Energy Management and Utilization in Food Plants ( Dr. Mustafa BAYRAM )

FE 467 FOOD PLANT DESIGN ENERGY MANAGEMENT AND UTILIZATION IN FOOD PLANTS

Prof. Dr. Mustafa BAYRAM University of Gaziantep Faculty of Engineering Department of Food Engineering Gaziantep/TURKEY

NOTE: From FE 366 DON’T FORGET • This semestry you have to prepare PID drawing • P&ID Diagram(YOU WILL DRAW THIS FOR YOUR PROJECT (Fe 467 Design II) The details of PID will be learned at FE 403 Food Process Control

ENERGY SOURCES • Liquids • Petrolium (Fuel oil-No:5 «Kalyak» or 6) • Waterdam (hydroelectric centralàelectiricty) • Ethly alcohol • Gas – LPG (Liq. petrolium gas: Propane+Butane «butane is heavy/high dense à red/ash fire)» – Natural gas – Hidrogen gas – Biogas (methane) • Solid • Coal • Solid waste • Wood

ALTERNATIVE ENEGRY SOURCES

Sun Wind Biomass Hydrogen Sea wave etc

Sun as an energy source • Sun collectors • Sun batteries • To produce; – Hot water – Steam – Electricity – Heated air Sun rock dryer (covered black dye or asphalt)

Wind • To produce electicity • Using wind turbine

Selection of energy sources • How can we select energy source? – Maintenance (coal needs more laboring, cleaning etc.) – Reparing – Calori value – Service life of heat converter machine – Economy (price, inflation etc.) – Availability – Constant price-constant supply – Waste and enviromental issue (coal ?) – Goverment policy and laws

Energy usage in the plant • For lighting (electiricty) • For motor power /Mechanical drive • Process Heating • Conditioning (indoor) (heating area etc.) • Air heating • Water heating • Steam generation (small scale) • Superheated steam • Material processing (cooking, pasteurization, sterilization, heatin of material, roasting etc.) • Cooling • Air • Water • Etc. • Space heating

Electricity sources in the plant • Energy Converter/Central •Natural gas central/converter •Coal central/converter •Water dam •Fuel/motorin central/convert

Electricity usage • In city • 220 V, 50 mHz (in Turkey, Europe etc.) • 110 V, 60 mHz (in USA) • 1-2 phases • Power (P, Watt): V (voltage) * I (ampere) • Energy consumption (E, kWh)= P * t (time) • In industry • 380 V , 50 mHz (in Turkey, Europe etc.) • 460 V, 60 mHz (in USA) • 3 phases • Power (P, Watt): V (voltage) * I (ampere) * √3 * Cos Ø • Energy consumption (E, kWh)= P * t (time)

Plug wires – colours Live – brown Neutral – blue Earth – green/yellow Fuse in live position

AC / DC Electricity So, in general, in industry, AC motor is used. Why??

In Turkey, 220 V in home

Three phases electricty

Utility Transmits at high voltage to reduce line losses 480, 600, 1K, 10K Vac Reduces voltage to useable levels Distributes current and protects circuits 120, 208, 277 Vac Heating cable Transformer Subpanel with circuit breakers generate heat

Decision and calculation: Energy/calori examination table: (Source: www.dosider.org)

Natural gas (pipeline in Turkey)-

Availabity of Natural gas in Cities

CONVERSION OF ENERGY

• For – Air heating – Water heating – Steam – Etc.

HEATING IN THE PLANT

Direct air heating Direct water heating Indirect air heating Indirect water heating

1- Direct air heating • A) Electricity (by using electrical resistance) – To process in duct/pipe + Cold air inlet Hot air outlet Resistant

B-Thermoblock (burner type) i-Ordinary thermoblock

ii-Turbo type thermoblock (back-pressure)

iii-Turbo type thermoblock (back-pressure)/ No Chimney

Indirect air heating

Circulating Air Systems • Heat distributed by an air stream through a heating unit to supply ducts • duct< 200’

2- WATER HEATING Direct and indirect 1. Direct

2.Indirect

Water Systems cooling tower off Heat is distributed by a pumped water system though a heating unit to supply piping boiler on Different piping arrangements are used – Hydronic Piping

INDUSTRIAL STEAM GENERATION

Sensible and Latent Heat • Sensible heat causes a change in temperature • Latent heat causes a change of state but no change in temperature

Calculation hints • Use Lower Heating Value (LHV) for energy source – The quantity known as lower heating value (LHV) (net calorific value (NCV) or lower calorific value (LCV)) is determined by subtracting the heat of vaporization of the water vapor from the higher heating value. This treats any H O formed as a vapor. The energy 2 required to vaporize the water therefore is not released as heat. – LHV calculations assume that the water component of a combustion process is in vapor state at the end of combustion, as opposed to the higher heating value (HHV) (a.k.a. gross calorific value or gross CV) which assumes that all of the water in a combustion process is in a liquid state after a combustion process. – The LHV assumes that the latent heat of vaporization of water in the fuel and the reaction products is not recovered. It is useful in comparing fuels where condensation of the combustion products is impractical, or heat at a temperature below 150°C cannot be put to use. – Higher heating value (HHV) (or gross energy or upper heating value or gross calorific value (GCV) or higher calorific value (HCV)) is determined by bringing all the products of combustion back to the original pre-combustion temperature, and in particular condensing any vapor produced. Such measurements often use a standard temperature of 25°C. This is the same as the thermodynamic heat of combustion since the enthalpy change for the reaction assumes a common temperature of the compounds before and after combustion, in which case the water produced by combustion is liquid.

Latent Heat of Evaporation 100 C 100 C • Evaporator: liquid changing to gas • Condenser: gas changing to liquid • It takes 180 Btu’s to raise the temperature of 1 lb. of water from 32 deg. to 212 deg. (100 C). • It takes 970 Btu’s to boil or vaporize 1 lb. of water at 212 deg. (100 C).

Training Agenda: Steam Introduction Steam distribution system Assessment of steam distribution system Energy efficiency opportunities

Introduction What is steam – Dryness fraction • Dry saturated steam: T = boiling point • Steam: mixture of water droplets and steam • Dryness fraction (x ) is 0.95 if water content of steam = 5% • Actual enthalpy of evaporation = dryness fraction X specific enthalpy hfg

Introduction • After obtaining saturated steam Saturated and super heated steam (in general it is used in all heating operation in food industry), saturated steam is heated with electirical resistant Superheated steam or hot oil or hot surface to obtain superheated steam (it is Sub-saturated water used for deodorization etc.)

Introduction Steam quality Steam should be available • In correct quantity • At correct temperature • Free from air and incondensable gases • Clean (no scale / dirt) • Dry

Classes of Steam • Low Pressure Heating Steam – 15 psig – Used Mainly for Space Heating Systems and Single Effect Absorption Chillers – Actual Code is More Restrictive • Medium Pressure Steam: 15-150 psig – Used in Hospitals, District Steam Systems, Some Industrial Heating • High Pressure: Above 150 psig – Strictly Industrial and Power Generating Applications • Each Class has Piping and Valve Requirements – Increase in Expense with Each Higher Class

Steam System Operation • Generation • Distribution • End Use • Condensate Recovery & Feed Water Systems

Steam Circle System Loads Radiators, Sterilizers Heat Exchangers, etc Steam Header Steam Traps BOILER Condensate Return Piping (Treated) Make up water Deaerator Condensate Return Tank

Generation • Boilers – Fire-tube or water-tube • Heat recovery generators – Turbine exhaust – Furnace exhaust Typical Boiler

Generation (2 types) • Water tube – fuel burned within combustion chamber – combustion gas surrounds water tubes within vessel • Fire tube – fuel burned in combustion chamber – combustion gases flow through tubes – water surrounds tubes – Scotch Marine – most popular Fire tube 44

Distribution & End Users • Distribution Systems – Distribution lines – Pressure reduction • Pressure reduction valve • Backpressure turbine • End Use Components – Heat exchangers – Mechanical drives – Steam sparging/injection equipment 45

Recovery & Feed Water • Condensate Recovery System – Steam traps – Collection tanks – Flash steam recovery – Pumps • Feed Water System – Deaerator – Economizer 46

BOILER EFFICIENCY HEAT LOSS METHOD BOILER EFFICIENCY = 100 – % AGE LOSSES 1. Heat Loss in Dry flue gas a. H = 0.24 w (T – T ) as percentage of heat input g g g a G.C.V a. H = K (T – T ) /1.8 K=0.32 for fuel oil g g a % CO2 in flue gas K=0.35 for Bituminous coal 2. Heat loss due to evaporation of moisture & H2 in fuel H = W +9H (100 – T ) + 540 – 4.6 (T – 100) %of heat input m m f g G.C.V 3. Heat loss due to moisture in air H = 0.26 W (T – T ) % of heat input a ma g a G.C.V 4. Heat loss due to Incomplete combustion to Co Hco = 2414 C x CO x 1 as % of heat input CO+CO2 G.C.V 5. Heat loss due to unburnt carbon “C” Hc = Wc x 7831 as % of heat input G.C.V

6. Heat loss due to Blow Down H = W (h – h ) as % of heat input bd b bw w G.C.V 7. Heat loss due to Radiation HR = Difficult to evaluate & thus take design values only In above Wg =Wt of dry flue gas W..G = [44.01 *CO2 + 32*O2 28.02 * N2 + 28.01*CO]*[Cb + 12.01 * S/32.07] 12.01 * (CO2 + CO) Tg = Tempt. Of flue gas at exit of Boiler Ta = Tempt. Of air at inlet (ambient) Tf = Tempt. Of fuel inlet h -h = Heat in blow down bw w Wm = Weight of moisture Wma = Wt of waterin Kg/Kg of air X Wt of air in Kg supplied / Kg of fuel Wc = Weight of unburnt “C” W = Wt of water blow down b All wts are / kg of fuel

Training Agenda: Steam Introduction Steam distribution system Assessment of steam distribution system Energy efficiency opportunities

Steam Distribution System Most important components 1. Pipes 7. Steam traps 2. Drain points 8. Air vents 3. Branch lines 9. Condensate 4. Strainers recovery 5. Filters system 6. Separators 10. Insulation

Steam Distribution System 1. Pipes • Pipe material: carbon steel or copper • Correct pipeline sizing is important • Oversized pipework: – Higher material and installation costs – Increased condensate formation • Undersized pipework: – Lower pressure at point of use – Risk of steam starvation – Risk of erosion, water hammer and noise • Size calculation: pressure drop or velocity

Steam Distribution System 1. Pipes • Pipeline layout: 1 m fall for every 100 m • Apply 5 degree angle for piping to remove/sliding condense (Spirax Sarco)

Steam Distribution System 2. Drain points Trap Pocket too small (Spirax Sarco)

Steam Distribution System 2. Drain points Properly Sized Trap Pocket (Spirax Sarco)

Steam Distribution System 3. Branch lines • Take steam away from steam main • Shorter than steam mains • Pressure drop no problem if branch line < 10 m A Branch Line (Spirax Sarco)

Steam Distribution System 3. Branch lines Branch line connections – Top: driest steam – Side or bottom: accept condensate and debris (Spirax Sarco)

Steam Distribution System 4. Strainers • Purpose – Stop scale, dirt and other solids – Protect equipment – Reduce downtime and maintenance • Fitted upstream of steam trap, flow meter, control valve • Two types: Y-type and basket type

Steam Distribution System 5. Filters • Consists of sintered stainless steel filter element • Remove smallest particles – Direct steam injection – e.g. food industry – Dirty stream may cause product rejection – e.g. paper machines – Minimal particle emission required from steam humidifiers – Reduction of steam water content

Steam Distribution System 6. Separators • Separators remove suspended water droplets from steam • Three types of separators Cyclonic type Coalescence type Baffle type

Steam Distribution System 7. Steam traps • What is a steam trap? – “Purges” condensate out of the steam system – Allows steam to reach destination as dry as possible

Steam Distribution System 8. Air vent – location • Within low lying steam trap opposite high level steam inlet • Opposite low level steam inlet • Opposite end of steam inlet

Steam Distribution System 9. Condensate recovery system • What is condensate – Distilled water with heat content – Discharged from steam plant and equipment through steam traps • Condensate recovery for – Reuse in boiler feed tank, deaerator or as hot process water – Heat recovery through heat exchanger

Steam Distribution System 10. Insulation • Insulator: low thermal conductor that keeps heat confined within or outside a system • Benefits – Reduced fuel consumption – Better process control – Corrosion prevention – Fire protection of equipment – Absorbing of vibration – Protects staff: hot surfaces, radiant heat

Steam Distribution System 10. Insulation Classification of insulators Temperature Application Materials o Low (<90 C) Refrigerators, cold / hot Cork, wood, 85% water systems, storage magnesia, mineral fibers, tanks polyurethane, expanded polystyrene Medium (90 – Low-temperature 85% magnesia, asbestos, o 325 C) heating and steam calcium silicate, mineral generating equipment, fibers steam lines, flue ducts, o High (>325 C) Boilers, super-heated Asbestos, calcium silicate, steam systems, oven, mineral fibre, mica, driers and furnaces vermiculite, fireclay, silica, ceramic fibre

Steam Distribution System Steam System Schematic

Example 1 Typical steam circuit

Example 2 –

Training Agenda: Steam Introduction Steam distribution system Assessment of steam distribution system Energy efficiency opportunities

Assessment of Steam Distribution System Three main areas of assessment • Stream traps • Heat loss from uninsulated surfaces • Condensate recovery

Training Agenda: Steam Introduction Steam distribution system Assessment of steam distribution system Energy efficiency opportunities

Efficient Steam Systems • Proper performance yields – Low operating costs – Minimal downtime – Reduced emissions – Effective process control • Effective maintenance is the best strategy!!

Energy Efficiency Opportunities 1. Manage steam traps 2. Avoid steam leaks 3. Provide dry steam for process 4. Utilize steam at lowest acceptable pressure 5. Proper utilization of directly injected steam 6. Minimize heat transfer barriers 7. Proper air venting 8. Minimize waterhammer 9. Insulate pipelines and equipment 10. Improve condensate recovery 11. Recover flash steam 12. Reuse low pressure steam

Why make a change? INEFFICIENT STEAM SYSTEM

Why make a change? EFFICIENT STEAM SYSTEM

Co-generator • To produce • Electricity • Hot water or steam From the engine

FOR PRESENTATION AND REPORTS • Show steam/hot water pipeline and ALL components • Calculate required steam/hot water for each machine separately • Calculate total steam/hot water quantity • Calculate total steam/hot water calories • Calculate total natural gas/electiricty/coal etc. «as energy source» quantity per hour, day, year and use them in feasibilty survey • Calculate boiler efficiency • Show in a table for; • Electricity • Energy

SOME IMPORTANT POWER CALCULATIONS FOR MOTOR/EQUIPMENT

EXAMPLES HOME STUDIES (SOME EXAM QUESTIONS) 1-Draw flow-diagram of a steam system, which includes the following components (use full page of your answer book, drawing is important, no partial grade will be given in this question) Pasteurizator (in parallel process) Jacketed tank (in parallel process) Steam distributor/head Steam traps Steam filters Condense tank Deaerator Water make-up/soft water system Pipes + Inclined pipes Air vents Valves Branch lines FLOW DIAGRAM !!!!!

2-In a food plant, overall steam requirement of the system is 5000 kg steam/hr at 120 C saturated steam. The efficiency of steam generator found in the plant is 85%. Condensed steam return at saturation temperature to the steam generator. According to following table, what quantity of the cheapest energy source is required (show all calculations)? Energy Source Heat value Unit cost Burning Efficiency Coal (C) 6500 kcal/kg 0.220 (TL/kg) 69% 3 3 Natural Gas (N) 8250 kcal/m 0.297 (TL/ m ) 93% Fuel-oil (No: 6) (F) 9200 kcal/kg 0.508 (TL/kg) 83%

Energy Burning TL/1000 Heat value Unit cost Source Efficiency kcal C 6500 0.220 0.69 0.0491 N 8250 0.297 0.93 CHEAPEST 0.0387 F 9200 0.508 0.83 0.0665 Natural gas is the cheapest: Required amount of natural gas: Real energy: 8250*0,93 = 7672,5 kcal/m3 3099620,04 kcal/h / 7672,5 kcal/m3 = 403,99 m3/h natural gas required.

(10 pts) Draw a steam generation and utilization system (in your drawing, show burner, steam generator, valves, termocouple, filters, piping, steam traps, one heating equipment/heat exchanger, condense tank, water treatment, flash etc),

1. (5 pts) Which energy source is the best according to following table? Energy source Energy value Unit price Burning yield (%) Diesel (Motorin) 10256 kcal/kg 2.805 TL/kg 84 Electricity 860 kcal/kWh 0.183 TL/kWh 99 Fuel oil (No:6) 9562 kcal/kg 0.95 TL/kg 80 Local Soma coal 4640 kcal/kg 0.348 TL/kg 65 LPG 11000 kcal/kg 3.100 TL/kg 92 3 3 Natural gas 8250 kcal/m 0.820 TL/m 93 Fe 478 Dr. Mustafa BAYRAM


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