Electricity + Control

ENERGY + ENVIROFICIENCY:

FOCUS ON VALVES + ACTUATORS

Figure 2: Typical shaft consumption.

Figure 3

shows the typical compressed air system pressure and air

flow supply of the gold plant before implementation of this energy

saving project.

Figure 3: Typical plant consumption.

The plant requires a constant high pressure for the pnumatic in-

strumentation thoughout the day. Constant air flow is also required

ustainable energy supply in South Africa requires ongoing

new and innovative methods to ensure that production ac-

tivities are maintained and that energy is conserved. South

African gold mines are among the largest electricity consumers in

the country [1]. The focus of the study was to reduce the electrical

energy consumption of air compressors supplying compressed air

to large compressed air rings at these mines.

A typical mining compressed air system consists of air com-

pressors, a pipe network and air consumers. These air consumers,

or end users, include rock drills, loading boxes, pneumatic valve

actuators and refuge chambers.

Figure 1

shows the typical layout of

a compressed air ring.

Figure 1: Typical layout of a compressed air ring.

The air consumption, pressure requirement and time of use of the

consumers also differ.

Figure 2

shows the typical pressure and air

flow consumption of a shaft. There are clearly defined periods of

high and low consumption throughout the day. This is a result of the

various combinations of pneumatic equipment in use. For example,

rock drills are mostly used in the drilling shift, requiring high pres-

sure and high air flow.

Splitting a compressed air ring

Energy efficiency opportunities

Rudi Joubert, Johann van Rensburg, Ruaan Pelzer, North West University;

Consultants to HVAC International and TEMM International

The purpose of this study was to implement an energy efficient strategy on a compressed air ring of a South African gold mine.

Compressor house

Gold plant

Control valve

Control

valve

Shaft

Typicalpressure requirement

Typicalflow requirement

Time in hours

Pressure in kPa

600

500

400

300

200

100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Flow in kg/s