A supercritical water gasification system and method for energy recovery and zero wastewater discharge

Abstract

A supercritical water gasification system with energy recovery and zero wastewater discharge includes: a supercritical water gasification hydrogen production unit, including a quality-improving slurry tank, a high-pressure delivery pump, a slurry preheater and an internal heat type gasification reactor; a gas separation unit, including a thermostat, a pressure regulator and a high-pressure gas separator; a waste treatment unit, including a high-pressure gas separator, a waste booster pump, a supplementary heat device and a supercritical water oxidation reactor; a residual energy recycling unit, including a supercritical water oxidation reactor, a regenerator, a pressure energy recovery device, a pressure regulator, a high-pressure three-phase separator and a flow distributor. The present invention can improve the slurrying rate of coal and thus increase its gasification rate and hydrogen production rate, while making full use of the remaining heat energy, pressure energy and water resources of the system, reducing the energy consumption and operating cost of the system, improving the economy of the system, achieving zero pollutant discharge, and contributing to the promotion and application of supercritical water gasification hydrogen production technology.

Description

Technical Field

[0001] The invention belongs to the field of energy and chemical technology, and particularly relates to a supercritical water gasification system and method for energy recovery and zero wastewater discharge. Background Art

[0002] With the increasing impact of the massive consumption of fossil energy on the environment and the requirement for sustainable development, the development and utilization of renewable energy sources have received increasing attention. Hydrogen energy not only has high combustion calorific value, zero emissions, and light weight, but can also be converted into a variety of energy sources. Therefore, it has received widespread attention as a recyclable green energy. At present, industrial large-scale hydrogen production is based on traditional gasification furnace technology that uses mineral energy such as natural gas and coal as raw materials. It has the disadvantages of low gasification efficiency, high energy consumption, and high carbon emission intensity. Other new hydrogen production routes include electrolysis and photolysis using solar energy, and the cost of hydrogen production is still relatively high. SCWG has unique advantages over other biomass thermochemical hydrogen production technologies. It can directly gasify wet materials with high water content, does not require a high-energy drying process, and does not cause intermediate pollution.

[0003] Supercritical water gasification (SCWG) is a new hydrogen production technology proposed by Modell of MIT in the mid-1970s. Supercritical water (SCW) refers to water with special properties whose temperature and pressure are higher than its critical point (temperature 374.15℃, pressure 22.12MPa). SCWG uses the powerful dissolving ability of supercritical water to dissolve various organic substances to generate high-density, low-viscosity liquids, and then quickly gasifies them under high-temperature and high-pressure reaction conditions to generate a hydrogen-rich mixed gas.

[0004] However, after a lot of research and development, the supercritical water gasification hydrogen production system still has the following three problems: First, different coals have different water contents due to different coal qualities, and it is difficult to slurry coal with high water content; Second, the existing supercritical water gasification hydrogen production system directly cools down and depressurizes after the reaction to enter the gas separation process, which does not fully utilize thermal energy and pressure energy, resulting in a large amount of energy loss and waste; Third, the supercritical water gasification hydrogen production reaction cannot completely degrade and transform organic matter and produces a large amount of slag-containing wastewater. The N, S and heavy metal elements in the product cannot be completely harmless, which will cause great harm to the environment and cause a large amount of water resources. The above problems cause high energy consumption and low economy of supercritical water gasification hydrogen production technology. Therefore, on this basis, our team has developed a supercritical water gasification hydrogen production process integrating supercritical water oxidation technology, which can well solve the problem of environmental hazards caused by gasification products. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art and solve the above-mentioned problems reasonably and efficiently, the purpose of the present invention is to provide a supercritical water gasification system and method with energy recovery and zero wastewater discharge, which can improve the coal slurry rate and thus increase its gasification rate and hydrogen production rate, while reducing the system energy consumption and operating costs, improving the system economy, achieving zero pollutant emissions, and contributing to the promotion and application of supercritical water gasification hydrogen production technology.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A supercritical water gasification system with energy recovery and zero wastewater discharge, comprising:

[0008] The supercritical water gasification hydrogen production unit comprises a quality-improving slurry conditioning tank 1, which has three inlets, namely a high-pressure recycled water inlet, a gasification raw material inlet and a water replenishment inlet, and its outlet is connected to the cold side inlet of a slurry preheater 3 through a slurry high-pressure delivery pump 2, and the cold side outlet of the slurry preheater 3 is connected to the inlet of an internal heating type gasification reactor 4;

[0009] The gas separation unit comprises a thermostat 5, a hot side inlet of the thermostat 5 is connected to the outlet of the internal heat type gasification reactor 4, a hot side outlet is connected to the inlet of a first pressure regulator 6, and an outlet of the first pressure regulator 6 is connected to the inlet of a high pressure gas separator 7;

[0010] The waste treatment unit includes a reheater 9, a slurry outlet of a high-pressure gas separator 7 is connected to a cold side inlet of the reheater 9 through a waste booster pump 8, and the cold side outlet of the reheater 9 is connected to an inlet of a supercritical water oxidation reactor 10;

[0011] The waste energy recycling unit comprises a regenerator 11, wherein the hot side inlet of the regenerator 11 is connected to the outlet of the supercritical water oxidation reactor 10, and the hot side outlet is connected to the inlet of a pressure energy recovery device 12, and the outlet of the pressure energy recovery device 12 is connected to the inlet of a high-pressure three-phase separator 14 through a second pressure regulator 13, and the liquid phase outlet of the high-pressure three-phase separator 14 is connected to the high-pressure recycled water inlet of the upgrading and slurry mixing tank 1; the cold side inlet of the regenerator 11 is connected to the cold side outlet of the thermostat 5, and the cold side inlet of the thermostat 5 is the inlet of high-pressure cooling water, and the cold side outlet of the regenerator 11 is connected to the hot side inlet of the supplementary heat device 9, and the hot side outlet of the supplementary heat device 9 is connected to the inlet of a flow distributor 15, and the flow distributor 15 has two outlets, and one of the outlets is connected to the replenishing water inlet of the upgrading and slurry mixing tank 1 through a valve V1.

[0012] The upgrading and slurry mixing tank 1 maintains high temperature and high pressure hydrothermal upgrading operation conditions.

[0013] The upgrading and slurry mixing tank 1 is provided with an agitator in the interior thereof, and the agitator is in the form of a paddle type, a turbine type, an anchor type or a screw belt type.

[0014] The high-pressure gas separator 7 is a high-pressure and high-temperature container, whose inlet is the gasification product after temperature and pressure regulation, and whose outlet is the gas phase product and the slurry after gas phase separation; the high-pressure three-phase separator 14 is a high-pressure and high-temperature container, whose inlet is the product after supercritical water oxidation treatment, and whose outlet is the gas phase product, solid phase product and liquid phase product. The slurry preheater 3, thermostat 5, supplementary heat device 9, and regenerator 11 all use heat exchangers with high pressure on both sides. The slurry high-pressure delivery pump 2 and the slurry booster pump 8 both use solid-containing high-pressure pumps. The first pressure regulator 6 and the second pressure regulator 13 use a single or combined device of a pressure reducing valve, a back pressure valve and a throttling element. The pressure energy recovery device 12 uses a hydraulic turbine or a piston-type pressure energy recovery machine.

[0015] Another outlet of the flow distributor 15 is used as an outlet for other industrial applications, and a valve V2 is arranged on the pipeline of the outlet.

[0016] The present invention also provides a method of a supercritical water gasification system based on the energy recovery and zero wastewater discharge, comprising:

[0017] Supercritical water gasification hydrogen production: The upgrading and slurry mixing tank 1 maintains high temperature and high pressure hydrothermal upgrading conditions, so that the raw materials and water form a uniform slurry therein, and the slurry high-pressure delivery pump 2 pressurizes the slurry to a supercritical pressure, and after being heated to a supercritical temperature by a slurry preheater 3, it is sent to an internal heat type gasification reactor 4 to start a supercritical water gasification hydrogen production reaction;

[0018] Gas separation: The three-phase product obtained after the supercritical water gasification hydrogen production reaction is adjusted to the optimal separation condition by using the thermostat 5 and the first pressure regulator 6, and then the mixed gas is separated and discharged through the high-pressure gas separator 7;

[0019] Waste treatment: The high-temperature and high-pressure waste liquid obtained from the high-pressure gas separator 7 is pressurized to a supercritical pressure by a waste booster pump 8, and then heated to a supercritical temperature by a supplementary heater 9, and then mixed with an oxidant and entered into a supercritical water oxidation reactor 10 for a supercritical water oxidation reaction, thereby obtaining harmless products mainly composed of H2O, CO2 and inorganic salts, thereby achieving a thorough treatment of the gasified waste;

[0020] Residual energy is recycled. The fluid obtained from the supercritical water oxidation reaction is cooled in the regenerator 11 by heating the high-pressure and low-temperature water from the thermostat 5, and then the excess pressure energy is recovered by the pressure energy recovery device 12. The pressure is accurately controlled and adjusted by the second pressure regulator 13, and finally enters the high-pressure three-phase separator 14 to separate and discharge the gasification products and solid phase residues. The obtained liquid phase is injected into the upgrading and slurrying tank 1 as recycled water for hydrothermal upgrading and slurrying of the gasified raw materials; the high-pressure cooling water passing through the regenerator 11 is heated to above 450°C, and then enters the supplementary heat device 9 to release heat to the gasified waste material to make it reach the supercritical temperature. The fluid out of the supplementary heat device 9 is divided into two paths by the flow distributor 15, one path enters the upgrading and slurrying tank 1 as slurrying water for the gasified raw materials, and most of the remaining fluid is discharged as heat source fluid for other industrial uses.

[0021] In the upgrading and slurry adjustment tank 1, the gasified slurry is mixed with the high-pressure recycled water thoroughly treated by supercritical water oxidation and the high-pressure make-up water heated by the waste heat of the system to reach the target temperature after heat exchange, and the hydrothermal upgrading and slurry adjustment operations of the gasified raw material are completed.

[0022] The waste heat of the reaction fluid after thorough harmless treatment in the supercritical water oxidation reactor 10 is recycled in two stages. The first stage is to heat the high-pressure cooling water from the thermostat 5 and then cool it down. The second stage is to enter the upgrading and slurry conditioning tank 1 and be recycled as the conditioning water for upgrading and slurry conditioning of the gasification raw material.

[0023] The cooling water has two-stage heating and two-stage recycling, wherein the first-stage heating is that the cooling water passes through the thermostat 5 to cool and regulate the fluid after the supercritical water gasification hydrogen production reaction to control its separation temperature; the second-stage heating is that the fluid is heated to above 450°C after the supercritical water oxidation reaction in the regenerator 11; the first-stage recycling is to supplement heat for the gasified waste after gas separation in the supplementary heat device 9 to make its temperature reach the supercritical temperature>374°C, and the second-stage recycling is to be used as make-up water in the quality improvement slurry tank 1 and other industrial hot water after leaving the supplementary heat device 9.

[0024] The gasification product of the supercritical water gasification hydrogen production uses pressure energy to separate gas in the high-pressure gas separator 7, completing the first stage of pressure energy utilization; the fluid that completes the first stage of waste heat recovery after supercritical water treatment completes the second stage of pressure energy utilization in the pressure energy recovery device 12; the gas and solid phase residue are separated by pressure energy in the high-pressure three-phase separator 14, completing the third stage of pressure energy utilization; the separated liquid phase enters the quality-improving slurry mixing tank 1 for reuse as mixing water, completing the fourth stage of pressure energy utilization; the high-pressure cooling water after the second stage of waste heat utilization enters the quality-improving slurry mixing tank 1 as mixing makeup water, completing the fifth stage of pressure energy utilization.

[0025] Compared with the prior art, the present invention integrates hydrothermal liquefaction / quality improvement technology into the supercritical water gasification hydrogen production reaction, changes the coal quality characteristics, improves the coal slurryability, and improves the coal gasification efficiency; multi-stage and circular utilization of the heat energy and pressure energy in the system, does not require the introduction of external heat, and does not require additional pressure increase and pressure reduction operations, thereby achieving the self-heating balance and pressure balance of the supercritical water gasification hydrogen production system, and reducing the energy consumption of the system; combined with supercritical water oxidation technology, the waste after gasification is thoroughly and harmlessly removed, so that the effluent after the reaction meets the standards and can be used as the blending water for coal slurrying, thereby achieving the circular utilization of water resources and reducing the energy consumption of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0027] Among them, 1-quality upgrading and slurry adjustment tank, 2-slurry high-pressure delivery pump, 3-slurry preheater, 4-internal heating gasification reactor, 5-temperature regulator, 6-first pressure regulator, 7-high-pressure gas separator, 8-waste booster pump, 9-supplementary heat device, 10-supercritical water oxidation reactor, 11-regenerator, 12-pressure energy recovery device, 13-second pressure regulator, 14-high-pressure three-phase separator, 15-flow distributor. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0031] refer to Figure 1The present invention provides a supercritical water gasification system with energy recovery and zero wastewater discharge, comprising a supercritical water gasification hydrogen production unit, a gas separation unit, a waste treatment unit, and a residual energy recovery unit, wherein:

[0032] The supercritical water gasification hydrogen production unit includes a quality upgrading and slurry conditioning tank 1, a slurry high-pressure delivery pump 2, a slurry preheater 3 and an internal heating type gasification reactor 4; wherein in the quality upgrading and slurry conditioning tank 1, a high-temperature and high-pressure hydrothermal quality upgrading operation condition is maintained, and an agitator is arranged in the tank, and the agitator can be selected from but not limited to a paddle type, a turbine type, an anchor type, and a screw type. The quality upgrading and slurry conditioning tank 1 has three inlets, namely a high-pressure recycled water inlet, a gasification raw material inlet, and a water replenishment inlet, and its outlet is connected to the inlet of the slurry high-pressure delivery pump 2, and the outlet of the slurry high-pressure delivery pump 2 is connected to the cold side inlet of the slurry preheater 3, and the cold side outlet of the slurry preheater 3 is connected to the inlet of the internal heating type gasification reactor 4, and its outlet is connected to the inlet of the gas separation unit;

[0033] The gas separation unit includes a thermostat 5, a first pressure regulator 6 and a high-pressure gas separator 7; wherein the hot side inlet of the thermostat 5 is connected to the outlet of the internal heat type gasification reactor 4, and the hot side outlet thereof is connected to the inlet of the first pressure regulator 6, and the outlet of the first pressure regulator 6 is connected to the inlet of the high-pressure gas separator 7. The high-pressure gas separator 7 has two outlets, one is the outlet of the separated gas product, and the other is the outlet of the slurry after gas separation, which are connected to the inlet of the waste treatment unit;

[0034] The waste treatment unit includes a waste booster pump 8, a reheater 9, and a supercritical water oxidation reactor 10; wherein the inlet of the waste booster pump 8 is connected to the outlet of the slurry after gas separation in the high-pressure gas separator 7, and the outlet is connected to the cold side inlet of the reheater 9, the cold side outlet of the reheater 9 is connected to the inlet of the supercritical water oxidation reactor 10, and the outlet of the supercritical water oxidation reactor 10 is connected to the inlet of the residual energy recovery unit;

[0035] The waste energy recovery unit includes a regenerator 11, a supplementary heat device 9, a pressure energy recovery device 12, a second pressure regulator 13, a high-pressure three-phase separator 14, a flow distributor 15 and a quality-improving slurry tank 1; wherein the hot side inlet of the regenerator 11 is connected to the outlet of the supercritical water oxidation reactor 10, and its outlet is connected to the inlet of the pressure energy recovery device 12, the outlet of the pressure energy recovery device 12 is connected to the inlet of the second pressure regulator 13, and the outlet of the second pressure regulator 13 is connected to the inlet of the high-pressure three-phase separator 14, and the high-pressure three-phase separator 14 has three outlets, namely, the outlet of the separated gas phase product, the outlet of the separated solid phase product, and the outlet of the separated gas phase product. The residue outlet and the liquid phase outlet after three-phase separation are connected to the inlet of the high-pressure recycled water of the upgrading and pulping tank 1; the cold side inlet of the regenerator 11 is connected to the cold side outlet of the thermostat 5, and the cold side inlet of the thermostat 5 is the inlet of the high-pressure cooling water. The cold side outlet of the regenerator 11 is connected to the hot side inlet of the supplementary heat device 9, and the hot side outlet of the supplementary heat device 9 is connected to the inlet of the flow distributor 15. The flow distributor 15 has two outlets, one of which is connected to the make-up water inlet of the upgrading and pulping tank 1, and the other is used as an outlet for other industrial applications. Valves V1 and V2 are respectively arranged on the two outlet pipelines.

[0036] In the above structure:

[0037] The high-pressure gas separator 7 is a high-pressure and high-temperature container, the inlet of which is the gasification product after temperature and pressure adjustment, and the outlet of which is the gas phase product and the slurry after gas phase separation;

[0038] The high-pressure three-phase separator 14 is a high-pressure and high-temperature container, the inlet of which is the product after the supercritical water oxidation treatment, and the outlet of which is the gas phase product, the solid phase product and the liquid phase product;

[0039] The slurry preheater 3, the thermostat 5, the supplementary heat device 9 and the regenerator 11 all use heat exchangers with high pressure on both sides, which may be, but not limited to, shell-and-tube heat exchangers.

[0040] The slurry high-pressure delivery pump 2 and the slurry booster pump 8 both adopt solid-containing high-pressure pumps, which may be, but are not limited to, high-pressure diaphragm pumps.

[0041] The first pressure regulator 6 and the second pressure regulator 13 may adopt single or combined devices such as but not limited to pressure reducing valves, back pressure valves, throttling elements, etc.

[0042] The pressure energy recovery device 12 may be selected from but is not limited to a hydraulic turbine or a piston type pressure energy recovery machine.

[0043] According to the above system structure, the supercritical water gasification reaction method of the present invention is implemented in the following manner:

[0044] Supercritical water gasification hydrogen production: wherein the upgrading and slurry adjustment tank 1 maintains high temperature and high pressure hydrothermal upgrading conditions, so that the raw material and water form a uniform slurry in the upgrading and slurry adjustment tank 1, and the upgrading and slurry adjustment operations of the gasified raw material are completed; the slurry high-pressure delivery pump 2 is connected to it to increase the slurry pressure to the supercritical pressure and transport it to the subsequent system; the slurry preheater 3 is connected to the slurry high-pressure delivery pump 2, and after preheating the high-pressure incoming material to the supercritical temperature, the supercritical water gasification hydrogen production reaction is started in the internal heat type gasification reactor 4;

[0045] Gas separation: The thermostat 5 and the pressure regulator 6 adjust the three-phase products after the reaction to the best separation conditions, and then the mixed gases such as H2, CO2, CH4, CO, etc. are separated through the high-pressure gas separator 7, and the remaining liquid-solid two-phase products enter the subsequent waste treatment unit;

[0046] Waste treatment: The high-temperature and high-pressure waste liquid after gas separation is pressurized to supercritical pressure by the waste booster pump 8, then enters the supplementary heat device 9 to absorb heat and heat to supercritical temperature, and then is mixed with the oxidant and enters the supercritical water oxidation reactor 10 to be rapidly oxidized and degraded into harmless products such as H2O, CO2 and inorganic salts to achieve complete treatment of gasified waste;

[0047] Residual energy recycling: After the supercritical water oxidation reaction, the fluid leaves the supercritical water oxidation reactor 10 and enters the regenerator 11 to cool down by heating the high-pressure and low-temperature water from the thermostat 5, then enters the pressure energy recovery device 12 to recover the excess pressure energy, and accurately controls and adjusts the pressure through the second pressure regulator 13, and finally enters the high-pressure solid-liquid separator 14 to inject the liquid phase after the gasification product and solid phase residue are separated and discharged as recycling water into the upgrading and slurrying tank 1 for hydrothermal upgrading and slurrying of the gasified raw materials; the high-pressure cooling water passing through the regenerator 11 is heated to above 450°C, and then enters the supplementary heat device 9 to release heat to the gasified waste material to make it reach a supercritical temperature>374°C; after passing through the supplementary heat device 9, the fluid is divided into two paths by the flow distributor 15, one path enters the upgrading and slurrying tank 1 as slurrying water for the gasified raw materials, and most of the remaining fluid is discharged as heat source fluid for other industrial uses.

[0048] In the present invention:

[0049] High-pressure cooling water can achieve two-stage heating and two-stage waste heat utilization. The process includes: the inlet of the thermostat 5 is the high-pressure cooling water inlet, and its outlet is connected to the cold side inlet of the regenerator 11. The first-stage heating is that the cooling water passes through the thermostat 5 to cool and adjust the temperature of the fluid after the supercritical water gasification hydrogen production reaction to control its separation temperature; the second-stage heating is that the fluid is heated to above 450°C after the supercritical water oxidation reaction in the regenerator 11; the cold side outlet of the regenerator 11 is connected to the hot side inlet of the supplementary heat 9, and the hot side outlet of the supplementary heat 9 is connected to the hot side outlet of the supplementary heat 9. The inlet of the flow distributor 15 is connected, and the primary reuse is to supplement heat for the gasified waste after gas separation in the supplementary heat device 9 to make its temperature reach the supercritical temperature>374°C; the outlet 1 of the flow distributor is connected to the water replenishment inlet of the quality improvement and slurry mixing tank, and the outlet 2 is an outlet for other industrial uses. Valves V1 and V2 are respectively arranged on the two outlet pipelines, and the waste heat is used for slurry mixing and water replenishment of the gasified raw materials and other industrial uses, that is, the secondary reuse is used as the water replenishment in the quality improvement and slurry mixing tank 1 and other industrial hot water after leaving the supplementary heat device 9.

[0050] The pressure energy can be utilized in five stages, and the process includes: the outlet of the first pressure regulator 6 is connected to the inlet of the high-pressure gas separator 7, and the gasification product of supercritical water gasification hydrogen production is separated into gas by pressure energy in the high-pressure gas separator 7, completing the first stage of pressure energy utilization; the hot side outlet of the regenerator 11 is connected to the inlet of the pressure energy recovery device 12, and the outlet of the pressure energy recovery device 12 is connected to the inlet of the second pressure regulator 13, and the pressure energy is recovered by the recovery device 12, and the fluid that completes the first stage of waste heat recovery after supercritical water treatment completes the second stage of pressure energy utilization in the pressure energy recovery device 12; the outlet of the second pressure regulator 13 is connected to the high-pressure three-phase separator 14. The inlet of the high-pressure three-phase separator 14 is connected to separate the gas and solid residue by pressure energy, completing the third stage of pressure energy utilization; the liquid phase outlet of the high-pressure three-phase separator 14 is connected to the inlet of the high-pressure reuse water of the upgrading and slurry mixing tank 4, and high-pressure reuse is carried out directly without reducing the pressure. The separated liquid phase enters the upgrading and slurry mixing tank 1 as the deployment water reuse, completing the fourth stage of pressure energy utilization; the high-pressure water outlet 1 of the flow distributor 15 is connected to the make-up water inlet of the upgrading and slurry mixing tank 1, and high-pressure reuse is carried out directly without reducing the pressure. The high-pressure cooling water after the second stage of waste heat utilization enters the upgrading and slurry mixing tank 1 as the deployment make-up water, completing the fifth stage of pressure energy utilization.

[0051] Water resources can be reused at two levels, and the process includes: the liquid phase outlet of the high-pressure three-phase separator 14 is connected to the inlet of the high-pressure recycled water of the quality-improving and slurry-mixing tank 1; the outlet 1 of the flow distributor 15 is connected to the water replenishment inlet of the quality-improving and slurry-mixing tank 1, and the outlet 2 is an outlet for other industrial uses; forming a systematic water circulation.

[0052] The waste heat of the fluid after gasification, that is, the waste heat of the fluid after the reaction that has been completely harmlessly treated by the supercritical water oxidation reactor 10, can be reused in two stages. The process includes: releasing heat to the high-pressure cooling water in the regenerator 11, the hot side inlet of the regenerator 11 is connected to the outlet of the supercritical water oxidation reactor 10, and its outlet is connected to the inlet of the pressure energy recovery device 12. The first stage is to heat the high-pressure cooling water from the thermostat 5 and then cool it down; the liquid phase outlet of the high-pressure three-phase separator 14 is connected to the high-pressure reuse water inlet of the upgrading and slurry mixing tank 1, and is mixed with the gasified raw material to release heat, that is, the second stage is to enter the upgrading and slurry mixing tank 1 and be reused as the mixing water for upgrading and slurry mixing of the gasified raw material.

[0053] In the upgrading and slurry adjustment tank 1, the gasified slurry and the high-pressure recycled water that has been thoroughly treated by supercritical water oxidation are mixed with the high-pressure replenishing water heated by the waste heat of the system to reach the target temperature after heat exchange, and the hydrothermal upgrading and slurry adjustment operations of the gasified raw material are completed.

Claims

1. A supercritical water gasification system with energy recovery and zero wastewater discharge, characterized in that: include: The supercritical water gasification hydrogen production unit comprises a quality-improving slurry conditioning tank (1), wherein the quality-improving slurry conditioning tank (1) has three inlets, namely a high-pressure recycled water inlet, a gasification raw material inlet and a water replenishment inlet, and its outlet is connected to the cold side inlet of a slurry preheater (3) through a slurry high-pressure delivery pump (2), and the cold side outlet of the slurry preheater (3) is connected to the inlet of an internal heating type gasification reactor (4); The gas separation unit comprises a thermostat (5), the hot side inlet of the thermostat (5) is connected to the outlet of the internal heat type gasification reactor (4), the hot side outlet is connected to the inlet of a first pressure regulator (6), and the outlet of the first pressure regulator (6) is connected to the inlet of a high-pressure gas separator (7); The waste treatment unit comprises a supplementary heater (9), the slurry outlet of the high-pressure gas separator (7) is connected to the cold side inlet of the supplementary heater (9) through a waste booster pump (8), and the cold side outlet of the supplementary heater (9) is connected to the inlet of a supercritical water oxidation reactor (10); The waste energy recovery unit comprises a regenerator (11), wherein the hot side inlet of the regenerator (11) is connected to the outlet of the supercritical water oxidation reactor (10), the hot side outlet is connected to the inlet of the pressure energy recovery device (12), the outlet of the pressure energy recovery device (12) is connected to the inlet of the high-pressure three-phase separator (14) through a second pressure regulator (13), and the liquid phase outlet of the high-pressure three-phase separator (14) is connected to the high-pressure recycled water inlet of the quality-improving slurry mixing tank (1); the cold side inlet of the regenerator (11) is connected to the cold side outlet of the thermostat (5), the cold side inlet of the thermostat (5) is the inlet of the high-pressure cooling water, the cold side outlet of the regenerator (11) is connected to the hot side inlet of the supplementary heat device (9), the hot side outlet of the supplementary heat device (9) is connected to the inlet of the flow distributor (15), the flow distributor (15) has two outlets, one of which is connected to the replenishing water inlet of the quality-improving slurry mixing tank (1) through a valve; The upgrading and slurry conditioning tank (1) is internally provided with an agitator, which is in the form of a paddle type, a turbine type, an anchor type or a screw type. The high-pressure gas separator (7) is a high-pressure and high-temperature container, the inlet of which is a gasification product after temperature and pressure adjustment, and the outlet is a gas phase product and a slurry after gas phase separation. The high-pressure three-phase separator (14) is a high-pressure and high-temperature container, the inlet of which is a product after supercritical water oxidation treatment, and the outlet is a gas phase product, a solid phase product and a liquid phase product. The slurry preheater (3), the temperature regulator (5), the supplementary heat device (9) and the regenerator (11) all use heat exchangers with high pressure on both sides. The slurry high-pressure delivery pump (2) and the slurry booster pump (8) both use solid-containing high-pressure pumps. The first pressure regulator (6) and the second pressure regulator (13) use a single or a combination of a pressure reducing valve, a back pressure valve and a throttling element. The pressure energy recovery device (12) uses a hydraulic turbine or a piston-type pressure energy recovery machine.

2. The supercritical water gasification system with energy recovery and zero wastewater discharge according to claim 1, characterized in that: The upgrading and slurry mixing tank (1) maintains high temperature and high pressure hydrothermal upgrading operation conditions.

3. The supercritical water gasification system with energy recovery and zero wastewater discharge according to claim 1 is characterized in that: Another outlet of the flow distributor (15) is used as an outlet for other industrial applications, and a valve is arranged on the pipeline of the outlet.

4. The method of the supercritical water gasification system with energy recovery and zero wastewater discharge according to claim 1, characterized in that: include: Supercritical water gasification hydrogen production: The upgrading and slurry mixing tank (1) maintains high temperature and high pressure hydrothermal upgrading conditions so that the raw material and water form a uniform slurry therein, and the slurry high pressure delivery pump (2) increases the pressure of the slurry to a supercritical pressure, and after being heated to a supercritical temperature by a slurry preheater (3), the slurry is sent to an internal heating type gasification reactor (4) to start a supercritical water gasification hydrogen production reaction; Gas separation: The three-phase product obtained after the supercritical water gasification hydrogen production reaction is adjusted to the optimal separation condition by using a thermostat (5) and a first pressure regulator (6), and then the mixed gas is separated and discharged through a high-pressure gas separator (7); Waste treatment: The high-temperature and high-pressure waste liquid obtained from the high-pressure gas separator (7) is pressurized to a supercritical pressure by a waste booster pump (8), then heated to a supercritical temperature by a supplementary heater (9), and then mixed with an oxidant and introduced into a supercritical water oxidation reactor (10) for a supercritical water oxidation reaction to obtain harmless products mainly composed of H2O, CO2 and inorganic salts, thereby achieving a thorough treatment of the gasified waste; Residual energy is recycled. The fluid obtained from the supercritical water oxidation reaction is cooled in the regenerator (11) by heating the high-pressure and low-temperature water from the thermostat (5). The excess pressure energy is then recovered by the pressure energy recovery device (12). The pressure is then accurately controlled and regulated by the second pressure regulator (13). Finally, the fluid enters the high-pressure three-phase separator (14) to separate and discharge the gasification products and solid phase residues. The obtained liquid phase is injected into the upgrading and slurrying tank (1) as recycling water for hydrothermal upgrading and slurrying of the gasified raw materials. The high-pressure cooling water passing through the regenerator (11) is heated to above 450°C and then enters the supplementary heat device (9) to release heat to the gasified waste material to make it reach the supercritical temperature. The fluid exiting the supplementary heat device (9) is divided into two paths by the flow distributor (15). One path enters the upgrading and slurrying tank (1) as slurrying water for the gasified raw materials, and most of the remaining fluid is discharged as heat source fluid for other industrial uses.

5. The method according to claim 4, characterized in that: In the upgrading and slurry adjustment tank (1), the gasified slurry is mixed with high-pressure recycled water that has been thoroughly treated by supercritical water oxidation and high-pressure replenishing water that has been heated by system waste heat to reach the target temperature after heat exchange, and the hydrothermal upgrading and slurry adjustment operations of the gasified raw material are completed.

6. The method according to claim 4, characterized in that: The waste heat of the reaction fluid after being completely harmlessly treated in the supercritical water oxidation reactor (10) is recycled in two stages. The first stage is to heat the high-pressure cooling water from the thermostat (5) and then cool it down. The second stage is to enter the upgrading and slurry conditioning tank (1) and be recycled as the conditioning water for upgrading and slurry conditioning of the gasified raw material.

7. The method according to claim 4, characterized in that: The cooling water has two-stage heating and two-stage recycling, wherein the first stage heating is that the cooling water passes through a thermostat (5) to cool and temperature-regulate the fluid after the supercritical water gasification hydrogen production reaction, thereby controlling its separation temperature; The secondary heating is to heat the fluid to above 450°C after the supercritical water oxidation reaction in the regenerator (11); the primary recycling is to supplement the heat of the gasified waste after gas separation in the supplementary heat device (9) to make its temperature reach the supercritical temperature>374°C; the secondary recycling is to use it as make-up water in the quality improvement slurry tank (1) and other industrial hot water after leaving the supplementary heat device (9).

8. The method according to claim 4, characterized in that: The gasification product of the supercritical water gasification hydrogen production is separated into gas by pressure energy in the high-pressure gas separator (7), completing the first stage of pressure energy utilization; the fluid that completes the first stage of waste heat recovery after supercritical water treatment is separated into the second stage of pressure energy utilization in the pressure energy recovery device (12); the gas and solid phase residue are separated by pressure energy in the high-pressure three-phase separator (14), completing the third stage of pressure energy utilization; the separated liquid phase enters the quality-improving slurry mixing tank (1) for reuse as mixing water, completing the fourth stage of pressure energy utilization; the high-pressure cooling water after the second stage of waste heat utilization enters the quality-improving slurry mixing tank (1) as mixing makeup water, completing the fifth stage of pressure energy utilization.

Images