04 Cross Sectional Technologies

1. Political and social target —> GHG emissions reduction

2. Industrial target: Savings of energy costs

Holistic approach of energy efficiency

—> Optimization of the inputs (Natural Gas and Electricity)

—> Optimization on industrial plant level

Green field

• Rare in practice

• Fundamental new ideas with high energy savings

• Solutions often not feasible for integration as retrofits

Brown field

• Usually in practice

• Solutions often not technical feasible (e. g. lack of installation space)

• Solutions often not economic feasible (e. g. high costs, high production loss)

—> In practice most plants are already build —> Realization: Retro fits and brown field approaches

—> Can be found in every industrial plant

—> Therefore energy efficiency concepts have a high impact

• Drives, pumps and ventilators

• Lighting

• Mechanical motion

• HVAC

• Supplying thermal energy (process heating and cooling)

• 70 % of industrial electricity demand

• > 90 % of life cycle costs due to elecricity

• Classifications by International Electrotechnical Commission (IEC) —> new

  and Committee of Manufacturers of Electrical Machines (CEMEP) —> old

• Efficiencies: Super premium, premimium,…. worse than state of the art

Energy Conversion

• Higher complexity —> higher investment and maintenance costs

• Main influence on efficiency and energy costs —> system design and control strategy

• Runtime: 3000 h/a over 7 years

Throttle valve control

—> Full load: Efficiency 67 %

—> Part load: Efficiency 13 %

Variable speed drive

—> Full load: Efficiency 63 %

—> Part load: Efficiency 45 %

Types (after efficacy)

• LED (200 lm/W)

• Metal halide (150 lm/W)

• Fluorescent

• CFL

• Mercury

• Halogen (25 lm/W)

• Incadescent

Increasing potential of various measures

Fluorescent lamp with…

1. conventional ballast (initial state)

2. low-loss ballast (initial state)

3. electronic ballast

4. dimmable electronic ballast + day light control system

5. dimmable electronic ballast + day light control system + motion detector to verify presence

—> Also saving potentials from T8 (26 mm) to T5 HE (16 mm)

• Compressed air

• Electromechanical linear motors

• 7 % of the industrial electricity demand

Definitions of pressure

—> Absolute pressure: measured from absolute zero and relevant for all theorectical considerations

—> For industrial praxis: Measure gage pressure to atmospheric pressure is relevant

Composition of costs

Tools

• Progress automation based: Pneumatic tools —> Linear or rotatory cylinders

• Very low investment costs

• Applied in explosion safe zones

Usable energy

• Very low efficiency in relation to the applied final energy

• 13 % of the input energy is usable mechanical energy

• Losses: Motor, compression, cooling,…

System Design

• Temperature change of + 10 K —> 2 - 4 % more energy input

• Target pressure drop

  • Treatment: < 0,6 bar

  • Pipe system: < 0,1 bar

  • Connection accessories: < 0,3 bar

• Pressure change of + 1 bar —> 6 - 10 % more energy input

• Audible leakages from 1 mm2 (annual costs of 500 €)

• Acceptable leakage losses

  • Max. 5 % for small networks

  • Max. 7 % for medium networks

  • Max. 10 % for large networks

  • Max. 15 % for very large networks

—> Potential for efficiency measurements: 33 %

—> Target should be optimization and substitution

• Optimization of compressor

• Usage of compressor’s waste heat

• Minimization of leakages

• Substitution of applications (electronic devices like linear motor)

+ Lower operating costs

+ Simple installation only electricity needed

+ Compact

- Less robust

- Higher investment costs

- Not explosion proof

Layers

• Heat recovery

• Energy storage

• Industrial Utilities

• Thermal Energy = Heat and cold

• Pinch Analysis —> Tools for analyzing and optimizing thermal systems

Pinch analysis

—> Provides theoretically possible potential for heat integration —> Often technical limitations

Stream

• Flow requires heat or cold —> don’t change composition

Cold stream

• Flow starts cold, needs heat

Hot stream

• Flow starts hot, needs cold

Reaction

• No stream

• Changes temperature and composition

Example

Composite Curve

1. External heat input above the pinch —> Because subsystem above the pinch has a heat deficit

2. External heat removal below pinch —> Because subsystem below the pinch has a heat surplus

3. No heat transfer across the pinch —> Or the heat is missing above the pinch and increases the heat deficit

• Furnace

• CHP

• Electrical heating

• Heat pump

• Compressed cooling machine

• Ab/Adsorption cooling machine

• High exergetic fuels for low exergetic heat production

• Fuel is burned —> Heat from flame and exhaust gas —> Water

• High temperature steam can be extracted —> Depends on the pressure

Exergy or Availability

= Amount of useful work you can get out of the system at a specified state by placing a reversible heat engine between it and the dead state

CHP —> 66 % better fuel usage

Types

• Motor - Generator

• Gas turbine - Generator

• ORC turbine - Generator

• Steam turbine - Generator

• Fuel cell

• Exergetic benefits

• Electricity as the main driver for economic values

• Heat is important for efficiency

• Emissions depends on the fuel

Immersion heating

• Resistor used

• Large scale water boiler

• Up to 200 °C

• Difficult control system, minimum power required

Electrode Type

• Electric current directly through water

• Up to 350 °C

• Easy to control through full bandwith of power

—> Heat and Cold

• Waste heat from the process —> transfered to a refrigerant

• Electric energy —> gaseous refrigerant gets compressed —> Increase of pressure and temperature

• Heat from refrigerant at high temperature —> Feed back into the process

• Thermodynamic integration is significant for efficiency

  
  

Process

• Ability to supply all year cooling with low flow temeratures

• Refrigerant gets evaporated at low pressure and low temperature

• Condensed above ambient temperature after compressing

• Types: Reciprocating, scroll, screw, turbo compressors —> increasing power range

Process

• Dissolves vapour in a liquid (the absorbent)

• Pumps the solution to a higher pressure in the regenerator

• Uses heat to evaporate the refrigerant vapour out of the solution

• Most common absorption cycle: Water as refrigerant and lithium bromide as the absorber

• Most common adsorption cycle: Silicia gel, zerolites, slat

• Mechanical compression —> Exergy 100 %

• Thermal compression —> Exergy << 100 %

• Share of exergy of heat changes with temperature (higher temperature, higher exergy —> logarithm)

Process