How does the screw machine determine if the shell tube needs cleaning?
The temperature difference of the screw end is the basis for judging whether the shell tube is too dirty. If the temperature difference between the ends is not known, it is not easy to determine whether the shell tube is fouled. Does it affect the heat transfer of the unit? Do you need to clean? After learning the calculation method of the end temperature difference, I learned the judgment standard.
First check the operating parameters through the controller
After starting the power, check the operating parameters of the unit, focusing on the chilled water inlet and outlet water temperature, cooling water inlet and outlet water temperature, condensing pressure and evaporation pressure.
Calculate the temperature difference at the end
The condensing pressure and the evaporating pressure are converted into corresponding condensing saturation temperature and evaporating saturation temperature. If the condensing temperature and the evaporating temperature can be inquired on the touch screen, the value is the corresponding condensing saturation temperature and evaporating saturation temperature.
If the temperature difference of the end is calculated to be >5 °C, it can be preliminarily judged that the heat exchanger has been fouled, and the temperature difference at the end is >7 °C, which is severely fouled.
Example: condensation end temperature difference = 36 ° C (condensation temperature) -32.3 ° C (cooling water temperature) = 3.7 ° C, evaporation end temperature difference = 12.1 ° C (chilled water outlet temperature) -9.7 ° C (evaporation temperature) = 2.4 ° C, visible condensation end The temperature difference between the temperature difference and the evaporation end is small, the heat transfer effect of the shell and tube is good, and there is basically no scaling.
If the temperature difference between the calculation ends is too large, the water quality can be checked:
1. Check the water quality of the cooling tower, requiring clear, no deposits, floating objects, algae and other impurities. If the cooling water quality is checked and the filler is fouled, and the end temperature difference is >5 °C, it can be confirmed that the heat exchanger shell tube is fouled.
2. Frozen water quality: Use a clean transparent water bottle to take water from the chilled water drain to see if it is turbid. Shake the water bottle to see if there are suspended particles. Stand still to see if there is any deposit at the bottom of the water bottle.
If the chilled water is turbid and the temperature difference between the ends is >5 °C, it can be confirmed that the heat exchanger shell tube is fouled.
