Technical and economical assessment of waste heat recovery on a ceramic industry

Abstract

Waste heat recovery is key for the improvement of several industrial sectors. It has the potential to be used as an energy source and, therefore, to reduce the current industrial energy consumption. The ceramic industry, in particular, encompasses significant thermal processes (the firing and drying) which generate substantial waste heat. This work studies the potential of waste heat recovery solutions for a ceramic floor tile plant. Direct re-use of hot air streams from kiln cooling zones as kiln combustion air is considered, as well as its use as drying agent and combustion air in dryers. The proposed strategies achieve natural gas savings up to 33% in the plant, reducing fuel consumption by 25-29% in kilns, by 44% in a dryer, and avoiding fuel consumption in the other dryer. Moreover, the payback period of all these strategies has been estimated as 0.12 years, which proves the attractiveness of waste heat recovery.

Review on Energy Efficiency Progresses, Technologies and Strategies in the Ceramic Sector Focusing on Waste Heat Recovery

“…[ [112][113][114][115][116][117][118] Modelling and optimisation of thermal process and plants Development of models which describe the specific thermal processes of a ceramic plant (more incidentally tunnel kilns) and the application of optimisation methods to improve the operation of plants.…”

“…From 15 to 30% fuel savings [126]; payback time is negligible [117]. [24,30,117,122,123,126] Exhaust air recirculation in spray dryers…”

“…Hot air recycling between kilns Similar to the hot air recycling in a kiln, the hot air from the cooling zone of a kiln may be used and mixed as preheated combustion air in other kilns of the plant [117]; the more adequate use for a recovered heat air stream is the one that allows to recover the higher thermal energy from that stream (having the lowest thermal loss: that is the closest matching heating need).…”

“…From 15 to 30% in fuel savings [126]; payback time is negligible [117]. [117,126,129] Hot air recycling as drying air…”

“…The hot air from the cooling zone of kilns may be used as an additional heat source in dryers; commonly implemented when part of the hot air is already recovered to the combustion chamber of kilns and a remaining part is recycled to the dryers [117]; in the case the hot air stream has a sufficient waste heat potential, the operation may be converted to disable the need to consume fuel [117].…”