Hot side bypass at the tops of each vapor column
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Is the hot bypass control at the tops of each vapor column in operation? We directly close the hot bypass manual valve and open the cold circuit fully.
There are many factors involved, including your load, the temperature of the heat exchange medium at the top of the tower, the tower pressure, as well as the efficiency of the heat exchange in the equipment. We don’t use heat exchangers very often; instead, we control the pressure at the top of the tower by adjusting the flow rate of the heat transfer medium, which results in a more stable pressure level. Generally, during winter when the load is low and the feed composition becomes heavier, the hot circuit is activated to maintain balance.
In our plant, the propane stripping tower and the top of the propylene distillation tower are both equipped with thermal bypasses, but we haven’t used them much. When they were first put into operation, the process was unstable; it seemed that the control valves caused the liquid level at the bottom of the towers to fluctuate frequently. It appeared that these bypasses were not as easy to operate as the conventional design. This might be related to the nature of the medium, the operating pressure, or the cooling load. In our catalytic unit, the stabilizer towers operate more smoothly.
It works great! The adjustment might be too drastic! Slow! It gets cold in winter when the temperature drops! It’s not energy-efficient