Online cleaning device and method for heat exchanger of power plant desulfurization wastewater treatment system

Abstract

The invention discloses an on-line cleaning device and method for a heat exchanger of a desulfurization wastewater treatment system of a power plant, the on-line cleaning device is suitable for a single-tube-pass tubular heat exchanger, an electromagnet is fixed in each of end sockets at two ends of the heat exchanger, an anti-corrosion and friction-resistant fixed line is arranged in each tube, and the fixed lines are connected with the electromagnets. The two ends of the fixing line are fixed to electromagnets at the two ends of the heat exchanger, and a small cleaning ball with a built-in permanent magnet penetrates through the fixing line. When cleaning is not conducted, the small cleaning ball is attracted to the electromagnet at any end; during online cleaning, the current directions of the electromagnets at the two ends are adjusted to change the magnetic pole directions of the electromagnets, and the small cleaning balls fully brush the inner walls of the tubes under the action of the magnetic force of the electromagnets and the scouring force of a tube pass medium and are adsorbed to the electromagnet at the other end after passing through the tubes. The moving direction of the small cleaning balls is consistent with the flow direction of a tube pass medium, online cleaning can be achieved without shutdown of a production system and disassembly of the heat exchanger, the cleaning time is short, mechanical damage or corrosion to the heat exchanger is avoided, and no pollutant is generated.

Description

Technical Field

[0001] The invention belongs to the technical field of desulfurization wastewater treatment, and specifically relates to an online cleaning device and method for a heat exchanger of a desulfurization wastewater treatment system of a power plant. Background Art

[0002] At present, the new power plant desulfurization wastewater treatment technology based on "multi-effect flash concentration + low-temperature flue gas evaporation" has become mature and is rapidly occupying the domestic market. In the implementation of this technology, the desulfurization wastewater is first concentrated by the multi-effect flash concentration system, and then the desulfurization wastewater concentrate enters the high-temperature evaporation tower to use the remaining low-temperature flue gas generated by coal combustion for evaporation treatment, the produced water is reused, and the ash and slag are disposed together with the power plant slag. The content of calcium and magnesium ions, sulfate and suspended solids in desulfurization wastewater is very high, and the operating temperature of the heat exchanger of the multi-effect flash system is 50-80℃. In this operating environment, calcium salts and magnesium salts are easy to precipitate and form crystals; after a period of operation, a scaling layer composed of calcium carbonate, calcium sulfate, magnesium hydroxide and other sludge will be formed on the inner wall of the tubes in the heat exchanger. The formation of the scaling layer will seriously affect the heat exchange efficiency of the heat exchanger, and more seriously, it will cause the inside of the tubes to be completely blocked. At present, the conventional methods for cleaning heat exchangers in industrial production applications mainly include manual cleaning and chemical cleaning. However, the conventional cleaning methods have the following disadvantages: chemical cleaning, chemical cleaning effect is better, but different cleaning agents need to be used for different scaling materials, and frequent use of chemical agents is easy to cause corrosion to the heat exchanger. In addition, chemical cleaning needs to be carried out after shutdown, and cleaning takes a long time, and the wastewater generated by cleaning needs to be treated; manual cleaning, the heat exchanger needs to be disassembled before cleaning, which is time-consuming and labor-intensive, and the cleaning effect is poor. Summary of the invention

[0003] In view of the above problems existing in the prior art, the present invention provides an online cleaning device and method for a heat exchanger in a desulfurization wastewater treatment system of a power plant.

[0004] The objective of the present invention is achieved in the following manner: an online cleaning device for a heat exchanger in a desulfurization wastewater treatment system of a power plant, wherein an electromagnet is fixedly arranged in each of the two heads of the heat exchanger, the electromagnet and the heat exchanger are sealed and insulated, a tube array is arranged in the heat exchanger, and a corrosion-resistant and friction-resistant fixed wire passes through the tube array, and both ends of the fixed wire are respectively fixed on two electromagnets, and the fixed wire passes through a hole in the center of a cleaning ball, the surface of the cleaning ball is a friction-resistant and corrosion-resistant layer, and a strong magnet is wrapped in the center, and an elastic protrusion is arranged on the friction-resistant and corrosion-resistant layer, and the cleaning ball reciprocates along the fixed wire under the action of the magnetic field force of the electromagnet and the impact of the medium in the tube side.

[0005] The fixing line is polyamide or fluorocarbon fiber.

[0006] The wear-resistant and corrosion-resistant layer and elastic protrusions on the surface of the cleaning ball are both made of rubber.

[0007] The outer diameter of the cleaning ball is 1 to 2 mm larger than the inner diameter of the tube.

[0008] The elastic protrusion is in the shape of a stripe.

[0009] The solenoid cable is sealed and connected to the heat exchanger via a flange.

[0010] The online cleaning method using the online cleaning device described above comprises the following steps: when online cleaning is not performed, the electromagnet at either end is energized, and the cleaning ball is adsorbed and fixed on the energized electromagnet 5 under the action of magnetic attraction; when online cleaning is performed, the controller controls the pipe inlet valve and the pipe outlet valve to be closed, and changes the coil current direction of the electromagnet that adsorbs and fixes the cleaning ball, so that the magnetic attraction of the electromagnet on the cleaning ball is changed into magnetic repulsion, and the cleaning ball enters the tube array under the action of the magnetic repulsion, and at the same time adjusts the coil current direction of the electromagnet at the other end so that it has magnetic attraction to the cleaning ball, and then immediately opens the pipe inlet valve and the pipe outlet valve so that the flow direction of the tube medium in the heat exchanger is consistent with the moving direction of the cleaning ball, and the cleaning ball scrapes the inner wall of the tube array under the action of the magnetic field force and the impact force of the tube medium, brushes off the newly formed scale, and the cleaning ball is adsorbed on the electromagnet at the other end after passing through the tube array, completing one online cleaning.

[0011] One cleaning time lasts 1 to 2 minutes.

[0012] Compared with the prior art, the heat exchanger online cleaning device disclosed in the present invention is suitable for single-pass tubular heat exchangers. According to the structure and operation of the heat exchanger in the desulfurization wastewater treatment system of the power plant, a disc-shaped electromagnet is fixed in the heads at both ends of the heat exchanger, and an anti-corrosion and friction-resistant fixed wire passes through the inside of each tube, and the two ends are fixed to the electromagnets at both ends of the heat exchanger. A cleaning ball with a built-in permanent magnet passes through each fixed wire, and the fixed wire is always in a straightened state. When the system is operating normally, the cleaning ball is adsorbed on the electromagnet at one end. After a period of time, the direction of the magnetic poles of the electromagnets is changed by adjusting the current direction of the electromagnets at both ends. The cleaning balls fully scrub the inner walls of the tubes under the action of the magnetic force of the two electromagnets and the flushing force of the medium in the tube of the heat exchanger. After passing through the tubes, the cleaning balls are adsorbed on the electromagnets at the other end. When flushing next time, the flow direction of the medium in the tube of the heat exchanger is adjusted to ensure that the moving direction of the cleaning balls is consistent with the flow direction of the medium in the tube. Online cleaning can be achieved without shutting down the production system or disassembling the heat exchanger. The cleaning time is short, and no mechanical damage or corrosion is caused to the heat exchanger, and no pollutants are generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the present invention.

[0014] Figure 2It is a schematic diagram of the structure of the cleaning ball.

[0015] In the figure: 1-heat exchanger, 2-shell side outlet valve, 3-tube side inlet valve, 4-cleaning ball, 5-electromagnet, 6-electromagnet cable fixing flange, 7-cable, 8-fixing line, 9-tube, 10-drain valve, 11-shell side inlet valve, 12-tube side outlet valve, 14-friction and corrosion resistant layer, 15-strong magnet, 16-hole, 17-elastic protrusion. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the present invention.

[0017] like Figure 1 As shown, the heat exchanger 1 is a single-pass tubular heat exchanger, which includes a shell and end caps at both ends of the shell. The end caps are detachably connected to the shell through flanges. A tube sheet is respectively arranged at both end caps in the heat exchanger, and a plurality of parallel tubes 9 are arranged between the two tube sheets. A shell-side inlet valve 11 is arranged at the lower part of one end of the shell, and a shell-side outlet valve 2 is arranged at the upper part of the other end. A tube-side inlet valve 3 is arranged at the upper part of the end cap adjacent to the shell-side outlet valve 2, and a tube-side outlet valve 12 is arranged at the lower part of the other end cap. A drain valve 10 is also arranged at the lower part of the shell. An electromagnet 5 is fixedly arranged in the sealing heads at both ends of the heat exchanger 1. The electromagnet 5 is tightly sealed with the heat exchanger 1 and the insulation is intact. The cable 7 of the electromagnet 5 extends out of the heat exchanger 1 through the electromagnet cable fixing flange 6. The electromagnet cable fixing flange 6 is well sealed and can meet the normal operating conditions of the heat exchanger 1. The cable 7 of the electromagnet 5 is connected to the controller (not shown in the figure) for communication. Each tube 9 has an anti-corrosion and friction-resistant fixed wire 8. The two ends of the fixed wire 8 are respectively fixed to the two electromagnets 5 in the sealing heads at both ends. A cleaning ball 4 is passed through each fixed wire 8. Figure 2 As shown, a radial hole is arranged at the center of the cleaning ball 4, and a fixing line 8 passes through the hole at the center of the cleaning ball 4. The surface of the cleaning ball is a friction-resistant and corrosion-resistant layer, and a strong magnet 15 is wrapped in the center. An elastic protrusion 17 is arranged on the surface of the friction-resistant and corrosion-resistant layer. The cleaning ball 4 reciprocates along the fixing line 8 under the action of the magnetic field force of the electromagnet 5 and the impact of the pipe medium (i.e., desulfurization wastewater).

[0018] Furthermore, the fixing wire 8 is made of polymer fiber wire with good anti-friction and anti-corrosion properties, preferably polyamide or fluorocarbon fiber.

[0019] Furthermore, the friction-resistant and anti-corrosion layer 14 and the elastic protrusion 17 on the surface of the cleaning ball 4 are made of rubber. When cleaning the inner wall of the tube 9, the friction-resistant and anti-corrosion layer 14 and the elastic protrusion 17 of the rubber material have shrinkage resilience, which facilitates the cleaning ball 4 to enter the tube 9. The outer diameter of the cleaning ball 4 is slightly larger than the inner diameter of the tube 9, generally 1 to 2 mm larger, so the contact area between the cleaning ball 4 and the inner wall of the tube 9 is larger, and the cleaning effect is better. The outer diameter of the cleaning ball 4 refers to the size from the center to the outermost edge of the elastic protrusion 17.

[0020] The elastic protrusion 17 is in a stripe shape.

[0021] When the desulfurization wastewater flash evaporation system is operating normally and no online cleaning is performed, the electromagnet 5 at either end is energized, and the cleaning ball 4 is adsorbed and fixed on the energized electromagnet 5 under the action of magnetic attraction. According to the operating conditions, online cleaning can be set to be performed every period of time (such as 4h, 6h, 8h). When online cleaning is performed, the controller controls the pipe inlet valve 3 and the pipe outlet valve 12 to be closed, and changes the coil current direction of the electromagnet 5 that adsorbs and fixes the cleaning ball 4. The magnetic attraction of the energized electromagnet 5 on the cleaning ball 4 is changed into a magnetic repulsion. The cleaning ball 4 enters the tube array 9 under the action of the magnetic repulsion. At the same time, the coil current direction of the electromagnet 5 at the other end is adjusted to have a magnetic attraction to the cleaning ball 4. Then, the pipe inlet valve 3 and the pipe outlet valve 12 are immediately opened to make the flow direction of the pipe medium in the heat exchanger consistent with the moving direction of the cleaning ball 4. The cleaning ball 4 fully scrapes the inner wall of the tube array 9 under the action of the magnetic field force and the impact force of the tube medium to brush off the newly formed scale. After passing through the tube array 9, the cleaning ball 4 is adsorbed on the electromagnet 5 at the other end, completing an online cleaning.

[0022] One cleaning time lasts about 1 to 2 minutes.

[0023] When the next cleaning is performed, the controller controls the tube inlet valve 3 and the tube outlet valve 12 to close, switches the inlet and outlet directions of the tube of the heat exchanger 1, and then changes the coil current directions of the two electromagnets 5 respectively, so that the cleaning balls 4 enter the tube array 9 under the repulsive force of the magnetic field, opens the tube inlet valve 3 and the tube outlet valve 12, so that the cleaning balls 4 scrape the inner wall of the tube array 9 under the action of the magnetic field force and the impact force of the tube medium, and adsorb on the electromagnet 5 at the other end after passing through the tube array 9.

[0024] According to the operation conditions, it can also be arranged that the cleaning balls 4 perform a reciprocating scraping motion in the tube array 9 once, or perform multiple reciprocating motions during one online cleaning process.

[0025] The tubular heat exchanger cleaning device provided by the present invention can realize online automatic cleaning of a single-pass tubular heat exchanger, adjust the flow direction of the tube-pass medium in the tube-pass of the heat exchanger, and ensure that the moving direction of the cleaning ball is consistent with the flow direction of the tube-pass medium. Online cleaning can be realized without shutting down the production system or disassembling the heat exchanger. The cleaning time is short, no mechanical damage or corrosion is caused to the heat exchanger, and no pollutants are generated.

[0026] (1) An electromagnet is fixed in each end cap of the tubular heat exchanger. A plurality of fixed wires are fixed between the two electromagnets. A cleaning ball is sleeved on the fixed wire. The fixed wire passes through the cleaning ball and the center of the tube. Under the action of the magnetic field force and the impact force of the medium in the tube, the cleaning ball can reciprocate between the two electromagnets along the fixed wire to fully scrape the inner wall of the tube, thereby realizing online automatic cleaning of the heat exchanger.

[0027] The cleaning ball adopts a double-layer structure, and its outer diameter is 1 to 2 mm larger than the inner diameter of the tube. The outer layer is made of rubber material with wear-resistant, corrosion-resistant and elastic properties, and the outer layer is equipped with rubber elastic protrusions. A strong magnet is set in the center, so that the cleaning ball can reciprocate along the fixed line between the two electromagnets under the action of the magnetic field force. The elastic protrusions of the rubber material on the surface of the cleaning ball can scrape the inner wall of the tube.

[0028] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, which should also be regarded as the scope of protection of the present invention.

Claims

1. An online cleaning device for a heat exchanger in a desulfurization wastewater treatment system of a power plant, characterized in that: An electromagnet is fixedly installed in each of the two heads of the heat exchanger. The electromagnet and the heat exchanger are sealed and insulated. A tube array is arranged in the heat exchanger. A corrosion-resistant and friction-resistant fixed wire passes through the tube array. Both ends of the fixed wire are fixed on the two electromagnets respectively. The fixed wire passes through the hole in the center of the cleaning ball. The surface of the cleaning ball is a friction-resistant and corrosion-resistant layer. A strong magnet is wrapped in the center. An elastic protrusion is arranged on the friction-resistant and corrosion-resistant layer. The cleaning ball reciprocates along the fixed wire under the action of the magnetic field force of the electromagnet and the impact of the medium in the tube.

2. The online cleaning device for a heat exchanger in a desulfurization wastewater treatment system of a power plant according to claim 1 is characterized in that: The fixing line is polyamide or fluorocarbon fiber.

3. The online cleaning device for a heat exchanger in a desulfurization wastewater treatment system of a power plant according to claim 1 is characterized in that: The wear-resistant and corrosion-resistant layer and elastic protrusions on the surface of the cleaning ball are both made of rubber.

4. The online cleaning device for a heat exchanger in a desulfurization wastewater treatment system of a power plant according to claim 1 is characterized in that: The outer diameter of the cleaning ball is 1 to 2 mm larger than the inner diameter of the tube.

5. The online cleaning device for a heat exchanger in a desulfurization wastewater treatment system of a power plant according to claim 1 is characterized in that: The elastic protrusion is in the shape of a stripe.

6. The online cleaning device for a heat exchanger in a desulfurization wastewater treatment system of a power plant according to claim 1, characterized in that: The solenoid cable is sealed and connected to the heat exchanger via a flange.

7. An online cleaning method using the online cleaning device according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: when online cleaning is not performed, the electromagnet at either end is energized, and the cleaning ball is adsorbed and fixed on the energized electromagnet 5 under the action of magnetic attraction; when online cleaning is performed, the controller controls the pipe inlet valve and the pipe outlet valve to be closed, and changes the coil current direction of the electromagnet that adsorbs and fixes the cleaning ball, so that the magnetic attraction of the electromagnet on the cleaning ball is changed into magnetic repulsion, and the cleaning ball enters the tube array under the action of the magnetic repulsion, and at the same time adjusts the coil current direction of the electromagnet at the other end so that it has magnetic attraction on the cleaning ball, and then immediately opens the pipe inlet valve and the pipe outlet valve so that the flow direction of the tube medium in the heat exchanger is consistent with the moving direction of the cleaning ball, and the cleaning ball scrapes the inner wall of the tube array under the action of the magnetic field force and the impact force of the tube medium, brushes off the newly formed scale, and the cleaning ball is adsorbed on the electromagnet at the other end after passing through the tube array, completing one online cleaning.

8. The online cleaning method according to claim 7, characterized in that: One cleaning time lasts 1 to 2 minutes.

Images