Energy Audit Methodology & Thumb Rules for Audit

Ten Steps Methodology for Detailed Audit Step No

PLAN OF ACTION

PURPOSE / RESULTS

Phase I –Pre Audit Phase Step 1

 Resource planning, Establish/organize a  Plan and organise Energy audit team  Walk through Audit  Informal Interview with  Organize Instruments & time frame Energy Manager, Production  Macro Data collection (suitable to type of industry.) / Plant Manager  Familiarization of process/plant activities  First hand observation & Assessment of current level operation and practices

Step 2

 Conduct of brief meeting /  Building up cooperation awareness programme with  Issue questionnaire for each department all divisional heads and  Orientation, awareness creation persons concerned (2-3 hrs.)

Step 3

Step 4

Phase II –Audit Phase  Primary data gathering,  Historic data analysis, Baseline data Process Flow Diagram, & collection Energy Utility Diagram  Prepare process flow charts  All service utilities system diagram (Example: Single line power distribution diagram, water, compressed air & steam distribution.  Design, operating data and schedule of operation  Annual Energy Bill and energy consumption pattern (Refer manual, log sheet, name plate, interview)  Conduct monitoring

survey

and  Measurements : Motor survey, Insulation, and Lighting survey with portable instruments for collection of more and accurate data. Confirm and compare operating data with design data.

Step 5

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Conduct of detailed trials /experiments for selected energy guzzlers

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Trials/Experiments: 24 hours power monitoring (MD, PF, kWh etc.). Load variations trends in pumps, fan compressors etc. Boiler/Efficiency trials for (4 – 8 hours) Furnace Efficiency trials Equipments Performance experiments etc

Step6

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Analysis of energy use

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Energy and Material loss/waste analysis

Step 7

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Identification and development of Energy Conservation (ENCON) opportunities

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Step 8

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Cost benefit analysis

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Reporting & Presentation to the Top Management

&

energy

Identification & Consolidation ENCON measures Conceive, develop, and refine ideas Review the previous ideas suggested by unit personal Review the previous ideas suggested by energy audit if any Use brainstorming and value analysis techniques Contact vendors for new/efficient technology

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Step9

balance

Assess technical feasibility, economic viability and prioritization of ENCON options for implementation Select the most promising projects Prioritise by low, medium, long term measures

Documentation, Report Presentation to the top Management.

Step10

Phase III –Post Audit phase  Implementation and Follow- Assist and Implement ENCON recommendation measures and Monitor the performance up Action plan, Schedule for implementation Follow-up and periodic review

Drawing process flow diagram -Identification of waste streams and obvious energy wastage

Auto Cane Feeding system

Identification of Energy Conservation Opportunities Energy generation  Energy distribution: Energy usage by processes: Fuel substitution:

Technical and Economic feasibility Technology availability, space, skilled manpower, reliability, service,Impact of measure on safety, quality, production or process.Maintenance requirements and spares availability Sample Worksheet for Economic Feasibility

Name of Energy Efficiency Measure

i.

Investment a. Equipments b. Civil works c. Instrumentati on d. Auxiliaries

2. Annual operating costs     

Cost of capital Maintenance Manpower Energy Depreciation

Net Savings /Year (Rs./year) = (Annual savings-annual operating costs)

3. Annual savings    

Thermal Energy Electrical Energy Raw material Waste disposal

Payback period in months = (Investment/net savings/year) x 12

Energy Audit Reporting Format

Energy Audit Reporting Format

LETS QUICKLY SUMMARIZE

THESE TO BECOME THE THUMB RULES FOR YOU IN FUTURE AUDITS

THERMAL ENERGY BOILERS 5% reduction in excess air increases boiler efficiency by 1% (or: 1% reduction of residual oxygen in stack gas increases boiler efficiency by 1%). 22 0C reduction in flue gas temperature increases boiler efficiency by 1%. 60C raise in feed water temperature by economiser / condensate recovery corresponds to a 1% saving in fuel consumption, in boiler. 200C raise in pre-heated combustion air temperature by waste heat recovery results 1% fuel savings.

THERMAL ENERGY A 3 mm diameter hole on a pipe line carrying 7 Kg/cm2 steam would waste 32'650 litres of fuel oil per year. A 3 mm thick soot deposition on the heat transfer surface can cause an increase in fuel consumption to the tune of 2.5%. A 1 mm thick scale (deposit) on the water side could increase fuel consumption by 5 to 8%.

Steam Piping : Features A 100mm well lagged pipe of 30-meter length carrying steam at 7 Kg/cm2 pressure can condense nearly 10 Kg. of water in the pipe in one hour unless it is removed from the pipe through traps. The pipes should run with a fall (slope)of not less than 12.5 mm in 3 meter in the direction of flow. Drain pockets should be provided at every 30 to 50 meters and at any low point in the pipe network.

Leaking Steam Pipe / Valve Audible Leak

Weak whistling Almost invisible steam jet

800 litre oil per year

Visible Leak

Weak hissing Visible steam jet

Bac k 2,000 to 4,000 litre oil per year

Utilising steam at the lowest possible pressure 2730.7 KJ/kg

2770.8 KJ/kg

2151.3 KJ/kg

2054 KJ/kg

579.4 KJ/kg

716.8 KJ/kg

2.4 bar, 121.5oC

6.8 bar, 164.3oC

Total Heat

Latent Heat

Sensible Heat

Steam should always be generated and distributed at the highest possible pressure but utilised at the lowest practicable pressure

Minimizing barriers to heat transfer

Resistance to heat transfer of water is 60 – 70 times more than steel and 500 – 600 times than copper Resistance to heat transfer of Air is 1500 times more than steel and 19,000 times than copper

THERMAL INSULATION

The Insulation should be designed such that the skin temperature is not more than 200C above the ambient temperature A bare steam pipe of 150 mm diameter and 100 m length, carrying saturated steam at 8 kg/cm2 would waste 25'000 litres furnace oil in a year.

ELECTRICAL ENERGY PUMPS Reducing the speed of a centrifugal pump by half would reduce the power consumption by 8 times

A reduction in 10% impeller diameter would reduce power consumption by 40 %

ELECTRICAL ENERGY COMPRESSED AIR Every 50C reduction in intake air temperature would result in 1% reduction in compressor power consumption.

Compressed air leak from 1 mm hole size at 7 kg/cm2 pressure would mean power loss equivalent to 4500 kWh per year. Reduction of 1 Kg/cm2 air pressure (8 Kg/cm2 to 7 Kg/cm2) would result in 9% input power savings .

ELECTRICAL ENERGY REFRIGERATION Refrigeration capacity reduces by 6%, for every 3.50C increase in condensing temperature.

Reducing condensing temperature by 5.50C, results in a 20 - 25% decrease in compressor power consumption. A reduction of 5.50C in cooling water temperature at condenser inlet, reduces compressor power consumption by 3%. 1 mm scale build-up on condenser tubes can increase energy consumption by 40%.

ELECTRICAL ENERGY ELECTRIC MOTORS For every 100C increase in motor operating temperature over recommended peak, the motor life is estimated to be halved. If rewinding is not done properly, the efficiency can be reduced by 5 - 8%.

Variable speed drive option can result in input energy consumption reduction by 5 - 15%. In some pump/fan applications saved energy could be as high as 35%.

ELECTRICAL ENERGY LIGHTING Ensure proper illumination & efficacy (lumens / watt) Install photocells Use timers Retrofit occupancy sensor Use servo stabilizer in lighting circuit Replace High Pressure Mercury Vapour lamps with High Pressure Sodium Vapour lamps Replace conventional chokes with electronic chokes

But is the Task Really Finished? Are we Experts in Energy Conservation and Efficiency ?

When and Why Should we start to “Practice What we Preach”

THANK YOU