Analysis of counter-current two-stage recontact and single-stage forward-flow recontact in reforming units
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In reforming units, in order to recover the light hydrocarbons carried away by the hydrogen produced and thereby increase the yield of light hydrocarbons as a liquid product as well as the purity of the hydrogen, a recontact process is necessary. Currently, there are two types of recontact processes: single-stage forward recontact and two-stage counterflow recontact. What are the differences between the hydrogen and liquid products obtained from these two processes?
Do you mean the process for one contact and two contacts?
It is necessary to take into comprehensive consideration factors such as product quality requirements and energy consumption
In the secondary re-contact process, the purity of hydrogen may improve, but energy consumption increases； The determination of a single process affects the purity of hydrogen. It’s simply a combination of hydrogen quality and energy consumption
Hydrogen produced through reverse re-contact at both ends has higher purity and a simpler process
Currently, the popular approach is to carry out contact once and simultaneously reduce the high-temperature level in order to recover light hydrocarbons and improve hydrogen purity. Using liquid ammonia cooling to lower the temperature yields much better results than two re-contacts.
In my opinion, the main difference in considerations between one recontact stage and two countercurrent recontact stages during the design phase is the hydrogen network pressure. If the pressure in the hydrogen network is high, two-stage recontact should be considered, and the purity of the hydrogen in these two stages is significantly higher than that in the single stage