Energy conservation depends more on the compressed air system

Energy conservation depends more on the compressed air system

Kuntan Panchal, Joint Managing Director of Indo Air Compressors.

Indo Air Compressors manufactures reciprocating air and water cooled compressors. It has a very modern factory, spanning across an area of 6300 sq m. The company has been continually adopting best engineering practices to lift the product quality to new heights. Young and dynamic Kuntan Panchal, Joint Managing Director of Indo Air Compressors, has pushed the turnover growth of Indo Air by 25 per cent in just three years of his association with the firm. He has also been instrumental in orienting the company to develop advanced compressors to meet the market demands. The company has harnessed its state- of- the- art R&D facility to develop highly energy efficient systems. Here he talks about what to look for in compressors and how to get the best out of them. Excerpts from the interview.

Tell us about the range of compressors offered by your company.
We manufacture both piston type reciprocating compressors and rotary screw compressors. The piston type reciprocating compressors includes single-stage for low pressure application, two-stage models for medium pressure application and the high pressure models of multi stage models. The connected load of the compressors range from 1 HP to 30 HP. The state-of-the-art rotary screw compressor manufactured by us emits very little noise, making it ideally suitable for installation within the factory area. Our screw compressors range from 7.5 HP to 100 HP now and plans are afoot to manufacture up to 300 HP systems.

Reciprocating type compressors in the oil-free version from 0.5 HP to 15 HP are also available for the industry where completely oil-free air is required. This has special application in hospitals.

Other products from Indo Air include vacuum pumps from 2 HP to 10 HP and heavy-duty water cooled vertical compressor from 25 to 60 HP.

The latest addition to our range is the high pressure water- cooled, oil-free IAH series compressor, from 40 HP to 150 HP models.

Which are your latest breakthrough products?
To ensure the product quality in the production of PET bottles, containers for home care/cosmetic products, food products, pharmaceutical products, aeronautics, turbine and hydraulic circuit pressurising and pharmaceutical industries, Indo Air has developed its new IAH hundred per cent oil-free high pressure series compressors.

Catering to the need of hospital for clean oil-free air systems has been a focus of Indo Air for many years. Indo Air's NL type compressors were well received in the market. Indo Air Vacuum pumps have satisfied the demands of hospitals to the fullest.

How can one rationalise the use of compressed air and improve the efficiency of compressor?
There are various steps that could be taken to improve the efficiency of compressors and can help in using compressed air effectively.

  • Use of high efficient and higher pull-out torque electrical motors has been found to give power savings in different plants; power savings of around 5 to 8 per cent was recorded at many plants.
  • Variable Speed Drives (VSD) for the compressors improves the power consumption pattern of the compressors. Of course, this depends on the usage and air output linked to the air pressure requirements. The savings VSDs provide vary between 10 to 40 per cent depending on the flow pattern.
  • Proper sizing of the pipe diameter contributes significantly to lower the power consumption; increasing the pipe diameter typically reduces annual energy consumption by 3-4 per cent.
  • When the compressor works, it produces heat and it is simple physics that compressing air gives off heat. The heat energy gets stored in the decreasing volume of air. To maintain proper operating temperatures, the compressor must transfer excess heat to a cooling media before the air goes out into the pipe system. As much as 90 per cent of that heat can be recovered for use in your operation. If you can supplement or replace the electricity, gas or oil needed to create hot water for washrooms or direct warm air into a workspace, warehouse or for any other use, the savings can add up significantly. The possibilities to recover this waste heat via hot air or hot water are very good. The return on the investment for energy recovery is usually as short as one to three years. In addition, energy recovered by means of a closed loop cooling system (for water cooled compressors) is advantageous to the compressor's operating conditions, reliability and service life.
  • If the input temperature to the compressor is reduced by placing the compressor inlet strategically, the energy consumption of the compressor can be reduced to the extent of 1-2 per cent for every 3-4 degree drop in inlet temperature.
  • Often, the air-cooled compressors are relegated to boiler rooms that do not have proper ventilation. These centralised compressors can experience elevated operating temperatures that reduce equipment life, increase maintenance and repair cost, and ultimately can yield an unreliable air system. The initial cost of a good ventilation system is usually far less than the ongoing increased maintenance costs of a hot operating environment.
  • System operators should also examine if a reduced system pressure could be used. Use of a central control system can run the existing air compressors to cyclical demand more effectively.
  • Increased storage capacity can also reduce the unnecessary high cycling demand of compressors.

Which features in your equipment help in the energy conservation?
With regard to the rationalisation of the use of compressed air, energy conservation depends more on the compressed air system than the elements built into the compressor. However, there are a few which are already available or can be built into Indo Air compressors.

Indo Air has been incorporating innovative ideas in the design of its reciprocating compressors. One such instance is to change the cylinder diameter combination, resulting in reduced speed of the compressor leading to drop in temperature built up. The Automatic Start-Stop control can be modified to have a solenoid valve system to have a pressure free start up of the compressor thus reducing the starting current demand of the electric motor. The water-cooled, inter-cooler can be provided as an option to reduce the input temperature of air at the subsequent stages. Variable speed drives is offered with the screw compressors to reduce energy consumption.

What kind of testing and quality checks does your equipment go through?
All internal assemblies are carried out in a dust-free closed assembly room to protect the internal moving parts. This room is adequately furbished to have the necessary tools, test benches, air lines and inspection facilities. The quality plan for the assembly is displayed at every stage of the compressor assembly to ensure a repetitive set performance of the compressors. All critical parts are inspected one hundred per cent for dimensional as well as geometrical accuracy. All castings and raw material purchases are accompanied by chemical and physical property reports. All compressors leaving the premises of Indo Air are tested for its performance, efficiency and the quality. Every model of the compressor is tested once in two months on a test bed established specially for this purpose, with calibrated instruments and measurement devices, where the nozzle is tested at various parameters as specified in the relevant Indian Standard and sometimes, rechecks are carried out.

There is a monitoring system in place on the compressor at the customer's place and the feedback is used to update the check list in the assembly. For every deviation noticed, a Quality Assurance Report (QAR) is prepared with the action taken to eliminate the error. We are a certified ISO 9000-2008 company and all quality practices are followed from design, procurement, inspection, assembly and testing, and proper records are maintained.

What are the new developments in compressor operations, design and maintenance processes?
With the advent of microprocessor systems, modern air compressors are now available with user friendly software systems to operate, control and maintain the equipment. All Indo Air screw compressors and high pressure, water-cooled reciprocating compressors come with a Indo-numeric PLC based control system software to control the compressor. Its user-friendly touchscreen MMI allows the operator to modify the parameters.

The system monitors, regulates, does error diagnosis and gives out warning signals, both visual and audible, preventing potential damages to the equipment. It also gives service warning signals to indicate oil filter/air filter change and such other service requirements.

The provision of an auto shutdown ensures shutting down of the compressors in case of abnormal parameters, to avert system damage. In the high pressure, water-cooled compressor control, there is a port available in the controller for a computer connection. Using this facility, remote sensing of the compressor can be performed via the internet for troubleshooting, from the Indo Air factory.

Double-acting cylinders have been incorporated into the new design, instead of single acting cylinders; this gives two compressor strokes for every revolution of the crank, thus doubling the output. Now booster compressors are developed where high output and high pressure of air is required. These designs use the advantage of both reciprocating and rotary screw compressors, compressors with a smaller footprint.

How have you incorporated safety into your design?
The air compressor is fitted with several safety components.

The first is an unloading valve. The unloading valve allows the air to escape from the compression chamber when there is a strain on the electrical motor.

The pressure inside the air receiver must never exceed the manufacturer's recommendations. If the pressure is greater than the recommended level, it may cause an explosion. The pressure in the air receiver is controlled by the pressure switch. To adjust the pressure, simply turn the switch in the desired direction.

Pressure relief valves are also installed on the compressor system. These valves allow air to escape from the system when the pressure goes beyond the desired level. The valves operate automatically.

The air intake valve is fitted with an air filter. The filter prevents dust from being drawn into the compression cylinder. If dust enters the compressor, the heat inside the cylinder can cause the dust to catch fire. Fire inside the cylinder may cause damage to the air compressor. For this reason, it is important to make sure that the air filter is clean and securely connected to the compressor.

Moisture too, can cause problems and so another filter must be installed to take out the moisture out of the compressed air. The moisture is usually removed using a filter and moisture separator assembly which is installed between the air compressor and the air receiver. It removes the moisture and dust from the compressed air before it enters the air receiver.

An automatic control device is attached to the air receiver. It controls the starting and stopping of the air compressor. It shuts down the compressor when the air pressure in the air receiver is adequate. It restarts the air compressor when there is a need for more pressure.

A cooling system is installed in each air compression unit. The compression chamber and the compressed air must be cooled. Small compressors are usually air-cooled. The air is circulated around the compressor by a fan. Large air compressors are usually water-cooled. Cold water is pumped throughout the compressor. Both the air and water cooling systems prevent the compressors from overheating and causing serious damage. The air compressor is also fitted with a low oil level indicator switch. This indicator switch automatically shuts down the air compressor if the oil level is low. The compressor should not be operated if the oil is low as this can cause serious damage to the compressor. Do not attempt to run the air compressor until the oil is replaced.

These measures are a must for the safety of the equipment and also for the people working in the factory. We at Indo Air take additional precautions with all compressor parts under air pressure. All the air receivers, inter-coolers and after -coolers, pressure pipes, are tested hydraulically at 2.5 times the designed pressure.

Selecting The Right Compressor

An air compressor is a valuable piece of equipment for operating power equipment or tools. The type you need depends on the equipments you will be using.

  • Consider how often you will use an air compressor and how it will be used. What tools will you be using and how much power will be needed to operate them? Some tools like nail guns use low volume of compressed air whereas other equipment, such as drills or sanders needs high volumes because they require a steady air flow.
  • Consider the power of the compressor; consider both the horsepower and pound per square inch (PSI) pressure. Make sure it is more powerful than the most powerful equipment you will be using.
  • The type of the compressor depends on the volume of air required and the air pressure. Normally in a cement plant, the compressor is located in a room far away from the equipment to be operated. There will be a significant pressure drop and this should be taken in to account while selecting the compressor.
  • With the availability of screw compressors with high volume outputs, with a closed canopy, it is possible to install these types of compressors in the shop floor itself, close to the equipment, resulting in minimum pressure loss.
  • The tank size is another important factor. The more you use the equipment, the larger the tank you will need. Always go a little larger than you think you will need, this will ensure that you can get the optimum use from the compressor and reduced power consumption.
  • List out the accessories you may need with the compressor and include them in the buying order.

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