Recovery processing device for methane in liquid nitrogen wash feed gas
By improving the methane recovery and treatment device in the liquid nitrogen washing feed gas, the cold energy provided by the low-temperature nitrogen washing gas and the liquid nitrogen separator is used to cool the feed gas, which solves the problem of high energy consumption after methane separation in the liquid nitrogen washing feed gas, and achieves energy consumption reduction and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HENAN JINMEI TIANQING COAL CHEMICAL CO LTD
- Filing Date
- 2025-02-28
- Publication Date
- 2026-05-08
AI Technical Summary
In existing technologies, the separation of methane from the raw gas after liquid nitrogen washing requires gasification, which consumes a large amount of electricity, resulting in high energy consumption and high costs.
The improved liquid nitrogen washing feed gas methane recovery and treatment device utilizes the low-temperature nitrogen washing gas, fuel gas and liquid nitrogen separator at the top of the nitrogen washing tower to provide cooling for the feed gas. The gas-liquid mixed feed gas is separated into liquid methane fraction in the cooler and returned to the cooler for further cooling. The liquid methane is pressurized and directly sent to the natural gas pipeline network. The reheating process provides cooling to reduce energy consumption.
This reduces the energy consumption of pressurizing liquid methane for delivery into the natural gas pipeline network, achieving the goal of energy conservation and consumption reduction, and lowering production costs.
Smart Images
Figure CN224207709U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of chemical production equipment technology, specifically relating to a device for recovering and treating methane from raw gas washed with liquid nitrogen. Background Technology
[0002] After the liquid nitrogen washing feed gas enters the cold box, it still contains impurity gases such as CO, CH4, and Ar. In order to finally prepare a pure synthesis gas with a hydrogen-nitrogen ratio of 3:1, the impurity gases such as CO, CH4, and Ar need to be removed in the cold box. The removed CO, CH4, etc. are depressurized, separated, and reheated, and the gas phase is returned to the upstream conversion section.
[0003] The CH4 gas treatment method in the liquid nitrogen scrubbing feed gas is as follows: The feed gas is sent to feed gas coolers No. 1 and No. 2 in the cold box, where it is cooled by the backflowing nitrogen scrubbing gas, fuel gas and methane fraction. It flows out of feed gas cooler No. 2 with the gas flow and enters the feed gas separator to separate the liquid methane fraction. Then it returns to feed gas cooler No. 2 for further cooling. Then it enters the lower section of the nitrogen scrubbing tower. The separated liquid methane is mixed with the liquid methane coming out of the lower part of the feed gas separator in the methane-rich gas separator. After reheating to recover the cold energy, it is sent to the methane-rich compressor. The methane-rich compressor pressurizes the gas from 40 kPa to 5.5 MPa and sends it into the natural gas pipeline network.
[0004] However, in the original process unit, after the liquid methane in the feed gas from the liquid nitrogen washing process is separated, it needs to be vaporized first and then sent to the natural gas pipeline network by a motor or steam to do a lot of work. This process consumes a lot of electricity, resulting in high energy consumption and high cost.
[0005] Therefore, there is an urgent need for a device to recover and process methane from the raw gas after liquid nitrogen washing, in order to solve the above problems. Utility Model Content
[0006] To address the aforementioned deficiencies in existing technologies, this invention provides a methane recovery and treatment device for liquid nitrogen scrubbing feed gas. The device includes a liquid nitrogen scrubbing feed gas system, a feed gas separator, a nitrogen scrubbing tower, a liquid methane pump, a high-pressure nitrogen cooler, a first feed gas cooler, a second feed gas cooler, and a methane gas pipeline network. The liquid nitrogen scrubbing feed gas system is connected to the inlet of the feed gas separator via a feed gas pipeline, which sequentially passes through the first and second feed gas coolers. Branch feed gas pipelines are also connected to the feed gas pipeline. The top of the feed gas separator is connected to the lower section of the nitrogen scrubbing tower via the first outlet pipeline. The lower section of the nitrogen scrubbing tower is more than 90% liquid methane, with a small amount of liquid nitrogen and liquid carbon monoxide. The bottom of the feed gas separator is connected to the inlet of the liquid methane pump via the second outlet pipeline. The bottom of the nitrogen scrubbing tower is connected to the second outlet pipeline via the first methane pipeline. The outlet of the liquid methane pump is connected to the methane gas pipeline network via the second methane pipeline. The second methane pipeline passes through the second feed gas cooler, the first feed gas cooler, and the high-pressure nitrogen cooler in sequence.
[0007] Optionally, the methane recovery and treatment device in the liquid nitrogen washing feed gas is equipped with a high-pressure nitrogen system and a synthesis system. The high-pressure nitrogen system is connected to the upper section of the nitrogen washing tower through a first nitrogen pipeline, and the first nitrogen pipeline passes through a high-pressure nitrogen cooler, a first feed gas cooler and a second feed gas cooler in sequence. The top of the nitrogen washing tower is connected to the synthesis system through a second nitrogen pipeline, and the second nitrogen pipeline passes through a second feed gas cooler, a first feed gas cooler and a high-pressure nitrogen cooler in sequence.
[0008] Optionally, the methane recovery and treatment device in the liquid nitrogen washing feed gas is equipped with a fuel gas separator and a fuel gas system. The inlet of the fuel gas separator is connected to the lower section of the nitrogen washing tower through a first fuel gas pipeline, and the outlet of the fuel gas separator is connected to the fuel gas system through a second fuel gas pipeline. The second fuel gas pipeline passes through the second feed gas cooler, the first feed gas cooler, and the high-pressure nitrogen cooler in sequence.
[0009] Optionally, the methane recovery and treatment device in the liquid nitrogen washing feed gas is also equipped with a liquid nitrogen separator and an exhaust fan. The inlet of the liquid nitrogen separator is connected to a liquid nitrogen pipeline, which introduces a stream of liquid nitrogen from the outside and provides cooling capacity to the device through the phase change principle. The outlet of the liquid nitrogen separator is connected to the exhaust fan through a third nitrogen pipeline, and the third nitrogen pipeline passes through the second feed gas cooler, the first feed gas cooler and the high-pressure nitrogen cooler in sequence. The nitrogen is vented after releasing all the cooling capacity.
[0010] Optionally, the liquid nitrogen separator is also connected to a circulation pipeline that passes through a second feed gas cooler.
[0011] This invention also includes other components that enable the normal operation of a methane recovery and treatment device for liquid nitrogen washing feed gas, all of which are conventional techniques in the art. Furthermore, any devices or components not specified in this invention employ conventional techniques in the art.
[0012] The working principle of this invention is as follows: the raw gas of the liquid nitrogen scrubbing raw gas system passes sequentially through the first and second raw gas coolers via the raw gas pipeline. The low-temperature nitrogen scrubbing gas from the top of the nitrogen scrubbing tower, the low-temperature fuel gas separated by the fuel gas separator, and the low-temperature nitrogen gas from the top of the liquid nitrogen separator flow back through the second nitrogen pipeline, the second fuel gas pipeline, and the third nitrogen pipeline, respectively, to provide cooling to the first and second raw gas coolers, thereby cooling the passing raw gas. The gas-liquid mixed raw gas flows out of the second raw gas cooler with the gas flow and enters the raw gas separation tank to separate the liquid methane distillate. After separation, the gaseous gas returns to the second feed gas cooler for further cooling. Then, the feed gas enters the lower section of the nitrogen scrubbing tower. The separated liquid methane, along with the liquid methane from the bottom of the feed gas separator, is fed into the liquid methane pump. After being pressurized by the liquid methane pump, the gaseous gas passes through the second feed gas cooler, the first feed gas cooler, and the high-pressure nitrogen cooler in sequence for reheating. The reheated gaseous methane is directly fed into the methane pipeline network. At the same time, the reheating process also provides cooling for subsequent feed gas. After releasing their cooling capacity, the nitrogen scrubbing gas, fuel gas, and nitrogen are sent to the synthesis system, fuel gas system, and exhaust fan, respectively. Some of the nitrogen scrubbing gas is also sent to the methanol scrubbing system.
[0013] The beneficial effect of this utility model is that it solves the problem of high energy consumption in the original process. The improved technology only requires less electricity to pressurize liquid methane and send it into the natural gas pipeline network, which can greatly reduce energy consumption, reduce production costs, and achieve the goal of energy saving and consumption reduction. Attached Figure Description
[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0015] Figure 1 This is a schematic diagram of the overall structure of this utility model. Detailed Implementation
[0016] The present invention will now be clearly described with reference to the accompanying drawings and specific embodiments. This description is merely for explaining the present invention and is not intended to limit it. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art based on the embodiments of the present invention without inventive effort to obtain all other embodiments should be included within the protection scope of the present invention.
[0017] Example
[0018] like Figure 1 As shown, this utility model embodiment provides a methane recovery and treatment device for liquid nitrogen washing feed gas, including a liquid nitrogen washing feed gas system 1, a feed gas separator S-61601, a nitrogen washing tower T-61601, a liquid methane pump 2, a high-pressure nitrogen cooler E-61604, a first feed gas cooler E-61605, a second feed gas cooler E-61606, and a methane gas pipeline network 3. The liquid nitrogen washing feed gas system 1 is connected to the inlet of the feed gas separator S-61601 through a feed gas pipeline K-1, and the feed gas pipeline K-1 passes sequentially through the first feed gas cooler E-61605 and the second feed gas cooler E-61606. A feed gas branch pipeline is also connected to the feed gas pipeline K-1. The feed gas separator S-61604... The top of 61601 is connected to the lower section of nitrogen scrubbing tower T-61601 via the first outlet pipe K-2. The lower section of nitrogen scrubbing tower T-61601 is more than 90% liquid methane, with a small amount of liquid nitrogen and liquid carbon monoxide. The bottom of raw material gas separator S-61601 is connected to the inlet of liquid methane pump 2 via the second outlet pipe K-3. The bottom of nitrogen scrubbing tower T-61601 is connected to the second outlet pipe K-3 via the first methane pipe K-4. The outlet of liquid methane pump 2 is connected to methane gas network 3 via the second methane pipe K-5. The second methane pipe K-5 passes through the second raw material gas cooler E-61606, the first raw material gas cooler E-61605, and the high-pressure nitrogen cooler E-61604 in sequence.
[0019] In addition, the methane recovery and treatment device in the liquid nitrogen washing feed gas is equipped with a high-pressure nitrogen system 4 and a synthesis system 5. The high-pressure nitrogen system 4 is connected to the upper section of the nitrogen washing tower T-61601 through the first nitrogen pipeline K-6, and the first nitrogen pipeline K-6 passes through the high-pressure nitrogen cooler E-61604, the first feed gas cooler E-61605 and the second feed gas cooler E-61606 in sequence. The top of the nitrogen washing tower T-61601 is connected to the synthesis system 5 through the second nitrogen pipeline K-7, and the second nitrogen pipeline K-7 passes through the second feed gas cooler E-61606, the first feed gas cooler E-61605 and the high-pressure nitrogen cooler E-61604 in sequence.
[0020] Meanwhile, the methane recovery and treatment device in the liquid nitrogen washing feed gas is equipped with a fuel gas separator S-61604 and a fuel gas system 6. The inlet of the fuel gas separator S-61604 is connected to the lower section of the nitrogen washing tower T-61601 through the first fuel gas pipeline K-8, and the outlet of the fuel gas separator S-61604 is connected to the fuel gas system 6 through the second fuel gas pipeline K-9. The second fuel gas pipeline K-9 passes through the second feed gas cooler E-61606, the first feed gas cooler E-61605, and the high-pressure nitrogen cooler E-61604 in sequence.
[0021] In addition, the methane recovery and treatment unit for the liquid nitrogen scrubbing feed gas is equipped with a liquid nitrogen separator S-61602 and an exhaust fan 7. The inlet of the liquid nitrogen separator S-61602 is connected to a liquid nitrogen pipeline K-10, which introduces liquid nitrogen from the outside to provide cooling for the unit through the phase change principle. The outlet of the liquid nitrogen separator S-61602 is connected to the exhaust fan 7 through a third nitrogen pipeline K-11, which passes sequentially through the second feed gas cooler E-61606, the first feed gas cooler E-61605, and the high-pressure nitrogen cooler E-61604. The nitrogen is vented after releasing its cooling capacity. The liquid nitrogen separator S-61602 is also connected to a circulation pipeline K-12, which passes through the second feed gas cooler E-61606.
[0022] The working principle of this invention is as follows: the raw gas from the liquid nitrogen washing raw gas system 1 passes sequentially through the first raw gas cooler E-61605 and the second raw gas cooler E-61606 via the raw gas pipeline K-1. The low-temperature nitrogen washing gas from the top of the nitrogen washing tower T-61601, the low-temperature fuel gas separated by the fuel gas separator S-61604, and the low-temperature nitrogen gas from the top of the liquid nitrogen separator S-61602 flow back through the second nitrogen pipeline K-7, the second fuel gas pipeline K-9, and the third nitrogen pipeline K-11 to provide cooling capacity to the first raw gas cooler E-61605 and the second raw gas cooler E-61606, thereby cooling the passing raw gas. The gas-liquid mixed raw gas flows out of the second raw gas cooler E-61606 with the gas flow and enters the raw gas separator S-6. After the liquid methane fraction is separated in section 1601, it is returned to the second feed gas cooler E-61606 for further cooling. Then, the feed gas enters the lower section of nitrogen scrubbing tower T-61601. The separated liquid methane and the liquid methane from the lower part of feed gas separator S-61601 are sent to liquid methane pump 2. After being pressurized by liquid methane pump 2, it passes through the second feed gas cooler E-61606, the first feed gas cooler E-61605 and the high-pressure nitrogen cooler E-61604 for reheating. The reheated gaseous methane is directly sent to methane pipeline 3. At the same time, the reheating process can also provide cooling for subsequent feed gas. After the nitrogen scrubbing gas, fuel gas and nitrogen have released their cooling capacity, they are sent to synthesis system 5, fuel gas system 6 and exhaust fan 7 for venting, respectively. Some of the nitrogen scrubbing gas is also sent to methanol scrubbing system 8.
[0023] The embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.
Claims
1. A device for recovering methane from liquid nitrogen scrubbing feed gas, comprising a liquid nitrogen scrubbing feed gas system, a feed gas separator, a nitrogen scrubbing tower, a liquid methane pump, a high-pressure nitrogen cooler, a first feed gas cooler, a second feed gas cooler, a methane gas pipeline network, a high-pressure nitrogen system, a synthesis system, a fuel gas separator, a fuel gas system, a liquid nitrogen separator, and an exhaust fan, characterized in that: The liquid nitrogen scrubbing gas system is connected to the inlet of the raw gas separator via a raw gas pipeline. The raw gas pipeline passes through the first raw gas cooler and the second raw gas cooler in sequence. The top of the raw gas separator is connected to the lower section of the nitrogen scrubbing tower via the first outlet pipeline. The bottom of the raw gas separator is connected to the inlet of the liquid methane pump via the second outlet pipeline. The bottom of the nitrogen scrubbing tower is connected to the second outlet pipeline via the first methane pipeline. The outlet of the liquid methane pump is connected to the methane gas network via the second methane pipeline. The second methane pipeline passes through the second raw gas cooler, the first raw gas cooler, and the high-pressure nitrogen cooler in sequence. The high-pressure nitrogen system is connected to the upper section of the nitrogen scrubbing tower through the first nitrogen pipeline, and the first nitrogen pipeline passes through the high-pressure nitrogen cooler, the first raw material gas cooler and the second raw material gas cooler in sequence. The top of the nitrogen scrubbing tower is connected to the synthesis system through the second nitrogen pipeline, and the second nitrogen pipeline passes through the second raw material gas cooler, the first raw material gas cooler and the high-pressure nitrogen cooler in sequence. The inlet of the fuel gas separator is connected to the lower section of the nitrogen scrubbing tower through the first fuel gas pipeline, and the outlet of the fuel gas separator is connected to the fuel gas system through the second fuel gas pipeline. The second fuel gas pipeline passes through the second raw material gas cooler, the first raw material gas cooler and the high-pressure nitrogen cooler in sequence. The inlet of the liquid nitrogen separator is connected to a liquid nitrogen pipeline, and the outlet of the liquid nitrogen separator is connected to the exhaust fan through a third nitrogen pipeline. The third nitrogen pipeline passes through the second raw material gas cooler, the first raw material gas cooler, and the high-pressure nitrogen cooler in sequence. The liquid nitrogen separator is also connected to a circulation pipeline, which passes through the second raw material gas cooler.