Method for coal gasification of segmented conversion fluidized bed and gasification furnace thereof

Abstract

The invention belongs to the technical field of coal gasification, and particularly relates to a segmented conversion fluidized bed coal gasification method and a gasification furnace thereof, the segmented conversion gasification furnace comprises a pyrolysis gasification reactor, a agglomerated ash separation unit and a dipleg fine powder circulation unit; the pyrolysis gasification reactor comprises a cylindrical furnace body, the lower end of the cylindrical furnace body is fixedly connected with a lower concentrated phase fluidized bed furnace body, and the lower concentrated phase fluidized bed furnace body is connected with a crushed coal feeding pipe, an oven gas pipe and a two-section gasification nozzle; the lower concentrated phase fluidized bed furnace body, the crushed coal feeding pipe, the oven gas pipe and the two-section gasification nozzle jointly form a lower concentrated phase fluidized bed gasification section, a chilling water pipe and a gasification furnace gas outlet are arranged at the top of the cylindrical furnace body, and the chilling water pipe and the gasification furnace gas outlet form an upper particle settling separation section. A segmented conversion process is adopted, the gas-solid contact rate is increased, the retention time is prolonged, and unconverted fly ash fine powder returns to the high-temperature area of the central pipe through the central burner to be efficiently converted.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal gasification, and particularly relates to a method for gasification of a fluidized bed of coal in stages and a gasification furnace thereof. BACKGROUND

[0002] The resource endowment of "rich coal, poor oil and little gas" determines that coal will still be an important basic energy in the foreseeable future in China, and the coal gasification technology is one of the core technologies for realizing efficient and clean utilization of coal. It is reported that low-rank coal mainly in the form of lignite and long flame coal accounts for about 45% of the remaining coal recoverable reserves in China, but the "two high and three low" (high volatile matter, high moisture, low ash fusion point, low density, and low calorific value) characteristics of lignite and other low-rank coal lead to serious environmental pollution and make it difficult to be utilized on a large scale.

[0003] Fluidized bed gasifier has been widely used in the field of coal gasification due to its uniform temperature field, good particle and gas heat and mass transfer effect, wide adaptability to coal types and low cost. Many coal gasification reactions are carried out in fluidized bed gasification devices. Through retrieval, there are a large number of patents disclosed about the gasification system of fluidized bed gasifier. The Chinese patent application file with publication number CN1114976A discloses a method and device for ash melting and agglomerating fluidized bed gasification process, which adopts dense phase fluidized bed gasification technology with ash melting and agglomerating method. Based on the principle of jet flow, an ash separation device is designed at the bottom of the fluidized bed to form a local high temperature in the bed, so that the ash and slag are agglomerated into balls, and the separation of ash balls and materials is realized by means of weight difference. The Chinese patent application file with publication number CN103911179A discloses a coal gasification method and device, which sends pulverized coal and gasifying agent into a circulating fluidized bed gasifier for reaction, and the generated gasifier flue gas is separated from the returned pulverized coal and the pulverized coal gas stream by a first gas-solid separator, and the returned pulverized coal is circulated back to the circulating fluidized bed gasifier for continuous reaction, while the pulverized coal gas stream is separated into coal gas and carbon-containing fly ash by a second gas-solid separator. The carbon-containing fly ash is sent into a hot blast furnace for combustion at a temperature higher than 1300℃, and the generated hot blast furnace flue gas is returned to the circulating fluidized bed gasifier for reaction. The liquid slag generated by combustion is discharged after cooling. The Chinese patent application file with publication number CN113088336A discloses a staged gasification pure oxygen circulating fluidized bed coal gas generator and working method, which sets a plurality of nozzles in the main gasification core area, the center line of each nozzle is tangent to the center circle, and a steam injection part is arranged in the slag discharge mechanism. The Chinese patent application file with publication number CN112824502A discloses a circulating fluidized bed gasification device and method, which is developed based on circulating fluidized bed boiler technology. The Chinese patent application file with publication number CN105779008A discloses a coal powder treatment method and system. The method combines the circulating fluidized bed gasification system with the entrained flow bed gasification system, and uses the entrained flow bed gasification system to treat the fly ash generated by the circulating fluidized bed gasification system as raw material, aiming to solve the problems of low utilization rate of circulating fluidized bed coal and difficult treatment of large amount of fly ash, so as to improve the conversion efficiency of coal.

[0004] However, with the increasing demand of industrialization, the gas production requirement of a single gasifier is increasing (the maximum gas production capacity of a single industrial gasifier is currently 80000 Nm3 / h), and there is inevitably a problem of uneven gas distribution in the process of scaling up the fluidized bed, which leads to a decrease in local fluidization quality in the bed, and even a dead zone, directly affecting the progress of the gasification reaction, reducing the carbon conversion efficiency, and becoming an important limiting factor for the scaling up of the fluidized bed gasifier. In addition, the coarse coal gas discharged from the gas outlet of the fluidized bed gasifier contains a large amount of dust, and the produced coal gas contains unreacted fly ash, the carbon content of the fly ash is high, and part of the calorific value of the coal is lost. These problems have not been effectively solved.

[0005] Therefore, it is urgent to design a gasification system with high gas production and efficient utilization of carbon-containing fly ash, which not only overcomes the shortcomings of large-scale utilization of coal, but also improves the utilization efficiency of carbon-containing fly ash, improves the reaction heat efficiency of the gasification furnace, and realizes efficient conversion of energy. SUMMARY

[0006] The present application provides a method for gasification of coal in a fluidized bed in stages and a gasification furnace thereof.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: The method for gasification of coal in a fluidized bed in stages comprises the following steps: Preparation of gasification raw coal: after the raw coal is crushed, it is dried and sieved, so that the moisture content is less than 25wt%, and the particle size of the crushed coal is less than 20mm, which is sent to the dry crushed coal storage bin as the fluidized bed gasification raw coal; First-stage gasification: a. The gasification furnace is heated, and when the temperature at the lower part of the gasification furnace is greater than 900℃, air and steam are introduced into the lower part of the fluidized bed through the conical distributor, and crushed coal is continuously added from the lower part of the gasification furnace, and the operation is carried out according to the air / coal ratio of 2.5-3.5Nm³ / kg and the steam / coal ratio of 0.3-0.6kg / kg, so that the crushed coal is burned in the gasification furnace, and semi-coke furnace charge is obtained, and the material in the gasification furnace is gradually established; b. When the bed pressure drop of the semi-coke furnace charge in the gasification furnace reaches 5-10KPa, air / oxygen / pure oxygen and steam are switched on, and the temperature is controlled at 800-900℃ during the switching process; c. The gasification operation is carried out according to the oxygen / coal ratio of 0.4-0.5Nm³ / kg and the steam / coal ratio of 0.5-1.0kg / kg, and the bottom temperature of the gasification furnace is stabilized at 900-1100℃; Second-stage gasification: after the first-stage gasification operation is stable, i.e. the bed pressure drop reaches 5-10KPa and the bottom temperature of the gasification furnace is stabilized at 900-1100℃, the crushed coal feed rate is increased to 10-15KPa, and the second-stage gasification nozzle is opened to blow air / oxygen / pure oxygen and steam, and the temperature is controlled at 900-1100℃ during the opening process; Third-stage gasification: the raw coal gas generated from the gasification furnace enters the secondary cyclone separator through the primary cyclone separator, and the captured fly ash is sent to the fly ash passage on the center gasification burner through the fly ash collection / cooling tank and the fly ash conveyor, and the air / oxygen / pure oxygen and steam in the center gasification agent inlet pipe are increased during the fly ash feeding process, so as to ensure that the temperature of the lower part of the gasification furnace is controlled at 950-1100℃; The slag discharge of the gasifier: in the gasification process, the gas velocity of the conical distributor is 1-3 m / s, the oxygen concentration in the gas is 10-15 Vol%, the gas velocity of the annular separation tube is 4-6 m / s, the oxygen concentration in the gas is 0-10 Vol%, the gas velocity of the gasifier in the gasifier is 20-60 m / s, the oxygen concentration in the gas is 15-60 Vol%, the gas velocity of the secondary gasification nozzle is 80-120 m / s, and the oxygen concentration in the gas is 15-60 Vol%; by controlling the rotation speed of the slag cooler, the slag discharge is controlled, and the bed pressure drop of the semi-coke in the gasifier is kept between 10-15 KPa; The purification and waste heat recovery of the raw coal gas: the quenching water is sprayed at the gas outlet of the gasifier to ensure that the inlet temperature of the primary cyclone separator is less than 900 DEG C; the raw coal gas is separated by the primary cyclone separator, the captured semi-coke fine powder is returned to the lower dense phase fluidized bed gasification section of the gasifier through the semi-coke fine powder circulation standpipe, the semi-coke fine powder circulation control pneumatic valve and the semi-coke feeding pipe, and participates in the reaction again; the raw coal gas enters the secondary cyclone separator, the captured fly ash is sent into the fly ash channel on the center gasification burner through the fly ash collection / cooling tank and the fly ash conveyor; the high-temperature coal gas after the primary separation is sent into the venturi scrubber and the tray-type water washing tower through the waste heat boiler, the steam superheater and the deoxidizing water preheater, the temperature of the coal gas is reduced to 50-170 DEG C, and then the coal gas is output to the coal gas purification section after further temperature reduction and dust removal through the coal gas pressure regulating valve; The gasifier shutdown: when the gasifier is normally shut down, firstly, the air / oxygen-enriched / pure oxygen is stopped from being introduced into the gasifier; the center fly ash feeding pipe on the center gasification burner is closed, the addition of fly ash into the gasifier is stopped, the addition of crushed coal into the gasifier is stopped; the pipeline between the secondary cyclone separator and the waste heat boiler is cut off, the raw coal gas from the secondary cyclone separator is vented, and the pressure in the gasifier is reduced to the normal pressure; then, the rotation speed of the slag cooler is increased, the ash discharge is increased, and the amount of the fluidized bed steam is increased, the temperature in the gasifier is controlled to be below 900 DEG C, the feeding of the steam is stopped after the discharge of the furnace charge, and finally, the gasifier is purged and cleaned by using the steam and the air in sequence.

[0008] The sectional conversion gasifier comprises a pyrolysis gasification reactor, a fused aggregate separation unit and a leg fine powder circulation unit. The pyrolysis gasification reactor comprises a cylindrical furnace body, a lower dense phase fluidized bed furnace body is fixedly connected to the lower end of the cylindrical furnace body, a crushed coal feeding pipe, an oven coal gas pipe and a secondary gasification nozzle are connected to the lower dense phase fluidized bed furnace body, and the lower dense phase fluidized bed furnace body, the crushed coal feeding pipe, the oven coal gas pipe and the secondary gasification nozzle jointly form a lower dense phase fluidized bed gasification section; a quenching water pipe and a gasifier coal gas outlet are arranged at the top of the cylindrical furnace body, and the quenching water pipe and the gasifier coal gas outlet form an upper particle sedimentation separation section. The melt polymerization ash separation unit comprises a plenum shell fixedly connected with a lower end of the lower dense phase fluidized bed furnace body, a conical distributor mounted on an upper portion of the plenum shell, the conical distributor being in an inverted conical shape, gas outlets uniformly distributed on the conical distributor, an annular separation tube connected with a lower end of the conical distributor, a lower end of the annular separation tube being located outside the plenum shell, the plenum shell, the conical distributor and the annular separation tube together constituting a gas inlet chamber, a distributor gasification agent inlet pipe communicating with the gas inlet chamber being arranged on the plenum shell, an annular separation tube ash discharge port being arranged on a lower portion of the annular separation tube, an annular separation tube gasification agent inlet port being arranged on a lower end of the annular separation tube, a central gasification burner being arranged in the annular separation tube, the central gasification burner coinciding with a central axis of the annular separation tube, and the annular separation tube and the central gasification burner both being in a same height level with a bottom of the conical distributor, the central gasification burner sequentially comprising a protective water jacket, a fly ash passage and a gasification agent passage from outside to inside, a protective water jacket inlet port, a protective water jacket outlet port, a central fly ash inlet pipe and a central gasification agent inlet pipe being arranged on the central gasification burner, the protective water jacket inlet port and the protective water jacket outlet port communicating with the protective water jacket, the central fly ash inlet pipe communicating with the fly ash passage, and the central gasification agent inlet pipe communicating with the gasification agent passage. The material leg fine powder circulation unit comprises a primary cyclone separator, an inlet of the primary cyclone separator being connected with a gas outlet of the gasification furnace, a semi-coke fine powder circulation vertical pipe being connected with a lower portion of the primary cyclone separator, a lower end of the semi-coke fine powder circulation vertical pipe being connected with a lower portion of a semi-coke fine powder circulation control pneumatic valve through an inclined pipe, a lower end of the semi-coke fine powder circulation control pneumatic valve being connected with a pneumatic valve steam blowing pipe, a fine powder return steam blowing pipe being connected with an upper portion of the inclined pipe, and a semi-coke fine powder inlet pipe being connected with an upper portion of the semi-coke fine powder circulation control pneumatic valve, the semi-coke fine powder inlet pipe being connected with the lower dense phase fluidized bed furnace body.

[0009] Further, a heat insulation material layer is arranged on inner walls of the cylindrical furnace body, the lower dense phase fluidized bed furnace body, the plenum shell, the conical distributor, the annular separation tube and the separation tube ash discharge port, and a refractory lining is arranged on an inner side of the heat insulation material layer.

[0010] Still further, the lower dense phase fluidized bed furnace body is in an inverted conical shape, and an included angle Ω between a conical generatrix and a central axis is 10-30°.

[0011] Still further, an outer diameter of the fly ash passage is 1 / 3-2 / 3 of an inner diameter of a lower end of the conical distributor, and a diameter of the gasification agent passage is 1 / 4-1 / 2 of the inner diameter of the lower end of the conical distributor.

[0012] Still further, an open area ratio of the conical distributor is 0.5%-2%, a hole diameter is 3-8 mm, and an included angle α between a conical generatrix and a central axis is 30-50°.

[0013] Further, the angle β between the conical generatrix of the upper throat of the annular separation tube and the central axis is 5-12°, and the angle θ between the conical generatrix of the lower throat of the annular separation tube and the central axis is 15-20°.

[0014] Further, the two-stage gasification nozzle is located at the lower part of the lower dense phase fluidized bed furnace body and is located below the crushed coal feeding pipe and above the distributor, the two-stage gasification nozzle is inclined upward, the angle ε between the two-stage gasification nozzle and the horizontal line is 10-20°, the extension line of the center line is tangent to the center circle, the center of the center circle is located on the axis of the gasification furnace, a tangent line is drawn at the intersection point of the center line of the two-stage gasification nozzle and the outer side wall of the lower dense phase fluidized bed furnace body, and the angle ʎ between the tangent line and the center line of the two-stage gasification nozzle is 45-75°.

[0015] Compared with the prior art, the present application has the following advantages: The operating pressure of the gasification furnace can reach 3.0 MPa, the processing capacity is large, and the compression energy consumption is low. The present application adopts selective ash separation, dry slagging, and low carbon content of ash, and the coal gas entrained fine powder increases the residence time through high circulation ratio to improve the total gasification carbon conversion rate. The present application adopts a staged conversion process, improves the gas-solid contact rate, increases the residence time, and the unconverted fly ash fine powder returns to the high-temperature area of the center pipe through the center burner for efficient conversion; the crushed coal can be directly used, the power consumption of coal grinding is reduced, the total energy consumption of the system is low, and the oxygen consumption is low. The present application adopts staged gasification, the volume utilization rate of the gasification furnace is high, the carbon conversion rate is high, and the risk of slagging is small. The gasification furnace in the present application has simple structure, no special refractory material, low cost, simple operation, and long service life. The present application has a wide range of available coal types, and most of the coal in China can be gasified. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 FIG. 1 is a structural schematic diagram of the gasification furnace of the present application; Figure 2 FIG. 2 is a structural schematic diagram of the melt-agglomerated ash separation unit of the present application; Figure 3 FIG. 3 is a structural schematic diagram of the two-stage gasification nozzle of the present application; Figure 2 FIG. 4 is a partial enlarged view of circle A in FIG. 3; Figure 4 FIG. 5 is a tangential schematic diagram of the two-stage gasification nozzle and the center circle of the present application; Figure 5 FIG. 6 is a flow chart of the coal gasification process of the present application; In the diagram, 1 is a cylindrical furnace body, 2 is a lower dense-phase fluidized bed furnace body, 3 is a crushed coal feed pipe, 4 is a furnace gas pipe, 5 is a secondary gasification nozzle, 6 is a quench water pipe, 7 is a gasifier gas outlet, 8 is a gas chamber shell, 9 is a conical distributor, 10 is an annular separator, 11 is a distributor gasifying agent inlet pipe, 12 is a separator ash discharge port, 13 is a separator gasifying agent inlet, 14 is a central gasification burner, 15 is a protective water jacket, 16 is a fly ash channel, 17 is a gasifying agent channel, 18 is a protective water jacket inlet, 19 is a protective water jacket outlet, 20 is a central fly ash feed pipe, 21 is a central gasifying agent inlet pipe, 22 is a primary cyclone separator, 23 is a semi-coke fine powder circulation riser, 24 is an inclined pipe, 25 is a semi-coke fine powder circulation control pneumatic valve, 26 is a pneumatic valve steam blower, and 27 is a fine powder return steam blower. 28 Semi-coke fine powder feed pipe, 29 Coal conveyor belt, 30 Vibrating screen, 31 Raw coal crusher, 32 Dryer, 33 No. 1 hoist, 34 Dry crushed coal storage silo, 35 Dry crushed coal conveyor, 36 No. 2 hoist, 37 Crushed coal feed hopper, 38 Rotary feeder, 39 Gasifier, 40 Slag cooler, 41 Ash discharge hopper, 42 Fly ash conveyor, 43 Fly ash collection / cooling tank, 44 Air separator, 45 Air preheater, 46 Superheated steam separator, 47 Coal gas separator, 48 Secondary cyclone separator, 49 Waste heat boiler, 50 Steam superheater, 51 Deoxygenated water preheater, 52 Venturi scrubber, 53 Tray-type water washing tower, 54 Gas-water separator, 55 Coal desulfurization tower, 56 Coal gas pressure regulating valve, 57 Flash evaporator. Detailed Implementation

[0017] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments. Example 1

[0018] like Figures 1 to 5 As shown, the method for staged conversion fluidized bed coal gasification includes the following steps: Preparation of raw coal for gasification: Raw coal is fed into vibrating screen 30 via coal conveyor belt 29. Raw coal with a particle size greater than 20mm is crushed into crushed coal with a particle size less than 20mm by raw coal crusher 31. The crushed coal and the raw coal under the screen of vibrating screen 30 are then fed into dryer 32 for drying to make the moisture content <25wt%. The crushed coal with a particle size less than 20mm is fed into dry crushed coal storage silo 34 via No. 1 elevator 33 as raw coal for fluidized bed gasification. First stage gasification: a. The gasifier 39 is heated by air from the air cylinder 44 and coal gas from the coal gas cylinder 47. The air enters the gasifier 39 through the distributor gas inlet pipe 11, the separation pipe gas inlet 13 and the central gas inlet pipe 21, and the coal gas enters the gasifier 39 through the heating coal gas pipe 4. When the temperature at the lower part of the gasifier 39 is greater than 900℃, air 1000 Nm3 / h and steam 100 kg / h from the superheated steam cylinder 46 are introduced through the distributor gas inlet pipe 11, the separation pipe gas inlet 13 and the central gas inlet pipe 21. The rotary feeder 38 is opened to continuously add the gasified crushed coal from the crushed coal feeding pipe 3 of the gasifier 39, and the operation is carried out according to the air / coal ratio of 2.5-3.5 Nm3 / kg and the steam / coal ratio of 0.3-0.6 kg / kg. The crushed coal is combusted in the gasifier 39 to obtain semi-coke furnace material, and the material in the gasifier 39 is gradually established; b. When the bed pressure drop of the semi-coke furnace material in the gasifier 39 reaches 5-10 KPa, the air / oxygen / pure oxygen and steam blowing are switched. The temperature is controlled at 800-900℃ during the switching process; c. The gasification operation is carried out according to the oxygen / coal ratio of 0.4-0.5 Nm3 / kg and the steam / coal ratio of 0.5-1.0 kg / kg. The bottom temperature of the gasifier 39 is stabilized at 900-1100℃; Second stage gasification: After the first stage gasification operation is stabilized, i.e. the bed pressure drop reaches 5-10 KPa and the bottom temperature of the gasifier 39 is stabilized at 900-1100℃, the crushed coal feeding amount is increased to make the bed pressure drop of the material in the gasifier 39 reach 10-15 KPa. The air / oxygen / pure oxygen and steam blowing are started by opening the second stage gasification nozzle 5. The temperature is controlled at 900-1100℃ during the opening process; Third stage gasification: The raw coal gas generated from the gasifier 39 enters the second stage cyclone separator 48 through the first stage cyclone separator 22. The captured fly ash is sent to the fly ash passage 16 on the central gas burner 14 through the fly ash collection / cooling tank 43 and the fly ash conveyor 42. The air / oxygen / pure oxygen and steam in the central gas inlet pipe 21 are increased during the fly ash feeding process to ensure that the temperature at the lower part of the gasifier 39 is controlled at 950-1100℃; Gasifier slag discharge: During the gasification process, the gas velocity of the conical distributor 9 is 1-3 m / s, the oxygen concentration in the gas is 10-15 Vol%, the gas velocity of the annular separation pipe 10 is 4-6 m / s, the oxygen concentration in the gas is 0-10 Vol%, the gas velocity of the gasification agent passage 17 in the central gas burner 14 is 20-60 m / s, the oxygen concentration in the gas is 15-60 vol%, the gas velocity of the second stage gasification nozzle 5 is 80-120 m / s, and the oxygen concentration in the gas is 15-60 Vol%. The rotation speed of the slag cooler 40 is controlled to control the slag discharge amount, so that the bed pressure drop of the semi-coke furnace material in the gasifier 39 is maintained at 10-15 KPa; Purification and waste heat recovery of crude gas: Quenching water is injected into the gas outlet 7 of the gasifier to ensure the inlet temperature of the primary cyclone separator 22 is <900℃. The crude gas is separated by the primary cyclone separator 22, and the collected semi-coke fine powder is returned to the lower dense-phase fluidized bed gasification section of the gasifier 39 via the semi-coke fine powder circulation riser 23, the semi-coke fine powder circulation control pneumatic valve 25, and the semi-coke fine powder feed pipe 28 to participate in the reaction again. The crude gas enters the secondary cyclone separator 48, where the collected... Fly ash is sent to the fly ash channel 16 on the central gasification burner 14 via fly ash collection / cooling tank 43 and fly ash conveyor 42; the high-temperature coal gas from coarse separation passes through waste heat boiler 49, steam superheater 50, and deoxygenated water preheater 51, and the coal gas temperature is reduced to 50-170℃ before entering Venturi scrubber 52 and tray-type water washing tower 53, gas-water separator 54 and coarse desulfurization tower 55, and after further cooling and dust removal, it is output to the coal gas purification section via coal gas pressure regulating valve 56. Gasifier shutdown: During normal shutdown, first stop the supply of air / oxygen-enriched / pure oxygen into the gasifier 39; close the central fly ash feed pipe 20 on the central gasification burner 14, stop adding fly ash into the gasifier 39, and stop adding crushed coal into the gasifier 39; disconnect the pipeline between the secondary cyclone separator 48 and the waste heat boiler 49, and vent the crude coal gas from the secondary cyclone separator 48 to reduce the pressure inside the gasifier 39 to atmospheric pressure; then, increase the speed of the slag cooler 40, increase the ash discharge, and simultaneously increase the fluidized bed steam consumption, keeping the furnace temperature below 900℃. After the furnace charge is discharged, stop the steam supply, and finally, purge and clean the gasifier 39 with steam and air in succession.

[0019] The segmented conversion gasifier includes a pyrolysis gasification reactor, a molten aggregate ash separation unit, and a feed leg fine powder circulation unit. The pyrolysis gasification reactor includes a cylindrical furnace body 1. A lower dense-phase fluidized bed furnace body 2 is fixedly connected to the lower end of the cylindrical furnace body 1. The lower dense-phase fluidized bed furnace body 2 is inverted conical in shape, with an angle Ω between its generatrix and central axis of 10–30°. A pulverized coal feed pipe 3, a furnace gas pipe 4, and a secondary gasification nozzle 5 are connected to the lower dense-phase fluidized bed furnace body 2. The lower dense-phase fluidized bed furnace body 2, pulverized coal feed pipe 3, furnace gas pipe 4, and secondary gasification nozzle 5 together constitute the lower dense-phase fluidized bed gasification section. The secondary gasification nozzle 5 is located at the lower part of the lower dense-phase fluidized bed furnace body 2 and is located at the lower end of the pulverized coal feed pipe 3. Between the lower part and the upper edge of the distributor, the two-stage gasification nozzle 5 is inclined upwards, and the angle ε between the two-stage gasification nozzle 5 and the horizontal line is 10-20°. The extension of its center line is tangent to the central circle. The center of the central circle is located on the axis of the gasifier. A tangent line is drawn at the intersection of the center line of the two-stage gasification nozzle 5 and the outer wall of the lower dense phase fluidized bed furnace body 2. The angle ʎ between the tangent line and the center line of the two-stage gasification nozzle 5 is 45-75°. A quench water pipe 6 and a gasifier gas outlet 7 are provided at the top of the cylindrical furnace body 1. The quench water pipe 6 and the gasifier gas outlet 7 constitute the upper particle settling and separation section. The fused agglomerate ash separation unit includes a gas chamber shell 8, which is fixedly connected to the lower end of the lower dense phase fluidized bed furnace body 2. A conical distributor 9 is installed on the upper part of the gas chamber shell 8. The conical distributor 9 is inverted conical in shape and has gas outlets evenly distributed on it. The opening ratio of the conical distributor 9 is 0.5% to 2%, the aperture is 3 to 8 mm, and the angle α between its conical generatrix and the central axis is 30 to 50°. An annular separation pipe 10 is connected to the lower end of the conical distributor 9, and the lower end of the annular separation pipe 10 is located outside the gas chamber shell 8. The gas chamber shell 8, the conical distributor 9, and the annular separator 10 together constitute the air inlet chamber. The angle β between the generatrix of the cone at the upper throat of the annular separator 10 and the central axis is 5–12°, and the angle θ between the generatrix of the cone at the lower throat of the annular separator 10 and the central axis is 15–20°. A distributor gasifying agent inlet pipe 11 communicating with the air inlet chamber is provided on the gas chamber shell 8. A separator ash discharge port 12 is provided at the lower part of the annular separator 10, and a separator gasifying agent inlet 13 is provided at the lower end of the annular separator 10. A gasifying agent inlet 13 is provided inside the annular separator 10. A central gasification burner 14 is provided, with its central axis coinciding with that of the annular separation pipe 10. The outlets of both the annular separation pipe 10 and the central gasification burner 14 are at the same height as the bottom of the conical distributor 9. The central gasification burner 14 is provided with a protective water jacket 15, a fly ash channel 16, and a gasifying agent channel 17 arranged sequentially from the outside to the inside. A protective water jacket inlet 18, a protective water jacket outlet 19, a central fly ash feed pipe 20, and a central gasifying agent inlet pipe 21 are also provided on the central gasification burner 14. The protective water jacket inlet 18 and the protective water jacket outlet 19 are connected to the protective water... The jacket 15 is connected, the central fly ash feed pipe 20 is connected to the fly ash channel 16, and the central gasifying agent inlet pipe 21 is connected to the gasifying agent channel 17. The outer diameter of the fly ash channel 16 is 1 / 3 to 2 / 3 of the inner diameter of the lower end of the conical distributor 9, and the diameter of the gasifying agent channel 17 is 1 / 4 to 1 / 2 of the inner diameter of the lower end of the conical distributor 9. Thermal insulation material layers are provided on the inner walls of the cylindrical furnace body 1, the lower dense phase fluidized bed furnace body 2, the gas chamber shell 8, the conical distributor 9, the annular separation pipe 10, and the ash discharge port 12 of the separation pipe. A refractory lining is provided on the inner side of the thermal insulation material layer.

[0020] The feed fine powder circulation unit includes a primary cyclone separator 22. The inlet of the primary cyclone separator 22 is connected to the gas outlet 7 of the gasifier. The lower part of the primary cyclone separator 22 is connected to a semi-coke fine powder circulation riser 23. The lower end of the semi-coke fine powder circulation riser 23 is connected to the lower part of the semi-coke fine powder circulation control pneumatic valve 25 through an inclined pipe 24. The lower end of the semi-coke fine powder circulation control pneumatic valve 25 is connected to a pneumatic valve steam blowing pipe 26. The upper part of the inclined pipe 24 is connected to a fine powder return steam blowing pipe 27. The upper part of the semi-coke fine powder circulation control pneumatic valve 25 is connected to a semi-coke fine powder feed pipe 28. The semi-coke fine powder feed pipe 28 is connected to the lower dense phase fluidized bed furnace body 2. Example 2

[0021] In the first stage of gasification, the air-to-coal ratio in step a is 3.5 Nm³ / kg, and the steam-to-coal ratio is 0.6 kg / kg. In step c, the oxygen-to-coal ratio is 0.4 Nm³ / kg, and the steam-to-coal ratio is 0.5 kg / kg.

[0022] In the slag discharge step of the gasifier, the gas velocity in the conical distributor 9 is 3 m / s, and the oxygen concentration in the gas is 10 vol; the gas velocity in the annular separator 10 is 6 m / s, and the oxygen concentration in the gas is 0 vol; the gas velocity in the gasifying agent channel 17 of the central gasifying burner 14 is 60 m / s, and the oxygen concentration in the gas is 15 vol%. The gas velocity in the second-stage gasifying nozzle 5 is 120 m / s, and the oxygen concentration in the gas is 15 vol.

[0023] The cone distributor 9 in the segmented conversion gasifier has an opening ratio of 0.5%, an aperture of 8 mm, and an included angle α of 30°.

[0024] The angle β between the conical generatrix of the upper throat of the annular separation tube 10 and the central axis is 12°, and the angle θ between the conical generatrix of the lower throat of the annular separation tube 10 and the central axis is 15°.

[0025] The angle Ω between the generatrix of the lower dense phase fluidized bed furnace body 2 and the central axis is 30°, and the angle ε between the second-stage gasification nozzle 5 and the horizontal line is 10°.

[0026] A tangent is drawn at the intersection of the centerline of the second-stage gasification nozzle 5 and the outer wall of the lower dense fluidized bed furnace body 2. The angle ʎ between the tangent and the centerline of the second-stage gasification nozzle 5 is 45°. Example 3

[0027] In the first stage of gasification, the air-to-coal ratio in step a is 2.5 Nm³ / kg, and the steam-to-coal ratio is 0.3 kg / kg. In step c, the oxygen-to-coal ratio is 0.5 Nm³ / kg, and the steam-to-coal ratio is 1.0 kg / kg.

[0028] In the slag discharge step of the gasifier, the gas velocity in the conical distributor 9 is 1 m / s, and the oxygen concentration in the gas is 15 vol; the gas velocity in the annular separator 10 is 4 m / s, and the oxygen concentration in the gas is 10 vol; the gas velocity in the gasifying agent channel 17 of the central gasifying burner 14 is 20 m / s, and the oxygen concentration in the gas is 60 vol; the gas velocity in the second-stage gasifying nozzle 5 is 80 m / s, and the oxygen concentration in the gas is 60 vol.

[0029] The cone distributor 9 in the segmented conversion gasifier has an opening ratio of 2%, an aperture of 3 mm, and an included angle α of 50°.

[0030] The angle β between the conical generatrix of the upper throat of the annular separation tube 10 and the central axis is 5°, and the angle θ between the conical generatrix of the lower throat of the annular separation tube 10 and the central axis is 20°.

[0031] The angle Ω between the generatrix of the lower dense phase fluidized bed furnace body 2 and the central axis is 10°, and the angle ε between the second-stage gasification nozzle 5 and the horizontal line is 20°.

[0032] A tangent is drawn at the intersection of the centerline of the second-stage gasification nozzle 5 and the outer wall of the lower dense fluidized bed furnace body 2. The angle ʎ between the tangent and the centerline of the second-stage gasification nozzle 5 is 60°. Example 4

[0033] In the first stage of gasification, the air-to-coal ratio in step a is 0.4 Nm³ / kg, and the steam-to-coal ratio is 0.5 kg / kg. In step c, the oxygen-to-coal ratio is 0.45 Nm³ / kg, and the steam-to-coal ratio is 0.7 kg / kg.

[0034] In the slag discharge step of the gasifier, the gas velocity in the conical distributor 9 is 2 m / s, and the oxygen concentration in the gas is 13 vol; the gas velocity in the annular separator 10 is 5 m / s, and the oxygen concentration in the gas is 6 vol; the gas velocity in the gasifying agent channel 17 of the central gasifying burner 14 is 40 m / s, and the oxygen concentration in the gas is 50 vol; the gas velocity in the second-stage gasifying nozzle 5 is 100 m / s, and the oxygen concentration in the gas is 40 vol.

[0035] The cone distributor 9 in the segmented conversion gasifier has an opening ratio of 1%, an aperture of 4 mm, and an included angle α of 40°.

[0036] The angle β between the conical generatrix of the upper throat of the annular separation tube 10 and the central axis is 8°, and the angle θ between the conical generatrix of the lower throat of the annular separation tube 10 and the central axis is 18°.

[0037] The angle Ω between the generatrix of the lower dense phase fluidized bed furnace body 2 and the central axis is 20°, and the angle ε between the second-stage gasification nozzle 5 and the horizontal line is 15°.

[0038] A tangent is drawn at the intersection of the centerline of the second-stage gasification nozzle 5 and the outer wall of the lower dense fluidized bed furnace body 2. The angle ʎ between the tangent and the centerline of the second-stage gasification nozzle 5 is 50°. Example 5

[0039] In the first stage of gasification, the air-to-coal ratio in step a is 0.5 Nm³ / kg, and the steam-to-coal ratio is 1.0 kg / kg. In step c, the oxygen-to-coal ratio is 0.4 Nm³ / kg, and the steam-to-coal ratio is 0.6 kg / kg.

[0040] In the slag discharge step of the gasifier, the gas velocity in the conical distributor 9 is 3 m / s, and the oxygen concentration in the gas is 13 vol; the gas velocity in the annular separator 10 is 5 m / s, and the oxygen concentration in the gas is 5 vol; the gas velocity in the gasifying agent channel 17 of the central gasifying burner 14 is 50 m / s, and the oxygen concentration in the gas is 50 vol; the gas velocity in the second-stage gasifying nozzle 5 is 90 m / s, and the oxygen concentration in the gas is 55 vol.

[0041] The cone distributor 9 in the segmented conversion gasifier has an opening ratio of 1.5%, an aperture of 6 mm, and an included angle α of 45°.

[0042] The angle β between the conical generatrix of the upper throat of the annular separation tube 10 and the central axis is 10°, and the angle θ between the conical generatrix of the lower throat of the annular separation tube 10 and the central axis is 20°.

[0043] The angle Ω between the generatrix of the lower dense phase fluidized bed furnace body 2 and the central axis is 15°, and the angle ε between the second-stage gasification nozzle 5 and the horizontal line is 15°.

[0044] A tangent is drawn at the intersection of the centerline of the second-stage gasification nozzle 5 and the outer wall of the lower dense fluidized bed furnace body 2. The angle ʎ between the tangent and the centerline of the second-stage gasification nozzle 5 is 75°.

[0045] The raw coal parameters under the conditions of Examples 2-5 are listed in Table 1.

[0046] Table 1 shows the parameters for different types of raw coal.

[0047] The synthesis gas produced by the segmented conversion fluidized bed coal gasification under the conditions of Examples 2-5 is listed in Table 2.

[0048] Table 2 shows the composition of syngas produced by staged conversion fluidized bed coal gasification under different conditions.

[0049] The foregoing has shown and described the main features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0050] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for staged conversion fluidized bed coal gasification, characterized in that: Includes the following steps: Preparation of raw coal for gasification: After crushing, the raw coal is dried and screened to ensure that the moisture content is <25wt% and the particle size is less than 20mm. The crushed coal is sent to the dry crushed coal storage silo (34) as raw coal for fluidized bed gasification. First stage of gasification: a. The gasifier (39) is baked until the temperature at the bottom of the gasifier (39) is greater than 900℃. Air and steam are introduced into the conical distributor (9) at the bottom of the fluidized bed. Crushed coal is continuously added from the bottom of the gasifier (39) and operated at an air-to-coal ratio of 2.5-3.5 Nm³ / kg and a steam-to-coal ratio of 0.3-0.6 kg / kg. The crushed coal is burned in the gasifier (39) to obtain semi-coke oven feed and gradually establish the gasification process. a. Material inside the gasifier (39); b. When the bed pressure drop of the semi-coke oven material in the gasifier (39) reaches 5-10KPa, switch to air / oxygen-enriched / pure oxygen and steam blast, and control the temperature at 800-900℃ during the switching process; c. Perform gasification operation at an oxygen-to-coal ratio of 0.4-0.5Nm³ / kg and a steam-to-coal ratio of 0.5-1.0kg / kg, and stabilize the bottom temperature of the gasifier (39) at 900-1100℃. Second-stage gasification: After the first-stage gasification operation is stable, i.e. the bed pressure drop reaches 5-10KPa and the bottom temperature of the gasifier (39) is stable at 900-1100℃, the amount of crushed coal is increased until the bed pressure drop of the furnace material in the gasifier (39) reaches 10-15KPa. The second-stage gasification nozzle (5) is opened to blow air / oxygen-enriched / pure oxygen and steam. During the opening process, the temperature is controlled at 900-1100℃. Three-stage gasification: The crude coal gas generated from the gasifier (39) enters the secondary cyclone separator (48) through the primary cyclone separator (22). The collected fly ash is sent to the fly ash channel (16) on the central gasification burner (14) through the fly ash collection / cooling tank (43) and fly ash conveyor (42). During the fly ash feeding process, the air / oxygen-enriched / pure oxygen and steam intake in the central gasification agent intake pipe (21) are increased to ensure that the temperature at the bottom of the gasifier (39) is controlled at 950~1100℃. Slag discharge from the gasifier: During the gasification process, the gas velocity of the conical distributor (9) is 1-3 m / s, and the oxygen concentration in the gas is 10-15 Vol%; the gas velocity of the annular separator (10) is 4-6 m / s, and the oxygen concentration in the gas is 0-10 Vol%; the gas velocity of the gasifying agent channel (17) in the central gasification burner (14) is 20-60 m / s, and the oxygen concentration in the gas is 15-60 vol%; the gas velocity of the second-stage gasification nozzle (5) is 80-120 m / s, and the oxygen concentration in the gas is 15-60 Vol%; by controlling the rotation speed of the slag cooler (40), the slag discharge is controlled, so that the bed pressure drop of the semi-coke oven material in the gasifier (39) is maintained between 10-15 KPa; Purification and waste heat recovery of crude gas: Cooling water is injected into the gas outlet (7) of the gasifier to ensure that the inlet temperature of the first-stage cyclone separator (22) is <900℃. The crude gas is separated by the first-stage cyclone separator (22), and the collected semi-coke fine powder is returned to the lower dense phase fluidized bed gasification section of the gasifier (39) to participate in the reaction again through the semi-coke fine powder circulation riser (23), the semi-coke fine powder circulation control pneumatic valve (25) and the semi-coke fine powder feed pipe (28). The crude gas enters the second-stage cyclone separator (48), and the collected fly ash is discharged through the fly ash flowr. The ash collection / cooling tank (43) and fly ash conveyor (42) are fed into the fly ash channel (16) on the central gasification burner (14); the high-temperature coal gas from the coarse separation passes through the waste heat boiler (49), steam superheater (50), and deoxygenated water preheater (51), and the coal gas temperature drops to 50-170℃ before entering the Venturi scrubber (52) and the tray-type water washing tower (53), the gas-water separator (54) and the coarse desulfurization tower (55), and after further cooling and dust removal, it is output to the coal gas purification section through the coal gas pressure regulating valve (56); Gasifier shutdown: During normal shutdown, first stop the supply of air / oxygen-enriched / pure oxygen into the gasifier (39); close the central fly ash feed pipe (20) on the central gasification burner (14), stop adding fly ash into the gasifier (39), and stop adding crushed coal into the gasifier (39); cut off the pipeline between the secondary cyclone separator (48) and the waste heat boiler (49), and release the crude coal gas from the secondary cyclone separator (48) to reduce the pressure in the gasifier (39) to atmospheric pressure; then, increase the speed of the slag cooler (40), increase the amount of ash discharged, and at the same time increase the amount of fluidized bed steam. Control the temperature inside the furnace to below 900℃. After the furnace charge is discharged, stop the steam supply. Finally, use steam and air to purge and clean the gasifier (39) in turn.

2. A staged reformer gasifier, applied to a staged reformer fluidized bed coal gasification method, characterized in that: It includes a pyrolysis gasification reactor, a melt-polymerized ash separation unit, and a feed leg fine powder recycling unit; The pyrolysis gasification reactor includes a cylindrical furnace body (1), and a lower dense fluidized bed furnace body (2) is fixedly connected to the lower end of the cylindrical furnace body (1). A crushed coal feed pipe (3), a furnace gas pipe (4), and a second-stage gasification nozzle (5) are connected to the lower dense fluidized bed furnace body (2). The lower dense fluidized bed furnace body (2), the crushed coal feed pipe (3), the furnace gas pipe (4), and the second-stage gasification nozzle (5) together constitute the lower dense fluidized bed gasification section. A quench water pipe (6) and a gasifier gas outlet (7) are provided at the top of the cylindrical furnace body (1). The quench water pipe (6) and the gasifier gas outlet (7) constitute the upper particle settling and separation section. The fused agglomerate ash separation unit includes a gas chamber shell (8), which is fixedly connected to the lower end of the lower dense phase fluidized bed furnace body (2). A conical distributor (9) is installed on the upper part of the gas chamber shell (8). The conical distributor (9) is inverted cone shape, and gas outlets are evenly distributed on the conical distributor (9). An annular separation pipe (10) is connected to the lower end of the conical distributor (9). The lower end of the annular separation pipe (10) is located outside the gas chamber shell (8). The gas chamber shell (8), the conical distributor (9), and the annular separation pipe (10) together constitute the inlet chamber. A distributor gasifying agent inlet pipe (11) communicating with the inlet chamber is provided on the gas chamber shell (8). A separation pipe ash discharge port (12) is provided at the lower part of the annular separation pipe (10). A separation pipe gasifying agent inlet port (13) is provided at the lower end of the annular separation pipe (10). A central gasification burner (14) is installed inside the annular separation tube (10). The central gasification burner (14) coincides with the central axis of the annular separation tube (10), and the outlets of the annular separation tube (10) and the central gasification burner (14) are at the same height as the bottom of the conical distributor (9). The central gasification burner (14) is provided with a protective water jacket (15), a fly ash channel (16), and a gasifying agent channel (17) from the outside to the inside. The gasification burner (14) is provided with a protective water jacket inlet (18), a protective water jacket outlet (19), a central fly ash feed pipe (20), and a central gasifying agent inlet pipe (21). The protective water jacket inlet (18) and the protective water jacket outlet (19) are connected to the protective water jacket (15). The central fly ash feed pipe (20) is connected to the fly ash channel (16). The central gasifying agent inlet pipe (21) is connected to the gasifying agent channel (17). The material leg fine powder circulation unit includes a primary cyclone separator (22). The inlet of the primary cyclone separator (22) is connected to the gas outlet (7) of the gasifier. The lower part of the primary cyclone separator (22) is connected to a semi-coke fine powder circulation riser (23). The lower end of the semi-coke fine powder circulation riser (23) is connected to the lower part of the semi-coke fine powder circulation control pneumatic valve (25) through an inclined pipe (24). The lower end of the semi-coke fine powder circulation control pneumatic valve (25) is connected to a pneumatic valve steam blow pipe (26). The upper part of the inclined pipe (24) is connected to a fine powder return steam blow pipe (27). The upper part of the semi-coke fine powder circulation control pneumatic valve (25) is connected to a semi-coke fine powder feed pipe (28). The semi-coke fine powder feed pipe (28) is connected to the lower dense phase fluidized bed furnace body (2).

3. The segmented conversion gasifier according to claim 2, characterized in that: A thermal insulation material layer is provided on the inner walls of the cylindrical furnace body (1), the lower dense phase fluidized bed furnace body (2), the gas chamber shell (8), the conical distributor (9), the annular separation pipe (10), and the ash discharge port (12) of the separation pipe, and a refractory lining is provided on the inner side of the thermal insulation material layer.

4. The segmented conversion gasifier according to claim 2, characterized in that: The lower dense fluidized bed furnace body (2) is inverted cone shape, and the angle Ω between its cone generatrix and the central axis is 10 to 30°.

5. The segmented conversion gasifier according to claim 2, characterized in that: The outer diameter of the fly ash channel (16) is 1 / 3 to 2 / 3 of the inner diameter of the lower end of the conical distributor (9), and the diameter of the gasifying agent channel (17) is 1 / 4 to 1 / 2 of the inner diameter of the lower end of the conical distributor (9).

6. The segmented conversion gasifier according to claim 2, characterized in that: The cone distributor (9) has an opening ratio of 0.5% to 2%, an aperture of 3 to 8 mm, and an angle α between its cone generatrix and the central axis of 30 to 50°.

7. The segmented conversion gasifier according to claim 2, characterized in that: The angle β between the conical generatrix of the upper throat of the annular separation tube (10) and the central axis is 5 to 12°, and the angle θ between the conical generatrix of the lower throat of the annular separation tube (10) and the central axis is 15 to 20°.

8. The segmented conversion gasifier according to claim 2, characterized in that: The second-stage gasification nozzle (5) is located at the lower part of the lower dense phase fluidized bed furnace body (2), and between the lower part of the crushed coal feed pipe (3) and the upper part of the distributor. The second-stage gasification nozzle (5) is inclined upwards, and the angle ε between the second-stage gasification nozzle (5) and the horizontal line is 10-20°. The extension of its center line is tangent to the center circle. The center of the center circle is located on the axis of the gasifier. A tangent line is drawn at the intersection of the center line of the second-stage gasification nozzle (5) and the outer wall of the lower dense phase fluidized bed furnace body (2). The angle ʎ between the tangent line and the center line of the second-stage gasification nozzle (5) is 45-75°.

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