KR20110113095A - Co2 collecting apparatus - Google Patents

Abstract

The present invention relates to a carbon dioxide recovery apparatus, according to an aspect of the present invention, the absorber for absorbing carbon dioxide from the exhaust gas by contacting the exhaust gas and the absorbent; A regenerator for separating carbon dioxide by heating the absorbent discharged from the absorber; A carbon dioxide recovery device comprising: an absorption heat pump operated by using a mixed gas of carbon dioxide and water vapor discharged from the regenerator as a heat source; And a circulation unit for circulating a heat transfer medium between the heater and the absorption heat pump, wherein the carbon dioxide recovery device supplies heat from the mixed gas of carbon dioxide and water vapor discharged from the regenerator to the heater. Is provided.

Description

CO2 Recovery Equipment {CO2 COLLECTING APPARATUS}

The present invention relates to a carbon dioxide recovery apparatus, and more particularly, to an apparatus for minimizing the amount of carbon dioxide emitted to the atmosphere by recovering carbon dioxide contained in the exhaust gas.

Global warming due to the recent increase in carbon dioxide in the atmosphere is one of the important environmental problems that humanity must solve. This carbon dioxide is emitted in large quantities during the burning of fossil fuels, which is particularly problematic in the case of thermal power plants or steel mills. Therefore, a technology for separating and removing only carbon dioxide from exhaust gases generated after burning fossil fuels has been developed, and the already developed carbon dioxide separation techniques include absorption, adsorption, deep cooling, and membrane separation.

Among them, absorption is a method of selectively separating carbon dioxide by contacting combustion or process gas containing carbon dioxide with various solutions (absorbents) capable of absorbing carbon dioxide. Or whether the target material is adsorbed by physical force.

As a technique commercialized in the absorption method, there is a wet amine method having a process as shown in FIG. The wet amine method is a method of recovering carbon dioxide contained in the combustion flue gas and uses an amine-based absorbent. The first commercial facility was built by Dow Chemical in 1982 using a process called "Gas Spec FT-1." The "Gas Spec FT-1" uses a mixture of alkanolamine and corrosion inhibitor as an absorbent. By reducing the deterioration to oxygen, it shows a feature that increased the ability to absorb carbon dioxide. Representative companies "Fluor Daniel" and "ABB Lummus" of the United States are developing carbon dioxide separation process using absorption method.

The conventional wet amine method uses a 16% aqueous solution of monoethanolamine (hereinafter referred to as 'MEA') as a liquid absorbent and absorbs carbon dioxide through a chemical reaction as shown in Chemical Formula 1 below. Here, the dominant element of the reaction is the temperature, carbon dioxide absorption reaction (forward reaction) at 40 ℃ and decarbon dioxide reaction (reverse reaction) at 108 ℃.

The process using the wet amine method is schematically illustrated in FIG. 1. Referring to FIG. 1, the generated exhaust gas is introduced into the absorber 20 by the blower 10. Since the absorbent having a lean concentration is continuously injected into the absorber 20, carbon dioxide contained in the introduced exhaust gas is absorbed by the absorber to be removed from the exhaust gas, and the exhaust gas from which the carbon dioxide is removed is absorbed ( 20) to the atmosphere.

On the other hand, the high concentration absorbent absorbing carbon dioxide from the absorber 20 is introduced into the regenerator 30 by the pump (pep 22). The high temperature absorbent heated by the heater 40 disposed adjacent to the regenerator 30 is supplied, and the carbon dioxide and steam which have been absorbed by the absorbent by the thermal energy supplied therefrom are discharged from the regenerator 30. do. In addition, a lower concentration of the absorbent in which carbon dioxide is removed is discharged to the lower portion of the regenerator 30. Some of the absorbent thus discharged is supplied to the heater 40 side and the other part is supplied to the absorber 20 by the pump 32.

Then, the mixed gas of carbon dioxide and steam discharged from the regenerator 30 is supplied to the condenser 50 and cooled, whereby the steam contained in the mixed gas is liquefied and only carbon dioxide is discharged from the condenser 50, The liquefied water is supplied to the absorber 20, mixed with a low concentration of absorbent, and supplied back to the absorber 20.

The gaseous carbon dioxide passing through the condenser 50 is compressed to a high pressure by the compressor 60 and stored in a separate place to separate and store carbon dioxide contained in the exhaust gas after concentration. Meanwhile, the low temperature absorbent passing through the absorber 20 and the relatively high temperature absorbent passing through the regenerator 30 are heat exchanged in the sensible heat exchanger 70 to reduce energy consumption.

Most of the energy required to drive the conventional carbon dioxide recovery device having the above configuration is consumed in the heater 40 for supplying a high temperature absorbent and steam to the regenerator 30. The heat energy supplied by the heater 40 is consumed not only in the reaction of separating carbon dioxide in the regenerator 30, but also in considerable amount in the evaporation of the mixed water. Investigations have found that 30 to 70 percent of the supplied thermal energy is required to evaporate water vapor.

In the case of a thermal power plant, steam is generally supplied at the low pressure stage of the steam turbine at a temperature higher than the regeneration temperature (100 to 140 ° C.) of the absorbent to be supplied to the heater 40, but as the amount of heat required increases, the amount of steam added is also increased. This should be a problem, which leads to a reduction in power generation power and a reduction in power generation efficiency.

The present invention has been made to overcome the problems of the prior art as described above, the technical problem is to provide a carbon dioxide recovery apparatus that can minimize the energy required to regenerate the absorbent.

According to an aspect of the present invention for achieving the above technical problem, the absorber for absorbing carbon dioxide from the exhaust gas in contact with the exhaust gas and the absorbent; A regenerator for separating carbon dioxide by heating the absorbent discharged from the absorber; A carbon dioxide recovery device comprising: an absorption heat pump operated by using a mixed gas of carbon dioxide and water vapor discharged from the regenerator as a heat source; And a circulation unit for circulating a heat transfer medium between the heater and the absorption heat pump, wherein the carbon dioxide recovery device supplies heat from the mixed gas of carbon dioxide and water vapor discharged from the regenerator to the heater. Is provided.

That is, according to the above aspect of the present invention, the heat of the mixed gas (hereinafter referred to as 'mixed gas') of the carbon dioxide and water vapor discharged through the regenerator is transferred to the heater side by using a heat pump is discharged to the atmosphere The heat can be utilized to reduce the heat consumed by the heater. In this case, as the heat pump, an absorption type heat pump operated using an absorbent for moving heat while absorbing or discharging water vapor may be used, and the aqueous solution of lithium bromide may be used as the absorbent.

On the other hand, the mixed gas is condensed to produce the condensed water by passing the heat amount in the process of passing the heat pump to the outside, the condensed water pipe for supplying the condensed water to the absorber additionally Can be.

On the other hand, the absorption heat pump includes a generator for separating the rare solution of the lithium bromide aqueous solution into the concentrated solution and the refrigerant vapor by the heat transferred from the mixed gas; A condenser for condensing the refrigerant vapor generated in the generator; An evaporator for evaporating the condensation refrigerant supplied from the condenser by heat transferred from the mixed gas; And a heat transfer medium circulating inside the circulation unit by heat generated by absorbing the refrigerant vapor generated by the evaporator into the concentrated solution of the lithium bromide aqueous solution and absorbing the refrigerant vapor into the lithium bromide aqueous solution. It may include a refrigerant absorber for heating.

Here, a concentrated solution pipe and a rare solution pipe connecting the generator and the refrigerant absorber, and may include additional sensible heat exchanger to perform heat exchange between the concentrated solution pipe and the rare solution pipe.

The generator and the condenser may be partitioned by a gas-liquid separator through which only refrigerant vapor passes. In addition, the evaporator and the refrigerant absorber may also be partitioned by a gas-liquid separator.

The regenerator includes a mixed gas discharge tube for discharging the mixed gas of the carbon dioxide and water vapor, and the mixed gas discharge tube is branched to pass through the generator and the evaporator to operate as a heat source of the absorption heat pump. can do.

In addition, the inside of the generator may be provided with a rare-solution injection nozzle for injecting a lithium bromide dilute solution on the surface of the mixed gas discharge tube.

In addition, the inside of the refrigerant absorber may be provided with a concentrated solution injection nozzle for injecting a concentrated solution on the surface of the circulation unit.

The circulation unit may further include a circulation passage extending between the heater and the refrigerant absorber; And a pump to circulate a heat transfer medium in the circulation passage.

The absorption heat pump may further include a first generator for separating a heavy solution of an aqueous lithium bromide solution into a concentrated solution and a refrigerant vapor by heat transferred from the mixed gas; A second generator for separating the rare solution of the lithium bromide aqueous solution into a heavy solution and a refrigerant vapor by heat from the refrigerant vapor generated by the first generator; A condenser to condense the refrigerant vapor generated in the first and second generators; An evaporator for evaporating the condensation refrigerant supplied from the condenser by heat transferred from the mixed gas; And a heat transfer medium circulating inside the circulation unit by heat generated by absorbing the refrigerant vapor generated by the evaporator into the concentrated solution of the lithium bromide aqueous solution and absorbing the refrigerant vapor into the lithium bromide aqueous solution. It may include a refrigerant absorber for heating.

Through this, the heat energy of the mixed gas discharged from the regenerator in the absorption heat pump can be extracted in two stages through the first and second generators to generate the refrigerant vapor, thereby further improving the efficiency.

At this time, the heavy solution pipe for supplying the heavy solution from the second generator to the first generator, the concentrated solution pipe for supplying the concentrated solution from the second generator to the router refrigerant absorber and the rare solution from the refrigerant absorber to the second generator And a first solution and a second sensible heat exchanger for supplying heat exchange between the heavy solution pipe and the rare solution pipe and between the concentrated solution pipe and the rare solution pipe.

The second generator and the condenser may be partitioned by a gas-liquid separator through which only refrigerant vapor passes, and the evaporator and the refrigerant absorber may be partitioned by a gas-liquid separator.

In addition, the regenerator may include a mixed gas discharge tube for discharging the mixed gas of carbon dioxide and water vapor, and the mixed gas discharge tube may be branched to pass through the first generator and the evaporator.

In addition, the first generator may be provided with a heavy solution injection nozzle for injecting a lithium bromide heavy solution on the surface of the mixed gas discharge pipe, and spraying the concentrated solution on the surface of the circulation unit in the refrigerant absorber A concentrated liquid injection nozzle may be provided.

According to aspects of the present invention having the configuration as described above, it is possible to minimize the amount of heat to be supplied in regenerating the absorbent aqueous solution absorbing carbon dioxide can reduce the operating cost of the carbon dioxide recovery apparatus.

1 is a system diagram showing an example of a conventional general carbon dioxide recovery apparatus.
2 is a system diagram showing a first embodiment of a carbon dioxide recovery apparatus according to the present invention.
FIG. 3 is an enlarged schematic diagram of an absorption heat pump part of the embodiment shown in FIG. 2.
4 is a diagram showing an operating state of the absorption heat pump of the embodiment shown in FIG.
5 is a system diagram showing a second embodiment of a carbon dioxide recovery apparatus according to the present invention.
FIG. 6 is an enlarged schematic diagram of an absorption heat pump part of the embodiment illustrated in FIG. 5.
FIG. 7 is a diagram illustrating an operating state of the absorption heat pump in the embodiment illustrated in FIG. 5.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the carbon dioxide recovery apparatus according to the present invention.

Figure 2 is a schematic diagram showing a first embodiment of the carbon dioxide recovery apparatus according to the present invention, Figure 3 is a schematic diagram showing an enlarged absorption type heat pump shown in FIG. For reference, in the following description, components similar to those shown in FIG. 1 are denoted by the same reference numerals, and redundant descriptions thereof will be omitted. 2, an absorption heat pump including a generator 100, a condenser 120, an evaporator 140, and a refrigerant absorber 160 is provided adjacent to an outlet end side of the regenerator 30.

Thermal energy required for the operation of the absorption heat pump is provided from a mixture of carbon dioxide and water vapor discharged from the regenerator 30. Specifically, the discharge pipe 34 of the regenerator 30 includes a first branch pipe 34a and a second branch pipe 34b branched into the generator 100 and the evaporator 140, respectively. Each branch pipe is configured to pass through the internal space of the generator 100 and the evaporator 140 in a zigzag form.

The heat energy absorbed by the discharge tube 34 is moved to the refrigerant absorber 160 as a result of the operation of the absorption heat pump, which is installed between the refrigerant absorber 160 and the heater 40. It is supplied to the heater 40 by the circulation unit 170 is to be able to supply the heat energy required for the operation of the regenerator 30. Here, the circulation unit 170 is configured to provide a heat transfer medium, that is, a water circulating between the refrigerant absorber 160 and the heater 40, that is, the water in the circulation flow path 172. Pump 174 for pumping.

Meanwhile, the mixed gas in the discharge pipe 34 is cooled while transferring heat to the absorption heat pump side, and condensed water is generated by condensing water vapor contained in the mixed gas in the process. At this time, the condensed water is supplied back to the absorber 20 through the condensed water pipe 36, and the carbon dioxide in the gas state is supplied to the compressor 60 through the carbon dioxide pipe 38.

On the other hand, the generator 100 and the condenser 120 of the absorption heat pump is partitioned from each other by the gas-liquid separator (110). The gas-liquid separator does not pass the rare solution injected through the rare solution nozzle 104 to be described later, and allows only the vapor vaporized from the rare solution to pass therethrough. That is, the rare solution stored in the bottom surface of the refrigerant absorber 160 is supplied through the rare solution supply pipe 102 to the inside of the generator 100 and then injected through the rare solution injection nozzle 104. At this time, the injected rare solution is injected onto the surface of the first branch pipe 34a, and water as the refrigerant contained in the rare solution is heated by the heat of the mixed gas (approximately 100 ° C.) flowing through the first branch pipe 34a. Evaporation will produce water vapor.

The water vapor generated in this way is passed to the condenser 120 through the gas-liquid separator 110, the concentration of the rare solution is increased by the evaporation of water to produce a concentrated solution. 4 is a During diagram showing the state of the aqueous lithium bromide solution in the absorption heat pump, in the generator 100, the lithium bromide aqueous solution moves from point 1 to point 2 to become a concentrated solution. The agricultural solution thus generated is temporarily stored on the bottom surface of the generator 100 and then supplied to the refrigerant absorber 160 through the agricultural liquid pipe 162.

Meanwhile, the water vapor supplied to the condenser 120 through the gas-liquid separator 110 is cooled and condensed by the cooling water pipe 122 passing through the condenser 120, thereby condensing the condenser 120. At the bottom, condensate is temporarily stored. The condensed water thus stored is supplied to the evaporator 140 through the refrigerant supply pipe 124 and is injected by the refrigerant injection nozzle 142. At this time, since the second branch pipe 34b passes through the evaporator 140, condensed water injected by the thermal energy of the mixed gas flowing in the second branch pipe 34b evaporates to generate water vapor. .

The water vapor thus generated passes through the gas-liquid separator 130 and moves to the refrigerant absorber 160. On the other hand, as described above, since the concentrated solution is injected through the concentrated solution injection nozzle 164 inside the refrigerant absorber 160, the moved water vapor is in contact with the concentrated solution is absorbed. Thus, the lithium bromide aqueous solution is diluted by the amount of water vapor absorbed into a rare solution, and is supplied to the generator 100 through the rare solution supply pipe 102. In addition, a sensible heat exchanger 150 is installed between the rare solution supply pipe 102 and the agricultural solution supply pipe 162 so that heat exchange is performed between both, thereby further improving the efficiency of the apparatus.

Referring back to FIG. 4, the concentrated lithium bromide aqueous solution has a temperature increase while passing through the sensible heat exchanger 150, moves from point 2 to point 3, and is diluted in a process of absorbing water vapor to form a rare solution. This moves to point 4. The rare solution is then cooled by the sensible heat exchanger 150 to return to point 1.

On the other hand, the internal temperature of the refrigerant absorber 160 is a high temperature (about 120 ℃) due to the heat generated in the absorbent of the agricultural solution absorbs the water vapor, thereby the water flowing in the circulation passage 172 Vaporized in the circulation passage 172 is supplied to the heater 40 in the state of steam. Therefore, the amount of heat consumed by the heater 40 is reduced by the amount of heat supplied by the absorption heat pump.

5 is a system diagram showing a second embodiment of a carbon dioxide recovery apparatus according to the present invention. The second embodiment differs from the first embodiment in that the absorption heat pump is configured to include the first and second generators 200 and 220.

That is, the first branch pipe 34a is configured to pass through the inside of the first generator 200. A medium concentration lithium bromide aqueous solution (hereinafter, referred to as 'heavy solution') supplied from the second generator 220 partitioned by the condenser 120 and the gas-liquid separator 110 inside the first generator 200. The heavy solution injection nozzle 204 is injected, and the heavy solution injection nozzle 204 is connected to the heavy solution pipe 202 connected to the second generator 220 to receive the heavy solution.

In addition, a steam supply pipe 210 is installed between the first generator 200 and the condenser 120 so that the steam generated in the first generator 200 is supplied to the condenser 120. However, the steam supply pipe 210 passes through the inside of the second generator 220 and is configured to supply heat to the inside of the second generator 220, whereby the water vapor in the steam supply pipe 210 It is condensed while passing through the second generator 220, and is actually supplied to the condenser 120 as condensed water.

Meanwhile, a concentrated solution pipe 206 is installed between the first generator 200 and the refrigerant absorber 160, and an end portion of the concentrated solution pipe 208, that is, the inside of the refrigerant absorber 160 is concentrated. A concentrated liquid injection nozzle 208 is provided to supply a solution into the refrigerant absorber 160. In addition, between the second generator 220 and the refrigerant absorber 160, a rare solution pipe 222 through which a rare solution temporarily stored in the refrigerant absorber 160 flows is installed, and the rare solution pipe A rare solution injection nozzle 224 is installed at an end of the second generator 222, that is, inside the second generator 220.

In addition, a first sensible heat exchanger 240 is installed between the heavy solution pipe 202 and the rare solution pipe 222, and between the agricultural solution pipe 206 and the rare solution pipe 222. 2 sensible heat exchanger 250 is installed.

Now, operation of the second embodiment will be described with reference to FIG.

In FIG. 7, point 1 corresponds to a state of the aqueous lithium bromide solution in the second generator 220, and receives moisture from water vapor passing through the second generator 220, and contains moisture in the aqueous solution. As it evaporates, it moves to the condenser 120. At this time, the concentration of the heavy solution gradually increases as the water content is lowered. At this time, the concentration is increased to a temperature (point 2) that is in equilibrium with the steam temperature in the steam supply pipe 210.

The generated heavy solution is changed to the point 2 'state while passing through the first sensible heat exchanger 240, and water is absorbed by the heat supplied from the first branch pipe 34a inside the first generator 200. The concentration increases to point 2 "while evaporating. The concentration increases until the temperature of the aqueous lithium bromide solution is in equilibrium with the temperature of the mixed gas in the first branch pipe 34a. do.

The concentrated solution thus formed is supplied to the refrigerant absorber 160 in a state where the temperature is increased to point 3 while passing through the second sensible heat exchanger 250. The refrigerant absorber 160 moves to point 4 while absorbing the steam supplied from the evaporator 140 while releasing thermal energy into the refrigerant absorber 160 and passing through the first and second sensible heat exchangers. Return to the second generator 220 in the state of the point 1.

In the second embodiment, since heat is absorbed in two steps compared with the first embodiment, higher efficiency can be expected.

Claims (17)

An absorber for contacting the exhaust gas with the absorbent to absorb carbon dioxide from the exhaust gas; A regenerator for separating carbon dioxide by heating the absorbent discharged from the absorber; A carbon dioxide recovery apparatus comprising: a heater for heating a low concentration of absorbent and water discharged from the regenerator and resupplying it to the regenerator.
An absorption heat pump operated using a mixed gas of carbon dioxide and water vapor discharged from the regenerator as a heat source; And
And a circulation unit for circulating a heat transfer medium between the heater and the absorption heat pump, wherein the carbon dioxide recovery apparatus supplies heat from the mixed gas of carbon dioxide and water vapor discharged from the regenerator to the heater. The method of claim 1,
And a condensate tube for supplying condensate condensed from the mixed gas to the absorber while passing through the absorption heat pump. The method of claim 1,
The absorption heat pump,
A generator for separating the rare solution of the lithium bromide aqueous solution into the concentrated solution and the refrigerant vapor by the heat transferred from the mixed gas;
A condenser for condensing the refrigerant vapor generated in the generator;
An evaporator for evaporating the condensation refrigerant supplied from the condenser by heat transferred from the mixed gas; And
The refrigerant vapor generated in the evaporator is absorbed into the concentrated solution of the lithium bromide aqueous solution to generate a rare solution, and at the same time, a heat transfer medium circulating inside the circulation unit by heat generated while the refrigerant vapor is absorbed into the lithium bromide aqueous solution. Carbon dioxide recovery apparatus comprising a; refrigerant absorber. The method of claim 3,
It includes a concentrated liquid pipe and a rare liquid pipe connecting between the generator and the refrigerant absorber,
Carbon dioxide recovery device further comprises a sensible heat exchanger to allow heat exchange between the agricultural fluid pipe and the rare water pipe. The method of claim 3,
And the generator and the condenser are partitioned by a gas-liquid separator through which only refrigerant vapor passes. The method of claim 3,
And the evaporator and the refrigerant absorber are partitioned by a gas-liquid separator through which only refrigerant vapor passes. The method of claim 3,
The regenerator includes a mixed gas discharge tube for discharging the mixed gas of the carbon dioxide and water vapor,
And the mixed gas discharge tube is branched to pass through the generator and the evaporator. The method of claim 7, wherein
And a rare-solution injection nozzle for injecting a lithium bromide dilute solution onto the surface of the mixed gas discharge tube. The method of claim 7, wherein
The inside of the refrigerant absorber is a carbon dioxide recovery apparatus, characterized in that a concentrated solution injection nozzle for injecting a concentrated solution on the surface of the circulation unit. The method of claim 3,
The circulation unit,
A circulation passage extending between the heater and the refrigerant absorber; And
And a pump for circulating a heat transfer medium in the circulation passage. The method of claim 1,
The absorption heat pump
A first generator for separating the heavy solution of the lithium bromide aqueous solution into the concentrated solution and the refrigerant vapor by the heat transferred from the mixed gas;
A second generator for separating the rare solution of the lithium bromide aqueous solution into a heavy solution and a refrigerant vapor by heat from the refrigerant vapor generated by the first generator;
A condenser to condense the refrigerant vapor generated in the first and second generators;
An evaporator for evaporating the condensation refrigerant supplied from the condenser by heat transferred from the mixed gas; And
The refrigerant vapor generated in the evaporator is absorbed into the concentrated solution of the lithium bromide aqueous solution to generate a rare solution, and at the same time, a heat transfer medium circulating inside the circulation unit by heat generated while the refrigerant vapor is absorbed into the lithium bromide aqueous solution. Carbon dioxide recovery apparatus comprising a; refrigerant absorber. The method of claim 11,
A heavy solution pipe for supplying the heavy solution from the second generator to the first generator, a farm solution pipe for supplying the concentrated solution to the first refrigerant generator, and a rare solution for supplying the rare solution from the refrigerant absorber to the second generator Includes rare water piping,
Carbon dioxide recovery apparatus further comprises a first and second sensible heat exchanger to perform heat exchange between the heavy solution pipe and the rare solution pipe and between the agricultural fluid pipe and the rare solution pipe. The method of claim 11,
And the second generator and the condenser are partitioned by a gas-liquid separator through which only refrigerant vapor passes. The method of claim 11,
And the evaporator and the refrigerant absorber are partitioned by a gas-liquid separator through which only refrigerant vapor passes. The method of claim 11,
The regenerator includes a mixed gas discharge tube for discharging the mixed gas of the carbon dioxide and water vapor,
And the mixed gas discharge pipe is branched and passes through the first generator and the evaporator. 16. The method of claim 15,
The inside of the first generator is a carbon dioxide recovery apparatus characterized in that the heavy solution injection nozzle for injecting a lithium bromide heavy solution on the surface of the mixed gas discharge pipe. 16. The method of claim 15,
The inside of the refrigerant absorber is a carbon dioxide recovery apparatus, characterized in that a concentrated solution injection nozzle for injecting a concentrated solution on the surface of the circulation unit.

Images