KR100985911B1

KR100985911B1 - System for preprocessing of bio-gas

Info

Publication number: KR100985911B1
Application number: KR1020100009579A
Authority: KR
Inventors: 김낙주; 박성범; 성현제; 심동민; 이영민; 조의종
Original assignee: 한솔이엠이(주)
Priority date: 2010-02-02
Filing date: 2010-02-02
Publication date: 2010-10-08

Abstract

PURPOSE: A bio gas preprocessing system is provided to solidify the bio gas with methane of 95% by removing impurities like hydrogen sulfide, moisture, carbon dioxide, volatile organic compound, and siloxane. CONSTITUTION: A desulfurizing unit(10) removes hydrogen sulfide. A compressing unit(20) compresses bio gas. A dehumidifying unit is comprised of a cooling dehumidifying unit(30) and an adsorption dehumidifying unit(40). An activated carbon absorbing unit(60) absorbs the remaining hydrogen sulfide, the volatile organic compound and siloxane.

Description

Biogas Pretreatment System {SYSTEM FOR PREPROCESSING OF BIO-GAS}

Exemplary embodiments of the present invention relates to a biogas pretreatment system, to remove the impurity substances, such as more particularly, to hydrogen sulfide, water and volatile organic compounds contained in the biogas (VOC _s), siloxanes, and separating carbon dioxide It relates to a biogas pretreatment system.

In general, anaerobic digesters and landfills that treat high concentrations of organic waste, such as livestock manure, food waste, sewage sludge, and biogas are generated as organic matter is decomposed in an anaerobic state.

The main components of such biogas are methane (50 to 70%) and carbon dioxide (30 to 50%), and trace amounts of impurities such as ammonia, hydrogen, nitrogen, volatile organic compounds, and siloxanes, including hydrogen sulfide, are contained.

Here, since the methane is the main component, the biogas can be used as an energy source as a combustible material. For this reason, biogas is used as a fuel for a process of producing electricity or heat such as a boiler and cogeneration as a renewable energy source.

In the prior art, most biogas treatment facilities have a pretreatment facility for removing impurity substances other than methane contained in the biogas. The pretreatment facilities have a large amount of biogas, low quality gas and medium. pretreatment as a quality gas and a high quality gas.

Conventionally, most biogas treatment facilities pre-treat biogas in the form of low quality gas or heavy gas, which is used as fuel such as a boiler with only water in biogas removed, and heavy gas is water in biogas. It is used as a fuel for cogeneration generators that produce electricity and heat without removing hydrogen sulfide and siloxane materials.

However, since the low quality gas and the heavy gas have low energy efficiency and limited energy use, the prior art removes impurity substances contained in the biogas and separates carbon dioxide to increase energy utilization and efficiency. There is an urgent need for development of a pretreatment facility to promote biogas nitrification, and to produce biogas nitrified as compressed biomethane (CBM) or liquefied biomethane (LBM).

The solidified biogas can be named biomethane as a gas containing a concentration of 95% or more of methane, and if the biomethane is compressed and used in demand, the compressed biomethane can be named and liquefied. Specify liquefied biomethane.

Accordingly, an exemplary embodiment of the present invention has been created to improve the above problems, and removes impurities in biogas to produce compressed biomethane or liquefied biomethane from the anaerobic digester and landfill. In addition, the present invention provides a biogas pretreatment system in which carbon dioxide is separated and nitrified to 95% or more of biogas.

To this end, the biogas pretreatment system according to an exemplary embodiment of the present invention is to remove and separate impurities and carbon dioxide contained in the biogas for high quality of the biogas, iii) hydrogen sulfide in the biogas. A desulfurization unit for removal, ii) a compression unit for compressing the biogas at a constant pressure, iii) a water removal device for removing water in the biogas, and iii) residual hydrogen sulfide and volatile organics in the biogas. Activated carbon adsorption unit for adsorbing the compound and siloxane through activated carbon, and iii) a carbon dioxide separation device for separating carbon dioxide in the biogas.

In the biogas pretreatment system, the water removal device may be configured of a cooling dehumidification unit for cooling the biogas to remove water, and an adsorption dehumidification unit for adsorbing moisture in the biogas through an adsorbent.

In the biogas pretreatment system, the adsorption dehumidification unit includes a pair of first adsorption towers filled with an adsorbent, and the adsorption of moisture in the biogas through the pair of first adsorption towers, and regeneration of the adsorbent, is performed. It can be done alternately.

The biogas pretreatment system may be configured such that the desulfurization unit, the compression unit, the cooling dehumidification unit, the activated carbon adsorption unit, the adsorption dehumidification unit, and the carbon dioxide separation unit are sequentially connected.

In the biogas pretreatment system, the carbon dioxide separation unit may separate carbon dioxide in the biogas through an adsorbent.

In the biogas pretreatment system, the carbon dioxide separation apparatus may include a first adsorption unit having a second adsorption tower filled with the adsorbent.

In the biogas pretreatment system, the second adsorption tower may be composed of at least two.

In the biogas pretreatment system, the carbon dioxide separation unit and the first carbon dioxide desorption unit is configured to be connected to the first adsorption unit, to desorb the carbon dioxide adsorbed on the adsorbent in the second adsorption tower to increase the methane recovery rate; A second adsorption unit configured to be connected to the first carbon dioxide desorption unit and provided with a third adsorption tower filled with the adsorbent and separating carbon dioxide in the desorption gas generated by the first carbon dioxide desorption unit through the adsorbent; A second carbon dioxide desorption unit configured to be connected to the second adsorption unit to desorb carbon dioxide adsorbed on the adsorbent in the third adsorption tower may be further included.

In the biogas pretreatment system, the first and second carbon dioxide desorption units may be configured as a pump.

In the biogas pretreatment system, a rear end of the carbon dioxide separation unit, a measurement unit for measuring the concentration of hydrogen sulfide, water, methane and carbon dioxide in the biogas, and the desulfurization unit according to the measured value of the measurement unit A recirculation line may be provided to recirculate to the front end of.

The biogas pretreatment system may be configured such that the desulfurization unit, the compression unit, the carbon dioxide separation unit, the cooling dehumidification unit, the activated carbon adsorption unit, and the adsorption dehumidification unit are sequentially connected.

In the biogas pretreatment system, the carbon dioxide separation unit may separate the carbon dioxide by contacting the high pressure biogas with an aqueous solution.

In the biogas pretreatment system, the carbon dioxide separator may be connected to a first regeneration stripper for separating carbon dioxide from the aqueous solution in which the carbon dioxide is dissolved.

The biogas pretreatment system may be configured such that the desulfurization unit, activated carbon adsorption unit, carbon dioxide separation unit, compression unit, cooling dehumidification unit, and adsorption dehumidification unit are sequentially connected.

In the biogas pretreatment system, the carbon dioxide separation apparatus may separate carbon dioxide in the biogas through a chemical reaction between carbon dioxide and an absorbent made of an amine compound.

In the biogas pretreatment system, the carbon dioxide separation device may be connected to a second regeneration stripper for regenerating the absorbent by removing carbon dioxide absorbed by the absorbent as heat.

In the biogas pretreatment system, a rear end of the adsorption dehumidification unit, a measurement unit for measuring the concentration of hydrogen sulfide, water, methane and carbon dioxide in the biogas, and the desulfurization unit according to the measured value of the measurement unit A recirculation line may be provided to recirculate to the front end of.

Removing impure substance, such as according to the bio-gas pre-treatment system according to an exemplary embodiment of the invention, hydrogen sulfide contained in the biogas, water, carbon dioxide, volatile organic compounds (VOC _s), siloxane as described above and the carbon dioxide As a result, the nitrification of biogas with a concentration of 95% or higher is possible.

Therefore, in this embodiment, high quality biogas can be used in the form of compressed biomethane or liquefied biomethane, resulting in improved energy utilization and efficiency of the biogas.

Since these drawings are for reference in describing exemplary embodiments of the present invention, the technical idea of the present invention should not be construed as being limited to the accompanying drawings.
1 is a block diagram schematically illustrating a biogas pretreatment system according to a first exemplary embodiment of the present invention.
FIG. 2 is a block diagram illustrating a biogas pretreatment process using a biogas pretreatment system according to a first exemplary embodiment of the present invention.
3 is a block diagram schematically illustrating a biogas pretreatment system according to a second exemplary embodiment of the present invention.
4 is a block diagram illustrating a biogas pretreatment process using a biogas pretreatment system according to a second exemplary embodiment of the present invention.
5 is a block diagram schematically illustrating a biogas pretreatment system according to a third exemplary embodiment of the present invention.
6 is a block diagram illustrating a biogas pretreatment process using a biogas pretreatment system according to a third exemplary embodiment of the present invention.
7 is a block diagram schematically illustrating a biogas pretreatment system according to a fourth exemplary embodiment of the present invention.
Fig. 8 is a block diagram showing a biogas pretreatment process using a biogas pretreatment system according to a fourth exemplary embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification.

In the following detailed description, the names of the components are divided into first, second, and the like in order to distinguish the names of the components in the same relationship, and the descriptions of the components are not necessarily limited to the order in the following description.

1 is a block diagram schematically illustrating a biogas pretreatment system according to a first exemplary embodiment of the present invention.

Referring to the drawings, the biogas pretreatment system 100 according to an exemplary embodiment of the present invention is applied to a process for pretreating biogas to produce compressed biomethane (CBM) or liquefied biomethane (LBM).

Here, the biogas is a digestive gas generated in an anaerobic digester treating high concentration organic waste in a sewage treatment plant, a food processing plant, a livestock wastewater treatment plant, a alcohol factory, and a landfill gas generated by decomposing organic matter in an anaerobic state at a landfill site. Means.

Such a bio-gas pre-treatment system 100 is the main component of the hydrogen sulphide contained in biogas, water, carbon dioxide, volatile organic compounds biogas by removing impurity substances such as (VOC _s), siloxanes, and separating carbon dioxide methane This is to pretreat the concentration of 95% or more.

That is, the biogas pretreatment system 100 according to the present embodiment removes impurities in the biogas to purify the methane concentration of the biogas to 95% or more, and compresses the purified biogas to compressed biomethane or liquefied biomethane. It consists of a configuration that can be supplied to the production process.

To this end, the biogas pretreatment system 100 according to an exemplary embodiment of the present invention basically includes a desulfurization unit 10, a compression unit 20, a cooling dehumidification unit 30, and an adsorption dehumidification unit 40. It comprises a water removing device 50, the activated carbon adsorption unit 60, and the carbon dioxide separation device 70, which will be described by the configuration as follows.

In this embodiment, the biogas pretreatment system 100 is desulfurization unit 10, compression unit 20, cooling dehumidification unit 30, activated carbon adsorption unit 60, adsorption dehumidification unit 40, and carbon dioxide separation The device 70 is configured to be sequentially connected, which will be described by configuration as follows.

In the above, the desulfurization unit 10 is for removing hydrogen sulfide contained in the biogas. In this case, when the hydrogen sulfide is not removed as a highly corrosive substance and is introduced into the compression unit 20 in a later process, the hydrogen sulfide acts as a factor causing corrosion of the pipe and damage to the equipment.

The desulfurization unit 10 has a structure capable of removing 95% or more of hydrogen sulfide contained in biogas through a process of caustic soda cleaning method, activated carbon removal method, iron hydroxide removal method, and liquid phase catalyst method, and lowering the concentration of hydrogen sulfide to 200 ppm or less. Is done.

The desulfurization unit 10 is made as a hydrogen sulfide removal device of a known technique well known in the art, and a detailed description thereof will be omitted.

In the above, the compression unit 20 is for compressing the biosulfide from which hydrogen sulfide is removed by the desulfurization unit 10 at a constant pressure (approximately 8.5 bar), and is configured to be connected to the desulfurization unit 10 and compresses the biogas. Compressor 21 is included.

In the present invention, the compression unit 20 is illustrated as compressing the biogas to 8.5 bar, but is not necessarily limited to this, through the compressor 21 according to the operating pressure required in the post-process of the compression unit 20 bio The pressure of the gas can be varied.

In this case, the compressor 21 is made of a conventional reciprocating type or screw type compressor, and is preferably an oilless type compressor.

In addition, the compressor 21 may stably maintain the pressure of the biogas by installing a bypass pipe on the discharge pipe in order to maintain a constant discharge pressure of the biogas.

In addition, since the temperature of the biogas is increased in the process of compressing the biogas, the compressor 21 may include a water-cooled or air-cooled cooling apparatus for lowering the temperature of the biogas.

In the above, the cooling dehumidification unit 30 is to remove moisture in the biogas compressed by the compression unit 20 primarily, and is configured to be interconnected with the compression unit 20.

The cooling dehumidification unit 30 is configured to include a heat exchanger and an absorption chiller (also referred to in the art as a "chiller") of a conventionally known technique for transferring a high temperature heat source to a low temperature.

Here, the cooling dehumidification unit 30 removes water in the biogas by cooling the temperature of the biogas through a heat exchanger and an absorption type refrigerator.

Impure substance, such as in the above, an activated carbon absorption unit 60 has accepted offer biogas moisture is removed by the cooling dehumidifying unit 30, the bio residual hydrogen sulfide, volatile organic compounds (VOC _s) contained in the gas, and siloxane To remove the, it is configured to be interconnected with the cooling dehumidification unit (30).

The activated carbon adsorption unit 60 is filled with activated carbon (not shown in the figure) inside the tank (not shown), and serves to adsorb the impurities in the biogas through the activated carbon. do.

In this embodiment, the adsorption dehumidification unit 40 is for secondary removal of moisture in the biogas from which impurities such as residual hydrogen sulfide, volatile organic compounds, and siloxane are removed.

The adsorption dehumidifying unit 40 is to adsorb moisture in the biogas through the adsorbent 41 and is configured to be connected to the activated carbon adsorption unit 60. In this case, the adsorbent 41 is preferably made of activated alumina, zeolite and silica gel.

The adsorption dehumidifying unit 40 includes a pair of first adsorption towers 43 in which the adsorbent 41 is filled, and a process of adsorbing moisture in biogas through the pair of first adsorption towers 43, and the adsorbents. The regeneration process of (41) takes place alternately.

The first adsorption tower 43 of any one of the pair of first adsorption towers 43 adsorbs moisture in the biogas provided from the activated carbon adsorption unit 60 through the adsorbent 41, and dewes the moisture in the biogas. (dew point) Remove below -40 ℃.

The other first adsorption tower 43 removes moisture adsorbed to the adsorbent 41 and regenerates the adsorbent 41.

Here, the regeneration of the adsorbent 41 is performed by removing moisture adsorbed to the adsorbent 41 using heat, and a part of the dry biogas discharged from any one of the first adsorption towers 43 is removed. It warms up through the heating part 45, and supplies the warmed biogas to another 1st adsorption tower 43, and removes the water adsorbed by the adsorbent 41.

The heating unit may be made of any one or two or more combinations selected from an electric heater, cogeneration, and a boiler.

That is, in this case, a portion of the dry biogas discharged in a state where water is removed through the adsorbent 41 from any one of the first adsorption towers 43 is heated to 150 to 350 ° C. through the heating unit 45, The warmed dry biogas is supplied to the other first adsorption tower 43 and the adsorption tower 43 is heated to 150 to 350 ° C. to remove moisture adsorbed to the adsorbent 41.

In addition, the biogas from which the moisture adsorbed to the adsorbent 41 is removed from the other first adsorption tower 43 is recycled to the rear end of the desulfurization unit 10 through a separate regeneration line 47.

In the present embodiment, the carbon dioxide separation device 70 is for separating methane and carbon dioxide in the biogas from which water is removed at a dew point of −40 ° C. or lower through the adsorption dehumidification unit 40.

That is, in this embodiment, in order to produce the biogas as compressed biomethane or liquefied biomethane, the concentration of methane in the biogas should be 95% or more, so that the methane contained in the biogas through the carbon dioxide separation device 70 and Carbon dioxide is separated.

The carbon dioxide separation unit 70 includes a first adsorption unit 75 configured to be connected to the adsorption dehumidification unit 40, and the first adsorption unit 75 adsorbs carbon dioxide in the biogas to the adsorbent 71. Function to separate.

The first adsorption unit 75 includes at least two or more second adsorption towers 73 filled with an adsorbent 71, and the second adsorption tower 73 includes a first carbon dioxide desorption unit 181 which will be described later. 3), the adsorption and desorption process of carbon dioxide is alternately performed.

The first adsorption unit 75 is made of an adsorption material in which the adsorbent 71 adsorbs only carbon dioxide in biogas and does not adsorb methane.

Therefore, the biogas discharged from the adsorption dehumidification unit 40 is supplied into the second adsorption tower 73, and carbon dioxide in the biogas is adsorbed by the adsorbent 71, and the remaining methane is adsorbed by the adsorbent 71. Instead, it is discharged through the discharge line 75 and is supplied to the compressed biomethane or liquefied biomethane production process.

Since the adsorption amount of carbon dioxide through the adsorbent 71 is determined in proportion to the pressure of the biogas, the biogas is supplied to the second adsorption tower 73 at a high pressure.

Thus, in the present embodiment, by separating the carbon dioxide in the biogas through the adsorbent 71 in the second adsorption tower 73, the biogas having a concentration of methane of 95% or more can be supplied to the compressed biomethane or liquefied biomethane production process. do.

Meanwhile, in the present embodiment, the concentration of hydrogen sulfide, water, methane, and carbon dioxide in the biogas is measured while the carbon dioxide in the biogas is finally separated through the carbon dioxide separator 70 and methane is purified to a concentration of 95% or more. It further comprises a measuring unit 80 for.

The measuring unit 80 is provided as a sensor for measuring the concentration of hydrogen sulfide, water, methane, and carbon dioxide in the biogas at the rear end of the carbon dioxide separation unit 70 and output the measured value to the controller 90. At this time, the sensor is installed in the discharge line 75 as mentioned.

In the present embodiment, when the controller 90 receives the measured value measured by the measuring unit 80 and does not satisfy the preset reference value, the biogas is desulfurized at the rear end of the carbon dioxide separation unit 70. Recycling line 91 for recycling to the front end of

Here, the recirculation line 91 is a pipe connecting the rear end of the carbon dioxide separation unit 70 and the front end of the desulfurization unit 10, the direction switching valve installed in the connection portion of the discharge line 75 (not shown in the figure) It is selectively opened and closed through). The operation of the diverter valve is controlled by the controller 90 according to the measured value of the measuring unit 80.

Hereinafter, a pretreatment process using the biogas pretreatment system 100 according to the first exemplary embodiment of the present invention configured as described above will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram illustrating a biogas pretreatment process using a biogas pretreatment system according to a first exemplary embodiment of the present invention.

Referring to the drawings, firstly, in the present embodiment, organic gases are desulfurized in an anaerobic digestion tank or landfill which treats high concentration organic waste discharged from a sewage treatment plant, a food treatment plant, a livestock wastewater treatment plant, a drinking plant, and the like. Supply to the unit (10).

Then, the desulfurization unit 10 removes 95% or more of hydrogen sulfide contained in the biogas through a caustic soda washing method, activated carbon removal method, iron hydroxide removal method, and liquid phase catalyst method, and lowers the concentration of hydrogen sulfide to 200 ppm or less.

Next, the biosulfide from which hydrogen sulfide is removed by the desulfurization unit 10 is supplied to the compression unit 20. Thus, the biogas is compressed to a pressure of approximately 8.5 bar through the compressor 21 of the compression unit 20.

Subsequently, the biogas compressed at a constant pressure by the compression unit 20 is supplied to the cooling dehumidification unit 30. Then, the cooling dehumidifying unit 30 primarily removes the moisture in the biogas by cooling the temperature of the biogas through a heat exchanger and an absorption chiller.

Next, the biogas from which moisture is first removed by the cooling dehumidification unit 30 is supplied to the activated carbon adsorption unit 60.

Therefore, the activated carbon absorption unit 60 removes adsorbed by the activated carbon to impure substances such as the residual hydrogen sulfide, volatile organic compounds (VOC _s), and siloxane contained in the biogas.

Subsequently, biogas from which impurities such as residual hydrogen sulfide, volatile organic compounds, and siloxanes are removed is supplied to the adsorption dehumidifying unit 40 as described above.

Then, in the adsorption dehumidification unit 40, the water adsorption process in the biogas and the regeneration process of the adsorbent 41 are alternately performed through a pair of first adsorption towers 43, which will be described in more detail. The biogas supplied from the activated carbon adsorption unit 60 is supplied to any one first adsorption tower 43 of the pair of first adsorption towers 43.

Thus, in any one of the first adsorption towers 43, water in the biogas is adsorbed through the adsorbent 41, and the water in the biogas is secondarily removed at a dew point of −40 ° C. or less.

In the present embodiment, a part of the dry biogas discharged from the first adsorption tower 43 is heated to 150 to 350 ° C. through the heating unit 45, and the heated dry biogas is heated to another one. Supply to the first adsorption tower (43).

As the dry biogas heated to 150 to 350 ° C. is supplied into the other first adsorption tower 43, the internal temperature of the adsorption tower 43 starts to gradually increase, and is heated to approximately 150 to 350 ° C. The moisture adsorbed on the adsorbent 41 is removed.

Therefore, in the present embodiment, the dry biogas heated by the heating unit 45 is regenerated from the adsorbent 41 to the first adsorption tower 43 while removing the moisture adsorbed on the adsorbent 41.

Here, the biogas from which the moisture adsorbed to the adsorbent 41 is removed from the other first adsorption tower 43 is discharged through the regeneration line 47 and recycled to the rear end of the desulfurization unit 10.

Next, in the present embodiment, the biogas from which water is removed at a dew point of −40 ° C. or lower is supplied to the second adsorption tower 73 of the carbon dioxide separation unit 70 through the adsorption dehumidification unit 40.

Therefore, the high pressure biogas is carbon dioxide adsorbed to the adsorbent 71 in the second adsorption tower 73, and methane gas is discharged through the discharge line 76.

Then, the biogas is supplied to the compressed biomethane or liquefied biomethane production process while carbon dioxide is adsorbed by the adsorbent 71 inside the second adsorption tower 73.

Thus, in the present embodiment, by separating the carbon dioxide in the biogas through the adsorbent 71 in the second adsorption tower 73, biogas having a concentration of methane of 95% or more can be supplied to the compressed biomethane or liquefied biomethane production process. Will be.

In the present embodiment, the measurement unit 80 measures the concentration of hydrogen sulfide, water, methane, and carbon dioxide in the biogas at the rear end of the carbon dioxide separation device 70, and outputs the measured value to the controller 90. .

Then, when the controller 90 is provided with the measured value measured by the measuring unit 80 and does not satisfy the preset reference value, the biogas is passed through the recycle line 91 at the rear end of the carbon dioxide separation device 70. Recycled to the front end of the desulfurization unit (10).

As it described so far, according to the bio-gas pre-treatment system 100 according to the first exemplary embodiment of the present invention, hydrogen sulfide contained in the biogas, water, carbon dioxide, volatile organic compounds (VOC _s), impurities such as siloxanes By removing the material and pretreating the concentration of methane to 95% or more, biogas nitriding is possible.

3 is a block diagram schematically illustrating a biogas pretreatment system according to a second exemplary embodiment of the present invention.

Referring to the drawings, the biogas pretreatment system 200 according to the second exemplary embodiment of the present invention is based on the configuration of the above embodiment, the methane recovery rate by separating the methane and carbon dioxide in the biogas through a multi-stage adsorption process It is possible to configure the carbon dioxide separation unit 170 to increase the.

In the biogas pretreatment system 200, the desulfurization unit 10, the compression unit 20, the cooling dehumidification unit 30, the activated carbon adsorption unit 60, the adsorption dehumidification unit 40, and the measurement unit 80. ) And the organic connection structure of these and the carbon dioxide separation unit 170 is the same as in the above embodiment, a more detailed description will be omitted below.

In the present embodiment, the carbon dioxide separation unit 170 is basically provided with the first adsorption unit 175 of the above embodiment, the first carbon dioxide desorption unit 181, the second adsorption unit 184, and the second carbon dioxide The desorption unit 187 is further included.

The first carbon dioxide desorption unit 181 is configured to be connected to the second adsorption tower 173 of the first adsorption unit 175 to desorb carbon dioxide adsorbed on the adsorbent 171 inside the second adsorption tower 173. As an adsorbent regeneration unit.

The first carbon dioxide desorption unit 181 includes a pump 182 capable of desorbing the carbon dioxide adsorbed on the adsorbent 171 by reducing the pressure inside the second adsorption tower 173.

Here, the first carbon dioxide desorption unit 181 depressurizes the pressure inside the second adsorption tower 173, thereby discharging carbon dioxide desorbed from the adsorbent 171 as desorption gas, and the desorption gas includes some methane. .

The second adsorption unit 184 separates the carbon dioxide in the desorption gas generated by the first carbon dioxide desorption unit 181 through the adsorbent 185 and compresses the biogas containing the high concentration of methane by carbon dioxide separation. It will serve to supply methane or liquefied biomethane production processes.

The second adsorption unit 184 is configured to be connected to the first carbon dioxide desorption unit 181, and includes a third adsorption tower 186 filled with the adsorbent 185. Here, the adsorbent 185 is made of an adsorbent material that adsorbs carbon dioxide in biogas and does not adsorb methane.

And, the second carbon dioxide desorption unit 187 is configured to be connected to the third adsorption tower 186 of the second adsorption unit 184, carbon dioxide adsorbed by the adsorbent 185 inside the third adsorption tower 186. It is provided as an adsorbent regeneration unit for desorbing.

The second carbon dioxide desorption unit 187 may include a pump 188 capable of desorbing carbon dioxide adsorbed on the adsorbent 185 by reducing the pressure inside the third adsorption tower 186.

Here, the second carbon dioxide desorption unit 187 reduces the pressure inside the third adsorption tower 186, thereby discharging the carbon dioxide desorbed from the adsorbent 185 as desorption gas.

Hereinafter, a biogas pretreatment process using the biogas pretreatment system 200 according to the second exemplary embodiment of the present invention configured as described above will be described in detail with reference to the accompanying drawings.

4 is a block diagram illustrating a biogas pretreatment process using a biogas pretreatment system according to a second exemplary embodiment of the present invention.

Referring to the drawings, firstly, the present embodiment uses the first adsorption unit 175 to remove biogas from which moisture is removed at a dew point of −40 ° C. or lower through the adsorption dehumidification unit 40 as in the above embodiment. 2 is supplied to the adsorption tower (173).

Then, the biogas is supplied to the compressed biomethane or liquefied biomethane production process while carbon dioxide is adsorbed to the adsorbent 171 inside the second adsorption tower 173.

Meanwhile, in the present embodiment, the carbon dioxide is separated while the adsorption and desorption processes of carbon dioxide are alternately operated through two or more second adsorption towers 173 and the first carbon dioxide desorption unit 181, and thus, inside the second adsorption tower 173. The adsorbent 171 may be regenerated by desorbing carbon dioxide adsorbed to the adsorbent 171 through the first carbon dioxide desorption unit 181.

In this case, the first carbon dioxide desorption unit 181 desorbs the carbon dioxide adsorbed to the adsorbent 171 by reducing the pressure inside the second adsorption tower 173 through the pump 182.

Here, the first carbon dioxide desorption unit 181 discharges carbon dioxide desorbed from the adsorbent 171 as desorption gas, and the desorption gas includes some methane.

In this embodiment, the desorption gas is supplied to the third adsorption tower 186 of the second adsorption unit 184. Then, in the third adsorption tower 186, carbon dioxide in the desorption gas is adsorbed to the adsorbent 185, and methane gas is separated while being discharged.

Thus, the biogas from which carbon dioxide is separated through the adsorbent 185 in the third adsorption tower 186 is supplied to a compressed biomethane or liquefied biomethane production process.

On the other hand, in the present embodiment, the adsorbent 185 may be regenerated by desorbing carbon dioxide adsorbed on the adsorbent 185 inside the third adsorption tower 186 through the second carbon dioxide desorption unit 187.

In this case, the second carbon dioxide desorption unit 187 depressurizes the pressure inside the third adsorption tower 186 through the pump 188 to desorb the carbon dioxide adsorbed on the adsorbent 185 and use the carbon dioxide as the desorption gas. Drain it.

Here, the desorption gas discharged from the second carbon dioxide desorption unit 187 is a high concentration of carbon dioxide, and is recovered to a tank (not shown) provided separately.

On the other hand, in the present embodiment, hydrogen sulfide, water, and methane in the biogas supplied to the compressed biomethane or liquefied biomethane production process at the rear end of the first and second adsorption units 175 and 184. , And the concentrations of carbon dioxide are respectively measured, and the measured values are output to the controller 90.

Then, when the controller 90 receives the measured value measured by the measuring unit 80 and does not satisfy the preset reference value, the controller 90 recycles the biogas at the rear end of the first and second adsorption units 175 and 184. The line 91 is recycled to the front end of the desulfurization unit 10.

Therefore, in this embodiment, through a series of pretreatment processes described above, purified biogas having a methane concentration of 95% or more and a methane recovery rate of 95% or more can be supplied to a compressed biomethane or liquefied biomethane production process. .

In this embodiment, since the desorption gas having a concentration of 95% or more of carbon dioxide can be recovered through the first and second carbon dioxide desorption units 181 and 187, the carbon dioxide can be reused.

5 is a block diagram schematically illustrating a biogas pretreatment system according to a third exemplary embodiment of the present invention.

Referring to the drawings, the biogas pretreatment system 300 according to the third exemplary embodiment of the present invention, unlike the previous embodiments, desulfurization unit 210, compression unit 220, carbon dioxide separation unit 270, The cooling dehumidification unit 230, the activated carbon adsorption unit 260, and the adsorption dehumidification unit 240 may be configured to be sequentially connected.

In the present embodiment, the carbon dioxide separation device 270 is configured as a structure capable of separating carbon dioxide in biogas through a water scrubbing process.

Here, the configuration of the desulfurization unit 210, the compression unit 220, the cooling dehumidification unit 230, the activated carbon adsorption unit 260, and the adsorption dehumidification unit 240 is the same as in the above embodiments, More detailed description will be omitted in the specification.

In this embodiment, the carbon dioxide separation device 270 is a carbon dioxide and methane from the biogas using the principle that the carbon dioxide in the biogas is dissolved in the aqueous solution by contacting the biogas compressed at high pressure through the compression unit 220 with an aqueous solution. It consists of a configuration that can be separated.

That is, the carbon dioxide separator 270 is separated by using the difference in solubility between methane and carbon dioxide. Since the amount of carbon dioxide is dissolved in an aqueous solution is much greater than that of methane, carbon dioxide is dissolved in the aqueous solution and the methane is discharged without being dissolved. The principle applies.

And since the solubility of carbon dioxide increases in proportion to the pressure, the higher the pressure of the biogas can dissolve a large amount of carbon dioxide in an aqueous solution to effectively separate the carbon dioxide and methane in the biogas.

The carbon dioxide separation device 270 is formed as a tank that can accommodate an aqueous solution, and forms an inlet (not shown) for introducing the biogas compressed at high pressure and introducing the aqueous solution.

In addition, the carbon dioxide separator 270 forms an outlet portion (not shown) for discharging the biogas from which carbon dioxide is removed and an aqueous solution in which carbon dioxide is dissolved.

Meanwhile, a first regeneration stripper 281 capable of separating carbon dioxide from an aqueous solution in which carbon dioxide is dissolved is connected to the carbon dioxide separator 270 according to the present embodiment.

In the present embodiment, the first regeneration stripper 281 is configured to be connected to an outlet portion (not shown) in which the aqueous solution is discharged in the carbon dioxide separator 270, and thus the carbon dioxide dissolved in the aqueous solution is It is made as a structure that can be removed by gasification.

That is, the first regeneration stripper 281 may receive an aqueous solution having a reduced pressure as it is discharged from the carbon dioxide separator 270, and may separate the aqueous solution and carbon dioxide by gasifying the carbon dioxide dissolved in the aqueous solution.

In addition, the first regeneration stripper 281 includes an outlet for discharging the aqueous solution from which carbon dioxide is separated, and has a structure capable of recycling the aqueous solution discharged through the outlet to the carbon dioxide separator 270.

Since the first regeneration stripper 281 is formed as a regeneration stripper for a cleaning process of a well-known technique widely used in the art, a detailed description thereof will be omitted herein.

On the other hand, the present embodiment further includes a measuring unit 280 for measuring the concentration of hydrogen sulfide, water, methane, and carbon dioxide in the biogas at the rear end of the adsorption dehumidifying unit 240.

The measurement unit 280 is provided as a sensor for measuring the concentration of hydrogen sulfide, water, methane, and carbon dioxide in the biogas at the rear end of the adsorption dehumidification unit 240, respectively, and outputs the measured value to the controller 290.

In the present embodiment, when the controller 290 is provided with the measured value measured by the measuring unit 280 and does not satisfy the preset reference value, the front end of the desulfurization unit 210 at the rear end of the adsorption dehumidifying unit 240. A recirculation line 291 for recirculation.

Hereinafter, a biogas pretreatment process using the biogas pretreatment system 300 according to the third exemplary embodiment of the present invention configured as described above will be described in detail with reference to the accompanying drawings.

6 is a block diagram illustrating a biogas pretreatment process using a biogas pretreatment system according to a third exemplary embodiment of the present invention.

Referring to the drawings, first, in the present embodiment, the biogas is supplied to the desulfurization unit 210 to remove hydrogen sulfide in the biogas through the desulfurization unit 210, and the biosulfide from which the hydrogen sulfide is removed is compressed into the compression unit 220. It supplies and compresses the biogas to a constant pressure through the compression unit 220.

Subsequently, the biogas compressed at a constant pressure is supplied to the carbon dioxide separator 270 through the compression unit 220 as described above.

Then, in the carbon dioxide separator 270, the high pressure biogas is in contact with the aqueous solution, and the carbon dioxide in the biogas is dissolved in the aqueous solution to separate the carbon dioxide in the biogas.

That is, the carbon dioxide separator 270 increases the amount of carbon dioxide dissolved in the aqueous solution as the pressure of carbon dioxide increases, so that the higher the pressure of the biogas, the larger amount of carbon dioxide is dissolved in the aqueous solution to separate carbon dioxide and methane from the biogas. You will be able to make it.

Here, as described above, the biogas separated from carbon dioxide is supplied to the cooling dehumidification unit 230, which is a post-process, and the aqueous solution is discharged through the carbon dioxide separation unit 270 and supplied to the first regeneration stripper 281 while the pressure is lowered. do.

Accordingly, in the first regeneration stripper 281, since the pressure of the aqueous solution is lowered, the carbon dioxide dissolved in the aqueous solution is removed while gasifying, and the aqueous solution in which the carbon dioxide is removed is discharged from the first regeneration stripper 281, and the carbon dioxide separator ( 270).

Meanwhile, the cooling dehumidification unit 230 cools the biogas supplied from the carbon dioxide separator 270 to remove moisture in the biogas primarily.

Next, when the biogas from which moisture is first removed by the cooling dehumidification unit 230 is supplied to the activated carbon adsorption unit 260, the activated carbon adsorption unit 260 includes residual hydrogen sulfide and volatile organic compounds contained in the biogas. Impurities such as (VOC _S ), and siloxanes are adsorbed and removed through activated carbon.

Subsequently, when biogas from which impurities such as residual hydrogen sulfide, volatile organic compounds, and siloxanes are removed is supplied to the adsorption dehumidification unit 240 as described above, the biogas is first supplied from the adsorption dehumidification unit 240. Through the same action as in the second step, water in the biogas is removed and fed to the compressed biomethane or liquefied biomethane production process.

On the other hand, in the present embodiment, at the rear end of the adsorption dehumidification unit 240, the measurement unit 280 measures the concentrations of hydrogen sulfide, water, methane, and carbon dioxide in the biogas, respectively, and the measured value is transferred to the controller 290. Output

Then, when the controller 290 is provided with the measured value measured by the measuring unit 280 and does not satisfy the preset reference value, the biogas is passed through the recycle line 291 at the rear end of the adsorption dehumidifying unit 240. It is recycled to the front end of the desulfurization unit 210.

As a result, in the present embodiment, through the series of pretreatment processes as described above, the biogas purified with methane concentration of 95% or more can be supplied to the compressed biomethane or liquefied biomethane production process.

7 is a block diagram schematically illustrating a biogas pretreatment system according to a fourth exemplary embodiment of the present invention.

Referring to the drawings, the biogas pretreatment system 400 according to the fourth exemplary embodiment of the present invention, unlike the previous embodiments, the desulfurization unit 310, activated carbon adsorption unit 360, carbon dioxide separation unit 370 The compression unit 320, the cooling dehumidification unit 330, and the adsorption dehumidification unit 340 may be configured to be sequentially connected.

In the present embodiment, the carbon dioxide separation device 370 is configured as a structure capable of separating carbon dioxide in biogas through a chemical absorption process.

Here, the configuration of the desulfurization unit 310, activated carbon adsorption unit 360, compression unit 320, cooling dehumidification unit 330, and adsorption dehumidification unit 340 is the same as in the above embodiments, the present specification A more detailed description will be omitted.

In this embodiment, an amine compound in the carbon dioxide separation unit 370 is the remaining hydrogen sulfide, volatile organic compounds through the activated carbon absorption unit (360) (VOC _s), and the normal pressure, such as the removal of biogas siloxane (常壓) By contacting with the absorbent 371 made of a chemical composition of the carbon dioxide and the amine compound is composed of a structure that can separate the carbon dioxide and methane from the biogas.

That is, the carbon dioxide separator 370 may separate carbon dioxide and methane in biogas by absorbing the carbon dioxide into the absorbent 371 through a chemical reaction between carbon dioxide and an amine compound.

Meanwhile, a second regeneration stripper 381 capable of separating carbon dioxide from an amine compound by heating an absorbent 371 absorbing carbon dioxide is connected to the carbon dioxide separator 370 according to the present embodiment.

The second regeneration stripper 381 uses heat, and has a structure for removing carbon dioxide from the amine compound of the absorbent 371 supplied from the carbon dioxide separator 370.

Since the second regeneration stripper 381 is made as a regeneration stripper for a chemical absorption process of a well-known technique widely used in the art, a detailed description thereof will be omitted herein.

On the other hand, the present embodiment further includes a measuring unit 380 for measuring the concentration of hydrogen sulfide, water, methane, and carbon dioxide in the biogas at the rear end of the adsorption dehumidifying unit 340.

The measurement unit 380 is provided as a sensor for measuring the concentration of hydrogen sulfide, water, methane, and carbon dioxide in the biogas at the rear end of the adsorption dehumidification unit 340, respectively, and outputs the measured value to the controller 390.

In the present embodiment, when the controller 390 receives the measured value measured by the measuring unit 380 and does not satisfy the preset reference value, the front end of the desulfurization unit 310 at the rear end of the adsorption dehumidifying unit 340. A recirculation line 391 for recirculation.

Hereinafter, a biogas pretreatment process using the biogas pretreatment system 400 according to the fourth exemplary embodiment of the present invention configured as described above will be described in detail with reference to the accompanying drawings.

Fig. 8 is a block diagram showing a biogas pretreatment process using a biogas pretreatment system according to a fourth exemplary embodiment of the present invention.

Referring to the drawings, first, in the present embodiment, the biogas is supplied to the desulfurization unit 310 to remove hydrogen sulfide in the biogas through the desulfurization unit 310, and the biogas from which the hydrogen sulfide is removed is activated carbon adsorption unit 360. the supply to the impurity substance such as a bio residual hydrogen sulfide, volatile organic compounds contained in the gas (VOC _s), and the siloxane is removed by adsorption with activated carbon.

Then, the supply to the residual hydrogen sulfide, volatile organic compounds (VOC _s), and the impure biogas material is removed, such as siloxane carbon dioxide separation device 370 as described above.

Then, the carbon dioxide separator 370 separates carbon dioxide and methane from the biogas using a chemical reaction of carbon dioxide and an amine compound by contacting the biogas with an absorbent 371 made of an amine compound at atmospheric pressure. do.

That is, the carbon dioxide separator 370 separates carbon dioxide in biogas by absorbing the carbon dioxide into the absorbent 371 through a chemical reaction between carbon dioxide and an amine compound, and compresses the biogas from which carbon dioxide is separated into compressed biomethane or liquefaction. Feed into the biomethane production process.

Here, the absorbent 371 absorbing carbon dioxide is supplied to the second regeneration stripper 381. In the second regeneration stripper 381, the absorbent 371 is heated to separate carbon dioxide from the amine compound. In addition, the absorbent 371 regenerated by the second regeneration stripper 381 is supplied to the carbon dioxide separator 370.

On the other hand, as described above, the biogas from which carbon dioxide is separated in the carbon dioxide separator 370 is supplied to the compression unit 310, and the compression unit 310 compresses the biogas to a constant pressure.

Next, when the biogas compressed at a predetermined pressure is supplied to the cooling dehumidification unit 330 through the compression unit 310, the cooling dehumidification unit 330 cools the biogas to remove moisture in the biogas primarily. do.

Subsequently, when the biogas from which moisture in the biogas is first removed through the cooling dehumidification unit 330 is supplied to the adsorption dehumidification unit 340, the adsorption dehumidification unit 340 may be the same as in the first embodiment. Through the action, the water in the biogas is secondarily removed, and the biogas is supplied to a compressed biomethane or liquefied biomethane production process.

On the other hand, in this embodiment, at the rear end of the adsorption dehumidification unit 340, the measurement unit 380 measures the concentrations of hydrogen sulfide, water, methane, and carbon dioxide in the biogas, respectively, and the measured value is transferred to the controller 390. Output

Then, when the controller 390 receives the measured value measured by the measuring unit 380 and does not satisfy the preset reference value, the controller 390 passes the biogas through the recycle line 391 at the rear end of the adsorption dehumidifying unit 340. Recycled to the front end of the desulfurization unit 310.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the scope of the invention.

10, 210, 310 ... Desulfurization unit 20, 220, 320 ... Compression unit
21 ... Compressors 30, 230, 330 ... Cooling dehumidification units
40, 240, 340 ... Adsorption Dehumidification Unit 41, 71, 171, 185 ... Adsorbent
43. First adsorption tower 45 ... heating section
47 ... Regeneration line 50 ... Moisture removal device
60, 260, 360 ... Activated carbon adsorption unit 70, 270, 370 ... Carbon dioxide separator
73, 173 second adsorption tower 75, 175 first adsorption unit
80, 280, 380 ... Measuring units 90, 290, 390 ... Controller
91, 291, 391 ... Recirculation line 181 ... First CO2 desorption unit
182, 188 pump 184 second adsorption unit
186 ... Third adsorption tower 187 ... Second carbon dioxide desorption unit
281 First Regeneration Stripper 371 Absorbent
381 ... Second Play Stripper

Claims

A biogas pretreatment system for removing and separating impurities and carbon dioxide contained in the biogas for high quality of biogas,
A desulfurization unit for removing hydrogen sulfide in the biogas, a compression unit for compressing the biogas at a constant pressure, a cooling dehumidifying unit for cooling the biogas to remove water, and water in the biogas through an adsorbent. A water removal device comprising an adsorption dehumidification unit for adsorbing, an activated carbon adsorption unit for adsorbing residual hydrogen sulfide, volatile organic compounds, and siloxane in the biogas through activated carbon, and a carbon dioxide separation device for separating carbon dioxide in the biogas Include,
The adsorption dehumidifying unit includes a pair of first adsorption towers filled with an adsorbent, and the adsorption of water in the biogas and regeneration of the adsorbent are alternately performed through the pair of first adsorption towers.
The desulfurization unit, the compression unit, the cooling dehumidification unit, the activated carbon adsorption unit, the adsorption dehumidification unit, and the carbon dioxide separation unit is configured to be connected in sequence,
The carbon dioxide separation device is configured to be connected to the first adsorption unit and the first adsorption unit comprising at least two second adsorption towers filled with the adsorbent to separate the carbon dioxide in the biogas through the adsorbent and the first adsorption unit. 2 is provided with a first carbon dioxide desorption unit for desorbing carbon dioxide adsorbed on the adsorbent in the adsorption tower, and a third adsorption tower configured to be connected to the first carbon dioxide desorption unit, and filled with the adsorbent, by the first carbon dioxide desorption unit. A second carbon dioxide desorption unit configured to be connected to the second adsorption unit for separating carbon dioxide in the desorption gas generated through the adsorbent and the second adsorption unit to desorb carbon dioxide adsorbed on the adsorbent in the third adsorption tower; Biogas pretreatment system comprising.
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The method according to claim 1,
Wherein said first and second carbon dioxide desorption units are configured as pumps.
The method according to claim 1,
At the rear end of the carbon dioxide separator,
A measuring unit for measuring concentrations of hydrogen sulfide, water, methane and carbon dioxide in the biogas;
And a recycling line for recycling the biogas to the front end of the desulfurization unit according to the measured value of the measuring unit.
A biogas pretreatment system for removing and separating impurities and carbon dioxide contained in the biogas for high quality of biogas,
A desulfurization unit for removing hydrogen sulfide in the biogas, a compression unit for compressing the biogas at a constant pressure, a cooling dehumidifying unit for cooling the biogas to remove water, and water in the biogas through an adsorbent. A water removal device comprising an adsorption dehumidification unit for adsorbing, an activated carbon adsorption unit for adsorbing residual hydrogen sulfide, volatile organic compounds, and siloxane in the biogas through activated carbon, and a carbon dioxide separation device for separating carbon dioxide in the biogas Include,
The desulfurization unit, compression unit, carbon dioxide separation unit, cooling dehumidification unit, activated carbon adsorption unit, adsorption dehumidification unit is configured to be connected in sequence,
The carbon dioxide separation unit is a biogas pretreatment system for separating the carbon dioxide by contacting the high pressure biogas with an aqueous solution.
10. The method of claim 9,
The carbon dioxide separator,
And a first regeneration stripper for separating carbon dioxide from the aqueous solution in which the carbon dioxide is dissolved.
A biogas pretreatment system for removing and separating impurities and carbon dioxide contained in the biogas for high quality of biogas,
A desulfurization unit for removing hydrogen sulfide in the biogas, a compression unit for compressing the biogas at a constant pressure, a cooling dehumidifying unit for cooling the biogas to remove water, and water in the biogas through an adsorbent. A water removal device comprising an adsorption dehumidification unit for adsorbing, an activated carbon adsorption unit for adsorbing residual hydrogen sulfide, volatile organic compounds, and siloxane in the biogas through activated carbon, and a carbon dioxide separation device for separating carbon dioxide in the biogas Include,
The desulfurization unit, activated carbon adsorption unit, carbon dioxide separation unit, compression unit, cooling dehumidification unit, and adsorption dehumidification unit is configured to be connected in sequence,
The carbon dioxide separation unit is a biogas pretreatment system for separating carbon dioxide in the biogas through a chemical reaction of the carbon dioxide and the absorbent consisting of an amine compound.
The method of claim 11, wherein
The carbon dioxide separator,
And a second regeneration stripper for regenerating the absorbent by removing carbon dioxide absorbed by the absorbent as heat.
The method according to claim 9 or 11,
At the rear end of the adsorption dehumidification unit,
A measuring unit for measuring concentrations of hydrogen sulfide, water, methane and carbon dioxide in the biogas;
And a recycling line for recycling the biogas to the front end of the desulfurization unit according to the measured value of the measuring unit.