One thing that is common throughout the cement industry is their location in dry areas of our country. Cement industries are found in areas where there is abundance of limestone and such areas are deficient in water like Rajasthan, Gujarat, Andhra Pradesh etc.
Due to huge deficit in electrical power production and power requirement by the industry, erratic and unreliable power supply, mostly all the cement factories have their own power production units. The huge water deficit and high cost of water has made ACC to be immensely suitable for its cooling purposes.
ACC stands for Air Cooled Condenser commonly known as Dry cooling system. ‘Dry Cooling’ name is derived in comparison with alternative cooling mechanism utilising water which are commonly called as Wet Cooling Tower or simply Cooling Tower. In comparison with Cooling Tower, Air Cooled Condenser (ACC) only utilizes ambient air for cooling. In ACC finned tube arrangement is used to condense the turbine exhaust steam. Steam is passed through tubes covered with fins, laying on A-frame structure. An Axial flow forced draft fan is used to force the cooling air across tube bundles. Air interacts with hot fins and carries away the heat without directly interacting with Steam. Fins act as point of heat transfer and increase the total available area for heat exchange. Air cooled condenser works on closed cycle.
ACC offers many advantages over other methods or technologies of cooling. This is particularly true for cement industry which faces many problems in its daily operations like ambient dust, water scarcity, low water quality with high Total Dissolved Solid (TDS), Total Suspended Solid (TSS), Calcium, Sulphate, Phosphate, Silica content etc. Use of ACC in such an environment becomes a boon for cement industry.
The foremost advantage that ACC gives is the savings in water cost. As ambient air is used as cooling medium, no water is required for cooling.
Secondly as the steam is in closed cycle and heat is directly taken from the fins, there is no requirement of treatment chemicals. Generally for ACC Demineralised (DM) water is used. Thus all the problems related to fouling and scaling are substantially reduced. This has marked impact on running and maintenance efforts and costs giving absolute peace of mind to the owners.
Thirdly, the very mechanism of working of ACC ensures that no plumes are generated. Thus ACC offers the advantage that these can be setup in populated areas as well.
Fourthly, ACC offers easy maintenance of its cooling equipments. Cement industry is prone to dust generation. This dust may pose problem with other methods or technologies of cooling. ACC offers very simple way to tackle this. Fins are the primary point of heat exchange and dust may accumulate on it. But it can be cleaned by simply imparting compressed air followed by water jet and the whole process of cleaning can be done without disturbing the process. This reduces shut down periods and increases the overall availability of plant.
Lastly use of ACC is environment friendly in many ways. It saves water in water scarcity areas, reduces use of chemicals for water treatment, reduces corrosion in nearby auxiliaries, eliminates plume, eliminates blow down and associated discharge water treatment etc.
As cement industry is generally considered as polluting industry by many, any step taken towards conservation of natural resource and ecology can highly lift its image. Moreover increasing environmental awareness throughout the world and steps taken by governments to implement environmental regulations strictly and incentives offered for the use of environmentally sound technologies, has made the industrial leaders to adopt such technologies. Adopting ACC for cooling in its power generation can be a big step towards such a goal.
Neelkanth Chopade is Senior Manager – Technical with Gactel Turnkey Projects Limited