JP2005288207A - Flue gas cleaning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flue gas cleaning apparatus capable of removing oil mist in the flue gas without using a fuel and maintaining high oil mist capturing ability over a long period of time. <P>SOLUTION: This flue gas cleaning apparatus is provided with a vapor/liquid contact type air cleaning device 1 for contacting air circulating from a suction port 14 toward an air discharge port 11 with water fed from a water feed port 15 to remove the oil mist in the air; a flue gas duct 2 for guiding the flue gas S containing the oil mist discharged from a flue gas generation source to the suction port 14 part; a suction duct 3 provided with a suction fan 30 and connected to the air discharge port 11; a standing oil/water separation tank 4 for storing water containing oil contents discharged from the air cleaning device 1; a water reflux device 5 for refluxing water taken from a lower part of the oil/water separation tank 4 to the water feed port 15; and a water circulation cleaning device 6 for circulating water in the oil/water separation tank 4 into the oil/water separation tank 4 via a coalescer system oil/water separator 65. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flue gas purifying apparatus that removes and purifies oil mist in flue gas such as a heat treatment furnace.

In a quenching furnace that performs quenching treatment of materials to be treated such as steel materials, a large amount of oil mist (small oil droplets) is generated by immersing high-temperature treated products in a quenching oil tank. Even in the tempering furnace, oil mist and soot (oil smoke) are generated by heating the quenching oil adhering to the article to be treated. And as a device for removing the oil mist in the flue gas of these furnaces, for example, a local exhaust device that collects the oil mist in the flue gas by contact with cooling water that always flows along the inner peripheral surface of the exhaust duct. In addition, there has been proposed an oil smoke processing device that sucks oil smoke generated from a heat treatment material and burns it with a combustion device (see, for example, Patent Documents 1 and 2).
JP-A-5-231632 (page 1-3, FIG. 1) JP 2000-356332 A (page 1-4, FIGS. 1-2)

  However, in the apparatus described in Patent Document 1, the oil mist collected by the cooling water returns to the cooling water tank and is circulated as it is. Therefore, the oil content in the cooling water increases with time, and the oil mist collecting ability is increased. It had the problem of decreasing. Further, the device described in Patent Document 2 requires a fuel for burning smoke in the combustion chamber, which is uneconomical and has a problem that it is necessary to treat the combustion exhaust gas.

  The present invention is intended to solve the above-mentioned conventional problems, and provides a flue gas purifying device capable of removing oil mist in flue gas without using fuel and maintaining high oil mist collecting ability over a long period of time. The purpose is to do.

  In order to achieve the above object, the smoke purification apparatus according to claim 1 removes oil mist in the air by bringing the air flowing from the intake port toward the exhaust port into contact with the water supplied from the water supply port. A gas-liquid contact type air purifying device, a smoke exhaust duct for guiding the exhaust gas containing oil mist discharged from the smoke generation source to the intake port, and an intake air connected to the exhaust port with an intake fan A duct, a static oil / water separation tank for storing water containing oil discharged from the air purification device, a water reflux device for returning water taken from the lower part of the static oil / water separation tank to the water supply port, and And a water circulation purification device that circulates the water in the stationary oil-water separation tank into the stationary oil-water separation tank through a coalescer oil-water separator.

  According to the first aspect of the present invention, the oil mist in the flue gas that is sucked by the intake fan and circulates in the air purification device is collected in the water supplied from the water supply port, and the oil component collected in the water is collected. Is circulated and removed by the water circulation purification device in addition to separation due to the difference in specific gravity in the stationary oil / water separation tank, so that the water recirculated to the water supply port by the water recirculation device has a high oil mist collecting ability. The oil is collected and used for a long period of time.

  In this invention, the intake duct may be provided with only the intake fan. However, as in the second aspect of the invention, a structure in which a dust filter is provided on the front side of the intake fan of the intake duct is used. For example, the dust filter collects the dust remaining in the flue gas discharged from the air purifier, and the dust can be prevented from being released to the outside.

  Moreover, in this invention, it is not necessary to provide a special defoaming device in the stationary oil / water separation tank. However, as in the invention according to claim 3, the stationary oil / water separation tank is disposed above the stationary oil / water separation tank. If a defoaming machine that sucks and defoams bubbles on the liquid level in the tank is provided, bubbles generated along with bubbling in the air purifier section are generated in the stationary oil-water separator. It is possible to prevent the amount of bubbles accumulated on the liquid surface from becoming excessive due to the formation of oil droplets by the defoamer at the upper part of the liquid surface.

  Further, in this invention, the water circulation purification device may connect a coalescer type oil-water separator directly to the water intake through a pipe, but as in the invention according to claim 4, the coalescer of the water circulation purification device. If the oil filter is provided on the upstream side of the system oil / water separator, the oil filter removes sludge, and therefore, the coalescer oil / water separator can be prevented from being clogged with sludge.

  In the present invention, the gas-liquid contact type air purification device is a spray type that sprays water from a nozzle-shaped water supply port and removes oil mist in the air by contact between the droplet-shaped water and the air. An air purifying device or the like may be used, but as the air purifying device according to claim 5, the bottom portion of the box having an exhaust port at the top is constituted by a water retaining plate having a number of ventilation holes. An air formed by providing a water supply port for supplying water on the water retaining plate, and providing a water tray having a drain port on the lower side of the box, and forming an intake port between the water tray and the box. Use of the purification device is preferable because oil mist in the flue gas can be efficiently collected in the water by bubbling in the water retaining plate portion of the air purification device.

  Furthermore, as in the invention according to claim 6, a partition plate in which a lower end edge is immersed in a predetermined amount of water in the side wall of the box of the air purifier so as to partition the inlet and the box. The oil mist in the smoke is first efficiently and reliably collected in the water by the bubbling by the smoke passing through the water in the water tray through the lower end of the partition plate. After that, since it is also collected in the water retaining plate portion, a particularly high oil mist collecting ability is obtained, which is preferable.

  According to this invention, the oil mist in the flue gas can be removed without using fuel, and the water that has collected the oil mist is separated and used by the stationary water storage tank and the water circulation purification device. High oil mist collecting ability is maintained for a long time.

  In addition to the above-described effect, according to the invention described in claim 2, even in the case of flue gas having a high dust content, the release of dust from the intake duct to the outside can be reliably prevented.

  Further, in addition to the above effects, according to the invention of claim 3, it is possible to suppress the amount of bubbles accumulated in the stationary oil-water separation tank from becoming excessive, and troublesome bubble removal work by hand is unnecessary, An easy-to-maintain smoke purification device is obtained.

  In addition to the above effects, according to the invention described in claim 4, it is possible to prevent damage due to clogging of the coalescer of the oil / water separator and decrease in the oil / water separation capacity, and the maintenance work is not required. High oil / water separation capacity can be maintained.

  In addition to the above effect, according to the invention described in claim 5, the oil mist in the flue gas can be efficiently collected in the water by bubbling in the water retention plate portion of the air purification device. According to the invention, since the oil mist in the flue gas can be collected in the water by bubbling in the water receiving tray part in addition to the water retaining plate part, higher oil mist collecting ability can be obtained.

  Hereinafter, an embodiment of the present invention will be described with reference to an example shown in FIGS. FIG. 1 is a block diagram showing the whole of a flue gas purifying apparatus. The flue gas purifying apparatus of the present invention includes an air purifying apparatus 1, a flue gas duct 2, an intake duct 3, a stationary oil / water separation tank 4, and a water circulation. A device 5 and a water circulation purification device 6 are provided. Hereinafter, each of these parts will be described.

  The air purification device 1 is of a type that is also used for exhaust purification of a kitchen. As shown in FIG. 2, the bottom of the box 10 having an exhaust port 11 at the top has a number of ventilation holes 12a. A water retaining plate 12 extending in the horizontal direction is provided, and a water tray 13 is provided below the box 10, and an air inlet 14 extending in the longitudinal direction of the box 10 is provided between the water tray 13 and the box 10. Is formed. A water supply port 15 is provided at the upper part of the box body 10 for supplying water onto the water retention plate 12, and 16 is a wire mesh filter for removing water droplets. The water tray 13 is provided with an overflow drain 17. In this example, a partition plate 18 whose lower end edge is immersed in the water W in the water tray 13 is screwed to the lower portion of the side wall 10a of the box 10 so that the vertical position can be adjusted. Since the end wall 13a of the water receiving tray is in close contact with the end wall of the box body 10, the partition plate 18 partitions the internal space of the box body 10 and the inlet 14 portion in a water-sealed state. .

  Further, as shown in FIG. 1, the smoke exhaust duct 2 purifies the exhaust gas S including the oil mist discharged from the smoke exhaust port 21 of the heat treatment furnace 20 (in this example, the quenching furnace) which is a smoke generation source. The upper end opening 22 is directed upward at the lower positions on both sides of the water tray 13.

  The intake duct 3 is for sucking and exhausting the smoke S from the intake port 14 through the box 10 to the exhaust port 11 and is connected to the exhaust port 11 with an intake fan 30. . In this example, a dust collection chamber 33 provided with dust filters 31 and 32 is provided on the front side of the intake fan 30. The air outlet 30a of the intake fan 30 is opened in the factory building in this example, but may be opened outdoors through a duct or the like. Reference numerals 34 and 35 denote dampers for adjusting the intake air amount. The damper 35 adjusts the amount of dilution air sucked from the opening 35a to adjust the intake air amount from the intake port 14, and is provided as necessary. .

The stationary oil / water separation tank 4 receives and stores water (drainage) containing oil discharged from the water tray 13 through a drain pipe 40 connected to the drain port 17 of the water tray 13, and has a specific gravity of oil and water. Oil water separation is performed by the difference, 42 is a water intake provided in a lower position of the tank body 41 (position corresponding to the separated water W layer), and 43 is an upper position of the tank body 41 (separated oil-mixed water W _This is a water intake provided at a position corresponding to the _0th layer). Reference numeral 44 denotes a water supply pipe provided with a ball tap, which is connected to a water supply source (not shown) and performs automatic water supply so as to maintain the liquid level F in the tank body 41 at a fixed position. Further, in this example, a defoamer 45 is provided at the upper part of the tank body 41 to suck the foam B on the liquid surface F by the rotating impeller 45a and collide with the side surface of the casing to defoam and liquefy.

  Further, the water reflux device 5 includes a pump 51 and a flow rate adjusting valve 52 in a water supply pipe line 50 that connects the water intake port 42 of the stationary oil / water separation tank 4 and the water supply port 15 of the air purification device 1. It is provided.

Further, the water circulation purification device 6 has one end connected to the water intake 43 of the stationary oil / water separation tank 4 and the other end connected to the circulation pipe 60 that opens into the tank body 41 as a reflux port 61, and a pump 62, A flow rate adjusting valve 63, an oil filter 64, and a coalescer oil / water separator 65 are provided. The coalescer oil-water separator 65 has a known configuration in which minute oil droplets captured inside the fiber filter-shaped coalescer 66 are aggregated and coarsened to be separated from the outer surface and separated by specific gravity. The separated oil is discharged from the upper discharge port to a waste oil storage tank 69 through an oil discharge pipe 68 with an on-off valve 67. The oil filter 64 preliminarily removes solid particles such as sludge in the oil-mixed water W ₀ flowing into the oil-water separator 65, depending on the content and content of the oil-mixed water. Used.

  In order to perform the exhaust gas purification process by the exhaust gas purification device having the above-described configuration, the pump 51 of the water recirculation device 5 is operated to supply the water W from the water supply port 15 of the air purification device 1 onto the water retaining plate 12, As shown in FIG. 2, a water film (shallow water layer) V is formed on the water retaining plate 12, and water W having a predetermined depth in which the lower end portion of the partition plate 18 is immersed is stored in the water tray 13. Thus, the intake fan 30 is operated while the supply of the water W from the water supply port 15 at a constant flow rate is continued. Then, due to the suction pressure by the intake fan 30, an atmospheric pressure difference is generated inside and outside the partition plate 18 through the inside of the box body 10, and the water level outside the partition plate 18 of the water W in the water receiving tray 13 is lowered. Since a suction air flow toward the inside of the partition plate is formed from a small gap formed between the lower edge and the smoke exhaust S discharged from the smoke exhaust 21 and guided to the intake 14 through the smoke exhaust duct 2 is 1 is sucked through the gap and causes bubbling to occur in the water W in the water receiving tray 13 as shown by a chain line P in FIG. 1, and oil mist and soot in the flue gas S due to intense contact with the water W Dusts are efficiently and reliably collected in the water W.

  The smoke S that passes through the water W of the water tray 13 and is sucked upward in this way is sucked upward through the vent holes 12a of the water retention plate 12, and is formed on the water retention plate 12 at this time. Dust such as oil mist and soot remaining in the flue gas S due to violent contact with the water W due to bubbling in the water retaining plate 12 part as shown by the chain line Q by passing through the water film V part. The water is efficiently and reliably collected in the water W, and the water droplets are removed by the filter 16 and then exhausted from the exhaust port 11. Even when the exhaust gas contains residual dust, the residual dust is removed by the dust filters 31 and 32 in the dust collection chamber 33 and then discharged as clean air from the air outlet 30a of the intake fan 30. It is.

  The water containing the oil that has collected oil mist and the like by each bubbling flows into the stationary oil / water separation tank 4 from the drain port 17 through the drain pipe 40 and is stored therein. Oil-water separation is carried out. The water W in the lower part of the liquid layer in the tank body 41 is circulated and supplied to the water supply port 15 by the water reflux device 5 and is circulated and used for the purification of the above-described smoke S.

The oil-mixed water W _{0 in the} upper part of the liquid layer in the tank body 41 flows through the circulation pipe 60 of the water circulation purification device 6 by the operation of the pump 62, and after sludge is removed by the oil filter 64, the coalescer In the oil / water separator 65 of the type, the oil is removed by being subjected to a strong oil / water separation action by the coalescer 66, and is returned to the tank body 41. At this time, since the oil filter 64 is provided as a pre-filter at the front stage of the oil / water separator 65, even if the water W ₀ mixed with oil contains sludge, the sludge is removed. It is possible to prevent the sludge from flowing in and causing the coalescer 66 to be damaged and the oil-water separation ability to be reduced due to clogging.

  The water that has collected oil mist and the like in the air purification device 1 as described above is sufficiently removed by oil-water separation due to the specific gravity difference in the stationary oil-water separation tank 4 and oil-water separation by the coalescer 66 in the water circulation purification device 6. The purified water W is returned to the water supply port 15 through the water reflux device 5 and circulated and used for exhaust gas purification, and the oil mist collecting ability of the water W is maintained.

  The water from the water tray 13 is mixed with a large amount of oil that has been bubbled due to the bubbling, and the bubbles B are accumulated in the upper part of the tank body 41. By defoaming the bubbles B to form oil droplets, it is possible to avoid a situation in which the amount of bubbles becomes excessive and a cumbersome manual bubble removal operation is required.

  In the above example, the partition plate 18 whose lower end edge is immersed in the water in the water tray 13 is provided on the side wall 10a of the box 10 of the air purification device 1. However, even if this partition plate 18 is omitted. Good. In this case, the oil mist in the flue gas S is collected in the water only by bubbling with the water on the water retaining plate 12. However, since the flue gas S in the bubbling state is in violent contact with the water W, for example, Compared with the collection by the water which flows along the exhaust duct inner peripheral surface in patent document 1, or the water sprayed by the nozzle to the flue gas flow, much higher oil mist collection capability is obtained.

  The present invention is not limited to the above example. For example, the air purifier 1 adjusts the amount of water supplied from the water inlet 15 or the amount of drainage from the water tray 13 according to the water surface position in the water tray 13. It may be configured other than the above, such as the one that collects oil mist in the flue gas only by bubbling in the water receiving tray portion by the partition plate 18 by omitting the water retaining plate 12, and the above bubbling type Instead of this, another type of air purification device such as a spray type air purification device that sprays water from a nozzle-shaped water supply port and sprays it on the flue gas flow may be used. The dust filters 31, 32, the defoamer 45, the oil filter 64, and the like can be omitted depending on the amount and components of oil mist and dust in the exhaust gas.

1 is an overall configuration diagram of a flue gas purifying apparatus showing an example of an embodiment of the present invention. It is an expansion longitudinal cross-sectional view of the air purification apparatus 1 in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Air purification apparatus, 2 ... Smoke duct, 3 ... Intake duct, 4 ... Static oil-water separation tank, 5 ... Water recirculation apparatus, 6 ... Water circulation purification apparatus, 10 ... Box body, 10a ... Side wall, 11 ... Exhaust port , 12 ... Water retaining plate, 12a ... Vent hole, 13 ... Water tray, 14 ... Intake port, 15 ... Water supply port, 17 ... Drain port, 18 ... Partition plate, 20 ... Heat treatment furnace (smoke generation source), 21 ... Exhaust Smoke, 30 ... intake fan, 31 ... dust filter, 32 ... dust filter, 40 ... drainage pipe, 42 ... water intake, 43 ... water intake, 45 ... defoaming machine, 45a ... impeller, 50 ... water supply line , 51 ... pump, 60 ... circulation line, 61 ... reflux port, 62 ... pump, 64 ... oil filter, 65 ... oil-water separator, 66 ... coalescer.

Claims (6)

A gas-liquid contact type air purifying device that removes oil mist in the air by bringing the air flowing from the intake port toward the exhaust port into contact with the water supplied from the water supply port;
A smoke exhaust duct for guiding the exhaust gas including oil mist discharged from the exhaust gas generation source to the intake port, and
An intake duct with an intake fan connected to the exhaust port;
A stationary oil-water separation tank for storing water containing oil discharged from the air purification device;
A water recirculation device for recirculating water taken from the lower part of the stationary oil / water separation tank to the water supply port;
A flue-gas purification device, comprising: a water circulation purification device that circulates water in the stationary oil-water separation tank into the stationary oil-water separation tank through a coalescer oil-water separator.   The exhaust gas purification apparatus according to claim 1, wherein a dust filter is provided on a front side of the intake fan of the intake duct.   The defoaming machine which sucks and defoams the foam on the liquid level in the stationary oil-water separation tank by a rotating impeller is provided at the upper part of the stationary oil-water separation tank. The smoke emission purification device described.   The exhaust gas purification device according to claim 1, wherein an oil filter is provided on the upstream side of the coalescer type oil-water separator of the water circulation purification device.   The air purifier comprises a water retaining plate having a plurality of ventilation holes at the bottom of a box having an exhaust port at the top, a water receiving tray having a water supply port for supplying water on the water retaining plate and having a drain port The exhaust gas purification device according to claim 1, 2, 3, or 4, wherein an air inlet is formed between the water tray and the box.   6. A partition plate having a lower end edge immersed in a predetermined amount of water in the water receiving tray and partitioning the intake port and the box body is provided on a side wall portion of the box body of the air purification device. The smoke emission purification device described.

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