① Source of exhaust gas: The exhaust gas from the crude benzene section mainly comes from the gas emissions during the pumping and feeding processes, as well as the surface volatilization of raw materials in the storage tank. Including areas such as crude benzene storage tanks, lean oil tanks, wash oil tanks, underground tanks, and crude benzene metering tanks. The exhaust gas in the cold drum section mainly refers to ammonia, hydrogen sulfide, and a small amount of VOCs. Mainly from tar storage tanks, ammonia tanks, tar intermediate tanks, tar ships, underground water sealed tanks, and tar residue outlets. The exhaust gas in the desulfurization section mainly consists of ammonia, hydrogen sulfide, and a small amount of VOCs. From mother liquor tank, regeneration tank, foam breaking tank and other areas. The exhaust gas from the sewage regulating tank section is mainly composed of benzene based organic volatile compounds, and the focus is on treating benzene based compounds.

 

 

 

② Tail gas analysis: The gas in the crude benzene tank area has the characteristics of low flow rate and high concentration. We need to work intermittently according to the pressure changes inside the tank to recover the crude benzene component. The production status of the cold drum section is characterized by continuous operation throughout the year, stable system operation, continuous and stable exhaust, and the need for continuous treatment of exhaust gas. The main components are organic and inorganic mixtures such as tar, hydrogen sulfide, water vapor, ammonia, naphthalene, and benzene derivatives. The production status of the desulfurization section is characterized by continuous operation throughout the year, stable system operation, and continuous and stable system exhaust, requiring continuous treatment of the exhaust gas. The main components are organic and inorganic mixtures such as tar, hydrogen sulfide, water vapor, ammonia, naphthalene, and benzene derivatives. The main components of the sewage regulating tank are benzene derivatives, hydrogen sulfide lamps, organic and inorganic mixtures.

 

 

 

③ Waste gas concentration: The raw materials in the crude benzene tank area evaporate directly, and the boiling point of benzene is 80.1 ℃. It is a light liquid that is highly volatile, so the VOCs concentration in the crude benzene tank area is high; Based on experience, the concentration of exhaust gas in the cold drum section is relatively low. The specific concentration shall be subject to the testing results of professional institutions;

④ Exhaust gas temperature: The crude benzene tank area is a room temperature storage tank. After cooling, the exhaust gas in the cold drum section has a temperature below 200 ℃ (usually below 80 ℃).

 

 

 

⑤ Exhaust gas volume: Crude benzene tank area: The large breathing emissions of the storage tank come from the feeding process of the tank, and the exhaust gas flow rate is related to the flow rate of the inlet and outlet pumps. Small breathing refers to the amount of exhaust gas exhaled due to the expansion of the gas volume inside the storage tank caused by temperature changes. The oil and gas emitted during the loading process are balanced using a vapor balance system. Cold drum section and desulfurization section: Due to their close proximity, it has been decided to concentrate the collection and treatment of exhaust gases from both sections in order to optimize investment. The collection method adopts an open type gas collection hood to collect the exhaust gas discharged from each release port, ensuring that all released exhaust gas is collected without actively extracting material gas. The collection rate is ≥ 90%. Sewage tank: Firstly, the open space of the sewage tank needs to be covered and sealed, and the enclosed space should be designed according to the exhaust gas exchange rate of 6-10 times per hour.

 

 

 

⑥ Emission method: The breathing valve in the crude benzene tank area is connected to the condensation recovery equipment and discharged through a 15 meter chimney; The exhaust gas from the cold drum and desulfurization section is collected and treated before being discharged through a 15 meter chimney; The surface of the sewage tank needs to be covered to collect volatile waste gas. After passing through the top installation pipeline and entering the waste gas treatment equipment for deodorization and VOC removal, it is discharged through a 15 meter chimney.