The Role Of Methanator In Ammonia Plant
In the world of industrial chemistry, ammonia (NH3) production plays a key role. Ammonia is an important component used in fertilizers, explosives, cleaning products, and various other applications. A common method for ammonia production is the Haber-Bosch process, which involves the reaction of nitrogen gas (N2) with hydrogen gas (H2) under high pressure and temperature. However, in the production process to produce ammonia, it is necessary to remove some impurities that can be an obstacle in the ammonia formation reaction. One of these impurities is CO and CO2. These gases are generally removed by reacting them with H2, this reaction takes place in the methanator. In this article, we will discuss the role of the methanator in the ammonia industry.
Function of Methanator
The methanator functions to
convert CO and CO2 into methane. CO and CO2 are converted into methane because
CO and CO2 can cause toxicity to the catalyst in the ammonia converter. The
methanator uses a Nickel catalyst, the methanation reaction occurs at a
temperature of 280-300oC and a pressure of 25 Kg/cm2G using the following
reaction equation:
CO2 + 3H2 → CH4 + H2O
CO2 + 4H2 → CH4 + 2H2O
Gas
at a temperature of 300oC enters through the top of the methanator past the
catalyst and the reaction is exothermic to increase the temperature of the gas
coming out through the bottom of the vessel to 347oC. The process of making
methane in the methanator can be seen in the simple flowsheet of the Methanator
in the following figure.
Because this reaction is
exothermic, the CO and CO2 entering the methanator must be controlled no more
than design (CO = 0.5% and CO2 = 0.1%). This is because every % of CO¬2 gas
that reacts with H2 gas results in a temperature increase of about 74oC and the
% of CO that reacts with H2 increases the temperature by about 60oC. At design
conditions, the CO and CO2 inlet methanator are 0.6 and 0.37 moles. The
synthesis gas coming out of the methanator is a mixture of H2 and N2 gas as the
main component, in addition, there are also inert gases in the form of CH4 and
Ar. Parameters that can be monitored in the DCS include TI 1357 ~ TI 1362 which
is the bed temperature equipped with a high alarm.
Advantages of Using Methanator:
Using a methanator in ammonia
production offers several significant advantages:
By effectively removing methane
and converting carbon dioxide, methanators improve the overall quality of
ammonia products. This ensures that the final ammonia product meets the
required purity and quality standards.
The presence of methane and
carbon dioxide can hamper the ammonia production process. Methanators optimize
the process by removing these unwanted gases. Improved efficiency means higher
production rates and lower energy consumption.
Methanators contribute to the
reduction of greenhouse gas emissions from ammonia plants. By converting CO2 to
CH4 and removing methane, they help minimize the environmental impact of
ammonia production
Conclusion
In the chemical industry, ammonia production has a very important role as ammonia is used in various applications, including fertilizers, explosives, and cleaning products. The main method for ammonia production is the Haber-Bosch process, which involves the reaction of nitrogen gas (N2) with hydrogen gas (H2) at high pressure and temperature conditions. However, during the production process, it is necessary to overcome some impurities, such as carbon monoxide (CO) and carbon dioxide (CO2), which can interfere with the ammonia formation reaction. In this context, the methanator plays a key role.