Removable plate heat exchanger fouling formation and its impact on heat transfer, in order to eliminate dirt, heat exchangers should regularly remove dirt, dirt, can be taken when designing heat exchangers To reduce the heat transfer coefficient or increase the heat exchange area, it is customary to select a certain fouling factor value, but in actual operation, it is difficult to explain whether it is correct to generally specify a reasonable time for cleaning the scale. After a time interval, use it as the basis for selecting the value of the fouling factor, and then add the required heat exchange area to the design. Even so, it is inevitable to remove the scale.
heat and evaporate the liquid in the tower to obtain the medium vapor in the tower, the medium vapor rises and contacts with the liquid flowing under the top of the tower to achieve the physical and chemical reaction in the tower. The equipment also has a name called tower. A kettle reboiler is used to realize a heater in which the liquid in the tower is boiled again. The heat exchanger tube medium is methanol, the shell side medium is steam, and the 180 degree steam heats the methanol to make the methanol boil. From the analysis of conventional corrosion mechanism, the material used in the tower body is 16MnR, the material of the tube tube of the heat exchanger tube is also 16MnR, and the heat exchange tube is 10# steel. Corrosion was not observed in the tube head of the tube and the heat exchanger. In the heat exchange tube, corrosion was found only near the upper tube sheet, indicating that the corrosion of the heat exchange tube was not considered or previously occurred in the original material selection. Corrosion.
Because the corrosion site is close to the upper tubesheet, other parts are not corroded, and most of the heat exchange tubes are corroded in this part, which means that corrosion has nothing to do with the material, it is definitely in the process design. Or lack of operation, resulting in local corrosion of the heat exchange tubes. The liquid level of the heat exchanger tube is about one-third to two-thirds of the length of the heat exchange tube. The shell side is filled with steam, and the condensate discharge line at the bottom is connected to the steam trap to ensure the shell-side heating effect.
When the methanol medium in the heat exchanger tube of the heat exchanger manufacturer is boiled by the shell-side steam, it becomes a methanol vapor rise, because the shell-side steam temperature is higher than the methanol vapor temperature in the heat exchange tube, the methanol temperature When rising in the heat exchange tube, it is heated and the temperature rises. When the methanol vapor enters the heat exchange tube in the tube sheet, since there is no steam around, the methanol vapor passes through the distance, or the methanol vapor enters the upper tube box, there is no heating source, and part of the steam in the methanol vapor becomes liquid. The droplets are attached to the wall of the heat exchange tube in the tube sheet, or the droplets in the upper tube box fall onto the upper tube sheet and then flow down the heat exchange tube. When the droplets flow down the tube along the heat exchange tube in the tube sheet, they are heated by the high temperature steam and become methanol vapor. This repeated process causes the inner surface of the lower heat exchange tube of the upper tube sheet to undergo a dielectric phase change. Corrosion occurs under a specific temperature environment, thereby forming annular pits.