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TECHNICAL BOILER TRAINING. Introduction. Water is the raw material most used in nearly all industries. US industry uses about 140 billion gallons per day. The Water Molecule. Oxygen and hydrogen share electrons - this is called covalent bonding. The bond angle is 105 degrees. H. O. - PowerPoint PPT Presentation
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TECHNICAL BOILER TRAINING
IntroductionWater is the raw material most used in nearly all industries.
US industry uses about 140 billion gallons per day.
Refinery Water Uses
Area
Per Cent
Boiler Make Up
Cooling Tower Make Up
Process Make Up
Desalter Make Up
Sanitary & Lab
30%
60%
1%
4%
4%
The Water MoleculeOxygen and hydrogen share electrons - this is called covalent bonding.
The bond angle is 105 degrees.
105 degHHO
The Hydrologic Cycle
FUNDAMENTALS OF AVAILABLE WATERSURFACE WATERLower in dissolved solidsHigher in suspended solidsQuality changes quickly with seasons and weatherGROUND WATERHigher in dissolved solidsLower in suspended solidsHigher in iron and manganeseLow in oxygen, may contain sulfide gasRelatively constant quality and temperature
Basic Water Chemistry
FOUR IMPORTANT CHEMICAL PROPERTIES OF WATER ARE:
1. Conductivity2. Hardness 3. Alkalinity 4. pH
CONDUCTIVITYA Measure of the Total Dissolved Solids (TDS) in the Water. Read in S/cm
Approximation:ppm TDS x 1,8 = S/cm
HARDNESSThe amount of Calcium and Magnesium ions in the waterTotal hardness and Ca-hardness
Read in ppm CaCO3
Water - the Universal SolventWater is a poor conductor of electricity.
As more ions dissolve, water becomes a better conductor.
Water - the Universal SolventThis phenomenon is used to indicate total dissolved solids.
ALKALINITYCarbonate or Bicarbonate Ions that Can Cause Scaling Problems together with Ca, Mg Ions.
Read in ppm CaCO3
Acid - Base ChemistryThe most common buffering system encountered in industrial plants is the carbonate buffering system.
pH
Acid - Base ChemistryThe actual distribution of carbonate speciesCO2HCO3-CO3=Carbonate Buffering System0102030405060708090 10000.81.62.43.244.85.66.47.288.89.610.411.21212.813.6pHMolar ratioCO2HCO3-CO3=
Acid - Base ChemistryExpressing hydrogen ion concentrations:
pH = negative log molar concentration of H+
pHH+ Conc.51.0 ppb60.1 ppb70.01 ppb80.001 ppb
Water - the Universal SolventExpressing the levels of dissolved solids:
per cent - used for concentrated solutionsppm - a weight relationshipppm as CaCO3 - an equivalent weight relationshipmg/l - same as g/ml - in dilute waters, same as ppm
FUNDAMENTALS OF WATERSPECIFIC HEATis the measure of how well a substance can absorb heat 1 Kcal/kgC
VAPORIZATION HEATEnergy to transform liquid to gaseous970 Kcal/kg at 100C
PretreatmentFiltrationSoftenerDealkalizerReverse OsmosesDemineralizer Dearator
PRETRATMENTSOFTENER
Softener - Ion Exchange ProcessIon Exchange ResinWater
Four Steps of Softener RegenerationBackwash
Brining Slow Rinse
Fast Rinse
Ca, MgNa, Na
Boiler tube failuredue to scaling andoverheating of tubemetal over critical temperature for steel
This leads to partialdestroyed boiler sectionsand even boiler explosion
Deaeration:Water Temperature is Increased So That CO2 and O2 Are Released from the WaterWater is Broken Into Small DropletsCO2 and O2 Are Removed By Venting
Solubility of Oxygen vs Temperature and Pressure
Oxygen CausesPitting Attack of metal due to Oxygen CorrosionIncreased Iron content in condensate/boilerIncreases TDS in boilerCorrosion CellDearator
Pitting by Oxygen Corrosion
Spray Deaerator
Tray Deaerator
Venting Requirements for Tray Deaerators
Types of Deaerating EquipmentOpen feedwater heaters0.5 to 1 ppm O2Vacuum degasifiers 0.29 to 0.43 ppm O2 2 to 10 ppm CO2Deaerators and deaerating heaters0.04 ppm O2 for heater0.007 ppm O2 for deaerators95% of free CO2
Major ProblemsCorrosion Scale
Boiler CorrosionTypes of CorrosionOxygen corrosionAlkalinity concentrationCaustic corrosionAcid corrosionChelant corrosionErosion/Corrosion
Effect of pH on Boiler Corrosion
Effect of Scale on Heat Transfer
Effect of Scale on Tube Temperature
Scale ProblemsBoiler tube failure
Caused by reduced heat transfer and tube overheating
Under-deposit corrosion
Caused by high concentration of corrosive agents (usually NaOH)
Scale PreventionPrecipitation of hardness in the boilerReduce amount of hardness entering boilerKeep the hardness soluble
Treatment With Makeup SofteningRequirements for SuccessProper Operation and Maintenance of Make-up EquipmentChemical Conditioning for Residual Hardness
Process Objective To produce the required amount of Steam
To produce the required pressure Steam To produce the required purity Steam To produce Steam efficiently
How Is the Steam UsedHeat only Steam drives such as turbines Is process contamination a concern
The Generation of Steam Is Energy IntensiveNeed to minimize the amount of energy used Need to maximize efficiency of the boiler An understanding of how a boiler works and proper measurements can reduce energy usage.
Make-up WaterPrimary PretreatmentCondensateSteam HeaderBoilerDeaeratorChemical Feed SystemsFeedwaterBlowdownSecondary Pretreatment
Boiler:Produces SteamVariety of Shapes and SizesVariety of FuelsWide Range of Operating Pressures
Boiler CalculationsCalculations
Fire-Tube Boiler
Fire-Tube Boiler - Circulation
Water - Steam - Condensate System POTENTIAL PROBLEM
Why is CondensateNaturally Corrosive?Alkalinity in Boiler Breaks Down to CO2CO2 Leaves with SteamSteam Condenses with CO2 to Form Carbonic Acid
Why is Condensate corrosive?Alkalinity of BFW breaks down in Boiler Bicarbonate 2 NaHCO2 Na2 CO3 + CO2 + H2O Soda Na2 CO3 + H2O 2 NaOH + CO2 CO2 leaves with steam and reacts with condensed water droplets to Carbonic Acid CO2 + H2O H2 CO3 Carbonic acid Acid attack to metals low pH
% ConversionPressure (bar)Caustic
Typical Condensate CO2-Corrosion
Boiler Feedwater TreatmentINTERNAL TREATMENT
SCALE and DEPOSITS prevention
Phosphate Residual ProgramsBlend of Ortho- or Polyphosphate Chemically Remove Hardness from FeedwaterHelps Corrosion ProtectionPrecipitates Hardness and IronPO4-3 + Ca+2 Ca3(PO4)2 in combination with Organic Polymers Polymer Disperses Ca3(PO4)2 Sludge Keeps it from sticking to the Tubes
Chelant/Polymer ProgramsChemically Complexes HardnessPolymer Disperses IronContains EDTA or NTAKeeps Hardness from Forming Scale in BoilerImproves Boiler Cleanlinessif overfed aggressive to Metal surfaces!!!
(NTA3 + Ca+2 NTA Ca)Chelant maintains the Ions in a Soluble State thus:No Suspended Solides to Bake onto Boiler Tubes
Types of Sludge ConditionersSynthetic polymersTanninsLigninsStarches
Phosphate-Polymer ProgramsAdvantageCan provide much cleaner boilers than other conventional Phosphate programs DisadvantageRequires much stricter control of feedwater hardness and chemical program
Boiler Feedwater TreatmentOXYGENSCAVENGER andPASSIVATOR
Anorganic and Organic
SULFITE
Chemically reacts with oxygen (O2) to remove it from the boiler feedwaterReduces Corrosion PotentialDoes not form Magnetite no PassivationIncreases the TDS/conductivityFast reaction only if catalyzed
HYDRAZINEHYDRAZINE has long been the most applied Scavenger in Demi water systemsDoes not increase TDSPassivates Iron and Copper metallurgiesIs Slow reacting - does not protect sufficiantly: Condensate hot well and Preheaters Decomposes at high Temperature >340 oC, forming AmmoniaBad neutralization due to NH3 V/L distributionServe Cu corrosion in case of Oxygen inleakage Is Toxic and suspected Carcinogen (OSHA/NIOSH) at air levels attained in utilization areas
Carbon Dioxide SourcesBreakdown of feedwater alkalinity2 HCO3- CO3= + H2O + CO2 Bicarbonate Carbonate Water Carbon DioxideCO3= + H2O 2OH- + CO 2Carbonate Water Hydroxide Carbon Dioxide
Air inleakage
pH Values of Solutions of Carbon Dioxide in Pure Water at Various Concentrations
Steam Traps
CONDENSATE TREATMENTNeutralizing and Filming Amines
Neutralizing AminesNeutralize Carbonic Acid to protect condensate systems from corrosive AttackMinimize Condensate Corrosion also in large condensate systems - Mixture! Different Vapor/Liquid distribution ratioKeep condensate pH between 8.5 and 9.0Reduce Iron levels in condensate return
Filming/Neutralizing AmineIncrease low condensate pHProtect when large amounts of Carbonic Acid are presentEffective between pH of 6.5 - 9.0Provide protection from Oxygen AttackHelp prevent Iron/Copper deposits in boiler system
Oxygen Corrosion in Condensate line
Filming AmineRepels condensate water droplets from surface and protects againstCO2 and O2
Optimum OperationWater & Fuel Cost
Water CostCity Water Cost: 1.00 L.E
Soft Water Cost: 1.25 L.E
Salt, water required for regeneration, resin replacement , depreciation
Fuel
Fuel Type: Natural gas (NG)
Calorific Value :8900-10700 Kcal/m3
Price: 0.18 L.E/m3
Cost of MM Kcal: 18 L.E
data
Energy Saving
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
Concentartion Number (Nc)5101520
% Condensate Retrun45607590
Calculations
Nc = TDS of Boiler Blowdown/TDS of Feed water
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Feed = Steam Production X Nc/Nc-1 (3)
Blowdown = Steam Production X 1/Nc-1 (4)
B.D
Energy Saving due to Blowdown
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
Concentartion Number (Nc)5101520
Nc = TDS of Boiler Blowdown/TDS of Feed water
Feed = Steam Production X Nc/Nc-1 (3)15000.0013333.3312857.1412631.58
Blowdown = Steam Production X 1/Nc-1 (4)3000.001333.33857.14631.58
Energy Losses Due to Blowdown2,550,000.001,133,333.33728,571.43536,842.11
kcal required for producing steam at 12 Bar850
L.E Cost for MM kcal18
Fuel losses due to B.D in 24 hours1101.60489.60314.74231.92
Water cost due to B/D per day90.0040.0025.7118.95
Total Losses L.E/day1191.60529.60340.46250.86
Cond.
Energy Saving due to Increasing Condensate Return
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
% Condensate Retrun45607590
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Condendate Return m3/hr5400.007200.009000.0010800.00
Make up water m3/hr6600.004800.003000.001200.00
Energy requied to rasise temp from 25 to 100 oC7549500036000022500090000
Energy Losses L.E/day213.84155.5297.2038.88
Make up water cost per day198.00144.0090.0036.00
Total Losses L.E/day411.84299.52187.2074.88
Sheet4
Sheet2
Calculations
Nc = TDS of Boiler Blowdown/TDS of Feed water
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Feed = Steam Production X Nc/Nc-1 (3)
Blowdown = Steam Production X 1/Nc-1 (4)
Sheet3
data
Energy Saving
Boiler Data
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
Concentartion Number (Nc)5101520
% Condensate Retrun45607590
Calculations
Nc = TDS of Boiler Blowdown/TDS of Feed water
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Feed = Steam Production X Nc/Nc-1 (3)
Blowdown = Steam Production X 1/Nc-1 (4)
B.D
Energy Saving due to Blowdown
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
Concentartion Number (Nc)5101520
Nc = TDS of Boiler Blowdown/TDS of Feed water
Feed = Steam Production X Nc/Nc-1 (3)15000.0013333.3312857.1412631.58
Blowdown = Steam Production X 1/Nc-1 (4)3000.001333.33857.14631.58
Energy Losses Due to Blowdown2,550,000.001,133,333.33728,571.43536,842.11
kcal required for producing steam at 12 Bar850
L.E Cost for MM kcal18
Fuel losses due to B.D in 24 hours1101.60489.60314.74231.92
Water cost due to B/D per day90.0040.0025.7118.95
Total Losses L.E/day1191.60529.60340.46250.86
Cond.
Energy Saving due to Increasing Condensate Return
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
% Condensate Retrun45607590
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Condendate Return m3/hr5400.007200.009000.0010800.00
Make up water m3/hr6600.004800.003000.001200.00
Energy requied to rasise temp from 25 to 100 oC7549500036000022500090000
Energy Losses L.E/day213.84155.5297.2038.88
Make up water cost per day198.00144.0090.0036.00
Total Losses L.E/day411.84299.52187.2074.88
Sheet4
Sheet2
Calculations
Nc = TDS of Boiler Blowdown/TDS of Feed water
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Feed = Steam Production X Nc/Nc-1 (3)
Blowdown = Steam Production X 1/Nc-1 (4)
Sheet3
data
Energy Saving
Boiler Data
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
Concentartion Number (Nc)5101520
% Condensate Retrun45607590
Calculations
Nc = TDS of Boiler Blowdown/TDS of Feed water
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Feed = Steam Production X Nc/Nc-1 (3)
Blowdown = Steam Production X 1/Nc-1 (4)
B.D
Energy Saving due to Blowdown
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
Concentartion Number (Nc)5101520
Nc = TDS of Boiler Blowdown/TDS of Feed water
Feed = Steam Production X Nc/Nc-1 (3)15000.0013333.3312857.1412631.58
Blowdown = Steam Production X 1/Nc-1 (4)3000.001333.33857.14631.58
Energy Losses Due to Blowdown2,550,000.001,133,333.33728,571.43536,842.11
kcal required for producing steam at 12 Bar850
L.E Cost for MM kcal18
Fuel losses due to B.D in 24 hours1101.60489.60314.74231.92
Water cost due to B/D per day90.0040.0025.7118.95
Total Losses L.E/day1191.60529.60340.46250.86
Cond.
Energy Saving due to Increasing Condensate Return
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
% Condensate Retrun45607590
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Condendate Return m3/hr5400.007200.009000.0010800.00
Make up water m3/hr6600.004800.003000.001200.00
Energy requied to rasise temp from 25 to 100 oC7549500036000022500090000
Energy Losses L.E/day213.84155.5297.2038.88
Make up water cost per day198.00144.0090.0036.00
Total Losses L.E/day411.84299.52187.2074.88
Sheet4
Sheet2
Calculations
Nc = TDS of Boiler Blowdown/TDS of Feed water
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Feed = Steam Production X Nc/Nc-1 (3)
Blowdown = Steam Production X 1/Nc-1 (4)
Sheet3
data
Energy Saving
Boiler Data
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
Concentartion Number (Nc)5101520
% Condensate Retrun45607590
Calculations
Nc = TDS of Boiler Blowdown/TDS of Feed water
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Feed = Steam Production X Nc/Nc-1 (3)
Blowdown = Steam Production X 1/Nc-1 (4)
B.D
Energy Saving due to Blowdown
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
Concentartion Number (Nc)5101520
Nc = TDS of Boiler Blowdown/TDS of Feed water
Feed = Steam Production X Nc/Nc-1 (3)15000.0013333.3312857.1412631.58
Blowdown = Steam Production X 1/Nc-1 (4)3000.001333.33857.14631.58
Energy Losses Due to Blowdown2,550,000.001,133,333.33728,571.43536,842.11
kcal required for producing steam at 12 Bar850
L.E Cost for MM kcal18
Fuel losses due to B.D in 24 hours1101.60489.60314.74231.92
Water cost due to B/D per day90.0040.0025.7118.95
Total Losses L.E/day1191.60529.60340.46250.86
Cond.
Energy Saving due to Increasing Condensate Return
Boiler Pressure12 Bar
Steam Production kilos/hr12000
Fuel TypeNatural gas
Fuel Cost L.E/M30.18
Make Up water TypeSoft Water
Water Cost L.E/M31.25
% Condensate Retrun45607590
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Condendate Return m3/hr5400.007200.009000.0010800.00
Make up water m3/hr6600.004800.003000.001200.00
Energy requied to rasise temp from 25 to 100 oC7549500036000022500090000
Energy Losses L.E/day213.84155.5297.2038.88
Make up water cost per day198.00144.0090.0036.00
Total Losses L.E/day411.84299.52187.2074.88
Sheet4
Sheet2
Calculations
Nc = TDS of Boiler Blowdown/TDS of Feed water
Make up + Condensate Return = Feed (1)
Steam Production + Blowdown = Feed (2)
Feed = Steam Production X Nc/Nc-1 (3)
Blowdown = Steam Production X 1/Nc-1 (4)
Sheet3
More SavingsWhere and Why
Thank You & Good Luck
Effect of Scale - Example