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Plate heat exchanger maintenance process and operation precautions_

by:DIGUANG     2021-04-11
Plate heat exchanger maintenance process and operation precautions

2020-05-20 16:13
539 In the process of inspecting and repairing plate heat exchangers, in addition to checking the relevant work records of the equipment, we mainly use visual appearance to find out whether the equipment is abnormal. The following will follow the plate heat exchanger manufacturer Diguang Let's learn about the maintenance process and operation precautions of the plate heat exchanger together! 1. Measuring the thickness of heat exchangers that work continuously for a long time. We must worry about abnormal corrosion. Therefore, measure the thickness of the shell from the outside and calculate the amount of corrosion. When measuring, use a non-destructive thickness measuring device such as ultrasonic. 2. External conditions The external conditions of the plate heat exchanger during work are visually inspected. The items include: inspection of the joint part: to check the leakage from the welding part of the main body, flange joints, and piping joints. Or whether the bolts are loose. Check the foundation and support legs: check whether the anchor bolts are loose, whether the cement foundation is cracked or falling off, and whether the steel support feet are abnormally deformed, damaged or deteriorated. Checking of heat preservation and cold preservation equipment: Check whether the exterior of the heat preservation and cold preservation equipment is damaged, especially the waterproof layer covering the outside and the simple damage of the feet, so pay attention to check. Paint inspection: To check the deterioration of the exterior paint. Oscillation check: Check the main body and connecting pipes for abnormal oscillations and abnormal sounds. If an abnormal situation occurs, it is necessary to find out the cause and adopt the necessary measures. 3. Internal leakage The internal leakage of the heat exchanger includes: thinning and perforation caused by tube corrosion and abrasion; loosening of the expanded tube due to cracking, corrosion, and oscillation; wear and perforation caused by touching the baffle ; The fastening bolts of the floating head cover are loosened, broken, and the sealing gaskets of these parts are deteriorated, etc. The two fluids are mixed due to leakage inside the heat exchanger. From the safety point of view, the equipment should be disassembled and inspected. Under normal conditions, dyeing and mixing of impurities may occur and the product does not meet the specifications, the quality is reduced, or even The situation of equipment parking occurs, so it is very important to find the internal leakage as early as possible by sampling and analyzing the low-pressure fluid outlet of the heat exchanger. Fourth, the pressure loss situation should be checked out due to the products attached to the inside and outside of the pipe that caused the increase in fluid pressure loss. 5. Measuring and investigating the temperature fluctuations of the fluid inlets and outlets of the heat exchanger and the amount of heat transfer decline to estimate the pollution status. 6. Operational precautions The heat exchanger cannot give a drastic temperature change. The ordinary heat exchanger adopts the thermal expansion method with the working temperature as the target, so the rapid temperature change will cause thermal stress on the part, which will cause the expansion part Loosening or broken pipes, etc., so special attention should be paid when the temperature rises and falls. The cooling water temperature should not exceed the required degree: seawater is used as cooling water in the heat exchanger. If the cooling water outlet temperature reaches 50°C or higher, it will promote the abnormality of microorganisms, the differentiation and adhesion of non-staple food products, and the rapid corrosion, perforation, and function decline of the tube, so be careful. Pay attention to the abnormal rise in pressure and temperature, fully understand the planning conditions of the heat exchanger, and use the appearance to check whether the pressure and temperature rise abnormally. VII. Disassembly inspection, repair inspection According to relevant regulations such as the defects of the heat exchanger, the function decline, etc., the work should be stopped regularly and the disassembly inspection should be carried out. The key is as follows: 1. The appearance inspection when disassembling is to determine the comprehensiveness of each part. Corrosion and deterioration status, so immediately after disassembly, check the degree of pollution and the adhesion status of scale, and conduct sampling and analysis experiments according to requirements. 2. The inspection of the shell, channel and tube sheet is in accordance with the general structure, and the inside and outside after disassembly are inspected-mainly by naked eyes. For the corroded part, the wall thickness can be measured with a depth gauge or an ultrasonic thickness gauge to determine whether it exceeds the allowable scale. Secondly, the channels and partitions are often tortuous due to conditions such as scale blockage and pressure changes during use, or corrosion caused by fluid leakage from the front end of the inner partition due to poor gasket installation. Other tube sheets are simply tortuous due to the effects of stress, tube blockage, and pressure changes during tube expansion, so it is necessary to measure the tensile strength and other items. 3. Checking the defects of the inner side of the heat transfer tube. Within 100mm from the tube sheet (counting from the tube sheet), it can be measured with a side diameter meter. If it exceeds the above scale, use a tube viewer with a magnifying glass for visual inspection. The size of the defect can be measured by the scale on the viewer, but its depth is difficult to accurately grasp by visual inspection. If the pipe material is non-magnetic, the amount of corrosion can be measured with an eddy current flaw detector. The shortcomings of the tubes of the fixed tube-sheet heat exchanger can also be measured by the water depth method with an ultrasonic flaw detector. 4. Install, reset, test, clean, check or maintain the repaired plate heat exchanger in accordance with the installation sequence and essentials, while performing a pressure test to see if it is abnormal, then install and reset it. The above is all about the maintenance process and operation precautions of the plate heat exchanger, I hope it will be helpful to you. If you want to know more about the maintenance price, plan, process flow and other contents of the plate heat exchanger, please go to the official website of Diguang Heat Transfer for details.
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