RU2618818C1 - Method for producing helium based on burning natural gas with useful thermal energy use - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method comprises obtaining enriched to about 90-95% helium gas by the combustion of natural gas, followed by passing the resulting flue gas through a heat exchanger, reducing the temperature of the flue gas to 40-50°C, and further the fuel gas membrane separation in the membrane separator of the hollow fiber membranes, where the differential pressure is 0.03-0.1 MPa. Combustion of natural gas is carried out in gas turbine or steam generator that produces electricity and heat simultaneously.

EFFECT: provision of a simple method with low energy consumption, reduction of harmful emissions.

3 cl, 2 dwg

Description

The invention relates to the field of production of helium from natural gas and can be used in gas, oil, chemical and other industries and science.

Helium is among the noble gases, the need for which is constantly growing. Due to its properties, it is widely used in various fields of industry: in the aviation, rocket and space, electronic, nuclear industry, medicine. Helium is used for the preparation of breathing mixtures, including for the atmosphere of inhabited spacecraft, for deep-sea diving, as well as for the treatment of asthma, for filling airships and balloons. It is non-toxic, so inhaling helium in small quantities together with air is completely harmless.

The unique properties of this substance are also used in metallurgy - to create a protective environment for welding metals, in nuclear energy - as a coolant in some types of nuclear reactors.

Helium is mainly extracted from natural gas. In Russia, helium is produced at only one plant - the Orenburg Gas Processing Plant, which is part of Gazprom Dobycha Orenburg. The Orenburgskoye oil and gas condensate field is considered to be “poor” in terms of helium content - the volume fraction of this substance in the gas is up to 0.055%. In "rich" deposits contain more than 0.5% helium, in ordinary ones - 0.1-0.5%. All deposits with a helium content of less than 0.1% are classified as “poor”.

The extraction of helium from natural gas containing it is a strategic task in the operation of a field with any significant helium content. For Russia, this task is especially relevant, since in such rich oil and gas fields as the Chayandinskoye and Kovyktinskoye, the volume content of helium varies from 0.25% to 0.5%.

Traditionally, low-temperature (cryogenic) methods are used in the separation of helium: condensation, rectification, and adsorption. In modern in-line production schemes for helium production, blocks of selective diffusion through membranes are often included. Cryogenic methods are based on the ability of natural gas components to condense readily at low temperatures. They have found industrial application because they easily fit into a complex gas processing system.

Typically, pure helium is obtained from purified natural gas in three stages: helium concentrate containing up to 80 - 90% helium is isolated in cryogenic plants, concentrated to 99.98% and liquefied for convenient transportation and storage. To obtain pure helium from raw materials, chemical, adsorption and catalytic methods are used.

A known method of producing helium from a multicomponent gas stream [US 4717407, 01/05/1988, B01D 53/22; СВВ 23/00; F25J 3/02]. The invention is aimed at increasing the utilization of the source of helium-containing gas, including natural gas can be used. The method is an alternation of low temperature and membrane separation to obtain pure helium.

The disadvantage of this method is the complexity of the technological chain, which requires large energy and capital costs.

As a prototype, a method for extracting helium from natural gas was selected [RF patent No. 2478569, 11.16.2011, СВВ 23/00, С07С 1/04], including the production of helium concentrate with its subsequent low-temperature or membrane separation and adsorption purification from impurities. Before receiving a helium concentrate, the natural gas stream is subjected to conversion to produce synthesis gas, a catalytic synthesis of products is carried out, which are then condensed to give a helium concentrate. The technical result is an increase in the utilization rate of natural gas and a reduction in energy costs in the production of helium.

The implementation of this method requires large energy and capital costs.

The objective of the invention is to develop a cost-effective method for producing helium, characterized by simplicity and low energy and economic costs for the production of helium.

Simplicity in comparison with analogues is achieved by reducing the process chain of the process, which leads to the exclusion of complex equipment. The use of flue gas allows the use of membrane separators containing a smaller number of membranes with a comparable performance for helium-containing gas. The elimination of complex equipment from the technological chain allows reducing the cost of servicing a helium plant. In addition, the method allows to solve environmental problems, including significantly reduce harmful emissions.

To solve this problem, a completely new method for producing helium by burning natural gas in a gas turbine or steam generator is proposed. Upon completion of the combustion process, a gaseous product (flue gas) is obtained, which contains nitrogen, carbon dioxide, water, helium, argon and other impurities. Incomplete combustion may contain a small amount of methane. When receiving helium, the main difficulty is getting rid of CO ₂ . Among a number of methods for liberation from CO _{2, the} most promising is the passage of the mixture through polymer membranes, which also allows you to get rid of N ₂ .

Thus, according to the invention, a method for producing helium based on the complete burning of natural gas with the beneficial use of thermal energy involves burning natural gas in a power plant to produce flue gas and subsequent membrane separation of the flue gas to produce helium-enriched gas. The flue gas will not contain methane, but will consist of carbon dioxide, nitrogen, argon, helium, water vapor and a small amount of other impurities. Further, the problem of removing carbon dioxide and nitrogen from the mixture is solved by passing flue gas through hollow fiber membranes. The flue gas passing through the economizer and air heater of the steam generator will have a temperature of about 100 ° C. Using an additional heat exchanger will reduce the temperature of the flue gas to 40-50 ° C, which is safe for passing it through the membrane. The pressure drop across the membrane is 0.03-0.1 MPa. Under such conditions, the flue gas passed through the membrane separator will have a helium concentration reaching 90-95 vol. % Additional cleaning should be provided by chemical methods, depending on the composition of the mixture.

The burning of natural gas is carried out in a gas turbine or steam generator, which allows you to get both electricity and heat. Membrane separation is carried out in a membrane separator of hollow fiber membranes.

In FIG. 1 shows a diagram of a process for producing helium in an industrial plant based on natural gas combustion. Here: 1 - gas turbine; 2 - current generator; 3 - fire chamber of a steam boiler; 4 - compressor; 5 - membrane separator.

Natural gas containing helium is burned in a gas turbine 1 or a steam generator. Through a current generator 2 generate electricity for their own needs or third-party consumers. Then the gas enters the furnace of the steam boiler 3. The resulting flue gas, consisting of CO ₂ , N ₂ , He and a small amount of other gases, pre-cooled and utilized heat in the heat exchangers, is compressed in the compressor 4 and passed through a membrane separator 5. The number of membranes in the membrane separator is selected depending on the performance requirements. To increase productivity, it is necessary to use a membrane separator from a larger number of membranes.

Further, helium can be pumped into cylinders or liquefied and transported for further sale.

After burning natural gas and subsequent membrane separation of the flue gas, the resulting gas contains about 95 vol. % helium. Further, after purification, 99.9 vol. % For comparison, condensation produces a gas containing up to 80 vol. % helium, which is then purified to 99.9 vol. %

The method is implemented in a system of interconnected apparatuses, including a device for burning gas, for example, a gas turbine or steam generator, heat exchangers, a compressor, a membrane separator. Depending on the needs, the system can be supplemented, for example, with filters, a separator, process control devices, gas tanks, etc.

Experiments were carried out confirming the possibility of obtaining enriched up to 95 vol. % helium gas, followed by purification up to 99 vol. % and higher.

A series of experiments was organized by burning methane with the supply of a certain amount of helium. Gas (methane) was burned in a burner, air was mixed with a gas stream and a flameless combustion process was implemented, followed by cooling of the combustion products in a heat exchanger. A quantity of helium was introduced into the air supplied to the flame. The installation diagram is shown in FIG. 2. Here: 4 - compressor, 5 - membrane separator (hollow fiber membrane); 6 - burner, 7 - heat exchanger, 8 - separator; 9 - filter; 10 - gas collector; 11 - receiver; 12 - gas meter; 13 is an Agilent gas chromatograph.

The experimental setup is designed for a capacity of up to 1 l / min for helium-containing gas (methane with helium).

Burner 6 burned methane with supplied air, to which a certain percentage of helium was added. The gas exited the burner into the heat exchanger 7, where it was cooled to a temperature safe for the membrane material. Then the gas was passed through the separator 8 and the filter 9 for the purpose of drying and pumped into the gas collector 10. After that, the gas was compressed by the compressor 4 to the pressure necessary to overcome the membrane resistance. To create a stock of compressed gas in the network, a receiver 11 was used. The compressed gas was supplied to the membrane separator 5, from which helium and other gases (CO ₂ , N ₂ ) were released.

In order to determine the amount of the obtained gas mixture, a gas meter 12 was used. Both helium-containing gas and a mixture of other gases can be supplied to the meter for research.

Helium flow rate and concentration were measured with high accuracy on a gas chromatograph 13 with subsequent data processing on a high-performance personal computer.

The effectiveness of the membrane was tested in a series of special experiments on the separation of the He-Xe gas mixture and experiments on the separation of helium from air.

At the output, a gas mixture with a helium concentration of at least 90 vol. %

Given the generation of electricity and heat, the process of obtaining He by burning natural gas in a power plant and subsequent membrane separation of the resulting flue gas becomes cost-effective. Cost-effectiveness was calculated based on the basic economic principles outlined in the book Accelerating Innovation: Improving the Product Development Process by Marvin L. Patterson, former vice president of Hewllet-Packard. The calculation of the dependence of the amount of future money on the introduction of the invention at current cost from time periods to receipt (payment) showed that the implementation of the claimed invention relates to a time interval corresponding to a decrease in the number of initial investments without reducing the expected return.

It should also be borne in mind that when receiving helium at the production site, the gas pressure at the exit from the well is so high that a sufficient level of pressure is provided to overcome the membrane filter without additional equipment, which also helps to increase efficiency.

The proposed method can be used on gas from the Kovykta field in the Power of Siberia project. Even if significant gas leaks are allowed along the route during transportation to the designed helium plant, which is planned to be located on the border with China, the proposed method may turn out to be more effective than any other method, for example, synthesis gas. As far as we know, complete liquefaction on the border with China is not provided.

Of course, burning all gas to produce electricity and heat is an excellent way out at the Chayandinskoye field. The power plant and boiler room can be located in Yakutsk, providing heat and electricity to the entire region and at the same time receive helium. The problem of storage of helium in Yakutia is solvable.

It is also possible to take gas throughout the Power of Siberia pipeline, provided that in the cities and places through which the pipeline will pass, for example, in Irkutsk, electricity, heat and helium production complexes are constructed.

Claims (3)

1. A method of producing helium based on the combustion of natural gas with the beneficial use of thermal energy, including the production of gas enriched with helium, cooling it with heat recovery in heat exchangers and subsequent membrane separation, characterized in that it is enriched up to 90-95 vol. % helium gas is obtained by burning natural gas, then passing the resulting flue gas through a heat exchanger, reducing the temperature of the flue gas to 40-50 ° C, and further membrane separation of the flue gas in a membrane separator, where the pressure drop is 0.03-0.1 MPa . 2. The method according to p. 1, characterized in that the natural gas is burned in a gas turbine, a steam generator. 3. The method according to p. 1, characterized in that the membrane separation is carried out in a membrane separator of hollow fiber membranes.

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