Recycle Purge Gas for Additional Ammonia Production from an Existing Ammonia Plant

Installation of a purge gas recovery (PGR) unit is the modern trend for additional production from an existing ammonia plant. Shriram has placed an order for PGR unit for their 600 TPD ammonia plant at Kota in India. The installed cost for complete unit will be about Rs. 20 million & additional ammonia production shall be 17 tpd. The PGR unit is scheduled to be commissioned in the first quarter of 1985. Meanwhile, as a first step towards achieving additional production, 1000 NM3/hr of purge gas from synthesis loop was recycled into primary reformer exit geses. In actual practice over a period of seven days, additional ammonia production was 6 TPD and no detrimental effect was observed anywhere in the plant. It costs Rs. 0.05 million for installing the purge gas recycle system. This paper gives steady state mass balance both for the base plant & yhe plant with purge gas recycle. It explains how additional ammonia production is achieved by recycling purge gas.