Inlet pressure losses

The GPSA Engineering Data Boole provides the following four graphs (Figures 2-5) showing the effect of altitude, inlet pressure loss, exhaust pressure loss, and ambient temperature on power and heat rate. 

As SR decreases, 1 must be decreased too (and thereby also the inlet pressure loss/total pressure ratio is decreased). This is what is really observed when dispersed fillers are added to polymer [182,190,193,194], The rubber phase in heat resistant polystyrene behaves much like a dispersed filler it also diminishes the inlet correction [195]. For polystyrene with different fillers the following relationship was found to be valid [196] ... 

For both conventional and balanced SRVs, the inlet pressure loss, including the mounting nozzle entrance loss, rupture disk flow resistance, and inlet pipe friction, is recommended to stay below 3 percent of the differential set pressure, or else valve instability may occur, resulting in degraded relief capacity. 

Pi = Set pressure - inlet pressure loss + allowable overpressure (21%) + 14.7 psia... 

Rugged design Very sensitive to inlet pressure losses... 

Operation not affected by inlet pressure losses with remote sense In-line maintenance (for some designs) High flexibility of designs and configurations to suit applications ... 

The installed SRV capacity should, however, always be calculated to ensure its flow is sufficient, with the correct inlet pressure losses being considered. For inlet piping loss calculations, see Section 6.1.1. 

The right one is less obvious, but the method of penetration and inlet configuration within the vessel can cause significant inlet pressure losses, as is demonstrated in Figure 6.6. 

The way the inlet nozzle enters the vessel it is protecting can also have a serious impact on inlet pressure losses. Of course, the ones which give the biggest pressure drops are also the most economic vessel penetrations. 

Here we focus on the calculation of the piping inlet losses. The total inlet pressure loss is the sum of the different components explained hereafter ... 

Pi = Relieving pressure (psia) = Set pressure (psig) + Overpressure (psi) -Inlet pressure loss + Focal atmospheric pressure (psia)... 

Pi = Set pressure + Overpressure - Inlet pressure loss (psig or barg)... 

Long blowdown required due to inlet pressure losses above 3% On gas service, a pop or modulating action POSRV can be used. On some pilot valves, blowdowns between 3% and 25% can be achieved. In case of very high pressure losses, pilot-operated valves with a remote sensor should be considered. 

The experimental data obtained by Han [735] with PE at 154°C revealed the inlet pressure drop to increase with increasing shearing rate, at a given entrance angle. In addition to that, the inlet pressure loss was found to decrease with increasing entrance angle from 15 to 60 °C remaining than constant. 

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