[China Refrigeration Network] In the field of medical equipment, no matter what kind of equipment, users should pay attention to the maintenance and maintenance of various components after using it for a period of time. Taking ultra-low temperature refrigerator as an example, the scale problem of shell-and-tube condenser needs special attention.
It is understood that scale, commonly known as "water rust", refers to crystals formed by the continuous adhesion and accumulation of impurities in natural water. Its poor thermal conductivity easily affects the heat dissipation of equipment, so in order to prolong the service life of ultra-low temperature refrigerator, scale on the surface of shell-and-tube condenser must be removed in time.
So, what are the methods for removing scale from shell-and-tube chillers? The industry has introduced three methods of descaling: mechanical descaling, chemical pickling descaling and electronic magnetic water separator descaling. Next, the small editor will introduce the principle and scope of application of these methods.
The invention relates to a mechanical descaling method of a shell-and-tube cold suspect, which is a method for descaling a condenser of a cooling pipe by using a soft shaft pipe washer, and is particularly suitable for a vertical shell-and-tube condenser.
The specific operation is to pump out the refrigerant in the condenser first, then close all the valves connected between the condenser and the refrigeration system to ensure the normal supply of cooling water to the condenser, then use the umbrella-shaped gear scraper connected with the flexible shaft pipe washer to rotate, roll, scrape and descale in the vertical pipe of the condenser from top to bottom, and use the circulating cooling water to cool the heat generated by friction between the scraper and the pipe wall, at the same time flush the removed dirt such as scale and rust into the water pool.
The industry reminds that when cleaning the shell-and-tube condenser of the ultra-low temperature refrigerator, attention should be paid to prevent damage to the tube wall to avoid causing the failure of the ultra-low temperature refrigerator.
Chemical pickling descaling method
The chemical pickling descaling method uses the prepared weak acid descaling agent to clean the ultra-low temperature condenser of the low-temperature refrigerator so as to make the scale fall off, thus improving the heat transfer efficiency of the condenser. Chemical pickling descaling method is suitable for vertical and horizontal shell-and-tube condensers.
The main steps are as follows: firstly, a descaling solution is prepared in a pickling tank, a pickling pump is started, after the descaling solution circulates in a condenser tube of a condenser for 24 hours, the pickling pump is stopped, then a round steel brush is used to pull the brush back and forth in the tube wall of the condenser tube, the scale and rust are rinsed clean with clear water, and then the descaling solution remaining in the tube is repeatedly cleaned with clear water until the descaling solution is completely clean.
Electronic magnetic water descaling method
In addition to the two methods mentioned above, there are also electronic magnetic water descaling methods for ultra-low temperature refrigerators to remove scale from shell-and-tube condensers.
According to introduction, the electronic magnetic water descaling method is to dissolve calcium, magnesium and other salts in the cooling water flowing through the condenser in the state of positive and negative ions in the water at normal temperature, thus effectively preventing the generation of new scale and removing the original scale. At the same time, due to the different expansion coefficients of the steel pipe and scale in the condenser, the original scale gradually cracks, and magnetized water continuously invades into the cracks, destroying the adhesion of the original scale, making it gradually loose and fall off on its own and be continuously taken away by the circulating cooling water.
In a word, once scale is produced in the condenser of ultra-low temperature refrigerator, its heat conduction resistance will continuously increase, resulting in the decrease of heat transfer coefficient value, making the refrigeration effect worse and worse. Therefore, it is suggested that operators should check and remove scale in the condenser once they find it.