CN115368937B - Pretreatment device, combustion device and combustion method for low-calorific-value solid fuel - Google Patents
Pretreatment device, combustion device and combustion method for low-calorific-value solid fuel Download PDFInfo
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- CN115368937B CN115368937B CN202210965222.1A CN202210965222A CN115368937B CN 115368937 B CN115368937 B CN 115368937B CN 202210965222 A CN202210965222 A CN 202210965222A CN 115368937 B CN115368937 B CN 115368937B
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/02—Fixed-bed gasification of lump fuel
- C10J3/20—Apparatus; Plants
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/72—Other features
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/72—Other features
- C10J3/82—Gas withdrawal means
- C10J3/84—Gas withdrawal means with means for removing dust or tar from the gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
- F23B90/00—Combustion methods not related to a particular type of apparatus
- F23B90/04—Combustion methods not related to a particular type of apparatus including secondary combustion
- F23B90/06—Combustion methods not related to a particular type of apparatus including secondary combustion the primary combustion being a gasification or pyrolysis in a reductive atmosphere
Abstract
The invention relates to a pretreatment device, a combustion device and a combustion method of low-heat-value solid fuel, which are used for solving the problems of insufficient and unstable combustion and high content of smoke pollutants caused by low heat value and high water content of the conventional low-heat-value solid fuel. The pretreatment device for the low-heating-value solid fuel comprises: the gasification furnace is provided with a feeding port, an air inlet, a material outlet and a material returning port, and part of materials are discharged out of the gasification furnace through the material outlet; the gas-solid separator is provided with a material inlet, a first outlet and a second outlet, the material inlet is communicated with the material outlet so that the material discharged from the material outlet enters the gas-solid separator for gas-solid separation, the separated gas is guided to a downstream device of the pretreatment device through the first outlet, and the separated solid is guided out of the gas-solid separator through the second outlet; and the conveyor is respectively communicated with the second outlet and the material returning port.
Description
Technical Field
The invention relates to the technical field of low-heat-value solid fuel combustion, in particular to a pretreatment device, a combustion device and a combustion method for low-heat-value solid fuel.
Background
A large amount of low-heat-value solid fuel is produced in a large amount of industrial production and agricultural production, the low-heat-value solid fuel is solid fuel with the heat value of 500-3000 Kcal/Kg, and a large amount of environmental pollution is caused because the heat value is low and the traditional combustion device cannot be used for effective combustion and harmless treatment. For example, gasified slag generated by gasification of a gas flow bed in the coal chemical industry cannot be fed into a boiler for effective combustion due to high water content, low heat value and poor activity.
At present, low-heat value solid fuel is generally treated in a landfill mode, land occupation is caused, and the environment is polluted, such as oil sludge generated in the oil exploitation and storage processes, sludge generated by water treatment, biomass and domestic garbage generated in agricultural production and the like.
Disclosure of Invention
In view of the above analysis, the embodiments of the present invention are directed to providing a pretreatment apparatus, a combustion apparatus and a combustion method for low-calorific-value solid fuel, so as to solve the problems of insufficient and unstable combustion and high content of smoke pollutants caused by low calorific value and high water content of the existing low-calorific-value solid fuel.
In one aspect, the present invention provides a pretreatment apparatus for a low heating value solid fuel, comprising:
the gasification furnace is provided with a feeding port and an air inlet so that low-calorific-value solid fuel and a gasifying agent respectively enter the gasification furnace through the feeding port and the air inlet; the feeding port is positioned above the air inlet so as to form internal material circulation in the gasification furnace; the gasification furnace is also provided with a material outlet and a material return port, and part of materials are discharged out of the gasification furnace through the material outlet;
the gas-solid separator is provided with a material inlet, a first outlet and a second outlet, the material inlet is communicated with the material outlet so that the material discharged from the material outlet enters the gas-solid separator for gas-solid separation, the separated gas is guided to a downstream device of the pretreatment device through the first outlet, and the separated solid is guided out of the gas-solid separator through the second outlet;
and the conveyor is respectively communicated with the second outlet and the material returning port so as to convey the solid separated by the gas-solid separator back to the gasification furnace.
Further, the second outlet is communicated with the conveyor through a material returning device.
Further, the gas-solid separator is arranged separately from the gasification furnace;
and a first fluid pipeline is arranged between the gas-solid separator and the material outlet.
Further, the gas-solid separator is coupled with the gasification furnace;
the gas-solid separator is sleeved on the material outlet, and the material inlet is communicated with the material outlet.
Further, the gas-solid separator is a cyclone separator.
Further, the air conditioner is provided with a fan, the gasification furnace is provided with a slag discharge port;
the slag discharge port and the air inlet are positioned at the bottom of the gasification furnace;
the feeding port and the material returning port are positioned in the middle of the gasification furnace, and the feeding port is higher than the material returning port;
the material outlet is positioned at the top of the gasification furnace.
Further, the bottom of the gasification furnace is in a horn shape gradually expanding from bottom to top, the opening angle of the bottom is alpha, the alpha is more than or equal to 15 degrees and less than or equal to 50 degrees, and the ratio of the upper sectional area to the lower sectional area of the bottom is 1.25 to 5.0;
the middle part of the gasification furnace is cylindrical, the diameter of the middle part is equal to the upper diameter of the bottom, and the height-diameter ratio of the middle part is 1 to 3.
Furthermore, the air inlet is provided with an air distribution device;
the air distribution device comprises an air cap and an air chamber; or
The air distribution device comprises a jet air pipe and at least one declination air pipe, the jet air pipe is arranged at the bottom end of the gasification furnace, and the declination air pipe is arranged on the side wall of the bottom of the gasification furnace; the horizontal included angle of the downdip air pipe is beta, and the beta is more than 0 degree and less than or equal to 75 degrees.
In another aspect, the present invention provides a combustion apparatus for a low calorific value solid fuel, comprising:
the above-mentioned pretreatment apparatus;
a furnace comprising at least one nozzle in communication with the first outlet of the pretreatment device;
and the material conveying device is respectively communicated with the combustion furnace and the material returning device of the pretreatment device.
In still another aspect, the present invention provides a method for burning a low calorific value solid fuel, in which the above-mentioned combustion apparatus burns a low calorific value solid fuel by using the burning method, the burning method comprising:
respectively introducing low-calorific-value solid fuel and a gasifying agent into a pretreatment device for treatment through a feeding port and an air inlet, wherein the running air speed at the bottom of a gasification furnace is 4-12 m/s, the running air speed at the middle part of the gasification furnace is 1.5-4 m/s, the gasifying agent is air, or the gasifying agent is a mixed gas of air and water vapor, air and carbon dioxide or air and flue gas, the circulation rate of the pretreatment device is less than 15, a gas-solid separator can collect particles larger than 100 mu m, and the carbon conversion rate of the solid fuel in the gasification furnace is 50-85%;
the low-calorific-value solid fuel is converted into gas fuel and high-temperature solid fuel in a pretreatment device, the gas fuel is conveyed to a nozzle of a combustion furnace for combustion after gas-solid separation, the high-temperature solid fuel is conveyed into the combustion furnace through a material returning device and a material conveying device for combustion, wherein the speed of a central channel nozzle of the nozzle is 20-60 m/s, the speed of a channel nozzle occupied by combustion-supporting air is 45-80 m/s, and the material conveying quantity of the material conveying device accounts for 0-30% of the material quantity collected by the gas-solid separator.
Compared with the prior art, the invention can realize at least one of the following beneficial effects:
(1) The low-calorific-value solid fuel is modified and activated by adopting a gasification pretreatment mode, the low-calorific-value solid fuel is converted into combustible gas fuel and high-temperature solid fuel, and meanwhile, a relatively high-carbon fuel cycle is formed among a gasification furnace, a gas-solid separator and a conveyor, so that the gasification modification and activation are more stable;
(2) The low-heat value solid fuel forms stronger internal circulation and higher heat capacity in the gasification furnace, and the solid fuel escaping from the gasification furnace returns to the gasification furnace through the gas-solid separator and the conveyor, so that the retention time of the solid fuel in the gasification furnace is prolonged, the modification and activation of the low-heat value solid fuel are facilitated, and the operation stability of the gasification furnace is enhanced due to the higher heat capacity;
(3) The low-calorific-value solid fuel combustion device and the method provided by the invention adopt a gasification pretreatment mode, a higher carbon concentration cycle is constructed among a gasification furnace, a gas-solid separator and a conveyor, the low-calorific-value solid fuel is gasified, modified and activated to generate hot gas fuel (namely gas fuel) and hot active solid fuel (namely high-temperature solid fuel), and then the hot gas fuel and the hot active solid fuel are introduced into a combustion furnace for combustion, so that the combustion rate and the combustion efficiency are greatly improved, and the low-calorific-value solid fuel is efficiently combusted;
(4) Through setting up the air distribution device, construct high inner loop, low extrinsic cycle material circulation form and high thermal capacity in the gasifier in preprocessing device, combine gasification pretreatment mode, promote low calorific value solid fuel thermal treatment stability by a wide margin.
In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a schematic diagram showing a configuration of a pretreatment apparatus for a low calorific value solid fuel according to an embodiment;
FIG. 2 is another schematic diagram of the pretreatment apparatus for low calorific value solid fuel according to an embodiment;
FIG. 3 is a schematic view showing still another configuration of a pretreatment apparatus for a low calorific value solid fuel according to an embodiment;
FIG. 4 is a top view of the interior of a cyclone separator in accordance with an embodiment;
fig. 5 is a schematic structural view of a combustion apparatus for a low calorific value solid fuel according to an embodiment.
Reference numerals:
1-gasification furnace; 101-a feed port; 102-an air inlet; 103-material outlet; 104-material returning port; 105-a slag discharge port; 11-air distribution device; 111-jet air duct; 112-downdip air pipe; 12-a communicating tube; 2-gas-solid separator; 21-a guide channel; 201-material inlet; 202-a first outlet; 203-a second outlet; 3-a conveyor; 4-a material returning device; 5-a combustion furnace; 51-a nozzle; 6-a material conveyer.
Detailed Description
The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention and not to limit its scope.
In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly stated or limited, the term "connected" should be interpreted broadly, and may be, for example, a fixed connection, a detachable connection, or an integral connection, which may be a mechanical connection, an electrical connection, which may be a direct connection, or an indirect connection via an intermediate medium. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The terms "top," "bottom," "at ...above," "below," and "at 8230; above" are used throughout the description to refer to the relative positions of the components of the device, such as the relative positions of the top and bottom substrates inside the device. It will be appreciated that the devices are multifunctional, regardless of their orientation in space.
The general working surface of the invention can be a plane or a curved surface, can be inclined or horizontal. For convenience of explanation, the embodiments of the present invention are placed on a horizontal plane and used on the horizontal plane, and are defined as "high and low" and "up and down".
Example one
The embodiment discloses a pretreatment device for low-heating-value solid fuel, as shown in fig. 1 to 4, comprising:
the gasification furnace 1 is provided with a feeding port 101 and an air inlet 102, so that low-calorific-value solid fuel S and a gasifying agent A1 enter the gasification furnace 1 through the feeding port 101 and the air inlet 102 respectively; the feeding port 101 is positioned above the air inlet so as to form internal material circulation in the gasification furnace 1; the gasification furnace 1 is also provided with a material outlet 103 and a material returning opening 104, and part of the material is discharged out of the gasification furnace through the material outlet 103;
the gas-solid separator 2 is provided with a material inlet 201, a first outlet 202 and a second outlet 203, the material inlet 201 is communicated with the material outlet 103, so that the material discharged from the material outlet 103 enters the gas-solid separator 2 from the material inlet 201 for gas-solid separation, the separated gas is guided to a downstream device of the pretreatment device by the first outlet 202 for combustion treatment, and the separated solid is guided out of the gas-solid separator 2 by the second outlet 203;
and the conveyor 3 is respectively communicated with the second outlet 203 and the material return port 104 so as to convey the solids separated by the gas-solid separator 2 back to the gasification furnace 1 for further gasification and activation.
The gasification furnace 1, the gas-solid separator 2 and the conveyor 3 form a low circulation rate circulating fluidized bed, so that the low-calorific-value solid fuel S and the gasifying agent A1 are subjected to combustion, gasification and activation reactions in the gasification furnace, and the high-temperature gas fuel generated by the reactions and the high-temperature solid fuel which cannot be collected by the gas-solid separator are guided to a downstream device through a first outlet; the high-temperature solid fuel collected by the gas-solid separator returns to the gasification furnace through the conveyor to continue gasification and activation reaction.
The internal circulation refers to that the solid materials form the internal circulation with the center upward and the edge downward under the action of gas fluidization. The part of materials comprises the gas fuel generated by gasification and part of the low heating value solid fuel carried by the gas fuel.
According to an optional embodiment of the pretreatment device, the gas-solid separator 2 is communicated with the conveyor 3 through a material returning device 4, that is, the material returning device 4 is respectively communicated with the second outlet 203 and the conveyor 3, and the solid material collected by the gas-solid separator 2 enters the material returning device 4 through the second outlet 203, enters the conveyor 3 through the material returning device 4, and finally returns to the gasification furnace 1 through the conveyor 3.
The material returning device 4 is a U-shaped material returning device or a shallow fluidized bed, and realizes material sealing and material dynamic balance. Preferably, the material returning device 4 distributes part of the solid materials collected by the gas separator 2 to the conveyor 3 to return to the gasification furnace 1, and part of the solid materials are distributed to a downstream device (such as a combustion furnace) to be combusted, and preferably, the material entering the material returning device 4 accounts for 0-30% of the material collected by the gas-solid separator.
The conveyer 3 is a pneumatic solid material conveyer, can be a Venturi conveyer, and can also be a fluidized pneumatic conveyer, and can provide 2-10 kPa inverse pressure difference to ensure that the return feeder 4 and the gas-solid separator 2 operate stably.
The gas-solid separator 2 is a cyclone separator, a cyclone separator or a high-efficiency inertia separator. The gas-solid separator 2 can trap all particles having a particle diameter of more than 100 μm.
According to one embodiment of the pretreatment device, the gas-solid separator 2 is disposed separately from the gasification furnace 1, and specifically, a first fluid pipeline is disposed between the gas-solid separator 2 and the material outlet 103, as shown in fig. 1 to 2.
According to an embodiment of the pretreatment device, the gas-solid separator 2 is coupled to the gasification furnace, specifically, the gas-solid separator 2 is located right above the material outlet 103, the material inlet 201 is directly sleeved outside the material outlet 103, in this case, it is preferable that the gas-solid separator 2 is a cyclone separator, the cyclone separator includes a guide channel 21, the guide channel 21 is located right above the material outlet 103, a communicating pipe 12 is arranged between the guide channel 21 and the material outlet 103, the material led out from the material outlet 103 enters the guide channel 21 through the communicating pipe 12, the solids in the material are thrown to the wall surface of the cyclone separator by centrifugal force formed by the flow field tissue of the guide channel 21, so as to realize gas-solid separation, the gas in the material is guided by a first outlet 202 arranged at the top end of the cyclone separator, the solids in the material are guided by a second outlet 203 arranged at the bottom of the cyclone separator, and the second outlet 203 is located at the lowest point at the bottom of the cyclone separator, so that the solids are collected at the second outlet 203.
The gasification furnace 1 is provided with a slag discharge port 105, and bottom slag generated after the low-calorific-value solid fuel reacts with the gasification agent is discharged out of the gasification furnace 1 through the slag discharge port 105.
It should be noted that the bottom slag and the high-temperature solid fuel have different carbon contents and different particle sizes, so that the bottom slag and the high-temperature solid fuel have different densities and different fluidization characteristics, a separation effect can be realized under the action of the gasification agent, and the bottom slag moves to the bottom and enters a slag discharge port.
The slag discharge opening 105 and the gas inlet 102 are located at the bottom of the gasification furnace 1.
The feed opening 101 and the material returning opening 104 are located in the middle of the gasification furnace, and the feed opening 101 is higher than the material returning opening 104, so that a feed point is ensured to be in a dilute phase area, and the fed material can be rapidly mixed with high-temperature materials instead of being rapidly mixed with the returned materials. The feed port 101 is located in the dilute phase region in the middle of the gasifier 1 to feed the low-heating-value solid fuel into the gasifier 1. The material returning port 104 is connected with the conveyor 3 and is used for receiving the solid materials conveyed by the conveyor 3 and realizing the circulation of the solid materials in the pretreatment device.
The material outlet 103 is located at the top end of the gasification furnace 1 and is connected with the material inlet 201 of the gas-solid separator 2.
The gasification furnace 1 comprises a bottom part, a middle part and an upper part, wherein the bottom part of the gasification furnace 1 is of a hollow round table structure gradually expanding from bottom to top, the included angle between two generatrices of the axial section of the round table is alpha, namely the bottom part of the gasification furnace is in a horn shape gradually expanding from bottom to top, the opening angle of the horn is alpha, alpha is more than or equal to 15 degrees and less than or equal to 50 degrees (preferably, alpha is more than or equal to 25 degrees and less than or equal to 40 degrees), and the ratio of the sectional area of the upper part of the round table to the sectional area of the lower part of the round table is 1.25-5.0 (preferably, 1.5-4.0); the middle part of the gasification furnace 1 is cylindrical, the diameter of the middle part is equal to the upper diameter of the bottom, and the height-diameter ratio of the middle part is 1 to 3; the top of the gasification furnace is of a hollow round table structure which is reduced from bottom to top, namely the top of the gasification furnace is of a horn shape which is gradually enlarged from top to bottom, the diameter of the middle part is equal to the lower diameter of the top, and two ends of the middle part of the gasification furnace 1 are respectively butted with the top and the bottom, namely, preferably, the central axes of the bottom, the middle and the upper part of the gasification furnace 1 are coincided to be the longitudinal central line of the gasification furnace 1.
According to a preferred embodiment of the pretreatment device, the air inlet 102 is provided with an air distribution device 11, the air distribution device 11 is positioned at the bottom end of the gasification furnace 1, and the gasification agent A1 enters the gasification furnace 1 from the air inlet 102 at the bottom of the gasification furnace 1 through the air distribution device 11 to react with the low-calorific-value solid fuel.
The air distribution device converges the gasifying agent A1 to the center of the bottom of the gasification furnace 1, and the gasifying agent A1 is introduced into the gasification furnace 1 through the air inlet 102, and the gasifying agent A1 is air, air and water vapor, air and carbon dioxide or air and flue gas mixed gas, wherein the oxygen concentration is 15-21%.
The air distribution device 11 ensures that the operating air speed at the bottom of the gasification furnace 1 ranges from 4m/s to 12m/s (preferably, 5m/s to 8 m/s), and the operating air speed at the middle part of the gasification furnace 1 ranges from 1.5m/s to 4m/s (preferably, 2m/s to 3 m/s).
In one implementation of the air distribution device 11, as shown in fig. 1 or fig. 3, the air distribution device 11 includes a hood and an air chamber.
In another implementation manner of the air distribution device 11, as shown in fig. 2, the air distribution device 11 includes a jet air pipe 111 and at least one declination air pipe 112, the jet air pipe 111 is disposed at the bottom end of the gasification furnace 1, and the declination air pipe 112 is disposed on the side wall of the bottom of the gasification furnace 1, so that the mixing and reaction between the internal circulation and the gas-solid of the low-calorific-value solid fuel in the gasification furnace 1 can be strengthened. The horizontal included angle of the downdip air pipe is beta, beta is more than 0 degree and less than or equal to 75 degrees (preferably, beta is more than or equal to 10 degrees and less than or equal to 50 degrees). At this time, the bottom slag Z1 generated in the gasification furnace 1 flows downward from the gap between the jet flow duct 111 and the bottom of the gasification furnace 1.
The number and the number of the declined air pipes 112 may be set according to actual conditions, and preferably, the plurality of declined air pipes 112 have the same structure and the same angle β, and are uniformly arranged on the sidewall of the bottom of the gasification furnace 1 in an enclosing manner.
Preferably, different gasifying agents are introduced from the jet flow air pipe 111 and the declination air pipe 112, gasifying agent A1-1 is introduced from the jet flow air pipe 111, and gasifying agent A1-2 is introduced from the declination air pipe 112, wherein the gasifying agent A1-1 is air; the gasifying agent A1-2 is air, air and steam, air and carbon dioxide, or air and flue gas mixed gas, wherein the concentration of oxygen is 15% -21%.
Preferably, the jet air pipe 111 has a jet air speed of 30-60 m/s, and the declined air pipe 112 has a jet air speed of 20-45m/s.
In order to ensure the treatment effect of the pretreatment device on the low-calorific-value solid fuel, the circulating fluidized bed consisting of the gasification furnace 1, the gas-solid separator 2 and the conveyor 3 has a circulating multiplying factor of less than 15, preferably, the circulating multiplying factor is more than or equal to 4 and less than or equal to 10.
The carbon conversion of the solid fuel in the gasification furnace 1 is 50% to 85%, preferably 60% to 80%, by the temperature, residence time, etc. of the gasification reaction.
Example two
The present embodiment provides a combustion apparatus for a low heating value solid fuel, as shown in fig. 5, including:
the pretreatment device provided by the first embodiment;
a burner 5 comprising at least one nozzle 51 communicating with a first outlet of said pretreatment device;
and a material carrier 6 which is respectively communicated with the combustion furnace 5 and the pretreatment device so as to lead part of high-temperature solid fuel in the pretreatment device into the combustion furnace 5 through the material carrier 6 for combustion.
Specifically, when the pretreatment device comprises a return feeder 4, the inlet of the material conveyer 6 is connected with the bottom of the return feeder 4, and the outlet of the material conveyer 6 is communicated with the combustion furnace 5; when the pretreatment device does not comprise the return feeder 4, the inlet of the material conveyer 6 is connected with the bottom of the gas-solid separator 2, and the outlet of the material conveyer 6 is communicated with the combustion furnace 5. Part of the solid material separated by the gas-solid separator 2 (namely the high-temperature solid fuel trapped by the gas-solid separator 2) returns to the gasification furnace, and part of the solid material is transported to the combustion furnace 5 for combustion, preferably, the material transported to the combustion furnace 5 accounts for 0-30% of the material trapped by the gas-solid separator.
The combustion furnace 5 is provided with a feed inlet connected with a material conveyer 6. Preferably, the feed inlet is located at the lower portion of the nozzle 51.
The combustion furnace 5 is one of a circulating fluidized bed combustion furnace, a pulverized coal furnace, a rotary kiln and a cyclone furnace.
The material conveying device 6 is one or the combination of a pneumatic conveying device and a screw feeder.
The nozzle 51 is a coaxial multi-channel nozzle, at least one channel being able to be used for injecting combustion air A2, so that the gaseous fuel is fully combusted at the nozzle, at least one channel being in communication with the first outlet 202. The nozzle can be a two-channel nozzle or a three-channel nozzle. The combustion-supporting air is air.
When the number of the passages of the nozzle 51 exceeds three, a central passage is included, and the remaining passages are surrounded outside the central passage, and the central passage communicates with the first outlet.
Preferably, the speed of the nozzle 51 at the nozzle opening of the channel communicated with the first outlet 202 is 20m/s to 60m/s, and the speed of the nozzle 51 at the nozzle opening of the channel provided with the combustion-supporting air is 45m/s to 80m/s.
The burner may be provided with one nozzle 51 or with two nozzles 51, the two nozzles 51 preferably being arranged in a counterpulsation.
The combustion furnace 5 can be connected with a plurality of pretreatment devices, the pretreatment devices are connected with nozzles on the combustion furnace, the nozzles can be arranged in one layer or a plurality of layers, the central line of the nozzle arranged in each layer is on the same horizontal plane, the nozzles in the same layer can be arranged in a hedging way, and can also be arranged in a tangent circle.
In addition, the bottom of the combustion furnace 5 is provided with a slag outlet for discharging slag Z2, and the top or top of the side wall of the combustion furnace 5 is provided with a smoke outlet for discharging smoke F.
EXAMPLE III
The embodiment provides a combustion method of a low-heating-value solid fuel, and the combustion device provided by the embodiment two can be used for combusting the low-heating-value solid fuel by using the combustion method, and the combustion method comprises the following steps:
respectively introducing low-calorific-value solid fuel and a gasifying agent into a pretreatment device for treatment through a feeding port and an air inlet, wherein the running air speed at the bottom of a gasification furnace is 4-12 m/s, the running air speed at the middle part of the gasification furnace is 1.5-4 m/s, the gasifying agent is air, or the gasifying agent is a mixed gas of air and water vapor, air and carbon dioxide or air and flue gas, the circulation rate of the pretreatment device is less than 15, a gas-solid separator can collect particles larger than 100 mu m, and the carbon conversion rate of the solid fuel in the gasification furnace is 50-85%;
the low-calorific-value solid fuel is converted into gas fuel and high-temperature solid fuel in the pretreatment device, the gas fuel is transported to a nozzle of a combustion furnace by a gas-solid separator for combustion, the high-temperature solid fuel is transported to the combustion furnace by a material returning device and a material transporting device for combustion, wherein the speed of a central channel nozzle of the nozzle is 20-60 m/s, the speed of a channel nozzle occupied by combustion-supporting air is 45-80 m/s, and the material transporting quantity of the material transporting device accounts for 0-30% of the material quantity collected by the gas-solid separator.
The combustion method comprises the steps of firstly adopting a fluidized bed gasification mode to improve the volume heat load of the pretreatment device and the carbon concentration in the pretreatment device, modifying and activating the low-calorific-value solid fuel, converting the solid fuel into combustible gas fuel and high-temperature solid fuel, simultaneously improving the volume heat load of the pretreatment device through the gasification mode, and constructing a relatively high carbon fuel cycle among the gasification furnace, the gas-solid separator, the material returning device and the conveyer through the fluidized bed mode to enable gasification modification and activation to be more stable. The solid materials form stronger internal circulation and higher heat capacity in the gasification furnace through the structure of the gasification furnace and the air distribution mode, the gas agent A1 fluidizes the materials gathered to the bottom through the air distribution device to form the internal circulation of the materials with the center upward and the side wall downward, and the circulation multiplying factor of a circulating fluidized bed consisting of a gasification pretreatment hearth, a gas-solid separator, a material returning device and a conveyor is less than 15. Then the gas fuel and the high-temperature solid fuel generated by the pretreatment device and the combustion improver are fully combusted in the combustion furnace through the nozzle, specifically, the low-calorific-value solid fuel is converted into the gas fuel and the high-temperature solid fuel in the pretreatment device, the high-temperature solid fuel which is not collected by the gas fuel and the gas-solid separator is transported to the nozzle of the combustion furnace for combustion, and a part of the high-temperature solid fuel which is collected by the gas-solid separator is returned to the gasification furnace through the material returning device and the transport device for continuous gasification and activation; the other part is transported to the combustion furnace through the material transporting device 6 for combustion. Wherein the proportion of the high-temperature solid fuel conveyed to the combustion furnace by the material conveyer for combustion accounts for 0 to 30 percent of the material amount collected by the gas-solid separator.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (4)
1. A method for combusting low-heating-value solid fuel, which is characterized by being realized by a combustion device for low-heating-value solid fuel, wherein the combustion device comprises:
a pretreatment device;
a burner comprising at least one nozzle in communication with a first outlet of the pretreatment device;
the material conveying device is respectively communicated with the combustion furnace and the material returning device of the pretreatment device;
wherein the preprocessing device comprises:
the gasification furnace is provided with a feeding port and an air inlet so that low-calorific-value solid fuel and a gasifying agent respectively enter the gasification furnace through the feeding port and the air inlet; the feeding port is positioned above the air inlet so as to form material internal circulation in the gasification furnace; the gasification furnace is also provided with a material outlet and a material return port, and part of the material is discharged out of the gasification furnace through the material outlet; the gasification furnace is also provided with a slag discharge port; the slag discharge port and the air inlet are positioned at the bottom of the gasification furnace; the feeding port and the return port are positioned in the middle of the gasification furnace, and the feeding port is higher than the return port; the material outlet is positioned at the top of the gasification furnace; the bottom of the gasification furnace is in a horn shape gradually expanding from bottom to top, the opening angle of the bottom is alpha, alpha is more than or equal to 15 degrees and less than or equal to 50 degrees, and the ratio of the upper sectional area to the lower sectional area of the bottom is 1.25 to 5.0; the middle part of the gasification furnace is cylindrical, the diameter of the middle part is equal to the upper diameter of the bottom, and the height-diameter ratio of the middle part is 1 to 3;
the gas-solid separator is provided with a material inlet, a first outlet and a second outlet, the material inlet is communicated with the material outlet so that the material discharged from the material outlet enters the gas-solid separator for gas-solid separation, the separated gas is guided to a downstream device of the pretreatment device through the first outlet, and the separated solid is guided out of the gas-solid separator through the second outlet;
the conveyer is respectively communicated with the second outlet and the material returning port so as to transport the solids separated by the gas-solid separator back to the gasification furnace;
the gasification furnace, the gas-solid separator and the conveyor form a circulating fluidized bed with the circulating multiplying power less than 15, so that the low-calorific-value solid fuel and the gasification agent are subjected to combustion, gasification and activation reactions in the gasification furnace, high-temperature gas fuel generated by the reaction and high-temperature solid fuel which cannot be collected by the gas-solid separator are guided to a downstream device through the first outlet, and the high-temperature solid fuel collected by the gas-solid separator returns to the gasification furnace through the conveyor to be subjected to gasification and activation reactions;
the gas-solid separator is positioned right above the material outlet, and the material inlet is sleeved outside the material outlet; the gas-solid separator is a cyclone separator, the cyclone separator comprises a guide channel, the guide channel is positioned right above the material outlet, a communicating pipe is arranged between the guide channel and the material outlet, the material led out from the material outlet enters the guide channel through the communicating pipe, the solid in the material is thrown to the wall surface of the cyclone separator by centrifugal force formed by flow field tissue of the guide channel so as to realize gas-solid separation, the gas in the material is led out by a first outlet arranged at the top end of the cyclone separator, the solid in the material flow is led away by a second outlet arranged at the bottom of the cyclone separator, and the second outlet is positioned at the lowest point of the bottom of the cyclone separator so as to be collected at the second outlet;
the combustion method comprises the following steps:
respectively introducing low-calorific-value solid fuel and a gasifying agent into a pretreatment device for treatment through a feeding port and an air inlet, wherein the running air speed at the bottom of a gasification furnace is 4-12 m/s, the running air speed at the middle part of the gasification furnace is 1.5-4 m/s, the gasifying agent is air, or the gasifying agent is a mixed gas of air and water vapor, air and carbon dioxide or air and flue gas, the circulation rate of the pretreatment device is less than 15, a gas-solid separator can collect particles larger than 100 mu m, and the carbon conversion rate of the solid fuel in the gasification furnace is 50-85%;
the low-calorific-value solid fuel is converted into gas fuel and high-temperature solid fuel in the pretreatment device, the gas fuel is conveyed to a nozzle of a combustion furnace for combustion after gas-solid separation, the high-temperature solid fuel is conveyed into the combustion furnace for combustion through a material returning device and a material conveying device, wherein the speed of a central channel nozzle of the nozzle is 20-60 m/s, the speed of a channel nozzle occupied by combustion-supporting air is 45-80 m/s, and the material conveying quantity of the material conveying device accounts for 0-30% of the material quantity collected by the gas-solid separator.
2. The combustion method of claim 1, wherein the second outlet is in communication with the conveyor via a return feeder.
3. The combustion method as claimed in claim 2, wherein the gas-solid separator is provided separately from the gasifier;
and a first fluid pipeline is arranged between the gas-solid separator and the material outlet.
4. The combustion method as claimed in claim 1, wherein the air inlet is provided with an air distribution device;
the air distribution device comprises an air cap and an air chamber; or
The air distribution device comprises a jet air pipe and at least one declination air pipe, the jet air pipe is arranged at the bottom end of the gasification furnace, and the declination air pipe is arranged on the side wall of the bottom of the gasification furnace; the horizontal included angle of the downdip air pipe is beta, and the beta is more than 0 degree and less than or equal to 75 degrees.
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