Tubular heat exchanger blockage online diagnosis method and tubular heat exchanger

Abstract

The invention provides a tubular heat exchanger blockage online diagnosis method and a tubular heat exchanger. The tubular heat exchanger blockage online diagnosis method comprises the following steps: constructing a C factor based on a resistance coefficient and a heat transfer coefficient of the tubular heat exchanger; and performing online diagnosis on the blockage degree of the tubular heat exchanger by detecting the change trend of the C factor. According to the technical scheme, the C factor is constructed based on the resistance coefficient and the heat transfer coefficient of the tubular heat exchanger; performing online diagnosis on the blockage degree of the tubular heat exchanger by detecting the change trend of the C factor; by constructing the C factor reflecting the blockage degree of the heat exchanger, a diagnosis basis is provided for whether the tubular heat exchanger is blocked or not.

Description

Background Art

[0002] Shell and tube heat exchanger is a kind of equipment that uses the principle of convection and heat transfer to exchange heat. It is mainly used in oil refining, chemical industry, steel, thermal power and food industries. Its advantages include large heat transfer area, low cost and easy maintenance. The heat exchanger consists of shell, tube bundle, baffle and head, in which cooling water flows in the tube bundle and hot process flow flows outside the tube.

[0003] Heat exchanger blockage is one of the main problems it faces, and blockage will significantly affect the heat exchange efficiency. However, most heat exchanger blockages occur at the inlet of the tubes, and this blockage is difficult to judge and evaluate from the appearance. For large-scale production companies, the number of heat exchangers is usually large, and it is difficult for technicians to monitor and analyze each heat exchanger in real time. Most of the current heat exchanger cleaning methods need to be carried out during shutdown maintenance or standby heat exchanger status, and cannot be implemented during equipment operation. Once a heat exchanger is seriously blocked, it may cause the entire production process to be interrupted, causing huge losses to the company. Summary of the invention

[0004] The present application provides an online diagnosis method for blockage of a shell-and-tube heat exchanger and a shell-and-tube heat exchanger, so as to realize real-time diagnosis and backwashing of blockage of the shell-and-tube heat exchanger.

[0005] In a first aspect, a method for online diagnosis of blockage of a shell-and-tube heat exchanger is provided, comprising the following steps:

[0006] Construct the C factor based on the resistance coefficient and heat transfer coefficient of the shell-and-tube heat exchanger;

[0007] By detecting the change trend of the C factor, the blockage degree of the shell-and-tube heat exchanger is diagnosed online.

[0008] In the above technical scheme, a C factor is constructed based on the resistance coefficient and heat transfer coefficient of the shell-and-tube heat exchanger; the blockage degree of the shell-and-tube heat exchanger is diagnosed online by detecting the change trend of the C factor; and a C factor reflecting the blockage degree of the heat exchanger is constructed to provide a diagnostic basis for whether the shell-and-tube heat exchanger has a blockage problem.

[0009] In a specific implementation scheme, the calculation formula of the C factor is:

[0010] C=C k +C K ;

[0011] Among them, C k is the resistance coefficient of the shell-and-tube heat exchanger after dimensionless processing, C K is the heat transfer coefficient of the shell and tube heat exchanger treated as dimensionless.

[0012] In a specific embodiment, the resistance coefficient C of the dimensionless shell-and-tube heat exchanger is k The calculation formula is:

[0013] C k =(k / k0-1)×100%;

[0014] The heat transfer coefficient C of the shell and tube heat exchanger treated without dimension K The calculation formula is:

[0015] C K =(K / K0-1)×100%;

[0016] Among them, k0 is the resistance coefficient of the shell-and-tube heat exchanger in a clean state, K0 is the heat transfer coefficient of the shell-and-tube heat exchanger in a clean state; k and K are the resistance coefficient and heat transfer coefficient of the real-time shell-and-tube heat exchanger, respectively.

[0017] In a specific implementation scheme, the calculation formula for the resistance coefficient k of the real-time shell-and-tube heat exchanger is:

[0018] ΔP E =kQ 2 ;

[0019] Among them, ΔP E is the inlet and outlet pressure drop of the cooling water side of the shell and tube heat exchanger, Q is the cooling water flow rate in the shell and tube heat exchanger, m 3 / h.

[0020] In a specific implementation scheme, the inlet and outlet pressure drop ΔP of the cooling water side of the shell and tube heat exchanger is E The calculation formula is:

[0021] ΔP E =(ΔP L +ΔP r )F t +ΔP N ;

[0022]

[0023] ΔP r =(ρv 2 / 2)(4N p );

[0024]

[0025] Q=(πD 2 / 4)V=nπd 2 v / 4N P ;

[0026] Among them, Ft is the scaling correction coefficient of the tube pass; v is the flow rate of cooling water in the tube; d is the inner diameter of the tube; D is the inner diameter of the heat exchanger inlet pipe; V is the flow rate of cooling water in the heat exchanger inlet pipe; ρ is the density of cooling water; n is the number of tubes; L is the length of the tube, m; N P is the number of tube passes; f D is the friction coefficient inside the tube; is the fluid viscosity correction factor; G N is the mass flow rate of cooling water flowing through the inlet and outlet pipes of the heat exchanger, kg / (m 2 ·s); Q is the cooling water flow rate in the shell-and-tube heat exchanger, m 3 / h.

[0027] In a specific implementation scheme, the calculation formula of the heat transfer coefficient K of the real-time shell and tube heat exchanger is:

[0028] KΔt m A=C w ρQΔt;

[0029]

[0030] Among them, C W is the specific heat capacity of water; Q is the flow value; ρ is the density of cooling water; A is the total heat transfer area of ​​the shell and tube heat exchanger, m 2 ; Δt is the difference between the outlet and inlet temperatures of the cooling water in the shell-and-tube heat exchanger, °C; Δt m is the logarithmic mean temperature difference between the hot and cold fluids in the shell-and-tube heat exchanger, °C; Δt max With Δt min is the larger and smaller temperature difference at both ends of the shell and tube heat exchanger, ℃; ψ′ is the correction coefficient for cross flow.

[0031] In a second aspect, a shell-and-tube heat exchanger is provided, comprising: a shell-and-tube heat exchanger body and a backwash pipeline, wherein:

[0032] The backwash pipeline is used to backwash the shell-and-tube heat exchanger body.

[0033] In the above technical solution, by setting up a backwash pipeline, backwashing is achieved by utilizing water supply pressure, which is not only suitable for low-position heat exchangers, but also has a good cleaning effect on high-position heat exchangers; the structure is simple and the operation is convenient, and there is no need to stop the machine during backwashing, so it is very economical and is conducive to reducing the number of cleaning and maintenance times of the shell-and-tube heat exchanger.

[0034] In a specific implementation manner, the backwash pipeline includes a connecting pipe and a control valve arranged on the connecting passage.

[0035] In a specific implementation scheme, the connecting pipeline includes pipeline three and pipeline four, the control valve includes valve three, valve four and valve five, and the shell and tube heat exchanger body includes cooling water inlet one and cooling water inlet two, wherein:

[0036] The pipeline 3 is connected to the cooling water inlet 1 and the cooling water inlet 2; the pipeline 4 is connected to the cooling water inlet 1 and is used to discharge the backwash sewage;

[0037] The valve three and the valve four are arranged on the pipeline three; the valve five is arranged on the pipeline four.

[0038] In a specific implementation scheme, it also includes pipeline 1 and pipeline 2, wherein,

[0039] The pipeline 1 is connected to the cold water inlet 1, and the pipeline 1 is provided with a pressure gauge 1 and a flow meter;

[0040] The second pipeline is connected to the second cooling water inlet, and a second pressure gauge is arranged on the second pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A flowchart of an online diagnosis method for blockage of a shell-and-tube heat exchanger provided in an embodiment of the present application;

[0042] Figure 2 A schematic diagram (stereoscopic diagram) of the structure of a shell-and-tube heat exchanger provided in an embodiment of the present application;

[0043] Figure 3 A schematic diagram of the structure of a shell-and-tube heat exchanger provided in an embodiment of the present application (normal operation);

[0044] Figure 4 A schematic diagram of the structure of a shell and tube heat exchanger (backwash) provided in an embodiment of the present application.

[0045] Among them, 1. Shell, 2. Tube bundle, 3. Baffle, 4. Process flow inlet, 5. Process flow outlet, 6. Head, 7. Cooling water inlet 1, 8. Cooling water inlet 2, 9. Pipeline 1, 10. Flow meter, 11. Valve 1, 12. Pressure gauge 1, 13. Pipeline 2, 14. Pressure gauge 2, 15. Valve 2, 16. Valve 3, 17. Pipeline 3, 18. Valve 4, 19. Valve 5, 20. Pipeline 4, 21. Ground, 22. Underground water inlet pipeline, 23. Underground water outlet pipeline, 24. Ground drainage ditch. DETAILED DESCRIPTION

[0046] The present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0047] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0048] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0049] To facilitate understanding of the online diagnosis method for blockage of a shell-and-tube heat exchanger and the shell-and-tube heat exchanger provided in the embodiment of the present application, its application scenario is first explained. The online diagnosis method for blockage of a shell-and-tube heat exchanger and the shell-and-tube heat exchanger provided in the embodiment of the present application are used to realize real-time diagnosis and backwashing of blockage of a shell-and-tube heat exchanger. A shell-and-tube heat exchanger is a device that uses the principles of convection and heat transfer to exchange heat, and is mainly used in industries such as oil refining, chemical industry, steel, thermal power and food. Its advantages include large heat transfer area, low cost, and easy maintenance. The heat exchanger consists of a shell, a tube bundle, a baffle and a head, wherein cooling water flows in the tube bundle and the hot process flow flows outside the tube. Blockage of the heat exchanger is one of the main problems it faces, and blockage will significantly affect the heat exchange efficiency. However, most heat exchanger blockages occur at the inlet of the tube, and this blockage is difficult to judge and evaluate from the appearance. For large-scale production enterprises, the number of heat exchangers is usually large, and it is difficult for technicians to monitor and analyze each heat exchanger in real time. Most of the current heat exchanger cleaning methods need to be carried out during shutdown for maintenance or standby heat exchanger status, and cannot be implemented during equipment operation. Once a heat exchanger is seriously blocked, the entire production process may be interrupted, causing huge losses to the company. For this reason, the embodiment of the present application provides an online diagnosis method for shell-and-tube heat exchanger blockage and a shell-and-tube heat exchanger to achieve real-time diagnosis and backwashing of shell-and-tube heat exchanger blockage. The following is a detailed description of the embodiment in conjunction with specific drawings.

[0050] refer to Figures 1 to 4 , Figure 1 A flowchart of an online diagnosis method for blockage of a shell-and-tube heat exchanger provided in an embodiment of the present application; Figure 2 A schematic diagram (stereoscopic diagram) of the structure of a shell-and-tube heat exchanger provided in an embodiment of the present application; Figure 3 A schematic diagram of the structure of a shell-and-tube heat exchanger provided in an embodiment of the present application (normal operation); Figure 4 A schematic diagram of the structure of a shell and tube heat exchanger (backwash) provided in an embodiment of the present application.

[0051] exist Figure 1 In the embodiment of the present application, a method for online diagnosis of blockage of a shell-and-tube heat exchanger is provided, comprising the following steps:

[0052] Construct the C factor based on the resistance coefficient and heat transfer coefficient of the shell-and-tube heat exchanger;

[0053] By detecting the change trend of the C factor, the blockage degree of the shell-and-tube heat exchanger is diagnosed online.

[0054] In the above technical scheme, a C factor is constructed based on the resistance coefficient and heat transfer coefficient of the shell-and-tube heat exchanger; the blockage degree of the shell-and-tube heat exchanger is diagnosed online by detecting the change trend of the C factor; and a C factor reflecting the blockage degree of the heat exchanger is constructed to provide a diagnostic basis for whether the shell-and-tube heat exchanger has a blockage problem.

[0055] In a specific implementation scheme, the calculation formula of the C factor is:

[0056] C=C k +C K ;

[0057] Among them, C k is the resistance coefficient of the shell-and-tube heat exchanger after dimensionless processing, C K is the heat transfer coefficient of the shell and tube heat exchanger treated as dimensionless.

[0058] In a specific embodiment, the resistance coefficient C of the dimensionless shell-and-tube heat exchanger is k The calculation formula is:

[0059] C k =(k / k0-1)×100%;

[0060] The heat transfer coefficient C of the shell and tube heat exchanger treated without dimension K The calculation formula is:

[0061] C K =(K / K0-1)×100%;

[0062] Among them, k0 is the resistance coefficient of the shell-and-tube heat exchanger in a clean state, K0 is the heat transfer coefficient of the shell-and-tube heat exchanger in a clean state; k and K are the resistance coefficient and heat transfer coefficient of the real-time shell-and-tube heat exchanger, respectively.

[0063] In a specific implementation scheme, the calculation formula for the resistance coefficient k of the real-time shell-and-tube heat exchanger is:

[0064] ΔP E =kQ 2 ;

[0065] Where ΔP E is the inlet and outlet pressure drop of the cooling water side of the shell and tube heat exchanger, Q is the cooling water flow rate in the shell and tube heat exchanger, m 3 / h.

[0066] In a specific implementation scheme, the inlet and outlet pressure drop ΔP of the cooling water side of the shell and tube heat exchanger is E The calculation formula is:

[0067] ΔP E =(ΔP L +ΔP r )F t +ΔP N ;

[0068]

[0069] ΔP r =(ρv 2 / 2)(4N p );

[0070]

[0071] Q=(πD 2 / 4)V=nπd 2 v / 4N P ;

[0072] Among them, F t is the scaling correction coefficient of the tube pass; v is the flow rate of cooling water in the tube; d is the inner diameter of the tube; D is the inner diameter of the heat exchanger inlet pipe; V is the flow rate of cooling water in the heat exchanger inlet pipe; ρ is the density of cooling water; n is the number of tubes; L is the length of the tube, m; N P is the number of tube passes; f D is the friction coefficient inside the tube; is the fluid viscosity correction factor; G N is the mass flow rate of cooling water flowing through the inlet and outlet pipes of the heat exchanger, kg / (m 2 ·s); Q is the cooling water flow rate in the shell-and-tube heat exchanger, m 3 / h.

[0073] In a specific implementation scheme, the calculation formula of the heat transfer coefficient K of the real-time shell and tube heat exchanger is:

[0074] KΔt m A=C w ρQΔt;

[0075]

[0076] Among them, C W is the specific heat capacity of water; Q is the flow value; ρ is the density of cooling water; A is the total heat transfer area of ​​the shell and tube heat exchanger, m 2 ; Δt is the difference between the outlet and inlet temperatures of the cooling water in the shell-and-tube heat exchanger, °C; Δt mis the logarithmic mean temperature difference between the hot and cold fluids in the shell-and-tube heat exchanger, °C; Δt max With Δt min is the larger and smaller temperature difference at both ends of the shell and tube heat exchanger, ℃; ψ′ is the correction coefficient for cross flow.

[0077] Specifically, the implementation process of the online diagnosis method for blockage of a shell-and-tube heat exchanger is as follows:

[0078] When cooling water flows through the heat exchanger, there are various flow resistances, including: total pressure drop ΔP E , resistance loss along the pipe section ΔP L , bending resistance loss ΔP r And the heat exchanger inlet and outlet resistance loss ΔP N , which are respectively expressed as:

[0079] ΔP E =(ΔP L +ΔP r )F t +ΔP N (1)

[0080]

[0081] ΔP r =(ρv 2 / 2)(4N p ) (3)

[0082]

[0083] According to the law of conservation of flow:

[0084] Q=(πD 2 / 4)V=nπd 2 v / 4N P (5)

[0085] Where: F t ——Tube scaling correction coefficient; v-------the flow rate of cooling water in the tube; d-------the inner diameter of the tube; D------the inner diameter of the heat exchanger inlet pipe; V------the flow rate of cooling water in the heat exchanger inlet pipe; ρ----the density of cooling water; n——the number of tubes; L——the length of the tube, m; N P ——Number of pipe passes; f D ——friction coefficient inside the tube; ——Fluid viscosity correction factor; G N ——The mass flow rate of cooling water flowing through the inlet and outlet pipes of the heat exchanger, kg / (m 2 ·s); Q——cooling water flow rate in the heat exchanger, m 3 / h.

[0086] According to formulas (1)-(5), it can be found that the inlet and outlet pressure drop ΔP on the cooling water side of the heat exchanger is E It can be expressed as kQ 2 , that is, ΔP E =kQ 2 Among them, k is called the comprehensive resistance coefficient of the cooling water side of the heat exchanger. Two pressure signal sensors can be installed for the cooling water inlet and outlet of the heat exchanger (refer to Figure 2 , i.e., pressure gauge 1 12 and pressure gauge 2 14) read the inlet and outlet static pressure values ​​P1 and P2 to obtain the heat exchanger pressure drop ΔP E A flow meter (ie, flow meter 10) may be installed on the inlet pipe to read the flow value Q.

[0087] On the other hand, the heat transfer capacity of the heat exchanger decreases after being blocked, and the heat transfer coefficient K will decrease. The heat transfer coefficient K can be calculated by the heat exchanger cooling water inlet and outlet temperatures t1, t2 and the high-temperature process side inlet and outlet temperatures T1, T2. Among them, the cooling water inlet and outlet temperatures are measured by thermometer 1 and thermometer 2 (not shown in the figure) set on pipeline 1 9 and pipeline 2 13; the high-temperature process side inlet and outlet temperatures are measured by thermometer 3 and thermometer 4 (not shown in the figure) set at the process flow inlet 4 and process flow outlet 5.

[0088] According to the principle of thermal balance:

[0089] KΔt m A=C w ρQΔt (8)

[0090] in,

[0091]

[0092] In the formula, C W -----Specific heat capacity of water; Q-------flow value; ρ------density of cooling water; A——total heat transfer area of ​​heat exchanger, m 2 ; Δt——the difference between the outlet temperature and inlet temperature of the cooling water in the heat exchanger, ℃; Δt m ——Logarithmic mean temperature difference between hot and cold fluids in heat exchanger, °C; Δt max With Δt min ——The larger and smaller temperature difference between the two ends of the heat exchanger, ℃; reference Figure 3 The temperature difference between the two ends of the heat exchanger refers to: the temperature difference between the process flow outlet 5 and the temperature of pipe 1 9, and the temperature difference between the process flow inlet 4 and pipe 2 13. ψ′——Correction coefficient for cross flow, which can be found in the heat transfer manual. Shell and tube heat exchangers include three conditions: co-current, counter-current, and cross-current. The value for co-current and counter-current is 1.

[0093] Let the resistance coefficient of the heat exchanger in the clean state be k0, that is, k0 is the k value calculated in the clean state, and the heat transfer coefficient be K0, that is, K0 is the K value calculated in the clean state. For different heat exchangers, k0 and K0 are different after the heat exchanger structure is determined, and k0 and K0 of the same heat exchanger at different times may also be different, so the resistance coefficient and heat transfer coefficient are dimensionless. Let,

[0094] C k =(k / k0-1)×100% (10)

[0095] C K =(K / K0-1)×100% (11)

[0096] Introducing the C factor,

[0097] C=C k +C K (12)

[0098] The more serious the blockage, the larger the k value, the larger the K value, and the larger the C factor. Compared with analyzing one of the resistance coefficient or the heat transfer coefficient, this method can more sensitively diagnose the blockage degree of the heat exchanger by monitoring the change trend of the C factor.

[0099] exist Figures 2 to 4 In the embodiment of the present application, a shell-and-tube heat exchanger is provided, comprising: a shell-and-tube heat exchanger body and a backwash pipeline, wherein:

[0100] The backwash pipeline is used to backwash the shell-and-tube heat exchanger body.

[0101] In the above technical solution, by setting up a backwash pipeline, backwashing is achieved by utilizing water supply pressure, which is not only suitable for low-position heat exchangers, but also has a good cleaning effect on high-position heat exchangers; the structure is simple and the operation is convenient, and there is no need to stop the machine during backwashing, so it is very economical and is conducive to reducing the number of cleaning and maintenance times of the shell-and-tube heat exchanger.

[0102] In a specific implementation manner, the backwash pipeline includes a connecting pipe and a control valve arranged on the connecting passage.

[0103] In a specific implementation scheme, the connecting pipeline includes pipeline three and pipeline four, the control valve includes valve three, valve four and valve five, and the shell and tube heat exchanger body includes cooling water inlet one and cooling water inlet two, wherein:

[0104] The pipeline 3 is connected to the cooling water inlet 1 and the cooling water inlet 2; the pipeline 4 is connected to the cooling water inlet 1 and is used to discharge the backwash sewage;

[0105] The valve three and the valve four are arranged on the pipeline three; the valve five is arranged on the pipeline four.

[0106] In a specific implementation scheme, it also includes pipeline 1 and pipeline 2, wherein,

[0107] The pipeline 1 is connected to the cold water inlet 1, and the pipeline 1 is provided with a pressure gauge 1 and a flow meter;

[0108] The second pipeline is connected to the second cooling water inlet, and a second pressure gauge is arranged on the second pipeline.

[0109] refer to Figure 3 and Figure 4 The working process of online diagnosis and backwashing of shell and tube heat exchanger blockage is as follows:

[0110] like Figure 3 As shown, the hot process fluid flows in from the process flow inlet 4 above, flows from right to left around the deflection baffle 3 inside the shell 1 and outside the tube bundle 2, and flows out from the process flow outlet 5 after heat exchange with the cooling water flowing from left to right inside the tube bundle.

[0111] During normal operation, the cooling water flows in the following direction: Figure 3 As shown, at this time, valve 11 and valve 2 15 are in a fully open state, while valve 3 16, valve 4 18 and valve 5 19 are in a fully closed state. The cooling water flows into pipe 1 9 from the underground water inlet pipe 22, and flows into the shell-and-tube heat exchanger through pipe 1 9 and cooling water inlet 1 7. The flow rate Q and the inlet static pressure P1 value are measured by flow meter 10 and pressure gauge 1 12 respectively, and the cooling water inlet temperature is measured by thermometer 1, and the process side outlet temperature is measured by thermometer 4. The cooling water flows in the tube bundle 2 and exchanges heat with the process flow outside the tube bundle 2, and then flows out to the underground water outlet pipe 23 through cooling water inlet 2 8 and pipe 2 13, and then is sent to the cooling tower for cooling. The outlet static pressure P2 value is measured by pressure gauge 2 14, and the cooling water outlet temperature is measured by thermometer 2, and the process side inlet temperature is measured by thermometer 3. The pressure signal, flow signal, and temperature signal are transmitted to DCS, and then by monitoring the C factor, it can be understood in real time whether the shell-and-tube heat exchanger is blocked and the degree of blockage.

[0112] During backwashing, the cooling water flows in the following direction: Figure 4As shown, at this time, valve 11 and valve 2 15 are in a fully closed state, while valve 3 16, valve 4 18 and valve 5 19 are in a fully open state. The circulating cooling water is pressurized by the circulating pump and flows through the underground water inlet pipe 22 into pipe 1 9, and flows into the shell-and-tube heat exchanger through pipe 1 9, pipe 3 17 and cooling water port 2 8. The flow rate Q and the inlet static pressure P1 value are measured by flow meter 10 and pressure gauge 2 14 respectively. The cooling water flows in the tube bundle 2 and exchanges heat with the process flow outside the tube bundle 2. It flows out to the ground drain through cooling water port 1 7 and pipe 4 20. The C factor is monitored to determine whether the blockage has been removed. When the C factor value of the heat exchanger increases, the blockage can be effectively cleared by switching the valve open and closed and turning on the backwash device. During backwashing, the cooling water flows in the reverse direction inside the tube bundle of the shell-and-tube heat exchanger, and the discharged cooling water and the blocked mixed flow are discharged to the ground drain.

[0113] In the above technical solution, backwashing is achieved by using water supply pressure, which is not only suitable for low-level heat exchangers, but also has a good cleaning effect on high-level heat exchangers. In addition, the device has a simple structure and is easy to operate, and it does not require shutdown during backwashing, so it is very economical and helps to reduce the number of cleaning and maintenance times of shell-and-tube heat exchangers. By remotely monitoring the flow rate Q and the inlet and outlet pressures P1 and P2 on the cooling water side of the heat exchanger, the outlet and inlet temperatures of the cooling water of the heat exchanger, the C factor reflecting the degree of blockage of the heat exchanger can be obtained, providing a diagnostic basis for whether there is a blockage problem in the heat exchanger. In addition, the backwashing device has the advantages of simple structure, wider application range, and can be carried out without stopping the machine.

[0114] Those skilled in the art will appreciate that the present application may be implemented as a system, method or computer program product.

[0115] Therefore, the present disclosure may be specifically implemented in the following forms, namely: it may be completely hardware, it may be completely software (including firmware, resident software, microcode, etc.), or it may be a combination of hardware and software, generally referred to herein as a "circuit", "module" or "system". In addition, in some embodiments, the present application may also be implemented in the form of a computer program product in one or more computer-readable media, and the computer-readable medium may contain computer-readable program code.

[0116] Any combination of one or more computer-readable media can be used. Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable storage media can be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or devices, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: electrical connections with one or more wires, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above. In this document, computer-readable storage media can be any tangible medium containing or storing a program, which can be used by an instruction execution system, device or device or used in combination with it.

[0117] Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art can change, modify, replace and modify the above embodiments within the scope of the present application. On this basis, a variety of replacements and improvements can be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. An online diagnosis method for blockage of a shell and tube heat exchanger, characterized in that: The following steps are involved: Construct the C factor based on the resistance coefficient and heat transfer coefficient of the shell-and-tube heat exchanger; By detecting the change trend of the C factor, the blockage degree of the shell-and-tube heat exchanger is diagnosed online.

2. The online diagnosis method for blockage of a shell-and-tube heat exchanger according to claim 1, characterized in that: The calculation formula of the C factor is: C=C k +C K ; Among them, C k is the resistance coefficient of the shell-and-tube heat exchanger after dimensionless processing, C K is the heat transfer coefficient of the shell and tube heat exchanger treated as dimensionless.

3. The online diagnosis method for blockage of a shell-and-tube heat exchanger according to claim 2, characterized in that: The resistance coefficient C of the shell-and-tube heat exchanger after dimensionless treatment k The calculation formula is: C k =(k / k0-1)×100%; The heat transfer coefficient C of the shell and tube heat exchanger treated without dimension K The calculation formula is: C K =(K / K0-1)×100%; Among them, k0 is the resistance coefficient of the shell-and-tube heat exchanger in a clean state, K0 is the heat transfer coefficient of the shell-and-tube heat exchanger in a clean state; k and K are the resistance coefficient and heat transfer coefficient of the real-time shell-and-tube heat exchanger, respectively.

4. The on-line diagnosis method for blockage of a shell-and-tube heat exchanger according to claim 3, characterized in that: The calculation formula for the resistance coefficient k of the real-time shell-and-tube heat exchanger is: ΔP E =kQ 2 ; Among them, ΔP E is the inlet and outlet pressure drop of the cooling water side of the shell and tube heat exchanger, Q is the cooling water flow rate in the shell and tube heat exchanger, m 3 / h.

5. The on-line diagnosis method for blockage of a shell-and-tube heat exchanger according to claim 4, characterized in that: The inlet and outlet pressure drop ΔP of the cooling water side of the shell and tube heat exchanger E The calculation formula is: ΔP E =(ΔP L +ΔP r )F t +ΔP N ; ΔP r =(ρv 2 / 2)(4N p ); Q=(πD 2 / 4)V=nπd 2 v / 4N P ; Among them, F t is the scaling correction coefficient of the tube pass; v is the flow rate of cooling water in the tube; d is the inner diameter of the tube; D is the inner diameter of the heat exchanger inlet pipe; V is the flow rate of cooling water in the heat exchanger inlet pipe; ρ is the density of cooling water; n is the number of tubes; L is the length of the tube, m; N P is the number of tube passes; f D is the friction coefficient inside the tube; is the fluid viscosity correction factor; G N is the mass flow rate of cooling water flowing through the inlet and outlet pipes of the heat exchanger, kg / (m 2 ·s); Q is the cooling water flow rate in the shell-and-tube heat exchanger, m 3 / h.

6. The on-line diagnosis method for blockage of a shell-and-tube heat exchanger according to claim 5, characterized in that: The calculation formula of the heat transfer coefficient K of the real-time shell and tube heat exchanger is: KΔt m A=C w ρQΔt; Among them, C W is the specific heat capacity of water; Q is the flow value; ρ is the density of cooling water; A is the total heat transfer area of ​​the shell and tube heat exchanger, m 2 ; Δt is the difference between the outlet and inlet temperatures of the cooling water in the shell-and-tube heat exchanger, °C; Δt m is the logarithmic mean temperature difference between the hot and cold fluids in the shell-and-tube heat exchanger, °C; Δt max With Δt min is the larger and smaller temperature difference at both ends of the shell and tube heat exchanger, ℃; ψ′ is the correction coefficient for cross flow.

7. A shell and tube heat exchanger, characterized in that: include: Shell and tube heat exchanger body and backwash pipeline, including: The backwash pipeline is used to backwash the shell-and-tube heat exchanger body.

8. The shell and tube heat exchanger according to claim 7, characterized in that: The backwash pipeline includes a connecting pipeline and a control valve arranged on the connecting passage.

9. The shell and tube heat exchanger according to claim 8, characterized in that: The connecting pipeline includes pipeline three and pipeline four, the control valve includes valve three, valve four and valve five, and the shell and tube heat exchanger body includes cooling water inlet one and cooling water inlet two, wherein, The pipeline 3 is connected to the cooling water inlet 1 and the cooling water inlet 2; the pipeline 4 is connected to the cooling water inlet 1 and is used to discharge the backwash sewage; The valve three and the valve four are arranged on the pipeline three; the valve five is arranged on the pipeline four.

10. The shell and tube heat exchanger according to claim 9, characterized in that: It also includes pipeline 1 and pipeline 2, wherein, The pipeline 1 is connected to the cold water inlet 1, and the pipeline 1 is provided with a pressure gauge 1 and a flow meter; The second pipeline is connected to the second cooling water inlet, and a second pressure gauge is arranged on the second pipeline.

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