NMP three-stage surface cooling recovery system and design method thereof

Abstract

The invention discloses an NMP three-stage surface cooling recovery system and a design method thereof, the three-stage surface cooling recovery system comprises a cooling surface air cooler, a condensing surface air cooler, a demister and a heating surface air cooler which are arranged in sequence, heat exchange is formed between the cooling surface air cooler and the heating surface air cooler through circulating water, and the condensing surface air cooler realizes cooling through chilled water. According to the design method, only the exhaust air volume, the exhaust air concentration, the exhaust air temperature, the discharge proportion and the return air temperature of the NMP three-stage surface cooling recovery system need to be given, the temperature point changes of the air side and the water side of each stage of surface air cooler in the three-stage surface cooling system and the size and the structure needed by each stage of surface air cooler can be determined, the design method is simple, the efficiency is high, and the design method is suitable for popularization and application. And the requirements of process and structural design can be quickly met.

Description

Technical Field

[0001] The invention belongs to the technical field of NMP waste gas recovery, and in particular relates to an NMP three-stage surface cooling recovery system and a design method thereof. Background Art

[0002] In the field of lithium battery production, N-methylpyrrolidone (NMP) is widely used as a polar solvent. However, NMP is easily consumed or volatilized during the production process and is relatively expensive. In order to reduce costs and reduce environmental impact, it is particularly important to recycle and reuse NMP. The NMP recovery solution dominated by the three-stage surface cooling system in the existing NMP waste gas recovery system can not only replace the waste heat recovery device and eliminate the use of cooling towers, but also recover the cooling capacity of the cooling tower, greatly reducing the layout of the equipment, and can also cool and condense the NMP waste gas, meeting the process requirements of NMP recovery.

[0003] In the prior art solution, in the three-stage cooling system, the heat loads among the first-stage cooling unit, the third-stage cooling unit and the circulating water pipe need to be balanced, and the cooling unit has a limited heat transfer performance due to its fixed structure, which results in the exhaust air volume and exhaust air temperature on the air side ultimately affecting the return air temperature on the air side and the circulating temperature on the water side. Therefore, the prior art three-stage cooling system involves many variable factors, and its design process and calculation method are relatively complicated, and the design efficiency is low and the cost is high.

[0004] Therefore, how to design a three-stage surface cooling system design method for a fixed NMP waste gas recovery system with high efficiency, low cost, simple design process and calculation method is a technical problem to be solved. Summary of the invention

[0005] Based on this, it is necessary to provide a NMP three-stage surface cooling recovery system and a design method thereof in view of the problems of the prior art.

[0006] In the first aspect, the embodiment of the present application provides a design method for a three-stage NMP surface cooling recovery system, wherein the three-stage surface cooling recovery system comprises a cooling surface cooler, a condensing surface cooler, a demister and a heating surface cooler arranged in sequence, wherein the cooling surface cooler and the heating surface cooler form heat exchange through circulating water, and the condensing surface cooler is cooled by chilled water, and the parameter design method comprises the following steps:

[0007] Step S1: obtaining initial gas side operating parameters, initial water side operating parameters and initial system structure parameters of the three-stage surface cooling recovery system;

[0008] Step S2: inputting the initial air side operating parameters, the initial water side operating parameters and the initial system structure parameters into the first surface cooling energy conservation model to obtain the first air side operating parameters, the first water side operating parameters and the first system structure parameters;

[0009] Step S3: inputting the first gas side operating parameter, the first water side operating parameter and the first system structure parameter into the second surface cooling energy conservation model to obtain the second gas side operating parameter, the second water side operating parameter and the second system structure parameter;

[0010] Step S4: inputting the second gas side operating parameter, the second water side operating parameter and the second system structure parameter into the third surface cooling energy conservation model to obtain the third gas side operating parameter, the third water side operating parameter and the third system structure parameter;

[0011] Step S5: determining whether the third gas side operating parameter, the third water side operating parameter and the third system structure parameter meet preset conditions;

[0012] Step S6: in response to the third air-side operating parameter, the third water-side operating parameter and the third system structure parameter satisfying a preset condition, the third air-side operating parameter, the third water-side operating parameter and the third system structure parameter are updated according to the first updating method and the updated third air-side operating parameter, the third water-side operating parameter and the third system structure parameter are output as the final air-side operating parameter, the final water-side operating parameter and the final system structure parameter of the three-stage surface cooling recovery system; otherwise, the third air-side operating parameter, the third water-side operating parameter and the third system structure parameter are updated according to the second updating method and the updated third air-side operating parameter, the third water-side operating parameter and the third system structure parameter are output as the final air-side operating parameter, the final water-side operating parameter and the final system structure parameter of the three-stage surface cooling recovery system;

[0013] Step S7: designing the three-stage surface cooling recovery system according to the final gas side operating parameters, final water side operating parameters and final system structure parameters of the three-stage surface cooling recovery system.

[0014] Preferably, the initial air side operating parameters include exhaust air volume F, exhaust air temperature T1, NMP exhaust air concentration q, return air temperature T3, circulation ratio a, room temperature T S , relative humidity and the mass flow rate G of the three-stage surface cooling recovery system;

[0015] The initial water side operating parameters include the circulating temperature t of the circulating water high temperature point 12 and water volume W1 and chilled water inlet temperature t 21 and outlet temperature t 22 ;

[0016] The initial system structural parameters include the coil outer diameter d, the wing ratio β, the heat transfer area margin coefficient ε, the maximum limited wind width w * , heat transfer coefficient K1 of cooling surface cooler, heat transfer coefficient K2 of condensing surface cooler, heat transfer coefficient K3 of heating surface cooler, expected value η of heat exchange efficiency e And the initial value of heat exchange efficiency η0.

[0017] Preferably, the first surface cooling energy conservation model is expressed by the following formulas (1)-(3):

[0018]

[0019] S1=πdwβR1C1 (2);

[0020]

[0021] Among them, ρ a is the air side density, ρ w1 is the circulating water side density, t 11 is the circulating temperature of the circulating water low temperature point, T2 is the outlet temperature of the air side after the cooling surface cooler, is the average specific heat capacity of the air side of the cooling cooler, is the average specific heat capacity of the water side of the cooling surface cooler, Q n1 is the condensation latent heat generated by the air side passing through the cooling surface cooler, S1 is the heat exchange area of ​​the cooling surface cooler, Δt m1 is the logarithmic mean temperature difference of the cooling surface cooler, R1 is the number of coil rows of the cooling surface cooler, C1 is the number of holes in each row of the coil of the cooling surface cooler, and W1 is the circulating water volume of the circulating water.

[0022] Preferably, the second surface cooling energy conservation model is expressed by the following formulas (4)-(6):

[0023]

[0024] S2=πdwβR2C2 (5);

[0025]

[0026] Among them, ρ w2 is the density of the chilled water side, W2 is the inlet and outlet volume of the chilled water, is the average specific heat capacity of the air side of the condensing cooler, is the average specific heat capacity of the water side of the condensing cooler, Q n2 is the condensation latent heat generated by the gas side passing through the condenser, S2 is the heat exchange area of ​​the condenser, Δt m2 is the logarithmic mean temperature difference of the condensing cooler, R2 is the number of coil rows of the condensing cooler, and C2 is the number of holes in each row of the coil of the condensing cooler.

[0027] Preferably, the third surface cooling energy conservation model is expressed by the following formulas (7)-(9):

[0028]

[0029] S3=πdwβR3C3 (8);

[0030]

[0031] Among them, T4 is the outlet temperature of the air side after passing through the heating surface cooler, is the average specific heat capacity of the air side of the heating surface cooler, S3 is the heat exchange area of ​​the heating surface cooler, Δt m3 is the logarithmic mean temperature difference of the heating surface cooler, R3 is the number of coil rows of the heating surface cooler, and C3 is the number of holes in each row of the coil of the heating surface cooler.

[0032] Preferably, step S2 comprises:

[0033] Step S21: Obtain T2, T4 and Q1 according to the initial value η0 of the heat exchange efficiency, the exhaust air temperature T1, the return air temperature T3 and the first surface cooling energy conservation model;

[0034] Step S22: According to parameter t 12 , T1, T2, obtain ρ a and ρ w1 ;

[0035] Step S23: Set the parameters W1, ρ a and ρ w1 Input the first table cold energy conservation model to obtain Q n1 ,t 11 and S1;

[0036] Step S24: According to the parameter Q n1 ,t 11 and S1, obtain R1 and C1;

[0037] Step S25: Obtain updated S1 according to parameters R1 and C1;

[0038] Step S26: Based on the parameters T1, updated S1, W1, t 12 And the first table cold energy conservation model, get the updated Q1, updated Q n1 , the first updated t 11 , the first updated T2;

[0039] Step S27: Based on the parameters T1, the first updated T2, and the first updated t 11 ,t12 , get updated Updated

[0040] Step S28: Based on the updated Updated Get the second updated T2 and the second updated t 11 ;

[0041] Step S29: Determine whether the absolute difference between the second updated T2 and the first updated T2 is greater than or equal to 0.001;

[0042] Step S210: in response to the absolute difference between the second updated T2 and the first updated T2 being greater than or equal to 0.001, repeating steps S21-S29;

[0043] Step S211: Output the second updated T2 and the updated Q n1 , the second updated t 11 ,t 12 , R1 and C1 are used as the first gas side operating parameter, the first water side operating parameter and the first system structure parameter.

[0044] Preferably, step S3 comprises:

[0045] Step S31: T2, T3, t 21 ,t 22 ,get and ρ w2 ;

[0046] Step S32: Set the parameters and ρ w2 Input the second cold energy conservation model to obtain Q2, Q n2 , W2 and S2;

[0047] Step S33: According to parameters Q2, Q n2 , W2 and S2, obtain R2 and C2;

[0048] Step S34: Obtain updated S2 according to parameters R2 and C2;

[0049] Step S35: Update the parameters S2, the second updated T2, and t 21 and t 22 Input the second table cold energy conservation model to obtain updated Q2 and updated Q n2 , first updated T3 and updated W2;

[0050] Step S36: Based on the parameters T2 of the second update, T3 of the first update, t 21 and t 22, get updated Updated

[0051] Step S37: Update the parameters Updated Get the second updated T3 and the updated t 22 ;

[0052] Step S38: Determine whether the absolute difference between the second updated T3 and the first updated T3 is greater than or equal to 0.001;

[0053] Step S39: in response to the absolute difference between the second updated T3 and the first updated T3 being greater than or equal to 0.001, repeating steps S2 and S31-S38;

[0054] Step S310: Output the second updated T2 and the updated Q n1 , the second updated t 11 ,t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2 are used as the second gas side operating parameter, the second water side operating parameter and the second system structure parameter.

[0055] Preferably, step S4 comprises:

[0056] Step S41: According to the second updated parameter T3, obtain

[0057] Step S42: Set the second updated parameters T3, W1, and t 11 ,t 12 and Input the third table cold energy conservation model to obtain the first updated T4 and S3;

[0058] Step S43: According to the second updated parameter T3 and the first updated parameter T4, obtain the updated

[0059] Step S44: Update the parameters Get the second updated T4;

[0060] Step S45: determining whether the absolute difference between the second updated T4 and the first updated T4 is greater than or equal to 0.001;

[0061] Step S46: in response to the absolute difference between the second updated T4 and the first updated T4 being greater than or equal to 0.001, repeating steps S41-S45;

[0062] Step S47: Substitute the second updated T4 and S3 to obtain R3 and C3;

[0063] Step S48: Obtain updated S3 according to parameters R3 and C3;

[0064] Step S49: Set the parameters of the second updated T3, the second updated T4, and the second updated t 11 and the updated S3 are input into the third table cold energy conservation model to obtain the updated W1, the first updated t 12 ;

[0065] Step S410: Obtain η according to the parameters T1, the second updated T3 and the second updated T4. k ;

[0066] Step S411: Obtain η according to parameters T1, T3 and T4 e ;

[0067] Step S412: Determine n k With η e Is the absolute difference between them less than 0.005?

[0068] Step S413: In response to n k With η e When the absolute difference between them is less than 0.005, the first updated T2 and the updated Q are output. n1 , the second updated t 11 , the first updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and η e As the third gas side operating parameter, the third water side operating parameter and the third system structure parameter; otherwise, execute step S5.

[0069] Preferably, the preset conditions are expressed by formulas (10) and (11):

[0070] 0≤η e -η0≤0.1 (10);

[0071] |η k -η e |<0.005 (11);

[0072] in, in, For the second updated T4, This is the second updated T3.

[0073] Preferably, the first updating method comprises the following steps:

[0074] Step S611: Update the first updated parameter t 12 is the second updated t 12 , according to the second updated t 12 Update η k Get the first updated η k ;

[0075] Step S612: Determine the first updated n k With η e Is the absolute difference between them less than 0.005?

[0076] Step S613: In response to the first updated n k With η e When the absolute difference between them is less than 0.005, repeat steps S2-S4 and S611-S612; otherwise, execute the second updating method;

[0077] Step S614: Output the second updated T2 and the updated Q n1 , the second updated t 11 , the second updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and first updated η k As the third gas side operating parameter, the third water side operating parameter and the third system structure parameter.

[0078] Preferably, the second updating method comprises the following steps:

[0079] Step S621: Update the initial value η0 to obtain an updated initial value η0, and update η according to the updated initial value η0. k Get the second updated η k ;

[0080] Step S622: Determine the second updated n k With η e Is the absolute difference between them less than 0.005?

[0081] Step S623: In response to the second updated n k With η e When the absolute difference between them is less than 0.005, repeat steps S2-S5 and S621-S622; otherwise, execute steps S625-S626;

[0082] Step S624: Output the second updated T2 and the updated Q n1 , the second updated t 11 , the second updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and second updated η k As the third gas side operating condition parameter, the third water side operating condition parameter and the third system structure parameter, execute step S7;

[0083] Step S625: In the steps of the first updating method and the second updating method, select and execute n k With η e The steps corresponding to the minimum absolute difference between them are performed to obtain the third updated η k ;

[0084] Step S626: Output the second updated T2 and the updated Q n1 , the second updated t 11 , the second updated t 12 , R1 and C1, the second updated T3, the updated q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and third updated η k As the third gas side operating parameter, the third water side operating parameter and the third system structure parameter.

[0085] Preferably, the parameters W1, t 12 、T2、T4、Q1、 and The initial value of is obtained by the following formula:

[0086] W1=2.3×10 -4 F;

[0087]

[0088] T2 = T1 - (T1 - T3) η0;

[0089] T4=T3+(T1-T3)η0;

[0090]

[0091] Among them, c w11 and c w21 are respectively the water side at temperature t 11 and t21 The specific heat capacity under .

[0092] Preferably, during the updating process, the parameter ρ a , ρ w1 , w2 , R1, R2, R3, C1, C2, C3, S1, S2, S3, Q1, and Q2 are updated using the following formula:

[0093]

[0094] S i =πdwβR i C i ,i=1,2,3;

[0095]

[0096] Among them, w is the wind width, h is the wind height, r is the coil hole distance, is the initial heat exchange area of ​​the surface cooler, S i is the heat exchange area of ​​the surface cooler, and the parameters of the above formula are obtained by the following formula:

[0097]

[0098] Among them, "[]" is a round-down operation, and "{}" is a small operation;

[0099] Among them, Q1 is the sensible heat generated by the air side through the cooling condenser, and Q2 is the sensible heat generated by the air side through the condensing condenser; a1 、c a2 、c a3 and c a4 are the specific heat capacities of the gas side at temperatures T1, T2, T3 and T4 respectively; c w12 and c w22 are respectively the water side at temperature t 12 and t 22 Specific heat capacity under w11 、c w12 、c w21 and c w22 It is obtained by the following formula:

[0100]

[0101]

[0102] Among them, Q n1 and Q n2 It is expressed by the following formula:

[0103]

[0104] Among them, T n1 is the dew point temperature at which NMP on the gas side condenses in the cooling condenser, T n2 T is the dew point temperature at which NMP on the gas side condenses in the condenser. n3 is the dew point temperature of NMP on the gas side at the outlet of the condenser. ni >0 satisfies T n(i+1) =T i+1 , L n1 , L n2 and L n3 Dew point temperature T n1 , T n2 and T n3 The saturated humidity of the air side under n1 , H n2 and H n3 Dew point temperature T n1 , T n2 and T n3 Heat of vaporization on the lower gas side, T ni , L ni and H ni They are all determined by the initial NMP exhaust concentration q of the system.

[0105] In the second aspect, an embodiment of the present application provides a NMP three-stage surface cooling recovery system designed according to the method described in the first aspect, wherein the three-stage surface cooling recovery system includes a cooling surface cooler, a condensing surface cooler, a defogger and a heating surface cooler arranged in sequence, wherein heat exchange is formed between the cooling surface cooler and the heating surface cooler through circulating water, and the condensing surface cooler is cooled by chilled water.

[0106] Compared with the prior art, the present invention has the following beneficial effects: the design method proposed in the present application only needs to give the exhaust air volume, exhaust air concentration, exhaust air temperature, external exhaust ratio and return air temperature of the NMP three-stage surface cooling recovery system, so as to determine the changes in each temperature point on the air side and water side of each stage of the surface cooler in the three-stage surface cooling system, as well as the required size and structure of each stage of the surface cooler. The design method is simple and efficient, and can quickly meet the requirements of process and structural design. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] By referring to the following drawings, the exemplary embodiments of the present invention can be more completely understood. The drawings are used to provide a further understanding of the embodiments of the present application, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present invention and do not constitute a limitation of the present invention. In the drawings, the same reference numerals generally represent the same parts or steps.

[0108] Figure 1A flow chart of a design method for a three-stage NMP surface cooling recovery system provided in an embodiment of the present application;

[0109] Figure 2 A flowchart of step S2 of a design method for a three-stage NMP surface cold recovery system provided in an embodiment of the present application;

[0110] Figure 3 A flowchart of step S3 of a design method for a three-stage NMP surface cold recovery system provided in an embodiment of the present application;

[0111] Figure 4 A flowchart of step S4 of a design method for a three-stage NMP surface cooling recovery system provided in an embodiment of the present application;

[0112] Figure 5 A flowchart of a first updating method of a design method for a NMP three-stage cold recovery system provided in an embodiment of the present application;

[0113] Figure 6 A flow chart of a second updating method of a design method for a NMP three-stage cold recovery system provided in an embodiment of the present application;

[0114] Figure 7 The present invention provides an overall process flow diagram of a three-stage NMP surface cooling recovery system.

[0115] Reference numerals

[0116] 1-production equipment, 2-heater, 3-return air fan, 4-air duct, 5-circulating water pipe, 6-circulating water pump, 7-refrigerator, 8-exhaust fan, 9-NMP three-stage surface cooling recovery system, 91-cooling surface cooler, 92-condensing surface cooler, 93-demister, 94-heating surface cooler. DETAILED DESCRIPTION

[0117] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0118] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0119] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0120] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0121] Reference Figure 1 This embodiment discloses a design method for a three-stage NMP surface cooling recovery system, wherein the three-stage surface cooling recovery system comprises a cooling surface cooler, a condensing surface cooler, a demister and a heating surface cooler arranged in sequence, wherein the cooling surface cooler and the heating surface cooler form heat exchange through circulating water, and the condensing surface cooler is cooled by chilled water, and the parameter design method comprises the following steps:

[0122] Step S1: obtaining initial gas side operating parameters, initial water side operating parameters and initial system structure parameters of the three-stage surface cooling recovery system;

[0123] The three-stage cooling recovery system of this embodiment takes a tube-fin type cooling unit as an example. The first stage cooling unit is a cooling unit, the second stage cooling unit is a condensing unit, and the third stage cooling unit is a heating unit. The number of coil rows and the number of holes in each row of the i-th stage cooling unit (i=1, 2, 3) are set as R. i and C i , the heat transfer coefficient on the gas side is K i (W / (m2·℃)) and the heat transfer area is S i(m2), other main structural dimensions are the same, namely, the wind width is w (m), the wind height is h (m), the coil outer diameter is d (m), the coil hole spacing is r (m), and the fin ratio β. Moreover, in order to ensure the condensation effect of the second-stage cooler and the defogger effect of the demister, an appropriate wind area Y (m) (i.e., Y = wh) is generally set in the structure, so that the gas side has a more appropriate mass flow rate G (kg / (m2·s)) when passing through the cooler. In order to facilitate the packaging of these three coolers into a whole to reduce the size, it is necessary to ensure that the wind area on the gas side remains consistent. For other types of heat exchangers, the difference is that S i Different calculation methods.

[0124] Specifically, the initial air side operating parameters include exhaust air volume F, exhaust air temperature T1, NMP exhaust air concentration q, return air temperature T3, circulation ratio a, room temperature T S , relative humidity and the mass flow rate G of the three-stage surface cooling recovery system; the initial water side operating parameters include the circulating temperature t of the circulating water high temperature point 12 and water volume W1 and chilled water inlet temperature t 21 and outlet temperature t 22 ; The initial system structural parameters include coil outer diameter d, wing ratio β, heat transfer area margin coefficient ε, maximum limited wind width w * , heat transfer coefficient K1 of cooling surface cooler, heat transfer coefficient K2 of condensing surface cooler, heat transfer coefficient K3 of heating surface cooler, expected value η of heat exchange efficiency e And the initial value of heat exchange efficiency η0.

[0125] Step S2: inputting the initial air side operating parameters, initial water side operating parameters and initial system structure parameters into the first surface cooling energy conservation model to obtain first air side operating parameters, first water side operating parameters and first system structure parameters.

[0126] Specifically, it is assumed that the dew point temperatures of NMP on the gas side at the cooling stage and the condensation stage are T n1 and T n2 (℃), the dew point temperature at the outlet of the condensation section is T n3 (℃)(i.e. T n3 =T3), and the saturated moisture content at the corresponding temperature is L n1 , L n2 and L n3 (g / kg) and the heat of vaporization is H n1 , H n2 and H n3 (kJ / kg) (If NMP does not condense, it can be ignored accordingly). According to the energy conservation relationship between the air side and the water side, the first surface cooling energy conservation model can be established, which is expressed by the following formulas (1)-(3):

[0127]

[0128] S1=πdwβR1C1 (2);

[0129]

[0130] Among them, ρ a is the air side density, ρ w1 is the circulating water side density, t 11 is the circulating temperature of the circulating water low temperature point, T2 is the outlet temperature of the air side after the cooling surface cooler, is the average specific heat capacity of the air side of the cooling cooler, is the average specific heat capacity of the water side of the cooling surface cooler, Q n1 is the condensation latent heat generated by the air side passing through the cooling surface cooler, S1 is the heat exchange area of ​​the cooling surface cooler, Δt m1 is the logarithmic mean temperature difference of the cooling surface cooler, R1 is the number of coil rows of the cooling surface cooler, C1 is the number of holes in each row of the coil of the cooling surface cooler, and W1 is the circulating water volume of the circulating water.

[0131] Specifically, Figure 2 The process of processing parameters of the first cold energy conservation model is given, that is, step S2 includes:

[0132] Step S21: Obtain T2, T4 and Q1 according to the initial value η0 of the heat exchange efficiency, the exhaust air temperature T1, the return air temperature T3 and the first surface cooling energy conservation model;

[0133] Step S22: According to parameter t 12 , T1, T2, obtain ρ a and ρ w1 ;

[0134] Step S23: Set the parameters W1, ρ a and ρ w1 Input the first table cold energy conservation model to obtain Q n1 ,t 11 and S1;

[0135] Step S24: According to the parameter Q n1 ,t 11 and S1, obtain R1 and C1;

[0136] Step S25: Obtain updated S1 according to parameters R1 and C1;

[0137] Step S26: Based on the parameters T1, updated S1, W1, t 12And the first table cold energy conservation model, get the updated Q1, updated Q n1 , the first updated t 11 , the first updated T2;

[0138] Step S27: Based on the parameters T1, the first updated T2, and the first updated t 11 ,t 12 , get updated Updated

[0139] Step S28: Based on the updated Updated Get the second updated T2 and the second updated t 11 ;

[0140] Step S29: Determine whether the absolute difference between the second updated T2 and the first updated T2 is greater than or equal to 0.001;

[0141] Step S210: in response to the absolute difference between the second updated T2 and the first updated T2 being greater than or equal to 0.001, repeating steps S21-S29;

[0142] Step S211: Output the second updated T2 and the updated Q n1 , the second updated t 11 ,t 12 , R1 and C1 are used as the first gas side operating parameter, the first water side operating parameter and the first system structure parameter.

[0143] Step S3: inputting the first gas side operating parameter, the first water side operating parameter and the first system structure parameter into the second surface cooling energy conservation model to obtain the second gas side operating parameter, the second water side operating parameter and the second system structure parameter;

[0144] Specifically, the second surface cooling energy conservation model is expressed by the following formulas (4)-(6):

[0145]

[0146] S2=πdwβR2C2 (5);

[0147]

[0148] Among them, ρ2 is the density of the chilled water side, W2 is the inlet and outlet volume of the chilled water, is the average specific heat capacity of the air side of the condensing cooler, is the average specific heat capacity of the water side of the condensing cooler, Q n2 is the condensation latent heat generated by the gas side passing through the condenser, S2 is the heat exchange area of ​​the condenser, Δt m2is the logarithmic mean temperature difference of the condensing cooler, R2 is the number of coil rows of the condensing cooler, and C2 is the number of holes in each row of the coil of the condensing cooler.

[0149] Specifically, Figure 3 The process of processing parameters of the second cold energy conservation model is given, that is, step S3 includes:

[0150] Step S31: T2, T3, t 21 ,t 22 ,get and ρ w2 ;

[0151] Step S32: Set the parameters and ρ w2 Input the second cold energy conservation model to obtain Q2, Q n2 , W2 and S2;

[0152] Step S33: According to parameters Q2, Q n2 , W2 and S2, obtain R2 and C2;

[0153] Step S34: Obtain updated S2 according to parameters R2 and C2;

[0154] Step S35: Update the parameters S2, the second updated T2, and t 21 and t 22 Input the second table cold energy conservation model to obtain updated Q2 and updated Q n2 , first updated T3 and updated W2;

[0155] Step S36: Based on the parameters T2 of the second update, T3 of the first update, t 21 and t 22 , get updated Updated

[0156] Step S37: Update the parameters Updated Get the second updated T3 and the updated t 22 ;

[0157] Step S38: Determine whether the absolute difference between the second updated T3 and the first updated T3 is greater than or equal to 0.001;

[0158] Step S39: in response to the absolute difference between the second updated T3 and the first updated T3 being greater than or equal to 0.001, repeating steps S2 and S31-S38;

[0159] Step S310: Output the second updated T2 and the updated Q n1, the second updated t 11 ,t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2 are used as the second gas side operating parameter, the second water side operating parameter and the second system structure parameter.

[0160] Step S4: inputting the second gas side operating parameter, the second water side operating parameter and the second system structure parameter into the third surface cooling energy conservation model to obtain the third gas side operating parameter, the third water side operating parameter and the third system structure parameter;

[0161] Specifically, the third surface cooling energy conservation model is expressed by the following formulas (7)-(9):

[0162]

[0163] S3=πdwβR3C3 (8);

[0164]

[0165] Among them, T4 is the outlet temperature of the air side after passing through the heating surface cooler, is the average specific heat capacity of the air side of the heating surface cooler, S3 is the heat exchange area of ​​the heating surface cooler, Δt m3 is the logarithmic mean temperature difference of the heating surface cooler, R3 is the number of coil rows of the heating surface cooler, and C3 is the number of holes in each row of the coil of the heating surface cooler.

[0166] Specifically, Figure 4 The process of processing parameters of the third table cold energy conservation model is given, that is, step S4 includes:

[0167] Step S41: According to the second updated parameter T3, obtain

[0168] Step S42: Set the second updated parameters T3, W1, and t 11 ,t 12 and Input the third table cold energy conservation model to obtain the first updated T4 and S3;

[0169] Step S43: According to the second updated parameter T3 and the first updated parameter T4, obtain the updated

[0170] Step S44: Update the parameters Get the second updated T4;

[0171] Step S45: determining whether the absolute difference between the second updated T4 and the first updated T4 is greater than or equal to 0.001;

[0172] Step S46: in response to the absolute difference between the second updated T4 and the first updated T4 being greater than or equal to 0.001, repeating steps S41-S45;

[0173] Step S47: Substitute the second updated T4 and S3 to obtain R3 and C3;

[0174] Step S48: Obtain updated S3 according to parameters R3 and C3;

[0175] Step S49: Set the parameters of the second updated T3, the second updated T4, and the second updated t 11 and the updated S3 are input into the third table cold energy conservation model to obtain the updated W1, the first updated t 12 ;

[0176] Step S410: Obtain η according to the parameters T1, the second updated T3 and the second updated T4. k ;

[0177] Step S411: Obtain η according to parameters T1, T3 and T4 e ;

[0178] Step S412: Determine n k With η e Is the absolute difference between them less than 0.005?

[0179] Step S413: In response to n k With η e When the absolute difference between them is less than 0.005, the first updated T2 and the updated Q are output. n1 , the second updated t 11 , the first updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated r 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and η e As the third gas side operating parameter, the third water side operating parameter and the third system structure parameter; otherwise, execute step S5.

[0180] Step S5: determining whether the third gas side operating parameter, the third water side operating parameter and the first system structure parameter meet preset conditions;

[0181] Preferably, the preset conditions are expressed by formulas (10) and (11):

[0182] 0≤η e -η0≤0.1 (10);

[0183] |η k -η e |<0.005 (11);

[0184] in, in, For the second updated T4, This is the second updated T3.

[0185] Step S6: in response to the third air-side operating parameter, the third water-side operating parameter and the third system structure parameter satisfying the preset condition, the third air-side operating parameter, the third water-side operating parameter and the third system structure parameter are updated according to the first updating method and the updated third air-side operating parameter, the third water-side operating parameter and the third system structure parameter are output as the final air-side operating parameter, the final water-side operating parameter and the final system structure parameter of the three-stage surface cooling recovery system; otherwise, the third air-side operating parameter, the third water-side operating parameter and the third system structure parameter are updated according to the second updating method and the updated third air-side operating parameter, the third water-side operating parameter and the third system structure parameter are output as the final air-side operating parameter, the final water-side operating parameter and the final system structure parameter of the three-stage surface cooling recovery system;

[0186] In this embodiment, in order to ensure the high efficiency of the actual system operation, the parameters cannot be kept in an updated state all the time. In specific applications, the parameter settings in the method steps are subject to restrictions. When the parameter restrictions are reached, it is determined whether the parameters meet the current conditions, thereby searching for the optimal parameter value. If the restrictions are reached, the parameter value under the restrictions is output. This setting is to improve the efficiency of the entire method. In the actual program settings, it can be set as needed, which is specifically reflected in the process of the first update method and the second update method.

[0187] Specifically, the first updating method includes the following steps:

[0188] Step S611: Update the first updated parameter t 12 is the second updated t 12 , according to the second updated t 12 Update η k Get the first updated η k ;

[0189] Step S612: Determine the first updated n k With η e Is the absolute difference between them less than 0.005?

[0190] Step S613: In response to the first updated n k With ηe When the absolute difference between them is less than 0.005, repeat steps S2-S4 and S611-S612; otherwise, execute the second updating method;

[0191] Step S614: Output the second updated T2 and the updated Q n1 , the second updated t 11 , the second updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and first updated η k As the third gas side operating parameter, the third water side operating parameter and the third system structure parameter.

[0192] Specifically, the second updating method includes the following steps:

[0193] Step S621: Update the initial value η0 to obtain an updated initial value η0, and update η according to the updated initial value η0. k Get the second updated η k ;

[0194] Step S622: Determine the second updated n k With η e Is the absolute difference between them less than 0.005?

[0195] Step S623: In response to the second updated n k With η e When the absolute difference between them is less than 0.005, repeat steps S2-S5 and S621-S622; otherwise, execute steps S625-S626;

[0196] Step S624: Output the second updated η2 and the updated Q n1 , the second updated t 11 , the second updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and second updated η k As the third gas side operating condition parameter, the third water side operating condition parameter and the third system structure parameter, execute step S7;

[0197] Step S625: In the steps of the first updating method and the second updating method, select and execute n k With η eThe steps corresponding to the minimum absolute difference between them are performed to obtain the third updated η k ;

[0198] Step S626: Output the second updated T2 and the updated Q n1 , the second updated t 11 , the second updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and third updated η k As the third gas side operating parameter, the third water side operating parameter and the third system structure parameter.

[0199] In this embodiment, the parameters W1, t 12 、T2、T4、Q1、 and The initial value of is obtained by the following formula:

[0200] W1=2.3×10 -4 F;

[0201]

[0202] T2 = T1 - (T1 - T3) η0;

[0203] T4=T3+(T1-T3)η0;

[0204]

[0205] Among them, c w11 and c w21 are respectively the water side at temperature t 11 and t 21 The specific heat capacity under .

[0206] Specifically, during the update process, the parameter ρ a , ρ w1 , w2 , R1, R2, R3, C1, C2, C3, S1, S2, S3, Q1, and Q2 are updated using the following formula:

[0207]

[0208] S i =πdwβR i C i ,i=1,2,3;

[0209]

[0210] Among them, w is the wind width, h is the wind height, r is the coil hole distance, is the initial heat exchange area of ​​the surface cooler, S i is the heat exchange area of ​​the surface cooler, and the parameters of the above formula are obtained by the following formula:

[0211]

[0212] Among them, "[]" is a round-down operation, and "{}" is a small operation;

[0213] Among them, Q1 is the sensible heat generated by the air side through the cooling condenser, and Q2 is the sensible heat generated by the air side through the condensing condenser; a1 、c a2 、c a3 and c a4 are the specific heat capacities of the gas side at temperatures T1, T2, T3 and T4 respectively; c w12 and c w22 are respectively the water side at temperature t 12 and t 22 Specific heat capacity under w11 、c w12 、c w21 and c w22 It is obtained by the following formula:

[0214]

[0215]

[0216] Among them, Q n1 and Q n2 It is expressed by the following formula:

[0217]

[0218] Among them, T n1 is the dew point temperature at which NMP on the gas side condenses in the cooling condenser, T n2 T is the dew point temperature at which NMP on the gas side condenses in the condenser. n3 is the dew point temperature of NMP on the gas side at the outlet of the condenser. ni >0 satisfies T n(i+1) =T i+1 , L n1 , L n2 and Ln3 are dew point temperatures T n1 、T n2 and T n3 The saturated humidity of the air side under n1 , H n2and H n3 Dew point temperature T n1 , T n2 and T n3 Heat of vaporization on the lower gas side, T ni , L ni and H ni They are all determined by the initial NMP exhaust concentration q of the system.

[0219] In this embodiment, T ni , L ni and H ni The initial NMP exhaust concentration q of the system is determined by the exhaust concentration q of NMP in the exhaust gas and in the case of condensation, and its dew point temperature T n , saturated moisture content L n and heat of vaporization H n There is a one-to-one correspondence T n =t(q),L n = l(q) and H n =h(t(q)), which can be obtained by looking up a table or directly calculating in the program. The detailed relationship description is not given here.

[0220] Specifically, when the parameter iteration is stopped, the final third gas side operating parameters, the third water side operating parameters and the third system structure parameters are output to form a matrix Results 3×6 :

[0221]

[0222] Results 3×6 It is a parameter matrix composed of the final gas side operating parameters, the final water side operating parameters and the final system structure parameters.

[0223] Step S7: designing a three-stage surface cooling recovery system according to the final gas side operating parameters, the final water side operating parameters and the final system structure parameters of the three-stage surface cooling recovery system.

[0224] Specifically, according to Results 3×6 To design a three-stage surface cooling system.

[0225] Reference Figure 7 This embodiment discloses a NMP three-stage surface cooling recovery system 9, which includes a cooling surface cooler 91, a condensing surface cooler 92, a demister 93 and a heating surface cooler 94 arranged in sequence. The cooling surface cooler 91 and the heating surface cooler 94 form heat exchange through circulating water, and the condensing surface cooler 92 is cooled by chilled water. The three-stage surface cooling recovery system 9 is obtained by the design method of the aforementioned embodiment.

[0226] Figure 7At the same time, the overall process flow diagram of the three-stage surface cooling system for waste gas recovery is given, including the NMP three-stage surface cooling recovery system. The following is a complete process of NMP recovery:

[0227] (1) The NMP waste gas from the production equipment 1 is transported to the three-stage surface cooling system 9 by the exhaust fan 8 and treated. According to the actual process requirements, a small amount of NMP waste gas can be discharged to the outside. After the NMP waste gas enters the return air fan 3 through the air duct 4 and reaches the return air temperature requirement through the heater 2, it finally returns to the production equipment 1.

[0228] (2) In the three-stage surface cooling system 9, it is mainly divided into four areas, namely, the cooling section, the condensing section, the demisting section and the heating section. The cooling section, the condensing section and the heating section each contain a surface cooler, and the demisting section contains a demisting device 93. They are all encapsulated in a three-stage surface cooling box shell, and a set of NMP condensate recovery device is provided. Moreover, between the two surface coolers of the cooling section and the heating section, two circulating water pipes 5 and a circulating water pump 6 are provided to realize heat exchange between them; in the condensing section, the surface cooler is externally connected to a refrigerator 7, and the freezing water pipe is filled with freezing water to discharge heat.

[0229] (3) When the NMP waste gas (~100°C) passes through the cooling section, it will exchange heat with the low-temperature circulating water in the cooling surface cooler 91 and cool to a lower temperature (30~50°C). If the NMP concentration is high, a small amount of NMP may condense. When the NMP waste gas passes through the condensing section, it will exchange heat with the chilled water in the condensing section surface cooler and cool to a lower temperature (~15°C). At this time, a large amount of NMP will condense, and then the small droplets carried by the saturated NMP waste gas will be intercepted by the demister 93 in the demister section. In addition, the above-mentioned NMP condensate will be collected and recovered through a set of waste gas condensate recovery equipment. When the NMP waste gas passes through the heating section, it will exchange heat with the high-temperature circulating water in the heating surface cooler 94 and heat to a higher temperature (75~95°C).

[0230] The system provided in the embodiment of the present application can implement the above method, and the system can be implemented by software, hardware or a combination of software and hardware. For example, the system may include integrated or separate functional modules or units to perform the corresponding steps in the above methods. In some implementations of the embodiment of the present application, the system provided in the embodiment of the present application is based on the same inventive concept as the method provided in the previous embodiment of the present application, and has the same beneficial effect. No further description is given here.

[0231] It should be noted that the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of the boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0232] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0233] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0234] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0235] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0236] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0237] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application.

Claims

1. A design method for a three-stage NMP surface cooling recovery system, wherein the three-stage surface cooling recovery system comprises a cooling surface cooler, a condensing surface cooler, a demister and a heating surface cooler arranged in sequence, wherein the cooling surface cooler and the heating surface cooler form heat exchange through circulating water, and the condensing surface cooler is cooled by chilled water, wherein: The parameter design method comprises the following steps: Step S1: obtaining initial gas side operating parameters, initial water side operating parameters and initial system structure parameters of the three-stage surface cooling recovery system; Step S2: inputting the initial air side operating parameters, the initial water side operating parameters and the initial system structure parameters into the first surface cooling energy conservation model to obtain the first air side operating parameters, the first water side operating parameters and the first system structure parameters; Step S3: inputting the first gas side operating parameter, the first water side operating parameter and the first system structure parameter into the second surface cooling energy conservation model to obtain the second gas side operating parameter, the second water side operating parameter and the second system structure parameter; Step S4: inputting the second gas side operating parameter, the second water side operating parameter and the second system structure parameter into the third surface cooling energy conservation model to obtain the third gas side operating parameter, the third water side operating parameter and the third system structure parameter; Step S5: determining whether the third gas side operating parameter, the third water side operating parameter and the third system structure parameter meet preset conditions; Step S6: in response to the third gas-side operating parameter, the third water-side operating parameter and the third system structure parameter satisfying a preset condition, updating the third gas-side operating parameter, the third water-side operating parameter and the third system structure parameter according to the first updating method and outputting the updated third gas-side operating parameter, the third water-side operating parameter and the third system structure parameter as the final gas-side operating parameter, the final water-side operating parameter and the final system structure parameter of the three-stage surface cooling recovery system; Otherwise, the third gas side operating parameter, the third water side operating parameter and the third system structure parameter are updated according to the second updating method and the updated third gas side operating parameter, the third water side operating parameter and the third system structure parameter are output as the final gas side operating parameter, the final water side operating parameter and the final system structure parameter of the three-stage surface cooling recovery system; Step S7: designing the three-stage surface cooling recovery system according to the final gas side operating parameters, final water side operating parameters and final system structure parameters of the three-stage surface cooling recovery system.

2. The design method of a NMP three-stage cold recovery system according to claim 1, characterized in that: The initial air side operating parameters include exhaust air volume F, exhaust air temperature T1, NMP exhaust air concentration q, return air temperature T3, circulation ratio a, room temperature T S , relative humidity and the mass flow rate G of the three-stage surface cooling recovery system; The initial water side operating parameters include the circulating temperature t of the circulating water high temperature point 12 and water volume W1 and chilled water inlet temperature t 21 and outlet temperature t 22 ; The initial system structural parameters include the coil outer diameter d, the wing ratio β, the heat transfer area margin coefficient ε, the maximum limited wind width w * , heat transfer coefficient K1 of cooling surface cooler, heat transfer coefficient K2 of condensing surface cooler, heat transfer coefficient K3 of heating surface cooler, expected value η of heat exchange efficiency e And the initial value of heat exchange efficiency η0.

3. The design method of a NMP three-stage cold recovery system according to claim 2, characterized in that: The first table cold energy conservation model is expressed by the following formulas (1)-(3): S1=πdwβR1C1 (2); Among them, ρ a is the air side density, ρ w1 is the circulating water side density, t 11 is the circulating temperature of the circulating water low temperature point, T2 is the outlet temperature of the air side after the cooling surface cooler, is the average specific heat capacity of the air side of the cooling surface cooler, is the average specific heat capacity of the water side of the cooling surface cooler, Q n1 is the condensation latent heat generated by the air side passing through the cooling surface cooler, S1 is the heat exchange area of ​​the cooling surface cooler, Δt m1 is the logarithmic mean temperature difference of the cooling surface cooler, R1 is the number of coil rows of the cooling surface cooler, C1 is the number of holes in each row of the coil of the cooling surface cooler, and W1 is the circulating water volume of the circulating water.

4. The design method of a NMP three-stage cold recovery system according to claim 3, characterized in that: The second table cold energy conservation model is expressed by the following formulas (4)-(6): S2=πdwβR2C2 (5); Among them, ρ w2 is the density of the chilled water side, W2 is the inlet and outlet volume of the chilled water, is the average specific heat capacity of the air side of the condensing cooler, is the average specific heat capacity of the water side of the condensing cooler, Q n2 is the condensation latent heat generated by the gas side passing through the condenser, S2 is the heat exchange area of ​​the condenser, Δt m2 is the logarithmic mean temperature difference of the condensing cooler, R2 is the number of coil rows of the condensing cooler, and C2 is the number of holes in each row of the coil of the condensing cooler.

5. The design method of a NMP three-stage cold recovery system according to claim 4, characterized in that: The third table cold energy conservation model is expressed by the following formulas (7)-(9): S3=πdwβR3C3 (8); Among them, T4 is the outlet temperature of the air side after passing through the heating surface cooler, is the average specific heat capacity of the air side of the heating surface cooler, S3 is the heat exchange area of ​​the heating surface cooler, Δt m3 is the logarithmic mean temperature difference of the heating surface cooler, Q3 is the number of coil rows of the heating surface cooler, and C3 is the number of holes in each row of the coil of the heating surface cooler.

6. The design method of a NMP three-stage surface cooling recovery system according to claim 5, characterized in that: Step S2 includes: Step S21: Obtain T2, T4 and Q1 according to the initial value η0 of the heat exchange efficiency, the exhaust air temperature T1, the return air temperature T3 and the first surface cooling energy conservation model; Step S22: According to parameter t 12 , T1, T2, obtain ρ a and ρ w1 ; Step S23: Set the parameters W1, ρ a and ρ w1 Input the first table cold energy conservation model to obtain Q n1 ,t 11 and S1; Step S24: According to the parameter Q n1 ,t 11 and S1, obtain R1 and C1; Step S25: Obtain updated S1 according to parameters R1 and C1; Step S26: Based on the parameters T1, updated S1, W1, t 12 And the first table cold energy conservation model, get the updated Q1, updated Q n1 , the first updated t 11 , the first updated T2; Step S27: Based on the parameters T1, the first updated T2, and the first updated t 11 ,t 12 , get updated Updated Step S28: Based on the updated Updated Get the second updated T2 and the second updated t 11 ; Step S29: Determine whether the absolute difference between the second updated T2 and the first updated T2 is greater than or equal to 0.001; Step S210: in response to the absolute difference between the second updated T2 and the first updated T2 being greater than or equal to 0.001, repeating steps S21-S29; Step S211: Output the second updated T2 and the updated Q n1 , the second updated t 11 ,t 12 , R1 and C1 are used as the first gas side operating parameter, the first water side operating parameter and the first system structure parameter.

7. The design method of a NMP three-stage surface cooling recovery system according to claim 6 is characterized in that: Step S3 includes: Step S31: T2, T3, t 21 ,t 22 ,get and ρ w2 ; Step S32: Set the parameters and ρ w2 Input the second cold energy conservation model to obtain Q2, Q n2 , W2 and S2; Step S33: According to parameters Q2, Q n2 , W2 and S2, obtain R2 and C2; Step S34: Obtain updated S2 according to parameters R2 and C2; Step S35: Update the parameters S2, the second updated T2, and t 21 and t 22 Input the second table cold energy conservation model to obtain updated Q2 and updated Q n2 , first updated T3 and updated W2; Step S36: Based on the parameters T2 of the second update, T3 of the first update, t 21 and t 22 , get updated Updated Step S37: Update the parameters Updated Get the second updated T3 and the updated t 22 ; Step S38: Determine whether the absolute difference between the second updated T3 and the first updated T3 is greater than or equal to 0.001; Step S39: in response to the absolute difference between the second updated T3 and the first updated T3 being greater than or equal to 0.001, repeating steps S2 and S31-S38; Step S310: Output the second updated T2 and the updated Q n1 , the second updated t 11 ,t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2 are used as the second gas side operating parameter, the second water side operating parameter and the second system structure parameter.

8. The design method of a NMP three-stage surface cooling recovery system according to claim 7, characterized in that: Step S4 includes: Step S41: According to the second updated parameter T3, obtain Step S42: Set the second updated parameters T3, W1, and t 11 ,t 12 and Input the third table cold energy conservation model to obtain the first updated T4 and S3; Step S43: According to the second updated parameter T3 and the first updated parameter T4, obtain the updated Step S44: Update the parameters Get the second updated T4; Step S45: determining whether the absolute difference between the second updated T4 and the first updated T4 is greater than or equal to 0.001; Step S46: in response to the absolute difference between the second updated T4 and the first updated T4 being greater than or equal to 0.001, repeating steps S41-S45; Step S47: Substitute the second updated T4 and S3 to obtain R3 and C3; Step S48: Obtain updated S3 according to parameters R3 and C3; Step S49: Set the parameters of the second updated T3, the second updated T4, and the second updated t 11 and the updated S3 are input into the third table cold energy conservation model to obtain the updated W1, the first updated t 12 ; Step S410: Obtain η according to the parameter T1, the second updated T3 and the second updated T4; Step S411: Obtain η according to parameters T1, T3 and T4 e ; Step S412: Determine n k With η e Is the absolute difference between them less than 0.005? Step S413: In response to n k With η e When the absolute difference between them is less than 0.005, the first updated T2 and the updated Q are output. n1 , the second updated T 11 , the first updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and η e As the third gas side operating parameter, the third water side operating parameter and the third system structure parameter; otherwise, execute step S5.

9. The design method of a NMP three-stage surface cooling recovery system according to claim 8, characterized in that: The preset conditions are expressed by formulas (10) and (11): 0≤η e -η0≤0.1 (10); |the k -or e |<0.005 (11); in, in, For the second updated T4, This is the second updated T3.

10. The design method of a NMP three-stage surface cooling recovery system according to claim 9, characterized in that: The first updating method comprises the following steps: Step S611: Update the first updated parameter t 12 is the second updated t 12 , according to the second updated t 12 Update η k Get the first updated η k ; Step S612: Determine the first updated n k With η e Is the absolute difference between them less than 0.005? Step S613: In response to the first updated n k With η e When the absolute difference between them is less than 0.005, repeat steps S2-S4 and S611-S612; otherwise, execute the second updating method; Step S614: Output the second updated T2 and the updated Q n1 , the second updated t 11 , the second updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and first updated η k As the third gas side operating parameter, the third water side operating parameter and the third system structure parameter.

11. The design method of a NMP three-stage surface cooling recovery system according to claim 10, characterized in that: The second updating method comprises the following steps: Step S621: Update the initial value η0 to obtain an updated initial value η0, and update η according to the updated initial value η0. k Get the second updated η k ; Step S622: Determine the second updated n k With η e Is the absolute difference between them less than 0.005? Step S623: In response to the second updated n k With η e When the absolute difference between them is less than 0.005, repeat steps S2-S5 and S621-S622; Otherwise, execute steps S625-S626; Step S624: Output the second updated T2 and the updated Q n1 , the second updated t 11 , the second updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and second updated η k As the third gas side operating condition parameter, the third water side operating condition parameter and the third system structure parameter, execute step S7; Step S625: In the steps of the first updating method and the second updating method, select and execute n k With η e The steps corresponding to the minimum absolute difference between them are performed to obtain the third updated η k ; Step S626: Output the second updated T2 and the updated Q n1 , the second updated t 11 , the second updated t 12 , R1 and C1, second updated T3, updated Q n2 ,t 21 , updated t 22 , R2 and C2, updated W1, updated W2, R3 and C3, second updated T4 and third updated η k As the third gas side operating parameter, the third water side operating parameter and the third system structure parameter.

12. The design method of a NMP three-stage surface cooling recovery system according to claim 11, characterized in that: Parameters W1, t 12 、T2、T4、Q1、 and The initial value of is obtained by the following formula: W1=2.3×10 -4 F; T2 = T1 - (T1 - T3) η0; T4=T3+(T1-T3)η0; Among them, c w11 and c w21 are respectively the water side at temperature t 11 and t 21 The specific heat capacity under .

13. The design method of a NMP three-stage surface cooling recovery system according to claim 12, characterized in that: During the update process, the parameter ρ a , ρ w1 , w2 , R1, R2, R3, C1, C2, C3, S1, S2, S3, Q1, and Q2 are updated using the following formula: S i =πdwβR i C i ,i=1,2,3; Among them, w is the wind width, h is the wind height, r is the coil hole distance, is the initial heat exchange area of ​​the surface cooler, S i is the heat exchange area of ​​the surface cooler, and the parameters of the above formula are obtained by the following formula: Among them, "[]" is a rounding operation, and "{}" is a rounding operation; Among them, Q1 is the sensible heat generated by the air side through the cooling condenser, and Q2 is the sensible heat generated by the air side through the condensing condenser; a1 、c a2 、c a3 and c a4 are the specific heat capacities of the gas side at temperatures T1, T2, T3 and T4 respectively; c w12 and c w22 are respectively the water side at temperature t 12 and t 22 Specific heat capacity under w11 、c w12 、c w21 and c w22 It is obtained by the following formula: Among them, Q n1 and Q n2 It is expressed by the following formula: Among them, T n1 is the dew point temperature at which NMP on the gas side condenses in the cooling condenser, T n2 T is the dew point temperature at which NMP on the gas side condenses in the condenser. n3 is the dew point temperature of NMP on the gas side at the outlet of the condenser. ni >0 satisfies Tn (i+1) =T i+1 , L n1 , L n2 and L n3 Dew point temperature T n1 , T n2 and T n3 The saturated humidity of the air side under n1 , H n2 and H n3 Dew point temperature T n1 , T n2 and T n3 Heat of vaporization on the lower gas side, T ni , L ni and H ni They are all determined by the initial NMP exhaust concentration q of the system.

14. A NMP three-stage surface cooling recovery system designed according to the method of any one of claims 1 to 13, characterized in that: The three-stage surface cooling recovery system includes a cooling surface cooler, a condensing surface cooler, a defogger and a heating surface cooler arranged in sequence. Heat exchange is formed between the cooling surface cooler and the heating surface cooler through circulating water, and the condensing surface cooler is cooled by chilled water.

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