JP2014057935A - Exhaust purification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust purification method which removes a solvent contained in an exhaust atmosphere gas and purifies the exhaust atmosphere gas without cooling the exhaust atmosphere gas, which is exhausted from a heat treatment device and contains the solvent evaporated by heating, in an exhaust process.SOLUTION: In an exhaust purification method, liquid particles 11 generated by a liquid particle supply device 3 are supplied to an exhaust atmosphere gas exhausted by an exhaust duct 2. The liquid particles approach, contact, and cohere with a solvent 10 evaporated in the exhaust atmosphere gas in a mixing part 4. The liquid particles capture the solvent thereinto by repeating the above-mentioned process and the particles and the solvent are removed by a centrifugal separator 5 to purify the exhaust atmosphere gas.

Description

  The present invention removes the solvent from the exhaust atmosphere gas on the path for discharging the atmosphere gas containing the solvent vaporized in the heat treatment apparatus when the material containing the solvent vaporized by heating is heat-treated. The present invention relates to an exhaust purification method for purifying exhaust atmosphere gas.

  In recent years, in the manufacturing process of various industrial products or home appliances, or in the manufacturing process of various electronic components, various batteries, or substrates that are components of those products, pastes having various functions The material is applied, and heat treatment is performed by various heat treatment apparatuses. Examples of various heat treatment apparatuses include a drying furnace, a firing furnace, a curing furnace, a reflow furnace used for soldering in an electronic component mounting process, and the like. In addition to the solids and the like that are ultimately required for the product, each paste-like material has its respective purpose, such as water or an organic solvent, in order to apply them to various substrates or substrates. Various solvents are mixed as necessary, and viscosity adjustment or performance adjustment is performed.

  These solvents are released from the material on the paste into the apparatus through vaporization and removal processes in the heating process in the heat treatment apparatus. As a result, when the heat treatment is continuously performed, the solvent is continuously vaporized and released in the apparatus, and as a result, the solvent concentration in the atmospheric gas in the apparatus may increase, leading to various problems. is there. For example, as the solvent concentration in the atmospheric gas in the apparatus increases, drying becomes difficult because the amount of solvent that can exist in the atmospheric gas at the apparatus temperature approaches a saturated state, or the solvent has explosive properties. In this case, even if the saturated vapor pressure is not reached, the explosion limit of the vaporized solvent concentration may be exceeded. Therefore, when external air is supplied from the outside of the apparatus regularly or continuously, or when nitrogen gas or other atmospheric gases are required, these atmospheric gases are supplied from outside the apparatus, and at the same time, the solvent A means for releasing the atmospheric gas in the apparatus whose concentration has increased to the outside of the apparatus is adopted.

  FIG. 7 is a diagram for explaining the supply and exhaust of the atmospheric gas. Outside air is supplied into the heat treatment apparatus 101 by the blower 119. A part of the atmospheric gas in the apparatus containing the solvent vaporized in the heat treatment apparatus 101 is discharged out of the apparatus by the exhaust blower 107. However, some of the solvents contained in the atmospheric gas exhausted outside the apparatus are harmful, and there are also concerns about the impact on the environment. Therefore, the solvent is removed from the exhaust atmosphere gas as necessary in order to exclude environmental influences such as air pollution caused by the solvent contained in the exhaust atmosphere gas discharged outside the apparatus or health effects on workers. As a method, for example, the method of Patent Document 1 is known.

  FIG. 8 is an explanatory diagram of Patent Document 1. In FIG. In Patent Document 1, an exhaust atmosphere gas containing a solvent exhausted from the inside of the heat treatment apparatus 101 is cooled by a cooler 21 arranged in communication with the in-apparatus exhaust duct 20. With this configuration, the solvent in the atmospheric gas inside the apparatus is liquefied and aggregated, and is captured by the mist collector 23 arranged to communicate further downstream with the exhaust duct 22 outside the apparatus. By doing in this way, exhaust atmosphere gas can be purified and the purified atmosphere gas can be discharged out of the apparatus.

JP 2004-301373 A

  However, in the configuration of Patent Document 1, the solvent in the exhaust gas is cooled by a cooler to liquefy and agglomerate the solvent. Therefore, enormous energy used to heat the atmosphere gas in the heat treatment apparatus to a high temperature. In the cooling process in the cooler, there is a problem that energy for cooling the cooler itself is consumed.

  In view of such a point, the present invention removes the solvent contained in the exhaust atmosphere gas without cooling the exhaust atmosphere gas containing the solvent vaporized by heating discharged from the heat treatment apparatus in the course of exhaust, and exhausts the exhaust gas. An object of the present invention is to provide an exhaust purification method for purifying atmospheric gas.

  In order to achieve the above object, the present invention is configured as follows.

An exhaust purification method according to one aspect of the present invention includes a heat treatment apparatus, wherein a solvent is vaporized by heating a material containing a solvent, and the exhaust atmosphere gas containing the vaporized solvent and exhausted from the heat treatment apparatus is purified. A way to
Exhaust gas containing the vaporized solvent is exhausted out of the heat treatment apparatus by an exhaust duct communicating with the heat treatment apparatus,
In the mixing section connected to the exhaust duct, the exhaust atmosphere gas discharged from the heat treatment device through the exhaust duct, and the liquid particles supplied from the liquid particle supply device and heated to the exhaust atmosphere gas temperature or higher To form a mixed atmosphere gas,
From the centrifugal separator, the mixed atmospheric gas in which the exhaust atmospheric gas and the liquid particles are mixed is centrifuged by a centrifugal separator, and the liquid particles adsorbing the solvent from the exhaust atmospheric gas are centrifuged. The solvent and the liquid particles are removed from the exhaust gas exhausted and purified.

  As described above, according to the exhaust purification method of the present invention, even when removing the vaporized solvent contained in the exhaust atmosphere gas discharged from the heat treatment apparatus that performs heating, the exhaust atmosphere gas is purified without cooling. It is possible to exhaust the atmospheric gas out of the heat treatment apparatus or to circulate it in the heat treatment apparatus.

Explanatory drawing of the exhaust gas purification method in 1st Embodiment of this invention. Explanatory drawing of the process of aggregation of the exhaust gas purification method in 1st Embodiment of this invention Explanatory drawing of the process of aggregation by the charge of the exhaust gas purification method in 1st Embodiment of this invention State explanatory drawing of the mixing part of the exhaust gas purification method in the first embodiment State explanatory drawing of the mixing part of the exhaust gas purification method in the first embodiment Explanatory drawing of the exhaust gas purification method in 2nd Embodiment of this invention. Explanatory drawing showing conventional supply and exhaust Explanatory drawing of a conventional exhaust purification device

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is an explanatory diagram of an exhaust gas purification apparatus that performs an exhaust gas purification method according to a first embodiment of the present invention.

  The exhaust purification device 40 includes an exhaust duct 2, a liquid particle supply device 3, a mixing unit 4, and a centrifugal separator 5. One end of the exhaust duct 2 communicates with the heat treatment apparatus 1 and the other end communicates with the mixing unit 4. The liquid particle supply device 3 is disposed in communication with one end of the mixing unit 4. The centrifugal separator 5 is disposed in communication with the other end of the mixing unit 4. An exhaust blower 7 may be disposed on the downstream side of the centrifugal separator 5.

  The heat treatment apparatus 1 is a furnace that performs heat treatment, such as a firing furnace, a drying furnace, a curing furnace, or a reflow furnace. The heat treatment apparatus 1 performs heating according to various materials or members to be heated, and the solvent evaporates in the atmosphere gas (atmosphere gas) in the heat treatment apparatus by the heating. A part of the atmospheric gas in the apparatus including the evaporated solvent is guided to the mixing unit 4 through the exhaust duct 2.

  Here, the liquid particle supply device 3 is disposed on a route different from the route of the exhaust duct 2. With this liquid particle supply device 3, a high-temperature atmospheric gas containing liquid particles heated to a temperature equal to or higher than the temperature of the exhausted atmospheric gas (exhaust atmospheric gas) is supplied into the mixing unit 4. When supplying high-temperature atmospheric gas containing liquid particles from the liquid particle supply device 3, the gas may be supplied not only to the mixing unit 4 but also into the exhaust duct 2 close to the mixing unit 4. In the liquid particle supply device 3, by heating the liquid particles to the exhaust gas temperature or higher, when the liquid particles are supplied to the exhaust gas and mixed, the liquid particles are evaporated or vaporized depending on the temperature of the gas. Can be prevented as much as possible.

  At this time, when the partial pressure of the water of the exhaust atmosphere gas discharged from the heat treatment apparatus 1 does not reach the saturated vapor pressure, some of the supplied high-temperature liquid particles are evaporated or vaporized. As a result, after the exhaust atmosphere gas and the mixed atmosphere gas of liquid particles reach the saturated vapor pressure of water, the liquid particles in the mixed gas exist in the atmosphere gas in a liquid state. In the mixing unit 4, a turbulent flow is provided to supply the high-temperature atmospheric gas containing liquid particles in a stream line substantially perpendicular to the flow line of the exhaust atmospheric gas. Is stirred. By stirring in the mixing unit 4, the solvent and the liquid particles contained in the exhaust atmosphere gas repeat approach, contact, and aggregation with each other.

  A centrifugal separator 5 typified by a cyclone system, for example, communicates with the downstream side of the mixing unit 4. By sending the exhaust atmosphere gas into the centrifugal separator 5, the liquid particles that have adsorbed and aggregated the solvent in the exhaust atmosphere gas are centrifuged from the exhaust atmosphere gas, removed, recovered, and discharged from the drain 6. . The exhaust atmosphere gas purified by removing the solvent is discharged to the exhaust blower 7 communicating with the downstream, and is discharged outside the apparatus by the exhaust blower 7.

  FIG. 2 is a diagram illustrating a process of aggregation of the solvent 10 and the liquid particles 11 or the liquid particles 11 in the exhaust atmosphere gas. FIG. 2A shows the state of the solvent 10 that is evaporated or vaporized in the exhaust atmosphere gas in the exhaust duct 3. FIG. 2B shows the state of the liquid particles 11 supplied from the liquid particle supply device 2 to the exhaust atmosphere gas and heated to a temperature equal to or higher than the exhaust atmosphere gas temperature. (C) of FIG. 2 is the liquid of (b) in the mixing part 4 after supplying the liquid particle 11 of (b) in the exhaust atmosphere gas of (a), or in the exhaust atmosphere gas of (a). A process in which the solvent 10 and the liquid particles 11 approach, contact, and agglomerate by the van der Waals force 12 in the mixing unit 4 that supplies the particles 11 is shown. FIG. 2D shows a state of the liquid particle 11A in which the mass is gradually increased by repeating this aggregation in the mixing unit 4 and the particle size of the liquid particle 11 is larger than that before the aggregation.

  FIG. 3 illustrates a case where the liquid particles 11 are charged at a stage before the liquid particles 11 are supplied to the exhaust atmosphere gas, as a modification of the first embodiment of FIG.

  In FIG. 3, before mixing the liquid particles 11 of FIG. 3 (b) with the atmospheric gas containing the solvent 10 of FIG. 3 (a) in FIG. A charge 15 is given by the corona discharge electrode 13 and the high voltage power source 14. And after making the liquid particle 11 into the charged state, the charged liquid particle 11 is supplied to the mixing part 4 (refer FIG.3 (c)). Accordingly, in FIG. 3C and FIG. 3D, in addition to the van der Waals force 12, the Coulomb force due to the charged electric charge 15 is also applied, so that both the van der Waals force 12 and the coulomb force 16 work. Compared with the case of van der Waals force 12 alone, aggregation can be promoted.

  In the field of dust recovery and the like, there is also known a method in which dust to be removed is charged by directly applying a charge to the powder to be removed by corona discharge and charged with a reverse-charged electrode. However, when the exhaust gas containing the vaporized solvent is charged by means such as corona discharge, for example, when the solvent is an organic solvent, the solvent having the risk of ignition or explosion has been vaporized. There is a possibility of ignition or explosion by discharging to the state. Therefore, in the first embodiment, instead of charging the vaporized solvent and charging it, a method of charging the liquid particles having no danger of explosion, for example, the liquid particles 11 of water by charging 10 is used. take.

  The state of the supplied liquid particles 11 is a state where the liquid particles 11 are present at each set temperature, that is, a state where the amount of water vapor contained in the atmospheric gas has reached the saturated vapor pressure. Therefore, when the water vapor pressure of the mixed atmosphere gas mixed in the mixing unit 4 does not reach the saturated water vapor pressure at that temperature, the liquid particles 11 mixed until the saturated water vapor pressure at the temperature of the mixed atmospheric gas is reached. The liquid particles 11 remaining when a part of the water vapor evaporates and reaches the saturated water vapor pressure are used for purification. On the other hand, when the temperature of the liquid particles 11 is higher than the temperature of the exhaust gas and the partial pressure of the water vapor of the exhaust gas reaches the saturated water vapor, the temperature of the mixed gas is higher than the temperature of the liquid particles 11. Accordingly, the saturated vapor pressure also decreases, and the water vapor contained in the mixed atmosphere gas cannot be present as water vapor, but is liquefied, that is, liquid particles. For this reason, the amount of the supplied liquid particles 11 does not decrease. In either case, the exhaust gas is purified by the liquid particles 11 existing as a liquid after mixing. Note that the exhaust duct 2 and the mixing unit 4 are inconvenient as a purification function using the liquid particles 11 because the liquefaction proceeds when the exhaust atmosphere gas passing through each of them is cooled by heat transfer at the outside air temperature. Absent. However, excessive liquefaction due to excessive cooling may affect corrosion in the exhaust duct 2 and the mixing unit 4. Therefore, in the first embodiment, in order to maintain the temperature of the exhaust atmosphere gas at a high temperature throughout the entire process of exhausting and circulating the atmosphere gas in the furnace, the respective devices or members are covered with a heat insulating material to block heat from the outside air. It is desirable that heat insulation treatment is applied.

  In general, the behavior of mist in the gas is determined by the size of the mist.

(1) When the mist size is less than 3 μm The mass of the particle can be ignored, and the slower the flow rate, the more the particle moves without being affected by inertia, so the particle does not move uniformly along the streamline. .
(2) In the case of a mist size particle size of 3 to 20 μm In the range where the influence of inertia and diffusion can be ignored, the center of the particle moves along the fluid streamline.

(3) When the mist size particle size is larger than 20 μm When the inertial force is large and the streamline is bent, the particles go straight by the inertial force.

  From the above, considering the steps of approaching, contacting, and agglomerating with the vaporized solvent 10 contained in the exhaust gas in the mixing unit 4, when the liquid particle 11 is a mist having a particle size of less than 3 μm, it follows the streamline. Do not perform uniform movement, but use Brownian movement. For this reason, the opportunity of the first “approach, contact” of the approach, contact, and agglomeration process is obtained, but in the range where the mass of the particles can be ignored, the separation and recovery process in the downstream centrifugal separator 5 is performed. There is a risk of reaching the exhaust blower 7 further downstream without being separated. On the other hand, when the size of the liquid particles 11 exceeds 20 μm, since the inertial force of the liquid particles 11 is large from the initial supply time point, the movement of the liquid particles 11 is also high in the mixing unit 4 and it is difficult to mix sufficiently. The possibility of contact with 10 is reduced, and contact between the liquid particles 11 is less likely to occur. Therefore, when the contact opportunity in gas or the separation / recovery process in the centrifugal separator 5 is taken into consideration, the size of the liquid particles 11 is preferably a particle size of 3 to 20 μm.

  In order to improve the contact opportunity between the solvent 10 and the liquid particles 11 in the mixing unit 4, the supply of the liquid particles 11 is not parallel to the flow line of the exhaust atmosphere gas in the exhaust duct 2, but an angle of less than 180 degrees. It is desirable to supply in the state given. FIG. 4 is an explanatory diagram when the flow lines 43 of the liquid particles 11 supplied from the liquid particle supply device 3 are supplied in a substantially vertical direction (approximately 90 degrees) with respect to the flow lines 42 of the exhaust atmosphere gas. . When the liquid particles 11 are added to the exhaust atmosphere gas in the mixing unit 4, the turbulent flow 17 is generated in the mixing unit 4 by intersecting and colliding both stream lines 42 and 43. Then, in the turbulent flow 17, contact between the solvent 10 and the liquid particles 11 or contact between the liquid particles 11 occurs. In this case, in order to generate the turbulent flow 17 and increase the contact opportunity, it is desirable that the flow rate when supplying the liquid particles 11 is equal to or higher than the flow rate when supplying the exhaust atmosphere gas.

  Alternatively, as shown in FIG. 5, a method in which the turbulent flow is positively generated by providing the stirring unit 18 in the mixing unit 4 to stir and mix the mixed atmosphere gas is also suitable. The stirring unit 18 is configured to generate a turbulent flow in the atmospheric gas by arranging a plurality of discs at predetermined intervals on a rotation shaft and rotating in a predetermined direction. A member or device can be used. According to the first embodiment, even when removing the vaporized solvent 10 contained in the exhaust atmosphere gas discharged from the heat treatment apparatus 1 that performs heating, the purified atmosphere gas is heat treated without cooling the exhaust atmosphere gas. It becomes possible to exhaust outside the apparatus. Further, liquid particles 11 generated by the liquid particle supply device 3 are supplied to the exhaust atmosphere gas discharged from the exhaust duct 2, and the vaporized solvent 10 and the liquid particles 11 in the exhaust atmosphere gas are mixed in the mixing unit 4. The solvent 10 is captured by the liquid particles 11 by repeating the approach, contact, and aggregation. As a result, the evaporated solvent 10 that cannot be removed from the exhaust gas by the centrifugal separation method with a small mass can be efficiently removed and purified by the centrifugal separator 5.

  Furthermore, since the mixing unit 4 is configured so that the stream line 42 of the exhaust atmosphere gas containing the vaporized solvent 10 and the stream line 43 of the liquid particles 11 intersect, the flow of the mixed atmosphere gas is turbulent, The approach, contact, and aggregation between the solvent 10 and the liquid particles 11 or between the liquid particles 11 can be promoted.

  When the mixing unit 4 includes the stirring unit 18, the exhaust atmosphere gas and the liquid particles can be mixed by the turbulent flow generated in the stirring unit 18, and the vaporized solvent in the exhaust atmosphere gas can be mixed. 10 and the liquid particles 11 and the approach and contact between the liquid particles 11 can be promoted.

(Second Embodiment)
FIG. 6 is an example in which an exhaust purification method is implemented by the exhaust purification device 41 in the second embodiment of the present invention.

  It further includes a duct 8 for allowing the centrifugal separator 5 and the heat treatment apparatus 1 to communicate with each other, and a circulation blower 9 disposed on the upstream side of the duct 8, that is, on the centrifugal separator side.

  The duct 8 is configured so that the exhaust atmosphere gas discharged from the centrifugal separator 5 is returned to the heat treatment apparatus 1 in a state where the outer surface of the duct 8 is covered with the heat insulating material 8a and is thermally insulated from the outside air by the heat insulating material 8a. ing. The circulation blower 9 promotes the circulation by forcibly returning the exhaust atmosphere gas discharged from the centrifugal separator 5 to the heat treatment apparatus 1.

  The second embodiment is an example in which the purified exhaust gas is not exhausted to the outside of the heat treatment apparatus 1 but is circulated back into the apparatus 1. More specifically, the exhaust atmosphere gas purified by removing the solvent 10 is discharged to the circulation blower 9 side communicating downstream. By driving the circulation blower 9, the atmospheric gas is again introduced into the heat treatment apparatus 1 through the duct 8. In this way, the purified exhaust atmosphere gas discharged from the centrifugal separator 5 is circulated into the heat treatment apparatus 1 through the duct 8 without being discharged outside the apparatus. In such a configuration, unless the active heating is performed, the temperature of the exhaust atmosphere gas decreases as it goes downstream from the heat treatment apparatus 1, and therefore the partial pressure of water vapor contained in the exhaust atmosphere gas is always constant. Continue to maintain saturated vapor pressure. Therefore, even when reheated by the heat treatment apparatus 1 and exhausted again, the water vapor always maintains a high partial pressure, and when the liquid particles 11 are supplied from the liquid particle generator 3 by the mixing unit 4, The amount of vaporized particles 11 can be suppressed. Further, when heat insulation is performed by the heat insulating material 8a over the entire circulation path, when circulating to the heat treatment apparatus 1, energy for raising the temperature to the furnace temperature of the heat treatment apparatus 1 again is not required. The energy consumption of the heat treatment apparatus 1 can be suppressed.

  According to the second embodiment, the exhaust atmosphere gas discharged from the centrifugal separator 5 can be circulated to the heat treatment apparatus 1 through the duct 8 that is thermally insulated from the outside air by the heat insulating material 8a. Therefore, the duct 8 for circulating the exhaust atmosphere gas discharged from the centrifugal separator 5 to the heat treatment apparatus 1 is insulated so as not to exchange heat with the external atmosphere gas in all steps of the exhaust atmosphere gas circulation. The heat is cut off by the material 8a, and the temperature of the circulating exhaust gas can be maintained without lowering.

  In the first or second embodiment, the liquid particle supply device 15 further consumes energy by using the dissipated heat discarded from the wall surface of the heat treatment device 1 to generate the high temperature liquid particles 11. Can be suppressed.

  In addition, it can be made to show the effect which each has by combining arbitrary embodiment or modification of the said various embodiment or modification suitably.

  Since the exhaust purification method of the present invention can purify the solvent contained in the exhaust atmosphere gas without cooling the exhaust atmosphere gas, the industrial product is an exhaust purification method that consumes less energy or uses less atmospheric gas. Or it can apply to the heat processing apparatus which performs various heat processings, such as a drying furnace in a manufacturing process of household appliances, or a manufacturing process of various electronic components, a baking furnace, a curing furnace, or a reflow furnace.

1. Heat treatment apparatus 2. Exhaust duct 3. Liquid particle supply device Mixing section 5. Centrifugal device 6. Drain Exhaust blower 8. Duct 8a. Insulation material 9. Circulating blower 10. Solvent 11. Liquid particles 11A. 11. Liquid particles having a larger particle size than before aggregation Van der Waals force 13. Corona discharge electrode 14. High voltage power supply 15. Charge 16. Van der Waals force + Coulomb force 17. Turbulence 18. Stirring section 19. Blower blower 20. In-device exhaust duct 21. Cooler 22. Furnace exhaust duct 23. Mist collector 40,41. Exhaust purification device

Claims (6)

In the heat treatment apparatus, the solvent is vaporized by heating the material containing the solvent, and the exhaust gas containing the vaporized solvent and exhausted from the heat treatment apparatus is purified.
Exhaust gas containing the vaporized solvent is exhausted out of the heat treatment apparatus by an exhaust duct communicating with the heat treatment apparatus,
In the mixing section connected to the exhaust duct, the exhaust atmosphere gas discharged from the heat treatment device through the exhaust duct, and the liquid particles supplied from the liquid particle supply device and heated to the exhaust atmosphere gas temperature or higher To form a mixed atmosphere gas,
From the centrifugal separator, the mixed atmospheric gas in which the exhaust atmospheric gas and the liquid particles are mixed is centrifuged by a centrifugal separator, and the liquid particles adsorbing the solvent from the exhaust atmospheric gas are centrifuged. An exhaust gas purifying method for an atmospheric gas, wherein the solvent and the liquid particles are removed from the exhausted exhaust gas and purified.   The liquid particles are charged at a stage before the liquid particles are supplied to the exhaust atmosphere gas when the liquid particles supplied from the liquid particle supply device are supplied into the exhaust duct or the mixing unit. 2. The exhaust gas purifying method of atmosphere gas according to 1.   The exhaust gas purification method according to claim 1, wherein the mixing unit performs mixing so that a streamline of the exhaust atmosphere gas and a streamline of the liquid particles intersect.   The exhaust gas purification method according to claim 1, wherein the mixing unit mixes the exhaust atmospheric gas and the liquid particles by turbulent flow generated in a stirring unit.   The exhaust purification method according to any one of claims 1 to 4, wherein the purified exhaust atmosphere gas discharged from the centrifugal separator is circulated in the heat treatment apparatus.   The exhaust purification method according to claim 5, wherein the exhaust atmosphere gas discharged from the centrifugal separator is circulated to the heat treatment apparatus through a duct that is thermally insulated from outside air by a heat insulating material.

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