Ammonia manufacturing

Operational Constraints and Problems. Synthetic ammonia manufacture is a mature technology and all fundamental technical problems have been solved. However, extensive know-how in the constmction and operation of the faciUties is required. Although apparendy simple in concept, these facihties are complex in practice. Some of the myriad operational parameters, such as feedstock source or quaUty, change frequendy and the plant operator has to adjust accordingly. Most modem facihties rely on computers to monitor and optimize performance on a continual basis. This situation can produce problems where industrial expertise is lacking. 

A ruthenium-based catalyst is used but low yields resulting from unexpected side reactions are stiU a problem. Refinement of alternative route ammonia manufacture and advances in genetic engineering, allowing a wider range of plant life to fix nitrogen in situ should provide assurance for long term world food needs. 

P. Rudolph, The Eurgi Pressure Gasification and Its Application for Ammonia Manufacture, Fertilizer Association of India, New Delhi, India, 1973. 

Manufacture. Historically, ammonium nitrate was manufactured by a double decomposition method using sodium nitrate and either ammonium sulfate or ammonium chloride. Modem commercial processes, however, rely almost exclusively on the neutralization of nitric acid (qv), produced from ammonia through catalyzed oxidation, with ammonia. Manufacturers commonly use onsite ammonia although some ammonium nitrate is made from purchased ammonia. SoHd product used as fertilizer has been the predominant form produced. However, sale of ammonium nitrate as a component in urea—ammonium nitrate Hquid fertilizer has grown to where about half the ammonium nitrate produced is actually marketed as a solution. 

Research in catalysts for ammonia manufacture is stiU going on, and though the use of supported metals such as mthenium may be two to three times as active as promoted iron oxide, catalysts 50—100 times more active than promoted iron oxide are required to affect process economics significantly. 

Improvements in ammonia manufacturing processes have reduced operating pressures. In the 1930s ammonia plants operated at pressures as high as 600 bar. In the 1950s, process... 

FIGURE 9.17 The Haber process is still used to produce almost all the ammonia manufactured in the world. This pie chart shows how the ammonia is used. The figures are percentages. Note that 80%— as shown by the green band—is used as fertilizer, either directly or after conversion into another compound. 

The Haber process for ammonia manufacture, which operates above the critical point of ammonia. 

Bosch also helped develop Haber s process into an industrial process. In 1913, Haber and Bosch opened an ammonia manufacturing plant in Germany. A year later, World War I started. Saltpeter had another use besides making fertilizer. It was also necessary to make nitric acid that was used to make explosives. When the war started, the British Navy quickly cut off Germany s supply of Chilean saltpeter. If not for the Haber process, some historians estimate that Germany would have run out of nitrates to make explosives by 1916. The war lasted another two years, however, because Germany did not need to rely on outside sources of nitrates for fertilizers or explosives. 

Electrolysis continued to be used for primary enrichment in countries with abundant electric power, such as Iceland and Norway, where the H2 is used in ammonia manufacture [9]. Molecular deuterium, D2, is produced in Norway by the electrolysis of DzO. For heavy water production, the method has, for the most part, been replaced by steam-H2S exchange columns for heavy water enrichment ... 

The SMR is by far the most important and widely used process for the industrial manufacture of hydrogen, amounting to about 40% of the total world production [7]. The technology is well developed and commercially available at a wide capacity range, from <1 t/h H2 for small decentralized units to about 100 t/h H2 for large ammonia manufacturing plants [8]. 

Harding, A. J., Ammonia, Manufacture and Uses, Oxford University Press, London, 1959. 

A methanator converts the last traces of carbon dioxide to methane, a less interfering contaminant in hydrogen used for ammonia manufacture. 

Over 90% of all carbon dioxide is made by steam-reforming of hydrocarbons, and much of the time natural gas is the feedstock. It is an important by-product of hydrogen and ammonia manufacture. 

Metal Hydride Process for Ammonia Purge Gas, The metal hydride process will be illustrated using the case of hydrogen recovery from an ammonia purge gas stream generated during ammonia manufacture. 

Ammonia Manufacture of fertilizers, explosives, ammonia Irritation... 

The process for ammonia manufacture will vary somewhat with the source of hydrogen, but the majority of ammonia plants generate the hydrogen by steam reforming natural gas or hydrocarbons such as naphtha (Fig. 2). 

FIGURE 1 Ammonia manufacture from hydrogen and nitrogen by the Haber process. 

FIGURE 2 Ammonia manufacture from natural gas or naphtha. 

From 1940 to 1950 the number of ammonia plants doubled then from 1950 to 1960 the number more than doubled again. Since 1963, there has been a revolution in ammonia-manufacturing technology. The advent of large singletrain plants has resulted in a large increase in production capacity, the shutdown of a number of smaller plants, and a reduction in manufacturing costs. Capacity tripled in the period from about 1958 to 1968. 

Ammonia manufacture from natural gas by the steam reforming process is well documented. Briefly, raw synthesis gas consisting mainly of H2, N2, and C02 is produced by primary and secondary steam reforming and CO shift conversion this is followed by bulk C02 removal, elimination of residual CO and CO2 through methanation, and ammonia synthesis. These basic steps... 

For some uses of by-product hydrogen, such as ammonia manufacture in particular, it is essential to avoid the presence ofexcessive amounts of residual methane. Thb is replaced by one of the synthesis reactants, with scrubbing by liquid nitrogen (see Section 1.3.1.1). 

Ammonia (mp —77 C, bp. ois —33J C. 4 " 0.6650y recovered during the water scrubbing of raw coke oven gases accounts for only a very small firaction in comparison with ammonia manufactured from its elements. 

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