When measuring differential pressure in dust-containing pipelines, what is the appropriate level for controlling the purge gas?
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When measuring the differential pressure at the inlet and outlet of dust-containing heat exchangers, the pressure tapping tubes often get clogged. What is the appropriate level for controlling the purge gas?
By using a purging air stream together with a flow-limiting orifice plate in the purging unit, blockages are less likely to occur; alternatively, using a dual-flange differential pressure transmitter will yield better results.
Calculation method for the flow rate of the fluidized bed backflow gas: The Society of Petroleum Engineers’ \"Manual on the Installation of Instrumentation and Control Systems in Refineries\" recommends a backflow gas velocity of 0.23–0.93 m/s; in China, a value of 0.5–1 m/s is generally used. The flow rate is usually controlled by flow-limiting orifice plates, and the backflow gas flow rate as well as the parameters of these orifice plates can be calculated using the following formulas. G=1.2522*δ*d*d*（square root of P*r） G--weight flow rate of backflow gas, in kg/h ； δ--flow coefficient, which can usually be taken as 0.35-0.4 ； d--Diameter of the sharp orifice in the flow restriction plate, in mm ； P--Backblast air source pressure kg/cm2 ； r--Backblast operation density, kg/m3. Last edited by sunhow on 2007-12-28 09:20.]