How to control it in the early stage of operation of the atmospheric and vacuum heat exchange network
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When designing the heat exchangers in a heat exchange network, the fouling coefficient is taken into account. However, at the beginning of operation it can be assumed that this coefficient is 0; as a result, there is a large margin for the heat exchangers during startup, and the operating temperatures of these exchangers deviate significantly from their design values. So how is the heat exchange temperature controlled in such situations?
A high heat exchange temperature has only a slight impact on the initial distillation tower and the electrodesalination unit; good initial heat exchange performance and a high final heat exchange temperature mean that the load on the heater is lower. When the heat exchange efficiency is high, the feed temperature to the initial distillation tower is usually low, and it is sufficient to open a bypass for the heat exchanger in that process. If the feed temperature for electrodesalination is low, opening a bypass for the heat exchanger in the post-desalination process will also solve the problem.
I think the only way is to make adjustments through auxiliary circuits, but this requires a high level of experience from the workers on site; if the adjustments aren’t done properly, things can get chaotic. There is particular concern regarding the impact on the atmospheric and vacuum distillation columns, as heat removal will also change at such times.