RU2548526C2 - Self-adapting method of low temperature separation of gas mix - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method of gas mix separation is implemented in gas mix flow. Components are separated from gas mix flow by direct injection of low-temperature coolant into the gas flow mix. Coolant is formed of gas mix separation product obtained at each stage of mix cooling and component separation. A part of each separation product obtained is aftercooled using external cooling source and then returned directly to all stages of gas mix cooling and gas component separation. After all stages of cooling and gas component separation, the gas mix flow is aftercooled using external cooling source and then returned directly to previous stages of mix cooling and component separation, forming repeated gas mix flow transfer and cooling cycles.

EFFECT: reduced capital, operation and power costs, along with high separation degree of mixes of any composition.

3 cl, 1 dwg

Description

The invention relates to methods for low-temperature separation of gas mixtures, which can be used both for the separation of natural petroleum gases, and gas mixtures of any composition.

The present invention is the development of a new method for low-temperature separation of the flow of gas mixtures with minimal operating costs while maintaining a high degree of separation of the gas mixture of any composition.

Known methods for the separation of natural and petroleum gases, including compression of the source gas, stepwise cooling, separation, in which the return flows, that is, the cooled separated gas fractions, are used as refrigerants or one of the refrigerants (see ed. St. USSR for inventions No. 732637 798443).

These methods can relatively reduce energy costs through the use of cold return flows of the separated gas components in comparison with methods that use special refrigerants. However, the cooling process takes place in heat exchangers, which are used in large quantities to achieve the efficiency of separation of gas mixtures. This significantly increases operating, capital and energy costs, reducing the effectiveness of the methods.

A known method for the separation of hydrocarbon gases by low-temperature distillation, in which the condensation of gases from the mixture is carried out by contacting them in countercurrent with a low-temperature insoluble coolant in them (see ed. St. USSR No. 132246 for the invention "Method for the separation of hydrocarbon gases". Priority date from 1/16/1960).

This method proceeds under conditions of contacting the vapor and liquid phases with a low-temperature insoluble in the latter refrigerant under high pressure. The method allows to reduce the amount of heat exchange equipment due to the implementation of the heat exchange process by directly contacting the refrigerant and the mixture to be separated. However, the use of a specially prepared refrigerant, condensation columns does not significantly reduce capital and energy costs, significantly reducing the effectiveness of this method.

A known method of air separation by low-temperature distillation, including cooling the air stream during heat exchange with separation products, the selection of an unbalanced air stream, part of which is condensed during heat exchange with liquid oxygen and fed to the rectification (see ed. St. USSR No. 783539 for the invention, “Air separation method low-temperature distillation. ”Priority date from 1/30/1979).

This method is based on direct contact in countercurrent of the gas to be separated with a refrigerant, which is a cooled separation product. The method is carried out using heat exchangers and distillation columns, which does not significantly reduce capital and energy costs, significantly reducing the effectiveness of this method.

An analysis of the information selected during the search revealed the closest technical solution to the method of low-temperature separation of associated (natural) gas, in which the refrigerant containing the compounds that make up the source gas is mixed with the source gas before compression, the compressed mixture or part of it is multi-stage cooled, after of one of the cooling processes, a liquid phase is taken from the mixture, which, or part of it, is used as a refrigerant or as part of the refrigerant in one of the cooling processes, while the agent is throttled, heated, partially or completely evaporated and then mixed with the source gas (see RF patent No. 2272972 for the invention “Method for the low-temperature separation of associated (natural) gas”. Priority date from 01/28/2004. IPC F25J 1/02. Prototype) .

The known method proposes to use a refrigerant containing components of the source gas, as well as the condensation product after cooling. But the main low-temperature separation is carried out using a large number of heat exchange equipment. This complicates the separation process, and increases the capital and energy costs of gas separation, significantly reducing the effectiveness of this method.

Thus, the known methods of low-temperature separation of gas mixtures do not provide high efficiency of the methods due to the high capital and energy costs.

The inventive method allows to achieve a new technical result - increasing the economic efficiency of the method of low-temperature separation of gas mixtures by reducing capital, operating and energy costs while ensuring a high degree of separation of gas mixtures of any composition.

The following set of essential features characterizes the essence of the proposed technical solution as an invention and contributes to the achievement of a new technical result.

A method of low-temperature separation of a gas mixture into components, comprising supplying a refrigerant to the initial gas mixture, stepwise cooling the mixture and separating gas components, wherein the low-temperature refrigerant is part of the liquid phase of the gas component after one of the cooling stages, characterized in that the components are separated from the gas stream mixtures by direct introduction at each stage of cooling directly into the gas mixture stream of a low-temperature refrigerant, which is a product of dividing the gas mixture obtained at each stage of cooling the mixture and isolating the components, while part of each obtained separation product is re-cooled using external cold, after which it is returned directly to all stages of cooling the gas mixture and the evolution of gas components, the gas mixture flow passing through all stages cooling and isolating the components, re-cooled using external cold and returning directly to the previous stages of cooling the mixture and isolating the components, forming multiple cycles of movement and cooling of the gas mixture stream.

To achieve the result in the invention:

- the refrigerant may be a single component and / or lower boiling gas, which is a mixture of the separated liquid gas components.

- the liquid phase of the gas recovered at lower temperatures than its boiling point is returned to earlier stages of cooling as a refrigerant.

So, the analysis of the revealed information about the current level of technology in the field of low-temperature separation of gas mixtures and the essence of the proposed invention showed that the proposed technical solution of the method meets the patentability criterion of "novelty".

The salient features of the present invention: “the separation of components is carried out from the gas mixture stream by direct introduction at each stage of cooling directly into the gas mixture stream of low-temperature refrigerant, which is the product of separation of the gas mixture obtained at each stage of the mixture cooling and separation of components” allow direct use of cold obtained separation products, which makes it possible to exclude a large number of refrigeration equipment.

Essential distinguishing feature:

“A part of each obtained separation product is cooled down using an external cold, after which it is returned to all stages of cooling the gas mixture and gas components are separated” together with the aforementioned feature, the method provides the necessary condensation temperature by using the cold of the isolated components and increasing the concentration of each component on the corresponding stages of cooling and isolation. In this case, external cold (refrigeration equipment) is used only at the end of the technological process of cooling and separation into components, this is enough. Since it is the direct introduction of separation products (by atomization) into the gas mixture stream as a low-temperature refrigerant that provides not only the necessary condensation temperature of the components, but also an increase in their concentration (after-recovery).

An essential distinguishing feature: “moreover, the gas mixture stream that has gone through all the stages of cooling and separation of components is cooled down using external cold and returned to the previous stages of cooling the mixture and separation of components, forming multiple cycles of movement and cooling of the gas mixture flow,” provides multiple cooling of the stream gas mixture to the required condensation temperatures and concentration of gas components included in the mixture. This allows you to start the process (start of the method) of cooling, condensation and separation of components from the mixture with minimal use of external cold, only at the end of the process, which ensures the achievement of the technical result.

Salient features “the refrigerant may be a single component and / or lower boiling gas, which is a mixture of the separated liquid gas components” and “the liquid gas phase recovered at lower temperatures than its boiling point is returned to earlier stages of cooling as the refrigerant” contributes to obtaining a technical result.

This is because the components to be separated from the gas mixture are not immediately released when the gas mixture flows through the cooling and separation stages, but as the concentration of each component increases at its corresponding boiling point, which is achieved by repeatedly cooling the gas mixture and entering directly into the product stream refrigerant separation.

Therefore, at the beginning of the cooling and separation into components, mixtures of isolated gas components are obtained, respectively, with different boiling points (high and low boiling gas components) with the predominant predominance of the component corresponding to each cooling stage (boiling temperature). And as the cooling cycles of the gas mixture increase with the direct introduction of the separation products into the mixture, the concentration of components increases at the corresponding cooling and recovery stages, respectively, the component corresponding to each cooling stage begins to prevail, which can be practically without impurities of the other components.

Thus, the gas mixture separation method is based on direct introduction (injection) of refrigerant into the gas mixture, including single-component cooling with the final product and / or lower boiling gas, which is a mixture of the separated liquid gas components (substances). The method of separating the gas mixture is characterized in that the liquid phase of the gas, extracted at lower temperatures than its boiling point, returns to the earlier stages of the process and serves as a refrigerant.

Therefore, the use of the gas mixture separation products themselves as a low-temperature refrigerant and their direct contact with the gas mixture flow at all stages of cooling and separation of components can significantly minimize the operational and energy costs of cooling the mixture and separating it into components due to minimal use of external cold ( refrigeration equipment).

Therefore, the proposed combination of essential features provides a technical result in all cases to which the requested amount of legal protection applies.

During the search by the applicant for information in the field of low-temperature separation of gas mixtures, certain significant distinctive features of the claimed invention were discovered, namely the use of refrigerant, the liquid phase of the gas component obtained in the process of cooling the mixture. However, the totality of significant distinguishing features is unknown.

It is the combination of essential distinguishing features that allows to obtain a new technical result - increasing the economic efficiency of the low-temperature separation of gas mixtures by reducing capital, operating and energy costs while ensuring a high degree of separation of gas mixtures of any composition.

Therefore, the present invention has such a patentability criterion as "inventive step".

The essence of the technical solution proposed as an invention is explained using the following example and the following drawing, where the drawing schematically shows a method of separating a gas mixture in a stream motion.

The method of low-temperature separation of the gas mixture is carried out with the flow movement of the gas mixture 1 and can be explained on the following schematically depicted system 2.

The source gas mixture 1 can be either two-component or multi-component. Figure 1 shows the low-temperature separation of a gas mixture 1, consisting, for example, of three components A, B, C with different boiling points (conventional gas).

In the system 2, designed for cooling, condensation and separation of the gas mixture 1 into components at their boiling point, separation devices 3 are installed, for example, separators. Separators are common standard industrial equipment.

The required number of devices 3 for separation is determined by the number of allocated components. Devices 3 divide the space of system 2 into separate sections corresponding to stages 4, 5, 6 of cooling and condensation of gas components. The drawing shows three stages 4, 5, 6, corresponding to the three conditional components A, B, C of the initial mixture 1.

For the extraction of components from mixture 1, for example, through membranes (standard industrial equipment) are used.

At the end of the system 2, external refrigeration equipment 7 is installed, standard, industrially produced. The output 8 of system 2 serves to remove the spent mixture 1, that is, after the maximum extraction of components A, B, C. from it

To control the flow rate of the gas mixture 1 using industrially produced flowing engines (not shown). The principle of their action is based on an increase or decrease in the flow rate of mixture 1 with a change in the composition of mixture 1 (concentration of components).

The process of separation of the gas mixture 1 in the system 2 is automated and is carried out using an industrial computer (not shown). The data necessary for isolating each component are introduced into it, namely, the boiling points of the gas components A, B, C, which are part of the mixture 1, which are necessary at each stage of cooling and isolation of the corresponding component.

The method is as follows.

The source gas mixture 1 is supplied at a predetermined speed by a stream to the cooling system 2 and gas components A, B, C.

The flow of the gas mixture 1 passes through all stages 4, 5, 6 of cooling, including a device 3 for the separation of components. Then, stream 1 enters the external refrigeration equipment 7, where it is cooled and returned directly to mixture stream 1 to the previous stages 4, 5, 6 of cooling and isolating components A. B. C, forming multiple cycles of movement and cooling of gas mixture stream 1 (starting way). This is necessary to run system 2 in order to cool the mixture and release gas components by achieving their boiling points.

And so, mixture 1 moves cyclically until it is cooled to the required boiling points of each component A, B, C. As a result of repeated movement and cooling of the mixture flow 1 at the corresponding cooling stages 4, 5, 6, the corresponding components A, B, C. begin to condense. This allows you to collect the gradually released separation product, the gas component, at each stage.

So at stage 4, this is the maximum predominance of component C with the other components B and A dissolved in it, since at this stage of cooling the boiling point of the highest boiling component C is maintained.

At stage 5, this is the maximum predominance of component B with other components dissolved in it, residues C, and component A, since here the lower boiling point corresponds to the boiling point of component B.

Accordingly, at stage 6, this is the maximum predominance of component A with the residues of components B and C dissolved in it, since here the lowest boiling point corresponds to the boiling point of component A.

So, the gases extracted in this way will have the composition:

C is a pure component with gases A and B dissolved in it.

B - with impurities of component C and gas A. dissolved in it.

A - with impurities of components B and C.

Part of each separation product is selected as the finished product A1, B1, C1, and the other part of each product A2, B2, C2 is sent to external refrigeration equipment 7 for additional cooling. Then, each pre-cooled part of the separation product A2, B2, C2 is directed to all stages of cooling 4, 5, 6 and separation by directly introducing mixture 1 into the stream (spraying) to effect direct contact and accordingly cooling mixture 1. That is, it is used as a low-temperature refrigerant, as well as to increase the concentration of released components (additional extraction of components).

In this case, the mixture 1, from which the gas components A, B, C are maximally extracted, is removed from the system 2 at the outlet 8.

At each stage of cooling, only those droplets of the gas which has passed into the liquid are recoverable; the rest, which go further through system 2, are useful in the future, since they are returned to cool all stages of the process. In the intermediate stages, before the boiling points of components A and B, the previous component is recovered. Component C is retrieved before the boiling point of component B. Components C + B are retrieved before the boiling point of component A.

The gas mixture separation method is based on direct injection (injection) of low-temperature refrigerant into the gas mixture, including one-component cooling with the final product and / or lower boiling gas, which is a mixture of the separated liquid gas components (substances). The method of separating the gas mixture is characterized in that the liquid phase of the gas, extracted at lower temperatures than its boiling point, returns to the earlier stages of the process and serves as a refrigerant (in the example, components C and B extracted in the following stages).

As a result of observing the prescribed for each component of the regime components are obtained by extraction exclusively at their "boiling" temperatures.

The main principle of this separation method is adaptation to any "gas" regardless of its composition, which means the possibility of low-temperature separation of a gas mixture of any composition (natural, oil, industrial, air gases, etc.) exclusively at their boiling points ".

Thus, as a result of the application of the proposed method, a new technical result is achieved - increasing the economic efficiency of the method of low-temperature separation of gas mixtures by reducing capital, operational and energy costs with a high degree of separation of gas mixtures of any composition.

Therefore, the present invention meets the patentability criterion of "industrial applicability".

The present invention allows to significantly reduce operating, capital and energy costs while maintaining a high degree of separation of gas mixtures of any composition, respectively, will find application not only in the oil and gas industry, but also in chemical, environmental treatment of industrial gases.

Claims (3)

1. A method of low-temperature separation of a gas mixture into components, comprising supplying a refrigerant to the initial gas mixture, stepwise cooling the mixture and isolating gas components, wherein the low-temperature refrigerant is part of the liquid phase of the gas component after one of the cooling stages, characterized in that the components are separated from the gas mixture stream by direct introduction at each stage of cooling directly into the gas mixture stream of a low-temperature refrigerant, which is the product of separating the gas mixture obtained at each stage of cooling the mixture and isolating the components, while a portion of each obtained separation product is further cooled using external cold, after which it is returned directly to all stages of cooling the gas mixture and isolating the gas components, the gas mixture flow passing through all stages cooling and isolating the components, docooling using external cold and returning directly to the previous stages of cooling the mixture and isolating the components, forming multiple e cycles of movement and cooling of the gas mixture flow. 2. The method according to claim 1, characterized in that the refrigerant may be a single component and / or lower boiling gas, which is a mixture of the separated liquid gas components. 3. The method according to claim 1 or 2, characterized in that the liquid phase of the gas recovered at lower temperatures than its boiling point is returned to earlier stages of cooling as a refrigerant.