Urea Nitrogen-Based Fertilizers: A Fuel for Growth GEA Ecoflex Plate Heat Exchangers Prove Their Worth in Fertilizer Plants

The world’s population is expanding rapidly, and so too are its energy requirements. Providing food for almost seven billion people, and reducing our dependence on crude oil by using plant-based energy sources, require the targeted use of fertilizers. The production of nitrogen-based fertilizers is a chemically complex process in which heat is repeatedly transferred between the process media. As the world’s leading fertilizer plant engineering company, Uhde relies mainly on plate heat exchangers from GEA Ecoflex.

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Helwan, 30 km south of Cairo on the banks of the Nile, was once a spa resort with its sulfur springs. Nowadays Helwan is a centre of Egyptian heavy industry. Since last year the area has had a new field of production: Uhde, based in Dortmund/Germany, has erected a large plant for the production of ammonia and urea granulate for fertilizer.

This global company has been building fertilizer plants for over 80 years, in recent years mainly in the Middle East. In Egypt and Qatar, where huge reserves of natural gas provide the raw material for ammonia and urea, Uhde has built six turnkey fertilizer plants in the past three years alone.

These plants are already running at over 100 percent capacity. To guarantee production reliability in the highly complex manufacturing process used to make urea fertilizer, Uhde uses mainly plate heat exchangers (PHEs) supplied by GEA Ecoflex. Gasketed PHEs are used for CO2 cooling and residual gas scrubbing, in the urea production plant, and in other process sections.

“The soaring crude oil price has given our business a gigantic boost. Worldwide demand for biofuels is on the increase, and the land area used for plant-based fuel sources is growing continuously. The demand for fertilizers is increasing accordingly,” says Reinhard Michel, Head of the Equipment Group in the Ammonia & Urea Division at Uhde.

Designing for speed and reliability

In order to meet the demand for production plants the engineers at Uhde have been developing a copy concept whereby as many component designs as possible from previous plants can be used—a completely new approach. This reduces engineering costs enormously and minimizes construction time. From initial discussions until the start of production now takes only 36 months.

“We were particularly careful in selecting our partners and component suppliers for this ‘copy concept’”, says Michel, “since every change to a component would mean that the parts of the plant would have to be re-designed. GEA Ecoflex offers good prices, but even more decisive is the quality, and the fact that the company offers reliable after-sales service to our customers. If problems arise, our partner GEA is there to help with their know-how and cooperate with us to find a practical solution.”

The Helwan plant produces 1,200 t/d of ammonia and 1,925 t/d of urea. Ammonia is the basic raw material for urea production. The ammonia plants use Uhde’s proprietary ammonia process, which is based on the well-established Haber-Bosch process. Natural gas is first desulfurized and then catalytically cracked with steam to generate a synthesis gas containing carbon monoxide, carbon dioxide, hydrogen and some methane. The addition of further steam converts carbon monoxide to carbon dioxide, which is then scrubbed out of the synthesis gas. Finally, nitrogen is added by burning methane, carbon monoxide and hydrogen using air, and the resulting mixture of hydrogen and nitrogen reacts to form ammonia (NH3).

“In the CO2 scrubbing process we have three VT 2508 plate heat exchangers in parallel,” says Carsten Reuter, Key Account Manager – Chemical Engineering at GEA Ecoflex. “The CO2 flows into the PHE as a two-phase gas-water mix at 95.2 °C and is cooled to 33 °C against cooling water at 30 °C. The plate design guarantees maximum heat transfer.”

The CO2 is fed into the urea plant together with the ammonia. Uhde’s urea plants use the Stamicarbon process to produce urea ((NH2)2CO).

Each of VT 2508 PHEs stands 3 m high and weighs 10 t, and contains 1000 m2 of high-performance special steel (1.4539; AISI 904 L), giving a heat transfer capacity of 14.5 MW. A total of 16 plate heat exchangers are installed in the Helwan plant for various process applications.

World-scale production

In Damietta, 160 km north of Cairo, Uhde is building a fertilizer complex for the EAgrium operating company that has twice the capacity of Helwan: 2400 t/d of ammonia and 3850 t/d of urea in two parallel plants on a single site. With a value of US$ 1.2 billion, this is the largest single contract in Uhde’s history, and it too will use GEA Ecoflex PHEs.

As the demand for nitrogen-based fertilizers continues to accelerate, production capacities are increasing. At a current urea price of US$ 750/t, operators generate a clear profit of around US$ 1 million per day. “Around two years ago the price for a tonne of urea was less than half that. Demand is simply outstripping supply,” says Michel.

The development engineers at GEA Ecoflex have already made plans for the future with the new NT 500, a development of the NT 350 that allows higher flow rates and so even larger fertilizer plants.

GEA Ecoflex is a part of GEA PHE Systems, the competence center for plate heat exchangers within the international GEA Group, with production facilities on three continents. After-sales service for the PHEs installed in the Uhde plants is provided by GEA Ecoflex Middle East. “It’s a decisive advantage that GEA Ecoflex has a service company on location. A large number of customers specifically request local service by the manufacturers and a contract is only awarded when this condition is met,” says Michel.

Uhde is a company of ThyssenKrupp Technologies. In the 2006/2007 business year Uhde earned around €1.2 billion, a quarter of which was in the building of urea and ammonia plants. As compared with the previous year, incoming orders increased by 84% to around € 2.6 billion.

The author is an employee at GEA Ecoflex GmbH, Sarstedt/Germany.

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