Design considerations Condensers

Failure is considered both on a local basis i.e., loss of utihty supply to one item of equipment (e.g., electric power to a pump motor) and on a general basis i.e., loss of supply to all consuming equipment in a process unit (e.g., cooling water to all coolers and condensers). For the purpose of these pressure rehef design considerations, a process unit is defined as one which meets all the following criteria ... 

Flooding in an up-flow in a vertical condenser is an important design consideration, because this flooding poses a limit on flows for any selected design. To select the number of tubes required to obtain the area for up-flow without flooding, the diameter of the tubesheet to hold these tubes becomes quite large. The selected number of tubes, to... 

When designing an active or passive system, many design considerations are common to the two systems. For example, some provision for removal of condensation that forms in the exhaust pipe will be required. Routing of the pipes from the basement to the roof must be considered when the house is being designed. Placement of the exhaust is extremely important. 

An important question with regard to the scope of this method for complex carbohydrate synthesis was whether an unstabilized carbohydrate phosphorane might be compatible with a suitably blocked nucleoside aldehyde. Condensation of the ylide derived from XXI with uridine derivative XXIII proceeded under the usual conditions to give a 25% yield of XXIV, from which the N-benzoyl group could be readily removed with methanolic ammonia. The yield from this condensation reaction was not optimized, but its success clearly demonstrated the feasibility of such a transformation, if design considerations dictate the use of a nucleoside directly. 

M/SC on many, in particular, polymer substrates the desorption of adatoms should be taken into consideration. In this case the probability of M/SC phase nucleation at PVD, usually designated as condensation coefficient C, is defined by a competition between desorption of adatoms and their irreversible fixing on a substrate surface. Irreversibility of M/SC atom fixing is provided either by its aggregation with other atoms or by immobilization on surface defect which can be surface steps, outputs of dislocations, vacancies, etc. [42],... 

Column process design specifies the separation, and sets column pressure, reflux, stages, and feed point. These in turn yield internal flows and reboiler and condenser duties. This chapter addresses the main column process design considerations. The column is optimized during the process design, and many times later during operation. Computer control continuously optimizes the column on-line. Both design and on-line optimization are also addressed in this chapter. 

Many hydrocarbon chlorinations that follow free a radical mechanism are associated with the problems of poor selectivity towards the intermediate products. Since most of the time there happens to be a distinct difference between the volatilities of the various chlorinated products, RD can be an appropriate choice of reactor for obtaining better selectivity towards the particular chlorinated product. The important example of commercial relevance is the photochlorination of aromatics such as benzene or toluene [60, 100]. Like hydrogenation, this process is also associated with the use of a non-condensing gas (chlorine) and hence its flow rate would make a significant impact on design considerations. 

At PWRs with ice condenser type containment vessel, design considerations are made such that the installation of flammable gas (electrical) recombiners allow to suppress hydrogen concentration not to reach the flammable condition even after a LOCA. 

A three-phase flooded weir separator is normally used where gas, water, and condensate flow rates are very high. In this design, NLL must be above the weir height. In the flooded-weir design, water and condensate holdups are high. This type of separator is very common where slug is a design consideration. 

Both the reboiling and condensing processes normally take place over a range of temperature. Practical considerations, however, usually dictate that the heat to the reboiler must be supplied at a temperature above the dew point of the vapor leaving the reboiler and that the heat removed in the condenser must be removed at a temperature lower than the bubble point of the liquid. Hence, in preliminary design at least, both reboiling and condensing can be assumed to take place at constant temperatures. ... 

It should be noted that a log-log plot condenses the data considerably and that the transition between a first-power and a 3.4-power dependence occurs over a modest range rather than at a precise cutoff. Nevertheless, the transition is read from the intersection of two lines and is identified as occurring at a degree of polymerization or molecular weight designated n, or, respectively. 

Overhead condensers sometimes need to be located in the stmcture. Usually, partial condensers need to be elevated above the reflux accumulator. Considerable stmcture cost reduction can be achieved if the process can use grade-mounted condensers. Mounting the exchangers at grade may require them to be designed with subcooling so that the reflux accumulator can be located above the condenser. This should be considered as part of the process design. 

A foulinghke problem may occur when condensable vapors are left in the residiie. Condensation may result which in the best case results in blinding of the membrane, and in the usual case, destruction of the membrane module. Dew-point considerations must be part of any gas-membrane design exercise. 

Recirculation of non-boiling liquids can be achieved by bubbling inert gas through the liquid in the reactor jacket. This is less practical for fluids with significant vapor pressure, because the jacket still must be under pressure, and a large condenser must be installed to condense the liquid from the vapor-saturated gas at the jacket temperature. It is more useful with molten metals and salts. For the design details of the reactor tube s inside, the same considerations apply as for a thermosiphon-controlled reactor. 

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