page 1 basic industrial and commercial electrical energy audit training for utility personnel draft...

Basic Industrial and Commercial Electrical Energy

Audit Training for Utility Personnel

DraftRobert Scott Frazier, Ph.D., CEM.

Assistant Professor,Renewable Energy Extension EngineerBiosystems & Agricultural Engineering

Oklahoma State University(405) 612-3641

What We Will Cover Today

• Utility Background Data• QuickPEP® Software• Motors• Lighting• Compressed Air• HVAC• Process Heat

What You Should Come Away With

1. Ability to produce general recommendations for the facility

2. Ability to generate a nice cover report with graphics for the customer regarding energy use

3. Ability to spot some of the more common energy areas for opportunity

Before we begin …

There are two ways to look at a facility's energy conservation (savings) potential:

(1) A general view – without much effort – how muchmight we save and in what general areas?

(2) A detailed view – with more effort – at what specific points in the plant can we place improvementefforts and how much can we expect to gain from these efforts?

ENERGY AUDIT WORKSHOP

Eight (Typical) Key Energy Issues in Auditing Facilities

1. Current situation -- getting a grip.2. Process heating and cooling.3. Steam and steam delivery.4. Compressed air and air delivery.5. Building and HVAC.6. Lighting.7. Electrical motors and systems.8. System x system interactions (not specifically

discussed, but very important in overall assessment).

Eight Key Questions for Commercial and Industrial Systems

1. What function(s) does this system serve?2. How does this system serve its function?3. What is the energy consumption of this system?4. What are the indications that this system is properly

functioning?5. If system is not working properly, how can it be

restored to proper operation?6. How can the energy cost of this system be

reduced?7. How should this system be maintained?8. Who has direct responsibility for maintaining and

improving the operation and energy efficiency of this system?

What Equipment is Needed for Basic Energy Auditing?

• Inexpensive IR Thermometer• Digital Camera• Data Loggers (Onset, etc.)• Steel toe boots/shoes • Side shields for glasses (get your own)• Ear plugs (get your own)• Good notebook and multiple pens• Business cards

What Else Should You Know?

• What Federal Incentives are there?• What State Incentives?• Visit http://www.dsireusa.org• Stay on top of it – it constantly changes with

the whims of Washington and state government

http://www.dsireusa.org/

Current Situation – Getting a Grip

• Facility Background• Personalities• Rate Schedule• Billing Analysis• Energy Profiles – As a whole• Energy Profiles – By systems/processes

(if you can)

Start a File (Hard and Softcopy)

• Everything goes in…– “Google®” company– Photos– Hand notes– Emails (Print if important)– Correspondence– Newspaper articles– Napkins with notes– Anything at all that has to do with this customer

Pre-Visit Phone Information I• Primary Contact Name:• Street Address of the plant we will be visiting:• Principal products Produced:• # of Employees:• Annual Sales ($):• Annual Energy Expenses ($):• # of Building we will be looking at:• Plant Area (square feet):• Production/yr (lbs, pcs…../yr):• Number of Shifts per day per week (and hours):• Primary Energy Users:

Boilers ….How Many, approx capacity (MMBtu, lbs steam, etc.)…Fuel typeChillers….How Many, approx capacity………SizeFurnaces…How ManyAir Compressors…..How Many……What HP?

• Type Of HVAC in Plant/Offices:• Type of Lighting in “ “ :• Other Energy Users of Interest (Blow Molders, etc.) ……..Energy Size (kW, Btu, etc.):• Other: (Things you would like us to look at) Do we need to bring safety Equipment? Don’t show up in open toe shoes or 3-piece suit. Leave jewelry at home.

Pre-Visit Phone Information IIYou may need to get copies of originals bills. You arethe utility so you may have this in-house…

• Energy bills (gas also possibly) for the past 12 consecutive months.• Water and sewer bills for the past 12 consecutive months.• Simple plant layout (8.5x11) (if they have it)• Process flow chart (if they have one)• List of primary energy consumers (e.g. motor list with horse

powers's, etc. if they have it)

** Part of this is to show the client – this is stuff they should have and be aware of!

Personalities

• Who is your main contact?• How important are they?• Are they threatened by this visit?• Plant manager knows the plant…• CEO can make sure projects get implemented…• Closing meeting – who is responsible for any

possible recommendations?• Implementation and progress calls (let’em know

you will be calling)

Rate Schedule

• You are the utility person• If you know nothing else, you should be able to explain

their rate schedule and bills• Make sure you know if they are on a “special” internal

schedule• If it’s a big customer, ask (internally) if there is

anything special you should know about these folks• Ask engineering if there is something unusual about

their service or metering before you go out to the plant (look like the company speaks as one)

Billing Analysis

• One of our most important tools.

• Get data for all meters at general location.

• Assemble data into spreadsheet (next slide).

• Break into columns showing: kW, kWh, Fuel charges, taxes, PPCA, etc.

Billing Analysis (cont.)

Client* Billing Analysis (cont.)

What's going on here?

*Confidential

Client Billing Analysis (cont.)

Billing Analysis (cont.)

Billing Analysis (cont.)• Know the definitions and relationships of kW and

kWh.• Understand what tariff the customer is on and

determine if it is the correct one (they will ask).• Understand the “fine print” items on the tariff and

how they work (e.g. power factor adjustment, ratchet clauses, etc.)

Electrical Energy Management

• Electrical energy management is unique due to the nature of electrical power. Almost impossible to store significant quantities of this

energy source (Maybe hydrogen in the near future). Must have sufficient capacity to meet instantaneous

demands (kW). Odd characteristics such as power factor. Issues such as power quality.

Electrical Demand Control

• Partially because demand (kW) is a separate portion of the bill, we can look at specific methods toward reducing this charge (and impact on electrical system).

• Try to keep in mind however that demand (kW) and consumption (kWh) are closely related.

Electrical Demand

• The thing to keep in mind is that demand is a kind of “snap-shot” of the maximum electrical draw – at any particular time of the month from your facility.

• Recall also that this snap shot is not really instantaneous but usually averaged over some interval like 15 minutes

• That’s good for the customer – shorter intervals are worse. Try to imagine why that is….

• Still, “Demand” is a reflection of how much electrical equipment was on at a particular time in the facility.

Electrical Demand & Load Factor

• There is a “Load Factor” column in the billing analysis spreadsheet

• Load Factor = Total Month’s kWh divided by 720 x measured monthly max demand

• If load factor is <<0.30 for a one shift operation or <<0.6 for a three shift operation, there may be demand control opportunities

• Load factor indicates how even/uneven the electrical usage is during the billing period (demand peaks), LF=1 is a perfectly consistent load

Demand Control (cont.)

• Many demand reduction strategies will be aimed at moving some of the load to different times of the day so we don’t get a coincident peak.

• Other strategies might include going to different types of equipment.

• Lets look at some of these demand control methods.

Demand Control (cont.)• Demand Shedding: In simplified form, the facility

operator will identify the high electrical draw pieces of equipment that can have their operations rescheduled to other times of the day.

• The operator (or software) will be monitoring the facility or sub-area total demand (kW).

• At some agreed-upon kW point, the operator, or software, will reschedule the previously identified equipment to avoid a demand peak.

• Various automated systems available (web search for “electrical demand control”)

Demand Shedding (cont.)

• In a simpler scenario, schedules of the equipment, or processes, are adjusted so that the peaks are avoided ahead of time.

• The problem is: Get it wrong once during the month and a high demand charge may be set.

Demand Shedding (cont.)

• Examples of equipment that can be Demand-Shed:

Chillers. Air handlers. Large pumps. Large Grinders. Recharging Stations (fork trucks, etc.). Large unnecessarily illuminated areas. Any large electrical load is a candidate…


• Duty Cycling (different than demand shedding)

Long uninterrupted equipment run times lead to a higher probability that coincident loads will produce a “peak” demand.

Imagine what types of equipment this sounds like (hint – Air Handling Units)

Duty cycling uses a signal (time, temperature or other controlled parameter) for the on/off operation.


• Other demand and energy control methods Optimum start/stop. Night setback. Hot water reset. Chilled water reset. Boiler and chiller optimization. Chiller demand limiting controls. Free cooling.

Power Factor Improvement

• This is an area that you (as a utility person) need to be somewhat familiar with.

• The reason is that your customers may be billed for Power Factor and you are the utility rep, therefore …

• You will still defer most technical problems to engineering but lets be able to “talk-the-talk” a bit

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Power Factor Basics:

o Induction loads (big electric motors) cause current to lag behind voltage so more kVA is needed to get the same kW. Yet, we are paying for kW. (???) – Bottom line…Power Factor – BAD!

o Charge is applied when PF exceeds the minimum level usually around 80 or 90% (95% for you folks!).

o Power factor is kW/kVA. See power triangle next page.

o Correction is (usually) made by adding capacitor banks

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Power Factor

Power triangle

kVA

kW

kVAR

(kV) x (I) x (√3)

Motor load example: (kVA) x (PF) or (HP load) x (.746 kW/HP) x (1/η)

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Power Factor Example

A plant has 2,000 kW demand and a power factor of 80%. How much capacitance is needed to correct this to 95%? (Why did I use 95%?)

2500 kVA

2000 kW

Δ kVARΔkVAR = 2000 (.421) = 842 kVAR

Table Next Page

2000/.8 = 2500 kVA

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Power Factor Table

• QuickPEP®• http://www1.eere.energy.gov/industry/quickpep/

(wu24wh55es44h1550shxdjby)/default.aspx• Plant Energy Profiler• Quick “Expert System” that gives:

– Estimated Breakdown of Energy Use– Estimated Savings Potential– Suggested Areas for Improvement– Graphics in a report type template

THE GENERAL VIEW

QuickPEP Screens and Sample Case (“TCC-1”)

Must use blended kWh & kW Cost

We will talk about where this data comes from in a bit…

Motors• This is the beginning of the more “detailed”

energy audit• Don’t panic though – all we want is a talking

knowledge of these systems• You are not expected to be the expert on this

stuff – however, you can still provide some insight and value for the customer…

Electric Motor Systems

• Electric Motors Power Many Machines

– Pumps– HVAC– Fans (a type of pump actually)– Air compressor (again, a pump)– Conveyors– Any type of rotary motion…– Motors often the largest (electrical) energy user in a

facility

Electric Motors

• Savings in Electric Motor Management We Will Look At:

– Energy efficient motors.– Savings calculations from

improved efficiency.– Motor rewinds.– Motor drives.

Electric Motor ManagementEnergy Efficient Motors (Induction)

• Why Energy Efficient?– Motor efficiency: percentage of input power actually

converted to mechanical work. – A small 20-HP motor continuously running, even at a

modest energy rate of 0.08 $/kWh, uses about $11,000 worth of electricity per year.

– Over half of electrical energy consumed in the US is used by electrical motors.

Sources: DOE – Best practices @ http://www.oit.doe.gov/bestpractices/


• What is an Energy Efficient motor?– More copper and iron – less resistance losses – (I2R) or

HEAT.– Better fans and bearings more carefully lubricated –

therefore less friction.– Larger and heavier (typically).


Source: Energy Management Handbook, 4th Ed., Turner, W.C., 2001, The Fairmont Press, GA, p.272,273

• Energy efficient motor characteristics– Higher inrush (LRA).– More efficient and higher power factor.– Save energy and reduce demand.– Reduce load on cables, transformers, etc. (note

higher efficiency and PF).– Speed is slightly higher (this can be critical).– Significantly larger inrush (LRA).– Less vibration.– Longer manufacturer’s warranties.


Sources: Energy Management Handbook, 4th Ed., Turner, W.C., 2001, The Fairmont Press, GA, p.286

http://www.wapa.gov/es/pubs/techbrf/eemotors.htm

Energy Efficient Motors

hp 3600 1800 1200 900 hp 3600 1800 1200 900

1 - 82.5 80 74 1 72.5 82.5 80 74

1.5 82.5 84 84 75.5 1.5 82.5 84 85.5 77

2 84 84 85.5 85.5 2 84 84 86.5 82.5

3 84 86.5 86.5 86.5 3 85.5 87.5 87.5 84

5 85.5 87.5 87.5 87.5 5 87.5 87.5 87.5 85.5

7.5 87.5 88.5 88.5 88.5 7.5 88.5 89.5 89.5 85.5

10 88.5 89.5 90.2 89.5 10 89.5 89.5 89.5 88.5

15 89.5 91 90.2 89.5 15 90.2 91 90.2 88.5

20 90.2 91 91 90.2 20 90.2 91 90.2 89.5

25 91 91.7 91.7 90.2 25 91 92.4 91.7 89.5

30 91 92.4 92.4 91 30 91 92.4 91.7 91

40 91.7 93 93 91 40 91.7 93 91.7 91

50 92.4 93 93 91.7 50 92.4 93 93 91.7

60 93 93.6 93.6 92.4 60 93 93.6 93 91.7

75 93 94.1 93.6 93.6 75 93 94.1 93.6 93

100 93 94.1 94.1 93.6 100 93.6 94.5 93.6 93

125 93.6 94.5 94.1 93.6 125 94.5 94.5 94.1 93.6

150 93.6 95 94.5 93.6 150 94.5 95 94.1 93.6

200 94.5 95 94.5 93.6 200 95 95 95 94.1

250 94.5 95.4 95.4 94.5 250 95.4 95 95 94.5

300 95 95.4 95.4 - 300 95.4 95.4 95 -

350 95 95.4 95.4 - 350 95.4 95.4 95 -

400 95.4 95.4 -- 400 95.4 95.4 --

450 95.8 95.8 -- 450 95.4 95.4 --500 95.8 95.8 -- 500 95.4 95.8 --

Shaded area indicates motor classes covered by efficiency standards contained within EPACT 1992

ENCLOSED MOTORSOPEN MOTORS

NEMA Threshold Full-Load Nominal Efficiency Values for EE motors (NEMA MG1 Table 12-10) 1

To be considered energy-efficient, a motor’s performance must equal or exceed the nominal full-load efficiency values provided by NEMA in their publication MG-1.

Energy Efficient MotorsCalculating Savings

• Power and energy savings depends on efficiency of standard vs. energy efficient motor.

• Calculation from replacing w/ EE, assuming same hp and % load: 1) Energy Savings ($) = hp x 0.746 x L x C x N x (100/Estd – 100/EEE)

where: L = % Load * Estd = Efficiency Std motorC = Energy Cost ($/kWh) EEE = Efficiency energy eff. motor

N = annual operating hours

* If “Load %” is measured or estimated as less than 60%, the motor is grossly under loaded and the efficiency will be very low for either Std or EE – resize motor in this case.

Source: Energy Management Handbook, 4th Ed., Turner, W.C., 2001, The Fairmont Press, GA, p.286

Energy Efficient MotorsCalculating Savings (cont.)

2) kW Savings (Simplified Estimate)

kW = kWstd – kWEE = (hp) (0.746 kW/hp) (100/Estd – 100/EEE)

$Dem. Savings = [(kW)std – (kW)EE] ($/kW.month) (12 month/yr)

3) DecisionPayback = $Motor Cost / [$Savings (Energy + Demand)]

Decision: Choose EE motor if D Payback < maximum desired Payback Period!


Energy Efficient MotorsExample

• Premium efficiency 50 HP motor available at 94.5% eff. to replace a std. 50 HP motor at 90.7% eff. Motor runs 8760 hrs/yr. Electricity demand costs $7.00/kW each month. Electrical energy costs $.05/kWhr.

• What are the operating savings for purchasing the energy efficient motor?

Energy Efficient Motors Example (cont.)

• Demand and energy savings both occur

– Demand savings = (50 hp) (0.746 kW/hp) (100/90.7 – 100/94.5) ($7/kW.momth) (12 month/yr) = $138.9 /yr

– Energy savings = (50hp) (0.746 kW/hp) ($0.05/kWh) (8,760 h/yr) (100/90.7 – 100/94.5) = $724.3 /yr

– Total savings = $ 863.2 /yr

Motor BasicsMotor Rewinds

• Most rewind motors over 10 (40?) HP. • Typical rewinds cost 60+% of a new motor.• New motor could be an energy efficient motor.• Motor efficiency often suffers during rewind

average drop about 1% according to one study and sometimes significantly more.

• If efficiency drops, losses increases, motor runs hotter and won’t last as long.

• Reduce un-needed run-time (ex.: automatic shut-off sensors).

• Reduce peak electrical demand (ex.: scheduling production for off-peak hours).

• Improve plant power factor: PF decreases for under-loaded motors. Don’t just put in PF capacitors first.

• Improve the efficiency of motor power trains: Cogged V-belts last longer and improve system efficiency by 2% to 4% over regular V-belts, while reducing maintenance and replacement costs.

• Replace the oversized motors: motor efficiency and power factor degrades quickly when motors are dramatically under-loaded.

• Work up an effective motor management program (e.g., replacing failed motors with Energy Efficient motors vs. rewinding when cost justified).

Electric Motor Summary

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• Many motor applications are inefficient because…

– Motor is oversized for application (therefore underloaded)

– Load varies from little to near full rated load during process operation

– Fan or Pumps are being driven too fast for actual application need

Motor Drives - Introduction

Recall the graphs of motor load and power factor?

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Motor Drives - Introduction

• Variable Torque Load– increase with speed and torque are usually

associated with centrifugal fan and pump loads, where (in theory) the HP requirement varies with the cube of the speed change. When driving positive displacement pumps, the HP requirement varies as the square of the speed change

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Electric Motor Management

“Drives”• Motors operate at fixed speeds, running between No Load RPM

and Full Load RPM• Processes (pump, fan, etc.) often require other speeds on the

driven end. Load on the motor is affected.• Various methods to vary speed: variable pitch pulley drives,

inlet-outlet dampers, inlet guide vanes, magnetic clutches, variable frequency drives (VFD)

• A VFD varies frequency and voltage of the motor supply line to match the load

• In constant torque applications VFDs can improve process control and reduce maintenance costs (e.g. Conveyor)

• Variable torque applications, such as centrifugal devices (pumps, blowers, fans), are desired applications for varying CFM or GPM because of the “fan laws” by using VFD’s

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Electric Motor ManagementFan Laws (Centrifugal Devices ONLY)

• CFM2 = CFM1(RPM2/RPM1) 1st law

• SP2 = SP1(RPM2 /RPM1)2 2nd law

• HP2 = HP1 (RPM2/RPM1)3 3rd law


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Electric Motor Management“Fan Laws” Example

• Opportunities for considerable savings in centrifugal devices by adjusting rotational speed

• Ex.: If the RPM of a fan can be reduced by 20%, its energy consumption will be:

HP2/HP1 = (RPM2/RPM1)3 = [ (RPM1 x 0.80) / RPM1 ]3

= 0.51 HP2 ~ 51% of HP1 - A drop of 49% !!

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Electric Motor ManagementFan Laws – Strange Example

• Fan system 32,000 CFM. Existing standard efficiency motor of 20HP and 1750 RPM. Considering replacing with a new 20-HP, EE motor (1790 RPM).

• What is the impact on energy consumption?

New CFM = 1790/1750 x 32,000 CFM = 32,731New HP requirement = (1790/1750)3 x 20 = 21.4 HP

7% increase !


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Typical Power Consumption of Various Motor Control Systems


Sv = Savings at 60% load when going from “constant volume” to “variable inlet vane”

Sv

Svfd = Savings at 40% load when going from “constant volume” to “variable frequency drive”

Svfd

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Electric Motor ManagementSelection of Best Option

• Outlet vane control (“potato in exhaust”)– Simple and effective (watch for cavitation or surging)– Not efficient, infrequently used– Great candidate for conversion to others

• Inlet vane control (“potato in carburetor”)– Simple and effective (watch for cavitation)– More efficient than outlet but significantly less than other

options, fairly frequently used– Great candidate for conversion to others

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Electric Motor ManagementSelection of Best Option

• Variable Frequency Drive (VFD)– Probably most efficient– Competitive cost– Harmonic concerns (input and output)– Remote (clean area) installation– Multiple motors may be connected to one drive providing higher

savings, but sizing is critical– Motors and load must be agreeable to VFDs (may need cooling)

• Magnetic clutches (permanent magnet or eddy current)– Bulky and heavy on motor shaft (seen on older applications)– No harmonics– Close to same savings but less

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VFD Application – Typical Loading Profile

Source: Energy Management Handbook, 4th Ed., Turner, W.C., 2001, The Fairmont Press, GA

78

1001

8,7600.02870.746

Percent Load Cycle Fraction hrs/yr Present VFD kWh Savings $ savings20% 0 0 1.1 0.09 0.00 0.0030% 0.05 438 1.1 0.11 32348.05 928.3940% 0.16 1401.6 1.1 0.14 100376.99 2880.8250% 0.23 2014.8 1.1 0.2 135273.67 3882.3560% 0.23 2014.8 1.1 0.29 121746.30 3494.1270% 0.20 1752 1.1 0.43 87568.46 2513.2180% 0.09 788.4 1.1 0.62 28231.03 810.2390% 0.03 262.8 1.1 0.85 4901.22 140.67

100% 0.01 87.6 1.1 1.16 -392.10 -11.25TOTAL 1 8760 510,053.63 14,638.54$

Conversion Factor: 1 Hp =

Power i/p Ratio[1]

Total HpLoad FactorOperation (hrs/yr)Consumption Charge ($/kWh)

For 50% load row: (100 hp)(0.746 kW/hp) (1.1-0.2) (0.23)(8,760) = 135,273 kWh/yr (135,273 kWh/yr) ($ 0.0287 /kWh) = $ 3,882.35/yr

Total annual savings: Savingsi = $14,638.54 , Simple Payback ~ 1.2 years

Ex.: VFD Application - Cooling Water System

Source: Oklahoma Industry Assessment Center, Report OK#0703

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$$$$ - Summary

• Choose the technology that the facility staff understands and likes to use

• You probably don’t want to mix technologies in a given facility

• Most efficient is VFD followed closely by magnetic clutching followed (way back) by inlet and outlet vane controls

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$$$$ - Summary

• For cooling towers work on air side as opposed to water side– Larger motors– Doesn’t affect operation as much (freeze protection,

biological control, etc.)• Concentrate on centrifugal devices not axial or

reciprocating– Chilled water pumps, cooling water pumps, etc.– Blowers on cooling towers or VAV HVAC units

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$$$$Variable Speed Drive Applications

• Chilled water pumps for large campus• Cooling tower water pumps• VAVs using inlet vane• Forced draft (blower) cooling towers• Any large centrifugal blower or pump that runs a

lot!– Constant volume? Convert to variable volume – Variable volume with inlet or outlet control

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• Reduce/Vary Flow Rate. In pump and fan applications, the work required by the pump or fan is the product of the volume flow rate and the pressure drop through the distribution system. The pressure drop through the distribution system is proportional to the square of the volume flow rate. Thus, pump/fan work is proportional to the cube for volume flow rate. Because of this, small reductions in fluid flow rate can mean large reductions in motor power (“fan laws”)

• Reduce System Pressure Drop. Reducing pressure drop through piping and ducts can reduce pump/fan energy consumption. In new applications, specify large diameter pipes/ducts, low pressure-drop fittings and minimize corners where possible. Then select an appropriately-sized pump or fan for the calculated pressure drop.

• In retrofit applications, open partially closed valves and remove unnecessary fittings. Next, resize the pump impeller or slow the pump/fan to take advantage of the reduced pressure drop. Depending on the individual pump/fan curve, reducing pressure drop without modifying the pump/fan may actually increase the volume flow rate and pump/fan energy consumption.

$$$$ - Summary

Opportunities for Pumps and Fans

83

Electric Motor ManagementAxial and Reciprocating

Pumping/Fans

• Centrifugal laws do not apply (power and flow relationships are more linear due to positive displacement characteristics)

• More difficult to predict savings

• We use linear so no real savings if “on/off” presently used

• Obviously, savings if converting from constant volume to variable volume

Lighting

Lighting

• In an industrial facility lighting may be less than 10% of the electrical load

• In a commercial facility, lighting will probably be between 25-45% of the electrical energy load

• Here in Texas, lighting will tend to be a lower percentage because the A/C loads are so high in the summer

Required light level (foot candles).

Fixture efficacy (Lumens/Watt).

Lumen output of lamps and fixtures.

Color Rendering Index (CRI).

Color temperature (Kelvins).

Types of light sources.

Light quality.

Lighting Issues

Lighting

Principles of Efficient Lighting Design

• Light levels meet requirements.• Light sources are efficiently produced

and delivered.• Qualities meet the application

– Balance efficiency (“efficacy”) with architecture, light quality, and visual comfort.

• Automatically control lighting operation.

Types of Light Sources

• Incandescent. Efficiency• Fluorescent . • Tungsten Halogen. • Mercury Vapor.• Metal Halide.• High Pressure Sodium.• Low Pressure Sodium. Better• Others.

Lamp Color

Color Rendering Index (CRI)

Indicates the effect of a light source on the color appearance of objects:

75 – 100 CRI = Excellent color rendition65 – 75 CRI = Good color rendition55 – 65 CRI = Fair color rendition0 – 55 CRI = Poor color rendition

http://www.nyserda.org/sclp2/technicalguide/about/colorRenderingIndex.asp?section=1.1.4

Typical CRI Values

Light Source CRI

White deluxe mercury 45

Cool white fluorescent tube 65

Daylight fluorescent 79

Metal halide 4200K 85

Deluxe cool white fluorescent 86

Low pressure sodium 0-18

High pressure sodium 25

100-Watt incandescent 100

Color Temperature

Color TemperatureA measure of the “warmth” or “coolness” of a light source:

< 3200K = “warm” or red side of spectrum

> 4000K = “cool” or blue side of spectrum

http://www.fullspectrumsolutions.com/cri_explained.htm

Amount of Light Required For Specific Applications

• We often use more light than is needed for many applications and tasks. – Light levels are measured in footcandles (or lux, in SI units)

using an illuminance meter.FC = lumens / ft2

Lux = lumens / m2

– Consensus standards for light levels are set by the Illuminating Engineering Society of North America (IESNA.org).

Some typical light levels needed are:

Parking lot 2 FootcandlesHallways 10 FootcandlesFactory floor 30 FootcandlesOffices 50 FootcandlesInspection 100 FootcandlesOperating room 1,000 Footcandles

Fundamental Law of Illumination or Inverse Square Law

E = I / d2

whereE = Illuminance in *footcandles (desired or needed)I = Luminous intensity in lumens (from lamp specs)d = Distance from light source to surface area of interest (this you can vary depending on ceiling)

*One footcandle is equal to one lumen per square foot

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ExampleIn a high-bay facility, the lights are mounted on the ceiling which is 30 feet above the floor. The lighting level on the floor is 50 footcandles. No use is made of the spacebetween 20 feet and 30 feet above the floor.

In a theoretical sense – that is, using the fundamental law of illuminance – what would be the light level in footcandles directly below a lamp if the lights were dropped to 20 feet?

FC = 50(302/202) = 112.5 footcandles (shortcut calc)

What to Look for in Lighting Audit

• Inventory of lighting equipment (what's there)

• Determine lighting loads (total wattages).• How are lights controlled? (panels, hard-

wired?)• Light levels at work tops and useable

spaces (use inexpensive light meter)• Hours in use (tricky – survey or log)• Lighting circuit voltage (if you’re an

electrician)

Lighting CalculationsEnergy Savings from delamping or turning off unneeded lamps• 100 fixtures with four, F40T12 - 40 watt lamps, per fixture• Facility runs 2-shifts for 250 days a year• Light levels on warehouse floor = 110 footcandles• Delamp or turn off half the lamps (after doing inverse sq law calc)• Look up wattage of lamps and ballasts in Grainger etc. (160 watts/fixture+12watts/ballast

with 2 ballasts/fixture) = 184 Watts/fixture• Energy Cost: $0.08/kWh , Demand Cost: $9.00/kW

Cost Savings:

kWh = (184 Watts/fixture) x (100/2 fixtures) x (16 hours/day) x (250 days/year) x (1 kWh/1,000 Watt-hour) x ($0.08/kWh) = $2,944/year

kW = (184 Watts/fixture) x (100/2 fixtures) x (1 kWh/1,000 Watt-hour) x ($9/kW-month) x 12 (months/year) = $994/year

Total yearly savings = $3,988/year

Lighting CalculationsEnergy Savings from switching to more efficient lamps• 100 fixtures with four, F40T12 - 40 watt lamps, per fixture (old)• 100 fixtures with four, F32T8 - 32 watt lamps, per fixture (new)• Look up wattage of lamps and ballasts in Grainger etc. F40T12 - (160 watts/fixture

+12watts/ballast with 2 ballasts/fixture)F32T8 – (114 watts/fixture)

Energy Cost: $0.08/kWh , Demand Cost: $9.00/kW

Cost Savings:

kWh = (160 - 114 Watts/fixture) x (100 fixtures) x (16 hours/day) x (250 days/year) x (1 kWh/1,000 Watt-hour) x ($0.08/kWh) = $1,472/year

kW = (160 - 114 Watts/fixture) x (100 fixtures) x (1 kWh/1,000 Watt-hour) x ($9/kW-month) x 12 (months/year) = $173/year

Total yearly savings = $1,645/year – Sounds Good Right?

Wait a minute … Installed Cost = Over $30,000

Payback = 18 years (if installed all at once)

Compressed Air

Compressed Air Systems

Widely used throughout industry, present in almost any industrial plant. Source of energy for tools and machines. Control medium. Material handling. Cleaning.

Relatively expensive to operate -- typical saving opportunities, 20-50% - Folks, this is huge!

Management required on both supply and demand side.

Air power is 3 times more expensive than electrical power!

Sources: “Improving Compressed Air Performance, a sourcebook for industry”, http://www.oit.doe.gov/bestpractices/ compressed_air/pdfs/compressed_air_sourcebook.pdf “Energy Management Handbook, 4th Ed., Turner, W.C., 2001, The Fairmont Press, GA

http://www.oit.doe.gov/bestpractices/

Compressed Air Systems (cont.)

Supply Side Air intake and filter. Air compressor. Dryer. Storage tank. Pressure / flow controllers. Distribution lines.

Demand side Users.

Source: “Improving Compressed Air Performance, a sourcebook for industry”, http://www.oit.doe.gov/bestpractices/ compressed_air/pdfs/compressed_air_sourcebook.pdf




Air Compressor types




Rotary Screw Most popular, range 30 - 200hp. Compact, low initial cost, fairly efficient. Easy maintenance. Air or water cooled.

Reciprocating Driven by an “automotive-type” piston. Available in sizes from less than 1hp up to above 600hp. Large, higher initial cost, very efficient. Usually multi-stage with intercooling.






Centrifugal Kinetic energy developed by centrifugal impeller(s) (typically at 50,000

rpm or more). Usually large, typically above 150hp. Flow capacity decreases as the system pressure increases (head/capacity

curve). Efficient modulation (surge point), VFD-suitable. Good maintenance critical (shaft vibration).

Other types less used


Compressed Air Systems (cont.)Example: Operation cost vs. Initial cost

100hp rotary screw compressor First cost $50,000 8,640 operating hours per year 75% load Demand cost: $7/kW-month ($84/kW-year) Energy cost: $0.08/kWh Average life: Maybe 10 years


Annual op. cost = (100hp)(0.746kW/hp)(0.75) x {($84/kW.yr)+ ($0.08/kWh)(8,640hr/yr)} = $43,372/yr

During the compressor’s life, it will use almost half a million dollars in electrical energy!!



Source: “Compressed Air”, Royo, E.C., 1991, Ed. Paraninfo, Madrid, Spain

Intake air As cool as possible, for every 5.5ºF reduction approx. 1% of increase in

the mass of intake air. (we will see this again…) Intake filter, maintain in top condition. Size properly to minimize

pressure drop.

Drivers Electric motors, most common. Diesel or Gas engines. Steam engine or turbine.

Compressor cooling

Support Systems


After-cooling and drying Remove moisture (100% RH at compressor outlet). In general, 20ºF of temperature drop reduces moisture content by about 50%. Dryer: refrigerant (most common), regenerative-desiccant, deliquescent.

Air receivers (Often Missing…) Smooth compressor cycling, reduce demand fluctuation. 2 to 4 gallons per CFM. Distributed throughout facility.

Support Systems


Distribution Looping (more is better). Size length and diameter to minimize pressure loss (bigger is better). Slopes.

Traps and draining points Allow removal of condensate from lines. However…may be source of air leaks if poor maintenance.

Separators

Support Systems

Compressed Air Systems (cont.) Demand side - Users

Some inappropriate uses of compressed air Open blowing (use brushes, electric fans, blowers, etc). Aspiration/bubbling (use low-pressure blowers). Sparging – aerating or oxygenating liquid with compressed air (use low-pressure

blowers or mixers). Venturis (use vacuum systems). Unregulated hand-held blowing guns. Cabinets cooling (use air conditioners or fans).

Air Quality (which do they have?) Plant air (needs to be fairly dry) Instrument air (needs to be clean and dry) Process air (squeaky clean, completely oil-free?)




Demand side - Users Pressure at the point of use

Supply pressure recommended by manufacturer. Insufficient pressure translates to productivity losses (therefore,

crank pressure up – right?) Pressure drop in distribution <= 10% (i.e., if 90 psig at receiver, then

not less than 80 psig at point of use) – crank it up some more! Pressure drops caused by undersized piping and/or accessories,

leaks, improper filters, regulators, lubricators – more! Monitor between compressor and storage tank. Approximately 1% additional energy required for each 2 psig

increase in air pressure (see where this is headed?)




Pressure Drops



Compressed Air Systems (cont.) Demand management

Quantity (Cubic Feet per Minute - CFM) Sum of average needs. Use secondary storage tanks. Use local pressure regulators (reduce artificial demand).

System controls (just be aware there are out there…) Individual compressor control

Start/stop – reciprocating or rotary screw. Load/unload - motor runs with open valve – unload, 40%. Modulating inlet – rotary and centrifugal.




System controls (cont.) Multiple compressor control: orchestrate compressor operation and air

delivery. Cascading set points: need higher set points to maintain system pressure

above minimum. Sequencers: match supply/demand by taking compressors on/off. Lower

set points achieved. Highly cost effective.

Flow controllers

Bottom line: If client has multiple, large (100 HP +) compressors running, they should have a fairly sophisticated control mechanism like sequencers. Ask to talk to air compressor contractor if client is unaware.

Often clients simply keep adding compressors without addressing control and leakage problems…




Air Leaks – Easiest Recommendation You Will Ever Make…No Brainer

Expensive..really expensive! Good System - 10% Leakage, typical 20-30% (recall the expense to run

slide…) When on/off control: Leakage(%)=(Tx100)/(T+t)

T=On-load time (min)

t=Off-load time (min) If other control strategies:

Leakage (CFM)=Vx(P1-P2)/(Tx14.7)x12.5

P1=normal operating pressure, in psig

P2=50% P1

V=total system volume, in CFMSource: “Improving Compressed Air Performance, a sourcebook for industry”, http://www.oit.doe.gov/bestpractices/ compressed_air/pdfs/compressed_air_sourcebook.pdf



Air Leaks (cont.) Ultrasonic acoustic detector. Soapy water in suspected areas. Off-production schedule. Look at

Connections and fittings. Hoses. Filters and regulators. Valves. Non-operating equipment.

Establish a leak prevention program


Example of annual cost of leaks for a typical installation


Savings Example: Waste Heat Recovery

Source: “Aire Comprimido”, Royo, E.C., 1991, Ed. Paraninfo, Madrid, Spain

Heat available: approx. 250,000 BTU/hr per 100hp

Fan

Cooling air

Thermostat

Dampers

Heat Exchanger

Hot Water

SummerWinter

Compressed Air Summary

• Compressed air is an expensive utility – people treat it like it’s free!

• Look for alternatives before deciding to use it for a particular need.

• Use appropriate multiple-compressor controls.• Properly size lines and storage tanks – don’t skimp here.• Match demand supply pressure – Keep pressure at a

minimum.• Preventive maintenance to avoid air leaks and maintain

traps/drain working – pain in the rear and not sexy but this is where the money can be really saved…

• Recover waste heat – it’s free - they already paid for it elsewhere…

HVAC(R)

• Heating• Ventilation• Air Conditioning• Cooling• Refrigeration

HVAC

• Probably the largest electrical energy user for many of your customers

• Systems can be complex but there are some things to watch for even if you are not an expert

• Lets go over a bit of background first…

HVAC System Components

• Controls (thermostat, computer) • Energy Supply (electricity, natural gas)• Heating or cooling unit (compressor,

evaporator, condenser, valves, burner)• Distribution system

(Ductwork, dampers, etc.)

126

Functions of HVAC Systems

• Purpose: provide and maintain a comfortable environment within a building for the occupants or for the process being conducted.

• HVAC systems were often not designed with energy efficiency as one of the design factors.

• Health and productivity of employees & clients are the most important criteria.

127

HVAC Environmental Control Factors

HVAC systems function to provide an environment in which these four factors are maintained within desired ranges:

• Temperature• Humidity• Air distribution• Air quality

128

HVAC Typical Design Conditions

• 70 degrees F temperature• 50% relative humidity• 30-50 FPM air movement• 20 CFM outside air per person or CO2

less than 1000 ppm (ASHRAE 62-1999 Ventilation Standard)

• ASHRAE std. 55 (next slide)

129

ASHRAE Std. 55 (can be complex)

130

The three principle functions of HVAC systems controls are:

1. To maintain comfortable conditions in the space by providing the desired cooling and heating outputs, while factors which affect the cooling and heating outputs vary.

2. To maintain comfortable conditions while using least amount of energy (on old systems this is not really a consideration)

3. To operate the HVAC system so as to provide safety for the occupants and equipment.

131

HVAC Primary Equipment

• Chillers (Big)• Direct expansion (DX) systems

(Rooftop, Pad Mount)• Boilers (Gas - Steam)• Furnaces (Typically Natural Gas)

132

HVAC Secondary Systems

• Single duct, single zone system• Single duct, terminal reheat system• Multizone system• Dual duct system• Single duct, variable air volume system• Fan coil system

Examples on next pages from Bloomquist 1987

133

Secondary Systems

Single Zone System

Multi- Zone System

134

Secondary Systems

Dual Duct System

Terminal ReHeat System

135

Secondary Systems

Variable Air Volume (VAV) System

Fan Coil Unit

136

4-Pipe Boiler/Chiller system

138

Power and Energy Terms Used in Air Conditioning

• One ton of A/C = 12,000 Btu/hr• A ton is a measure of A/C power, and is used

when sizing systems, or when determining electrical demand

• One ton-hour of A/C = 12,000 Btu• A ton-hour is a measure of A/C energy, and is

used when sizing storage tanks for thermal energy storage (TES) systems, or when determining electrical energy consumption.

139

HVAC System Performance Measures

1. Energy Efficiency Ratio (EER)EER = Btu of cooling output

Wh of electric input

2. Coefficient of Performance (COP)

COP = Energy or heat output (total) Energy or heat input (external)

= EER/ (3412 Btu/Wh)

140

Principles for HVAC Management

1. Most buildings are “thermally heavy” when occupied (produce much internal heat) and the amount usually dwarfs weather demands (how could you spot that bills?)

2. Cooling is much more expensive than heating when occupied because of the above

3. Almost all heating for thermally heavy buildings occurs at night and weekends (when not occupied) and most of it occurs at night in even thermally light structures (see an opportunity?)

4. You can’t do much to reduce the cooling/heating load but you can dramatically impact “how you satisfy that load” (Why is this?)

141

HVAC Guiding Principles cont.5. A good place to save money is how you supply the

heating and cooling (Variable Air Volume, new chillers, new boilers, chilled water reset, etc.)

6. It is difficult and expensive to significantlychange the building envelop (walls, windows, etc.) in existing buildings

7. The winter sun hits your south wall (friendly) but the summer sun hits your east wall (unfriendly) and your west wall (most unfriendly). That’s a tough one to change though…

8. Most energy that enters a building generates heat in that building (225 Btu/person, electricity for lights and motors, etc.)

142

Thermally Heavy Buildings

• See Guiding Principle One: Most TH buildings produce much internal heat

– Outside conditions not very important– Much more cooling and less heating required

(12 months per year of cooling not unusual)– Economizers often can save much money but

can be difficult to maintain and control on DX units (more later)

– Heating demand occurs at night, etc. when building is not occupied.

143

$$$$

• Thermally Heavy Buildings– Use economizers (or fix)– Night set-back on heating (15 F to 55 F) will save at

least 40% of heating cost in most facilities– Air Handling Units (AHUs) can be throttled down

(VFD) or turned off when building is not occupied – put building “to sleep” at night. Outside air can be throttled down or even off when building is not occupied

– Above is especially true for buildings in temperate areas (most of the US) and for core zones of buildings

144

Thermally Light Buildings

• Different animal…• These buildings produce little internal heat (but all

produce some) – examples: homes, lightly constructed buildings, warehouses, maintenance shops, storage units, etc.

• These buildings are very responsive to outside conditions (cold, you heat; hot, you cool) – Can you spot this on the utility bills?

• Heating and cooling cost close to being equal for mid-Texas

145

$$$$

• Thermally light buildings

– Night set-back still saves about 40% of heating cost for most areas if running at night

– Night set-up saves about 40% of cooling costs if running at night

– “Core zone” management still possible– Outside air management still possible

(economizers)– AHU throttling still possible

146

Humidity Control

• Humidification• Dehumidification

– “Controlling indoor air moisture to below 65 percent relative humidity will limit the probability of supporting mold growth” <http://www.wbaonline.org/everyone/hottopics.asp>

• HVAC systems typically over-cool the air to remove water vapor, and then may have to heat the air back up. This is called reheat, and requires additional energy.

• Some contractors grossly oversize HVAC systems – short cycling

147

$$$$

• Variable Air Volume (VAV) systems can dramatically reduce energy distribution energy costs. (Cube Fan Law)

• In some areas “bucking” (reheat) may be required for humidity control, however be very careful of simultaneous heating and cooling in other areas (e.g. large exposed glass perimeter areas)

• Ask if building uses re-heat, ask if it has been checked recently…

What to Look For with HVAC

• Controls:– Are controls actually functional? (Some may be

disconnected etc.)– Are thermostats calibrated?– Are controls properly programmed?– Are controls properly installed? (near heat

sources, on outside walls, etc.)– If thermostats are air powered – are air lines clean

and dry?– Are air handlers running 24/7? (no control)


• Heating and Cooling Units– Are heating and cooling coils clean?– Is refrigeration system properly charged?– Are temperature set-points set correctly? (chillers

are often set low for “insurance”)– Carefully check temperatures of pipes, do gauges

show fluids moving, pressure?– Look for evidence of bad housekeeping with HVAC

system (insulation falling off, leaks, mess…)


• Distribution System– Are grills clogged and dirty?– Do dampers operate? Does anyone know?– Is ductwork insulated? Are joints sealed?– Are economizers operating? Does anyone know?

(described below)– If no one can answer – time to speak to client’s

HVAC contractor (try to get client to do this…)– Is reheat on all the time?

151

System Improvement Options$$$$

Big Ticket ($) Solutions

• Replace old chiller; possibly downsize oversized chiller based on good load calculation

• Consider multiple chillers; consider installing a small chiller for high cooling demand periods.

• Use VFDs on pumps, cooling towers (air side), and chillers (not all) if applicable.

• Use heat recovery; use ozonation of cooling tower water.

152

Economizer (Free cooling)$$$$

• Use of outside air to provide air conditioning or to ventilate a building when the enthalpy* of the outside air is less than the enthalpy of internal air and there is a desire to cool the building. In dry climates, economizers can work well by measuring dry-bulb temperature, however enthalpy based is preferable, especially in humid climates.

• On smaller rooftop DX units, the economizers are not maintained and are disconnected when they fail (be careful)

* Heat and Humidity

153

Economizer

• Dry-Side economizer

Source: http://www.reznoronline.com/mpd/pub/reznor/products/maps/art/tpc_apguid_economizer.htm

154

$$$ Hours per year that the dry-bulb temperature ranges below 60oF

Dry Bulb Total

Temp. (F) 01-08 09-16 17-24 observations (hrs)

55/59 252 192 226 670

50/54 247 173 215 635

45/49 237 152 190 579

40/44 219 119 146 484Fort Worth, TX Total 2,368Source: Engineering Weather Data

Observation hour group (hrs)

Number of hours are approximate and may vary each year

155

Economizer: Wet Side Economizer

Source: The ASHRAE Handbook: 2000 HVAC systems and Equipment

156

$$$Hours per year for the wet bulb temperature ranges below 50ºF

WB Total

Temp. (F) 01-08 09-16 17-24 observations (hrs)

45/50 220 178 200 598

40/45 194 165 195 554

35/40 210 172 196 578

30/35 416 277 353 1046Fort Worth, TX Total 2,776Source: Engineering Weather Data

Observation hour group (hrs)

Number of hours are approximate and may vary each year

157

Night Setback $$$$

• Night setback: lower thermostat settings for nighttime, weekend and holiday hours (winter). Setup for summer.

• Savings can be huge. In Texas bin data proves about 40% savings for a nightime/weekend set back program. For thermally heavy buildings, savings can be a larger percentage.

• Often this can be done by turning off AHUs especially in core zones; but be very careful of mold and IAQ in general. – (That should generate some discussion)

Chiller Energy Savings$$$$$

• Basically, very large HVAC units for cooling entire buildings or processes

• Chillers usually rated in kW/Ton (cooling) – lower is better

• They can be complex but you should be aware of some opportunities to save energy

• Often oversized – not good• Even if new, there is an opportunity to save 5-

20% in operating costs

159

Chiller Energy Savings$$$$$

• Variable condenser water flow (VFD based onChiller demand)

• Condenser water temperature reset (VFD on cooling tower fan based on basin temperatures – tricky but big potential, about 1-2% savings per degree lowered)

• Chilled water reset (Varies the temperature of the chilled water in a loop such that the water temperature is increased as the cooling requirement for the building decreases)

• Saves about 1-2% for each degree increase in chilled water temperature

• Mostly for simple systems and be careful of humidity control

160

• Heat wheels:– Transfer heat– Transfer

humidity

Air to Air Heat Recovery System

Source: The ASHRAE Handbook: 2000 HVAC systems and Equipment and Airxchange Inc.

161

Cooling Towers

• Natural draft (Large – power plants)• Force draft tower• Induced draft tower (Typical)• Remarkable devices that operate very efficiently

(COP 50 to 70 in some cases – dry weather)• Maintenance intensive so many don’t use (this is

not “set & forget”)• If you find cooling towers and they are well

maintained, they can save lots of energy

Cooling Tower Energy Savings

• Consider replacing old-dirty towers, newer towers are up to 10 times the efficiency of >10 year old units

• Use towers to overcool chiller condenser water for chiller energy savings

• Use VFDs on fans, basin water temperature is signal to drive

• Use towers for “Free Cooling” in the right conditions (use enthalpy control)

Process Heating and Cooling

• Process heating is vital to nearly all manufacturing processes, supplying heat needed to produce basic materials and commodities. According to the U.S. Department of Energy (DOE), heating processes consume about 5.2 quadrillion Btu of energy annually, which accounts for nearly 17 percent of all industrial energy use.

• Not the same as HVAC

(http://www.mntap.umn.edu/energy/heat.htm)

Industrial Processes

Process Heat Examples

• Heat treat furnaces.• Food cooking.• Drying ovens.• Steam and heat exchanger systems.• Chemical and water heated baths.• Heated vessels of material.• Other…

Energy Saving Areas for Process Heating

• Reduce or eliminate openings in the furnaces or ovens to reduce radiation heat losses

• Repair cracks and losses in the insulation of furnace or oven walls, doors, etc.

• Use infrared heat thermometers or IR cameras to detect heat loss

• Repair doors that don’t seal well on closing

Process Heating SurveyConduct Process Heating Score Card:• Have you conducted a detail energy assessment for your heating equipment using tools such as

Process Heating Survey and Assessment Tool (PHAST) to identify energy saving opportunities? • Do you measure oxygen (O2) and Carbon Monoxide CO or combustible in flue gases and "tune"

the burners periodically to maintain low values for O2 and combustibles in the furnace flue gases?

• Have you sealed openings in furnaces and repaired cracks, and damaged insulation in furnace walls, doors etc.?

• Do you regularly clean heat transfer surfaces to avoid build up of soot, scale or other material? • Do you have a program for calibration/adjustment of sensors (i.e. thermocouples), controllers,

valve operators etc.? • Do you operate the furnace at or close to design load by proper furnace scheduling and loading,

and avoid delays, waits between production? • Do you maintain proper (balanced or slightly positive) pressure in furnaces to avoid air leakage

in the furnace? • Do you use any type of heat recovery system (i.e. recuperator, regenerator, water or heating

etc.) to recover heat form the furnaces flue gases?

Process Heating Survey• Please answer either a or b.

– a. Are you using a heat recovery method to use heat of flue gases from furnace or air preheater to heat charge material, fixtures etc.?

– b. Are you using a heat recovery method to use heat of flue gases from furnace or air preheater for lower temperature processes such as steam generation, water heating or air heating for the plant or other application?.

• Do you use design of fixtures, trays and other material handling system components with minimum weight and proper material?

• Do you use proper insulation for (or minimize use of) water or air cooled parts such as rolls, load supports etc. used in furnaces?

• Are you using the most cost effective source of heat for processes where it is possible use alternate energy sources (i.e. steam vs. electricity vs. fuel firing) where applicable?

• Do your heating equipment and other heated parts use cost effective type and thickness of insulation?

Energy Saving Areas for Process Heating: Insulation Levels and Condition

Energy Saving Areas for Process Heating: Flue Gas Heat Recovery (Combustion Air Preheat)

Energy Saving Areas for Process Heating: Waste Heat “Cascading”

• Cascade waste heat. The heat from exhaust gases can be used as a source of heat for lower temperature process heating equipment.

• For example, waste heat boilers can use the thermal energy from flue gases to generate hot water or steam. Waste heat from heat treating furnaces can also be used in aging or paint-drying ovens.

• To maximize benefits of the heat recovery, the downstream heating equipment must be in operation while the furnace (heat source) is operating

Energy Saving Areas for Process Heating: Fuel Switching and Innovative Technologies

• Example: Electrical induction heating versus large natural gas furnace for metal treatment.

Waste Heat Recovery

Energy in streams of air, exhaust gases, liquids leaving the boundaries of a plant or building.

Quantity of waste heat:

H [Btu/hr] = m [lb/hr] x Δh [Btu/lb]

m = density [lb/ft3] x volumetric flow [ft3/h]

Waste Heat Recovery


Temp. Range T, ºC Source

High 600 ≤ T ≤ 1,650 Exhausts from furnaces, kilns, and incinerators

Medium 200 ≤ T ≤ 600 Exhausts from engines, boilers, and furnaces

Low 25 ≤ T ≤ 200 Cooling water, process liquids

Quality of waste heat:

Waste Heat Recovery (cont.)

Other concerns

How close is location where heat is needed?

Is the waste heat available when needed?

Is the waste heat compatible with a heat exchangers?

Several applications

1. Heat pump 2. Recuperator

3. Economizers 4. Blowdown recovery

5. Desuperheat 6. Condensing heat recovery

7. Rotary wheel

Sources: Energy Management Handbook, 4th Ed., Turner, W.C., 2001, The Fairmont Press, GA, p. 205 Alfa Laval @ http://www.alfalaval.com

Heat Exchangers

Shell & Tube Plate

Waste Heat Recovery (cont.)

Energy Saving Areas for Process Heating: Heat Exchanger Condition

Thttp://www.energystar.gov/ia/business/industry/clnwtrsd.pdf#search=%22fire%20tube%20scale%22

Process Cooling Systems

• We sometimes find situations where the heated “product/process” must be cooled to some point before the next process step can take place (examples include injection molding, extrusion, …).

• Other times we see “product” that requires a cooling process step and then maybe a heating process step, and then maybe cooling again (examples include food processes, …).

• In these situations, the cooling cycle generally drives the cycle time for production. Depending on mass and temperatures, we see a variety of approaches. We may see small local cooling systems or large centralized cooling systems.

Process Cooling System Components – Look Familiar?

• Cooling towers. • Chillers.• Delivery systems.• Controls.

Diagram of Typical Chiller

High Pressure SideExpansionValve

Low Pressure Side

Compressor

Motor

Condenser

Evaporator

Condenser Water

Chilled Water

85°F 95°F

45°F 55°F

“Free” Cooling and Rules of Thumb - Again

• Chillers demand about 1 Kw (input) for every ton demand (output).

• Economizers -- Use of “outside air” to provide cooling (when conditions permit, e.g. cool dry air, relative to cooling demands).

• Controls that sense load (chilled water reset) -- temperature of the chilled water in a loop such that the water temperature is increased as the cooling requirement for the process decreases.

• Saves about 1.5% for each degree increase in chilled water temperature.

End Day One

Web Sites (U.S. DoE)

http://www1.eere.energy.gov/industry/bestpractices/

http://www1.eere.energy.gov/industry/bestpractices/technical.html

http://www1.eere.energy.gov/industry/bestpractices/iacs.htmlIAC web site

Technical publications web site

U.S. DoE Bestpractices web site

http://www.dsireusa.org/

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Documents

energy efficiency

energy consumption

energy cost

energy audit workshop

customer slide

basic energy auditing

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