Solid biomass pressurized gasification process

Abstract

The invention relates to a solid biomass pressurized gasification process. The process comprises the following steps: adding solid biomass into a reactor; gas and fluidizing gas required by biomass gasification reaction are controlled by the gas inlet unit and then enter the reactor; high-temperature ash slag from the reactor is cooled through the slag discharging unit and then is conveyed to the normal-pressure equipment; in the waste heat recovery unit, the synthesis gas is subjected to heat exchange in three stages; the synthesis gas from the waste heat recovery unit enters the dust removal unit for gas and particle separation, and the synthesis gas subjected to particle separation enters the water washing cooling unit; particles separated and captured by the dust removal unit are sent back to the reactor through the fly ash furnace returning unit; and the synthesis gas from the dust removal unit is cooled in the water washing cooling unit and then is sent to a downstream device. According to the solid biomass pressurized gasification process provided by the invention, the temperature of the reactor upper section is higher than that of the reactor lower section, and the tar generated in the reactor lower section is further converted in the reactor upper section, so that the tar content in the synthesis gas at the outlet of the reactor is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of biomass pressurized gasification, and in particular to a solid biomass pressurized gasification process. Background Art

[0002] As society's demand for energy grows, fossil fuels, which are the main energy source, are decreasing, and they also bring serious environmental problems. Therefore, seeking renewable alternative energy has become the development direction of future energy. Biomass energy is an ideal renewable energy source and the fourth largest energy source in the world. The use of biomass energy has two major advantages: first, as a renewable energy source, biomass energy can help humans get rid of their dependence on fossil energy; second, it is conducive to improving the environment. The amount of CO2 emitted during the use of biomass is equal to the amount of CO2 absorbed during its formation, so biomass replacing fossil energy helps to reduce the greenhouse effect.

[0003] Among the many biomass utilization technologies, biomass gasification is the most promising technology that is easy to use on a large scale. Biomass gasification can generate medium and low calorific value fuel gas, which can be used for industrial fuel, chemical synthesis or power generation, and its efficiency is higher than other technologies. At present, the fixed bed gasification technology has simple equipment manufacturing and simple operation, but the scale is small, and the gasification process produces difficult-to-handle tar, which limits its development and application. Fluidized bed gasification technology is one of the technologies that is easy to apply to large-scale biomass gasification due to its wide adaptability to raw materials, good gas-solid heat and mass transfer performance, and uniform mixing. The temperature of biomass fluidized bed gasification is relatively low, and the production of tar is a problem that currently exists in this process. Summary of the invention

[0004] The present invention aims at solving the above problems and adopts a technical solution: a solid biomass pressurized gasification process, wherein the process steps implemented by a solid biomass pressurized gasification system are as follows:

[0005] The solid biomass is sent to a feed unit and added to a reactor;

[0006] The gas and fluidizing gas required for the biomass gasification reaction enter the reactor after being controlled by the air intake unit;

[0007] Solid biomass and fly ash are converted into synthesis gas and ash in the reactor. The synthesis gas leaves the upper part of the reactor and enters the separator.

[0008] The high-temperature ash from the reactor is cooled by the slag discharge unit and then sent to the atmospheric pressure equipment;

[0009] In the waste heat recovery unit, the syngas undergoes three stages of heat exchange;

[0010] The synthesis gas from the waste heat recovery unit enters the dust removal unit to separate the gas and particles, and the synthesis gas after the particles are separated enters the water washing and cooling unit;

[0011] The particles separated and captured by the dust removal unit are sent back to the reactor via the fly ash return unit;

[0012] The synthesis gas from the dust removal unit is sent to the downstream device after being cooled in the water washing and cooling unit;

[0013] The solid biomass pressurized gasification system comprises: a feeding unit, an air intake unit, a reactor, a separator, a slag removal unit, a waste heat recovery unit, a dust removal unit, a fly ash return unit, and a water washing and cooling unit.

[0014] A further improvement is that the solid biomass is delivered to the feed unit, measured, and then added to the reactor through a conveying device under the combined effect of the solid biomass' own gravity and the kinetic energy of the conveying air.

[0015] A further improvement is that the conveying gas for the solid biomass is inert gas, synthesis gas or a mixture of the two.

[0016] A further improvement is that the gas and fluidizing gas required for the biomass gasification reaction are controlled and measured by the air intake unit, mixed in the required proportion, and then enter the reactor through different channels.

[0017] A further improvement is that the ratios of different gases in the gas composition in each channel are the same or different.

[0018] A further improvement is that the fluidizing gas required for fluidizing the reactor bed is water vapor, synthesis gas or a mixture of the two.

[0019] A further improvement is that the solid biomass from the feeding unit, the fly ash returned from the separator, the fly ash from the fly ash return furnace unit, and the gasifying agent from the air intake unit are converted into synthesis gas containing CO and H2 and ash in the reactor.

[0020] As a further improvement, the reactor is a fluidized bed type gasifier, the upper section and the lower section of the reactor are provided with one or more gasifying agent feed ports respectively, and the internal pressure of the reactor is 0.1 MPa-7.5 MPa.

[0021] A further improvement is that the separator is composed of one or more groups of cyclone separators connected in series, and each group of cyclone separators is a collection of a single cyclone separator or multiple cyclone separators.

[0022] A further improvement is that, in the waste heat recovery unit, the synthesis gas from the separator is first heat exchanged with water, water vapor or a mixture of water and water vapor to be reduced to 650°C ~ 750°C, then mixed with a quenching medium and reduced to 450°C ~ 550°C, and finally heat exchanged with water, water vapor or a mixture of water and water vapor to be reduced to 350°C ~ 400°C before leaving the waste heat recovery unit.

[0023] A further improvement is that the filter element of the dust collector is a metal filter element or a ceramic filter element.

[0024] As a further improvement, the synthesis gas from the dust removal unit is cooled to 140°C ~ 200°C by a heat exchanger in the water washing cooling unit and then enters the water washing tower, where it contacts with the washing water for heat and mass transfer and drops to 30°C ~ 180°C before exiting the water washing tower and being sent to the downstream device as the product gas of the pressurized gasification process system.

[0025] A further improvement is that the solid biomass and fly ash are converted into synthesis gas and ash in the reactor. The synthesis gas leaves the upper part of the reactor and enters the separator step. The internal temperature of the lower section of the reactor is 750°C to 850°C, and the internal temperature of the upper section of the reactor is 950°C to 1050°C.

[0026] A further improvement is that the synthesis gas in the fluidizing gas required for fluidization of the reactor bed and the synthesis gas in the transport gas of the solid biomass contain the gas rich in CO and H2 discharged from the dust removal unit, or the gas rich in CO and H2 discharged from the dust removal unit and then treated, or a mixture of the above two. The synthesis gas discharged from the dust removal unit may be further treated by a water washing and cooling device, or by a downstream device after water washing and cooling.

[0027] The beneficial effects of the present invention are:

[0028] In the solid biomass pressurized gasification process provided by the present invention, the temperature of the upper section of the reactor is higher than that of the lower section of the reactor, and the tar generated in the lower section of the reactor is further converted in the upper section of the reactor, thereby effectively reducing the tar content in the synthesis gas at the reactor outlet; the operating temperature of the synthesis gas of the heat exchanger in the waste heat recovery unit is reasonably selected, thereby effectively reducing the corrosion and scaling of the heat exchanger by the alkali metal or alkaline earth metal carried by the synthesis gas; the synthesis gas replaces water vapor as the fluidizing gas of the reactor, thereby greatly reducing the use of water vapor and the amount of wastewater discharged from the gasification process system; compared with the use of CO2-rich gas from the synthesis gas purification device, the use of synthesis gas as the conveying gas for solid particles entering the reactor can save the compression power consumption for pressurizing the gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0030] Figure 1is a process flow chart of the solid biomass pressurized gasification process of the present invention;

[0031] Figure 2 It is a schematic diagram of the sources of transport gas and fluidization gas in the solid biomass pressurized gasification process of the present invention;

[0032] Figure 3 It is a schematic diagram of the structure of the reactor used in the solid biomass pressurized gasification process of the present invention.

[0033] Description of the reference numerals in the accompanying drawings:

[0034] 10- material preparation device, 20- gasification device, 30- conversion device, 40- first compression device, 50- purification device, 60- second compression device;

[0035] 210-feeding unit, 220-air intake unit, 230-reactor, 240-separator, 250-slag discharge unit, 260-waste heat recovery unit, 270-dust removal unit, 280-fly ash return unit, 290-water washing and cooling unit;

[0036] 01, 11-solid biomass, 02-O2-rich gas, 03-steam, 04-H2-rich gas, 21-synthesis gas, 31-conversion gas, 41, 42, 43-conversion gas, 51-purified gas, 52-CO2-rich gas, 61-fresh gas;

[0037] 201, 211-solid biomass, 202-O2-rich gas, 203-steam, 204, 207-transport gas, 205-fluidizing gas, 206-backflush gas, 208-quenching medium, 209-washing water, 231, 241, 261, 271, 291-synthesis gas, 221-gasifying agent, 232, 251-ash, 242, 272, 281-fly ash, 292-tar-containing water;

[0038] 2301 - reactor lower section, 2303 - reactor upper section, 2304 - distributor, 2311, 2312, 2313, 2315 - gasifying agent inlets, 2314, 2317, 2318 - feed inlets, 2316 - discharge outlet. DETAILED DESCRIPTION

[0039] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0040] In the description of the invention, it is necessary to understand that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] In the invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to the specific circumstances.

[0043] Unless expressly specified or limited otherwise, the term "synthesis gas" is to be understood as a gas containing CO and H2.

[0044] The specific implementation is as follows:

[0045] like Figure 1 As shown, the present invention provides a solid biomass pressurized gasification process, and the process steps implemented by a solid biomass pressurized gasification system are as follows:

[0046] The solid biomass pressurized gasification process includes a feed unit 210, an air intake unit 220, a reactor 230, a separator 240, a slag removal unit 250, a waste heat recovery unit 260, a dust removal unit 270, a fly ash return unit 280, and a water washing and cooling unit 290. The implementation process includes the following steps:

[0047] 1) Feeding: The solid biomass 201 that has been qualified after being processed by the upstream preparation device is sent to the feeding unit 210 and then added to the reactor 230 through the conveying device under the combined action of the solid biomass 201's own gravity and the kinetic energy of the conveying gas 204. The solid biomass 211 can enter the reactor 230 from the feeding unit 210 through one, two, or more channels. The conveying gas 204 used to convey the solid biomass to the feeding unit 210 can be inert gas (rich in N2 or rich in CO2) or synthesis gas, preferably synthesis gas from the dust removal unit 270 and its downstream. The solid biomass 201 entering the feeding unit 210 is generally required to have an external moisture content of no more than 30% and a particle size of 5mm to 30mm.

[0048] 2) Intake: The O2-rich gas 202, steam 203, and fluidizing gas 205 required for the fluidization of the reactor 230 bed are controlled and metered by the intake unit 220, and then mixed in the required proportions and enter the reactor 230 through different channels. The gas composition in each channel can be the same or different. The O2-rich gas 202 can be substantially pure O2, which is obtained from the atmosphere via an air separation unit. The fluidizing gas 205 required for the fluidization of the reactor 230 bed can be water vapor, synthesis gas, or a mixture of the two, preferably synthesis gas from the dust removal unit 270 and its downstream. Using synthesis gas instead of water vapor can reduce the use of water vapor and the amount of wastewater discharged from the gasification process system.

[0049] 3) Gasification: Solid biomass 211 from the feed unit 210, fly ash 242 from the separator 240, fly ash 281 from the fly ash return unit 280, and gasifying agent 221 (oxygen, steam, synthesis gas) from the air intake unit are converted into synthesis gas and ash containing CO and H2 in the reactor 230. Synthesis gas 231 carries a large amount of particles (fly ash) and leaves the upper part of the reactor 230 and enters the separator 240. The mass content of carbon element in the particles is 20% to 80%. Most of the particles are separated from the synthesis gas 231 by the separator 240. The unseparated particles leave the separator 240 with the synthesis gas 241 and enter the waste heat recovery unit 260. The separated particles (fly ash 242) are basically particles with relatively large particle size, accounting for 50% to 99% of the total mass of particles carried by the synthesis gas 231. The fly ash 242 is sent back to the reactor. The ash 232 exits from the bottom of the reactor 230 and enters the ash discharge unit 250 .

[0050] Reactor 230 is a fluidized bed type gasifier. The gasification agent feed ports of the upper and lower sections of reactor 230 can be selected as one or more, respectively. The internal pressure of reactor 230 is 0.1MPa (gauge pressure) to 7.5MPa (gauge pressure). The internal temperature of the lower section of reactor 230 is 750℃ to 850℃. Too low temperature is not conducive to the biomass reaction conversion, resulting in a high carbon content in the ash 232 and an increase in the CH4 content in the synthesis gas 231. Too high temperature may cause slagging of biomass ash due to the low ash melting point, thereby affecting the continuous and stable operation of the system. The internal temperature of the upper section of reactor 230 is 950℃ to 1050℃. The synthesis gas generated in the lower section of reactor 230 carries the residual carbon particles, tar and fly ash generated by the incomplete reaction into the upper section of reactor 230 for high-temperature gasification, tar cracking and solid particle ash removal.

[0051] The separator 240 may be selected to be one or more groups of cyclone separators connected in series, and each group of cyclone separators may be selected to be a collection of a single cyclone separator or a plurality of cyclone separators.

[0052] 4) Slag discharge: The high-temperature ash 232 from the reactor 230 is cooled by the slag discharge unit 250 and then sent to the atmospheric pressure equipment. The stacking height of the solid material in the reactor 230 can be controlled by adjusting the discharge amount of the ash 232 of the reactor.

[0053] 5) Waste heat recovery: In the waste heat recovery unit 260, the synthesis gas (and particles) 241 from the separator 240 is first heat-exchanged with water, water vapor or a mixture of water and water vapor to be reduced to 650°C to 750°C, then mixed with the quenching medium 208 to be reduced to 450°C to 550°C, and finally heat-exchanged with water, water vapor or a mixture of water and water vapor to be reduced to 350°C to 400°C (greater than the tar dew point) before leaving the waste heat recovery unit 260. The waste heat recovery unit 260 may produce steam as a by-product. The quenching medium 208 may be selected from water, water vapor, synthesis gas or other gases. Preferably, the quenching medium 208 includes synthesis gas, which contains CO and H2-rich gas discharged from the dust removal unit 270, or CO and H2-rich gas discharged from the dust removal unit 270 and then treated, or a mixture of the above two. The temperature of the synthesis gas (and particles) 241 drops rapidly from 650°C to 750°C to 450°C to 550°C, which can rapidly change the alkali metal contained in the synthesis gas 241 from gas to solid, thereby preventing corrosion and scaling of the heat exchanger caused by the adhesion of the alkali metal to the metal wall. The temperature of the synthesis gas 261 when leaving the waste heat recovery unit and entering the dust removal unit 270 is higher than the tar dew point, which can effectively prevent the liquid tar after the condensation of the gaseous tar from aggregating with the particles carried in the synthesis gas 261 and clogging the flow channel of the synthesis gas 261 and the equipment of the downstream dust removal unit 270.

[0054] 6) Dust removal: The synthesis gas 261 from the waste heat recovery unit 260 enters the dust removal unit 270 for separation of gas and particles. The synthesis gas 271 with a particle content of no more than 2 mg / Nm3 after particle separation enters the water washing and cooling unit 290. The particles (fly ash 272) separated and captured by the dust removal unit 270 are sent to the fly ash return unit 280. The dust removal equipment of the dust removal unit can be selected as a dust collector or a cyclone separator with a dust collector connected in series downstream. The filter element of the dust collector can be selected as a metal filter element or a ceramic filter element.

[0055] 7) Fly ash return to the furnace: The mass content of carbon element in the particles (fly ash 272) separated and captured by the dust removal unit 270 is 20% to 80%. In order to improve the utilization rate of carbon element in the biomass 201 and reduce energy consumption, in the fly ash return to the furnace unit 280, the fly ash 272 is returned to the reactor 230 for further reaction and conversion under the action of the conveying gas 207. The conveying gas 207 can be selected as an inert gas (rich in N2 or CO2), a syngas or a mixture of the two, preferably a syngas from the dust removal unit 270 and its downstream.

[0056] 8) Water washing and cooling: In the water washing and cooling unit 290, the synthesis gas 271 from the dust removal unit 270 is cooled to 140℃~200℃ by the heat exchanger and then enters the water washing tower. After contacting with the washing water 209 for heat and mass transfer, the synthesis gas 291 exiting the water washing tower at 30℃~180℃ is sent to the downstream device as the product gas of the pressurized gasification process system. The particle content of the synthesis gas 291 is not higher than 0.1mg / Nm3. The gas (synthesis gas 231) generated in the reactor 230 contains a certain amount of tar, most of which is condensed into water in the water washing and cooling unit 290, and the tar content of the synthesis gas 291 is not higher than 50mg / Nm3. The washing water 209 that conducts heat and mass transfer with the synthesis gas 271 enters the water washing tower from the upper part of the water washing tower, and leaves the water washing tower from the lower part or bottom of the water washing tower together with the condensed tar (tar-containing water 292). The water washing tower is a tower container.

[0057] The internal pressure of the fluidized bed reactor 230 is 1.0 MPa (gauge pressure), the temperature of the lower section of the reactor 230 is 750°C~850°C, the internal temperature of the upper section of the reactor 230 is 950°C~1050°C, the received lower calorific value of the solid biomass 201 is 14.65 MJ / kg, and other parameters of the solid biomass 201 are shown in the specifications in Tables 1 to 4, the composition of the synthesis gas 231 is shown in Table 5, and the composition of the conversion gas 41 / 42 / 43 is shown in Table 6.

[0058] Table 1 Solid biomass specifications - industrial analysis

[0059] project unit Numeric Full moisture, Aar ％ 12.90 Air dried moisture Aad ％ 11.62 Air dried basis volatile matter Vad ％ 63.56 Air dried fixed carbon FCad ％ 14.49 Air dry basis ash Vad ％ 10.33

[0060] Table 2 Solid biomass specifications - elemental analysis (dry basis)

[0061] project unit Numeric Carbon, Cd wt.% 47.89 Hydrogen, Hd wt.% 4.03 Oxygen, Od wt.% 34.07 Nitrogen, Nd wt.% 1.22 Sulfur, Sd wt.% 0.14 Chlorine, Cld wt.% 0.96

[0062] Table 3 Solid biomass specifications - ash fusibility analysis

[0063]

[0064]

[0065] Table 4 Solid biomass specifications - ash composition analysis

[0066] project unit Numeric Na2O ％ 1.18 K2O ％ 15.72 Fe2O3 ％ 1.15 CaO ％ 9.22 MgO ％ 9.72 MnO ％ 0.41 SiO2 ％ 53.12 Al2O3 ％ 2.08 TiO2 ％ 0.09 SO3 ％ 1.25 P2O5 ％ 4.03 Cl ％ 1.92 RbO2 ％ 0.01 SrO ％ 0.03 Br ％ 0.05 ZnO ％ 0.02

[0067] Table 5 Synthesis gas specifications

[0068] project unit Numeric H2 Mol.% 27.167 CO Mol.% 27.806 CO2 Mol.% 18.990 CH4 Mol.% 4.462 N2 Mol.% 0.315 Ar Mol.% 0.051 NH3 Mol.% 0.268 H2S Mol.% 0.045 COS Mol.% 0.00045 HCl Mol.% Trace H2O Mol.% 18.990 tar mg / Nm3 100 total Mol.% 100.0

[0069] Table 6 Shift gas specifications

[0070]

[0071]

[0072] When converting solid carbonaceous feedstock into synthesis gas for the production of methanol or ammonia, the following steps are included: gasification (forming synthesis gas optionally containing tar fraction), tar reforming or removal (if tar is present), synthesis gas conditioning by water gas shift, acid gas and impurity removal (H2S, COS and part of CO2 removal), compression. Figure 2 As shown in the example, the raw material solid biomass 01 is treated for moisture content, particle size, etc. in the material preparation device 10, and the solid biomass 11 after qualified treatment is sent to the gasification device 20 to react with the O2-rich gas 02, steam 03, etc. After the reaction, the biomass is converted into synthesis gas and ash, and the high-temperature dusty synthesis gas is recovered by waste heat, dust removal, and water washing to separate most of the tar. The synthesis gas 21 enters the downstream conversion device 30 at 30°C to 180°C. Under the same pressure, the higher the temperature of the synthesis gas 21, the higher its saturated water vapor partial pressure. The synthesis gas 21 leaves the gasification device 20 at 30°C to 180°C instead of lower or room temperature. The synthesis gas 21 will carry more water into the conversion device 30. This part of the water can provide raw materials for the synthesis gas 21 when the water-gas shift reaction is carried out in the conversion device 30, thereby reducing the water vapor consumption of the conversion device 30, and the wastewater volume of the gasification device 20 is correspondingly reduced. According to the requirements for the H2 and CO content in the fresh gas 61, the synthesis gas 21 is converted into the water-gas shift reaction in the conversion device 30. Adjust the H2 and CO content in the gas (increase the H2 content, reduce the CO content). When, in addition to the synthesis gas 21 of the gasification device 20 providing the CO and / or H2 required by the downstream device, there are other sources to provide the H2-rich gas 04, such as the process route of preparing synthesis gas by biomass gasification and coupling the production of methanol by electrolysis of water through wind and solar power generation, if the amount of H2-rich gas 04 is sufficient and there is no need to increase the H2 in the fresh gas 61 through the water-gas shift reaction of the conversion device 30, then the conversion device 30 may not be set in the process. The conversion gas 31 obtained after adjusting the H2 and CO content enters the first compression device 40 for pressurization. The gas pressurized by the first compression device 40 is divided into three routes: conversion gas 41, conversion gas 42, and conversion gas 43. The conversion gas 41 is purified by the purification device 50, and the conversion gas 42 and the conversion gas 43 are respectively separated from the appropriate positions of the compressor of the first compression device 40 and returned to the gasification device 20. The shifted gas 42 is not cooled by the heat exchanger in the first compression device 40 and is used for fluidization of the reactor and back-flushing of the dust collector, such as Figure 1 The fluidizing gas 205 and the back-blowing gas 206 are used. The conversion gas 43 is cooled to room temperature to 40°C by the heat exchanger in the first compression device 40 and is used for the transportation of solid particles, such as Figure 1 The conveying gas 204 and conveying gas 207 in the gasification device 50 are used as the conveying gas 204 and conveying gas 207. The purified gas 51 after H2S, tar and all or part of CO2 are removed by the purification device 50 is further pressurized by the second compression device 60 to obtain fresh gas 61. Optionally, when there is H2-rich gas 04, the purified gas 51 is mixed with H2-rich gas 04 to obtain fresh gas 61. The purification device 50 can be selected as a low-temperature methanol washing process technology, and the tar content in the purified gas 51 obtained by the low-temperature methanol washing process is less than 1 mg / Nm3. The oxygen content in the biomass raw material is high, and water is easily generated during biomass gasification. The synthesis gas (conversion gas 42) replaces water vapor as the fluidizing gas of the fluidized bed reactor, which greatly reduces the water vapor usage of the gasification device 20, and also reduces the wastewater discharge of the gasification device 20. The conveying gas required for the transportation of solid particles in the gasification device 20 is usually an inert gas. When the solid particles need to be fed into the reactor, the pressure of the conveying gas needs to be higher than the pressure of the reactor, such as the pressurized gas of the CO2-rich gas 52 generated in the purification device 50. The pressure of the CO2-rich gas 52 is usually 0.15-0.05 MPa (gauge pressure), which is much lower than the pressure of the shift gas 31. The use of the synthesis gas (shift gas 43) instead of the CO2-rich gas 52 as the conveying gas for solid particles can save the compression power required to increase the pressure of the conveying gas. Compared with the use of the pressurized gas of the CO2-rich gas 52, the use of the shift gas 42 as the back-blowing gas 206 of the dust collector of the gasification device 20 can also save compression power.

[0073] For a specific device, whether the shifted gas 31 to the shifted gas 41 and the purified gas 51 to the fresh gas 61 need to be pressurized depends on the pressure of the synthesis gas 21 and the pressure of the fresh gas 61. When the shifted gas 31 does not need to be pressurized to obtain the shifted gas 41, the first compression device 40 only pressurizes a part of the shifted gas 31 to obtain the shifted gas 42 and the shifted gas 43.

[0074] like Figure 3As shown, the reactor 230 is a fluidized bed type gasifier, which is divided into a reactor lower section 2301 and a reactor upper section 2303. The upper portion of the reactor lower section 2301 is directly connected to the lower portion of the reactor upper section 2303. The reactor lower section 2301 is provided with openings including a gasification agent inlet 2311, a gasification agent inlet 2312, a gasification agent inlet 2313, a feed inlet 2314, a feed inlet 2317, and a feed inlet 2318. The reactor upper section 2303 is provided with openings including a gasification agent inlet 2311, a gasification agent inlet 2312, a gasification agent inlet 2313, a feed inlet 2314, a feed inlet 2317, and a feed inlet 2318. 15. Discharge port 2316. The openings with the same function of the reactor lower section 2301 and the reactor upper section 2303 can be selected to be one, two or more. A distributor 2304 is arranged inside the reactor lower section 2301. The distributor 2304 is in an inverted cone shape. The distributor 2304 is provided with a certain number of openings. The gas required for fluidization of the solid particles inside the reactor lower section 2301 enters the reactor 230 through the gasification agent port 2313 and then flows through the openings on the distributor 2304. The internal pressure of the reactor 230 is 0.1MPa (gauge pressure) to 7.5MPa (gauge pressure). The solid biomass 211 from the feeding unit 210 passes through the feeding port 2314, the fly ash 242 from the separator 240 passes through the feeding port 2317, and the fly ash 281 from the fly ash return unit 280 passes through the feeding port 2318, and the gasifying agent 221 (oxygen, steam, synthesis gas) from the air intake unit passes through the gasifying agent port 2311, the gasifying agent port 2312 and the gasifying agent port 2313, and is converted into synthesis gas containing CO and H2, residual carbon particles and ash in the lower section 2301 of the reactor. The synthesis gas contains tar components, and the synthesis gas carries the residual carbon particles, tar and fly ash generated by incomplete reaction into the upper section 2303 of the reactor, and the ash 232 leaves from the gasifying agent port 2312 at the bottom of the lower part 2301 of the reactor and enters the slag discharge unit 250. The temperature of the area above the distributor 2304 of the lower section 2301 of the reactor is 750°C to 850°C. If the temperature is too low, it is not conducive to the biomass reaction conversion, resulting in a high carbon content in the ash 232 and an increase in the CH4 content in the synthesis gas 231. If the temperature is too high, the biomass ash may slag due to the low ash melting point, thereby affecting the continuous and stable operation of the system. In the upper section 2303 of the reactor, the synthesis gas generated by the lower section 2301 of the reactor and the residual carbon particles it carries that are not completely reacted react with the gasification agent (containing O2) entering through the gasification agent port 2315. The synthesis gas 231 generated by the reaction carries a large amount of particles (referred to as fly ash in the present invention) and leaves the discharge port 2316 at the upper part of the upper section 2303 of the reactor and enters the separator 240. The overall thermal effect of the reaction in the upper section 2303 of the reactor is an exothermic reaction, so the temperature of the upper section 2303 of the reactor is higher than that of the lower section 2301 of the reactor. The internal temperature of the upper section 2303 of the reactor is 950°C to 1050°C. The increase in temperature is beneficial to the full conversion of carbon elements in tar and particles into small molecular gas products, effectively improving the gasification efficiency and gas production rate of biomass.The diameter of the upper section 2303 of the reactor is larger than that of the lower section 2301 of the reactor, so that the gas flow rate in the upper section 2303 of the reactor is smaller than that in the lower section 2301 of the reactor. The reduction in gas flow rate is beneficial to increase the residence time of the material and reduce the mass of particles carried by the synthesis gas 231. Figure 3 Not all openings of the reactor 230 are shown.

[0075] The pressurized gasification process of the present invention is suitable for preparing fuel gas or synthesis gas by pressurized gasification of solid biomass in a fluidized bed, especially under the working conditions of methanol synthesis with high oxygen content and high alkali metal content in biomass and requiring steam.

[0076] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A solid biomass pressurized gasification process, characterized in that: The process steps implemented by a solid biomass pressurized gasification system are as follows: The solid biomass is fed into a feed unit and then added to the reactor; The gas and fluidizing gas required for the biomass gasification reaction enter the reactor after being controlled by the air intake unit; Solid biomass and fly ash are converted into synthesis gas and ash in the reactor. The synthesis gas leaves the upper part of the reactor and enters the separator and then the waste heat recovery unit. The ash and slag enter the slag discharge unit from the lower part of the reactor; In the waste heat recovery unit, the syngas is cooled and heat is recovered; The synthesis gas from the waste heat recovery unit enters the dust removal unit to separate the gas and particles, and the synthesis gas after the particles are separated enters the water washing and cooling unit; The synthesis gas from the dust removal unit is washed and cooled in the water washing and cooling unit and then sent to the downstream device; The solid biomass pressurized gasification system comprises: a feeding unit, an air intake unit, a reactor, a separator, a slag removal unit, a waste heat recovery unit, a dust removal unit, a fly ash return unit, and a water washing and cooling unit; The gas required for the biomass gasification reaction and the fluidizing gas in the fluidizing gas are synthesis gas, or water vapor, or a mixture of synthesis gas and water vapor.

2. The solid biomass pressurized gasification process according to claim 1, characterized in that: The solid biomass is fed to the feed unit and then metered and added to the reactor through a conveying device under the combined action of the solid biomass' own gravity and the kinetic energy of the conveying gas. The conveying gas for the solid biomass is inert gas, synthesis gas or a mixture of the two.

3. The solid biomass pressurized gasification process according to claim 1, characterized in that: The separator is composed of one or more groups of cyclone separators connected in series, and each group of cyclone separators is a collection of a single cyclone separator or multiple cyclone separators.

4. The solid biomass pressurized gasification process according to claim 1, characterized in that: The fly ash separated by the separator is sent back to the reactor.

5. The solid biomass pressurized gasification process according to claim 1, characterized in that: The heat exchange in the waste heat recovery unit is divided into three stages. The synthesis gas from the separator is firstly heat exchanged with water, water vapor or a mixture of water and water vapor to be reduced to 650°C-750°C, then mixed with a quenching medium and reduced to 450°C-550°C, and finally heat exchanged with water, water vapor or a mixture of water and water vapor to be reduced to 350°C-400°C before leaving the waste heat recovery unit.

6. The solid biomass pressurized gasification process according to claim 5, characterized in that: The quenching medium is water, water vapor, synthesis gas or other gases.

7. The solid biomass pressurized gasification process according to claim 1, characterized in that: The dust removal unit comprises a dust collector and back-blowing gas, and the filter element of the dust collector is a metal filter element or a ceramic filter element.

8. The solid biomass pressurized gasification process according to claim 7, characterized in that: The back-blowing gas is inert gas, synthesis gas or a mixture of the two.

9. The solid biomass pressurized gasification process according to claim 1, characterized in that: The fly ash separated and captured by the dust removal unit is sent back to the reactor through the fly ash return unit.

10. The solid biomass pressurized gasification process according to claim 9, characterized in that: In the fly ash returning unit, the fly ash is returned to the reactor under the action of a conveying gas, and the conveying gas is an inert gas or a synthesis gas.

11. The solid biomass pressurized gasification process according to any one of claims 1, 2, 6, 8 and 10, characterized in that: The synthesis gas contains CO and H2-rich gas discharged from the dust removal unit, or CO and H2-rich gas discharged from the dust removal unit and then treated, or a mixture of the two.

12. The solid biomass pressurized gasification process according to claim 1, characterized in that: The synthesis gas from the dust removal unit is cooled by the heat exchanger in the water washing and cooling unit and then enters the water washing tower. After contacting with the washing water for heat and mass transfer, it leaves the water washing and cooling unit and is sent to the downstream device as the product gas of the pressurized gasification process system.

13. The solid biomass pressurized gasification process according to claim 12, characterized in that: The gas leaving the water washing cooling unit is reduced to 30℃~180℃.

14. The solid biomass pressurized gasification process according to claim 1, characterized in that: The solid biomass from the feed unit, the fly ash returned from the separator, the fly ash from the fly ash return unit, and the gasifying agent from the air intake unit are converted into synthesis gas containing CO and H2 and ash in the reactor.

15. The solid biomass pressurized gasification process according to claim 1, characterized in that: The reactor is a fluidized bed type gasifier, the upper section and the lower section of the reactor are provided with one or more gasifying agent feed ports, respectively, and the internal pressure of the reactor is 0.1 MPa-7.5 MPa.

16. The solid biomass pressurized gasification process according to claim 1, characterized in that: The internal temperature of the lower section of the reactor is 750°C to 850°C, the internal temperature of the upper section of the reactor is 950°C to 1050°C, and the diameter of the upper section of the reactor is greater than the diameter of the lower section of the reactor.

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