Fired heater reactor

Reducing gas is generated from natural gas in a conventional steam reformer. The natural gas is preheated, desulfurized, mixed with steam, further heated, and reformed in catalyst-filled reformer tubes at 760°C. The reformed gas is cooled to 350°C in a waste heat boiler, passed through a shift converter to increase the content, mixed with clean recycled top gas, heated to 830°C in an indirect-fired heater, then injected into reactor 4. 

Fired Heaters. The fired heater is first a reactor and second a heat exchanger. Often, in reafity, it is a network of heat exchangers. 

Fired Hester a.s a. Reactor. When viewed as a reactor, the fired heater adds a unique set of energy considerations, such as. Can the heater be designed to operate with less air by O2 and CO analy2ers How does air preheating affect fuel use and efficiency How can a lower cost fuel (coal) be used Can the high energy potential of the fuel be used upstream in a gas turbine ... 

FIG. 23-1 Heat transfer to stirred tank reactors, a) Jacket, (h) Internal coils, (c) Internal tubes, (d) External heat exchanger, (e) External reflux condenser. if) Fired heater. (Walas, Reaction Kinetics for Chemical Engineers, McGraw-Hill, 1959). 

Refractory bricks and cements are needed for equipment operating at high temperatures such as, fired heaters, high-temperature reactors and boilers. 

In such cases, radiant heat transfer is used from the combustion of fuel in a fired heater ox furnace. Sometimes the function is to purely provide heat sometimes the fired heater is also a reactor and provides heat of reaction. The special case of steam generation in a fired heater (a steam boiler) will be dealt with in Chapter 23. Fired heater designs vary according to the function, heating duty, type of fuel and the method of introducing combustion air. However, process furnaces have a number of features in common. A simple design is illustrated in Figure 15.19. The chamber where combustion takes place, the radiant section... 

It was noticed that the order of process items in the layout spacing recommendations is almost identical. The furnaces and fired heaters are on the top of the list (see Table 18). The next group is formed by compressors and high hazard reactors. Air coolers, ordinary reactors and high hazard pumps appear next. After that come towers, process drums, heat exchangers and pumps. The last and safest group is formed of equipment handling nonflammable and nontoxic materials. 

We have ranked furnaces unsafer (score 4) than reactors (score 3 or 2), since fired heaters are the most common ignition sources (Instone, 1998) for any leaks. Instone (1989) also lists furnaces as the most commonly involved process items... 

Figure 17.13. Multibed catalytic reactors (a) adiabatic (b) interbed coldshot injection (c) shell and tube (d) built-in interbed heat exchanger (e) external interbed exchanger (f) autothermal shell, outside influent-effluent heat exchanger (g) multishell adiabatic reactor with interstage fired heaters (h) platinum-catalyst, fixed bed reformer for 5000 bpsd charge rate reactors 1 and 2 are 5.5 ft dia by 9.5 ft high and reactor 3 is 6.5 x 12.0 ft.

Figure 17.15. A fired heater as a high temperature reactor, (a) Arrangement of tubes and burners (1) radiant tubes (2) radiant panel burners (3) stack (4) convection chamber tubes (Sukhanov, Petroleum Processing, Mir, Moscow, 1982). (b) Radiant (surface-combustion) panel burner (1) housing (2) ceramic perforated prism (3) tube (4) injector (5) fuel gas nozzle (6) air throttle Sukhanov, Petroleum Processing, Mir, Moscow, 1982). (c) Fired tubular cracking furnace for the preparation of ethylene from naphtha.

Figure 17.33. Heat transfer to stirred-tank reactors (a) jacket (b) internal coils (c) internal tubes (d) external heat exchanger (e) external reflux condenser (f) fired heater (Walas, 1959).

Plans were under way to return a reactor to service. This gaseous phase reactor requires a startup temperature in excess of 500° F (260° C). A natural gas—fired heater provides the heat energy to a circulating combustible heat transfer fluid and the heat transfer fluid flows through the reactor tubes until startup temperature is reached. 

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