CN116640606A - Coal fuel staged gasification combustion system and combustion method - Google Patents

Abstract

The invention provides a coal fuel graded gasification combustion system and combustion method, including: a pyrolyzer, which is suitable for performing a pyrolysis reaction on coal fuel and absorbing heat to obtain semi-coke particles, tar and pyrolysis gas; pyrolysis The product purification and separation unit is suitable for separating the tar and pyrolysis gas from the pyrolyzer to obtain the separated tar and separated pyrolysis gas; the gasifier is suitable for making the semi Coke particles and tar from the pyrolysis product purification and separation unit are respectively gasified with the gasification agent preheated by the waste heat boiler to release heat to prepare synthesis gas; and the waste heat boiler is suitable for making the pyrolysis product The pyrolysis gas in the purification and separation unit undergoes a reforming reaction with the water in the synthesis gas to obtain reformed gas; wherein, the pyrolysis gas includes methane, ethane and ethylene. The invention utilizes the sensible heat of the high-temperature synthesis gas to preheat the gasification agent and drive the reforming of the pyrolysis gas, thereby realizing the cascade utilization of heat energy.

Description

Coal fuel staged gasification combustion system and combustion method

technical field

The invention relates to the technical field of energy utilization and fuel combustion, in particular to a coal fuel staged gasification combustion system and a combustion method.

Background technique

At present, the mainstream of the energy system is traditional fossil fuels represented by coal, oil and natural gas. Among them, coal is a relatively important primary energy, and its main utilization method is coal-fired power generation. However, the direct combustion of coal will produce a relatively large amount of pollutants, such as SO _x , NO _x , dust, etc., which will pollute the atmosphere and cause serious environmental problems when discharged into the environment. In addition, the emission of _CO2 into the atmosphere from burning coal contributes to the greenhouse effect.

Coal gasification converts coal from a solid fuel to a clean gaseous fuel. However, there are still some problems with traditional coal gasification technology. Such as relying on the reaction of part of coal and oxygen to supply heat for the gasification process, high consumption of pure oxygen, large heat transfer temperature difference in the cooling process of high-temperature syngas, and low efficiency of cold gas (70%-85%) and other problems.

Therefore, it is necessary to find a coal fuel combustion system to solve the above problems.

Contents of the invention

Aiming at at least one or part of the above technical problems, embodiments of the present invention provide a coal fuel staged gasification combustion system and combustion method, which can decouple the coal gasification process into a pyrolysis process and a gasification process, reducing the The share of coal fuel is directly burned and reduces the heat transfer temperature difference in the gasifier.

In order to achieve the above object, as an aspect of the present invention, a coal fuel staged gasification combustion system is provided, including: a pyrolyzer, which is suitable for performing a pyrolysis reaction on coal fuel and absorbing heat to obtain semi-coke particles, tar And pyrolysis gas; pyrolysis product purification and separation unit, suitable for separating tar from pyrolysis device and pyrolysis gas to obtain separated tar and separated pyrolysis gas; gasifier, suitable for use The semi-coke particles from the pyrolyzer and the tar from the pyrolysis product purification and separation unit are respectively gasified with the gasification agent preheated by the waste heat boiler to release heat to prepare syngas; and the waste heat boiler is suitable for The purpose is to reform the pyrolysis gas from the pyrolysis product purification and separation unit and the water in the synthesis gas to obtain reformed gas; wherein, the pyrolysis gas includes methane, ethane and ethylene.

In one of the embodiments, the waste heat boiler uses the heat from the first temperature range of the syngas from the gasifier to preheat the gasification agent required for the gasification reaction; and the waste heat boiler uses the synthetic gas from the gasifier The heat in the second temperature range of the gas provides energy for the reforming reaction of the pyrolysis gas; wherein, the temperature in the first temperature range is higher than that in the second temperature range.

In one of the embodiments, it also includes: a synthesis gas purification unit, adapted to purify the synthesis gas; and a pre-combustion CO ₂ capture unit, adapted to react CO in the synthesis gas to obtain CO ₂ , and treat the CO ₂ It is captured and discharged from the combustion system.

In one of the embodiments, it also includes: a gas turbine, which is suitable for combusting hydrogen in the syngas with air to obtain high-temperature flue gas and generate first heat and second heat, and convert the generated first heat into electrical energy output system; a splitter, adapted to split the second heat from the gas turbine so that a part of the second heat is transferred to the pyrolyzer to provide heat for the pyrolysis reaction of coal fuel, and another part of the second heat is transferred Waste heat boiler; waste heat boiler, which is suitable for recovering sensible heat from the high-temperature flue gas from the gas turbine and another part of the second heat; and steam turbine, which uses the steam from the waste heat boiler to expand and generate electricity.

In one of the embodiments, it also includes an air separation unit, which is suitable for purifying the incoming oxygen; and a second mixer, which is suitable for mixing the air with the purified oxygen to obtain a gasification agent, and Pass the gasifying agent into the waste heat boiler.

In one of the embodiments, a first mixer is also provided in the waste heat boiler and the synthesis gas purification unit.

In one of the embodiments, the pre-combustion CO ₂ capture unit includes a CO ₂ shift unit and a CO ₂ capture unit, the CO ₂ shift unit is suitable for oxidizing CO in the syngas to obtain CO ₂ ; the CO ₂ capture unit is suitable for The obtained CO ₂ is captured and discharged from the combustion system.

As another aspect of the present invention, a combustion method is provided, using the combustion system as described above, the method comprising:

Pass the coal fuel into the pyrolyzer, carry out pyrolysis reaction and absorb heat, and obtain semi-coke particles, tar and pyrolysis gas;

The tar and pyrolysis gas obtained by pyrolysis are passed into the pyrolysis product purification and separation unit for separation, and the separated tar and semi-coke particles obtained by pyrolysis are respectively input into the gasifier and the gas preheated by the waste heat boiler. gasification reaction with chemical agent to prepare synthesis gas; and

The pyrolysis gas from the pyrolysis product purification and separation unit is input to the waste heat boiler and undergoes reforming reaction with the water in the synthesis gas to obtain reformed gas.

In one of the embodiments, the reformed gas includes CO, H ₂ ; the synthesis gas includes CO, H ₂ , H ₂ O, CO ₂ .

In one embodiment, the temperature of the synthesis gas before entering the waste heat boiler is 1300-1500°C; the temperature of the mixture of low-temperature synthesis gas and reformed gas passing through the outlet of the waste heat boiler is 200-300°C.

Based on the coal fuel hierarchical gasification combustion system and combustion method of the above-mentioned embodiments of the present invention, the coal gasification process is decoupled into a pyrolysis process and a gasification process, and a part of the heat is used to pyrolyze the coal fuel to obtain semi-coke particles, Tar and pyrolysis gas, the semi-coke particles in it are input into the gasification furnace for gasification, the tar and pyrolysis gas are separated in the pyrolysis product and separation unit, and then the tar is passed into the gasification furnace for gasification The heat released from the synthesis gas at the furnace outlet is used to preheat the gasification agent respectively, and drive the methane, ethylene and ethane in the pyrolysis gas to reform, so that the carbon and hydrogen in the methane, ethane and ethylene in the pyrolysis gas Decoupling reduces the share of direct oxidation of coal fuel and reduces the irreversible loss in the gasification process. The sensible heat of the high-temperature syngas is used to preheat the gasification agent and drive the reforming of the pyrolysis gas through the gasification furnace, so that the heat energy can be utilized in stages and the heat exchange temperature difference in the gasification furnace can be reduced.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Fig. 1 shows the block diagram of coal fuel staged gasification combustion system in an embodiment of the present invention; And

Fig. 2 shows a flow chart of a method for staged gasification combustion of coal fuel in an embodiment of the present invention.

[Description of Reference Signs]

1-pyrolyzer, 2-air separation unit, 3-pyrolysis product purification and separation unit, 4-gasifier, 5-waste heat boiler, 6-first mixer, 7-syngas purification unit, 8-combustion Front _CO2 capture unit, 9-gas turbine, 10-splitter, 11-waste heat boiler, 12-steam turbine, 13-second mixer, s1-coal fuel, s2-semi-coke particles, s3-air, s4-high temperature Synthesis gas, s5-synthesis gas, s6 and s7 are the mixture of synthesis gas, s8-carbon dioxide, s9-the mixture of hydrogen and water vapor, s10, s11, s14 and s15 are high-temperature flue gas, s12 and s21 are both For water, s13-water vapor, s16-mixture of tar and pyrolysis gas, s17-pyrolysis gas, s18-reformed gas, s19-tar, s20-oxygen, s22-gasification agent, s23-preheated Gasification agent, P-electric energy output.

Detailed ways

The composition of coal fuel is relatively complex, and it contains many chemical bonds or chemical chains that are easily broken. However, the coal quality of the coal fuel is different, and the chemical bonds and chemical chains are broken in different situations. Traditional coal gasification does not make a specific distinction between different coal fuels, but directly transports them to the gasifier for gasification reaction and converts them into carbon monoxide and hydrogen. In the process of realizing the concept of the present invention, it is found that by decoupling the coal gasification process into a pyrolysis process and a gasification process, the share of direct coal combustion can be reduced.

Therefore, the embodiments of the present invention provide a coal fuel staged gasification combustion system and combustion method, which can use the heat obtained from the gasification reaction in the gasifier to preheat the gasification agent and drive the pyrolysis gas to Reforming decouples the carbon and hydrogen in methane, ethane and ethylene in the pyrolysis gas, reducing the irreversible loss in the gasification process.

In this paper, the decoupling of carbon and hydrogen refers to the process of decomposing compounds containing carbon and hydrogen such as methane, ethylene or ethane into carbon monoxide and hydrogen after a reforming reaction, specifically refers to the two elements of carbon and hydrogen in the compound The process of breaking the connection of the elements so that they become individual elements or compounds.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

Specifically, as an aspect of the present invention, a coal fuel staged gasification combustion system is provided, including: a pyrolyzer, a pyrolysis product purification and separation unit, a gasifier, and a waste heat boiler. The pyrolyzer is suitable for pyrolyzing coal fuel and absorbing heat to obtain semi-coke particles, tar and pyrolysis gas. The pyrolysis product purification and separation unit is suitable for separating the tar and pyrolysis gas from the pyrolyzer to obtain the separated tar and the separated pyrolysis gas. The gasification furnace is suitable for the gasification reaction of the semi-coke particles from the pyrolyzer and the tar from the pyrolysis product purification and separation unit with the gasification agent preheated by the waste heat boiler to release heat to prepare syngas . The waste heat boiler is suitable for reforming the pyrolysis gas from the pyrolysis product purification and separation unit and the water in the synthesis gas to obtain reformed gas. Pyrolysis gases include methane, ethane, and ethylene.

Fig. 1 shows a block diagram of a coal fuel staged gasification combustion system in an embodiment of the present invention.

A coal fuel staged gasification combustion system in an embodiment of the present invention will be described in detail below with reference to FIG. 1 .

Specifically, as shown in FIG. 1 , the coal fuel staged gasification combustion system provided by the embodiment of the present invention includes a pyrolyzer 1 , a pyrolysis product purification and separation unit 3 , a gasifier 4 and a waste heat boiler 5 .

The pyrolyzer 1 is a closed structural unit made of high temperature resistant alloy material. Specifically, a heating furnace, a reactor, and a discharge device can be set as required, wherein the heating furnace can be selected from electric heating, oil-gas heating or steam heating, so that the inside of the pyrolyzer 1 can maintain a relatively high temperature state; the reactor can be Control the reaction gas flow and temperature change; the discharge device can install multiple branch pipelines to discharge the generated gas and solid particles according to the needs. The pyrolyzer 1 is suitable for converting the coal fuel into solid semi-coke particles, liquid tar and gaseous pyrolysis gas by thermally decomposing the coal fuel at a relatively high temperature. The outlet of the solid product on the endothermic side of the pyrolyzer 1 can be connected to the gasifier 4 as required, and the semi-coke particles s2 are transported to the gasifier 4 through the branch pipeline of the solid product outlet, and the endothermic side of the pyrolyzer 1 The outlet of liquid and gaseous products is connected to the pyrolysis product purification and separation unit 3, and the mixture s16 of tar and pyrolysis gas can be transported to the pyrolysis product purification and separation unit 3 through the branch pipeline of the outlet.

The pyrolysis product purification and separation unit 3 is provided with a feed inlet, a closed reaction chamber, a cooler, a purification device, a separation device and a discharge port. The feed port mainly sends the mixture of tar and pyrolysis gas obtained from the pyrolysis reaction into a closed reaction chamber for processing; the closed reaction chamber can be set in a spherical or cylindrical structure to keep the reaction temperature and pressure constant ; The cooler, through the cooling medium, such as water, will quickly cool the passing reaction product; the purification device is suitable for removing impurities mixed therein from the reaction mixture, so that the reaction product is cleaner; the separation device can be used according to Membrane separation, extraction or rectification need to be provided to separate the purified tar and pyrolysis gas mixture s16; the outlet will transport the separated tar to the gasifier 4 through a branch pipeline , the separated pyrolysis gas is transported to the waste heat boiler 5 through another branch pipeline. The pyrolysis product purification and separation unit 3 is mainly used for separating the mixture s16 of tar and pyrolysis gas and transporting them separately.

The gasification furnace 4 is set as a fixed bed or a fluidized bed structure, and the overall layout of the equipment can be set as a vertical structure as required, including a fuel input end, a gas discharge end, and a heating furnace. The fuel input end, gas discharge end, and The end and the heating furnace are arranged on the same plane, which is convenient for operation and maintenance. The gasification furnace 4 is used to make the semi-coke particles from the pyrolyzer 1 and the tar from the pyrolysis product purification and separation unit 3 respectively perform a gasification reaction with the preheated gasification agent s23 and release heat, thereby A high-temperature syngas s4 is prepared.

The waste heat boiler 5 can be provided with a furnace body, a flue exhaust duct, a waste heat recovery device, an air preheater, a dust collector and a flue duct as required. The waste heat boiler 5 is a kind of heat exchanger, which is mainly used to transfer heat. In an embodiment of the present invention, the waste heat boiler includes circular and/or square tubes and plates, and is composed of parallel tubes arranged side by side, and the tubes can be fastened by welding and/or bolts as required. During heat transfer, the high-temperature syngas s4 flowing out through the outlet of the gasifier is cooled, and then the heat is transferred to the pyrolysis gas s17 in another pipeline, which is used to recombine the pyrolysis gas s17 with the water in the high-temperature syngas s4 The reaction is carried out to obtain the reformed gas s18. It should be noted that these different gases are always kept in different channels, thus preventing their mixing. Valves and/or automatic regulators to adjust the flow rate can be set as needed to control the transfer of heat, so as to achieve the purpose of controlling temperature for heating and cooling. Among them, the pyrolysis gas includes methane, ethane and ethylene; the gasification agent s22 is a mixture of oxygen and water.

More specifically, the coal fuel s1 is input into the pyrolysis furnace 1 through a pipeline, and a pyrolysis reaction occurs to obtain a mixture s16 of semi-coke particles s2, tar and pyrolysis gas. A gasification reaction occurs in the furnace 4 and heat is released. The mixture s16 of tar and pyrolysis gas is transported to the pyrolysis product purification and separation unit 3 through another pipeline, and passes through the separation device in the pyrolysis product purification and separation unit 3. The mixture s16 of tar and pyrolysis gas is separated, and the separated tar is transported to the gasification furnace 4 through a branch pipeline for gasification reaction to prepare high-temperature synthesis gas s4 and release heat. The separated pyrolysis gas passes through another A branch pipe feeds into the waste heat boiler 5 . Among them, the tar and semi-coke particles s2 undergo gasification reaction with the preheated gasification agent s23 in the gasifier 4 to prepare high-temperature syngas s4 and release heat, which is used to enter the preheated gasification agent s23 The preheating before the gasifier and the reforming of the driving pyrolysis gas, in which the sensible heat of the high-temperature syngas s4 is used to preheat the gasification agent, saves the afterburning equipment before the gasification agent enters the gasifier, making The preheated gasification agent s23 is passed into the gasification furnace, and the semi-coke particles s2 are gasified to reduce the preheat of the reactants; the sensible heat of the high-temperature syngas s4 is used to drive the pyrolysis gas s17 reforming reaction to drive the reforming of methane, ethylene and ethane, decoupling the carbon and hydrogen in the pyrolysis gas s17, reducing the share of direct oxidation of coal fuel, realizing the cascade utilization of chemical energy, reducing irreversible losses in the gasification process.

In the embodiment of the present invention, the waste heat boiler 5 uses the heat from the first temperature range of the high-temperature syngas s4 from the gasification furnace 4 to preheat the gasifying agent s22 required for the gasification reaction; and the waste heat boiler 5 utilizes The heat in the second temperature range of the high-temperature syngas s4 from the gasifier 4 provides energy for the reforming reaction of the pyrolysis gas s17; the temperature in the first temperature range is higher than that in the second temperature range. Through the cascade utilization of different temperature sections, the full utilization of chemical energy is further realized, and the heat exchange temperature difference in the gasifier is further reduced.

In the embodiment of the present invention, a first mixer 6 is also arranged in the waste heat boiler 5 and the syngas purification unit 7, and the inlet of the first mixer 6 is connected with the waste heat boiler 5 through a pipe, so that the gas from the waste heat boiler 5 The synthetic gas s5 is passed into the first mixer 6; the other inlet of the first mixer 6 is connected with the reforming reaction device from the waste heat boiler 5 through a pipeline, so that the reformed gas s18 is input into the first mixer through a pipeline. A mixer 6 is fully mixed with the synthesis gas s5, in which the temperature of the high-temperature synthesis gas s4 discharged from the gasifier is 1300-1500 ° C, and the synthesis gas obtained when it is discharged through the branch pipeline after passing through the waste heat boiler 5 for heat exchange and cooling The temperature of s5 is 210-250°C. It should be noted that the composition of the reformed gas s18 includes hydrogen and carbon monoxide, and the composition of the synthesis gas s5 includes a mixture of hydrogen, carbon monoxide, carbon dioxide and water vapor. The two are only slightly different in the content of hydrogen and carbon monoxide. Therefore, After the first mixer 6 is fully mixed, the mixed gas formed when flowing out of the first mixer 6 is collectively referred to as the mixed gas s6 of the syngas.

In an embodiment of the present invention, the combustion system also includes: an air separation unit 2, adapted to purify the incoming oxygen; and a second mixer 13, adapted to mix the air with the purified oxygen to obtain gasification agent s22, and pass the gasification agent s22 into the waste heat boiler 5. Among them, the air separation unit 2 has a double-flow structure, including a container-type shell and internal partitions. The processes are connected by pipelines, and the inside of the process can be composed of fillers or membranes as required. The air separation unit 2 is mainly used to separate and purify the incoming air s3, so that the gas flowing out of the air separation unit 2 is oxygen s20. The incoming water s21 enters the second mixer 13 and fully mixes with the oxygen s20 from the air separation unit 2 to form a gasifying agent s22 which is transported to the waste heat boiler 5 for preheating through pipelines.

In the embodiment of the present invention, the combustion system further includes: a syngas purification unit 7 and a pre-combustion CO ₂ capture unit 8 . Among them, the syngas purification unit 7 is suitable for purifying the syngas s5; and the pre-combustion CO ₂ capture unit 8 is suitable for reacting CO in the syngas to obtain CO ₂ , capturing the CO ₂ and discharging it out of the combustion system.

Specifically, the synthesis gas purification unit 7 is mainly used to remove impurities and ash in the synthesis gas s5, so as to ensure the purity and quality of the synthesis gas s5. The synthesis gas purification unit 7 is provided with a filter, for example, mechanical filtration can be used to remove the synthesis gas Large particle impurities in s5, and then add chemical adsorbent in the adsorption tower to absorb the ash and other impurity gases in the synthesis gas s5. The syngas purification unit 7 can also add a demister as needed to remove liquid water and grease in the adsorbed syngas to avoid impact on subsequent equipment. The pre-combustion CO ₂ capture unit 8 is used to capture the carbon dioxide in the mixed gas s7 of the syngas to reduce its emission, thereby reducing the emission of greenhouse gases and helping to protect the environment.

Further, the pre-combustion CO ₂ capture unit 8 includes a CO ₂ conversion unit and a CO ₂ capture unit, the CO ₂ conversion unit is suitable for oxidizing CO in the syngas to obtain CO ₂ ; the CO ₂ capture unit is suitable for capturing and obtaining The carbon dioxide s8 is discharged from the combustion system. The pre-combustion CO ₂ capture unit 8 may also be provided with an air inlet and a pressure eliminator. The mixed gas s7 of the syngas enters the pre-combustion CO ₂ capture unit 8 through the air inlet, and first passes through the CO ₂ conversion unit to oxidize the CO in the mixed gas s7 of the syngas to generate _{CO 2 .} The gas from the outlet of the unit only includes water vapor, CO ₂ and hydrogen, and then passes through the CO ₂ capture unit, where the adsorbent layer is used to capture and store carbon dioxide s8, and then the depressurizer is used to decompress the adsorbent that has absorbed carbon dioxide layer, release the carbon dioxide s8 and discharge it out of the system, for example, the carbon dioxide s8 discharged from the system can be captured by the air capture bag, and 90% of the CO ₂ in the combustion system can be captured by this capture method, realizing the The clean, efficient and low-carbon utilization of coal is conducive to environmental protection.

In the embodiment of the present invention, the combustion system further includes: a gas turbine 9 , a splitter 10 , a waste heat boiler 11 and a steam turbine 12 .

The gas turbine 9 is suitable for making the hydrogen in the mixture s9 of hydrogen and water vapor mixed with the air (not shown in the figure) fed into it for combustion to obtain flue gas and generate the first heat and the second heat, the first heat to be produced Converted to electrical energy output system.

The splitter 10 is suitable for splitting the second heat from the gas turbine, transferring a part of the second heat to the pyrolyzer 1, providing heat for the pyrolysis reaction of the coal fuel s1, and transferring the other part of the second heat Passed to waste heat boiler 11.

The waste heat boiler 11 is suitable for recovering sensible heat from the high-temperature flue gas s11 from the gas turbine 9 and another part of the second heat.

The steam turbine 12 utilizes steam s13 from the waste heat boiler 11 to expand and generate electricity.

Specifically, as shown in Figure 1, the gas turbine 9 is provided with a first outlet and a second outlet, and the mixture gas s9 of hydrogen and water vapor is passed into the gas turbine 9 through a pipeline, and the hydrogen gas is combusted in the gas turbine to make the incoming gas The air heats up and expands, driving the turbine to rotate, which in turn drives the generator to work. The gas turbine 9 is provided with a compressor, a combustion chamber and a turbine as required, wherein the compressor compresses the incoming air through a series of rotor blades, and then enters the combustion chamber, injects hydrogen fuel into the combustion chamber, and after ignition and combustion A first heat and a second heat are generated, wherein the first heat is output P through a turbine-driven mechanical device.

The flow divider 10 divides the second heat from the gas turbine 9, and transports a part of the second heat to the pyrolyzer 1 through a closed delivery pipeline to provide heat for the pyrolysis reaction of coal fuel, and transfer the second heat to the pyrolysis device. The other part is passed to the waste heat boiler 11 through pipelines.

The structure of the waste heat boiler 11 is mainly composed of a furnace body, a flue exhaust duct, a waste heat recovery device, and a condenser. The waste heat boiler 11 recovers the heat contained in the high-temperature flue gas s11 through waste heat recovery devices, condensers and other equipment, and then transfers the heat to the incoming water s12, so that when the water vapor s13 flows out of the waste heat boiler 11, it will be heated and heated, and then Make sufficient preparations for the next generation of power generation. Therefore, the waste heat boiler is also a kind of heat exchanger. Compared with the waste heat boiler 5, the heat recovery efficiency of the waste heat boiler 11 is higher, which can greatly reduce energy consumption, and can also enhance environmental protection and protect the environment.

Further, the steam turbine 12 utilizes the energy generated by the steam s13 from the waste heat boiler 11 to drive the generator. The structure of the steam turbine 12 mainly includes a steam turbine. The steam turbine is a relatively key component of the steam turbine. There are a series of blades inside it. Water vapor s13 impacts the blades to generate a relatively large power in the turbine, thereby driving the mechanical equipment to work, and finally driving the generator to generate electricity to realize the electrical energy output P.

Fig. 2 shows a flow chart of a method for staged gasification and combustion of coal fuel in an embodiment of the present invention. As shown in Fig. 2, the method for staged gasification and combustion of coal fuel includes S201-S203.

In operation S201 , the coal fuel s1 is passed into the pyrolyzer 1 to perform a pyrolysis reaction and absorb heat to obtain a mixture s16 of semi-coke particles s2 , tar and pyrolysis gas.

In operation S202, the mixture s16 of tar obtained by pyrolysis and pyrolysis gas is passed to the pyrolysis product purification and separation unit 3 for separation, and the separated tar s19 and semi-coke particles s2 obtained by pyrolysis are respectively input into the gas The gasification furnace 4 performs a gasification reaction with the gasification agent s23 preheated by the waste heat boiler to prepare high-temperature synthesis gas s4.

In operation S203, the pyrolysis gas s17 from the pyrolysis product purification and separation unit 3 is input to the waste heat boiler 5 and reformed with water in the high-temperature syngas s4 to obtain reformed gas s18.

In an embodiment of the present invention, the reformed gas includes CO, H ₂ ; the synthesis gas includes CO, H ₂ , H ₂ O, CO ₂ .

In the embodiment of the present invention, the temperature of the high-temperature syngas s4 before entering the waste heat boiler 5 is 1300-1500° C.; the temperature of the mixture of the low-temperature syngas s5 and the reformed gas s18 passing through the outlet of the waste heat boiler 5 is 200-300° C. ℃. Specifically, after the semi-coke particles s2 and tar s19 enter the gasifier 4 from different inlets, they undergo gasification reactions to release heat, so that the temperature of the high-temperature syngas s4 discharged from the gasifier 4 is 1300-1500°C , the high-temperature synthesis gas s4 is passed into the waste heat boiler 5 for heat release, and the heat is transferred to the gasification agent s22 fed into the other inlet of the waste heat boiler 5, and the temperature of the gasification agent s22 is raised to between 800-1000°C, The preheated gasification agent s23 is passed into the gasification furnace 4; the pyrolysis gas s17 from the pyrolysis product purification and separation unit 3, including methane, ethylene and ethane, is heated up after heat exchange by the waste heat boiler 5 to 700-900°C, through the setting of the waste heat boiler 5, the sensible heat release of the synthesis gas 4 is applied to the preheating and supplementary combustion of the gasification agent s22 and the pyrolysis gas s17, which further realizes the cascade utilization of chemical energy and reduces the The heat transfer temperature difference in the gasifier.

It should be noted that the coal fuel staged gasification combustion system and combustion method proposed in the embodiments of the present invention can decouple the coal gasification process into a pyrolysis process and a gasification process, and use part of the exhaust gas of the gas turbine 9 as coal Heat is supplied during the pyrolysis process of the fuel, the heat in the first temperature range of the high-temperature syngas s4 is used to preheat the gasification agent s22 required by the gasifier 4, and the heat in the second temperature range of the high-temperature syngas s4 is used to drive pyrolysis For gas s17 reforming, the heat in the first temperature range and the heat in the second temperature range are all heat above 900°C, and the remaining heat below 900°C is used for transfer in the combustion system, and finally steam is generated to drive the steam turbine to do work. In this way, through the graded utilization of the heat obtained from the combustion and gasification of coal fuel, the share of direct combustion of coal can be reduced, and the demand for oxygen and the energy consumption of air separation can be reduced. At the same time, the pre-combustion CO ₂ capture method can capture 90% of the CO ₂ in the system, and finally realize the clean, high-efficiency, and low-carbon utilization of coal.

The coal fuel staged gasification combustion system and combustion method in the embodiment of the present invention will be further described below in conjunction with a specific embodiment. It should be understood that this specific embodiment is only for those skilled in the art to better understand the present invention. The technical solution of the invention should not be regarded as an improper limitation of the protection scope of the present invention.

Embodiment one

Continue as shown in Figures 1 to 2, the flow rate of coal fuel s1 into the coal fuel staged gasification combustion system used in the embodiment of the present invention is 62727.34kg/h, the pressure is 1.01bar, and the temperature is 25°C. Coal fuel s1 undergoes pyrolysis reaction in pyrolyzer 1 to obtain semi-coke particles s2 and mixture s16 of tar and pyrolysis gas. The flow rate of the obtained semi-coke particles s2 is 41553.54kg/h, the pressure is 1.01bar, and the temperature is 600°C; the flow rate of the obtained tar and pyrolysis gas mixture s16 is 20821.80kg/h, the pressure is 1.067bar, and the temperature is 600°C ℃, the mixture s16 of tar and pyrolysis gas is passed into the pyrolysis product purification and separation unit 3 for separation and purification, the flow rate of the obtained pyrolysis gas s17 is 10235.15kg/h, the pressure is 1.067bar, and the temperature is 76.40°C, the flow rate of the obtained tar s19 is 8843.33kg/h, the pressure is 1.067bar, and the temperature is 76.40°C, the tar s19 and semi-coke particles s2 are respectively gasified in the gasifier 4 with the gasification agent s23 to obtain The high-temperature syngas s4 has a flow rate of 158862.82kg/h, a pressure of 34.00bar, and a temperature of 1400°C. The high-temperature syngas s4 includes CO ₂ , 0.27 CO, 0.25 H ₂ , and 0.28 mole fractions respectively. H ₂ O, also includes N ₂ with a mole fraction of 0.11.

The flow rate of water s21 is 54434.57kg/h, the pressure is 34.00bar, and the temperature is 25.00℃, the flow rate of air s3 is 144910.24kg/h, the pressure is 1.01bar, the temperature is 25.00℃, and the air s3 flows through Air separation unit 2 performs purification to obtain oxygen s20 with a flow rate of 35277.70kg/h, a pressure of 34.00bar, and a temperature of 300.55°C, wherein the proportion of oxygen obtained is more than 95%. Oxygen s20 and water s21 are mixed in the second mixer 13 to obtain a gasification agent s22 with a flow rate of 89712.27kg/h, a pressure of 34.00bar, and a temperature of 58.20°C. After heat exchange between the waste heat boiler 5 and the high-temperature syngas s4 , the flow rate and pressure of the obtained gasification agent s23 remain unchanged, the temperature is raised from 58.2°C to 900.01°C, and then the gasification agent s23 is passed into the gasification furnace 4 for gasification reaction with semi-coke particles s2 and tar s19.

The pyrolysis gas s17, which has been purified by pyrolysis products and separated by the separation unit 3, is passed into the waste heat boiler 5 for reforming reaction. The flow rate of s18 is 10235.15kg/h, the pressure is 1.067bar, and the temperature is 850°C. It is further mixed with the synthesis gas s5 flowing out of the waste heat boiler 5 in the first mixer 6. The flow rate of the synthesis gas s5 is 158862.82kg/h, The pressure is 32.86bar and the temperature is 216.01°C. After mixing, the flow rate and pressure of the mixed gas s6 of the syngas and the mixed gas s7 of the syngas treated by the syngas purification unit 7 remain unchanged, respectively 164610.27kg/h and 32.58bar, the temperature is lowered from 210.05°C of s6 to 199.42°C of s7, and then _CO2 is captured by the _CO2 capture unit before combustion, and the temperature of the obtained carbon dioxide s8 is 39.37°C, the pressure is 100.00bar, and the flow rate is 121435.44 kg/h. The flow rate of the separated hydrogen and water vapor mixture s9 is 60837.34kg/h, the pressure is 30.00bar, and the temperature is 169.55°C. After passing through the gas turbine 9, the hydrogen in it is mixed with the incoming air and combusted to release heat. From the gas turbine 9 The flow rate of the high-temperature flue gas s10 is 889224.32kg/h, the pressure is 1.067bar, and the temperature is 650°C. The high-temperature flue gas s10 is divided into s11 and s14 through the splitter 10, and the flow rate of the high-temperature flue gas s11 is 806834.64kg/h h. The pressure is 1.067bar, the temperature is 650°C, the flow rate of high-temperature flue gas s14 is 82389.69kg/h, the pressure is 1.067bar, and the temperature is 650°C. The high-temperature flue gas s14 is used to provide coal fuel s1 for pyrolyzer 1 For the heat of pyrolysis, the temperature of the incoming water s12 is 25°C. After the high-temperature flue gas s11 is heated in the waste heat boiler 11, the temperature of the outgoing water s13 is 566°C, which flows into the steam turbine 12 for expansion and power generation.

A coal fuel staged gasification combustion system in Example 1 of the present invention is simulated and calculated, and compared with a conventional _CO2 capture power generation system before coal gasification combustion, the parameters of the system are shown in Table 1.

Table 1 Energy balance table of two coal gasification power generation systems

It can be seen from Table 1 that under the condition that the input energy is 397.78MW and the carbon capture rate is 90%, the net power output of the coal fuel staged gasification combustion system is 160.13MW, compared with the conventional coal gasification The net electrical output (149.50MW) of the pre-combustion _CO2 capture power generation system increased by 7.11%. On the one hand, it is because the power output of the gas turbine in the coal fuel staged gasification combustion system is much higher than that of the CO ₂ capture power generation system before the conventional coal gasification combustion. On the other hand, the energy consumption of the air separation unit and the oxygen compressor of the coal fuel staged gasification combustion system is lower than that of the CO ₂ capture power generation system before the conventional coal gasification combustion. The coal fuel staged gasification combustion system in the embodiment of the present invention replaces the heat released by direct combustion of coal in the gasification process by using the chemical heat recovery method to replace part of the waste heat of exhaust gas from the gas turbine and the sensible heat of the synthesis gas. The net power generation efficiency of the final power generation system reaches 40.26%, which is 2.68% higher than that of the _CO2 capture power generation system (37.58%) before conventional coal gasification combustion. At the same time, the CO ₂ emission per unit of electricity is 84.64g/kWh, which is 6.63% lower than that of the CO ₂ capture power generation system (90.65g/kWh) before conventional coal gasification combustion.

The coal fuel graded gasification combustion system and combustion method provided by the embodiments of the present invention mainly include: a pyrolyzer 1, an air separation unit 2, a pyrolysis product purification and separation unit 3, a gasifier 4, and a waste heat boiler 5. First mixer 6, synthesis gas purification unit 7, pre-combustion _CO2 capture unit 8, gas turbine 9, splitter 10, waste heat boiler 11, steam turbine 12. The combustion system decouples the coal gasification process into a pyrolysis process and a gasification process, uses gas turbine 9 waste heat to provide heat for the coal pyrolysis process, and obtains a part of the pyrolysis gas s16, and sends the remaining semi-coke particles s2 and tar s19 into the Going to the gasification furnace 4 for gasification reduces the proportion of coal fuel s1 directly burned and reduces the irreversible loss in the gasification process. In addition, the sensible heat of the high-temperature syngas s4 at the outlet of the gasification furnace 4 is used to preheat the gasification agent s22 and drive the reforming of the pyrolysis gas s17, which reduces the heat exchange temperature difference in the gasification furnace 4 while utilizing the thermal energy in stages , and completely decouple the carbon and hydrogen in CH ₄ , C ₂ H ₄ , and C ₂ H ₆ in pyrolysis gas s17. In addition, the pre-combustion _CO2 capture unit 8 is used to capture 90% of the _CO2 in the system, realizing the clean, efficient and low-carbon utilization of coal fuel s1.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (10)

1. A staged gasification combustion system of coal fuel, comprising: Pyrolyzer, suitable for pyrolyzing coal fuel and absorbing heat to obtain semi-coke particles, tar and pyrolysis gas; The pyrolysis product purification and separation unit is suitable for separating the tar and pyrolysis gas from the pyrolyzer to obtain the separated tar and separated pyrolysis gas; The gasification furnace is suitable for the gasification reaction of the semi-coke particles from the pyrolyzer and the tar from the pyrolysis product purification and separation unit with the gasification agent preheated by the waste heat boiler to release heat to prepare a synthetic gas; and A waste heat boiler, suitable for reforming the pyrolysis gas from the pyrolysis product purification and separation unit with the water in the synthesis gas to obtain reformed gas; Wherein, the pyrolysis gas includes methane, ethane and ethylene. 2. The combustion system of claim 1, wherein: The waste heat boiler preheats the gasification agent required for the gasification reaction by using the heat from the first temperature range of the syngas from the gasification furnace; and The waste heat boiler provides energy for the reforming reaction of the pyrolysis gas by using the heat from the second temperature range of the syngas from the gasification furnace; Wherein, the temperature in the first temperature range is higher than that in the second temperature range. 3. The combustion system of claim 1, further comprising: a synthesis gas cleaning unit adapted to clean said synthesis gas; and The pre-combustion CO ₂ capture unit is suitable for reacting the CO in the synthesis gas to obtain CO ₂ , and capturing the CO ₂ to discharge it from the combustion system. 4. The combustion system of claim 3, further comprising: The gas turbine is suitable for mixing and burning the hydrogen in the synthesis gas with the incoming air to obtain high-temperature flue gas and generate first heat and second heat, and convert the generated first heat into an electric energy output system; A splitter, suitable for splitting the second heat from the gas turbine so that part of the second heat is transferred to the pyrolyzer to provide heat for the pyrolysis reaction of coal fuel, and the other part of the second heat is transferred to the waste heat boiler; Waste heat boiler, suitable for recovering sensible heat from the high-temperature flue gas from the gas turbine and another part of the second heat; and The steam turbine uses the water vapor from the waste heat boiler to expand and generate electricity. 5. The combustion system of claim 1, further comprising, an air separation unit adapted to purify incoming oxygen; and The second mixer is suitable for mixing air and purified oxygen to obtain the gasification agent, and pass the gasification agent into the waste heat boiler. 6. The combustion system according to claim 3, wherein a first mixer is further provided in the waste heat boiler and the syngas cleaning unit. 7. The combustion system of claim 3, wherein: The pre-combustion _CO2 capture unit includes a _CO2 shift unit and a _CO2 capture unit, The _CO2 shift unit is adapted to oxidize CO in the syngas to _CO2 ; The CO ₂ capture unit is adapted to capture the resulting CO ₂ and exhaust it from the combustion system. 8. A method of combustion, using the combustion system according to any one of claims 1-7, said method comprising: Pass the coal fuel into the pyrolyzer, carry out pyrolysis reaction and absorb heat, and obtain semi-coke particles, tar and pyrolysis gas; The tar and pyrolysis gas obtained by pyrolysis are passed into the pyrolysis product purification and separation unit for separation, and the separated tar and semi-coke particles obtained by pyrolysis are respectively input into the gasifier and the gas preheated by the waste heat boiler. gasification reaction with chemical agent to prepare synthesis gas; and The pyrolysis gas from the pyrolysis product purification and separation unit is input to the waste heat boiler and undergoes reforming reaction with the water in the synthesis gas to obtain reformed gas. 9. The method of claim 8, wherein, The reformed gas includes CO, H ₂ ; The synthesis gas includes CO, H ₂ , H ₂ O, CO ₂ . 10. The method of claim 8, wherein, The temperature of the synthesis gas before entering the waste heat boiler is 1300-1500°C; The temperature of the mixture of low-temperature synthesis gas and reformed gas passing through the outlet of the waste heat boiler is 200-300°C.