Pressure drop through nozzles

The following table gives suggested maximum velocities in exchanger nozzles. The pressure drop through nozzles should be checked, especially where pressure losses are a problem such as in low pressure systems. 

When operating pressure goes below 25 psi on propane or butane, check with the factory to avoid difficulty from pressure drop through nozzles. (See Table V-4.)... 

Nozzle Pressure Drop, AP The pressure drop through a jet mixing nozzle is given by ... 

Flare stack sizing and pressure drop is included with considerations of pressure drop through the safety valve headers, blowdown drums, flare headers, seal drum, etc. Elevated flare tips incorporating various steam injection nozzle configurations are normally sized for a velocity of 120 m/s at maximum flow, as limited by excessive noise and the ability of manufacturers to design tips which will insure flame stability. This velocity is based on the inclusion of steam flow if injected internally, but the steam is not included if added through jets external to the main tip. 

Pumping Head—The energy required to raise water to the distribution elevation and overcome friction losses through pipe, valves, fittings and nozzles. It is expressed in feet of liquid the pump must move and is equal to the total friction loss, static head and pressure drop through the distribution system. 

As air flows through an impactor nozzle, it expands since this is a near adiabatic process. According to Hering and Marple (1986), the pressure drop through an orifice with a cross-sectional area A is... 

Plenums are used to homogenize the incoming gas flows to evenly distribute them to the outlet of the burner. This is important to ensure proper operation of the burner over the entire range of operating conditions, especially at turndown. These gases may include combustion air, premixed fuel and air, or partially premixed fuel and air. If the plenum is too large, then the flows may be unevenly distributed across the burner nozzle outlet. If the plenum is too small, then the pressure drop through the plenum may be excessive. 

Permissible pressure drop through tubes (excluding the pressure drop through the shell nozzles) Ap = 3.5 psi. 

Pressure drop through the vapor distributor or a vapor-distributing support should be at least equal to the velocity head at the column inlet nozzle (386). T3rpically, a pressure drop of 1 to 8 in of water (289) is used for these devices. In one typical specific example (346), it was 4 ins. 

APi B pressure drop in pipework between the tank take-off and jet nozzle A 2 = pressure drop through jet nozzle ... 

The pressure drop through the injection nozzles is certainly 21 psig. But this AP is all due to the disp>ersion steam. The pressure drop through the FCCU feed restriction orifices was only 1 psi. To prove the point we recalculated the AP for the orifice size and found that the calculated orifice AP was also about 1 psi. 

The mechanical design had allowed for a pressure drop through the tube side of 50 psi the operating pressure drop was 70 psi. Partially plugged tubes had greatly increased the normal crude AP. The pass partition had to withstand the high pressure differential. When it finally failed, it was pushed against the channel-head outlet nozzle. 

Vapor maldistribution theoretically could lead to the same lack of performance, as illustrated in Figure 7-5. There is, however, a much better radial mixing of the vapor phase in the packed bed because it almost always is in the turbulent flow regime. Vapor distribution normally is not a problem as long as the pressure drop through the packed bed is at least 0.10 in. H20/ft of packed depth, and the inlet vapor nozzles are operating at Fg vapor rates not greater than 22 Ib /ft s. For columns in which the packed depth is less than the column diameter, vapor maldistribution can be a problem. 

The great advantage of forced circulation is that careful calculation of the pressure drop through the reboiler and associated piping is not critical. But as we can see in Fig. 8.6, the operator now has two tower-bottom levels to control. Further, if the hot-side liquid level rises above the reboiler return nozzle, the force of the vapor and liquid rushing back into the column will cause the trays to flood, but the reboiler heat input will not be affected. 

The experiments to which Weissenberg refers were done during World War II in England on materials for flame throwers. One goal of this research was to improve predictions of the pressure drop through the spray nozzles (Russell. 1946). Gum rubber in gasoline, polymethyl methacrylate in benzene, and similar materials were studied. Figure 4.1.1 shows some of the experiments that were used to demonstrate normal stress effects. 

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