Dakota Gasification : Gas ammonia plant work increases efficiency and reliability

Overall efficiencies and reliability of the ammonia plant continue to improve, which will be important when the urea facility becomes operational.

Work completed last summer at Dakota Gasification Company 's Great Plains Synfuels Plant to increase efficiency and reliability of the ammonia plant is proving itself.

The work included installing new compressors and turbine work. Jeremy Baranko, Dakota Gas Rotating Equipment Engineer, said the new compressors provide additional efficiency because of advances in modern design and machining.

'The new compressor's much lower vibration amplitudes can also be attributed to the integration of modern technology, such as a squeeze film damper,' Baranko said. 'The reliability improvements are largely seen through the new compressor's dry gas seal system, replacing the original compressor's oil seals.'

A reduction in operating temperature of the feed gas heater yielded a reduction in fuel consumption, and is expected to improve the reliability of the heater.

Recently, an ammonia plant efficiency test was conducted to look at the ammonia plant net energy requirements. Recent improvements have reduced the net energy requirement to run the ammonia plant by an average of 4 percent. At full rates, producing 1,150 tons of anhydrous ammonia per day, the net energy requirement has reduced by more than 6 percent.

The net energy requirement takes into account the feed and fuel gas heating values, the net steam usage, electricity usage, and waste gas heating value to give a quantitative value of how much energy is used to produce anhydrous ammonia.

Overall efficiencies and reliability of the ammonia plant continue to improve, which will be important when the urea facility becomes operational. Ammonia will be a primary feedstock for the unit.