Energetica India Magazine October-November 2021

ENERGY EFFICIENCY 57 energetica INDIA- Oct-Nov_2021 week in wasted energy. It is estimated that up to 20% of total compressed air consumption may be lost through leaks. If you are still working on site and have some spare time, we recommend tak- ing the opportunity to detect the leaks in your system. For example, you could run your air compressor with no production to check for leaks. Fixing air leaks will start to save you money immediately. 3. Reduce the pressure band As a rule of thumb for most compressors, a reduction of 1 bar in pressure (14.5 psi) will lead to a 7% saving in electricity consumption. The pressure settings of the compressor should be adjusted un- til the lowest pressure can be reached and the pressure band reduced without affecting the application. For centralised systems utilising multiple compressors, by using a central control- ler, the network can be set to run within a narrow pressure band which ensures that the compressed air network match- es your precise needs. The controller can also allow you to manually or auto- matically create two different pressure bands to optimise energy use within dif- ferent periods, drastically reducing ener- gy costs at low-use times. Also, lowering the system pressure re- duces the impact of leaks. A 1 bar pres- sure reduction decreases the impact of air leaks by 13%. 4. Turn compression heat into useful energy with heat recovery One area that offers manufacturers a significant opportunity for savings is to recover the waste heat from air compres- sors. Without energy recovery, this heat is lost into the atmosphere via the cool- ing system and radiation. The amount of electrical energy that can be recovered depends on the size of the compressor and the running hours. Typical recover- ies are between 70-94%*. Recovering heat from compressed air reduces the need for purchasing ener- gy, for example to heat hot water. It is this reduction that results in lower op- erating costs and CO2 emissions, also reducing your carbon footprint. *Approximately 70% of energy is recov- erable from oil-injected screw compres- sors, and up to 94% from oil-free wa- ter-cooled screw compressors. 5. Ensure the correct type of com- pressor is installed Most production processes require dif- ferent levels of demand in different pe- riods, which may mean that the com- pressor is running off-load or idle (not producing any compressed air) for long periods of time. Great savings can be made if a fixed speed compressor can be replaced by a variable speed drive unit as it only produces compressed air as and when required. This also minimis- es offload running of the compressor, which is known to waste energy. *A VSD compressor saves an average 35% energy and a VSD+ unit can save as much as 50% compared to a fixed speed unit, even at full load. As a fixed speed compressor has a fixed amount of motor starts an hour, the com- pressor runs offload for a set time which limits the number of motors starts to en- sure overheating of the motor does not occur. As a VSD unit ramps up and down in a controlled fashion, the maximum number of starts and stops per hour may be increased, and it also avoids peaks in current when starting. 6. Don’t forget the impact of regular maintenance The best way of taking care of your compressed air availability is by taking the best care of your compressed air equipment. This means investing in reg- ular preventative maintenance, which will sustain the efficiency that you have gained by purchasing a new compres- sor or improve the performance of an older unit. Whether you prefer to purchase spare parts only and perform maintenance in-house, sign up to a planned mainte- nance program at pre-determined inter- vals from the manufacturer or approved distributor, or choose a total responsibili- ty package that covers breakdowns and leaves no room for surprises, the main thing to remember is that reduced com- pressor performance is not inevitable as the machine gets older. Regular ser- vicing will improve your equipment up- time and energy efficiency: the opposite could lead to more downtime, increased energy consumption and potentially a breakdown.