阅读说明：本技术 一种膜分离浓缩回收氢气的方法及系统装置 (Method and system device for recovering hydrogen through membrane separation and concentration ) 是由 张剑锋 管英富 陶宇鹏 张汇霞 陈健 李守荣 王键 于 2019-10-25 设计创作，主要内容包括：本发明属于化工领域,涉及一种采用膜从含氢尾气中浓缩回收氢气的方法,包括含氢气体,进入冷干机脱除烃类组分、水等液态物质,再经过滤器脱除气体中的微量固体颗粒杂质,最后进入真空膜分离装置提纯氢气,膜的渗透侧连接的真空泵、回流管线和压力调节阀将渗透侧压力降低并稳定至较低压力；渗透侧的氢气经抽空系统获得,作为氢气产品输出；渗余侧的气体进入工厂燃料气管网作为燃料使用。从抽空系统的出口获得氢气,分离氢后的渗余气作为燃料气体排出膜分离装置。本发明与现有不对膜分离单元氢气渗透侧进行抽空降压的膜分离装置比较,氢气在膜表面的渗透效率可以提高15％～40％,可以明显降低膜分离装置的能耗和运行成本。(The invention belongs to the field of chemical industry, and relates to a method for concentrating and recovering hydrogen from hydrogen-containing tail gas by adopting a membrane, which comprises the steps of feeding hydrogen-containing gas into a cold dryer to remove liquid substances such as hydrocarbon components and water, removing trace solid particle impurities in the gas by a filter, and finally feeding the gas into a vacuum membrane separation device to purify the hydrogen, wherein a vacuum pump, a return pipeline and a pressure regulating valve which are connected with the permeation side of the membrane reduce and stabilize the permeation side pressure to a lower pressure; hydrogen on the permeation side is obtained through a pumping system and is output as a hydrogen product; the gas on the residual side enters a factory fuel gas pipe network to be used as fuel. Hydrogen is obtained from the outlet of the evacuation system, and the residual gas after hydrogen separation is discharged from the membrane separation device as fuel gas. Compared with the existing membrane separation device which does not perform evacuation depressurization on the hydrogen permeation side of the membrane separation unit, the permeation efficiency of hydrogen on the membrane surface can be improved by 15-40%, and the energy consumption and the operation cost of the membrane separation device can be obviously reduced.)

1. A method for recovering hydrogen by membrane separation and concentration is characterized in that: the method comprises the following steps:

(1) hydrogen-containing gas enters a cold dryer to remove liquid hydrocarbon components and liquid water;

(2) removing trace solid particle impurities in the gas through a filter;

(3) hydrogen is purified in a membrane separator, and the pressure of the permeation side is reduced and stably maintained by a vacuum pump, a backflow pipeline and a pressure regulating valve which are connected with the permeation side of the membrane separator;

(4) hydrogen on the membrane permeation side is obtained after evacuation and is output as a hydrogen product;

(5) the gas on the membrane retentate side is discharged from the membrane separator and enters a factory fuel gas pipe network to be used as fuel.

2. The method for concentrating and recovering hydrogen by membrane separation according to claim 1, characterized in that: and (4) after the hydrogen product is pressurized, further purifying by a pressure swing adsorption device to obtain pure hydrogen or a high-purity hydrogen product.

3. The method for concentrating and recovering hydrogen by membrane separation according to claim 1, characterized in that: the hydrogen-containing gas is refinery hydrogen-containing fuel gas with 20-60% of hydrogen content, wherein the pressure value is 0.2-1.0 Mpa.

4. The method for concentrating and recovering hydrogen gas by membrane separation according to claim 1, characterized in that: between the step (1) and the step (2), the hydrogen-containing gas is heated to 20-80 ℃ before entering the membrane separator.

5. The method for concentrating and recovering hydrogen by membrane separation according to claim 1, characterized in that: the pressure of the infiltration side in the step (3) is-0.04 to-0.09 Mpa.

6. The method for concentrating and recovering hydrogen gas by membrane separation according to claim 5, characterized in that: the pressure of the infiltration side is-0.081 to-0.085 Mpa.

7. The membrane separation and concentration hydrogen recovery device according to claim 1, wherein: the device comprises a freeze drying machine, a filter and a membrane separation mechanism, wherein the freeze drying machine is connected with the filter, the filter is connected with the membrane separation mechanism, the membrane separation mechanism is provided with a membrane separator, a vacuum pump, a backflow pipeline and a pressure regulating valve, the membrane separator is connected with the vacuum pump, one end of the pressure regulating valve is arranged on the connection between the membrane separator and the vacuum pump, one end of the pressure regulating valve is connected with the vacuum pump, a hydrogen product is output through the vacuum pump, and fuel gas is output through the membrane separator.

8. The apparatus for concentrating and recovering hydrogen by membrane separation according to claim 7, wherein: the membrane of the membrane separator is provided with a retentate side and a permeate side, the permeate side is connected with a vacuum pump, and the retentate side is connected with a filter and a fuel gas device; the raw material inlet and outlet are connected to form the retentate side, and the permeate side is the other side through which hydrogen gas permeates.

9. The apparatus for membrane separation and concentration hydrogen recovery according to claim 7 or 8, wherein: and a heater is arranged between the membrane separator and the cold dryer, one end of the heater is connected with the membrane separator, and the other end of the heater is connected with the cold dryer.

Technical Field

The invention belongs to the technical field of hydrogen extraction, and particularly relates to a method and a system device for recovering hydrogen through membrane separation and concentration.

Background

Hydrogen is an important resource in novel energy and petrochemical industry, and the prior technology for separating and recovering hydrogen from hydrogen-containing mixed gas mainly comprises a pressure swing adsorption method and a membrane separation method.

The pressure swing adsorption method is to utilize the characteristic that the adsorption capacity, adsorption force and adsorption speed of the adsorbent to different gases are different with the difference of pressure, to pressurize and adsorb easily-adsorbed components in the mixture under the condition of selective adsorption of the adsorbent, and to desorb the adsorbed components when the pressure of the adsorbent bed is reduced, thereby regenerating the adsorbent. The pressure swing adsorption method has the advantages of high regeneration speed, low energy consumption, simple operation and mature and stable process. The method has the greatest advantages that the hydrogen with high product purity (99.99%) can be obtained, and the hydrogen recovery rate is about 85-90%. But the number of the adsorption towers is large, and the occupied area is large.

The membrane separation method is realized by means of the difference of the permeability of each component of gas in the membrane, and the osmotic driving force is the partial pressure difference of two sides of the membrane. The membrane separation technology has the advantages of simple process, small occupied area, low cost and the like. However, the purity of hydrogen recovered by membrane separation is not high, and a relatively high pressure is required for the feed gas.

For the hydrogen-containing gas with the pressure of dry gas of an oil refinery being 0.2Mpa to 1.0Mpa and the hydrogen content being 20 percent to 60 percent, the technical problems of low membrane separation efficiency, large dosage of membrane material and high investment cost exist because the permeation driving force of the hydrogen on the membrane surface is small. Therefore, the low-content hydrogen recovery needs to be pressurized, the membrane separation needs to be carried out by adopting a mode of compressing and pressurizing the hydrogen-containing feed gas under 1.5-3.0 Mpa, the hydrogen with high recovery rate can be obtained, and the technical problems of high cost of a compressor and high pressurization energy consumption also exist.

Disclosure of Invention

In order to solve the technical problems, the invention provides a method for recovering hydrogen by membrane separation and concentration, which overcomes the limitation that the conventional membrane separation method needs compression and pressurization to operate under higher pressure under the condition of lower hydrogen content of raw materials aiming at the raw materials with lower concentration of hydrogen, and can evacuate the hydrogen permeation side of a membrane device without pressurizing the raw materials, thereby having low energy consumption, low investment and low cost.

The method for recovering hydrogen by membrane separation and concentration, which solves the technical problems, is characterized by comprising the following steps: the method comprises the following steps:

(1) hydrogen-containing gas enters a cold dryer to remove liquid hydrocarbon components and liquid water;

(2) removing trace solid particle impurities in the gas through a filter;

(3) hydrogen is purified in a membrane separator, and the pressure of the permeation side is reduced and stably maintained by a vacuum pump, a backflow pipeline and a pressure regulating valve which are connected with the permeation side of the membrane separator;

(4) hydrogen on the membrane permeation side is obtained after evacuation and is output as a hydrogen product;

(5) the gas on the membrane retentate side is discharged from the membrane separator and enters a factory fuel gas pipe network to be used as fuel.

Hydrogen is obtained from the outlet of the evacuation system, and the residual gas after hydrogen separation is discharged out of the membrane separator as fuel gas.

And (3) purifying the hydrogen by adopting a vacuum membrane separation device, wherein the vacuum membrane separation mechanism is provided with a membrane separator, a vacuum pump, a backflow pipeline and a pressure regulating valve, two ends of the pressure regulating valve are respectively connected with the membrane separator and the vacuum pump, the vacuum pump is connected with the membrane separator, and the membrane separator, the vacuum pump and the pressure regulating valve are mutually connected through the backflow pipeline. When the vacuum pump and the pressure regulating valve are adopted to pump the permeation side of the membrane separator, the hydrogen at the outlet of a part of vacuum pump flows back to the permeation side of the membrane separator to ensure the stability of the permeation side pressure.

The hydrogen-containing gas is refinery hydrogen-containing fuel gas with 20-60% of hydrogen content or other hydrogen-containing gas, wherein the pressure value is 0.2-1.0 MPa.

In the step (1) and the step (2), the hydrogen-containing gas is heated to 20-80 ℃ by a heater before entering the filter.

And (3) in the step (2), the cold drying temperature is 2-10 ℃, and the pressure value is 0.2-1.0 MPa.

And (3) keeping the pressure of the permeation side at negative pressure, specifically-0.04 to-0.09 Mpa. The energy consumption of the pressure low vacuum pump is increased, the hydrogen recovery rate is increased, and a proper pressure value is important.

The permeate side pressure is preferably between-0.081 and-0.085 Mpa.

And (4) pressurizing the hydrogen product obtained after evacuation in the step (4), and further purifying by using a pressure swing adsorption device to obtain pure hydrogen or a high-purity hydrogen product.

The invention relates to a system device for recovering hydrogen by membrane separation and concentration, which comprises a freeze-drying machine, a filter and a vacuum membrane separation mechanism, wherein the freeze-drying machine is connected with the filter, the filter is connected with the vacuum membrane separation mechanism, the vacuum membrane separation mechanism is provided with a membrane separator, a vacuum pump, a backflow pipeline and a pressure regulating valve, the membrane separator is connected with the vacuum pump, one end of the pressure regulating valve is arranged on the connection between the membrane separator and the vacuum pump, the other end of the pressure regulating valve is connected with the vacuum pump, a hydrogen product is output by the vacuum pump, and fuel gas is output.

The membrane separator membrane is provided with a retentate side and a permeate side, the permeate side is connected with the vacuum pump, and the retentate side is connected with the filter and the fuel gas device. The raw material inlet and outlet are connected to form the retentate side, and the permeate side is the other side through which hydrogen gas permeates. The attachment point for the vacuum pump in the present invention is on the permeate side of the hydrogen-rich gas.

The pressure of the surplus side of the membrane separation hydrogen recovery device is 0.2-1.0 Mpa.

The purpose of the pressure control valve backflow is to stabilize the pressure, the lower the backflow the better, the normally closed state.

The membrane assembly is cylindrical, and the separation membrane is a hollow fiber membrane.

And a heater is arranged between the membrane separator and the cold dryer, one end of the heater is connected with the membrane separator, and the other end of the heater is connected with the cold dryer.

The hollow fiber membrane is in a fibrous shape and has a self-supporting effect, and is a fiber filament processed into a hollow cavity by taking polysulfone and dimethylacetamide as raw materials, and then the fiber filament is divided by a high-permeability polymer, so that the hollow fiber membrane has a selective permeability characteristic. Since water vapor, hydrogen, ammonia, and carbon dioxide permeate faster, and methane, nitrogen, argon, oxygen, and carbon monoxide permeate slower, this allows for a fast permeation to slow permeation separation. Is distinguished from the fact that polymeric membranes are more permeable to non-condensable gases of relatively small molecular mass, such as hydrogen.

The present invention utilizes the difference between the gas pressure at both sides and the difference between the permeation rates of the fuel gas and the hydrogen gas in the mixed gas to selectively permeate the hydrogen gas, thereby achieving the separation effect. Hydrogen was delivered by a vacuum pump. The hydrogen is selectively separated from the fuel gas, resulting in improved hydrogen recovery.

In the invention, the pressure is 0.2 Mpa-1.0 Mpa, other hydrogen-containing gases such as hydrogen-containing fuel gas of an oil refinery with the hydrogen content of 20-60 percent enter a cold dryer to remove liquid substances such as hydrocarbon components, water and the like, and after trace solid particle impurities in the gas are removed by a filter, purifying hydrogen in a vacuum membrane separation device consisting of a membrane separator, a vacuum pump, a backflow pipeline and a pressure regulating valve, reducing and stabilizing the pressure of the permeation side to a lower pressure by the vacuum pump, the backflow pipeline and the pressure regulating valve which are connected with the permeation side of the membrane, because the vacuum system reduces the pressure at the permeation side, the partial pressure difference at two sides of the membrane as the driving force of hydrogen permeation is obviously improved, the permeation efficiency of hydrogen in the membrane device is improved, compared with the prior membrane separation hydrogen recovery device which does not perform evacuation and depressurization on the permeation side, the membrane consumption can be reduced, the cost is reduced, the hydrogen yield is increased, and the economic benefit is improved.

The invention adopts the vacuum system to reduce the pressure of the hydrogen permeation side of the membrane separation device, can not pressurize the feed gas, improves the hydrogen partial pressure difference of the hydrogen at the two sides of the membrane, and improves the permeation driving force of the hydrogen on the surface of the membrane, and compared with the existing membrane separation device which does not evacuate and depressurize the hydrogen permeation side of the membrane separation unit, the permeation efficiency of the hydrogen on the surface of the membrane can be improved by 15-40%. Compared with the conventional method of pressurizing the raw material gas of the membrane separation device and increasing the partial pressure difference of hydrogen on two sides of the membrane, the method can obviously reduce the energy consumption and the operation cost of the membrane separation device.

The method of the invention is mainly suitable for the raw material gas with the hydrogen content of 20 to 60 percent under the pressure of 0.2 to 1.0Mpa, in particular to the raw material gas with the hydrogen content of 20 to 30 percent.

Drawings

FIG. 1 is a process flow diagram of the present invention

FIGS. 2 and 3 are schematic views of the structure of the apparatus of the present invention

Wherein, the marks in the figure are specifically: 1. cold drying machine, 2 filter, 3 membrane separator (3-1 permeation side, 3-2 permeation side), 4 vacuum pump, 5 pressure regulating valve, 6 heater, 7 fuel gas device and 8 pressure swing adsorption device

Detailed Description

The present invention will be described in further detail with reference to the following embodiments, wherein the apparatus is conventional apparatus and equipment, wherein the freeze-drying machine, the filter, the membrane separator, the vacuum pump and the pressure regulating valve are all conventional general-purpose equipment in the technical field, and are commercially available: