Current Developments in Antipollution Control in the Fertilizer Industry
Illustrated by a Case Study for an Urea Granulation Plant
The fertilizer industry is currently building new plants which comply with the stricter antipollution laws in force today.
Existing plants operating older scrubbing equipment are being required to improve their environmental standards which in turn induces a need for more efficient systems while reducing maintenance whenever possible.
We will analyse the increase in environmental performance of a specific fertilizer plant for producing urea and more specifically one using the fluidized bed granulation technology.
SOCREMATIC, part of the PROCEDAIR/FIVES-LILLE GROUP started to install «TURBULAIRE » scrubbers » at the end of the seventies in a urea fluidized bed granulation plant in Holland.
Since then several systems using this unique Venturi type ring system have been installed worldwide in urea plants using the HFT fluidized bed granulation process.
An in-depth analysis of major technical factors observed during an extensive survey of installed pollution control systems led us to propose several developments in order to achieve higher efficiency, better reliability and lower maintenance. They were implemented in different newly built plants over the last five years and some have been in full operational
service for a while.
Current feedback proves the validity of these developments and strengthens the will to even further increase their environmental performance.
As well as reducing the urea dust emission from the granulator and coolers to a concentration of less than 30 mg/Nm3, SOCREMATIC has recently studied and proposed an antipollution system to lower the residual gaseous ammonia content to values lower than 20 ppm in the exhaust stack.
The ammonia abatement system will use a urea solution acidified by an inorganic acid and will be located in the existing scrubber vessel. The resulting salts however, will not contaminate the final product as they will be evacuated to a separate recycling tank. The first of these will be installed in a new fertilizer plant in Asia and will start operating in 2001.