WO2020216289A1 - Lime kiln and heat supply method thereof - Google Patents

Abstract

Provided are a lime kiln and heat supply method thereof, said lime kiln containing a kiln chamber (1), a heating device, and a combustion-supporting fan (2); the heating device comprises a fuel supply device and a spray gun set (3); the fuel supply device comprises a coal gas supply device (4) and a pulverized-coal supply device (5); the coal gas supply device (4) comprises a coal gas ring pipe (401) and a coal gas branch pipe (402); the pulverized-coal supply device (5) comprises a pulverized-coal ring pipe (501) and a pulverized-coal branch pipe (502); the coal gas supply device (4) and the pulverized-coal supply device (5) share the spray gun set (3); each coal gas branch pipe (402) is provided with a coal-gas branch pipe regulating valve (403); each pulverized-coal branch pipe (502) is provided with a pulverized-coal branch pipe regulating valve (503); a flow rate detector (311) is disposed on the spray gun (31); a first heat-value detector (404) and a first pressure detector (405) are respectively arranged on the coal gas ring pipe (401); a second heat value detector (504) is arranged on the pulverized-coal ring pipe (501); a second pressure detector (11) is disposed inside the kiln chamber (1); the spray gun set (3) comprises a plurality of spray gun matrices; each spray gun matrix comprises a plurality of spray guns (31) evenly distributed along the circumference thereof.

Description

Lime kiln and heating method thereof

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office on April 25, 2019, the application number is 201910340082.7, and the invention title is "a lime kiln and its heating method", the entire content of which is incorporated herein by reference Applying.

Technical field

This application relates to the technical field of lime kilns, in particular to a lime kiln and its heating method.

Background technique

The lime kiln is the core equipment in the lime production process. The raw material of limestone is heated to 1100°C in the lime kiln and calcined to produce finished lime. The fuel used for the calcination of limestone usually includes coal gas and coal powder. Due to the different combustion characteristics of coal gas and pulverized coal, the type of fuel used for a particular lime kiln is generally fixed.

Figure 1 is a schematic diagram of the structure of a conventional lime kiln. The lime kiln includes a kiln 1 and a heating device. The heating device includes a fuel ring tube 2'and a number of spray guns 31 connected to the fuel ring tube 2'. Each spray gun 31 runs along the kiln The cross section of the calcining zone of the bore 1 is evenly distributed to form a spray gun group 3, and each spray gun 31 in the spray gun group 3 communicates with the inside of the kiln bore 1. Limestone raw materials are loaded from the top of the kiln 1, the fuel is distributed from the fuel ring 2'to each spray gun 31, and each spray gun 31 evenly distributes the fuel to the inside of the kiln 1, while delivering combustion-supporting air to the inside of the kiln 1. The limestone raw material is calcined and decomposed to produce calcium oxide and carbon dioxide waste gas under the action of gas combustion heat release. The carbon dioxide waste gas is discharged from the top of the kiln 1 and the finished calcium oxide is cooled to the preset temperature under the action of the cooling air at the bottom of the kiln 1 The discharge temperature is then discharged from the bottom of the kiln 1 to complete the production of quicklime.

Since conventional lime kilns can only use one of gas or pulverized coal fuel, the heating medium fuel is single, resulting in poor production adaptability of the lime kiln. In addition, although each spray gun 31 in the spray gun group 3 runs along the calcining zone of the kiln 1 The cross-section is evenly distributed, but the conventional lime kiln still has the problem of uneven heating, which causes overburning of lime in places with high temperatures and green burning of lime in places with low temperatures, which affects the quality of lime kiln products. The above factors seriously restrict the performance of the lime kiln.

Summary of the invention

The present application provides a lime kiln and a heating method thereof to solve the problem of poor performance of the existing lime kiln.

In the first aspect, this application provides a lime kiln, including a kiln, a heating device, and a combustion-supporting fan. A combustion-supporting air pipe is connected between the combustion-supporting fan and the kiln. The combustion-supporting air pipe is provided with a combustion-supporting air cutoff valve and the heating device Including fuel supply device and spray gun group, the spray gun group is connected with the inside of the kiln. The spray gun group has a total of N spray guns. The fuel supply device includes a gas supply device and a pulverized coal supply device. The gas supply device includes a gas ring pipe and N gas The gas branch pipes connected by the ring pipe, each gas branch pipe is connected to the inlet end of a spray gun, the pulverized coal supply device includes a pulverized coal ring pipe and N pulverized coal branch pipes connected with the pulverized coal ring pipe, and each pulverized coal branch pipe is connected with The inlet end of a spray gun is connected so that the gas supply device and the pulverized coal supply device share the spray gun group; each gas branch pipe is provided with a gas branch pipe regulating valve, and each coal branch pipe is provided with a coal powder branch pipe regulating valve; on the spray gun A flow detector is provided; a first calorific value detector and a first pressure detector are respectively set on the gas loop pipe, a second calorific value detector is set on the coal powder loop pipe, and a second pressure detector is set inside the kiln; The bore section is divided into a number of annular heating areas in the radial direction. The spray gun group includes a number of spray gun matrices. Each spray gun matrix is correspondingly arranged in an annular heating area. Each spray gun matrix includes a number of spray guns evenly distributed along the circumference.

With reference to the first aspect, in a first possible implementation of the first aspect, the spray gun includes a spray gun body, the two ends of the spray gun body are respectively provided with an inlet and a discharge port, and the spray gun body includes an inner tube body and a sleeve The outer tube body is arranged outside the inner tube body, the inner fuel channel is arranged in the inner tube body, the annular outer fuel channel is formed between the inner tube body and the outer tube body, and the outer tube body is close to the discharge A section of the port is provided with a plurality of branching hole groups at intervals along the axial direction. The branching hole group includes a plurality of branching holes evenly distributed along the circumference, and the branching holes are downwardly inclined through holes.

With reference to the first aspect or the first possible implementation manner of the first aspect, in the second possible implementation manner of the first aspect, the fuel supply device further includes N fuel switches, and each fuel switch includes a gas inlet , The pulverized coal inlet and fuel outlet, the gas inlet is connected with the gas branch pipe, the pulverized coal inlet is connected with the pulverized coal branch pipe, the fuel outlet is connected with the inlet end of the spray gun, and the gas inlet and the pulverized coal inlet are respectively equipped with valve bodies; gas supply The device also includes a gas conveying fan. The gas conveying fan and the gas ring pipe are connected through the gas conveying pipe, and the gas conveying pipe is equipped with a gas shut-off valve; the pulverized coal supply device also includes the pulverized coal conveying fan, the pulverized coal conveying fan and the pulverized coal ring pipe The pulverized coal transportation pipeline is connected, and the pulverized coal transportation pipeline is provided with a pulverized coal shut-off valve.

In combination with the second possible implementation of the first aspect, in the third possible implementation of the first aspect, the fuel supply device further includes a nitrogen purging device, and the nitrogen purging device includes a nitrogen compression tank and a nitrogen loop, The nitrogen ring pipe is connected with N nitrogen branch pipes, and the N nitrogen branch pipes are respectively provided with nitrogen branch pipe regulating valves, the nitrogen compression tank and the nitrogen ring pipe are connected through a nitrogen delivery pipeline, and the nitrogen delivery pipeline is provided with a nitrogen shut-off valve; the fuel switch The device also includes a nitrogen inlet. The nitrogen inlet is connected to the nitrogen branch pipe. There is a valve body at the nitrogen inlet. By adjusting each valve body, only one of the gas inlet, the pulverized coal inlet and the nitrogen inlet is connected to the fuel outlet at the same time; When the nitrogen shut-off valve and the valve body at the nitrogen inlet are used, the residual gas or coal powder in the fuel switch is blown into the spray gun by nitrogen.

In combination with the third possible implementation manner of the first aspect, in the fourth possible implementation manner of the first aspect, the valve body includes a rigid sealing ring, a sealing plug, and a return spring; The supporting steel body; the rigid sealing ring is fixed on the periphery of the gas inlet, the pulverized coal inlet and the nitrogen inlet respectively; one end of the return spring is connected to the supporting steel body, and the other end is connected to the sealing plug; when the sealing plug is received from the fuel switch When the internal pressure is applied, the sealing plug is tightly crimped with the rigid sealing ring, so that the valve body is in a closed state; when the sealing plug receives pressure from the outside of the fuel switch, the return spring is compressed, and the sealing plug and the rigid sealing ring are separated, so that The valve body is open.

In combination with the third possible implementation manner of the first aspect or the fourth possible implementation manner of the first aspect, in the fifth possible implementation manner of the first aspect, the gas supply device further includes a gas return pipeline, a gas return pipeline A gas return valve is installed on the gas return pipe, the outlet end of the gas return pipe is connected with the inlet end of the gas conveying fan, the inlet end of the gas return pipe is connected with the gas conveying pipe, and the inlet end of the gas return pipe is located at the gas shut-off valve and the gas conveying fan Between the outlet ends, when the gas return valve is opened, the gas conveying air circulates between the gas return pipe and the gas conveying fan to release the pressure of the gas conveying fan.

With reference to the fifth possible implementation manner of the first aspect, in the sixth possible implementation manner of the first aspect, the pulverized coal supply device further includes a pulverized coal return pipeline, and a pulverized coal return valve is provided on the pulverized coal return pipeline, The outlet end of the pulverized coal return pipe is connected with the inlet end of the pulverized coal conveying fan, the inlet end of the pulverized coal return pipe is connected with the pulverized coal conveying pipe, and the inlet end of the pulverized coal return pipe is located at the pulverized coal shut-off valve and the pulverized coal conveying fan. Between the outlet ends, when the pulverized coal return valve is opened, the pulverized coal conveying air circulates between the pulverized coal return pipe and the pulverized coal conveying fan to release the pressure of the pulverized coal conveying fan.

In a second aspect, this application provides a method for heating a lime kiln, which is used in the lime kiln as described in the first aspect or the first possible implementation of the first aspect, and the method includes:

When the pressure difference between the first pressure detector and the second pressure detector is greater than or equal to the minimum kiln inlet pressure, close N pulverized coal branch pipe control valves, open N gas branch pipe control valves, and make all N spray guns deliver to the kiln chamber Gas fuel

Heating area average calculation annular gas supply quantity W _ij of each gun, adjust the opening of each of the gas branch pipe control valve, the measuring flow detector and the value S _ij W _ij match;

When the pressure difference is less than the minimum inlet pressure, calculate the switching number N _m ; N _m is the theoretical number of spray guns that need to switch the fuel medium;

Close N _x gas branch control valves, correspondingly open N _x pulverized coal branch control valves, so that the fuel delivered by N _x spray guns in the spray gun group is switched from gas to pulverized coal. N _x is the actual number of spray guns that need to switch the fuel medium. N _m ≦N _x ≦N;

Calculate the fuel supply T _ij of each spray gun in the annular heating area, adjust the opening of the N _x pulverized coal branch control valves and the other NN _x gas branch control valves, so that the measured value S _{ij of the} flow detector is equal to T _ij match;

Open the combustion-supporting air shut-off valve and increase the operating frequency of the combustion-supporting fan, so that the combustion-supporting air volume entering the kiln matches the total amount of fuel, and the switching process ends.

In some embodiments, the calculating the number of switching N _m includes:

According to the pressure difference between the first pressure detector and the second pressure detector, calculate the maximum number of gas spray guns N _q allowed in the spray gun group under the current gas loop pressure P ₁ ;

Calculate the difference between the total number of spray guns N and the maximum number of gas spray guns N _q to obtain the switching number N _m .

In some embodiments, the maximum number of gas spray guns N _q is calculated according to the following formula:

Wherein, [rho] is the gas density, v _i is the lance gas design flow rate, h _t of gas resistance coefficient of a grommet, h _i is the coefficient of drag gas manifold, P ₁ is the gas loop first pressure detector measurement, P ₂ is the internal pressure of the kiln measured by the second pressure detector, and α is the correction coefficient related to the particle size of the limestone particles in the kiln.

In some embodiments, the method further includes:

According to the total number N of spray guns included in the spray gun group and the distribution state of each spray gun on the kiln bore section, a number of uniform heating modes are preset; the uniform heating mode is used to indicate that N _{m is} in the specified value range In the spray gun group, the spray gun position of the fuel medium and the actual spray gun number N _{x in the} spray gun group need to be switched.

In some embodiments, after calculating the number of handovers N _m , the method further includes:

Determine the target uniform heating mode corresponding to the value range of N _m ;

According to the instruction of the target uniform heating mode, the fuel medium of the N _x spray guns in the corresponding part is switched from coal gas to pulverized coal.

In some embodiments, the method further includes:

Label each spray gun in the spray gun group in advance;

The corresponding relationship between the value range of N _m and the spray gun set is established to obtain a uniform heating mode; the spray gun set includes the labels of N _x spray guns in the spray gun group that need to switch the fuel medium.

In some embodiments, the method further includes:

When a number of uniform heating modes are preset, the uniform heating threshold N _{y is determined} ;

When the value range is (N _y , N), N _x is equal to N, so that the uniform heating mode is a single pulverized coal heating;

When the value range is (0, N _y ], 0 <N _x ≦ N _y , so that the uniform heating mode is gas and pulverized coal combined heating;

When the value range is 0, N _x is equal to 0, so that the uniform heating mode is single gas heating.

In some embodiments, the total amount of heat for heating the annular region Q _i is:

Q ₁ ＝Q÷δ i=1

Q _i ＝Q×k _1i /δ 2≤i≤Y

In the formula, Q ₁ is the total heat supply of the first annular heating area, which is located at the center of the kiln bore; Q is when the material is roasted at a certain height of the kiln bore The required theoretical heat supply; δ is the heat transfer efficiency between the flue gas and the material in the lime kiln; k _1i is the heat supply ratio coefficient between the first annular heating area and the i-th annular heating area; Y is the number of circular heating areas.

In some embodiments, the average gas supply amount W _ij of each spray gun in the annular heating area is calculated according to the following formula:

Where, Q _i is the total amount of heat for heating the annular region, X _i is the number of guns in the annular heating zone comprises, h ₁ is the gas specific heat value of the first heating value detector is measured, 1 ≦ j ≦ X _i , 1≦i≦Y.

In some embodiments, the fuel supply amount T _ij of each spray gun in the annular heating area is calculated according to the following formula:

In the formula, M _i is the average for each of the heat gun annular heating zone; Q _i is the total amount of heat for heating the annular region; X _i is the number of guns in the annular heating region comprises; is turned on The spray guns corresponding to the N _x pulverized coal branch control valves, h=h ₂ ; for the corresponding spray guns of the other NN _x gas branch control valves in the open state, h=h ₁ ; where h ₁ is the first heating value The unit calorific value of coal gas measured by the detector, h ₂ is the unit calorific value of pulverized coal measured by the second calorific value detector, 1≦j≦X _i , 1≦i≦Y.

For the solution described in the second aspect, the fuel supply device includes a gas supply device and a pulverized coal supply device, and the independent gas supply device and the pulverized coal supply device share a spray gun group, and each spray gun in the spray gun group is connected to a gas branch pipe. And the pulverized coal branch pipe, so that the fuel medium delivered by each spray gun can be switched between coal gas and pulverized coal. During the initial heating, the first pressure detector is used to measure the pressure of the gas loop, and the second pressure detector is used to measure the internal pressure of the kiln. When the pressure difference between the two is greater than or equal to the minimum inlet pressure, it indicates that the gas supply is sufficient. The single gas heating is preferred, and the average gas supply _Wij of each spray gun in the annular heating area is calculated, and the opening of each gas branch control valve is adjusted to match the measured value S _ij with _{Wij of} the flow detector. In order to ensure the uniformity and accuracy of heat supply in the kiln section.

During the heating process, if the pressure difference between the first pressure detector and the second pressure detector is less than the minimum inlet pressure, it indicates that the gas pressure fluctuates, causing the pressure of the gas pipeline network to be too low, and the gas pressure is not enough to support the kiln inlet. Under this condition, it is necessary to start the combined heating of gas and pulverized coal, calculate the theoretical switching number N _m , then close N _x gas regulating valves in the gas supply device, and open N _x pulverized coal in the pulverized coal supply device Regulating valve, where N _{x is} greater than or equal to N _m , so that the fuel medium of at least N _m spray guns in the spray gun group is switched from the original gas to pulverized coal, while ensuring the gas energy in the other NN _x spray guns in the spray gun group Spray into the inside of the kiln at a flow rate not lower than the design requirements to automatically switch the fuel medium of the designated spray gun according to the gas pressure. It can be seen that under the premise that a single gas heating is preferred, this application can ensure the stable operation of the lime kiln under low gas pressure conditions, ensure that the fuel medium supply in the kiln is sufficient, and the fuel medium of the lime kiln can be switched instead of being single. Thereby improving the production stability and production adaptability of the lime kiln, which is conducive to the continuous and efficient production of the lime kiln. In addition, this scheme divides the section of the lime kiln into several heating areas along the radial direction, and according to the difference in heat dissipation of each heating area , To obtain the total heat supply required by each heating area, so as to accurately calculate and implement the fuel supply required by each independent spray gun, so as to achieve precise heating, so that the materials at different positions on the same horizontal section of the kiln can be heated It is uniform and avoids overburning or raw burning of lime, thereby improving the quality of the lime kiln product. Therefore, the present application can significantly improve the performance of the lime kiln.

In a third aspect, the present application provides a heating method for a lime kiln, which is used in the lime kiln as described in the sixth possible implementation manner of the first aspect, and the method includes:

When the pressure difference between the first pressure detector and the second pressure detector is greater than or equal to the minimum kiln inlet pressure, the single gas heating mode is activated, so that all N spray guns deliver gas fuel to the kiln; the single gas heating mode It is: the valve body at the gas inlet of the gas shut-off valve, the gas conveying fan and the N fuel switchers are all open, and the valve body at the pulverized coal inlet of the pulverized coal shutoff valve and the N fuel switchers are all closed. The pulverized coal conveying fan is in standby state, the nitrogen shut-off valve and the valve bodies at the nitrogen inlet of the N fuel switchers are all closed; the gas return valve is closed, and the pulverized coal return valve is open; N gas branch control valves , N pulverized coal branch control valves and N nitrogen branch control valves are all open;

Heating area average calculation annular gas supply quantity W _ij of each gun, adjust the opening of each of the gas branch pipe control valve, the measuring flow detector and the value S _ij W _ij match;

When the pressure difference is less than the minimum inlet pressure, calculate the switching number N _m ; N _m is the theoretical number of spray guns that need to switch the fuel medium;

Determine the uniform heating mode that needs to be activated. The uniform heating mode is used to indicate when N _{m is} within the specified value range, the position of the spray gun in the spray gun group that needs to switch the fuel medium and the actual number of spray guns N _x , N _m ≦ N _x ≦N;

After starting the uniform heating mode, calculate the fuel supply T _ij of each spray gun in the annular heating area;

Adjust the opening degree of the pulverized coal branch pipe regulating valve corresponding to N _x spray guns in the position, and adjust the opening degree of the gas branch pipe regulating valve corresponding to the other NN _x spray guns, so that the measured values S _ij and T of each flow detector _ij match;

Open the combustion-supporting air shut-off valve and increase the operating frequency of the combustion-supporting fan, so that the combustion-supporting air volume entering the kiln matches the total amount of fuel, and the switching process ends.

In some embodiments, the method further includes:

Determine the uniform heating threshold N _y according to the total number N of spray guns included in the spray gun group and the distribution state of each spray gun on the kiln bore section;

When the value range is (N _y , N), N _x is equal to N, so that the uniform heating mode is a single pulverized coal heating;

When the value range is (0, N _y ], 0 <N _x ≦ N _y , so that the uniform heating mode is gas and pulverized coal combined heating;

When the value range is 0, N _x is equal to 0, so that the uniform heating mode is single gas heating.

In some embodiments, when the uniform heating mode is a single pulverized coal heating, the uniform heating mode is activated as follows:

Close the valve body and the gas shut-off valve at the gas inlet of the N fuel switchers in turn, open the gas return valve at the same time, and adjust the gas conveying fan to the standby state;

Open the nitrogen shut-off valve and the valve body at the nitrogen inlet of the N fuel switchers in sequence. After the nitrogen blows the residual coal powder inside the fuel switcher to the spray gun, close the valve body and the valve body at the nitrogen inlet of the N fuel switchers in turn. Nitrogen shut-off valve;

Close the pulverized coal return valve and increase the operating frequency of the pulverized coal conveying fan. When the pressure of the pulverized coal reaches the kiln requirement, open the pulverized coal shut-off valve and the valve body at the pulverized coal inlet of the N fuel switchers in order to make the pulverized coal sequentially After passing through the pulverized coal conveying pipeline, the pulverized coal ring pipe, N pulverized coal branch pipes, the pulverized coal inlets and fuel outlets of the N fuel switchers, and the N spray guns, it flows into the kiln, and the uniform heating mode is activated.

In some embodiments, when the uniform heating mode is combined heating of coal gas and pulverized coal, the uniform heating mode is activated as follows:

Close remaining NN _x lances corresponding to the pulverized coal pipe branch regulating gas branched valve and a nitrogen gas branch pipe control valve, while closing the parts of the N _x lances corresponding pipe control valve, and closing the portion of the N _x lances corresponding The valve body at the gas inlet in the fuel switch;

Open the nitrogen shut-off valve and the valve body at the nitrogen inlet of the fuel switch corresponding to the N _x spray guns of the position in sequence. After the nitrogen blows the residual gas inside the fuel switch to the spray gun, close the N _{x of} the position in turn The valve body and nitrogen shut-off valve at the nitrogen inlet of the fuel switch corresponding to each spray gun;

Close the pulverized coal return valve and increase the operating frequency of the pulverized coal conveying fan. When the pulverized coal pressure reaches the kiln entry requirement, turn on the pulverized coal shut-off valve and the pulverized coal inlet of the fuel switch corresponding to the N _x spray guns in the position in turn The valve body allows the pulverized coal to flow into the kiln chamber through the pulverized coal conveying pipeline, the pulverized coal ring pipe, N _x pulverized coal branch pipes, N _x pulverized coal inlets and fuel outlets of the fuel switcher, and N _x spray guns in sequence .

In some embodiments, the calculating the number of switching N _m includes:

According to the pressure difference between the first pressure detector and the second pressure detector, calculate the maximum number of gas spray guns N _q allowed in the spray gun group under the current gas loop pressure P ₁ ;

Calculate the difference between the total number of spray guns N and the maximum number of gas spray guns N _q to obtain the switching number N _m .

In some embodiments, the maximum number of gas spray guns N _q is calculated according to the following formula:

Wherein, [rho] is the gas density, v _i is the lance gas design flow rate, h _t of gas resistance coefficient of a grommet, h _i is the coefficient of drag gas manifold, P ₁ is the gas loop first pressure detector measurement, P ₂ is the internal pressure of the kiln measured by the second pressure detector, and α is the correction coefficient related to the particle size of the limestone particles in the kiln.

In some embodiments, the total amount of heat for heating the annular region Q _i is:

Q ₁ ＝Q÷δ i=1

Q _i ＝Q×k _1i /δ 2≤i≤Y

In the formula, Q ₁ is the total heat supply of the first annular heating area, which is located at the center of the kiln bore; Q is when the material is roasted at a certain height of the kiln bore The required theoretical heat supply; δ is the heat transfer efficiency between the flue gas and the material in the lime kiln; k _1i is the heat supply ratio coefficient between the first annular heating area and the i-th annular heating area; Y is the number of circular heating areas.

In some embodiments, the average gas supply amount W _ij of each spray gun in the annular heating area is calculated according to the following formula:

Where, Q _i is the total amount of heat for heating the annular region, X _i is the number of guns in the annular heating zone comprises, h ₁ is the gas specific heat value of the first heating value detector is measured, 1 ≦ j ≦ X _i , 1≦i≦Y.

In some embodiments, the fuel supply amount T _ij of each spray gun in the annular heating area is calculated according to the following formula:

In the formula, M _i is the average for each of the heat gun annular heating zone; Q _i is the total amount of heat for heating the annular region; X _i is the number of lance comprising an annular heating region; for the site Of N _x spray guns, h=h ₂ , for the other NN _x spray guns, h=h ₁ ; among them, h ₁ is the unit calorific value of the gas measured by the first calorific value detector, and h ₂ is the second calorific value detector The measured unit calorific value of pulverized coal is 1≦j≦X _i , 1≦i≦Y.

For the solution described in the third aspect, the gas supply device and the pulverized coal supply device are used in parallel, and the lime kiln fuel switching control is realized through the fuel switch. During the initial heating, the first pressure detector is used to measure the pressure of the gas loop, and the second pressure detector is used to measure the internal pressure of the kiln. When the pressure difference between the two is greater than or equal to the minimum inlet pressure, it indicates that the gas supply is sufficient. The single gas heating mode is preferred, and the average gas supply amount _Wij of each spray gun in the annular heating area is calculated, and the opening of each gas branch pipe regulating valve is adjusted to match the measured value S _{ij of the} flow detector with _Wij , In order to ensure the uniformity and accuracy of heat supply in the kiln section.

After starting the single gas heating mode, if the pressure difference between the first pressure detector and the second pressure detector is less than the minimum inlet pressure, it indicates that the gas pressure is fluctuating, causing the pressure of the gas network to be too low, and the gas pressure is not enough to support Enter the kiln, under this condition, switch the heating mode. Calculate the theoretical switching number N _m , and determine the uniform heating mode that needs to be activated next. The uniform heating mode is based on the uniformity of heating to the chamber, according to the total number N of spray guns included in the spray gun group, and each spray gun distribution in the furnace chamber section is set in advance, as long as N _m is calculated, to find the relevant parts of the gun N _m ranges corresponding need to switch connected to the fuel, and the actual number of spray guns N _x. The gas inlet, the pulverized coal inlet and the nitrogen inlet inside the fuel switch are respectively provided with valve bodies, and only one valve body at the inlet is opened at the same time, and the remaining valve bodies are closed, so as to avoid the interconnection between the inlets. The gas flees into the pulverized coal ring pipe or the pulverized coal flees into the gas ring pipe, and at the same time, it can avoid the fuel mixing caused by the backflow of the fuel in the kiln, thereby realizing the effective cut off of the coal gas. The pulverized coal supply device and the gas supply device are combined and isolated through the fuel switcher. By controlling the opening and closing status of each valve in the lime kiln and the operation status of the fan, the lime kiln fuel medium can be quickly, automatically and flexibly switched. Realize diversified heating modes, thus overcoming the shortcomings of the single type of heating fuel of the lime kiln and poor production adaptability. In addition, this scheme divides the cross section of the lime kiln into several heating areas along the radial direction, and according to each heating area The amount of heat dissipation is different, and the total heat supply required by each heating area is obtained, so as to accurately calculate and implement the fuel supply required by each independent spray gun, so as to achieve precise heating and make the kiln bore different positions on the same horizontal section The materials at the location are heated uniformly, avoiding over-burning or raw burning of lime, thereby improving the quality of the lime kiln product. Therefore, the application can significantly improve the performance of the lime kiln.

Description of the drawings

In order to explain the technical solution of the present application more clearly, the following will briefly introduce the drawings needed in the embodiments. Obviously, for those of ordinary skill in the art, without paying creative labor, Other drawings can be obtained from these drawings.

Figure 1 is a schematic diagram of the structure of an existing lime kiln;

2 is a schematic diagram of the overall structure of the lime kiln shown in Example 1 of this application;

Figure 3 is a structural diagram of the heating device of the lime kiln shown in the first embodiment of the application;

Figure 4 is a division diagram of the annular heating area on the kiln bore section shown in Example 1 of the application;

Figure 5 is a distribution diagram of each spray gun in the kiln bore cross section in the spray gun group shown in Example 1 of the application;

FIG. 6 is a distribution diagram of gas spray guns and pulverized coal spray guns in each uniform heating mode shown in Embodiment 1 of the application;

Figure 7 is a schematic diagram of the overall structure of the lime kiln shown in the third embodiment of the application;

FIG. 8 is a schematic diagram of a partial structure of a lime kiln shown in Example 3 of this application;

9 is a schematic structural diagram of a fuel switch shown in the third embodiment of the application;

10 is a schematic structural diagram of another fuel switch shown in the third embodiment of the application;

11 is a schematic diagram of the structure of the spray gun body shown in the fifth embodiment of the application;

12 is a circular cross-sectional view of a section of the spray gun body close to the outlet shown in the fifth embodiment of the application;

FIG. 13 is a schematic diagram of the spreading range of the spray gun shown in Embodiment 5 of the application.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the accompanying drawings.

As shown in Figures 2 and 3, the first embodiment of the present application provides a lime kiln, including a kiln 1, a heating device and a combustion-supporting fan 2. The heating device is used to supply and transport calcined limestone into the kiln 1. The combustion-supporting air pipe 21 is connected between the combustion-supporting fan 2 and the kiln 1, and the combustion-supporting air pipe 21 is provided with a combustion-supporting air shut-off valve 22. When the combustion-supporting fan 2 is started and the combustion-supporting air shut-off valve 22 is opened, the combustion-supporting air will be The combustion-supporting air pipe 21 enters the interior of the kiln 1 to provide combustion-supporting air for fuel combustion and heat release.

Specifically, in this embodiment, the heating device includes a fuel supply device and a spray gun group 3. The spray gun group 3 communicates with the inside of the kiln 1, and the spray gun group 3 is used to deliver the fuel provided by the fuel supply device to the inside of the kiln 1. The spray gun group 3 has N spray guns 31 in total, that is, the total number of spray guns 31 in the spray gun group 3 is N. The fuel supply device includes a gas supply device 4 and a pulverized coal supply device 5. The gas supply device 4 includes a gas ring pipe 401 and N gas branch pipes 402 connected with the gas ring pipe 401, and each gas branch pipe 402 is connected to a spray gun 31. The pulverized coal supply device 5 includes a pulverized coal ring pipe 501 and N pulverized coal branch pipes 502 connected to the pulverized coal ring pipe 501. Each pulverized coal branch pipe 502 is connected to the inlet end of a spray gun 31 to make the gas The supply device 4 and the pulverized coal supply device 5 share the spray gun group 3; each gas branch pipe 402 is provided with a gas branch pipe regulating valve 403, and each coal powder branch pipe 502 is provided with a coal powder branch pipe regulating valve 503; the spray gun 31 is provided with a flow rate Detector 311; a first calorific value detector 404 and a first pressure detector 405 are set on the gas loop 401, a second calorific value detector 504 is set on the pulverized coal loop 501, and a second pressure is set in the kiln 1 Detector 11.

Since the existing lime kiln can only use one of gas or pulverized coal fuel, if the fuel type needs to be changed, the heating system of the lime kiln can only be modified, which is very inflexible. In addition, for lime kilns built in steel plants, coal gas is a by-product of ironmaking and steelmaking processes. Although the cost is low, the supply is not stable. The gas volume and calorific value of coal gas often fluctuate greatly. Only coal gas is used as a single fuel. It is difficult to guarantee the stability of production, and the use of pulverized coal as a single fuel will increase the cost of lime production. It can be seen that the existing lime kiln has a single heating fuel and cannot adapt and flexibly switch the fuel type according to the working conditions in the steel plant, resulting in poor production adaptability and low lime kiln performance.

In this embodiment, based on the lime kiln structure shown in Figure 1, the heating device includes parallel gas supply devices and pulverized coal supply devices, independent gas supply devices and pulverized coal supply devices sharing spray gun group 3, gas branch pipes 402. The number of pulverized coal branch pipes 502 and the spray guns 31 included in the spray gun group 3 are equal, and both are N. Thus, each spray gun 31 in the spray gun group 3 is connected to a gas branch pipe 402 and a pulverized coal branch pipe 502, and a single spray gun 31 corresponds to The gas branch pipe regulating valve 403 and the pulverized coal branch pipe regulating valve 503 are not opened at the same time to prevent the gas branch pipe 402 from communicating with the pulverized coal branch pipe 502, so as to ensure that each spray gun 31 does not spray mixed fuel of gas and coal.

For a single spray gun 31, when the pulverized coal branch pipe regulating valve 503 set on the pulverized coal branch pipe 502 connected to it is closed, and the gas branch pipe regulating valve 403 on the gas branch pipe 402 connected to it is opened, the fuel medium delivered by the spray gun 31 is coal gas. When closing the gas branch regulating valve 403 on the gas branch pipe 402 connected to it, and opening the pulverized coal branch regulating valve 503 set on the pulverized coal branch pipe 502 connected to it, the fuel medium delivered by the spray gun 31 is pulverized coal. In this embodiment, by adjusting the opening and closing states of the gas branch control valve 403 and the pulverized coal branch control valve 503, the fuel medium delivered by each spray gun 31 can be quickly controlled to switch between coal gas and pulverized coal, thereby effectively solving the problem. The existing lime kiln has a single fuel and the problem of flexible switching of the fuel medium according to the production conditions of the lime kiln, thereby improving the production adaptability of the lime kiln.

Compared with pulverized coal fuel, coal gas fuel, as a by-product of ironmaking and steelmaking processes, has the advantages of low cost and simple combustion device. Therefore, this application uses coal gas fuel as the initial heating of the lime kiln when the gas pressure meets the conditions for entering the kiln. The first choice and preferred fuel at the time. In the initial heating, the first pressure detector 405 is used to measure the gas ring pressure P ₁ , and the second pressure detector 11 is used to measure the internal pressure P _{2 of the} kiln. When the pressure difference ΔP between the two is greater than or equal to the minimum inlet pressure When ΔP _min is sufficient, it means that the gas supply is sufficient to meet the conditions for entering the kiln. The single gas heating is preferred. During the single gas heating process, if the pressure difference ΔP is detected to be less than the minimum kiln entering pressure ΔP _min , it indicates that the gas pressure fluctuates. As a result, the pressure of the gas pipe network is too low, and the gas pressure is not enough to support the kiln entry, so some or all of the fuel medium delivered by the spray guns 31 in the spray gun group 3 can be switched from gas to pulverized coal, so as to ensure the stable operation of the lime kiln.

For the existing lime kiln shown in Figure 1, the applicant found in the production practice that, on the one hand, due to the differences in the production process of the spray guns and the different installation positions of the spray guns, the resistance coefficients of the spray guns are not consistent. As a result, the fuel is unevenly distributed among the various spray guns, and due to the lack of necessary detection and adjustment means, this uneven defect cannot be corrected, resulting in uneven fuel distribution on the kiln calcination section. On the other hand, theoretically, the heat dissipation of different parts of the kiln bore is not the same. Correspondingly, in order to maintain the same temperature, the theoretical heat supply required for each part of the kiln bore is also different. The least, the theoretically required heat supply is also the least; and the heat dissipation perimeter at the edge of the kiln bore is the largest, and the heat dissipation is the largest, so the theoretical heat supply is also the largest. Due to the constraints of the above two factors, even if the spray guns 31 in the spray gun group 3 are evenly distributed along the cross section of the kiln 1, they cannot truly provide accurate and uniform heating for the lime kiln.

In this regard, the section of the kiln 1 in this embodiment is divided into a number of annular heating areas in the radial direction. For example, in Figure 4, it is divided into four annular heating areas from the inside to the outside, which are R1, R2, R3 and R4, where R1 is located at the center of the section of the kiln 1 and R4 is located at the edge of the section of the kiln 1. As shown in Figure 5, the spray gun group 3 includes several spray gun matrices, and each spray gun matrix is correspondingly arranged in an annular heating area Each spray gun matrix includes a number of spray guns 31 evenly distributed along the circumference. For example, in Figure 5, the spray gun matrix of the annular heating area R1 includes one spray gun 31, and the spray gun matrix of the annular heating area R2 includes 8 spray guns 31. The spray gun matrix of the heating region R3 includes 8 spray guns 31, the spray gun matrix of the annular heating region R4 includes 16 spray guns 31, and there are a total of 33 spray guns in the spray gun group 3, that is, N=33.

After the completion of the annular heating zone is divided, depending on the respective regions can be heat amount required to accurately determine the total area of each annular heat for the heat Q _i, with a first heating value detector 404, a second The calorific value detector 504, the gas branch pipe regulating valve 403, the pulverized coal branch pipe regulating valve 503, and the flow detector 311 can precisely adjust the fuel supply of each spray gun 31. Each spray gun 31 in the spray gun group 3 can be labeled in advance, for example, the label format is qij, i is the serial number used to characterize the annular heating area, and j is the spray gun sequence number used to characterize the spray gun matrix in the area, such as the number in R2 The spray gun of q23 is used to identify the third spray gun in the second annular heating area (R2), so as to facilitate the precise identification and control of each spray gun 31.

Take the spray gun numbered q23 in the ring heating area R2 as an example, the total heat supply of the ring heating area R2 is Q ₂ , the spray gun matrix in R2 includes 8 spray guns 31, then the average heat supply of each spray gun 31 S ₂ =Q ₂ /8, the first calorific value detector 404 is used to measure the unit calorific value h _{1 of} coal gas, and the second calorific value detector 504 is used to measure the unit calorific value h _{2 of} coal powder; when the spray gun numbered q23 is transported When it is gas fuel, its fuel supply amount T ₂₃ =S ₂ /h ₁ , then adjust the opening degree of the gas branch control valve 403 corresponding to the q23 spray gun so that the measured value S ₂₃ of the flow detector 311 of the q23 spray gun matches T ₂₃ ; If the spray gun numbered q23 is delivering pulverized coal fuel, and its fuel supply T ₂₃ =S ₂ /h ₂ , adjust the opening of the pulverized coal branch control valve 503 corresponding to the q23 spray gun to make the flow detector 311 of the q23 spray gun The measured value S ₂₃ matches T ₂₃ . It can be seen that the present application can accurately obtain the fuel supply required by each spray gun 31 according to the difference in heat dissipation of each annular heating area, so as to achieve accurate and uniform heating of the lime kiln, thereby improving the performance of the lime kiln. In practical applications, the lime kiln described in the embodiment may further include a computer control unit configured to execute the program steps described in the second embodiment below.

The second embodiment of the present application specifically provides a lime kiln heating method, which is used in the lime kiln as described in the first embodiment, and the method includes the following program steps:

Step S101, when the pressure difference between the first pressure detector and the second pressure detector is greater than or equal to the minimum kiln inlet pressure, close N pulverized coal branch control valves, open N gas branch control valves, and make all N spray guns face The kiln conveys gas fuel.

The gas loop pressure P _{1 is} obtained by the first pressure detector 405, and the internal pressure P _{2 of the} kiln chamber is obtained by the second pressure detector 11, then the pressure difference ΔP=P ₁ -P ₂ , the pressure difference ΔP is the judgment Whether the gas pressure meets the key parameters of the kiln entry conditions. Then judge whether ΔP is greater than or equal to the minimum kiln inlet pressure ΔP _min , if ΔP is greater than or equal to ΔP _min , the gas pressure meets the kiln inlet conditions, and the single-gas heating mode can be started first. The single-gas heating mode is: N All pulverized coal branch pipe regulating valves 503 are in a closed state, and N coal gas branch pipe regulating valves 403 are all in an open state.

Step S102: Calculate the average gas supply amount _Wij of each spray gun in the annular heating area, adjust the opening degree of each gas branch pipe regulating valve, and match the measured value S _{ij of} the flow detector with _Wij .

Since all N spray guns 31 deliver gas into the kiln 1 in the single gas heating mode, that is, the fuel medium of each spray gun is the same, calculate the average gas supply amount _Wij of each spray gun in the annular heating area according to the following formula:

Q _i is the total amount of heat for heating the annular region, X _i is the number of guns in the annular heating zone comprises, h ₁ is the gas specific heat value of the first heating value detector is _{measured, 1 ≦ j ≦ X i,} 1 ≦i≦Y, Y is the number of annular heating areas. For the heating area division diagram shown in Fig. 5, X ₁ =1 for the R1 area, X ₂ =8 for the R2 area, X ₃ =8 for the R3 area, and X ₄ =16 for the R4 area.

Wherein the total amount of heat for heating the annular region Q _i is:

Q ₁ ＝Q÷δ i=1

Q _i ＝Q×k _1i /δ 2≤i≤Y

In the formula, Q ₁ is the total heat supply of the first annular heating area, which is located at the center of the kiln bore; Q is when the material is roasted at a certain height of the kiln bore The required theoretical heat supply; δ is the heat transfer efficiency between the flue gas and the material in the lime kiln; k _1i is the heat supply ratio coefficient between the first annular heating area and the i-th annular heating area. Since the first annular heating zone (i.e., R1) is located at a center of the bore cross-sectional kiln, the minimum amount of heat, so it is preferably used as a reference area, to calculate the total amount of heat for heating the other annular areas Q _{i, i} is greater than 1.

For the four annular heating zones shown in Figure 4, calculate R1-R4 according to the following formula, and the total heating value of each zone:

Q ₁ ＝Q÷δ i=1

Q ₂ ＝Q ₁ ×k ₁₂ ＝Q×k ₁₂ /δ

Q ₃ ＝Q ₁ ×k ₁₃ ＝Q×k ₁₃ /δ

Q ₄ ＝Q ₁ ×k ₁₄ ＝Q×k ₁₄ /δ

Among them, k ₁₂ is the heat supply ratio coefficient between R1-R2. Because R1 and R2 have different positions on the kiln section and the heat dissipation capacity, the total heat supply required by the two is different, k ₁₂ It is the scale factor used to characterize these differences, and its value range is 1.15-1.3;

k ₁₃ is the heat supply ratio coefficient between R1-R3. Because R1 and R3 have different positions on the kiln bore section and the heat dissipation, the total heat supply required by the two is different. K ₁₃ is used To characterize these differentiated scale coefficients, the value range is 1.3-1.5;

k ₁₄ is the heat supply ratio coefficient between R1-R4. Because R1 and R4 have different positions on the kiln bore section and different heat dissipation capacity, the total heat supply required by the two is different. K ₁₄ is used To characterize these differentiated scale coefficients, the value range is 1.5-1.75.

In the calculation of the annular heating zone after the average amount of each gas supply gun W _ij, each lance may be in the sync area 31 corresponding to the opening degree of the gas valve manifold 403, each lance the flow measuring instrument of measurement values S _ij 31 Matching with _Wij , the precise heating regulation under the single gas heating mode is completed. It should be noted that the division method of the annular heating area is not limited to this embodiment and shown in Figure 4, so k _1i can be selected according to the specific area division method, and in other possible implementation manners, the kiln can also be The corresponding annular heating area at the middle section or edge of the cross-section is used as the reference area to obtain the differentiated scale factor between the reference area and other annular heating areas.

Step S103, when the pressure difference is less than the minimum kiln inlet pressure, calculate the switching number N _m ; N _m is the theoretical number of spray guns that need to switch the fuel medium.

After the single gas heating mode is activated, it is still necessary to check whether the pressure difference ΔP is greater than or equal to the minimum kiln inlet pressure ΔP _{min in} real time. If it is, the gas pressure meets the kiln inlet conditions and maintain the current single gas heating state; ΔP is less than the minimum kiln inlet pressure ΔP _min , indicating that the pressure of the gas pipe network is insufficient to support the kiln inlet, and part or all of the fuel medium of the spray gun 31 needs to be switched from coal gas to coal powder.

Further, when the gas pressure does not meet the conditions for entering the kiln, according to the pressure difference ΔP, the maximum number of gas spray guns N _q allowed in the spray gun group 3 under the current gas loop pressure P ₁ can be calculated, and the spray gun group 3 includes The difference between the total number of spray guns N and the maximum number of gas spray guns N _{q is} the switching number N _m , that is, N _m =NN _q .

According to the theory of fluid mechanics, the pressure drop of the gas pipeline is calculated by formula (a):

Formula (a),, ρ is the gas density; v _t is the gas loop of gas flow rate; v _i spray gun gas design flow rate; h _t of gas resistance coefficient over the loop; h _i is the coefficient of drag gas manifold. In the heating apparatus of the lime kiln, since the conditions of gas flow rate is large, greater than 20m / s, the fluid in the inner tube over the turbulent zone, and two constants h _t h _i at this time is independent of the gas flow.

Since the geometric dimensions and other conditions of each spray gun 31 are the same, the gas flow rate of each spray gun 31 is the same, and the gas flow rate v _t in the gas loop can be calculated according to the following formula (b):

_{v t = N q · v i} (b)

In summary, we can further obtain:

According to formula (c), the maximum number of gas spray guns N _q allowed in spray gun group 3 is:

The applicant found in practice that, unlike other combustion devices, the spray gun 31 of the lime kiln is generally set in the buried limestone layer, and the fuel burns directly inside the layer. This causes the fuel to be sprayed from the spray gun 31, not only Need to overcome the pipe resistance, but also need to overcome the additional layer resistance. The resistance of the material layer to the fuel is related to the particle size and porosity of the material under the spray gun 31. For lime kiln conditions, the material at the spray gun 31 is a mixture of limestone raw materials and calcium oxide powder, and it is difficult to accurately calculate the corresponding resistance. In order to ensure that the flow rate of the fuel sprayed from the spray gun 31 is not lower than the design requirements, on the basis of the formula (d) of this embodiment, multiply a correction coefficient α related to the particle size of the limestone material particles, as shown in formula (e) As shown, the correction coefficient α is a series of values less than 1 obtained through actual production experience.

Among them, the correction coefficient α is related to the particle size of the limestone material particles, and the specific value of the correction coefficient α can be referred to Table 1 below.

Table 1

Average particle size of limestone	＜30mm	30mm-40mm	40mm-60mm	＞60mm
Correction factor α	0.4	0.6	0.75	0.8

Since N _q can only be an integer, and in order to ensure that the gas flow rate of the spray gun is not lower than the design requirement, the N _q calculated by formula (e) is rounded down to obtain formula (f):

Calculate the maximum number of gas spray guns N _q allowed in the spray gun group 3 through formula (f), and then use N _m =NN _q to calculate the theoretical switching number N _m .

Step S104, close N _x gas branch control valves, correspondingly open N _x pulverized coal branch control valves, so that the fuel delivered by N _x spray guns in the spray gun group is switched from gas to pulverized coal, and N _x is the actual fuel medium that needs to be switched Number of spray guns, N _m ≦N _x ≦N.

During the operation of single gas heating mode, if it is detected that the pressure difference ΔP is less than the minimum kiln inlet pressure ΔP _min , it is necessary to calculate the theoretical switching number N _m , and then close the N _x gas branch control valves in the gas supply device 403. Turn on N _x pulverized coal branch pipe regulating valves 503 in the pulverized coal supply device, where N _{x is} greater than or equal to N _m , so that there are at least N _m spray guns 31 in the spray gun group 3 whose fuel medium is switched from the original gas to coal At the same time, it is ensured that the gas in the other NN _x spray guns 31 in the spray gun group 3 can be sprayed into the kiln 1 at a flow rate not lower than the design requirement, so that the fuel medium of the designated spray gun 31 can be automatically switched according to the gas pressure. It can be seen that under the premise of optimizing single gas heating, this application can ensure the stable operation of the lime kiln under the condition of low gas pressure and ensure sufficient fuel medium supply in the kiln, thereby improving the production stability and production adaptability of the lime kiln. Conducive to the continuous and efficient production of the lime kiln, thereby improving the performance of the lime kiln.

However, different fuels are used for combined heating. When some of the spray guns in the spray gun group 3 deliver coal gas and the other spray guns deliver pulverized coal, the heating characteristics of different fuel media such as heat intensity and range of action are different, and kiln 1 is likely to occur. The heating temperature of different parts of the spray gun is quite different, and the temperature distribution inside the kiln 1 is uneven, which affects the product quality of the lime kiln.

In this regard, in this embodiment, the method further includes: presetting several uniform heating modes according to the total number N of spray guns included in the spray gun group 3 and the distribution state of each spray gun 31 on the cross section of the kiln 1; The uniform heating mode is used to indicate that when N _{m is} within a specified value range, the spray gun positions in the spray gun group 3 where the fuel medium needs to be switched and the actual number of spray guns N _x . Determine the target uniform heating mode corresponding to the value range of N _m , and then switch the fuel medium of the N _x spray guns in the corresponding position from coal gas to pulverized coal according to the instruction of the target uniform heating mode.

When a plurality of predetermined uniform heating mode, first need to determine the threshold value N _y uniform heating, uniform heating threshold N _y can be determined according to the total number N and the distribution state of each of the gun on the gun bore section of the kiln and other information, when N _m When it is greater than N _y , if the combined heating with coal gas and pulverized coal is used, the uniformity of temperature distribution in the kiln cannot be guaranteed.

When the value range is (N _y , N), N _x is equal to N, so that the uniform heating mode is a single pulverized coal heating;

When the value range is (0, N _y ], 0﹤N _x ≦N _y , the uniform heating mode is gas and pulverized coal combined heating;

When the value range is 0, N _x is equal to 0, so that the uniform heating mode is single gas heating.

Fig. 5 is an example of the thirty-three spray guns 31 in the spray gun group 3. The spray gun matrixes are respectively set in the four annular heating regions. The spray gun matrix in the first annular heating region R1 includes one spray gun 31, and the second The spray gun matrix in the ring heating area R2 includes eight spray guns 31, the third ring heating area R3 includes eight spray guns 31, and the fourth ring heating area R4 includes sixteen spray guns 31. This structure can make the thirty-three spray guns evenly distributed on the cross section of the kiln 1, thereby facilitating the even distribution of the kiln temperature. For this spray gun group 3 distribution structure, this embodiment shows seven uniform heating modes, as shown in the following table 2. The uniform heating threshold N _y corresponding to this spray gun group structure is equal to 9, and the uniform heating mode 1 is single Gas heating mode, uniform heating mode 2-6 is the combined heating mode of gas and pulverized coal, and uniform heating mode 7 is the single pulverized coal heating mode.

Table 2

Value range of N m	Uniform heating mode
N m =0	1
N m =1	2
1＜N m ≤4	3
N m = 5	4
5＜N m ≤8	5
N m = 9	6
9＜N m ≤33	7

When N _m = 0, it corresponds to uniform heating mode 1, as shown in Figure 6 (a). In uniform heating mode 1, the number of gas spray guns is 33, and the number of pulverized coal spray guns is 0, that is, N _x =0, the heating mode with coal gas as the single fuel medium is performed.

When N _m = 1, it corresponds to uniform heating mode 2, as shown in Figure 6 (b). In uniform heating mode 2, the number of gas spray guns is 32, and the number of pulverized coal spray guns is 1, that is, N _x = 1, the pulverized coal spray gun is a spray gun at the center of the first annular heating area (that is, the spray gun location where the fuel medium needs to be switched).

When 1<N _m ≤4, it corresponds to uniform heating mode 3, as shown in 6(c) in Figure 6. In uniform heating mode 3, the number of gas spray guns is 29, and the number of pulverized coal spray guns is 4. That is, N _x =4, and the pulverized coal spray guns are distributed at intervals in the spray gun matrix of the second annular heating area.

When N _m =5, it corresponds to uniform heating mode 4, as shown in Figure 6 (d), in uniform heating mode 4, the number of gas spray guns is 28, and the number of pulverized coal spray guns is 5, that is, N _x = 5, where 4 pulverized coal spray guns are distributed in the spray gun matrix of the third annular heating area at intervals, and the other pulverized coal spray gun is the spray gun in the center of the first annular heating area.

When 5＜N _m ≤8, it corresponds to uniform heating mode 5, as shown in 6(e) in Figure 6. In uniform heating mode 5, the number of gas spray guns is 25, and the number of pulverized coal spray guns is 8. That is, N _x =8, and the pulverized coal spray guns are all 8 spray guns in the spray gun matrix of the second annular heating area.

When N _m =9, it corresponds to uniform heating mode 6, as shown in 6(f) in Figure 6. In uniform heating mode 6, the number of gas spray guns is 24, and the number of pulverized coal spray guns is 9, namely N _x = 9, 8 of the pulverized coal spray guns are all spray guns in the spray gun matrix of the third annular heating area, and the other pulverized coal spray gun is the spray gun at the center of the first annular heating area.

When 9<N _m ≤33, that is, when N _{m is} greater than the uniform heating threshold N _y , it corresponds to uniform heating mode 7, as shown in 6(g) in Fig. 6, in uniform heating mode 7, the number of gas spray guns If the number of pulverized coal spray guns is 0, the number of pulverized coal spray guns is 33, that is, N _x = 33. When the gas pressure is too low, the maximum number of gas spray guns N _q allowed in spray gun group 3 is less. , The temperature in the kiln 1 cannot be guaranteed to be uniform, so this heating mode with pulverized coal as the single fuel medium is selected.

It should be noted that this embodiment and Figure 6 show the optional uniform heating mode when 33 spray guns are distributed according to Figure 5. For different spray gun group distribution structures, the uniform heating threshold can be determined adaptively according to the actual situation. As well as setting the corresponding uniform heating mode, this application does not limit this.

In order to facilitate the control of the uniform heating mode, in other optional solutions of this embodiment, the method further includes: pre-labeling each spray gun in the spray gun group; establishing a correspondence between the value range of N _m and the spray gun set , A uniform heating mode is obtained, and the spray gun set includes the numbers of the N _x spray guns in the spray gun group that need to switch the fuel medium. For example, referring to Figure 5, each spray gun can be labeled in sequence according to the distribution of the spray gun matrix. The number of the spray gun matrix in the first circular heating area is q11, and the spray guns in the second circular heating area are labeled clockwise in turn They are q21～q28, the spray guns in the third ring heating zone are numbered q31~q38 in turn clockwise, and the spray guns in the fourth ring heating zone are numbered q41~q416 in turn clockwise.

According to the example of the uniform heating mode given in Figure 6, the uniform heating mode can be expressed as:

Uniform heating mode 1 is the corresponding relationship between N _m =0 and {empty set};

The uniform heating mode 2 is the corresponding relationship between N _m =1 and {q11};

The uniform heating mode 3 is the corresponding relationship between 1<N _m ≤4 and {q21, q23, q25, q27};

The uniform heating mode 4 is the corresponding relationship between N _m =5 and {q11, q31, q33, q35, q37};

Uniform heating mode 5 is the corresponding relationship between 5<N _m ≤8 and {q21, q22, q23, q24, q25, q26, q27, q28};

The uniform heating mode 6 is the corresponding relationship between N _m =9 and {q11, q31, q32, q33, q34, q35, q36, q37, q38};

The uniform heating mode 7 is the corresponding relationship between 9<N _m ≤33 and {full set}.

For example, when N _m =3 is calculated, it is determined that it belongs to uniform heating mode 3, and the corresponding spray gun set is queried as {q21, q23, q25, q27}, then the number of spray gun group 3 is marked as q21, q23, q25, The gas branch control valve 403 corresponding to the q27 spray gun is closed, and the coal powder branch control valve 503 corresponding to the q21, q23, q25, and q27 spray guns in the spray gun group 3 is opened, so that the spray guns labeled q21, q23, q25, q27 The fuel medium is switched from coal gas to pulverized coal, and the spray gun corresponding to the label not included in the spray gun set {q21, q23, q25, q27} still keeps delivering gas fuel.

Step S105: Calculate the fuel supply T _ij of each spray gun in the annular heating area, and adjust the opening of the N _x pulverized coal branch control valves and the other NN _x gas branch control valves to make the measured value of the flow detector S _ij matches T _ij .

Calculated in step S102 with reference to the total amount of heat for heating the respective annular regions illustrated Q _i, and on this basis, according to the following formula to calculate the heating zone an annular fuel supply amount for each gun T _ij, where the The fuel is gas or pulverized coal:

In the formula, M _i is the average for each of the heat gun annular heating zone; Q _i is the total amount of heat for heating the annular region; X _i is the number of guns in the annular heating region comprises; is turned on The spray guns corresponding to the N _x pulverized coal branch control valves, h=h ₂ ; for the corresponding spray guns of the other NN _x gas branch control valves in the open state, h=h ₁ ; where h ₁ is the first heating value The unit calorific value of coal gas measured by the detector, h ₂ is the unit calorific value of pulverized coal measured by the second calorific value detector, 1≦j≦X _i , 1≦i≦Y.

Taking the above-mentioned uniform heating mode 4 as an example, the uniform heating mode 4 has indicated the positions of the spray guns that need to switch the fuel medium and the actual number of spray guns N _x , N _x = 5, these 5 spray guns supply pulverized coal fuel to the kiln , Calculate the fuel supply volume T _ij of the five spray guns (numbered q11, q31, q33, q35, q37) in the corresponding part, that is, the pulverized coal supply volume, the fuel supply volume of the q11 spray gun is T ₁₁ , then adjust q11 The opening degree of the pulverized coal branch pipe regulating valve 503 corresponding to the spray gun matches the measured value S ₁₁ of the flow detector of the q11 spray gun with T ₁₁ , and similarly adjusts the pulverized coal flow of the q31, q33, q35 and q37 spray guns. At the same time, for other NN _x spray guns that are not included in the {q11, q31, q33, q35, q37} spray gun set, for example, q32, whose fuel is still gas, then the fuel supply is calculated as T ₃₂ , That is the gas supply, adjust the opening of the gas branch control valve 403 corresponding to the q32 spray gun to match the measured value S ₃₂ of the flow detector of the q32 spray gun with T ₃₂ , and adjust the other NN _x -1 spray guns in the same way. Gas flow, so that the entire spray gun group 3 provides precise heating for the kiln 1.

Step S106: Open the combustion-supporting air shut-off valve, increase the operating frequency of the combustion-supporting fan, and make the combustion-supporting air volume into the kiln match the total amount of fuel, and the switching process ends.

When the fuel flow of each spray gun 31 in the spray gun group 3 is all adjusted, the operating frequency of the combustion fan 2 is increased, the combustion fan 2 is started, and the combustion air shut-off valve 22 is opened. The combustion air enters the kiln 1 through the combustion air duct 21 Internally, if the combustion-supporting air volume matches the total amount of fuel delivered by the N spray guns in the spray gun group 3, the fuel switching process of the spray gun group 3 ends, and the limestone in the kiln 1 can be calcined to obtain finished lime.

In this embodiment, under the premise that a single gas heating is preferred, this application can ensure the stable operation of the lime kiln under low gas pressure conditions, ensure that the fuel medium supply in the kiln is sufficient, and the fuel medium of the lime kiln can be switched without It is single again to improve the production stability and production adaptability of the lime kiln, which is conducive to the continuous and efficient production of the lime kiln. In addition, this scheme divides the cross section of the lime kiln into several heating areas along the radial direction, and dissipates heat according to each heating area Obtain the total heat supply required by each heating area, so as to accurately calculate and implement the fuel supply required by each independent spray gun, so as to achieve precise heat supply and make the kiln at different positions on the same horizontal section The materials are heated uniformly to avoid over-burning or raw burning of lime, thereby improving the quality of the lime kiln product. Therefore, this solution can significantly improve the performance of the lime kiln.

As shown in Figures 7-9, the third embodiment of the present application provides another lime kiln. On the basis of the lime kiln structure described in the first embodiment, the fuel supply device further includes N fuel switchers 6, and the fuel switch The device 6 corresponds to the spray gun 31 one-to-one. Figures 7-9 only show the connection structure of one set of fuel switch 6 and spray gun 31. The connection structure of the other N-1 groups of fuel switch 6 and spray gun 31 is the same. Therefore, it is not shown in the figure. The fuel switch 6 is used to combine and isolate the gas supply device 4 and the pulverized coal supply device 5 to ensure that the lime kiln can switch fuel from coal gas to pulverized coal, and fuel from pulverized coal to gas, and ensure There will be no mixed flow between coal gas and pulverized coal in the lime kiln. Limestone raw materials are loaded into the kiln 1 through the distributor 8. The spray gun 31 is used to spray the switched fuel (gas or coal) into the kiln 1, and then open the combustion air shut-off valve 22 to enable the combustion fan 2 to deliver The combustion-supporting air enters the kiln 1 through the combustion-supporting air pipe 21, and the fuel is burned to provide heat for the calcined limestone to produce lime products.

Each fuel switch 6 includes a gas inlet 61, a pulverized coal inlet 62 and a fuel outlet 64. The gas inlet 61 is connected to the gas branch pipe 402, the pulverized coal inlet 62 is connected to the pulverized coal branch pipe 502, and the fuel outlet 64 is connected to the inlet of the spray gun 31. The gas inlet 61 and the pulverized coal inlet 62 are respectively provided with valve bodies 65; the gas supply device 4 also includes a gas conveying fan 406. The gas conveying fan 406 and the gas ring pipe 401 are connected through the gas conveying pipe 407, and the gas conveying pipe 407 There is a gas shut-off valve 408; the pulverized coal supply device 5 also includes a pulverized coal conveying fan 505. The pulverized coal conveying fan 505 is connected to the pulverized coal ring pipe 501 through a pulverized coal conveying pipe 506. The pulverized coal conveying pipe 506 is provided with pulverized coal. Shut off valve 507.

In the gas supply pipeline, the gas conveying fan 406, the gas conveying pipe 407, and the gas ring pipe 401 constitute the main gas pipeline. N gas branches are generated from the gas ring pipe 401, and the gas branches include corresponding gas in turn. The branch pipe 402, the fuel switch 6 and the spray gun 31. When the gas shut-off valve 408 is open and the gas conveying fan 406 is working normally, the main gas pipeline is turned on, and the N gas branches are also turned on, so as to transport gas fuel to the kiln 1; when the gas shut-off valve 408 is closed When the operating frequency of the gas conveying fan 406 is low to the standby state, the entire gas supply pipeline is cut off, and at this time, no gas is supplied to the kiln 1.

Similarly, in the pulverized coal supply pipeline, the pulverized coal conveying fan 505, the pulverized coal conveying pipe 506, and the pulverized coal ring pipe 501 constitute the pulverized coal main pipeline, and N pulverized coal branch roads are generated from the pulverized coal ring pipe 501. The pulverized coal branch road includes a pulverized coal branch pipe 502, a fuel switch 6 and a spray gun 31 corresponding in sequence. When the pulverized coal shut-off valve 507 is in the open state and the pulverized coal conveying fan 505 is working normally, the main pulverized coal pipeline is turned on, and the N pulverized coal branch circuits are also turned on, thus transporting pulverized coal fuel to the kiln 1; The pulverized coal shut-off valve 507 is in the closed state, and when the operation frequency of the pulverized coal conveying fan 505 is low to the standby state, the entire pulverized coal supply pipeline is cut off, and at this time, no pulverized coal is supplied to the kiln 1.

9, taking the spray gun 31 to deliver pulverized coal to the kiln 1 as an example, the working principle of the fuel switch 6 is explained. The valve body 65 at the pulverized coal inlet 62 is opened, and the valve body 65 at the gas inlet 61 is closed to avoid coal. The pulverized coal fuel from the pulverized branch pipe 502 enters the gas supply pipeline through the gas inlet 61, thereby avoiding the mixed flow of pulverized coal and gas. At this time, only the pulverized coal inlet 62 is connected to the fuel outlet 64, and the pulverized coal flows in from the pulverized coal inlet 62, flows out from the fuel outlet 64, and enters the spray gun 31. At the same time, only one of the gas inlet 61 and the pulverized coal inlet 62 is in communication with the fuel outlet 64, thereby isolating the pulverized coal and gas. The valve body 65 may be a solenoid valve or a fluid control valve with other types of structures, which is not limited in this application.

Since the cross-sectional area of the fuel switch 6 is larger than the diameter of the respective inlets (the gas inlet 61, the pulverized coal inlet 62, and the nitrogen inlet 63), a small part of the fuel may not be fully discharged from the fuel outlet 64, which may result in the fuel switch 6 Fuel residue. In addition, since the fuel outlet 64, the spray gun 31 and the kiln 1 are in communication with each other, it may also happen that the fuel in the kiln 1 flows back to the fuel switch 6. For example, when the lime kiln fuel needs to be switched from coal gas to pulverized coal, since there may be residual gas in the fuel switch 6, once the valve body 65 at the pulverized coal inlet 62 is opened, the residual gas may flow from the pulverized coal inlet 62. Into the pulverized coal supply pipeline, resulting in mixed flow of gas and pulverized coal, that is, the gas and pulverized coal are not effectively isolated and cut off. On the one hand, if the mixed flow of gas and pulverized coal enters the kiln 1, due to the different combustion characteristics of gas and pulverized coal, it will affect the uniformity of the temperature distribution of the calcining zone in the kiln 1, thereby affecting the product quality of the lime kiln. On the other hand, if coal powder and coal gas are mixed, it is also easy to cause an explosion, thereby causing safety hazards during the production of the lime kiln.

In this regard, in the preferred solution of this embodiment, the fuel supply device further includes a nitrogen purging device 7, which includes a nitrogen compression tank 71 and a nitrogen ring 72, and the nitrogen ring 72 is connected with N nitrogen The branch pipes 73 and the N nitrogen branch pipes 73 are respectively provided with a nitrogen branch regulating valve 74, the nitrogen compression tank 71 and the nitrogen ring pipe 72 are connected through a nitrogen delivery pipe 75, and a nitrogen shutoff valve 76 is provided on the nitrogen delivery pipe 75; the fuel switch The device 6 also includes a nitrogen inlet 63. The nitrogen inlet 63 is connected to the nitrogen branch pipe 73. The nitrogen inlet 63 is provided with a valve body 65. By adjusting each valve body 65, the gas inlet 61, the pulverized coal inlet 62 and the nitrogen inlet 63 are at the same time. Only one of them is connected to the fuel outlet 64; when the nitrogen shut-off valve 76 and the valve body 65 at the nitrogen inlet 63 are opened, the residual gas or coal powder in the fuel switch 6 is blown into the spray gun 31 by nitrogen.

In the nitrogen supply pipeline, the nitrogen compression tank 71, the nitrogen delivery pipe 75 and the nitrogen loop 72 constitute a nitrogen main pipeline. N nitrogen branches are generated from the nitrogen loop 72, and the nitrogen branches include corresponding nitrogen in sequence. Branch pipe 73, fuel switch 6 and spray gun 31. When the nitrogen shut-off valve 76 is in the open state, the nitrogen main pipeline is turned on, and the N nitrogen branches are also turned on. The valve body 65 at the nitrogen inlet 63 in the N fuel switches 6 is opened, and the nitrogen switches the fuel switch 6 The remaining fuel inside is purged into the spray gun 31 and returned to the kiln 1 by the spray gun 31; after purging, the nitrogen shut-off valve 76 and the valve body 65 at the nitrogen inlet 63 are closed, and the entire nitrogen supply pipeline is cut off. The preliminary work of the switching process is completed, and the fuel can be switched based on the aforementioned gas supply pipeline or pulverized coal supply pipeline. Since nitrogen is an inert gas and is not flammable, the use of nitrogen to blow the fuel into the kiln 1 will not affect the combustion of the fuel and also avoid the risk of explosion. By installing a nitrogen purge device 7, the coal The powder and gas are effectively separated, and the safety of lime kiln production is improved.

In a preferred solution of this embodiment, as shown in FIG. 10, this embodiment also provides a specific structure of a valve body 65. Unlike an electronic control valve, the valve body 65 includes a rigid sealing ring 651, a sealing plug 652 and The return spring 653; the inner center of the fuel switch 6 is provided with a fixed support steel body 66; the rigid sealing ring 651 is fixed on the periphery of the nozzles of the gas inlet 61, the pulverized coal inlet 62 and the nitrogen inlet 63 respectively; one end of the return spring 653 and the support The steel body 66 is connected, and the other end is connected with the sealing plug 652; when the sealing plug 652 receives the pressure from the inside of the fuel switch 6, the sealing plug 652 is tightly crimped with the rigid sealing ring 651, so that the valve body 65 is in a closed state; When the plug 652 receives pressure from the outside of the fuel switch 6, the return spring 653 is compressed, and the sealing plug 652 is separated from the rigid sealing ring 651, so that the valve body 65 is in an open state.

Taking the spray gun 31 conveying pulverized coal into the kiln 1 as an example, the pulverized coal conveying air from the pulverized coal branch pipe 502 has a certain pressure. When passing through the pulverized coal inlet 62, the sealing plug 652 is pushed from the outside, and the return spring 653 is The pulverized coal inlet 62 is compressed to open the pulverized coal inlet 62 and the fuel outlet 64. It can be seen that for the valve body 65 at the pulverized coal inlet 62, the sealing plug 652 is subjected to the pulverized coal conveying air from the pulverized coal branch pipe 502 The pressure is from the outside of the fuel switch 6; when the pulverized coal conveying air enters the fuel switch 6 from the pulverized coal inlet 62, the air pressure of the pulverized coal conveying air will seal the gas inlet 61 and the nitrogen inlet 63 The plug 652 compresses the rigid sealing ring 651 to ensure the airtightness of the gas inlet 61 and the nitrogen inlet 63. The sealing plug 652 at the gas inlet 61 and the nitrogen inlet 63 is subjected to pressure from the inside of the fuel switch 6.

The support steel body 66 is arranged in the center of the fuel switch 6 and its position is fixed. One end of the return spring 653 is connected to the support steel body 66, and the other end of the return spring 653 is connected to the sealing plug 652. The sealing plug 652 can follow the return spring When the fuel delivery is completed, the return spring 653 resets and drives the sealing plug 652 to press the rigid sealing ring 651, thereby controlling the opening and closing of the gas inlet 61, the pulverized coal inlet 62 and the nitrogen inlet 63, avoiding the gap between the inlets. Connect with each other. The rigid sealing ring 651 is arranged around each inlet. The diameter of the rigid sealing ring 651 is slightly larger than the diameter of the inlet, and the size of the sealing plug 652 should be larger than the diameter of the rigid sealing ring 651 to ensure the sealing performance of each inlet. If the rigid sealing ring 651 is not provided, the sealing plug 652 directly blocks the inlet of the fuel switch 6. The sealing performance of this surface contact seal is poor, and the rigid sealing ring 651 and the sealing plug 652 are crimped, which will cause the valve body 65 has good airtightness to ensure the effect of fuel switching. The valve body shown in Fig. 10 has a simple structure, which can reduce the equipment cost of the lime kiln. By spontaneously sensing the pressure from the inside and outside of the fuel switch 6, the opening and closing of the valve body 6 is automatically controlled without sending an electric control signal for control. The sealing performance and control efficiency of the valve body 65 are improved.

When the fuel in the kiln 1 returns, it may enter the fuel switch 6 from the fuel outlet 64. At this time, the sealing plugs 652 of the valve body 65 at the gas inlet 61, the pulverized coal inlet 62 and the nitrogen inlet 63 are all exposed to the fuel The pressure inside the switch 6 and the return spring 653 can make the three valve bodies 65 closed. The three inlets of the fuel switch 6 have good sealing properties to ensure that the returning fuel will not enter the gas branch pipe 402, coal Powder branch pipe 502 and nitrogen branch pipe 73. When switching fuel, the nitrogen purging device 7 is used to blow the return fuel remaining in the fuel switch 6 into the spray gun 31 again, and the spray gun 31 can be sprayed back into the kiln 1.

When switching fuel, take the fuel switch from gas to pulverized coal as an example. When the gas shut-off valve 408 is closed, the main gas pipeline is cut off, and the gas conveying fan 406 cannot suddenly stop running, but needs to gradually reduce the operating frequency to In the standby state, the pressure of the gas delivery pipe 407 between the gas shut-off valve 408 and the gas delivery fan 406 increases, thereby affecting the safety of the gas supply pipe. Similarly, the pulverized coal supply pipeline also has the same problem.

In this regard, in the preferred solution of this embodiment, referring to FIG. 7, the gas supply device 4 further includes a gas return pipe 409, the gas return pipe 409 is provided with a gas return valve 410, the outlet end of the gas return pipe 409 and the gas conveying fan The inlet end of 406 is connected, the inlet end of the gas return pipe 409 is connected to the gas delivery pipe 407, and the inlet end of the gas return pipe 409 is located between the gas shut-off valve 408 and the outlet end of the gas delivery fan 406. When the gas return valve 410 is opened At this time, the gas conveying air can be circulated between the gas return pipe 409 and the gas conveying fan 406 to release the pressure of the gas conveying fan 406, thereby ensuring the safety of the gas supply pipeline.

The pulverized coal supply device 5 also includes a pulverized coal return pipeline 508. The pulverized coal return pipeline 508 is provided with a pulverized coal return valve 509. The outlet end of the pulverized coal return pipeline 508 is connected to the inlet end of the pulverized coal conveying fan 505. The pulverized coal return pipeline The inlet end of 508 is connected with the pulverized coal conveying pipe 506, and the inlet end of the pulverized coal return pipe 508 is located between the pulverized coal shut-off valve 507 and the outlet end of the pulverized coal conveying fan 505. When the pulverized coal return valve 509 is opened, The pulverized coal conveying air circulates between the pulverized coal return pipe 508 and the pulverized coal conveying fan 505 to release the pressure of the pulverized coal conveying fan 505, thereby ensuring the safety of the pulverized coal supply pipeline. The lime kiln described in the third embodiment may further include a computer control unit configured to execute the program steps described in the fourth embodiment below.

The fourth embodiment of the present application provides a lime kiln heating method, which is used in the lime kiln structure as described in the third embodiment, and the method includes:

First, when the pressure difference between the first pressure detector and the second pressure detector is greater than or equal to the minimum kiln entry pressure, indicating that the gas pressure meets the kiln entry conditions, the single gas heating mode will be activated first, so that all the N spray guns are directed The kiln conveys gas fuel; the single gas heating mode is: the gas shut-off valve 408, the gas conveying fan 406, and the valve body 65 at the gas inlet 61 of the N fuel switches 6 are all open, and the pulverized coal shut-off valve 507 And the valve bodies 65 at the pulverized coal inlet 62 in the N fuel switches 6 are all closed, the pulverized coal conveying fan 505 is in standby state, the nitrogen shut-off valve 76 and the valve body at the nitrogen inlet 63 in the N fuel switches 6 65 are all closed; the gas return valve 410 is closed, and the pulverized coal return valve 509 is open; N gas branch control valves 403, N pulverized coal branch control valves 503, and N nitrogen branch control valves 74 are all open status. After starting the single heating mode, each link of the supply device is in the state as described above. In this case, proceed to the second step to adjust the gas flow of each spray gun 31 in the spray gun group 3 to achieve the lime kiln Precise heating.

Second, calculate the average gas supply _Wij of each spray gun in the annular heating area, and adjust the opening of each gas branch control valve to match the measured value S _{ij of} the flow detector with _Wij . For the precise heating flow adjustment methods described in step S202 and step S206, reference may be made to the related description and description in the second embodiment, which will not be repeated in this embodiment.

Third, when the pressure difference is less than the minimum kiln inlet pressure, calculate the switching number N _m ; N _m is the theoretical number of spray guns that need to switch the fuel medium. For this step, reference may be made to the related description and description in the second embodiment, which will not be repeated in this embodiment.

Fourth, determine the uniform heating mode that needs to be activated. The uniform heating mode is used to indicate that when N _{m is} within a specified value range, the position of the spray gun in the spray gun group that needs to switch the fuel medium and the actual number of spray guns N _x , N _m ≦N _x ≦N.

According to the total number N of spray guns included in the spray gun group and the distribution state of each spray gun on the kiln bore section, the uniform heating threshold N _{y is determined} . The distribution state of the spray guns on the kiln bore section described here includes the division of the annular heating area, and the number of spray guns included in the spray gun matrix in each annular heating area and the distribution position and status of each spray gun.

When the value range is (N _y , N), N _x is equal to N, so that the uniform heating mode is a single pulverized coal heating;

When the value range is (0, N _y ], 0 <N _x ≦ N _y , so that the uniform heating mode is gas and pulverized coal combined heating;

When the value range is 0, N _x is equal to 0, so that the uniform heating mode is single gas heating.

For the preset mode and working mode of the uniform heating mode, please refer to the related description and description in the second embodiment of the present application, which will not be repeated in this embodiment. After calculating the switching number N _m , the uniform heating mode that needs to be adopted can be determined according to the value range of N _m .

In a possible implementation manner, when N _m =N _x =0, the current single gas heating mode of the lime kiln is maintained unchanged, that is, the state mode described in the first step is maintained.

In another possible implementation, when it is determined that the uniform heating mode is a single pulverized coal heating, it is necessary to switch the fuel of all N spray guns from coal gas to pulverized coal synchronously. In the state of the aforementioned single gas heating mode , Start the uniform heating mode as follows:

(A) Turn off the valve body 65 and the gas shut-off valve 408 at the gas inlet 61 of the N fuel switches 6 in turn, and open the gas return valve 410 at the same time, and adjust the gas conveying fan 406 to the standby state; at this time, the entire gas supply pipe The circuit is cut off, the heating device no longer delivers gas into the kiln 1, and the gas return valve 410 is used to release the pressure of the gas delivery fan 406.

(B) Open the nitrogen shut-off valve 76 and the valve body 65 at the nitrogen inlet 63 of the N fuel switches 6 in sequence. After the nitrogen blows the remaining coal powder in the fuel switch 6 to the spray gun 31, the nitrogen purge process ends , Close the valve body 65 and the nitrogen shut-off valve 76 at the nitrogen inlet 63 of the N fuel switches 6 in sequence. At this time, the residual gas in the N fuel switchers 6 is removed, which effectively avoids the possibility of pulverized coal and gas mixing during the switching process, and the entire nitrogen supply pipeline can be cut off to prepare for the subsequent delivery of pulverized coal fuel to the kiln 1. .

(C) Close the pulverized coal return valve 509 and increase the operating frequency of the pulverized coal conveying fan 505. When the pulverized coal pressure reaches the kiln entry requirement, it is guaranteed that the pulverized coal can be driven into the kiln 1 through the spray gun 31, and the coal is turned on in turn The pulverized cut-off valve 507 and the valve body 65 at the pulverized coal inlet 62 of the N fuel switchers 6 make the pulverized coal pass through the pulverized coal conveying pipe 506, the pulverized coal ring pipe 501, N pulverized coal branch pipes 502, and N fuel switches in sequence The pulverized coal inlet 62 and fuel outlet 64 of the device 6 and the N spray guns 31 finally flow into the interior of the kiln 1, and the uniform heating mode is started. In this way, the fuel in the N spray guns 31 Synchronously switch from gas to pulverized coal.

In another possible implementation, when it is determined that the uniform heating mode is the combined heating of coal gas and pulverized coal, the uniform heating mode can be used to know which parts of the spray gun group 3 will be fueled by the spray guns. Switching from gas to pulverized coal and the actual number of spray guns N _x that need to switch the fuel medium is to switch the fuel of some of the N spray guns from gas to pulverized coal. In the aforementioned single gas heating mode, follow the steps below Start the uniform heating mode:

(D) Close the pulverized coal branch pipe regulating valve 503 and nitrogen branch pipe regulating valve 74 corresponding to the remaining NN _x spray guns (that is, not the spray guns at the designated position in the uniform heating mode), and at the same time, close the positions (that is, the uniform heating mode The location of the spray guns that need to switch fuel is specified in) the gas branch pipe regulating valve 403 corresponding to the N _x spray guns, and close the valve at the gas inlet 61 in the fuel switch 6 corresponding to the N _x spray guns in the location体65.

For the remaining NN _x spray guns 31, after the adjustment in step (D), the corresponding pulverized coal branch and nitrogen branch are cut off, and only the gas branch remains conductive. Therefore, the NN _x spray guns 31 spray The fuel medium is still gas, which will not be affected by subsequent nitrogen purging and switching to pulverized coal. The gas passes through the gas pipeline 407, the gas loop 401, NN _x gas branch pipes 402, and NN _x coal gas from the fuel switch 6 in sequence. The inlet 61 and the fuel outlet 64, as well as NN _x spray guns 31, flow into the kiln 1. For the N _x spray guns 31 at the position, the corresponding gas branch is cut off. The nitrogen supply pipeline can be opened according to the following step (E) to purge the residual gas inside the fuel switch 6 to ensure that the spray guns 31 will not blow out Mixed fuel of coal gas and pulverized coal.

(E) Open the nitrogen shut-off valve 76 and the valve body 65 at the nitrogen inlet 63 of the fuel switch 6 corresponding to the N _x spray guns at the position in sequence, after the nitrogen blows the remaining gas in the fuel switch 6 to the spray gun 31 , The valve body 65 and the nitrogen shut-off valve 76 at the nitrogen inlet 63 of the fuel switcher 6 corresponding to the N _x spray guns at the position are sequentially closed. When the nitrogen N shutoff valve 76 is opened, nitrogen gas is turned general line, a nitrogen from the nitrogen loop strip N _x N _x branches nitrogen guns 31 into the corresponding portion 72, and the fuel corresponding to the switches 6 _x After the remaining gas is purged and sent to the respective spray guns 31, the nitrogen branch can be cut off, and the next step (F) is prepared to switch the fuel of the N _x spray guns 31 at the location from gas to pulverized coal.

(F) Close the pulverized coal return valve 509 and increase the operating frequency of the pulverized coal conveying fan 505. When the pressure of the pulverized coal reaches the requirement for entering the kiln, turn on the pulverized coal shut-off valve 507 and the fuel switching corresponding to the N _x spray guns in the position in turn The valve body 65 at the pulverized coal inlet 62 in the device 6 causes the pulverized coal to pass through the pulverized coal conveying pipe 506, the pulverized coal ring pipe 501, N _x pulverized coal branch pipes 502, and N _x pulverized coal inlets 62 of the fuel switch 6 in sequence. And the fuel outlet 64 and N _x spray guns 31 finally flow into the kiln 1.

In this embodiment, the gas conveying fan 406 and the pulverized coal conveying fan 505 can operate normally at the same time. The pulverized coal conveying fan 505 is used to convey pulverized coal to the N _x spray guns 31 in the position, and the gas conveying fan 406 is used to convey pulverized coal to the other NN _x One spray gun 31 delivers gas. Since each spray gun 31 has a corresponding gas branch control valve 403, a pulverized coal branch control valve 503, and a nitrogen branch control valve 74, it can ensure that the gas supply device 4 and the pulverized coal supply device 5 can simultaneously supply fuel , And will not interfere with each other, so it can realize the combined heating of coal gas and coal.

The above single gas heating mode, combined gas and pulverized coal heating mode, and single pulverized coal heating mode. The startup mode and control method of these three modes are the valve bodies 65 at the three inlets inside the fuel switch 6 The valve body structure shown in Figure 6 can be used, such as a traditional solenoid valve, etc., or a specially designed pressure-sensitive automatic regulating valve as shown in Figure 10 can be used, as long as it can achieve the three inlets of the fuel switch 6 Just seal and open and close.

Fifth, after starting the uniform heating mode, calculate the fuel supply amount T _ij of each spray gun in the annular heating area.

Sixth, adjust the opening of the pulverized coal branch control valve corresponding to the N _x spray guns in the position, and adjust the opening of the gas branch control valve corresponding to the other NN _x spray guns, so that the measured value of each flow detector is S _ij matches T _ij .

Seventh, open the combustion-supporting air shut-off valve, increase the operating frequency of the combustion-supporting fan, and make the combustion-supporting air volume into the kiln match the total amount of fuel, and the switching process ends.

It should be noted that after the single gas heating is started first, if the pressure difference between the first pressure detector and the second pressure detector is less than the minimum inlet pressure, switch to the combined heating mode of gas and pulverized coal, or switch to In the single pulverized coal heating mode, when the non-single gas heating mode is activated, it is still necessary to detect in real time whether the pressure difference is greater than or equal to the minimum inlet pressure. This application has disclosed the operating status of each equipment and valve in the heating device in the single gas heating mode. If the gas pressure meets the kiln entry conditions under the current non-single gas heating mode, you can choose from the current heating mode Switch to a single gas heating mode to reduce the fuel cost of the lime kiln. In addition, by adjusting the operating status of various equipment and valves in the heating device, the mutual conversion between various heating modes can be realized to achieve the actual heating effect required, thereby improving the production adaptability of the lime kiln .

In this embodiment, the pulverized coal supply device and the gas supply device are combined and isolated by a fuel switcher, and by controlling the opening and closing status of each valve in the lime kiln and the operation status of the fan, the switch can be quickly, automatically and flexibly The lime kiln fuel medium realizes diversified heating modes, thereby overcoming the shortcomings of single heating fuel type and poor production adaptability of the lime kiln. In addition, this scheme divides the cross section of the lime kiln into several heating areas along the radial direction. According to the difference in heat dissipation of each heating area, obtain the total heat supply required by each heating area, so as to accurately calculate and implement the fuel supply required by each independent spray gun, so as to achieve precise heating and make the kiln chamber the same The materials at different positions on the horizontal section are evenly heated to avoid over-burning or raw burning of lime, thereby improving the quality of the lime kiln product. Therefore, the present application can significantly improve the performance of the lime kiln.

For the spray guns involved in the above embodiments, due to the limitation of the spreading range of each spray gun, the fuel sprayed by the spray gun is mainly concentrated at the outlet of the spray gun, but the area between the spray gun and the spray gun does not distribute fuel, that is, the fuel is in The uneven distribution on the cross section of the kiln leads to high material temperature at the spray gun outlet and relatively low material temperature in the area between the spray gun and the spray gun. This makes the limestone calcination rate different on the same cross section of the kiln and affects the quality of the finished quicklime.

In this regard, as shown in FIGS. 11 and 12, on the basis of the solutions described in the foregoing embodiments, Embodiment 5 of the present application specifically provides a structure of a spray gun 31, including a spray gun body 3101, which is respectively provided with The inlet 3102 and the outlet 3103, the spray gun body 3101 includes an inner tube body 3104 and an outer tube body 3105. The outer tube body 3105 is sleeved on the outside of the inner tube body 3104. The inner tube body 3104 and the outer tube body 3105 are both It is a hollow tube structure, the inner tube body 3104 is provided with an inner fuel channel 3106, the diameter of the inner tube body 3104 is smaller than the diameter of the outer tube body 3105, so that the inner tube body 3104 and the outer tube body 3105 A ring-shaped outer fuel passage 3107 is formed. A section of the outer tube body 3105 close to the outlet 3103 is provided with a plurality of diversion hole groups 3108 spaced along the axial direction. The diversion hole group 3108 includes a plurality of distribution holes 3109 evenly distributed along the circumference. Generally, the calcining process temperature of the lime kiln is about 1100°C, and the spray gun body 3101 can be made of high temperature resistant materials, which can be selected according to actual applications.

The spray gun provided in this embodiment is based on a dual-channel structure. Fuel (including coal gas, pulverized coal, etc.) flows in from the inlet 3102, and then enters the inner fuel channel 3106 and the outer fuel channel 3107 respectively, and finally from the outlet 3103 and each distribution hole 3109 The outlet 3103 is the main outlet of the spray gun body 3101. Most of the fuel is sprayed through the main outlet. The sub-circulation holes 3109 provided on the outer tube body 3105 are equivalent to the auxiliary outlets of the spray gun body and flow into the outer fuel channel. A small part of the fuel of 3107 is sprayed through the distribution hole 3109, which effectively increases the spreading range of a single spray gun, thereby distributing fuel to the area between the spray gun and the spray gun, so as to ensure the uniformity of temperature distribution on the same section of the kiln and improve the quicklime The quality of the finished product.

In practical applications, in order to facilitate the material guide of the spray gun, the spray gun body can be divided into a horizontal section 3110, a circular arc transition section 3111 and a vertical section 3112. The horizontal section 3110 and the vertical section 3112 are connected by the circular arc transition section 3111; 3102 is set at the open end of the horizontal section 3110, such as the left end of the horizontal section 3110 in Figure 11; the outlet 3103 is set at the open end of the vertical section 3112, such as the bottom end of the vertical section 3112 in Figure 11, and a number of diversion hole groups 3108 It is arranged on the outer tube body 3105 corresponding to the vertical section 3112. In practical applications, the horizontal section 3110, the arc transition section 3111, and the vertical section 3112 may be provided as an integral structure, or alternatively, a method such as segmented welding may also be selected, which is not limited in this application.

As shown in Figure 13, the spreading range of the existing lime kiln spray gun is only the area S1 below the outlet, and the sprayed fuel falls in the area where S1 is located, so that the fuel cannot be distributed between the spray gun and the spray gun. , Resulting in uneven temperature distribution in the kiln chamber section. In the present application, the fuel flowing into the outer fuel channel 3107 will flow out of the sub-circulation holes 3109 after falling into the area of the vertical section 3112, so that the fuel spreading range is expanded, and the spreading range is larger than S1. In other possible implementations, the central axis of the inner tube body 3104 coincides with the central axis of the outer tube body 3105 to ensure that the distribution of the fuel flowing out of the sub-circulation holes 3109 is more even and symmetric; the sub-circulation holes 3109 are directed The downwardly inclined through hole, that is, the central axis of the sub-circulation hole 3019 and the central axis of the vertical section 3112 have an inclination angle β, so that the spray gun spreading range is S1+S2, where S1 is constant, and S2 is a number of branch hole groups 3108 For example, the split hole group with the largest height in the vertical direction in Figure 13 has the largest spray range. The value of S2 is related to the design height of the split hole group 3108 and the inclination angle β. The higher the height of the split hole group 3108 and the greater the inclination angle β, the larger S2 and the larger the spreading range of a single spray gun. Therefore, in practical applications, the size of the spray gun body 3101, the distribution of the split hole group 3108 on the vertical section 3112, and the size of the inclination angle β can be reasonably designed according to parameters such as the number of spray guns, the distribution state of the spray guns, and the size of the kiln chamber.

With the dual-channel spray gun provided in this embodiment, the spraying range of the spray gun is no longer limited. The fuel spraying range is increased from the original S1 to S1+S2, which can not only act on the outlet, but also on the spray gun and the spray gun. In the area, the fuel distribution is more in place and uniform, and the temperature distribution of the kiln hearth section of the lime kiln is also more uniform, thereby improving the quality of the finished quicklime product, thereby improving the performance of the lime kiln.

The same or similar parts in the various embodiments in this specification can be referred to each other.

The implementation manners of the present application described above do not constitute a limitation on the protection scope of the present invention.

Claims (26)

1. A lime kiln includes a kiln chamber (1), a heating device and a combustion-supporting fan (2). The combustion-supporting fan (2) and the kiln chamber (1) are connected with a combustion-supporting air duct (21) and a combustion-supporting air duct (21) There is a combustion-supporting air shut-off valve (22), the heating device includes a fuel supply device and a spray gun group (3), the spray gun group (3) is connected to the interior of the kiln (1), and the spray gun group (3) has a total of N spray guns (31), characterized in that the fuel supply device includes a gas supply device (4) and a pulverized coal supply device (5), and the gas supply device (4) includes a gas ring pipe (401) and N gas ring pipes (401) Connected gas branch pipes (402), each gas branch pipe (402) is connected to the inlet end of a spray gun (31), the pulverized coal supply device (5) includes pulverized coal ring pipes (501) and N pulverized coal rings The pulverized coal branch pipe (502) connected by the pipe (501), each pulverized coal branch pipe (502) is connected to the inlet end of a spray gun (31), so that the gas supply device (4) and the pulverized coal supply device (5) are shared Spray gun group (3); each gas branch pipe (402) is provided with a gas branch pipe regulating valve (403), and each coal powder branch pipe (502) is provided with a coal powder branch pipe regulating valve (503); the spray gun (31) is provided There is a flow detector (311); the first calorific value detector (404) and the first pressure detector (405) are set on the gas loop pipe (401), and the second calorific value detector is set on the coal powder loop pipe (501) In the kiln (504), there is a second pressure detector (11) inside the kiln (1); the section of the kiln is divided into a number of annular heating areas along the radial direction. The spray gun group (3) includes a number of spray gun matrices, each The spray gun matrix is correspondingly arranged in an annular heating area, and each spray gun matrix includes a plurality of spray guns (31) evenly distributed along the circumference.
2. The lime kiln according to claim 1, characterized in that the spray gun (31) comprises a spray gun body (3101), and both ends of the spray gun body (3101) are respectively provided with a material inlet (3102) and a material outlet (3103) ), the spray gun body (3101) includes an inner tube body (3104) and an outer tube body (3105) sleeved outside the inner tube body (3104). The inner tube body (3104) is provided with an inner fuel channel ( 3106), an annular outer fuel channel (3107) is formed between the inner tube body (3104) and the outer tube body (3105), and a section of the outer tube body (3105) close to the discharge port (3103) is along the axis A plurality of distribution hole groups (3108) are arranged at intervals, and the distribution hole group (3108) includes a plurality of distribution holes (3109) evenly distributed along the circumference, and the distribution holes (3109) are downwardly inclined through holes.
3. The lime kiln according to claim 1 or 2, characterized in that the fuel supply device further comprises N fuel switchers (6), and each fuel switcher (6) includes a gas inlet (61) and a pulverized coal inlet (62) and the fuel outlet (64), the gas inlet (61) is connected with the gas branch pipe (402), the pulverized coal inlet (62) is connected with the pulverized coal branch pipe (502), and the fuel outlet (64) is connected with the inlet of the spray gun (31) The feed port is connected, and the gas inlet (61) and the pulverized coal inlet (62) are respectively equipped with valve bodies (65); the gas supply device (4) also includes a gas conveying fan (406), a gas conveying fan (406) and gas The loop pipe (401) is connected through the gas conveying pipe (407), and the gas conveying pipe (407) is provided with a gas shut-off valve (408); the pulverized coal supply device (5) also includes a pulverized coal conveying fan (505). The fan (505) and the pulverized coal ring pipe (501) are connected through a pulverized coal conveying pipe (506), and the pulverized coal conveying pipe (506) is provided with a pulverized coal shutoff valve (507).
4. The lime kiln according to claim 3, characterized in that the fuel supply device further comprises a nitrogen purging device (7), and the nitrogen purging device (7) includes a nitrogen compression tank (71) and a nitrogen ring pipe (72) , The nitrogen ring pipe (72) is connected with N nitrogen branch pipes (73), the N nitrogen branch pipes (73) are respectively provided with a nitrogen branch pipe regulating valve (74), the nitrogen compression tank (71) and the nitrogen ring pipe (72) pass The nitrogen delivery pipe (75) is connected, and the nitrogen delivery pipe (75) is provided with a nitrogen shut-off valve (76); the fuel switch (6) also includes a nitrogen inlet (63), a nitrogen inlet (63) and a nitrogen branch pipe (73) ) Is connected, the nitrogen inlet (63) is provided with a valve body (65). By adjusting each valve body (65), at the same time, only the gas inlet (61), the pulverized coal inlet (62) and the nitrogen inlet (63) One is connected to the fuel outlet (64); when the nitrogen shut-off valve (76) and the valve body (65) at the nitrogen inlet (63) are opened, the residual gas or coal powder in the fuel switch (6) is blown to In the spray gun (31).
5. The lime kiln according to claim 4, characterized in that the valve body (65) comprises a rigid sealing ring (651), a sealing plug (652) and a return spring (653); the inner center of the fuel switch (6) Equipped with a fixed supporting steel body (66); a rigid sealing ring (651) is fixed on the periphery of the gas inlet (61), coal powder inlet (62) and nitrogen inlet (63) respectively; one end of the return spring (653) It is connected with the supporting steel body (66), and the other end is connected with the sealing plug (652); when the sealing plug (652) receives pressure from the fuel switch (6), the sealing plug (652) and the rigid sealing ring (651) Press tightly to make the valve body (65) in a closed state; when the sealing plug (652) receives pressure from outside the fuel switch (6), the return spring (653) is compressed, and the sealing plug (652) and the rigid seal The ring (651) is separated, leaving the valve body (65) in an open state.
6. The lime kiln according to claim 4 or 5, characterized in that the gas supply device (4) further comprises a gas return pipeline (409), and a gas return valve (410) is provided on the gas return pipeline (409), and the gas return The outlet end of the pipe (409) is connected to the inlet end of the gas conveying fan (406), the inlet end of the gas return pipe (409) is connected to the gas conveying pipe (407), and the inlet end of the gas return pipe (409) is located at the gas cutoff Between the valve (408) and the outlet end of the gas conveying fan (406), when the gas return valve (410) is opened, the gas conveying air circulates between the gas return pipe (409) and the gas conveying fan (406), To release the pressure of the gas conveying fan (406).
7. The lime kiln according to claim 6, characterized in that the pulverized coal supply device (5) further comprises a pulverized coal return pipeline (508), and a pulverized coal return pipeline (508) is provided with a pulverized coal return valve (509), The outlet end of the pulverized coal return pipe (508) is connected with the inlet end of the pulverized coal conveying fan (505), the inlet end of the pulverized coal return pipe (508) is connected with the pulverized coal conveying pipe (506), and the pulverized coal return pipe (508) The inlet end of) is located between the pulverized coal shut-off valve (507) and the outlet end of the pulverized coal conveying fan (505). When the pulverized coal return valve (509) is opened, the pulverized coal conveying air is in the pulverized coal return pipe (508) It circulates with the pulverized coal conveying fan (505) to release the pressure of the pulverized coal conveying fan (505).
8. A method for heating a lime kiln according to claim 1 or 2, characterized in that, the method comprises:

   When the pressure difference between the first pressure detector and the second pressure detector is greater than or equal to the minimum kiln inlet pressure, close N pulverized coal branch pipe control valves, open N gas branch pipe control valves, and make all N spray guns deliver to the kiln chamber Gas fuel

   Heating area average calculation annular gas supply quantity W _ij of each gun, adjust the opening of each of the gas branch pipe control valve, the measuring flow detector and the value S _ij W _ij match;

   When the pressure difference is less than the minimum inlet pressure, calculate the switching number N _m ; N _m is the theoretical number of spray guns that need to switch the fuel medium;

   Close N _x gas branch control valves, correspondingly open N _x pulverized coal branch control valves, so that the fuel delivered by N _x spray guns in the spray gun group is switched from gas to pulverized coal. N _x is the actual number of spray guns that need to switch the fuel medium. N _m ≦N _x ≦N;

   Calculate the fuel supply T _ij of each spray gun in the annular heating area, adjust the opening of the N _x pulverized coal branch control valves and the other NN _x gas branch control valves, so that the measured value S _{ij of the} flow detector is equal to T _ij match;

   Open the combustion-supporting air shut-off valve and increase the operating frequency of the combustion-supporting fan, so that the combustion-supporting air volume entering the kiln matches the total amount of fuel, and the switching process ends.
9. The method according to claim 8, wherein the calculating the number of handovers N _m comprises:

   According to the pressure difference between the first pressure detector and the second pressure detector, calculate the maximum number of gas spray guns N _q allowed in the spray gun group under the current gas loop pressure P ₁ ;

   Calculate the difference between the total number of spray guns N and the maximum number of gas spray guns N _q to obtain the switching number N _m .
10. The method according to claim 9, wherein the maximum number of gas spray guns N _q is calculated according to the following formula:

    

    Wherein, [rho] is the gas density, v _i is the lance gas design flow rate, h _t of gas resistance coefficient of a grommet, h _i is the coefficient of drag gas manifold, P ₁ is the gas loop first pressure detector measurement, P ₂ is the internal pressure of the kiln measured by the second pressure detector, and α is the correction coefficient related to the particle size of the limestone particles in the kiln.
11. The method according to any one of claims 8-10, wherein the method further comprises:

    According to the total number N of spray guns included in the spray gun group and the distribution state of each spray gun on the kiln bore section, a number of uniform heating modes are preset; the uniform heating mode is used to indicate that N _{m is} in the specified value range In the spray gun group, the spray gun position of the fuel medium and the actual spray gun number N _{x in the} spray gun group need to be switched.
12. The method according to claim 11, characterized in that, after calculating the number of handovers N _m , the method further comprises:

    Determine the target uniform heating mode corresponding to the value range of N _m ;

    According to the instruction of the target uniform heating mode, the fuel medium of the N _x spray guns in the corresponding part is switched from coal gas to pulverized coal.
13. The method of claim 11, wherein the method further comprises:

    Label each spray gun in the spray gun group in advance;

    The corresponding relationship between the value range of N _m and the spray gun set is established to obtain a uniform heating mode; the spray gun set includes the labels of N _x spray guns in the spray gun group that need to switch the fuel medium.
14. The method of claim 11, wherein the method further comprises:

    When a number of uniform heating modes are preset, the uniform heating threshold N _{y is determined} ;

    When the value range is (N _y , N), N _x is equal to N, so that the uniform heating mode is a single pulverized coal heating;

    When the value range is (0, N _y ], 0 <N _x ≦ N _y , so that the uniform heating mode is gas and pulverized coal combined heating;

    When the value range is 0, N _x is equal to 0, so that the uniform heating mode is single gas heating.
15. The method according to claim 8, wherein the total amount of heat for heating the annular region Q _i is:

    Q ₁ ＝Q÷δ i=1

    Q _i ＝Q×k _1i /δ 2≤i≤Y

    In the formula, Q ₁ is the total heat supply of the first annular heating area, which is located at the center of the kiln bore; Q is when the material is roasted at a certain height of the kiln bore The required theoretical heat supply; δ is the heat transfer efficiency between the flue gas and the material in the lime kiln; k _1i is the heat supply ratio coefficient between the first annular heating area and the i-th annular heating area; Y is the number of circular heating areas.
16. The method according to claim 15, wherein the average gas supply amount _Wij of each spray gun in the annular heating area is calculated according to the following formula:

    

    Where, Q _i is the total amount of heat for heating the annular region, X _i is the number of guns in the annular heating zone comprises, h ₁ is the gas specific heat value of the first heating value detector is measured, 1 ≦ j ≦ X _i , 1≦i≦Y.
17. The method according to claim 15, wherein the fuel supply amount T _ij of each spray gun in the annular heating area is calculated according to the following formula:

    

    In the formula, M _i is the average for each of the heat gun annular heating zone; Q _i is the total amount of heat for heating the annular region; X _i is the number of guns in the annular heating region comprises; is turned on The spray guns corresponding to the N _x pulverized coal branch control valves, h=h ₂ ; for the corresponding spray guns of the other NN _x gas branch control valves in the open state, h=h ₁ ; where h ₁ is the first heating value The unit calorific value of coal gas measured by the detector, h ₂ is the unit calorific value of pulverized coal measured by the second calorific value detector, 1≦j≦X _i , 1≦i≦Y.
18. A method of heating a lime kiln according to claim 7, wherein the method comprises:

    When the pressure difference between the first pressure detector and the second pressure detector is greater than or equal to the minimum kiln inlet pressure, the single gas heating mode is activated, so that all N spray guns deliver gas fuel to the kiln; the single gas heating mode It is: the valve body at the gas inlet of the gas shut-off valve, the gas conveying fan and the N fuel switchers are all open, and the valve body at the pulverized coal inlet of the pulverized coal shutoff valve and the N fuel switchers are all closed. The pulverized coal conveying fan is in standby state, the nitrogen shut-off valve and the valve bodies at the nitrogen inlet of the N fuel switchers are all closed; the gas return valve is closed, and the pulverized coal return valve is open; N gas branch control valves , N pulverized coal branch control valves and N nitrogen branch control valves are all open;

    Heating area average calculation annular gas supply quantity W _ij of each gun, adjust the opening of each of the gas branch pipe control valve, the measuring flow detector and the value S _ij W _ij match;

    When the pressure difference is less than the minimum inlet pressure, calculate the switching number N _m ; N _m is the theoretical number of spray guns that need to switch the fuel medium;

    Determine the uniform heating mode that needs to be activated. The uniform heating mode is used to indicate when N _{m is} within the specified value range, the position of the spray gun in the spray gun group that needs to switch the fuel medium and the actual number of spray guns N _x , N _m ≦ N _x ≦N;

    After starting the uniform heating mode, calculate the fuel supply T _ij of each spray gun in the annular heating area;

    Adjust the opening degree of the pulverized coal branch pipe regulating valve corresponding to N _x spray guns in the position, and adjust the opening degree of the gas branch pipe regulating valve corresponding to the other NN _x spray guns, so that the measured values S _ij and T of each flow detector _ij match;

    Open the combustion-supporting air shut-off valve and increase the operating frequency of the combustion-supporting fan, so that the combustion-supporting air volume entering the kiln matches the total amount of fuel, and the switching process ends.
19. The method according to claim 18, wherein the method further comprises:

    Determine the uniform heating threshold N _y according to the total number N of spray guns included in the spray gun group and the distribution state of each spray gun on the kiln bore section;

    When the value range is (N _y , N), N _x is equal to N, so that the uniform heating mode is a single pulverized coal heating;

    When the value range is (0, N _y ], 0 <N _x ≦ N _y , so that the uniform heating mode is gas and pulverized coal combined heating;

    When the value range is 0, N _x is equal to 0, so that the uniform heating mode is single gas heating.
20. The method according to claim 19, wherein when the uniform heating mode is a single pulverized coal heating, the uniform heating mode is activated as follows:

    Close the valve body and the gas shut-off valve at the gas inlet of the N fuel switchers in turn, open the gas return valve at the same time, and adjust the gas conveying fan to the standby state;

    Open the nitrogen shut-off valve and the valve body at the nitrogen inlet of the N fuel switchers in sequence. After the nitrogen blows the residual coal powder inside the fuel switcher to the spray gun, close the valve body and the valve body at the nitrogen inlet of the N fuel switchers in turn. Nitrogen shut-off valve;

    Close the pulverized coal return valve and increase the operating frequency of the pulverized coal conveying fan. When the pressure of the pulverized coal reaches the kiln requirement, open the pulverized coal shut-off valve and the valve body at the pulverized coal inlet of the N fuel switchers in order to make the pulverized coal sequentially After passing through the pulverized coal conveying pipeline, the pulverized coal ring pipe, N pulverized coal branch pipes, the pulverized coal inlets and fuel outlets of the N fuel switchers, and the N spray guns, it flows into the kiln, and the uniform heating mode is activated.
21. The method according to claim 19, wherein when the uniform heating mode is gas and pulverized coal combined heating, the uniform heating mode is activated as follows:

    Close remaining NN _x lances corresponding to the pulverized coal pipe branch regulating gas branched valve and a nitrogen gas branch pipe control valve, while closing the parts of the N _x lances corresponding pipe control valve, and closing the portion of the N _x lances corresponding The valve body at the gas inlet in the fuel switch;

    Open the nitrogen shut-off valve and the valve body at the nitrogen inlet of the fuel switch corresponding to the N _x spray guns of the position in sequence. After the nitrogen blows the residual gas inside the fuel switch to the spray gun, close the N _{x of} the position in turn The valve body and nitrogen shut-off valve at the nitrogen inlet of the fuel switch corresponding to each spray gun;

    Close the pulverized coal return valve and increase the operating frequency of the pulverized coal conveying fan. When the pulverized coal pressure reaches the kiln entry requirement, turn on the pulverized coal shut-off valve and the pulverized coal inlet of the fuel switch corresponding to the N _x spray guns in the position in turn The valve body allows the pulverized coal to flow into the kiln chamber through the pulverized coal conveying pipeline, the pulverized coal ring pipe, N _x pulverized coal branch pipes, N _x pulverized coal inlets and fuel outlets of the fuel switcher, and N _x spray guns in sequence .
22. The method according to any one of claims 18-21, wherein the calculating the number of handovers N _m comprises:

    According to the pressure difference between the first pressure detector and the second pressure detector, calculate the maximum number of gas spray guns N _q allowed in the spray gun group under the current gas loop pressure P ₁ ;

    Calculate the difference between the total number of spray guns N and the maximum number of gas spray guns N _q to obtain the switching number N _m .
23. The method according to claim 22, wherein the maximum number of gas spray guns N _q is calculated according to the following formula:

    

    Wherein, [rho] is the gas density, v _i is the lance gas design flow rate, h _t of gas resistance coefficient of a grommet, h _i is the coefficient of drag gas manifold, P ₁ is the gas loop first pressure detector measurement, P ₂ is the internal pressure of the kiln measured by the second pressure detector, and α is the correction coefficient related to the particle size of the limestone particles in the kiln.
24. The method of any of claims 18-21, wherein the total amount of heat for heating the annular region Q _i is:

    Q ₁ ＝Q÷δ i=1

    Q _i ＝Q×k _1i /δ 2≤i≤Y

    In the formula, Q ₁ is the total heat supply of the first annular heating area, which is located at the center of the kiln bore; Q is when the material is roasted at a certain height of the kiln bore The required theoretical heat supply; δ is the heat transfer efficiency between the flue gas and the material in the lime kiln; k _1i is the heat supply ratio coefficient between the first annular heating area and the i-th annular heating area; Y is the number of circular heating areas.
25. The method according to claim 24, wherein the average gas supply amount _Wij of each spray gun in the annular heating area is calculated according to the following formula:

    

    Where, Q _i is the total amount of heat for heating the annular region, X _i is the number of guns in the annular heating zone comprises, h ₁ is the gas specific heat value of the first heating value detector is measured, 1 ≦ j ≦ X _i , 1≦i≦Y.
26. The method according to claim 24, wherein the fuel supply amount T _ij of each spray gun in the annular heating area is calculated according to the following formula:

    

    In the formula, M _i is the average for each of the heat gun annular heating zone; Q _i is the total amount of heat for heating the annular region; X _i is the number of lance comprising an annular heating region; for the site Of N _x spray guns, h=h ₂ , for the other NN _x spray guns, h=h ₁ ; among them, h ₁ is the unit calorific value of the gas measured by the first calorific value detector, and h ₂ is the second calorific value detector The measured unit calorific value of pulverized coal is 1≦j≦X _i , 1≦i≦Y.

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