Waste recovery system and matching method for improving energy efficiency of waste recovery system

Abstract

The invention relates to the technical field of waste recovery, and particularly provides a waste recovery system. In order to solve the problems that in the existing battery pole piece coating process, an NMP recovery system is poor in operation stability and low in energy efficiency, the waste recovery system comprises a circulating air duct, a multi-stage heat pump unit, a cooling tower heat exchanger and a cooling tower, the cooling tower heat exchanger is communicated with the cooling tower through a circulating water path, and the cooling tower is communicated with the exterior of the recovery system. Air in the circulating air duct is cooled and condensed through the evaporator step by step to recover waste materials, heat of the air is absorbed through the cooling tower heat exchanger and then discharged out of the system through the cooling tower, and the condensed air is heated through the condenser step by step and then enters the coating machine again to be dried. The exhausted waste gas is condensed in the mode that the multiple stages of heat pump units are combined with the cooling tower, so that NMP in the waste gas is recycled, the NMP recycling rate is increased, part of heat in the system is taken away through the cooling tower, heat in the system is balanced, it is guaranteed that the heat pump units operate stably, and the energy efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of waste recycling, and specifically provides a waste recycling system and a matching method for improving the energy efficiency thereof. Background Art

[0002] During the coating process of lithium battery pole pieces, NMP solution (N-methylpyrrolidone) is used to dissolve the adhesive in the pole piece slurry, ensuring uniform distribution of the adhesive on the pole piece and ensuring pole piece quality. However, NMP is an expensive organic solvent. To improve its recycling value and reduce costs, it is generally recovered by condensing the evaporated NMP through a heat pump unit. The air is then reheated and returned to the coater to continue drying the pole piece. However, due to the high drying load of the pole piece coating, the low concentration of NMP solvent in the hot air, and the poor operating stability of the heat pump unit, the recovery process consumes a lot of energy, has low energy efficiency, and has a low recovery rate.

[0003] Accordingly, the art needs a new waste recycling system to solve the problems of poor operating stability and low energy efficiency of the existing NMP recovery system in the battery electrode coating process. Summary of the Invention

[0004] The present invention aims to solve the above technical problems, that is, to solve the problems of poor operating stability and low energy efficiency of the NMP recovery system in the existing battery electrode coating process.

[0005] The present invention provides a waste recycling system, which includes a circulating air duct, a multi-stage heat pump unit, a cooling tower heat exchanger and a cooling tower, wherein the cooling tower heat exchanger and the cooling tower are connected through a circulating water circuit, and the cooling tower is connected to the outside of the recycling system;

[0006] The multi-stage heat pump unit includes an evaporator and a condenser arranged on a refrigerant circulation loop, the two ends of the circulating air duct are respectively connected to the air inlet and the air outlet of the coating machine, the evaporator and the condenser are arranged between the air inlet and the air outlet in sequence, and the cooling tower heat exchanger is arranged between the air outlet and the condenser, so that the air in the circulating air duct passes through the evaporator step by step to cool down and condense the recovered waste, and after the cooling tower heat exchanger absorbs the heat of the air, the heat is discharged to the outside of the recovery system through the cooling tower to maintain heat balance. The condensed air is then heated by the condenser step by step and re-enters the coating machine for drying.

[0007] In the preferred technical solution of the above-mentioned waste recycling system, the multi-stage heat pump unit includes a first heat pump unit, a second heat pump unit and a third heat pump unit arranged in sequence; the first heat pump unit includes a first compressor, a first evaporator and a first condenser arranged on a first refrigerant circulation loop, the second heat pump unit includes a second compressor, a second evaporator and a second condenser arranged on a second refrigerant circulation loop, and the third heat pump unit includes a third compressor, a third evaporator and a third condenser arranged on a third refrigerant circulation loop.

[0008] In a preferred technical solution of the above waste recycling system, the cooling tower heat exchanger is arranged between the second evaporator and the third evaporator.

[0009] In the preferred technical solution of the above waste recycling system, the cooling tower heat exchanger is a surface cooler.

[0010] In the preferred technical solution of the above-mentioned waste recycling system, the first heat pump unit also includes a first throttle valve arranged on the first refrigerant circulation loop, the second heat pump unit also includes a second throttle valve arranged on the second refrigerant circulation loop, and the third heat pump unit also includes a third throttle valve arranged on the third refrigerant circulation loop.

[0011] In the preferred technical solution of the above waste recycling system, the waste recycling system further includes a waste collecting device, which is arranged in the circulating air duct and is used to collect condensed waste.

[0012] The present invention also provides a matching method for improving the energy efficiency of a waste recycling system, wherein the waste recycling system includes a circulating air duct, a multi-stage heat pump unit, a cooling tower heat exchanger, and a cooling tower, wherein the cooling tower heat exchanger and the cooling tower are connected via a circulating water circuit, and the cooling tower is connected to the outside of the recycling system;

[0013] The multi-stage heat pump unit includes a compressor, an evaporator and a condenser arranged on a refrigerant circulation loop, the two ends of the circulation duct are respectively connected to the air inlet and the air outlet of the coating machine, the evaporator and the condenser are sequentially arranged between the air outlet and the air inlet, so that the air in the circulation duct is cooled and condensed step by step through the evaporator to recover waste materials, the cooling tower heat exchanger absorbs the heat of the air and discharges the heat to the outside of the system through the cooling tower, and the condensed air is then heated step by step through the condenser and re-enters the coating machine for drying; the multi-stage heat pump unit includes a first heat pump unit, a second heat pump unit and a third heat pump unit arranged in sequence;

[0014] The first heat pump unit includes a first compressor, a first evaporator, and a first condenser arranged on a first refrigerant circulation loop; the second heat pump unit includes a second compressor, a second evaporator, and a second condenser arranged on a second refrigerant circulation loop; the third heat pump unit includes a third compressor, a third evaporator, and a third condenser arranged on a third refrigerant circulation loop; the cooling tower heat exchanger is arranged between the second evaporator and the third evaporator;

[0015] The matching method includes:

[0016] Calculate the total temperature rise of the multi-stage heat pump unit ΔT = (T0-T4+2t);

[0017] The average temperature rise of each heat pump unit is calculated based on ΔT = (T0-T4+2t) / 3; where T0 is the air temperature at the air outlet and the air inlet, T4 is the air temperature in the air outlet direction of the third evaporator, and t is the heat exchange temperature difference; T0, T4, and t are set values;

[0018] Calculate T1 based on the temperature rise of the first heat pump unit ΔT1=CT1-ET1=ΔT;

[0019] According to CT1=T0+t, ET1=T1-t, we can obtain T1=2T0 / 3+T4 / 3+4t / 3; wherein CT1 is the condensing temperature of the first heat pump unit, and ET1 is the evaporating temperature of the first heat pump unit;

[0020] Calculate the heat exchange rate of the first evaporator QE1 = m 风 (h0-h1); where h0 and h1 are the enthalpy values ​​of dry air at temperatures T0 and T1 respectively; m 风 is the air mass in the circulating air duct;

[0021] m 风 =Q 风 ρ 风 ; Where Qwind is the air volume, ρwind is the air density; Qwind is the set value;

[0022] The first evaporator, the first condenser and the first compressor are matched with corresponding parameters according to QE1, ET1 and CT1.

[0023] In the preferred technical solution of the above waste recycling system, the matching method further includes:

[0024] The heating capacity QC1 of the first compressor is obtained by matching QE1, ET1 and CT1;

[0025] According to QC1=m 风 (h0-h6) gives h6=h0-QC1 / m 风; h6 is the enthalpy of dry air at temperature T6, T6 is the air temperature in the outlet direction of the second condenser;

[0026] Calculate T2 based on the temperature rise of the second heat pump unit ΔT2 = CT2 - ET2 = ΔT;

[0027] According to CT2=T6+t, ET2=T2-t, we can obtain T2=T6+4 / 3t-1 / 3t0+1 / 3T4; wherein CT2 is the condensing temperature of the second heat pump unit, ET2 is the evaporating temperature of the second heat pump unit; T2 is the air temperature in the air outlet direction of the second evaporator;

[0028] Calculate the heat exchange rate of the second evaporator QE2 = m 风 (h1-h2); h2 is the enthalpy of dry air at temperature T2;

[0029] The second evaporator, the second condenser and the second compressor are matched with corresponding parameters according to QE2, ET2 and CT2.

[0030] In the preferred technical solution of the above waste recycling system, the matching method further includes:

[0031] The heating capacity QC2 of the second compressor is obtained by matching QE2, ET2, and CT2;

[0032] According to QC2=m 风 (h6-h5) gives h5=h6-QC2 / m 风 ;

[0033] h5 is the enthalpy of dry air at temperature T5, and T5 is the air temperature in the air outlet direction of the third condenser;

[0034] Calculate the heat exchange capacity of the third condenser Qc3 = m 风 (h5-h4); h4 is the enthalpy of dry air at temperature T4;

[0035] The third evaporator, the third condenser and the third compressor are matched with corresponding parameters according to QE3, ET3 and CT3.

[0036] In the preferred technical solution of the above waste recycling system, the matching method further includes:

[0037] The cooling capacity QE3 of the third compressor is obtained according to the matching of QC3, ET3 and CT3;

[0038] According to QE3=m 风 (h3-h4) gives h3=h4+QE3 / m 风 ; h3 is the enthalpy of dry air at temperature T3;

[0039] Calculate the heat that the cooling tower needs to take away Q cooling = m 风 (h2-h3);

[0040] According to Q 冷却 The cooling tower and the cooling tower heat exchanger are matched with corresponding parameters.

[0041] It will be understood by those skilled in the art that the waste recycling system of the present invention includes a circulating air duct, a multi-stage heat pump unit, a cooling tower heat exchanger and a cooling tower, the cooling tower heat exchanger and the cooling tower are connected through a circulating water circuit, and the cooling tower is connected to the outside of the recycling system;

[0042] The multi-stage heat pump unit includes an evaporator and a condenser arranged on the refrigerant circulation loop. The two ends of the circulating air duct are respectively connected to the air inlet and the air outlet of the coating machine. The evaporator and the condenser are arranged between the air inlet and the air outlet in sequence. The cooling tower heat exchanger is arranged between the air outlet and the condenser, so that the air in the circulating air duct passes through the evaporator step by step to cool down and condense the waste to recycle. The cooling tower heat exchanger absorbs the heat of the air and discharges the heat outside the system through the cooling tower. The condensed air is then heated by the condenser step by step and re-enters the coating machine for drying.

[0043] When adopting the above technical solution, the waste recovery system of the present invention adopts a multi-stage heat pump unit combined with a cooling tower to condense the discharged waste gas to recover the NMP therein, and recycle the heat for drying. The inventor found that since the compressor continuously works to generate heat, and the heat required for drying the coater is certain, the heat generated during the closed-loop operation of the recovery system is increasing, which eventually leads to heat imbalance, making the system unstable and even causing the system to be unable to continue operating. Therefore, part of the heat in the system is taken away by the cooling tower to maintain the heat balance in the system, ensuring that the heat pump unit always runs smoothly, improving the energy efficiency of the recovery system, and the condensation effect of the present invention is better and the operation is more stable, thereby improving the NMP recovery rate and lowering the recovery cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0045] Figure 1 Schematic diagram of the waste recycling system of the present invention. List of reference numerals: 1. First heat pump unit; 11. First compressor; 12. First evaporator; 13. First condenser; 14. First throttle valve; 2. Second heat pump unit; 21. Second compressor; 22. Second evaporator; 23. Second condenser; 24. Second throttle valve; 3. Third heat pump unit; 31. Third compressor; 32. Third evaporator; 33. Third condenser; 34. Third throttle valve; 41. Cooling tower heat exchanger; 42. Cooling tower; 5. Coating machine. DETAILED DESCRIPTION

[0046] Preferred embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely intended to illustrate the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art may adjust these embodiments as needed to suit specific applications. It should be noted that, in the description of the present invention, terms such as "inner" and "outer" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is for ease of description only and does not indicate or imply that the device or component described must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0047] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the term "connection" should be understood in a broad sense. For example, it can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection; it can mean a direct connection, an indirect connection through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0048] In order to solve the problems of poor operating stability and low energy efficiency of NMP recovery system in the existing battery electrode coating process, Figure 1 The waste recycling system of the present invention includes a circulating air duct, a multi-stage heat pump unit, a cooling tower heat exchanger 41 and a cooling tower 42. The cooling tower heat exchanger 41 and the cooling tower 42 are connected through a circulating water circuit, and the cooling tower 42 is connected to the outside of the recycling system;

[0049] The multi-stage heat pump unit includes an evaporator and a condenser arranged on the refrigerant circulation loop. The two ends of the circulating air duct are respectively connected to the air inlet and the air outlet of the coating machine. The evaporator and the condenser are arranged between the air inlet and the air outlet in sequence. The cooling tower heat exchanger 41 is arranged between the air outlet and the condenser, so that the air in the circulating air duct passes through the evaporator step by step to cool down and condense the waste to recycle. The cooling tower heat exchanger 41 absorbs the heat of the air and discharges the heat to the outside of the system through the cooling tower 42. The condensed air is then heated by the condenser step by step and re-enters the coating machine for drying.

[0050] The advantage of the above-mentioned setting method is that the waste recovery system of the present invention adopts a multi-stage heat pump unit combined with a cooling tower 42 to condense the discharged waste gas to recover the NMP therein, and recycle the heat for drying. The inventor found that since the compressor continuously works to generate heat, and the heat required for drying the coater is certain, the heat generated during the closed-loop operation of the recovery system is increasing, which eventually leads to heat imbalance, making the system unstable and even causing the system to be unable to continue operating. Therefore, part of the heat in the system is taken away by the cooling tower 42 to maintain the heat balance in the system, ensuring that the heat pump unit always runs smoothly, improving the energy efficiency of the recovery system, and the condensation effect of the present invention is better and the operation is more stable, thereby improving the NMP recovery rate and lowering the recovery cost.

[0051] Reference Figure 1 In one possible embodiment, the waste recycling system of the present invention includes a circulating air duct, a three-stage heat pump unit, a cooling tower heat exchanger 41, a cooling tower 42 and a collection device. The cooling tower heat exchanger 41 and the cooling tower 42 are connected by a circulating water circuit, and the cooling tower 42 is connected to the outside of the recovery system to discharge excess heat in the system to the outside of the system and maintain the thermal balance in the system.

[0052] Furthermore, the three-stage heat pump unit includes a first heat pump unit 1, a second heat pump unit 2, and a third heat pump unit 3. The first heat pump unit 1 includes a first compressor 11, a first evaporator 12, a first throttle valve 14, and a first condenser 13, which are arranged on a first refrigerant circulation loop. The second heat pump unit 2 includes a second compressor 21, a second evaporator 22, a second throttle valve 24, and a second condenser 23, which are arranged on a second refrigerant circulation loop. The third heat pump unit 3 includes a third compressor 31, a third evaporator 32, a third throttle valve 34, and a third condenser 33, which are arranged on a third refrigerant circulation loop. Existing two-stage heat pumps require a relatively large temperature rise, resulting in relatively low energy efficiency for each heat pump unit. However, a three-stage heat pump can maintain the three heat pump units within a reasonable temperature rise range, achieving not only higher energy efficiency but also a balance between energy efficiency and cost. Furthermore, compared to a two-stage heat pump, a three-stage heat pump can recover NMP at a lower temperature, resulting in a higher NMP recovery rate.

[0053] Furthermore, the two ends of the circulating air duct are respectively connected to the air inlet and outlet of the coating machine. Along the direction of air flow, the first evaporator 12, the second evaporator 22, the cooling tower heat exchanger 41, the third evaporator 32, the third condenser 33, the second condenser 23 and the first condenser 13 are sequentially arranged between the air outlet and the air inlet, so that the air in the circulating air duct is cooled and condensed by the evaporators step by step to recover the NMP waste. When the air passes through the cooling tower heat exchanger 41, the cooling tower heat exchanger 41 discharges the absorbed heat to the outside of the system through the cooling tower 42, maintaining the system heat balance and making the recovery system run more smoothly. The condensed air is then heated to the target temperature by the condenser step by step and then re-enters the coating machine for drying. Among them, the cooling tower 42 is arranged between the second heat pump unit 2 and the third heat pump unit 3, so that the air temperature therebetween is not too high or too low. The cooling tower heat exchanger 41 can condense the air only by relying on municipal water, which can prevent the air temperature from falling below the cooling water temperature, causing the cooling tower 42 to lose its cooling air function.

[0054] The waste recycling system further includes a waste collection device disposed within the circulating air duct for collecting NMP waste precipitated by condensation of air within the circulating air duct. For example, the waste collection device can be a conveyor belt, onto which the NMP waste falls and is then transported out of the circulating air duct. Alternatively, the waste collection device can be a receiving tray suspended within the circulating air duct for receiving the NMP waste.

[0055] As stated in the first paragraph of this section, the above implementation mode is only used to illustrate the principles of the present invention and is not intended to limit the scope of protection of the present invention. Without departing from the principles of the present invention, those skilled in the art can adjust the above structure so that the present invention can be applied to more specific application scenarios.

[0056] In addition, the present invention also provides a matching method for improving the energy efficiency of a waste recycling system. The waste recycling system is the waste recycling system in the above-mentioned embodiment. Through this matching method, the parameters of the heat pump unit and the cooling tower 42 in the recycling system are selected, thereby matching a high-efficiency recycling system that matches the drying capacity of the coating machine, making NMP recovery more energy-efficient.

[0057] Reference Figure 1 Specifically, the energy efficiency matching methods of the waste recycling system include:

[0058] Calculate the total temperature rise required by the three-stage heat pump system: △T = T0-T4+2t;

[0059] Calculate the average temperature rise of each heat pump unit △T based on △T 均=(T0-T4+2t) / 3; wherein T0 is the air temperature at the air outlet and the air inlet, T4 is the air temperature in the air outlet direction of the third evaporator 32, and t is the heat exchange temperature difference; T0, T4, and t are set values, which are set by those skilled in the art according to actual needs.

[0060] Specifically, △T1=△T2=△T3=△T 均 , where △T1 is the temperature rise of the first heat pump unit, △T2 is the temperature rise of the second heat pump unit, and △T3 is the temperature rise of the third heat pump unit. The temperature rise of the heat pump is directly related to the difficulty of the compressor to perform work, which is also directly related to the operating energy efficiency of the heat pump system. The larger the temperature difference that the heat pump needs to increase, the lower the heat pump efficiency, and the smaller the temperature difference that the heat pump needs to increase, the higher the heat pump efficiency. Therefore, by equalizing the temperature rise of the three heat pump units, the energy efficiency of the three heat pump units is balanced and they can all operate under optimal conditions. Taking T0 = 110℃, T4 = 15℃, and t = 10℃ as an example, the average temperature rise of each heat pump unit in the three-stage heat pump unit is 38.3℃. Under this temperature rise, the heating energy efficiency of the general heat pump system can be greater than 4.0, thereby making the overall energy efficiency of the recovery system higher.

[0061] According to △T1=CT1-ET1=△T 均 Calculate T1; wherein CT1 is the condensing temperature of the first heat pump unit, ET1 is the evaporating temperature of the first heat pump unit; T1 is the air temperature in the outlet direction of the first evaporator 12.

[0062] Specifically, according to CT1=T0+t; ET1=T1-t;

[0063] △T1=CT1-ET1=T0-T1+2t=△T 均 ;

[0064] T0-T1+2t=(T0-T4+2t) / 3;

[0065] Finally, we get T1=2T0 / 3+T4 / 3+4t / 3.

[0066] Calculate the heat exchange capacity of the first evaporator 12 QE1 = m 风 (h0-h1); where h0 and h1 are the enthalpy values ​​of dry air at temperatures T0 and T1 respectively; m 风 It is the air quality in the circulating air duct.

[0067] m 风 =Q 风 ρ 风 ; where Q 风 is the air volume, ρ 风 is the air density; Q 风 is a set value, which is set by those skilled in the art according to the drying requirements of the coater;

[0068] According to QE1, ET1, and CT1, the first evaporator 12, the first condenser 13, and the first compressor 11 with corresponding parameters are matched for the recovery system.

[0069] The first evaporator 12, the first condenser 13 and the first compressor 11 are selected according to the specific values ​​of QE1, ET1 and CT1 obtained by calculation, so as to achieve the optimal system energy efficiency.

[0070] Based on T0 and T1, the specific values ​​of h0 and h1 can be obtained by looking up the physical properties of the air in a table. The circulating air has an extremely low humidity content, and the NMP it contains is negligible compared to the large change in air enthalpy. Therefore, it can be treated as dry air for calculating the heat change. It should be noted that the references to air temperature and enthalpy below can be obtained by looking up the table to obtain the dry air enthalpy at the corresponding air temperature or the air temperature at the corresponding dry air enthalpy value. This will not be further explained.

[0071] Furthermore, the rated operating power W1 of the first compressor 11 and the heating capacity QC1 of the first compressor 11 are obtained by matching the calculated QE1, ET1, and CT1 through the compressor operating condition calculation sheet;

[0072] According to QC1=m 风 (h0-h6) gives h6=h0-QC1 / m 风 ; h6 is the enthalpy of dry air at temperature T6, T6 is the air temperature in the outlet direction of the second condenser 23;

[0073] According to the temperature rise of the second heat pump unit △T2=CT2-ET2=△T 均 Calculate T2; where CT2 is the condensing temperature of the second heat pump unit, ET2 is the evaporating temperature of the second heat pump unit; T2 is the air temperature in the outlet direction of the second evaporator 22;

[0074] According to CT2=T6+t;ET2=T2-t;

[0075] T6-T2+2t=(T0-T4+2t) / 3;

[0076] Finally, we get T2=T6+4 / 3t-1 / 3t0+1 / 3T4;

[0077] Calculate the heat exchange capacity of the second evaporator 22 QE2 = m 风 (h1-h2); h2 is the enthalpy of dry air at temperature T2;

[0078] According to QE2, ET2, and CT2, the second evaporator 22, the second condenser 23, and the second compressor 21 with corresponding parameters are matched for the recovery system.

[0079] The second evaporator 22, the second condenser 23 and the second compressor 21 are selected according to the specific values ​​of QE2, ET2 and CT2 obtained by calculation, so as to achieve the optimal system energy efficiency.

[0080] According to the calculated QE2, ET2, and CT2, the rated operating power W2 of the second compressor 21 and the heating capacity QC2 of the second compressor 21 are obtained by matching the compressor working condition calculation sheet;

[0081] According to QC2=m 风 (h6-h5) gives h5=h6-QC2 / m 风 ; Among them, h5 is the enthalpy value of dry air at temperature T5, and T5 is the air temperature in the outlet direction of the third condenser 33.

[0082] Calculate the heat exchange capacity of the third condenser 33 QC3 = m 风 (h5-h4); h4 is the enthalpy of dry air at temperature T4;

[0083] According to QE3, ET3, and CT3, the third evaporator 32, the third condenser 33, and the third compressor 31 with corresponding parameters are matched to the recovery system.

[0084] The third evaporator 32 , the third condenser 33 and the third compressor 31 are selected according to the specific values ​​of QE3 , ET3 and CT3 obtained by calculation, so as to achieve the optimal system energy efficiency.

[0085] According to the calculated QE3, ET3, and CT3, the rated operating power W3 of the third compressor 31 and the heating capacity QC3 of the third compressor 31 are obtained by matching the compressor working condition calculation sheet;

[0086] According to QE3=m 风 (h3-h4) gives h3=h4+QE3 / m 风 ; h3 is the enthalpy of dry air at temperature T3;

[0087] Calculate the heat Q that the cooling tower 42 needs to remove 冷却 =m 风 (h2-h3);

[0088] According to Q 冷却 The cooling tower 42 and cooling tower heat exchanger 41 are matched with corresponding parameters for the recovery system.

[0089] That is, according to the calculated Q 冷却 Select a type for the cooling tower 42 and the cooling tower heat exchanger 41.

[0090] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A waste recycling system, characterized in that: It includes a circulating air duct, a multi-stage heat pump unit, a cooling tower heat exchanger and a cooling tower, wherein the cooling tower heat exchanger and the cooling tower are connected through a circulating water circuit, and the cooling tower is connected to the outside of the recovery system; The multi-stage heat pump unit includes an evaporator and a condenser arranged on a refrigerant circulation loop, the two ends of the circulating air duct are respectively connected to the air inlet and the air outlet of the coating machine, the evaporator and the condenser are arranged between the air inlet and the air outlet in sequence, and the cooling tower heat exchanger is arranged between the air outlet and the condenser, so that the air in the circulating air duct passes through the evaporator step by step to cool down and condense the recovered waste, and after the cooling tower heat exchanger absorbs the heat of the air, the heat is discharged to the outside of the recovery system through the cooling tower to maintain heat balance. The condensed air is then heated by the condenser step by step and re-enters the coating machine for drying.

2. The waste recycling system according to claim 1, characterized in that: The multi-stage heat pump unit includes a first heat pump unit, a second heat pump unit and a third heat pump unit arranged in sequence; the first heat pump unit includes a first compressor, a first evaporator and a first condenser arranged on a first refrigerant circulation loop, the second heat pump unit includes a second compressor, a second evaporator and a second condenser arranged on a second refrigerant circulation loop, and the third heat pump unit includes a third compressor, a third evaporator and a third condenser arranged on a third refrigerant circulation loop.

3. The waste recycling system according to claim 2, characterized in that: The cooling tower heat exchanger is arranged between the second evaporator and the third evaporator.

4. The waste recycling system according to claim 1, characterized in that: The cooling tower heat exchanger is a surface cooler.

5. The waste recycling system according to claim 3, characterized in that: The first heat pump unit also includes a first throttle valve arranged on the first refrigerant circulation loop, the second heat pump unit also includes a second throttle valve arranged on the second refrigerant circulation loop, and the third heat pump unit also includes a third throttle valve arranged on the third refrigerant circulation loop.

6. The waste recycling system according to claim 3, characterized in that: The waste recycling system further comprises a waste collecting device, which is arranged in the circulating air duct and is used for collecting condensed waste.

7. A matching method for improving the energy efficiency of a waste recycling system, characterized in that: The waste recycling system includes a circulating air duct, a multi-stage heat pump unit, a cooling tower heat exchanger and a cooling tower, wherein the cooling tower heat exchanger and the cooling tower are connected through a circulating water circuit, and the cooling tower is connected to the outside of the recycling system; The multi-stage heat pump unit includes a compressor, an evaporator and a condenser arranged on a refrigerant circulation loop, the two ends of the circulation duct are respectively connected to the air inlet and the air outlet of the coating machine, the evaporator and the condenser are sequentially arranged between the air outlet and the air inlet, so that the air in the circulation duct is cooled and condensed step by step through the evaporator to recover waste materials, the cooling tower heat exchanger absorbs the heat of the air and discharges the heat to the outside of the system through the cooling tower, and the condensed air is then heated step by step through the condenser and re-enters the coating machine for drying; the multi-stage heat pump unit includes a first heat pump unit, a second heat pump unit and a third heat pump unit arranged in sequence; The first heat pump unit includes a first compressor, a first evaporator, and a first condenser arranged on a first refrigerant circulation loop; the second heat pump unit includes a second compressor, a second evaporator, and a second condenser arranged on a second refrigerant circulation loop; the third heat pump unit includes a third compressor, a third evaporator, and a third condenser arranged on a third refrigerant circulation loop; the cooling tower heat exchanger is arranged between the second evaporator and the third evaporator; The matching method includes: Calculate the total temperature rise of the multi-stage heat pump unit ΔT = (T0-T4+2t); Calculate the average temperature rise of each heat pump unit △T based on △T 均 =(T0-T4+2t) / 3; where T0 is the air temperature at the air outlet and the air inlet, T4 is the air temperature in the air outlet direction of the third evaporator, and t is the heat exchange temperature difference; T0, T4, and t are set values; According to the temperature rise of the first heat pump unit ΔT1=CT1-ET1=ΔT 均 Calculate T1; According to CT1=T0+t, ET1=T1-t, we can obtain T1=2T0 / 3+T4 / 3+4t / 3; wherein CT1 is the condensing temperature of the first heat pump unit, and ET1 is the evaporating temperature of the first heat pump unit; Calculate the heat exchange rate of the first evaporator QE1 = m 风 (h0-h1); where h0 and h1 are the enthalpy values ​​of dry air at temperatures T0 and T1 respectively; m 风 is the air mass in the circulating air duct; m 风 =Q 风 ρ 风 ; where Q 风 is the air volume, ρ 风 is the air density; Q 风 is the set value; The first evaporator, the first condenser and the first compressor are matched with corresponding parameters according to QE1, ET1 and CT1.

8. The matching method for improving the energy efficiency of a waste recycling system according to claim 7, characterized in that: The matching method further includes: The heating capacity QC1 of the first compressor is obtained by matching QE1, ET1 and CT1; According to QC1=m 风 (h0-h6) gives h6=h0-QC1 / m 风 ; h6 is the enthalpy of dry air at temperature T6, T6 is the air temperature in the outlet direction of the second condenser; According to the temperature rise of the second heat pump unit ΔT2=CT2-ET2=ΔT 均 Calculate T2; According to CT2=T6+t, ET2=T2-t, we can obtain T2=T6+4 / 3t-1 / 3t0+1 / 3T4; wherein CT2 is the condensing temperature of the second heat pump unit, ET2 is the evaporating temperature of the second heat pump unit; T2 is the air temperature in the air outlet direction of the second evaporator; Calculate the heat exchange rate of the second evaporator QE2 = m 风 (h1-h2); h2 is the enthalpy of dry air at temperature T2; The second evaporator, the second condenser and the second compressor are matched with corresponding parameters according to QE2, ET2 and CT2.

9. The matching method for improving the energy efficiency of a waste recycling system according to claim 8, characterized in that: The matching method further includes: The heating capacity QC2 of the second compressor is obtained by matching QE2, ET2, and CT2; According to QC2=m 风 (h6-h5) gives h5=h6-QC2 / m 风 ; h5 is the enthalpy of dry air at temperature T5, and T5 is the air temperature in the air outlet direction of the third condenser; Calculate the heat exchange capacity of the third condenser Qc3 = m 风 (h5-h4); h4 is the enthalpy of dry air at temperature T4; The third evaporator, the third condenser and the third compressor are matched with corresponding parameters according to QE3, ET3 and CT3.

10. The matching method for improving the energy efficiency of a waste recycling system according to claim 9, characterized in that: The matching method further includes: The cooling capacity QE3 of the third compressor is obtained according to the matching of QC3, ET3 and CT3; According to QE3=m 风 (h3-h4) gives h3=h4+QE3 / m 风 ; h3 is the enthalpy of dry air at temperature T3; Calculate the heat Q that the cooling tower needs to remove 冷却 =m 风 (h2-h3); According to Q 冷却 The cooling tower and the cooling tower heat exchanger are matched with corresponding parameters.

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