Vacuum drying and degreasing system and method suitable for evaporator or condenser of air conditioner

Abstract

The invention provides a vacuum drying and degreasing system and method suitable for an air conditioner evaporator or condenser in order to solve the problems of poor degreasing effect and secondary waste gas treatment of traditional degreasing equipment, and belongs to the technical field of degreasing. The vacuum drying and degreasing system comprises a vacuum drying box, a nitrogen supply device, an oil gas condensing device, a vacuum pump and the like. The vacuum drying and degreasing method comprises the following steps: placing an evaporator or a condenser to be treated; vacuumizing to a certain degree, filling a certain amount of nitrogen, enabling the pressure of the vacuum drying box to be 10000-90000Pa (absolute pressure), heating the sealed nitrogen to enable heat to be transmitted to the workpiece, and maintaining the temperature of the inner wall of the vacuum drying box to be 100-260 DEG C; and finally, exhausting and degreasing oil gas, cooling and recovering. Compared with a traditional degreasing device and method, the mode that nitrogen is charged in the vacuum environment, heat is transferred through nitrogen and oil gas cooling recovery is combined is adopted, the degreasing temperature is reduced, the degreasing effect is good, energy is saved, consumption is reduced, the operation cost is low, tail gas can be directly discharged in a standard reaching mode, and other environment-friendly equipment does not need to be added for treatment.

Description

Technical Field

[0001] The invention relates to the technical field of degreasing, and in particular to a vacuum drying and degreasing system and method suitable for an evaporator or a condenser. Background Art

[0002] During the processing of air-conditioning condensers or evaporators, stamping volatile grease is usually added to ensure that the fins and copper tubes can be formed smoothly. In the later stage of processing, the stamping volatile grease needs to be fully removed by degreasing equipment.

[0003] Traditional degreasing equipment mainly uses natural gas, electricity, liquefied petroleum gas or infrared lamps to heat the continuously charged air, and then uses the continuously heated air to heat the air conditioner condenser or evaporator. The air and oil gas after heating the evaporator or condenser are directly discharged, and waste gas treatment equipment must be configured to treat them to meet environmental protection requirements. Therefore, traditional degreasing equipment has the following problems: (1) High energy consumption: Since the boiling point of stamping volatile oil is 170℃, the conventional process needs to heat the evaporator or condenser to 160℃-180℃. At the same time, the conventional process discharges a large amount of hot air, which will cause a lot of heat loss, so a large amount of heat is required; (2) Oxidation of evaporator or condenser: It is carried out under normal pressure. The evaporator or condenser needs to be heated to 160℃-180℃. The oxygen content in the air is 21%. After drying and degreasing, the evaporator and condenser are severely oxidized. (3) Secondary pollution: The volatile oil will generate a large amount of harmful substances such as benzene and amines when it is cracked at high temperature. The volatile oil is directly discharged into the atmosphere, which will pollute the environment; (4) Poor effect: The traditional degreasing process has poor effect on removing volatile oil and moisture on the inner surface of copper tubes. Summary of the invention

[0004] The present invention provides a vacuum drying degreasing system and method suitable for an evaporator or condenser to solve the defects of traditional degreasing equipment such as high energy consumption, oxidation of the evaporator or condenser, secondary waste gas pollution, and poor effect. The present invention fills a certain amount of nitrogen in a vacuum environment, uses nitrogen to transfer heat and protect the evaporator or condenser from oxidation and cooling and degreasing, so that the system or method can reduce the degreasing temperature in a vacuum environment.

[0005] The technical solution adopted by the present invention is: A vacuum drying and degreasing system suitable for an air conditioner evaporator or condenser, characterized by comprising: A vacuum drying box, wherein a heating element is provided inside the vacuum drying box; the surface of the vacuum drying box also has a nitrogen interface and an oil and gas outlet connected to the inside of the vacuum drying box; A nitrogen supply device, wherein the output end of the nitrogen supply device is connected to the nitrogen interface of the vacuum drying box; At least two oil-gas condensing devices are connected in series; wherein the input end of the first oil-gas condensing device in the series-connected oil-gas condensing devices is connected to the oil-gas outlet; A vacuum pump is arranged on the oil and gas pipeline where at least two oil and gas condensing devices connected in series are located.

[0006] The technical solution disclosed in the present invention utilizes multi-stage condensation to efficiently recover grease under conditions of vacuum, low oxygen and nitrogen protection, has low operating costs, good degreasing effects, and can effectively avoid oxidation of the evaporator and condenser.

[0007] In one embodiment disclosed in the present application, the heating element is a device that uses infrared heating or electric heating.

[0008] In one embodiment disclosed in the present application, the output end of each of the oil-gas condensing devices is connected to an automatic oil collecting tank, or the output ends of all the oil-gas condensers are connected to an automatic oil collecting tank.

[0009] Based on the same inventive concept, the present application also discloses a vacuum drying and degreasing method. The following steps are involved: Step S10, placing the evaporator or condenser to be treated in a vacuum drying oven, and then sealing the vacuum drying oven; Step S20, start the vacuum pump to perform an evacuation operation on the vacuum drying oven, so that the vacuum degree in the vacuum drying oven is reduced to below 2000Pa (absolute pressure); then start the nitrogen supply device to fill the vacuum drying oven with a preset amount of nitrogen, and maintain the pressure in the vacuum drying oven at 10000 Pa-90000Pa (absolute pressure); finally start the heating element to heat the nitrogen and heat the evaporator or condenser to be treated, and maintain the inner wall surface temperature of the vacuum drying oven at 100°C-260°C; Step S30, cooling the gaseous volatile oil by at least two oil-gas condensing devices connected in series under the suction action of the vacuum pump to obtain liquid volatile oil.

[0010] In one embodiment disclosed in the present application, in step S20, the vacuum pump is started to perform an evacuation operation on the vacuum drying oven, further reducing the vacuum degree in the vacuum drying oven to below 1500 Pa (absolute pressure); further, the vacuum degree in the vacuum drying oven is reduced to below 900 Pa (absolute pressure).

[0011] In one embodiment disclosed in the present application, in step S20, a nitrogen supply device is started to fill a preset amount of nitrogen into the vacuum drying oven, and further, the pressure in the vacuum drying oven is maintained at 10000-80000 Pa (absolute pressure); further, the pressure in the vacuum drying oven is maintained at 40000-80000 Pa (absolute pressure).

[0012] In one embodiment disclosed in the present application, the temperature of the inner wall surface of the vacuum drying oven is maintained at 120°C-200°C.

[0013] The above method further comprises drawing an oil weight-time curve with the duration of the vacuum pump or the heating element starting to work as the abscissa and the weight of the collected volatile oil as the ordinate, and then calculating the slope of any point on the oil weight-time curve; When the slope of a certain point is less than or equal to 0.001 after the first calculation, the corresponding time is the starting point of the countdown to the end point of the vacuum drying and degreasing treatment. Continue to perform the vacuum drying and degreasing treatment for 30-120 minutes and then confirm the slope again; If the slope is still less than or equal to 0.001, and the vacuum degree in the vacuum drying oven is lower than 900Pa (absolute pressure), the vacuum drying and degreasing process is terminated; If the slope is greater than 0.001, continue the vacuum drying and degreasing process for 30-120 minutes and confirm the slope again until the slope is less than or equal to 0.001.

[0014] The vacuum drying and degreasing system and method provided by the present invention is to fill a certain amount of nitrogen in a vacuum environment, and use the nitrogen to transfer heat to heat the evaporator or condenser and cool and degrease in combination, so that the system or method can reduce the degreasing temperature in a vacuum environment, with good degreasing effect and low operating cost. At the same time, multi-stage condensation is used to efficiently recover grease, vacuum low oxygen and nitrogen protection measures, which not only improves the safety performance of the equipment, but also effectively avoids the oxidation of the evaporator or condenser. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 Schematic diagram of the connection structure of the vacuum drying and degreasing system in this embodiment 1; Figure 2 Another variation of the connection structure schematic diagram of the vacuum drying and degreasing system in this embodiment 1; Figure 3 This is a schematic flow chart of the vacuum drying and degreasing method disclosed in Example 2.

[0017] Description of reference numerals: 100-vacuum drying oven, 200-nitrogen supply device, 300-oil and gas condensing device, 400-vacuum pump, 500-oil collecting tank. DETAILED DESCRIPTION

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0019] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention.

[0020] The grease mentioned in this application refers to the volatile oil in the evaporator or condenser of the air conditioner. In this technical field, it is usually called grease. In other words, degreasing is actually deoiling. In order to comply with the industry's customary terms, the wording of degreasing is used in this application.

[0021] The embodiments of the invention are described in detail below with reference to the accompanying drawings. Example

[0022] Attached Figure 1 Schematic diagram of the connection structure of the vacuum drying and degreasing system in this embodiment. Figure 1As shown in , the vacuum drying and degreasing system includes: a vacuum drying box 100, a nitrogen supply device 200, two or more (including two) oil and gas condensing devices 300, a vacuum pump 400 and an oil collecting tank 500. Among them, the vacuum drying box 100 has a heating element, and the surface of the box body of the vacuum drying box 100 also has a nitrogen interface and an oil and gas outlet connected to the interior thereof, the output end of the nitrogen supply device 200 is connected to the nitrogen interface, and the two or more oil and gas condensing devices 300 are connected in series, wherein the input end of the first oil and gas condensing device 300 connected in series is connected to the oil and gas outlet of the vacuum drying box 100, and the end of the second oil and gas condensing device 300 connected in series is connected to the vacuum pump 400; in an actual working scenario, as a variation of the above-mentioned embodiment, see Figure 2 As shown, the vacuum pump 400 may also be disposed between two oil-gas condensing devices 300 connected in series.

[0023] Compared with traditional degreasing equipment, this embodiment is filled with a certain amount of nitrogen in a vacuum environment, and uses a combination of nitrogen heat transfer and cooling and oil removal to reduce the degreasing temperature in a vacuum environment, with good degreasing effect and low operating cost. At the same time, multi-stage condensation is used to efficiently recover grease, avoiding the situation where oil mist pollutes the environment, and improving the safety performance of the equipment to a certain extent.

[0024] The heating element in this embodiment uses infrared heating or electric heating to heat the sealed nitrogen, and then heats the evaporator or condenser. The heating method is convenient and easy to obtain, and no carbon dioxide is generated.

[0025] See also Figure 1-2 As shown, in this embodiment, the output ends of all oil-gas condensers 300 are connected to an oil collecting tank 500. In this embodiment, the volatile oil that is volatilized by heat and then cooled and separated by the oil-gas condensing device 300 is collected by the oil collecting tank 500. On the one hand, the harm to the environment caused by the random discharge of volatile oil can be reduced. At the same time, the end point of the vacuum drying and degreasing treatment can be determined by analyzing the change trend of the collected weight of the volatile oil, which is highly flexible. Under actual use conditions, the effect of using three oil-gas condensers 300 is better, and the balance between oil removal effect and energy consumption can be taken into account.

[0026] The technical solution disclosed in this embodiment has been put into use in a large air-conditioning manufacturer in Sichuan and Guangdong. Taking one of them as an example, based on the annual production scale of 4 million sets of two devices (air-conditioning condensers and / or evaporators), the vacuum drying and degreasing system in Example 1 (total electricity consumption per hour is 182.08 kWh / h) has the following technical and economic indicators compared with the treatment method of gas degreasing + RTO incineration device (gas consumption 18m³ / h, total electricity consumption per hour is 15.9 kWh): (1) Energy saving and carbon reduction Annual natural gas consumption of gas degreasing + RTO incineration device: 18m³ / h×12h×330 days+36m³ / h×12h×330 days=213840m³, Equivalent to 263.02 tons of standard coal. The conversion factor is: 1m³ natural gas corresponds to 1.23kg standard coal.

[0027] Annual power consumption of gas degreasing + RTO incineration device: 15.9kWh / h×12h×330 days+93.5kWh×12h×330 days=433224 degrees, Equivalent to 138.63 tons of standard coal. The conversion factor is: 1 kWh corresponds to 0.32 kg of standard coal.

[0028] In summary, the gas degreasing + RTO incineration device consumes 401.65 tons of standard coal annually.

[0029] Annual power consumption of vacuum drying and degreasing device: 182.08kWh / h×12h×330 days=721036.8 degrees, Equivalent to 230.73 tons of standard coal. The conversion factor is: 1 kWh corresponds to 0.32 kg of standard coal.

[0030] According to the above calculation, the energy consumption ratio of vacuum drying degreasing device compared with gas degreasing + RTO incineration device is: 230.73 / 401.65=57.45%, Reduce energy consumption by 42.55%.

[0031] Reduce carbon emissions every year: (401.65-230.73)×2.46+0.19 tons / day (VOCs recovery amount)×3.7 tons (CO2)×330 days=652.46 tons of CO2.

[0032] Among them, saving 1 ton of standard coal is equivalent to reducing CO2 emissions by 2.46 tons; removing 1 ton of VOCs, the amount of carbon dioxide produced in the combustion process is 3.7 tons of CO2.

[0033] (2) Pollution reduction and recycling Non-methane total hydrocarbons (VOCs) emission indicators: The hourly emission of non-methane total hydrocarbons (VOCs) in the vacuum drying and degreasing process based on the vacuum drying and degreasing system (800 pieces / hour) is: Q2=8.07mg / m 3 ×534m3 / h×2=4309.38mg / h.

[0034] Converted to 1000 pieces / hour, the emission volume is: 4309.38mg / h×(1000 / 800)=5386.725mg / h.

[0035] The hourly emission of non-methane total hydrocarbons (VOCs) in the conventional degreasing process (1000 pieces / hour) is: Q1=16.3mg / m 3 ×37019m 3 / h=603409.7mg / h, Q2÷Q1=5386.725÷603409.7=0.89%.

[0036] According to the above calculation results, the vacuum drying degreasing process replaces the traditional degreasing process and can significantly reduce waste gas emissions through condensation recovery. The emission volume is less than 1% of conventional degreasing equipment, reducing air pollution and being beneficial to environmental protection. At the same time, more than 95% of the oil can be recovered.

[0037] (3) Equipment investment costs

[0038] (4) Comparison of equipment operating costs

[0039] From the above, it can be seen that the vacuum drying and degreasing system disclosed in the present invention has significant advantages in terms of energy consumption, emissions, and equipment operation. According to feedback from air conditioner manufacturers, the oil recovery rate of this system is over 95%. Example

[0040] Figure 2 The figure is a flow chart of the vacuum drying and degreasing method disclosed in the present invention. The method and the system in Example 1 belong to the same inventive concept. Specifically, the vacuum drying and degreasing method is implemented based on the vacuum drying and degreasing system in Example 1, and specifically includes the following steps: Step S10, placing the evaporator or condenser to be treated in a vacuum drying oven, and then sealing the vacuum drying oven; Step S20, start the vacuum pump to perform air extraction operation on the vacuum drying oven, so that the vacuum degree in the vacuum drying oven is reduced to below 2000Pa (absolute pressure); then start the nitrogen supply device to fill the vacuum drying oven with a preset amount of nitrogen, and maintain the pressure in the vacuum drying oven at 10000-90000Pa (absolute pressure); finally start the heating element to heat the nitrogen and heat the evaporator or condenser to be treated, and maintain the inner wall surface temperature of the vacuum drying oven at 100°C-260°C; Step S30, cooling the gaseous volatile oil by at least two oil-gas condensing devices connected in series under the suction action of the vacuum pump to obtain liquid volatile oil.

[0041] In this embodiment, the duration of the vacuum pump or the heating element starting to work is used as the horizontal coordinate, and the weight of the collected volatile oil is used as the vertical coordinate to draw the oil weight-time curve, and then calculate the slope of any point on the oil weight-time curve; when the slope of a certain point is less than or equal to 0.001 for the first time, the corresponding time is the starting point of the countdown to the end of the vacuum drying and degreasing treatment, and the vacuum drying and degreasing treatment is continued for 30 to 120 minutes and the slope is confirmed again; if the slope is still less than or equal to 0.001 and the vacuum degree in the vacuum drying box is lower than 900Pa (absolute pressure), the vacuum drying and degreasing treatment is terminated; if the slope is greater than 0.001, the vacuum drying and degreasing treatment is continued for 30 to 120 minutes and the slope is confirmed again until the slope is less than or equal to 0.001. The slope of the oil weight-time curve in this embodiment represents the trend of the change amount of volatile oils. The change amount of volatile oils is large in the early stage of the treatment, and the change amount of volatile oils is small in the later stage of the treatment. When the change in volatile oil approaches 0, it indicates that the stamping volatile oil attached to the evaporator or condenser has been almost removed, which also represents the end point of the vacuum drying and degreasing process. In this embodiment, by observing the slope of the oil weight-time curve, the vacuum drying and degreasing process can be flexibly controlled.

[0042] Under actual use conditions, the inventor used an infrared spectrophotometer of model SYT700 to test the use environment. Combined with the actual measured data, the parameter range of the technical solution can be further optimized as follows: When the vacuum degree in the vacuum drying oven is reduced to below 1500Pa (absolute pressure), the degreasing effect will be further optimized, especially when the vacuum degree in the vacuum drying oven is reduced to below 900Pa (absolute pressure), the degreasing effect and energy consumption will reach a balanced state that takes each other into consideration.

[0043] Keep the pressure and temperature in the vacuum drying box unchanged, and simply change the vacuum value of the vacuum drying box. The test results are as follows: (a) When the vacuum degree in the vacuum drying oven is reduced to 2000Pa, the data measured by the infrared spectrophotometer is: 48mg / m 2 ; (b) When the vacuum degree in the vacuum drying oven is reduced to 1500Pa, the data measured by the infrared spectrophotometer is: 30mg / m 2 ; (c) When the vacuum degree in the vacuum drying oven is reduced to 900Pa, the data measured by the infrared spectrophotometer is: 20mg / m 2 .

[0044] Keep the vacuum degree and temperature in the vacuum drying box unchanged, and simply change the pressure value of the vacuum drying box. The test results are as follows: (d) When the vacuum drying oven pressure is maintained at 10000-80000Pa (absolute pressure), the infrared spectrophotometer measures the oil content to be 46mg / m 2 ; (e) When the vacuum drying oven pressure is maintained at 40000-80000Pa (absolute pressure), the infrared spectrophotometer measured the value of 31mg / m 2 .

[0045] Keep the pressure and vacuum degree in the vacuum drying oven unchanged, and simply change the temperature value of the vacuum drying oven. The test results are as follows: (f) When the inner wall temperature of the vacuum drying oven is between 100℃ and 260℃, the value measured by the infrared spectrophotometer is 33mg / m 2 ; (g) When the inner wall temperature of the vacuum drying oven is 120℃-200℃, the value measured by the infrared spectrophotometer is 21mg / m 2 .

[0046] When the pressure, vacuum degree and temperature of the vacuum drying box are kept linked, the degreasing effect is better under the following conditions after testing.

[0047]

[0048] It can be seen that in this embodiment, a certain amount of nitrogen is filled in a vacuum environment, and the heat transfer and cooling degreasing of nitrogen are combined, which can not only reduce the degreasing temperature in a vacuum environment, achieve good degreasing effect, reduce consumption and reduce operating costs; but also effectively avoid oxidation of the evaporator or condenser. This embodiment uses multi-stage condensation to efficiently recover grease, improves the safety performance of the equipment, and has significant economic benefits compared to traditional degreasing equipment and methods.

Claims

1. A vacuum drying and degreasing system suitable for air-conditioning evaporator or condenser, characterized in that: include: A vacuum drying box, wherein a heating element is provided in the vacuum drying box, and a nitrogen interface and an oil and gas outlet are provided on the surface of the vacuum drying box which are connected to the interior of the vacuum drying box; A nitrogen supply device, wherein the output end of the nitrogen supply device is connected to the nitrogen interface of the vacuum drying box; At least two oil-gas condensing devices are connected in series; wherein the input end of the first oil-gas condensing device in the series-connected oil-gas condensing devices is connected to the oil-gas outlet; A vacuum pump is arranged on the oil and gas pipeline where at least two oil and gas condensing devices connected in series are located.

2. The vacuum drying and degreasing system according to claim 1, characterized in that: The heating element is a device that uses infrared heating or electric heating.

3. The vacuum drying and degreasing system according to claim 1, characterized in that: The output end of each of the oil-gas condensing devices is connected to an automatic oil collecting tank, or the output ends of all the oil-gas condensers are connected to an automatic oil collecting tank.

4. A vacuum drying and degreasing method, implemented by the vacuum drying and degreasing system according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S10, placing the evaporator or condenser to be treated in a vacuum drying oven, and then sealing the vacuum drying oven; Step S20, start the vacuum pump to perform an evacuation operation on the vacuum drying oven, so that the vacuum degree in the vacuum drying oven is reduced to below 2000Pa (absolute pressure); then start the nitrogen supply device to fill the vacuum drying oven with a preset amount of nitrogen, and maintain the pressure in the vacuum drying oven at 10000-90000Pa (absolute pressure); finally start the heating element to heat the nitrogen and heat the evaporator or condenser to be processed, and maintain the inner wall surface temperature of the vacuum drying oven at 100°C-260°C; Step S30, cooling the gaseous volatile oil by at least two oil-gas condensing devices connected in series under the suction action of the vacuum pump to obtain liquid volatile oil.

5. The vacuum drying and degreasing method according to claim 4, characterized in that: In step S20, the vacuum pump is started to evacuate the vacuum drying box, so that the vacuum degree in the vacuum drying box is further reduced to below 1500 Pa (absolute pressure).

6. The vacuum drying and degreasing method according to claim 5, characterized in that: The vacuum degree in the vacuum drying box is further reduced to below 900 Pa (absolute pressure).

7. The vacuum drying and degreasing method according to claim 4, characterized in that: In step S20, the nitrogen supply device is started to fill the vacuum drying oven with a preset amount of nitrogen. Further, the pressure in the vacuum drying oven is maintained at 10000-80000 Pa (absolute pressure).

8. The vacuum drying and degreasing method according to claim 7, characterized in that: Furthermore, the pressure in the vacuum drying oven is maintained at 40000-80000 Pa (absolute pressure).

9. The vacuum drying and degreasing method according to claim 4, characterized in that: Furthermore, the inner wall surface temperature of the vacuum drying box is maintained at 120°C-200°C.

10. The vacuum drying and degreasing method according to claim 4, characterized in that: The oil weight-time curve is drawn with the duration of the vacuum pump or the heating element starting to work as the horizontal coordinate and the weight of the collected volatile oil as the vertical coordinate, and then the slope of any point on the oil weight-time curve is calculated; When the slope of a certain point is less than or equal to 0.001 after the first calculation, the corresponding time is the starting point of the countdown to the end point of the vacuum drying and degreasing treatment. Continue to perform the vacuum drying and degreasing treatment for 30-120 minutes and then confirm the slope again; If the slope is still less than or equal to 0.001 and the vacuum degree is lower than 900Pa (absolute pressure), the vacuum drying and degreasing process is terminated; If the slope is greater than 0.001, continue the vacuum drying and degreasing process for 30-120 minutes and confirm the slope again until the slope is less than or equal to 0.001.

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