Shell-and-tube heat exchanger free of scale removal and cleaning method of shell-and-tube heat exchanger

Abstract

The shell-and-tube heat exchanger comprises a shell-and-tube heat exchanger body, the shell-and-tube heat exchanger body comprises a shell, a heat transfer tube bundle, two tube plates and a plurality of baffle plates, the two ends of the heat transfer tube bundle are installed in the shell through the two tube plates, and the baffle plates are installed in the shell through the two tube plates. The baffle plates are installed between the two tube plates at intervals in the shell pass direction of the shell, the shell is provided with a shell pass fluid inlet, a shell pass fluid outlet, a tube pass fluid inlet and a tube pass fluid outlet, the shell-and-tube heat exchanger body is further provided with a drain outlet and a pressure pulse cleaning system, and the pressure pulse cleaning system at least comprises a pulse nozzle and a nested tube. The ultrasonic cleaning and pressure pulse cleaning method is used for conducting online cleaning and full-range cleaning on the heat exchanger tube bundle space, cleaning dead angles do not exist, the cleaning efficiency is greatly improved, meanwhile, the service life of the shell-and-tube heat exchanger is effectively prolonged, the heat exchange efficiency is improved, and the labor cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchangers, and in particular to a scale-free shell-and-tube heat exchanger and a cleaning method thereof. Background Art

[0002] Shell and tube heat exchangers are wall heat exchangers that use the wall of the tube bundle enclosed in the shell as the heat transfer surface. This type of heat exchanger has a simple structure and reliable operation. It can be made of various structural materials (mainly metal materials) and can be used under high temperature and high pressure. It is currently the most widely used type. However, as the operating time increases, a large amount of scale will be generated in the heat exchanger tube bundle space, which not only affects the heat exchange efficiency of the heat exchanger, but also causes corrosion to the heat transfer tube, threatening the safe operation of the heat exchange equipment. Therefore, the heat exchanger tube bundle space needs to be cleaned regularly.

[0003] In the past, the cleaning of the heat exchanger tube bundle space was mostly done by mechanical cleaning. However, this required stopping the heat exchanger, disassembling the heat exchanger shell, and then using a high-pressure water gun to flush the internal tube bundle. Cleaning was very inconvenient and wasted a lot of time and manpower, and the cleaning efficiency was low. Summary of the invention

[0004] In view of the above problems, a descaling-free shell and tube heat exchanger and a cleaning method thereof are now provided, aiming to effectively solve the problems existing in the prior art.

[0005] The specific technical solutions are as follows:

[0006] The first aspect of the present invention is to provide a shell and tube heat exchanger that does not require descaling, including a shell and tube heat exchanger body, the shell and tube heat exchanger body including a shell, a heat transfer tube bundle, two tube sheets, and a plurality of baffles, the two ends of the heat transfer tube bundle are installed in the shell through two tube sheets, the baffles are installed between the two tube sheets in an interval manner along the shell side direction of the shell, the shell is provided with a shell side fluid inlet, a shell side fluid outlet, a tube side fluid inlet, and a tube side fluid outlet, the shell and tube heat exchanger body is also provided with a drain port and a pressure pulse cleaning system, the pressure pulse cleaning system at least includes a pulse nozzle and a nested tube for providing a pressure pulse wave for pulse cleaning of the heat transfer tube bundle, the pulse nozzle is provided on the shell, the nested tube is provided between the two tube sheets, the nested tube is provided with an openable and closable external exhaust hole, and the drain port is connected to the shell side of the shell.

[0007] Furthermore, an ultrasonic cleaning system is provided on the shell and tube heat exchanger body for ultrasonically cleaning the heat transfer tube bundle. The ultrasonic cleaning system at least includes an ultrasonic generator and an ultrasonic transducer connected in sequence, and the ultrasonic transducer is installed on the shell.

[0008] Furthermore, the nested tube includes a hollow outer tube and an inner tube, the two ends of the outer tube are correspondingly arranged on the tube plate, the outer exhaust hole is arranged on the outer tube, the inner tube is rotatably arranged in the outer tube, and the inner tube is provided with an inner exhaust hole and an elastic protrusion.

[0009] Furthermore, the shell and tube heat exchanger also includes a driver, and an output shaft of the driver passes through the shell and is connected to the inner tube.

[0010] Furthermore, the pressure pulse cleaning system also includes an air source and an air storage tank connected in sequence, the pulse nozzle is connected to the air storage tank through a first solenoid valve and a first pressure regulating valve in sequence, and the outer tube is connected to the air storage tank through a second solenoid valve and a second pressure regulating valve in sequence.

[0011] Furthermore, a first one-way valve is provided between the pulse nozzle and the first solenoid valve, and a second one-way valve is provided between the outer tube and the second solenoid valve.

[0012] Furthermore, each heat transfer tube in the heat transfer tube bundle is provided with a corrugated tube section.

[0013] Furthermore, the descaling-free shell and tube heat exchanger also includes a data acquisition and control system for data acquisition and monitoring, including a PC terminal, armored thermocouples, and pressure sensors, temperature sensors and flow meters installed on each liquid inlet or outlet, and the armored thermocouples are installed on the heat transfer tubes in the heat transfer tube bundle.

[0014] The second aspect of the present invention is to provide a method for cleaning the above-mentioned scale-free shell and tube heat exchanger, comprising:

[0015] The local dirt thermal resistance R f The standard value of thermal resistance R f0 Compare, if R f >R f0 , the heat exchanger enters the cleaning mode;

[0016] After entering the cleaning mode, the gas source is turned on and the ultrasonic cleaning system is turned on. Under the action of ultrasound, the heat transfer tube bundle vibrates slightly and the mud residue is loosened initially.

[0017] When the pressure of the gas storage tank reaches the set value, the pressurized gas is released from the lower part of the shell through the pulse nozzle at a certain frequency and intensity to further loosen the mud and remove the mud covering the outer exhaust hole on the nested tube to prevent the outer exhaust hole from being blocked;

[0018] Open the external exhaust holes and release the pressurized gas from the middle of the shell to both sides and the top through the external exhaust holes at a certain frequency and intensity to fully clean the tube bundle space;

[0019] If R f <R f0, close the external exhaust hole and ultrasonic cleaning system, open the drain port to discharge the sewage, and when the discharged water becomes clear, close the drain port and air source, complete the cleaning, and exit the cleaning mode.

[0020] The beneficial effects of the above scheme are:

[0021] 1) In the present invention, by changing the structure of the heat transfer tube, the heat exchanger tube bundle space is cleaned online and in the entire range by using ultrasonic cleaning and pressure pulse cleaning methods without disassembling the heat exchanger, and there is no dead corner for cleaning, which greatly improves the cleaning efficiency and effectively prolongs the service life of the shell and tube heat exchanger, improves the heat exchange efficiency, and reduces labor costs;

[0022] 2) In the present invention, data collection and monitoring can be used to intelligently control the start and stop of cleaning, thereby improving production efficiency and ensuring that the heat exchanger always has a high heat transfer performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a shell and tube heat exchanger provided in an embodiment of the present invention;

[0024] Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure along the line AA;

[0025] Figure 3 It is a schematic diagram of the structure of a heat transfer tube provided in an embodiment of the present invention;

[0026] Figure 4 It is a schematic diagram of the structure of an outer tube provided in an embodiment of the present invention;

[0027] Figure 5 It is a schematic diagram of the structure of the inner tube provided in an embodiment of the present invention.

[0028] In the attached drawings: 1, shell and tube heat exchanger; 1-1, tube sheet; 1-2, heat transfer tube; 1-2-1, corrugated tube section; 1-3, baffle; 1-4, shell; 1-5, tube side fluid inlet; 1-6, tube side fluid outlet; 1-7, shell side fluid inlet; 1-8, shell side fluid outlet; 1-9, sewage outlet; 1-10, air guide tube; 1-11, nested tube; 1-11-1, outer tube; 1-11-11 outer exhaust hole; 1-11-2, inner tube; 1-1 1-21 internal exhaust hole; 1-11-22, elastic protrusion; 1-12, driver; 2, ultrasonic cleaning system; 2-1, ultrasonic generator; 2-2, ultrasonic transducer; 3, pressure pulse cleaning system; 3-1, gas source; 3-2, gas storage tank; 3-3, pressure regulating valve; 3-4, solenoid valve; 3-5, first gas path; 3-6, one-way valve; 3-7, pulse nozzle; 3-8, second gas path; 4, data acquisition and control system; 4-1, PC terminal. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0032] like Figures 1 to 5 As shown, the scale-free shell and tube heat exchanger provided in the embodiment of the present invention includes a shell and tube heat exchanger body 1, which includes a shell 1-4, a heat transfer tube bundle, two tube sheets 1-1, and a plurality of baffles 1-3. The two ends of the heat transfer tube bundle are installed in the shell 1-4 through the two tube sheets 1-1. The baffles 1-3 are installed between the two tube sheets 1-1 in a spaced manner along the shell side direction of the shell 1-4. The shell 1-4 has a shell side fluid inlet 1-7, a shell side fluid outlet 1-8, The tube-side fluid inlet 1-6 and the tube-side fluid outlet 1-7, the shell and tube heat exchanger body 1 is also provided with a drain port 1-9 and a pressure pulse cleaning system 3, the pressure pulse cleaning system 3 comprises at least a plurality of pulse nozzles 3-7 and a nested tube 1-11, the pulse nozzle 3-7 is arranged on the shell 1-4, the nested tube 1-11 is arranged between two tube sheets 1-1, the nested tube 1-11 is provided with an external exhaust hole 1-11-11 which can be opened and closed periodically, and the drain port 1-9 is connected to the shell side of the shell 1-4.

[0033] like Figure 2 As shown, in the present invention, a plurality of pulse nozzles 3-7 can be installed in the air inlet holes at the bottom of the shell 1-4 along the axial direction of the shell 1-4, so that the pressurized gas can be released from the lower part of the shell 1-4 through the pulse nozzles 3-7 at a predetermined frequency and intensity; the nested tubes 1-11 can be installed on the central axis of the shell 1-4, so that the pressurized gas can be released from the middle of the shell 1-4 to both sides and the upper part through the nested tubes 1-11 at a predetermined frequency and intensity, so that the tube bundle space can be cleaned without dead angles by means of the pulse nozzles 3-7 and the nested tubes 1-11, so as to greatly improve the cleaning efficiency while effectively extending the service life of the shell and tube heat exchanger and reducing labor costs.

[0034] As a specific example, Figure 1 , Figure 4 , Figure 5As shown, the nested tube 1-11 in the present invention includes a hollow outer tube 1-11-1 and an inner tube 1-11-2, the two ends of the outer tube 1-11-1 are fixedly mounted on the tube sheet 1-1, the outer exhaust hole 1-11-11 is arranged on the outer tube 1-11-1, the inner tube 1-11-2 is rotatably arranged in the outer tube 1-11-1, and the inner tube 1-11-2 is staggered along the circumferential direction. Under the above structure, when the inner tube 1-11-2 rotates a certain distance, the inner tube 1-11-2 is rotated to the inner tube 1-11-2. When the inner exhaust hole 1-11-21 is connected to the outer exhaust hole 1-11-11, the outer exhaust hole 1-11-11 is opened, and the pressure gas introduced into the inner tube 1-11-2 through the outer tube 1-11-1 is discharged from the inner exhaust hole 1-11-21 and the outer exhaust hole 1-11-11 in turn, and then released from the middle of the shell 1-4 to both sides and the upper part; when the inner tube 1-11-2 is rotated to a certain angle again, the elastic protrusion 1-11-22 rotates into the outer exhaust hole 1-11-11, thereby closing the front sleeve 1-11. As a specific driving example, Figure 1 As shown, in the present invention, the driver 1-12 can be installed outside the shell and tube heat exchanger body 1, and the output shaft of the driver 1-12 is connected to the inner tube 1-11-2 after passing through the shell 1-4 and the tube sheet 1-1, so as to open or close the outer exhaust hole 1-11-11 on the nested tube 1-11 by driving the inner tube 1-11-2. Figure 1 As shown, the pressure pulse cleaning system 3 of the present invention also includes a gas source 3-1 and a gas storage tank 3-2 which are connected in sequence. A first pressure regulating valve 3-3 for adjusting the gas pressure and a first solenoid valve 3-4 for controlling the opening and closing of the gas circuit are installed on the first gas circuit 3-5 behind the gas storage tank 3-2. Each pulse nozzle 3-7 is connected to the first solenoid valve 3-4 through a pipeline. A second pressure regulating valve for adjusting the gas pressure and a second solenoid valve for controlling the opening and closing of the gas circuit are installed on the second gas circuit 3-8. The outer tube 1-11-1 is connected to the second solenoid valve through the air guide tube 1-10. In order to prevent the fluid in the shell from entering the gas circuit, a first check valve 3-6 is provided between the pulse nozzle 3-7 and the first solenoid valve 3-4, and a second check valve is provided between the outer tube 1-11-1 and the second solenoid valve.

[0035] On the basis of the above technical solution, in order to further enhance the cleaning effect, the shell and tube heat exchanger body 1 of the present invention is also provided with an ultrasonic cleaning system 2 for ultrasonic cleaning of the heat transfer tube bundle. The ultrasonic cleaning system 2 at least comprises an ultrasonic generator 2-1 and an ultrasonic transducer 2-2 connected in sequence. The ultrasonic transducer 2-2 is mounted on the shell 1-4. The ultrasonic generator 2-1 is used to provide power to the ultrasonic transducer 2-2 to generate ultrasonic waves of different frequencies and powers, thereby performing ultrasonic cleaning. In order to further loosen the sludge and improve the cleaning effect, as Figure 1 , Figure 3As shown, in the present invention, each heat transfer tube 1-2 in the heat transfer tube bundle is provided with a bellows section 1-2-1. The bellows section 1-2-1 enables the heat transfer tube 1-2 to be displaced to a certain extent in the length direction under the action of ultrasonic cleaning and / or pressure pulse cleaning, thereby loosening mud residue and greatly improving the subsequent cleaning efficiency.

[0036] In order to collect and monitor data, the present invention also provides a data collection and control system 4, which includes a PC terminal 4-1, an armored thermocouple, and a pressure sensor, a temperature sensor, and a flow meter installed on each liquid inlet or outlet. The armored thermocouple is installed on the heat transfer tube in the heat transfer tube bundle 1-2. The data collection and control system 4 records the data detected by the armored thermocouple (4-2) and the pressure sensor, the temperature sensor, and the flow meter installed on each liquid inlet or outlet, and calculates the local fouling thermal resistance value R in real time. f and the standard value of the fouling thermal resistance R f0 Compare, if R f >R f0 The system enters the cleaning mode by controlling the driver 1-12, the gas source 3-1, etc. f <R f0 Then exit the cleaning mode.

[0037] The cleaning method of the heat exchanger in the present invention is:

[0038] The local dirt thermal resistance R f The standard value of thermal resistance R f0 Compare, if R f >R f0 , the heat exchanger enters the cleaning mode;

[0039] After entering the cleaning mode, the PC terminal 4-1 controls the gas source 3-1 to start operation, and the ultrasonic cleaning system 2 is turned on. Under the action of ultrasound, the heat transfer tube bundle 1-2 vibrates slightly and initially loosens the mud residue;

[0040] After the pressure of the gas storage tank 3-2 reaches the set value, the PC end 4-1 adjusts the gas pressure through the first pressure regulating valve 3-3 and controls the opening and closing of the first solenoid valve, thereby releasing the pressurized gas from the lower part of the shell 1-4 through the pulse nozzle 3-7 at a certain frequency and intensity, further loosening the mud residue and removing the mud residue covered in the outer exhaust hole 1-11-11 on the nested tube 1-11, so as to prevent the outer exhaust hole 1-11-11 from being blocked;

[0041] The PC end 4-1 controls the driver 1-12 to drive the inner tube 1-11-2, and the inner tube 1-11-2 rotates and opens the outer exhaust hole 1-11-11. The PC end 4-1 adjusts the gas pressure by controlling the second pressure regulating valve, and controls the opening and closing of the second solenoid valve 3-4, so as to release the pressurized gas from the middle of the shell 1-4 to both sides and the upper part through the nested tube 1-11 at a predetermined frequency and intensity, and the ultrasonic cleaning system 2 and the pressure pulse cleaning system 3 fully clean the tube bundle space;

[0042] If R f <R f0 , PC end 4-1 closes the external exhaust hole 1-11-11 by controlling the driver 1-12, and at the same time, PC end 4-1 turns off the ultrasonic cleaning system 2, opens the sewage outlet 1-9 to discharge sewage, and at this time, the pulse nozzle 3-7 is still in working state to prevent the mud particles suspended in the water from depositing again. When the discharged water quality becomes clear, the sewage outlet 1-9 and the air source 3-1 are closed to complete the cleaning and exit the cleaning mode.

[0043] The local dirt thermal resistance value R f The calculation method is as follows:

[0044]

[0045] Among them, T wf is the interface temperature between the heat exchange tube wall and the dirt; T wc is the temperature at the corresponding measuring point when the heat exchange wall is clean, which can be obtained by equation Find, where t w0 is the inlet temperature of the tube fluid, t w1 is the outlet temperature of the tube fluid, S t is the Stanton number; q is the heat flux density, Where G is the volume flow rate of the tube-side fluid, d is the inner diameter of the tube; ρ w is the density of the tube-side fluid; f is the dirt thickness, Δp is the flow pressure drop of the fluid in the pipe before and after the dirt thickness changes.

[0046] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A scale-free shell and tube heat exchanger, comprising a shell and tube heat exchanger body, the shell and tube heat exchanger body comprising a shell, a heat transfer tube bundle, two tube sheets, and a plurality of baffles, the two ends of the heat transfer tube bundle are installed in the shell through the two tube sheets, the baffles are installed between the two tube sheets in a spaced manner along the shell side direction of the shell, the shell has a shell side fluid inlet, a shell side fluid outlet, a tube side fluid inlet, and a tube side fluid outlet, characterized in that: The shell and tube heat exchanger body is also provided with a drain port and a pressure pulse cleaning system, the pressure pulse cleaning system at least includes a pulse nozzle and a nested tube for providing a pressure pulse wave for pulse cleaning of the heat transfer tube bundle, the pulse nozzle is arranged on the shell, the nested tube is arranged between the two tube sheets, the nested tube is provided with an openable and closable external exhaust hole, and the drain port is connected to the shell side of the shell.

2. The descaling-free shell and tube heat exchanger according to claim 1, characterized in that: The shell and tube heat exchanger body is also provided with an ultrasonic cleaning system for ultrasonically cleaning the heat transfer tube bundle. The ultrasonic cleaning system at least includes an ultrasonic generator and an ultrasonic transducer connected in sequence. The ultrasonic transducer is installed on the shell.

3. The descaling-free shell and tube heat exchanger according to claim 1 or 2, characterized in that: The nested tube includes a hollow outer tube and an inner tube, the two ends of the outer tube are correspondingly arranged on the tube plate, the outer exhaust hole is arranged on the outer tube, the inner tube is rotatably arranged in the outer tube, and the inner tube is provided with an inner exhaust hole and an elastic protrusion.

4. The descaling-free shell and tube heat exchanger according to claim 3, characterized in that: The shell and tube heat exchanger further comprises a driver, wherein an output shaft of the driver passes through the shell and is connected to the inner tube.

5. The descaling-free shell and tube heat exchanger according to claim 3, characterized in that: The pressure pulse cleaning system also includes an air source and an air storage tank which are connected in sequence. The pulse nozzle is connected to the air storage tank through a first solenoid valve and a first pressure regulating valve in sequence, and the outer tube is connected to the air storage tank through a second solenoid valve and a second pressure regulating valve in sequence.

6. The descaling-free shell and tube heat exchanger according to claim 5, characterized in that: A first one-way valve is provided between the pulse nozzle and the first solenoid valve, and a second one-way valve is provided between the outer tube and the second solenoid valve.

7. The descaling-free shell and tube heat exchanger according to claim 3, characterized in that: Each heat transfer tube in the heat transfer tube bundle is provided with a corrugated tube section.

8. The descaling-free shell and tube heat exchanger according to claim 1 or 2, characterized in that: The scale-free shell and tube heat exchanger also includes a data acquisition and control system for data acquisition and monitoring, including a PC terminal, an armored thermocouple, and a pressure sensor, a temperature sensor and a flow meter installed on each liquid inlet or outlet. The armored thermocouple is installed on the heat transfer tube in the heat transfer tube bundle.

9. A method for cleaning a shell and tube heat exchanger without removing scale, characterized in that: The method for cleaning the scale-free shell and tube heat exchanger according to any one of claims 3 to 8 comprises: The local dirt thermal resistance R f The standard value of thermal resistance R f0 Compare, if R f >R f0 , the heat exchanger enters the cleaning mode; After entering the cleaning mode, the gas source is turned on and the ultrasonic cleaning system is turned on. Under the action of ultrasound, the heat transfer tube bundle vibrates slightly and the mud residue is loosened initially. After the pressure of the gas storage tank reaches the set value, the pressurized gas is released from the lower part of the shell through the pulse nozzle at a certain frequency and intensity to further loosen the mud and remove the mud covering the outer exhaust hole on the nested tube to prevent the outer exhaust hole from being blocked; Open the external exhaust hole, release the pressurized gas from the middle of the shell to both sides and the upper part through the external exhaust hole at a certain frequency and intensity, and fully clean the tube bundle space; If R f <R f0 , close the external exhaust hole and the ultrasonic cleaning system, open the sewage outlet to discharge the sewage, and when the discharged water becomes clear, close the sewage outlet and the air source to complete the cleaning.

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