[[TitleIndustry]]

Several key points of screw machine repair and maintenance inspection!

Date:Jan 15, 2020

[China Refrigeration Network] The temperature difference at the end of the screw machine is the basis for judging whether the shell tube is too dirty. Without knowing the temperature difference at the end, it is difficult to judge whether the shell tube is scaling.  Does it affect the heat exchange of the unit?  Do you need cleaning?  When one learns the calculation method of end temperature difference, one learns the judgment standard.


Firstly, check the operating parameters through the controller


After starting up, check the operating parameters of the unit, focusing on the inlet and outlet temperatures of chilled water, inlet and outlet temperatures of cooling water, condensation pressure and evaporation pressure.


Calculate end temperature difference


The condensation pressure and evaporation pressure are converted into corresponding condensation saturation temperature and evaporation saturation temperature. If the condensation temperature and evaporation temperature can be queried on the touch screen, the value is the corresponding condensation saturation temperature and evaporation saturation temperature.


If the calculated end temperature difference is more than 5℃, the heat exchanger can be preliminarily judged to have been fouled, and if the end temperature difference is more than 7℃, serious fouling will occur.



For example, the temperature difference at the condensation end =36℃-32.3℃=3.7℃, and the temperature difference at the evaporation end =12.1℃-9.7℃=2.4℃. It can be seen that the temperature difference at the condensation end and the temperature difference at the evaporation end are both small, and the shell-and-tube heat exchange effect is good, basically without scaling.


Several key points of screw machine repair and maintenance inspection!


If the temperature difference at the calculation end is too large, the water quality can be checked:


1, check the cooling tower water quality, clear, no sediment, floaters, algae and other impurities.  If the cooling water quality is turbid and the packing is scaling, and the temperature difference at the end is more than 5℃, the shell and tube of the heat exchanger can be confirmed to be scaling.



2. Frozen water quality: Use a clean transparent water bottle to take water from the frozen water outlet and observe whether it is turbid.  Shake the water bottle to see if there are suspended particles.  Let stand and observe whether there is deposit at the bottom of the water bottle.


If the chilled water is turbid and the temperature difference at the end is more than 5℃, scaling of the shell and tube of the heat exchanger can be confirmed.


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