Powder coating waste heat recovery device and method

Abstract

The present invention provides a powder coating waste heat recovery device, which at least includes: a curing furnace, an evaporation box, a preheating box and a first steam-water separator. Among them, the curing furnace is used to bake and cure powder coating. The evaporation box is connected to the curing furnace through a second pipe equipped with a second solenoid valve, and the internal structure is a superheater and an evaporator in sequence. Its main function is to use the waste heat generated by the curing furnace to drive the superheater and evaporator to work and convert the waste heat into steam. The preheating box is connected to the curing furnace through a first pipe, and a first solenoid valve is provided on the first pipe. The preheating box is connected to the evaporation box through a third pipe, and a third solenoid valve is provided on the third pipe. A heat exchanger is provided in the preheating box, and a water supply pipe is connected to one end of the heat exchanger.

Description

Technical Field

[0001] The present invention relates to the technical field of powder coating waste heat recovery, and in particular to a powder coating waste heat recovery device and method. Background Art

[0002] Powder coating is a surface treatment technology that uses powder coatings to apply a coating to the surface of a workpiece via spraying. This coating method is widely used in various fields, such as automobiles, home appliances, and construction. Powder coatings primarily consist of resins, pigments, fillers, and additives, all in a dry powder form. During the coating process, the powder coating is evenly applied to the workpiece surface through electrostatic spraying, fluidized bed dipping, or electrostatic fluidized bed dipping. The coating then undergoes preheating and curing to form a continuous, dense film.

[0003] During the powder coating curing process, the treated workpiece is first dried and then placed in a stainless steel mesh belt curing oven for baking and curing. The curing process is divided into two stages. The first is the preheating stage, during which the workpiece absorbs heat and gradually heats up to a temperature range of 60-80°C. The temperature rise during this stage is slow, allowing the workpiece to gradually heat up and evaporate moisture from the coating to prevent blistering. The second stage is the high-temperature curing stage, during which the curing oven temperature must be strictly controlled within the required range, neither too high nor too low. The high-temperature curing of the workpiece in the curing oven generates a large amount of waste heat, which is wasted if directly discharged. Furthermore, at temperatures above 150°C, the curing process on the powder coating line produces a certain amount of volatile organic compounds and cracking products, which, if discharged directly, can pollute the environment. Therefore, it is necessary to optimize the curing oven's emissions to reduce environmental pollution and fully utilize the waste heat. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the present invention aims to provide a powder coating waste heat recovery device and method to address the problem that, during the curing process in a powder coating curing furnace, a large amount of waste heat is generated during the high-temperature curing of the workpiece, and direct discharge of this heat results in energy waste. Furthermore, at temperatures above 150°C, the coating curing process on the powder coating production line generates a certain amount of organic volatiles and pyrolysis products, which, if directly discharged, can pollute the environment.

[0005] In order to achieve the above-mentioned and other related purposes, the present invention provides a powder coating waste heat recovery device and method

[0006] At least includes: a curing furnace, an evaporation box, a preheating box and a first steam-water separator;

[0007] The curing oven is used to bake and cure the powder coating;

[0008] The evaporation box is connected to the curing furnace through a second pipe, the second pipe is provided with a second solenoid valve, and the evaporation box is provided with a superheater and an evaporator in sequence;

[0009] The preheating box is connected to the curing furnace through a first pipe, the first pipe is provided with a first solenoid valve, the preheating box is connected to the evaporation box through a third pipe, the third pipe is provided with a third solenoid valve, a heat exchanger is provided in the preheating box, and one end of the heat exchanger is connected to a water supply pipe;

[0010] The air inlet of the first steam-water separator is connected to the evaporator through a wet steam pipe, and the air outlet of the first steam-water separator is connected to the superheater through a dry steam pipe. A saturated water tank is provided in the first steam-water separator, and the saturated water tank is connected to the heat exchanger through a water inlet pipe. A first circulating pump is provided on the water inlet pipe. The saturated water tank is also connected to the evaporator through a downcomer, and a second circulating pump and a fourth solenoid valve are provided on the downcomer.

[0011] Preferably, one end of the preheating box is connected to a purification box, and the purification box includes: a flushing chamber, a steam-water separation chamber and a filtering chamber;

[0012] The flushing chamber is used to flush out the organic waste gas volatilized during the powder solidification process;

[0013] The steam-water separation chamber is used to separate the water in the flushed gas;

[0014] The filter chamber is used to filter the residual organic volatiles and fission products in the gas.

[0015] Preferably, a spray assembly is provided on the top of the purification box and a sewage outlet is provided at the bottom; a second steam-water separator and a wire mesh demister are provided in the steam-water separation chamber, a drain outlet is provided at the bottom and an exhaust outlet is provided at the top of the steam-water separation chamber; an activated carbon adsorption layer is provided in the filter chamber.

[0016] Preferably, a flow regulating valve is provided on the water inlet pipe, and a first temperature sensor and a second temperature sensor are provided on the first pipe and the second pipe respectively.

[0017] Preferably,

[0018] In the first step, during the preheating stage of the powder coating curing process, the first solenoid valve is opened, the second solenoid valve is closed, and the third and fourth solenoid valves are closed at the same time to introduce the gas in the curing furnace into the preheating box;

[0019] The second step is to start the first circulation pump to pass water into the heat exchanger for heat exchange, adjust the flow rate through the flow control valve, and finally introduce the heat-exchanged water into the saturated water tank;

[0020] Step 3: When the powder coating curing process reaches the high-temperature curing stage, open the second solenoid valve and close the first solenoid valve to guide the gas in the curing furnace into the evaporation box;

[0021] Step 4: Start the second circulation pump and open the third solenoid valve and the fourth solenoid valve at the same time to let the water in the saturated water tank flow into the evaporator and the gas in the evaporation box flow into the preheating box;

[0022] Step 5: Open the spray assembly to flush the gas into the flushing chamber.

[0023] As described above, the powder coating waste heat recovery device and method of the present invention have the following beneficial effects:

[0024] During the preheating phase of the powder coating curing process, the gases generated within the curing furnace are directly directed into the preheating tank. The preheating tank recovers the heat from the relatively low-temperature gases discharged from the curing furnace and stores it in a saturated water tank, effectively collecting the waste heat from the gases. During the high-temperature curing phase, this device directs the high-temperature gases discharged from the curing furnace into the evaporation tank, where they exchange heat with saturated water in the evaporator. The saturated water forms wet steam, which flows into the first steam-water separator for dehydration. Finally, the dehydrated gases flow into the superheater, where they are reheated by the high-temperature gases to form high-temperature steam. This high-temperature steam has a high thermal energy content and can be used for power generation or heating. This method not only improves energy efficiency but also reduces production costs, fully embracing the principles of energy conservation and environmental protection. Furthermore, the utility model utilizes a purification tank to effectively purify the volatile organic compounds and pyrolysis products generated during the coating curing process on the powder coating production line. This not only reduces the negative environmental impact of the production process but also aligns with current societal initiatives for green environmental protection and energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0026] Component number description

[0027] 1 Curing oven

[0028] 2 Evaporator

[0029] 3 Preheating box

[0030] 4. First steam-water separator

[0031] 5 Purification Box

[0032] 11 First Pipeline

[0033] 12 Second Pipeline

[0034] 21 Superheater

[0035] 22 Evaporator

[0036] 23 Third Pipeline

[0037] 31 Water supply pipe

[0038] 32 heat exchanger

[0039] 41 Water inlet pipe

[0040] 42 Downcomer

[0041] 43 Wet Steam Pipe

[0042] 44 Dry Steam Pipe

[0043] 45 Saturated water tank

[0044] 51 Flushing Chamber

[0045] 52 Soda-water separation tank

[0046] 53 filter chamber

[0047] 111 First solenoid valve

[0048] 112 First temperature sensor

[0049] 121 Second solenoid valve

[0050] 122 Second temperature sensor

[0051] 231 Third solenoid valve

[0052] 411 Flow Control Valve

[0053] 412 First circulation pump

[0054] 421 Second circulation pump

[0055] 422 Fourth solenoid valve

[0056] 511 Spray

[0057] 512 sewage outlet

[0058] 521 Second steam-water separator

[0059] 522 Drain

[0060] 523 Wire Mesh Demister

[0061] 524 exhaust port DETAILED DESCRIPTION

[0062] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0063] See also Figure 1 . It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0064] like Figure 1 As shown, the present invention provides a powder coating waste heat recovery device and method, which at least includes: a curing furnace 1, an evaporation box 2, a preheating box 3 and a first steam-water separator 4. Among them, the curing furnace 1 is used for baking and curing powder coating. The evaporation box 2 is connected to the curing furnace 1 through a second pipe 12 equipped with a second solenoid valve 121, and its internal structure is a superheater 21 and an evaporator 22 in sequence. Its main function is to use the waste heat generated by the curing furnace 1 to drive the superheater 21 and the evaporator 22 to work and convert the waste heat into steam. The preheating box 3 is connected to the curing furnace 1 through a first pipe 11, and a first solenoid valve 111 is provided on the first pipe 11. The preheating box 3 is connected to the evaporation box 2 through a third pipe 23, and a third solenoid valve 231 is provided on the third pipe 23. A heat exchanger 32 is provided in the preheating box 3, and one end of the heat exchanger 32 is connected to a water supply pipe 31. The air inlet of the first steam-water separator 4 is connected to the evaporator 22 through the wet steam pipe 43, and the air outlet of the first steam-water separator 4 is connected to the superheater 21 through the dry steam pipe 44. A saturated water tank 45 is provided in the first steam-water separator 4, and the saturated water tank 45 is connected to the heat exchanger 32 through the water inlet pipe 41. The water inlet pipe 41 is provided with a first circulating pump 412. The saturated water tank 45 is also connected to the evaporator 22 through the downcomer 42, and the downcomer 42 is provided with a second circulating pump 421 and a fourth solenoid valve 422.

[0065] In this device, during the preheating stage of the powder coating curing process, the gas generated in the curing furnace 1 can be directly introduced into the preheating tank 3. Through the first circulation pump 412, water begins to circulate and enters the heat exchanger 32 in the preheating tank 3 for heat exchange. After the heat exchange, the temperature of the water increases and is then introduced into the saturated water tank 45 of the steam-water separator. The main purpose of this process is to use the heat exchanger 32 in the preheating tank 3 to recover the heat from the relatively low-temperature gas discharged from the curing furnace 1. Through heat exchange, this heat that might otherwise be wasted is transferred to the water, causing the water temperature to increase. Subsequently, this heat is stored in the saturated water tank 45, thereby achieving effective collection of the waste heat of the gas. This method not only improves the efficiency of energy use, but also reduces production costs, fully responding to the concept of energy conservation and environmental protection. During the high-temperature curing stage, the high-temperature gases exhausted from the curing furnace 1 can be directed directly into the evaporator 2. There, the high-temperature gases exchange heat with the saturated water in the evaporator 22. The resulting saturated water forms wet steam, which flows into the first steam-water separator 4 for dehydration. The dehydrated gases then flow into the superheater 21, where they are reheated by the high-temperature gases to form high-temperature steam. This high-temperature steam possesses high thermal energy and can be used for power generation or heating, thus achieving efficient energy utilization. Simultaneously, the temperature of the high-temperature gases gradually decreases after passing through the superheater 21 and evaporator 22, and they are then directed into the preheater 3. Within the preheater 3, these gases undergo further heat exchange with the water in the heat exchanger 32, raising the water's temperature. This allows the water in the preheater 3 to continuously absorb and store waste heat from the curing furnace 1, achieving thermal energy recycling.

[0066] During the high-temperature baking stage of powder coating curing, the coating curing process on the powder coating production line produces a certain amount of organic volatiles and cracking products. If directly discharged, they will pollute the environment. To purify the organic volatiles and cracking products in the gas, in one embodiment, a purification box 5 is connected to one end of the preheating box 3. The purification box 5 includes: a flushing chamber 51, a steam-water separation chamber 52, and a filtration chamber 53;

[0067] The flushing chamber 51 is used to flush and separate organic waste gases volatilized during the powder curing process. The steam-water separator 52 is used to separate water from the gas. The filter chamber 53 is used to filter residual organic volatiles and fission products in the gas. Specifically, the purification box 5 is equipped with a spray 511 at the top and a drain outlet 512 at the bottom. The steam-water separator is equipped with a wire mesh demister 523, a drain outlet 522 at the bottom, and an exhaust outlet 524 at the top. The filter chamber 53 is equipped with an activated carbon adsorption layer.

[0068] In one embodiment, a flow control valve 411 is provided on the water inlet pipe 41, and a first temperature sensor 112 and a second temperature sensor 122 are provided on the first pipe 11 and the second pipe 12, respectively. Adjusting the flow control valve 411 controls the heat exchange efficiency. The first temperature sensor 112 and the second temperature sensor 122 monitor the temperature of the gas flowing into the evaporator 2 and the preheater 3.

[0069] Working process:

[0070] Preheating Phase: During this process, the preheating temperature is approximately 60-80°C, which is used to evaporate moisture from the coating. To achieve gas purification and waste heat collection, first, close the second solenoid valve 121, open the first solenoid valve 111, and simultaneously close the third solenoid valve 231 and the fourth solenoid valve 422. This allows the medium-temperature gas within the curing oven 1 to enter the preheating tank 3 through the second channel. The first circulation pump 412 is activated, and water flows through the water supply pipe 31 into the heat exchanger 32 for heat exchange with the medium-temperature gas within the preheating tank 3. The saturated water after heat exchange flows through the water inlet pipe 41 into the saturated water tank 45. During this process, the water flow rate is controlled by controlling the flow control valve 411 to ensure sufficient heat exchange and that the saturated water in the heat storage tank does not exceed 1 / 2 of its volume at the end of the preheating process. The gas after heat exchange continues to flow into the purification tank 5. Because the temperature is relatively low during the preheating process, no organic volatiles or pyrolysis products are generated during the coating preheating process on the powder coating line, so the spray system 511 does not need to be activated. The steam containing water enters the steam-water separator and is dehydrated by the wire mesh demister 523 and the second steam-water separator 521. Finally, the dry gas finally enters the filter chamber 53 and is filtered by the activated carbon filter layer before being discharged.

[0071] High-temperature curing stage: After preheating, the coating requires high-temperature curing. During this process, the first solenoid valve 111 is first closed, and the second and third solenoid valves 121 and 231 are opened. At this point, the high-temperature gas within the curing furnace 1 enters the evaporation tank 2 through the first channel. The second circulation pump 421 and fourth solenoid valve 422 are activated, and saturated water in the saturated water tank 45 flows through the downcomer 42 into the evaporator 22. The wet steam generated after heat exchange enters the first steam-water separator 4 for dehydration. The dehydrated dry steam then flows through a pipeline into the superheater 21, forming high-temperature steam. This high-temperature steam can be used for power generation and heat supply. During this process, the high-temperature gas within the curing furnace 1 enters the evaporation tank and exchanges heat with the evaporator 22 in the superheater 21. The heat-exchanged gas then flows into the preheating tank, where it continues to exchange heat with the heat exchanger 32, continuously providing saturated water to the circulation loop. During this process, a certain amount of water is stored in the saturated water tank 45, providing a certain amount of heat and water. This helps slow down steam pressure fluctuations during operating conditions and provides a buffering effect when water supply and load are temporarily out of sync. After exchanging heat with heat exchanger 32, the gas flows into the purification chamber. At this point, spray 511 is turned on to flush the gas, allowing the organic waste gas volatilized during the powder curing process to be flushed and precipitated and discharged through drain port 512. The moist gas flows into the second steam-water separator 521, where it is dehydrated to form dry gas. The dry gas ultimately enters filter chamber 53, where it is filtered through the activated carbon filter layer before being discharged.

[0072] In summary, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0073] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A powder coating waste heat recovery device, characterized in that: At least: Curing furnace, evaporation box, preheating box and first steam-water separator; The curing oven is used to bake and cure the powder coating; The evaporation box is connected to the curing furnace through a second pipe, the second pipe is provided with a second solenoid valve, and the evaporation box is provided with a superheater and an evaporator in sequence; The preheating box is connected to the curing furnace through a first pipe, the first pipe is provided with a first solenoid valve, the preheating box is connected to the evaporation box through a third pipe, the third pipe is provided with a third solenoid valve, a heat exchanger is provided in the preheating box, and one end of the heat exchanger is connected to a water supply pipe; The air inlet of the first steam-water separator is connected to the evaporator through a wet steam pipe, and the air outlet of the first steam-water separator is connected to the superheater through a dry steam pipe. A saturated water tank is provided in the first steam-water separator, and the saturated water tank is connected to the heat exchanger through a water inlet pipe. A first circulating pump is provided on the water inlet pipe. The saturated water tank is also connected to the evaporator through a downcomer, and a second circulating pump and a fourth solenoid valve are provided on the downcomer.

2. The powder coating waste heat recovery device according to claim 1, characterized in that: One end of the preheating box is connected to a purification box, which includes: a flushing chamber, a steam-water separation chamber and a filtering chamber; The flushing chamber is used to flush out the organic waste gas volatilized during the powder solidification process; The steam-water separation chamber is used to separate the water in the flushed gas; The filter chamber is used to filter the residual organic volatiles and fission products in the gas.

3. The powder coating waste heat recovery device according to claim 2, characterized in that: The purification box is provided with a spray assembly on the top and a sewage outlet at the bottom; the steam-water separation chamber is provided with a second steam-water separator and a wire mesh demister, the steam-water separation chamber is provided with a drain outlet at the bottom and an exhaust outlet at the top; the filter chamber is provided with an activated carbon adsorption layer.

4. The powder coating waste heat recovery device according to claim 1, characterized in that: The water inlet pipe is provided with a flow regulating valve, and the first pipe and the second pipe are respectively provided with a first temperature sensor and a second temperature sensor.

5. A method for recovering waste heat from powder coating, comprising the following steps: In the first step, during the preheating stage of the powder coating curing process, the first solenoid valve is opened, the second solenoid valve is closed, and the third and fourth solenoid valves are closed at the same time to introduce the gas in the curing furnace into the preheating box; The second step is to start the first circulation pump to pass water into the heat exchanger for heat exchange, adjust the flow rate through the flow control valve, and finally introduce the heat-exchanged water into the saturated water tank; Step 3: When the powder coating curing process reaches the high-temperature curing stage, open the second solenoid valve and close the first solenoid valve to guide the gas in the curing furnace into the evaporation box; Step 4: Start the second circulation pump and open the third and fourth solenoid valves at the same time to let the water in the saturated water tank flow into the evaporator and the gas in the evaporation box flow into the preheating box; Step 5: Open the spray assembly to flush the gas into the flushing chamber.

Images