How to recover the oil and gas at the top of tar tanks for heavy oil?
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With increasingly strict requirements regarding safety and environmental protection, it is necessary to install recovery devices for the oil vapor generated by heavy oil tar topping. I’m posting this here to see if any colleagues have experience with installing such recovery devices
Under the current standards for pollutant emissions in the petrochemical industry, GB31571-2015, the allowable emission concentration for non-methane total hydrocarbons is 120 mg/m3, the limit for benzene is 4 mg/m3, and that for xylene is 20 mg/m3. To control the VOC emissions from heavy oil and tar storage tanks, the following modifications and new installations are required: 1. Modifications: It is necessary to modify the breather valves on top of the tanks, install a nitrogen sealing system, and seal the ventilation openings of the tanks. A flame arrester should be installed on the nitrogen sealing exhaust pipes, and the VOC pipelines related to the nitrogen sealing system of each tank need to be connected together； For specific procedures, refer to Sinopec’s Letter on Refining and Production [2016] No. 127. II. New construction section: A new treatment unit is required for the connected VOCs main pipelines, and the types of such units can include low-temperature adsorption, catalytic combustion, regenerative combustion, etc
Recycling may not be economical, but for exhaust gas treatment, the use of activated carbon for adsorption along with regular replacement of this carbon can be considered; since the gases and vapors at the top of heavy oil tar tanks consist of small-molecule organic compounds, it is difficult to recover and condense them
For macromolecules, oxidative combustion is recommended; other methods such as condensation, adsorption, and membrane separation are cumbersome
There are just a few methods: combustion, exhaust gas washing and recovery, membrane separation, and adsorption