HITACHI AMERICA, LTD. Air Technology Group … Paper: Compressed Air Cost Savings for Small Food Processing The following shows an example of this

White Paper: Compressed Air Cost Savings for Small Food Processing

www.hitachi-america.us/airtech

HITACHI AMERICA, LTD.Air Technology Group

5808-Q Long Creek Park Drive, Charlotte, NC 28269 Tel: 704.494.3008 x28 www.hitachi-america.us/airtech; [email protected]

Hitachi Industrial Equipment Systems Co., Ltd.

White Paper: Compressed Air Cost Saving for Small Food Processing

With recent trends and consumer concerns for food safety, many food processors are considering and adopting the use of oil-‐free compressed air for their food manufacturing process.

One of the major concerns is the capital investment of oil free air compressors, as typically oil free compressors are significantly more expensive than lubricated units (sometimes called Oil-‐Bath, Oil-‐Flooded or Oil-‐Injected). A possible alternative for those who want to avoid the high initial investment of an oil free compressor may be a lubricated compressor with food grade lubricant.

As consumers become more and more sensitive for food safety, food grade lubricant may not be in their best interest if the air comes into contact with the product or packaging materials during the manufacturing process. Oil free compressors can and do eliminate the issue and provide the best air quality (Class 0 Certification, ISO8573.1).

An Oil-‐Free Compressor when properly applied can provide financial savings. Here are a few concepts to be aware of during the design of an air compressor system. Knowledge of the actual “point of use” pressure requirement by the manufacturing equipment is essential. Typically, pneumatic equipment requires 40 to 70 psig to operate. In order to fulfill plant wide needs of air, many companies tend to choose air compressors with a design pressure of 125psi. This higher design pressure is to accommodate for air pressure drops and still be able to achieve 90 to 100psig. Many applications such as air blowing, air knifes, cylinder movement, etc. may not necessarily require a high pressure supply. All plant equipment should be researched to determine the correct amount of pressure required.

Applying a 100psi air compressor instead of a 125psi air compressor can save up to 10% of the operation cost. (Below graph 1)

Graph1. The theoretical power to adiabatic air compression






A 10% savings of the daily operating cost is a huge financial benefit. The energy consumption of the use of a 30HP compressor with a 6,000 hour operating schedule a year is $17,000 a year. The annual savings will be $1,700 just by lowering the air pressure at the source.

Another valuable point is that the typical plant air leak load is around 10~20%. Lowering the plant air pressure from 125psi to 100psi provides a benefit in the reduction of air consumption; leakage will be reduced by up to 18%. (Below graph 2) In addition to the reduced daily energy consumption; an overall reduction in the size of the air compressor required may be obtained.

Graph2. Air leakage from hole *1 Air Temperature is 68F *2 Depends on the inner surface friction of the bore

Many other methods, such as proper maintenance, larger air storage, pressure regulators, etc. will also provide opportunities to save energy.

Industry Movement and Application

Countries such as Japan and their major automotive manufacturers that consume significant energy have started applying techniques to lower their entire plant air pressure. One technique is by using small booster compressors for the equipment that requires higher pressure.



The following shows an example of this type of application.

Typical example of compressed air installation as described below. (Air Treatment excluded)

One example of the more energy efficient models is as follows:

*Booster means Booster compressor or Booster valve

Air Compressor (125psi)

Air Receive

r

(Pressure reducing valve)


70psi

100psi


Air Receive

r

Booster Equipment


70psi

More than 100psi






A second option would be separate systems:

Line1

Line2

In either of these examples, operation can be optimized and significantly save energy cost.

Many smaller food processors continue to have a tight initial investment budget. One way to overcome such financial challenges is to use single stage oil free compressors. A typical oil free compressor uses two stages of compression within the design (2 air-‐ends/compression modules). Advances in technology have enabled the design and manufacturing of single stage designs, with a typical maximum pressure of 100psi. Naturally single air-‐end compressors have lower initial cost and also less maintenance cost due to the reduction of components (Below Graph 3). A further reduction in energy cost may be achieved if a variable speed drive compressor is utilized (Below Graph 4).

Fig. 1 The difference between 1-‐stage and 2-‐stage by simplified model

70psi


Air Receive

r

100psi


Air Receive

r






Graph3. Total Cost Comparison* Graph4. Total Cost Comparison* (2-‐stage vs1-‐stage) (2-‐stage Fixed Speed vs 1-‐stage VSD) *The vertical axis means the value of the model to be compared if the total cost of 2-‐stage compressor is 100%. *6,000hr operation a year *Approximately 70% load operation of 2-‐stage compressor *Electricity: $.10 per kWh

Consumers are becoming more and more sensitive related to food safety and health. Integration of oil free air compressors to food processing is a growing trend to address certain aspects of food safety. With proper design and application, the usage of oil-‐free compressed air is not limited to the larger organizations offering “peace of mind” to even the smallest food processor.

By: Larry M Cooke

Contributing Writer: Shawn Okita

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HITACHI AMERICA, LTD. Air Technology Group … Paper: Compressed Air Cost Savings for Small Food Processing The following shows an example of this