One of the largest energy-consuming parts of any factory is compressed air, also known as the 'fourth utility.' The air compressors used to generate this form of energy use many kilowatt hours annually to produce the required amount of air to power machines throughout the plant. By reducing consumption at each process, companies can likewise reduce the energy required by the compressor, ultimately decreasing operating costs by a substantial amount.
As facilities engineers seek additional ways to lower energy consumption and costs, commonly used compressed air systems and tools are often missed source of saving. Nearly 50% of industrial plant usage of compressed air is consumed in 'blow-off' applications such as removing swarf and other debris, drying parts, removing products from the conveyor, etc. This supply of air is 'uncontrolled,' i.e. provided continually via nozzles throughout the day, and is often extremely costly.
Given that air compressors often exceed other equipment in energy usage, this seems like a perfect starting point for slashing an energy bill. In fact, the U.S. Department of Energy has found that more than 95% of compressed air systems used in industry are viable sources of energy reduction. And more than 30% of total air usage in plants is attributable to this costly method of continual compressed air supply. That's not even accounting for air leaks. In this area, energy cost savings by way of reduced electricity consumption vary from 20 to 50% or more. For a large plant with high compressed air usage, these savings can amount to six-figure savings annually.
Because of the expensive energy costs accrued by continuous flow compressed air systems, manufacturers are increasingly utilizing more energy-efficient systems and devices. But how are these savings achieved?
The Answer: Pulsed Air
Providing a cost-saving alternative to continually blowing compressed air, pulsed air blow systems give facilities engineers a simple, actionable way to reduce their facility's compressed air usage and energy costs. Consequently, pulsing the air is an effective way to reduce carbon dioxide emissions. While the cost to produce and sustain the air required to run many different in-plant machines can be costly, pulsing the air instead can reduce air consumption up to 50% in certain applications.
A leading Chinese soft-drink manufacturer currently uses Parker Hannifin's pulsed air blow valves for many different pneumatic applications including removing particulates in their PET (polyethylene terephthalate) bottle plants prior to and following their blow molding process. Blasts of pulsed ionized air agitate process waste particles resulting in highly-efficient removal and reduced cycle time.
Pulsed air blasts also give a secondary blow to bottles on the conveyor as an escape blow following line stoppage and prior to label attachment. Consequently, this particular soft-drink manufacturer reported a near-50% reduction in air consumption and associated energy use costs.
|Parker Hannifin Air Saver Pulsed Air Product: Designed for use in new and older-model air nozzles and air guns, the Air Saver pneumatic valve is ideal for achieving energy cost savings in pneumatic applications which allow uncontrolled blow-offs.|
Requiring no programming changes to the existing PLC, the pulsed air valve was easily retrofitted into the manufacturer's production line. Now it serves as a cost-effective replacement for the previous continuous air flow system, reducing the plant's air consumption and increased effectiveness at no subsequent cost.
Plant managers and system designers can use this formula to determine the current cost of compressed air usage in a plant:
bhp = Motor full-load horsepower (frequently higher than the motor nameplate horsepower; check equipment specification)
0.746 = conversion between hp and kW
Percent time = percentage of time running at this operating level
Percent full-load bhp = bhp as percentage of full-load bhp at this operating level
Motor efficiency = motor efficiency at this operating level
Commonly, compressed air systems have low efficiencies ranging from 10-15%, making them ideal targets for energy savings and system improvements.
Pulsed-Air Blow Reduces Energy Costs
Without the need for external control, pulsed air blowing is delivered directly to the local work tool, occurring as a rapid set of ON and OFF pulses. This method ensures lower compressed air consumption, translating to less energy consumption and cost savings. Additionally, workers don't need to recharge air tanks as often, freeing them up for other tasks.
This presents a major advance in pneumatic technology and efficiency as well as substantial energy savings for users. By producing these sets of air pulses instead of a continual flow, pulsed air valves are ideal to realize energy savings.
A U.S. Department of Energy survey found that for a typical industrial facility, compressed air generation accounts for approximately 10% of all electricity consumed. According to the US Office of Industrial Technologies, "Very often the cost of generation is not known; however, some companies use a value of 15-30 cents per 1000 ft³ of air." The Office also cites that compressed air generation may account for 30% or more of the electricity consumed in some facilities, making it one of the most expensive sources of electricity in a plant. By contrast, pulsed air valves reduce compressed air generation costs by as much as 50% compared against continual air flow systems and applications.
- Air blow-off assembly of precision electronic parts
- Cleaning parts, removal of swarf and cooling liquids
- Production of machined parts
- Blow-off of liquid cleaner from cast parts
- Dust removal
- Crumb removal
- Cleaning machining tools
- Air blow for bolt holes
- Air blow for automotive painting processes
- Air blow on part feeders
- Arc-weld cooling
Pulsed Air Improves Efficiency and Delivers Quick ROI
Not only will pulsing compressed air help to reduce the cost of manufacturing operations via energy reduction, it is also more effective. Pulsed air generates more agitation than a continual air stream, which means a more effective blow is created to rapidly strike the work, improving the effectiveness of drying processes and those which remove swarf and debris, i.e. from resin-molded parts before surface coating or finishing.
The Air Saver valve can quickly and easily be retrofitted into any existing system, as it does not require any other external control. The efficient design of a pulsed air valve allows it to be installed at the point of application for a variety of different uses, such as on a pneumatic drilling machine, etc. Meanwhile the air compressor itself remains in its usual location, i.e. in a corner of the plant.
Pulsed air valves are also easy to install in existing pneumatic systems for a quick ROI. Facilities engineers working with systems using solenoid valves to control air blow can easily replace them with pulsed air blow valves. There's no need to interrupt production schedules or to program a PLC controlling air blow at the point of work.
They also deliver a quick return on investment (ROI) and are also suitable to reach environmental and sustainability goals including greenhouse gas reduction.
Pulsed air switch valves feature a wide range of flow capacities, for example flows (at 5 bar) ranging from 150 to 15,000 liters/min. Additional valve features include an ON/OFF time adjustment needle, adjustable pulse frequency and duty cycle, and models for specific applications.
Pulsed air blow valves are equally fit for additional uses across many industries:
- Electronics Manufacture: Pre-assembly cleaning of components and product surfaces
- Swarf Blowing: Swarf (aka turnings, filings, or shavings) is composed of minute pieces of plastic, metal, cardboard, etc. waste from machining and other subtractive manufacturing processes. A pulsed air blow system blows swarf from operating machinery into recycling or other containers.
- Print Surface Drying: Pulsed air blow is more efficient to dry surfaces used for printing prior to the actual printing process.
- Convection Cooling: Pulsed air blow systems are also a low-cost option for forced convection cooling applications.
Several different configurations are offered to adapt to current pneumatic applications. Facilities engineers working with manual valves (i.e. ball valves) can quickly install a pulsed air valve model since they do not require electrical power.
Facilities engineers using an electrically-operated solenoid valve to control air blow, can easily retrofit a pulsed air valve to immediately reduce compressed air consumption, again without having to program any changes into the PLC.
Alex Bakos is the product sales manager – controls for Parker Hannifin's Pneumatic Division. He earned his bachelor's degree in engineering management and his MBA from Western Michigan University.