Two-stage coal gasifier and coal gasification method

Abstract

The application discloses a two-stage coal gas generator and a coal gasification method, and relates to the technical field of coal gasification, and particularly relates to a two-stage coal gas generator and a coal gasification method. The coal gas generator comprises a coal gas generator, which is provided with a feeding opening, an upper-stage coal gas outlet, a lower-stage coal gas outlet, a second gasification agent inlet and a first gasification agent inlet; a grate is arranged in the coal gas generator and located below the second gasification agent inlet; and a phenol water stripping tower is provided with a phenol water steam outlet of the phenol water stripping tower, which is in communication with the first gasification agent inlet and the second gasification agent inlet. The heat of the lower-stage coal gas is used for heating phenol water in a reboiler and superheating water vapor in a superheater, respectively. In the meanwhile, the sensible heat of the lower-stage coal gas is recovered, the temperature of the lower-stage coal gas is reduced, the thermal efficiency is high, the phenol water obtained after purification treatment of the upper-stage coal gas is recycled and utilized, and the resource utilization rate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal gas furnace. More particularly, the present application relates to a two-stage coal gas generator and a coal gasification method. BACKGROUND

[0002] The two-stage coal gas furnace is a technology for producing coal gas by using coal as raw material through fixed bed gasification method, which generally has upper-stage coal gas and lower-stage coal gas. The upper-stage coal gas is collected from the coal pyrolysis and drying area, which contains tar and phenols. A large amount of phenolic wastewater is generated in the purification process of the upper-stage coal gas. The lower-stage coal gas is collected from the coal combustion and gasification area, which generally does not contain tar and phenols.

[0003] In the prior art, the phenolic water is heated to vaporize into steam, which is added to the gasification agent to react in the coal gas furnace to try to solve the phenolic water treatment problem. However, the heating of the phenolic water requires a large amount of heat energy, and the phenolic steam directly added to the gasification agent condenses after mixing with cold air, and the phenol is enriched in the condensate, causing new pollution, without solving the root problem. In addition, the temperature of the lower-stage coal gas is generally high, and the purification and cooling treatment of the lower-stage coal gas wastes the sensible heat of the coal gas, resulting in low system thermal efficiency.

[0004] How to reasonably plan and utilize energy to improve system thermal efficiency while avoiding secondary pollution is a difficult problem that needs to be solved by technical personnel. SUMMARY

[0005] An object of the present application is to solve at least the above problems and provide at least the advantages to be described later.

[0006] Another object of the present application is to provide a two-stage coal gas generator and a coal gasification method, which solves the technical problems of difficult phenolic water treatment, high energy consumption and low thermal efficiency of the existing two-stage coal gas furnace.

[0007] In order to achieve these objects and other advantages according to the present application, a two-stage coal gas generator is provided, which comprises:

[0008] The coal gas generator (100) is provided with a feeding port (110) at the top and a slag discharge port (130) at the bottom. A side of the coal gas generator is provided with an upper-stage coal gas outlet (140), at least one lower-stage coal gas outlet (150), at least one second gasification agent inlet (170) and a first gasification agent inlet (120) from top to bottom.

[0009] a grate (160) arranged in the coal gas generator (100) and located below the second gasifying agent inlet (170), the bottom of the grate (160) being in communication with the first gasifying agent inlet (120) and the top being provided with air distribution ports in communication with the reaction chamber of the coal gas generator (100); the grate is a multi-layer structure arranged from bottom to top, the diameter of the multi-layer structure decreases from bottom to top, each layer is provided with air distribution ports, and the air volume of the air distribution ports decreases from top to bottom; the air volume per unit area of the air distribution ports on the topmost layer is not more than 200% of the average air volume per unit area, and the air volume per unit area of the air distribution ports on the bottommost layer is not less than 30% of the average air volume per unit area;

[0010] a phenol water stripping tower (300) provided with a phenol water vapor outlet (330) of the phenol water stripping tower in communication with the first gasifying agent inlet (120) and the second gasifying agent inlet (170); the phenol water stripping tower is also provided with an oxygen-containing gas inlet (320) of the phenol water stripping tower and a sewage outlet (340).

[0011] Preferably, the two-stage coal gas generator further comprises:

[0012] a reboiler (400) provided with a coal gas outlet (420) of the reboiler, a phenol water inlet (430) of the reboiler in communication with the phenol water outlet (380) of the phenol water stripping tower, a phenol water outlet (440) of the reboiler in communication with the second phenol water inlet (390) of the phenol water stripping tower, and a coal gas inlet (410) of the reboiler in communication with the lower-stage coal gas outlet (150);

[0013] a coal gas cooler (600) provided with a coal gas inlet (610) of the coal gas cooler in communication with the coal gas outlet (420) of the reboiler on one side and a lower-stage coal gas outlet (620) on the other side.

[0014] Preferably, the two-stage coal gas generator, the air volume per unit area of the air distribution ports on the topmost layer is not more than 200% of the average air volume per unit area, and the air volume per unit area of the air distribution ports on the bottommost layer is not less than 30% of the average air volume per unit area.

[0015] Preferably, the two-stage coal gas generator further comprises an electric tar precipitator (700), a gas intercooler (800) and a phenol water tank (900) connected in sequence; the gas inlet (710) of the electric tar precipitator is communicated with the upper-stage gas outlet (140), the gas outlet (720) of the electric tar precipitator is communicated with the gas inlet (810) of the gas intercooler, the cooling medium in the gas intercooler (800) is cold water, the upper-stage gas discharge port (820) is arranged in the middle of one side of the gas intercooler, and the lower part of the gas intercooler is provided with a phenol water outlet (830) of the gas intercooler communicated with the phenol water inlet (910) of the phenol water tank; the phenol water outlet (920) of the phenol water tank is communicated with the first phenol water inlet (310) of the phenol water stripping tower.

[0016] Preferably, the two-stage coal gas generator, the phenol water outlet (380) of the phenol water stripping tower is provided with a phenol water pressurizing pump (500) between the phenol water inlet (430) of the reboiler.

[0017] Preferably, the two-stage coal gas generator further comprises a superheater (200), the gas inlet (210) of the superheater is communicated with the lower-stage gas outlet (150), the gas outlet (220) of the superheater is communicated with the gas inlet (410) of the reboiler, the phenol-containing steam inlet (230) of the superheater is communicated with the phenol water steam outlet (330) of the phenol water stripping tower, and the phenol-containing steam outlet (240) of the superheater is communicated with the first gasification agent inlet (120) and the second gasification agent inlet (170).

[0018] Preferably, the two-stage coal gas generator further comprises a cyclone separator (250), the upper part of one side of the cyclone separator is provided with a gas inlet communicated with the lower-stage gas outlet (150), the top of the cyclone separator is provided with a gas outlet communicated with the gas inlet (210) of the superheater, and the bottom of the cyclone separator is provided with a fly ash discharge port.

[0019] Preferably, the two-stage coal gas generator, the oxygen-containing gas inlet (320) of the phenol water stripping tower is communicated with the oxygen-containing gas outlet (1020) of the pressure swing adsorption device, one side of the pressure swing adsorption device (1000) is provided with a gas inlet (1010) communicated with external air, and the bottom of the pressure swing adsorption device is provided with a tail gas discharge port (1030).

[0020] Preferably, the two-stage coal gas generator, each second gasification agent inlet (170) comprises a plurality of gasification agent inlets uniformly arranged in the circumferential direction, and the gasification agent discharge amount of all the gasification agent inlets is not greater than the gasification agent discharge amount of the first gasification agent inlet.

[0021] The application also provides a coal gasification method of the two-stage coal gas generator, which comprises the following steps:

[0022] Step one, coal raw material is added from the charging port (110) on the top of the coal gas generator, and the gasifying agent is added from the first gasifying agent inlet on the bottom of the two-stage coal gas generator, the raw material successively undergoes drying, pyrolysis, gasification and combustion reactions, the temperature in the gasification and combustion reaction zone can reach 800-1100℃, the unreacted ash is discharged from the ash discharge port (130) on the bottom of the coal gas generator, and the generated coal gas is discharged from the upper-stage coal gas outlet (140) and the lower-stage coal gas outlet (150) respectively;

[0023] Step two, the upper-stage coal gas flows into the electric tar catcher (700) to remove tar, and then flows into the intercooler (800) to be cooled by cooling water, and the residual upper-stage coal gas is discharged through the upper-stage coal gas discharge port (820) of the intercooler, and the condensate of the upper-stage coal gas is discharged from the phenol water outlet (830) of the intercooler into the phenol water pool (900);

[0024] Step three, the phenol water after precipitation in the phenol water pool (900) flows into the phenol water stripping tower (300), the phenol water in the phenol water stripping tower is pressurized by the phenol water pressurizing pump (500) and then flows into the reboiler (400), the lower-stage coal gas is discharged through the lower-stage coal gas outlet (150) to the cyclone separator for purification by removing fly ash particles, and then flows into the superheater to be once heat-exchanged with the gasifying agent and then flows into the reboiler to be twice heat-exchanged with the phenol water, so that the sensible heat of the lower-stage coal gas is fully recovered and utilized; the phenol water is heated by the heat source in the reboiler (400) and then returns to the phenol water stripping tower (300), and the phenol water is vaporized to form phenol water vapor; at the same time, the oxygen-containing gas formed by processing air through the pressure swing adsorption device (1000) enters the phenol water stripping tower (300), the mixed gas formed by the oxygen-containing gas and the phenol water vapor flows out from the phenol water vapor outlet (330) of the phenol water stripping tower, flows into the coal gas generator reaction chamber through the first gasifying agent inlet and the second gasifying agent inlet via the superheater, and the phenol vapor in the gasifying agent is decomposed into small molecule gas in the high-temperature environment of the coal gas furnace reaction chamber;

[0025] Step four, the lower-stage coal gas flowing into the reboiler is heat-exchanged twice and then discharged to the coal gas cooler for further cooling, and then discharged through the lower-stage coal gas discharge port of the coal gas cooler.

[0026] The present application at least includes the following beneficial effects:

[0027] 1. The present application makes full use of the sensible heat of the coal gas in the coal gas producer, the heat of the lower section coal gas is used to heat the phenol water in the reboiler and superheat the water vapor in the superheater, while recovering the sensible heat of the lower section coal gas, the temperature of the lower section coal gas is reduced, the thermal efficiency is high, the phenol water obtained after the purification treatment of the upper section coal gas is recycled and utilized, the resource utilization rate is improved; the gasifying agent is heated by the sensible heat of the coal gas, forms a superheated state, and is then sent into the coal gas producer for reaction, the superheat degree of the water vapor in the gasifying agent is high, the condensation of the water vapor to bring phenol into the ash and slag to form secondary pollution is avoided, and the problem of waste water treatment is completely solved;

[0028] 2. The present application makes the ventilation quantity per unit area of the cross section of the reaction hearth of the coal gas producer decrease from the center to the periphery by opening the air distribution port on the grate, and sets a second gasifying agent inlet to supplement the secondary gasifying agent into the reaction hearth of the coal gas producer. Near the grate, part of the airflow flows from the center to the outer layer; near the secondary gasifying agent inlet, part of the airflow flows from the outer layer to the center. Therefore, on the basis of the main airflow flowing upward, the lateral flow of the airflow is increased, thereby the contact and mixing of the gasifying agent and the solid raw material are strengthened, and the gas-solid reaction is improved

[0029] 3. The present application supplements the secondary gasifying agent into the reaction hearth of the coal gas producer through the second gasifying agent inlet, thereby the oxygen concentration of the combustion and gasification reaction area is reduced, and the highest temperature of the combustion and gasification reaction area is reduced. The risk of melting and slagging caused by the high oxygen concentration of the combustion and gasification reaction area and the highest temperature exceeding the ash softening temperature of the solid material is avoided; by setting the second gasifying agent inlet to supplement the secondary gasifying agent into the reaction hearth of the coal gas producer, the height of the combustion and gasification reaction area can be increased, thereby more raw materials can be gasified under the condition of the same diameter of the coal gas producer, and the production capacity of the coal gas producer is improved; or the residence time can be increased, the steam decomposition rate is improved, the amount of water vapor taken out of the furnace by the coal gas is reduced, and the amount of phenol-containing waste water is reduced.

[0030] 4. In the present application, the vaporization of the phenol water comes partly from the heat energy provided by the reboiler and partly from the decrease of the water vapor partial pressure and the saturation temperature after the oxygen-containing gas is added, compared with the complete vaporization provided by the heat energy, the consumption of the heat energy is greatly reduced.

[0031] 5. The present application sets a phenol water pressurizing pump, adjusts the pressure after the phenol water pressurizing pump, so that the phenol water is still in an undersaturated state (full liquid state) after being heated in the reboiler, the phenol water is not easy to scale in the reboiler, and the phenol water vaporizes again (such as pressure reduction) after flowing into the phenol water stripping tower from the reboiler. The phenol water stripping tower is provided with an external sewage outlet to discharge the salts and solid impurities in the phenol water, thereby avoiding the scaling and blockage of the phenol water stripping tower and the reboiler.

[0032] 6、The oxygen-containing gas of the present application can not only directly use air, but also can use oxygen-rich air by setting a pressure swing adsorption device, so as to reduce the concentration of nitrogen in the coal gas and improve the calorific value of the coal gas.

[0033] Other advantages, objects, and features of the present application will be apparent from the following specification, and will be understood by persons skilled in the art. BRIEF DESCRIPTION OF DRAWINGS

[0034] Fig. 1 Structure diagram of the two-stage coal gas generator in one technical solution of the present application;

[0035] Fig. 2 Distribution diagram of the second gasifying agent inlet in another technical solution of the present application.

[0036] BRIEF DESCRIPTION OF DRAWINGS

[0037] Coal gas generator (100), charging port (110), first gasifying agent inlet (120), slag discharge port (130), upper-stage coal gas outlet (140), lower-stage coal gas outlet (150), grate (160), second gasifying agent inlet (170), and a plurality of gasifying agent inlets (171-174);

[0038] Superheater (200), coal gas inlet (210) of the superheater, coal gas outlet (220) of the superheater, phenol-containing vapor inlet (230) of the superheater, phenol-containing vapor outlet (240) of the superheater, and cyclone separator (250);

[0039] Phenol water stripping tower (300), first phenol water inlet (310) of the phenol water stripping tower, oxygen-containing gas inlet (320) of the phenol water stripping tower, phenol vapor outlet (330) of the phenol water stripping tower, sewage discharge port (340), phenol water outlet (380) of the phenol water stripping tower, and second phenol water inlet (390) of the phenol water stripping tower;

[0040] Reboiler (400), coal gas inlet (410) of the reboiler, coal gas outlet (420) of the reboiler, phenol water inlet (430) of the reboiler, and phenol water outlet (440) of the reboiler;

[0041] Phenol water pressurizing pump (500);

[0042] Coal gas cooler (600), coal gas inlet (610) of the coal gas cooler, and coal gas outlet (620) of the coal gas cooler;

[0043] Electric tar precipitator (700), coal gas inlet (710) of the electric tar precipitator, and coal gas outlet (720) of the electric tar precipitator;

[0044] a coal gas intercooler (800), a coal gas inlet (810) of the coal gas intercooler, a coal gas outlet (820) of the coal gas intercooler, a phenol water outlet (830) of the coal gas intercooler;

[0045] a phenol water tank (900), a phenol water inlet (910) of the phenol water tank, a phenol water outlet (920) of the phenol water tank;

[0046] a pressure swing adsorption device (1000), an oxygen-containing gas inlet (1010) of the pressure swing adsorption device, an oxygen-containing gas outlet (1020) of the pressure swing adsorption device, a tail gas exhaust outlet (1030). DETAILED DESCRIPTION

[0047] The application will be further described in conjunction with the accompanying drawings and examples, so that those skilled in the art can implement the application according to the description.

[0048] It should be understood that the terms such as "have", "contain" and "include" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0049] It should be noted that the experimental methods in the following embodiments are all conventional methods, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0050] In the description of the application, the terms "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the application.

[0051] As shown in Figs. 1-2 The application provides a two-stage coal gas generator, which comprises:

[0052] The coal gas generator (100) is provided with a feeding port (110) at the top and a slag discharge port (130) at the bottom; one side of the coal gas generator is provided with an upper-stage coal gas outlet (140), at least one lower-stage coal gas outlet (150), at least one second gasifying agent inlet (170) and a first gasifying agent inlet (120) from top to bottom; the number of at least one lower-stage coal gas outlet is at least two, and the plurality of lower-stage coal gas outlets are distributed at at least two different heights; each lower-stage coal gas outlet is provided with a valve;

[0053] A grate (160) is arranged in the coal gasifier (100) below the second gasifying agent inlet (170), the bottom of the grate (160) is communicated with the first gasifying agent inlet (120), and the top of the grate (160) is provided with air distribution ports communicated with the reaction chamber of the coal gasifier (100); the grate (160) is a multi-layer structure stacked from bottom to top, the diameter of the multi-layer structure decreases from bottom to top, each layer is provided with air distribution ports, and the air volume of the air distribution ports decreases from top to bottom; the air volume per unit area of the air distribution ports on the topmost layer is not more than 200% of the average air volume per unit area, and the air volume per unit area of the air distribution ports on the bottommost layer is not less than 30% of the average air volume per unit area; the air volume per unit area is the air volume Q of the corresponding air distribution port / the area A1 of the corresponding air distribution port; and the average air volume per unit area is the total air volume Q of the furnace / the total air distribution port area A of the furnace.

[0054] A phenol water stripping tower (300) is provided with a phenol water vapor outlet (330) of the phenol water stripping tower communicated with the first gasifying agent inlet (120) and the second gasifying agent inlet (170); the phenol water stripping tower is further provided with an oxygen-containing gas inlet (320) of the phenol water stripping tower and a sewage outlet (340).

[0055] In the above technical solution, the present application provides a two-stage coal gas producer which produces coal gas by using coal raw materials through a fixed bed gasification method, and the two-stage coal gas producer comprises a coal gas producer (100), a charging port (110) for adding coal raw materials into the coal gas producer is arranged at the top of the coal gas producer, a slag discharge port (130) is arranged at the bottom of the coal gas producer, an upper-stage coal gas outlet (140) for discharging upper-stage coal gas in the coal gas producer, a lower-stage coal gas outlet (150) for discharging lower-stage coal gas in the coal gas producer, and a second gasification agent inlet (170) and a first gasification agent inlet (120) for adding gasification agents into the coal gas producer are arranged at one side of the coal gas producer from top to bottom, wherein one or more lower-stage coal gas outlets can be arranged, and the number of the second gasification agent inlets can be one or more; a grate is arranged in the coal gas producer, the grate is arranged below the second gasification agent inlet (170) and is in communication with the first gasification agent inlet at the bottom, air distribution ports in communication with the reaction chamber of the coal gas producer (100) are arranged at the top of the grate, and the grate is further arranged in a multi-layer structure in a stacked manner from top to bottom, each layer is a cylinder coaxial with the coal gas producer, the diameters of the multi-layer structure decrease from bottom to top, air distribution ports are arranged on each layer, and the air volume of the air distribution ports decreases from top to bottom, so that the air volume of the grate decreases gradually from the center to the periphery, the air volume per unit area of the air distribution port on the top layer (the air distribution port in the middle) is not more than 200% of the average air volume per unit area, and the air volume per unit area of the air distribution port on the bottom layer (the air distribution port at the outermost position) is not less than 30% of the average air volume per unit area; the gas flow of the gasification agent supplemented through the first gasification agent inlet flows from the center to the outer layer, and the gas flow of the gasification agent supplemented through the second gasification agent inlet flows from the outer layer to the center, on the basis of the upward flow of the main gas flow, the lateral flow of the gas flow is increased, so that the contact and mixing of the gasification agent and the solid raw materials are strengthened, and the gas-solid reaction rate is improved.

[0056] The present application further comprises a phenol water stripping tower (300), a first phenol water inlet (310) of the phenol water stripping tower is arranged at the top of the phenol water stripping tower and is used for adding phenol water into the phenol water stripping tower (300), an oxygen-containing gas inlet (320) is arranged on the phenol water stripping tower (300) and is used for introducing oxygen-containing gas into the phenol water stripping tower (300), the phenol water in the phenol water stripping tower (300) is heated to become phenol water vapor, the phenol water vapor and the oxygen-containing gas form a mixed gas (gasification agent), the mixed gas is introduced into the coal gas producer (100) through a phenol water vapor outlet (330) of the phenol water stripping tower, the first gasification agent inlet (120) and the second gasification agent inlet, and a sewage discharge outlet (340) is arranged at the bottom of the phenol water stripping tower (300) and is used for discharging sewage.

[0057] The vaporization of phenolic water in the gasifier of this invention is partly due to the heat energy provided by the reboiler and partly due to the addition of oxygen-containing gas, which reduces the partial pressure and saturation temperature of water vapor. Compared with vaporization provided entirely by heat energy, this significantly reduces heat energy consumption. In the phenolic water stripping tower, the water vapor is in a saturated state. After entering the gasifier, the phenolic water vapor decomposes into small molecule gases such as CO and H2 at high temperatures. The oxygen-containing gas includes oxygen, air, and a mixture of oxygen and CO2. The phenolic water vapor mixes with the oxygen-containing gas to form a gasifying agent, which is fed into the gasifier for reaction through the first and second gasifying agent inlets. The water vapor in the gasifying agent has a high superheat, which avoids the condensation of water vapor carrying phenol into the ash residue and causing secondary pollution, thus completely solving the problem of wastewater treatment. The phenolic water stripping tower is equipped with an external wastewater discharge system to remove salts and solid impurities from the phenolic water, preventing scaling and clogging of the phenolic water stripping tower and reboiler.

[0058] In another technical solution, the two-stage gasifier further includes:

[0059] A reboiler (400) is provided with a gas outlet (420) of the reboiler, a phenol water inlet (430) of the reboiler connected to the phenol water outlet (380) of the phenol water stripping tower, a phenol water outlet (440) of the reboiler connected to the second phenol water inlet (390) of the phenol water stripping tower, and a gas inlet (410) of the reboiler connected to the lower gas outlet (150).

[0060] The gas cooler (600) has a gas inlet (610) on one side that is connected to the gas outlet (420) of the reboiler, and a lower gas outlet (620) on the other side.

[0061] In the above technical solution, a reboiler and a gas cooler are further provided. The phenol-water stripping tower (300) and the reboiler (400) are provided with two unidirectional phenol-water channels to form a phenol-water circulation: the phenol-water outlet of the phenol-water stripping tower is connected to the phenol-water inlet (430) of the reboiler, and the phenol-water outlet (440) of the reboiler is connected to the second phenol-water inlet (390) of the phenol-water stripping tower; the lower section gas outlet (150) of the gas generator is connected to the gas inlet (410) of the reboiler, and the gas outlet (420) of the reboiler is connected to the gas cooler. The gas inlet (610) is connected, and the gas cooler (600) is provided with a lower gas outlet (620). The heat of the lower gas is used to heat the phenol water and gasifying agent, and then it is further cooled down to the target temperature by the gas cooler before being discharged and sent to the downstream section. The heat of the lower gas is used to heat the phenol water in the reboiler. While recovering the sensible heat of the lower gas, the temperature of the lower gas is reduced, resulting in high thermal efficiency. The heat of the lower gas is used to heat the phenol water in the reboiler, fully recovering and utilizing the sensible heat of the lower gas, and improving thermal efficiency.

[0062] In another technical solution, the two-stage coal gas generator further comprises an electric tar precipitator (700), a coal gas intercooler (800) and a phenol water tank (900) connected in sequence; the coal gas inlet (710) of the electric tar precipitator is communicated with the upper-stage coal gas outlet (140), the coal gas outlet (720) of the electric tar precipitator is communicated with the coal gas inlet (810) of the coal gas intercooler, the cooling medium in the coal gas intercooler (800) is cold water, the upper-stage coal gas discharge outlet (820) is arranged in the middle of one side of the coal gas intercooler, and the lower part of the coal gas intercooler is provided with a phenol water outlet (830) of the coal gas intercooler communicated with the phenol water inlet (910) of the phenol water tank; the phenol water outlet (920) of the phenol water tank is communicated with the first phenol water inlet (310) of the phenol water stripping tower.

[0063] In the above technical solution, the electric tar precipitator (700), the coal gas intercooler (800) and the phenol water tank (900) for recycling and cooling the upper-stage coal gas are further arranged and connected in sequence; specifically, the upper-stage coal gas outlet (150) is communicated with the coal gas inlet (710) of the electric tar precipitator, the tar in the upper-stage coal gas is removed, then the upper-stage coal gas enters the coal gas intercooler (800) through the communicated coal gas outlet (720) of the electric tar precipitator and the coal gas inlet (810) of the coal gas intercooler, the upper-stage coal gas is cooled by the cooling water, the upper-stage coal gas cooled to the target temperature is discharged through the upper-stage coal gas discharge outlet (820) of the coal gas intercooler and sent to the downstream section; the condensate in the coal gas intercooler (800) is discharged to the phenol water tank (900) through the communicated phenol water outlet (830) of the coal gas intercooler and the phenol water inlet (910) of the phenol water tank, the phenol water after precipitation in the phenol water tank is flowed into the phenol water stripping tower through the phenol water outlet (920) of the phenol water tank and the first phenol water inlet (310) of the phenol water stripping tower, and the phenol water in the upper-stage coal gas is recycled.

[0064] In another technical solution, the two-stage coal gas generator, the phenol water outlet (380) of the phenol water stripping tower is provided with a phenol water pressurizing pump (500) communicated with the phenol water inlet (430) of the reboiler. By arranging the phenol water pressurizing pump (500), the pressure after the phenol water pressurizing pump is adjusted, so that the phenol water is still in the undersaturated state (full liquid state) after being heated in the reboiler, the phenol water is not easy to scale in the reboiler, and the phenol water is vaporized again (such as pressure reduction) after flowing into the phenol water stripping tower from the reboiler.

[0065] In another technical solution, the two-stage coal gas generator further comprises a superheater (200), a gas inlet (210) of the superheater is communicated with the lower-stage gas outlet (150), a gas outlet (220) of the superheater is communicated with a gas inlet (410) of the reboiler, a phenol-containing steam inlet (230) of the superheater is communicated with a phenol water steam outlet (330) of the phenol water stripping tower, and a phenol-containing steam outlet (240) of the superheater is communicated with the first gasifying agent inlet (120) and the second gasifying agent inlet (170). The superheater (200) is arranged to further heat the mixed gas (gasifying agent) discharged from the phenol water steam outlet (330) of the phenol water stripping tower by using the sensible heat of the lower-stage gas discharged from the lower-stage gas outlet (150), so that the gasifying agent discharged into the coal gas generator (100) through the first gasifying agent inlet (120) and the second gasifying agent inlet (170) is in a superheated state, the superheat degree of the water vapor in the gasifying agent is high, and the secondary pollution caused by the condensation of water vapor to carry phenol into the ash is avoided, which is conducive to completely solving the problem of wastewater treatment.

[0066] In another technical solution, the two-stage coal gas generator further comprises a cyclone separator (250), a gas inlet of the cyclone separator is arranged on one side and upper portion of the cyclone separator and is communicated with the lower-stage gas outlet (150), a gas outlet of the cyclone separator is arranged on the top of the cyclone separator and is communicated with the gas inlet (210) of the superheater, and a fly ash discharge outlet is arranged on the bottom of the cyclone separator. The cyclone separator (250) is used for purifying the lower-stage gas discharged from the lower-stage gas outlet (150) and removing fly ash particles in the lower-stage gas.

[0067] In another technical solution, the two-stage coal gas generator, the oxygen-containing gas inlet (320) of the phenol water stripping tower is communicated with an oxygen-containing gas outlet (1020) of a pressure swing adsorption device, one side of the pressure swing adsorption device (1000) is provided with a gas inlet (1010) communicated with external air, and a tail gas discharge outlet (1030) is arranged on the bottom of the pressure swing adsorption device. External air is communicated with the oxygen-containing gas inlet (1010) of the pressure swing adsorption device, the air is treated by the pressure swing adsorption device (1000) to increase the oxygen concentration, form oxygen-enriched air, reduce the nitrogen concentration in the gasifying agent, and increase the calorific value of the coal gas; the oxygen-enriched air enters the phenol water stripping tower through the oxygen-containing gas outlet (1020) of the pressure swing adsorption device and the oxygen-containing gas inlet (320) of the phenol water stripping tower.

[0068] In another technical solution, the two-stage coal gas generator, each second gasifying agent inlet (170) comprises a plurality of gasifying agent inlets uniformly and regularly arranged in a circumferential direction, and the gasifying agent discharge amount of all the gasifying agent inlets is not greater than the gasifying agent discharge amount of the first gasifying agent inlet. Fig. 2As shown, each second gasification agent inlet further comprises a plurality of (4) gasification agent in-holes (171-174) evenly spaced in the circumferential direction, and the total gasification agent in-flow of all the gasification agent in-holes is not greater than the total gasification agent in-flow of the first gasification agent in-holes, i.e. the total gasification agent in-flow of all the gasification agent in-holes is not greater than 50% of the total gasification agent in-flow in the coal gas generator.

[0069] The present application also provides a coal gasification method for a two-stage coal gas generator, comprising the following steps:

[0070] Step one, coal raw materials are added from the charging port (110) at the top of the coal gas generator, and gasification agents are added from the first gasification agent inlet and the second gasification agent inlet at the bottom of the two-stage coal gas generator, and the raw materials successively undergo drying, pyrolysis, gasification and combustion reactions, the temperature in the gasification and combustion reaction zone can reach 800-1100℃, unreacted ash is discharged from the ash discharge port (130) at the bottom of the coal gas generator, and the generated coal gas is discharged from the upper-stage coal gas outlet (140) and the lower-stage coal gas outlet (150), respectively;

[0071] Step two, the upper-stage coal gas flows into the electric tar catcher (700) to remove tar, then flows into the intercooler (800) to be cooled by cooling water, and the residual upper-stage coal gas is discharged through the upper-stage coal gas discharge port (820) of the intercooler, and the condensate of the upper-stage coal gas is discharged from the phenol water outlet (830) of the intercooler into the phenol water pool (900);

[0072] Step three, the phenol water after precipitation in the phenol water pool (900) flows into the phenol water stripping tower (300) for recycling, the phenol water in the phenol water stripping tower (300) is pressurized by the phenol water pressurizing pump (500) and then flows into the reboiler (400), the lower-stage coal gas is discharged through the lower-stage coal gas outlet (150) to the cyclone separator for purification by removing fly ash particles, then flows into the superheater to exchange heat with the gasification agent for the first time, and then flows into the reboiler to exchange heat with the phenol water for the second time, so as to fully recycle the sensible heat of the lower-stage coal gas; the phenol water in the reboiler (400) is heated by the heat source and then returns to the phenol water stripping tower (300), and the phenol water is vaporized to form phenol water vapor; at the same time, the oxygen-containing gas formed by processing air by the pressure swing adsorption device (1000) enters the phenol water stripping tower (300), and the mixed gas formed by the oxygen-containing gas and the phenol water vapor flows out from the phenol water vapor outlet (330) of the phenol water stripping tower, and the tail gas of the pressure swing adsorption device is discharged through the tail gas discharge port (1030); the gasification agent in the phenol water stripping tower is further heated (by the sensible heat of the lower-stage coal gas) to a superheated state by the superheater, and then flows into the reaction furnace of the coal gas generator through the first gasification agent inlet and the second gasification agent inlet, and the phenol vapor in the gasification agent is decomposed into small molecule gas in the high temperature environment of the coal gas furnace reaction furnace;

[0073] Step four, the lower section coal gas flowing into the reboiler is cooled further by two heat exchanges and then is discharged through the lower section coal gas outlet of the coal gas cooler.

[0074] The present application has the following advantages:

[0075] (1) The vaporization of phenol water is partly provided by the heat energy from the reboiler and partly by the oxygen-containing gas, which reduces the partial pressure and saturation temperature of water vapor. Compared with the complete vaporization provided by heat energy, the consumption of heat energy is greatly reduced.

[0076] (2) The water vapor in the phenol water stripping tower is in a saturated state, and the water vapor in the gasification agent mixed gas is further heated to a superheated state in the superheater before being sent into the coal gas furnace for reaction. The superheat degree of the water vapor in the gasification agent is high, which avoids the condensation of water vapor and the pollution caused by the phenol entering the ash residue, and completely solves the problem of waste water treatment.

[0077] (3) The heat of the lower section coal gas is used to heat the phenol water in the reboiler and to superheat the water vapor in the superheater. In the process of recovering the sensible heat of the lower section coal gas, the temperature of the lower section coal gas is reduced, and the thermal efficiency is high.

[0078] (4) The phenol water stripping tower is provided with an external sewage outlet to discharge the salts and solid impurities in the phenol water, avoiding the scaling and plugging of the phenol water stripping tower and the reboiler.

[0079] (5) By setting a phenol water pressurizing pump, the pressure after the phenol water pressurizing pump is adjusted, so that the phenol water is still in an undersaturated state (full liquid state) after being heated in the reboiler, and the phenol water is less likely to scale in the reboiler. The phenol water vaporizes again (such as pressure reduction) after flowing from the reboiler into the phenol water stripping tower.

[0080] (6) By opening the air distribution port on the grate, the ventilation volume per unit area of the cross section of the coal gas generation furnace reaction chamber decreases from the center to the periphery, and the second gasification agent inlet is provided to supplement the secondary gasification agent into the coal gas generation furnace reaction chamber. Near the grate, part of the gas flow flows from the center to the outer layer; near the secondary gasification agent inlet, part of the gas flow flows from the outer layer to the center. Therefore, on the basis of the main gas flow flowing upward, the lateral flow of the gas flow is increased, thereby strengthening the contact and mixing of the gasification agent and the solid raw material, and improving the gas-solid reaction rate.

[0081] (7) By setting the second gasification agent inlet to supplement the secondary gasification agent into the coal gas generation furnace reaction chamber, the oxygen concentration in the combustion and gasification reaction region is reduced, thereby reducing the maximum temperature in the combustion and gasification reaction region. Avoiding the risk of melting and slagging caused by the high oxygen concentration in the combustion and gasification reaction region and the maximum temperature exceeding the ash softening temperature of the solid material when all the gasification agents are supplemented at one time.

[0082] (8) By setting the second gasification agent inlet to supplement the secondary gasification agent to the coal gas producer reaction hearth, the height of the combustion and gasification reaction area can be increased, so that more raw materials can be gasified under the same coal gas producer diameter conditions, and the production capacity of the coal gas producer can be improved; or the residence time can be increased, the steam decomposition rate can be improved, and the amount of water vapor taken out of the furnace by the coal gas can be reduced, thereby reducing the amount of phenol-containing wastewater generated.

[0083] (9) The oxygen-containing gas can not only be directly used as air, but also can be used as oxygen-enriched air by setting a pressure swing adsorption device, so that the concentration of nitrogen in the coal gas is reduced, and the calorific value of the coal gas is improved.

[0084] The present application sets a second gasification agent inlet, which has the following advantages:

[0085] 1. By opening the air distribution port on the grate, the ventilation volume per unit area of the cross section of the coal gas producer reaction hearth decreases from the center to the periphery, and the second gasification agent inlet is set to supplement the secondary gasification agent to the coal gas producer reaction hearth. Near the grate, a part of the gas flow flows from the center to the outer layer; near the secondary gasification agent inlet, a part of the gas flow flows from the outer layer to the center. Therefore, on the basis of the main gas flow flowing upward, the lateral flow of the gas flow is increased, thereby strengthening the contact and mixing of the gasification agent and the solid raw material, and improving the gas-solid reaction rate.

[0086] 2. By setting the second gasification agent inlet to supplement the secondary gasification agent to the coal gas producer reaction hearth, the oxygen concentration in the combustion and gasification reaction area is reduced, thereby reducing the maximum temperature of the combustion and gasification reaction area. Avoiding the risk of melting and slagging caused by the high oxygen concentration in the combustion and gasification reaction area and the maximum temperature exceeding the ash softening temperature of the solid material caused by the one-time supplement of all gasification agents.

[0087] 3. By setting the second gasification agent inlet to supplement the secondary gasification agent to the coal gas producer reaction hearth, the height of the combustion and gasification reaction area can be increased, so that more raw materials can be gasified under the same coal gas producer diameter conditions, and the production capacity of the coal gas producer can be improved; or the residence time can be increased, the steam decomposition rate can be improved, and the amount of water vapor taken out of the furnace by the coal gas can be reduced, thereby reducing the amount of phenol-containing wastewater generated.

[0088] Further, the present application further heats the phenol water vapor to a superheated state in the superheater before being sent into the coal gas furnace reaction, and the water vapor in the gasification agent has a high superheat degree, which avoids the condensation of water vapor to bring phenol into the ash and form secondary pollution, and completely solves the problem of wastewater treatment; the present application sets a phenol water stripping tower, which produces phenol-containing steam through oxygen-containing gas stripping and heating by a reboiler, and has the following beneficial effects:

[0089] The vaporization of phenol water is partly provided by heat energy from the reboiler and partly provided by the oxygen-containing gas, which reduces the partial pressure of water vapor and the saturation temperature, thereby greatly reducing the consumption of heat energy compared with the vaporization provided by heat energy alone.

[0090] The phenol water stripping tower is provided with an external sewage outlet to discharge salts and solid impurities in the phenol water, thereby avoiding the fouling and plugging of the phenol water stripping tower and the reboiler.

[0091] The phenol water is still in an undersaturated state (fully liquid) after being heated in the reboiler by adjusting the pressure of the phenol water pressurizing pump, so that the phenol water is not easy to be fouled in the reboiler, and the phenol water is vaporized again (such as pressure reduction) after flowing from the reboiler into the phenol water stripping tower.

[0092] Embodiment 1

[0093] As shown in Fig. 1 , the present application provides a two-stage coal gas generator, which comprises:

[0094] The coal gas generator (100) is provided with a charging port (110) at the top and a slag discharge port (130) at the bottom; one side of the coal gas generator is provided with an upper-stage coal gas outlet (140), at least one lower-stage coal gas outlet (150), at least one second gasification agent inlet (170), and a first gasification agent inlet (120) from top to bottom; each second gasification agent inlet (170) comprises a plurality of gasification agent inlets uniformly spaced in the circumferential direction, and the total gasification agent inlet amount of all the gasification agent inlets is not more than the gasification agent inlet amount of the first gasification agent inlet;

[0095] The grate (160) is arranged in the coal gas generator (100) and below the second gasification agent inlet (170), the bottom of the grate (160) is in communication with the first gasification agent inlet (120), and the top is provided with an air distribution port in communication with the reaction furnace of the coal gas generator (100); the grate (160) is a multi-layer structure stacked from bottom to top, the diameter of the multi-layer structure decreases from bottom to top, each layer is provided with an air distribution port, and the ventilation amount of the air distribution ports decreases from top to bottom; the unit area ventilation amount of the air distribution port on the topmost structure is not more than 200% of the average unit area ventilation amount, and the unit area ventilation amount of the air distribution port on the bottommost structure is not less than 30% of the average unit area ventilation amount;

[0096] The reboiler (400) is provided with a reboiler coal gas outlet (420), a reboiler phenol water inlet (430), a reboiler phenol water outlet (440), and a reboiler coal gas inlet (410) in communication with the lower-stage coal gas outlet (150);

[0097] a phenol water stripping tower (300) provided with a second phenol water inlet (390) of the phenol water stripping tower in communication with a phenol water outlet (440) of the reboiler, a phenol water outlet (380) of the phenol water stripping tower in communication with a phenol water inlet (430) of the reboiler, a phenol water vapor outlet (330) of the phenol water stripping tower in communication with the first gasification agent inlet (120) and the second gasification agent inlet (170); the phenol water stripping tower is further provided with a oxygen-containing gas inlet (320) of the phenol water stripping tower and a sewage discharge outlet (340); a phenol water pressurizing pump (500) is arranged between the phenol water outlet (380) of the phenol water stripping tower and the phenol water inlet (430) of the reboiler;

[0098] a superheater (200) provided with a gas inlet (210) of the superheater in communication with the lower-stage gas outlet (150), a gas outlet (220) of the superheater in communication with a gas inlet (410) of the reboiler, a phenol-containing vapor inlet (230) of the superheater in communication with the phenol water vapor outlet (330) of the phenol water stripping tower, and a phenol-containing vapor outlet (240) of the superheater in communication with the first gasification agent inlet (120) and the second gasification agent inlet (170);

[0099] a cyclone separator (250) provided with a gas inlet of the cyclone separator on one side and upper portion in communication with the lower-stage gas outlet (150), a gas outlet of the cyclone separator on the top in communication with the gas inlet (210) of the superheater, and a fly ash discharge outlet on the bottom;

[0100] a gas cooler (600) provided with a gas inlet (610) of the gas cooler on one side in communication with the gas outlet (420) of the reboiler, and a lower-stage gas discharge outlet (620) on the other side;

[0101] an electric tar precipitator (700), a gas intercooler (800) and a phenol water pool (900); a gas inlet (710) of the electric tar precipitator is in communication with the upper-stage gas outlet (140), a gas outlet (720) of the electric tar precipitator is in communication with a gas inlet (810) of the gas intercooler, a cooling medium in the gas intercooler (800) is cold water, an upper-stage gas discharge outlet (820) is arranged on one side and middle portion of the gas intercooler, a phenol water outlet (830) of the gas intercooler in communication with a phenol water inlet (910) of the phenol water pool is arranged on the bottom, and a phenol water outlet (920) of the phenol water pool is in communication with a first phenol water inlet (310) of the phenol water stripping tower;

[0102] a pressure swing adsorption device (1000), the oxygen-containing gas inlet (320) of the phenol water stripping tower is in communication with an oxygen-containing gas outlet (1020) of the pressure swing adsorption device, a gas inlet (1010) in communication with external air is arranged on one side of the pressure swing adsorption device (1000), and a tail gas discharge outlet (1030) is arranged on the bottom.

[0103] The present application also provides a coal gasification method of a two-stage coal gasifier, which comprises the following steps:

[0104] Step one, coal raw materials are added from the charging port (110) at the top of the coal gasifier, and the gasifying agent is added from the first gasifying agent and second gasifying agent inlet at the bottom of the two-stage coal gasifier, the raw materials successively undergo drying, pyrolysis, gasification and combustion reactions, the temperature of the gasification and combustion reaction zone can reach 800-1100℃, the unreacted ash is discharged from the ash discharge port (130) at the bottom of the coal gasifier, and the generated coal gas is discharged from the upper-stage coal gas outlet (140) and the lower-stage coal gas outlet (150) respectively;

[0105] Step two, the upper-stage coal gas flows into the electric tar precipitator (700) to remove tar, then flows into the intercooler (800) to be cooled by cooling water, and the residual upper-stage coal gas is discharged through the upper-stage coal gas discharge port (820) of the intercooler, and the condensate of the upper-stage coal gas is discharged from the phenol water outlet (830) of the intercooler into the phenol water pool (900);

[0106] Step three, the phenol water after precipitation in the phenol water pool (900) flows into the phenol water stripping tower (300) for recycling, the phenol water in the phenol water stripping tower (300) is pressurized by the phenol water pressurizing pump (500) and then flows into the reboiler (400), the lower-stage coal gas is discharged through the lower-stage coal gas outlet (150) to the cyclone separator for purification by removing fly ash particles, then flows into the superheater to be once heated with the gasifying agent and then flows into the reboiler to be twice heated with the phenol water, so as to fully recycle the sensible heat of the lower-stage coal gas; the phenol water is heated by the heat source in the reboiler (400) and then returns to the phenol water stripping tower (300), and the phenol water is vaporized to form phenol water vapor; at the same time, the oxygen-containing gas formed by processing air by the pressure swing adsorption device (1000) enters the phenol water stripping tower (300), the mixed gas formed by the oxygen-containing gas and the phenol water vapor flows out from the phenol water vapor outlet (330) of the phenol water stripping tower, and the tail gas of the pressure swing adsorption device is discharged through the tail gas discharge port (1030); the gasifying agent in the phenol water stripping tower is further heated (heated by the sensible heat of the lower-stage coal gas) to a superheated state by the superheater, and then flows into the reaction furnace of the coal gasifier through the first gasifying agent inlet and the second gasifying agent inlet, and the phenol vapor in the gasifying agent is decomposed into small molecule gas in the high temperature environment of the coal gas furnace reaction furnace;

[0107] Step four, the lower-stage coal gas flowing into the reboiler is subjected to twice heat exchange, then is further cooled in the coal gas cooler, and then is discharged through the lower-stage coal gas discharge port of the coal gas cooler.

[0108] In the present embodiment 1, the ratio of air to water vapor in the mixed gas of the phenol water stripping tower is 80%, 20% (the phenol content is ignored), the pressure of the phenol water stripping tower is 0.12 MPa, and therefore the partial pressure of water vapor in the mixed gas is 0.024 MPa, and the temperature of the mixed gas is 64.1°C. The heat energy required for heating the phenol water is the energy required for heating the phenol water from room temperature (enthalpy 84.03 kJ / kg) to 64.1°C (enthalpy 2615.88 kJ / kg), which is 2615.88 kJ / kg - 84.03 kJ / kg = 2531.85 kJ / kg.

[0109] The coal gasifier has a diameter of 3200 mm, the gasifying agent is fed in from the first gasifying agent inlet at 70% and from the second gasifying agent inlet at 30%, the height of the combustion and gasification reaction zone reaches 2 m, the steam decomposition rate is 80%, and the raw material processing capacity is 3 t / h.

[0110] The existing coal gas generator and coal gasification method are selected as the comparative examples, such as Comparative Example 2 (two-stage coal gas generator coal gas purification treatment device and process with phenol water treatment CN103589461A). In the comparative examples, the phenol water is heated to saturated water vapor and then mixed with air, the pressure of the saturated water vapor after heating the phenol water is 0.12 MPa (the same as the pressure of the embodiment), and the temperature of the saturated water vapor is 104.8°C. Therefore, the heat energy required for heating the phenol water is the energy required for heating the phenol water from room temperature (enthalpy 84.03 kJ / kg) to 104.8°C (enthalpy 2683.06 kJ / kg), which is 2683.06 kJ / kg - 84.03 kJ / kg = 2599.03 kJ / kg. The coal gasifier has a diameter of 3200 mm, the gasifying agent is fed in from the gasifying agent inlet, the height of the combustion and gasification reaction zone is only 1 m, the steam decomposition rate is 30%, and the raw material processing capacity is 2.4 t / h.

[0111] As can be seen from the embodiment 1 and the comparative examples, the heat energy consumption of the embodiment 1 is lower than that of the comparative examples. The vaporization of the phenol water is partly provided by the heat energy from the reboiler and partly provided by the decrease of the partial pressure of water vapor and the saturation temperature after the addition of the oxygen-containing gas. Compared with the vaporization provided completely by heat energy, the heat energy consumption is greatly reduced. The embodiment can increase the height of the combustion and gasification reaction zone by setting the second gasifying agent inlet to supplement the secondary gasifying agent to the reaction hearth of the coal gas generator, so that more raw materials can be gasified and the production capacity of the coal gas generator can be improved under the condition of the same diameter of the coal gas generator; or the residence time can be increased, the steam decomposition rate can be improved, and the amount of water vapor taken out of the furnace by the coal gas can be reduced, so that the amount of phenol-containing wastewater generated can be reduced.

[0112] The number of devices and the processing scale described herein are used to simplify the description of the present application. The application, modification and change of the present application are obvious to those skilled in the art.

[0113] While embodiments of the application have been disclosed in connection with the above specification and drawings this description is not intended to limit the scope of the application and many modifications, enhancements, alternatives, and variations will become apparent to those skilled in the art from this disclosure. Accordingly, it is expressly intended that the description should not limit the application as claimed but rather the only limitation placed on the scope of the application be the scope of the claims as set out below and equivalents thereof.

Claims

1. A two-stage gasifier, characterized in that, include: A gas generator (100) is provided with a feeding port (110) at the top and a slag discharge port (130) at the bottom; one side of the gas generator is provided with an upper gas outlet (140), at least one lower gas outlet (150), at least one second gasifying agent inlet (170), and a first gasifying agent inlet (120) from top to bottom. A grate (160) is disposed inside the gasifier (100) and located below the second gasifying agent inlet (170). The bottom of the grate (160) is connected to the first gasifying agent inlet (120), and the top is provided with an air distribution port connected to the reaction furnace of the gasifier (100). The grate is a multi-layer structure stacked from bottom to top, with the diameter of the multi-layer structure decreasing from bottom to top. Each layer of the structure is provided with an air distribution port, and the ventilation volume of the multi-layer air distribution ports decreases from top to bottom. A phenol-water stripping tower (300) is provided with a phenol-water vapor outlet (330) that is connected to the first gasifying agent inlet (120) and the second gasifying agent inlet (170); the phenol-water stripping tower is also provided with an oxygen-containing gas inlet (320) and a wastewater outlet (340). A reboiler (400) is provided with a gas outlet (420) of the reboiler, a phenol water inlet (430) of the reboiler connected to the phenol water outlet (380) of the phenol water stripping tower, a phenol water outlet (440) of the reboiler connected to the second phenol water inlet (390) of the phenol water stripping tower, and a gas inlet (410) of the reboiler connected to the lower gas outlet (150). A gas cooler (600) has a gas inlet (610) on one side that is connected to the gas outlet (420) of the reboiler, and a lower gas outlet (620) on the other side. It also includes an electrostatic precipitator (700), a gas intercooler (800), and a phenol water tank (900) connected in sequence; the gas inlet (710) of the electrostatic precipitator is connected to the upper gas outlet (140), the gas outlet (720) of the electrostatic precipitator is connected to the gas inlet (810) of the gas intercooler, the cooling medium in the gas intercooler (800) is cold water, the upper gas outlet (820) is provided in the middle of one side of the gas intercooler, and the phenol water outlet (830) of the gas intercooler is provided in the lower part, which is connected to the phenol water inlet (910) of the phenol water tank; the phenol water outlet (920) of the phenol water tank is connected to the first phenol water inlet (310) of the phenol water stripping tower.

2. The two-stage gasifier as described in claim 1, characterized in that, The ventilation volume per unit area of ​​the air vents on the topmost structure shall not exceed 200% of the average ventilation volume per unit area, and the ventilation volume per unit area of ​​the air vents on the bottommost structure shall not be less than 30% of the average ventilation volume per unit area.

3. The two-stage gasifier as described in claim 1, characterized in that, A phenol water pressurization pump (500) is provided between the phenol water outlet (380) of the phenol water stripping tower and the phenol water inlet (430) of the reboiler.

4. The two-stage gasifier as described in claim 3, characterized in that, It also includes a superheater (200), the gas inlet (210) of the superheater is connected to the lower gas outlet (150), the gas outlet (220) of the superheater is connected to the gas inlet (410) of the reboiler, the phenol-containing steam inlet (230) of the superheater is connected to the phenol-water steam outlet (330) of the phenol-water stripping tower, and the phenol-containing steam outlet (240) of the superheater is connected to the first gasifying agent inlet (120) and the second gasifying agent inlet (170).

5. The two-stage gasifier as described in claim 4, characterized in that, It also includes a cyclone separator (250), which has a gas inlet on one side connected to the lower gas outlet (150), a gas outlet at the top connected to the gas inlet (210) of the superheater, and a fly ash discharge outlet at the bottom.

6. The two-stage gasifier as described in claim 5, characterized in that, The oxygen-containing gas inlet (320) of the phenol-water stripping tower is connected to the oxygen-containing gas outlet (1020) of the pressure swing adsorption device. The pressure swing adsorption device (1000) has a gas inlet (1010) on one side that is connected to the outside air and a tail gas outlet (1030) at the bottom.

7. The two-stage gasifier as described in claim 6, characterized in that, Each second vaporizer inlet (170) includes a plurality of vaporizer inlets evenly spaced along the circumferential direction, and the vaporizer discharge amount of all vaporizer inlets is not greater than the vaporizer discharge amount of the first vaporizer inlet.

8. A method for gasifying coal in a two-stage coal gasifier as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Coal raw material is added from the top feed port (110) of the gasifier, and gasifying agent is added from the first gasifying agent inlet at the bottom of the two-stage gasifier. The raw material undergoes drying, pyrolysis, gasification and combustion reactions in sequence. The temperature of the gasification and combustion reaction zone can reach 800-1100℃. Unreacted ash is discharged from the bottom ash discharge port (130) of the gasifier. The generated gas is discharged from the upper gas outlet (140) and the lower gas outlet (150) respectively. Step 2: The upper section of gas flows into the electrostatic precipitator (700) to remove tar, and then flows into the gas intercooler (800) to be cooled by cooling water. The remaining upper section gas is discharged through the upper section gas outlet (820) of the intercooler. The condensate of the upper section gas is discharged into the phenol water tank (900) through the phenol water outlet (830) of the intercooler. Step 3: After sedimentation in the phenol water tank (900), the phenol water flows into the phenol water stripping tower (300). The phenol water in the stripping tower is pressurized by the phenol water pressurization pump (500) and then flows into the reboiler (400). The lower-stage gas is discharged through the lower-stage gas outlet (150) to the cyclone separator for fly ash particle removal and purification. It then enters the superheater for primary heat exchange with the gasifying agent and flows into the reboiler for secondary heat exchange with the phenol water, fully recovering and utilizing the sensible heat of the lower-stage gas. The phenol water is heated by the heat source in the reboiler (400) and then returns to the phenol water stripping tower (300), where it vaporizes to form phenol water vapor. Simultaneously... After the air is treated by the pressure swing adsorption device (1000), the oxygen-containing gas enters the phenol-water stripping tower (300). The mixture of oxygen-containing gas and phenol-water vapor flows out from the phenol-water vapor outlet (330) of the phenol-water stripping tower, passes through the superheater, and flows into the gasifier reactor through the first gasifying agent inlet and the second gasifying agent inlet. The phenol vapor in the gasifying agent decomposes into small molecule gas in the high temperature environment of the gasifier reactor. Step four: The lower section gas flowing into the reboiler undergoes two heat exchanges and is discharged to the gas cooler for further cooling. Then it is discharged through the lower section gas outlet of the gas cooler.

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