Tube-Cooled Converters

Topsoe (1940s) First converters tube cooled. Later quench cooling and radial flow. 

Fig. 7. Methanol converter types (a) quench, (b) multiple adiabatic, (c) tube-cooled, and (d) steam-raising.

Tube-Cooled Converter. The tube-cooled converter functions as an interchanger, consisting of a tube-filled vessel with catalyst on the shell side (Fig. 7c). The combined synthesis and recycle gas enters the bottom of the reactor tubes, where it is heated by the reaction taking place in the surrounding catalyst bed. The gas turns at the top of the tubes and passes down through the catalyst bed. The principal advantage of this converter is in... 

Fig. 9. Tube-cooled converter temperature profile. A, adiabatic bed B, tube-cooled bed C, equiUbrium line and D, maximum rate line.

Figure 11.5 Examples of ammonia synthesis converters (a) tube-cooled, axial-flow converter (Twigg, 1996, p. 438 reproduced with permission from Catalyst Handbook, ed. M.V. Twigg, Manson Publishing Company, London, 1996.)...

Figure 11.6 Examples of methanol synthesis converters (a) tube-cooled, low-pressure reactor A nozzles for charging and inspecting catalyst B outer wall of reactor as a pressure vessel C thin-walled cooling tubes D port for catalyst discharge by gravity (b) quench-cooled, low-pressure reactor, A,B,D, as in (a) C ICI lozenge quench distributors (Twigg, 1996, pp. 450, 449 reproduced with permission from Catalyst Handbook, ed. M.V. Twigg, Manson Publishing Company, London, 1996.)...

Tube collectors, 26 702 Tube-cooled converter, in methanol synthesis, 26 309 Tube furnaces, 12 739 Tube-in-orifice jet nozzle design,... 

Liquid Sulphur Dioxide.—Sulphur dioxide was the first gas to be converted to the liquid state.4 It can be liquefied by passage through a tube cooled to below —10° C. in a freezing mixture,5 but commercially the liquid is produced by compression.6 The sulphurous gases from burning iron pyrites or some other suitable source, containing some... 

As discussed above, several different types of ammonia converters are available. These types include axial quench converters (e.g., standard Kellogg reactors), tube cooled converters (e.g., TVA and Synetix designs), axial-radii designs (e.g., Ammonia Casale retrofit) and Kellogg s horizontal design. Typical operating data for different types of ammonia converters are shown in Table 6.4204. 

Figure 83. Countercurrenl tube-cooled converter (TVA converter) [842]...

Other tube-cooled converters with countercurrent flow are the Mont Cenis reactor [848], [852], [856], the original Haher-Bosch reactors [854], the Claude converter [856], [857], and the older Fauser design [852]. These converters were all used in relatively small plants and are now obsolete. 

An interesting rebirth of the countercurrent principle is the new ICI tube-cooled converter used in the LCA process. 

Figure 84. Tube cooled ammonia converter (Fast Engineering)... 

Converters with indirect cooling have been known since the early days of ammonia production, for example, the Fauser-Montecatini reactor [843], [844], [848], [867], [891]-[893], In this converter, tube coils between catalyst beds transfer the reaction heat to a closed hot water cycle under pressure, operating by natural draft. The hot water releases the absorbed heat in an external steam boiler generating about 0.8 t of steam per tonne of ammonia at about 45 bar (ca. 250 °C). 

In this paper the various routes to methanol synthesis are summarized and compared with a new catalytic partial oxidation route. Also compared are quench, steam raising and tube cooled converters, along with comparative energy and economic stannaries of the various routes. 

The concept of the new tube-cooled converter is a simple gas to gas heat exchanger with no high differential pressure tubesheets. The reactant gas is fed into the bottom of the TCC where it is directed upward and preheated to reaction temperatures through multiple tubes. Upon exiting the tubes, the reactant gases are channeled downward into the catalyst which is... 

After coirparing the various options to methanol production, a new methanol plant design evolved which utilizes catalytic oxidation syngas generation and the tube cooled methanol converter. This new route was... 

FIGURE 5 I. C. I. QUENCH CONVERTER VS TUBE COOLED CONVERTER... 

A mixture of nitroethane (25 ml), D20 (25 ml), and anhydrous sodium acetate (10 mg) was heated overnight in a sealed bomb-tube at 90°. After the tube had been opened, its contents were placed in a vacuum-distillation apparatus, which was cooled in an ice-bath and evacuated. The upper layer of [l,l-D2]nitroethane distilled through an U tube filled with Drierite and was frozen into a U tube cooled to — 78°C. The yield amounted to 19 ml. Repetition of the procedure gave 11 ml of [l,l-D2]nitroethane. This product was then readily convertible into [1-D]acetaldehyde. [D3]Nitromethane, similarly prepared,86 is a convenient starting material for [D3]methylamine. 

In the Scientific Design process (13,14), air, ethylene, and recycled gases are passed over a fixed-bed, supported silver catalyst at 230-350° and 150-300 psig. The catalyst is in tubes cooled externally by an organic cooling medium. A smaller, secondary, once-through reactor is used to convert much of the unreacted ethylene in the pui e gases. 

Lewin, D.R., and R. Lavie, Optimal Operation of a Tube Cooled Ammonia Converter in the Face of Catalyst Bed Deactivation, I. Chem. Eng. Symp. Ser., 87, 393 (1984). 

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