Nozzles, Inlets and Outlets

Calculations relating to the sizing of the exchanger nozzle inlets and outlets are presented in Appendix H.12. 

Nozzles, Inlets and Outlets Three principles must be kept in mind in designing inlets and outlets. 

Membranes should be continued out through all nozzles (inlets and outlets) and over the exterior flange, so that the membrane has no discontinuity. 

Pressure measurements inside the nozzle capillary are done with a transducer (Wagner, Type P-05). The pressure is measured at three locations in the nozzle capillary, at the nozzle inlet (0 mm), in the middle between nozzle inlet and outlet (9 mm), and at nozzle outlet (18 mm). The measurements last for 10 s and data is recorded in a frequency of 0.1 Hz. Measurements of the spray temperature are... 

Configuration Counter current, horizontal, number of tube passes/shell is 4. Nozzle Shell nozzle inlet and outlet diameter is 8 in., tube side nozzle inlet, and outlet diameter is 6 in. 

Mercury vapor discharge from vents of reactors or storage tanks at normal atmospheric pressure is controlled readily by means of activated carbon. Standard units (208-L (55-gal) dmms) of activated carbon equipped with proper inlet and outlet nozzles can be attached to each vent. To minimize the load on the carbon-absorbing device, a small water-cooled condenser is placed between the vent and the absorber. 

Process simulators stop generally at the process specifications for the equipment. For the detailed mechanical design of the equipment, such as heat exchangers and distillation columns, stand-alone programs are often used. They make process calculations, size the equipment, calculate thermal and mechanical stresses, design mechanical support of the parts of the equipment, design inlet and outlet nozzles, etc. 

Sampie Specifications 15 in. (38.1 cm) diameter aluminum ring the ring has a rectangular cross section measuring 1 x 2 in. (214 x 5 cm) the ring is fitted with a series of brass inlet and outlet nozzles... 

Provide inlet and outlet nozzles at one end, and an internal flat cone (see Figure 1). 

Inlet and outlet nozzles sized for pump discharge. 

Couplings are handy to have on the process inlet and outlet nozzles on both the tube and shell sides. These may be used for flushing, sampling, or thermometer wells, thermocouple bulbs, or pressure gages. 

In practice, the distance travelled by the vapour will be less than the vessel length, Lv, as the vapour inlet and outlet nozzles will be set in from the ends. This could be allowed for in the design but will make little difference. 

The tube layout for a particular design will normally be planned with the aid of computer programs. These will allow for the spacing of the pass partition plates and the position of the tie rods. Also, one or two rows of tubes may be omitted at the top and bottom of the bundle to increase the clearance and flow area opposite the inlet and outlet nozzles. 

Another source of pressure drop will be the flow expansion and contraction at the exchanger inlet and outlet nozzles. This can be estimated by adding one velocity head for the inlet and 0.5 for the outlet, based on the nozzle velocities. 

An even number of tube passes is usually the preferred arrangement, as this positions the inlet and outlet nozzles at the same end of the exchanger, which simplifies the pipework. Start with one shell pass and 2 tube passes. 

The tube velocity needs to be reduced. This will reduce the heat transfer coefficient, so the number of tubes must be increased to compensate. There will be a pressure drop across the inlet and outlet nozzles. Allow 0.1 bar for this, a typical figure (about 15% of the total) which leaves 0.7 bar across the tubes. Pressure drop is roughly proportional... 

Allow a drop of 0.1 bar for the shell inlet and outlet nozzles, leaving 0.7 bar for the shell-side flow. So, to keep within the specification, the shell-side velocity will have to be reduced by around J(1/2) = 0.707. To achieve this the baffle spacing will need to be increased to 100/0.707 = 141, say 140 mm. 

An estimate of the pressure loss incurred in the shell inlet and outlet nozzles must be added to that calculated by equation 12.37 see Section 12.9.3. 

The spacing in the end zones will often be increased to provide more flow area at the inlet and outlet nozzles. The velocity in these zones will then be lower and the heat transfer and pressure drop will be reduced slightly. The effect on pressure drop will be more marked than on heat transfer, and can be estimated by using the actual spacing in the end zone when calculating the cross-flow velocity in those zones. 

Inlet and outlet nozzles should be sized (or pump discharge. 

It is necessary first to define the region or control volume for which the momentum equation is to be written. In this example, it is convenient to select the fluid within the nozzle as that control volume. The control volume is defined by drawing a control surface over the inner surface of the nozzle and across the flow section at the nozzle inlet and the outlet. In this way, the nozzle itself is excluded from the control volume and external forces acting on the body of the nozzle, such as atmospheric pressure, are not involved in the momentum equation. This interior control surface is shown in Figure 1.9(a). 

Upon discharge from the nozzle, the droplets are simultaneously accelerated by gravity and retarded by fluid-fricuonal drag The drag force acts in both the honzontal (x directional) and vertical (j directional) dimensions. Thus, two-dimensional particle dvnamics must be considered to properly size the vertical dimension of the vapor space and the horizontal distance between inlet and outlet nozzles (Fig. 4). 

The pressure difference between the inlet and outlet nozzles on either the shellside or tubeside of a heat exchanger may be written in the form... 

The first bracketed term represents the pressure difference between the inlet and oudet nozzles resulting from the difference in fluid velocity, acceleration or momentum, and the second bracketed term represents the pressure difference between the inlet and outlet nozzles from the difference in elevation. 

The tangent to tangent length of the drum will be approximately 24 in. greater than Lf to accommodate inlet and outlet nozzles and baffles. 

Proper mechanical design principles determine the option of cantilevered or centerhung rotor, the shaft diameter, the type and position of bearings, and seal design. The drive train, whether belt driven or direct coupled, is determined by the power requirements and the shaft orientation. The housing must be sufficient to contain the temperature and pressure of the operation and to provide adequate inlet and outlet nozzles for the process fluids. 

The micro mixer was fabricated by UV lithography of SU-8 [54], Two lithography masks were employed, one for the inlet and outlet channels and sidewalls and the other for making the array of micro nozzles. A non-conventional tilted lithographic method was used. A thick layer of SU-8 was exposed at 45° and -45° as well as other angles. A special resist development technique for the small and deep nozzle structures also had to be explored. 

The pressure drop associated with inlet and outlet nozzles can be reduced by selection of other channel types, but the expense is not warranted except for situations in which pressure drop is critical or costly. 

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