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ABSORPTION CHILLERby;Juzaidi, Zaini & Shahirul27 & 28 September 2011PJ2 MSB Training Center1Training Objective2Participants are able to know the history and development of chiller.

Participants are able to explain type of major component use.

Participants are able to explain type of chiller control use.

Participants are able to Calculate Energy in absorption cycle.

Participants are able to use the knowledge to operate chiller safely and efficiently.

Participants are able to use the knowledge for maintaining chiller.

Participants are able to use the knowledge to carry out initial troubleshooting or mis-operation.3Topics to cover4HistoryRefrigeration start with ice harvesting First refrigeration systemThe development

Unit of Refrigeration

3. Absorption Principles Absorption Chiller in GDC.Major Component Absorption cycle.Lithium Bromide & Refrigerant CharacteristicCrystallization Curve54. Chiller safetyGeneral / common safety in absorption chillersCrystallization protectionFreeze protectionSafety devices

5. Maintenance, Inspection and Trouble ShootingPreventive MaintenanceTrouble Shooting Chiller/HTG, Gas & Oil BurnerOverhaul & Inspection66. Chiller PerformanceEnergy CalculationC.O.P

7. Auxiliary Equipment Common auxiliary system in absorption chillers Refrigerant pump Solution pump Purging system

8. Chiller PipingWater system (CHW, CW)Steam systemFuel systemExhaust system 71.0 History8Refrigeration start by the use of ice to refrigerate and preserve food during prehistoric times.Chinese, Hebrews, Greek, Roman, Persian ice and snow were stored in caves or dugouts lined with straw or other insulating materials.In the 16th century, the discovery of chemical refrigerant was one of the first steps toward artificial means of refrigeration. Sodium nitrate or potassium nitrate, when added to water, lowered the water temperature and created a sort of refrigeration bath for cooling substances. In Italy, such a solution was used to chill wine and cakes.During the first half of the 19th century, ice harvesting became big business in America.

Ice Harvesting.First Refrigeration System

1756 - First known method of artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in Scotland. Cullen used a pump to create a partial vacuum over a container of diethyl ether, which then boiled, absorbing heat from the surrounding air. The experiment even created a small amount of ice, but had no practical application at that time.

1758 Benjamin Franklin & John Hadley, Chemistry professor at Cambridge University conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. They confirmed that evaporation of highly volatile liquids such as alcohol and ether could be used to drive down the temperature of an object past the freezing point of water.

First Refrigeration System1805 American inventor Oliver Evans designed vapor compression refrigeration cycle rather than chemical solutions or volatile liquids such as ethyl ether but never built a refrigeration system

1820 British scientist, Michael Faraday liquefied ammonia and other gases by using high pressures and low temperatures.1834 Jacob Perkins, an American living in Great Britain obtained the first patent for a vapor-compression refrigeration system. Built a prototype system and actually work although it did not succeed commercially.1842 American physician, John Gorrie designed the first system for refrigerating water to produce ice. It can cooled the air to a temperature low enough to freeze water and produce ice but the system is a commercial failure.

1848 Alexander Twining began experimenting vapor-compression refrigeration and obtain patents in 1850 and 1853. Successful and credited with having initial commercial refrigeration in US 1856.1851 In Australia, James Harrison began operation of a mechanical ice-making machine in 1851. His first commercial ice making machine followed in 1854 and patent for an ether liquid-vapor compression refrigeration system was granted in 1855. Introduce commercial vapor compression refrigerant to breweries and meat packing housing. 1861 dozen of this system in operation.1882 The first commercial success on refrigerated shipping when William Soltau Davidson fitted a compression refrigeration unit to the New Zealand vessel/ship Dunedin leading to a meat and dairy boom industry in Australasia & South America.

The Development1859 The first gas absorption refrigeration system using gaseous ammonia dissolved in water (referred to as aqua ammonia) developed by Ferdinand Carre and patented in 1860. Due to the toxicity of Ammonia, such systems were not developed for use in homes but were used to manufacture ice for sale.

1895 German engineer Carl von Linde set up a large scale for the production of liquid air and eventually liquid oxygen for use in safe household refrigerators.

1920s Refrigerant Freon is a trademark of the DuPont Corporation and refers to CFC(chlorofluorocarbon) and later HCFC and HFC is developed.

In the early years of twentieth century, the vapor absorption cycle using water-ammonia system was popular and widely used.

After the development of the vapor compression cycle, the vapor absorption cycle lost much of its importance because of its low COP (about one fifth of that of the vapor compression cycle).

The absorption cycle is similar to the compression cycle, except for the method of raising the pressure of the refrigerant vapor.

Vapor Absorption CycleIn the absorption system, the compressor is replaced by an absorber which dissolves the refrigerant in a suitable liquid, a liquid pump which raises the pressure and a generator which, on heat addition, drives off the refrigerant vapor form the high pressure liquid.

Some work is required by the liquid pump but, for a given quantity of refrigerant, it is much smaller than needed by the compressor in the vapor compression cycle.

In an absorption refrigerator, a suitable combination of refrigerant and absorbent is used. The most common combinations are ammonia (refrigerant) and water (absorbent), and water (refrigerant) and lithium bromide (absorbent)

1950s and 1960s, both centrifugal chillers driven by electric motors & SAC to provide summer cooling were widely used in central refrigeration plants.

Steam widely used because excess steam was available in summer in many central plant (used steam to provide winter heating) and because energy cost were of little concern.

1973 energy crisis; the price of NG and oil used to fuel steam boiler drastically increased.

SAC / DFC DevelopmentThe earliest single-stage, indirect-fired SAC had a COP of only 0.6 to 0.7. they required more energy and could not compete with ECC.

Many absorption chillers were replaced by ECC in the late 1970s and 1980s

High investment required to build new power plants, electric utility company added high demand charges and raised cost-per-unit charges during peak usage period.

In recent years, double effect, direct fired absorption chillers have been developed in both Japan and the US with a COP approximately equal to 1.

2.0 Unit Refrigerant18Typically, commercial and industrial refrigeration systems North America are rated in Tons of Refrigeration (TR). Historically, one Ton of Refrigeration was defined as the rate of heat (energy) removal that will freeze one short ton of water at 0 C (32 F) in one day

It was also defined as cooling capacity of an air conditioner or refrigerator equal to 12,000 British Thermal Unit (Btu) per hour 200 Btu per minute and denotes; the amount of heat required to melt one ton of ice in 24 hours

19This was very important because many early refrigeration systems were in ice houses. The simple unit allowed owners of these refrigeration systems measure a days output of ice against energy consumption and compare their plant to one down the street.

While ice houses make up a much smaller part of the refrigeration industry than they once did the unit of Tons of Refrigeration has remained in North America. The unit's value as historically defined is approximately 11,958 BTU/hr (3.505 kW) has been redefined to be exactly 12,000 BTU/hr (3.517 kW).20One short Ton = 2,000 lbLatent heat of ice (i.e., heat of fusion) 144 Btu / lb (or 334.5 kJ/kg)

Therefore, One Ton of Refrigeration

= 2,000 * 144 = 288,000 Btu / 24 hr= 12,000 Btu/hr = 200 Btu / Minute = 3.517 kJ/s= 3.517 kW

The Formula3.0 Absorption Principles22Absorption Chiller in GDC.Major Component Absorption cycle.Lithium Bromide & Refrigerant CharacteristicCrystallization CurveTYPEMANUFACTUREQTYLOCATIONSIZE(RT)SACHITACHI3PLANT 125003KLIA25006PLANT 22500EBARA2PLANT 125005PLANT 225009KLIA25002UTP1250DFCSANYO2PLANT 215004PICC8306PJ1-ANNEX1000KAWASAKI3WP7004586,9203.1 Absorption Chiller in GDC3.2 Major Equipment Evaporator Absorber Condenser Low Stage Generator High Stage Generator Burner (For DFC)

TubesChilled water inletChilled water outletRefrigerant spray* All parameters above are typical operating parameters.Chilled water enters at 12oC-13oCRefrigerant flow to evaporator from condenser by gravity flow and refrigerant pump sprays the liquid refrigerant through the spray nozzles over the outer surface of the CHW tube bundles Refrigerant water is sprayed at 5oC. However, for 2 modules SAC like HITACHI, the 1st module ~7-8CRefrigerant evaporates & absorbs heat from CHW Return. Heat is transferred from the CHW to the vaporized refrigerant at an amount equal to the latent heat of vaporization.Chilled water temp goes down to 6oC-7oCRefrigerant vapor enters Absorber.Pressure: 5.6 6.5 mmHg (0.7kPa 0.9kPa). For Hitachi 1st module, P= ~8mmHg(1.05kPa)RERIGERANT PUMPTYPE OF CHILLERSPECIFICATIONQTYREMARKHITACHI415V x 3 x 50Hz x 0.4kW X 4P21 UNIT EACH / MODULEEBARA415V x 3 x 50Hz x 1.5kW x 4P2SANYO / KAWASAKI415V x 3 x 50Hz x 0.4Hz x 4P1a. Evaporator

LiBr 57%LiBr 64%Cooling waterSolution pump* All parameters above are typical operating parameters.When its absorbs water vapor, temp goes up and becomes diluted 57%.Cooling water takes away heat of absorptionDiluted solution is pumped into generator to be heated & concentratedPressure = 6mmHgIn the absorber, concentrated solution is supplied and sprayed at about 40-49C with a concentration of 62-64%Vaporized refrigerant is absorbed by the concentrated LiBr solution because of its lower vapor pressureIt is cooled by the CDW flowing inside the tube bundle at an entering temperature of 29-30C. As the water vapor from the evaporator is absorbed, the solution is diluted to a concentration of about 57% & its temp drops to 35CThe vapor pressure of the solution is then about 5mmHg abs, which is lower than the evaporator pressure of 5.6 6.5 mmHg The heat of absorption is removed by the CDW. Diluted solution is then pumped to the LTG & HTG by the solution pump. However for Hitachi chiller one solution pump is used to circulate diluted LiBr back to the absorber b. AbsorberAbsorption takes place as the refrigerant vapor that is created in the evaporator diffuses into the LiBr solution that is sprayed down over the tubes in the absorber. Diffusion is a term that is used when a substance tends to move( spread of particles) from an area of greater concentration to an area of lesser concentration.The diffusion of refrigerant vapor into liquid LiBr solution is almost the same. It happens because the vapor pressure of the LiBr solution is lower than that the vapor pressure of the refrigerant.

Detail ProcessWhen the solution has only small amounts of refrigerant in it (higher concentration of LiBr) and its temperature is reasonably low, its vapor pressure is also low and the refrigerant vapor has great desire to diffuse or dissolve into the solution. The greater the difference in vapor pressure between solution mixture and the refrigerant vapor, the greater the desire to merge and so on.Two simple rules govern the rate of absorption.1) The lower the solution mixture temperature, the lower the vapor pressure of the solution2) The higher the concentration, the lower the vapor pressure of the solution.Therefore, the lower the solution temperature & the higher the concentration, the greater the rate of absorptionReference; Durhing Diagram.

How it happen?In our example, LiBr solution entering the absorber is 62% LiBr while the temperature is approximately 48.9C. Figure 1 (Durhing Diagram) which shows the vapor pressure verses solution temperature for 62% LiBr, reveals that at 48.9C, the solution has a vapor pressure of slightly less than 7 mmHg absolute.

Since the refrigerant vapor is at pressure of 5.6mmHg absolute, diffusion of the refrigerant vapor into the solution cannot take place. In order for the solution to absorb refrigerant vapor, its vapor pressure must be lower than the refrigerant vapor pressure.As the solution from the spray nozzles hits the top layer of tubes, its temperature is lowered by the Cooling Water passing through the tubes. Our typical droplet lands on one of the tubes in the top row and spreads nicely around the tubes outer surface.

The Cooling Water flowing through the inside of the absorber tubes at approx. 29-30C begins to cool our droplet of solution. When the droplet temperature falls below approx. 43C, its vapor pressure is lowered (~5 mmHg) below that of refrigerant vapor.As the solution vapor pressure continues to fall due to the cooling effect of the absorber tubes, the refrigerant vapor with a higher pressure than the solution, is able to diffuse into the solution and absorption takes place.

This is actually only the beginning of the absorption process or mass transfer. Mass transfer simply means that the solution is gaining mass or weight if you prefer. The mass that it is gaining is refrigerant.1.Solution Pump 1 unit for each module (7.5kW)To pump out diluted solution (57%) to LTG via LT Hex To pump out diluted solution (57%) to HTG via LT hex, HT hex & drain cooler2. Solution spray pump #1- 1 unit for each module (5.5kW)To circulate diluted LiBr back to absorber to maintain good cooling process for LiBr so that vaporpressure is always low and absorption rate is efficient.

3. Solution spray pump #2 1 unit for each module (5.5kW)To pump concentrated LiBr (64%) from LTG & HTG via LT Hex & HT Hex back to absorber

Hitachi Chiller : Solution pump 4 units - To pump out diluted LiBr to LTG & HTG via LT Hex, Drain Hex1#. After drain Hex #1, the LiBr flow is split to LTG and HTG (via HT Hex and drain Hex #2)

Ebara Chiller

Burner/SteamWater vaporDiluted LiBrConcentrated LiBr* All parameters above are typical operating parameters.There is a different between Hitachi & Ebara chiller before the solution enteringHTG due to some component arrangement. It can be explained as below;

For HITACHI chiller-The diluted solution (57%) from absorber is separated into two ;i) Flowing through LT Hex (in 35C-out 70C) & partly to HT Hex (in 70C- out 120C). Another part from LT Hex will flow to LTG (70C)ii) Flowing through Drain Hex (in 35C-out 70C) - The solution leaving from the above section which is partly concentrated (~60%) will join again before entering HTG

For EBARA chiller- The diluted solution (57%) from absorber is flowing through LT Hex (in 35C- out 68C max.) and LT Drain Hex (in 68C-out 80C max.) and after that is separated into two; i) Flowing through HT Hex (in 70C out ~115C) and HT Drain Hex (in 115C out 122C) to HTGii) Flowing directly to LTG (70C)

c. HTGIn the HTG, the solution is heated to ~140C by driving heat source i.e steam for SAC (up to 160C) and ~1,400C flame for DFC. The water vapor boils off at a pressure of about 390 mmHg abs. (52 kPa abs). For DFC the pressure is at maximum 690mmHg abs (91kPa abs)The solution release the absorbed refrigerant (vaporized) and also re-concentrates to 66%Refrigerant vapor (~149C) flows via the tubes submerged in the diluted solution in the LTG and condenses to liquid there.The LiBr solution;66% and 130C in temperature returns to the HT Hex and cools to about 90C.

It will then flow via LT Hex, leaves at ~45C before entering absorber with 63-64% concentrationFor SAC Hitachi, a pump (solution spray #2) is used to pump LiBr from HT Hex & LTG via LT Hex back to absorber while for EBARA, LiBr flow to absorber by gravitational forceSteam source that has been utilized will flow via drain Hex before turns to steam condensate at ~80C back to Hot Well Tank while for DFC the combustion exhaust is release to the atmosphere

STEAM ABSORPTION CHILLER SINGLE EFFECT* All parameters above are typical operating parameters.38

STEAM ABSORPTION CHILLER DOUBLE EFFECT* All parameters above are typical operating parameters.39Double effect means that there are 2 generatorsThe generator section is divided into a high temp generator (HTG) and a low temp generator (LTG)The refrigerant vapor produced by HTG is used to heat LiBr solution in the LTG in which the pressure (hence the boiling point) is lower.Thus the heat of condensation is effectively utilized.In the single effect type, the refrigerant vapor produced by the (LTG) generator is send to the condenser to become liquid refrigerantIn the double effect, the refrigerant vapor produced by the HTG turns to water in LTG HEX tubes as it releases heat to the LiBr solution.In this step, the diluted solution is heated by driving heat source (HTG) and by the latent heat in the refrigerant vapor (LTG) which otherwise would be released into the cooling water.Double Effect TypeThe refrigerant vapor produced by both LTG and HTG turns to refrigerant liquid and mixes in the condenser before returning to the evaporator.

This combination means a lower energy consumption of driving heat source.

Moreover, less heat being discarded into the Cooling Water translates into small cooling water.

The COP of single stage AC is about 0.6 while double stage is about 1.2

Comparison of driving energy consumption of single effect and double effect is as follows.The amount of evaporated refrigerant per one (1) USRT in the evaporator is;

Heat amount of 1 USRT = 3,024 kcal/h = 5 kg/hLatent heat of evaporated refrigerant 594.3 kcal/kg

Namely, in order to get 1 USRT, 5 kg/h of refrigerant is needed

Comparison of Driving EnergyIn the single effect, the generator must produce 5kg/hr of refrigerant. Therefore driving energy to produce 5kg/hr is required.

However, in case of the double effect,5 kg/h of refrigerant is totally produced by both high and low generators.

3 kg/h of refrigerant is produced by the HTG and 2 kg/h of refrigerant is produced by the LTG. In other word, only driving energy to produce 3 kg/h of refrigerant is required.

Accordingly, the double effect type can save 2kg/h of driving energy as compared with the single effect type and still more as a heat released to the air by cooling water; cooling tower can be sized down.

Diluted SolutionConcentrated SolutionRefrigerant VaporCondenserTo Absorber* All parameters above are typical operating parameters.The diluted LiBr from LT Hex (Hitachi) and LT DHex (EBARA) enters the LTG at 65-70C. The water vapor from HTG (149C) flows through the tube bundle submerged in the diluted LiBr and condenses to liquid form at ~90CThe liquid refrigerant then enters the trench in the condenserThe latent heat of condensation released from the liquid refrigerant heats the diluted solution from 65C to 82C & boils off the water vapor from the diluted solution at pressure of about 50mmHg abs (6.7 kPa abs). The vapor goes to condenserAs the water vapor is boiled off, the LiBr solution becomes partly concentrated with a concentration of 60.2%.At the outlet of the LTG, partly concentrated LiBr combines with the concentrated LiBr from the HT Hex at 95C & the mixture enters the LT Hex at ~89C and a concentration of 63-64%.After it flows through the LT Hex, the temperature of the solution drops to about 45C. The solution then enters the absorber, spray over the CDW tube bundle & absorbs the water vapor from the evaporator.

d. LTGCooling water

CondenserCondensate* All parameters above are typical operating parameters.The liquid refrigerant from LTG tubes enters the trench in the condenser at ~90CCondensed liquid refrigerant from the tubes is cooled to a temperature 37C & combined with the liquid refrigerant condensed in the condenserRefrigerant vapor boiled off in the LTG is extracted by the condensers low saturated pressure of 46.2 mmHg abs. (6.2 kPa abs.) through the top passage & condenses to liquid as the Cooling Water removes the latent heat of condensation at a temperature of about 37C Liquid refrigerant is forced through an orifice, throttled to a pressure of about 6.8mmHg abs. (906 Pa abs.) and returned to the evaporator

e. Condenser45Lithium Bromide & RefrigerantCharacteristic46Absorbent: Lithium Bromide

Stable.Solid state.Similar to salt, high boiling point.Very stable but corrosive to the metalVery High Absorption Ability, Dissolve up to 60% at normal temperature.Non Toxic, OdorlessComponent: Li = 8%, Br = 92%.Specific Gravity = 3.46 (at 25oC)

Refrigerant: Pure Water

LiBr Solution: Pure Water + LiBr

LiBr solution charged in composition: - LiBr = 53 56%, Water = 46 43 %Strong LiBr Solution:- % of LiBr Concentration > 64%Weak LiBr Solution - % of LiBr Concentration < 64%

LiBr SolutionLiBr SolutionInhibitor-To protect chiller internal materials such as steel, copper etc. from corrosion attack.-Chemical used: Lithium Molybdate, Lithium Chromate, Lithium Nitrite.

SurfactantTo maintain solution surface tension. Increase solution absorption rate hence will increase heat transfer efficiency and chiller performance.Chemical used: Alcohol based e.g. Octyle Alcohol, Iso-Octanol.

pH AdjusterTo maintain pH at certain range (xx-xx) due solution Alkalinity increase after internal chemical reaction.Chemical used: Hydrogen Bromide (HBr).Additional SubstanceA chemical compound of Lithium (from lithium ore) & Bromine (from seawater)Prepared by treatment of lithium carbonate with Hydrobromic acid. The salts forms several crystalline hydrates. The anhydrous salt forms cubic crystals similar to common saltA white, deliquescent, granular powder with a bitter taste, melting at 547C, soluble in alcohol & glycolA desiccant material which has hygroscopic characterHygroscopic is the ability of a substance to attract and hold water molecules from the surrounding environment with the absorbing material becoming physically changed somewhat by an increase in volume, stickness or other physical characteristics of the materialsWater molecules become suspended between the materials molecules in the processSame characteristics as salt (Sodium Chloride) but absorption power is stronger than saltLiBr has strong corrosive action to a metal under existing oxygen

Lithium Bromide CharacteristicsLithium Chromate/Molybdate

Lithium Chromate and Lithium Molybdate protect steel without the formation of ammonia or iron oxideThey don't scavenge hydrogen gas formed when the iron corrodes. They stop iron from corroding in the first placeEffective corrosion inhibitors in brine systems such as lithium bromideChromates are pollutants, their usage has been highly reduces over the years. However it is still quite reasonable to apply chromate systems since nothing is being discharge into the environmentMolybdate is not as effective as chromate

Lithium Nitrate

Nitrate has the ability to scavenge the hydrogen gas generated by corrosion thus maintain good vacuum conditionNitrate works by increasing the formation of iron oxide commonly found in all absorbersIdea is that the oxide will coat the steel surface and prevent additional corrosive attackA good concept except that the oxide layer becomes too thick (accumulate), ultimately falling off the steel into the solution. Debris the fouls all of the internal orifices causing significant problemsThe disadvantage is nitrate can reacts directly with hydrogen, reducing it to ammoniaAmmonia is very harmful to cuprous (copper) material and increase the overall corrosion rate of copper-based metalCan be a component of more exotic corrosion failures such as stress corrosion cracking.Therefore, the nitrate must not be overused

Inhibitor CharacteristicsHydrobromic acid and lithium hydroxide modify the solutions pH and alkalinityThe acid lowers these values while the hydroxide increases themThe cuprous (copper) metals are naturally protected at low pH and low solution alkalinitiesIt is the ferrous metal (iron/steel) that is affected under these conditionIf low pH and alkalinity are maintained in the lithium bromide brine, an inhibitor is needed to protect the steel

Ph Adjuster CharacteristicsAs an accelerating agent of absorption power Without alcohol, the solution surrounding the absorber tube tends to stratify or develop layersAs refrigerant is absorbed into the outer surface of the solution surrounding the absorber tube, the solution reaches equilibrium due to lack of heat transfer.Equilibrium is a scientific way of saying things that have stopped happeningIn other words, the heat build up in LiBr on the outer-layer causes absorption to cease due to solution temperature rising.Vapor pressure goes up and when it gets as high as the refrigerant vapor pressure, no more absorption can take place.Some stirring up of the solution is needed to mix the layer and get the heat from the outer layers to the inner area of the tube where the heat can be carried away.Alcohol will stir up the layers by convection at the correct quantity therefore a small quantity should be added and observed the performanceIt will maintain solution surface tension and increase heat transfer efficiency and chiller performanceOctyl AlcoholLithium Bromide corrosion control in absorption refrigeration is a very complex scheme of proper mechanical operation and the balance of added chemical.What complicates the situation still further is that there arent a large number of highly skilled personnel available to service absorption systems.These conditions lead to many absorption machines suffering from severe corrosion. They are performing very poorly at best and many are ready to be scrapped prematurelyTherefore, attention should be paid to handle the solution and it is necessary to keep inhibitor concentration/limit within the maintenance standard (OEM) by performing chemical analysis of the solution as well as any air leakages from outside that can affected vacuum side of the chillerIssuesInhibitor and Alkalinity adjustment shall be conducted periodically base on vendor recommendation in order to ensure system will be protected from corrosion.

Amount to be used for the adjustment depend on LiBr Solution analysis.

Topping up LiBr Solution is not required unless it leaks from the system or contaminated.

LiBr Solution can be used for the period of 20 years with the condition that the solution is free from contamination.More on LiBr Solution

Refrigerant boiling point depends on the pressure of the systemRefrigerant CharacteristicRefrigerant (Pure water) boiling point will depend on surrounding pressure.

Water boiling point is relatively low at low surrounding pressure.

Absorption Cycle chiller evaporator & absorber shall be maintained at pressure below 6 mmHg in order to achieve chilled water temperature at 6oC.

If evaporator & absorber pressure slightly high chiller will not be able to produce lower chilled water temperature hence chiller capacity will be reduced.Refrigerant CharacteristicExample:

Refer to Water Saturated Temperature Curve, determine water boiling point temperature at 5 mmHg absolute pressure.The answer = 4OC Condition at below the crystallization curve, LiBr Solution will be crystallized (solidified).

During design stage, the lower point of LiBr Solution crystallization must be considered in order to determine LiBr Solution concentration before charge in into the chiller.

Due to sudden change of Temperature (High Low) at certain chiller compartment such as HTHE, LTHE & Piping, High Concentration LiBr Solution may be crystallized.

LiBr Solution Crystallization Curve

Pressure< Temperature & Concentration of DEA Cycle4.0 Chiller Safety

60Common Safety Crystallization prevention/protection functionHigh concentration alarmCombustion or steam will be stopped when high concentration detectedHigh Stage Generator temperature high alarmFuel or steam flowrate will be reduced when high temperature generator reached high temperature setting.Cooling water temperature lowSetting temperature of cooling water can be controlled automatically depending on inlet CW temperature. Freeze protection function To prevent chilled water freezingThe chiller will cut-off when the chilled water outlettemperature fall below than the setting temperature.62DevicesFunctionInstallation LocationHTG temp sensorTo prevent HTG super high temperature & crystallizationHTGCW temp sensorTo prevent crystallization inside HEXCW inlet pipeCHW temp sensorTo prevent frozen copper tubes inside evaporatorCHW outlet pipeHTG Solution level sensorPrevent HTG damage caused by HTG solution offHTGRefrigerant level sensorPrevent cavitation of refrigerant pump.Refrigerant chamber in evaporatorRefrigerant pump thermal relayPrevent overload damage to refrigerant pump.Control CabinetVacuum pump thermal relayPrevent overload damage to refrigerant pump.Control Cabinet

* Typical safety devices may be different for other Manufacturers. Separate list will be provided.Typical safety Devices635.0 Maintenance, Inspection & Troubleshooting64ACTIVITYDURATIONWEEKLYMONTHLYANNUALLYRecording Of Operation DataxCheck Of Liquid (Solution & Refrigerant) LevelxCheck Of Operational Control Valvex* Refining Of Refrigerantx* Manual PurgingEvery 3 monthsReplacement Of Vacuum Pump OilxAppearance Check Leakage, Vibration, SoundxInsulation Resistant MeasurementxElectrical Terminal CheckxOperation Control Panel CheckxPreventive MaintenanceACTIVITYDURATIONWEEKLYMONTHLYANNUALLYCapacity Of Purging UnitxLeakage Check for Purging Solenoid ValvexAir Tightness CheckEvery 3 MonthsAnalysis Of Quality for CHW, CW and steam drainEvery 3 MonthsAnalysis Of Solution & Refrigerantx NO.FAULTSCAUSESKEYS1Poor vacuum conditionLeakage caused during transportation and leakage detection not performed at initial start, or new leakage occurred during operation.Leakage at welding seam caused by serious outside corruption.Improper purging.Performance of vacuum pump decreased.Aging sealing element or improper installation.Vacuum valve does not close tightly.HTG temp. high than 165OC during operation which generates Hydrogen.Leaking at Solution & Refrigerant Pump.Carry out overall leakage detection and eliminate the leakage.Clean the rust and eliminate the leakage then repaint it or all chiller (the chiller should be in vacuum during painting); maintain good ventilation, humidity (2oC; readjust the water temp. compensating parameter when tolerance 1.04)a.cooling water inlet temp. too lowb.combustion too greatc.too much cycling causes HTG or LTG solution level too high and concentration too weak.d.concentration of mixed solution too diluteIncrease the cooling water inlet temp. properly.Regulate the burner decreasing the combustion.Discharge some refrigerant per the sampling result.Discharge some refrigerant per the sampling result. By-pass refrigerant completely after above procedures.7HTG solution control abnormalSolution level does not stabilize at zone C with wide fluctuation, sometimes fluctuates to Zone A or E: keeps at Zone D or B for a long time. Solution level probes are not well-connected or disconnected.Something wrong with solution level control or PLC.UKD aging.Solution level control is poor grounded.Long time observe and set frequency parameter accurately.Overhaul.Overhaul or replace.Replace.Check the grounding.

b,c, d and e items also applicable to refrigerant control abnormal. NO.FAULTSCAUSESKEYS8Copper tubes in main shell crack.Tube frozen. - Some valve plate in CHW system falls suddenly. - CHW pump fault. - Filter at CHW system blocked.CHW temp. outlet too low. Water system improper cleaning. Additional anti-freeze while machine room