Discussion on the treatment solutions for exhaust gases from oil and gas recovery devices

1. If the exhaust emissions do not meet the standards, it is necessary to determine the exact cause: is it insufficient processing capacity, saturated adsorbents, too high a condensation temperature, or problems with the control system? Is this exhaust recovery device also connected to the exhaust from the loading and unloading stations? Does loading and unloading have a significant impact on the emissions from this recovery device?； Has a nitrogen seal been installed in the naphtha tank area and the benzene tank area? What is the nitrogen sealing amount? Can it be adjusted? Should I try each value one by one? You could ask the design and installation company to take a look. 2. It is considered risky to burn exhaust gases in a process furnace; a diagram of the process furnace should be prepared, as otherwise it is impossible to determine where the risks lie. However, could the success of burning the gas from the top of the vacuum tower in a process furnace serve as a reference? 3. By how much do the exhaust emissions exceed the limits, and what is the amount? Is it feasible to use activated carbon to adsorb the exhaust gases once more?

This post was last edited by bfdlwolf on 2019-10-2 09:13. Unlike the gas at the top of the pressure relief tower, the exhaust gas from the oil and vapor recovery unit is mainly nitrogen; burning it in a process furnace is not appropriate, so a catalytic oxidation process could be considered

What was said on the 2nd floor is correct, but the key is still to figure out what is causing the emissions to not meet the standards

It is difficult to desorb benzene from activated carbon, causing it to become deactivated

Thank you very much for your reply. The main reason is likely that the processing capacity of our company’s oil and gas recovery unit is insufficient.

There is definitely some risk involved in burning it, and containers like yours certainly have nitrogen sealing; using a large amount of nitrogen makes subsequent processing complicated as well. If you are using the activated carbon adsorption process, it may be that due to the small size of the treatment unit, the activated carbon loses its effectiveness quickly, resulting in exhaust gases that do not meet the standards ； We recommend that you use resin-based adsorption technology; it is renewable, does not become deactivated, and the adsorbent hardly needs to be replaced. We have used it several times in our designs, and it achieves the required emission standards with excellent results.

This post was last edited by Hansonwen on 2019-10-15 at 16:58. There are methods that involve using fans to increase the pressure of unorganized emissions, and then sending them to flares or incinerators for combustion. However, when transporting the exhaust gas from this condensation and adsorption unit to the process reboiler for combustion, it is essential to take the following factors into consideration: 1) The exhaust gas from the condensation and adsorption unit does not meet the standards; which specific pollutants are not within the required limits? Benzene, xylene, or total non-methane hydrocarbons? 2) Specific components and calorific value of exhaust gases. Combustion requires certain conditions; if the nitrogen content in the condensed and adsorbed exhaust gases is too high, or if the calorific value of the exhaust gases is below 7880 kJ/Nm3, it is necessary to adjust the calorific value prior to combustion (for details, refer to SH3009-2013 Design Specifications for Flammable Gas Emission Systems in the Petrochemical Industry). If the calorific value is too low and the nitrogen content is too high, it may again result in excessive Nox levels in the flue gases emitted from the process reboiler ； 3) Explosion prevention issues during exhaust gas transportation. Tanks equipped with condensation and adsorption units should generally have a nitrogen sealing system. If not, then one must consider whether there is oxygen in the exhaust gas. At this point, it is necessary to calculate the limiting oxygen content of the exhaust components and the lower limit for mixed explosions. In cases where the oxygen content is relatively high, it is necessary to consider whether a fan is required to supply air, in order to keep the concentration of flammable gases in the exhaust gas below 25% of their lower explosive limit. Only in this way can the transportation process be safe. 4) The issue of flame arrestment. At present, the vapor phase from the storage tanks in the tank farm has been connected to the condensation and adsorption unit ； If the condensation and adsorption unit is connected to open-flame equipment, the focus of safety risk control should be on preventing major fire and explosion incidents involving multiple tanks caused by backfire in the process reboiler. Therefore, venting and pipeline flame arresters are particularly important.

Thank you very much. 1. Our exhaust gas fails the test for non-methane hydrocarbons. 2. Indeed, the nitrogen content is relatively high, accounting for 96% by volume. 3. The oxygen content is very low, at 2.6% by volume. 4. A flame arrester of the blast suppression type has been installed in the exhaust pipe. Thank you again.