What is the difference between reboiler steam inlet control and outlet control?
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Think about this question: What’s the difference between steam inlet control and outlet control in a reboiler? When is it used at the beginning and when is it used at the end? Why?
Currently, what is being used is inlet steam control; this approach provides direct control, fast response, and a low pressure in the reboiler shell side. In terms of export control, only the discharge of condensate can be regulated, and such a control method has a lag time.
There are export controls on refining, and the same goes for aromatics
For heat exchangers with high load and stable heating steam pressure, the outlet temperature of the material being heated can be adjusted by controlling the amount of condensate at the outlet. This control scheme actually controls the effective heating area of the heat exchanger. When the output volume of outlet condensate decreases, the level of condensate in the heat exchanger rises, thereby reducing the heating surface area for steam and utilizing part of the sensible heat of the condensate. This control scheme can be adopted if the plant has no use for the low-pressure steam flashed from the steam condensate.
A control scheme is adopted with a regulating valve installed at the reboiler inlet and a steam trap at the outlet, which makes full use of the latent heat of steam to aid energy savings. When using outlet traps, care must be taken to prevent steam leakage; in some cases, a condensate pump must also be installed to avoid accumulation. The outlet can also adopt a liquid level control scheme using a condensate tank.