Condenser tubular-type

With surface condensers, the condensation surface is usually formed by tubes, in which the coolant (normally cooling water) flows at speeds from 0.4 to 2 m s . Vapour flows usually around the pipes, as with this construction sufficient cross sections for the large volume flow of the vapour can be realised. As an example of such a condenser. Figure 2.7 shows a tubular type condenser. For condensation... 

Figure 2.7 Tubular type condenser (1) vapour inlet, (2) outlet for not condensed flow, (3) condensate outlet, (4) coolant inlet, and (5) coolant outlet.

Figure 2.8 Tubular type surface condenser with fixed tubes cooling water flows in the tubes vapour flow in the shell room around the tubes.

Figure 2.8 shows a horizontal tubular type condenser with fixed bank of tubes, where the condensation takes place around the pipes and the cooling water flows in the tubes. A disadvantage of this design is the inherent difficulty in cleaning the condensation area. 

In large condensers of the tubular type the condenser usually consists of several separate condensing units and liquid is withdrawn from each. Each of these units is referred to as a partial condenser. However, partial condensation does not give an effective separation between products, and hence it is not generally used as a method of fractionation. The partial condensers that are used in a modem vacuum plant for the separation of gas oil and wax distillate may be an exception. This separation need not be exact, and hence partial condensers are satisfactory (Fig. 7-25). In the past, dephlegmators or partial-condensation towers, cooled either by air or water, were extensively used. 

Water Coolers and Condensers. The design of these equipments is much the same as for the exchangers, and hence only one cooler, the gasoil cooler, will be designed. A tubular type of cooler will be used. 

Surface Condensers Surface condensers (indirect-contact condensers) are used extensively in the chemical-process industiy. They are employed in the air-poUution-equipment industry for recoveiy, control, and/or removal of trace impurities or contaminants. In the surface type, coolant does not contact the vapor condensate. There are various types of surface condensers including the shell-and-tube, fin-fan, finned-hairpin, finned-tube-section, ana tubular. The use of surface condensers has several advantages. Salable condensate can be recovered. If water is used for coolant, it can be reused, or the condenser may be air-cooled when water is not available. Also, surface condensers require less water and produce 10 to 20 times less condensate. Their disadvantage is that they are usually more expensive and require more maintenance than the contac t type. 

The reaction section consists of the high pressure reactors filled with catalyst, and means to take away or dissipate the high heat of reaction (300-500 Btu/lb of olefin polymerized). In the tubular reactors, the catalyst is inside a multiplicity of tubes which are cooled by a steam-water condensate jacket. Thus, the heat of reaction is utilized to generate high pressure steam. In the chamber process, the catalyst is held in several beds in a drum-type reactor with feed or recycled product introduced as a quench between the individual beds. 

A similar unit, modified in details such as location of condenser, use of an agitator and shape of the vessel, was used by Fisher and Whitney . Further substantial modifications to permit interface location of specimens, cooling of specimens and operation under applied pressure, have been described by Fisher . Earlier laboratory test methods tried by Fisher and Whitney included exposure of specimens heated by their own electrical resistance and of tubular specimens containing a pencil-type resistance-wire heater in a quartz tube. 

In the feed pretreatment section oil and water are removed from the recovered or converted CCI2F2. The reactor type will be a multi-tubular fixed bed reactor because of the exothermic reaction (standard heat of reaction -150 kJ/mol). After the reactor the acids are selectively removed and collected as products of the reaction. In the light removal section the CFCs are condensed and the excess hydrogen is separated and recycled. The product CH2F2 is separated from the waste such as other CFCs produced and unconverted CCI2F2. The waste will be catalytically converted or incinerated. A preliminary process design has shown that such a CFC-destruction process would be both technically and economically feasible. 

A relatively simple pore structure of fairly uniform tubular pores would 1) expected to give a narrow Type HI hysteresis loop (see Figure 7.3) and in this cas the desorption branch is generally used for the analysis. On the other hand, if there i a broad distribution of interconnected pores it would seem safer to adopt the adsoif tion branch since the location of the desorption branch is largely controlled b network-percolation effects. If a Type H2 loop is very broad, neither branch canb used with complete confidence because of the possibility of a combination of effect (i.e. both delayed condensation and network-percolation). Furthermore, the condeii sate becomes unstable and pore emptying occurs when the steep desorption branch j located at a critical pjp° (i.e. at c. 0.42 for N2 adsorption at 77 K). 

The pyrolysis unit consisted of an insulated 316 stainless steel preheater tube (1.3 cm i.d. X 50 cm length) which extended 1 in. into a 316 stainless steel fixed bed tubular reactor (2.5 cm i.d. x 46 cm length), which was heated by a cylindrical block heater. Two type J (iron-constantan) thermocouple probes were used to both monitor the internal catalyst bed temperature and maintain a consistent reactor wall temperature in combination with a temperature controller, A syringe pump, condenser, vacuum adapter, receiving flask, nitrogen cylinder, and gas collection system were connected as shown in Fig uTe 2. The reactor midsection was packed with 40 g of activated alumina, which was held in place by a circular stainless steel screen. The preheater and reactor were operated at 180-190 and 450 C, respectively. The entire process remained at normal atmospheric pressure throughout the mn. 

Typical reactor type Mechanically agitated reactor with a heating jacket or condenser Mechanically agitated reactor with a heating jacket or condenser CSTR, tubular reactor, multiple CSTRs, fluidized bed reactor, loop reactor... 

In tissue culture, cells of the rat adrenal cortex with mitochondria of the type found in the z.g. do not respond to ACTH while those of the z. Intermedia show mitochondrial changes to the vesicular types seen in the z.f-r.The tubular and vesicular forms of the endoplasmic reticulum also increase. A large number of dehydrogenases are shown to be present but ATP-ase as well as alkaline and acid phosphatase are absent. Chromatin condensation along the nuclear membrane suggest that ACTH might effect transformation of z.g. cells to those of the z.f-r. by action at the nuclear or gene level. 

With Type II (autophagic) apoptosis, by contrast, chromatin condensation often does not occur until after the cell has fragmented. Vacuolation of the apoptotic body may be prominent, coincident with internal lysosomal degranulation, which may even begin before fragmentation has been completed. Phagocytosis of the apoptotic bodies by adjacent cells in the tissue is often observed in this type. Apoptosis in renal tubular epithelium after exposure to okadaic acid could be considered the prototype for Type II apoptosis. 

Plate evaporators may be constructed of flat plates or corrugated plates, the latter providing an extended heat transfer surface and improved structural rigidity. Two basic types of heat exchangers are used for evaporation systems plate-and-frame and spiral-plate evaporators. Plate units are sometimes used because of the theory that scale will flake off such surfaces, which can flex more readily than curved tubular surfaces. In some plate evaporators, flat surfaces are used, each side of which can serve alternately as the liquor side and the steam side. Scale deposited while in contact with the liquor can then be dissolved while in contact with the steam condensate. There are still potential scaling problems, however. Scale may form in the valves needed for cycling the fluids and the steam condensate simply does not easily dissolve the seale produced. 

This chapter deals with equipment types that are of most interest to a process engineer tubular and plate exchangers condensers boilers and calandrias extended surface equipment mechanically aided heat-transfer devices and tubular chemical reactors. Evaporators are described in Chap. 16. Information on all types of heat-exchange equipment is given in engineering texts and handbooks.i -= °... 

A tubular stainless steel reactor (I.D. 104 mm) heated by an electrical oven at atmospheric pressure is used for the oxidation of toluene [Fig. 1]. The toluene is dosed with an HPLC pump (LKB2150) to an evaporator at 320 °C and then mixed to the O2 and N2 flows which are controlled with mass flow controllers (Bronkhorst High-Tech B. V ). Nitrogen is used as diluent. The catalyst fixed-bed preceded by quartz beads is maintained between quartz wool. The temperature of the fixed-bed is measured with a K-type thermocouple (Philips AG). The outlet gases are cooled in three consecutive condensers. The liquid products are collected and analysed by gas chromatography with a flame ionisation detector for quantification (Perkin-Elmer Autosystem gas chromatograph, capillary column Supelco SPB-1, 30 m x 0.53 mm I.D. X 0.50 jum film thickness) and with an electron ionisation detector for identification (Hewlett-Packard, G1800A, GCD System, capillary column HP-5, 30 m x 0.25 mm I.D. x 0.25 fm film thickness). The experiments are carried out at a conversion less than 5 per cent. 

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