Steam nozzles

Ejectors are available in many materials of construction to suit process requirements. If the gases or vapors are not corrosive, the diffuser is usually constructed of cast iron and the steam nozzle of stainless steel. For more corrosive gases and vapors, many combinations of materials such as bronze, various stainless-steel alloys, and other corrosion-resistant metals, carbon, and glass can be used. 

There are various designs of flare tips that incorporate such features as central steam injection, an annular ring of steam nozzles, internal air-inspirating steam nozzles, windshields, etc. Table 2 provides some details of suitable types from which selection may be made. 

The motive steam design pressure must be selected as the lowest expected pressure at the ejector steam nozzle. The unit will not operate stably on steam pressures below the design pressure [16]. 

An increase in steam pressure over design will not increase vapor handling capacity for the usual fixed capacity ejector. The increased pressure usually decreases capacity due to the extra steam in the diffuser. The best ejector steam economy is attained when the steam nozzle and diffuser are proportioned for a specified performance [8]. This is the reason it is difficult to keep so-called standard ejectors in stock and expect to have the equivalent of a custom designed unit. The throttling type ejector has a family of performance curves depending upon the motive steam pressure. This type has a lower compression ratio across the ejector than the fixed-type. The fixed-type unit is of the most concern in this presentation. 

Figure 10-164. Direct steam heating of liquids with internal temperature control using variable orifice steam nozzle. (Used by permission Bui. H 150. Hydro-Thermal Corp.)...

The booster ejectors are usually of steel plate (or cast) with Monel steam nozzles. 

Figure 8.46. Steam jet ejector A Steam nozzle B Mixing region C Mixed fluids D Entrained fluid...

FIG. 10-99 Booster ejector with multiple steam nozzles. 

An eroded steam nozzle shows no obvious sign of damage. The erosion is quite uniform and the nozzle interior is smooth. The inner diameter of the jet must be checked carefully with a micrometer. Growth in diameter of just 5 to 10 percent is significant. The nozzle is intended to be replaced periodically, much like the wear ring on a centrifugal pump. 

The 300-psig steam next passes through the steam nozzle. This is an ordinary nozzle. It screws into a hole in the wall, which separates the steam chest from the turbine case. The nozzle is shaped to efficiently convert the pressure of the 300 psig to steam velocity. The pressure of the steam, as soon as it escapes from the steam nozzle, is already the same as the exhaust steam pressure (100 psig). 

It is the velocity of the steam, impacting on the turbine wheel buckets, that causes the turbine to spin. If that is so, then the way to extract more work from each pound of steam is to increase the velocity of the steam as it escapes from the steam nozzle, shown in Fig. 17.1. 

What I wish to achieve is to maintain the same horsepower output from the turbine. But at the same time, I want to force open the governor speed-control valve, raise the pressure in the steam chest, but decrease the steam flow through the steam nozzle. The only way this can be done is to make the nozzle smaller. 

The velocity of the steam escaping from the steam nozzle (see Fig. 17.1) is 25 ft/s, when the exhaust pressure is 30 psig (45 psia). What, then, would be the velocity of the steam if the exhaust pressure were 76 mm Hg (1.5 psia) ... 

Jet problems. These include low motive-steam pressure, excess wear on the steam nozzles, high condenser backpressure, and air leaks that exceed the jet s capacity. To determine whether a poor vacuum in a surface condenser is due to such jet problems, consult the chart shown in Fig. 18.4. Measure the surface condenser vapor outlet temperature and pressure. Plot the point on the chart. If this point is some-... 

Many steam turbines do not have full-ported steam nozzles (see Chap. 17). The existing steam nozzles may then be exchanged for larger nozzles. An increase of nozzle diameter of 10 percent would increase the turbine horsepower by 20 percent. 

SLOW PRESSURE STEAM NOZZLE SIZE DEAERATOR WATER Outlet Nozzle Size PIMP BALANCE LINE NOZZLE S I ZE/QTY. 

The transfer of this principle also benefits from the characteristic conditions that count for microfluidic systems. By using MEMS technologies the geometry of the steam nozzles can be reduced drastically without losing relative accuracy. Thus, the overall dimensions of the pump and also the amount of steam that is necessary for operation is reduced. Another advantage of a micro-diffusion pump is that the capillary forces overbalance gravity forces, which are decisive in the macroworld. Hence it is possible to construct a pump that can be operated orientation-independent. 

WATER ANO I PH. CONDENSATE NOZZLE. SI ZE 2PH. Condensate Nozzle Size 3 LOW PRESSURE STEAM NOZZLE SIZE 3 DEAERATOR wAter Outlet Nozzle Size PUMP balance LINE NOZZLE-S I 2E/QTY. DEAERATCR CRAIN NOZZLE SIZE PUMP K ICXBACK/Sparqer Nozzle Size ACCkSSCft I ES -----------------------------------... 

PH. Condensate Nozzle Size Slow pressure steam nozzle size... 

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