Energy Conservation Principles

Energy is a critical component of processing industries. There is a total dependence on fossil fuels for this energy supply. It is also a know fact that our fossil fuel reserves are finite and we should utilize these resources judiciously. Efforts are also being made in several sectors to tap and develop new energy sources as an alternative to the fossil fuels. But until the alternative sources are put to commercial use we have to rely on the available means. Due to increased prices of fossil fuels,the cost of energy sources has increased tremendously. This has forced the industries to take the possible energy conservation measures. The concept of energy conservation is based on following general principles:

i) Save Energy: Economize the use of commercial energy. The amount of energy saved in a process can be equated as equivalent amount of energy generated.The wasteful expenditure of energy should be avoided. Minimize the losses of energy during its use.

ii) Enhance Equipment Efficiency: The energy utilization efficiency of equipments should be enhanced by incorporating regenerator, economizer, pre-heater, etc. and also by improvements in processing technologies.

iii) Heat Recovery from Discharge Streams: Hot condensate and exhaust air which are discharged in to atmosphere contain considerable amount of heat energy. Appropriate means and devices should be adopted recover this.

iv) Alternate Energy sources: Wherever possible, encourage the use of renewable energy sources, such as, solar energy, wind energy, bio gas etc. to ease the load on costly fossil fuel energy.

Dairy processing involves essentially the heating and cooling of milk and milk products. The related equipments are required to perform these operations efficiently and in doing so, the operation consumes a large amount of energy. Savings in this energy expenditure is possible if we apply the conservation measures. Energy conservation should receive attention of both the equipment manufacturer and the entrepreneurs of the processing plants, especially in view of the declining energy supply and rising energy cost.

For the milk processing plants the energy use profile is dependent on the product mix. The two major energy inputs during processing are the electricity and industrial oil fuel. There is a significant potential for energy conservation in the above two inputs with the improved engineering services and processing technologies in a dairy plant. The analysis in this section identifies areas for improvements in energy resource utilization. Following text describes some of the guidelines for conservation of energy in a dairy plant.

i) Look into the possibility to reduce peak load demand of steam and refrigeration by spreading the actual requirement over the day. This would not save energy but would redistribute the energy requirement from an expensive peak demand period to a period with low loading.

ii) Rationalize the use of cold storage rooms and shutting down rooms not required. Ensure the minimum ingress of heat into cool rooms through open doors and poor insulation. Cooled produce should be immediately moved to cold storage and the doors of the cold room be kept closed at all possible times.

iii) Production processes which involve pre-cooling with unreferigerated water should be controlled in such a way that operators will not short circuit the use of water and switch to refrigeration to meet a too rigid time schedule.

iv) The thermal efficiency of steam boilers operating in a dairy industry varies between 55 to 80%. It is not unusual for boilers to have an exhaust gas temperature of 220 to 250° C. It is worthwhile to consider the installation of feed water pre-heater or an air pre-heater which utilizes the heat in the exhaust gases down to 159 – 160 °C.

v) Insulate storage tanks, cold-water tank, chilled water pipes and steam pipe lines. Avoid water leaks through unattended losses and pipe connections.

vi) Regenerative application of heat exchangers is an effective means of conserving energy.

vii) Vapour recompression in multi-effect evaporators reduces the steam consumption and energy input. Use thermo-compression or mechanical vapour recompression in conjunction with multiple evaporators.

viii) Multistage spray drying plants equipped with heat and mass recovery system are successful in saving energy in spray drying of milk.

ix) Dairy industry mainly has small and medium sized motors with a low power factor or a high consumption of reactive power. Fitting a power factor correction system and ensuring that electric motor operate at high loads can reduce electric cost.

x) Replacing the traditional double wash procedure by a single wash procedure can reduce the energy cost in CIP-cleaning.

xi) Greater use of microprocessor based automatic controls improves the energy efficiency in food processing.

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