of the coal gas and pulverized coal streams, i. e. there is no effective isolation and separation of coal gas and pulverized coal. On the one hand, if the mixed flow of coal gas and pulverized coal enters the furnace chamber 1, due to the different combustion characteristics of coal gas and pulverized coal, the uniformity of the temperature distribution in the firing zone in the furnace chamber 1 may change, which will affect the quality of products in the furnace. for burning limestone; on the other hand, if pulverized coal and coal gas are mixed, an explosion may easily occur, so that there is a potential safety hazard in the production of the lime kiln.

[00171] In this regard, in the preferred scheme of the embodiment, the fuel supply device further includes a nitrogen purge device 7, containing a compressed nitrogen reservoir 71 and an annular nitrogen supply pipe 72, while the annular nitrogen supply pipe 72 is in communication with N outlets. nitrogen supply pipes 73, which are equipped with nitrogen supply discharge pipe control valves 74, respectively, the compressed nitrogen tank 71 and the nitrogen supply ring pipe 72 are connected through the nitrogen transport pipeline 75, on which the nitrogen shut-off valve 76 is installed. The fuel switch 6 is optional includes a nitrogen supply inlet 63 which communicates with a nitrogen supply outlet pipe 73, wherein a valve body 65 is provided on the nitrogen supply inlet 63, and only a coal gas supply inlet 61, a pulverized coal supply inlet 62 or the nitrogen inlet 63 communicates with the outlet fuel inlet 64 at the same time by adjusting each valve body 65. When the nitrogen shut-off valve 76 and the valve body 65 at the nitrogen inlet 63 are opened, the residual coal gas or pulverized coal in the fuel switch 6 is blown with nitrogen into the atomizer 31.

[00172] In the nitrogen supply pipe, the compressed nitrogen tank 71, the nitrogen transport pipeline 75, and the nitrogen supply ring 72 constitute the main nitrogen supply pipe, the N nitrogen supply lines are formed by the nitrogen supply ring 72, and the nitrogen supply line comprises nitrogen supply outlet pipe 73, fuel switch 6 and atomizer 31 arranged in series to each other. When the nitrogen shut-off valve 76 is in the open state, nitrogen flows through the main nitrogen supply pipe and N nitrogen supply lines, the valve body 65 at the nitrogen supply inlet 63 in the N fuel switches 6 is opened, the residual fuel in the fuel switch 6 is blown into the nozzles 31 with nitrogen, and the fuel is supplied to the furnace chamber 1 by the atomizer 31. After the completion of the purge, the nitrogen shut-off valve 76 and the valve body 65 at the nitrogen supply inlet 63 are closed, the entire nitrogen supply pipe is closed, the preliminary steps in the switching process are completed, and fuel can be switched to coal gas or pulverized coal. Since nitrogen is an inert gas and is not flammable, fuel is blown into the furnace chamber 1 while absorbing nitrogen so that combustion of the fuel is not affected and the risk of explosion is prevented. By accommodating the nitrogen purge device 7, an efficient separation of pulverized coal and coal gas is achieved, and the production safety of the limestone kiln is improved.

[00173] In the preferred scheme of the embodiment, as shown in FIG. 10, the embodiment also provides a special design for the valve body 65. Unlike a motorized control valve, the valve body 65 includes a rigid O-ring 651, a sealing plug 652, and a return spring 653. A fixed support steel body 66 is provided at the center inside the fuel selector. 6. A rigid sealing ring 651 is fixed around the circumference of the coal gas inlet 61, the pulverized coal inlet 62, and the nitrogen inlet 63, respectively. One end of the return spring 653 is connected to the supporting steel body 66, and the other end of the return spring 653 is connected to the seal plug 652. 65 is closed. When the seal plug 652 is subjected to pressure from outside the fuel switch 6, the return spring 653 is compressed and the seal plug 652 and the rigid seal ring 651 are separated so that the valve body 65 is in the open state.

[00174] Taking the pulverized coal supplied by the atomizer 31 to the furnace chamber 1 as an example, the air conveying the pulverized coal from the pulverized coal discharge pipe 502 exerts a certain pressure, and when it passes through the pulverized coal supply inlet 62 , the seal plug 652 is pushed outwards and the return spring 653 is compressed so that the pulverized coal supply inlet 62 opens and communicates with the fuel supply outlet 64. It will be understood that the seal plug 652 in the valve body 65 at the fuel inlet The pulverized coal conveying air pressure 62 is affected by the pressure of the pulverized coal conveying air through the pulverized coal supply discharge pipe 502, the air pressure being dependent on the pressure outside the fuel switch 6. When the pulverized coal conveying air enters the inside of the fuel switch 6 from the pulverized coal supply inlet 62, air pressure, transporting the pulverized coal will cause the sealing plug 652 on the coal gas inlet 61 and the nitrogen inlet 63 to be firmly pressed against the rigid sealing ring 651, thereby sealing the coal gas inlet 61 and the nitrogen inlet 63 The sealing plugs 652 on the coal gas inlet 61 and the nitrogen inlet 63 are pressurized from within the fuel switch 6.

[00175] The supporting steel housing 66 is located in the center of the fuel switch 6 and is fixed in this position. One end of the return spring 653 is connected to the support steel body 66, the other end of the return spring 653 is connected to the seal plug 652, which can move when the return spring 653 expands and contracts. When fuel is applied, the return spring 653 returns to its original position to firmly press the seal plug 652 to the rigid sealing ring 651 so that the opening and closing of the coal gas inlet 61, the pulverized coal inlet 62, and the nitrogen inlet 63 is controlled to prevent mutual communication between each inlet. A rigid O-ring 651 is located around each inlet, the diameter of the rigid O-ring 651 is slightly larger than the diameter of the inlet, and the seal plug 652 must be larger than the diameter of the rigid O-ring 651 to ensure that each inlet is sealed. If the hard sealing ring 651 is missing, the sealing plug 652 directly blocks the inlet of the fuel switch 6, so that the sealing performance of the surface seal is low. The rigid seal ring 651 is pressed by the seal plug 652 so that the valve body 65 has a good seal and a fuel switching effect is obtained. The valve body shown in Fig. 10 has a simple structure, which can reduce the cost of limestone kiln equipment. The opening and closing of the valve body 6 can be controlled automatically by spontaneously sensing the pressure inside and outside the fuel switch 6 without sending an electrical control signal for control, so that the sealing performance and the driving efficiency of the valve body 65 are improved.

[00176] When the fuel in the furnace chamber 1 flows back, the fuel can flow inside the fuel switch 6 through the fuel supply outlet 64, and at the same time, the sealing plugs 652 of the valve bodies 65 on the coal gas supply inlet 61, the inlet for the pulverized coal supply 62 and the nitrogen supply inlet 63 are subjected to pressure from within the fuel switch 6. All three valve bodies 65 can be closed by matching with the return spring 653, and the three fuel switch inlets 6 are well sealed, so that the fuel will not flow back into the coal gas outlet pipe 402, the pulverized coal outlet pipe 502, and the nitrogen outlet pipe 73. When switching, the fuel flowing back and remaining inside the fuel switch 6 is re-blown into the atomizer 31 by the device purge with nitrogen 7 and is injected back into the furnace chamber 1 with atomizer 31 .

[00177] When a fuel switch is performed, such as a fuel switch from coal gas to pulverized coal, that is, when the coal gas shut-off valve 408 is closed, the main coal gas pipe is closed, and the coal gas supply fan 406 cannot suddenly stop working, and the working the frequency is gradually reduced to an operational state, so that the pressure in the coal gas conveying pipeline 407 between the coal gas shut-off valve 408 and the coal gas supply fan 406 increases, thereby affecting the safety of the coal gas supply pipe. The same problem exists for the pulverized coal supply pipe.

[00178] In this regard, in the preferred scheme of the embodiment with reference to FIG. 7, the coal gas supply apparatus 4 further includes a coal gas return line 409 on which a coal gas check valve 410 is mounted. 409 is in fluid communication with the coal gas transport pipeline 407, with the inlet end of the coal gas return pipeline 409 located between the coal gas shut-off valve 408 and the outlet end of the coal gas supply fan 406. When the coal gas transport check valve 410 is opened, the air conveying the coal gas can circulate between the coal gas return pipe 409 and the coal gas supply fan 406 to depressurize the coal gas supply fan 406, thereby ensuring the safety of the coal gas supply pipe.

[00179] The pulverized coal supply device 5 further includes a pulverized coal return line 508 provided with a pulverized coal check valve 509, an outlet end of the pulverized coal return line 508 communicates with an inlet end of a pulverized coal supply fan 505, an inlet end of the pulverized coal return line 508 communicates with the pulverized coal conveying line 506, with the inlet end of the pulverized coal return line 508 located between the pulverized coal shut-off valve 507 and the outlet end of the pulverized coal conveying fan 505. When the pulverized coal conveying check valve 509 is opened, the pulverized coal conveying air can the pulverized coal return pipe 508 and the pulverized coal supply fan 505 to depressurize the pulverized coal supply fan 505, thereby securing the pulverized coal supply pipe. The limestone kiln according to the third embodiment may further comprise a computer control unit configured to execute the program steps described in the fourth embodiment below.

[00180] A fourth embodiment of the proposed solution provides a method for supplying heat to a limestone kiln, which is used to construct the limestone kiln disclosed in the third embodiment. The method includes the following steps.

[00181] 1. When the pressure difference between the first pressure sensor and the second pressure sensor is greater than or equal to the minimum furnace inlet pressure, it indicates that the coal gas pressure values satisfy the furnace inlet condition, preferably starting the coal-fired heat supply mode. gas and the inclusion of all N atomizers to supply coal gas to the furnace chamber. The coal gas heat supply mode is as follows: the coal gas shut-off valve 408, the coal gas supply fan 406, and the valve body 65 at the coal gas supply inlet 61 N of the fuel switches 6 are in the open state, the pulverized coal shut-off valve 507 and valve body 65 at the pulverized coal inlet 62 N fuel switches 6 are closed, the pulverized coal fan 505 is operational, and the nitrogen shut-off valve 76 and valve body 65 at the nitrogen inlet 63 N switches fuel 6 are in the closed state; the coal gas check valve 410 is in the closed state, and the pulverized coal check valve 509 is in the open state; and N coal gas discharge pipe control valves 403, N pulverized coal discharge pipe control valves 503, and N nitrogen discharge pipe control valves 74 are in the open state. After starting the single fuel heat supply mode, each equipment in the feeder link is in the state as described above, in which case step 2 is performed to adjust the flow of coal gas of each gun 31 in the gun group 3 to ensure accurate heat supply to the lime kilns.

[00182] 2. Calculate the average amount of coal gas supply Wij for each nozzle in the annular heat supply zone, and adjust the opening degree of each control valve of the coal gas discharge pipe to match the value Sij measured by the flow meter with the value Wij. With regard to the method for finely adjusting the heat input flow described in step S202 and step S206, reference can be made to the corresponding description and illustration in Embodiment 2, which will not be described in detail in this embodiment.

[00183] 3. When the pressure drop is less than the minimum furnace inlet pressure, the switching number Nm is calculated; N _m is the theoretical number of atomizers needed to switch the fuel medium. For this step, reference may be made to the corresponding description and illustration in Embodiment 2, which will not be described in detail in this embodiment.

Nx

N.[00184] 4. Determination of the uniform heat mode to be started, wherein the uniform heat mode is used to indicate the position of the atomizer required to switch the fuel medium and the actual atomizer number Nx in the atomizer group when Nm is within the specified value range , and Nm

Nx

N.

[00185] The uniform heat input threshold Ny is determined according to the total number N of nozzles included in the group of nozzles and the distribution of each nozzle over the cross section of the furnace chamber. The distribution of each nozzle across the cross section of the furnace chamber described here includes the method of dividing the annular heat supply zone and the number of nozzles included in the matrix of nozzles, as well as the position and distribution, etc. of each nozzle in each annular heat input zone.

[00186] When the range of values is (Ny, N], Nx is equal to N, so that the even heat supply mode is pulverized coal supply.

Ny, так что режим равномерного подвода тепла представляет собой комбинированный подвод тепла с применением угольного газа и пылевидного угля.[00187] When the range of values is (0, Ny], 0<Nx

Ny, so that the mode of uniform heat supply is a combined heat supply using coal gas and pulverized coal.

[00188] When the value range is 0, Nx is 0, so that the uniform heat supply mode is coal gas supply.

[00189] The preset uniform heat supply mode and its operating mode are mentioned in the corresponding description and illustration in Embodiment 2 of the proposed solution and will not be described in detail in this embodiment. After the number of switchings Nm is calculated, the desired uniform heat supply mode can be determined according to the range of Nm.

[00190] In one possible embodiment, when Nm=Nx=0, the mode of heat supply using coal gas, which is currently used in the known limestone kiln, is maintained unchanged, that is, the state mode described in step 1 is maintained .

[00191] In another exemplary embodiment, when the uniform heat input mode is defined as pulverized coal supply, the fuel in all N atomizers needs to be switched synchronously from coal gas to pulverized coal, and in the coal gas heat input mode described above, the uniform mode heat supply is carried out as follows.

[00192] (A) The valve body 65 at the charcoal gas inlet 61 in the N fuel switches 6 and the charcoal gas shut-off valve 408 are closed in succession, the charcoal gas check valve 410 is opened at the same time, and the charcoal gas ventilator 406 is placed in the operational state . At this time, the entire coal gas supply pipe is shut off, the heat supply device no longer supplies coal gas to the furnace chamber 1, and the coal gas check valve 410 is used to depressurize the coal gas supply fan 406.

[00193] (B) The nitrogen shut-off valve 76 and the valve body 65 at the nitrogen supply inlet 63 N of the fuel switches 6 are opened in succession, and after the nitrogen blows the residual pulverized coal from the fuel switch 6 into the atomizer 31, the nitrogen purge process ends , and the valve body 65 on the nitrogen supply inlet 63 N of the fuel switches 6 and the nitrogen cut-off valve 76 are successively closed. At this time, the residual coal gas in the N fuel switches 6 is removed, so that the possibility of the pulverized coal and coal gas streams mixing in the switching process is effectively prevented. It is possible to shut off the entire nitrogen supply pipe, and prepare the next process for transporting pulverized coal to furnace chamber 1.

[00194] (C) The pulverized coal check valve 509 closes, the operation frequency of the pulverized coal blower 505 rises. When the pressure of the pulverized coal reaches the required value to enter the furnace, that is, it is possible to supply pulverized coal to the furnace chamber 1 with the atomizer 31, the pulverized coal shut-off valve 507 and the valve body 65 at the pulverized coal supply inlet 62 N of the fuel switches 6 in series are opened so that the pulverized coal passes through the pulverized coal conveying line 506, the annular pulverized coal supply pipe 501, the N pulverized coal discharge pipes 502, the pulverized coal supply inlet 62, and the fuel outlet 64 N fuel switches 6 and N nozzles 31 and, finally, enters the inner cavity of the furnace chamber 1, so that the mode of uniform heat supply starts. Thus, the fuel in the N atomizers 31 can be switched synchronously from coal gas to pulverized coal.

[00195] In yet another exemplary embodiment, when it is determined that the uniform heat mode is a combined heat input using coal gas and pulverized coal, it can be known from the uniform heat mode indication that the fuel in the atomizers in atomizer group 3 is switched from coal gas to pulverized coal, and the actual number Nx of nozzles required to switch the fuel medium can be known, that is, the fuel of some N nozzles is switched from coal gas to pulverized coal. In the aforementioned state of the coal gas heat supply mode, the uniform heat supply mode is started as follows.

[00196] (D) The pulverized coal discharge pipe control valve 503 and the nitrogen supply discharge pipe control valve 74 corresponding to the remaining N-Nx nozzles (i.e., the nozzle not indicated by a position in the uniform heat supply mode) are closed, and at the same time, the charcoal gas outlet pipe control valve 403 corresponding to the Nx atomizers (i.e., the position of the atomizer that requires fuel switching in uniform heat supply mode) is closed, and the valve body 65 at the charcoal gas inlet 61 in the fuel switch 6 in the position corresponding to the nozzles Nx is closed.

[00197] For the remaining N-Nx atomizers 31, after adjustment in step (D), the respective pulverized coal supply outlet pipe and the nitrogen supply outlet pipe are closed, and only the coal gas outlet pipe remains, so that the fuel medium sprayed by N- Nx by atomizers 31, is still coal gas, and cannot be affected by the subsequent nitrogen purge and switch to pulverized coal, and the coal gas passes through the coal gas transport pipeline 407 in series, the coal gas supply annular pipe 401, NN _x outlet pipes for supplying coal 402, the inlet for supplying coal gas 61 and the outlet for supplying fuel 64 of the N-Nx fuel switches 6 and N-Nx nozzles 31, and enters the inside of the furnace chamber 1. In N _x nozzles 31, the corresponding outlet pipe for supplying coal gas. The nitrogen supply pipe can be connected according to the next step (E) to purge the residual coal gas in the fuel switch 6 to ensure that the atomizer 31 does not blow the mixed coal gas and pulverized coal.

[00198] (E) The nitrogen shut-off valve 76 and the valve body 65 at the nitrogen supply inlet 63 of the fuel switch 6 at the position corresponding to the Nx nozzles are opened in succession, and after the nitrogen blows out the residual carbon gas from the fuel switch 6 to the nozzles 31, the valve body 65 on the nitrogen supply inlet 63 of the fuel switch 6 at the position corresponding to the Nx atomizers and the nitrogen cut-off valve 76 are successively closed. When the nitrogen shut-off valve 76 is opened, the main nitrogen supply pipe is connected. Nitrogen enters the Nx nitrogen supply lines at positions corresponding to the Nx nozzles 31 from the annular nitrogen supply pipe 72. After purging the residual carbon gas from the respective Nx fuel switches 6 to the respective nozzle 31, the nitrogen supply line can be shut off and the next one started. a step (F) in which the fuel in the Nx atomizers 31 in this position is switched from coal gas to pulverized coal.

[00199] (F) The pulverized coal check valve 509 closes, the operating frequency of the pulverized coal supply fan 505 rises, and when the pressure of the pulverized coal reaches the kiln inlet requirements, the pulverized coal shut-off valve 507 and the valve body 65 at the pulverized coal inlet coal 62 of the fuel switch 6 at the position corresponding to the Nx atomizers are sequentially opened so that the pulverized coal passes through the pulverized coal conveyance line 506, the annular pulverized coal supply pipe 501, the Nx pulverized coal discharge pipes 502, the pulverized coal supply inlet coal 62 and the fuel outlet 64 of Nx fuel switches 6 and Nx atomizers 31 and finally enters the inside of the furnace chamber 1.

[00200] In an embodiment, the coal gas supply fan 406 and the pulverized coal supply fan 505 can operate simultaneously, the pulverized coal supply fan 505 is used to transport the pulverized coal to the Nx atomizers 31 at the corresponding position, and the coal gas supply fan 406 supplies coal gas to other N-Nx nozzles 31. Since each nozzle 31 has a respective coal gas outlet pipe control valve 403, a pulverized coal outlet pipe control valve 503, and a nitrogen outlet pipe control valve 74, it is ensured that the supply device The coal gas 4 and the pulverized coal supply device 5 can supply fuel at the same time and do not interfere with each other, so that combined heat supply using coal gas and pulverized coal can be realized.

[00201] According to the above coal gas heat input mode, the coal gas and pulverized coal combined heat input mode, and the pulverized coal heat input mode in the start mode, and the method of controlling the three modes of the valve body 65 on the three inlets in fuel switch 6 may be constructed as shown in FIG. 6, like a conventional solenoid valve, etc., and can also use an induction-type automatic control valve with a special design as shown in FIG. 10, provided that the sealing, opening and closing of the three inlets inside the fuel switch 6 can be realized.

[00202] Fifth, after starting the even heat supply mode, the fuel supply amount Tij for each atomizer in the annular heat supply zone is calculated.

[00203] Sixth, the opening degree of the pulverized coal discharge pipe control valves at the positions corresponding to the Nx nozzles is adjusted, and the opening degree of the coal gas discharge pipe control valves corresponding to the other N-Nx nozzles is adjusted so that the value measured by the flow meter Sij is consistent with the value of Tij.

[00204] Seventh, opening the combustion air shut-off valve and increasing the operating frequency of the combustion air supply fan to match the amount of combustion air entering the furnace with the total amount of fuel, and ending the switching mode.

[00205] It should be noted that after the preferred start of the coal gas supply, if the pressure difference between the first pressure sensor and the second pressure sensor is less than the minimum pressure at the furnace inlet, the combined heat supply mode using coal gas and pulverized coal, or the heat input mode using coal gas. If the differential pressure is greater than or equal to the minimum furnace inlet pressure, it is necessary to determine in real time when to start the heat input mode using combined heat input. The application discloses the operating states of various equipments and valves in a heat supply apparatus in the coal gas heat supply mode, and if the coal gas pressure satisfies the furnace entry condition in the current combined heat input mode, the current heat input mode can be switched to the heat input mode. with the use of coal gas, thus reducing the cost of fuel for the limestone kiln. In addition, by adjusting the operating states of various equipments and valves in the heat supply device, mutual switching between different heat supply modes can be realized so that the actual desired heat supply effect is achieved, and the process adaptability of the limestone kiln is also improved.

[00206] In an embodiment, the combination and separation of the pulverized coal supply device and the coal gas supply device is carried out by means of a fuel switch. By controlling the opening and closing state of each valve in the limestone kiln and the working state of the fan, the fuel medium in the limestone kiln can be switched quickly, automatically and flexibly, which can realize a variety of heat supply modes, thus eliminating the disadvantages of one heat supply method and poor technological adaptability of the limestone kiln. In addition, according to the diagram, the cross section of the limestone kiln is divided into several heat input zones along the radial direction, and the total amount of heat input required for each heat input zone is determined according to the heat output difference of each heat input zone, so that the amount of fuel required for each independent atomizer is precisely calculated and implemented, in addition, accurate heat input is realized, materials at different positions on the same horizontal cross section of the kiln chamber are evenly heated, and overburning or underburning of limestone is eliminated. Therefore, the quality of the product produced in the limestone kiln is improved, and therefore the solution can greatly improve the performance of the limestone kiln.

[00207] With respect to the atomizer mentioned in the above embodiments, since the distribution range of each atomizer is limited, the fuel atomized from the atomizer is mainly located at the outlet of the atomizer. However, the fuel is not distributed in the space between the atomizers, that is, the fuel is not evenly distributed over the cross section of the furnace chamber, which results in a high temperature of the material at the outlet of the atomizer and a relatively low temperature of the material in the region between the atomizers. The speed of burning limestone on the same cross section of the kiln chamber is different, which affects the quality of the finished lime.

[00208] In this regard, as shown in FIG. 11 and 12, based on the above diagrams of various embodiments, the fifth embodiment of the present application provides a construction of the atomizer 31, including the atomizer body 3101. The atomizer body 3101 is provided with an inlet 3102 and an outlet 3103, respectively, the atomizer body 3101 includes an inner tube body 3104 and a body outer pipe body 3105, wherein the outer pipe body 3105 extends outside the inner pipe body 3104, the inner pipe body 3104 and the outer pipe body 3105 are hollow tubular structures, the inner pipe body 3104 has an internal fuel passage 3106, and the diameter of the inner pipe body 3104 is smaller than the diameter outer tube body 3105 so that an annular outer tube 3107 is formed between the inner tube body 3104 and the outer tube body 3105. direction. The group of bypass holes 3108 includes several bypass through holes 3109 evenly distributed around the circumference. In general practice, the firing process temperature in a limestone kiln is about 1100°C, the spray gun body 3101 may be made of a heat-resistant material and may be specially selected according to practical applications.

[00209] The atomizer provided in the embodiment is based on a two-channel design in which fuel (including coal gas, pulverized coal, etc.) enters from the inlet 3102, and then enters the internal fuel passage 3106 and the external fuel passage 3107 , respectively, and finally atomized through the outlet 3103 and each bypass hole 3109. The outlet 3103 is the main outlet of the atomizer body 3101 through which most of the fuel is atomized. Each bypass through hole 3109 located on the outer pipe body 3105 is equivalent to an auxiliary outlet of the atomizer body, and a small part of the fuel flowing into the outer fuel passage 3107 is atomized through the bypass through hole 3109, so that the atomization range of one atomizer is effectively increased, the fuel is distributed in the area between the atomizers, the uniformity of temperature distribution on the same cross section of the kiln chamber is ensured, and the quality of the finished lime is also increased.

[00210] In practical application, in order to facilitate the direction of material from the atomizer, the atomizer body can be divided into a horizontal section 3110, an arcuate transition section 3111, and a vertical section 3112. The horizontal section 3110 and the vertical section 3112 are connected by an arcuate transition section 3111; the inlet 3102 is located at the open end of the horizontal section 3110, namely the left end of the horizontal section 3110 in FIG. eleven; the outlet 3103 is located at the open end of the vertical section 3112, namely the lower end of the vertical section 3112 in FIG. 11, and several groups of bypass holes 3108 are located on the vertical section 3112 of the body of the outer pipe 3105. In practical application, the horizontal section 3110, the arc transition section 3111, and the vertical section 3112 may be a single structure, or, alternatively, may be connected by welding, which is not limited in this application.

[00211] As shown in FIG. 13, the existing atomizer for a limestone kiln has a distribution range only in the corresponding area S1 under the outlet, and the atomized fuel enters the area S1, so that the fuel cannot be distributed in the area between the atomizers, and the temperature distribution across the cross section of the kiln chamber is not uniform. . In the present application, after the fuel entering the outer fuel passage 3107 enters the region of the vertical section 3112, fuel will flow out of each bypass hole 3109, so that the fuel distribution range expands and becomes larger than S1. In other possible embodiments, the central axis of the inner tube body 3104 coincides with the central axis of the outer tube body 3105 so that the fuel flowing from each of the bypass through holes 3109 is distributed more evenly and symmetrically. The bypass through hole 3109 is a downwardly inclined through hole, that is, the central axis of the bypass through hole 3019 has an angle of inclination (3 with the central axis of the vertical section 3112, so that the spray range of the atomizer is S1+S2, where the value of S1 is constant and the value S2 is the maximum spray range of multiple bypass groups 3108, such as the maximum vertical height bypass group (FIG. 13) that has the maximum spray distance.The value of S2 is related to the design height and slope angle β of the bypass group 3108. The higher the height of the group of bypass holes 3108 and the larger the angle of inclination β, the greater the value of S2 and the greater the spray range of a single nozzle.Therefore, in practical application, the size of the body of the atomizer 3101, the distribution of the group of bypass holes 3108 in the vertical section 3112 and the magnitude of the angle of inclination β may be calculated according to parameters such as the number of nozzles, the distribution of nozzles, the size of the furnace chamber, etc.

[00212] According to the dual-channel atomizer provided in the embodiment, the atomization range of the atomizer is no longer limited, the fuel atomization range is increased from S1 to S1+S2, which makes it possible to distribute fuel not only under the outlet but also in the area between the atomizers to ensure more accurate and uniform fuel distribution, more uniform temperature distribution across the chamber cross-section of the limestone kiln, improved quality of finished lime, and furthermore, improved performance of the limestone kiln.

[00213] The same or similar parts in various embodiments in this description may refer to each other.

[00214] The above preferred embodiments of the present application do not limit the scope of the present invention.

Claims (78)

1. A limestone kiln, including a kiln chamber (1), a heat supply device and a combustion air supply fan (2), while a combustion air supply pipe (21) is connected between the combustion air supply fan (2) and the kiln chamber ( 1), a combustion air shut-off valve (22) is made on the combustion air supply pipe (21), the heat supply device includes a fuel supply device and a group of atomizers (3), a group of atomizers (3) is connected to the internal cavity of the furnace chamber (1), a group nozzles (3) consists of a total of N nozzles (31), characterized in that the fuel supply device includes a coal gas supply device (4) and a pulverized coal supply device (5), the coal gas supply device (4) includes an annular pipe for coal gas supply pipe (401) and N coal gas supply outlet pipes (402) connected to an annular coal gas supply pipe (401), each coal gas outlet pipe (402) connected to a supply inlet end of one atomizer (31), the pulverized coal supply device (5) includes an annular pulverized coal supply pipe (501) and N pulverized coal outlet pipes (502) connected to the annular pulverized coal supply pipe (501), and each pulverized coal supply outlet pipe (502) is connected to the supply inlet of one atomizer (31), so the coal gas supply device (4) and the pulverized coal supply device (5) share a group of atomizers (3); each coal gas outlet pipe (402) has a coal gas outlet pipe control valve (403), and each pulverized coal outlet pipe (502) has a pulverized coal outlet pipe control valve (503); atomizer (31) has a flow meter (311); the first calorific value sensor (404) and the first pressure sensor (405) are respectively located on the annular coal gas supply pipe (401), the second calorific value sensor (504) is located on the annular pulverized coal supply pipe (501), and the second pressure sensor (11) is made inside the furnace chamber (1); the cross section of the furnace chamber is sequentially divided in the radial direction into several annular heat supply zones, and the atomizer group (3) includes several atomizer arrays, each atomizer matrix is respectively located in one annular heat supply zone, and each atomizer matrix includes several atomizers (31), evenly distributed around the circumference. 2. The limestone kiln according to claim 1, characterized in that the atomizer (31) includes an atomizer body (3101), at the two ends of the atomizer body (3101) there is a supply inlet (3102) and a supply outlet (3103), respectively, atomizer body (3101) includes an inner pipe body (3104) and an outer pipe body (3105) inserted from the outer side of the inner pipe body (3104), an internal fuel channel (3106) is located inside the inner pipe body (3104), between the inner pipe body (3104) and the body of the outer pipe (3105) an annular external fuel channel (3107) is formed, on the part of the body of the outer pipe (3105), next to the supply outlet (3103), several groups of bypass holes (3108) are located at intervals in the axial direction , the group of bypass holes (3108) includes several bypass through holes (3109) evenly distributed around the circumference, and the bypass through hole (3109) is a speed down through hole. 3. The limestone kiln according to claim 1 or 2, characterized in that the fuel supply device further includes N fuel switches (6), each fuel switch (6) includes a coal gas supply inlet (61), a pulverized coal (62) and a fuel outlet (64), wherein the coal gas inlet (61) is connected to the outlet pipe for coal gas supply (402), the pulverized coal inlet (62) is connected to the outlet pipe for supplying pulverized coal (502), the outlet for supplying fuel (64) is connected to the supply inlet end of the atomizer (31), on the inlet for supplying coal gas (61) and the inlet for supplying pulverized coal (62), respectively, there are housings valves (65); the coal gas supply device (4) further includes a coal gas supply fan (406), the coal gas supply fan (406) is connected to the coal gas supply ring pipe (401) via the coal gas transport pipeline (407), and on the transport pipeline coal gas (407) is made shut-off valve of coal gas (408); the pulverized coal supply device (5) further includes a pulverized coal supply fan (505), the pulverized coal supply fan (505) is connected to the annular pulverized coal supply pipe (501) through the pulverized coal conveying pipeline (506), and on the conveying pipeline pulverized coal (506), a pulverized coal shut-off valve (507) is provided. 4. The limestone kiln according to claim 3, characterized in that the fuel supply device further includes a nitrogen purge device (7) including a compressed nitrogen tank (71) and an annular nitrogen supply pipe (72), while the supply pipe nitrogen supply (72) is connected to N discharge pipes for nitrogen supply (73), on the N discharge pipes for nitrogen supply (73) there is respectively a control valve of the discharge pipe for nitrogen supply (74), a tank for compressed nitrogen (71) and an annular pipe for the nitrogen supply (72) is connected via a nitrogen transport pipeline (75), and a nitrogen shut-off valve (76) is provided on the nitrogen transport pipeline (75); the fuel switch (6) further includes a nitrogen inlet (63), the nitrogen inlet (63) is connected to the nitrogen outlet pipe (73), a valve body (65) is formed on the nitrogen inlet (63), and only one of the coal gas inlet (61), the pulverized coal inlet (62), and the nitrogen inlet (63) is connected to the fuel outlet (64) at a time by adjusting each valve body (65) ; when the nitrogen shut-off valve (76) and the valve body (65) on the nitrogen supply inlet (63) are opened, residual coal gas or pulverized coal in the fuel switch (6) is purged with nitrogen into the atomizer (31). 5. Limestone kiln according to claim 4, characterized in that the valve body (65) includes a rigid sealing ring (651), a sealing plug (652) and a return spring (653); in the center inside the fuel switch (6) is a fixed support steel body (66); rigid sealing rings (651) are respectively fixed around the perimeter of the pipe holes of the coal gas inlet (61), the pulverized coal inlet (62), and the nitrogen inlet (63); one end of the return spring (653) is connected to the support steel housing (66), and the other end of the return spring (653) is connected to the sealing plug (652); when the seal plug (652) is pressurized from the internal cavity of the fuel switch (6), the seal plug (652) is firmly pressed against the rigid sealing ring (651), so that the valve body (65) is in the closed state; when pressure is applied to the seal plug (652) from the outside of the fuel switch (6), the return spring (653) is compressed and the seal plug (652) and the hard seal ring (651) are separated, thus the valve body (65) is in the open condition. 6. Limestone kiln according to claim 4 or 5, characterized in that the coal gas supply device (4) further includes a coal gas return pipeline (409) on which a coal gas check valve (410) is located, while the outlet end of the return coal gas pipeline (409) is connected to the inlet end of the coal gas supply fan (406), the inlet end of the coal gas return pipeline (409) is connected to the coal gas transport pipeline (407), the inlet end of the coal gas return pipeline (409) is located between the shutoff coal gas valve (408) and the outlet end of the coal gas supply fan (406), and when the coal gas check valve (410) is open, the coal gas supply air circulates between the coal gas return pipe (409) and the coal gas supply fan (406) to depressurize the coal gas blower (406). 7. The limestone kiln according to claim 6, characterized in that the pulverized coal supply device (5) further includes a pulverized coal return line (508), on which a pulverized coal check valve (509) is located, wherein the outlet end of the pulverized coal return line coal (508) is connected to the inlet end of the pulverized coal supply fan (505), the inlet end of the pulverized coal return pipeline (508) is connected to the pulverized coal transport pipeline (506), the inlet end of the pulverized coal return pipeline (508) is located between the pulverized coal shut-off valve (507) and the outlet end of the pulverized coal supply fan (505), and when the pulverized coal check valve (509) is opened, the pulverized coal supply air circulates between the pulverized coal return pipe (508) and the pulverized coal supply fan (505 ) to depressurize the pulverized coal blower (505). 8. The method of supplying heat to the limestone kiln according to claim 1 or 2, characterized in that the method includes the following steps: when the pressure difference between the first pressure sensor and the second pressure sensor is greater than or equal to the minimum furnace inlet pressure, N pulverized fuel outlet pipe control valves are closed and N coal gas outlet pipe control valves are opened, thus all N nozzles supply coal gas as fuel into the furnace chamber; calculating the average amount of coal gas supply W _ij of each nozzle in the annular heat supply zone, and adjusting the opening degree of each control valve of the coal gas discharge pipe to match the measured value S _ij of the flow meter with W _ij ; when the pressure drop is less than the minimum furnace inlet pressure, the number of switchings N _m is calculated; N _m is the theoretical number of atomizers needed to switch the fuel medium; the N _{x control valves of the coal gas outlet pipes are closed and the N x control} valves of the pulverized coal outlet pipes are respectively opened, so that the fuel supplied by the N _x nozzles in the nozzle group is switched from coal gas to pulverized coal, N _x represents is the actual number of nozzles required to switch the fuel medium, and N _m

N _x

N; the amount of fuel supplied T _ij of each atomizer in the annular heat supply zone is calculated and the opening degrees of the N _x pulverized coal outlet pipe control valves and other NN _x coal gas outlet pipe control valves are adjusted to ensure that the measured value S _ij of the flow meter corresponds to T _ij ; and the combustion air shut-off valve opens, and the operation frequency of the combustion air supply fan increases to match the amount of combustion air entering the furnace with the total amount of fuel, and the switching process is completed. 9. The method according to p. 8, characterized in that the calculation of the number of switching N _m includes: calculating the maximum number of coal gas nozzles N _q allowed in the group of nozzles at the current pressure in the annular coal gas supply pipe P ₁ in accordance with the pressure difference between the first pressure sensor and the second pressure sensor; and calculating the discrepancy value between the total number of nozzles N and the maximum number of coal gas nozzles N _q to obtain the number of switchings N _m . 10. The method according to claim 9, characterized in that the maximum number of coal gas atomizers N _q is calculated according to the formula below:

, where ρ is the density of the coal gas, ν _i is the calculated flow rate of the coal gas atomizer, h _t is the resistance factor of the coal gas supply ring pipe, h _i is the resistance coefficient of the coal gas discharge pipe, P ₁ is the pressure in the annular coal gas pipe, measured by the first pressure sensor, P ₂ is the pressure inside the furnace chamber, measured by the second pressure sensor, α is a correction factor related to the size of the limestone particles in the furnace chamber. 11. The method according to paragraphs. 8-10, characterized in that it additionally includes presetting modes of uniform heat supply in accordance with the total number of nozzles N, included in the group of nozzles, and the location of each nozzle in the cross section of the furnace chamber; the uniform heat supply mode indicates the position of the nozzles required to switch the fuel medium and the actual number of nozzles N _x in the nozzle group when N _m is within the specified value range. 12. The method according to claim 11, characterized in that after calculating the number of switching N _m , the method further includes: determination of the target mode of uniform heat supply corresponding to the range of N _m values; and switching the fuel medium of the N _x atomizers in the corresponding position from coal gas to pulverized coal in accordance with the indication of the target mode of uniform heat supply. 13. The method according to p. 11, characterized in that the method further includes: preliminary marking of each nozzle in a group of nozzles; and evaluating an appropriate relationship between a range of N _m values and a set of atomizers in a matrix to obtain a uniform heat supply mode; and the matrix atomizer set contains marks of the N _x nozzles in the matrix atomizer set requiring fuel medium switching. 14. The method according to p. 11, characterized in that the method further includes: when multiple uniform heat input modes are pre-set, determining a uniform heat input threshold value N _y ; when the range of values is (N _y , N], N _x is equal to N, therefore, the even heat supply mode is heat supply using pulverized coal; when the range of values is (0, N _y ] being 0<N _x

N _y , therefore, the uniform heat supply mode is a combined heat supply using coal gas and pulverized coal; and, when the value range is 0, N _x is 0, therefore, the uniform heat supply mode is heat supply using coal gas. 15. The method according to claim 8, characterized in that the total amount of heat input Q _i of the annular heat supply zone is

, where Q ₁ is the total amount of heat input of the first annular heat input zone, the first annular heat input zone is in the center of the cross section of the furnace chamber; Q is the theoretical amount of heat input required to fire the material at a certain cross-sectional height of the kiln chamber; δ is the heat transfer coefficient between the flue gas and the material in the limestone kiln; k _1i is the proportionality factor of the heat input between the first annular heat input zone and the i-th annular heat input zone; and Y is the number of annular heat supply zones. 16. The method according to claim 15, characterized in that the average amount of supplied coal gas W _ij of each atomizer in the annular heat supply zone is calculated according to the formula below:

, where Q _i is the total heat input of the annular heat input zone, X _i is the number of nozzles included in the annular heat input zone, h ₁ is the specific calorific value of the coal gas measured by the first calorific value sensor, 1

j

X _i and 1

i

Y. 17. The method according to claim 15, characterized in that the amount of fuel supplied T _ij of each atomizer in the annular heat supply zone is calculated according to the formula below:

, where M _i represents the average amount of heat input of each nozzle in the annular heat supply zone; Q _i is the total heat input of the annular heat input zone; X _i is the number of atomizers included in the annular heat supply zone; h=h ₂ for nozzles corresponding to the N _x control valves of the pulverized coal outlet pipes in the open state; h=h ₁ for nozzles corresponding to other NN _x charcoal gas outlet pipe control valves when open; wherein h ₁ is the specific calorific value of coal gas measured by the first calorific value sensor, h ₂ is the specific calorific value of pulverized coal measured by the second calorific value sensor, 1

j

X _i and 1

i

Y. 18. A method for supplying heat to a limestone kiln according to claim 7, characterized in that the method includes the following steps: when the pressure difference between the first pressure sensor and the second pressure sensor is higher than or equal to the minimum furnace inlet pressure, the coal gas heat supply mode is started to supply coal gas as fuel to the furnace chamber by all N nozzles; charcoal gas heat input mode is as follows: charcoal gas shut-off valve, charcoal gas fan and valve body on the charcoal gas inlet N fuel switches, all open, pulverized coal shut-off valve and valve body on pulverized coal inlet N fuel switches, all closed, the pulverized coal blower is ready for operation, and the nitrogen shut-off valve and valve bodies at the nitrogen inlet N fuel switches, all are in closed state; the coal gas check valve is in the closed state, and the pulverized coal check valve is in the open state; and N coal gas outlet pipe control valves, N pulverized coal outlet pipe control valves, and N nitrogen outlet pipe control valves are all open; calculating the average amount of coal gas supply W _ij of each nozzle in the annular heat supply zone, and adjusting the opening degree of each control valve of the coal gas discharge pipe to match the measured value S _ij of the flow meter with W _ij ; when the pressure drop is less than the minimum furnace inlet pressure, the number of switchings N _m is calculated; N _m is the theoretical number of atomizers needed to switch the fuel medium; the uniform heat mode to be started is determined, where the uniform heat mode is used to indicate the position of the nozzles required to switch the fuel medium and the actual number of nozzles N _x in the nozzle group when N _m is within the specified range of values, and N _m

N _x

N; after starting the uniform heat supply mode, the amount of fuel supplied T _ij of each atomizer in the annular heat supply zone is calculated; adjusting the opening degrees of the control valves of the pulverized coal discharge pipes at the positions corresponding to N _x nozzles, and adjusting the opening degrees of the control valves of the coal gas discharge pipes corresponding to other NN _x nozzles, so that the measured value S _ij of the flow meter corresponds to T _ij ; and the combustion air shut-off valve opens, and the operation frequency of the combustion air supply fan increases to match the amount of combustion air entering the furnace with the total amount of fuel, and the switching process is completed. 19. The method according to p. 18, characterized in that the method further includes: determining a uniform heat input threshold value N _y in accordance with the total number of atomizers N included in the atomizer group and the location of each atomizer in a cross section of the furnace chamber; when the range of values is (N _y , N], N _x is equal to N, therefore, the uniform heat supply mode is pulverized coal heat supply; when the range of values is (0, N _y ] being 0<N _x

N _y , therefore, the uniform heat supply mode is a combined heat supply using coal gas and pulverized coal; and when the value range is 0, N _x is 0, therefore, the uniform heat supply mode is the heat supply using coal gas. 20. The method of claim 19, wherein when the uniform heat input mode is pulverized coal heat input, the uniform heat input mode is started as follows: the valve body at the charcoal gas inlet of the N fuel switches and the charcoal gas cut-off valve are successively closed, while the charcoal gas check valve is opened and the charcoal gas ventilator is put into a ready-to-operate state; the nitrogen shut-off valve and the valve body at the nitrogen supply inlet of the N fuel switches are sequentially opened, and after the residual amount of pulverized coal in the fuel switch is blown into the atomizer with nitrogen, the valve body at the nitrogen supply inlet of the N fuel switches and the nitrogen shut-off valve are sequentially closed; and the pulverized coal check valve is closed, the operating frequency of the pulverized coal supply fan is increased, and when the pressure of the pulverized coal reaches the required value at the furnace inlet, the pulverized coal shut-off valve and the valve body at the pulverized coal supply inlet of the N fuel switches are opened in succession, thus , the pulverized coal passes through the pulverized coal conveying pipeline, the annular pulverized coal supply pipe, N pulverized coal discharge pipes, the pulverized coal inlet and the fuel outlet of N fuel switches and N atomizers in succession, and enters the inner cavity of the chamber oven, thus starting the mode of uniform heat supply. 21. The method according to claim 19, characterized in that when the uniform heat input mode is combined heating using coal gas and pulverized coal, the uniform heat input mode is started as follows: the pulverized coal outlet pipe control valve and the nitrogen outlet pipe control valve corresponding to the remaining NN _x nozzles are closed, and at the same time the charcoal gas outlet pipe control valve is closed at the position corresponding to N _x nozzles, and the valve body is closed at the inlet for supplying coal gas in the fuel switch in the position corresponding to N _x nozzles; the nitrogen shut-off valve and the valve body at the nitrogen inlet of the fuel switch in the position corresponding to N _x atomizers are sequentially opened, and after the residual carbon gas in the fuel switch is purged with nitrogen into the atomizer, the valve body at the nitrogen inlet of the fuel switch in the position is successively closed , corresponding to N _x sprayers, and a shut-off valve for nitrogen; and the pulverized coal check valve is closed, the operating frequency of the pulverized coal supply fan is increased, and when the pressure of the pulverized gas reaches the required value at the furnace inlet, the pulverized coal shut-off valve and the valve body at the pulverized coal supply inlet of the fuel switch are opened in sequence at the position corresponding to N _x atomizers, so the pulverized coal passes successively through the pulverized coal conveyance line, the annular pulverized coal supply pipe, N _x pulverized coal outlet pipes, the pulverized coal inlet and the fuel outlet N _x fuel switches and N _x atomizers and enters the inner cavity of the furnace chamber. 22. The method according to any one of paragraphs. 18-21, characterized in that the calculation of the number of switching N _m includes: calculating the maximum number of coal gas atomizers N _q allowed at the current pressure in the annular coal gas supply pipe P ₁ in accordance with the pressure difference between the first pressure sensor and the second pressure sensor; and calculating the difference between the total number of nozzles N and the maximum number of coal gas nozzles N _q to obtain the number of switchings N _m . 23. The method according to claim 22, characterized in that the maximum number of coal gas atomizers N _q is calculated according to the formula below:

, where ρ is the density of the coal gas, ν _i is the calculated flow rate of the coal gas atomizer, h _t is the resistance factor of the coal gas supply ring pipe, h _i is the resistance coefficient of the coal gas discharge pipe, P ₁ is the pressure in the annular coal gas pipe measured by the first pressure sensor, P ₂ is the pressure inside the furnace chamber measured by the second pressure sensor, and α is a correction factor related to the size of the limestone particles in the furnace chamber. 24. The method according to any one of paragraphs. 18-21, characterized in that the total amount of heat input Q _i of the annular heat supply zone is

, where Q ₁ is the total amount of heat input of the first annular heat input zone, the first annular heat input zone is located in the center of the cross section of the furnace chamber; Q is the theoretical amount of heat input required to fire the material at a certain cross-sectional height of the kiln chamber; δ is the heat transfer coefficient between the flue gas and the material in the limestone kiln; k _1i is the proportionality factor of the heat input between the first annular heat input zone and the i-th annular heat input zone; and Y is the number of annular heat supply zones. 25. The method according to claim 24, characterized in that the average amount of coal gas supplied W _ij of each atomizer in the annular heat supply zone is calculated according to the formula below:

, where Q _i is the total heat input of the annular heat input zone, X _i is the number of nozzles included in the annular heat input zone, h ₁ is the specific calorific value of the coal gas measured by the first calorific value sensor, 1

j

X _i and 1

i

Y. 26. The method according to claim 24, characterized in that the amount of fuel supplied T _ij of each atomizer in the annular heat supply zone is calculated according to the formula below:

, where M _i represents the average amount of heat input of each nozzle in the annular heat supply zone; Q _i is the total heat input of the annular heat input zone; X _i is the number of atomizers included in the annular heat supply zone; h=h ₂ for N _x nozzles in the open position and h=h ₁ for other NN _x nozzles; wherein h ₁ is the specific calorific value of coal gas measured by the first calorific value sensor, h ₂ is the specific calorific value of pulverized coal measured by the second calorific value sensor, 1

j

X _i and 1

i

Y.

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