Due to developments in the ammonia manufacturing process, we use natural gas as feedstock. Natural gas is being supplied to some plants under production through the Bombay High (H.B.J.) pipeline. The main machinery used in NH3 recovery plants is as follows.
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(i) Organic Reactor.
(ii) Sulphur Hydrogenerator.
(iii) H2S Absorber.
(iv) Heat Exchanger.
(v) Tube Type Furnace.
(vi) Furnace.
(vii) Steam Boiler.
(viii) Shift methane Convertor.
(ix) First stage co-convertor.
(x) second co-Convertor.
(xi) CO2 Generator.
(xii) CO2 Absorber.
(xiii) Air cooler.
(xiv) Metganator.
(xv) Turbo compression with gas turbines.
(xvi) Steam Turbines.
(xvii) Ammonia Coolar.
(xviii) Primary Separator.
(xix) Secondary Separator.
(xx) Synthetesis gas column.
This process is divided into the following parts.
Process Description
Natural gas is sent to the Desulphurisation unit at 40 kg/cm2 pressure which contains activated carbon/ZnO (mostly ZnO is used which removes sulphur H2S). In this process, two Desulphurisation units are installed in the same path. When one is working it receives steam from the conversion of the primary separator. It treats steam and CO2 in 3 - 4 minutes. The steam and gas mixture is passed into a catalyst tube and the gas is perforated up to about 500 °C.
This tube is made of a special mix of metal, the gas obtained from the primary reformer contains 10% unconverted methane. The reforming furnace is made in such a way that it generates steam by recovering waste gas from the flue gas pass and sending it to the NH3 plant. The gas (10% moisture) obtained from the primary reformer is sent to the secondary reformer and the cooled gas is passed through the shift converter where the steam reacts with CO2 due to which some part of CO is converted into CO2 and H2 formation occurs. The conversion into CO and CO2 happens in the following two steps.
(i) High-Temperature Shift Conversion
(ii) Low-Temperature Shift Conversion
In High Temperature Shift Conversion 37% gas remains whereas in low temperature shift conversion, only 0.5% gas remains. To remove CO2 the gas is sorbed in both the towers. CO2 is absorbed by the verified solution under pressure in the first converter, however, it gets regenerated at low pressure in the second tower.
CO and CO2 are converted into methane in the methanation. Thus in the synthesis gas, the amount of CO and CO2 remains less than 10 ppm. K2CO3 or ethanol amine is used as absorption media to remove some CO2 from the verified solution. Synthesis gas is taken under centrifugal compression, in which the gas obtained from the methanator becomes 3 to 10 psi. Which helps in the recirculation of large volumes of ammonia.
A synthesis gas converter is a high-pressure vessel that contains a catalyst in the form of seeds. The reactor temperature is controlled by sophisticated controls. This controller is similar to a refrigeration system. NH3 vapour is cooled by this and sent directly to the urea plant or storage tank under medium pressure.
Conclusion
Recent developments in the ammonia manufacturing process have made ammonia production more efficient and environmentally friendly.
In addition to the above information, the following points are also worth noting:
The ammonia manufacturing process consists of several steps, each of which uses different types of equipment.
The ammonia manufacturing process uses high pressure and temperature, so special precautions are taken for safety.
Ammonia is an important chemical compound used in the manufacture of fertilizers and other products.