Waste gas utilization system of PSA (Pressure Swing Adsorption) nitrogen-making system of gas station

Abstract

A waste gas utilization system of a PSA (pressure swing adsorption) nitrogen making system of a gas station belongs to the technical field of coal chemical industry and comprises a pressure swing adsorption nitrogen making machine, and a waste gas pipeline at an outlet of the pressure swing adsorption nitrogen making machine is divided into a diffused waste gas pipeline and an oxygen-enriched air utilization pipeline; a first automatic control valve communicated with the atmosphere is arranged on the diffused waste gas pipeline; the waste gas pipeline is connected with a gas storage tank through a second automatic control valve and a first check valve; the gas storage tank is connected with the waste gas heater through a pressure-stabilized waste gas pipeline, and the waste gas heater is connected with the gasification furnace through a temperature-rising waste gas pipeline. The waste gas discharged by the pressure swing adsorption nitrogen making machine is recycled to serve as a gasifying agent of the coal gas, the temperature of the waste gas entering the gas furnace is increased through the waste gas heater, and the gasification efficiency of the coal gas is improved; the temperature of coal gas entering the coal gas cooler is reduced through the waste gas heater, the circulating water consumption is reduced, and the coal gas water consumption is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal chemical industry, and in particular relates to a waste gas utilization system of a PSA nitrogen production system of a gas station. Background Art

[0002] Nitrogen is a critical gas in the coal-to-gas process, with a wide range of applications and high usage. It's primarily used for baghouse dust collector injection, coal hopper injection, fly ash conveying, and nitrogen replacement. Due to its simple system and minimal ancillary equipment, nitrogen is typically produced using a pressure swing adsorption (PSA) nitrogen generator. This generates a significant amount of waste gas (oxygen-enriched air). Due to the inherent characteristics of PSA, this waste gas is discontinuous and pulsating. In previous projects, this waste gas was discharged and underutilized. This waste gas is the residual oxygen left after nitrogen adsorption, and gasifiers require air or oxygen as a gasifying agent during the gasification process. Discharging this waste gas results in energy waste.

[0003] The nitrogen purity required in the coal gasification process is generally required to be above 99%. Nitrogen is produced by purified high-quality compressed air. The air-to-nitrogen ratio of 99% pure nitrogen produced by the PSA nitrogen production process is about 2.8, that is, 1 Nm 3 99% pure nitrogen requires 2.8 Nm 3 The compressed air in previous projects was actually close to 1.8Nm 3 Exhaust gas (oxygen-enriched air) will be discharged. 3 The nitrogen required for coal gas is 25~35Nm 3 , each 1KNm 3 The exhaust gas emitted by the coal gas is 45~63Nm 3 The exhaust gas discharged by the pressure swing adsorption nitrogen generator has a pressure of 0.1~0.2Mpa, and the pressure energy of the exhaust gas is relatively high. The exhaust gas has utilization value in terms of both quantity and mass energy. Summary of the Invention

[0004] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a waste gas utilization system for the PSA nitrogen production system of a gas station, the purpose of which is to efficiently and safely utilize the waste gas (oxygen-enriched air) discharged by the pressure swing adsorption nitrogen production equipment in the existing coal gasification process, reduce the consumption of circulating water, reduce the power consumption of coal gasification, reduce the unit cost of coal gasification, and save energy and reduce emissions.

[0005] In order to achieve the above objectives, the main technical solutions adopted by the present invention include: A waste gas utilization system for a PSA nitrogen production system in a gas station includes a pressure swing adsorption (PSA) nitrogen generator. The waste gas pipeline at the outlet of the pressure swing adsorption (PSA) nitrogen generator is divided into two pipelines: a venting waste gas pipeline and an oxygen-enriched air utilization pipeline. The venting waste gas pipeline is provided with a first automatic control valve connected to the atmosphere. The waste gas pipeline is connected to a gas storage tank via a second automatic control valve and a first check valve. The gas storage tank is connected to an exhaust gas heater via a post-pressure stabilization exhaust gas pipeline. The exhaust gas heater is connected to a gasifier via a temperature-raising exhaust gas pipeline. The gasifier is connected to a gas waste heat utilization device via a high-temperature gas pipeline. The gas waste heat utilization device is connected to a bag filter via a medium-temperature gas pipeline before the bag filter. The bag filter is connected to the exhaust gas heater via a medium-temperature gas pipeline after the bag filter. The exhaust gas heater is connected to a gas cooler via a low-temperature gas pipeline after the exhaust gas heater. The gas cooler is connected to a desulfurization system via a low-temperature gas pipeline after the gas cooler.

[0006] Furthermore, the heated exhaust gas pipeline is provided with a pressure detection device, which is interlocked with the first automatic control valve and the second automatic control valve.

[0007] Furthermore, a second check valve is provided on the heated exhaust gas pipeline before entering the gasifier.

[0008] Furthermore, the gas cooler is cooled by circulating water.

[0009] Furthermore, the gas temperature of the high-temperature gas pipeline is 800-900°C.

[0010] Furthermore, the gas temperature of the low-temperature gas pipeline after the exhaust gas heater is 130-160°C.

[0011] Furthermore, the temperature in the low-temperature gas pipeline after the gas cooler will reach 40°C.

[0012] Furthermore, the gas temperature of the medium-temperature gas pipeline before the bag is 170-200°C; the gas temperature of the medium-temperature gas pipeline after the bag is 160-190°C.

[0013] Furthermore, the temperature of the waste gas pipeline after pressure stabilization is 25-30°C; the temperature of the waste gas pipeline after heating is 130-160°C.

[0014] Furthermore, the coal gas waste heat utilization device is a heat exchanger, and the heat exchange medium is water. After the coal gas waste heat utilization device gasifies the heat exchange medium, a part of it enters the gasifier as a gasifying agent.

[0015] The beneficial effects of the present invention are: This invention recycles the exhaust gas (oxygen-enriched air) emitted by a pressure swing adsorption (PSA) nitrogen generator as a gasifying agent for coal gasification. The high-temperature gas from the gasifier is used to gasify the heat exchange medium water within the gas waste heat recovery unit, which then enters the gasifier. The low-temperature gas from the gas waste heat recovery unit is then removed from the gasifier by a bag filter. The remaining relatively high-temperature gas then provides heat for the exhaust gas heat exchanger, heating the exhaust gas before entering the gasifier. After heat exchange in the exhaust gas heat exchanger, the gas is cooled by circulating cooling water before entering the desulfurization system. Heat exchange in the exhaust gas heat exchanger utilizes the waste heat of the gas to heat the exhaust gas, while reducing the amount of cooling water required to cool the high-temperature gas. This fully utilizes the exhaust gas emitted by the PSA nitrogen generator, reducing energy waste.

[0016] The present invention respectively arranges automatic control valves on the waste gas discharging pipeline and the waste gas utilization pipeline. The automatic control valves are interlocked with the pressure detection device arranged on the waste gas utilization pipeline to realize automatic control of waste gas recovery. The oxygen-enriched air discharged by the pressure swing adsorption nitrogen generator can be automatically utilized without adding other power equipment. Only by using pipelines, valves and detection elements, the oxygen concentration in the gasifying agent is increased, and the unit power consumption of coal gasification is reduced.

[0017] This invention eliminates the discontinuous emission of waste gas by installing a gas storage tank after the PSA nitrogen generator, thereby stabilizing the waste gas pressure. The PSA nitrogen generator waste gas recovery system is equipped with an exhaust gas heater to increase the temperature of the waste gas entering the gasifier, thereby improving gasification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the waste gas utilization system of the PSA nitrogen production system of a gas station according to the present invention.

[0019] In the figure: 1. Pressure swing adsorption nitrogen generator; 2. Gas storage tank; 3. Exhaust gas heater; 4. Gasifier; 5. Gas waste heat utilization device; 6. Bag filter; 7. Gas cooler; V1. First automatic control valve; V2. Second automatic control valve; V3. First check valve; V4. Second check valve; G1. High-temperature gas pipeline; G2a. Medium-temperature gas pipeline before bag filter; G2b. Medium-temperature gas pipeline after bag filter; G3. Low-temperature gas pipeline after exhaust heater; G4. Low-temperature gas pipeline after gas cooler; G5. Exhaust gas pipeline; G6. Exhaust gas release pipeline; G7. Exhaust gas pipeline after pressure stabilization; G8. Exhaust gas pipeline for heating. DETAILED DESCRIPTION

[0020] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0021] like Figure 1As shown, the present invention provides a waste gas utilization system for a PSA nitrogen production system in a gas station, comprising a pressure swing adsorption (PSA) nitrogen generator 1. The waste gas pipeline G5 at the outlet of the PSA nitrogen generator 1 is divided into two pipelines: a discharge waste gas pipeline G6 and an oxygen-enriched air utilization pipeline. The discharge waste gas pipeline G6 is provided with a first automatic control valve V1, which is vented to the atmosphere. The waste gas pipeline G5 is connected to a gas storage tank 2 via a second automatic control valve V2 and a first check valve V3. The provision of the gas storage tank 2 eliminates the discontinuous discharge of waste gas and stabilizes the waste gas pressure. To ensure that the normal operation of the PSA nitrogen generator 1 is not affected when the waste gas is not being utilized, the PSA nitrogen generator 1 is provided with a discharge waste gas pipeline G6.

[0022] The gas storage tank 2 is connected to the exhaust gas heater 3 via the post-pressure stabilization exhaust gas pipeline G7, and the exhaust gas heater 3 is connected to the gasifier 4 via the heating exhaust gas pipeline G8. The heating exhaust gas pipeline is arranged on the gasifier air distribution plate, below the return pipe. The gasifier 4 is connected to the gas waste heat utilization device 5 via the high-temperature gas pipeline G1; the gas waste heat utilization device 5 is connected to the bag filter 6 via the medium-temperature gas pipeline G2a before the bag filter; the bag filter 6 is connected to the exhaust gas heater 3 via the medium-temperature gas pipeline G2b after the bag filter; the exhaust gas heater 3 is connected to the gas cooler 7 via the low-temperature gas pipeline G3 after the exhaust gas heater; the gas cooler 7 is connected to the desulfurization system via the low-temperature gas pipeline G4 after the gas cooler. The gas cooler 7 is cooled by circulating water.

[0023] Specifically, the coal gas waste heat utilization device 5 is a heat exchanger, and the heat exchange medium is water. After the coal gas waste heat utilization device 5 gasifies the heat exchange medium, a portion of it enters the gasification furnace 4 as a gasifying agent.

[0024] Specifically, the heating exhaust gas pipeline G8 is equipped with a pressure detection device, which is interlocked with the first automatic control valve V1 and the second automatic control valve V2. To achieve automatic switching between waste gas utilization and safe release, the heating exhaust gas pipeline G8, which passes through the exhaust gas heater, is equipped with a pressure detection device. This device is interlocked with the automatic control valve V1 on the exhaust gas release pipeline G6 and the automatic control valve V2 before the gas storage tank 2. When the pressure in the waste gas utilization pipeline rises and cannot meet the requirements of the gasifier, the automatic control valve V1 opens and the automatic control valve V2 automatically closes.

[0025] Specifically, in order to prevent the coal gas from flowing back through the heated exhaust gas pipeline, a second check valve V4 is provided before the heated exhaust gas pipeline G8 enters the gasifier 4 .

[0026] Specifically, the gas temperature of the high-temperature gas pipeline G1 is 800~900℃; the gas temperature of the low-temperature gas pipeline G3 after the exhaust gas heater is 130~160℃; the gas temperature of the medium-temperature gas pipeline G2a before the bag filter is 170~200℃; the gas temperature of the medium-temperature gas pipeline G2b after the bag filter is 160~190℃; the temperature of the waste gas pipeline G7 after pressure stabilization is 25~30℃; the temperature of the heating waste gas pipeline G8 is 130~160℃; the temperature in the low-temperature gas pipeline G4 after the gas cooler will reach 40℃.

[0027] This invention recycles the exhaust gas (oxygen-enriched air) emitted by a pressure swing adsorption nitrogen generator as a gasifying agent for coal-to-gas production. The high-temperature coal gas from the gasifier is used to gasify the heat exchange medium water within the coal gas waste heat recovery unit, which then enters the gasifier. The low-temperature coal gas from the waste gas heat recovery unit is then removed from the gasifier by a bag filter. The remaining high-temperature coal gas provides heat for the waste gas heat exchanger, heating the waste gas before entering the gasifier. After heat exchange in the waste gas heat exchanger, the coal gas is cooled by circulating cooling water before entering the desulfurization system. Heat exchange in the waste gas heat exchanger utilizes waste gas heat to heat the waste gas, while reducing the amount of cooling water required to cool the high-temperature coal gas.

[0028] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limiting the present invention. Any changes, modifications, substitutions and variations of the above embodiments by a person skilled in the art fall within the scope of the present invention.

Claims

1. A waste gas utilization system for a PSA nitrogen production system in a gas station, characterized by: The invention comprises a pressure swing adsorption nitrogen generator (1), wherein the waste gas pipeline (G5) at the outlet of the pressure swing adsorption nitrogen generator (1) is divided into two pipelines: a venting waste gas pipeline (G6) and an oxygen-enriched air utilization pipeline; the venting waste gas pipeline (G6) is provided with a first automatic control valve (V1) communicating with the atmosphere; the waste gas pipeline (G5) is connected to the gas storage tank (2) through a second automatic control valve (V2) and a first check valve (V3); the gas storage tank (2) is connected to the waste gas heater (3) through a pressure-stabilized waste gas pipeline (G7); the waste gas heater (3) is connected to the gasification furnace ( 4), the gasifier (4) is connected to the gas waste heat utilization device (5) through a high-temperature gas pipeline (G1); the gas waste heat utilization device (5) is connected to the bag dust collector (6) through a medium-temperature gas pipeline (G2a) before the bag; the bag dust collector (6) is connected to the exhaust gas heater (3) through a medium-temperature gas pipeline (G2b) after the bag; the exhaust gas heater (3) is connected to the gas cooler (7) through a low-temperature gas pipeline (G3) after the exhaust gas heater; the gas cooler (7) is connected to the desulfurization system through a low-temperature gas pipeline (G4) after the gas cooler.

2. The waste gas utilization system of the PSA nitrogen production system of a gas station according to claim 1, characterized in that: The heated exhaust gas pipeline (G8) is provided with a pressure detection device, which is interlocked with the first automatic control valve (V1) and the second automatic control valve (V2).

3. The waste gas utilization system of the PSA nitrogen production system of a gas station according to claim 1, characterized in that: The heated exhaust gas pipeline (G8) is provided with a second check valve (V4) before entering the gasification furnace (4).

4. The waste gas utilization system of the PSA nitrogen production system of a gas station according to claim 1, characterized in that: The gas cooler (7) is cooled by circulating water.

5. The waste gas utilization system of the PSA nitrogen production system of a gas station according to claim 1, characterized in that: The gas temperature of the high-temperature gas pipeline (G1) is 800-900°C.

6. The waste gas utilization system of the PSA nitrogen production system of a gas station according to claim 1, characterized in that: The gas temperature of the low-temperature gas pipeline (G3) after the exhaust gas heater is 130~160℃.

7. The waste gas utilization system of the PSA nitrogen production system of a gas station according to claim 1, characterized in that: The temperature in the low-temperature gas pipeline (G4) after the gas cooler will reach 40°C.

8. The waste gas utilization system of the PSA nitrogen production system of a gas station according to claim 1, characterized in that: The gas temperature of the medium-temperature gas pipeline (G2a) before the bag is 170-200°C; the gas temperature of the medium-temperature gas pipeline (G2b) after the bag is 160-190°C.

9. The waste gas utilization system of the PSA nitrogen production system of a gas station according to claim 1, characterized in that: The temperature of the pressure-stabilized exhaust gas pipeline (G7) is 25-30°C; the temperature of the heated exhaust gas pipeline (G8) is 130-160°C.

10. The waste gas utilization system of the PSA nitrogen production system of a gas station according to claim 1, characterized in that: The coal gas waste heat utilization device (5) is a heat exchanger, and the heat exchange medium is water. After the coal gas waste heat utilization device (5) gasifies the heat exchange medium, a portion of the water enters the gasification furnace (4) as a gasifying agent.

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