Waste Heat Recovery from Cement Kiln



cement kiln medium

Industrial sector accounts for more than 50% of the global energy consumption. Cement Industry has a 5% share of the global industrial energy consumption. It is one of the highly energy intensive industries. About 80% of the energy consumption for cement production, is at the rotary kiln system for the clicker production. These rotary kiln systems have to be maintained at high temperatures of 900 °C – 1500 °C

More than 40% of the input energy is lost through the kiln shell, cooler stacks and kiln exhaust gases. When all the heat losses are considered, the kiln operates at a low efficiency of around 46%.

WasteHeatRecovery

One of effective methods of improving the efficiency of rotary kiln, is through waste heat recovery around the kiln surface. Radiant panel can be installed along the kiln that can harvest the heat dissipated through the kiln surface.

RadiantPanels

The radiant panels designed and fabricated at Oorja, have a coolant running through them. The heat is transferred from around the kiln to the panels through radiation. The heated “coolant”, which is now around 200-300 °C, is then used for multitude of purposes like :

  • Electricity Generation : The captured waste heat can be utilized for preheating and electricity generation.This in turn would reduce the electricity demand of the plant.
  • Pre-Heating: Waste heat captured can also be used in preheating of the raw material before clinkering process, which leads to more efficient grinding process as the raw material is now at a higher temperature.
  • etc.

Radiant Panels are able to recover about 30% of the heat losses that occur from the kiln surface. This heat recovered helps in tremendous savings in fuel and electricity and greatly helps in reducing the GHG emissions caused by the cement factory.

Energy Savings :

Assumptions :

  • Kiln Length : ~ 50m
  • Kiln Diameter : 3.75m
  • Kiln Surface Temperature : 240 °C
  • Radiant Panels Measurements : 50m X 5m
  • Heat Transfer Efficiency : 55%

Total Heat Recovery per day is 21,114 KWHth

Annual Fuel Savings : Rs. 1.2 Cr.

Annual Electricity Savings : Rs. 2.1 Cr.