JP3585067B2 - Heat deoiler - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat deoiler for removing mechanical oil attached to a work.
[0002]
[Prior art]
The manufacturing process of the conventional heat exchanger (see FIG. 2) 20 will be described below.
First, a component manufacturing process for manufacturing components such as the tube 21, the fins 22, the tank 20 and the header 24, a core assembling process for assembling them, a flux application process for applying a flux to a portion to be brazed and its vicinity, and an assembly The heat exchanger 20 was manufactured by sequentially performing a degreasing step of removing mechanical oil adhered to the surface of the substrate and a brazing step of brazing the assembly. The degreasing process is performed to prevent oil (particularly mechanical oil) from adhering to the components of the assembly in the above-described component manufacturing process and core assembling process, and to prevent this oil from adversely affecting the subsequent brazing process. This is conventionally performed by a heat deoiler as shown in FIG.
[0003]
An example of the heating deoiler will be described with reference to FIG. As shown in FIG. 3, the work W is configured such that the heat exchanger 20 is placed on a tray 25, a number of trays are stacked and placed on a carrier 26, and is conveyed by a conveyor 27.
Numerals 28 denote heating furnaces arranged in a row in contact with each other for heating and evaporating the oil adhering to the heat exchanger 20. The heating furnaces 28 at both ends are provided with preliminary chambers 29 in contact with them. The conveyor 27 sequentially passes through the preliminary chamber 29 and the heating furnace 28 to carry in and carry out the work W.
[0004]
A shutter (not shown) is provided at a work entrance / exit (not shown) provided at a boundary between the heating furnace 28 and the preliminary chamber 29 and preferably at an entrance / exit between the preliminary chamber 29 and the outside. Is opened so that the workpiece can pass only when the conveyor is driven.
The heating furnace 28 is provided with a furnace heating burner 30 serving as a heating heat source and a temperature sensor 31 for detecting the temperature in the heating furnace 28. A signal detected by the temperature sensor 31 is input by the controller 100, Based on this, the controller 100 controls the output heat amount of the furnace heating burner 30.
[0005]
Reference numeral 33 denotes an exhaust fan for exhausting oil evaporated by the heat of the furnace heating burner 30, and is exhausted to the outside through an exhaust duct 34. Reference numeral 35 denotes a combustor provided in the middle of the exhaust duct 34, which burns the oil-containing gas sucked from the heating furnace 28 by the exhaust fan 33 into a clean combustion gas.
Reference numeral 37 denotes a stirring fan for stirring the inside of the heating furnace 28, and is disposed on a ceiling of each heating furnace 28.
[0006]
Next, the operation will be described. First, the work W in the preliminary chamber 29 on the entrance side is transported into the heating furnace 28 by the conveyor 27. After the transfer, the shutter (not shown) is closed, and the temperature in the heating furnace 28 is detected by the temperature sensor 31 and output to the controller 100. Based on the temperature detected by the controller 100, the amount of heat generated by each furnace heating burner 30 Control.
[0007]
As a result, the oil adhering to each heat exchanger 20 is heated and evaporated, is sucked into the exhaust duct 34 by the exhaust fan 33, and is burned and removed by the combustor 35 on the way. Thereafter, the shutter is opened, the conveyor 27 is driven, and the work W in the rightmost heating furnace 28 is carried out to the right preliminary chamber 29, and the work W is carried into the leftmost heating furnace 28 from the left preliminary chamber 29. I do.
[0008]
[Problems to be solved by the invention]
However, in the conventional heating deoiler, since the furnace temperature is controlled only by controlling the furnace heating burner 30, there is a problem in that the inside of the heating furnace 28 is maintained in a suitable temperature range. Hereinafter, this problem will be described in detail.
First, the ignition point of this oil is, for example, lower than 300 ° C., and considering the safety, it is preferable to set the furnace temperature to around 200 ° C.
[0009]
Next, in the above-described conventional heat deoiler, the heat exchanger 20 before the brazing step is bound by wires or the like in order to prevent loosening or displacement between the components. When the temperature is as high as 200 ° C. or more, the linear expansion of the wire is larger than the expansion of the heat exchanger 20 before the brazing process, so that the wire is loosened even if the wire is tied firmly first. As a result, a relative displacement occurs between the above-mentioned components, and there is a possibility that the product becomes defective. For this reason, the temperature in the heating furnace 28 is preferably set to less than 200 ° C. in view of a certain margin.
[0010]
On the other hand, the evaporation temperature of the adhered oil at atmospheric pressure is usually about 140 to 160 ° C., and if the furnace temperature is lowered to this temperature or slightly higher, the evaporation speed of the adhered oil is significantly reduced. Of course, if the residence time in the furnace of the heat exchanger 20 before the brazing step is significantly extended, the reduction in the evaporation rate can be compensated for, but it is actually difficult in view of maintaining the productivity of the apparatus.
[0011]
After all, in order to evaporate the oil adhering to the work before the brazing process, the temperature in the furnace should be lower than the ignition temperature of the oil adhering, not higher than the temperature at which there is no deviation between the bound parts, and higher than the evaporating temperature of the oil adhering. It can be seen that it is preferable to keep the temperature within a certain narrow range.
However, the above-described furnace heating burner 30 is effective for rapid startup of the furnace at the start of operation because of its large heating value. However, when the temperature in the furnace is slightly changed, hunting is generated instead. In some cases, the internal temperature fluctuated greatly.
[0012]
Further, the furnace heating burner 30 essentially diffuses the locally generated high-temperature combustion gas of 1000 ° C. or higher by stirring and mixing, and heats it with the radiant heat. , The temperature of each part in the furnace may fluctuate.
Further, in the above-described conventional heat deoiling apparatus, the shutter (not shown) prevents the oil-containing gas from the heating furnace 28 from leaking to the outside through the preliminary chamber 29. Oil-containing gas, that is, oil or odor may leak to the outside through the spare chamber 29 due to incomplete airtightness or leakage at the time of opening and closing the shutter.
[0013]
In order to solve this problem, as shown in FIG. 5, it is easy to suck the air in the preliminary chamber 29 into the combustor 35 and burn the oil contained therein. However, in this case, even if a shutter is provided between the preliminary chamber 29 and the outside, the flow rate of the gas flowing into the combustor 35 increases in consideration of the leakage and the like. A new problem arises in that fuel consumption increases.
[0014]
The present invention has been made in view of the above-mentioned problems, and it is possible to prevent the ignition of the adhering oil and suppress the relative displacement of the components constituting the work, and to control the temperature inside the furnace by a good control of the furnace temperature before the brazing process. It is a first object of the present invention to provide a heating deoiling device capable of satisfactorily removing adhered oil.
A second object of the present invention is to achieve the first object while reducing fuel consumption and preventing oil leakage to the outside.
[0015]
[Means for Solving the Problems]
According to the heat deoiling device of the first aspect, the work before brazing to which the oil has adhered is heated in the heating furnace to evaporate the oil, and the oil-containing gas containing the evaporated oil component is burned in the combustor. A part of the generated combustion gas is returned to the heating furnace by the reflux duct, and the amount of the returned gas is controlled by the furnace temperature of the heating furnace.
[0016]
This makes it possible to satisfactorily control the temperature in the furnace so as to remove the oil adhering to the work before the brazing process while suppressing the relative displacement of the components constituting the work. More specifically, in comparison with the case where the furnace temperature is controlled by the furnace heating burner 30 having a large heat output, in the present apparatus, the combustion gas discharged from the combustor 35 for incinerating the oil-containing gas is supplied to the heating furnace. At the same time, the temperature of the heating furnace is adjusted by controlling the amount of the reflux. Since the temperature of the combustion gas is usually stable at about 400 ° C. and much lower than the combustion portion of the furnace heating burner 30, the furnace can be uniformly heated, and the flow rate can be controlled precisely. As a result, fluctuations in the furnace temperature can be suppressed, and hunting can be prevented.
[0017]
The need to control the work temperature (furnace temperature) within a narrow range when removing the oil adhering to the work before the brazing step has already been described, and thus the description is omitted.
In addition, in this device, the combustion gas is recirculated from the combustor, so that the amount of heat for heating the inside of the heating furnace can be reduced by the recirculation amount, and the fuel consumption can be reduced by that amount. it can. Heating of the heating furnace can be performed only with the combustion gas refluxing from the combustor, but in consideration of shortening the start-up time of the heating furnace, the above-mentioned furnace heating burner can be provided, and the furnace temperature can be reduced. It goes without saying that the control of the amount of recirculation and the adjustment of the amount of heat generated by the furnace heating burner can be used together for the control. However, in order to take advantage of the feature of the present apparatus that the furnace temperature fluctuation is reduced, it is preferable to control the furnace temperature after starting the heating furnace mainly by controlling the combustion gas recirculation amount. Considering the variation in the temperature of each part in the furnace due to the radiant heat of the burner, it is preferable to input heat to the heating furnace by recirculating the combustion gas after starting the heating furnace. However, when the furnace heating burner is not installed, it is preferable to shorten the start-up time by temporarily increasing the calorific value of the combustor at the time of starting up the heating furnace from the steady-state heat amount at the time of burning the oil-containing gas.
[0018]
As for the feedback control of the combustion gas recirculation amount, in addition to simply comparing the furnace temperature with the target temperature and controlling the combustion gas recirculation amount so as to eliminate the temperature difference, various known control methods are employed. Of course you can. For example, the rate of change of the temperature inside the furnace can be checked, and the rate of change of the recirculated amount of combustion gas can be controlled based on the rate of change. Then, the required heat quantity is calculated from the furnace temperature, and feedback control is performed based on the calculated heat quantity, thereby preventing control errors and hunting. Further, when the detected temperature difference between the furnace temperature and the target temperature is large, the change amount of the combustion gas recirculation amount from the balanced combustion gas recirculation amount (average value) is increased, and the change amount is reduced as the temperature difference decreases. It is possible to reduce the risk of hunting. Such a specific configuration of the feedback control itself can be performed by only slightly modifying the program of the microcomputer, and is not the gist of the present invention.
[0019]
It is easiest to specifically recirculate the combustion gas with a damper provided in the duct, but it is also possible to provide a fan capable of stepless speed control in the recirculation duct. According to the apparatus of the second aspect, in the apparatus of the first aspect, the reduction of the recirculation amount of the combustion gas for controlling the temperature in the furnace is performed within a range where the concentration of the evaporated oil component in the heating furnace does not reach the explosive limit concentration. Done. Thereby, explosion of a heating furnace or the like can be prevented.
[0020]
According to the apparatus of the third aspect, in the apparatus of the first or second aspect, the heating furnace further includes a furnace heating burner for heating the inside, so that the startup time of the heating furnace can be reduced. . It should be noted that it is naturally preferable to perform a control operation of reducing the amount of heat generated by the furnace heating burner together with the temperature rise due to the start-up from the viewpoint of preventing hunting.
[0021]
According to the device of claim 4, in the device of any one of claims 1 to 3, the blowing means is further disposed downstream of the combustor. This can prevent the blower from being soiled.
According to the apparatus according to claim 5, in the apparatus according to any one of claims 1 to 4, a plurality of heating furnaces are further arranged in a row adjacent to each other, and the amount of recirculated combustion gas to each heating furnace is reduced. Since each sub-damper controls individually, and the total amount of recirculated combustion gas is controlled by the main damper accordingly, good control can be performed.
[0022]
More specifically, when each sub-damper is closed, the pressure of the reflux duct at the upstream side of the sub-damper increases, and as a result, the pressure difference of the sub-damper increases. The flow rate cannot be reduced, and controllability deteriorates. On the other hand, when the opening degree of some of the sub-dampers is large, this does not occur, and when closing the other sub-dampers, the pressure difference is naturally small. Therefore, in the present device, this problem is prevented by suppressing the fluctuation of the pressure in the common duct portion upstream of the reflux duct.
[0023]
The control parameters for controlling the main damper include the pressure of the common duct, the opening degree of each sub-damper, the detected temperature of each heating furnace, and the deviation (temperature difference) between the detected temperature of each heating furnace and the target temperature. Can be used.
According to the apparatus of the sixth or seventh aspect, spare chambers are provided at both ends of the heating furnace, and the spare chamber is evacuated through an electric dust collector, and the oil is collected by the electric dust collector.
[0024]
In this way, oil and odor can be prevented from leaking to the outside, and problems such as an increase in the size of the combustor and an increase in fuel consumption due to the flow of low-temperature air into the combustor from the spare room are provided. Can be prevented.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be described based on the following examples.
(Example 1)
FIG. 1 is a schematic view showing one embodiment of the heating deoiler of the present invention. This heating deoiler itself is obtained by adding a reflux duct 38, a main damper 5, a sub damper 6, a pressure sensor 7, and an electric precipitator 9 to the conventional heating deoiler shown in FIG.
[0026]
More specifically, the work W is formed by stacking the heat exchangers 20 having the shapes shown in FIGS. 2 and 3, and the description thereof is omitted because it is already described. However, the heat exchangers 20 are bound together by wires (not shown) such that components such as the tube 21, the fins 22, the tank 20, and the header 24 do not shift. Further, a flux is applied in advance to a portion to be brazed. The reason why the heat deoiling step is performed after the application of the flux is that if the heat deoiling step is performed before the flux application, the work W must be cooled for the flux application, and the thermal economy is poor.
[0027]
Reference numeral 28 denotes four heating furnaces arranged in a row in contact with each other to heat and evaporate the oil adhering to the heat exchanger 20. The heating chambers 28 at both ends are provided with a preliminary chamber 29 in contact with them. A conveyor 27 sequentially passes through the preliminary chamber 29 and the heating furnace 28 to carry in and carry out the work W. A shutter (not shown) is provided at a work entrance (not shown) provided at a boundary between the heating furnace 28 and the preliminary chamber 29 and a work entrance (not shown) to the outside of the preliminary chamber 29, respectively. This shutter is opened so that the workpiece can pass only when the conveyor is driven.
[0028]
An exhaust fan 33 is provided in an exhaust duct 34 for exhausting oil evaporated by the heat of the furnace heating burner 30, and is exhausted outside or the like through the exhaust duct 34. Reference numeral 35 denotes a combustor provided in the middle of the exhaust duct 34, which burns the oil-containing gas sucked from the heating furnace 28 by the exhaust fan 33 into a clean combustion gas. Reference numeral 37 denotes a stirring fan for stirring the inside of the heating furnace 28, and is disposed on a ceiling of each heating furnace 28.
[0029]
A return duct 38 branching from an exhaust duct 34 downstream of the outlet of the exhaust fan 33 is provided, and a common duct 38 a forming an upstream portion of the return duct 38 is provided with a main damper 5 comprising a motor-driven proportional control damper device. And a pressure sensor 7 are provided. On the other hand, the downstream portion of the exhaust duct 34 branches into four branch duct portions 38b opening to each heating furnace 28, and each branch duct portion 38b is provided with a sub damper 8 composed of a motor-driven proportional control damper device. I have.
[0030]
Reference numeral 9 denotes an electric precipitator, and reference numeral 90 denotes an exhaust fan. Exhaust air sucked from the ceiling of the preliminary chamber 29 through the duct 34 and the electric precipitator 9 is discharged to the outside. A temperature sensor 31 for detecting the temperature in the heating furnace 28 is attached to the heating furnace 28, and a furnace temperature signal detected by the temperature sensor 31 is sent to a controller 100 having a microcomputer configuration. The main damper 5 is controlled based on the pressure signal output from the pressure sensor 7, and the sub damper 8 is controlled based on the furnace temperature signal detected by the temperature sensor 31.
[0031]
Next, the operation will be described. First, the combustor 35, the exhaust fans 33 and 90, and the electric precipitator 9 are operated, and the work W in the preliminary chamber 29 on the inlet side is transported into the heating furnace 28 by the conveyor 27. After the conveyance, the shutter (not shown) is closed, the main damper 5 and the sub damper 8 are opened, and the heating furnace 28 is heated. Then, the controller 100 controls the sub damper 8 based on the furnace temperature signal from the temperature sensor 31 to maintain the furnace temperature of each heating furnace 28 at 180 ° C., and further, based on the pressure signal from the pressure sensor 7. By controlling the damper 5, the pressure of the reflux duct 38 is maintained at a constant value.
[0032]
After the temperature in the heating furnace 28 is stabilized at 180 ° C., the work is retained in each of the preliminary chambers 29 and the heating furnace 28 for a certain period of time by the intermittent operation of the conveyor 27 and the synchronous opening and closing of the shutter. The attached oil is evaporated. The oil-containing gas containing oil evaporated in the heating furnace 28 is sucked into an exhaust duct 34 by an exhaust fan 33, and is burned and removed by a combustor 35 on the way. The oil leaking into the preparatory chamber 29 is sucked and collected by the electrostatic precipitator 9 together with the air in the preparatory chamber 29 by electrostatic force, and collected.
[0033]
FIG. 4 shows a flowchart example of the furnace temperature control of the present embodiment performed by the controller 100.
First, the furnace temperature t1 to t4 of each heating furnace 28 is detected from each temperature sensor 31 (100), and the furnace temperature corresponding to the number i stored in the built-in register among the detected furnace temperatures t1 to t4. It is determined whether ti is within a suitable temperature range (160 to 200 ° C.) (102). Note that the number i is any integer from 1 to 4. As a result of this determination, if the furnace temperature ti is lower than the preferable temperature range, the opening degree of the i-th sub damper 8 is increased by a predetermined amount to raise the furnace temperature of the i-th heating furnace 28 (104). If the in-furnace temperature ti is higher than the preferred temperature range, the opening of the i-th sub damper 8 is reduced by a predetermined amount to lower the in-furnace temperature of the i-th heating furnace 28 (106), and the routine proceeds to step 107. move on. If the in-furnace temperature ti is within this preferred temperature range, the routine proceeds directly to step 107.
[0034]
In step 107, the built-in register (a shift register that circulates in the order of 1, 2, 3, 4, 1, and 2 in this case) is shifted by one, and the process proceeds to step 108, where the pressure sensor 7 detects the pressure P of the return duct 38. Read. In the next step 110, it is determined whether or not the read pressure P is within the preferred pressure range (Ps-ΔP to Ps + ΔP). Note that Ps is an allowable deviation based on 1 atm and Ps.
[0035]
As a result of this determination, if the pressure P is lower than the preferred pressure range, the opening of the main damper 5 is increased by a predetermined amount to increase the pressure of the recirculation duct 38 (112), and the pressure P becomes lower than the preferred pressure range. If it is higher, the opening of the main damper 5 is reduced by a predetermined amount to lower the pressure of the return duct 38 (114), and the routine proceeds to step 116. If the pressure P is within this preferred pressure range, the process proceeds directly to step 116.
[0036]
In step 116, the process waits for a predetermined time and returns to step 100.
According to the apparatus of the present embodiment described above, since a furnace heating burner is not used as in the related art, the work surface where the burner exposes the work surface or the like that is strongly heated by the radiant heat does not receive the radiant heat. It is also possible to prevent the problem that the temperature becomes higher than the surface.
[0037]
(Modification)
In the above embodiment, the heat exchanger 20 before the brazing step is used as the workpiece W, but it is a matter of course that any workpiece can be used as long as it is an oil-adhered metal processed product before the brazing step. In the above embodiment, four heating furnaces 28 are used, but the number of heating furnaces 28 can be arbitrarily selected.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing one embodiment of a heat deoiler of the present invention.
FIG. 2 is a perspective view of a heat exchanger 20 that performs deoiling.
FIG. 3 is a perspective view of a work W formed by laminating the heat exchangers 20.
FIG. 4 is a flowchart showing a control operation of the controller 100 of FIG.
FIG. 5 is a schematic explanatory view showing an example of a conventional heat deoiler.
[Explanation of symbols]
5 is a main damper, 8 is a sub damper, 9 is an electric dust collector, 28 is a heating furnace, 35 is a heat exchanger, 33 is an exhaust fan (blower), 38 is a recirculation duct, 31 is a temperature sensor (temperature detecting means), 38a Is a common duct portion of the return duct 38, 38b is a branch duct portion of the return duct 38, and 100 is a controller (control means).

Claims (7)

A heating furnace that evaporates the oil by heating the work before brazing to which the oil is attached, a combustor that burns the oil-containing gas containing the oil introduced from the heating furnace, and the oil-containing gas from the heating furnace. A blower that feeds into the combustor and discharges combustion gas from the combustor,
A recirculation duct for recirculating a part of the combustion gas discharged from the combustor to the heating furnace, a temperature detection unit for detecting a temperature in the heating furnace, and the temperature based on at least an output signal of the temperature detection unit. Control means for controlling the recirculation amount of the combustion gas in a direction in which the temperature of the combustion gas converges to a predetermined target temperature. The control means may be configured to control the concentration of the evaporating oil component in the heating furnace within a range exceeding a flow rate exceeding a predetermined minimum flow rate value that is assumed to be equal to or higher than the explosion limit concentration by a predetermined margin flow value. The heating deoiler according to claim 1, wherein the detected temperature converges to the target temperature by adjusting a reflux amount. The heating deoiler according to claim 1, wherein the heating furnace includes a furnace heating burner for heating the inside. The heating deoiling device according to any one of claims 1 to 3, wherein the blower is disposed downstream of the combustor. A plurality of the heating furnaces are arranged so as to be able to communicate with each other in order by a work transfer port through which the work passes, the temperature detecting means is individually installed in each of the heating furnaces, and the return duct is a common duct part constituting an upstream part. And a branch duct section having an individual sub-damper and branching from the outlet of the common duct section to each of the heating furnaces, wherein the control means is based on each detected temperature detected from each of the temperature detection means. The sub-damper is adjusted to individually control the amount of recirculation for each of the heating furnaces, and the main damper disposed upstream of the recirculation duct is opened based on a parameter related to the detected temperature. 5. The heat deoiler according to claim 1, wherein the degree is adjusted. A pair of preparatory chambers arranged adjacent to the work entrance and the work exit of the heating furnace to prevent the oil-containing gas from leaking to the outside, and a transfer formed by connecting the heating furnace and the two preliminary chambers in order. A work transfer means for transferring the work along a path, an electric dust collector for removing gas introduced from the spare chamber, and an exhaust fan for discharging gas in the spare chamber through the electric dust collector; The heating deoiler according to any one of claims 1 to 5, wherein the pressure is maintained below the atmospheric pressure. A heating furnace that evaporates the oil by heating the work before brazing to which the oil is attached, a combustor that burns the oil-containing gas containing the oil introduced from the heating furnace, and the oil-containing gas from the heating furnace. A blower that feeds into the combustor and discharges combustion gas from the combustor,
A pair of spare chambers arranged adjacent to the work carry-in and work carry-out openings of the heating furnace to prevent the oil-containing gas from leaking to the outside, and along a transfer path formed by connecting the heating furnace in order; A work transfer means for transferring the work, an electric precipitator for removing gas introduced from the pre-chamber, and an exhaust fan for discharging gas in the pre-chamber through the electric precipitator; A heat deoiler which is set lower.

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