Problem of regulating the return water pressure for circulating water
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I have a question and would like to seek advice from those with more experience: How should the circulating water system in a chemical plant be controlled? The options are as follows: (A) Both the inlet and return valves of the circulating water main pipes are kept open, and the total flow rate of the circulating water is controlled by adjusting the return valves of each user unit (heat exchanger); (B) The inlet valve of the circulating water main pipe is kept open, while the return valve of this main pipe is adjusted to facilitate control of the total flow rate, with the return valves of each user unit (heat exchanger) being adjusted to achieve the appropriate flow rates. I would like to know which of these two approaches is better; please explain why...
a, it’s hard to define users clearly. Based on the amount of water flow adjusted by the heat exchanger
A: To adjust the temperature of the circulating water, adjust the outlet valve of the heat exchanger; keep all the water supply and return valves open, and close the bypass valve. In winter, keep the bypass valve slightly open in order to adjust the heat exchange temperature through the temperature of the water passing through the heat exchanger
{:3_49:} Whoever gave you Plan B, beat him up – it’s like installing another pressure regulator after an existing one. . . . It’s completely useless. . . It’s better to adjust him rather than your main inlet valve; that way you can save some electricity. . . . . .
A: To adjust the temperature of the circulating water, adjust the outlet valve of the heat exchanger; keep all the water supply and return valves open, and close the bypass valve. In winter, keep the bypass valve slightly open in order to adjust the heat exchange temperature through the temperature of the water passing through the heat exchanger
The total amount of circulating water entering each device zone needs to be controlled; otherwise, the load on the circulating water pumps will be very high. After entering the device’s heat exchanger, it is adjusted via the return water valve.
I have only seen Plan B used in situations where specific pressure requirements exist for different users; it involves adjusting the pressure in the supply main to control the flow rate in the return main. In standard cooling water systems, Plan A is generally used, with each user automatically adjusting the cooling water flow rate based on temperature, and only pressure balance valves or anti-freezing bypasses are installed on the main pipes.