Cement industry consumes high energy levels with 4GJ per ton produced in average, 30% of it being electric and 70% thermal [1]. Cogeneration in this type of processes is not widespread; for only a few efforts have been made worldwide to implement methods that take advantage of waste heat stream, given that these contain 36% of the thermal input energy required to produce electricity [2]. Furthermore the implementation of a power generation alternative to feed limestone’s calcinations process is suggested.
This paper is focused on the evaluation of thermal energy recovery strategies through the implementation of cogeneration systems, enabling an increase in efficiency and profitability producing electricity in before and after-processes of the cement production process. This will be achieved using methods of computer analysis implementing the ASPEN HYSIS™ software to simulate the behavior of the systems taking the rotary kiln operating conditions as main input or output variables.
For the implementation of the system two important steps furnace operation will be taken. First one, related to combustion, is performed to produce the energy required in limestone’s processing entering this system, at this point the commercial gas turbine is used, coupled to a generator subsequently taking the power of oxygen-rich flow at the exhaust which is at a high temperature allowing a post-combustion using an afterburner.
Finally, a second stage is evaluated at the downstream of the kiln, where a flow of charged waste gases counts with enough energy to perform an additional phase of power generation using an organic Rakine cycle (ORC).
Evaluation of low-temperature waste heat recovery technologies for the cement industry