Diluting system for ethylene membrane recovery purge gas

Abstract

The invention discloses a dilution system for ethylene membrane recovery purge gas, which belongs to the technical field of chemical production, comprises a pipeline b, a pipeline g and a pipeline e, and is characterized in that the pipeline b is connected with a pipeline accessory a and a methane pressure swing adsorption tank, the pipeline b is connected with a pipeline c in parallel, the pipeline h is connected with a pipeline accessory c, the pipeline g is connected with the pipeline h, and the pipeline g is connected with a pipeline accessory d; the pipeline b and the pipeline g are connected through a pipeline a, a pipeline accessory e is connected to the pipeline a, the pipeline h and the pipeline e are connected through a pipeline d, a pipeline accessory f and an ethylene membrane recovery tank are connected to the pipeline e, and a pipeline accessory h is connected to the pipeline f. When the system is switched to the 0.8 MPa natural gas pipeline network for use, it can be guaranteed that adaptive fuel is provided for the 0.4 MPa pipeline network, and the pipeline accessory h is provided for the 0.4 MPa natural gas pipeline network for use. And purge gas in the ethylene membrane recovery tank can be diluted to reach 0.6 MPa natural gas concentration and is sent back to a 0 MPa natural gas pipe network for use when 0.6 M pipe network natural gas is switched next time.

Description

Technical Field

[0001] This invention relates to the field of chemical production technology, specifically to a dilution system for recovering ethylene membrane off-gas. Background Technology

[0002] The purge gas from the ethylene membrane recovery unit of the epoxy plant is a typical industrial tail gas generated during the production process. Its oxygen content is consistently between 7% and 10%, and due to the presence of combustible components, it has recycling value. However, the high oxygen content imposes strict requirements on transportation and combustion safety. Our company originally had two natural gas pipelines at 0.6 MPa and 0.8 MPa, discharging into the plant's 0.4 MPa fuel gas pipeline as fuel for the steam boiler. Therefore, for energy recovery, the purge gas from the ethylene membrane recovery unit needed to be introduced into the 0.6 MPa or 0.8 MPa natural gas pipeline. However, to optimize production costs and reduce steam prices, the company adjusted its energy production strategy, ceasing operation of its own steam boiler and purchasing external steam as a heat source. This resulted in a significant reduction in the gas demand of the plant's original 0.4 MPa fuel gas pipeline. Existing technology uses a 0.6 MPa natural gas and methane pressure swing adsorption tank... After desorbing and mixing to reduce the oxygen content in the mixture to a safe range, the gas is then mixed and diluted with the purge gas from the ethylene membrane recovery unit before being sent to the 0.4MPa pipeline network to accommodate users whose gas demand has decreased significantly. However, when switching to the 0.8MPa natural gas pipeline network, due to its larger flow rate, even if it is mixed and diluted with the purge gas from the ethylene membrane recovery unit before being sent to the 0.4MPa pipeline network, it will exceed the operating load and be difficult to adapt to. This leads to the 0.8MPa pipeline network facing abandonment and becoming unusable. On the other hand, it also means that when the 0.6MPa pipeline network is shut down, the purge gas from the ethylene membrane recovery unit can only be discharged and cannot be recycled. Summary of the Invention

[0003] To address the technical problems mentioned in the background section, this invention provides a dilution system for recovering ethylene membrane off-gas, employing the following technical solution:

[0004] The system includes pipelines b, g, and e, characterized in that pipeline accessory a and a methane pressure swing adsorption tank are connected to pipeline b; pipeline c is connected in parallel to pipeline b; pipeline accessory b is connected to pipeline c; pipeline h is connected to pipeline b; pipeline accessory c is connected to pipeline h; pipeline g is connected to pipeline h; pipeline accessory d is connected to pipeline g; pipeline b and pipeline g are connected via pipeline a, and pipeline accessory e is connected to pipeline a; pipeline h and pipeline e are connected via pipeline d; pipeline accessory f and an ethylene membrane recovery tank are connected to pipeline e; pipeline accessory g is connected to pipeline d; pipeline e and pipeline b are connected via pipeline f; and pipeline accessory h is connected to pipeline f.

[0005] Furthermore, pipeline accessory a includes gate valve w, blind flange i, gate valve v, gate valve r, gate valve t, blind flange h, gate valve u, sampler, thermometer, pressure gauge b, and flow meter b, all connected to pipeline b.

[0006] Furthermore, pipeline accessory b includes a gate valve e and a blind flange b connected to pipeline c.

[0007] Furthermore, pipeline accessories c include gate valve f, blind flange c, gate valve g, pressure gauge c, flow meter c, gate valve l, flow control valve and gate valve m connected to pipeline h.

[0008] Furthermore, pipeline accessory d includes gate valve a, blind flange a, flow meter a, gate valve j, blind flange e, and gate valve k connected to pipeline g.

[0009] Furthermore, pipeline accessory e includes gate valve d, pressure gauge a, gate valve c, pressure control valve a, and gate valve b connected to pipeline a.

[0010] Furthermore, the pipeline accessory f includes a pressure gauge d (31), a gate valve n, a pressure control valve b, a gate valve o, a flow meter d, a gate valve p, a blind flange f, a gate valve q, a pressure gauge e, and a flow meter e connected to the pipeline e.

[0011] Furthermore, pipeline fitting g includes a gate valve h, a blind flange d, and a gate valve i connected to the pipeline d.

[0012] Furthermore, the pipeline fitting h includes a gate valve r, a blind flange g, and a gate valve s connected to the pipeline f.

[0013] This invention has the following advantages: By switching various pipe fittings, pipeline b with a 0.6MPa natural gas interface and pipeline g with a 0.8MPa natural gas interface can be respectively connected to pipeline f at the inlet of the 0.4MPa natural gas network. When switching to use 0.8MPa network natural gas, the system switches to pipeline g, causing the 0.8MPa gas to split into two streams, reducing the flow rate of both streams. Pressure regulation is then used to ensure that one stream has a higher flow rate than the other. The stream with the lower flow rate mixes with the desorbed gas from the pressure swing adsorption tank and is then directly fed into pipeline e, satisfying the requirements of... For users of the 0.4MPa pipeline, a large flow of gas is mixed and diluted with the purge gas generated in the ethylene membrane recovery tank (its concentration is approximately equal to that of natural gas at 0.6MPa) and then sent to the 0.6MPa pipeline b. This way, when switching to the 0.8MPa natural gas pipeline, it can ensure that the 0.4MPa pipeline provides suitable fuel, and the purge gas in the ethylene membrane recovery tank can be diluted to a natural gas concentration of 0.6MPa and sent back to the 0.8MPa natural gas pipeline for use when switching to the 0.6MPa pipeline next time. Attached Figure Description

[0014] Figure 1This is a flowchart of the present invention.

[0015] Attached Figures: 1-Gate Valve a, 2-Blind Plate a, 3-Flow Meter a, 4-Gate Valve b, 5-Pressure Control Valve a, 6-Gate Valve c, 7-Pressure Gauge a, 8-Gate Valve d, 9-Gate Valve e, 10-Blind Plate b, 11-Sampler, 12-Thermometer, 13-Pressure Gauge b, 14-Methane Pressure Swing Adsorption Tank, 15-Flow Meter b, 16-Gate Valve f, 17-Blind Plate c, 18-Gate Valve g, 19-Gate Valve h, 20-Blind Plate d, 21-Gate Valve i, 22-Gate Valve j, 23-Blind Plate e, 24-Gate Valve k, 25-Pressure Gauge c, 26-Flow Meter c, 27-Gate Valve l, 28-Flow Control Valve, 29-Gate Valve m, 3 0-Ethylene membrane recovery tank, 31-Pressure gauge d, 32-Gate valve n, 33-Pressure control valve b, 34-Gate valve o, 35-Flow meter d, 36-Gate valve p, 37-Blind flange f, 38-Gate valve q, 39-Pressure gauge e, 40-Flow meter e, 41-Gate valve r, 42-Blind flange g, 43-Gate valve s, 44-Gate valve t, 45-Blind flange h, 46-Gate valve u, 47-Flow meter f, 48-Gate valve v, 49-Blind flange i, 50-Gate valve w, 51-Pipeline a, 52-Pipeline b, 53-Pipeline c, 54-Pipeline d, 55-Pipeline e, 56-Pipeline f, 57-Pipeline g, 58-Pipeline h. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1As shown, this invention provides a dilution system for ethylene membrane recovery of purge gas, including pipelines b52, g57, and e55. Pipeline b52 is connected to a 0.6 MPa natural gas pipeline network, pipeline g57 is connected to a 0.8 MPa natural gas pipeline network, and pipeline e55 is connected to a 0.4 MPa natural gas user pipeline network. Pipeline accessory a and a methane pressure swing adsorption tank 14 are connected to pipeline g57 and pipeline b52, respectively. Desorption gas is generated in the methane pressure swing adsorption tank 14. Pipeline c53 is connected in parallel to pipeline b52, pipeline accessory b is connected to pipeline c53, and pipeline h5 is connected to pipeline b52. 8. Pipeline h58 is connected to pipeline accessory c. Pipeline g57 is connected to pipeline h58. Pipeline g57 is connected to pipeline accessory d. Pipeline b52 is connected to pipeline g57 via pipeline a51, and pipeline accessory e is connected to pipeline a51. Pipeline h58 is connected to pipeline e55 via pipeline d54. Pipeline e55 is connected to pipeline accessory f and ethylene membrane recovery tank 30. Purge gas is generated in ethylene membrane recovery tank 30. Pipeline accessory g is connected to pipeline d54. Pipeline e55 is connected to pipeline b52 via pipeline f56. Pipeline accessory h is connected to pipeline f56.

[0018] Pipeline accessory A includes gate valve W50, blind flange I49, gate valve V48, gate valve R47, gate valve T44, blind flange H45, gate valve U46, sampler 11, thermometer 12, pressure gauge B13, and flow meter B15 connected to pipeline B52. Gate valves W50, V48, R47, T44, and U46 control the opening and closing of pipeline B52. Blind flanges H45 and I49 prevent fluctuations in pipeline B52. Sampler 11 facilitates gas sampling and testing within pipeline B52. The thermometer 12, pressure gauge B13, and flow meter B15 are used to monitor the temperature, pressure, and flow rate of pipeline B52, respectively.

[0019] Pipeline accessory b includes a gate valve e9 and a blind flange b10 connected to pipeline c53. The gate valve e9 controls the opening and closing of pipeline c53, and the blind flange b10 prevents fluctuations in pipeline c53.

[0020] Pipeline accessory C includes a gate valve f16, a blind flange c17, a gate valve g18, a pressure gauge c25, a flow meter c26, a gate valve l27, a flow control valve 28, and a gate valve m29 connected to pipeline h58. Gate valves f16, g18, l27, and m29 control the opening and closing of pipeline h58. Blind flange c17 prevents fluctuations in pipeline h58. Pressure gauge c25 and flow meter c26 monitor the pressure and flow rate of pipeline h58, respectively. Flow control valve 28 controls the flow rate of pipeline h58.

[0021] Pipeline accessory d includes gate valve a1, blind flange a2, flow meter a3, gate valve j22, blind flange e23, and gate valve k24 connected to pipeline g57. Gate valve a1, gate valve j22, and gate valve k24 control the opening and closing of pipeline g57. Blind flange a2 and blind flange e23 prevent fluctuations in pipeline g57. Flow meter a3 detects the flow rate on pipeline g57.

[0022] Pipeline accessory e includes gate valve d8, pressure gauge a7, gate valve c6, pressure control valve a5, and gate valve b4 connected to pipeline a51. Gate valve d8, gate valve c6, and gate valve b4 control the opening and closing of pipeline a51. Pressure gauge a7 monitors the pressure inside pipeline a51, and pressure control valve a5 controls the pressure inside pipeline a51.

[0023] Pipeline accessory f includes pressure gauge d31, gate valve n32, pressure control valve b33, gate valve o34, flow meter d35, gate valve p36, blind flange f37, gate valve q38, pressure gauge e39, and flow meter e40 connected to pipeline e55. Gate valves n32, o34, p36, and q38 control the opening and closing of pipeline e55. Pressure gauges e39, d31, and b33 monitor and control the pressure within pipeline e55, respectively. Flow meters e40 and d35 monitor the flow rate within pipeline e55. Blind flange f37 prevents fluctuations in pipeline e55.

[0024] Pipeline accessory g includes gate valve h19, blind flange d20 and gate valve i21 connected to pipeline d54. Gate valve h19 and gate valve i21 control the opening and closing of pipeline d54, and blind flange d20 prevents fluctuations in pipeline d54.

[0025] The pipeline accessory h includes a gate valve r41, a blind flange g42, and a gate valve s43 connected to the pipeline f56. The gate valve r41 and the gate valve s43 control the opening and closing of the pipeline f56, and the blind flange g42 prevents fluctuations in the pipeline f56.

[0026] Working principle:

[0027] When using 0.6MPa pipeline natural gas, close gate valves a1, s43, d8, h19, and i21. The 0.6MPa natural gas enters pipeline b52, then enters the methane pressure swing adsorption tank 14 to mix with the desorbed gas before entering pipeline h58. Another stream enters pipeline c53 and then enters pipeline h58 (flowmeter b15 only outputs a little over 100 standard cubic meters, which is insufficient, so it is connected in parallel through pipeline c53 to maintain a flow rate of 2000 kg / h). The mixed gas in pipeline h58 enters pipeline e55 and mixes and dilutes with the purge gas generated by the ethylene membrane recovery device 30 entering pipeline e55 before being sent to the 0.4MPa natural gas user pipeline.

[0028] When using 0.8MPa natural gas, close gate valves t44, u46, e9, f16, g18, p36, and q38, and open gate valves a1, s43, d8, h19, and i21. 0.8MPa natural gas enters pipeline g57. Adjust the pressure in pipeline a51 as monitored by pressure gauge a7, and control the pressure in pipeline a51 via pressure control valve a5, ensuring that the flow rate of natural gas diverted from pipeline g57 to pipeline a51 is less than the flow rate of natural gas within pipeline g57. Natural gas in pipeline a51 enters pipeline b52, then enters the methane pressure swing adsorption tank 14, mixes with the desorbed gas, enters pipeline d54, then enters pipeline e55, and finally enters the 0.4MPa user network. Natural gas in pipeline g57 enters pipeline h58, then enters pipeline e55, mixes with the purge gas generated in the ethylene membrane recovery tank 30, dilutes to a concentration equal to the natural gas concentration in the 0.6MPa network, then enters pipeline f56, and then enters pipeline b52, and is then fed back into the 0.6MPa natural gas network.

[0029] This invention is simple to operate, convenient to use, and suitable for widespread promotion and application. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A dilution system for recovering ethylene membrane purge gas, comprising line b (52), line g (57) and line e (55), characterized in that, Pipeline b (52) is connected to pipeline accessory a and methane pressure swing adsorption tank (14). Pipeline c (53) is connected in parallel to pipeline b (52). Pipeline accessory b is connected to pipeline c (53). Pipeline h (58) is connected to pipeline b (52). Pipeline accessory c is connected to pipeline h (58). Pipeline g (57) is connected to pipeline h (58). Pipeline accessory d is connected to pipeline g (57). Pipeline b (52) and pipeline g (57) are connected to each other. The pipelines are connected by pipeline a (51) and pipeline accessory e is connected to pipeline a (51). Pipeline h (58) and pipeline e (55) are connected by pipeline d (54). Pipeline e (55) is connected by pipeline accessory f and ethylene membrane recovery tank (30). Pipeline d (54) is connected by pipeline accessory g. Pipeline e (55) and pipeline b (52) are connected by pipeline f (56). Pipeline f (56) is connected by pipeline accessory h.

2. The dilution system for recovering purge gas from an ethylene membrane as described in claim 1, characterized in that: Pipeline accessory a includes a gate valve w (50), a blind flange i (49), a gate valve v (48), a gate valve r (47), a gate valve t (44), a blind flange h (45), a gate valve u (46), a sampler (11), a thermometer (12), a pressure gauge b (13), and a flow meter b (15) connected to pipeline b (52).

3. The dilution system for recovering purge gas from an ethylene membrane according to claim 1, characterized in that: Pipeline fitting b includes gate valve e (9) and blind flange b (10) connected to pipeline c (53).

4. The dilution system for recovering purge gas from an ethylene membrane according to claim 1, characterized in that: Pipeline fittings c include gate valve f (16), blind flange c (17), gate valve g (18), pressure gauge c (25), flow meter c (26), gate valve l (27), flow control valve (28), and gate valve m (29) connected to pipeline h (58).

5. The dilution system for recovering purge gas from an ethylene membrane according to claim 1, characterized in that: Pipeline fitting d includes gate valve a (1), blind flange a (2), flow meter a (3), gate valve j (22), blind flange e (23) and gate valve k (24) connected to pipeline g (57).

6. The dilution system for recovering purge gas from an ethylene membrane according to claim 1, characterized in that: Pipeline accessory e includes gate valve d (8), pressure gauge a (7), gate valve c (6), pressure control valve a (5), and gate valve b (4) connected to pipeline a (51).

7. The dilution system for recovering purge gas from an ethylene membrane according to claim 1, characterized in that: Pipeline fittings f include pressure gauge d (31), gate valve n (32), pressure control valve b (33), gate valve o (34), flow meter d (35), gate valve p (36), blind flange f (37), gate valve q (38), pressure gauge e (39), and flow meter e (40) connected to pipeline e (55).

8. The dilution system for recovering purge gas from an ethylene membrane according to claim 1, characterized in that: Pipeline fitting g includes gate valve h (19), blind flange d (20) and gate valve i (21) connected to pipeline d (54).

9. The dilution system for recovering purge gas from an ethylene membrane according to claim 1, characterized in that: The pipeline fitting h includes a gate valve r (41), a blind flange g (42), and a gate valve s (43) connected to the pipeline f (56).

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