The overflash volume in atmospheric distillation is an important indicator for effective and well balanced operation of the distillation column. A precise measurement of this quantity poses a special challenge.
Driven only by gravity, the medium moves at very low flow velocities of around 0,45 ft/s, with a maximum flow rate of 10 tons/hr. Therefore, in order to reach a reasonable accuracy, the previously installed orifice plates had very small diameters. This resulted in a high pressure loss which could almost not be overcome by the hydrostatic conditions.
Another challenge for the measuring system was the high medium temperature of around 720 °F. After successful testing, a flow measuring system using FLEXIM's WaveInjector was installed at the measuring point, which is located in an ATEX 1 / FM Class I, Div. 1 explosion hazard zone. The installation was completed without any modification to the existing system.
The higher accuracy of the overflash measurement now allows a drastic improvement in process efficiency. The investment costs were quickly paid for by the higher yield.