Linmine Energy Audit

7/29/2019 Linmine Energy Audit

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AUDIT OF THE BAUXITE AND POWER PLANTS - LINMINE,

MACKENZIE, GUYANA

Following an audit conducted in the abovementioned plants; these guidelines are issued in the interest ofenergy conservation. Findings and recommendations were discussed with the energy conservation team onFebruary 20, 1996.

1. FURNACE/KILNSCheck that:

1.1 The fuel: air ratio in fuel-fired furnaces is the minimum permissible consistent

with complete combustion;

1.2 Brickwork, flues and dampers are free from leaks;

1.3 Furnace draughting is properly balanced;

1.4 Fuel supplied to the furnace is in proper condition eg. temperature, pressure,atomisation, burner setting, moisture;

1.5 Multiple burners and multiple zone heating are properly balanced;

1.6 Fans, pumps and compressors are not badly worn or leaking;

1.7 Furnace heating cycle is as short as possible;

1.8 Production is planned to give to give the maximum possible evenness ofoperation;

1.9 Unwanted furnaces are switched off.

Calcination kiln

2. STEAM MAINSCheck that:

2.1 Heat exchangers surfaces are examined, repaired and kept clean;

2.2 Steam mains do not leak;

2.3 Steam traps are effective;


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6. RENEWAL AND IMPROVEMENTS6.1 Review insulation standards and consider improvements;

6.2 Review control systems, consider closer thermostatic control;

6.3 Use spray taps and low throughput showers;

6.4 Ensure that power factor of electrical installation is brought to optimum value;6.5 Consider maximum demand control system;

6.6 Match electrical motors' power as precisely as possible to duty;

6.7 Examine the possibility of waste heat recovery/utilisation on kilns and

compressors.

7. ENERGY AUDIT7.1 Monitor fuel, electricity and services consumption at regular intervals and ensure

periodic accuracy checks on all metering equipment;

7.2 Make regular checks on purchases, stock and quality of fuels;

7.3 Aids to any energy-saving campaign are; log books, temperature recorders, kWhand maximum demand meters etc..

8. GENERAL NOTES8.1 High sulphur content of fuels (>3.5%) can restrict usage where the gaseousatmosphere is important and can give rise to cold-end acid corrosion problems.

8.2 Methods of dealing with waste heat can be classified into the following

categories:

8.2.1 Direct utilisation - e.g.for drying, where no external heat exchanger is

employed;

8.2.2 Recuperation - where waste gases and air for preheating are separated bya metallic or refractory heat-exchange surface;

8.2.3 Regeneration - where heat from waste gases is given up and stored by a

heat exchange medium, refractory or metallic, and subsequently returned

and used for preheating air;

8.5.4 Waste heat boiler process steam or hot water can be recuperated;8.2.5 Reduction of waste heat emitted - this is prevention rather than cure.

8.3 Power Factor - This is the percentage of current in an AC circuit which can beused as energy, and is the ratio of true power, in watts, to apparent power in VA.

Apparent power is obtained by multiplying the volts by the current flowing inThe circuit or by the vector sum of the active and reactive components.

Since the reactive current is a quarter of a cycle behind the voltage, the power factor

is normally defined as "lagging" power factor.

THE REACTIVE POWER USES PART OF THE DISTRIBUTION NETWORK

ALTHOUGH IT DOES NO USEFUL WORK.


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Diagram showing the benefits of power factor correction

An approximate value of the overall power factor of any plant may be obtainedby a simple calculation from the electricity maximum demand meters, the

reading of the kilowatt maximum demand meter should be divided by the

reading of the kVA maximum demand meter.The power factor of an induction motor falls as the mechanical load on the

motor decreases, therefore the aim should be to keep all motors fully loaded. The usual

method of correcting a low power factor is to use capacitors. Apart from

reducing the electricity bill, power factor correction may have other advantages.

If cables and main switchgear are operating at the limit of their current capacity,

reduction of the reactive current will permit an increase in the available power

for newly installed equipment without the need for enlarged switchgear and

cables.8.4 Neglect of machinery lubrication, machine misalignment and spillage build-up

also waste power.

8.5 Some of the ways of reducing maximum demand are to ensure that:

8.5.1 No two units of heavy machinery that are used only during short periodsof the working day are ever used at the same time;

8.5.2 Heavy machinery which takes a high starting load and is used

intermittently is never started twice within one half-hour recording

period of the maximum demand meter;8.5.3 Wherever possible, clutches and fluid couplings should be fitted on heavy

machinery so that motors are started on no-load;

8.5.4 Remember that star/delta starters will only take approximately twice the normal runningcurrent whereas direct on-line starters will take 5-6 times normal running current;

8.5.5 A starting schedule for heavy machinery is prepared and adhered to8.5.6 Ensure that the whole of the plant's starting load does not occur within

the same half hour period of the maximum demand meter;

8.5.7 Maximum advantage is taken of night usage.


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Operating plant

RAMOUTAR SEECHARRAN BSc(Hons), MSc(Eng), ACSM, DIC, FIMM, CEngENVIRONMENTAL CONSULTANT

Linmine Energy Audit

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