Have questions regarding solvents?
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The last edit to this post was made by liaifeng on 2020-1-12 at 19:31. Are there any specific ratio requirements for preparing the amine solution used in solvent regeneration? What is the difference between condensed water and deoxygenated water? What is the purpose of adding lean liquid to the rich liquid flash tank?
This post was last edited by liaifeng on 2020-1-12 at 19:36. There are certainly requirements regarding the preparation of the solvent: the concentration is generally set at 30-50%, and it is recommended to use deoxygenated water. If the temperature of the condensate is too high, it can easily cause the solvent to age or decompose. It is more reasonable to locate the point for replenishing the lean solution on the pipeline from the solvent to the absorption tower; have you placed it in the flash tank? PS: In the future, when posting a topic, it’s recommended to include some content; otherwise, how will others know what you’re asking?
Generally, it is 30%-50%, which is determined based on the proposal of the MDEA supplier; manufacturers that import their products use a slightly higher concentration, resulting in better performance. The solvent is added by transferring it from the solvent preparation tank, where it has been prepared, into the lean liquid tank.
Okay, there is a line from the outlet of our lean liquid pump that leads to the rich liquid flash tank. Is the purpose of this to carry out secondary absorption of the gases that overflow from the flash tank?
The path to the flash tank indeed involves a secondary absorption of light hydrocarbons
The path to the flash tank indeed involves a secondary absorption of light hydrocarbons
Generally, it is most appropriate to keep the concentration of the amine solution at around 30%. If the concentration is too high, the viscosity of the amine solution increases, which affects the absorption of acidic gases and the heat transfer efficiency of the heat exchangers, as well as the pumping process. If the concentration is too low, the absorption efficiency of acidic gases declines, impacting the upstream desulfurization units. For preparing the amine solution, demineralized water or deoxygenated water is generally used; condensed water or fresh water should not be used. This is because condensed water contains iron oxides and small amounts of salts, while fresh water contains impurities and dissolved salts. These substances can cause foaming in the amine solution system. What you mean by introducing lean amine solution into the rich liquid flash tank refers to the distillation column section at the top of the tank; the lean amine solution introduced there is primarily used to absorb some of the hydrogen sulfide contained in the flashed hydrocarbons.
The rich liquid flash tank is only used to absorb hydrogen sulfide.
Both condensate and deaerated water are acceptable. As long as there is no oxygen, it’s fine. The rich flash drum’s make-up lean solvent primarily absorbs hydrogen sulfide from the flashed hydrocarbons.
When making the configuration, it is recommended to use deoxygenated water. The temperature of the condensate is generally around 140°C; this makes it easier to detect any degradation of the solvent, which could affect its performance.