KR-102963604-B1 - Apparatus and process capturing carbon dioxide linked with production of high-quality biogas with heat exchange network

KR102963604B1KR 102963604 B1KR102963604 B1KR 102963604B1KR-102963604-B1

Abstract

The present invention relates to a carbon dioxide capture device and process linked to biogas upgrading equipped with a heat exchange network, and provides a carbon dioxide capture device linked to biogas upgrading that can simultaneously obtain high-purity methane and carbon dioxide, as well as utilize the gas flow after the liquefaction process and recover cold energy within the process to achieve excellent separation efficiency without additional processes.

Inventors

하성용
민광준
이충섭
임진혁
백은별
한상훈

Assignees

(주)에어레인

Dates

Publication Date: 20260513
Application Date: 20230621

Claims (20)

A first compressor that compresses a first compressor supply gas containing biogas; A first separation membrane that separates a first separation membrane supply gas, including gas compressed in the first compressor, into a first separation membrane permeate gas and a first separation membrane residual gas; A second separation membrane that receives the first separation membrane residual gas and separates it into a second separation membrane permeate gas and a second separation membrane residual gas; A third separation membrane that receives the first separation membrane permeate gas and separates it into a third separation membrane permeate gas and a third separation membrane residual gas; A second compressor that compresses a second compressor supply gas containing the third membrane permeate gas; A heat exchanger for cooling the gas compressed by the second compressor above; A carbon dioxide purification unit comprising a separation tower receiving gas cooled by the above heat exchanger, an upper section where carbon dioxide-containing gas is obtained, and a lower section where high-purity carbon dioxide liquid is obtained; A dry ice generating unit comprising a chamber that receives the above-mentioned high-purity carbon dioxide liquid and converts it into dry ice, and a discharge section for discharging residual carbon dioxide gas that is not converted into dry ice; A first recovery membrane that receives the above carbon dioxide-containing gas and separates it into a first recovery membrane permeate gas and a first recovery membrane residual gas; A first circulation unit for circulating the first recovered membrane permeate gas to the first membrane, the third membrane, or the second compressor; and A carbon dioxide capture device linked to biogas upgrading, comprising: a heat exchange network that cools the gas compressed in the first compressor by heat exchange with one or more of the second membrane permeate gas, the second membrane residual gas, the third membrane permeate gas, the third membrane residual gas, the carbon dioxide-containing gas, the first recovered membrane permeate gas, the first recovered membrane residual gas, and the residual carbon dioxide gas before supplying the gas to the first membrane; The above heat exchange network is, A first heat exchanger that heat exchanges the gas compressed in the first compressor with the gas permeated through the third membrane; A second heat exchanger that heat exchanges the gas compressed in the first compressor, cooled in the first heat exchanger, with a methane-dominant gas comprising one or more of the second membrane residual gas and the first recovered membrane residual gas; A third heat exchanger that heat exchanges the gas compressed in the first compressor, cooled in the second heat exchanger, with a second recovery gas comprising one or more of the second membrane permeate gas and the third membrane residual gas; and A carbon dioxide capture device linked to biogas upgrading, characterized by including a fourth heat exchanger that exchanges heat with the gas compressed in the first compressor, which is cooled in the third heat exchanger, with the residual carbon dioxide gas.
A carbon dioxide capture device linked to biogas upgrading according to claim 1, characterized in that the first compressor compresses the first compressor supply gas to a pressure of 2 to 15 bar.
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A carbon dioxide capture device linked to biogas upgrading according to claim 1, further comprising a second circulation unit that circulates at least one of the second membrane permeate gas and the third membrane residual gas to the first compressor.
A carbon dioxide capture device linked to biogas upgrading according to claim 1, further comprising: a second recovery membrane that receives the first recovery membrane residual gas and separates it into a second recovery membrane permeate gas and a second recovery membrane residual gas.
A carbon dioxide capture device linked to biogas upgrading according to claim 1, characterized in that the temperature of the gas supplied to the first membrane is -40 to 10 ℃.
A carbon dioxide capture device linked to biogas upgrading according to claim 1, characterized in that the second compressor compresses the supplied gas to a pressure of 20 to 50 bar.
A carbon dioxide capture device linked to biogas upgrading according to claim 1, characterized in that the temperature of the gas supplied to the first recovery membrane is -40 to 0 ℃.
A carbon dioxide capture device linked to biogas upgrading according to claim 1, wherein the first membrane, the second membrane, the third membrane, and the first recovery membrane are identical or different from each other and are made of one or more materials selected from polysulfone (PSF) or polyimide (PI).
A carbon dioxide capture device linked to biogas upgrading according to claim 1, further comprising an additional heat exchanger that further heat exchanges the gas compressed in the second compressor with the residual carbon dioxide gas to cool the gas compressed in the second compressor.
A first compression step of compressing a first compressor supply gas containing biogas into a first compressor; A first separation step of supplying the gas compressed in the first compressor to a first membrane to separate it into a first membrane permeate gas and a first membrane residual gas; A second separation step of supplying the first membrane residual gas to a second membrane to separate it into a second membrane permeate gas and a second membrane residual gas; A third separation step of supplying the first membrane permeate gas to a third membrane to separate it into a third membrane permeate gas and a third membrane residual gas; A second compression step of compressing a second compressor supply gas containing the third membrane permeate gas into a second compressor; A liquefaction step of cooling the gas compressed by the second compressor using a heat exchanger; A separation and purification step in which the gas cooled by the above heat exchanger is supplied to a separation tower to obtain a carbon dioxide-containing gas at the top of the separation tower and recover high-purity carbon dioxide liquid at the bottom through a separation and purification process; A dry ice manufacturing step of converting the above high-purity liquid carbon dioxide into dry ice and obtaining residual carbon dioxide gas that is not converted into dry ice; A first recovery step of supplying the carbon dioxide-containing gas to a first recovery membrane to separate it into a first recovery membrane permeate gas and a first recovery membrane residual gas, and circulating the first recovery membrane permeate gas to the first membrane, the third membrane, or the second compressor; and A carbon dioxide capture process linked to biogas upgrading, comprising: a heat exchange step of cooling the gas compressed in the first compressor by heat exchange with one or more of the second membrane permeate gas, the second membrane residual gas, the third membrane permeate gas, the third membrane residual gas, the carbon dioxide-containing gas, the first recovered membrane permeate gas, the first recovered membrane residual gas, and the residual carbon dioxide gas before supplying the gas to the first membrane; The above heat exchange step is, A step of heat-exchanging the gas compressed in the first compressor with the gas permeated through the third membrane using a first heat exchanger; A step of heat-exchanging the gas compressed in the first compressor, cooled in the first heat exchanger, with a methane-dominant gas comprising one or more of the second membrane residual gas and the first recovered membrane residual gas using a second heat exchanger; A step of heat-exchanging the gas compressed in the first compressor, cooled in the second heat exchanger, with the second recovery gas comprising one or more of the second membrane permeate gas and the third membrane residual gas in the third heat exchanger; and A carbon dioxide capture process linked to biogas upgrading, characterized by including the step of heat-exchanging the gas compressed in the first compressor, which is cooled in the third heat exchanger, with the residual carbon dioxide gas in the fourth heat exchanger.
A carbon dioxide capture process linked to biogas upgrading according to claim 11, wherein the first compression step is characterized by compressing a first compressor supply gas containing biogas to a pressure of 2 to 15 bar.
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A carbon dioxide capture process linked to biogas upgrading according to claim 11, characterized in that at least one of the second membrane permeate gas and the third membrane residual gas is circulated to the first compressor.
A carbon dioxide capture process linked to biogas upgrading according to claim 11, characterized in that the temperature of the gas supplied to the first membrane is -40 to 10 ℃.
A carbon dioxide capture process linked to biogas upgrading according to claim 11, further comprising the step of supplying the residual gas from the first recovery membrane to the second recovery membrane to separate it into a gas permeated by the second recovery membrane and a residual gas from the second recovery membrane.
A carbon dioxide capture process linked to biogas upgrading according to claim 11, characterized in that the second compressor compresses the supplied gas to a pressure of 20 to 50 bar.
A carbon dioxide capture process linked to biogas upgrading according to claim 11, characterized in that the temperature of the gas supplied to the first recovery membrane is -40 to 0 ℃.
A carbon dioxide capture process linked to biogas upgrading according to claim 11, wherein the first membrane, the second membrane, the third membrane, and the first recovery membrane are identical or different from each other and are made of one or more materials selected from polysulfone (PSF) or polyimide (PI).
In Paragraph 11, A carbon dioxide capture process linked to biogas upgrading, further comprising the step of additionally heat-exchanging the gas compressed in the second compressor and the residual carbon dioxide gas with an additional heat exchanger.

Description

Apparatus and process capturing carbon dioxide linked with production of high-quality biogas with heat exchange network The present invention relates to a carbon dioxide capture device and process linked to biogas upgrading equipped with a heat exchange network. Biogas refers to a gaseous fuel containing methane and carbon dioxide produced when organic waste resources such as sludge, food waste, and livestock manure are decomposed by microorganisms. Among these biogases, methane gas from which carbon dioxide and some other gases have been removed is called biomethane, and recently, it is gaining attention as an energy source because it can be used as a clean fuel like natural gas. However, the methane content in biogas is approximately 50–70%, and the calorific value (less than 5,000 kcal/ m³ ) is low, making it difficult to use as a transportation fuel or city gas. To match the calorific value of natural gas, there is a challenge to increase the methane content in biogas to over 95%. Therefore, a process to separate the carbon dioxide/methane mixture, which makes up the majority of biogas, must be applied to improve its quality so that it can be supplied over long distances, thereby enabling its use as fuel for power generation, boilers, factories, and automobiles, or as city gas. Membrane separation is a method of separating gases by using a separation membrane to selectively permeate specific components. Gas separation using membranes separates gases through dissolution and diffusion processes and does not involve phase changes, resulting in low energy consumption. Furthermore, it has the advantages of a small installation area and easy maintenance, which is why it has recently been attracting attention as a gas separation and purification technology. Meanwhile, in the past, carbon dioxide generated as a byproduct of biogas was released into the atmosphere; however, as carbon dioxide is a well-known cause of global warming, it can lead to other environmental problems. Therefore, there is a need to develop devices and processes capable of separating and recovering high-purity methane and carbon dioxide. Figure 1 shows a process diagram for carbon dioxide capture linked to biogas upgrading equipped with a heat exchange network according to the present invention. The present invention will be described in more detail below with reference to the attached drawings and embodiments. Figure 1 shows a process diagram for carbon dioxide capture linked to biogas upgrading according to the present invention. Hereinafter, a carbon dioxide capture device and process linked to biogas upgrading equipped with a heat exchange network according to the present invention will be described with reference to FIG. 1 above. One aspect of the present invention comprises: a first compressor for compressing a first compressor supply gas containing biogas; a first membrane for separating a first membrane supply gas containing gas compressed by the first compressor into a first membrane permeate gas and a first membrane residual gas; a second membrane for receiving the first membrane residual gas and separating it into a second membrane permeate gas and a second membrane residual gas; a third membrane for receiving the first membrane permeate gas and separating it into a third membrane permeate gas and a third membrane residual gas; a second compressor for compressing a second compressor supply gas containing the third membrane permeate gas; a heat exchanger for cooling the gas compressed by the second compressor; a carbon dioxide purification unit comprising a separation tower receiving the gas cooled by the heat exchanger, an upper portion for obtaining a carbon dioxide-containing gas, and a lower portion for obtaining a high-purity carbon dioxide liquid; and a dry ice generation unit comprising a chamber for receiving the high-purity carbon dioxide liquid and converting it into dry ice, and a discharge portion for discharging residual carbon dioxide gas that is not converted into dry ice. A carbon dioxide capture device linked to biogas upgrading is provided, comprising: a first recovery membrane that receives the carbon dioxide-containing gas and separates it into a first recovery membrane permeate gas and a first recovery membrane residual gas; a first circulation unit that circulates the first recovery membrane permeate gas to the first membrane, the third membrane, or the second compressor; and a heat exchange network that cools the gas compressed in the first compressor by exchanging heat with one or more of the second membrane permeate gas, the second membrane residual gas, the third membrane permeate gas, the third membrane residual gas, the carbon dioxide-containing gas, the first recovery membrane permeate gas, the first recovery membrane residual gas, and the residual carbon dioxide gas before supplying the gas to the first membrane. In the present invention, biogas refers to a gas produced by the anaerobic digestion of