chiller plant ee webcast_1113

8/20/2019 Chiller Plant EE Webcast_1113

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©© Hudson TechnologiesHudson Technologies1

Introduction to Improving EnergyEfficiency in Chiller Systems

Riyaz Papar, PE, CEMDirector, Global Energy Services

Hudson Technologies Company

[email protected]

November 2013


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Acknowledgments

Texas Industries of the Future (TXIOF)

Texas State Energy Conservation Office (SECO)

Energy Industries in Ohio

Joe Longo & Derrick Shoemake, HudsonTechnologies


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Webinar Agenda

The Systems Approach

Fundamentals of Refrigeration

Chiller Plant Actual Operating Performance

Predictive and Preventive MaintenanceBestPractices

Energy Conservation Measures (ECMs)

Conclusions


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Chiller System Energy Cost?Chiller System Energy Cost?

1,000 Refrigeration Tons chiller plant load

Chiller System performance = 0.75 kW/ton

Bundled power cost = $0.085/kWh

-

100,000

200,000

300,000

400,000

500,000

600,000

4 months 6-8 months All year round

Operating hours

O p e r a t i n g C o s t ( $ )


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Establish current system conditions,

operating parameters, and system energy use

Investigate how the total system presentlyoperates

Identify potential areas where system

operation can be improved Analyze the impacts of potential

improvements to the plant system

Implement system improvements that meet

plant operational and financial criteria

Continue to monitor overall system

performance


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A Chilled Water Plant Systems Approach


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Energy Reliability

Maintenance Productivity

Quality

Cost avoidance

Emissions reductions

Main Driving Force for Change


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Fundamentals of

Refrigeration


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The Refrigeration Cycle

0 25 50 75 100 125 150

101

102

103

h [Btu/lbm]

P

[ p s i a ]

105°F

40°F

0.2 0.40.6 0.8

R134a

Compression

Condensation / SubCooling

Ev aporation (Boili ng)

Expansion

State Point


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Single Stage Chiller System

Condenser

Compressor

Evaporator

HGBP

HGBP

Cooling Water

Chilled Water

(Hot Gas ByPass)


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A Centrifugal Chiller

Evaporator (Chiller Barrel)

Condenser

Compressor

A Water-Cooled Chiller System


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Two Stage Chiller System

Condenser

Compressor

Evaporator

HGBP

HGBP

Cooling Water

Chilled Water

Economizer

(Hot Gas ByPass)


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LiBr-Water Absorption Chillers


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The Air, Water and Refrigerant CycleThe Air, Water and Refrigerant Cycle



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Chiller Plant - Actual

Operating Performance


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Chiller Performance Metrics

Most standard rating in the US - kW/RT(hp/RT)

Amount of compressor power (kW orhp) required to produce 1 RT of coolingor refrigeration

)(

)(/

RT Load Cooling

kW Power Compressor RT kW


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Chiller ID: Chiller #6 Chiller Manufacturer: ZZZZZZZ

Year Commissioned: 1990 Chiller Type: Constant Speed Centrifugal

Model Number: XXXXXXXXXX Serial Number: AAAAAAAA

Refrigerant Type: R-134a Capacity (Tonnage): 2,000

Efficiency (kW/Ton): 0.625 IPLV / NPLV: .541

Full Load Amps (FLA): 198 Volts: 4160

Evaporator Entering Water Temperature: 54.37°F Evaporator Leaving Water Temperature: 44°F

Condenser Entering Water Temperature: 85°F Condenser Leaving Water Temperature: 94.4°F

Evaporator Delta Temperature: 10.37°F Condenser Delta Temperature: 9.4°F

Evaporator GPM: 4,627 Condenser GPM: 6,000

Evaporator Pressure Drop (psig): 9.9 Condenser Pressure Drop (psig): 8.1

Chiller Full Load Design Specifications

Obtained from the Chiller Manufacturer


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Overall Chiller Plant Performance

Information required

Total tonnage

Total kW Compressor Power

Pumping Power

Cooling Tower Fan Power

Other (as defined in the scope)

m

n

TonsChiller

kW

ePerformancPlant


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Chiller Plant Efficiency Metrics

Overall chiller plant performance

Total tonnage

Total kW (including chillers and auxiliaries)

Individual chiller efficiency Chiller tonnage

Compressor kW

Individual Chiller Lift

Lift is defined as the difference between the refrigerantsaturated condensing and evaporating temperatures

Individual compressor isentropic efficiency

Suction and discharge temperatures

Suction and discharge pressures Individual heat exchanger effectiveness

Approach temperatures

T on chilled water and cooling tower water


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Predictive & Preventive

MaintenanceBestPractices


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First Things FirstFirst Things First –– Fluid ManagementFluid Management

Understanding “Cause” and “Effect” is veryimportant for Root Cause Analysis

This enhances system reliability and reducesunplanned shutdown

Significant savings in Maintenance costs

Most Maintenance BestPractices are testing-

based Refrigerant, Oil and Water Testing

Rotating equipment monitoring

Vibration analysis

Eddy-current testing

In chiller systems, contaminants affectefficiency & capacity

Chemistry Based Solutions


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Blood ChemistryBlood Chemistry


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Chiller ChemistryChiller Chemistry


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Refrigerant Analysis CriteriaRefrigerant Analysis Criteria

Moisture

Oil

Particulate Chlorides

Acid

Purity

Non-Condensables

Other Contaminants


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Nonferrous cutting wearNonferrous cutting wear Severe sliding wearSevere sliding wear

Copper alloyCopper alloy

sliding wearsliding wear

Nonferrous cutting wearNonferrous cutting wear

Ferrography

Oil Analysis


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Water Testing and Analysis

Cooling Tower Water testing and analysis

Open loop – evaporation of water

Control of corrosion, scale and biological activity

Material of construction plays a very important role Testing conducted for pH, TDS, Conductivity, Hardness,

Alkalinity, Chlorides, Silica, Bacteria, etc.

Chilled Water testing and analysis Closed loop – generally less issues

Lower temperatures

Working with a water chemist / treatmentcompany

Periodic testing program


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Energy Conservation

Measures (ECMs)


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3 Methods of Maximizing Chiller Plant Efficiency

Preventive Identify problems before they become expensive

(cost avoidance)

Maintain optimum chiller plant efficiency Restorative

Identify heat transfer problems, i.e., off-designwater flow, fouling or scaling, etc.

Remove non-condensable gases

Maintain proper refrigerant levels

Opportunity Identify optimal chilled water set points

Proper chiller sequencing and load balancing Proper tower basin water management

Peak demand management

Condition-based maintenance versus scheduledpreventive maintenance


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List of ECMs

Implement ECWT management

Optimize settings for ChWST

Eliminate all refrigerant leaks

Maintain design water flow rates

in evaporator / condenser Eliminate refrigerant stacking

Remove non-condensable gases

and moisture

Reclaim refrigerant

N o C o s t / L o w C o s t

E

C M s


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List of ECMs (continued)

Clean fouled and scaled heatexchangers

Sequence multiple chillers to optimize

efficiency Maintain compressor isentropic

efficiency

Improve drive efficiency

Investigate application of variablefrequency drives

Undertake peak load managementstrategy

Install water-side economizers

M e d i u

m C o s t

E C

M s

H i g h

e r C o s t

E C M s


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Implement ECWT Management

ECWT – Entering Cooling Water Temperature

Approach

The approach is the difference in temperature betweenthe cooled-water temperature and the entering-air wetbulb temperature

Since the cooling towers are based on the principles of

evaporative cooling, the maximum cooling towerefficiency depends on the wet bulb temperature of air

Wet Bulb

Wet bulb temperature is the lowest temperature thatcan be reached by the evaporation of water only

It is determined by the atmospheric pressure, ambienttemperature and the relative humidity


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Concept of Lift


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80°F ECWT drops to 70°F ECWT

kW/ton drops from 0.7 to 0.47 (33% improvement)

Implement ECWT Management


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Optimize Settings for ChWST

ChWST – Chilled Water Supply Temperature

Approach / RAT

The approach (RAT) is the difference in temperaturebetween the chilled-water supply temperature and therefrigerant saturated temperature in the evaporator

It provides the driving force to transfer the heat from

the water to the refrigerant

Load control

Cooling required is controlled by bypassing chilledwater flow

Alternate methodology – variable pumping

Primary

Secondary


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Optimize Settings for ChWST

0.3

0.325

0.35

0.375

0.4

0.425

0.45

0.475

41 42 43 44 45 46 47

CWST (°F)

C h i l l e r P e r f o r m a n c e ( k W

/ R T )


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Clean Fouled and Scaled Evaporator

Fouling in the evaporator / cooler

Refrigerant-side

Water-side

Refrigerant-side fouling – Excess Oil

Refrigerant-side fouling – Water

Water-side fouling

High makeup (leaks) in the closed loop system

Iron fouling from corrosion, microbiological growth andscale due to insufficient chemical protection


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Fouled/Scaled EvaporatorFouled/Scaled Evaporator

Iron Oxide Scaled

Condition

After tube brushing


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Fouled/Scaled CondenserFouled/Scaled Condenser

March

July

Sept


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Reclaim Refrigerant

Over time and operations, the refrigerant in thechiller gets contaminated and results in Fouling of heat exchangers

Reductions in heat transfer coefficients The process of recovering the refrigerant and

bringing it back to AHRI-700 specificationstandard is known as “Reclamation”

Reclaiming a refrigerant improves overalloperating performance and in most casesincreases chiller tonnage (capacity)

Periodic sampling and testing of refrigerants in

chiller systems is key to ensuring that the chillerchemistry is well maintained Analogous to maintaining water chemistry in boilers


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Reclaim Refrigerant

Presence of Oil

in refrigerant

Particulate in

refrigerant

Moisture in

refrigerant

l i f i


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SUMMARY of RESULTS & COST SAVINGS

Tons = 1,502 [RT]

com pHP = 1,219 [HP]

SteamRate = 12.02 [lb/hr-HP]

NC% = 0.0 [%] Superheat Capacity Penalties

Total System

Cost ($) NC Penalty ($)

678,871 0

Evaporator Condenser System

Evaporator

%Capacity Lo ss (RT)

2.8 0.1

2.6 2.3

13.1 0.0 13.1

BalanceSystem = 0.0 [%]

BalanceEvap = 0.0 [%]

BalanceSubCooler = ???? [%]

SteamCos t = 14.48 [$/1000lb]

Hours = 4,000 [Hr]

SUMMARY of RESULTS & COST SAVINGSTotal System

2.3

2.6

Component Balances

LFC = 0.80 [kW/ton]

2,002 [RT]

2,360 [HP]

12.03 [lb/hr-HP]

Annual Energy Cost s

RefrigerantDesign F/L

Design:

Currently Used:

R134a

R134a

Potential Savings Opportun ities

Pressure Ratio (current):

New Ratio

Savin gs (%)

HPTon = 0.81 [BHP/RT] 1.18 [BHP/RT]

1,502 [RT]

1,503 [HP]

Desig n P/L

1.001 [HP/Ton]

Reclaim Refrigerant

Impact of Oil, Particulate

& Moisture in refrigerant

on energy efficiency &costs

I m

p a c t o n C a p a c i t y

Eli i t R f i t St ki


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Eliminate Refrigerant Stacking

Refrigerant stacking impacts heat transfer efficiencyin both the evaporator and condenser - higherkW/Ton and energy costs

Leads to reduced compressor capacity

Chiller surging or stalling

Shut down on low refrigerant temperature

(pressure)

R f i t St ki


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Refrigerant Stacking

RaiseECWT

Sequence Multiple Chillers to Optimize Efficiency


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Sequence Multiple Chillers to Optimize Efficiency

All chillers will have an optimal operation range(best efficiency point)

When multiple chillers are operating, the overallplant’s composite operating curve maybe verydifferent from the individual chiller’s curve

It is important to know how each of the chillersoperate under different load conditions

Pick the best chiller operating combination forthe current operating conditions – DynamicOptimization problem (NOT Easy)

In estigate Application of Va iable


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Investigate Application of Variable

Frequency Drives (VFD) Replacing old chillers with newer energy efficient systems –

most new packaged chillers will come with a VFD option

VFDs take advantage of lower ambient temperatures (lowerlift) and correspondingly lower cooling loads (lowerrefrigerant flow rates)

VFD pumps and fans can play a very important role inreducing total system energy consumption

VFD efficiency is extremely high (99%) and moreimportantly, it offers a benefit on the drive side by providing

Soft start capability

Power factor correction

Comparison of Constant Speed & VFD


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Comparison of Constant Speed & VFDChiller Performance

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

20 30 40 50 60 70 80 90 100

Cooling Load (%)

C h i l l e r P e r f

o r m a n c e ( k W / R

T )

Constant SpeedVariable Frequency

Install Water side Economizers


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Install Water-side Economizers

This ECM is applicable only in certaingeographical areas but can have a hugeimpact on energy savings

Installing a water-side economizer allows for “free cooling” during times of the year when

the outdoor ambient conditions allow forvery low wet-bulb temperatures

The cooling tower water provides all (or

some portion) of the chilled water plant loadand reduces the amount of chillers required

Undertake a Peak Load Management Strategy


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Undertake a Peak Load Management Strategy

Peak demand charges can become excessivedepending on chiller plant management andoperational strategy

There are 3 ways to manage peak demandregarding chillers

Thermal energy storage Optimize chiller efficiency to lower kW usage of running

chillers

Take a chiller off-line


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Conclusions

Next Steps


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Next Steps

Develop a simple schematic of your Chiller Plant /Refrigeration system and define the boundaries

Use a systems approach to complete an initial assessment to

understand operations and load profile

Undertake a simple gap analysis to identify any potentialimprovement opportunities

Evaluate each ECM and prioritize based on quantified savingsopportunities

Put a program in place to ensure that there is proper

Predictive and Preventive Maintenance BestPractices

Implement an effective Chiller Plant Performance Monitoring,Diagnostics and Optimization system

1-Day Training Workshop


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1 Day Training Workshop

Introduction to Energy Efficiency inChiller Plant Systems

December 17, 20138 am – 4 pm

Houston Business RoundTable5213 Center StreetPasadena, TX 77505

Facilitator: Riyaz Papar, PE, CEMHudson Technologies Co.

Registration Information:

Kathey FerlandTexas Industries of [email protected]

http://TexasIOF.ceer.utexas.edu

Contact Information


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Contact Information

Technical Information

Riyaz Papar, PE, CEM

Hudson Technologies Co.

[email protected]://www.hudsontech.com

Program Information

Kathey Ferland

Texas Industries of Future

[email protected]://TexasIOF.ceer.utexas.edu

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