WO2004071625A1

WO2004071625A1 - Collection apparatus for volatile organic compounds

Info

Publication number: WO2004071625A1
Application number: PCT/KR2003/002768
Authority: WO
Inventors: Kyeong-Soo Lee
Original assignee: Kyeong-Soo Lee
Priority date: 2003-02-13
Filing date: 2003-12-18
Publication date: 2004-08-26
Also published as: KR100387947B1; AU2003286963A1

Abstract

The present invention relates to an apparatus for recovering volatile organic compounds (VOCs) capable of recovering the VOCs contained in the exhaust gas at high efficiency. The inventive apparatus comprises: a first condensation unit, which reduces the temperature and flow velocity of the introduced VOC-containing gas are reduced so that the VOC-containing gas is condensed by the bonding force between the VOCs; a second condensation unit which condenses the remaining VOCs passed through the first condensation unit; a third condensation unit, which increases the temperature of the VOC-containing gas passed the second condensation unit above the condensation temperature of the VOCs, and cools the heated VOC-containing gas below the condensation temperature of the VOCs, so that the remaining VOCs are condensed; and an oil and water separator into which the condensed VOCs are introduced so that they are separated into water and organic compounds and the organic compounds are recovered.

Description

COLLECTION APPARATUS FOR VOLATILE ORGANIC COMPOUNDS

Technical Field

The present invention relates to an apparatus for recovering volatile organic compounds, and more particularly to an apparatus for recovering volatile organic compounds, which continuously changes the density and temperature of a volatile organic compound-containing gas contained in exhaust gas are continuously changed such that the volatile organic compounds contained in the exhaust gas can be recovered at high efficiency.

Background Art

Exhaust gas from a dryer in a laundry, etc., contains environmental contamination factors, such as volatile organic compounds . The volatile organic compounds (VOCs) are substances containing hydrocarbons (C_xH_y) and having physical properties, such as a vapor pressure higher than 0.02 psi in the atmosphere and a boiling point lower than 100 °C, and easily evaporated into the atmosphere. The volatile organic compounds are abundantly contained in solvents used in coating, printing and washing facilities, and the organic synthesis and petroleum refining industries. Other examples of the volatile organic compounds include aromatic compounds, such as benzene, toluene and xylene, which are contained in the exhaust gas from automobiles. Also, other examples of the volatile organic compounds include organic substances frequently used in our daily life, such as paraffin as a raw material of candles, and low-boiling point fuels such as butane and propane. Such volatile organic compounds become causes of global environmental destructions, such as tropospheric ozone contamination, stratospheric ozone layer destruction and global warming. Particularly, there is a report showing that the tropospheric ozone contamination is a cause of acid rain having a great effect on forest damage.

Currently, the number of countries adopting the reduction of volatile organic compounds as a main policy for atmospheric management shows a tendency to increase. In Korea, regulations related to the volatile organic compounds are also established to tighten regulations on the use of the volatile organic compounds .

However, to remove volatile organic compounds which are mainly generated in washing facilities, only a filter type air cleaner is used, so that the volatile organic compounds cannot be recovered and an additional burden to treat the contaminated filter is required.

Meanwhile, a water-cooled, closed apparatus for recovering the volatile organic compounds is proposed but has problems in that it is expensive, has a complex structure, is difficult to manage, and has low recovery efficiency for the volatile organic compounds .

Disclosure of Invention

Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide an apparatus for recovering volatile organic compounds, which has high recovery efficiency for the volatile organic compounds.

Another object of the present invention is to provide an apparatus for recovering volatile organic compound, which changes the density and temperature of a gas containing the volatile organic compounds, such that the condensation of the ^• volatile organic compounds can be smoothly achieved.

Other objects of the present invention will be more clearly understood from the following description of an embodiment of the present invention.

To achieve the above objects, the present invention provides an apparatus for recovering volatile organic compounds

(VOCs) , which is connected to a system from which a volatile organic compound (VOC) -containing gas is exhausted, the volatile organic compound recovery apparatus including: a first condensation unit in which a first cooler for reducing the temperature of the VOC-containing gas is placed at an inlet for the VOC-containing gas, and a blocking net for reducing the flow velocity of the VOC-containing gas is placed below and apart from the first cooler, such that the VOC-containing gas is condensed between first cooler and the blocking net by the bonding force between the VOCs; a second condensation unit for condensing the remaining VOC-containing gas passed through the first condensation unit, the second condensation unit being placed below the first condensation unit and including a second cooler for cooling the VOC-containing gas below the condensation temperature of the VOCs; a third condensation unit for condensing the remaining VOC-containing gas passed through the second condensation unit, the third condensation unit being located below the second condensation unit and including an evaporator for increasing the temperature of the remaining VOC- containing gas above the condensation temperature of the VOCs, and a third cooler placed below the evaporator and serving to cool the remaining VOC-containing gas passed through the evaporator below the condensation temperature of the VOCs; and an oil and water separator into which the condensed VOCs passed through the second and third condensation units are introduced so that water and organic compounds contained in the condensed VOCs are separated and the organic compounds are recovered.

Preferably, the volatile organic compound recovery apparatus of the present invention additionally includes an air passage below the third condensation unit, the air passage including a plurality of friction plates by which the flow of the remaining air passed through the third condensation unit is bent. Preferably, the volatile organic compound recovery apparatus of the present invention additionally includes a filter unit below the third condensation unit, the filter unit serving to adsorb the VOCs contained in the remaining air when the condensed VOCs together with the remaining air are passed through the filter unit.

Preferably, the volatile organic compound recovery apparatus includes organic compound recovery units below the second and third condensation units, respectively. Each of the organic compound recovery units is of a J-shaped form whose one upper end is fed with the VOCs condensed in the second and third condensation units and the remaining VOC-containing gas, whose lower middle portion is provided with a discharge port for introducing the condensed VOCs into the oil and water separator, and whose other upper end discharges the remaining VOC- containing gas.

Brief Description of Drawings

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 is a perspective view showing the shape of a volatile organic compound recovery apparatus according to the present invention;

FIG. 2 is a block diagram showing the construction of a volatile organic compound recovery apparatus according to the present invention;

FIG. 3 is a perspective view showing the inside of a volatile organic compound recovery apparatus according to one embodiment of the present invention; FIG. 4 is a drawing showing the installed state of an organic compound recovery unit according to one embodiment of the present invention; and

FIG. 5 is a drawing showing the flow of the remaining air in an air passage according to one embodiment of the present invention.

Best Mode for Carrying Out the Invention

FIG. 1 is a perspective view showing the shape of a volatile organic compound recovery apparatus according to the present invention. Referring to FIG. 1, a volatile organic compound recovery apparatus 1 may have the shape of a single device, and is connected to the outlet of a volatile organic compound exhaust system 100 (e.g., a evaporation dryer in a laundry) by a pipe 5 such that clean air from which volatile organic compounds were removed is exhausted through an air outlet 4. Meanwhile, an exhaust damper 2 may be disposed at the inlet of the volatile organic compound recovery apparatus according to the present invention such that only a volatile organic compound-containing gas can be introduced into the apparatus .

FIG. 2 is a block diagram showing the construction of the volatile organic compound recovery apparatus according to the present invention. Referring to FIG. 2, in the apparatus for recovering the volatile organic compounds (hereinafter, referred to as VOCs) , the following units are successively disposed in the vertical direction: a first condensation unit 10 which reduces the temperature and flow velocity of the volatile organic compound (VOC) -containing gas introduced from the evaporation dryer so that the VOCs are condensed by the bonding force between them; a second condensation unit 20 which cools the remaining VOCs below the condensation temperature of the VOCs to condense the remaining VOCs; a third condensation unit 30 which heats the remaining VOC-containing gas passed through the second condensation unit above the condensation temperature of the VOCs and then cools the VOC-containing gas below the condensation temperature of the VOCs, thereby condensing the remaining VOCs; and a oil and water separator 60 in which water and organic compounds contained in the VOCs condensed in the second and third condensation units 20 and 30 are separated and recovered. Meanwhile, in the second condensation unit 20 and the third condensation unit 30, first and second organic compound recovery units 24 and 42 for introducing the condensed VOCs into the oil and water separator 60 are placed. Also, a filter unit 40 is placed which finally adsorbs and removes the VOCs from the remaining VOC-containing gas passed through the third condensation unit 30.

FIG. 3 is a perspective view showing the inside of a volatile organic compound recovery apparatus according to one embodiment of the present invention. Referring to FIG. 3, the first condensation unit 10 is connected to the volatile organic compound exhaust system 100, such as an evaporation dryer, such that the VOC-containing gas is introduced into the first condensation unit 10. In the inlet 13 of the first condensation unit 10, a first cooler 11 serving to reduce the temperature of the VOC-containing gas is placed, and below the first cooler 11, a blocking net 12 serving to reduce the flow velocity of the VOC-containing gas is placed in such a manner as to be spaced from the first cooler 11. In this case, the first cooler 11 is preferably formed of a circular cooling coil capable of performing heat exchange without influencing the flow velocity of the VOC-containing gas, and the blocking net is preferably formed of a metal yarn having resistance to the VOCs, such as stainless steel.

Thus, the VOC-containing gas introduced into the first condensation unit 10 is cooled by passing it through the first cooler 11 disposed at the inlet 13, and reflected by the blocking net 12 to form a turbulent flow moving toward the inlet 13, thereby mixing the VOC-containing gas. As a result, the VOC- containing gas is present between the first cooler and the blocking net at high density, and condensed by the bonding force between the VOCs . In the second condensation unit 20, a second cooler 21 is disposed adjacent to the lower portion of the first condensation unit 10, and in the lower portion of the second cooler 21, a first discharge port 23 is formed through which the condensed VOCs and the remaining non-condensed VOC-containing gas are passed. The second cooler 21 is fed with a lower temperature coolant to cool the VOCs below their condensation temperature, and condenses the VOCs contained in the remaining VOC-containing gas passed through the first condensation unit 10. For example, if the VOCs are solvents used in a laundry, they will have a condensation temperature of 4 °C and thus a coolant lower than this condensation temperature will be fed. Meanwhile, the lower portion of the second cooler 20 is completely sealed with a δ gasket 22 such that the condensed VOCs and the remaining non- condensed VOC-containing gas are passed only through the first outlet 23.

FIG. 4 is a drawing showing the installed state of the organic compound recovery unit according to one embodiment of the present invention. Referring to FIG. 4, a first organic compound recovery unit with a J-shaped form is disposed below the second condensation unit 20. One upper end of the first organic recovery unit 24 extends to the first outlet 23 formed in the lower portion of the second condensation unit 20, a discharge port 25 for introducing the condensed VOCs into the oil and water separator 60 is formed in the middle of the lower portion of the first organic compound recovery unit, and an opening 26 for exhausting the remaining VOC-containing gas to a location adjacent to the lower portion of the second cooler 21 is formed in the other upper end of the first organic compound recovery unit 24.

Thus, the VOCs condensed in the second condensation unit 20 together with the remaining VOC-containing gas are introduced into the first organic compound recovery unit 24, and the condensed organic compounds is introduced into the oil and water separator 60 by the discharge port 25 formed in the middle of the lower portion of the first organic compound recovery unit 24. Then, the remaining non-condensed VOC-containing gas is discharged downward. At this time, if the opening 26 is formed adjacent to the second condensation unit 20, the remaining cooled VOC-containing gas passed through the opening 26 will indirectly cool the lower portion of the second cooler 21 to increase the cooling efficiency of the second cooler 21. The third condensation unit 30 is placed below the second condensation unit 20 and fed with the remaining VOC-containing gas discharged from the opening 26 of the first organic compound recovery unit 24. In the third condensation unit 30, the following units are successively disposed in the vertical direction: an evaporator 31 for heating the remaining VOC- containing gas above the condensation temperature of the VOCs; a third cooler 32 for cooling the remaining VOC-containing gas below the condensation temperature of the VOCs; and a second discharge port 33 through which the condensed VOCs and the remaining air are passed.

Furthermore, the second discharge port 33 is provided with a second organic compound recovery unit 42, which can have a J- shaped form likewise to the first organic compound recovery unit 24 formed below the second condensation unit 20.

Thus, the remaining low-temperature VOC-containing gas introduced into the third condensation unit 30 is passed through the evaporator 31 so that it is heated above the condensation temperature of the VOCs. Then, it is passed through the third cooler 32 so that it is cooled below the condensation temperature of the VOCs to cool the VOCs contained in the gas . For example, in the case of solvents, the evaporator allows the temperature of the VOC-containing gas to be increased by about 50 °C, and the third cooler cools it below the condensation temperature of the VOCs .

Moreover, the oil and water separator 60 is placed in such a manner that the condensed VOCs passed through the second condensation unit 20 and the third condensation unit 30 can be introduced into the separator 60 and separated into water and VOC, and the VOCs can be finally recovered.

However, the filter units 40 and 53 are disposed either between the third cooler 32 and the second discharge port 33, or within the air passage before exhausting the remaining air to the external environment. In this case, the filter unit 40 placed below the third condensation unit 30 is a sponge-like filter, and the condensed VOCs together with the remaining air are passed through the filter unit 40 while the VOCs contained in the remaining air are adsorbed onto the filter unit 40. The condensed VOCs are introduced into the oil and water separator 60 through the second organic compound recovery unit 42. As the filter 41 placed within the air passage, an active carbon fiber filter, etc., is detachably mounted, and the remaining air is passed through the filter unit while the VOCs contained in the remaining air are removed by adsorption onto the filter. FIG. 5 is a drawing showing the flow of the remaining air in the air passage according to one embodiment of the present invention. As shown in FIG. 5, the air passage 50 is formed below the third condensation unit 30 in such a manner that the remaining air passed through the second organic compound recovery unit 42 is exhausted through the exhaust outlet 4. Within the air passage 50, pluralities of friction plates 51 are formed such that the flow of the remaining air being exhausted is bent. In the lower portion of the air passage 50, a third discharge port 52 for the introduction into the oil and water separator 60 is formed. If the friction plates 51 are formed in the air passage as described above, the VOCs contained in the remaining air can be condensed with pressure generated by the collision of the remaining air against the friction plates 51. The condensed VOCs are introduced into the oil and water separator 60 through the third discharge port 52.

A coolant used in the volatile organic compound recovery apparatus 1 of the present invention is heat-exchanged with circulation through a compressor 70, an evaporator 31, an expander 80 and the first, second and third coolers 11, 21 and 32. Namely, the coolant which was compressed in the compressor 70 at high temperature is introduced into the evaporator 31 through a conduit 71 and heat-exchanged with the VOC-containing gas in the evaporator 31. The coolant which was heat-exchanged in the evaporator 31 is introduced into the expander 80 through a conduit 81 and cooled to low temperature. Then, it is passed through a conduit 82 to the first, second and third coolers 11, 21 and 31 in which it is heat-exchanged with the VOC-containing gas. Then, it is introduced again into the compressor 70 by the conduit 72.

Moreover, the first, second and third coolers 11, 21 and 32 are either coated in such a manner as to have resistance to the VOCs, or formed of a metal having resistance to the VOCs.

Hereinafter, the operation of the volatile organic compound recovery apparatus according to the present invention will be described.

As shown in FIG. 1, the volatile organic compound recovery apparatus 1 of the present invention is first connected to the VOC-containing gas exhaust system 100, such as an evaporation dryer of the laundry, by the pipe 5. Meanwhile, the volatile organic compound recovery apparatus according to the present invention can be formed to a size corresponding to the gas exhaust system.

As shown in FIGS. 2 and 3, when the gas exhaust system 100 is operated to exhaust a VOC-containing gas, the VOC-containing gas is introduced into the inlet 13 of the first condensation unit through the pipe 5 and at the same time, heat-exchanged with the first cooler 11 so that its temperature is lowered. Then, it is reflected by the dense blocking net 12 placed below and apart from the first cooler 11, so that a turbulent flow moving toward the first cooler 11 is formed and the VOC- containing gas introduced into the first condensation unit 10 is present at high density. Thus, the VOCs present at high density are condensed by the bonding force between them and discharged downward through the blocking net 12. The condensed VOCs and the remaining non-condensed VOC- containing gas, which were passed through the metal net 12 of the first condensation unit, are introduced into the second cooler 21 of the second condensation unit, which is fed with a coolant lower than the condensation temperature of the VOCs . The VOCs condensed in the second cooler 21 are passed in a condensed state, and the VOCs present in the remaining VOC-containing gas are condensed by heat exchange and introduced into the first discharge port 23. Then, the condensed VOCs and the remaining VOC-containing gas are passed through the first organic compound recovery unit 24 having a J-shaped form, which extends to the first outlet 23 of the first condensation unit. At this time, the condensed organic compounds are introduced into the oil and water separator 60 through the discharge port 25 formed in the middle of the lower portion of the organic compound recovery unit, while the remaining non-condensed VOC-containing gas is discharged downward through the opening 26.

Since the VOCs introduced from the second condensation unit 20 into the third condensation unit 30 were not completely recovered, the remaining VOCs need to be recovered so as to exhaust a clean gas. However, since the VOC-containing gas passed through is lower than the condensation temperature of the VOCs and is in the form of a mixture with gas, its condensation efficiency will be reduced.

Thus, the remaining VOC-containing gas introduced into the third condensation unit 30 is passed through the evaporator so that its temperature is increased above the condensation temperature of the VOCs. At this time, a coolant fed into the evaporator 31 has high temperature by compression in the compressor 70.

The VOC-containing gas whose temperature was increased by passage through the evaporator 31 as described above is introduced into the third cooler 32 which is fed with a coolant lower than the condensation temperature of the VOCs . In the third cooler 32, the VOCs present in the remaining ^' VOC- containing gas are condensed by heat exchange with the coolant. At this time, the coolant, which is fed into the third cooler 32, is heat-exchanged with the VOC-containing gas in the evaporator 31, expanded by the expander 80 at low temperature in a cooled state, and then fed into the third cooler 32. Thus, energy can be efficiently used.

The VOCs condensed in the third cooler 32 of the third condensation unit, and the remaining VOC-containing gas, are passed through the filter unit 40 so that the organic compounds contained in the remaining VOC-containing gas are condensed. The condensed VOCs passed through the filter unit, and the remaining air, are introduced into the second organic compound recovery unit 42 connected to the second discharge port 33.

The second organic compound recovery unit 42 may be formed of a J-shaped pipe. In this case, the condensed organic compounds are introduced into the oil and water separator 60 through the discharge port 41 formed in the middle of the lower portion of the organic compound recovery unit 42, and the remaining air is discharged downward through the opening 43.

The remaining air passed through the second organic compound recovery unit 42 is passed through the air passage 50 in which a plurality of the friction plates 51 making the air flow bent are formed. The airflow passed through the air passage is exhausted into the atmosphere. At this time, the VOCs contained in the remaining air are finally condensed by pressure generated by the collision of the airflow against the friction plates 51, and the condensed VOCs are introduced into the oil and water separator 60 through the third discharge port 52. Meanwhile, in the oil and water separator 60, the VOCs recovered through the first and second organic compound recovery units 23 and 33 and the third discharge port 52 are separated into water and organic compounds, and only the organic compounds are finally recovered.

Industrial Applicability

As described above, the inventive apparatus for recovering the volatile organic compounds is advantageous in that it has high recovery efficiency such that most of the volatile organic compounds contained in exhaust gas can be recovered while only clean air is exhausted, thereby preventing the environmental pollution caused by the volatile organic compounds, Another advantage is that the volatile organic compounds can be recovered and recycled regardless of their kinds by changing the temperature of a volatile organic compound- containing gas according to its kind.

Furthermore, if a detachable filter is additionally mounted at an inlet through which air is introduced into the inventive apparatus, there will be an advantage in that the contamination with the volatile organic compounds can be further reduced.

In addition, since the inventive apparatus can be used in a substitute for an air conditioner in the summer season, it allows energy saving.

While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.

Claims

What Is Claimed Is:

1. An apparatus for recovering volatile organic compounds (VOCs) , which is connected to a system from which a volatile organic compound (VOC) -containing gas is exhausted, the volatile organic compound recovery apparatus comprising: a first condensation unit in which a first cooler for reducing the temperature of the VOC-containing gas is placed at an inlet for the VOC-containing gas, and a blocking net for reducing the flow velocity of the VOC-containing gas is placed below and apart from the first cooler, such that the VOC- containing gas is condensed between first cooler and the blocking net by the bonding force between the VOCs; a second condensation unit for condensing the remaining VOC-containing gas passed through the first condensation unit, the second condensation unit being placed below the first condensation unit and including a second cooler for cooling the VOC-containing gas below the condensation temperature of the VOCs; a third condensation unit for condensing the remaining VOC- containing gas passed through the second condensation unit, the third condensation unit being located below the second condensation unit and including an evaporator for increasing the temperature of the remaining VOC-containing gas above the condensation temperature of the VOCs, and a third cooler placed below the evaporator and serving to cool the remaining VOC- containing gas passed through the evaporator below the condensation temperature of the VOCs; and an oil and water separator into which the condensed VOCs passed through the second and third condensation units are introduced so that water and organic compounds contained in the condensed VOCs are separated and the organic compounds are recovered.

2. The apparatus of Claim 1, which additionally includes a filter unit below the third condensation unit, the filter unit serving to adsorb the VOCs contained in the remaining air when the condensed VOCs and the remaining air are passed through the filter unit.

3. The apparatus of Claim 1, which additionally includes an air passage below the third condensation unit, the air passage including a plurality of friction plates by which the flow of the remaining air passed through the third condensation unit is bent.

4. The apparatus of Claim 3, wherein the air passage includes a detachable filter.

5. The apparatus of Claim 1, wherein organic compound recovery units for feeding the condensed VOCs to the oil and water separator are placed below the second and third condensation units, respectively.

6. The apparatus of Claim 5, wherein each of the organic compound recovery units is of a J-shaped form whose one upper end is fed with the VOCs condensed in the second and third condensation units and the remaining VOC-containing gas, whose lower middle portion is provided with a discharge port for introducing the condensed VOCs into the oil and water separator, and whose other upper end discharges the remaining VOC- containing gas.

7. The apparatus of Claim 1, wherein the first cooler is a cooling coil.

8. The apparatus of Claim 1, wherein the second and third coolers are radiators which are cooled by heat exchange with the VOC-containing gas.

9. The apparatus of Claim 1, wherein the first, second and third coolers are either coated in such a manner as to have resistance to the VOCs, or made of a metal having resistance to the VOCs.

10. The apparatus of Claim 1, wherein the blocking net is a metal net formed of a metal yarn having resistance to the VOCs.

11. The apparatus of Claim 1, wherein a coolant, which is used in the first, second and third coolers and the evaporator, is compressed in a compressor at high temperature, fed into the evaporator, heat-exchanged in the evaporator, fed into an expander, heat-exchanged in the expander at low temperature, fed into the first, second and third coolers in a low-temperature state, and heat-exchanged in each of the coolers, and then circulated again to the compressor.