KR100791091B1 - Condensation-absorption hybrid tower for simultaneous water vapor condensing and ammonia scrubbing - Google Patents

Abstract

An apparatus for separating and recovering carbon dioxide simply and efficiently is provided to recover high purity carbon dioxide, use a minimum amount of water, and scrub ammonia at a low temperature by exhausting carbon dioxide only from a mixture of carbon dioxide, water vapor and ammonia gas from an upper part of a carbon dioxide stripping tower, washing ammonia gas with water, and condensing water vapor, thereby injecting the condensed water vapor again into the stripping tower. An apparatus for producing high purity carbon dioxide from a mixed gas containing carbon dioxide comprises: a first absorption tower(101) for optionally absorbing carbon dioxide from waste gas using ammonia water; a stripping tower(103) for stripping carbon dioxide from ammonia water containing carbon dioxide; a third absorption tower(106) for absorbing ammonia gas contained in the stripped carbon dioxide using water; a second absorption tower(105) for removing ammonia contained in waste gas(114) from the top of the first absorption tower using water and sending ammonia-containing water to the third absorption tower; a first heat exchanger(102) for exchanging heat between carbon dioxide-containing ammonia water from the first absorption tower and recirculating ammonia water from the stripping tower; a concentration tower(107) for recirculating ammonia-containing water to the second absorption tower while recirculating the concentrated ammonia water to the stripping tower after concentrating some of ammonia water from the stripping tower; and a second heat exchanger(110) for exchanging heat between water discharged from the concentration tower and carbon dioxide-containing ammonia water discharged from the first heat exchanger, wherein the third absorption tower is a condensation-absorption hybrid tower for exhausting carbon dioxide only from a mixture of carbon dioxide, water vapor and ammonia gas exhausted from the top of the stripping tower, washing ammonia gas with water, and condensing water vapor to inject the condensed water vapor into the stripping tower again.

Description

Condensation-absorption hybrid tower for simultaneous water vapor condensing and ammonia scrubbing}

1 is a process chart showing the configuration of an apparatus for recovering carbon dioxide using ammonia water as an absorbent liquid which can be used as the condensation merger absorption tower of the present invention.

<Description of Major Symbols in Drawing>

101: first absorption tower for recovering carbon dioxide from the mixed gas into ammonia water

102: first heat exchanger

103: stripping tower to remove carbon dioxide from ammonia water absorbed

104: first reboiler as an accessory to the stripping column shown in 103;

105: second absorption tower for absorbing ammonia contained in trace amount in exhaust gas from which carbon dioxide has been removed with water

106: third absorption tower for absorbing ammonia contained in the stripped carbon dioxide with water

107: a concentration tower for removing the water used in the second absorption tower 105 and the third absorption tower 106 to increase the ammonia water concentration

108: second reboiler as an accessory of the enrichment tower shown in 107 above

109: first circulation pump for recycling carbon dioxide stripped ammonia water to the absorption tower

110: second heat exchanger

111: second circulation pump for recycling water discharged from the bottom of the concentration tower to the second absorption tower

112: mixed gas containing carbon dioxide supplied to the first absorption tower 101

113: Ammonia absorbing liquid supplied from the circulation pump 109 and heat exchanged with the effluent of the absorption tower bottom

114: exhaust gas discharged after carbon dioxide is removed from the absorption tower 101, and gas supplied to the lower portion of the second absorption tower 105 for removing a small amount of ammonia contained therein.

115: carbon dioxide-containing absorbent liquid discharged into the absorption tower 101 and passed through the first heat exchanger 102 and the second heat exchanger 110.

116: clean flue gas in which carbon dioxide is removed from the mixed gas containing carbon dioxide and the trace amount of ammonia is removed while passing through the first absorption tower 101.

117: a small amount of ammonia is removed from the carbon dioxide discharged from the stripping column 103

118: ammonia gas vaporized in the upper part of the concentration tower 107 and injected into the bottom of the stripping column

119: The ammonia water supplied to the top of the concentration tower 107 by the amount of water 120 is removed from the second reboiler 104 below the stripping column 103 and supplied to the upper portion of the second absorption tower 105.

120: discharged from the second reboiler 108 under the concentration tower 107 to increase the ammonia water concentration, cooled through the second heat exchanger 110, and contained in the exhaust gas 116 from which carbon dioxide is removed and the removed carbon dioxide Water circulated to absorb traces of ammonia

121: cooling tower

122: Low temperature heat medium exiting the cooling tower 121 and enters the third absorption tower 106

123: the high temperature heat medium to be returned to the cooling tower after heat exchange in the third absorption tower 106

The present invention is a device for effectively separating the carbon dioxide and the trace amount of ammonia gas discharged from the carbon dioxide stripping tower in the apparatus for removing carbon dioxide from the mixed gas containing carbon dioxide, such as combustion exhaust gas using the ammonia water as the absorbent liquid 40 ~ 80 ^o C The present invention relates to a device for condensing water vapor and ammonia gas from a mixed gas including steam, carbon dioxide, and ammonia gas discharged at a temperature of about 2% to a stripping column at a lower part, and discharging high-purity carbon dioxide to the upper part using a difference in solubility.

As a method of removing or recovering carbon dioxide using the absorbent liquid, it is common to use an amine solution as the absorbent liquid. The composition of the device for removing carbon dioxide by using the amine-based solution as an absorbent liquid includes an absorption tower that absorbs carbon dioxide into a mixed gas, a stripping column that removes carbon dioxide from a solution that absorbs carbon dioxide, and transfers heat to the absorbent liquid to remove carbon dioxide. It is composed of a reboiler at the bottom of the stripping tower, and a condenser for condensing water vapor through heat exchange in a mixture of water vapor and carbon dioxide discharged from the stripping column, circulating to the stripping column, and discharging carbon dioxide. In an apparatus using an amine absorbent liquid, the stripping column has a temperature in the range of 100 to 150 ^° C. and the amine compound in the stripping column does not evaporate with water vapor. Therefore, the condenser at the top of the stripping column simply performs heat exchange, condensing only water vapor, and functions. However, when ammonia water is used as the absorption liquid, the temperature range in the stripping column is 40 to 80 ^° C., and less water vapor is evaporated than a device using an amine absorption liquid, but a considerable amount of ammonia gas is discharged together with carbon dioxide. The use of a condenser in a device using an existing amine absorbent will release a significant amount of ammonia gas classified as a noxious gas.

Therefore, the present invention relates to a condensation merging absorption tower in which the ammonia wash function is added to the function of the condenser of the heat medium circulation pipe for heat exchange inside and outside of the condenser and a device using a conventional amine absorbent. . The heating medium circulation jacket was installed outside the condensation merger absorption tower and the coil type or linear heat exchanger was installed inside. Filled material is filled in a place other than the space occupied by the heat exchanger to smoothly disperse the water introduced from the upper portion. The condensation merger absorption tower combined with this configuration can effectively control the temperature rising by the ammonia gas and water vapor rising from the bottom of the condensation merger absorption tower by the improved heat conduction by the filling material, and thus the input from the top The amount of water to be minimized to dissolve the ammonia gas from the bottom and re-injected to the top of the stripping column to prevent a decrease in ammonia concentration in the stripping column.

The present invention condenses and reinjects water vapor into the stripping column using a condensation merging absorption tower from the water vapor, carbon dioxide, and a small amount of ammonia mixture discharged to the top of the stripping column in the apparatus using ammonia water as the absorbing liquid, and simultaneously By using the difference in solubility in water, ammonia is separated from carbon dioxide and returned to the stripping column to recover only high purity carbon dioxide. As described above, carbon dioxide, ammonia gas, and water vapor are discharged at a temperature range of 40 to 80 ^° C. In order to separate only carbon dioxide from the gas mixture, steam removal by condensation and ammonia washing by water washing should be performed at the same time. If an absorption tower is installed that can only perform ammonia cleaning, the amount of heat transferred by the ammonia gas, carbon dioxide and water vapor from the stripping tower must be excessively large to clean the ammonia. To this end, excess water is introduced into the stripping column, which leads to a low ammonia concentration and excessive inflow of energy into the ammonia concentration tower to remove the excess water. If only condensation towers are installed, the ammonia gas in the gas reacts with carbon dioxide to form salts, which can clog the piping and make it difficult to remove the effective ammonia gas. In addition, if the condenser for removing water vapor and the washing tower for washing ammonia are independently installed at the same time, the equipment costs are increased and the apparatus is enlarged by separate equipment, and the above problems remain. Therefore, an object of the present invention by using a condensation combined absorption tower having the function of a washing tower for washing ammonia and a condensation of steam at the same time by using a minimum of water to wash ammonia at a low temperature and effectively condensing water vapor by It is to simplify the carbon dioxide separation and recovery apparatus using ammonia water as the absorption liquid and to increase the efficiency.

A steam condenser is generally installed in a device for removing and recovering carbon dioxide using an existing amine-based absorbent liquid. And in other distillation process, a condenser is installed for heat exchange and product recovery. However, there is no known or attempted apparatus for removing ammonia contained in the carbon dioxide gas recovered as in the present invention and recovering it by condensing water vapor which is evaporated at the same time.

The present invention discharges only carbon dioxide from a mixture of carbon dioxide, water vapor and ammonia gas discharged from the upper portion of the carbon dioxide stripping tower in the carbon dioxide separation and recovery apparatus using ammonia water as the absorption liquid, wash off the ammonia gas with water, condensing the steam to remove the column The present invention is to provide a simple and efficient carbon dioxide separation and recovery apparatus using minimal water and washing ammonia at a low temperature while recovering high purity carbon dioxide by reconstructing the condensation merger absorption tower.

The present invention uses ammonia water as an absorption liquid to remove ammonia gas and water vapor from a mixture of carbon dioxide, water vapor, and ammonia gas discharged from the top of the carbon dioxide stripping tower in a device for separating carbon dioxide from a mixed gas containing carbon dioxide such as exhaust gas. An apparatus for effectively separating, reinjecting into a system and recovering high purity carbon dioxide. The temperature of the mixture of carbon dioxide, water vapor, and ammonia gas discharged to the top of the stripping tower is 40 to 80 ^o C. When using 10wt% ammonia water as the absorbent, the equilibrium partial pressure of ammonia is 167 ~ 716 mmHg and the equilibrium partial pressure of water is 55 ~ 355mmHg at 40 ~ 80 ^o C. Discharged to the top. In order to selectively separate ammonia gas and water vapor from carbon dioxide in the mixed gas, the temperature of the mixed gas is reduced by heat exchange to condense the water vapor, and at the same time, ammonia, which has high solubility in water, is absorbed into the water from outside. It is necessary to discharge only. Accordingly, the present invention is to provide a method and an apparatus capable of simultaneously performing such water vapor condensation and ammonia absorption.

Prior to describing the condensation merging absorption tower of the present invention, an apparatus which may include the condensation merging absorption tower of the present invention, that is, the ammonia water shown in FIG. It is necessary to explain the structure and the process of the apparatus which collect | recovers carbon dioxide using as an absorption liquid. The description of the apparatus shown in FIG. 1 is as follows. The apparatus of FIG. 1 is a first absorption tower 101 for selectively absorbing carbon dioxide using ammonia water, and a second absorption tower for dissolving and removing ammonia gas contained in exhaust gas 114 from which carbon dioxide has been removed. 105), a stripping column 103 for removing carbon dioxide from the absorbed liquid absorbed by carbon dioxide, a third absorption tower 106 for absorbing ammonia contained in the stripped carbon dioxide into water, and used to absorb ammonia gas. It is composed of a concentration tower 107 for removing water 120 and increasing the concentration of ammonia water, absorption liquid circulation pumps 109 and 111, heat exchangers 102 and 110, and the like. The method of recovering carbon dioxide using ammonia water is as follows. The mixed gas 112 including carbon dioxide is supplied to the lower portion of the first absorption tower 101, and the exhaust gas 114 from which carbon dioxide is removed is discharged to the upper portion thereof. At the same time, the ammonia water 114 is supplied to the upper portion of the first absorption tower 101 to discharge the ammonia water 115 absorbed with carbon dioxide. Ammonium water 115 absorbed with carbon dioxide discharged to the first absorption tower 101 is supplied to the upper part of the stripping column 103 via the first heat exchanger 102, and in the stripping column 103, carbon dioxide is removed. Ammonia water containing bovine is heated to 70 ~ 88 ^o C to release carbon dioxide as a gas. The stripping column 103 is a kind of distillation column to discharge carbon dioxide containing a small amount of ammonia to the top and discharge the ammonia water 113 from which carbon dioxide is stripped to the bottom. The exhaust gas 114 from which carbon dioxide is discharged to the upper portion of the first absorption tower 101 is removed is sent to the second absorption tower 105 using water as an absorption liquid to remove and discharge a small amount of ammonia contained therein (116). ). Trace ammonia-containing water coming out of the bottom of the second absorption tower 105 is supplied to the top of the third absorption tower (106). The carbon dioxide containing a small amount of ammonia discharged to the stripping column is sent to the third absorption tower 106 using water as an absorption liquid, and the ammonia is removed to be discharged as high purity carbon dioxide. At this time, water containing a small amount of ammonia discharged from the lower portion of the third absorption tower 106 is supplied to the upper portion of the stripping column 103. That is, the ammonia water containing carbon dioxide discharged from the carbon dioxide first absorption tower 101 and the water containing a small amount of ammonia from the third absorption tower 106 are simultaneously supplied to the stripping column 103. The lower portion of the ammonia concentration tower 107 is to remove the amount 120 corresponding to the amount of water supplied to the upper portion of the ammonia second absorption tower 105. In other words, the ammonia concentration tower 107 serves to increase the ammonia concentration lowered by the water supplied to the apparatus and to remove excess water. The temperature of the water 120 removed from the concentration tower is 90 ~ 100 ^o C and ammonia is dissolved. The release of this water out of the system causes a constant loss of traces of ammonia in the system. To compensate for this, the water 120 is used to remove traces of ammonia that are cooled through the second heat exchanger 110 and discharged back to the second absorption tower 105.

In the carbon dioxide recovery apparatus using the above-described ammonia water as the absorption liquid, the third absorption tower 106 may be replaced with the condensation merger absorption tower of the present invention. The condensation merging absorption tower of the present invention is as follows. Ammonia-containing carbon dioxide gas and water vapor discharged from the top of the stripping column 103 are injected into the bottom of the condensation merger absorption tower. In the cooling tower 121, the low temperature (0 ~ 30 ^° C) heat medium 122 enters the inlet of the heat exchanger, which is a component of the condensation merging tower, and the heat medium 123 exiting the outlet through heat exchange is recycled back to the cooling tower 121. Is cooled. Through the heat exchange, water vapor injected from the bottom of the condensation merging absorption tower 106 is condensed, and some ammonia is dissolved in the condensed water and discharged again in the form of ammonia water to the bottom of the tower. Water 120 containing a small amount of ammonia is introduced to the top of the condensation merger absorption tower 106 at a low temperature to wash away undissolved ammonia by the condensed water in the tower, and condensed water under the condensation merger absorption tower with ammonia water. Joined and discharged to the bottom. With this type of operation, only high-purity carbon dioxide is emitted to the top of the tower. In the tower, the empty space except the space occupied by the heat exchange pipe was filled with the filling to maximize the contact between the water coming from the top of the tower and the gas coming from the bottom.

Preferably, the present invention provides a method of producing high purity carbon dioxide from a mixed gas containing carbon dioxide, and supplying 5-15 wt% aqueous ammonia solution to the upper portion of the first absorption tower 101 at a temperature of 0-40 ^° C. And introducing a mixed gas containing carbon dioxide into the lower portion of the first absorption tower 101 to absorb carbon dioxide contained in the mixed gas into ammonia water and sending the absorbed liquid absorbed carbon dioxide to the stripping column 103 to 70 to 88 ^° C. To remove the carbon dioxide, and to cool the ammonia water 113 from which carbon dioxide has been removed to the first heat exchanger (102) and recycle it back to the first absorption tower (101) while removing the removed carbon dioxide to the third absorption tower (106). Send trace ammonia to produce high-purity carbon dioxide as a product, absorb the trace amount of ammonia contained in the treated flue gas into water in the second absorption tower and Water containing ammonia is concentrated from the stripping column 103 by the amount of water circulated to the second absorption tower 105 to guide the water containing the upper portion of the third absorption tower 106 to remove the trace ammonia in the treated flue gas. Sending to the tower 107 to remove the ammonia through distillation and discharged through the second reboiler 108 and the discharged water 120 is cooled through heat exchange to recycle again to the top of the second absorption tower 105 In the third absorption tower discharges only carbon dioxide from the mixture of carbon dioxide, water vapor, and ammonia gas discharged from the stripping column 103, washing the ammonia gas with water, condensing the water vapor and re-injecting it into the stripping column Characterized in that the condensation merger absorption tower, to provide a method for recovering high purity carbon dioxide.

In addition, the present invention is a device for producing high-purity carbon dioxide from the mixed gas containing carbon dioxide, the first absorption tower 101 for selectively absorbing carbon dioxide from the exhaust gas using ammonia water, carbon dioxide in the carbon dioxide-containing ammonia water absorbed carbon dioxide In the stripping column 103 for removing the gas, the third absorption tower 106 for absorbing the ammonia gas contained in the stripped carbon dioxide into the water, and the exhaust gas 114 from the upper portion of the first absorption tower. Between the second absorption tower 105, the carbon dioxide-containing ammonia water from the first absorption tower 101, and the recycled ammonia water from the stripping column 103, which removes the existing ammonia with water and sends the ammonia-containing water to the third absorption tower 106. Heat exchanger 102 for exchanging heat in the water, to remove the water used to absorb the ammonia gas A concentration tower 107 for concentrating a portion of the ammonia water from the bottom of the stripping column 103 to increase the concentration and recycling the trace amount of ammonia-containing water to the second absorption tower 105 while recirculating to the stripping column 103; In order to increase the ammonia solubility of the trace amount of ammonia-containing water discharged from the concentration tower 107, heat is exchanged between the water discharged from the concentration tower 107 and the ammonia-containing water containing carbon dioxide discharged from the first heat exchanger (102). In the apparatus for continuously producing a high-purity carbon dioxide according to the method of claim 1, including the second heat exchanger 110, the third absorption tower 106 is discharged from the upper of the stripping column 103, steam Condensate combined absorption tower which discharges only carbon dioxide from the mixture of water and ammonia gas, washes the ammonia gas with water, condenses water vapor and re-injects it into the stripping column. And it provides a device for recovering a high purity carbon dioxide, characterized by.

The condensation merging absorption tower of the present invention can increase the contact between the water flowing from the top and the gas flowing from the bottom by filling a filler in a space not occupied by the heat exchanger and the function of the heat exchanger to cut off the flow of heat transferred from the stripping column. The function of the absorption tower has a fused function.

In the present invention, the temperature of the heat medium flowing into the heat exchange pipe of the condensation merger absorption tower is 0 ^o C ~ 30 ^o C and the shape of the heat exchanger for cooling does not limit the present invention.

In addition, in the present invention, the material of the condensation merger absorption tower is preferably iron, aluminum, or stainless steel.

In addition, in the present invention, it is preferable to fill the structure or non-structured fillings in the space inside the tower except for the heat exchange pipe to improve the contact between the water flowing from the top and the gas flowing from the bottom.

The condensation merging absorption tower of the present invention removes the burden of cooling from the water introduced to the top of the tower to absorb ammonia by the heat exchanger as a component, and fills the inside of the tower to maximize the contact between the water and the gas to increase the amount of water introduced. It can be minimized.

<Example>

The diameter of all towers shown in FIG. 1 is 51 mm, the carbon dioxide first absorption tower 101 is 2,000 mm in length, and the inside is filled with a gauze-type structured packing (700 m ² / m ³ ). The length of the stripping column 103, the second absorption tower 105 for removing ammonia that may be contained in the exhaust gas, and the third absorption tower 106 for removing ammonia that may be contained in the product are 500 mm, respectively. to be. The lengths of the carbon dioxide stripping column 103 and the ammonia concentration tower 107 are 1,300 mm and 1,000 mm, respectively. In addition, the insides of these towers were filled with the same material as the first absorbing tower 101. Table 1 shows the operating conditions and results of the device. The concentration of carbon dioxide gas recovered using the above apparatus was 99.9%.

 TABLE 1 Operating Conditions of Example

Condition value Condition value Initial absorbent ammonia concentration (wt%) 13 Simulation flue gas composition 10 vol% CO ₂ / N ₂ Absorbent circulating flow rate (113) (m ³ / m ² * h) 2.95 Supply flue gas (112) Supply flow rate (m ³ / m ² * h) 530 Circulating flow rate of water (m ³ / m ² * h) 0.4 to 1.3 CO ₂ recovery rate (%) 98.4 CO ₂ concentration (vol%) of the upper exhaust gas of the absorption tower 101 0.16 Product (117) CO ₂ Concentration (vol%) 99.9 Ammonia concentration tower reboiler (108) temperature (℃) 90-100 Extraction column first reboiler 104 temperature (° C.) 79.0 to 81.0 Ammonia Absorption Tower (106) Lower Temperature (℃) 35-50 Ammonia Absorption Tower 106 Upper Temperature (° C) 0 to 40 Absorption liquid 115 absorbed carbon dioxide temperature (℃) 35-50 Absorption liquid 113 temperature (° C.) supplied to the upper portion of the carbon dioxide absorption tower 101. 25

As described above, the third absorption tower 106 of the above-described device may be operated by being replaced with the condensation combined absorption tower of the present invention. Temperature distribution and carbon dioxide outlet in stripping column 103 according to the amount of water 120 introduced when using an absorption tower filled with conventional structured packing and when using the condensation merger absorption tower of the present invention The temperature of is shown in <Table 2>. The condensation merger absorption tower was 500mm long, the same length as the existing absorption tower, and the internal pipe was made of 0.25in diameter stainless steel. In addition, the diameter of the inner spiral formed by the piping was 30 mm. The remaining void space was filled with saddle packing (5 mm OD × 10 mm H). Condensation merger Absorbent tower internal piping and external cooling jacket were allowed to circulate 15 ^° C heat medium.

<Table 2> Temperature distribution inside the stripping tower and the temperature of carbon dioxide outlet

Amount of water introduced Conventional Absorption Tower Condensation Merger Absorption Tower Distance from the scrambler (mm) Temperature ( ^oC ) Distance from reboiling (mm) Temperature ( ^oC ) 0.44 m ³ / m ² * h 150 79 150 78 450 77 450 75 1300 70 1300 68 1800 (carbon dioxide outlet) 65 1800 (carbon dioxide outlet) 19 0.88 m ³ / m ² * h 150 79 150 78 450 77 450 75 1300 69 1300 66 1800 (carbon dioxide outlet) 58 1800 (carbon dioxide outlet) 19 1.32 m ³ / m ² * h 150 79 150 78 450 77 450 75 1300 67 1300 65 1800 (carbon dioxide outlet) 54 1800 (carbon dioxide outlet) 19

As shown in Table 2, when the existing absorption tower is used, the temperature of the carbon dioxide outlet varies according to the incoming water. However, it was very difficult to reduce the temperature of the carbon dioxide outlet to below 50 ^o C even with the inflow of water close to half of the volume of circulating ammonia water. It was confirmed that the pressure in the stripping column rose slightly due to the excessive heat transfer from the reboiler, and that the ammonia gas was discharged to the carbon dioxide outlet. On the other hand, in the case of using the condensation combined absorption tower of the present invention, the temperature distribution inside the stripping column was not only constant, but the temperature of the carbon dioxide outlet was maintained at 19 ^° C regardless of the amount of water introduced. There was also little ammonia emission from the carbon dioxide outlet.

The present invention uses ammonia water and water vapor in a mixture of carbon dioxide, water vapor, and ammonia gas discharged from the top of the carbon dioxide stripping tower in a device for separating carbon dioxide from a mixed gas containing carbon dioxide such as combustion flue gas using an aqueous ammonia solution. The present invention relates to an apparatus for effectively separating carbon dioxide from carbon dioxide, injecting it back into a system, and recovering high purity carbon dioxide. In the case of using a conventionally known absorption tower, the amount of water flowing from the top is excessively required due to the amount of heat transferred from the stripping column, so that the concentration of ammonia in the stripping column may be low, and the amount of water to be removed from the concentration tower is high. Excessive calories should be added to the tower reboiler. In addition, when the condenser is used alone, the ammonia gas flows out, and thus high purity carbon dioxide cannot be obtained, and solid salts formed by the gaseous reaction of ammonia gas and carbon dioxide may block the piping. Condensation merging absorption tower of the present invention accommodates only the advantages of both the absorption tower and the condenser can perform cooling by heat exchange and ammonia gas absorption by water at the same time. Therefore, by minimizing the amount of water flowing into the top to wash the ammonia gas to maintain the concentration of ammonia in the stripping column, the amount of water to be removed from the concentration tower is also minimized to reduce the energy for ammonia concentration. Condensation combined absorption tower of the present invention is a device that can save energy by increasing the purity of carbon dioxide recovered in the apparatus for high purity carbon dioxide recovery using ammonia water and reducing the amount of heat required for the stripping tower.

Claims (10)

As a method of producing high purity carbon dioxide from a mixed gas containing carbon dioxide, 5 to 15 wt% aqueous ammonia solution is supplied to the top of the first absorption tower 101 at a temperature of 0 ~ 40 ^° C and the first absorption tower 101 Introduce the mixed gas containing carbon dioxide to the lower portion of the mixed gas to absorb the carbon dioxide contained in the mixed gas into ammonia water and send the absorbing liquid absorbed carbon dioxide to the stripping column 103 and heated to 70 ~ 88 ^o C to remove the carbon dioxide, carbon dioxide While the stripped ammonia water 113 is cooled by the first heat exchanger 102 and recycled back to the first absorption tower 101, the stripped carbon dioxide is sent to the third absorption tower 106 to remove the trace ammonia to obtain high purity carbon dioxide. Produced as a product, absorbs trace amounts of ammonia in the treated flue-gas into the water in the second absorption tower and absorbs trace amounts of ammonia-containing water in the third Ammonia water from the stripping column 103 to the concentration tower 107 is introduced into the upper portion of the 106 and the amount of water circulated to the second absorption tower 105 to remove the trace ammonia in the treated flue gas 114. In the method for sending and removing the ammonia through distillation and discharge through the second reboiler 108 and the discharged water 120 is cooled through heat exchange to recycle again to the top of the second absorption tower 105, The third absorption tower 106 discharges only carbon dioxide from the mixture of carbon dioxide, water vapor, and ammonia gas discharged from the stripping column 103, washes off the ammonia gas with water, and condenses the water vapor to re-inject it into the stripping column. A method for recovering high purity carbon dioxide, characterized in that the condensation merger absorption tower. The method of claim 1, wherein the heat exchanger pipe is installed inside or outside the third absorption tower 106, which is a condensation merger absorption tower, or both inside and outside, to stop the flow of heat transferred from the stripping tower, Filling the filling in the space not occupied by the heat exchange pipe inside the tower to increase the contact between the water flowing from the top and the gas flowing from the bottom. The temperature of the heat medium flowing into the heat exchange pipe of the third absorption tower 106, which is the condensation merger absorption tower, is 0 ^o C to 30 ^o C, and the circulating heat mediums 122 and 123 are connected to the cooling tower 121. By means of continuous cooling. The method according to claim 2 or 3, characterized in that the material of the third absorption tower (106), which is a condensation merger absorption tower, is made of iron, aluminum, or stainless steel. According to claim 1 or 2, the contact between the water flowing from the top and the gas flowing from the bottom by filling the structure or non-structured filling in the space except the heat exchange pipe inside the third absorption tower 106, which is a condensation merge absorption tower Characterized in that for improving the quality. A device for producing high purity carbon dioxide from a mixed gas containing carbon dioxide, the first absorption tower 101 for selectively absorbing carbon dioxide from the exhaust gas using ammonia water, desorption for removing carbon dioxide from carbon dioxide-containing ammonia water absorbed carbon dioxide The tower 103, the third absorption tower 106 for absorbing ammonia gas contained in the stripped carbon dioxide with water, the ammonia that may be contained in the exhaust gas 114 from the top of the first absorption tower with water and Heat exchanger 102 for exchanging heat between the second absorption tower 105 which sends the ammonia containing water to the third absorption tower 106, the carbon dioxide containing ammonia water from the first absorption tower 101 and the recycled ammonia water from the stripping tower. ), Remove the water used to absorb the ammonia gas and increase the concentration of ammonia water. Concentration tower 107 for recycling a small amount of ammonia-containing water to the second absorption tower 105 while concentrating a portion of the ammonia water from the bottom of the tower 103 and recycling it to the stripping tower, and discharged from the concentration tower 107 In order to increase the ammonia solubility of the trace amount of ammonia-containing water, a second heat exchanger 110 exchanging heat between the water discharged from the concentration tower 107 and the ammonia-containing water containing carbon dioxide discharged from the first heat exchanger 102 is provided. In the apparatus for continuously producing high-purity carbon dioxide according to the method of claim 1, The third absorption tower 106 has both a water vapor condensation tower function by heat exchange and an absorption tower function for ammonia washing, and discharges only carbon dioxide from a mixture of carbon dioxide, water vapor, and ammonia gas discharged from the stripping column 103. The gas is washed with water and the water vapor is condensation combined absorption tower for re-injecting the condensation tower 103, characterized in that the high-purity carbon dioxide recovery apparatus. According to claim 6, wherein the heat pipe through which the heat medium circulates is installed on the outside or inside or outside and inside of the third absorption tower 106, which is a condensation merging absorption tower to cut off the flow of heat transferred from the stripping column 103 , Filling the filling in the space not occupied by the heat exchange pipe inside the tower device characterized in that to increase the contact of the water flowing from the top and the gas flowing from the bottom. According to claim 7, wherein the temperature of the heat medium flowing into the heat exchange pipe of the third absorption tower 106, which is the condensation merger absorption tower is 0 ^o C ~ 30 ^o C, the circulating heat medium 122, 123 is the cooling tower 121 Characterized in that it is continuously cooled by. 9. An apparatus according to claim 7 or 8, characterized in that the material of the third absorption tower (106), which is a condensation merger absorption tower, is made of iron, aluminum or stainless steel. The method according to claim 6 or 7, wherein the filling of the structure or non-structural fillings in the space other than the heat exchange pipe inside the third absorption tower, which is the condensation merger absorption tower, improves the contact between the water flowing from the upper portion and the gas flowing from the lower portion. Device characterized in that.

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