soft drink manufacturing paper

8/12/2019 Soft Drink Manufacturing Paper

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Mixing

Carbo Cooler

(Ammonia Cooled)

Flavor Concentrates

Water & HFCS

Packaging

Filler

Containers are

Warmed

Palletizing

Shipping

CO2

Figure 1 A Typical Process Flow Diagram ofa Soft Drink Bottling Facility

Soft drink manufacturing facilities havesignificant electric and natural gas (or otherfossil fuels) usage. Major energy users include,

A significant amount of lighting energy,mostly for warehouse storage spaces.

Various blowers, and pumps for pumping

water and product.Significant level of refrigeration (usuallyammonia) for cooling the product forcarbonization

Various hydraulic pumps for palletizers

Significant level of compressed air forblowing, drying, pneumatics, etc.

Significant level of heating (usually fromnatural gas) for warming the containers toavoid condensation.

Shrink wrap tunnels when plasticwrapping is utilized

Figure 2 shows a typical electrical energydistribution pie chart of a soft drink plant.

Miscellaneous

7% Lighting

14%

Refrigeration27%

Conveyors

3%Air

Compression

17%

Water Plant

5%

Hydraulic

Pumps

2%

Fluid

Pumps

10%

Blowers3%Other Motors

12%

Figure 2 Annual Electrical Energy Pie Chartfor a Large Soft Drink ManufacturingPlant

Major Opportunities for Energy Efficiency

Our experience in detailed audits of soft drinkmanufacturing facilities has resulted inidentification of numerous energy saving

opportunities. Summaries of major energyefficiency opportunities are briefly describedbelow.

Containers are then warmed to above the

dew point of the ambient air to avoidcondensation in the packaging. Warmingusually happens through spraying orimmersion in hot water bath at atemperature of about 130- 140 F. Production Process

Cooling the Product to Optimum LevelContainers are then packaged, palletized,stored, and shipped. The product is usually cooled to above freezing

(e.g. 36 F) for dissolving carbon dioxide under

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Other sources of lighting energy savingsinclude:

high pressure. The desired absorbed level ofcarbon dioxide depends on the carbonationpressure and temperature. Optimizing the carbo-cooler temperature (e.g. raising it from 34 F to40 F ) will result in significant savings inrefrigeration energy. Additionally increasing the

temperature in carbo-cooler will result in heatingenergy saving in the warmer. An importantpoint, raising the temperature beyond anoptimum level can result in foaming which isundesirable.

Replacing other types of HID lamps (e.g.mercury vapor) with high pressure sodiumlamps

Installation of skylights, which are

particularly attractive in mild climatessuch as California.

Replacing T-12 lamps with magneticballast with T-8 or T-5 lamps withelectronic ballast

Use of light sensors in the areas thatreceive enough natural lightingHeating the Containers to Optimum Level

After the containers (cans or bottles) are filled,they are usually heated to 20 to 30 F above thedew point of the ambient air, in order to raise thedrink temperature to prevent condensate fromcollecting on the containers when they are

stored. The container exit temperature is 20 to30 F above the dew point of the ambient air,which may be excessive depending on the lengthof time the container spends in the warmer. Asimple heat transfer model (see for exampleHolman, 1990) can show the temperaturedistribution inside the container when it exits thewarmer, and as a result the container surfacetemperature as a function of time. The surfacetemperature at equilibrium should be greater thatthe dew point temperature of the ambient air.For most applications heating the containers to

10 F above ambient will be sufficient.Measurement of the ambient dew pointtemperature and controlling the warmertemperature can result in significant heatingenergy savings.

Use of occupancy sensors in areas that areinfrequently occupied

HVAC SystemAlthough HVAC is often not a significant partof energy consumption in a soft drinkmanufacturing plants, it can be a major energyuser in the administration part of the facilities.Major sources of energy savings in HVACsystems are:

Controlling the HVAC system to heat andcool when needed by programmablethermostat or better with an energymanagement system.

Proper zoning the HVAC air supply andreturn.

Use of high EER package units with theminimum requirements of ASHRAEStandard 90.1.

Use of variable frequency drive (VFD)controllers on air handlers in place ofdampers

Buildings and groundsRefrigeration System

High Efficiency LightingIn production of carbonated soft drinks, therefrigeration system and its accessories such ascooling towers/evaporative coolers use asignificant amount of energy. The refrigerationsystems mostly use ammonia as the refrigerant.In the plants we have audited, between 25% to35% of plants electrical energy is used forrefrigeration. Significant levels of energysavings can be achieved through:

Soft drink manufacturers usually have very largehigh bay warehouses that are usually illuminatedwith high intensity discharge (HID) lamps, suchas metal halide and high-pressure sodium. These

types of lamps can not be turned on and off ondemand, but they can be dimmed on demand,with an energy saving of 50 to 60%. Majorsavings can be attained by installing bi-levellighting control systems that are activated byoccupancy sensors upon detection of a person ora forklift in an aisle and shifting to fullbrightness.

Sequencing the compressors

Use of high efficiency refrigerationcompressors with VFD controllers

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Heat recovery from the ammonia vapor atthe compressor exit to pre-heat the boilerfeed water. This measure also results inenergy savings in the cooling tower/evaporative cooler system because itreduces the heat load.

Use of VFD on cooling tower fans, usingsump temperature for feedback.

Use of VFD on cooling tower supplywater pumps, using return watertemperature or chiller condenser pressurefor feedback.

Modification of refrigeration parameters(e.g. suction pressure, head pressure) toconform to process requirements

Heating System

Heating is needed to warm the containers before

they are packaged in order to preventcondensation on container surface. Hot water forheating the containers is usually heated to about130-140 F.

Two types of heating systems are used for thispurpose, steam from steam boiler or hot waterfrom hot water boiler that in turn heats thewarming water through heat exchangers. Use ofhot water boilers is much more efficient becausesmall hot water boilers can be installed near thepoints of application (rather than installation of

steam boilers in a more remote area). Installationof a central hot water boiler is also an option.

Main advantages using local hot water boilersare:

Use of lengthy piping can be avoided

Redundancy is built into the system, dueto multiple hot water boilers rather thanone or two large steam boilers

Modern hot water boilers are much moreefficient than steam boilers.

The issue of maintaining steam traps aretotally avoided

Compressed Air Systems

As Figure 2 shows, air compression can be asignificant portion of the electrical energyconsumption in these facilities. Major sources ofair consumption include air jets used fordirecting cans and bottles along the conveyor

lines, air jets for drying the containers aftervarious stages of washing, air leaks andpneumatic actuators.

Significant saving can be achieved by usingblowers in place of air jets for drying

applications, and wherever possible for movingthe containers. Table 1 compares the powerconsumption of a compressor versus blowers ofvarious pressures. For majority of dryingapplications and some displacing applications,blowers can easily replace the compressed air.Refer to Compressed Air Challenge, 1998 forother energy efficiency measures for compressedair systems.

Combined Heat and Power

Carbonated soft drink facilities are ideal cases

where distributed generation in the form ofcombine heat and power (CHP, the same ascogeneration) can be used. This is due to the factthat both heating and electrical energy arerequired simultaneously. In the plants we haveaudited, the ratio of electrical energy usage toheating energy usage have been 70% to 83%,which are in the bulk part range of electrical tothermal ratio of natural gas reciprocating enginecogeneration systems. Natural gas fueledreciprocating engines are suitable for this type offacility because,

Low pressure steam or hot waterproduction capability of these engines

Suitability of the size of these engines tocarbonated soft drink facilities, a fewhundred kW to a few MW.

Air pollution control technology is readilyavailable for these engines even in astringent air pollution control environmentsuch as South Coast Air QualityManagement District in California.

Several percentage points of higherefficiency compared to gas turbines of the

similar capacity.

Other Energy Efficiency Measures

The other energy efficiency measures we havebeen able to identify in carbonated soft drinkmanufacturing facilities are:

Insulation of hot surfaces includingcondensate return lines.

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Avoid using shrink-wrap tunnels byconverting the line to carton packaging ifacceptable to the market. Shrink-wraptunnels are significant energy users inthese facilities.

Interlocking blower or drying air jets to

the flow of containers, i.e. with productionInstallation of high efficiency motors

For details on some other measures inmanufacturing facilities refer to Ganji (1999).

Some Specific Case

In order to indicate the level of savings in thesetypes of facilities one comprehensive case studyand the case of CHP recommendation arepresented here. Table 2 shows the summary ofsavings and costs for a plant in California. Total

recommended measures amount to over 20%cost savings for the plant.

In another plant in addition to other measures,we recommended the installation of a CHP(cogeneration) system. Table 3 shows the resultsof this evaluation for an approximate averageelectrical usage cost of $0.057/kWh, averagedemand cost of $13.5/kW and natural gas cost of$0.415/therm.

ConclusionsSignificant opportunities exist for energy andcost savings in carbonated soft drinkmanufacturing facilities. Major savingsidentified are in process modification, lighting,ammonia refrigeration, compressed air and mostimportantly combined heat and power. Althougheach facility has its own unique features, themeasures identified can have applications inmost plants.

References

ANSI/ASHRAE/IESNA Standard 90.1-1999,Energy Standard for Buildings Except Low-Rise Residential Buildings, American Society

of heating, Refrigerating and Air-ConditioningEngineers, 1999.

Compressed Air Challenge, ImprovingCompressed Air System Performance, USDepartment of Energy, Motor ChallengeProgram, 1998., also www.knowpressure .com.

Fuller, A. H. , Soft Drink Industry, Vol. 6,Carbonation, Jusfrute, Ltd., 1973.

Ganji, A. R., Conducting an Energy Audit, How

to Cut Costs in the Second Largest Energy-UsingIndustry, Chemical Processing, pp64-70, Sept.1999.

Holman, J. P. Heat Transfer, 7thEdition,McGraw Hill 1990.

Acknowledgment

The authors would like to thank the SouthernCalifornia Gas Company, particularly Mr. TonyHesam for providing BASE Energy, Inc. with

the opportunity to audit numerousmanufacturing facilities in the past few years.All authors have also greatly benefited from theexperience at San Francisco State UniversityIndustrial Assessment Center.

Table 1 Power Difference of Production of Compressed Air and Blower Air

Compressor Blower

Pressure (psig) 100 3 6 9 12 15

HP/SCFM 0.238 0.0233 0.0439 0.0624 0.0794 0.0950


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TABLE 2 SUMMARY OF SAVINGS AND COSTS

EEO

No. Description

Potential

Energy

Conserved

Demand

Savings

(kW)

Potential

Savings

($/yr)

Resource

ConservedImplem.

Cost

($)

Simple

Payback

(years)

No or Low Term Measures1 Control the Temperature of theFilled Cans

63,108therms/yr

N/A 27,004 NaturalGas

0 immediate

2 Raise the Temperature of theCarbo Coolers

351,404kWh/yr

84.47 51,916 Electricity 0 immediate

3 Turn-Off the Two SuctionBlowers on the Washer of Line#1

50,332kWh/yr

11.52 7,343 Electricity 0 immediate

4 Tune and Adjust the Air-to-Fuel Ratio of the SteamBoilers

15,759therms/yr


500 0.1

5 Replace the Standard V-Belts

with Cog-Type V-Belts

82,397

kWh/yr

18.82 12,024 Electricity 2,463 0.2

6 Use a Smaller Air Compressorfor Weekend Operations

48,180kWh/yr

0.00 5,256 Electricity 2,000 0.4

7 Insulate the Hot Surfaces in theBoiler Area and Line #2 HeatExchanger

9,515therms/yr


2,490 0.5

8 Use a Blower to Produce Airfor the Air Jets

16,448kWh/yr

3.95 2,429 Electricity 1,500 0.6

9 Install Light Sensors on Lampsin the Loading Dock

5,192kWh/yr

1.25 767 Electricity 480 0.6

10 Install Higher EfficiencyMotors *

44,071kWh/yr

6.43 6,360 Electricity 4,740 0.7

11 Recover Waste Heat from theAmmonia RefrigerationSystem

29,234kWh/yr82,900

therms/yr

0.00 44,639 Electricity

NaturalGas

39,050 0.9

Short Term Measures

12 Install Bi-Level LightingControl on the HID Lights inthe Warehouses

169,318kWh/yr

24.67 22,437 Electricity 49,500 2.2

13 Install High Efficiency T8Fluorescent Lighting

67,058kWh/yr

17.18 10,077 Electricity 25,950 2.6

Total

Energy(Electricity) 863,634

kWh/yr

Savings (Natural Gas) 171,282therms/yr

Total Demand Savings 168.3 kW

Total Cost Savings $202,888/yr

Total Implementation Cost $128,673

Simple Payback Period 0.6years

* Two year figures. See EEO for details.


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TABLE 3 SUMMARY OF SAVINGS AND COSTS

EEO

No. Description

Potential

Energy

Conserved

Demand

Savings

(kW)

Potential

Savings

($/yr)

Resource

ConservedImplem.

Cost

($)

Simple

Payback

(years)

1 Install a Combined Heat andPower System 4,632,900kWh/yr-254,947

Therms/yr

900 245,408 Electricity

NaturalGas

920,986 3.8

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