Coating recovery integrated system

Abstract

The application relates to a coating and recycling integrated system, which comprises a coating machine and a recycling system arranged on the coating machine, the recycling system comprises a gas-gas heat exchanger, a gas-cooling heat exchanger and a gas-heating heat exchanger, the coating machine comprises a coating machine oven, and a fresh air inlet for external fresh air is arranged on the coating machine oven; the coating machine oven is communicated with the gas-gas heat exchanger, the gas-gas heat exchanger is communicated with the gas-cooling heat exchanger, the gas-cooling heat exchanger is communicated with the outside, and the gas-cooling heat exchanger is communicated with the gas-gas heat exchanger through a return air pipe, and the circulation is an external circulation operation line; the coating machine oven is closed-loop communicated with the gas-heating heat exchanger, forming an internal circulation operation line; the gas-gas heat exchanger is communicated with the gas-heating heat exchanger and the internal circulation operation line; the system in the application reduces the installation space of a factory building, shortens the length of the air pipe, reduces the heat dissipation area of the air pipe, saves heating energy consumption, and is closed-loop operation, does not need to additionally add chilled water and refrigerant, and saves cost and process.

Description

Technical Field

[0001] This application relates to the field of coating machine technology, and in particular to an integrated coating and recycling system. Background Technology

[0002] In traditional processes, heat exchangers are used for waste gas treatment to recover NMP solvent. Waste gas from the coating machine passes through a heat exchanger to exchange heat with the low-temperature gas returning to the coating machine, thus lowering the waste gas temperature. Then, chilled water is used to further reduce the waste gas temperature, lowering the NMP concentration in the gas to below 300 ppm. After this, the waste gas re-enters the heat exchanger to exchange heat with the coating machine's exhaust gas, recovering heat from the waste gas. However, this traditional process has some problems.

[0003] First, NMP recovery equipment is bulky and typically needs to be placed far from the coating machine, requiring the use of large and long ducts to connect the two. This not only occupies a significant amount of factory space but also places high demands on the design of the factory and NMP recovery system, resulting in high equipment investment costs. Furthermore, chilled water is required to further cool the wastewater (e.g., Figure 2 As shown in the figure, this reduces the energy utilization efficiency of the recycling process and increases the cost of use. Summary of the Invention

[0004] Based on this, it is necessary to provide an integrated coating and recycling system, including a coating machine and a recycling system installed on the coating machine. The recycling system includes a gas-to-gas heat exchanger, a gas-cooled heat exchanger, and a gas-heat heat exchanger. The coating machine includes a coating machine oven, and the coating machine oven is provided with a fresh air inlet for external fresh air to enter.

[0005] The coating machine oven is connected to the gas-to-gas heat exchanger, the gas-to-gas heat exchanger is connected to the air-cooled heat exchanger, the air-cooled heat exchanger is connected to the outside and is connected to the gas-to-gas heat exchanger through a return air pipe. This cycle is an external circulation operation circuit.

[0006] The coating machine oven is connected in a closed loop with the gas heat exchanger to form an internal circulation circuit.

[0007] The gas-to-gas heat exchanger is connected to the gas-heat exchanger and is connected to the internal circulation circuit.

[0008] The recovery system also includes a primary circulating evaporator, which is connected to the air-cooled heat exchanger to form a closed loop, creating a cold pipe circulation.

[0009] The recovery system also includes a secondary circulating condenser, which is connected to the gas heat exchanger to form a closed loop, forming a heat pipe circulation.

[0010] The recovery system includes a primary circulating compressor, an evaporator-condenser, and a primary expansion valve. The primary circulating evaporator, the primary circulating compressor, the evaporator-condenser, and the primary expansion valve are connected in sequence to form a closed loop, which is a primary circulating compression circuit.

[0011] The recovery system includes a two-stage circulating condenser, a two-stage circulating compressor, and a two-stage expansion valve. The two-stage circulating condenser, the two-stage expansion valve, the evaporator-condenser, and the two-stage circulating compressor are connected in sequence to form a closed loop, which is a two-stage circulating compression circuit.

[0012] Of the gas passing through the gas-cooled heat exchanger, 5% to 10% is discharged, and the remaining gas is returned to the gas-to-gas heat exchanger.

[0013] The coating machine includes multiple coating machine ovens, and each of the coating machine ovens is equipped with a recycling system.

[0014] The amount of fresh air entering the coating machine oven corresponds to the amount of exhaust gas discharged.

[0015] Compared with the prior art, the advantages of the present invention are as follows:

[0016] The coating and recycling integrated system provided by this invention allows fresh air to enter the coating machine oven through a fresh air inlet. After being heated together with the gas inside the oven, the air splits into two streams. One stream, waste gas, enters the external circulation path and undergoes primary cooling via an air-to-air heat exchanger. The other stream, internal circulation gas, enters the internal circulation path, is heated via an air-to-heat exchanger, and returns to the coating machine oven to assist in the drying process. The gas passing through the air-to-air heat exchanger splits into two parts: one part flows along the external circulation path into an air-cooled heat exchanger for secondary cooling, while the other part enters the air-to-heat exchanger and mixes with the gas in the internal circulation path, thus increasing the temperature. This invention achieves energy recycling. The exhaust gas passing through the air-cooled heat exchanger is also divided into two parts: one part is discharged externally, and the other part is returned to the air-to-air heat exchanger to exchange heat with the exhaust gas entering the air-to-air heat exchanger from the coating machine, thus completing the step-by-step cooling and recovery of temperature. Because the invention integrates the recovery system with the coating machine, the system control during production is more coordinated and convenient, and it is also easier to maintain in the future. Compared with the existing coating and recovery separate systems, the system in this invention reduces the factory installation space and shortens the length of the air duct, reducing the heat dissipation area of ​​the air duct, thereby saving heating energy. Moreover, this invention operates in a closed loop and does not require the addition of additional chilled water and refrigerant, saving costs and processes. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the working process of the coating and recycling integrated system according to an embodiment of this application;

[0019] Figure 2 This is a schematic diagram of the workflow of a separate coating machine and recycling equipment in the existing technology.

[0020] Explanation of reference numerals in the attached figures:

[0021] 1. Coating machine oven; 2. Gas-to-gas heat exchanger; 3. Gas-cooled heat exchanger; 4. Primary circulating evaporator; 5. Auxiliary heating; 6. Gas-heat exchanger; 7. Primary circulating compressor; 8. Evaporator condenser; 9. Primary expansion valve; 10. Secondary expansion valve; 11. Secondary circulating compressor; 12. Secondary circulating condenser. Detailed Implementation

[0022] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0023] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0025] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0026] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0027] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0028] The coating and recycling integrated system includes a coating machine and a recycling system installed on the coating machine. The recycling system includes an air-to-air heat exchanger 2, an air-cooled heat exchanger 3, and an air-heated heat exchanger 6. The coating machine includes a coating machine oven 1, which is provided with a fresh air inlet for external fresh air to enter.

[0029] The coating machine oven 1 is connected to the air-to-air heat exchanger 2, the air-to-air heat exchanger 2 is connected to the air-cooled heat exchanger 3, the air-cooled heat exchanger 3 is connected to the outside and is connected to the air-to-air heat exchanger 2 through the return air pipe. This cycle is the external circulation operation circuit.

[0030] The coating machine oven 1 is connected in a closed loop with the air-heat exchanger 6 to form an internal circulation circuit.

[0031] Gas-to-gas heat exchanger 2 is connected to gas-to-heat heat exchanger 6, and is connected to the internal circulation circuit.

[0032] The gas-to-gas heat exchanger 2 is used for the initial heat exchange between the coating exhaust air and the coating return air; the air-cooled heat exchanger 3 further cools the exhaust gas and further reduces the exhaust concentration, while transferring the heat to the primary circulating evaporator 4.

[0033] This integrated coating and recovery system allows fresh air to enter the coating machine's drying oven 1 through the fresh air inlet. After being heated together with the gas inside the oven 1, the air splits into two streams. One stream, waste gas, enters the external circulation path and undergoes primary cooling via the gas-to-gas heat exchanger 2. The other stream, internal circulation gas, enters the internal circulation path, is heated via the gas-heat exchanger 6, and returns to the coating machine's drying oven 1 to assist in the drying process. The waste gas passing through the gas-to-gas heat exchanger 2 is split into two parts. One part flows along the external circulation path into the air-cooled heat exchanger 3 for secondary cooling, while the other part enters the gas-heat exchanger 6 to mix with the gas in the internal circulation path, thus increasing the temperature and realizing energy recovery. The waste gas is recycled; the waste gas passing through the air-cooled heat exchanger 3 is also divided into two parts, one part is discharged externally, and the other part is returned to the air-to-air heat exchanger 2. The waste gas returning to the air-to-air heat exchanger 2 exchanges heat with the waste gas entering the air-to-air heat exchanger 2 from the coating machine, completing the step-by-step cooling and recovery of temperature. Because the recovery system is integrated with the coating machine, the system control during production is more coordinated and convenient, and it is also easier to maintain in the future. Compared with the existing coating and recovery separate system, the system in this invention reduces the factory installation space and shortens the length of the air duct, reducing the heat dissipation area of ​​the air duct, thereby saving heating energy. Moreover, this invention is a closed-loop operation and does not require the addition of chilled water and refrigerant, saving costs and processes.

[0034] In this invention, the introduction of fresh air is to compensate for the exhaust gas. That is, the amount of fresh air entering corresponds to the amount of exhaust gas being discharged, thereby ensuring that the gas in the entire system remains at a stable level.

[0035] The recovery system also includes a primary circulating evaporator 4, which is connected to the air-cooled heat exchanger 3 via cold pipes, forming a closed loop. The primary circulating evaporator 4 reduces the gas temperature. The air-cooled heat exchanger 3 further cools the exhaust gas and further reduces its concentration, while transferring heat to the primary circulating evaporator 4.

[0036] In this invention, the recovery system also includes a secondary circulating condenser 12, which is connected to the gas heat exchanger 6 to form a closed loop. The gas temperature is increased through the secondary circulating condenser 12. The gas heat exchanger 6 transfers part of the heat of the gas in the internal circulation circuit to the coating return air and fresh air, completing the entire heat transfer cycle.

[0037] In this invention, the recovery system includes a primary circulating compressor 7, an evaporator-condenser 8, and a primary expansion valve 9. The primary circulating evaporator 4, primary circulating compressor 7, evaporator-condenser 8, and primary expansion valve 9 are sequentially connected to form a closed loop, constituting a primary circulating compression circuit. The primary circulating compressor 7 compresses the low-temperature, low-pressure gas flowing from the primary circulating evaporator 4 into a high-temperature, high-pressure gas. This high-temperature, high-pressure gas passes through the evaporator-condenser 8 and exchanges heat with the gas in the secondary circulating compression circuit (details below). The primary expansion valve 9 expands the liquid in the high-pressure gas, absorbing heat. The primary circulating evaporator 4 and the gas-cooled heat exchanger 3 form a closed loop, a cold-pipe circulation. The cold-pipe circulation is used for heat exchange, and the contents of the pipes can be either liquid or gas.

[0038] In this invention, the recovery system includes a secondary circulating condenser 12, a secondary circulating compressor 11, and a secondary expansion valve 10. The secondary circulating condenser 12, secondary expansion valve 10, evaporator condenser 8, and secondary circulating compressor 11 are sequentially connected to form a closed loop, creating a secondary circulating compression path. When the gas in the secondary circulating compression path passes through the evaporator condenser 8, it exchanges heat with the high-temperature, high-pressure gas in the circulating compression path, thus increasing its temperature. It then enters the secondary circulating compressor 11 for a second heating. The secondary circulating compressor 11 compresses the low-temperature, low-pressure gas to a high-temperature state. The high-temperature, high-pressure gas then passes through the secondary circulating condenser 12. The secondary circulating condenser 12 and the gas-heat exchanger 6 form a closed loop, creating a heat pipe circulation. The heat pipe circulation is used for heat exchange, and the gas inside the pipe can be either liquid or gas. When the high-temperature, high-pressure gas passes through the secondary circulating condenser 12, it exchanges heat with the gas in the heat pipe circulation, which in turn heats the gas in the inner circulating circuit. The secondary expansion valve 10 allows the liquid in the compressed gas to expand and absorb heat.

[0039] In this invention, 5% to 10% of the gas passing through the gas-cooled heat exchanger 3 is discharged, and the remaining gas is returned to the gas-to-gas heat exchanger 2. That is, about 90% to 95% of the gas is recovered and heat exchanged again through the gas-to-gas heat exchanger 2.

[0040] In this invention, the coating machine includes multiple coating machine ovens 1, and each coating machine oven 1 is equipped with a recycling system to ensure that the temperature of each oven remains consistent during the operation of the coating machine, avoiding the situation where the temperature of the middle oven is too low and the temperature of the ovens at both ends is too high. The recycling system in each coating machine oven 1 makes the temperature adjustment of the air in the coating machine more flexible and meets the air temperature requirements of the coating machine.

[0041] In this invention, the coating machine and the recycling system are integrated together, making the equipment smaller. The recycling system can be installed inside the coating machine housing, on the top, or on the side, and the installation location can be selected according to the actual situation.

[0042] Specific embodiments of the various working fluids used in the process of this invention are as follows:

[0043] Working fluid 1: responsible for the heat circulation in the air-cooled heat exchanger 3 and the first-stage circulating evaporator 4. The gas outlet temperature of the air-cooled heat exchanger 3 is controlled at 10±2℃, while the inlet temperature of working fluid 1 in the first-stage circulating evaporator 4 is 15±2℃, the outlet temperature of working fluid 1 in the first-stage circulating evaporator 4 is 8±2℃, and 5% of the gas is discharged.

[0044] Working fluid 2: This refers to the first-stage circulating compression circuit. The outlet temperature of the first-stage circulating evaporator 4 is 10±2℃, the outlet temperature of the first-stage compressor is 90±3℃, the outlet temperature of the evaporator condenser 8 is 54±2℃, and the outlet temperature of the first-stage expansion valve 9 is 3±1℃.

[0045] Working fluid 3: This refers to the two-stage circulation compression circuit. The outlet temperature of the evaporator condenser 8 is 82±2℃, the outlet temperature of the two-stage compressor is 140±3℃, the outlet temperature of the two-stage circulation condenser 12 is 123±2℃, and the outlet temperature of the two-stage expansion valve 10 is 50±2℃.

[0046] Working fluid 4: responsible for the heat transfer between gas heat exchanger 6 and secondary circulating condenser 12, that is, heat pipe circulation. The outlet air temperature of gas heat exchanger 6 is controlled at 128±3℃, while the inlet temperature of working fluid 4 in secondary circulating condenser 12 is 130±3℃, and the outlet temperature of working fluid 4 in secondary circulating condenser 12 is 115±3℃. Internal circulating gas enters and mixes with the gas at the outlet of gas heat exchanger 6.

[0047] In this invention, an auxiliary heater 5 is also provided in the internal circulation. The coating machine oven 1, the gas heat exchanger 6, and the auxiliary heater 5 form a closed loop. The gas entering the internal circulation mixes with part of the gas diverted from the gas heat exchanger 2. The auxiliary heater 5 increases the temperature from 128±2℃ to 150±2℃ and then returns to the coating machine oven 1.

[0048] Compared with traditional processes, the advantages of this invention are high efficiency integration, energy saving, and reduced equipment and space costs:

[0049] 1. In terms of efficient integration:

[0050] (1) The equipment of the present invention is small in size, and integrates the coating machine and the recycling system together. The recycling system can be built into the coating machine, placed on the top, or placed on the side.

[0051] (2) Integrate the design, production, installation and commissioning of the coating system and the recycling system to make the system control more coordinated during production and facilitate future maintenance;

[0052] (3) Since the temperature of each oven section is different when the coating machine is running, the traditional process collects the coating exhaust air and puts it into the recycling system, processes it and then distributes it evenly to each oven, resulting in the temperature of the middle oven being too low and the temperature of the two end ovens being too high. The integrated machine process can configure a recycling system for each oven section, making the temperature adjustment of the air returning to the coating machine more flexible and meeting the air temperature requirements inside the coating machine.

[0053] 2. Energy saving:

[0054] (1) This invention operates in a closed loop and does not require additional chilled water or refrigerant.

[0055] (2) The length of the duct in this invention is reduced by more than 80%, which reduces the heat dissipation area of ​​the duct. The heat dissipation saved by this invention is about 10% of the energy consumption for return air heating.

[0056] (3) The excess heat of the present invention is small and will not have a significant impact on the environment.

[0057] 3. Regarding reducing investment costs:

[0058] The NMP recovery system of this invention is arranged on the coating machine, and since only the exhaust gas is discharged outdoors, the duct area is reduced by more than 80%, which reduces the investment cost of ducts and the installation space of the factory.

[0059] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A coating and recycling integrated system, characterized in that, The system includes a coating machine and a recycling system installed on the coating machine. The recycling system includes a gas-to-gas heat exchanger, a gas-cooled heat exchanger, and a gas-heated heat exchanger. The coating machine includes a coating machine oven, which is provided with a fresh air inlet for external fresh air to enter. The recycling system is integrated into the coating machine. The coating machine oven is connected to the gas-to-gas heat exchanger, the gas-to-gas heat exchanger is connected to the air-cooled heat exchanger, the air-cooled heat exchanger is connected to the outside and is connected to the gas-to-gas heat exchanger through a return air pipe. This cycle is an external circulation operation circuit. The coating machine oven is connected in a closed loop with the gas heat exchanger to form an internal circulation circuit. The gas-to-gas heat exchanger is connected to the gas-heat exchanger and to the internal circulation circuit, and is used to introduce part of the gas cooled by the gas-to-gas heat exchanger into the internal circulation circuit.

2. The coating and recycling integrated system according to claim 1, characterized in that, The recovery system also includes a primary circulating evaporator, which is connected to the air-cooled heat exchanger to form a closed loop, creating a cold pipe circulation.

3. The coating and recycling integrated system according to claim 2, characterized in that, The recovery system also includes a secondary circulating condenser, which is connected to the gas heat exchanger to form a closed loop, forming a heat pipe circulation.

4. The coating and recycling integrated system according to claim 3, characterized in that, The recovery system includes a primary circulating compressor, an evaporator-condenser, and a primary expansion valve. The primary circulating evaporator, the primary circulating compressor, the evaporator-condenser, and the primary expansion valve are connected in sequence to form a closed loop, which is a primary circulating compression circuit.

5. The coating and recycling integrated system according to claim 4, characterized in that, The recovery system includes a two-stage circulating condenser, a two-stage circulating compressor, and a two-stage expansion valve. The two-stage circulating condenser, the two-stage expansion valve, the evaporator-condenser, and the two-stage circulating compressor are connected in sequence to form a closed loop, which is a two-stage circulating compression circuit.

6. The coating and recycling integrated system according to claim 1, characterized in that, Of the gas passing through the gas-cooled heat exchanger, 5% to 10% is discharged, and the remaining gas is returned to the gas-to-gas heat exchanger.

7. The coating and recycling integrated system according to claim 1, characterized in that, The coating machine includes multiple coating machine ovens, and each of the coating machine ovens is equipped with a recycling system.

8. The coating and recycling integrated system according to claim 6, characterized in that, The amount of fresh air entering the coating machine oven corresponds to the amount of exhaust gas discharged.

Images