Preheater-reactor system

Figure 1. Experimental apparatus preheater-reactor system...

Figure 2, Physical model of the preheater-reactor system. Isothermal regions are indicated as a, fixed beds b, fluidized beds c, gaseous regions.

The energy balances on the different zones and regions of the preheater-reactor system yield the following types of terms ... 

The iron carbide process is alow temperature, gas-based, fluidized-bed process. Sized iron oxide fines (0.1—1.0 mm) are preheated in cyclones or a rotary kiln to 500°C and reduced to iron carbide in a single-stage, fluidized-bed reactor system at about 590°C in a process gas consisting primarily of methane, hydrogen, and some carbon monoxide. Reduction time is up to 18 hours owing to the low reduction temperature and slow rate of carburization. The product has the consistency of sand, is very britde, and contains approximately 6% carbon, mostly in the form of Ee C. 

In delayed coking, the reactor system consists of a short contact-time heater coupled to a large drum in which the preheated feed soaks on a hatch basis. Coke gradually forms in the drum. A delayed coking unit has at least a pair of drums. When the coke reaches a predetermined level in one drum, flow is diverted to the other so that the process is continuous. 

A pulse reactor system similar to that described by Brazdll, et al( ) was used to obtain the kinetic data. The reactor was a stainless-steel U-tube, composed of a l/S" x 6 preheat zone and a 3/8" X 6 reactor zone with a maximum catalyst volume of about 5.0 cm. The reactor was Immersed In a temperature controlled molten salt bath. 

Prepare a chemical engineering design of the preheater vaporiser superheater-reactor system and indicate the type of instrumentation required. 

Figure 17.23. Representative temperature profiles in reaction systems (see also Figs. 17.20, 17.21(d), 17.22(d), 17.30(c), 17.34, and 17.35). (a) A jacketed tubular reactor, (b) Burner and reactor for high temperature pyrolysis of hydrocarbons (Ullmann, 1973, Vol. 3, p. 355) (c) A catalytic reactor system in which the feed is preheated to starting temperature and product is properly adjusted exo- and endothermic profiles, (d) Reactor with built-in heat exchange between feed and product and with external temperature adjustment exo- and endothermic profiles.

In this process (Figure 8-6), the feedstock, usually a vacuum residuum, is fed to the preheater and then enters the bottom of the fractionator, where it is mixed with the recycle oil. The mixture is then fed to the reactor system that consists of a pair of reactors operating alternately. In the reactor, thermal cracking... 

Openloop Response The openloop response of the seven-bed adiabatic reactor system with cold-shot cooling to a 20% increase in recycle flowrate FR is shown in Figure 6.17. The inlet temperature of the first reactor decreases because of the larger flow through the preheat system. However, the reactor inlet temperatures of the other reactors increase because the cold-shot flows are fixed. Then the first reactor inlet temperature starts to increase at 5 min because of the increase in the exit temperature of the seventh reactor. The pressure initially increases gradually because of the lower temperature in the first reactor. At about 12 min, the pressure drops rapidly because of the large increase in temperature in the first reactor. 

In Chapters 5 and 6, high-temperature exothermic tubular reactor systems were considered. All of these systems used feed-effluent heat exchangers (FEHE) to preheat the feed to the desired reactor inlet temperature by recovering heat from the hot reactor exit stream. Some of the systems also used a trim furnace to add additional heat if needed. 

A commercial rotary, resistance-heated vertical reactor system for semi-continuous operation (Rotox-60) is sold by Unicorp, Inc., CA. It features premixed gas input through four tubes inside the conical deposition chamber for uniform distribution, and has separate stations on a carrier disk for wafer loading/unloading, preheating, deposition, and cool-down. As many as seven 5 cm wafers can be accommodated per station. The maximum oxide deposition rate is 1,700 A/min, with a conservatively estimated overall uniformity of 5% (Kern, 1975). 

In the particular reactor system employed, structure of the black is more easily controlled by injecting the selected feedstock as a liquid, rather than as a vapor or gas. In this case, the distribution of the oil injected into the combustion chamber can be controlled by mechanical means. The point of initiation of the reaction can also be moved along a line in the reactor to make it short or long at will. Structure then is more dependent upon the feedstock, its boiling range and preheat temperature, and the point within the reactor selected for reaction initiation. Structure can also, of course, be altered downward through the use of feedstock additives. 

Prepare a heat balance diagram of the preheater-vaporizer-superheater-reactor system. 

Catalytic reactions were performed in two differential reactor systems under 1 atm.. The laboratory reactor consisted of a glass tube heated by a furnace. A glass packing was used as preheater. The catalytic charge was always 200mg. 

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