For the heat exchanger in liquid ring vacuum pumps, should the working fluid flow through the shell side or the tube side?
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Hello, experts. Regarding the liquid seal heat exchanger in liquid ring vacuum pumps, should the working fluid flow through the tube side or the shell side? I see that according to API681, the working fluid is required to flow through the shell side, while the cooling water flows through the tube side ； 1. Conventional shell-and-tube heat exchangers are basically single-pass with multiple tubes ； If it is a small vacuum pump, the flow rate of the working fluid is already low; if it flows through the shell side, the flow velocity will be too low. What should be done? 2. Is it feasible to have the working fluid flow through the tube side and the cooling circulating water flow through the shell side? 3. If there are multiple shell sides, the manufacturing difficulty of the heat exchanger increases. (I see that the heat exchangers I developed, as shown in the samples, are essentially multi-shell-type; the structure was modified to a rectangular shape for easier fabrication.) 4. Can finned-tube heat exchangers be used in vacuum units to increase the heat exchange area when space is limited? But then another issue arises: if the working fluid flows through the shell side, how can it be cleaned? 5. According to API681 standards, heat exchange tubes for sealant heat exchangers must have a diameter of at least φ15; in China, tubes with a diameter of φ14 or more are used. However, I noticed that NASH requires tubes with a diameter of φ12 or more. Is it sufficient to use tubes with a diameter of 12 for the sealant heat exchangers in liquid-ring vacuum units, as long as the fouling coefficient of the circulating water is not high?)
So, our company’s vacuum units. The working fluid flows through the tube side, while the circulating water flows through the shell side. In this way, carbon steel can be used for the shell side under most operating conditions.
For plate-type designs, it depends on the medium involved; since gas components dissolve in water, it won’t work if that medium reacts with or corrodes the rubber components. As the seals between the plates are generally made of rubber, the shell-and-tube type is more versatile.
We use fully welded and semi-welded plate exchangers in centrifuges and other areas
In the liquid ring vacuum pumps produced by our company, the working fluid flows through the tube side, while the cooling medium flows through the shell side. This is because blockages can occur in the heat exchanger; the tube side is easier to clean, whereas the shell side cannot be cleaned； The circulation volume of the working fluid is not high, making it difficult to control flow in the shell side
It is correct for the working fluid in the heat exchanger of a liquid ring vacuum pump unit to flow through the shell side, as the flow velocity there is relatively low and the resistance is small. The circulation of the working fluid relies on the pressure difference between the inlet and outlet, and since this pressure difference is limited, it is necessary to minimize resistance. If there is a concern about blockages, a floating-head core-type heat exchanger can be used. As for the choice made by most manufacturers, it is generally aimed at reducing costs, including the use of rectangular-shaped heat exchangers!