Waste heat recovery units play a vital role in energy conservation
With the installation of Waste Heat Recovery System, ACC is expected to cut down carbon emission drastically. In an interview with Projects Info, KN Rao, Director,-Energy and Environment, ACC Limited, explains its requirement.
ACC has recently installed a Waste Heat Recovery System (WHRS) at the Gagal cement plant. What was the rationale behind it?
The WHRS at Gagal is expected to lead directly to a reduction of over 44,000 tonnes of carbon dioxide (CO2) emissions per annum. Since this energy is based on waste heat and requires no additional fossil fuels, the energy thus produced is green energy that is equivalent to renewable energy. Waste heat recovery can comprise a valuable and reliable alternate source of captive power generation to an industry like cement that is so energy-intensive. In view of the many advantages, units like these mark an important step in sustainable development. We have invested about Rs 100 crore.
How does the entire WHRS system works?
The WHRS system harnesses waste heat discharged in the cement manufacturing process as exhaust gases and converts it into useful electrical energy. Heat from hot flue gases discharged as waste into the atmosphere from the cement manufacturing process is converted into electricity by channelising them into a waste heat boiler that runs a steam turbine using Steam Rankine Cycle technology. The newly commissioned WHRS project, which can generate about 7.5 MW of electricity, comprises a suspension pre-heater boiler, an air quenching chamber boiler, a steam turbine generator, distributed control system, water-circulation system and a dust-removal system.
Does the company have any plans to install WHRS in other facilities too?
Following the commissioning of the WHRS at Gagal, ACC is exploring the possibility of installing the same at Wadi (Karnataka), Jamul (Chhattisgarh), Kymore (Madhya Pradesh) and Chanda (Maharashtra) plants. Basically the economy involved in installing WHRS units offers several advantages. These systems play a vital role in energy conservation, they are entirely environment-friendly as they do not need any additional fuels to generate electricity and hence reduces the cost.
What are your efforts on R&D and safety?
Being the veteran in the field, ACC had faced many technical and financial challenges for upgrading the old processes, and equipment. Today, ACC operates one of the largest kilns in the world and uses state of the art technologies in their new plants. Over the years, ACC, through captive research and development, has taken innovative measures for energy efficiency improvement of the plants.
Some of the initiatives are listed below:
- Conversion of Wet/Semi dry kilns to long dry process / suspension pre heater kilns
- Disengaging some of the inefficient wet kilns and converting them into the refractory kilns.
- Increasing the number of stages of suspension pre heater kilns to 5/6/7
- Introduction of pre-calciners for increasing the thermal and electrical efficiency
- Introduction of high efficiency coolers
- Introduction of pre-grinders for improving the grinding efficiency
- First to develop energy efficient indigenous (1 MTPA) cement plant
- Developed energy efficient mini cement plant with rotary kiln
- First to introduce blended cements (PPC and PSC) in India and registered the largest CDM project in the Indian cement industry
- Using latest grinding technology of vertical roller mills and roller press with efficient separators for grinding of raw materials and finished products
- Efficiency improvement of all process equipment like fans, compressors, pumps, material handling systems, size reduction equipments etc.
- First to introduce Alternative Raw Material in the Use Cement industry
- Co-processing of waste and biomass in cement kilns to reduce the CO2 emission
- Introduction of high efficiency burners, seals, expert control system and variable speed drives, etc
- Conversion of low efficiency (stoker fired boilers) to high efficiency (FBC) boilers
- Introduction of CFBC technology for CPP
- Extensive use of biomass in CPP
- Use of wind energy for cement manufacturing (9 MW)
Efficient lighting and solar energy usage for water heating and operating small water pumps