What level of H2S content in the gases emitted by various units in petrochemical plants is considered to indicate acidic gas?
Thread Content
There are also many types of units, such as hydrocracking, catalytic cracking, hydrorefining, hydroprocessing, reforming, acidic gas stripping, amine liquid regeneration, and so on. Which of the waste gases produced by these units need to be sent to acid gas flares? Is there any specific definition for acid gas? For example, what H2S concentration constitutes acid gas, or are there other criteria? Thank you
We only have catalytic cracking, diesel lubricant hydrogenation, reforming, acidic gas stripping, amine solution regeneration, and so on; the waste gases generated by these processes do not go directly into the acidic gas flare. It generally needs to be sent to a desulfurization tower for desulfurization.
Under normal conditions, it definitely goes into the desulfurization tower. When considering abnormal operating conditions in which release occurs directly through safety valves, what needs to be taken into account regarding discharge into the acidic gas flare?
1. It is called acidic gas or not – the terminology used in upstream and downstream facilities may vary. We once had a type of gas from reformation or diesel hydrogenation; since it was brought to our workshop to be mixed with catalytic dry gas for desulfurization, we referred to it as reformation (or hydrogenation) dry gas. However, upstream facilities called it acidic gas. Now I know that hydrogenation produces high and low pressure gases; reformation processes probably don’t come to our workshop anymore, I’m not sure. 2. Since the safety valve is facing the acidic gas flare, we can only regenerate acidic gas using amine solution or strip acidic gas using wastewater. The others should all be directed at low-pressure gas pipelines.
We’re doing it this way for now as well. However, in the first few units, there were cases where during fire relief, the H2S concentration was between 10~20% mol, and that situation is quite problematic. You must have encountered similar situations as well; so in cases of fires or other abnormal conditions, do you just direct the gas to ordinary flares?
Generally, safety valves are activated by low-pressure gas – that is, the largest pipe in the pipeline network. It is possible to choose whether to send this gas to a flare for combustion via a gas holder or not. Typically, flares do not handle acidic gases; they have two nozzles: one for low-pressure gas and one for high-pressure gas (fuel gas), which is commonly referred to as an eternal flame- -
In this case, should we not consider J2S?
In this case, it is not feasible to use an air release and gas intake cabinet for storage without employing a flare; instead, the gas is compressed by a screw compressor for desulfurization before being used as fuel gas； The other is to light a torch and let it burn- -
What is the control limit for hydrogen sulfide in the off-gases at the top of the tower after desulfurization? Thank you for the advice
Acidic gas has little correlation with the specific amount of acidic components in its composition; generally, as long as hydrogen sulfide and carbon dioxide are present, it can be considered acidic gas. In petrochemical processes, the concentration of acidic gases varies greatly; in the recycled hydrogen used for refining and hydrogenation, the hydrogen sulfide content is generally no more than 500 ppm. However, when hydrogenating gasoline fractions produced by heavy catalysis, the hydrogen sulfide level in the recycled hydrogen can reach percentages.