Preparation For Detailed Energy Audit

Plan for analysis of a compressed air system

Check energy balance

SUPPLY

DISTRIBUTION

DEMAND

SUPPLY = DEMAND + LOSSES

SUPPLY = DEMAND + LOSSES

Establish real demand

> pressure [barg]

> air quality neded [oil, water, particles, dryness]

> demand profile at the point of use

> is it legitimate use of compressed air

Detection and minimization of losses 1. No-load test

• to detect amount of air leakage in the system:

efficiency [n] improvement:

• establish real demand

• minimize losses

• optimize supply

Optimize compressed air supply

Leaks =

V - volume of the air mains (<25 mm) and receivers P1 - pump-up pressure P2 -drop pressure T -time for the pressure drop

2. Distribution main sizing

• maximum pressure drop at the point of use Dp = 0.2 bar

• pipe diameter enough to limit air velocity to 6 m/s

3. Drainage

• drain points every 25-30 meters

• manual drains should be replaced by condensate tapes

1. Air inlet temperature

• for every 4 °C temperature increase, 1 % increase in energy consumption

2. Air inlet pressure drop

• for every 25 mbar depression, 2 % increase in energy consumption

• check inlet air filters

3. Off-loading

• electricity consumption in off-load mode: 2040 % of on-load

• check for the viability of automatic sequencing

4. Dryers

• in most dryers permissible pressure drop Dp = 0.1-0.4 bar

5. Air treatment

• avoid excessive filtration, and supply only required air quality!

• check filters for fouling

6. Receivers

• act as pulsation dampers; recommended capacity 5 % of hourly air consumption

7. Control system

• avoid freqent off-loading

• avoid prolonged partial loading

• avoid too large pressure variations - pressure control

8. Metering

• kWh meter on compressors rated 50 kW and above

• air flow metering - an area using 30 nm3/min warrants the instalation of permanent meter

• weekly monitoring program should be introduced

4.4.5 Data Collection on Environmental Impacts

The scope of environmental data collection is determined by the purpose or scope of the environmental audit itself, as elaborated earlier in this chapter. However, the key environmental data are common to most requirements and these are summarized in Toolbox III-1. The logical first step is to identify the relevant environmental regulations that a company is required to comply with. This should be complemented by a review of any complaints from the neighboring communities and of warnings or fines issued by relevant authorities.

The second step is to determine all the physical source points of environmental impacts (Fig. 4.5). For air emissions, these will be stacks and ventilation exhaust ducts. For waste water discharge, these are the points where waste water is released into the sewage, canals or waterways outside the factory perimeter. For solid waste, these are waste collection areas around the site and for soil and underground

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