Temperature setting for the flash tank in the refinery’s solvent regeneration unit

Let’s discuss this – what is the typical temperature controlled for heat exchange before flash evaporation?

The solvent is different, the equipment varies, and the processes differ – how can they be compared? Is it enough if you flash it? When the solvent becomes a rich solvent and is flashed, where does the heat for the flashing come from? Isn’t it from heat exchange? 60°C is sufficient for flash evaporation to meet the product requirements. The flash temperature is related to the target product.

I have never seen an ammonia-rich liquid reach 60 degrees Celsius without any heat exchange.

So what was the temperature of the material after heat exchange and prior to flash evaporation that you have seen?

Our design temperature is 61 degrees; we have also operated at 70 and 80 degrees when the content of acidic hydrocarbons was high. At first, steam was used for heating; later, heat exchange was carried out using steam condensate; and finally, heat exchange was done with lean amine solution. There were definitely issues with the design of early desulfurization processes, or perhaps a lack of proper understanding; amine solutions tend to foam easily, and they also tend to contain hydrocarbons. Moreover, liquefied gas played a significant role in desulfurization processes. In the acidic gases from those early systems, the main hydrocarbon was propane. Later, hydrogen desulfurization of sulfur-containing exhaust gases was developed, as was desulfurization of coker dry gas; there were also more methods for desulfurizing hydroprocessed light gases. The proportion of amine solution required for liquefied gas desulfurization became increasingly smaller. Our flash tanks have long relied on the injection of nitrogen or purified gas from above to maintain pressure, with little actual flashing occurring. In the early days, the flash temperature was increased because of the high hydrocarbon content in the acidic gas, which often caused sulfur to turn black. However, starting from at least 2002, we no longer encountered such problems; as the hydrocarbon content in the acidic gas decreased, there was no need to raise the flash temperature. Raising the temperature would increase the sulfur content in the flashed gas, and since this gas is sent to low-pressure gas pipelines and gas holders, high hydrogen sulfide levels can lead to corrosion and other issues. Moreover, once the pressure in the gas holders increases, desulfurization must be carried out again.

Okay, very professional, thank you~~