Coal hydrogen-rich synthesis gas and raw coal upgrading system and method based on iron ore particles

Abstract

The invention relates to the technical field of energy conversion and environment, in particular to a coal hydrogen-rich synthesis gas and raw coal upgrading system and method based on iron ore particles. The system comprises: a chemical looping gasification unit, which is used for producing hydrogen-rich gas through a reaction of an iron ore oxygen carrier in an oxidation state with clean coal in a reactor; wherein the iron ore oxygen carrier in the oxidation state plays roles in catalytic oxidation and synthesis gas quality adjustment, and after the iron ore oxygen carrier is changed into the reduction state, the iron ore oxygen carrier is regenerated into the oxidation state through oxidation reaction with air in the reactor; the inactivated oxygen carrier treatment unit is used for crushing and screening the inactivated oxygen carrier in the reactor to obtain a dense medium; and the separation fluidized bed unit is used for separating the coal particles through a two-phase flow formed by fluidizing gas and a dense medium so as to separate clean coal and tailings. According to the method, full-process and efficient utilization of the cheap iron ore particles is achieved, and quality improvement and ash reduction of the coal are achieved while the gasification efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of energy conversion and environmental technology, in particular to a coal-to-hydrogen-rich syngas system and method based on iron ore particles. BACKGROUND

[0002] As an innovative technology in the field of energy and environment, chemical looping gasification decouples traditional single chemical reactions into multi-stage sub-reactions, and realizes "three transmission and one reaction" through the circulation of oxygen carriers, showing great potential in the field of syngas preparation. The core of this technology lies in the oxygen release and regeneration of oxygen carriers, so as to realize the redox reaction cycle of oxygen carriers between the fuel reactor and the air reactor. Especially for solid fuels such as coal, the oxygen carriers not only need to maintain good fluidization state and reaction activity under high temperature conditions, but also need to promote the conversion of coal (the rate-limiting step of chemical looping gasification technology), both of which directly determine the stability and reaction effect of the chemical reaction cycle.

[0003] Because of the wear and activity decay of oxygen carriers, it is inevitable to supplement or replace the oxygen carriers, and the raw material cost of oxygen carriers becomes an important reason for limiting the large-scale application of chemical looping technology.

[0004] Moreover, using raw coal as raw material for chemical looping gasification reaction will increase the amount of sulfur-containing gas in the syngas, thereby increasing the subsequent processing cost, and high-ash raw coal will reduce the gasification efficiency.

[0005] Furthermore, the oxygen carriers have a certain service life, and the raw material cost and preparation cost of the oxygen carriers obtained by chemical methods are too high to be applied on a large scale. In addition, the deactivated oxygen carriers as solid waste also face the problems of resource waste and space occupation.

[0006] Therefore, it is urgent to solve the problems existing in the existing chemical looping gasification. SUMMARY

[0007] The technical problem to be solved by the present application is to overcome the defects of the prior art and provide a coal-to-hydrogen-rich syngas system based on iron ore particles, which realizes the full-process and efficient utilization of cheap iron ore particles, improves the gasification efficiency, and realizes the upgrading and ash reduction of coal.

[0008] In order to solve the above technical problems, the technical scheme of the present application is as follows: a coal-to-hydrogen-rich syngas system based on iron ore particles, comprising: A chemical looping gasification unit for producing hydrogen-rich gas by reacting with fine coal in a reactor using oxidized iron ore oxygen carriers; wherein the oxidized iron ore oxygen carriers play a role in catalytic oxidation and syngas quality adjustment, and after being reduced, they are regenerated into oxidized state by oxidizing with air in the reactor; The deactivated oxygen carrier treatment unit is used to crush and screen the deactivated oxygen carrier in the reactor to obtain heavy medium. The fluidized bed separation unit is used to separate coal particles into clean coal and tailings through a two-phase flow formed by fluidizing gas and heavy medium.

[0009] Furthermore, the reactor includes: The reaction tube is filled with iron ore oxygen carrier; Heating mechanism, used to heat the reaction tube; An air distribution plate is installed inside the reaction tube.

[0010] Furthermore, the sorting fluidized bed unit includes: A separating fluidized bed is used to separate coal particles by a two-phase flow formed by fluidizing gas and heavy medium, so as to divide the bed into two parts. An air compressor, connected to the separating fluidized bed, is used to provide the fluidizing gas required by the separating fluidized bed; The desliming screen is used to remove heavy media from two parts of the bed to obtain clean coal and tailings.

[0011] Furthermore, the particle size range of the iron ore oxygen carrier is 0.1-0.3 mm.

[0012] This invention also relates to a method for producing hydrogen-rich syngas from coal and upgrading raw coal based on iron ore particles, the method comprising: Step S1, chemical looping gasification step: hydrogen-rich gas is produced by reacting oxidized iron ore oxygen carrier with clean coal in a reactor; wherein, the oxidized iron ore oxygen carrier plays the role of catalytic oxidation and syngas quality regulation. After becoming reduced, it is regenerated into oxidized state by reacting with air in the reactor. Step S2: Deactivated oxygen carrier treatment step: After the iron ore oxygen carrier in step S1 is deactivated, the deactivated oxygen carrier is crushed and screened to obtain heavy medium; Step S3, raw coal upgrading: coal particles are separated by a two-phase flow formed by fluidized gas and heavy medium to separate clean coal and tailings.

[0013] Furthermore, at least a portion of the clean coal produced in step S3 is used as the coal in step S1 to participate in the chemical looping gasification step.

[0014] Furthermore, step S1 specifically includes: Step S11: Install the air distribution plate inside the reaction tube and check the airtightness of the reaction tube; Step S12: Iron ore oxygen carrier is added to the reaction tube at room temperature; Step S13: Continuously introduce oxidizing gas into the reaction tube and heat the reaction tube through a heating mechanism to make the ore oxygen carrier in a fully oxidized state. Step S14: Stop introducing oxidizing gas into the reaction tube and introduce inert gas into the reaction tube until the oxygen concentration drops to 0. Step S15: Start the water pump connected to the reaction tube. After condensate appears at the gas outlet of the reaction tube, heat the coal powder in the reaction tube. The coal powder reacts with the oxidized iron ore oxygen carrier to produce hydrogen-rich gas. Step S16: After the reduction reaction is complete, turn off the water pump and inert gas, and return to step S13 until the iron ore oxygen carrier is deactivated.

[0015] Furthermore, the temperature range inside reaction tube 2 is 850–950 °C.

[0016] Furthermore, prior to step S1, the following steps are also included: Step S0, preparing iron ore oxygen carrier: dry iron ore, and then fully calcine it in air atmosphere to give it the expected mechanical strength and at the same time exhibit an oxidized state. Select particles within a preset range as iron ore oxygen carriers.

[0017] By adopting the above technical solution, the present invention has the following beneficial effects: First, this invention is based on inexpensive iron ore particles and achieves efficient coal conversion through a chemical loop gasification system. The iron ore oxygen carrier plays a role in catalytic oxidation and syngas composition regulation, which solves the problem that the raw material cost and preparation cost of oxygen carriers obtained by traditional chemical methods are too high, making it difficult to carry out large-scale application. Then, the deactivated oxygen carrier is discharged from the reactor. At this time, the reduced oxygen carrier is magnetic. The deactivated oxygen carrier can replace the commonly used magnetite powder as a heavy medium, saving costs and solving the problem of high cost of fluidized separation caused by high medium consumption and high price of traditional heavy media. It also solves the problem of resource waste and space occupation caused by deactivated oxygen carrier as solid waste. Furthermore, the ash content of the clean coal obtained by gas-solid fluidized bed separation is significantly lower than that of the raw coal. As a feedstock for chemical looping gasification, it can further improve the quality of syngas and gasification efficiency. At the same time, it solves the problem that directly using raw coal as a feedstock for chemical looping gasification leads to an increase in sulfur-containing gases in the syngas, thereby increasing the subsequent processing costs. Finally, this invention simplifies operation and saves equipment costs by switching between oxidation and reduction reactions in the same reactor. Attached Figure Description

[0018] Figure 1 This is a flowchart of the coal-to-hydrogen-rich syngas and raw coal upgrading system based on iron ore particles of the present invention. Figure 2 This is a schematic diagram of the reactor structure of the present invention; In the diagram: 100, Reactor; 1, Heating mechanism; 2, Reaction tube; 2a, Gas outlet; 2b, Water inlet; 2c, Pulverized coal inlet; 2d, High-pressure gas inlet; 3, Clamp; 4, T-joint; 5, Thermocouple sheath; 6, Thermocouple; 7, Water pipe sheath; 7a, Water pipe; 8a, Ball valve one; 8b, Ball valve two; 8c, Ball valve three; 9, Air distribution plate; 10, Air distribution plate support rod; 11, Stainless steel wire mesh; 12, Main input pipe; 13a, Pressure measuring hole one; 13b, Pressure measuring hole two. Detailed Implementation

[0019] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0020] like Figure 1 and Figure 2 As shown, a coal-to-hydrogen-rich syngas and raw coal upgrading system based on iron ore particles includes: The chemical looping gasification unit is used to produce hydrogen-rich gas by reacting oxidized iron ore oxygen carrier with clean coal in reactor 100; wherein, the oxidized iron ore oxygen carrier plays the role of catalytic oxidation and syngas quality regulation. After being reduced to a reduced state, it is regenerated into an oxidized state by reacting with air in reactor 100. The deactivated oxygen carrier treatment unit is used to crush and screen the deactivated oxygen carrier in reactor 100 to obtain heavy medium. The fluidized bed separation unit is used to separate coal particles into clean coal and tailings through a two-phase flow formed by fluidizing gas and heavy medium.

[0021] In this embodiment, the chemical looping gasification unit includes a heating system, a reactor 100, a gas supply system, and an analysis and detection system.

[0022] The heating system mainly consists of heating mechanism 1, which can be a heating furnace, used to heat the reaction tube 2. The final temperature setting is based on the feedback from the thermocouple 6 inside the reaction tube 2. The reaction tube 2 is fitted with a stainless steel thermocouple sheath 5, which is located in a fluidized particle bed during the reaction. The thermocouple is placed in the sheath to measure the temperature of the bed in real time during the reaction. The function of the thermocouple sheath 5 is to prevent the thermocouple 6 from direct contact with the oxygen carrier particles and coal powder, thus extending the service life of the thermocouple.

[0023] like Figure 2As shown, the reaction tube 2 is equipped with a gas outlet 2a, a water inlet 2b, a pulverized coal inlet 2c, and a high-pressure air inlet 2d. A tee connector 4 is installed at the bottom of the reaction tube 2. One of the interfaces of the tee connector 4 is connected to the input main pipe 12. A pressure measuring port 13a is provided on the gas outlet 2a, and a pressure measuring port 13b is provided on the input main pipe 12. A differential pressure gauge is connected between the pressure measuring ports 13a and 13b. The two ends of the differential pressure gauge are connected to the pressure measuring port 13a at the gas outlet 2a and the pressure measuring port 13b on the input main pipe 12, respectively, to collect the pressure inside the reaction tube 2 in real time, thereby determining the fluidization state of the oxygen-carrying bed material.

[0024] The gas supply system includes inert gas cylinders, oxidizing gas cylinders, flow meters, and pulse valves, with the pulse valves connected to the inert gas cylinders. The analysis and detection system includes a particulate filter, a condenser, and a flue gas analyzer, which collects and transmits data in real time. Gas outlet 2a is connected sequentially to the particulate filter, condenser, and flue gas analyzer via pipelines. The flue gas analyzer collects data at 1-second intervals, and the syngas quality is analyzed based on the collected data.

[0025] An air distribution plate 9 is arranged inside the reaction tube 2. The air distribution plate 9 is installed inside the reaction tube 2 via an air distribution plate support rod 10. The air distribution plate support rod 10 can move freely relative to the tee joint 4, thereby adjusting the position of the air distribution plate 9 relative to the pulverized coal inlet pipe 2c. The air distribution plate 9 is located below the pulverized coal inlet pipe 2c, and unloading is performed by removing the air distribution plate 9. To facilitate the movement of the air distribution plate 9, a gap is left between it and the inner wall of the reaction tube 2. To prevent iron ore oxygen carrier particles from falling through the air holes of the air distribution plate 9 or through the gap between the air distribution plate 9 and the wall of the reaction tube 2, it is covered with a stainless steel wire mesh 11, which can be made of 310S.

[0026] A water pipe sleeve 7 is connected to the water inlet 2b, and a water pipe 7a is inserted inside the water pipe sleeve 7. A constant pressure water pump is connected to the water pipe 7a, continuously supplying deionized water at a set flow rate to the lower end of the air distribution plate 9. The water vapor generated at high temperature mixes with the inert fluidizing gas to form the fluidizing gas in the reduction reaction process. Based on this, the steam generator and heat tracing device are eliminated, and the actual steam supply is precisely controlled.

[0027] Ball valve 1 8a and ball valve 2 8b are sequentially installed from the end furthest from the reaction pipe 2 to the end closest to the reaction pipe. High-pressure gas inlet 2d is connected between ball valve 1 8a and ball valve 2 8b. Ball valve 3 8c is installed on high-pressure gas inlet 2d. Ball valve 3 8c is connected to a pulse valve to control the supply of high-pressure inert gas, and the supply time is extremely short.

[0028] The reaction tube 2 is made of 310S stainless steel, which offers better corrosion resistance and high-temperature strength compared to 304 stainless steel. The reaction tube 2 is filled with iron ore oxygen carrier particles and is in a high-temperature fluidized state. The fluidizing gas during the reduction process is a mixture of inert gas and water vapor, while the fluidizing gas during the oxidation process comes from an oxidizing gas cylinder. The reaction atmosphere can be switched arbitrarily. After the reaction, the gaseous products are discharged from the gas outlet 2a at the top of the reaction tube 2. The iron ore oxygen carrier particles are derived from iron ore, and the lattice oxygen released by the active components and its reduced phase can promote coal conversion. The preferred particle size range for the iron ore oxygen carrier is 0.1-0.3 mm.

[0029] In this embodiment, the deactivated oxygen carrier treatment unit includes a crushing and screening machine and a heavy medium storage tank. The crushing process is mainly for the sintered oxygen carrier. All particles are screened to obtain particles that meet the particle size requirements of heavy medium, and then enter the heavy medium storage tank for storage.

[0030] In this embodiment, the sorting fluidized bed unit includes: A separating fluidized bed is used to separate coal particles by a two-phase flow formed by fluidizing gas and heavy medium, so as to divide the bed into two parts. An air compressor, connected to the separating fluidized bed, is used to provide the fluidizing gas required by the separating fluidized bed; The desliming screen is used to remove heavy media from two parts of the bed to obtain clean coal and tailings.

[0031] The heavy media mixed with pulverized coal are diverted. One part enters the circulating media bin for direct use in the fluidized bed separator, while the other part enters the magnetic separator for pulverized coal removal and then enters the circulation system. The heavy media lost (such as those carried out by the product) are replenished by the heavy media storage bin.

[0032] The method for producing hydrogen-rich syngas from coal and upgrading raw coal based on the above system includes: Step S0, Iron Ore Oxygen Carrier: Before use, the iron ore needs to be dried and then fully calcined in air to give it a certain mechanical strength and to make it exhibit an oxidized state, in which the content of the active component Fe2O3 is 82.6 wt.%. 0.10-0.30 mm particles are screened out and used directly as iron ore oxygen carriers.

[0033] Step S1, chemical looping gasification step: Hydrogen-rich gas is produced by reacting oxidized iron ore oxygen carrier with clean coal in reactor 100; wherein, the oxidized iron ore oxygen carrier plays the role of catalytic oxidation and syngas quality regulation. After becoming reduced, it is regenerated into oxidized state by reacting with air in reactor 100; the temperature range in reaction tube 2 is generally controlled between 850 and 950 ℃. Too high a temperature can easily cause the oxygen carrier particles to sinter and agglomerate, while too low a temperature will make the conversion rate of coal particles too slow.

[0034] Step S2: Deactivated oxygen carrier treatment step: After the iron ore oxygen carrier in step S1 is deactivated, the deactivated oxygen carrier is crushed and screened to obtain heavy medium; wherein, the deactivated oxygen carrier particles are in a reduced state, and the reduced phase is Fe3O4, which is magnetic.

[0035] Step S3, raw coal upgrading: coal particles are sorted by a two-phase flow with a certain density formed by fluidized gas and heavy medium to separate clean coal and tailings. At least a portion of the clean coal is used as the coal in step S1 to participate in the chemical looping gasification step.

[0036] Specifically, step S1 may include: Step S11: Install the air distribution plate 9 inside the reaction tube 2, install the clamp 3, connect the water pipe, and check the airtightness of the reaction tube 2. Step S12: Iron ore oxygen carrier is added to reaction tube 2 at room temperature; Step S13: Open the oxidizing gas cylinder (which can be an air cylinder), continuously introduce oxidizing gas into the reaction tube 2, and heat the reaction tube 2 through the heating mechanism 1 so that the ore oxygen carrier is in a fully oxidized state. Step S14: Close the oxidizing gas cylinder and open the inert gas cylinder (which can be a nitrogen cylinder with a flow rate of 1 L / min). Inert gas is introduced into the reaction tube 2 until the oxygen concentration drops to 0. Then, open ball valve 8a and add pulverized coal into the pulverized coal inlet pipe 2c. Then, close ball valve 8a. Start the pulse valve, open ball valve 8c, and close it momentarily. Step S15: Start the constant pressure water pump (flow rate can be 0.8 g / min). When condensate appears at gas outlet 2a of reaction tube 2, the water vapor concentration in the reaction zone is considered to have reached the set value. At this point, open ball valve 2b. Due to the pressure difference, pulverized coal instantly enters reaction tube 2 and reacts with the oxygen carrier, meaning the pulverized coal instantly enters the high-temperature reaction zone. Then, close ball valve 2b. The pulverized coal reacts with the oxidized iron ore oxygen carrier to produce hydrogen-rich gas. Step S16: After the reduction reaction is complete, turn off the constant pressure water pump and inert gas cylinder, and return to step S13 until the iron ore oxygen carrier is deactivated.

[0037] The temperature range within reaction tube 2 can be 850–950 °C. The pressure range of the high-pressure inert gas can be 0.1–0.2 MPa. The high-pressure gas injection time controlled by the pulse valve is less than 10 ms.

[0038] In some specific examples, when the oxygen-fuel ratio is 0.5 and the temperature is 950°C... o At temperature C, the syngas production and H2 / CO ratio corresponding to iron ore are 0.78 Nm³. 3 / kg coal and 3.90.

[0039] When the oxygen-fuel ratio is 0.2 and the temperature is 950°C o At temperature C, the syngas production and H2 / CO ratio corresponding to iron ore are 1.30 Nm³. 3 / kg coal and 3.21.

[0040] Iron ore oxygen carrier at an oxygen-fuel ratio of 0.2 and a temperature of 950°C o Multiple chemical looping gasification reaction cycles were performed under C conditions until the oxygen carrier particles were sintered or the reactivity was significantly reduced.

[0041] This shows that iron ore particles are suitable for the preparation of hydrogen-rich syngas, achieving a hydrogen-to-carbon ratio greater than 3.0, while the reduction in the oxygen-fuel ratio is beneficial for increasing syngas production.

[0042] The separating fluidized bed is cylindrical in shape, made of plexiglass, and has an inner diameter of 140 mm. Two types of lignite are used as raw coal: -13+6 mm (particle size greater than 6 mm but less than or equal to 13 mm) and -6+3 mm (particle size greater than 3 mm but less than or equal to 6 mm), with corresponding ash contents of 27.56 wt.% and 26.78 wt.%, respectively.

[0043] In some examples, when the fluidization number is 1.4, the bed height is 120 mm, and the coal particle size is -13 to +6 mm, the clean coal ash content of the deactivated iron ore is 14.38 wt.%.

[0044] When the fluidization number is 1.4, the static bed height is 120 mm, and the coal particle size is -6 to +3 mm, the clean coal ash content of the deactivated iron ore is 15.25 wt.%.

[0045] This shows that deactivated iron ore particles are suitable as a heavy medium in fluidized bed separation, which can significantly reduce the ash content of raw coal, while increasing the particle size of coal particles is beneficial to improving the segregation effect.

[0046] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A system for producing hydrogen-rich syngas and upgrading raw coal based on iron ore particles, comprising: a chemical looping gasification unit for producing hydrogen-rich syngas by reacting oxidized iron ore oxygen carriers with clean coal in a reactor; wherein the oxidized iron ore oxygen carriers serve as catalysts for oxidation and syngas quality adjustment, and are regenerated into oxidized state by oxidizing with air in the reactor after being reduced to a reduced state; a deactivated oxygen carrier treatment unit for crushing and screening the deactivated oxygen carriers in the reactor to obtain heavy medium; and a fluidized bed separation unit for separating clean coal and tail coal by using a two-phase flow of fluidizing gas and heavy medium to separate coal particles. 2.The system according to claim 1, wherein the reactor comprises: a reaction tube containing the iron ore oxygen carriers; a heating mechanism for heating the reaction tube; and a wind distribution plate installed in the reaction tube. 3.The system according to claim 1, wherein the fluidized bed separation unit comprises: a fluidized bed for separating coal particles by using a two-phase flow of fluidizing gas and heavy medium to divide the bed into two parts; an air compressor connected to the fluidized bed for providing fluidizing gas required by the fluidized bed; and a medium removal screen for removing heavy medium from the two parts of the bed to obtain clean coal and tail coal. 4.The system according to claim 1, wherein the particle size of the iron ore oxygen carriers ranges from 0.1 mm to 0.3 mm. 5.A method for producing hydrogen-rich syngas and upgrading raw coal based on iron ore particles, comprising: a chemical looping gasification step S1 for producing hydrogen-rich syngas by reacting oxidized iron ore oxygen carriers with clean coal in a reactor; wherein the oxidized iron ore oxygen carriers serve as catalysts for oxidation and syngas quality adjustment, and are regenerated into oxidized state by oxidizing with air in the reactor after being reduced to a reduced state; a deactivated oxygen carrier treatment step S2 for crushing and screening the deactivated oxygen carriers to obtain heavy medium; and a raw coal upgrading step S3 for separating clean coal and tail coal by using a two-phase flow of fluidizing gas and heavy medium to separate coal particles. 6.The method according to claim 5, wherein the step S1 specifically comprises: a step S11 for installing a wind distribution plate in a reaction tube and checking the air tightness of the reaction tube; a step S12 for adding iron ore oxygen carriers into the reaction tube at room temperature; a step S13 for continuously introducing oxidizing gas into the reaction tube and heating the reaction tube by a heating mechanism to make the iron ore oxygen carriers in a fully oxidized state; and a step S14 for stopping the introduction of oxidizing gas into the reaction tube and introducing inert gas into the reaction tube until the oxygen concentration is reduced to 0. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Step S15, start the water pump connected to the reaction tube, after the gas outlet of the reaction tube appears condensate, add heated coal powder into the reaction tube, the coal powder reacts with the oxidized iron ore oxygen carrier to produce hydrogen-rich gas; Step S16, after the reduction reaction is completed, close the water pump and inert gas, return to step S13 until the iron ore oxygen carrier is deactivated.

7. The method according to claim 6, wherein the temperature in the reaction tube is in the range of 850-950 ℃.

8. The method according to claim 5, wherein before step S1, the method further comprises: Step S0, preparing the iron ore oxygen carrier: drying the iron ore, and then fully calcining under air atmosphere to make it have the expected mechanical strength and present the oxidized state, and screening the particles in the preset size range as the iron ore oxygen carrier. ​ ​

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