CN111054173A

CN111054173A - Exhaust gas purification system

Info

Publication number: CN111054173A
Application number: CN201811208963.5A
Authority: CN
Inventors: 王玉伟; 舒鹏; 张冬
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2018-10-17
Filing date: 2018-10-17
Publication date: 2020-04-24
Also published as: TW202027845A; WO2020081273A1; TWI811455B

Abstract

The application discloses exhaust gas purification system for purify the pollutant in the waste gas in the reflow soldering furnace, including first order cooling unit, second level cooling unit and filter unit, can make the pollutant in the waste gas be difficult to adhere to cooling device's inner wall, thereby the extension maintenance cycle. The application also discloses exhaust gas purification system that can automatically cleaning, including cooling unit, filter unit, heater block, first passageway and second passageway, gaseous self-cleaning gas circulation that forms in cooling unit, first passageway, filter unit and second passageway to can be convenient maintain exhaust gas purification system.

Description

Exhaust gas purification system

Technical Field

The present application relates to a waste gas treatment system for a reflow oven, and more particularly to a waste gas purification system for purifying waste gas in a furnace chamber of a reflow oven.

Background

In the manufacture of printed circuit boards, electronic components are typically mounted to the circuit board using a process known as "reflow soldering". In a typical reflow soldering process, solder paste (e.g., solder paste) is deposited onto selected areas of a circuit board, and the leads of one or more electronic components are inserted into the deposited solder paste. The circuit board then passes through a reflow oven where the solder paste is reflowed (i.e., heated to a melting or reflow temperature) in the heating region and then cooled in the cooling region to electrically and mechanically connect the leads of the electronic components to the circuit board. The term "circuit board" as used herein includes any type of substrate assembly of electronic components, including, for example, wafer substrates. In a reflow oven, air or a substantially inert gas (e.g., nitrogen) is typically used as the working gas, with different working gases being used for different process requirements of the circuit board. The oven chamber of the reflow oven is filled with a working gas in which the circuit boards are soldered while being conveyed through the oven chamber by the conveyor.

In a reflow oven, the solder paste includes not only solder, but also flux, which promotes wetting of the solder and provides a good solder joint. Other additives such as solvents and catalysts may also be included. After the solder paste is deposited on the circuit board, the circuit board is conveyed on a conveyor through a plurality of heating zones of a reflow oven. The heat in the heated area melts the solder paste and volatile organic compounds (referred to as "VOCs") including primarily flux vaporize to form vapor, thereby forming "contaminants". The accumulation of these contaminants in the reflow oven can cause problems. For example, if contaminants reach the cooling area, they will condense on the circuit board and contaminate it, thereby necessitating a subsequent cleaning step. Contaminants may also condense on the surfaces of the cooler of the reflow oven, thereby blocking the air holes. In addition, the condensation may also drip onto subsequent circuit boards, which may damage components on the circuit boards or necessitate subsequent cleaning steps for the contaminated circuit boards.

Disclosure of Invention

The exhaust gas containing contaminants in the reflow oven chamber needs to be exhausted out of the chamber to keep the working atmosphere in the reflow oven chamber clean, thereby preventing contaminants from entering the reflow oven cooling zone and causing the above-mentioned problems in the reflow oven.

When the reflow oven uses a substantially inert gas (e.g., nitrogen) as the working gas, it is generally desirable that the exhaust gas from the reflow oven be cleaned by an exhaust gas purification system and then sent back to the reflow oven for recycling, because the substantially inert gas (e.g., nitrogen) is expensive. When the reflow soldering furnace uses air as working gas, the waste gas discharged from the reflow soldering furnace can be directly discharged into the atmosphere after being treated by the waste gas purification system, and can also be conveyed back to the reflow soldering furnace for recycling.

One treatment scheme is to cool the exhaust gas in a cooling device to below about 80 ℃ to condense the pollutants in the exhaust gas from a gaseous form to a liquid or solid form, and then remove the pollutants in the liquid or solid form. However, the liquid or solid contaminants formed by temperature reduction are not only easily attached to the inner wall of the cooling device and difficult to clean, resulting in short maintenance period and high maintenance cost, but also attached to the heat exchange components (such as heat exchange plates or heat exchange tubes) of the cooling device, thereby affecting the heat exchange efficiency.

On the other hand, in the related art exhaust gas purification system, it is inconvenient to clean the connection pipes and various parts of the exhaust gas purification system manually.

Through observation and study, the applicant found that the hard-to-clean contaminants adhered to the inner wall of the cooling device and the heat exchange part in the exhaust gas purification system were mainly rosin in a solid form. This is because rosin and other fluxes in the pollutants are directly solidified from a gaseous form into a solid form when cooled from a high temperature to about 80 ℃, and adhere to the inner wall of the cooling device and the heat exchange member, so that the maintenance period of the exhaust gas purification system is too short, and the heat exchange efficiency is also affected.

In order to solve at least one of the problems described above, at least one object of the present application is to provide an exhaust gas purification system for a furnace of a reflow furnace, which can make rosin not easily adhere to an inner wall of a cooling device, thereby prolonging a maintenance period.

In order to achieve the above object, a first aspect of the present application provides an exhaust gas purification system for purifying pollutants in exhaust gas in a hearth of a reflow soldering furnace, comprising: a first stage cooling unit having an exhaust gas inlet and a gas outlet, the first stage cooling unit for cooling the exhaust gas entering the first stage cooling unit through the exhaust gas inlet to a first temperature such that a portion of the contaminants in the exhaust gas entering the first stage cooling unit are cooled from a gaseous state to a liquid state and discharged from the first stage cooling unit, a portion of the remaining portion of the contaminants in the exhaust gas entering the first stage cooling unit remaining in a gaseous state; a second stage cooling unit having a gas inlet and a gas outlet, the gas inlet of the second stage cooling unit being in fluid communication with the gas outlet of the first stage cooling unit, the second stage cooling unit being configured to cool the exhaust gas entering the second stage cooling unit from the first temperature to a second temperature such that a portion of the contaminants in the exhaust gas entering the second stage cooling unit are cooled from a gaseous state to a liquid state and are discharged from the second stage cooling unit, a portion of the remaining portion of the contaminants in the exhaust gas entering the second stage cooling unit remaining in a gaseous state or a mist state; the filter unit is provided with a gas inlet and a clean gas outlet, the gas inlet of the filter unit is communicated with the gas outlet of the second-stage cooling unit in a fluid mode, and the filter unit is used for filtering waste gas entering the filter unit and discharging at least one part of the filtered gas through the clean gas outlet of the filter unit.

According to the first aspect described above, the exhaust gas purification system further includes: the first-stage cooling unit and the second-stage cooling unit are respectively provided with a waste liquid outlet, and the collecting unit is controllably communicated with the waste liquid outlets of the first-stage cooling unit and the second-stage cooling unit in a flow equalizing mode and is used for collecting the discharged liquid waste gas.

According to the first aspect described above, the contaminants in the exhaust gas cooled from the gaseous state to the liquid state at the first temperature include organic rosin; at the second temperature, the pollutants in the waste gas cooled from the gas state to the liquid state comprise other low-condensation-point acid or ester or ether organic matters.

According to the first aspect, the first temperature is 110-130 ℃; the second temperature is 60-80 ℃.

According to the first aspect described above, the exhaust gas inlet of the first stage cooling unit is adapted to be controllably in fluid communication with the furnace chamber of the reflow oven.

A second aspect of the present application provides an exhaust gas purification system capable of self-cleaning, comprising: a cooling unit having a self-cleaning gas inlet and a gas outlet; a filter unit having a gas inlet and a self-cleaning gas outlet; a heating member provided in the filter unit for raising a temperature of the gas inside the filter unit; a first passage connecting a gas outlet of the cooling unit and a gas inlet of the filtering unit, the first passage being for conveying the gas in the cooling unit into the filtering unit; and a second channel connecting the self-cleaning gas outlet of the filtration unit and the self-cleaning gas inlet of the cooling unit, the second channel for controllably conveying gas in the filtration unit into the cooling unit; wherein a self-cleaning gas circulation is formed in the cooling unit, the first channel, the filtering unit and the second channel.

According to the second aspect described above, the exhaust gas purification system further includes: a fluid power device enabling gas to circulate in the filtration unit and the cooling unit through the first and second passages.

According to the second aspect described above, the cooling unit comprises an exhaust gas inlet for controllably connecting with the furnace of the reflow oven; the filter unit comprises a clean gas outlet for controllably discharging gas from the filter unit.

According to the second aspect described above, the exhaust gas purification system further includes: the cooling unit and the filtering unit are respectively provided with a waste liquid outlet, and the collecting unit is controllably communicated with the waste liquid outlets of the cooling unit and the filtering unit in a flow equalizing manner and is used for collecting the discharged liquid waste gas.

According to the second aspect, the cooling unit further has a make-up gas port for controllably fluidly communicating shielding gas to allow shielding gas to enter the exhaust gas purification system; the filter unit has a gas outlet for controllably discharging gas within the exhaust gas purification system.

The conception, specific structure and technical effects of the present application will be further described in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present application.

Drawings

FIG. 1A is a simplified block diagram of an exhaust purification system according to an embodiment of the present application;

fig. 1B is a block diagram showing a gas flow path when the exhaust gas purification system in fig. 1A is in an operating state;

fig. 1C is a block diagram showing a gas flow path when the exhaust gas purification system in fig. 1A is in a maintenance state; fig. 2A is a schematic perspective view of an exhaust gas purification apparatus according to an embodiment of the present application;

fig. 2B is a front view of the exhaust gas purifying apparatus shown in fig. 2A;

fig. 2C is a plan view of the exhaust gas purifying apparatus shown in fig. 2A;

fig. 3 is an exploded view of the exhaust gas purifying device shown in fig. 2A;

FIG. 4 is a cross-sectional view taken along line A-A of FIG. 2B;

FIG. 5 is a cross-sectional view taken along line B-B of FIG. 2C;

fig. 6 is a schematic perspective view of a cooling device in the exhaust gas purification device shown in fig. 2A;

fig. 7A is a schematic perspective view of an exhaust gas purification apparatus according to another embodiment of the present application;

fig. 7B is a front view of the exhaust gas purifying apparatus shown in fig. 7A;

fig. 7C is a plan view of the exhaust gas purifying apparatus shown in fig. 7A;

fig. 8 is an exploded view of the exhaust gas purifying device shown in fig. 7A;

FIG. 9 is a cross-sectional view taken along line A-A of FIG. 7B;

FIG. 10A is a cross-sectional view taken along line B-B of FIG. 7C;

FIG. 10B is a cross-sectional view taken along line C-C of FIG. 10A;

fig. 11 is a schematic perspective view of a cooling device in the exhaust gas purification device shown in fig. 7A.

Detailed Description

Various embodiments of the present application will now be described with reference to the accompanying drawings, which form a part hereof. It should be understood that although directional terms, such as "front," "rear," "upper," "lower," "left," "right," "top," "bottom," "side," and the like may be used herein to describe various example structural portions and elements of the application, these terms are used herein for convenience of description only and are intended to be based on the example orientations shown in the figures. Because the embodiments disclosed herein can be arranged in a variety of orientations, these directional terms are used for purposes of illustration only and are not to be construed as limiting.

It will be understood by those skilled in the art that the exhaust gas or gas described in the present embodiment refers to a component that is mostly in a gaseous state, and may also include a part of a component in a form of mist or particles.

Fig. 1A shows a simplified structural block diagram of an exhaust gas purification system according to an embodiment of the present application, for illustrating a connection relationship of respective parts of the exhaust gas purification system 100. As shown in FIG. 1A, the exhaust gas purification system 100 is disposed outside of the reflow oven chamber 118 and is coupled to the reflow oven chamber 118. When the reflow oven uses a substantially inert gas (e.g., nitrogen) as the working gas, the exhaust gas purification system 100 receives exhaust gas from the oven chamber 118 of the reflow oven and delivers the purified gas back into the oven chamber 118. When the reflow oven uses air as the working gas, the exhaust gas purification system 100 receives the exhaust gas exhausted from the furnace 118 of the reflow oven, and the purified gas may or may not be conveyed back into the furnace 118 and is exhausted to the outside of the furnace 118. In FIG. 1A, the flue gas cleaning system 100 delivers cleaned gas back into the furnace 118.

As shown in fig. 1A, the exhaust gas purification system 100 includes a first-stage cooling unit 110, a second-stage cooling unit 120, and a filtering unit 130, which are connected in sequence and are connected to the furnace 118 to purify the exhaust gas discharged from the furnace 118. The flue gas cleaning system 100 may also deliver cleaned gas back to the furnace 118. Also, the exhaust gas purification system 100 can self-clean the first-stage cooling unit 110, the second-stage cooling unit 120, and the filtering unit 130 and the connection passages therebetween.

Specifically, the first stage cooling unit 110 has an exhaust gas inlet 111.1, a self-cleaning gas inlet 114, a gas outlet 111.2 and a first waste liquid outlet 141.1. The second stage cooling unit 120 has a gas inlet 121.1, a gas outlet 121.2 and a waste outlet 141.2. The filter unit 130 has a gas inlet 131.1, a self-cleaning gas outlet 134, a clean gas outlet 131.2 and a waste liquid outlet 141.3.

The exhaust gas inlet 111.1 of the first stage cooling unit 110 is controllably in fluid communication with the high temperature zone of the furnace 118 via valve means 117.1. The gas outlet 111.2 of the first stage cooling unit 110 is in fluid communication with the gas inlet 121.1 of the second stage cooling unit 120 via a connecting channel 125.1. The gas outlet 121.2 of the second stage cooling unit 120 is in fluid communication with the gas inlet 131.1 of the filter unit 130 via a connecting channel 125.2, and the clean gas outlet 131.2 of the filter unit 130 is controllably in fluid communication with the low temperature zone of the furnace 118 via a valve member 117.2. Thus, the exhaust gas discharged from the furnace 118 can be purified by the first-stage cooling unit 110, the second-stage cooling unit 120, and the filtering unit 130 in this order and then returned to the furnace 118.

Furthermore, the self-cleaning gas outlet 134 of the filter unit 130 is connected to the gas inlet 114 of the first stage cooling unit 110 via a connecting channel 135, and a channel switching member 117.5 is provided on the connecting channel 135 to controllably fluidly connect the self-cleaning gas outlet 134 of the filter unit 130 to the gas inlet 114 of the first stage cooling unit 110. Thus, gas exiting from the self-cleaning gas outlet 134 of the filter unit 130 can enter the first stage cooling unit 110, and can flow through the first stage cooling unit 110 and the second stage cooling unit 120 in sequence, and then return to the filter unit 130 to form a self-cleaning gas circulation inside the exhaust gas purification system 100.

According to an embodiment of the present application, the first stage cooling unit 110 may not be provided with the self-cleaning gas inlet 114 separately from the exhaust gas inlet 111.1, but may use the same inlet as the exhaust gas inlet and the self-cleaning gas inlet. Likewise, the filter unit 130 may not be provided with a self-cleaning gas outlet 134 separate from the clean gas outlet 131.2, but may use the same outlet for both the self-cleaning gas outlet 134 and the clean gas outlet 131.2.

The exhaust gas purification system 100 further includes an air supply port 112 provided on the first-stage cooling unit 110 and an air discharge port 132 provided on the filter unit 130, and a gas concentration detection means for detecting the concentration of gas in the filter unit 130. As an example, the gas concentration detecting means is an oxygen concentration detecting means 155 for detecting the oxygen concentration to obtain the concentration of the working gas. Here, the oxygen concentration detection member 155 is disposed near the exhaust port 132. The supply port 112 is controllably opened and closed by the valve member 117.3 and the exhaust port 132 is controllably opened and closed by the valve member 117.4. When the reflow oven uses a substantially inert gas (e.g., nitrogen) as the working gas, the exhaust gas purification system 100 may be supplemented with the working gas (i.e., a substantially inert gas (e.g., nitrogen)) through the gas supplementing port 112, and the exhaust port 132 is used to operate in conjunction with the gas supplementing port 112 when the gas supplementing port 112 is in operation. The concentration of the working gas in the flue gas cleaning system 100 can be adjusted to match the working gas concentration in the furnace 118 by providing the make-up gas port 112 and the exhaust port 132. The make-up port 112 may be in controllable fluid communication with a source of working gas (i.e., a substantially inert gas such as nitrogen) via valve member 117.3, and the exhaust port 132 may be in controllable fluid communication with the atmosphere via valve member 117.4.

The filter unit 130 is provided therein with a filter member 136. Wherein the gas inlet 131.1 of the filter unit 130 is arranged on the upstream side of the filter member 136 and the self-cleaning gas outlet 134 and the clean gas outlet 131.2 are arranged on the downstream side of the filter member 136. It should be noted that "upstream" and "downstream" are referred to herein with respect to the direction of gas flow in the exhaust gas purification system 100. The filter element 136 may be a steel ball filter or a paper filter, etc.

The filter unit 130 is further provided with a heating member 133, and the heating member 133 is located below the filter member 136 and heats the filter member 136.

The exhaust gas purification system 100 further comprises a fan 124 for driving the flow of gas in the exhaust gas purification system 100. In the embodiment shown in FIG. 1A, the fan 124 is disposed in the filter unit 130. More specifically, the fan 124 is disposed above the filter element 136, the air inlet side of the fan 124 is in fluid communication with the plenum within the filter unit 130, and the air outlet side of the fan 124 is in fluid communication with the clean air outlet 131.2, the self-cleaning air outlet 134, and the air outlet 132 of the filter unit 130. In other embodiments, other fluid power devices (e.g., blowers, pumps, etc.) may be used instead of the fan 124 in the embodiment shown in fig. 1A, as long as the gas in the exhaust gas purification system 100 can be driven to flow according to a desired path.

The exhaust gas purification system 100 further includes a collection unit 140, and the waste liquid outlet 141.1 of the first stage cooling unit 110, the waste liquid outlet 141.2 of the second stage cooling unit 120, and the waste liquid outlet 141.3 of the filter unit 130 are all communicated with the collection unit 140, so that the liquids discharged from the first stage cooling unit 110, the second stage cooling unit 120, and the filter unit 130 can all flow into the collection unit 140. A valve member 117.6 is provided at an inlet of the collection unit 140, and the valve member 117.6 is closed to disconnect the collection unit 140 from the first-stage cooling unit 110, the second-stage cooling unit 120, and the filtering unit 130 when the collection unit 140 needs to be replaced or the liquid in the collection unit 140 is poured out.

The exhaust gas purification system 100 further comprises temperature detection means 151,152 arranged to detect the temperature in the first stage cooling unit 110 and the second stage cooling unit 120, respectively.

It should be noted that in the embodiment shown in fig. 1, the exhaust gas purification system 100 includes two cooling units, and the two cooling units are in fluid communication with each other through a connecting passage 125.1. In other embodiments, only the first stage cooling unit 110 or the second stage cooling unit 120 may be included in the exhaust gas purification system.

The exhaust gas purification system 100 has an operating state and a maintenance state. In operation, the exhaust gas purification system 100 purifies the exhaust gas from the reflow oven chamber 118. In the maintenance state, the exhaust gas purification system 100 no longer receives the exhaust gas from the reflow oven chamber 118, but the interior of the exhaust gas purification system 100 is self-cleaning. By controlling the opening and closing of the respective valve members 117.1,117.2,117.3,117.4,117.5,117.6, the exhaust gas purification system 100 can be switched between two states, that is, the operating state and the maintenance state. The flow paths of the gases in the two operating states of the exhaust gas purification system 100 of the present application are described below by taking as an example a reflow oven that uses a substantially inert gas (e.g., nitrogen) as the operating gas.

Fig. 1B shows a flow path of gas when the exhaust gas purification system 100 in fig. 1A is in an operating state. As shown in fig. 1B, when the exhaust gas purification system 100 is in an operating state, the valve member 117.1,117.2,117.6 is open, the valve members 117.3 and 117.4 are closed, and the passage switching member 117.5 may be closed, or at least partially open. The exhaust gas (temperature is approximately 170 ℃) containing the pollutants in the reflow oven chamber 118 is discharged from the high temperature region of the chamber 118, and then is cooled to a first temperature, for example, 110 to 130 ℃ by the first stage cooling unit 110. At this temperature, organic matters such as rosin in the exhaust gas pollutants in the first stage cooling unit 110 are condensed from a gaseous state to a liquid state and can be discharged from the waste liquid outlet 141.1 of the first stage cooling unit 110 into the collecting unit 140, and the remaining part of the exhaust gas is conveyed to the second stage cooling unit 120 for further cooling. The gas entering the second-stage cooling unit 120 is cooled to a second temperature, for example, 60 to 80 ℃, in the second-stage cooling unit 120, so that other pollutant organic matters (for example, low-condensation-point acid or ester or ether organic matters) in the exhaust gas are condensed into a liquid state from a gaseous state, and are discharged into the collecting unit 140 through the waste liquid outlet 141.2 of the second-stage cooling unit 120, and the remaining part of the exhaust gas is conveyed to the filtering unit 130 for filtering and purifying. After the exhaust gas entering the filtering unit 130 is filtered, the particulate and mist organic matters are removed, so that clean gas can be obtained. Finally, the clean gas is conveyed back to the low-temperature area of the reflow oven hearth 118 to complete the purification of the waste gas.

When the exhaust gas purification system 100 is in operation, if the valve element 117.5 is closed, the filtered clean gas from the filter unit 130 cannot be returned to the first stage cooling unit 110 via the connecting channel 135. If the passage switching part 117.5 is opened or partially opened, a part of the clean air filtered by the filter unit 130 can be returned to the first stage cooling unit 110 through the connection passage 135, and thus, the clean air having a lower temperature in the filter unit 130 can be used to cool the air in the first stage cooling unit 110, so as to save the cooling medium for heat exchange in the first stage cooling unit 110.

Fig. 1C shows the flow direction of the gas when the exhaust gas purification system 100 is in the maintenance state. As shown in fig. 1C, when the exhaust gas purification system 100 is in the maintenance state, the valve members 117.1,117.2,117.3,117.4 are opened, and the valve member 117.6 and the passage switching member 117.5 are opened. At this time, the gas in the filter unit 130 is heated by the heating member 133 in the filter unit 130, so that the temperature inside the filter unit 130 can be raised, for example, to about 150 to 170 ℃. At this temperature, some of the solid contaminants attached to the filter member 136 are converted into a liquid state and some are converted into a gaseous state, the liquid can be discharged through the waste liquid outlet 141.3 of the filter unit 130, and the gas is re-delivered to the first-stage cooling unit 110 and the second-stage cooling unit 120 through the connection passage 135 at a higher temperature. The gas in the first stage cooling unit 110 and the second stage cooling unit 110 flows back to the filtering unit 130 through the connecting passage 125.1,125.2 as in the above exhaust gas purification process, so that the pollutant organic matters in solid form attached to the respective components in the first stage cooling unit 110 and the second stage cooling unit 120 and the inner walls of the connecting passage 125.1 and the cooling passage 125.2 are heated again to liquid or gaseous state, and the liquid is discharged through the waste liquid outlet 141.1 of the first stage cooling unit 110 and the waste liquid outlet 141.2 of the second stage cooling unit 120, and the gas is returned to the filtering unit 130, thereby completing the self-cleaning gas circulation.

In the self-cleaning gas circulation process as shown in fig. 1C, the self-cleaning gas circulation process can be performed without affecting the operation of the reflow oven, since the valve parts 117.1,117.2 are disconnected. That is, even if the reflow oven is in operation, the exhaust gas purification system 100 can be maintained to self-clean the interior thereof.

A range of concentrations of the working gas in the reflow oven chamber 118 that uses a substantially inert gas (e.g., nitrogen) as the working gas is required to be maintained to meet the process requirements. Reflow ovens are typically provided with units that regulate the working gas concentration in the oven cavity 118 (e.g., units that replenish the working gas). When the exhaust gas purification system 100 is in operation, the gas in the furnace 118 of the reflow oven is continuously purified by the exhaust gas purification system 100 and returned to the furnace 118 of the reflow oven, so that the concentration of the working gas in the exhaust gas purification system 100 in operation is close to the concentration unit of the working gas in the furnace 118 of the reflow oven. However, when the flue gas cleaning system 100 is disconnected from the furnace 118 of the reflow oven for self-cleaning maintenance, the concentration of the working gas in the flue gas cleaning system 100 will typically be less than the concentration of the working gas in the furnace 118. Therefore, according to the present application, after the maintenance state of the exhaust gas purification system 100 is completed (the maintenance process including the self-cleaning gas circulation or the maintenance process using other cleaning methods), before the exhaust gas purification system 100 is communicated with the furnace 118 of the reflow oven again, a certain amount of working gas can be supplemented into the exhaust gas purification system 100, so that the concentration of the working gas in the exhaust gas purification system 100 is equal to or similar to that of the working gas in the reflow oven. For this purpose, the working gas is replenished into the exhaust gas purification system 100 through the replenishment port 112, and at the same time, the gas in the exhaust gas purification system 100 is discharged through the exhaust port 132 until it is judged by the gas concentration detection section 155 that the concentration of the shielding gas in the exhaust gas purification system 100 reaches the concentration of the shielding gas in the reflow furnace.

When the exhaust gas purification system 100 is used in a reflow oven using air as a working gas, the gas purified by the exhaust gas purification system 100 may be delivered back to the furnace 118, or may not be delivered back to the furnace 118, but may be directly discharged to the atmosphere. If the gas cleaned by the exhaust gas cleaning system 100 is discharged directly to the atmosphere, the clean gas outlet 131.2 of the filter unit 130 shown in fig. 1B is controllably in fluid communication with the atmosphere via the valve member 117.2 instead of being connected to the furnace 118.

The first stage cooling unit 110 and the second stage cooling unit 120 in the exhaust gas purification system 100 may employ any type of known heat exchange device according to the present application.

According to the present application, the first stage cooling unit 110, the second stage cooling unit 120 and the filtering unit 130 of the exhaust gas purification system 100 may be integrated together, so that the entire exhaust gas purification system 100 forms a box-type exhaust gas purification apparatus for use with a reflow oven.

Two specific structural examples of the exhaust gas purification apparatus are described below, in which fig. 2A to 6 show a specific structure of the exhaust gas purification apparatus 200 according to one embodiment of the present application, and fig. 7A to 11 show a specific structure of the exhaust gas purification apparatus 700 according to another embodiment of the present application.

Fig. 2A to 2C are schematic general structural views of an exhaust gas purification apparatus 200, where fig. 2A is a perspective structural view of the exhaust gas purification apparatus 200, fig. 2B is a front view of fig. 2A, and fig. 2C is a plan view of fig. 2A. As shown in fig. 2A-2C, the exhaust gas purification apparatus 200 includes a housing 201, and the housing 201 is substantially box-shaped having a cavity therein, and includes a top portion 202, a bottom portion 203, a left portion 204, a right portion 205, a front portion 206, and a rear portion 207. Wherein the top 202, the bottom 203, the left portion 204, the right portion 205 and the rear portion 207 of the housing 201 are connected together, for example by welding, to form a box cavity, and the front portion 206 is detachably connected to the top 202 and the bottom 203, for example by snapping, to close the box cavity. Wherein the top 202, bottom 203, left 204, right 205 and front 206 portions are shown in fig. 2B and the rear portion 207 is shown in fig. 2C.

As shown in fig. 2A-2C, the exhaust gas purification apparatus 200 further comprises an exhaust gas inlet 211.1 and a clean gas outlet 231.2 provided on the housing 201. The exhaust gas inlet 211.1 is provided with a connecting pipe 251.1, and the connecting pipe 251.1 is provided with a valve member 217.1. The valve member 217.1 can open and close. The waste gas inlet 211.1 is connected to the high-temperature zone (not shown) of the reflow oven chamber via a connecting pipe 251.1. The clean gas outlet 231.2 is provided with a connecting pipeline 251.2, and the connecting pipeline 251.2 is provided with a valve component 217.2. The valve member 217.2 can be opened and closed. The clean gas outlet 231.2 is connected to the low temperature zone (not shown) of the reflow oven chamber via a connecting duct 251.2. The exhaust gas discharged from the hearth can enter the exhaust gas purification device 200 from the exhaust gas inlet 211.1, is purified into clean gas through the exhaust gas purification device 200, and then is discharged to the low-temperature area of the hearth of the reflow oven from the clean gas outlet 231.2.

The exhaust gas inlet 211.1 is arranged to the rear of the right part 205 of the housing 201 and the clean gas outlet 231.2 is arranged to the left of the rear part 207 of the housing 201, as seen from the front of the exhaust gas cleaning device 200, whereby the flow direction of the exhaust gas in the exhaust gas cleaning device 200 is substantially from right to left.

The front portion 206 of the housing 201 comprises a first front plate 206.1 and a second front plate 206.2. The first front plate 206.1 serves to seal off a part of the interior of the housing 201 from the front (see filter volume 342 in fig. 3), and the second front plate 206.2 serves to seal off another part of the interior of the housing 201 from the front (see cooling volume 341 in fig. 3). Wherein the second front plate 206.2 is provided with a plurality of openings 271 for inserting cooling means into the cooling volume 341 through the openings 271 of the second front plate 206.2 (as will be described in detail in connection with fig. 3).

The exhaust gas purification device 200 further comprises a collecting device, which is attached to the bottom 203 of the housing 201. In the example shown, the collecting device comprises two collecting bottles 240.1 and 240.2, each connected to the bottom 203 of the housing 201 via a valve member 217.6, so that the condensed liquid contaminants can be controllably drained into the collecting bottles 240.1 and 240.2. The bottom 203 comprises a floor which slopes gradually downwards in the direction from back to front, to the front side of which collecting bottles 240.1 and 240.2 are attached (see fig. 4). The collector bottle 240.1 is adapted to communicate with a filtration volume 342 (see fig. 3) inside the housing 201 and the collector bottle 240.2 is adapted to communicate with a cooling volume 341 (see fig. 3) inside the housing 201. By providing an inclined floor, the contaminants condensed to liquid can be made to flow more easily into the collecting device.

The exhaust gas purification apparatus 200 further includes an exhaust port 232 and an air replenishment port 212 (see fig. 2C). As one example, the air replenishment port 212 is disposed on the top 202 of the housing 201 near the exhaust inlet 211.1. The exhaust 232 is arranged in the connection pipe 251.1 at the clean gas outlet 231.2 and is located at a position between the clean gas outlet 231.2 and the valve member 217.1. The bottom of the connecting pipe 251.1 at the clean gas outlet 231.2 is provided with an oxygen concentration detecting device 455 (see fig. 4), and the oxygen concentration detecting device 455 is used for detecting the oxygen concentration in the gas discharged at the clean gas outlet 231.2. Therefore, the flow direction of the supplementary protection gas to the exhaust gas purification apparatus 200 also flows substantially from right to left, so that the concentration of the working gas in the entire exhaust gas purification apparatus 200 can be increased. The exhaust port 232 and the air supplement port 212 are respectively provided with a valve member, and the opening or closing of the exhaust port 232 and the air supplement port 212 is controlled by the valve member, for example, by a solenoid valve. It will be appreciated by those skilled in the art that, in order to maintain the gas pressure in the exhaust gas purification apparatus 200 within a certain range, the valve components on the exhaust port 232 and the air supply port 212 should be simultaneously opened or simultaneously closed. Of course, the exhaust port 232 and the air supply port 212 may be disposed at other positions as long as the air can be controllably supplied into the exhaust gas purification apparatus 200 through the air supply port 212 and be controllably discharged out of the exhaust gas purification apparatus 200 through the exhaust port 232. The exhaust gas purification apparatus 200 further includes a blower 224. The drive components of the fan 224 are disposed to the left of the top 202 of the housing 201 and the impeller of the fan 224 is disposed within a filter volume 342 (see fig. 5) within the housing 201. The impeller of the fan 224 has an air inlet side in fluid communication with the filter volume 342 and an air outlet side in fluid communication with the purified air outlet 231.2.

The exhaust gas purification device 200 further comprises temperature detectors 213.1, 213.2, 213.3, 213.4, 213.5 and 213.6. Temperature detectors 213.1 and 213.2 are disposed at exhaust gas inlet 211.1 and clean gas outlet 231.2, respectively, and temperature detectors 213.3, 213.4 and 213.5 are connected to rear portion 207 of housing 201 and extend into cooling volume 341 (see fig. 5) of exhaust gas purification apparatus 200. The temperature sensor 213.6 is connected to the left part 204 of the housing 201 and projects into a filter chamber 342 (see fig. 5) of the exhaust gas purification device 200. As an example, temperature detectors 213.1, 213.2, 213.3, 213.4, 213.5, and 213.6 are thermocouples. In other examples, the exhaust gas purification apparatus 200 may include only a part of the temperature detector or be provided with another type of temperature detector.

The exhaust gas purification apparatus 200 further includes a plurality of heating rods 222. A heater rod 222 is also connected to the left portion 204 of the housing 201 and projects into the filter volume 342 (see fig. 5) of the exhaust gas purification device 200 in order to heat the filter element 336 (see fig. 5) in the filter volume 342 during the self-cleaning of the exhaust gas purification device 200. Other heating devices may be used in place of the heating rod 222 in other examples. Of course, the heating rod 222 may not be included in the exhaust gas purifying apparatus which does not need to be self-cleaned.

Fig. 3 is an exploded view of the exhaust gas purification apparatus 200 for illustrating the internal structure and components of the exhaust gas purification apparatus 200. As shown in fig. 3, the interior of the housing 201 includes a partition 437 (see fig. 4 for a specific structure of the partition 437), the partition 437 partitions the cavity inside the housing 201 into a cooling cavity 341 and a filtering cavity 342, and the cooling cavity 341 is located on the right side of the filtering cavity 342. However, partition plate 437 has upper opening 432 and lower opening 431 (see fig. 4) therein, and upper opening 432 and lower opening 431 are capable of communicating cooling chamber 341 and filtration chamber 342. The cooling volume 341 communicates with the waste gas inlet 211.1 and the filtration volume 342 communicates with the clean gas outlet 231.2. Cooling means for reducing the temperature of the gas in the cooling chamber 341 are provided in the cooling chamber 341. The cooling means includes a first stage cooling device 310 and a second stage cooling device 320, the first stage cooling device 310 being located at the right side of the second stage cooling device 320. After entering the cooling volume 341 from the waste gas inlet 211.1, the gas flows through the first stage cooling device 310 and the second stage cooling device 320 in sequence from right to left. A filter element 336 is provided in filter volume 342 and filter element 336 is mounted transversely in filter volume 342 such that gas entering filter volume 342 flows through filter element 336 from below to above to exit filter volume 342 through a clean gas outlet 231.2 above filter element 336.

A shroud 327 is also provided in the cooling plenum 341, the shroud 327 being disposed at a position near the top and rear of the cooling device, the shroud 327 together with the housing 201 forming part of a connecting passage through which the self-cleaning gas flows, as will be described in detail later.

After being discharged from a high-temperature region of a hearth of the reflow soldering furnace, the waste gas enters the waste gas purification device 200 from the waste gas inlet 211.1, pollutants such as rosin in the waste gas are condensed into liquid from a gaseous state through the cooling cavity 341 by the first-stage cooling device 310 and the second-stage cooling device 320 and are discharged into the collecting bottle 240.2, residual gas in the waste gas flows into the filtering cavity 342 through the opening 431, is filtered into clean gas by the filtering part 336 in the filtering cavity 342, and finally the clean gas is discharged to a low-temperature region of the hearth of the reflow soldering furnace from the clean gas outlet 231.2.

It should be noted that the cooling volume 341 may also be disposed on the left side of the filtering volume 342, but at this time, the exhaust gas inlet 211.1 needs to be located on the left portion 204 of the housing to maintain communication with the cooling volume 341, and the clean gas outlet 231.2 needs to be located on the right portion 205 of the housing to maintain communication with the filtering volume 342.

Still referring to FIG. 3, the first stage cooling arrangement 310 includes a plurality of cooling plates 315 and the second stage cooling arrangement 320 includes a plurality of cooling plates 317. Each cooling plate 315,317 may contain a cooling medium therein. The cooling medium in the cooling plates 315,317 exchanges heat with the exhaust gas through the outer peripheral side walls of the cooling plates 315,317, and the temperature of the exhaust gas is lowered. Each of the plurality of openings 271 of the second front plate 206.2 of the housing is dimensioned to match the size of a respective one of the cooling

plates

315 or 317, such that each cooling

plate

315 or 317, after being inserted into a respective opening 271, is able to close off the respective opening 271. A cooling

medium inlet

355 or 357 and a cooling

medium outlet

365 or 367 are provided in an end plate of each cooling

plate

315 or 317 located outside the housing 201, and a cooling medium can be introduced into the

corresponding cooling plate

315 or 317 through the cooling

medium inlet

355 or 357 and can be discharged from the corresponding

cooling plate

315 or 317 through the cooling

medium outlet

365 or 367. The cooling

medium inlet

355 or 357 and the cooling

medium outlet

365 or 367 may be sealed.

In the embodiment shown in fig. 3, the cooling medium in the plurality of cooling plates 315 of the first stage cooling device 310 is compressed gas and the cooling medium in the plurality of cooling plates 317 of the second stage cooling device 320 is air. The muffler 208 (see fig. 2A) is provided at the cooling medium outlet 365 of the plurality of cooling plates 315 of the first stage cooling device 310 to reduce noise caused by the flow of the compressed gas. A filter screen is further provided at the cooling medium inlet 357 of the plurality of cooling plates 317 of the second-stage cooling device 320, and a gas pipe 318 and a suction fan 319 are connected so that air can be input from the cooling medium inlet 357 and output from the cooling medium outlet 367 at a certain speed. Of course, other types of cooling media, such as cooling water, etc., may be selected by those skilled in the art depending on the actual working environment.

Fig. 4 is a sectional view taken along a-a line in fig. 2B, for illustrating a specific structure of the partition plate 437. As shown in fig. 4, a partition 437 inside the housing 201 is connected between the top 202 and bottom 203 of the housing 201 for separating the cooling volume 341 from the filtration volume 342. The partition plate 437 is provided with an upper opening 432 and a lower opening 431, wherein the upper opening 432 is provided at a higher position within the housing than the filter member 336 (not shown in fig. 4), and the lower opening 431 is provided at a lower position within the housing than the filter member 336 (not shown in fig. 4). Wherein the upper opening 432 is in fluid communication with an air outlet side 584 of an impeller 580 of the fan 224 (see fig. 5).

The shroud 327 is L-shaped in cross-section and includes transverse plates 425 and risers 426 that are interconnected, with the transverse plates 425 abutting or substantially abutting the rear portion 207 of the housing 201 and the risers 426 abutting the top portion 202 of the housing 201 such that the shroud 327 and the housing 201 together form a connecting channel 635 (see fig. 6). The connecting passage 635 is aligned with and communicates with the upper opening 432 of the divider plate 437 such that gas in the filter volume 342 can pass through the upper opening 432 of the divider plate 437 into the connecting passage 635.

Thus, gas in cooling volume 341 can flow through lower opening 431 into filter volume 342, flowing from bottom to top in filter volume 342 to be filtered as a net gas by filter element 336. Also, a portion of the filtered purge gas in the filtering volume 342 can be discharged to the reflow oven through the purge gas outlet 231.2, and another portion of the purge gas flows through the connecting passage 635 through the upper opening 432 and then flows back into the cooling volume 341.

Fig. 5 is a sectional view taken along line B-B in fig. 2C, for illustrating the detailed structure of the first-stage cooling device 310, the second-stage cooling device 320, and the filter member 336, and illustrating the flow path of gas during the exhaust gas purification process. As shown in fig. 5, the first stage cooling device 310 includes four cooling plates 315 and the second stage cooling device 320 includes two cooling plates 317.

The four cooling plates 315 are arranged in the lateral direction of the housing 201 (i.e., in the left-right direction). Each cooling plate 315 has a cavity 546.1, the cavity 546.1 communicating with a cooling medium inlet 355 and a cooling medium outlet 365 on the housing 201, so that compressed air as a cooling medium can flow into and out of the cavity 546.1 of the cooling plate 315. Two cooling plates 317 are also arranged in the lateral direction (i.e., in the left-right direction), each cooling plate 317 having a cavity 546.2, the cavity 546.2 communicating with a cooling medium inlet 357 and a cooling medium outlet 367 on the housing 201, so that air as a cooling medium can flow into and out of the cavities 546.2 of the cooling plates 317. Each of the cooling

plates

315 and 317 is made of a thermally conductive material, such as metal, so that the gas around the cooling

plates

315 and 317 can exchange heat with the cooling medium contained in the cooling

plates

315 and 317. The gas in the first stage cooling device 310 and the second stage cooling device 320 can be cooled to a temperature range by adjusting the speed at which the cooling medium flows into or out of the cooling

plates

315 and 317.

Each cooling plate 315,317 is vertically positioned (i.e., in a direction perpendicular to the top 202 and bottom 203 of the housing), with vertical gas passages 548 formed between each two adjacent cooling plates. Each cooling plate 315,317 has left and right side walls, and as the exhaust gas in the cooling volume 341 flows through the vertical gas passage 548, the exhaust gas passes through the left and right side walls of the cooling plates 315,317 to exchange heat with the cooling medium in the cavities 546.1 and 546.2, thereby reducing the temperature of the exhaust gas. As the exhaust gases descend, a portion of the contaminants in the exhaust gases can condense into liquid and flow down the left and right sidewalls of the cooling plates 315,317 to the bottom 203 of the housing. Note that, in the leftmost cooling plate, vertical gas passages 548 are formed between the cooling plate and the left partition plate 437 in addition to vertical gas passages 548 being formed between the cooling plate and the adjacent cooling plate on the right side thereof. Similarly, for the rightmost cooling plate, in addition to forming vertical gas passages 548 with the adjacent cooling plate to its left, vertical gas passages 548 are also formed with the housing right portion 205.

Also, each cooling plate 315,317 also forms a bottom transverse gas passage 549.2 with the housing bottom 203 or a top transverse gas passage 549.1 with the housing top 202. Wherein each of the top lateral gas passage 549.1 and the bottom lateral gas passage 549.2 is in communication with at least one vertical gas passage 548 to form a gas passage 550 for the flow of the exhaust gas. As an example, the top transverse gas channels 549.1 and the bottom transverse gas channels 549.2 are alternately arranged in the direction of the arrangement of the cooling plates 315,317 to form a curved gas channel 550 as shown in FIG. 5. Wherein the exhaust gas inlet 211.1 communicates with the rightmost vertical gas channel 548 and the lower opening 431 of the separation plate communicates with the leftmost vertical gas channel 548, such that exhaust gas can flow into the gas channel 550 from the rightmost vertical gas channel 548 and flow out of the gas channel 550 from the leftmost vertical gas channel 548. In other embodiments, the top transverse gas channels, the bottom transverse gas channels, and the vertical gas channels may be arranged in other arrangements to form other gas channels, as long as the exhaust gas is allowed to flow in the gas channels and through each cooling plate.

As will be appreciated by those skilled in the art, in this embodiment, each cooling plate 315,317 forms only one of the bottom transverse gas channel 549.2 or the top transverse gas channel 549.1 in order to form the curved gas channel 550. When the bottom transverse gas channel 549.2 is formed between the cooling plates 315,317 and the housing bottom 203, the cooling plates 315,317 need to abut or otherwise block the gap between the housing top 202 so that fluid cannot pass between the cooling plates 315,317 and the housing top 202. Likewise, when the top lateral gas passage 549.2 is formed between the cooling plate and the housing top 202, the cooling plates 315,317 need to abut or otherwise block the gap between the housing bottom 203 so that fluid cannot pass between the cooling plates 315,317 and the housing bottom 203.

In the embodiment shown in FIG. 5, there are three cooling plates 315,317 that form a top transverse gas passage 549.1 with the housing top 202. A set of seal plates 554 are provided adjacent the housing bottom 203 for each of the three cooling plates 315,317. Each set of seal plates 554 includes two seal plates 554 that abut against the lower left and right sides of the respective cooling plate 315,317 to block the gap between the cooling plate 315,317 and the housing bottom 203 so that fluid cannot pass between the cooling plate 315,317 and the housing bottom 203. By providing the seal plate 554, fluid flow between the cooling plates 315,317 and the housing bottom 203 is blocked, even when the housing bottom 203 is in the angled shape shown in FIG. 4. Of course, one skilled in the art may also design the shape of the cooling plate without providing the sealing plate 554, such that the cooling plate matches the shape of the bottom 203 of the housing.

As shown in fig. 5, the temperature detector 213.3 is used for detecting the gas temperature at the gas inlet of the first stage cooling device 310, the temperature detector 213.4 is used for detecting the gas temperature at the gas outlet of the first stage cooling device 310, the temperature detector 213.5 is used for detecting the gas temperature at the gas outlet of the second stage cooling device 320, and the temperature detector 213.6 is used for detecting the gas temperature in the filtering device. These temperature detectors can detect the gas temperature in the exhaust gas purification apparatus 200 in real time and adjust the flow rate of the cooling medium in accordance with the temperature situation. When the detected gas temperature is too high, or when the influence of adjusting the flow rate of the cooling medium on the gas temperature is not significant, it may be necessary to self-clean the exhaust gas purification apparatus 200.

The filter component 336 is disposed in the middle of the filter cavity 342, dividing the filter cavity 342 into an upper sub-cavity and a lower sub-cavity, wherein the lower sub-cavity is communicated with the lower opening 431 of the partition plate, and the impeller 580 of the blower 224 is disposed in the upper sub-cavity, so that the air inlet side 582 of the impeller 580 of the blower 224 is in fluid communication with the upper sub-cavity. The air outlet side 584 of the impeller 580 of the fan 224 is in fluid communication with the clean air outlet 231.2 and the upper opening 432 of the divider plate. As impeller 580 rotates, gas is allowed to flow within cooling plenum 341 and filter plenum 342 in the direction of the arrows shown in fig. 5. As an example, the filtering component 336 is a steel ball filter screen, which is beneficial to heat conduction on one hand, and can be cleaned for reuse and cost saving on the other hand.

It should be noted that, with the cooling cavity being sized, the transverse width of the cooling plate 315 of the first stage cooling device 310 should be as small as possible to accommodate sufficient cooling medium to allow less rosin that condenses to liquid when the exhaust gas flows through the first stage cooling device 310 to accumulate on top of the cooling plate 315. Thus, a smaller lateral width, but greater number of cooling plates 315 are included in the first stage cooling arrangement 310, while a larger lateral width, but lesser number of cooling plates 317 are included in the second stage cooling arrangement 320. In the embodiment shown in fig. 5, the transverse width of the cooling plate 315 of the first stage cooling arrangement 310 is one third of the transverse width of the cooling plate 317 of the second stage cooling arrangement 320. In other embodiments, other numbers of cooling plates 315,317 may be provided, and the lateral widths of cooling

plates

315 and 317 may be in other proportions, so long as it is ensured that the cooling medium contained within cooling plates 315,317 is sufficient to cool the exhaust gases to the desired temperature.

Fig. 6 is a schematic perspective view of the cooling device in the exhaust gas purifying device 200 of fig. 5, for illustrating the specific structure and positional relationship of the cooling plate, the partition plate 437 and the enclosing plate 327, to explain the flow path of the self-cleaning gas circulation process. In order to show the internal structure of the cooling plates 315,317, the end plates of the cooling plates 315,317 (i.e., the end plates provided with cooling medium inlets and outlets shown in fig. 3) are removed in fig. 6. As shown in fig. 6, the partition plate 437, the cooling plate 544, and the cooling plate 543 in the exhaust gas purification apparatus 200 are vertically placed substantially in parallel, and are spaced apart from each other to form the gas passage 550 as described above.

The shroud 327 is provided behind and above the cooling plates 544 and 543, and extends in the left-right direction. As an example of one arrangement, a portion of the cooling plate, for example, the portion of the cooling plate forming the bottom lateral air passage 549.2 with the bottom 203 of the housing, is provided with a stepped support portion on the top rear side thereof. The step-shaped support portion is for receiving an L-shaped shroud 327. This arrangement makes it possible to make the structure of the exhaust gas purification apparatus 200 more compact. It will be appreciated by those skilled in the art that the shroud 327 may not be L-shaped or have no supports or the like provided thereon, but rather, it is sufficient to ensure that the cooling plate, shroud 327 and housing are sealed as necessary to form the gas channel 550.

With the above arrangement, the shroud 327 can form a connecting passage 635 with the housing 201, and both ends of the connecting passage 635 are provided with a self-cleaning gas outlet 634 and a self-cleaning gas inlet 614, wherein the self-cleaning gas outlet 634 is communicated with the upper opening 432 of the partition 437, and the self-cleaning gas inlet 614 is communicated with the cooling cavity 341 at the first stage cooling device 310. As an example, the self-cleaning gas inlet 614 is located near the exhaust gas inlet 211.1.

As one example, the upper opening 432 of the divider plate 437 can be sized to allow gas in the filter volume 342 to controllably flow into the connecting passage 635. In the embodiment of the present application, an adjustable stopper 638 is movably connected to the partition plate 437, and the adjustable stopper 638 can move back and forth to cover the upper opening 432 or open the upper opening 432, and the opening size of the upper opening 432 can be adjusted. Be equipped with guide way 661 on adjustable baffle 638, be provided with on the division board 437 guide pin 662 and insert in guide way 661, realize the mobilizable connection between adjustable baffle 638 and division board 437.

Thus, when the exhaust gas purification device 200 is in the maintenance state, the gas in the filter volume 342 can flow into the connecting passage 635 through the upper opening 432 and flow to the first stage cooling device 310 through the connecting passage 635.

As also shown in fig. 6, flow equalization plates 656.1 are included in cavity 546.1 inside cooling plate 315, and similarly flow equalization plates 656.2 are included in cavity 546.2 inside cooling plate 317, each having a plurality of through holes. As an example, a plurality of circular holes 658.1 are uniformly formed on the flow equalizing plate 656.1, and a plurality of elongated holes 658.2 are formed on the flow equalizing plate 656.2. Flow equalizing plates 656.1 and 656.2 are provided on the flow paths of the cooling medium in the cavities 546.1 and 546.2, respectively, so that the cooling medium can pass through the through holes and flow uniformly and stably. With respect to the cooling plate 317, air flows from the cooling medium inlet 357 into the cavity 546.2 of the cooling plate, passes through the flow equalizing plate 656.2 from bottom to top, and then flows out from the cooling medium outlet 367 to exchange heat with the exhaust gas through the side wall of the cooling plate 317. For the cooling plate 315, the compressed gas flows from the cooling medium inlet 355 into the cavity 546.1 of the cooling plate 315, passes through the flow equalizing plate 656.1 from bottom to top, and then flows out from the cooling medium outlet 365 to exchange heat with the exhaust gas through the side wall of the cooling plate 315.

The exhaust gas is roughly purified in the exhaust gas purification apparatus 200 as follows: exhaust gas (at approximately 170 c) containing contaminants is discharged from the high temperature zone of the reflow oven chamber and enters the gas tunnel 550 through the exhaust gas inlet 211.1. When the exhaust gas flows through the cooling plate 315 in the first stage cooling device 310, the flow rate of the compressed air flowing into and out of the cooling plate 315 is adjusted, so that the exhaust gas is cooled to about 110-130 ℃ (the gas temperature at the outlet of the first stage cooling device 310, measured by the temperature detection device 213.4), at which temperature organic matters such as rosin and other scaling powder in the exhaust gas are condensed from a gaseous state to a liquid state, and can be discharged into the collecting bottle 240.2. The remaining portion of the exhaust gas flows through the cooling plate 317 in the second stage cooling device 320, and is cooled to about 60-80 ℃ (the temperature of the gas at the outlet of the second stage cooling device 320, measured by the temperature detection device 213.5) by adjusting the flow rate of the air flowing into and out of the cooling plate 317, at which temperature the organic substances of other pollutants in the exhaust gas, such as the organic substances of acids or esters or ethers with low condensation points, are condensed from the gas state to the liquid state and can be discharged to the collecting bottle 240.2. The remaining exhaust gas flows into the filter chamber 342 through the lower opening 431 of the partition 437, then flows through the filter component 336 from bottom to top, and is filtered by the filter component 336 to remove particulate and misty organic matter therein, so as to obtain clean gas. Finally, most of the clean gas is discharged from the clean gas outlet 231.2 to the low temperature region of the reflow oven furnace chamber, the purification process of the waste gas is completed, and a small part of the clean gas can flow back to the first stage cooling device 310 through the upper opening 432 and the connecting passage 635 to be mixed with the waste gas and reduce the temperature of the waste gas. Adjusting the opening size of the upper opening 431 may change the amount of net gas flowing back into the first stage cooling device 310 through the upper opening 432 and the connecting passage 635. Of course, the upper opening 431 may be completely closed, preventing the net gas from being able to flow back into the first stage cooling device 310 through the upper opening 432 and the connecting passage 635.

The self-cleaning process of the exhaust gas purification apparatus 200 is as follows: the waste gas inlet 211.1 and the clean gas outlet 231.2 are closed by the valve members 217.1 and 217.2 and the gas in the filtration vessel 342 is heated by the heater 222 until the temperature in the filtration vessel 342 rises to about 150 c to about 170 c (as measured by the temperature sensing device 213.6) so that a portion of the solid contaminants adhering to the filter member 336 are converted to a liquid state and a portion are converted to a gaseous state, with the liquid contaminants flowing to the housing bottom 203. The high-temperature gaseous pollutants flow from bottom to top to the upper opening 432 of the partition plate under the action of the fan 224, then flow through the connecting passage 635 and are conveyed back to the first-stage cooling device 310 and the second-stage cooling device 320, and the solid pollutants attached to the surfaces of the inner wall of the housing, the outer wall of the cooling device, the enclosing plate 327, the filtering component 336 and the like in the exhaust gas purification device 200 are heated to be liquid again to be cleaned. Wherein liquid contaminants from the bottom 203 of the housing are collected by the collecting devices 240.1 and 240.2.

After the self-cleaning process is completed, the working gas such as nitrogen is supplied to the exhaust gas purification apparatus 200 through the gas supply port 212, and the gas in the exhaust gas purification apparatus 200 is discharged from the exhaust port 232. After the oxygen concentration in the exhaust gas purification device 200 is detected to meet the requirement, the exhaust gas purification device 200 is communicated with the hearth of the reflow oven.

Fig. 7A to 11 show the structure of an exhaust gas purification apparatus 700 according to another embodiment of the present application, in which the exhaust gas purification apparatus 700 is different from the exhaust gas purification apparatus 200 mainly in the specific structure of the cooling apparatus.

Fig. 7A to 7C are schematic general structural views of an exhaust gas purification apparatus 700, in which fig. 7A is a perspective structural view of the exhaust gas purification apparatus 700, fig. 7B is a front view of fig. 7A, and fig. 7C is a plan view of fig. 7A. As shown in fig. 7A to 7C, the exhaust gas purification apparatus 700 includes a housing 701, and the housing 701 has a structure similar to that of the housing 201 of the exhaust gas purification apparatus 200, including a top portion 702, a bottom portion 703, a left portion 704, a right portion 705, a front portion 706, and a rear portion 707, which will not be described again.

The clean air outlet 731.2 of the exhaust gas purification device 700 is arranged to the left in the rear section 707 of the housing 701. In contrast to the exhaust gas inlet 211.1 of the exhaust gas purification device 200, the exhaust gas inlet 711.1 of the exhaust gas purification device 700 is arranged on the rear 707 of the housing 701, and the exhaust gas inlet 711.1 is arranged to the right of the rear 707 of the housing 701. Accordingly, the supply 712 is also disposed on the rear side of the top 702 of the housing 701, near the exhaust inlet 711.1. While the positions of the exhaust port 732 and the oxygen concentration detecting device 955 (see fig. 9) are maintained.

The front 706 of the housing 701 includes a first front panel 706.1 and a second front panel 706.2.

Wherein the second front panel 706.2 is also provided with a plurality of openings 771 for inserting cooling means into the second cooling volume 862. The exhaust gas purification apparatus 700 further comprises collection bottles 740.1 and 740.2 attached to the bottom 703 of the housing, and a blower 724 attached to the top 702 of the housing.

Fig. 8 is an exploded view of the exhaust gas purification apparatus 700, illustrating the cooling volume 841 and the filtering volume 842 inside the exhaust gas purification apparatus 700 to illustrate the flow direction of gas in the exhaust gas purification apparatus 700. As shown in fig. 8, the interior of housing 701 includes a partition 937 (partition 937 has the same structure as partition 437, see fig. 9 in particular), partition 937 partitions the interior of housing 701 into a cooling chamber 841 and a filter chamber 842, and cooling chamber 841 and filter chamber 842 are communicated through a lower opening 931 (see fig. 9) of partition 937. Cooling cavity 841 includes first cooling cavity 861 and second cooling cavity 862, and first cooling device 810 is arranged in first cooling cavity 861, and second cooling device 820 is arranged in second cooling cavity 862, and after entering cooling cavity 841 from waste gas inlet 711.1, the gas flows through first cooling device 810 and second cooling device 820 from right to left in sequence. The filter volume 842 comprises a filter member 836 therein, and after entering the filter volume 842, the gas flows from bottom to top through the filter member 836 and can flow out of the filter volume 842 through the purified gas outlet 731.2. The structure of the second stage cooling device 820 is the same as that of the second stage cooling device 320 in the exhaust gas purification device 200, and the description thereof is omitted. An L-shaped shroud 827 is provided on the upper portion of the second-stage cooling device 820 toward the rear side, and unlike the shroud 327 of the exhaust gas purification device 200 shown in fig. 2A to 6, the shroud 827 is provided only at the second-stage cooling device 820.

As also shown in fig. 8, the first stage cooling device 810 includes cooling fins 863 and cooling tubes 865, each of the cooling tubes 865 can contain a cooling medium therein, and the cooling medium in the cooling tubes 865 exchanges heat with the exhaust gas through the cooling fins 863. Second stage 820 includes a plurality of cooling plates 817, the cooling plates 817 sized to match the openings 771 in the second front panel 706.2. Wherein, as seen from the front of the housing, the first stage cooling device 810 is provided with a cooling medium inlet 855 and a cooling medium outlet 815, and the second stage cooling device 820 is provided with a cooling medium inlet 857 and a cooling medium outlet 816. It is to be noted that the two groups of cooling medium inlets 855 and cooling medium outlets 815 are not arranged side by side, where one group of cooling medium inlets 855 and cooling medium outlets 815 are relatively close to each other, and the other group of cooling medium inlets 855 and cooling medium outlets 815 are relatively far from each other (see fig. 7B). In the embodiment shown in fig. 8, the cooling medium in the cooling pipes 865 of the first stage cooling device 810 is compressed gas, and the cooling medium in the plurality of cooling plates 817 of the second stage cooling device 820 is air. A muffler 708 is also provided at each cooling medium outlet 815 of the first stage cooling device 810.

Fig. 9 is a sectional view taken along line a-a in fig. 7B, for illustrating a specific structure of the divider plate 937. The partition 937 has a structure similar to that of the partition 437 of the exhaust gas purification apparatus 200 shown in fig. 2A to 6, and also has an upper opening 932 and a lower opening 931. And shroud 827 includes transverse plates 925 and vertical plates 926 that cooperate with housing 701 to form connecting channel 1135 (see FIG. 11). Wherein the upper opening 932 is also in fluid communication with an air outlet side 1084 (see fig. 10) of the impeller 1080 of the fan 724.

Fig. 10A and 10B are views for illustrating specific structures of the first-stage cooling device 810, the second-stage cooling device 820, and the filter member 836 to explain a flow path of gas in the exhaust gas purification process. Wherein fig. 10A is a sectional view taken along line B-B of fig. 7C, fig. 10B is a sectional view taken along line C-C of fig. 10A, and only the first cooling device 810 is shown in fig. 10B with other components removed in order to more clearly show the detailed structure of the first cooling device 810.

As shown in fig. 10A and 10B, the first stage cooling device 810 includes four layers of cooling fins 863 and four layers of cooling tubes 865, and cooling media are contained in the four layers of cooling tubes 865. The cooling pipe 865 is connected to the cooling fin 863, and performs heat exchange with the exhaust gas through the cooling fin 863, so that the temperature of the exhaust gas is reduced.

Wherein, four layers of cooling fins 863 are arranged along longitudinal direction (that is, arranged in the up-down direction), each layer of cooling fins 863 is transversely arranged (that is, arranged in the left-right direction), and a certain distance is provided between two adjacent layers of cooling fins 863. The cooling tube 865 has a cavity 1046.1. The cooling fins 863 are made of a heat conductive material, such as metal, so that the exhaust gas in the first cooling compartment 861 can exchange heat with the cooling medium in the cavities 1046.1 of the cooling tubes 865 by heat transfer of the cooling fins 863.

Each layer of cooling fins 863 is generally U-shaped having through slots 1064 and side slots 1072 (see also fig. 11), wherein the through slots 1064 are provided at the bottom 1066 of the cooling fins 863 and extend in the left-right direction. The exhaust gas passes through the through slots 1064 at the bottom of the cooling fins 863 to form a longitudinal gas flow 1068 from top to bottom. It should be noted that, since the exhaust inlet 711.1 is disposed at the rear side of the housing, the exhaust flows from the rear to the front in addition to the top to the bottom. The side grooves 1072 are provided on both side walls 1067 of the cooling fin 863, and both ends of the through groove 1064 communicate with the pair of side grooves 1072, respectively. The cooling pipe 865 passes through a pair of side grooves 1072 to support the cooling fins 863 so that the cooling fins 863 are detachably connected with the cooling pipe 865.

A plurality of through grooves 1064 are formed in each layer of cooling fins, and the through grooves 1064 in at least a part of the two adjacent layers of cooling fins 863 are arranged in a staggered manner, so that the exhaust gas passes through each layer of cooling fins 863 not along a straight line from top to bottom, but along a curved path, thereby better exchanging heat with the cooling pipes 865 and the cooling fins 863. In the example shown in fig. 10A and 10B, the through slots 1064 of the first and second tiers of cooling fins 863 are staggered, and the through slots 1064 of the third and fourth tiers of cooling fins 863 are staggered.

The number of the cooling pipes 865 and the side grooves 1072 is set to correspond to the number of the through grooves 1064. And the cooling pipe 865 of each layer communicates with the cooling medium inlet 855 and the cooling medium outlet 815 of the housing 701, so that compressed air as the cooling medium can flow into the cooling pipe 865 and flow out of the cooling pipe 865. As an example, the cooling tubes 865 of each layer are joined together by an input manifold 1081 and/or an output manifold 1085 (see also fig. 11), and the input manifold 1081 and the output manifold 1085 are connected to the cooling medium inlet 855 and the cooling medium outlet 815 of the housing 701. The input manifold 1081 and the output manifold 1085 are tubes extending in the front-rear direction, one end of which is closed, and the other end of which is connected to the cooling medium inlet 855 or the cooling medium outlet 815.

As an example, the respective cooling tubes of the first and fourth tiers are connected together to form a right-side open U-shaped cooling tube, wherein the U-shaped cooling tube nozzles of the first tier are connected to the output manifold 1085 and the U-shaped cooling tube nozzles of the fourth tier are connected to the input manifold 1081. Similarly, the cooling tubes of the second tier and the third tier are connected together to form a left open U-shaped cooling tube, wherein the U-shaped cooling tube ports of the second tier are connected to the output manifold 1085 and the U-shaped cooling tube ports of the third tier are connected to the input manifold 1081. Thus, only two sets of cooling medium inlet 855 and cooling medium outlet 815 may be provided in case 701. In other embodiments, separate input and output manifolds may be provided at both ends of the cooling tubes of each layer for connection to the housing 701, in which case four sets of cooling medium inlets and outlets may be provided on the housing.

In the illustrated example of the present application, six cooling tubes are included in the first and fourth layers of cooling tubes 865, while five cooling tubes are included in the second and third layers.

Thus, the cooling pipe 865 can expand the area of heat exchange with the longitudinal gas flow 1068 by the cooling fins 863, so that the temperature of the longitudinal gas flow 1068 formed by the off-gas is reduced, and a portion of the contaminants in the off-gas can condense into liquid and flow up and down to the bottom 703 of the housing through the through slots 1064.

Second stage cooling device 820 includes two cooling plates 817, each cooling plate 817 having the same structure as cooling plate 317 in fig. 5 to form vertical gas passages 1048. The cooling plate 817 has a cavity 1046.2 for containing a cooling medium (e.g. air), the cavity 1046.2 communicating with the air inlet 716.1 and the air outlet 716.2 on the housing 701 so that air as a cooling medium can flow into and out of the cooling plate 817. A bottom transverse air channel 1049.2 is formed between the right cooling plate 817 and the housing bottom 703, and a top transverse air channel 1049.1 is formed between the left cooling plate 817 and the housing top 702. The top lateral gas passage 1049.1 and the bottom lateral gas passage 1049.2 are in fluid communication with the vertical gas passage 1048 to form a curved gas cooling passage 1050. And the bottom transverse gas passage 1049.2 is in communication with the first stage cooling device 810 so that the longitudinal flow of gas 1068 in the first cooling cavity 861 passes from above and below the first stage cooling device 810 and into the gas cooling passage 1050.

Referring back to fig. 10A, filter element 836 is also disposed in the middle of filter volume 842, dividing filter volume 842 into two sub-volumes, a lower sub-volume communicating with partition plate lower opening 931 and an upper sub-volume communicating with clean gas outlet 731.2 and partition plate upper opening 932. The impeller 1080 of the blower 724 is disposed in the upper sub-volume such that the air intake side 1082 of the impeller 1080 of the blower 724 is in fluid communication with the upper sub-volume. The air outlet side 1084 of the impeller 1080 of the fan 724 is in fluid communication with the clean air outlet 731.2 and the upper opening 932 of the divider plate. As impeller 1080 rotates, it enables gas to flow within cooling volume 841 and filter volume 842 in the direction of the arrows shown in fig. 10A. As one example, the filter element 836 is also a steel ball screen.

It should be noted that the first stage cooling device 810 in this embodiment may be any final finned heat exchanger component known to those skilled in the art to save cost.

Fig. 11 is a schematic perspective view of a cooling device in an exhaust gas purification device 700 according to the present application, which shows specific configurations and positional relationships of a first-stage cooling device 810, a second-stage cooling device 820, a partition plate 937, and a shroud 827. Similar to the exhaust gas purifying apparatus 200, a stepped-shaped catching groove for receiving the shroud 827 is provided on the top rear side of the right-hand cooling plate 817 in the second-stage cooling apparatus 820. Wherein the shroud 827 can form with the housing 701 a connecting channel 1135, the connecting channel 1135 having a self-cleaning gas outlet 1134 and a self-cleaning gas inlet 1114, wherein the self-cleaning gas outlet 1134 communicates with an upper opening 932 of the partition 937, and the self-cleaning gas inlet 1114 communicates with the exhaust gas inlet 711.1. In this embodiment, since the exhaust gas inlet 711.1 is located closer to the second stage cooling device 820, the shroud 827 only needs to be disposed behind the second stage cooling device 820 so that the self-cleaning gas inlet 1114 of the connecting channel 1135 communicates with the exhaust gas inlet 711.1.

Similarly, divider 937 is also coupled to adjustable stop 1138 to adjust the size of upper opening 932. This arrangement enables a portion of the gas in the sub-volume above the filter volume 342 to be vented from the clean gas outlet 731.2 to the reflow oven and another portion of the gas to flow through the upper opening 932 into the connecting channel 1135 and through the connecting channel 1135 to the vicinity of the off-gas inlet 711.1.

A cavity 1046.2 inside the cooling plate 817 comprises flow equalizing plates 1156, and each flow equalizing plate is provided with a plurality of elongated holes 1158.

The exhaust gas is roughly purified in the exhaust gas purification apparatus 700 as follows: exhaust gases (at a temperature of approximately 170 c) containing contaminants are discharged from the high temperature region of the reflow oven chamber and pass from the exhaust gas inlet 711.1 into the first cooling volume 861. The exhaust gas flows through the first stage cooling device 810 from top to bottom and from back to front, and the velocity of the compressed air flowing into and out of the cooling pipe 865 is adjusted so that the temperature of the gas at the outlet where the exhaust gas is cooled is about 110-130 ℃, and at this temperature, organic matters such as rosin in the exhaust gas are condensed from a gaseous state to a liquid state and flow to the bottom 703 of the housing through the through groove 1064 from top to bottom. The rest of the exhaust gas flows through the cooling plate 817 in the second-stage cooling device 820 from right to left, and the velocity of the air flowing into and out of the cooling plate 817 is adjusted, so that the temperature of the gas at the outlet of the rest of the exhaust gas is about 60-80 ℃, and at this temperature, other pollutant organic matters in the exhaust gas, such as low-condensation-point acid or ester or ether organic matters, are condensed into a liquid state from a gaseous state and flow to the bottom 703 of the shell along the side wall of the cooling plate 817. The remaining portion of the exhaust gas flows into the filtering chamber 842 through the lower opening 931 of the partition 937, then flows from bottom to top through the filtering member 836, and is filtered by the filtering member 836 to remove particulate and misty organic matter therein, so as to obtain clean gas. Finally, most of the clean gas is discharged from the clean gas outlet 731.2 to the low temperature region of the reflow oven furnace chamber, the purification process of the exhaust gas is completed, and the remaining small part of the clean gas flows back to the first stage cooling device 810 through the upper opening 932 and the connecting channel 1135 to be mixed with the exhaust gas and reduce the temperature of the exhaust gas. Adjusting the opening size of the upper opening 932 may change the amount of net air that flows back into the first stage cooling device 810 through the upper opening 932 and the connecting channel 1135. Of course, the upper opening 932 may also be completely closed, preventing the net gas from being able to flow back into the first stage cooling device 810 through the upper opening 932 and the connecting channel 1135. Wherein the liquid contaminants in the bottom 703 of the housing are collected by the collection device 740.2.

The self-cleaning process of the exhaust gas purification apparatus 700 is similar to that of the exhaust gas purification apparatus 200 and will not be described in detail.

The main difference between the exhaust gas purification apparatus 200 and the exhaust gas purification apparatus 700 in the two embodiments of the present application is that the first-stage cooling apparatus is different. Among them, the cooling plate 315 in the first-stage cooling device 310 of the exhaust gas purification device 200 has a smaller lateral area, and therefore, causes less contaminants to accumulate on the heat exchange member (cooling plate 315), and therefore, enables a longer maintenance interval. While the first stage cooling device 810 of the exhaust gas purification apparatus 700 is a commercially available finished product, which can be provided at a lower cost.

Although the present application will be described with reference to the particular embodiments shown in the drawings, it should be understood that many variations of the exhaust gas purification device of the present application are possible without departing from the spirit and scope and background of the teachings of the present application. Those of ordinary skill in the art will also recognize that there are different ways to alter the arrangement of the embodiments disclosed in this application, all within the spirit and scope of the application and claims.

Claims

1. An exhaust gas purification system for purifying a reflow oven chamber (118)1. an exhaust gas purification system for purifying pollutants in exhaust gas in a reflow oven chamber (118), characterized by: the method comprises the following steps:

a first stage cooling unit (110), the first stage cooling unit (110) having an exhaust gas inlet (111.1) and a gas outlet (111.2), the first stage cooling unit (110) being configured to cool the exhaust gas entering the first stage cooling unit (110) through the exhaust gas inlet (111.1) to a first temperature such that a portion of the contaminants in the exhaust gas entering the first stage cooling unit (110) are cooled from a gaseous state to a liquid state and discharged from the first stage cooling unit (110), a portion of a remaining portion of the contaminants in the exhaust gas entering the first stage cooling unit (110) remaining in a gaseous state;

a second stage cooling unit (120), the second stage cooling unit (120) having a gas inlet (121.1) and a gas outlet (121.2), the gas inlet (121.1) of the second stage cooling unit (120) being in fluid communication with the gas outlet (111.2) of the first stage cooling unit (110), the second stage cooling unit (120) being configured to cool the exhaust gas entering the second stage cooling unit (120) from the first temperature to a second temperature, such that a portion of the contaminants in the exhaust gas entering the second stage cooling unit (120) is cooled from a gaseous state to a liquid state and is discharged from the second stage cooling unit (120), a portion of the remaining portion of the contaminants in the exhaust gas entering the second stage cooling unit (120) remaining in a gaseous state or mist state;

a filter unit (130), the filter unit (130) having a gas inlet (131.1) and a clean gas outlet (131.2), the gas inlet (131.1) of the filter unit (130) being in fluid communication with the gas outlet (121.2) of the second stage cooling unit (120), the filter unit (130) being configured to filter the exhaust gas entering the filter unit (130) and to discharge at least a portion of the filtered gas through the clean gas outlet (131.2) of the filter unit (130).

2. The exhaust gas purification system according to claim 1, characterized in that: further comprising:

a collection unit (140), the first stage cooling unit (110) and the second stage cooling unit (120) each having a waste liquid outlet (141.1,141.2), the collection unit (140) being controllably in fluid communication with both the waste liquid outlets (141.1,141.2) of the first stage cooling unit (110) and the second stage cooling unit (120) for collecting the discharged liquid exhaust gas.

3. The exhaust gas purification system according to claim 1, characterized in that:

at the first temperature, the pollutants in the waste gas cooled from the gaseous state to the liquid state comprise rosin organic matters;

at the second temperature, the pollutants in the waste gas cooled from the gas state to the liquid state comprise other low-condensation-point acid or ester or ether organic matters.

4. The exhaust gas purification system according to claim 3, characterized in that:

the first temperature is 110-130 ℃;

the second temperature is 60-80 ℃.

5. The exhaust gas purification system according to claim 1, characterized in that:

the exhaust gas inlet (111.1) of the first stage cooling unit (110) is for controllable fluid communication with the furnace chamber (118) of the reflow oven.

6. An exhaust gas purification system capable of self-cleaning, characterized in that: the method comprises the following steps:

a cooling unit (110,120), the cooling unit (110,120) having a self-cleaning gas inlet (114) and a gas outlet (121.2);

a filter unit (130), the filter unit (130) having a gas inlet (131.1) and a self-cleaning gas outlet (134);

a heating means (133), the heating means (133) being provided in the filter unit (130) for raising the temperature of the gas inside the filter unit (130);

a first channel (125.2), the first channel (125.2) connecting a gas outlet (121.2) of the cooling unit (110,120) and a gas inlet (131.1) of the filtering unit (130), the first channel (125.2) being for conveying gas in the cooling unit (110,120) into the filtering unit (130); and

a second channel (13), a second channel (135), the second channel (135) connecting a self-cleaning gas outlet (134) of the filter unit (130) and a self-cleaning gas inlet (114) of the cooling unit (110,120), the second channel (135) for controllably conveying gas in the filter unit (130) into the cooling unit (110, 120);

wherein the gas forms a self-cleaning gas circulation in the cooling unit (110,120), the first channel (125.2), the filter unit (130) and the second channel (135).

7. The exhaust gas purification system according to claim 6, characterized in that: further comprising:

a fluid power device (124), the fluid power device (124) enabling gas to circulate in the filtration unit (130) and the cooling unit (110,120) through the first channel (125.2) and the second channel (135).

8. The exhaust gas purification system according to claim 6, characterized in that:

the cooling unit (110,120) comprises an exhaust gas inlet (111.1), the exhaust gas inlet (111.1) being adapted to be controllably connected to a furnace chamber (118) of a reflow oven;

the filter unit (130) comprises a clean gas outlet (131.2), the clean gas outlet (131.2) being adapted for controllably discharging gas from the filter unit (130).

9. The exhaust gas purification system according to claim 6, characterized by further comprising:

a collection unit (140), the cooling unit (110,120) and the filtration unit (130) each having a waste liquid outlet (141.1,141.2,141.3), the collection unit (140) being controllably in fluid communication with both the waste liquid outlets (141.1,141.2) of the cooling unit (110) and the filtration unit (130) for collecting the discharged liquid exhaust gas.

10. The exhaust gas purification system according to claim 6, characterized in that:

the cooling unit (110,120) further having a make-up gas port (112), the make-up gas port (112) for controllably fluidly communicating a shielding gas to enable shielding gas to enter into the exhaust gas purification system (100);

the filter unit (130) has a gas outlet (132), the gas outlet (132) being adapted to controllably discharge gas from within the exhaust gas purification system (100).