Questions regarding the flow restriction orifice plate
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I have a question for everyone: Flow control orifice plates are installed at the loose points of the inclined (vertical) tubes in catalytic cracking units. Once the critical pressure drop is reached, regardless of how much the pressure drops behind the orifice plate (or rises before it), the flow rate of the medium passing through the orifice plate remains unchanged. Generally, the pressure before the orifice plate is at least twice that of the pressure behind it. If the pressure before the orifice plate is less than twice the pressure behind it – and certainly higher than the pressure behind the orifice plate – will the flow rate decrease?
The traffic will of course decrease. The addition of a flow-limiting orifice plate at the loose point is intended to prevent blockages, and to ensure that the flow rate of the loose air does not cause a significant drop in the temperature of the inclined tubes
The flow rate will certainly decrease, but if the value in front is higher than that behind, it will inevitably lead to blockages
Under normal operating conditions, the flow rate through an orifice plate is proportional to the pressure difference across the orifice plate; however, this relationship no longer exists when a critical state is reached
There is another question to discuss: when the calculations using orifice plates meet the requirements, what impact does the design with a single orifice have compared to one with multiple orifices? The specifications require that perforations be installed for diameters > DN150; are there any requirements regarding the diameter of these perforations?