A nitrogen and sulfur element resource recovery system and its working method

Abstract

The present invention discloses a nitrogen and sulfur element resource recovery system and its working method, which belong to the field of energy chemical industry and environmental technology. It includes a supercritical water gasification reaction unit, a heat exchange unit, a gas-liquid separation unit, a desulfurization reaction unit, a pressure swing adsorption separation unit, a desulfurizer regeneration unit, an ammonium sulfate absorption unit, an ammonia water concentration unit, an ammonium sulfate crystallization unit, a water tank and a pressure reducing valve. The system of the present invention has a reasonable design and stable and reliable operation. It can avoid the damage of hydrogen sulfide and ammonia to the pressure swing adsorption separation equipment and the harm to the environment in the coal supercritical water hydrogen production technology, and at the same time achieve near-zero emissions of nitrogen and sulfur pollutants in the system and the resource recovery and utilization of nitrogen and sulfur, thereby reducing the cost of treatment.

Description

Technical Field

[0001] The present invention belongs to the field of energy chemical industry and environmental technology, and in particular relates to a nitrogen and sulfur element resource combined recovery system and a working method thereof. Background Art

[0002] During the coal combustion process, nitrogen and sulfur elements will generate large amounts of sulfur oxides and nitrogen oxides, causing great damage to the ecological environment and bringing emission reduction pressure and costs to coal-fired power plants.

[0003] Supercritical water gasification of coal for hydrogen production is an emerging clean coal conversion and utilization technology. Under supercritical water gasification reaction conditions, the carbon and hydrogen elements in coal are mainly converted into hydrogen and carbon dioxide, while the nitrogen and sulfur elements are converted into ammonia and hydrogen sulfide, respectively.

[0004] In coal supercritical water gasification hydrogen production technology, hydrogen sulfide is not only harmful to the environment, but also damages hydrogen pressure swing adsorption (PSA) separation equipment. Ammonia is dissolved in the liquid after gas-liquid separation, and direct discharge will cause environmental pollution. Summary of the Invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a nitrogen and sulfur element resource joint recovery system and its working method. The system has a reasonable design and stable and reliable operation. It can avoid the damage of hydrogen sulfide and ammonia to the pressure swing adsorption separation equipment and harm to the environment in the coal supercritical water hydrogen production technology. At the same time, it can achieve near-zero emissions of nitrogen and sulfur pollutants in the system and resource recovery and utilization of nitrogen and sulfur, thereby reducing treatment costs.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention discloses a nitrogen and sulfur element resource recovery system, which includes a supercritical water gasification reaction unit, a heat exchange unit, a gas-liquid separation unit, a desulfurization reaction unit, a pressure swing adsorption separation unit, a desulfurizer regeneration unit, an ammonium sulfate absorption unit, an ammonia water concentration unit, an ammonium sulfate crystallization unit, a water tank and a pressure reducing valve;

[0008] The fluid outlet of the supercritical water gasification reaction unit is connected to the high-temperature side inlet of the heat exchange unit, and the high-temperature side outlet of the heat exchange unit is connected to the inlet of the gas-liquid separation unit through a pressure reducing valve; the gas outlet of the gas-liquid separation unit is connected to the gas inlet of the desulfurization reaction unit, and the gas outlet of the desulfurization reaction unit is connected to the gas inlet of the pressure swing adsorption separation unit; the liquid outlet of the gas-liquid separation unit is connected to the inlet of the ammonia concentration unit; the desulfurizer outlet of the desulfurization reaction unit is connected to the desulfurizer inlet of the desulfurizer regeneration unit, and the fresh desulfurizer inlet of the desulfurizer regeneration unit is connected to the fresh desulfurizer inlet of the desulfurizer regeneration unit. The sulfur agent outlet is connected; the concentrated ammonia outlet of the ammonia concentration unit is connected to the concentrated ammonia inlet of the ammonium sulfate absorption unit, and the sulfur dioxide outlet of the desulfurizer regeneration unit is connected to the sulfur dioxide inlet of the ammonium sulfate absorption unit; the desulfurizer regeneration unit and the ammonium sulfate absorption unit are both provided with an air inlet, and the outlet of the ammonium sulfate absorption unit is connected to the inlet of the ammonium sulfate crystallization unit; the ammonia concentration unit and the ammonium sulfate crystallization unit are respectively heat exchanged through the low-temperature side of the heat exchange unit; the pure water outlets of the ammonia concentration unit and the ammonium sulfate crystallization unit are respectively connected to the inlet of the water tank, and the outlet of the water tank is connected to the supercritical water gasification reaction unit.

[0009] Preferably, the exhaust gas outlet of the pressure swing adsorption separation unit is connected to the oxidation unit, and the hydrogen outlet of the pressure swing adsorption separation unit is connected to the hydrogen storage device.

[0010] Further preferably, the oxidation unit exchanges heat with the supercritical water gasification reaction unit through a heat exchange device.

[0011] Preferably, a dehumidification device is provided between the gas outlet of the gas-liquid separation unit and the gas inlet of the desulfurization reaction unit.

[0012] Preferably, the heat exchange unit is a single high-temperature side and three low-temperature side heat exchanger.

[0013] Preferably, a water pump is provided on the pipeline between the water tank and the supercritical water gasification reaction unit.

[0014] Preferably, the ammonium sulfate absorption unit is provided with a supplementary liquid ammonia inlet, which is connected to a liquid ammonia source.

[0015] Further preferably, the concentrated ammonia outlet of the ammonia concentration unit is provided with an ammonia concentration detection device, and a regulating valve is provided on the pipeline between the replenishing liquid ammonia inlet and the liquid ammonia source.

[0016] The working method of the nitrogen and sulfur element resource recovery system disclosed in the present invention includes:

[0017] The water in the water tank enters the supercritical water gasification reaction unit to react with the coal. The gasification product dissolves in supercritical water and flows through a pipeline to the heat exchange unit to supply heat to the ammonia concentration unit and external heat before cooling. The cooled fluid is reduced to atmospheric pressure by a pressure reducing valve and enters the gas-liquid separation unit. The gas enters the desulfurization reaction unit to remove hydrogen sulfide. The clean gas after hydrogen sulfide removal enters the pressure swing adsorption separation unit to produce hydrogen product and exhaust gas. The liquid enters the ammonia concentration unit to absorb heat and concentrate to produce concentrated ammonia. The used desulfurizer from the desulfurization reaction unit is sent to the desulfurizer regeneration unit to react with air to produce fresh desulfurizer and sulfur dioxide. The fresh desulfurizer is returned to the desulfurization reaction unit for recycling. The sulfur dioxide enters the ammonium sulfate absorption unit, reacts with the concentrated ammonia from the ammonia concentration unit, and is oxidized by air to produce ammonium sulfate solution. The ammonium sulfate solution enters the ammonium sulfate crystallization unit for endothermic crystallization and purification to produce ammonium sulfate fertilizer product. The clean water generated by the ammonia concentration unit and the ammonium sulfate crystallization unit is collected in the water tank for system recycling.

[0018] Preferably, the exhaust gas generated by the pressure swing adsorption separation unit enters the oxidation unit to release heat, and the heat is supplied to the supercritical water gasification reaction unit.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] The present invention discloses a combined recovery system for the resource utilization of nitrogen and sulfur elements, which can directly regulate the flow mixing of the reaction flow during the supercritical water hydrogen oxidation exothermic reaction, avoid the reaction from being too concentrated and violent, effectively reduce the loss of energy and quality during the reaction, and improve the overall efficiency of the hydrogen oxidation reactor. The entire system has a high desulfurization efficiency and a high ammonia absorption rate, can continuously recover nitrogen and sulfur elements, convert nitrogen and sulfur elements into nitrogen fertilizers, achieve near-zero emissions of nitrogen and sulfur pollutants, and reduce the cost of pollutant treatment. The system has wide applicability and is not only suitable for the supercritical water gasification hydrogen production process of coal, but also for the supercritical water gasification hydrogen production process of various organic matter containing nitrogen and sulfur elements. The used desulfurizer can be regenerated in the desulfurizer regeneration unit for recycling, and the generated sulfur dioxide can be used subsequently. At the same time, the heat generated by the supercritical water gasification reaction unit can be supplied to the ammonia concentration unit and the ammonium sulfate crystallization unit, and the excess heat can also be supplied to the outside for heating, making full use of the heat of the system.

[0021] Furthermore, a dehumidification device is provided between the gas outlet of the gas-liquid separation unit and the gas inlet of the desulfurization reaction unit, which can remove the liquid entrained in the gas.

[0022] Furthermore, the ammonium sulfate absorption unit is provided with a liquid ammonia supplement inlet. When the ammonia concentration obtained by concentration is insufficient, liquid ammonia can be added from the liquid ammonia supplement inlet.

[0023] Furthermore, the concentrated ammonia outlet of the ammonia concentration unit is equipped with an ammonia concentration detection device, which can accurately detect the concentration of the outlet ammonia and use a regulating valve to control the amount of liquid ammonia added according to the detection value, thereby achieving precise control of the system reaction parameters.

[0024] The working method of the nitrogen and sulfur element resource combined recovery system disclosed in the present invention has a high degree of automation, energy conservation and emission reduction, and low operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the overall structure of the system of the present invention.

[0026] In the figure: 1 is a supercritical water gasification reaction unit, 2 is a heat exchange unit, 3 is a gas-liquid separation unit, 4 is a desulfurization reaction unit, 5 is a pressure swing adsorption separation unit, 6 is a desulfurizer regeneration unit, 7 is an ammonium sulfate absorption unit, 8 is an ammonia water concentration unit, 9 is an ammonium sulfate crystallization unit, 10 is a water tank, 11 is a water pump, and 12 is a pressure reducing valve. DETAILED DESCRIPTION

[0027] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments, which are intended to explain rather than limit the present invention:

[0028] like Figure 1 The nitrogen and sulfur element resource recovery system of the present invention includes a supercritical water gasification reaction unit 1, a heat exchange unit 2, a gas-liquid separation unit 3, a desulfurization reaction unit 4, a pressure swing adsorption separation unit 5, a desulfurizer regeneration unit 6, an ammonium sulfate absorption unit 7, an ammonia concentration unit 8, an ammonium sulfate crystallization unit 9, a water tank 10 and a pressure reducing valve 12;

[0029] The fluid outlet of the supercritical water gasification reaction unit 1 is connected to the high-temperature side inlet of the heat exchange unit 2, and the high-temperature side outlet of the heat exchange unit 2 is connected to the inlet of the gas-liquid separation unit 3 through the pressure reducing valve 12; the gas outlet of the gas-liquid separation unit 3 is connected to the gas inlet of the desulfurization reaction unit 4, and the gas outlet of the desulfurization reaction unit 4 is connected to the gas inlet of the pressure swing adsorption separation unit 5; the liquid outlet of the gas-liquid separation unit 3 is connected to the inlet of the ammonia concentration unit 8; the desulfurizer outlet of the desulfurization reaction unit 4 is connected to the desulfurizer inlet of the desulfurizer regeneration unit 6, and the fresh desulfurizer inlet of the desulfurizer regeneration unit 6 is connected to the fresh desulfurizer inlet of the desulfurizer regeneration unit 6 The concentrated ammonia outlet of the ammonia concentration unit 8 is connected to the concentrated ammonia inlet of the ammonium sulfate absorption unit 7, and the sulfur dioxide outlet of the desulfurizer regeneration unit 6 is connected to the sulfur dioxide inlet of the ammonium sulfate absorption unit 7; the desulfurizer regeneration unit 6 and the ammonium sulfate absorption unit 7 are both provided with an air inlet, and the outlet of the ammonium sulfate absorption unit 7 is connected to the inlet of the ammonium sulfate crystallization unit 9; the ammonia concentration unit 8 and the ammonium sulfate crystallization unit 9 are respectively heat exchanged through the low-temperature side of the heat exchange unit 2; the pure water outlets of the ammonia concentration unit 8 and the ammonium sulfate crystallization unit 9 are respectively connected to the inlet of the water tank 10, and the outlet of the water tank 10 is connected to the supercritical water gasification reaction unit 1.

[0030] In a preferred embodiment of the present invention, the exhaust gas outlet of the pressure swing adsorption separation unit 5 is connected to an oxidation unit, and the hydrogen outlet of the pressure swing adsorption separation unit 5 is connected to a hydrogen storage device. Preferably, the oxidation unit exchanges heat with the supercritical water gasification reaction unit 1 through a heat exchange device.

[0031] In a preferred embodiment of the present invention, a dehumidification device is provided between the gas outlet of the gas-liquid separation unit 3 and the gas inlet of the desulfurization reaction unit 4 .

[0032] In a preferred embodiment of the present invention, the heat exchange unit 2 is a heat exchanger with a single high-temperature side and three low-temperature sides.

[0033] In a preferred embodiment of the present invention, a water pump 11 is provided on the pipeline between the water tank 10 and the supercritical water gasification reaction unit 1 .

[0034] In a preferred embodiment of the present invention, the ammonium sulfate absorption unit 7 is provided with a supplementary liquid ammonia inlet, which is connected to a liquid ammonia source. Preferably, the concentrated ammonia outlet of the ammonia concentration unit 8 is provided with an ammonia concentration detection device, and a regulating valve is provided on the pipeline between the supplementary liquid ammonia inlet and the liquid ammonia source.

[0035] The above-mentioned nitrogen and sulfur element resource recovery system includes the following processes when in operation:

[0036] Water is pumped from a water tank 10 under pressure by a water pump 11 into the supercritical water gasification unit 1 to react with coal. The gasification produces hydrogen and carbon dioxide as primary gaseous products, along with small amounts of hydrogen sulfide and ammonia as contaminants. These products dissolve in supercritical water and flow through pipelines to the heat exchange unit 2, providing heat to the system and externally. The cooled fluid is reduced to atmospheric pressure by a pressure reducing valve 12 before entering the gas-liquid separation unit 3. The gas enters the desulfurization unit 4 to remove hydrogen sulfide. The clean gas, after hydrogen sulfide removal, enters the pressure swing adsorption separation unit 5, producing hydrogen product and exhaust gas. The exhaust gas then enters the oxidation unit, releasing heat to supply heat to the supercritical water gasification unit 1. The liquid separated by the gas-liquid separation unit 3 enters the ammonia concentration unit 8, where it absorbs heat and concentrates to produce concentrated ammonia. The desulfurizer used in the desulfurization unit 4 is fed to the desulfurizer regeneration unit 6, where it reacts with air to produce fresh desulfurizer and sulfur dioxide. Fresh desulfurizer can be fed into the desulfurization reaction unit 4 for recycling, while sulfur dioxide is fed into the ammonium sulfate absorption unit 7, where it reacts with concentrated ammonia from the ammonia concentration unit 8 and is oxidized by air to produce ammonium sulfate solution. If the ammonia concentration from the ammonia concentration unit is insufficient, liquid ammonia can be added from the replenishment liquid ammonia inlet to participate in the absorption reaction. The ammonium sulfate solution is then fed into the ammonium sulfate crystallization unit 9 for endothermic crystallization and purification to produce ammonium sulfate fertilizer. The purified water from the ammonia concentration unit 8 and the ammonium sulfate crystallization unit 9 is collected in a water tank 10 for recycling.

[0037] The above description is only part of the embodiments of the present invention. Although some terms are used in the present invention, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the present invention. Interpreting them as any additional limitations is contrary to the spirit of the present invention. The above description is only to further illustrate the content of the present invention with examples to facilitate easier understanding, but it does not mean that the embodiments of the present invention are limited to these. Any technical extension or re-creation made according to the present invention is protected by the present invention.

Claims

1. A nitrogen and sulfur element resource recovery system, characterized in that: It comprises a supercritical water gasification reaction unit (1), a heat exchange unit (2), a gas-liquid separation unit (3), a desulfurization reaction unit (4), a pressure swing adsorption separation unit (5), a desulfurizer regeneration unit (6), an ammonium sulfate absorption unit (7), an ammonia water concentration unit (8), an ammonium sulfate crystallization unit (9), a water tank (10) and a pressure reducing valve (12); The fluid outlet of the supercritical water gasification reaction unit (1) is connected to the high-temperature side inlet of the heat exchange unit (2), and the high-temperature side outlet of the heat exchange unit (2) is connected to the inlet of the gas-liquid separation unit (3) through a pressure reducing valve (12); the gas outlet of the gas-liquid separation unit (3) is connected to the gas inlet of the desulfurization reaction unit (4), and the gas outlet of the desulfurization reaction unit (4) is connected to the gas inlet of the pressure swing adsorption separation unit (5); the liquid outlet of the gas-liquid separation unit (3) is connected to the inlet of the ammonia concentration unit (8); the desulfurizer outlet of the desulfurization reaction unit (4) is connected to the desulfurizer inlet of the desulfurizer regeneration unit (6), and the fresh desulfurizer inlet of the desulfurizer regeneration unit (6) is connected to the fresh desulfurizer in the desulfurizer regeneration unit (6). The concentrated ammonia outlet of the ammonia concentration unit (8) is connected to the concentrated ammonia inlet of the ammonium sulfate absorption unit (7), and the sulfur dioxide outlet of the desulfurizer regeneration unit (6) is connected to the sulfur dioxide inlet of the ammonium sulfate absorption unit (7); the desulfurizer regeneration unit (6) and the ammonium sulfate absorption unit (7) are both provided with an air inlet, and the outlet of the ammonium sulfate absorption unit (7) is connected to the inlet of the ammonium sulfate crystallization unit (9); the ammonia concentration unit (8) and the ammonium sulfate crystallization unit (9) are both heat-exchanged through the low-temperature side of the heat exchange unit (2); the pure water outlets of the ammonia concentration unit (8) and the ammonium sulfate crystallization unit (9) are respectively connected to the inlet of the water tank (10), and the outlet of the water tank (10) is connected to the supercritical water gasification reaction unit (1).

2. The nitrogen and sulfur element resource recovery system according to claim 1 is characterized in that: The exhaust gas outlet of the pressure swing adsorption separation unit (5) is connected to the oxidation unit, and the hydrogen outlet of the pressure swing adsorption separation unit (5) is connected to the hydrogen storage device.

3. The nitrogen and sulfur element resource recovery system according to claim 2 is characterized in that: The oxidation unit exchanges heat with the supercritical water gasification reaction unit (1) through a heat exchange device.

4. The nitrogen and sulfur element resource recovery system according to claim 1 is characterized in that: A dehumidification device is provided between the gas outlet of the gas-liquid separation unit (3) and the gas inlet of the desulfurization reaction unit (4).

5. The nitrogen and sulfur element resource recovery system according to claim 1 is characterized in that: The heat exchange unit (2) is a single high-temperature side and three low-temperature side heat exchanger.

6. The nitrogen and sulfur element resource recovery system according to claim 1 is characterized in that: A water pump (11) is provided on the pipeline between the water tank (10) and the supercritical water gasification reaction unit (1).

7. The nitrogen and sulfur element resource recovery system according to claim 1 is characterized in that: The ammonium sulfate absorption unit (7) is provided with a liquid ammonia supplement inlet, which is connected to a liquid ammonia source.

8. The nitrogen and sulfur element resource recovery system according to claim 7 is characterized in that: The concentrated ammonia outlet of the ammonia concentration unit (8) is provided with an ammonia concentration detection device, and a regulating valve is provided on the pipeline between the replenishing liquid ammonia inlet and the liquid ammonia source.

9. The operating method of the nitrogen and sulfur element resource recovery system according to any one of claims 1 to 8, characterized in that: include: The water in the water tank (10) enters the supercritical water gasification reaction unit (1) to react with the coal, and the gasification product is dissolved in the supercritical water and flows through the pipeline to the heat exchange unit (2) to supply heat to the ammonia concentration unit (8) and external heat and then cool; the cooled fluid is reduced to normal pressure by the pressure reducing valve (12) and enters the gas-liquid separation unit (3), wherein the gas enters the desulfurization reaction unit (4) to remove hydrogen sulfide, and the clean gas after the hydrogen sulfide is removed enters the pressure swing adsorption separation unit (5) to obtain hydrogen product and exhaust gas; wherein the liquid enters the ammonia concentration unit (8) to absorb heat and concentrate to obtain concentrated ammonia water; the desulfurizer used in the desulfurization reaction unit (4) is sent to the desulfurizer regeneration unit (6) to react with air to generate fresh desulfurizer and sulfur dioxide, and the fresh desulfurizer is returned to the desulfurization reaction unit (4) for recycling, and the sulfur dioxide enters the ammonium sulfate absorption unit (7), reacts with the concentrated ammonia water from the ammonia concentration unit (8), and is oxidized by air to generate ammonium sulfate solution; The ammonium sulfate solution enters the ammonium sulfate crystallization unit (9) for endothermic crystallization and purification to obtain an ammonium sulfate fertilizer product; the clean water generated by the ammonia concentration unit (8) and the ammonium sulfate crystallization unit (9) is collected in the water tank (10) for system recycling.

10. The operating method of the nitrogen and sulfur element resource recovery system according to claim 9, characterized in that: The exhaust gas generated by the pressure swing adsorption separation unit (5) enters the oxidation unit to release heat, and the heat is supplied to the supercritical water gasification reaction unit (1).

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