Kemija u Industriji (Oct 2011)
Pretreatment of Process Condensate with Ammonia Degassing in CAN Fertilizer Production
Abstract
In the production process of calcium ammonium nitrate (CAN) fertilizer, process-condensate is generated with a high content of ammonium nitrogen. Such high mass concentration of ammonium nitrogen (approximately 2 g L-1) significantly burdens the operation of the wastewater treatment plant, where the process condensate is treated by method of ion exchange. At CAN 1 Plant, a degassing system for process condensate was built. After pretreatment, the concentration of ammonium nitrogen in the process condensate was reduced to less than 500 mg L-1.Before upgrading with degassing system, the process condensate from CAN 1 Plant was collected in tank TK 17 301, from which it was pumped to the wastewater treatment plant to be treated by the method of ion exchange. When CAN 1 Plant is in normal operation, 10 m3h-1 of process condensate is formed with pH around 10, and temperatures around 50 °C. The degassing system of process condensate consists of a new tank, TK 17 504, which is connected with new pipeline to the tank TK 17 301. The process condensate input was transferred from the old to the new tank, TK 17 504. A new pump was installed for regulation of process condensate and bursting above the condensate level.Additional stimulation for ammonia degassing followed, after the return of 12 bar steam condensate into the tank TK 17 504. Consequently, the process condensate temperature increased to 80 C. Degassed ammonia is introduced into the existing system for washing gases and returns into the process of fertilizer production.By degassing ammonia from the process condensate at CAN 1 Plant, 10.7 kg h-1of ammonia returns into the fertilizer production process.Additionally, there has been an improved performance of the wastewater treatment plant, so that in December 2010, the volume of treated wastewater was almost 80 000 m3 which is an increase of 86 %.
