CN113694718A

CN113694718A - Process and equipment for extracting helium from helium-poor BOG gas

Info

Publication number: CN113694718A
Application number: CN202110965971.XA
Authority: CN
Inventors: 王海; 郑峰; 齐昊然; 李一鸣
Original assignee: Dalian Haiaohao Membrane Technology Co ltd
Current assignee: Dalian Haiaohao Membrane Technology Co ltd
Priority date: 2021-08-23
Filing date: 2021-08-23
Publication date: 2021-11-26

Abstract

The invention discloses a process and equipment for extracting helium from a helium-poor BOG gas, wherein the process comprises the steps of compressing the BOG raw material gas, performing primary membrane separation, performing catalytic dehydrogenation, performing molecular sieve dehydration, performing secondary membrane separation and performing helium refining to purify the helium-poor high-purity helium in the BOG raw material gas, wherein separated non-permeation gas mainly comprises methane and is sent to a fuel gas pipe network.

Description

Process and equipment for extracting helium from helium-poor BOG gas

Technical Field

The invention relates to the technical field of extracting helium from BOG gas, in particular to a process and equipment for extracting helium from poor-helium BOG gas.

Background

Helium belongs to the noble gases and is one of the most important industrial gas species. In the semiconductor industry, high purity helium is used as a shielding gas for growing germanium and silicon crystals. Bottom gas of some mixed gas, inert gas of cleaning, shielding and pressurizing system; gas chromatography carrier gas; as a shielding gas in the production of reactive metals such as titanium and zirconium; shielding gas for electric arc welding; as a cooling medium for gases in nuclear reactors; a helium-filled spacecraft; fluorescent lamp tubes filled in cold weather; filling neutrons and a gas thermometer; helium mass spectrometer leak detection of equipment, pipelines and the like; mixing with oxygen for medical treatment; in the aerospace technology, air in a vacuum pipeline, a storage tank, a tank car and a rocket storage tank of a liquid hydrogen filling system must be replaced by high-purity nitrogen firstly, and after the air is qualified, the air is replaced by high-purity helium, and after the air is qualified, the air is sealed by high-purity helium; it can also be used as the extruding air source of satellite and rocket and the air source for attitude control engine. Liquid helium is mainly used in superconducting technology and Magnetic Resonance Imaging (MRI). The superconducting particle accelerator uses liquid helium to cool the superconducting magnet.

The helium gas production methods mainly include 4 methods, namely a natural gas separation method, an ammonia synthesis method (in ammonia synthesis, helium separated and purified from tail gas), an air fractionation method, and a uranium ore method. Among them, the natural gas separation method is currently the only method for industrially obtaining helium. In view of this, the upstream of the helium industry chain is mainly the industries of natural gas, air separation equipment and the like, and the downstream is various application industries.

Because the processes for liquefying natural gas into LNG are different, the LNG storage tanks of the liquefaction plants have different structures, so that helium in the BOG gas of the LNG storage tanks of most LNG liquefaction plants is only about 1 percent, and the BOG gas belongs to low-helium BOG gas, and has the defects of large methane composition and small hydrogen composition.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a process and equipment for extracting helium from a helium-poor BOG gas, which solve the problems of low hydrogen content and large direct catalytic treatment capacity in the helium-poor BOG feed gas.

In order to achieve the purpose, the invention is realized by the following technical scheme: a process for extracting helium from a helium-depleted BOG gas, comprising the steps of: BOG raw gas is sent from an LNG storage tank to a BOG raw gas compressor through a pipeline, the outlet of the BOG raw gas compressor is connected with a front heat exchanger of a primary membrane separator, the outlet of a front heater of the primary membrane separator is connected with the primary membrane separator, non-permeable gas of the primary membrane separator mainly comprises nitrogen and methane and is sent to a fuel gas pipe network, the outlet of the permeable gas of the primary membrane separator is connected with a permeable gas compressor of the primary membrane separator, the outlet of the permeable gas compressor of the primary membrane separator is connected with a catalytic dehydrogenation reactor, oxygen is simultaneously introduced into the catalytic dehydrogenation reactor for catalytic reaction, the concentration of hydrogen in the BOG raw gas is controlled within 0.1ppm, the outlet of the catalytic dehydrogenation reactor is connected with a molecular sieve dehydrator, water generated by the catalytic dehydrogenation reactor is removed to be below 1ppm, the outlet of the molecular sieve dehydrator is connected with the front heat exchanger of a secondary membrane separator to heat the BOG raw gas, and the outlet of the front heat exchanger of the secondary membrane separator is connected with a secondary membrane separator, and the non-permeation gas of the secondary membrane separator is sent to a front heat exchanger of the primary membrane separator, is mixed with BOG feed gas and then is separated again, the permeation gas outlet of the secondary membrane separator is connected to a crude helium compressor, the outlet of the crude helium compressor is connected with a helium purifier, and pure helium at the outlet of the helium purifier is sent to a helium bottle for storage through a digital display type gas supply busbar system after being boosted by the compressor.

Preferably, the process and the equipment for extracting the helium from the helium-poor BOG gas keep the original BOG fuel gas pipeline, a helium extracting device is newly connected to the pipeline, and the process is selected by a hand valve.

Preferably, the BOG raw material gas pressure is 0.02-0.05 MPaG, the helium content is 1-3% (v), and the hydrogen content is 0.1-0.3% (v).

Preferably, the gas pressure after the BOG raw material gas compressor is 0.7-1.5 MPaG.

Preferably, the compressor is provided for standby.

Preferably, the heat exchanger is steam heating or electric heating.

Preferably, the non-permeate gas of the primary membrane separator is sent to a fuel gas pipe network. The helium content of the permeation gas of the first-stage membrane separator is more than 15% (v).

Preferably, the primary membrane separator can be a single membrane separation device or a multi-stage membrane separation device.

Preferably, the gas pressure after the first-stage membrane permeation gas compressor is 0.9-1.7 MPaG.

Preferably, the compressor is provided for standby.

Preferably, the temperature of the catalytic dehydrogenation reactor is controlled below 200 ℃, so that hydrogen is oxidized, methane is not oxidized, and the concentration of outlet hydrogen is below 0.1 ppm.

Preferably, the oxidant of the catalytic dehydrogenation reactor is pure oxygen or air.

Preferably, the molecular sieve dryer adopts porous aluminosilicate crystals, and the water content of gas passing through the molecular sieve dryer is less than or equal to 1 ppm.

Preferably, the non-permeate gas of the secondary membrane separator is sent to the front of the heat exchanger inlet of the primary membrane separator. The helium content of the permeation gas of the secondary membrane separator is more than 90% (v).

Preferably, the secondary membrane separator may be a single membrane separation device or a multi-stage membrane separation device.

Preferably, the gas pressure after the crude helium compressor is 0.8-1.6 MPaG.

Preferably, the compressor is provided for standby.

Preferably, the helium purifier comprises a pressure swing adsorption purifier and a cryogenic condensation purifier.

Preferably, the helium purifier can remove nitrogen, oxygen and methane in the crude helium gas to make the helium concentration reach 99.999%.

Preferably, the helium booster outlet pressure is 16.0 MPaG.

Preferably, the digital display type gas supply bus system comprises a safety valve and an instrument.

Preferably, the helium bottle is a 40L or 50L standard gas bottle.

The utility model provides an equipment of gaseous helium of carrying of BOG of poor helium, equipment include BOG feed gas compressor, BOG feed gas compressor input is connected with the admission line, be connected with the fuel gas pipe network on the admission line, be equipped with first hand valve on the fuel gas pipe network, the admission line just is located fuel gas pipe network one side department and is equipped with the second hand valve, BOG feed gas compressor output passes through the preceding heat exchanger of pipe connection one-level membrane separator, the first-level membrane separator of heat exchanger exit linkage before the one-level membrane, the non-permeate gas export of one-level membrane separator communicates with the fuel gas pipe network through the connecting tube, be equipped with the third hand valve on the connecting tube, the one-level membrane separator permeate gas export passes through the one-level membrane permeate gas compressor of pipe connection, one-level membrane permeate gas compressor exit linkage catalytic dehydrogenation reactor, the last oxygen admission pipe of connecting of catalytic dehydrogenation reactor, the catalytic dehydrogenation reactor outlet is connected with the molecular sieve dehydrator through a pipeline, the outlet of the molecular sieve dehydrator is connected with the front heat exchanger of the secondary membrane separator through a pipeline, the outlet of the front heat exchanger of the secondary membrane separator is connected with the secondary membrane separator through a pipeline, the non-permeation gas outlet of the secondary membrane separator is communicated with the inlet end pipeline of the front heat exchanger of the primary membrane separator, the permeation gas outlet of the secondary membrane separator is connected with the crude helium compressor through a pipeline, the outlet of the crude helium compressor is connected with the helium purifier through a pipeline, the outlet of the helium purifier is connected with the helium booster through a pipeline, the outlet of the helium booster is connected with the digital display type gas supply busbar system, and the outlet of the digital display type gas supply busbar system is connected with the helium bottle.

Advantageous effects

1. The BOG raw material gas is compressed by a BOG raw material gas compressor and then is subjected to primary membrane separation, helium and hydrogen are preliminarily concentrated, the concentration of the hydrogen is still outside an explosion danger area, and then dehydrogenation is carried out, so that the volume of the BOG raw material gas is reduced, and the equipment volume of a dehydrogenation reactor is further reduced.

2. Compared with the conventional membrane method, the method improves the pure helium without adding new equipment, can reduce the volume of a catalytic dehydrogenation reactor and a molecular sieve dehydrator, and reduces the cost of equipment and a catalyst.

3. According to the invention, the molecular sieve dehydrator is arranged behind the dehydrogenation reactor, so that the generated water of the dehydrogenation reactor is separated out of the device, and the phenomenon that the subsequent device generates condensed water to influence the use of a compressor and the separation efficiency of a membrane is prevented.

4. By adopting a multistage membrane process, the non-permeation gas of the subsequent membrane returns to the inlet of the first-stage membrane separator for multiple times of separation, so that the recovery rate of helium is ensured.

5. The invention has no phase change in the membrane separation process of concentrating crude helium from BOG feed gas, and reduces equipment investment and operation cost.

6. The invention adds a new interface on the original BOG fuel gas pipeline to concentrate helium in BOG raw material gas, and the loss of non-permeable gas after passing through a membrane separator is less than 5 percent.

7. The process is reasonable, and the effective components of the raw material gas are recycled to the maximum extent.

8. Low energy consumption, low investment and good product quality.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

In the figure: 1. a BOG feed gas compressor; 2. a front heat exchanger of a primary membrane separator; 3. a primary membrane separator; 4. a first stage membrane permeate gas compressor; 5. a catalytic dehydrogenation reactor; 6. a molecular sieve dehydrator; 7. a secondary membrane separator front heat exchanger; 8. a secondary membrane separator; 9. a crude helium compressor; 10. a helium purifier; 11. a helium booster; 12. a digital display type gas supply bus system; 13. a helium tank; v1, first hand valve; v2, second hand valve; v3, third hand valve.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example (b): as shown in fig. 1, a process and equipment for extracting helium from a helium-poor BOG gas mainly comprise a BOG raw gas compressor 1, a primary membrane separator front heat exchanger 2, a primary membrane separator 3, a primary membrane permeation gas compressor 4, a catalytic dehydrogenation reactor 5, a molecular sieve dehydrator 6, a secondary membrane separator front heat exchanger 7, a secondary membrane separator 8, a crude helium compressor 9, a helium purifier 10, a helium supercharger 11, a digital display type gas supply busbar system 12 and a helium tank 13; a first hand valve V1, a second hand valve V2, and a third hand valve V3.

The BOG raw material gas pressure from an LNG plant LNG storage tank is 0.02MPaG, the BOG raw material gas is conveyed to the vicinity of the device through a pipeline, the BOG raw material gas is compressed to 1.4MPaG through a BOG raw material gas compressor 1 and is sent to a front heat exchanger 2 of a first-stage membrane separator, the BOG raw material gas is heated to 65 ℃ by the front heat exchanger 2 of the first-stage membrane separator and is sent to a first-stage membrane separator 3, and non-permeable gas of the first-stage membrane separator 3 is sent to a fuel gas pipe network. The content of helium in the permeation gas of the primary membrane separator 3 is more than 15% (v), the permeation gas is sent to the inlet of the primary membrane permeation gas compressor 4, the outlet pressure of the primary membrane permeation gas compressor 4 is 1.6MPaG, the non-permeation gas pressure of the secondary membrane separator 8 after the permeation gas passes through the equipment is ensured to be more than 1.4MPaG, and therefore the helium is recovered again after the heat exchanger 2 and the BOG feed gas are mixed before returning to the primary membrane separator. The outlet of the first-stage membrane permeation gas compressor 4 is connected with a catalytic dehydrogenation reactor 5, meanwhile, oxygen (air) is added into the catalytic dehydrogenation reactor 5, and under the action of a catalyst, hydrogen and oxygen react to generate water, so that the aim of removing the hydrogen in the BOG raw material gas is fulfilled. The temperature of the catalytic dehydrogenation reactor 5 is controlled at 180 ℃, so that hydrogen is ensured to be oxidized, methane is not oxidized, and the condition of over-temperature of the catalytic dehydrogenation reactor 5 is prevented. The BOG raw material gas after passing through the catalytic dehydrogenation reactor 5 does not contain hydrogen and oxygen, so that the quality of high-purity helium is ensured, and the safe operation of a subsequent device is also ensured. And the BOG raw material gas enters a heat exchanger 7 before the secondary membrane separator, the dehydrogenated BOG raw material gas is heated to 65 ℃, then the BOG raw material gas enters a secondary membrane separator 8, the non-osmotic gas pressure of the secondary membrane separator 8 is not lost, and the BOG raw material gas is mixed with the BOG raw material gas and then concentrated again before being sent to an inlet of a heat exchanger 2 before the primary membrane separator. The content of helium in the permeation gas of the secondary membrane separator 8 is more than 90% (v), the permeation gas of the secondary membrane separator 8 is sent to a crude helium compressor 9, the crude helium compressor 9 compresses the crude helium to 1.5MPa (G) and sends the crude helium to a helium purifier 10, the process of the helium purifier 10 is selected according to the treatment capacity of BOG feed gas, if the amount of pure helium is small, the helium purifier 10 adopts a pressure swing adsorption process, and if the amount of pure helium is large, the helium purifier 10 adopts a cryogenic condensation process. The helium purifier 10 removes impurity gases from the crude helium gas to a helium concentration of 99.999%. The purified gas helium purified by the helium purifier 10 passes through a helium supercharger 11 to reach the gas pressure of 16.0 MPaG. Then the helium bottle 13 is filled through the digital display type gas supply busbar system 12.

When the BOG helium extracting device is put into use, the first hand valve V1 is closed, the second hand valve V2 is opened, the third hand valve V3 is opened, and the BOG purified helium system is put into use. When the BOG purification helium system is overhauled, the first hand valve V1 is opened, the second hand valve V2 is closed, the third hand valve V3 is closed, the BOG fuel gas pipe network can normally supply gas, and the use of subsequent users is not influenced.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation. The use of the phrase "comprising one of the elements does not exclude the presence of other like elements in the process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A process for extracting helium from a helium-depleted BOG gas, comprising the steps of: BOG raw gas is sent from an LNG storage tank to a BOG raw gas compressor through a pipeline, the outlet of the BOG raw gas compressor is connected with a front heat exchanger of a primary membrane separator, the outlet of a front heater of the primary membrane separator is connected with the primary membrane separator, non-permeable gas of the primary membrane separator mainly comprises nitrogen and methane and is sent to a fuel gas pipe network, the outlet of the permeable gas of the primary membrane separator is connected with a permeable gas compressor of the primary membrane separator, the outlet of the permeable gas compressor of the primary membrane separator is connected with a catalytic dehydrogenation reactor, oxygen is simultaneously introduced into the catalytic dehydrogenation reactor for catalytic reaction, the concentration of hydrogen in the BOG raw gas is controlled within 0.1ppm, the outlet of the catalytic dehydrogenation reactor is connected with a molecular sieve dehydrator, water generated by the catalytic dehydrogenation reactor is removed to be below 1ppm, the outlet of the molecular sieve dehydrator is connected with the front heat exchanger of a secondary membrane separator to heat the BOG raw gas, and the outlet of the front heat exchanger of the secondary membrane separator is connected with a secondary membrane separator, and the non-permeation gas of the secondary membrane separator is sent to a front heat exchanger of the primary membrane separator, is mixed with BOG feed gas and then is separated again, the permeation gas outlet of the secondary membrane separator is connected to a crude helium compressor, the outlet of the crude helium compressor is connected with a helium purifier, and pure helium at the outlet of the helium purifier is sent to a helium bottle for storage through a digital display type gas supply busbar system after being boosted by the compressor.

2. The process for extracting helium from the helium-depleted BOG gas as claimed in claim 1, wherein the BOG raw material gas has a pressure of 0.02-0.05 MPaG, a helium content of 1-3% (v), and a hydrogen content of 0.1-0.3% (v).

3. The process for extracting helium from a helium-depleted BOG gas according to claim 1, wherein the gas pressure after the BOG feed gas compressor is 0.7-1.5 MPaG, the gas pressure after the primary membrane permeation gas compressor is 0.9-1.7 MPaG, the gas pressure after the crude helium compressor is 0.8-1.6 MPaG, and the outlet pressure of the helium booster is 16.0 MPaG.

4. The process for extracting helium from helium-depleted BOG gas as claimed in claim 1, wherein the temperature of the catalytic dehydrogenation reactor is controlled below 200 ℃ to ensure that hydrogen is oxidized, methane is not oxidized, and the outlet hydrogen concentration is below 0.1 ppm.

5. The process for extracting helium from a helium-depleted BOG gas as claimed in claim 1, wherein the content of helium in the permeation gas of the primary membrane separator is more than 15% (v), and the content of helium in the permeation gas of the secondary membrane separator is more than 90% (v).

6. A device for extracting helium from a poor-helium BOG gas is applied to the process for extracting helium from a rich-neon BOG gas, which is disclosed by any one of claims 1 to 5, and comprises a BOG raw gas compressor (1), wherein an input end of the BOG raw gas compressor (1) is connected with a gas inlet pipeline, a fuel gas pipe network is connected onto the gas inlet pipeline, a first hand valve (V1) is arranged on the fuel gas pipe network, a second hand valve (V2) is arranged at one side of the gas inlet pipeline and positioned on one side of the fuel gas pipe network, an output end of the BOG raw gas compressor (1) is connected with a front heat exchanger (2) of a primary membrane separator through a pipeline, an outlet of the front heat exchanger (2) of the primary membrane separator is connected with a primary membrane separator (3), a non-permeation gas outlet of the primary membrane separator (3) is communicated with the fuel gas pipe network through a connecting pipeline, and a third hand valve (V3) is arranged on the connecting pipeline, the device is characterized in that a permeating gas outlet of the primary membrane separator (3) is connected with a primary membrane permeating gas compressor (4) through a pipeline, an outlet of the primary membrane permeating gas compressor (4) is connected with a catalytic dehydrogenation reactor (5), the catalytic dehydrogenation reactor (5) is connected with an oxygen inlet pipe, an outlet of the catalytic dehydrogenation reactor (5) is connected with a molecular sieve dehydrator (6) through a pipeline, an outlet of the molecular sieve dehydrator (6) is connected with a front heat exchanger (7) of a secondary membrane separator through a pipeline, an outlet of the front heat exchanger (7) of the secondary membrane separator is connected with a secondary membrane separator (8) through a pipeline, a non-permeating gas outlet of the secondary membrane separator (8) is communicated with an inlet end pipeline of the front heat exchanger (2) of the primary membrane separator, a permeating gas outlet of the secondary membrane separator (8) is connected with a crude helium compressor (9) through a pipeline, and an outlet of the crude helium compressor (9) is connected with a helium purifier (10) through a pipeline, the helium purifier (10) export is through pipe connection helium booster compressor (11), helium booster compressor (11) exit linkage digital display formula gas supply busbar system (12), digital display formula gas supply busbar system (12) exit linkage helium bottle (13).

7. The helium extraction equipment of helium poor BOG gas as claimed in claim 6, wherein the molecular sieve dehydrator (6) adopts porous aluminosilicate crystals.

8. The helium extraction equipment of the helium poor BOG gas is characterized in that the primary membrane separator (3) and the secondary membrane separator (8) adopt any one of a single-stage membrane separation device and a multi-stage membrane separation device.

9. The apparatus for stripping helium from a helium-depleted BOG gas of claim 6, wherein the helium purifier (10) comprises a pressure swing adsorption purifier and a cryocondensation purifier.

10. The helium stripping plant for a helium depleted BOG gas as claimed in claim 6, characterized in that the helium tank (13) is a 40L or 50L standard tank.