In ammonia synthesis gas cooler, synthesis gas, which is at higher pressure ( 200 bar) is kept in the tubes and cooling water (CW) is kept on the shell side. With passage of time, efficiency of this cooler goes down mainly due to deposits on the CW side in the shell. This increases the load on downstream refrigeration system. This calls for improving efficiency of the cooler, which can be achieved by variuos means, such as circulating demineralized water, which in turn is cooled by CW in a separate plate type heat exchanger, installation of booster pump to increase velocity of CW or installation of an additional cooler in parallel to the existing one. Improving efficiency of synthesis gas water cooler lowers load on refrigeration compressor and thus reduces load on service boilers (FAI, 2013).
In India, this cooler has been replaced with modified design in two plants, while in one plant; additional cooler is provided in parallel to the original one (FAI, 2013).