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APPLIED INDUSTRIAL ENERGY AND ENVIRONMENTAL MANAGEMENT Z. K. Morvay, D. D. Gvozdenac

Part III:

FUNDAMENTALS FOR ANALYSIS AND CALCULATION OF ENERGY AND

ENVIRONMENTAL PERFORMANCE

1

Applied Industrial Energy and Environmental Management Zoran K. Morvay and Dusan D. Gvozdenac © John Wiley & Sons, Ltd

Toolbox 2

ENERGY AUDITING IN INDUSTRY

Step-By-Step Guide to Carrying Out an Energy Audit

STEP 1 UNDERSTANDING INDUSTRIAL OPERATIONS

STEP 2 PRELIMINARY ENERGY AUDIT

STEP 3 IDENTIFICATION OF ENERGY CONSERVATION

OPPORTUNITIES (ECO)

STEP 4 DETAILED ENERGY AUDIT (DEA)

• preparing measurement plans and conducting measurements

STEP 4.1 SPECIFICATION OF ENERGY CONSERVATION MEASURES

(ECM)

STEP 4.2 PREPARATION AND PRESENTATION OF DEA REPORT AND

ACTION PLANS

STEP 1: UNDERSTANDING INDUSTRIAL OPERATIONS

Developing an understanding of industrial operations is a prerequisite for the analysis of energy

efficiency in an organization. In order to achieve that, we start with data on the general characteristics

of the business (Checklist 1) followed by data collection on energy use, main utilities and

characteristics of energy end-use requirements, as described by Step 2.

CHECKLIST 1: GENERAL CHARACTERISTICS Activity Type (sector):

Main products:

Production capacity [t/y]

Capacity utilization [%]

NATIONAL OR MULTINATIONAL:

History

When established:

Growth pattern

Part III – Toolbox 2:

ENERGY AUDITING IN INDUSTRY 2

Cost structure

Raw material [%]

Labor [%]

Energy [%]

Other [%]

EXTERNAL ENVIRONMENTAL FACTORS

Economics

Broad economic setting:

Development trends:

Structure and share of the market:

OBJECTIVES AND STRATEGIES General

Specific organizational objectives and strategies as defined by management

Growth

Growth objectives over the next 5 years

Investment

Policies and plans, main projects

STEP 2: PRELIMINARY ENERGY AUDIT (PEA)

A PEA is essentially a data gathering exercise which aims to develop an understanding of how energy

is used in a factory, and prepare a background for detailed energy audit (DEA) implementation (Fig.

2.1). Questionnaires 1 and 2 will help to guide you through and structure the data gathering process.



Figure 2.1: Flow Chart of Preliminary Energy Audit (PEA)

QUESTIONNAIRE 1: PRELIMINARY ENERGY AUDIT – Data on energy consumption and costs

Company:

Address:

General Manager:

Contact person:

Telephone, Fax, E-Mail

By:

Date:



GENERAL INFORMATION

Production program and capacity

Production in the year ______ (description and quantities of final products)1

Raw materials (description and quantities):

Short process description (phases)

Draft scheme of the production process

1 All quantities shall be given for the same year.



Electricity, 3×380 V

Steam, 8 barg

Industrial Water

Cooling Water, 34 oC

Compressed Air, 7 barg

Waste Water

Solid Waste

Total annual operating time [h/yr]:

Number of shifts per working day:

Total number of employees:

Number of employees in energy group:

Head of group:

Total annual cost of production:

Total annual cost for energy and water:



Layout of the factory



MONTHLY SUMMARY OF FUEL OIL CONSUMPTION AND COSTS

Name of fuel:

Source:

Fuel classification:

Average low calorific value [kJ/kg]:

Year of consumption:

Month Deliveries

[l]

Cost of

delivery

[ ]

Working

days in a

month

Consumption

[l]

Cost of

consumed fuel

[ ] 1 2 3 4 5 6

I

II

III

IV

V

VI

VII

VIII

IX

X

XI

XII

Total



MONTHLY SUMMARY OF ELECTRICITY ENERGY AND COSTS

Tariff description:

Year of consumption

Month

Active energy Reactive energy Total cost

[ ]

Consumption

[kWh]

Price/unit

[ /kWh]

Consumption

[kVArh]

Price/unit

[ /kVArh]

1 2 3 4 5 6

I

II

III

IV

V

VI

VII

VIII

IX

X

XI

XII

Total



MONTHLY SUMMARY OF ELECTRICITY DEMAND COSTS

Month

Maximum demand

(on peak; partial peak)

Cost

[ ]

Total cost

of demand

Total cost of

energy and

maximum

demand

On peak

[kW]

Partial

peak

[kW]

On peak Partial

peak [ ] [ ]

1 2 3 4 5 6 7

I

II

III

IV

V

VI

VII

VIII

IX

X

XI

XII

Total

MONTHLY SUMMARY OF FRESH WATER CONSUMPTION AND COSTS

Year of consumption

Month

District system Own wells

Consumption

[l]

Price/unit

[ /l]

Cost

[ ]

Consumption

[l]

Price/unit

[ /l]

Cost

[ ] 1 2 3 4 5 6 7

I

II

III

IV

V

VI

VII

VIII

IX

X

XI

XII

Total



MONTHLY SUMMARY OF WASTE WATER COSTS

Year of consumption

Month

Sewerage system Total cost of

water Total cost

Consumption

[l]

Price/unit

[ / ]

Cost

[ ]

[ ]

[ ] 1 2 3 4 5 4+5

I

II

III

IV

V

VI

VII

VIII

IX

X

XI

XII

Total



QUESTIONNAIRE 2:

PRELIMINARY ENERGY AUDIT – Specifications of main utilities

ENERGY TRANSFORMERS

Boiler Room

BOILER No.1

BOILER No.2

FEEDWATERTANK

Make UpWater

Returncondensateapp. 65 %

STEAM to process

Oil

Preheater

Heavy Fuel Oil

Blow Down

Feed Water

Pumps

EXAMPLE

Figure 2.2: Draft Scheme of the Boiler Room

Number of boilers:

Total capacity:

Total annual production of heat energy [TJ/yr]:

Total annual fuel consumption [h/yr]:


Total annual quantities of water supplied to the

system [h/yr]:



Steam Boiler

Figure 2.3: Draft Scheme of the Steam Boiler

Type of boiler:

Design capacity [t/h]:

Fuel:


Age [years]:

Rated capacity [t/h]:

Annual fuel consumption [yr]:

Annual operating period:

Pressures and Temperatures

Steam pressure at boiler outlet [kPa]

Steam temperature at boiler outlet [oC]:

Water temperature at boiler inlet [oC]:

Combustion air temperature [oC]:

Temperature of gas leaving the boiler [oC]:

Fuel temperature [oC]:

Flue Gas Analyses

CO2:

O2:

CO:

N2:

Excess air:



Electric Power

Figure 2.4: Draft Single-Pole Scheme of the Transformer Station’s Connection

Annual need for electric power satisfied by:

Distribution system [%]

Your own CHP plant [%]

Voltage of the power supply system [kV]

Voltage transformation [kV]

Number of transformer stations

Number of transformers

Total installed capacity [kVA]

Installed capacity per units [kVA]

ENERGY END-USERS

A/C systems

A/C systems used:

Number of independent systems:

Total design quantity of the A/C air output [m3/h]



FRESH AIR

OAHU 1 & 2

FRESH AIR

CFU

AHU

OEF

PREMISES

24 oC

50 %

SA

RA

FA

AHU

OEF

PREMISES

24 oC

50 %

SA

RA

FA

AHU

AEF

PREMISES

24 oC

50 %

SA

FA

RA

84000 m3/h

1512 kW

46800 m3/h

179600 m3/h

825 kW

133300 m3/h

538800 m3/h

1943 kW

494500 m3/h

44800 m3/h

85800 m3/h

605 kW

63900 m3/h

19100 m3/h

FRESH AIR

AHU

AEF

PREMISES

24 oC

50 %

SA

FA

RA

30250 m3/h

3150 m3/h

OAHU 3

39400 m3/h

170 kW

3150 m3/h

66 kW

FRESH AIR

PREMISES

24 oC

SA

OAHU 4

A B C D E

Figure 2.5: Draft Scheme of the System

Age [years]

Total design capacity of air cooling

[MJ/s]

Annual operating time (describe all relevant facts and characteristics, such as changes in

working conditions, seasonal and other)

Daily operating time (describe):

Air temperature [o C]

Type of regulation



Compressed air system

Compressed air system used in a building:

DC 5600 AF0.9

After Filter

65AFlow Adjust

65A

DRY-1DOMNICK AO

15/30 1.0

Pre Filter65A

PQ

DC 5600 AF0.9

After Filter

65AFlow Adjust

65A

DRY-2DOMNICK AO

15/30 1.0

Pre Filter65A

PQ

DC 5600 AF0.9

After Filter

65AFlow Adjust

65A

DRY-3DOMNICK AO

15/30 1.0

Pre Filter65A

PQ

PG

100A

100APG PG

After FilterPre Filter65A

200A

PG PG


200A

PG PG


200A

PG

FQ

PG


200A

PG

After Filter

PCC 1200 AF

0.7Flow Adjust

80A

DRY-5Pre Filter

DOMNICK

40/30/30 0.980A

FQ

50A

50A

FQ

FQ

FQ

200A

200APG

100A

10A

15A

PG

20A

PG

Seperator

Sequence Control

in Control room

Air Tank

WWT.

Auto Tabe

Cleaning R-3

25A

15A

25A

15A

10A

20A

40A

PG

PG

PG

AIR SUPPLY

40A

PG

PG

PG

AIR SUPPLY

40A

PG

PG

PG

AIR SUPPLY

40A

PG

PG

AIR SUPPLY

50A/75A

Ball

Valve

CFU-1

40A

PG

PG

PG

AIR SUPPLY

PG

PG PG PG PG PG PG

Unload

PG PG PG PG PG PG

Unload

150A /100A

150A /100A

100A 100A

50A/75A

100A

15A

75A

15A

75A

15A

75A

100A100A

40A

40A

40A

100A

Figure 2.6: Draft Scheme of the Compressed Air System

Number of compressors:

Total capacity [nm3/min]

Capacity per unit [nm3/min]

Output pressure [kPa]

Total capacity of electric motors [kW]

Unit capacity of electric motors: [KW]

Volume of the tank [m3]

Type of regulation

Air cooling system

Parameters

Working pressure of machinery [kPa]

Entering air temperature [o C]

Daily operating time (system):

Daily operating time (compressors):



STEP 3: IDENTIFICATION OF ENERGY CONSERVATION

OPPORTUNITIES (ECOs)

During inspection of the plant, as a part of PEA activities, opportunities for energy conservation have to

be identified. The following checklist should serve as a reminder as to where to look for ECOs.

Based on the ECOs identified, measurement plans will be prepared and measurements executed

during the DEA, in order to evaluate the potential for energy performance improvement by individual

ECOs.

ELECTRICAL SYSTEM – GENERAL

• Use demand limiters where applicable and where cost benefits exceed installed cost without

creation of unacceptable environmental conditions or limitations in manufacturing

production.

• Replace oversized motors and replace old motors with new energy-efficient motors.

• Investigate power factor improvement.

• Use two- or three- speed motors on pumps and fans when reduced flow is desired.

• Improve maintenance for all equipment.

• Reduce lighting levels where this will not reduce manufacturing production or quality or

sales efficiency. Turn off lights when not needed. Replace present lighting with more

efficient lighting sources.

• In manufacturing processes control warm-up time and turn off time.

• Reschedule production or other operations to spread out the electrical load and thus

improve the load factor.

• When possible, modulate a load rather than turning it off and on.

• Install small electric boilers for local requirements rather than operating a complete steam

system.

• In manufacturing plants, install sub metering for manufacturing sections. This has the effect

of making a manufacturing subsection an energy profit centre.

• Use variable-speed drives.

• Installation of electrical-peak-shaving generators.

The largest savings of electrical energy by electrical energy management will come from the basic

principle:

‘WHEN YOU DON'T NEED IT, TURN IT OFF’

AIR CONDITIONING

• Turn off air conditioning in all unoccupied areas.

• Ensure that the air conditioning system is in good working order; keep filters, coils and

blowers clean.

• Use spot coolers when spaces are occupied only at various and irregular times.

• Clean refrigerant condensers to reduce compressor horse power.

• Utilize humidity controlling systems which will allow humidity to rise to the highest

acceptable setting – systems that use re-heat are particularly beneficial.

• Minimize the heat created by lights, machinery or equipment which are left ‘on’ when not

required.

• Leave storm doors and windows in place during the summer to prevent outside heat from

coming in.

• Use water cooled lighting fixtures if possible.

• If the office is completely vacated after normal closing hours, turn off air conditioning at least

one hour before quitting time.



• If possible, use heat-producing equipment such as photocopiers in the early morning or late

afternoon.

• Use awnings or shades to reduce heat gain from insulation.

• Urge employees to wear lighter clothing in order to accustom themselves to slightly higher

office or plant temperatures.

• Consider a spraying system or other means of evaporating water on the roof in order to reduce

the air conditioning load.

• Size air handling grills, ducts and coils in order to minimize air resistance.

LIGHTING

• Turn off all unnecessary lights.

• Replace low efficiency light sources with fluorescent, mercury, sodium or high intensity

direct lighting.

• Keep bulbs and fixtures clean and free of light-blocking dirt.

• Remove lights selectively – and ballasts – where lighting levels exceed established standards.

• Reduce or eliminate decorative lighting.

• Install photocells in order to control outdoor or perimeter lighting.

• Utilize direct sunlight as a light source wherever possible.

• Employ a lower wattage of lighting where possible.

• Use light colors on ceilings and walls, floors and furnishings.

• Install timers on lights in little used areas of the plant.

• Use automatic switches in order to ensure that plant lighting is extinguished after the last shift

leaves.

• Provide light switches in office areas so that individual lights may be turned off.

• Place lighting switches in prominent places.

• Move to ‘task lighting’ wherever possible.

• Eliminate inefficient electric lamps from plant stocks and catalogs.

• Consider turning off plant lights during lunch breaks.

INDUSTRIAL BOILERS

• Look to stack gas temperatures as a running indicator of boiler performance.

• Carry out frequent checks of boiler performance.

• If more than one boiler is in use, sequence boiler use in decreasing order of efficiency.

• Keep as many boilers as possible operating near full load (rather than having a greater number

operating at partial capacity).

• Keep all heat transfer surfaces clean.

• Improve boiler control systems.

• Reduce ‘excess air’ in order to increase boiler efficiency.

• Look to waste heat boilers and/or economizers in order to utilize hot stack gases.

• Utilize boiler blow-down as flash steam or in a blow-down heat exchanger in order to preheat

make-up water.

• Reduce blow-down through feed-water control.

STEAM

• Fully insulate all steam and condensate lines, and process equipment.

• Cover and insulate condensate tanks.

• Repair or replace faulty steam traps.

• Repair all other sources of steam leakage including flanges and high pressure reducing

stations.

• Maintain steam jets used for vacuum system.

• Ensure that boilers are operating at peak efficiency.



• Keep boiler tube surfaces clean.

• Return condensate to boiler – or use pre-softened cooling water from compressors, etc. as

feed-water – in order to minimize both blow-down and overall energy and water

consumption.

• Monitor boiler blow-down chemical analysis.

• Recapture blow-down energy using heat exchangers or flash tanks.

• Use air heaters and/or economizers to recover heat from boiler flue gases.

• Minimize the distance that steam must travel by re-arranging process equipment and

eliminating straggling steam laterals.

• Use insulation valves to split up the steam distribution system.

• Operate steam-heated processes at the lowest permissible temperature.

• Lower steam pressures wherever possible.

• Use steam traps and/or balance pressure air vents in order to eliminate air films in steam lines.

• Put flash steam to work in lower pressure applications.

• Where clean condensate cannot be returned to the boiler, use it for washing or other

processes.

• Turn off steam tracing during mild weather.

• Look to glycol tracing systems to replace steam.

• Consider replacing electric motors with back pressure steam turbines and use exhaust steam

for process heat.

• Operate distillation columns at minimum quality requirements.

• Operate distillation columns at near flooding conditions for maximum separation efficiency.

• Determine correct feed plate location on distillation columns in order to increase efficiency

and minimize steam consumption.

• Consider switching selected steam stripping distillation units from direct (live) steam to

indirect (dry) stripping.

• Use steam traps of a correct size.

• Evaluate replacing condensing steam turbine rotating equipment drives with electric motors,

if your plant has a power generating capability.

• Add traps to distillation column in order to reduce the reflux ratio.

• Minimize boiler blow-down with better feed-water treatment.

• Use waste heat low pressure steam for absorption refrigeration.

• Replace barometric condensers with surface condensers.

• Shut off steam traps on superheated steam lines when not in use.

• Optimize the operation of multi-stage vacuum steam jets.

• Use insulation of optimum thickness.

• Use reflux ratio control or similar control instead of flow control on distillation towers.

• Substitute hot process fluids for steam.

FURNACES, KILNS AND OVENS

• Calculate and plot boiler efficiency daily.

• Establish a definite burner maintenance schedule.

• Adjust burners regularly for the most efficient operation.

• Heat oil to a proper temperature for good atomization.

• Eliminate combustible gas in flue gas.

• Reduce combustion air flow to an optimum level.

• Replace obsolete burners with more efficient ones.

• Use waste and by-products as fuel wherever possible.

• Limit and control secondary combustion air in furnace operations.

• Calculate a ‘heat balance’ for all combustion equipment in order to better understand where

energy is dissipated or used.

• Utilize hot stack gases as an energy source.

• Insulate furnaces, kilns and ovens in order to minimize heat loss.



• Control infiltration of cold air into furnaces.

• Shut down idle combustion whenever possible.

• Consider cam controllers or other systems in order to control the shut down cycle on

combustion equipment.

• Schedule plant operations for ‘full load’ operations on combustion equipment.

• Minimize energy loss during loading and unloading (cycling).

• Eliminate ‘over-design’ in equipment and practices.

• Analyze flue gases regularly.

• Look into using automatically controlled flue dampers.

COMPRESSED AIR

• Make an optimized selection of a central compressor versus a number of smaller zone

compressors.

• Choose the compressor with the highest efficiency.

• Select an air intake location that provides dry, clean air.

• Maintain compressor driving belts, and all other critical parts.

• Ensure that water cooling ducts are not blocked.

• Use larger or extra receivers on existing compressors.

• Investigate automatic control systems.

• Provide basic instrumentation in order to gauge system efficiency.

• Repair all line leaks promptly as part of a regular maintenance program.

• Use long radius bend and welded joints wherever possible in piping.

• Incorporate strainers and lubricators in each air-operated device.

• Maintain air operated equipment regularly as well as ‘conditioning units’ – filters, pressure

regulators and lubricators.

• Do not operate equipment above the manufacturer's recommended operating pressure.

• Reduce air pressure to the lowest feasible level.

• Consider using double acting air cylinders.

• Use hot air from remote receiver tanks close to cylical loads.

• Use hot air from air cooled compressors for space heating wherever economically available.

• Cooling water from water cooled compressors has many potential uses within the plant.



STEP 4: DETAILED ENERGY AUDIT (DEA)

A detailed energy audit aims at establishing actual energy performance of selected end-users and

processes. Based on identified of energy conservation opportunities during the preliminary audit.

At the heart of a DEA is a specific metering campaign which usually takes a week or two

according to a carefully prepared measurement plan (see Examples 1 and 2 below). The measuring

results are analyzed in order to establish energy balances, specify performance improvement measures

(Step 4.1) and carry out an economic and financial analysis of performance improvement projects

(Fig. 2.7)

Figure 2.7: Flow Chart of Detailed Energy Audit (DEA)

The Economic and Financial Evaluation of energy performance improvement measures includes

cost-benefit analysis, calculation of economic and financial internal rates of return (EIRR and FIRR)

and a discounted cash flow analysis. It is described in Toolbox III-3 and includes a spreadsheet

program (Software No. 3, Toolbox III-3), for carrying out such calculations.

The audit results have to be summarized in a report, together with an action plan containing the

priorities for the implementation of performance improvement projects, as specified in Step 4.2.



Example 1: Preparing the measurement plan for a steam boiler

M1 Combustion air:

- Temperature, tFA [oC]

- Relative humidity, RHFA [%]

M2 Fuel consumption:

- Fuel flow rate, mF [l/h, t/h, nm3/h ….]

- Temperature, tF [oC]

M3 Steam (saturated):

- Pressure, pS [bar]

M4 Feed water:

- Mass flow rate of feed water, mFW [t/h]

- Temperature, tFW [oC]

- Conductivity, CondFW, [µS/cm]

M5 Flue gas:

- Flue gas temperature, tFG [oC]

- Oxygen content, O2 [%]

- CO content, CO [ppm]

M6 Blow-down:

- Mass flow rate of blow-down water, mBD,

[t/h]

M7 Boiler water:

- Conductivity, CondBW, [µS/cm]

Example 2: Preparing measurement plan for a a Sterilization Process (Retorts)

M1 Mass flow rate versus time kg/h

Temperature oC

Pressure Bar

Duration min

M2 Mass flow rate of water versus

time

kg/h

Temperature oC

M3 Mass flow rate f condensate kg/h

Temperature oC

M4 Mass flow rate of water kg/h

Temperature versus time oC

M5 Mass of product in kg

Temperature oC

M6 Temperature oC



STEP 4.1: SPECIFICATION OF ENERGY

CONSERVATION MEASURES

All of the measures or performance improvement projects have to be specified to the level of a

conceptual engineering design (see the example below).

Project:

CHP

ECM #2:

Gas Engine Installation

Scheme and position of NEW PLANT

Investment specification: Design and installation 25 000

Supervision 12 500

EQUIPMENT

Gas engine and generator

(electrical output 1,819 kWe) 1 000 000

Absorption chiller

Capacity 861 kWR; hot water 88/83 oC 327 500

Heat exchanger for engine cooling

(767 kWH) 45 000

Heat exchanger for flue gases (1148 kWH) 70 000

Transformer 0.4/20 kV 62 500

Cooling tower 20 000

LOCATION PREPARATION

Site preparation 5000

Adoption the existing installation 12 500

Gas connection installation 7500

MISCELLANEOUS

10 % of equipment cost 152 500

TOTAL: 1 740 000 $US

Energy cost reduction:

0.2487 m$US/y

Simple pay back period:

7 years

Reduction in co2 emission:

31.1 %



STEP 4.2: PREPARATION AND PRESENTATION OF DEA

REPORT AND ACTION PLANS

1. Recommended chapters for DEA report

• Executive summary

• General data on factory and processes

• Observations and comments on operational, housekeeping and maintenance practice

• Current level of production and energy consumption and energy balances

• Specifications of identified energy performance improvement measures

• Expected values of energy cost savings

• Investment analysis:

– Economic aspects: Payback period and EIRR

– Financial aspects: Cash flow and FIRR

• Quantitative target for improving energy performance

• Implementation plan for achieving the set targets

• Technical details and specifications must be attached

2. Approach to preparing an energy action plan

The order of consideration of energy conservation measures: i. Improvement of maintenance practices,

ii. Improvement of operation practices,

iii. Improvement of equipment efficiency,

iv. Improvement of process efficiency.

The order of priority for the implementation of energy conservation measures: i. Introduction of systematic energy management practices (including awareness,

training and motivation programs)

ii. Improvement of energy metering, control and monitoring (provide data for continuing

improvement of efficiency)

iii. Improved housekeeping and maintenance

iv. Implementation of energy performance improvement projects with a short payback

period

3. Selling of energy action plan to management

i. Organize the session as a formal presentation to be attended by general, technical,

production, financial and maintenance managers

ii. Establish the relevance of energy costs

iii. Explain the opportunities for cost reduction

iv. Avoid technical jargon and detail

v. Provide comparisons or benchmarks within the industry group

vi. Provide a time scale in order to achieve results

vii. Provide targets for the coming years

viii. Specify investment requirements

toolbox 2 energy auditing in industry - wiley.com · developing an understanding of industrial...

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