Ammonia-water based thermal conversion technology: Applications in waste heat recovery for the cement industry

Cement production is one of the most energy intensive industrial processes in the world. In many world regions, energy cost is 50% to 60% of the direct production cost of cement. Energy cost is incurred due to the need for large quantities of thermal heat for the kiln, calcination and drying processes and electrical energy for operation of motors for grinding mills, fans, conveyers and other motor driven process equipment. As electricity prices increase, cement producers are installing energy saving devices throughout cement plants to incrementally reduce purchased power. A major energy conservation project available to each cement facility is utilization of the exhaust gases from preheater towers and clinker coolers to produce electricity. Both of these heat sources are classified as medium to low temperature heat for electrical power generation. These heat streams are well matched for use of the Kalina Cyclereg process for waste heat recovery (WHR) to produce electricity. This paper describes the conditions of typical cement plant heat sources available for utilization to generate electricity. The sources of heat from cement plants are compared with specific heat sources utilized in existing Kalina Cycle power plant projects. The Kalina Cycle is described for power generation "inside the fence" of a cement plant facility including specific environmental and operational safety considerations