Structure of a company's energy system Supply Conversion Distribution Consumption Heat recovery Disposal
Energy efficiencyTypical areas of improvement • Cooling/refrigeration • Heating • Compressed air • Insulation • Heat recovery • Separation processes • Lighting • ...
Efficient energy use Not only a question of best technology!
Energy management • Organization Set up an organizational unit, identify responsibilities and determine the budget • Analysis and Inventory and descriptionPlanning of the energy situation search for energy saving options • Control Control of the energy plants, work out energy indicators • Consulting Energy reports, internal consulting and market analysis • Implementation Implementation of energy saving options maintenance of energy plants
Documentation of load curves Analysis of load curves • Winter – summer ratio • Combined use of heat and power • Switched off or reduced operation at weekends • Days with high energy demand • Bottlenecks • Energy demand after production Documentation of curves for • A year • A week • A day
Collection and documentation for all energy carriers Quantity Cost Reference quantities Definition of indicators Analysis and interpretation Distribution of quantities Distribution of costs Variation of indicators Comparison of indicators with other companies or publications Annual energy consumption
Analysis of consumers • Electric power • Avoid partial load and use adequate machines • Adapt power (e. g. fans) • Optimize lights (cleaning, modern lighting, analyse demand) • Clean and service (air filter, nozzles, etc.) • Compressor location and pressure • Peak load management Heat • Thermostatic valves • Separate control of plants • Adequate temperatures • No internal sources of heat and humidity in cooled areas • Use shades for heat protection • Frequency-controlled fans • Use heat cascades • ...
Specific energy consumption Example: Energy consumption of a brewery Indicator: MJ/hl Measure: June 1992 Installation of a vapour recompression plant 150 125 100
Energy, work and power • Work is the transmission of energy. • The unit of work and energy is JOULE. • The speed at which work is performed is power [J/s = W].
Heat capacity To heat up a body with a mass of m by DT, the following amount of heat is required: Q = c m DT The specific heat capacity c of the material depends on the temperature. The specific heat capacity is the amount of energy required to heat up 1 kg of material by 1 °C. Unit: [c] = 1 J.kg-1.K-1 Specific heat capacity Gold Iron Oxygen Benzene Water
The performance of 1 kWh • Lifts 1 ton of steel by 367 m! • Accelerates a car (1 ton) to approx. 60 km/h (without losses 305 km/h)! • Heats up 1 000 l of water by 0.86 °C! Source: Karl Lummerstorfer, Energie Institut Linz
Part of the steam system Efficiency Steam boiler (70-) 82 – 90% Steam transportation 75 – 90% Heat exchange 85 – 98% Efficiency in a steam system
Steam system • Reduce leaks. • Improve operation of steam traps. • Increase condensate recovery. • Increase flash steam recovery. • Use lower steam pressure if possible. • Use direct steam for heating if possible.
Cooling process Efficiency = Qcond. / P ~ Tcond. / (Tcond. – Tevap.) Q: Heat P: Power T: Temperature Consequences: • The lower the temperature difference the better: • Check the necessary cooling temperature • Allow the temperature in the condenser to be as low as possible (e.g. water cooling) • Maintain the heat exchanger (especially evaporator) • ... • The higher the cooling temperature the better • Others: • Remove water from ground • Avoid high temperature of the incoming product • ...
P M Qu = Qo + P Compressor Qo Qu Evaporator Condenser To Tu Collector Low pressure High pressure Efficiency = Qo / P = To / (Tu – To) Cooling process
Cooling and freezing • Raising the cooling temperature by 1 °C saves approx. 4% of electric energy. • Choose the adequate temperature: frozen meat at -20 °C, cooling at 0 °C to 4 °C. • Clean the condenser regularly and provide sufficient cool air supply. • Use the capacity of the storage rooms, collect goods, switch off unused cooling units. • Keep storage rooms closed to avoid entrance of humidity and warm air. • Defrost cooling rooms.
Cooling – 2 • Insulation • Recommendations for PU-foam insulation: Insulation thickness • Evaporator: • Optimize defrosting • Compressor • Close to evaporator • Central location makes servicing and use of heat easier • Condenser: • Outside of building, sun-protected • Clean regularly • Use R134 a, R22 or ammonia 0 to -8 °C 0 to -15 °C below -15 °C 80mm 110mm 150mm
Q1 Q4 8 Q3 Q2 Ti Td To QT Drying process • Fresh air drying • Fresh air drying with heat recovery • Circulating air drying with/without heat recovery • Heat recovery with condensation of humidity (heat pumps, thermo-compression) Typical options for improvement: Q1 = Insulation of drier Q2 = Pre-drying, pre-concentration of the product Q3 = Control of temperature and humidity Q4 = Heat recovery, humidity control of flue gas, good housekeeping
Compressedair • Shut down compressor, drier and the network • Reduce the pressure level(as far as possible) • Avoid leakages • Lower the temperature of incoming air • Avoid compressed air for cleaning • Carry out maintenance • Use electrically-driven equipment • Foster heat recovery Source: Karl Lummerstorfer, Energie Institut Linz
Lighting • Turn off when not needed • Use timer or motion detector • Use daylight as much as possible • Service and clean • Clean windows, ensure efficientdesign of rooms • Use energy saving bulbs
Air-cooled condenser Water-cooled condenser Evaporator Compressor Heat recovery cooling units – 1
ECOPROFIT-company: BreweryAnnual production: > 1 million hl, ISO 14000 • Saving of water, energy and chemicals due to CP options:Cold filtering/sterilizationNew filling lineHeat/power co-generationVapour compression ...
Specific heat consumption of a brewery 50.00 40.00 30.00 in kWh/hl 20.00 10.00 0.00 1993 1994 ´95 ´96 ´97 ´98 ´99 2000 2001 2002 38.60 40.67 47.30 42.62 41.42 37.56 34.19 29.91 27.58 24.47 spec. heat
Multistage evaporation 1. evaporator 2. evaporator 3. evaporator condenser 1. vapour 2. vapour 3. vapour vacuumpump feed steam finalconcentrate 1. concentrate 2. concentrate steamcondensate 1. vapourcondensate 2. vapourcondensate 3. vapourcondensate Source: Ignatowitz 1994
Evaporation with vapour compression vapour evaporator preheated feed steam(start-up) pre-heater compressor vapour- condensate feedsolution concentrate Source: Ignatowitz 1994