Comparison of Kalina cycles for heat recovery application in cement industry

Abstract

The comparison of two Kalina cycles, KCS1 and KCS34 was performed for the cogeneration of electricity from waste heat recovery in the cement industry. Cement industries with clinker daily production capacities between 3,000 and 6,300 t/d were explored. Both Kalina cycles were thermodynamically modeled from mass, energy and entropy balances, heat transfer for the cycle heat exchangers, and equipment cost. The models were developed in Engineering Equations Solver and optimized with genetic algorithm. The objective functions of the optimization were the net power generated and the specific investment cost. The results of thermodynamic modeling showed which cycle parameters influence as independent variables the objective functions allowing to define their limits. It was also observed that a right definition of costs of the system goes through the proper selection of the turbine and the correct dimensioning of the cycle heat exchangers, especially those that make up the heat recovery steam generator. The comparison between the cycles was performed based on the optimization results and allowed us to conclude that the configuration of the Kalina cycle to be used should be analyzed in detail. Both, KCS1 and KCS34 can be used for waste heat recovery in cement industry but, from the point of view of the specific investment cost, the Kalina KSC1 cycle was more competitive. From the point of view of the net power generated this cycle is more promising for daily capacity equal to or greater than 5000 t/d, and the Kalina KCS34 cycle is more interesting for smaller capacities.