Feed-Effluent Exchangers

Feed, animal Feedb ack Feed-effluent exchanger... 

Feed—Effluent Exchanger. The detailed solution for the optimum ATin a feed—effluent exchanger (Fig. 7) involves a quadratic equation for AT, , but within the following restrictions. 

Fig. 7. AT in a feed—effluent exchanger (a) schematic (b) corresponding graphic representation. For example, the optimum AT for a feed—effluent exchanger is computed as follows ...

From these equations, the optimum AP for a feed—effluent exchanger, where the fluid has the physical properties of water and the following values ... 

Fig. 4. Manufacture of styrene by adiabatic dehydrogenation of ethylbenzene A, steam superheater B, reactor section C, feed—effluent exchanger D,...

NO analyzers at the preheater inlet and catalyst vessel outlet monitor NO concentrations and control the ammonia feed rate. The effluent gives up much of its heat to the incoming gas in the feed/effluent exchanger. The vent gas is discharged at about 350° F. 

F. Feed/effluent exchanger nozzle-to-shell weld, cracks in welds and in exchanger tubes. 

I. Catalytic reformer, combined feed/effluent exchanger shell plate postweld heat treated at 1250°F. 

Reactors are normally made of low-alloy steel (selected per API Publication 941) and clad or weld overlaid with type 347 (UNS S34700) SS. The stabilized grades (i.e., type 947 or 321 [UNS S32100] SS) are normally used for all stainless equipment in these units to avoid intergranular stress corrosion cracking (SCC) during downtime. Downtime corrosion is discussed in the next section of this chapter, Feed-Effluent Exchangers."... 

A typical process flow diagram of a catalytic reformer is shown in Figure 3.17. Desulfurized naphtha is heated in feed-effluent exchangers and then passed to a fired heater, where it is heated to 850 to 1,000° F (455 to 540° C) at 500 psia (3,450 kPa) in a series of reactors and fired heaters. In the reactors, the hydrocarbon and hydrogen are passed over a catalyst (often platinum/rhenium based) to produce rearranged molecules, which are primarily aromatics with some isoparaffins. The reactor effluent is cooled by exchange and then passed to a separator vessel. The gas from the separator is recycled to the reactors. The liquid is fed to a fractionator. 

The synthesis loop consists of a recycle compressor, feed/effluent exchanger, methanol reactor, final cooler and crude methanol separator. Uhde s methanol reactor is an isothermal tubular reactor with a copper catalyst contained in vertical tubes and boiling water on the shell side. The heat of methanol reaction is removed by partial evaporation of the boiler feedwater, thus generating 1-1.4 metric tons of MP steam per metric ton of methanol. Advantages of this reactor type are low byproduct formation due to almost isothermal reaction conditions, high level heat of reaction recovery, and easy temperature control by... 

We next try a more aggressive heat recovery alternative as shown in Fig. 5.24. The heat input to the furnace is quite small and most of the heat is provided by the large feed-effluent exchanger. With, our choice of measurement lags (two 1-minute lags in series) and the lag in the furnace., this system cannot be stabilized by feedback control around the furnace if the quench controller is in manual. However, it is possible to stabilize the system with just the quench controller in automatic and the furnace controller in manual. Subsequent tuning of the furnace controller is then easy since the new system is open-loop stable. 

Douglas, J. M.. Orcutt, J. C., and Berthiaume. P. W. Design and Control of Feed-Effluent, Exchanger-Reactor Systems. Ind. Eng. Chem. Fundam., 1, 253-257 (1962). 

Description Dry toluene feed and hydrogen-rich recycle gas are pumped through feed/effluent exchangers and charge heater and into the PxMax reactor (1). Selective toluene disproportionation (STDP) occurs in the vapor phase to produce the paraxylene-rich xylene and benzene co-product. Byproduct yields are small. Reactor efflu-... 

Description The para-depleted liquid C8 aromatics raffinate stream from the paraxylene separation unit, along with hydrogen-rich recycle gas are pumped through feed/effluent exchangers and the charge heater (1) and into the reactor (2). Vapor then flows down through... 

Figure 4.28. Common feed heating schemes (a) Feed-effluent exchange, (b) Feed-bottoms exchange.

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