Relook at energy conservation in Cement Factory

A cement factory is big Energy guzzler. Each component of the processing plant is equally critical. Small reduction in energy consumption can yield big commercial and environmental benefits. Some of the aspects to ponder upon are: Fuel:

Due to frequent variations in the quality of coal, inadequate supplies and transportation bottlenecks go for substitute fuels like, lignite, rice-husk, petroleum coke etc. Use alternate fuels such as natural gas and pet coke. Use industrial and agricultural combustible wastes as supplementary fuel.

Power Supply:

For uninterrupted power supply have your own captive power plant.

Operational Measures:

Use improved insulating bricks/blocks in kiln and preheaters. Rationalise compressed air utilisation. Use energy efficient equipment High efficiency fans Improved Ball Mill internals Carry out Heat and gas balance Recover waste heat of preheater and use for co-generation of power. Increase utilization of waste products generated by other industries(substitution like use of fly ash and petroleum coke, the by-products of thermal power and refinery industry respectively) Install fly ash handling & feeding system. Reduce energy consumption in manufacturing at each stage & monitor energy performance of the plant. Prevent idle running of equipment by providing interlocking arrangement and operating with PLC system. Generate daily report on idle running of equipment, also in terms of monetary losses. Eliminate ingress of false air into the kiln, cooler, coal mill, cement mill and raw mill circuits by plugging leaks. Optimise raw mix Use low ash coal Adopt preventive maintenance approach Repair steam leaks Reinforce heat insulation Establish efficient management information system for identifying various important parameters for efficient operation of the equipment and taking timely remedial measures. Regularly monitor and calibrate flow meters. Minimize waste by installing efficient dust collector equipment. Modify the equipment to recover heat from the preheater and cooler in the process of cement making and effective use of industrial waste. Use exhaust gas from kiln to dry raw material and coal etc. Carry out energy audits. Before improving a process, activities of good housekeeping and equipment improvement should be applied to promote energy conservation. Avoid extra fine grinding of product to prevent wastage of power since it does not enhance long term strength.

Air Compressor:

Reduce compressed air pressure from 8 Kg/Cm2 to 7.0 Kg/Cm2 where ever possible to conserve energy, when required pressure at usage point is 6.0 Kg/Cm2 Stop use of compressed air for floor cleaning. Check for compressed air leakage and arrest it. Switch off one compressor if requirement can be met by balance operating compressors.

DG Sets Operation and Maintenance

Improve SFC of the DG sets DG sets flue gas temperature is more than 4500C install waste heat recovery boilers on DG sets to generate additional power & pre heat fuel oil Improve specific electricity generation by loading in excess of 60% and up to 80%

Motors:

Replace under loaded / overloaded motors with proper size motors. Replace the motors with energy efficiency motors. Prevent idle operation of the motors

Transformer

If possible switch off one transformer running under loaded in parallel. Maintain all transformers at a loading of 70 to 80 % of rated capacity to minimise loss component (no load losses). Try to have separate transformer for lighting where voltage can be kept low.

Power Factor :

Improve power factor by regular checking of current of all the capacitors and their timely replacement. Install Automatic power factor correction device to have power factor of 0.99 to 1.00

Lighting :

Replace 40W Tube light by slim 28W Tube light and electromagnetic choke with electronic choke. Replace 400 Watt Mercury Vapour lamps with 250 Watt sodium vapour lamps or 250 W metal halide lamps. Replace 250 Watt Mercury Vapour lamps with 150 Watt sodium vapour lamps or 150 W metal halide lamps. Provide more transparent sheet instead of asbestos sheets to use natural light. Install energy saver for reducing the lighting load. Prevent unnecessary lighting of the electric lamps. Rationalise lighting in identified areas i.e. remove excess lighting in identified areas. Also relocate lighting, if necessary.

Resurgence of Coal

Coal has been the first primary ‘Stocks’ energy source that found Industrial application. Power plants and metal refineries were built on coal based energy source. It triggered and sustained the industrial revolution till 1950s, when the oil arrived as a more convenient, economical and less polluting. Even gas-dash of 1990s could not displace Coal from the second position. This is essentially due to the fact that there is abundance and widespread geographic availability of coal. The R/P of coal is the best at 197 years.

At current consumption rates and with current technology and land-use restrictions, the U.S. coal reserves would last well over 250 years. US is hailed as Saudi Arabia of coal.

With improved technologies, estimated recoverable coal reserves, at current consumption rates, are estimated to be sufficient for 500 years or longer.

Both OECD (Organization for Economic Cooperation and Development) nations and the upcoming non-OECD countries are replete with coal based installations.

Three nations account for 60% of world coal use i.e. China, US and India. Energy demand is growing rapidly in China and India and both nations get most of their electricity from coal. The US Department of electricity projects that world coal consumption will rise by 60% from 2010 through 2030 and that China and India will account for nearly three-fourths of the increase.

An exponential increase in world demand for energy, geopolitical development, growing concern on imports and security of supply, uneconomical non-fossil energy sources, indecision about nuclear power are all factors which are contributing to the resurgence of coal.

Coal is considered attractive again because its prices are low and stable relative to those of petroleum and natural gas, which swing unpredictably.

But some reviewers believe that the current haste has more to do with fear and hunger to garner as much energy resources as possible. Coal use, primarily for the generation of electricity, now accounts for roughly 20 percent of global GHG emissions. With the ghost of climate change looming even larger in the public consciousness, utilities are anticipating that the time will soon come when regulators will slap a limit on carbon emissions from electric power generators and perhaps other industrial sources, and that the more coal-fired capacity the producers build before that day of reckoning, the higher their share of the total cap will be.

This renaissance is taking place in many countries, but by far the most important driver is escalating demand for coal in China, accompanied by growth in India and by continued strong demand in the USA.

Coal is normally one of the most economic ways to generate electricity. But, with a cost of CO2 – either direct or indirect – at $60/ton, coal would be more expensive than the natural gas, nuclear and wind power.

There is enough federal spend on research and technology development for cleaner-burning coal (called integrated gasification combined cycle, or IGCC), that can be equipped to capture and sequester carbon.

IGCC, mentioned above, is the least polluting coal burning technology being developed today  The advantages of IGCC over pulverized coal technology are that it is more efficient (using less coal to produce each kilowatthour of electricity), uses much less water, and emits much less SO₂, particulates, and mercury. Most important, carbon capture can be integrated into an IGCC plant much more easily and cheaply than into a pulverized coal plant. Jana Milford, a senior scientist with the U.S. NGO Environmental Defense, says that IGCC combined with sequestration can cut CO₂ emissions by 90 percent compared with conventional plants.

 The power plants in the U.S. generated 1,764,486 thousand Megawatt-hours (MWh) of electricity from coal in 2009.

Demand for coal will peak by 2025 and begin a gradual decline, in part because of emerging policies that will seek to curb emissions by imposing a cost on higher carbon fuels. Use of renewable energies and nuclear power will grow significantly. By 2040, less than 30% of the world’s electricity will be generated from Coal, down from about 40% today.

It is very clear that coal will resurge as an essential contributor to the world’s primary energy supply for a decade to come. Unless there are discoveries of oil or gas thate enhances R/P ratio by double digits, or radical technology improvement in the use of renewable energy sources, it seems that the Stock-driven choice in the twenty-first century could continue to be coal and nuclear power. Consumption of coal will expand, although more slowly than that of other fuels.  But, the coal usage will decline after 2025, since many of the renewable energy sources and Nuclear energy will also become sustainable.