Ammonia synthesis technology

Haldor Topspe s ammonia synthesis technology is based on the S-200 ammonia converter. This is a two-bed radial flow converter with indirect cooling between the beds. Features of the S-200 include efficient use of converter volume and low pressure drop (factors related to the use of small catalyst particles 1.5 to 3.0 mm), and high conversion per pass due to indirect cooling85. 

Commercial plants More than 60 plants use the Tbpspe process concept. In addition, many plants based on other feedstocks use the Topspe ammonia synthesis technology. Since 1988, 52% of all new ammonia production capacity has been based on Tbpspe technology. 

The previous sections mainly considered the individual process steps involved in the production of ammonia and the progress made in recent years. The way in which these process components are combined with respect to mass and energy flow has a major influence on efficiency and reliability. Apart from the feedstock, many of the differences between various commercial ammonia processes lie in the way in which the process elements are integrated. Formerly the term ammonia technology referred mostly to ammonia synthesis technology (catalyst, converters, and synthesis loop), whereas today it is interpreted as the complete series of industrial operations leading from the primary feedstock to the final product ammonia. 

The development of ammonia synthesis technology may be classified into the following three historical phases [139]... 

In the following, a brief description of these ammonia synthesis technologies will be given. For more detailed and currently updated descriptions, reference is made to the respective company websites (40, 41, 42),... 

As mentioned above, Haldor Topsoe A/S, KBR, and Uhde GmbH share the major part of the market for new ammonia synthesis technology. For plant retrofits also others are active and especially for ammonia converter revamps, Ammonia Casale offer their ammonia synthesis technology. The main feature of the Casale technology is the so-called axial-radial flow synthesis converter (55, 56), and (57). 

Understanding ammonia synthesis technology is important for several reasons ... 

The development of ammonia synthesis technology was an economically driven situation, with its own wars in the nineteenth century in South... 

During whole development of catalytic ammonia synthesis technology, Haber completed the research foundation of the theory and the technology for ammonia synthesis, and Bosch made it applicable for industrialization. As a result, the process is called Haber-Bosch process. In 1911, first ammonia plant commenced to be built. In 9 September 1913, the plant with reactor of 285mm diameter and 90L of catalyst was switched on at 200 bar (Fig. 1.8). Initially, aimnonia production was about 3-5 tons per day. But the production scale was rapidly expanded. In 1917, the ammonia produced from Haber-Bosch process exceeded 60,000 tons per... 

Catalytic ammonia synthesis technology is one of the greatest discoveries for human in the 20th century. The fused iron catalyst is one of the most important catalysts in the world. The studies to the currently used ammonia synthesis catalysts have been much deeper than that of any other catalyst. All these work has been reviewed by different researchers at different stages, such as Emmett in 1955, Nielsen in 1968, d7 Slack in 1979, Boudart in 1981, Jennings in 1991, and Somorjai et al. in 1994. ... 

It is well known that the conversion of hydrogen and nitrogen per pass is only 20%-30% for the present catalytic ammonia synthesis technology (Table 1.4). Most synthesis gases need to be returned to the reaction system, which increases power consumption. In order to increase conversion per pass, it must increase the outlet ammonia concentration of reactor. Accordingly, it can be seen from Table 1.4 that it is necessary to increase reaction pressure for small and medimn scale aimnonia plants and Topspe process, or to reduce the content of inert gas in sjmthesis gas for Topspe and Braun processes, or to reduce ammonia concentration in the inlet of converter for small and medium scale ammonia plants and Kellogg process. But all of these operations will add the power consumption or unit gas consumption. 

In recent years there have been major advances in ammonia synthesis technology. These changes have resulted in increased plant capacity, improved reliability, higher efficiency, and lower capital cost. These developments came about in two stages first by the introduction of the large single-stream ammonia plant, and second as a result of the search for maximum plant efficiency. 

Two recent developments have been made to the synthesis loop of the purifier process, in line with the general trend of modem ammonia synthesis technology. First, a third ammonia converter has been added to increase the conversion per pass. Heat recovery between the second and third converters is used for the generation of high-pressure steam. Second, the design of the converter internals... 

The main purpose of the present chapter is to describe modern technology for ammonia production. For the sake of completeness a brief description of the early development of ammonia synthesis technology will be given in the following. More details can be found in the relevant literature. 

Just before the second world war it was a general belief [18] that ammonia synthesis technology was mature, and that no significant further developments could be expected. This was to some extent true, since most of the features which characterize modern synthesis technology - including catalyst type and most major converter designs - were already well proven in industrial operation. However, since that time, there has been a tremendous development in the scale... 

In the foregoing sections the individual process steps involved in the production of ammonia from various feedstocks have been described. However, it is very important how these building blocks are combined with each other, and with the steam and power systems, to form a complete facility for the production of ammonia. The way this is accomplished has a major impact on plant efficiency and reliability, and much of the difference between the several ammonia processes and much of the development in ammonia production technology may today be found in these areas. It may be said that while Ammonia Technology was in the early days of the industry most often understood as Ammonia Synthesis Technology or even Ammonia Converter and Catalyst Technology , it is today interpreted as the complete technology involved in transformation of the primary feedstock to the final product ammonia. 

---