Sulfur Daily Question, April 14th------5 rewards for participation, 10 rewards for correct answers
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This post was last edited by Sulfur-Zinc-Aluminum on 2016-4-17 at 14:23. Why is 0.4 MPa of low-pressure saturated steam used for heating in the solvent regeneration tower? Answer: Since the bottom temperature of the solvent regeneration tower is controlled at 125°C, and the temperature of saturated steam at 0.4 MPa(g) is around 148°C, the temperature requirements can be fully met by adjusting the flow rate of the low-pressure heating steam supplied to the bottom reboiler at 0.4 MPa(g). If steam with a higher temperature and pressure level is used for heating, excessively high temperatures can lead to the degradation of the solvent in the regeneration tower, increase solvent consumption, and affect the efficiency of solvent desulfurization.
The mixed solution reaches gas-liquid two-phase equilibrium. 0.4 MPa low-pressure saturated steam is the temperature reached at gas-liquid equilibrium (where both pressure and composition are constant).
This is because the regeneration temperature at the bottom of the regeneration tower should be maintained at 120–122°C; if this temperature is too low, it becomes difficult to remove H2S from the lean liquid, which affects the quality of the product； Excessively high temperatures, above 125°C, can cause thermal degradation of the solvent. And the temperature of 0.4 MPa low-pressure saturated steam is just right.
The maximum temperature of the heating medium for MDEA is 148 degrees, which helps to mitigate the thermal decomposition of the MDEA solvent; the regeneration temperature is generally maintained at 125 degrees； The lower the pressure control in the solvent regeneration tower, the better, as it helps save energy consumption.
The temperature at the bottom of the regeneration tower is controlled at 125°C. Since the temperature of the low-pressure steam at 0.4 bar is around 148°C, it is possible to meet the temperature requirements by adjusting the amount of low-pressure steam used in the bottom reboiler. If too high a temperature of steam is used, it can cause the amine solution to degrade, thereby affecting the desulfurization efficiency
The high steam pressure leads to rapid heating, and the excessive expansion during liquid-rich regeneration can easily cause overpressure in the equipment.
Using 0.4 Mpa steam is to prevent thermal degradation of the solvent caused by superheated steam.
This is related to factors such as the temperature control of the regeneration tower and the type of regenerant used!