A decoupling type biomass gasification power generation system and a multi-parameter collaborative control method

Abstract

The present application belongs to the technical field of biomass energy power generation, and particularly relates to a decoupling type biomass gasification power generation system and a multi-parameter collaborative control method, which comprises the following steps: 1) biomass raw materials are fed into a vertical multi-stage decoupling gasification furnace for gasification, a gasification agent and water vapor are introduced into the decoupling gasification furnace, the amount of the gasification agent and water vapor introduced is adjusted, and the temperature in the reduction zone is controlled at 700-900 DEG C; 2) the gasification products of the decoupling gasification furnace are cooled by a heat exchanger, then filtered by a filter I for the first time, water is removed by a steam-water condenser separator, pressurized by a Roots blower, filtered by a filter II for the second time, and then fed into an internal combustion engine for power generation; and 3) the gas discharged from the internal combustion engine is pressurized by an exhaust gas turbocharger, then compressed by a compressed air generator, and then fed into the decoupling gasification furnace as a gasification agent. The present application has the advantages that the present application can realize in-situ high-temperature catalytic cracking of tar, efficient utilization of waste heat, and stable operation of the system, thereby improving the power generation efficiency and reducing the equipment cost.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biomass energy power generation, and particularly relates to a decoupled biomass gasification power generation system and a multi-parameter collaborative control method. BACKGROUND

[0002] Biomass gasification power generation is a clean energy technology that utilizes biomass resources (such as crop straw, wood waste, municipal organic waste, etc.) to convert into combustible gas through gasification reaction, and then drives power generation equipment to generate electricity. Biomass gasification is a thermochemical conversion process that decomposes biomass under partial oxidation conditions to convert it into combustible gas (main components include hydrogen (H2), carbon monoxide (CO), methane (CH4), etc.). The gasification process is usually carried out in a high-temperature (700℃-1000℃) and limited oxygen (or no oxygen) environment, and the organic matter in the biomass is decomposed into gaseous products, while a small amount of solid residue (such as carbon black) and liquid products (such as tar) are produced. Compared with traditional biomass direct combustion, the gasification power generation process produces less pollution, and can further reduce pollution emissions through purification systems, meeting environmental protection requirements. At the same time, with the application of biomass gasification power generation systems, some technical defects have also been found:

[0003] 1. Low biomass gasification efficiency: Traditional single gasification agent (oxidizing agent) has low gasification efficiency, and the biomass gas heat value is low.

[0004] 2. High energy consumption for tar treatment: Tar produced during the gasification process is a complex organic mixture that is prone to deposit in equipment, causing blockage and corrosion, affecting the stable operation of the system. Existing tar treatment relies on water washing or electric tar trapping units, accounting for 15%-20% of the total system energy consumption, and is prone to secondary pollution. At the same time, it also increases the operating cost and capital investment for gas purification.

[0005] 3. Large fluctuations in gas quality: Open-loop control leads to a ±30% fluctuation range of H2 / CO concentration in the gasification gas, affecting the stability of power generation.

[0006] 4. Low utilization rate of waste heat: The traditional system has a waste heat recovery rate of less than 40%, and the utilization is single, with an overall power generation efficiency of less than 25%. SUMMARY

[0007] To overcome the shortcomings of the prior art, the present application aims to provide a decoupled biomass gasification power generation system and a multi-parameter collaborative control method, which optimizes the system structure and multi-parameter collaborative control, and realizes in-situ high-temperature catalytic cracking of tar, efficient utilization of waste heat, and stable operation of the system.

[0008] To achieve the above-mentioned purpose, the present application realizes the following technical solutions:

[0009] A multi-parameter coordinated control method for decoupled biomass gasification power generation, comprising:

[0010] 1) Biomass gasification treatment: biomass raw materials are sent into a vertical multi-stage decoupled gasification furnace for gasification, a gasification agent and steam are passed into the vertical multi-stage decoupled gasification furnace, the reduction zone temperature is controlled at 700-900 DEG C by adjusting the amount of gasification agent and steam passed in, and the air-fuel ratio of the oxidation zone is controlled at 0.25-0.35;

[0011] 2) Flue gas treatment: the gasification products of the vertical multi-stage decoupled gasification furnace are cooled by a heat exchanger, then filtered by a filter once, remove moisture by a steam-water condenser separator, pressurized by a Roots blower, filtered by a filter twice, and then sent into an internal combustion engine for power generation, with the inlet temperature being stabilized at 35-50 DEG C;

[0012] 3) Flue gas waste heat utilization: the gas discharged from the internal combustion engine is pressurized by an exhaust gas turbocharger, and then compressed by a compressed air generator and sent to the vertical multi-stage decoupled gasification furnace as a gasification agent.

[0013] The total spraying amount of steam passed into the vertical multi-stage decoupled gasification furnace is dynamically adjusted based on a fuzzy PID algorithm, and the calculation formula of the spraying amount is:

[0014] Q total =Q b +Q pid (1)

[0015] In formula (1), Q total is the total spraying amount, with the unit of L / min; Q b is the basic spraying amount, with the unit of L / min; and Q pid is the dynamic spraying amount;

[0016] Qb=0.8×Tgas×ln(P / 101.325P) (2)

[0017] In formula (2), Tgas is the temperature of the gasification furnace, with the unit of DEG C; and P is the pressure, with the unit of kPa;

[0018] Q pid =Kp*△t+Ki*∫△t dt (3)

[0019] In formula (3), Q oid is the dynamic adjustment spraying amount, with the unit of L / min; Kp is a proportional coefficient, with no dimension; Ki is an integral coefficient, with no dimension; and △t is the temperature difference between the set value and the actual measured value of the gasification furnace, with the unit of DEG C.

[0020] A decoupled biomass gasification power generation system, comprising a vertical multi-stage decoupled gasification furnace, a fuel gas treatment unit, and a flue gas waste heat utilization unit;

[0021] The vertical multi-stage decoupling gasifier is divided into a pyrolysis zone, an oxidation zone and a catalytic reduction zone from top to bottom by a perforated partition plate in the furnace.

[0022] The gas treatment unit comprises a heat exchanger, a filter one, a steam-water condenser separator, a Roots blower and a filter two connected in sequence, the vertical multi-stage decoupling gasifier is connected with the heat exchanger, the heat exchanger is used for reducing the temperature of the gas produced by the vertical multi-stage decoupling gasifier, and the outlet of the Roots blower is connected with an internal combustion engine of a flue gas waste heat utilization unit.

[0023] The flue gas waste heat utilization unit comprises an internal combustion engine, an exhaust turbocharger and a compressed air generator, the flue gas treated by the gas treatment unit is input into the internal combustion engine, the exhaust turbocharger is driven by the gas discharged from the internal combustion engine to compress the air generator, and the compressed gasification agent output by the compressed air generator is delivered to the vertical multi-stage decoupling gasifier.

[0024] The oxidation zone is connected with a temperature sensor, the pyrolysis zone is connected with a pressure transmitter, the furnace is further connected with a spraying pipeline, the spraying pipeline is connected with a high-temperature spraying valve, and the outlet of the vertical multi-stage decoupling gasifier is connected with a flow meter.

[0025] The outlet of the vertical multi-stage decoupling gasifier is connected with a gas analyzer.

[0026] The decoupling reactor is filled with a supported nickel-based catalyst.

[0027] The supported nickel-based catalyst is a nickel-based rare earth element catalyst with a loading amount of 20% to 25%.

[0028] Compared with the prior art, the beneficial effects of the present application are:

[0029] The present application realizes in-situ high-temperature catalytic cracking of tar, efficient utilization of waste heat and stable operation of the system through structural optimization and multi-parameter collaborative control, improves the power generation efficiency, and reduces the equipment cost.

[0030] 1. Reducing the content of tar: the supported nickel-based catalyst has high catalytic activity, good stability and anti-carbon deposition performance, and a long service life, can effectively crack tar and convert it into small molecule gas, and the content of tar is reduced to 10 mg / Nm 3 The tar removal rate reaches more than 99%, the tar is almost completely removed, the operation is convenient, the energy consumption is low, and no secondary pollution is caused.

[0031] 2. Improving the power generation efficiency: through the decoupling gasification furnace technology, the biomass gasification rate is improved, the mixed gas calorific value is increased, and the power generation efficiency is improved.

[0032] 3. Improve system stability: H2 / CO concentration fluctuation range is controlled within ±5%. Through the control strategy of composite gasification agent, the ratio of H2 / CO is adjustable between 1-2, the calorific value of mixed gas is controllable between 5-12 MJ / Nm 3 , and the carbon conversion rate can reach 95%, providing multi-mode selection for subsequent mixed gas utilization. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a structural schematic diagram of a decoupled biomass gasification power generation system.

[0034] Figure 2 is a logic diagram of multi-parameter coordinated control.

[0035] Figure 3 is a tar content curve diagram of a traditional gasification furnace and a vertical multi-stage decoupled gasification furnace.

[0036] In the figure: 1-decoupled gasification furnace; 101-hole isolation plate; 102-pyrolysis zone; 103-oxidation zone; 104-catalytic reduction zone; 105-decoupling reactor; 201-internal combustion engine; 202-exhaust gas turbocharger; 211-internal combustion engine flue gas; 212-gasification agent;

[0037] 3-control system; 301-temperature sensor; 302-pressure transmitter; 303-high temperature spray valve; 304-gas flow meter; 305-gas analyzer; 306-air gasification agent flow meter;

[0038] 4-gas treatment unit; 401-heat exchanger; 402-filter one; 403-steam-water condenser separator; 404-roots blower. DETAILED DESCRIPTION

[0039] The present application will be described in detail below in conjunction with the drawings of the specification, but it should be pointed out that the implementation of the present application is not limited to the following embodiments.

[0040] See Figure 1 , a decoupled biomass gasification power generation system, comprising a vertical multi-stage decoupled gasification furnace 1, a gas treatment unit 4, and a flue gas waste heat utilization unit.

[0041] The furnace of the vertical multi-stage decoupling gasifier 1 is divided into a pyrolysis zone 102, an oxidation zone 103, and a catalytic reduction zone 104 from top to bottom by a perforated partition plate 101. The reduction zone is provided with a decoupling reactor 105. The pyrolysis zone 102 is used for the preliminary decomposition of biomass raw materials to generate volatile matter and fixed carbon. The pore size of the perforated partition plate 101 between the pyrolysis zone 102 and the oxidation zone 103 is 1-3 cm. The oxidation zone 103 is supplied with sufficient oxygen by the gasification agent to promote the complete combustion of volatile matter and release a large amount of heat. The pore size of the perforated partition plate 101 between the oxidation zone 103 and the catalytic reduction zone 104 is 0.5-1 cm, which helps to reduce the gas flow rate in the catalytic reduction zone 104, prolong the contact time between the gas and the catalyst, and thus improve the efficiency of the reduction reaction to generate high-quality biomass mixed gas. In addition, a temperature sensor 301 is connected in the oxidation zone 103 to collect temperature data of the oxidation zone 103. A pressure transmitter 302 is connected to the pyrolysis zone 102 to monitor the pressure change in the furnace to prevent excessive pressure or low pressure from affecting the gasification efficiency and safety. The furnace is also connected with a spray pipeline, and a high-temperature spray valve 303 is connected to the spray pipeline. The spray amount is calculated according to the detected values of temperature and pressure, and the spray amount is adjusted by adjusting the opening degree of the high-temperature spray valve 303 in real time to keep the temperature and pressure in the system within the preset safe range. The temperature sensor 301, the pressure transmitter 302, the high-temperature spray valve 303, a gas analyzer 305 connected to the outlet of the decoupling gasifier 1, and a control system are used for real-time monitoring and adjustment to ensure the stability and efficiency of the gasification process, reduce energy consumption and emissions. In addition, the control system is also equipped with a fault self-diagnosis function, which can immediately start protection measures (alarm, reduce load when exceeding the set value, and shut down in severe cases) when detecting abnormal temperature, pressure, and gas composition to prevent equipment damage or safety accidents.

[0042] The decoupling reactor 105 is filled with a supported nickel-based catalyst. The supported nickel-based catalyst is a nickel-based rare earth catalyst with a loading of 20%-25%. The nickel-based rare earth catalyst includes, by weight percentage: Ni: 20%-25%; Al2O3: 65%-70%; MgO: 3%-5%; SiO2: 2%-4%; and rare earth elements: 2%-5%. The rare earth elements mainly include Ce, and the rest include La, Nd, Y, or Z.

[0043] Catalyst regeneration: The catalyst is installed in the decoupling structure device, and the temperature is above 650°C, and the deactivation is low. If activation is needed, calcination at no less than 800°C for more than 2 hours, the activity is restored to 95% of the initial value.

[0044] The multi-stage decoupling gasifier 1 is a fixed type down exhaust positive pressure system. The biomass raw material enters the furnace from the top of the furnace, the gasification agent 212 at about 250 DEG C is uniformly injected by the oxidation zone 103, so that the gasification temperature rises to above 900 DEG C, and the combustion and pyrolysis of the biomass raw material are carried out at the same time. After the high-temperature gas passes through the catalytic reduction zone 104 of the hot carbon layer, the main components will be reduced to H2 and CO, and the tar content in the product gas of the down exhaust gasifier is low, and the tar is almost completely removed by the secondary action of the supported nickel-based catalyst.

[0045] The gas treatment unit 4 comprises a heat exchanger 401, a filter 402, a steam-water condenser separator 403 and a Roots blower 404 connected in sequence, the vertical multi-stage decoupling gasifier 1 is connected with the heat exchanger 401, the heat exchanger 401 is used for reducing the temperature of the gas produced by the vertical multi-stage decoupling gasifier 1, and a gas-water heat exchanger can be used; the outlet of the Roots blower 404 is connected with the internal combustion engine 201 of the flue gas waste heat utilization unit; the outlet of the vertical multi-stage decoupling gasifier is connected with a gas analyzer 305. The response speed of the temperature sensor 301, the pressure transmitter 302, the high-temperature spray valve 303 and the gas analyzer 305 is less than 0.5 s.

[0046] The flue gas waste heat utilization unit comprises an internal combustion engine 201, an exhaust turbocharger 202 and a compressed air generator, the flue gas treated by the gas treatment unit 4 is input to the internal combustion engine 201, the exhaust turbocharger 202 drives the compressed air generator by using the gas discharged from the internal combustion engine 201, and the compressed gasification agent 212 output by the compressed air generator is delivered to the vertical multi-stage decoupling gasifier 1.

[0047] See Figure 2 A multi-parameter coordinated control method for decoupling type biomass gasification power generation, comprising:

[0048] 1) Biomass gasification treatment: the biomass raw material is sent to the vertical multi-stage decoupling gasifier 1 for gasification, the gasification agent 212 and water vapor are input to the furnace of the vertical multi-stage decoupling gasifier 1, the reduction zone temperature is controlled at 700-900 DEG C by adjusting the input amount of the gasification agent 212 and the water vapor, and the air-fuel ratio of the oxidation zone 103 is controlled at 0.25-0.35; the residence time of the reduction zone is greater than 10 s.

[0049] The gasification agent uses a composite gasification agent: air + steam. Both of these two gasification agents are used simultaneously or alternately in the process of gasifying the biomass. The air serves as an oxidizing agent to provide necessary oxygen, while the steam serves as a gasification agent to participate in the reaction. The two agents work together to significantly improve the gasification efficiency. By adjusting the ratio of air to steam, the content of H2 and CO in the synthesis gas can be controlled. In addition, the addition of steam helps to regulate the temperature distribution in the gasifier, prevents local overheating, and ensures the stability of the gasification process. The participation of steam in the gasification reaction can also effectively reduce the amount of tar generated, improve the quality of synthesis gas, and reduce the occurrence of coking in the furnace.

[0050] Catalytic cracking can easily degrade relatively stable tar to a great extent. The combustible gas containing tar that enters the catalytic reduction zone 104 from the oxidation zone 103 is introduced into the decoupling reactor 105 filled with a supported nickel-based catalyst. The reaction temperature is controlled at 800-950°C by spraying steam, the gas yield is increased to 20% (volume percentage), and the calorific value is increased. The mixed gas leaves the gasifier at a temperature of 800-950°C, realizing in-situ cracking of tar (CnHm→CO+H2) and CH4 reforming.

[0051] Adaptive control: During the biomass gasification process, the gasification conditions in the furnace are detected in real time by temperature sensor 301, pressure sensor 302, gas analyzer 305, mixed fuel gas flow meter 305, air gasification agent flow meter 306, and other measuring equipment. According to the different physical and chemical properties of different biomass raw materials and different gasification agent usage strategies, different parameter module units are embedded, different parameter models and compensation models are established, dynamic parameter adjustment and automatic response following are realized, and the system can quickly and automatically switch, ensuring stable and efficient gasification process under different working conditions.

[0052] From Figure 3 It can be seen that the traditional gasifier fails after 36 hours of operation, resulting in secondary pollution and a sharp increase in tar content. The vertical multi-stage decoupling gasifier 1 can almost completely remove tar from the beginning of operation for 36 hours through multi-parameter closed-loop control response.

[0053] 2) Flue gas treatment: The biomass mixed gas enters the filter to remove most of the dust before entering the gas internal combustion engine 201 group, and then passes through the dehumidification and cooling system for condensation and dehydration, pressure boosting and dust removal. The gasification products of the vertical multi-stage decoupling gasifier 1 are cooled by the heat exchanger 401 (the heat exchanger 401 can use a gas-water heat exchanger), then filtered by the filter one 402, removed of water by the steam-water condenser separator 403, pressurized by the Roots blower 404, filtered by the filter two, and sent to the internal combustion engine 201 for power generation. The inlet temperature is stable at 35-50°C;

[0054] 3) Waste heat utilization of flue gas: The gas discharged from the internal combustion engine 201 is pressurized by the exhaust turbocharger 202, and then compressed by the compressed air generator and sent to the vertical multi-stage decoupling gasification furnace 1 as the gasification agent 212. A gas flow meter 304 is arranged on the pipeline at the outlet of the decoupling gasification furnace and the inlet of the internal combustion engine to detect the flow data in real time and provide control reference data. The unused exhaust energy can be effectively utilized, and in particular, the flow energy can be used for gasification and power generation to reduce the external energy consumption.

[0055] The use of composite gasification agent is based on air gasification agent supplemented by high-temperature steam as auxiliary gasification agent. Among them, the spraying amount of steam gasification agent is dynamically regulated based on fuzzy PID algorithm, and the calculation formula of spraying amount (also applicable to single steam gasification agent use condition) is as follows:

[0056] Q total = Q b + Q pid (1)

[0057] In formula (1), Q total is the total spraying amount, unit: L / min; Q b is the basic spraying amount, unit: L / min; Q pid is the dynamic spraying amount;

[0058] Qb = 0.8 x Tgas x ln (P / 101.325P) (2)

[0059] In formula (2), Tgas is the temperature of the gasification furnace, unit: ℃; P is the pressure, unit: kPa;

[0060] Q pid = Kp*△t + Ki*∫△t dt (3)

[0061] In formula (3), Q oid is the dynamic adjustment spraying amount, unit: L / min; Kp: proportional coefficient, dimensionless; Ki: integral coefficient, dimensionless; △t: temperature difference between set value and actual measured value of the gasification furnace, unit: ℃.

[0062] The basic spraying amount provides the basic set spraying amount, and the PID controller adjusts the dynamic spraying amount in real time based on the temperature difference.

[0063] The control system performs self-adaptive adjustment: for different biomass raw materials and gasification agent use strategies, the system parameters are dynamically adjusted to realize system self-adaptive following, which can ensure that the system quickly reaches the ideal operating state.

[0064] Benchmark + feedback control: the experience model quickly responds to static parameter changes, and the PID controller suppresses dynamic interference to improve system robustness.

[0065] Efficiency and stability: benchmark value reduces PID adjustment range, avoids overshoot; dynamically adjusts to compensate for transient errors, ensuring stable gas quality. Achieves intelligent, high-precision, low-vibration operation of the biomass gasification power generation system.

[0066] Extreme conditions: when the moisture content of biomass is >24%, the gasification efficiency will decrease, the content of H2 and CO will decrease, and the calorific value of the mixed gas will decrease. Adjust the air-fuel ratio to above 0.30, increase the oxygen supply, stabilize the furnace temperature, and reduce the variation of mixed gas data;

[0067] In the initial start-up stage of the decoupled biomass gasification power generation system, air is used as the main gasification agent to quickly raise the furnace temperature to the working temperature; after the working temperature is stabilized, it enters the stable operation stage, and adjusts the ratio of air to steam according to the target syngas composition. In the load regulation stage, the gasification agent ratio is changed to adapt to the characteristics of the raw materials or load changes.

Claims

1. A multi-parameter coordinated control method for decoupled biomass gasification power generation, characterized in that, The application relates to a biomass gasification treatment system. 1) Biomass gasification treatment: biomass raw materials are fed into a vertical multi-stage decoupling gasification furnace, air and water vapor are introduced into the vertical multi-stage decoupling gasification furnace, the reduction zone temperature is controlled at 700-900 DEG C by adjusting the air and water vapor introduction amount, and the air-fuel ratio of the oxidation zone is controlled at 0.25-0.35; 2) Flue gas treatment: the gasification products of the vertical multi-stage decoupling gasification furnace are cooled by a heat exchanger, then filtered by a filter I, water is removed by a steam-water condenser separator, pressurized by a Roots blower, filtered by a filter II, and then sent into an internal combustion engine for power generation, and the inlet temperature is stabilized at 35-50 DEG C; 3) Flue gas waste heat utilization: the gas discharged from the internal combustion engine is pressurized by an exhaust turbocharger, then compressed by a compressed air generator, and then sent to the vertical multi-stage decoupling gasification furnace as a gasification agent; The total spraying amount of water vapor introduced into the vertical multi-stage decoupling gasification furnace is dynamically controlled based on a fuzzy PID algorithm, and the spraying amount calculation formula is as follows: Qb=0.8*Tgas*ln (P / 101.325P) (2) wherein Tgas is the gasification furnace temperature, unit: DEG C; P is the pressure, unit: kPa; Ki is an integral coefficient, dimensionless; and Delta t is the temperature difference between the set value and the actual measured value of the gasification furnace, unit: DEG C. Q total =Q b +Q pid (1) In formula (1), Q total is the total spray amount, unit: L / min; Q b is the base spray amount, unit: L / min; Q pid Dynamic spray quantity; The application further discloses a biomass gasification treatment system which comprises a vertical multi-stage decoupling gasification furnace, a gas treatment unit and a flue gas waste heat utilization unit. The vertical multi-stage decoupling gasification furnace is divided into a pyrolysis zone, an oxidation zone and a catalytic reduction zone from top to bottom by a hole isolation plate in the furnace. Q pid = Kp*△t + Ki*∫△t dt (3) In formula (3), Q oid for dynamic adjustment of the amount of spray, units: L / min; Kp: proportional coefficient, dimensionless; The decoupling reactor is filled with a supported nickel-based catalyst. The supported nickel-based catalyst is a nickel-based rare earth element catalyst with a loading amount of 20%-25%.

2. A decoupled biomass gasification power generation system implementing the multi-parameter coordinated control method of claim 1, characterized in that, The gas treatment unit comprises a heat exchanger, a filter I, a steam-water condenser separator, a Roots blower and a filter II which are connected in sequence, the vertical multi-stage decoupling gasification furnace is connected with the heat exchanger, the heat exchanger is used for reducing the gas temperature generated by the vertical multi-stage decoupling gasification furnace, and the outlet of the Roots blower is connected with the internal combustion engine of the flue gas waste heat utilization unit through the filter II. The flue gas treated by the gas treatment unit is input into the internal combustion engine, the exhaust turbocharger is driven by the gas discharged from the internal combustion engine to compress the air generator, and the compressed gasification agent output by the air generator is delivered to the vertical multi-stage decoupling gasification furnace. The oxidation zone is connected with a temperature sensor, the pyrolysis zone is connected with a pressure transmitter, the furnace is further connected with a spraying pipeline, the spraying pipeline is connected with a high-temperature spraying valve, and the outlet of the vertical multi-stage decoupling gasification furnace is connected with a flow meter. The outlet of the vertical multi-stage decoupling gasification furnace is connected with a gas analyzer. ​ ​ 3. The decoupled biomass gasification power generation system of claim 2, wherein, ​ 4. The decoupled biomass gasification power generation system of claim 2, wherein, ​

Images