ICT2014 Abstracts

Portland cement is produced by means of one of the most energy intensive industrial processes. China has become the largest cement producer, consumer in the world and its cement production has totaled to 2.35 billion tons in 2013. Energy consumption of Portland cement is about 80~100 kWh per ton. The rotary cement kilns are important equipment in cement production process. A large amount of thermal energy are wasted from the rotary kiln external surface because of its high surface temperature (in the range of 200℃ to 400℃) and large body size (the length may exceed 100 m, and the diameter may from 4 to 6 m). In fact, about 10~15% energy expenditure of cement clinker is directly dissipate into the atmosphere through the rotary kilns external surface.

In this paper, a thermoelectric waste heat energy recovery system from the external surface of the rotary cement kilns is proposed. This system is configured as an array of thermoelectric generation units, which are arranged in a longitudinal direction on the kilns outer shell coaxial with the rotary kiln. A mathematical and economic model for sizing and performance estimation of the waste heat recovery is developed. Meanwhile discusses the main points on the waste heat recovery and energy saving with an example of Φ4.8×72 m cement rotary kiln. Results show that about 206 kW capacity of electrical power generation and 2589 kW capacity of energy saving can be obtained by using Bi₂Te₃ and PbTe hybrid thermoelectric waste heat energy recovery system. Compared with the kiln without thermoelectric recovery system, there are more than 29% of the waste heat from kiln surface is saved by the thermoelectric waste heat energy recovery system.