Our benzene product tank is internal floating roof tank with N2 blanketing which follow US EPA regulation. However measuring the VOC content at breath out shows as high at 15000 ppm. The internal roof rim seal was replaced and produced only minor improvement.
Is there any plant try to install vapor recovery unit to reduce these emissions? Is there any regulation which requires the benzene tank to be equipment with close system?
Jayaraj Jayam, Chennai Petroleum Corporation Limited, firstname.lastname@example.org
Check the blanketing pressure. Do you have the split range pressure control system to maintain the blanketing pressure? In some cases, due to faulty instruments, the vent valve of the blanketing system may be in opened condition irrespective of the pressure above the floating roof. The old Pressure vacuum vent is not an equal one to the split range control system for maintaining blanket pressure.
Calibrate the pressure measuring instruments and the split range control valves' position. Also forget not to check any leak in the shell or at the roof of the tank.