A fuel system for a natural gas to syngas plant

Abstract

The utility model belongs to the field of chemical synthesis technology, concretely relates to a fuel system for natural gas preparation synthetic gas device, including natural gas heater, fuel gas separator and heating furnace, and the import end and export end of natural gas heater are connected with natural gas inlet pipe and raw material gas pipe respectively, and the raw material gas pipe links to each other with heating furnace, the raw material gas pipe is linked with main fuel gas pipe, and the main fuel gas pipe links to each other with fuel gas separator, and the fuel gas separator links to each other with heating furnace, and the natural gas inlet pipe is linked with main fuel gas pipe and has the starting fuel gas pipe, and the natural gas inlet pipe is installed with natural gas valve, and the raw material gas pipe is installed with raw material gas valve, and the main fuel gas pipe is installed with fuel gas valve I and pressure reducing valve, and the starting fuel gas pipe is installed with fuel gas valve II, in the utility model, the natural gas valve or fuel gas valve I and raw material gas valve are damaged simultaneously under the starting condition, and only then can natural gas mix with starting cycle gas, effectively reduce the accident probability, improve the security.

Description

Technical Field

[0001] This utility model belongs to the field of chemical synthesis technology, specifically relating to a fuel system for a natural gas to syngas production device. Background Technology

[0002] Natural gas is a high-quality clean energy source with low sulfur content and minimal pollution. It is widely used globally to produce hydrogen, methanol, ethylene glycol, synthetic ammonia, and synthetic oils. The natural gas-to-ethylene glycol (PGG) process involves converting natural gas into syngas, and then using a catalyst to convert the syngas into ethylene glycol. In the PGG process, natural gas, as the feedstock, is compressed, desulfurized, purified, and heated before being sent to a conversion furnace to produce syngas. The syngas then undergoes a decarbonization unit to remove CO2, followed by an H2 / CO cryogenic separation unit and a PSA pressure swing adsorption unit to separate H2 and CO for ethylene glycol synthesis. The natural gas is heated through fuel combustion, thus serving as both a feedstock and a fuel. Under normal operating conditions, a portion of the natural gas enters the syngas production system, and the remainder enters the fuel system. During start-up, the start-up circulating gas circulates within the syngas production system, while natural gas only enters the fuel system. The switching of natural gas lines relies on a single valve for control. When this valve fails, the natural gas will mix with the circulating gas during operation, causing a safety accident and posing a significant safety risk. Utility Model Content

[0003] The present invention aims to provide a fuel system for a natural gas to syngas production plant to solve the safety risks posed by the easy mixing of natural gas with the start-up circulating gas during operation.

[0004] To achieve the above objectives, the present invention provides a fuel system for a natural gas-to-syngas production device, comprising a natural gas heater, a fuel gas separator, and a heating furnace. The inlet end of the natural gas heater is connected to a natural gas inlet pipe, and the outlet end is connected to a raw material gas pipe. The end of the raw material gas pipe furthest from the natural gas heater is connected to the raw material gas inlet of the heating furnace. The raw material gas pipe is connected to a main fuel gas pipe, and the end of the main fuel gas pipe furthest from the raw material gas pipe is connected to the fuel gas separator. The fuel gas separator is connected to the fuel gas inlet of the heating furnace via a pipeline. A natural gas valve is installed on the natural gas inlet pipe, a raw material gas valve is installed on the raw material gas pipe, and a fuel gas valve I and a pressure reducing valve are installed on the main fuel gas pipe. A start-up fuel gas pipe connects the natural gas inlet pipe and the main fuel gas pipe. The connection point between the start-up fuel gas pipe and the natural gas inlet pipe is located on the side of the natural gas valve furthest from the natural gas heater, and the connection point between the start-up fuel gas pipe and the main fuel gas pipe is located on the side of the fuel gas valve I furthest from the raw material gas pipe. A fuel gas valve II is installed on the start-up fuel gas pipe.

[0005] The working principle and beneficial effects of this scheme are as follows: Under start-up conditions, the natural gas valve, fuel gas valve I, and feedstock gas valve are all closed, while fuel gas valve II is open. High-pressure natural gas in the natural gas inlet pipe enters the main fuel gas pipe via the start-up fuel gas pipe, undergoes pressure reduction, enters the fuel gas separator, and finally enters the heater to heat the feedstock gas. Under normal operating conditions, fuel gas valve II is closed, while the natural gas valve, fuel gas valve I, and feedstock gas valve are all open. At this time, some natural gas enters the main fuel gas pipe, and some natural gas enters the feedstock gas pipe. Thus, under start-up conditions, the natural gas valve or both fuel gas valve I and feedstock gas valve must fail simultaneously for natural gas to mix with the start-up circulating gas. This scheme effectively reduces the probability of accidents, improves system safety, and reduces safety risks.

[0006] Optionally, it also includes a decarbonization flash pipe, one end of which is connected to the exhaust port of the decarbonization unit, and the other end of which is connected to the main fuel gas pipe. The connection point between the decarbonization flash pipe and the main fuel gas pipe is located between the pressure reducing valve and the fuel gas separator.

[0007] In this scheme, the decarbonization flash vapor generated during the CO2 removal process of the syngas in the decarbonization unit enters the fuel gas separator through the decarbonization flash vapor pipe and finally enters the heating furnace for combustion. This reduces energy waste caused by emissions to the flare and decreases the consumption of natural gas as fuel gas. Furthermore, under normal operating conditions, the natural gas is heated using a natural gas heater, which increases the temperature of the fuel gas after pressure reduction and prevents moisture in the decarbonization flash vapor from condensing.

[0008] Optionally, it also includes a methane-rich gas pipe, one end of which is connected to the methane outlet of the H2 / CO cryogenic separation unit, and the other end of which is connected to the main fuel gas pipe. The connection point between the methane-rich gas pipe and the main fuel gas pipe is located between the pressure reducing valve and the fuel gas separator.

[0009] In this scheme, the methane-rich gas from the H2 / CO cryogenic separation unit enters the fuel gas separator through the methane-rich gas pipe, and finally enters the heating furnace for combustion, thereby reducing energy waste caused by emissions to the flare and reducing the consumption of natural gas as fuel gas.

[0010] Optionally, it also includes a nitrogen-containing exhaust pipe, one end of which is connected to the tail gas emission port of the H2 / CO cryogenic separation unit, and the other end of which is connected to a methane-rich gas pipe.

[0011] In this scheme, the nitrogen-containing waste gas from the H2 / CO cryogenic separation unit enters the fuel gas separator through the nitrogen-containing waste gas pipe and the methane-rich gas pipe, and finally enters the heating furnace for combustion, thereby reducing energy waste caused by emissions to the flare and reducing the consumption of natural gas as fuel gas.

[0012] Optionally, it also includes a surplus hydrogen pipe, one end of which is connected to the hydrogen outlet of the PSA pressure swing adsorption unit, and the other end of which is connected to the main fuel gas pipe. The connection point between the surplus hydrogen pipe and the main fuel gas pipe is located between the pressure reducing valve and the fuel gas separator. In this scheme, the excess hydrogen from the PSA pressure swing adsorption unit enters the fuel gas separator through the excess hydrogen pipe, and finally enters the heating furnace for combustion, thereby reducing energy waste caused by discharge to the flare and reducing the consumption of natural gas as fuel gas. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the fuel system for a natural gas to syngas production device according to Embodiment 1 of this utility model. Detailed Implementation

[0014] The following detailed description illustrates the specific implementation method: The markings in the accompanying drawings include: natural gas heater 1, fuel gas separator 2, heating furnace 3, decarbonization flash vapor pipe 4, methane-rich gas pipe 5, nitrogen-containing waste gas pipe 6, surplus hydrogen pipe 7, natural gas inlet pipe 8, natural gas valve 9, feed gas pipe 10, feed gas valve 11, main fuel gas pipe 12, fuel gas valve I 13, pressure reducing valve 14, start-up fuel gas pipe 15, fuel gas valve II 16, decarbonization unit 17, H2 / CO cryogenic separation unit 18, PSA pressure swing adsorption unit 19, converter 20, start-up circulating gas pipe 21, compressor 22, and circulating gas valve 23.

[0015] Example 1 This embodiment is basically as follows: Figure 1 The diagram shows a fuel system for a natural gas-to-syngas production plant, comprising a natural gas heater 1, a fuel gas separator 2, a heater 3, a decarbonization flash vapor pipe 4, a methane-rich gas pipe 5, a nitrogen-containing waste gas pipe 6, and a surplus hydrogen pipe 7. The inlet end of the natural gas heater 1 is connected to a natural gas inlet pipe 8, on which a natural gas valve 9 is installed. The outlet end of the natural gas heater 1 is connected to a feed gas pipe 10, on which a feed gas valve 11 is installed. The end of the feed gas pipe 10 furthest from the natural gas heater 1 is connected to the feed gas inlet end of the heater 3. A main fuel gas pipe 12 connects the feed gas pipe 10 between the feed gas valve 11 and the natural gas heater 1. A fuel gas valve 13 and a pressure reducing valve 14 are installed on the main fuel gas pipe 12. The end of the main fuel gas pipe 12 furthest from the feed gas pipe 10 is connected to the fuel gas separator 2. The fuel gas separator 2 is connected to the fuel gas inlet end of the heater 3 via a pipeline.

[0016] A start-up fuel gas pipe 15 is connected between the natural gas inlet pipe 8 and the main fuel gas pipe 12. The connection point between the start-up fuel gas pipe 15 and the natural gas inlet pipe 8 is located on the side of the natural gas valve 9 away from the natural gas heater 1. The connection point between the start-up fuel gas pipe 15 and the main fuel gas pipe 12 is located on the side of the fuel gas valve I 13 away from the raw material gas pipe 10. A fuel gas valve II 16 is installed on the start-up fuel gas pipe 15.

[0017] One end of the decarbonization flash vapor pipe 4 is connected to the tail gas outlet of the decarbonization unit 17, and the other end is connected to the main fuel gas pipe 12. The connection point between the decarbonization flash vapor pipe 4 and the main fuel gas pipe 12 is located between the pressure reducing valve 14 and the fuel gas separator 2. One end of the methane-rich gas pipe 5 is connected to the methane outlet of the H2 / CO cryogenic separation unit 18, and the other end is connected to the main fuel gas pipe 12. The connection point between the methane-rich gas pipe 5 and the main fuel gas pipe 12 is located between the pressure reducing valve 14 and the fuel gas separator 2. One end of the nitrogen-containing waste gas pipe 6 is connected to the tail gas outlet of the H2 / CO cryogenic separation unit 18, and the other end is connected to the methane-rich gas pipe 5. One end of the surplus hydrogen pipe 7 is connected to the hydrogen outlet of the PSA pressure swing adsorption unit 19, and the other end of the surplus hydrogen pipe 7 is connected to the main fuel gas pipe 12. The connection point between the surplus hydrogen pipe 7 and the main fuel gas pipe 12 is located between the pressure reducing valve 14 and the fuel gas separator 2.

[0018] In addition, the converter 20 in the natural gas to syngas unit is located between the heater 3 and the decarbonization unit 17. The feed gas from the heater 3 enters the converter 20 for reaction to obtain syngas, which then enters the decarbonization unit 17. The decarbonization unit 17 is also connected to the start-up circulating gas pipe 21, which is equipped with a compressor 22 and a circulating gas valve 23. Thus, under start-up conditions, the start-up circulating gas circulates in the loop formed by the heater 3, converter 20, decarbonization unit 17, compressor 22, and start-up circulating gas pipe 21 under the action of the compressor 22.

[0019] In actual use, under start-up conditions, natural gas valve 9, fuel gas valve I 13, and feedstock gas valve 11 are all closed, while fuel gas valve II 16 and recirculation gas valve 23 are all open. Thus, high-pressure natural gas enters the main fuel gas pipe 12 via start-up fuel gas pipe 15, and after being depressurized by pressure reducing valve 14, it enters the fuel gas separator 2, and finally enters the heater 3 for combustion, heating the start-up recirculation gas / feedstock gas entering the heater 3. Simultaneously, the start-up recirculation gas enters the heater 3 and circulates in the loop formed by the heater 3, converter 20, decarbonization unit 17, compressor 22, and start-up recirculation gas pipe 21. Therefore, under start-up conditions, both natural gas valve 9 and feedstock gas valve 11 (or fuel gas valve I 13 and feedstock gas valve 11) must fail simultaneously for natural gas to mix with the start-up recirculation gas, effectively reducing the probability of accidents and improving safety.

[0020] After the natural gas to syngas conversion enters normal operating conditions, fuel gas valve II 16 and circulating gas valve 23 are both closed, while natural gas valve 9, fuel gas valve I 13, and feedstock gas valve 11 are all open. Thus, high-pressure natural gas, after preheating in natural gas heater 1, enters furnace 3 via feedstock gas pipe 10, and the other part enters fuel gas separator 2 via main fuel gas pipe 12. The natural gas entering furnace 3 via feedstock gas pipe 10 serves as feedstock gas, and after heating, it enters reformer 20 to react and produce syngas. The syngas then enters a decarbonization unit to remove CO2, and subsequently enters H2 / CO cryogenic separation unit 18 and PSA pressure swing adsorption unit 19 to separate H2 and CO for ethylene glycol synthesis. Simultaneously, the natural gas entering fuel gas separator 2 via main fuel gas pipe 12 serves as fuel gas, entering furnace 3 for combustion to heat the feedstock gas.

[0021] In the above process, the decarbonization flash vapor from decarbonization unit 17 enters fuel gas separator 2 via decarbonization flash vapor pipe 4; the methane-rich gas from H2 / CO cryogenic separation unit 18 enters fuel gas separator 2 via methane-rich gas pipe 5; the nitrogen-containing waste gas from H2 / CO cryogenic separation unit 18 enters fuel gas separator 2 via nitrogen-containing waste gas pipe 6 and methane-rich gas pipe 5; and the excess gas pipe and excess hydrogen pipe 7 from PSA pressure swing adsorption unit 19 enter fuel gas separator 2. Thus, this embodiment heats the fuel natural gas and uses the decarbonization flash vapor, methane-rich gas, nitrogen-containing waste gas, and excess hydrogen as fuel gas, which not only reduces the risk of decarbonization flash vapor condensation and energy waste but also reduces the amount of natural gas consumed as fuel gas, thereby lowering production costs.

[0022] The above descriptions are merely embodiments of this utility model, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of this utility model, and these should also be considered within the scope of protection of this utility model. These modifications will not affect the effectiveness or practicality of this utility model. The specific embodiments described in the specification can be used to interpret the claims.

Claims

1. A fuel system for a natural gas to syngas production plant, comprising a natural gas heater, a fuel gas separator, and a furnace, wherein the inlet end of the natural gas heater is connected to a natural gas inlet pipe, the outlet end of the natural gas heater is connected to a raw material gas pipe, the end of the raw material gas pipe away from the natural gas heater is connected to the raw material gas inlet end of the furnace, the raw material gas pipe is connected to a main fuel gas pipe, the end of the main fuel gas pipe away from the raw material gas pipe is connected to the fuel gas separator, the fuel gas separator is connected to the fuel gas inlet end of the furnace via a pipeline, a natural gas valve is installed on the natural gas inlet pipe, a raw material gas valve is installed on the raw material gas pipe, and a fuel gas valve I and a pressure reducing valve are installed on the main fuel gas pipe; characterized in that: The natural gas inlet pipe is connected to the main fuel gas pipe by a start-up fuel gas pipe. The connection point between the start-up fuel gas pipe and the natural gas inlet pipe is located on the side of the natural gas valve away from the natural gas heater. The connection point between the start-up fuel gas pipe and the main fuel gas pipe is located on the side of fuel gas valve I away from the raw material gas pipe. Fuel gas valve II is installed on the start-up fuel gas pipe.

2. The fuel system for a natural gas to syngas plant of claim 1, wherein: It also includes a decarbonization flash pipe, one end of which is connected to the exhaust port of the decarbonization unit, and the other end of which is connected to the main fuel gas pipe. The connection point between the decarbonization flash pipe and the main fuel gas pipe is located between the pressure reducing valve and the fuel gas separator.

3. The fuel system for a natural gas to syngas plant of claim 1, wherein: It also includes a methane-rich gas pipe, one end of which is connected to the methane outlet of the H2 / CO cryogenic separation unit, and the other end of which is connected to the main fuel gas pipe. The connection point between the methane-rich gas pipe and the main fuel gas pipe is located between the pressure reducing valve and the fuel gas separator.

4. The fuel system for a natural gas to syngas plant of claim 3, wherein: It also includes a nitrogen-containing waste gas pipe, one end of which is connected to the tail gas emission port of the H2 / CO cryogenic separation unit, and the other end of which is connected to a methane-rich gas pipe.

5. The fuel system for a natural gas to syngas plant of claim 1 wherein: It also includes a surplus hydrogen pipe, one end of which is connected to the hydrogen outlet of the PSA pressure swing adsorption unit, and the other end of which is connected to the main fuel gas pipe. The connection point between the surplus hydrogen pipe and the main fuel gas pipe is located between the pressure reducing valve and the fuel gas separator.

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