Ammonia reactor

Figure 5-2. The ICI process for producing synthesis gas and ammonia (1) desulfurization, (2) feed gas saturator, (3) primary reformer, (4) secondary reformer, (5) shift converter, (6) methanator, (7) ammonia reactor.

Why does the ammonia reactor contain more than one catalyst bed and why is it cooled ... 

Nonlinear programming Staged-Distillation column (12.1) < Liquid extraction column (12.2) Gas transmission network (13.4) Ammonia reactor (14.2) Alkylation reactor (14.3) CVD reactor (14.5) Refrigeration process (15.2) Extractive distillation (15.3) Operating margin (15.4) Reactor control (16.3)... 

All multi-wall constructions are considered for a temperature limit of approx. 300°C. Above this temperature the stresses from the shrinking process are disintegrated. For higher temperatures, mono-bloc vessels are used. On the other hand, it may necessary to use multi-wall vessels when te inner wall must be cooled, for example as in ammonia reactors, where the cold inlet gas is fed along the inner wall to keep the temperatures at allowable levels. 

Since the beginning of the manufacture of high-pressure vessels in the early 1910 s their weight have increased continuously up to the beginning of the 1970 s. As an example, the development of ammonia-reactors is shown in Table 4.3-4 [29]. 

Development of size and weight of ammonia reactors since 1910 [29]. 

A selection of ammonia reactors is illustrated in Figures 17.21 and 17.22. These vessels incorporate particularly elaborate means for temperature regulation. The basic flow pattern is indicated in... 

STEAM MAY be produced by cooling the nitrous process gases leaving the ammonia reactor/converter. These gases leave the reactor at 645°C and 1035 kPa, and at a flowrate of 31 706 kg/h. 

Figure 8.21 Simplified flow schematic of the PRISM membrane system to recover hydrogen from an ammonia reactor purge stream. A two-step membrane system is used to reduce permeate compression costs...

In reviewing thermodynamics, the nature of the heat of reaction and whether the reaction is reversible can be investigated. In the synthesis of ammonia, reactors operate at about 200 atm and 350°C and approach the equilibrium conversion of about 70% in each pass. 

Morud, J. and Skogestad, S. (1998). Analysis of instability in an industrial ammonia reactor. AIChE J., 44, 888-895. 

The catalysts can therefore be tuned to the particular conditions pertaining in the particular ammonia reactor, which accounts for the differences in composition between industrially utilized catalysts. 

An alternative process in which catalysts have been prereduced in separate plants, has become favored in recent years. These catalysts are pyrophoric and are therefore stabilized by exposure to nitrogen containing 0.2% oxygen at 100°C. Only a short reaction time is required to reduce the thereby partially oxidized catalyst in the ammonia reactor. 

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