Operating conditions of the flash tank in the solvent regeneration unit
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The last edit to this post was made by liaifeng on 2018-9-3 at 17:59. The main function of the flash tank in a solvent regeneration unit is to flash off the light hydrocarbons from the amine-rich liquid under low pressure. I used Aspen to simulate the flash tank; at 70°C and 0.028 MPa, not only the light hydrocarbons but also H2S was completely vaporized. How do you control the conditions for flashing, and what methods are used in practical production to ensure that only light hydrocarbons are vaporized during the flashing process, without H2S being vaporized as well? I know that the absorption of H2S by amine solution is a chemical process; before flashing, MDEA in the rich amine solution combines with H2S to form compounds similar to complexes. Could my process simulation be inconsistent with the actual situation due to ignoring this fact? (During simulation, I only entered the amounts of MDEA and H2S separately, without taking into account the chemical reactions). If that’s the case, how should the simulation be carried out correctly?
The top of the flash tank is equipped with packing, which removes hydrogen sulfide through counter-current contact between the amine solution and the flashed gas; simple simulations are insufficient, as the packing section must also be taken into account.