The stabilizer tower product contains hydrogen sulfide

Is the pressure control for this stabilizer reflux tank a single-loop control system? Is it not a conventional setup with a selected control loop system? That is, the two methods of venting non-condensable gases and pressurizing the thermal bypass! Is this the normal situation, or has it only appeared recently?

This is what it looks like after the maintenance is completed. Our pressure control for the stabilizer operates on a single-loop system; the equipment is quite old. There is no hydrogen sulfide stripping tower, and the removal of hydrogen sulfide relies on pressure control in the reflux tank

Should we reduce the backflow slightly to see how it works?

I tried that – reducing it to 3 tons. The reason for using such a high value now is to increase the circulation at the top of the tower in order to release hydrogen sulfide; let’s see if it works

The water cooling effect is not satisfactory; could high pressure in the reflux tank cause some of the light hydrocarbon components to evaporate? It is recommended to take a sample of the oil in the reflux tank to check its boiling range.

In our stripping tower as well, the pressure in the reflux drum is higher than that at the top of the tower; this is probably due to the difference in height (it does not affect production). The presence of hydrogen sulfide is normal, as the raw materials contain it. There is no gas at the top of the tower; presumably this is because there is too little non-condensable gas in the feed material ； Second, the control valve has some internal leakage, which results in the valve not reaching its full opening degree.

Due to the pressure, you’re not sending the acidic gases from the reflux tank outside; reduce the pressure a bit. Also, the liquid level there is too high

I think the following adjustments can be made to see what works. First, since hydrogen sulfide from this tower exits mainly from the top, it’s definitely not feasible if there is no opening for pressure control in the reflux tank at the top. It is recommended to increase the bottom temperature slightly so that more hydrogen sulfide vapor can escape. Reduce the pressure in the reflux tank to allow hydrogen sulfide to escape. Secondly, the liquid level in this reflux tank is also too high; as a result, there is too little space inside the tank for flashing. It is recommended to use an external drain line to keep the liquid level at 50%. As for why the pressure at the top of the tower is lower than that in the reflux tank. . . It is still recommended to lower the pressure in the return tank first. It’s probably related to the height issue mentioned by the technician earlier; I can’t think of a solution for now. I’ll go ask my technician – he’s quite skilled, haha. I think you can try making this adjustment first and see. Since hydrogen sulfide is mainly present in liquefied gas, it is recommended to analyze the carbon 5 content in the liquefied gas at the top of the tower.

Based on my personal understanding, just offering some thoughts: 1. Are the tower pressure and filling pressure issues related to the instruments? Otherwise, it doesn’t make sense! When the pressure difference is 0.037 MPa, the material can no longer circulate properly; where does the pressure in the return tank come from? Could it be that the torch has leaked? 2. Is the liquid level in the reflux tank too high? There is no space for hydrogen sulfide in the naphtha to be separated; reducing the pressure and lowering the liquid level will help increase the separation of hydrogen sulfide.

1. Reduce tower pressure 2. Increase reflux 3. Increase heat load at the tower bottom