Computer Simulation and Parametric Analysis of an Old Ammonia Industrial Storage Unit

Abstract

Old chemical plants are still used worldwide mainly in commodities production. These facilities usually hold performance standards and operational points different from original design, which impacts in loss of energetic efficiency and even in products with unsatisfactory quality. Computer simulation nowadays represents a valuable tool when the objective is the optimization of these units. This work aimed the analysis of an ammonia industrial storage unit through computer simulation using COCO, a free-of-charge computer simulator, based on the CAPE-OPEN protocol. Through the simulation of the original design conditions of the unit, it was possible to verify that COCO and the Peng-Robinson Equation of State achieved good accuracy. Using parametric analysis we show that the pressure specification of the received ammonia does not have any influence on the other process variables of the industrial unit. On the other hand, the elevation of the operational pressure of the storage spheres increases the temperature of the exported ammonia in 6 K. This elevation increases the ammonia’s vapor pressure, its tendency to volatilize and causes pump cavitation. Through simulation, a new operational point was proposed. We show that it is possible to obtain an energetic gain of 28.61 kW at the pumps and compressors when comparing to the current operational point. This gain corresponds to an energy cost reduction of 3.34% in this equipment. Under this new condition, the temperature of the exported ammonia can be returned to its original designed value.
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