Producing Ammonia from Syngas and Our Syngas Coolers

For a company operating in the chemical and petrochemical sector, like Cividac, being present in the Gulf region is a fundamental strategic asset.

And it's exactly in this area that we had the opportunity to contribute to important projects with one of the largest companies in the industry, such as Kuwait's Petrochemical Industries Company (PIC).

PIC was formed in 1963, and is now a subsidiary of Kuwait Petroleum Corporation, the national oil company. In particular, it operates in the production of fertilisers and ammonia. Over the last years, we had the opportunity to design and deliver several Syngas coolers for their ammonia plants.

But what is Syngas? To answer, let's start by stressing the importance that ammonia has in the chemical industry. Not only is it one of the main components of fertilizers, but it's also widely used in other sectors, such as the pharmaceutical, household cleaning, and fermentation industries.

The four steps of ammonia production process

Ammonia is composed of one atom of nitrogen and three of hydrogen and it's synthesised in four phases, using two main ingredients: air (for the nitrogen) and methane gas (for the hydrogen).

In the first phase, high-pressured hot methane gas and steam are combined through a catalyst. The result is carbon dioxide and hydrogen.

In the second phase, air is added to the mix, resulting in four components: carbon dioxide, hydrogen, nitrogen and water vapour.

The next step will be to remove CO2 and to dry the vapour, in order to remain with ammonia's two main components: nitrogen and hydrogen. This mix is called Syngas (synthesis gas).

Before moving to the last phase, the Syngas is first compressed and then cooled, to neutralise the heat produced by compression.

Finally, in the fourth stage, nitrogen and hydrogen are combined in a reactor through a catalyst. For the ammonia to be collected and stored, the Syngas has to be cooled once again. The part of Syngas that did not become ammonia is sent back to the reactor.

The Syngas cooler: a fundamental component

As we can see, Syngas coolers are employed twice in the last phase, before and after the final reactor, and are one of the essential pieces of the whole process of ammonia production.

The peculiarity of this type of exchanger is not that it has to manage very high temperatures (which remain relatively low, considering that water is used for cooling), but that it needs to endure very high pressure, which can reach 200-250 Barg through different stages.

For this reason, a Syngas cooler needs to be designed using particular shapes, a large thickness (over 100mm), and a solid structure. The tap is mounted with screws of 80mm of diameter, which are screwed using hydraulic rather than more conventional tools.