What Is A Boiler?
What is a Boiler? Vessel that heats water to becomehot water or steam At atmospheric pressure watervolume increases 1,600 times Hot water or steam used to transferheat to a process
Boiler Safety ! Heat – “Ouch that’s HOT !”Fuel / GasElectricityExhaust GasMoving Parts
BoilersBoilers used from 1891 to 1901were Horizontal Return Tube[HRT] Boiler
Boilerfor 1902 plant
Babcock & WilcoxStraight Tube Boiler
Rossdale had 16 of these boilerinstalled between 1908 & 1914
1914 Boiler roomB & W straight tube boilers
1914 Boiler roomB & W straight tube boilers
Crane lifting Boiler Drum
Crane lifting Boiler Drum
# 4 Boiler Steam Drums
The Classifications Pressures and temperaturesHeat Exchanger TypeFuelMaterialsDraft TypeBurner TypeChamber Type
Boiler Types and Classifications Water flow through tubes Water Tubes surrounded by hotgasApplication Used for Power Plants Steam capacities range from4.5- 120 t/hr CharacteristicsHigh Capital CostUsed for high pressure highcapacity steam boilerDemands more controlsCalls for very stringent waterqualityWater Tube Boiler
1. Fire Tube Boiler2. Water Tube Boiler
Package boilers aregenerally of shell type withfire tube design High heat release rate insmall combustion space More number of passes-somore heat transfer Large number of smalldiameter tubes leading togood convective heattransfer. Higher thermal efficiencyPackaged Boiler
3. Packaged BoilerTo ChimneyOil Burner
4. Fluidized Bed Combustion(FBC) Boiler Suspend solid fuelson upward-blowingjets of air during thecombustion process
Fluidized-bed boiler (Contd.)Advantages : Higher rates of heat transfer betweencombustion process and boiler tubes(thus reduced furnace area and sizerequired), combustion temperature 850oC is lowerthan in a conventional furnace. The lowerfurnace temperatures means reducedNOx production. In addition, the limestone (CaCO3) anddolomite (MgCO3) react with SO2 to formcalcium and magnesium sulfides,respectively, solids which do not escapeup the stack; This means the plant caneasily use high sulfur coal. Fuel Flexibility: Multi fuel firingCirculating Fluidized Bed Boiler
Fluidized bed Combustion (FBC) boilerWhen an evenly distributed air or gas is passed upward through afinely divided bed of solid particles such as sand supported on a finemesh, the particles are undisturbed at low velocity. As air velocity isgradually increased, a stage is reached when the individual particlesare suspended in the air streamFurther, increase in velocitygives rise to bubble formation,vigorous turbulence and rapidmixing and the bed is said to befluidized.Coal is fed continuously in to ahot air agitated refractory sandbed, the coal will burn rapidlyand the bed attains a uniformtemperatureFluidized Bed Combustion
Stoke Fired BoilersCoal is first burnt in suspension then incoal bedFlexibility to meet load fluctuationsFavored in many industrial applications
Chain Grate or Traveling Grate Stoker Boiler Coal is fed on one end of amoving steel chain grate Coal burns and ash dropsoff at end Coal grate controls rate ofcoal feed into furnace bycontrolling the thickness ofthe fuel bed. Coal must be uniform insize as large lumps will notburn out completely Bed thickness decreasesfrom coal feed end to rearend and so more air atfront and less air at rearend to be supplied Water tube boiler
6. Pulverized Fuel Boiler Pulverized coal powder blown with combustionair into boiler through burner nozzles Combustiontemperature at 1300 1700 C Benefits: varying coalquality coal, quickresponse to loadchanges and high preheat air temperatures
Pulverized Fuel Boiler (Contd.)Advantages Its ability to burn all ranks of coal from anthraciticto lignitic, and it permits combination firing (i.e.,can use coal, oil and gas in same burner). Becauseof these advantages, there is widespread use ofpulverized coal furnaces.Disadvantages High power demand for pulverizing Requires more maintenance, flyash erosion andpollution complicate unit operation
7. Waste Heat Boiler Used when waste heatavailable at medium/hightemp Auxiliary fuel burnersused if steam demand ismore than the waste heatcan generate Used in heat recoveryfrom exhaust gases fromgas turbines and dieselengines
Pressure & Temperature Steam– Low Pressure ( 15 psig)– Medium Pressure (15- 160 psig)– High Pressure ( 160 psig) Hot Water– Low Temperature ( 250F and 160 psig)– Medium Temperature (250 to 350F)– High Temperature ( 350F)
Fuel Fuel– Oil– Natural gas– Propane– Electric– Coal– Wood
Heat Exchanger Water Tube– Straight tube– Bent tube Fire Tube– Sing pass– Multiple pass Modular / Sectional
Materials Non-Condensing– Carbon Steel– Copper– Cast Iron Condensing– Stainless Steel– Aluminum– Cast Iron– Plastic
Draft Type Natural (Atmospheric) Forced Induced
Burner Type One Stage High/Low Fire Modulating
Chamber Type Dry Based CombustionFire box under the boiler and will needrefractory material opposite the burner toabsorb and help distribute the heat back up intothe bottom of the boiler Wet Based Combustion– Boiler water surroundthe burner flame. Wet Leg (mud leg) Dry Back Wet Back
Boiler performance Causes of poor boiler performance-Poor combustion-Heat transfer surface fouling-Poor operation and maintenance-Deteriorating fuel and water quality Heat balance: identify heat losses Boiler efficiency: determinedeviation from best efficiency
Methods of Heat Transferconvectionwarm airradiationhotwaterconductioncool air
Principles of Heat Transfer Heat energy cannotbe destroyed Heat always flowsfrom a highertemperaturesubstance to a lowertemperaturesubstance Heat can betransferred from onesubstance to another
Warm Air Units
Components of Fan tion
Heat BalanceAn energy flow diagram describes geographicallyhow energy is transformed from fuel into usefulenergy, heat and lossesStochiometricExcess AirUn burntStack GasFUEL INPUTSTEAMOUTPUTConvection &RadiationBlowDownAsh and Un-burnt partsof Fuel in Ash
Heat BalanceBalancing total energy entering a boiler againstthe energy that leaves the boiler in different forms12.7 %8.1 %1.7 %100.0 %BOILERFuel0.3 %Heat loss due to dry flue gasHeat loss due to steam in fuel gasHeat loss due to moisture in fuelHeat loss due to moisture in air2.4 %Heat loss due to unburnts in residue1.0 %Heat loss due to radiation & otherunaccounted loss73.8 %Heat in SteamHeat loss due to radiation & otherunaccounted loss
GoalHeat BalanceGoal: improve energy efficiency by reducingavoidable lossesAvoidable losses include:- Stack gas losses (excess air, stack gastemperature)- Losses by unburnt fuel- Blow down losses- Condensate losses- Convection and radiation
Boiler EfficiencyThermal efficiency: % of (heat) energy input that iseffectively useful in the generated steamBOILER EFFICENCYCALCULATION1)DIRECT METHOD:The energy gain of theworking fluid (water and steam)is compared with the energycontent of the boiler fuel.2) INDIRECT METHOD:The efficiency is thedifferent between lossesand energy input
Boiler Efficiency: Direct MethodBoiler efficiency ( ) Heat Input x 100Q x (hg – hf) x 100 Heat OutputQ x GCVhg -the enthalpy of saturated steam in kcal/kg of steamhf -the enthalpy of feed water in kcal/kg of waterParameters to be monitored:- Quantity of steam generated per hour (Q) in kg/hr- Quantity of fuel used per hour (q) in kg/hr- The working pressure (in kg/cm2(g)) and superheattemperature (oC), if any- The temperature of feed water (oC)- Type of fuel and gross calorific value of the fuel (GCV) inkcal/kg of fuel
Boiler Efficiency: Direct MethodAdvantages Quick evaluationFew parameters for computationFew monitoring instrumentsEasy to compare evaporation ratios withbenchmark figuresDisadvantages No explanation of low efficiencyVarious losses not calculated
Boiler Efficiency: Indirect MethodRequired calculation data Ultimate analysis of fuel (H2, O2, S, C, moisturecontent, ash content) % oxygen or CO2 in the flue gas Fuel gas temperature in C (Tf) Ambient temperature in C (Ta) and humidity of air inkg/kg of dry air GCV of fuel in kcal/kg % combustible in ash (in case of solid fuels) GCV of ash in kcal/kg (in case of solid fuels)
Boiler Efficiency: Indirect MethodAdvantages Complete mass and energy balance for eachindividual streamMakes it easier to identify options to improveboiler efficiencyDisadvantages Time consumingRequires lab facilities for analysis
The Opportunities1.2.3.4.5.6.7.8.9.10.11.12.13.Stack temperature controlFeed water preheating usingeconomizersCombustion air pre-heatingIncomplete combustion minimizationExcess air controlAvoid radiation and convection heatlossAutomatic blow down controlReduction of scaling and soot lossesReduction of boiler steam pressureVariable speed controlControlling boiler loadingProper boiler schedulingBoiler replacement
Boiler solutions Control Products of combustionsControl Water treatmentControl heat lossControl blow downControl water lossControl boiler control scheduleControl heat transfer surfaces
RegulatorLow PressureSafetyGas SafetyValveGas ControlValveHigh PressureSafety
RayPak Hi Delta
Water Flows2.31 PSI 1 Foot
Example
Forced Draft
Gas pressure
InOutPWR120VACCombustionBlower24 VACCommonBIP Blower StatusBIP Blower InterlockGas Valve
Cold Water Start
Cold Water Start
Cold Water Run
Cold Water Run
Cold Water Run
Cold water Start VS Cold Water run Cold water start is for transient cold wateroperation Cold water run s for continuous operation below105deg. F. Cold water start maintains design flow rate atsystem design temperatures but reduces boilerflow rate during heavy bypass operation. Cold water run maintains constant design flowrate in the boiler
All heating systems are designedand engineered to operate withvery specific ranges of: Combustion AirCarbon MonoxideStack TemperatureTemperature Rise across the heatexchanger (air flow)
Combustion
Air/Fuel Ratio – CombustionEfficiency In theory . . .AIR (O2 & N2)PERFECTCOMBUSTIONFUEL (C2H)EXHAUST(CO2, H2O & N2)
Air/Fuel Ratio – Combustion Efficiency In the real world . . . Excess air introduced to prevent incomplete combustionEXCESS O2AIRNN2 &&2) )AIR(O(O22CombustionFUEL (C2H)EXHAUST(CO2, H2O & N2) Left over oxygen carries heat away from boiler
Standard Air 20.9% oxygen 78% nitrogen 1% other gasses
Complete Combustion CH4 3O2 Heat 2H2O CO2 O2 Where– CH4 1 cubic foot of methane gas(natural gas)– 3O2 3 cubic feet of Oxygen– Heat 1027 BTU’s of energy producedfrom the chemical reaction– 2H2O 2 cubic feet of water Vapor– CO2 1 cubic feet of carbon dioxide– O2 1 cubic foot of excess oxygen
Incomplete Combustion CH4 3O2 Heat 2H2O CO ( /- O2)– Where CO Carbon Monoxide
Courtesy of Bill Spohn, TestoCombustion DiagramIncompleteCompleteExcess FuelCO2burnersStoichiometric lineCOIdeal operating range ofEff.Flue gas componentsThe idealoperatingrange is asetting withexcess air.O2Excess Air
What is flue gas?Carbon dioxide CO2Carbon monoxide COSulfur dioxide SO2O2 - balanceNitrogen oxide NOxWater vapor H2OSmoke (oil systems)How is it formed?fuelairOxygen (20.9%)water vaporNitrogen (79%)Courtesy of Bill Spohn, itrogenwater
H2O and CO2 are always the productsfrom combustion of hydrocarbons H20 Is water– What is wrong with water as a product ofcombustion and where does the water comefrom.
CO2 What is it Carbon DioxideEmissions of CO2 can contribute to climate changeCO2 is toxic in higher concentrations: 1% (10,000 ppm)The combustion process is two stage, carbon monoxideis formed first and if excess oxygen is present then thecarbon monoxide reacts with additional oxygen to formCO2 12 to 14 % by volume, the higher the readings, the betterthe combustion efficiency. It must be remembered thatthe CO2 reading changes with the fuel type/ quality andthe level of excess air supplied to the burners Of environmental concern
Carbon DioxideOrdinary outside air normally contains CO2 at aconcentration of about 300 ppm (300 parts of CO2 gasper million parts of air.)Adults take more than 20,000 breaths a day, and when we breath, we exhalecarbon dioxideIt has been observed that CO2 concentrations between 300-600 ppm areadequate, i.e., people don't usually notice whether or not the air is "stale". However,as CO2 concentrations increase beyond these levels, one will notice ill effects. This isespecially true if room temperatures rise and/or CO2 levels increase above 800 ppm.As these conditions persist, fresh air will need to be introduced. Several studies haveindicate that CO2 does not seriously impact human health until levels reachapproximately 15,000 ppm. This level is more than 40 times greater than the normalconcentration of atmospheric CO2. At extremely high levels, i.e., 30,000 ppm, (theseconcentrations are usually never be reached in a standard home) the symptoms caninclude nausea, dizziness, mental depression, shaking, visual disturbances andvomiting.Concentrations of 100,000 ppm or more of CO2 can produceunconsciousness or death.
Oxygen 3-4 % by volume (for fire tube boiler). 0.5-1.5 % by volume (for water tube boilerwith high efficiency burners). Normally these numbers represent 10%excess air for natural gas Generally 1cubic foot of air to 100BTU’s ofheat value Used to analyze combustion efficiency
Excess % Air A well designed –natural gas fired systemcan be run at 10% Excess % Air Rule of thumb– Boiler efficiency is increased by 1% For each 15% reduction in excess air 40⁰F decrease in stack temperature
N2 Nitrogen Not of single concern in flue gas analysis
NOX Nitrous-oxides NO and NO2 produced from the reaction betweennitrogen and oxygen gases during combustion athigh temperatures. Initiates reactions that result in theproduction of ozone and acid rain 30 PPMV (parts per million by volume)Level requirements change per region andboiler size.
SO2 Sulfur-Dioxide Of environmental concern Directly related to sulfur levels in fuel
Incomplete combustion results in
Carbon Monoxide ( CO ) is acolorless, odorless, tasteless andnon-irritating gas resulting fromthe incomplete combustion oforganic matter.Slightly lighter than air
Sources: Unvented kerosene andgas space heaters; leakingchimneys and furnaces; backdrafting from furnaces, gas waterheaters, wood stoves, andfireplaces; gas stoves. Automobileexhaust from attached garages.Environmental tobacco smoke.
Health Effects: At lowconcentrations, fatigue in healthypeople and chest pain in peoplewith heart disease. At higherconcentrations, impaired vision andcoordination; headaches; dizziness;confusion; nausea. Can cause flulike symptoms that clear up afterleaving home. Fatal at very highconcentrations.
Flame Detection Using FlameConductivity If two electrodes are placed in or near the flameand a voltage is applied to the electrodes, acurrent will flow between the electrodes usingthe ions and the electrons as charge carriers. Acurrent will flow between the electrodes when aflame is present, but there will be no currentwhen the flame is not present.
Principles of Ionization FlameMonitoring An ion is a charged atom that has either gainedan electron to become negatively charged(anion) or has lost an electron to becomepositively charged (cation). The energyreleased during a combustion process will causeelectrons to be knocked loose from an atom,resulting in a positively charged particle and afree electron. This ionization, if monitoredproperly, can be used to generate a safe andreliable indication of a flame.
Principles of Ionization FlameMonitoring cont. If the air-fuel ratio is optimal, the reaction will bethe strongest, and more free ions and electronswill be produced. Since the electrons are somuch lighter than the ions, the electrons travelmuch faster and move away from the burnermouth toward the tip of the flame much morequickly than the heavier ions. This leaves agreater concentration of positively charged ionsin the area near the burner mouth than freeelectrons.
Flame Detection Using FlameRectification: In a rectifying flame ionization detection system,an alternating potential (AC) is supplied to thetwo electrodes. In addition, one of theelectrodes must have a larger surface areacompared to the other electrode. To increasethe size of one of the electrodes and to simplifyconstruction, one of the electrodes is the burnertube. The small electrode is then electricallyisolated from the burner tube (the otherelectrode) with ceramic insulators.
Flame Detection Using FlameRectification cont.
Silicon Carbide
TEMPERATURES 1,100 degrees F to 3,000 degrees F
What is the voltage to the HSI? 120 VAC
Natural gas is lighter than air, which means itdissipates quickly in well-ventilated areas –unless it becomes trapped in an enclosedspace. Given the right concentrations of naturalgas and air, natural gas can ignite from sparksfrom electrical switches or appliances and fromopen flames such as matches and pilot lights.Fire or explosions can result.
Intent is to have the lowest level of Oxygen in percentage andCarbon Monoxide in PPM with carbon monoxide (C) reading lessthan 250PPM
Signs of Carbon Monoxide Stuffy, stale or smelly air Dripping water condensation on yourwindows. (This is a reliable sign if you'vealready taken steps to reduce moistureproduction. It could also mean yourhumidifier is set too high.) Backdraft or soot from a fireplace, chimney orother fuel burning equipment. A yellowburner flame, instead of the normal clear blueflame. (This does not apply to natural gasfireplaces.) A pilot light that keeps going out, or the smellof unusual gases in your home. Even thoughcarbon monoxide is odorless, it is sometimesaccompanied by exhaust gases.
Carbon Monoxide A reading of 100-200 ppm normallyindicates good combustion efficiency. COreadings are more reliable than CO2reading. Of environmental concern
Boiler Maintenance ?*Regular service by a qualifiedservice agency and periodicmaintenance must be performedto assure maximum boileroperating efficiency and safety
Suggested MinimumMaintenance Annual service call by a qualified service agencyBoiler area is free of combustible materials or vaporsCheck for obstructions to airflow or ventilation airVisually check top of vent for soot, check for cracksVisually inspect burners, ignitor, flame sensor and wiringVisually inspect insulation and/or refractory compoundCheck relief valve (refer to manufacturer’s instructions)Test operator and safety controls, check settingsVisually inspect main burner and pilot flames (light blue)Check piping and water system for leaksCheck gas piping and controls for gas leaks
Controls Operator– Sets desired water temperaturesetpoint– *can be leaving or return watercontrol Hi-Limit Safety– Locks out boiler due to high temp Water Flow Switch or Sensors– Proves water is actually flowing
Controls Pilot Sensor– Detects pilot flame (may be visual) Flame Sensor– Detects main flame (may be visual) Airflow Switch– Proves combustion airflow
Controls Pressure Relief– Prevents over-pressurization Low Water Cut-off– Shuts off burner if water level is toolow Fuel Pressure Safeties– Detects high and/or low gas pressure
Types of Controllers
Safety Valves Often considered the primary safety featureon a boiler, the safety valve should really bethought of as the last line of defense. Ifsomething goes wrong, the safety valve isdesigned to relieve all the pressure that canbe generated within the boiler. Keep inmind that the same conditions that makeother safety devices malfunction can alsoaffect the safety valve. Don't let testing andmaintenance schedules slide.
Pressure Relief
Water Level Control and LowWater Fuel Cutoffs These devices perform two separate functions,but are often combined into a single unit. Thismethod is economical, providing both a waterlevel control function and the safety feature of alow water fuel cutoff device. It is recommended,however, that both steam and hot water boilersalways have two separate devices — a primaryand a secondary low water fuel cutoff. Manylocal jurisdictions require two such devices onsteam boilers.
The Fuel System Failure to maintain the equipment in goodworking order could result in higher fuelcosts, the loss of heat transfer or even afurnace explosion. Modern fuel systems arevery complex assemblies, consisting ofboth electronic and mechanicalcomponents. Over a period of time manythings may go wrong. Many users wiselycontract with their gas company or oilservice company to periodically check andmaintain their burner equipment.
Boiler Logs Are Important The majority of boiler accidents can beprevented. One of the most effective toolsis the proper use of operating andmaintenance logs. Boiler logs are the bestmethod to assure a boiler is receiving therequired attention and provide a continuousrecord of the boiler's operation,maintenance and testing. Because aboiler's operating conditions change slowlyover time, a log is the best way to detectsignificant changes that may otherwise gounnoticed.
A CLOGGED OR WARPED HEATEXCHANGERWILL RESULT IN A HAZARDOUSCONDITION DUETO OVERHEATING, FIRE ANDPOSSIBLECARBON MONOXIDEPOISONING.
Natural Gas: 265 deg F plus ½ deg F foreach foot of stack or breeching, includingboth horizontal or vertical runs. #2 Fuel Oil : 240 deg F plus ½ deg F foreach foot of stack or breeching, includingboth horizontal or vertical runs.
Water Quality Less than 50 ppm of calcium Less than 50 ppm of magnesium Less than 100 ppm (5 grains) of totalhardness Less than 25 ppm of chloride Less than 25 ppm of sulfate
Freeze ProtectionConcentration by volumeEthylene GlycolPropylene Glycol55%-50F-40F50%-37F-28F40%-14F-13F30% 2F 4F20% 15F 17F
Gas Hot Water Boiler PM1.2.3.4.5.6.7.8.9.Vacuum clean boiler and breechingClean burners and orifices, check for cracksCheck and clean pilot, thermocouple and ignitorCheck chimney base for dirt or obstructions. Cleanas required. Report and unusual conditions (i.e.fallen bricks, etc.)Check gas valves and gas train for closure andexternal gas leakageCheck circulator motors, bearings, and couplers(Lubricate as required)Test fire and adjust burner as requiredVerify that all safety and operating controls areworking properlyCheck pressure on boiler through firing range anddrain or check expansion tank and test auto fill asrequired
Gas Steam Boiler PM1.2.3.4.5.6.7.8.9.10.11.12.Vacuum clean boiler and breechingClean burner and orifices, check for cracksCheck and clean pilot, thermocouple and ignitorCheck chimney base for dirt or obstructions. Clean asrequired. Report any unusual conditions (i.e. fallen bricks,etc.)Check gas valves and gas train for closure and externalgas leakageClean or replace gauge glass as requiredFlush down boiler and low water cutoffs as required. Verifycutoff operationsPull apart and check or clean all gauge and control siphonsand associated pipingTest fire and adjust burner as requiredVerify that all safety and operating controls are workingproperlyCheck system traps, air valves, vents, and strainers forproper operation. Report any additional problemsCheck condensate pumps, floats and traps, if applicable,and auto fill, if required
The Advantages of IntermittentPump OperationBoiler ABoiler BBoiler Input199,000 BTUH199,000 BTUHCirculating Pump1/7 HP1/7 HPStandby Period18 hrs/day18 hrs/dayPump ControlIntermittentContinuousPump Run Time6 Hours24 HoursWatts Used1224 watts4896 wattsDaily Electricity Cost(@ .08/kwh) .098 .392Annual Electricity Cost 35.74 142.96
Bladder Type Pre-charged Expansion Tanks
Boiler Water Treatment
Ty-Ion B20
Introduction to Boiler Enclosed PressureVessel Heat generated byCombustion of Fuel istransferred to water tobecome steam Process: Evaporation Steam volume increasesto 1,600 times from waterand produces tremendousforce Boiler to be extremelydangerous equipment.Care is must to avoidexplosion.What is a boiler?
What are the various heating surfaces ina boiler?Heating surface is expressed in square feet or insquare meterClassified into :1 Radiant Heating Surfaces — (direct or primary)including all water-backed surfaces that are directly exposed tothe radiant heat of the combustion flame.2 Convected Heating Surfaces — ( indirect orsecondary) including all those water-backed surfacesexposed only to hot combustion gases.3 Extended Heating Surfaces — referring to the surfaceof economizers and super heaters used in certain types of watertube boilers.
Fuels used in BoilerS. SolidNo1 Coal2 Lignite3456Liquid Gaseous AgroWasteHSDNGasLDOBio GasFur.OilLSHSBaggasePithRice HuskPaddyCoconut shellGroundnutshell
Performance Evaluation of Boilers What are the factors for poor efficiency?Efficiency reduces with time, due to poor combustion,heat transfer fouling and poor operation andmaintenance.Deterioration of fuel and water quality alsoleads to poor performance of boiler. How Efficiency testing helps to improveperformance?Helps us to find out how far the boiler efficiency driftsaway from the best efficiency. Any observed abnormaldeviations could therefore be investigated to pinpoint theproblem area for necessary corrective action.
Boiler EfficiencyThermal efficiency of boiler is defined as the percentage ofheat input that is effectively utilized to generate steam. Thereare two methods of assessing boiler efficiency.1)The Direct Method: Where the energy gain of theworking fluid (water and steam) is compared with the energycontent of the boiler fuel.2)The Indirect Method: Where the efficiency is thedifference between the losses and the energy input.Boiler EfficiencyEvaluation Method1. Direct Method2. IndirectMethod
What are the losses that occur in a boiler?Steam Output6. Surface loss1. Dry Flue gas loss2. H2 loss3. Moisture in fuel4. Moisture in air5. CO loss7. Fly ash lossFuel Input, 100%BoilerFlue gasAir8. Bottom ash lossEfficiency(by In Direct Method) 100 – (1 2 3 4 5 6 7 8)
Why Boiler Blow Down ?When water evaporates Dissolved solids gets concentrated Solids precipitates Coating of tubes Reduces the heat transfer rate
Intermittent Blowdown The intermittent blown down is given bymanually operating a valve fitted to dischargepipe at the lowest point of boiler shell to reduceparameters (TDS or conductivity, pH, Silica etc)within prescribed limits so that steam quality isnot likely to be affected TDS level keeps varying fluctuations of the water level in the boiler. substantial amount of heat energy is lost withintermittent blow down.
Continuous Blowdown A steady and constant dispatch of small streamof concentrated boiler water, and replacementby steady and constant inflow of feed water. This ensures constant TDS and steam purity. Once blow down valve is set for a givenconditions, there is no need for regular operatorintervention. Even though large quantities of heat are wasted,opportunity exits for recovering this heat byblowing into a flash tank and generating flashsteam. This type of blow down is common in highpressure boilers.
The quantity of blowdown required to control boiler watersolids concentration is calculated by using the followingformula:(Continuous Blow down)Steam 10 T/hrTDS(T) 0TDS(S) in feed water TDS (C) 3500 ppm Allowable)100 ppmBlow down(B)B SX100/(C-S)Blowdown % TDS in FWx100TDSin Boiler - TDS in FWBlow down flow rate 3%x 10,000kg/hr 300kg/hr 100 / (3500-100) (100/3400)x100 2.9 % 3%
Boiler Water Treatment Method : It is carried out by adding chemicals to boiler toprevent the formation of scale by converting the scale-formingcompounds to free-flowing sludges, which can be removed byblowdown. Limitation : Applicable to boilers, where feed water is low inhardness salts, to low pressures- high TDS content in boilerwater is tolerated, and when only small quantity of water isrequired to be treated. If these conditions are not applied, thenhigh rates of blowdown are required to dispose off the sludge.They become uneconomical from heat and water lossconsideration. Chemicals : Different waters require different chemicals. Sodiumcarbonate, sodium aluminate, sodium phosphate, sodiumsulphite and compounds of vegetable or inorganic origin are allused for this purpose. Internal treatment alone is not recommended.
External Water Treatment Propose: External treatment is used to remove suspendedsolids, dissolved solids (particularly the calcium andmagnesium ions which are a major cause of scale formation)and dissolved gases (oxygen and carbon dioxide). Different treatment Process : ion exchange;demineralization; reverse osmosis and de-aeration. Before any of these are used, it is necessary to removesuspended solids and colour from the raw water, becausethese may foul the resins used in the subsequent treatmentsections. Methods of pre-treatment include simple sedimentation insettling tanks or settling in clarifiers with aid of coagulants andflocculants. Pressure sand filters, with spray aeration toremove carbon dioxide and iron, may be used to remove metalsalts from bore well water. Removal of only hardness salts is called softening, while totalremoval of salts from solution is called demineralization.
Ion-exchange Process (SoftenerPlant) In ion-exchange process, hardness is removed as the water passesthrough bed of natural zeolite or synthetic resin and without theformation of any precipitate. The simplest type is ‘base ex
RayPak Hi Delta . Water Flows 2.31 PSI 1 Foot . Example . Forced Draft . Gas pressure . PWR 120VAC 24 VAC Common Combustion Blower In Out BIP Blower Status BIP Blower Interlock Gas Valve . Cold Water Start . Cold Water Start . Cold Water Run . Cold Water Run . Cold Water Run .
Raypak Hi-Delta Boiler Raypack Hi-Delta boiler with on/off state animations. Murray Boiler Murray boiler with flame animation. Multistack Boiler Multistack boiler with open/closed version but no animations. Superior Boiler Superior boiler with flame animation. F - salesqagraphicscom C 515-965-3403 O S P O S P O S P O S P O S P O S P D
A Lochinvar Crest series condensing boiler, model FBN2001 was installed to replace "Boiler 2" in January 2019. Boiler 2 was an AERCO Benchmark 2.0, serial number G-08-0799. New Boiler Information-SUN-224 Boiler Identification: Boiler 2 Location: Boiler Room Boiler Make/Model
the boiler and they have to enter the registration number of the boiler along with the following details a. Boiler Details : User need to provide following details of the boiler i. Types of Boiler/ Economizer ii. Total Heating Surface Area (Sq. mt) iii. Name of Manufacturer iv. Boiler/ Small Industrial Boiler/ Economizer Works Number v.
Fire tube steam boilers may be either high or low pressure boilers. There are three types of fire tube steam boilers: (i) horizontal return tubular boiler, (ii) scotch marine boiler, and (iii) vertical fire tube boiler. The boiler studied in the present experiment is horizontal return tubular boiler. This boiler is a 3 pass fire tube boiler.
Inspect boiler jacket door gaskets on front of cabinet and reinstall boiler jacket door after start or servicing. The boiler jacket door must be securely fastened to the boiler to prevent boiler from drawing air from inside the boiler room. This is particularly important if the boiler is
EU-34.2 Nebraska Boiler - #2 fuel oil EU-34.3 Nebraska Boiler - soybean oil EU-34.4 Nebraska Boiler - animal fats EU-34.5 Nebraska Boiler - biodiesel heavies EU-34.6 Nebraska Boiler - biodiesel EP-34.2 EU-34.21 Nebraska Boiler (Heat Recover Stack) - natural gas 02-A-387-S1 EU-34.22 Nebraska Boiler (Heat Recover Stack) - #2 fuel oil
8 UNIVERSAL steam boiler U-ND/U-HD 12 UNIVERSAL steam boiler U-MB 16 UNIVERSAL steam boiler UL-S/UL-SX 20 UNIVERSAL steam boiler ZFR/ZFR-X 24 Self-fired waste heat boiler 26 UNIVERSAL heat recovery steam boiler HRSB 27 Series UL-S and UT-H as waste heat boilers 28 Boiler control BCO 29 Service 30 References middle of 2012 the systems were sold .
boiler interlocks in addition to closed loop fully modulating controls required for the normal operation of the boilerrequired for the normal operation of the boiler , interlock controls are required for the safe startinterlock controls are required for the safe start--up and shutup and shut--down of the boiler.down of the boiler. the following are some of the interlocks used forthe following .
