A system and method for using biomass as a substitute fuel in a cement kiln

Abstract

The present invention discloses a system and method for using biomass as an alternative fuel in a cement kiln. The system includes a fuel combined storage workshop, a primary drying device, a secondary drying homogenization bin, and a decomposition furnace. The method comprises the following steps: small-particle-size biomass fuel enters the primary drying device, and flue gas at 80-130 °C is used as a heat source to heat and dry the biomass fuel; the biomass fuel enters the secondary drying homogenization bin, and flue gas at 80-130 °C is used as a heat source to heat and dry the biomass fuel. The flue gas is blown in vertically upward from the bottom and exchanges heat countercurrently with the downward biomass fuel. The present invention uses waste heat to perform two-stage drying on the biomass alternative fuel, fully recovers heat energy, the fuel moisture removal rate can reach 15-80%, and the calorific value is significantly increased; a material homogenization process is provided, and the composition fluctuation of the material after homogenization is smaller, which is beneficial to the stability of the thermal system of the cement kiln.

Description

Technical Field

[0001] The present invention belongs to the field of energy conservation, carbon reduction and environmental protection, and specifically relates to a system and method for using biomass as a substitute fuel in a cement kiln. Background Art

[0002] At the present stage, biomass substitute fuels in China generally exhibit characteristics such as high moisture content, low calorific value, and large fluctuations in composition. When burning, there are problems such as non-concentrated flames, poor stability, and high alkaline substance content leading to preheater clinkerization, which affect the normal operation of the cement kiln system and cannot achieve large-scale and large-ratio applications. Summary of the Invention

[0003] Aiming at the problems that biomass substitute fuels affect the production operation of the cement kiln system and cannot achieve large-scale and large-ratio applications at the present stage, the present invention provides a system and method for using biomass as a substitute fuel in a cement kiln, which can realize large-scale and large-ratio utilization of biomass fuels while not affecting the normal operation of the cement kiln system and is suitable for large-scale industrial promotion and use.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A system for using biomass as a substitute fuel in a cement kiln includes a fuel combined storage workshop. The fuel combined storage workshop is connected to a primary drying device through a second conveying and metering component. The primary drying device is connected to a first waste heat flue gas channel, and the primary drying device is connected to a secondary drying and homogenizing bin. The secondary drying and homogenizing bin is connected to a second waste heat flue gas channel. The secondary drying and homogenizing bin is connected to a third conveying and metering component. The third conveying and metering component is connected to a fourth conveying component. The fourth conveying component is respectively connected to a decomposition furnace and a pre-combustion furnace, and the pre-combustion furnace is connected to the decomposition furnace.

[0006] Further, the fuel combined storage workshop includes a crusher, a large-particle-size biomass fuel pit, and a small-particle-size biomass fuel pit. The inlet of the crusher is connected to a first feeding bin, and the outlet of the crusher is connected to the small-particle-size biomass fuel pit.

[0007] Further, the fuel combined storage workshop includes an intelligent grab crane. The intelligent grab crane is located at the top and is equipped with a coarse material grab and a bulk material grab. A spray dust removal device is connected to the top of the fuel combined storage workshop.

[0008] Further, both the primary drying device and the secondary drying and homogenizing bin are connected to a dust collector through pipelines. The dust collector is connected to a chimney through a centrifugal fan and pipelines.

[0009] Further, the second conveying and metering assembly includes a second screw conveyor and a second metering feeder. The inlet of the second screw conveyor is connected to the second feeding bin, the outlet of the second screw conveyor is connected to the second metering feeder, and the second metering feeder is connected to the primary drying device.

[0010] Further, the top of the secondary drying and homogenizing bin is provided with a downward feeding port, and the bottom of the secondary drying and homogenizing bin is provided with an upward air inlet.

[0011] Further, the third conveying and metering assembly includes a third screw conveyor and a third metering feeder. The inlet of the third screw conveyor is connected to the secondary drying and homogenizing bin, the outlet of the third screw conveyor is connected to the third metering feeder, and the third metering feeder is connected to the fourth conveying assembly.

[0012] Further, the fourth conveying assembly includes a fourth screw conveyor. A fourth gate valve is provided at the outlet end of the fourth screw conveyor, and a fifth gate valve is provided between the pre - combustion furnace and the decomposition furnace.

[0013] A method for a cement kiln to utilize biomass as a substitute fuel, using the above - mentioned system, includes the following steps:

[0014] Step ①, the biomass fuel is fed into the fuel combined storage workshop and classified according to the incoming particle size.

[0015] Step ②, the large - particle - size biomass fuel is crushed into small - particle - size biomass fuel.

[0016] Step ③, the small - particle - size biomass fuel is conveyed through the second conveying and metering assembly and enters the primary drying device. The flue gas at 80 - 130 °C in the first waste heat flue gas channel is used as a heat source to heat and dry the biomass fuel.

[0017] Step ④, the biomass fuel after primary drying enters the secondary drying and homogenizing bin. The flue gas at 80 - 130 °C in the second waste heat flue gas channel is used as a heat source to heat and dry the biomass fuel. The flue gas is blown in vertically upward from the bottom and counter - currently exchanges heat with the downward biomass fuel.

[0018] Step ⑤, the biomass fuel after secondary drying is successively conveyed through the third conveying and metering assembly and the fourth conveying assembly, and is fed into the pre - combustion furnace or the decomposition furnace according to the different utilization amounts of the biomass fuel. When the utilization amount is low and the heat substitution rate of the decomposition furnace < 30%, the biomass fuel can directly enter the decomposition furnace for incineration. When the utilization amount is high and the heat substitution rate of the decomposition furnace ≥ 30%, the biomass fuel enters the pre - combustion furnace for incineration. The biomass fuel completely burns in the pre - combustion furnace, and the generated high - temperature flue gas enters the decomposition furnace. The fuel fly ash enters the decomposition furnace to participate in the production of cement clinker, achieving the effect of saving coal.

[0019] Further, in step ①, the particles are classified according to whether the particle size is greater than or less than 100 mm, and enter the large particle size biomass fuel pit or the small particle size biomass fuel pit respectively;

[0020] Step ②, the large-particle biomass fuel is sent into the first feeding bin through the coarse material grab in the intelligent grab crane, and is crushed to a particle size of less than 100 mm by the crusher below, and then enters the small-particle biomass fuel pit for storage;

[0021] Step ③, the small-size biomass fuel is fed into the second feeding bin through the bulk material grab in the intelligent grab crane, unloaded through the second screw conveyor below and metered by the second quantitative feeder before entering the primary drying device;

[0022] In steps ③ and ④, the outlet exhaust gas from the primary drying device and the secondary drying and homogenizing bin is collected and purified by the dust collector and then discharged into the chimney into the atmosphere;

[0023] Step ⑤, the biomass fuel after secondary drying is unloaded through the third screw conveyor, and then after being measured by the third quantitative feeder, it is conveyed to the fourth screw conveyor, and fed into the precombustion furnace or the decomposition furnace according to the different utilization amounts of the biomass fuel; by opening or closing the fifth gate valve between the precombustion furnace and the decomposition furnace, the online-offline switching of the system and the cement kiln system can be realized.

[0024] Beneficial effects of the present invention:

[0025] 1. The process of the present invention is simple, the scheme is economical and feasible, and it is suitable for industrial production.

[0026] 2. The present invention utilizes the waste heat of the original cement kiln system to dry the biomass alternative fuel in two stages, fully recovering the heat energy. The water removal rate of the biomass alternative fuel after two stages of drying can reach 15-80%. The calorific value is significantly improved, which can greatly increase the subsequent alternative fuel dosage.

[0027] 3. The present invention is provided with a material homogenization process. After homogenization, the fluctuation of material composition is smaller, which solves the problem of unstable calorific value when entering the kiln later and is beneficial to the stability of the thermal system of the cement kiln.

[0028] 4. The present invention adopts a two-stage drying and homogenizing bin, which has the function of homogenizing while drying the materials, thus reducing equipment investment.

[0029] 5. The present invention feeds the biomass alternative fuel into the pre-combustion furnace or the decomposition furnace of the original cement kiln system according to the difference between the utilization amount of biomass alternative fuel and the heat substitution rate of the decomposition furnace. The enterprise can reasonably choose the route into the kiln according to its own production situation, accurately and reasonably allocate it, act according to the circumstances, save energy consumption, and has good adaptability.

[0030] 6. The present invention is equipped with a precalciner and a pre - combustor. Biomass alternative fuels with a relatively high utilization rate and a heat substitution rate in the precalciner ≥ 30% are fed into the pre - combustor for incineration, which can reduce the impact on the original system and enable the online - offline switching between this system and the original cement kiln system, solving the problem of inconsistent maintenance cycles between the pre - combustor and the cement kiln system.

[0031] 7. The present invention reasonably classifies and stores the incoming biomass fuels according to particle size, and sets storage pits for large - and small - particle - size biomass fuels for classified storage, effectively reducing crushing energy consumption.

[0032] 8. Practical data show that by adopting the solution of the present invention, for a typical 5000t / d cement clinker production line, the heat substitution rate of biomass fuels in the precalciner can reach more than 80%.

[0033] The main solution of the present invention and its various further alternative solutions can be freely combined to form multiple solutions, all of which are solutions that can be adopted and claimed by the present invention; and among the present invention, (each non - conflicting option) options and other options can also be freely combined. Those skilled in the art can understand that there are various combinations according to the prior art and common general knowledge after understanding the solution of the present invention, all of which are the technical solutions to be protected by the present invention, and are not enumerated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural diagram of the present invention.

[0035] In the figure: 1 - fuel combined storage workshop, 2 - intelligent grab crane, 3 - first feed bin, 4 - crusher, 5 - second feed bin, 6 - second screw conveyor, 7 - second metering feeder, 8 - primary drying device, 9 - dust collector, 10 - secondary drying and homogenizing bin, 11 - third screw conveyor, 12 - third metering feeder, 13 - fourth screw conveyor, 14 - fourth gate valve, 15 - pre - combustor, 16 - fifth gate valve, 17 - spray dust removal device, 18 - rotary kiln, 19 - precalciner, 20 - first waste heat flue gas channel, 21 - second waste heat flue gas channel, 22 - large - particle - size biomass fuel pit, 23 - small - particle - size biomass fuel pit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The following non - restrictive embodiments are used to illustrate the present invention.

[0037] Embodiment 1:

[0038] Reference Figure 1As shown in the figure, a system for a cement kiln to use biomass as a substitute fuel includes a fuel combined storage workshop 1, a second conveying and metering assembly, a primary drying device 8, a dust collector 9, a secondary drying and homogenizing silo 10, a third conveying and metering assembly, a fourth conveying assembly, and a pre - combustion furnace 15. The rotary kiln 18 and the decomposition furnace 19 are the original cement kiln system, and the decomposition furnace 19 is connected to the end of the rotary kiln 18.

[0039] Inside the fuel combined storage workshop 1, there are an intelligent grab crane 2, a first feeding bin 3, a crusher 4, a spray dust removal device 17, a large - particle - size biomass fuel pit 22, and a small - particle - size biomass fuel pit 23. The second conveying and metering assembly includes a second feeding bin 5, a second screw conveyor 6, and a second metering feeder 7. The third conveying and metering assembly includes a third screw conveyor 11 and a third metering feeder 12, and the fourth conveying assembly includes a fourth screw conveyor 13.

[0040] The intelligent grab crane 2 is located at the top. The intelligent grab crane 2 is equipped with a coarse - material grab and a bulk - material grab, which can respectively grab and place large - particle - size and small - particle - size biomass substitute fuels. The spray dust removal device 17 is connected to the top of the fuel combined storage workshop 1 to perform spray dust reduction in the workshop.

[0041] The large - particle - size biomass fuel pit 22 is used to store large - particle - size biomass fuels (particle size greater than 100 mm), and the small - particle - size biomass fuel pit 23 is used to store small - particle - size biomass fuels (particle size less than 100 mm). The inlet of the crusher 4 is connected to the first feeding bin 3, and the outlet of the crusher 4 is connected to the small - particle - size biomass fuel pit 23. The large - particle - size biomass fuel can be grabbed by the coarse - material grab of the intelligent grab crane 2 and placed into the first feeding bin 3, and then crushed into small - particle - size biomass fuels by the crusher 4.

[0042] The inlet of the second screw conveyor 6 is connected to the second feeding bin 5, the outlet of the second screw conveyor 6 is connected to the second metering feeder 7, and the second metering feeder 7 is connected to the primary drying device 8. The small - particle - size biomass fuel is grabbed by the bulk - material grab of the intelligent grab crane 2 and placed into the second feeding bin 5, and the second screw conveyor 6 and the second metering feeder 7 are used to measure and convey the biomass material.

[0043] The primary drying device 8 is connected to the first waste heat flue gas channel 20. The primary drying uses the waste heat flue gas from the cement kiln head, kiln tail, or a mixture of both as the drying heat source. The flue gas exchanges heat with the biomass fuel to achieve heating and dehydration. The primary drying device 8 is connected to the secondary drying and homogenizing silo 10, and the secondary drying and homogenizing silo 10 is connected to the second waste heat flue gas channel 21. The secondary drying uses the waste heat flue gas from the cement kiln head, kiln tail, or a mixture of both as the drying heat source. The flue gas exchanges heat with the biomass fuel to achieve heating and dehydration.

[0044] At the top of the secondary drying and homogenizing bin 10, there is a downward feed inlet, and at the bottom of the secondary drying and homogenizing bin 10, there is an upward air inlet. The flue gas moves vertically upward and exchanges heat countercurrently with the fuel moving downward, which can greatly improve the material drying efficiency and reduce the moisture content of the material. In addition, due to the relatively light biomass fuel, the upward hot flue gas will have a pneumatic stirring effect on the material, causing the material to be suspended and dispersed inside the bin, making the material in the bin more evenly dispersed. The secondary drying and homogenizing bin 10 can have the function of material homogenization while drying the material, and also has the basic function of material buffer storage.

[0045] Both the primary drying device 8 and the secondary drying and homogenizing bin 10 are connected to the dust collector 9 through pipelines. The dust collector 9 is connected to the chimney through a centrifugal fan and pipelines. After the waste gas generated from the two-stage drying is dust-removed and purified by the bag-type dust collector, it is discharged into the atmosphere by merging into the original kiln head and kiln tail chimneys, without adding new flue gas emission points.

[0046] The inlet of the third screw conveyor 11 is connected to the secondary drying and homogenizing bin 10, and the outlet of the third screw conveyor 11 is connected to the third metering feeder 12. The third metering feeder 12 is connected to the fourth screw conveyor 13. After the biomass fuel after secondary drying passes through the transportation and metering of the third screw conveyor 11 and the third metering feeder 12 in sequence, it enters the fourth screw conveyor 13.

[0047] The fourth screw conveyor 13 conveys the biomass material, and a fourth gate valve 14 is provided at the outlet end of the fourth screw conveyor 13 to control the opening and closing of the outlet through the fourth gate valve 14. The fourth screw conveyor 13 is respectively connected to the decomposition furnace 19 and the pre-combustion furnace 15, and is fed into the pre-combustion furnace 15 or the decomposition furnace 19 of the original cement kiln system for incineration according to the different utilization amounts of the biomass fuel.

[0048] The pre-combustion furnace 15 is connected to the decomposition furnace 19, and a fifth gate valve 16 is provided between the pre-combustion furnace 15 and the decomposition furnace 19. By opening or closing the fifth gate valve, the online-offline switching of this system and the original cement kiln system can be realized.

[0049] Example 2:

[0050] A method for a cement kiln to use biomass as a substitute fuel, adopting the above-mentioned system for a cement kiln to use biomass as a substitute fuel, includes the following steps:

[0051] Step ①, the biomass fuel is fed into the fuel combined storage workshop 1 and classified according to whether the incoming particle size is greater than or less than 100 mm, and enters the large particle size biomass fuel pit 22 or the small particle size biomass fuel pit 23 respectively. The types of biomass fuel include one or more, and its incoming particle size < 500 mm and moisture content ≤ 80%.

[0052] Step ②, the large-particle biomass fuel is sent into the first feeding bin 3 through the coarse material grab in the intelligent grab crane 2, and is crushed to a particle size of less than 100 mm by the crusher 4 below, and then enters the small-particle biomass fuel pit 23 for storage.

[0053] Step ③, the small-size biomass fuel is fed into the second feeding bin 5 through the bulk material grab in the intelligent grab crane 2, and enters the primary drying device 8 after being unloaded by the second screw conveyor 6 below and metered by the second quantitative feeder 7. The flue gas at 80-130°C in the first waste heat flue gas channel 20 is used as a heat source, and the waste heat flue gas from the cement kiln head, kiln tail, or a mixture of the two is used to heat and dry the biomass fuel. The moisture removal rate of the biomass fuel after primary drying can reach 10-50%.

[0054] In step ④, the biomass fuel after primary drying enters the secondary drying and homogenizing bin 10, and the flue gas at 80-130°C in the second waste heat flue gas channel 21 is used as a heat source. The waste heat flue gas from the cement kiln head, kiln tail, or a mixture of the two is used to heat and dry the biomass fuel. The flue gas is vertically blown upward through the bottom and performs countercurrent heat exchange with the downward biomass fuel, which can greatly improve the material drying efficiency and reduce the moisture content of the material.

[0055] In addition, since biomass fuel is relatively light, the upward hot flue gas will pneumatically stir the material, causing the material to be suspended and dispersed inside the silo, making the material in the silo more evenly dispersed. The secondary drying and homogenizing silo 10 can have the function of homogenizing the material while drying it, and it also has a basic material buffer storage function.

[0056] After secondary drying, the water removal rate of the fuel can reach 5-30%, and the calorific value is significantly improved, which can greatly increase the subsequent alternative fuel dosage. Whether to inject hot flue gas can be flexibly selected according to the moisture content of the material after primary drying. In addition, the composition fluctuation of the material is smaller after homogenization, which can solve the problem of unstable calorific value when entering the kiln later, which is beneficial to the stability of the thermal system of the cement kiln.

[0057] In steps ③ and ④, the outlet exhaust gas from the primary drying device 8 and the secondary drying and homogenizing bin 10 is collected and purified by the dust collector 9 and then discharged into the chimney into the atmosphere.

[0058] Step ⑤, the biomass fuel after secondary drying is discharged through the third screw conveyor 11, and then after being measured by the third quantitative feeder 12, it is conveyed to the fourth screw conveyor 13, and fed into the pre-combustion furnace 15 or the decomposition furnace 19 according to the different utilization amounts of the biomass fuel. The outlet end of the fourth screw conveyor 13 is controlled by the fourth gate valve 14 to open and close the outlet.

[0059] When the utilization amount is low and the heat substitution rate of the decomposition furnace < 30%, the biomass fuel can directly enter the decomposition furnace 19 for incineration; when the utilization amount is high and the heat substitution rate of the decomposition furnace ≥ 30%, the biomass fuel enters the pre - combustion furnace 15 for incineration. The biomass fuel is completely burned in the pre - combustion furnace 15, and the generated high - temperature flue gas enters the decomposition furnace 19. The fuel fly ash enters the decomposition furnace 19 to participate in the production of cement clinker, achieving the effect of saving coal.

[0060] By opening or closing the fifth gate valve 16 between the pre - combustion furnace 15 and the decomposition furnace 19, the online - offline switching of this system and the cement kiln system can be realized, meeting the differential requirements between the maintenance cycles of the biomass incineration system and the cement kiln system, and solving the problem of asynchronous maintenance cycles between the pre - combustion furnace and the cement kiln.

[0061] The spray dust removal device 17 is connected to the fuel combined storage workshop 1 and sprays at the top. While effectively reducing the dust in the workshop, it also takes into account the requirements of the workshop fire protection system, effectively ensuring the safe production of the system.

[0062] Example 3:

[0063] A method for a cement kiln to use biomass to replace fuel includes the following steps:

[0064] In step ①, straw with a particle size of 120 mm and a moisture content of 50% is sent to the large - particle - size biomass fuel pit 22 in the fuel combined storage workshop 1. In step ②, the straw is crushed to a particle size of 50 mm by the crusher 4 and enters the small - particle - size biomass fuel pit 23. In step ③, using the waste heat flue gas from the kiln head as the heat source, the inlet flue gas temperature is set at 120 °C, and after drying, the moisture content of the straw is reduced from 50% to 25%. In step ④, using the mixed waste heat flue gas from the kiln head and the kiln tail of the cement kiln as the heat source, the inlet flue gas temperature is set at 100 °C, and after secondary drying, the moisture content of the straw is reduced from 25% to 18%. In step ⑤, the heat substitution rate of the decomposition furnace is set ≥ 30%. When feeding, the fourth gate valve is opened, and the straw is sent to the pre - combustion furnace 15 through the fourth screw conveyor 13 for incineration.

[0065] Other structural methods are the same as those in Example 2.

[0066] Example 4:

[0067] A method for a cement kiln to use biomass to replace fuel includes the following steps:

[0068] In Step ①, wood chips with a particle size of 50 mm and a moisture content of 30% are fed into the small-particle biomass fuel pit 23 of the fuel combined storage workshop 1. In Step ③, the waste heat flue gas from the kiln tail is used as the heat source, and the inlet flue gas temperature is set at 90 °C. After drying, the moisture content of the wood chips is reduced from 30% to 20%. In Step ④, the waste heat flue gas from the kiln head of the cement kiln is used as the heat source, and the inlet flue gas temperature is set at 80 °C. After secondary drying, the moisture content of the wood chips is reduced from 20% to 15%. In Step ⑤, the heat substitution rate of the decomposition furnace is set to be less than 30%. When feeding, the fourth gate valve is opened, and the wood chips directly enter the decomposition furnace 19 of the original cement kiln system through the fourth screw conveyor 13 for incineration.

[0069] Other structural methods are the same as those in Embodiment 2.

[0070] The basic example of the present invention and its various further selected examples can be freely combined to form multiple embodiments, all of which are embodiments that can be adopted and claimed by the present invention. In the solution of the present invention, each selected example can be arbitrarily combined with any basic example and selected example.

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for using biomass as a substitute fuel in a cement kiln, which adopts a system for using biomass as a substitute fuel in a cement kiln. The system includes a fuel combined storage workshop (1), and is characterized in that: The described fuel combined storage workshop (1) is connected to the primary drying device (8) through the second conveying and metering component. The primary drying device (8) is connected to the first waste heat flue gas channel (20). The primary drying device (8) is connected to the secondary drying and homogenizing bin (10). The secondary drying and homogenizing bin (10) is connected to the second waste heat flue gas channel (21). The secondary drying and homogenizing bin (10) is connected to the third conveying and metering component. The third conveying and metering component is connected to the fourth conveying component. The fourth conveying component is respectively connected to the decomposition furnace (19) and the pre - combustion furnace (15). The pre - combustion furnace (15) is connected to the decomposition furnace (19). The method includes the following steps: Step ①, the biomass fuel is fed into the fuel combined storage workshop (1) and classified according to the incoming particle size. Step ②, the large - particle - size biomass fuel is crushed into small - particle - size biomass fuel. Step ③, the small - particle - size biomass fuel is conveyed through the second conveying and metering component and enters the primary drying device (8). The flue gas at 80 - 130 °C in the first waste heat flue gas channel (20) is used as the heat source to heat and dry the biomass fuel. Step ④, the biomass fuel after primary drying enters the secondary drying and homogenizing bin (10). The flue gas at 80 - 130 °C in the second waste heat flue gas channel (21) is used as the heat source to heat and dry the biomass fuel. The flue gas is blown in vertically from the bottom and exchanges heat counter - currently with the downward - flowing biomass fuel. Step ⑤, the biomass fuel after secondary drying is successively conveyed through the third conveying and metering component and the fourth conveying component, and is fed into the pre - combustion furnace (15) or the decomposition furnace (19) according to the different utilization amounts of the biomass fuel. When the utilization amount is low and the heat substitution rate of the decomposition furnace < 30%, the biomass fuel can directly enter the decomposition furnace (19) for incineration. When the utilization amount is high and the heat substitution rate of the decomposition furnace ≥ 30%, the biomass fuel enters the pre - combustion furnace (15) for incineration. The biomass fuel is completely burned in the pre - combustion furnace (15), and the generated high - temperature flue gas enters the decomposition furnace (19), and the fuel fly ash enters the decomposition furnace (19) to participate in the production of cement clinker.

2. The method for using biomass as a substitute fuel in a cement kiln according to claim 1, wherein: The described fuel combined storage workshop (1) includes a crusher (4), a large - particle - size biomass fuel pit (22) and a small - particle - size biomass fuel pit (23). The inlet of the crusher (4) is connected to the first feeding bin (3), and the outlet of the crusher (4) is connected to the small - particle - size biomass fuel pit (23).

3. The method for using biomass as a substitute fuel in a cement kiln according to claim 1 or 2, characterized in that: The described fuel combined storage workshop (1) includes an intelligent grab crane (2). The intelligent grab crane (2) is located at the top. The intelligent grab crane (2) is equipped with a coarse - material grab and a bulk - material grab. The spray dust removal device (17) is connected to the top of the fuel combined storage workshop (1).

4. The method for using biomass as an alternative fuel in a cement kiln according to claim 1, characterized in that: Both the primary drying device (8) and the secondary drying and homogenizing bin (10) are connected to the dust collector (9) through pipelines. The dust collector (9) is connected to the chimney through a centrifugal fan and pipelines.

5. The method for using biomass as a substitute fuel in a cement kiln according to claim 1, characterized in that: The described second conveying and metering assembly includes a second feeding bin (5), a second screw conveyor (6), and a second metering feeder (7). The inlet of the second screw conveyor (6) is connected to the second feeding bin (5), the outlet of the second screw conveyor (6) is connected to the second metering feeder (7), and the second metering feeder (7) is connected to the primary drying device (8).

6. The method for using biomass as a substitute fuel in a cement kiln according to claim 1 or 4, characterized in that: The top of the described secondary drying and homogenizing bin (10) is provided with a downward feeding port, and the bottom of the secondary drying and homogenizing bin (10) is provided with an upward air inlet.

7. The method for using biomass as a substitute fuel in a cement kiln according to claim 1, characterized in that: The described third conveying and metering assembly includes a third screw conveyor (11) and a third metering feeder (12). The inlet of the third screw conveyor (11) is connected to the secondary drying and homogenizing bin (10), the outlet of the third screw conveyor (11) is connected to the third metering feeder (12), and the third metering feeder (12) is connected to the fourth conveying assembly.

8. The method for using biomass as a substitute fuel in a cement kiln according to claim 1, characterized in that: The described fourth conveying assembly includes a fourth screw conveyor (13). A fourth gate valve (14) is provided at the outlet end of the fourth screw conveyor (13), and a fifth gate valve (16) is provided between the pre - combustion furnace (15) and the decomposition furnace (19).

9. The method for using biomass as a substitute fuel in a cement kiln according to claim 1, characterized in that: Step ①: Classify according to whether the incoming particle size is greater than or less than 100 mm, and enter the large - particle - size biomass fuel pit (22) or the small - particle - size biomass fuel pit (23) respectively. Step ②: The large - particle - size biomass fuel is fed into the first feeding bin (3) by the coarse - material grab in the intelligent grab crane (2), crushed to a particle size less than 100 mm by the crusher (4) below, and then stored in the small - particle - size biomass fuel pit (23). Step ③: The small - particle - size biomass fuel is fed into the second feeding bin (5) by the bulk - material grab in the intelligent grab crane (2), discharged by the second screw conveyor (6) below and metered by the second metering feeder (7), and then enters the primary drying device (8). In Steps ③ and ④, the exhaust gas at the outlets of the primary drying device (8) and the secondary drying and homogenizing bin (10) is dust - collected and purified by the dust collector (9), and then converges into the chimney and is discharged into the atmosphere. Step ⑤: The biomass fuel after secondary drying is discharged by the third screw conveyor (11), then metered by the third metering feeder (12), and conveyed into the fourth screw conveyor (13), and fed into the pre - combustion furnace (15) or the decomposition furnace (19) according to the different utilization amounts of the biomass fuel. By opening or closing the fifth gate valve (16) between the pre - combustion furnace (15) and the decomposition furnace (19), the online - offline switching between this system and the cement kiln system can be realized.

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