Energy efficiency in starch/potatoes/ grain mill products

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Thermal energy

Heat generation

low-cost / short term opportunities
Energy Saving Opportunity Action to Check
1. Reduce excess combustion air to minimum 1. CO2/O2 measurement
2. Maximise completeness of combustion 2. Soot/CO measurement
3. Maintain boiler cleanliness (soot/scale) 3. Monitor for rise in flue gas temperature
4. Repair (replace) boiler insulation 4. Periodic inspection of boiler insulation condition.
5. Insulate feedwater tank – cover tank 5. Check possible feedwater temperature losses
6. Insulate condensate return lines 6. Check possible heat loss from condensate return lines.
7. Optimise quality of make-up water and feedwater 7. Monitor quality of make-up water and feedwater: hardness, acidity, O2.
8. Minimise blowdown 8a. Monitor concentration of dissolved solids in boiler water.

8b. Improve blowdown controls

9. Maintain nozzles, grates, fuel supply pressure/temperature at manufacturers’ specifications 9a. Ensure specifications are available and in use.

9b. Regular check and resetting/maintenance.

10. Maximise combustion air temperature 10. Draw air from highest point in boilerhouse.
11. Reduce steam pressure where it exceed system/process requirements. 11. Check system/process needs; adjust controls.
12. Use duct for intake of warmer combustion air 12. Install duct from combustion air intake to higher parts of room.
13. Install an automated gas leakage detector. -
14. Repair leaks in steam pipework. -
Higher cost / longer term opportunities
Energy Saving Opportunity Action to Check
1. For rapidly varying demand, convert one or more boilers to live accumulator (buffer tank). 1. Monitor/evaluate demand change patterns.
2. Alter controls to “High-Low-Off” or “modulating-Low-Off” 2. Monitor/evaluate demand change patterns.
3. Install flash steam heat recovery 3. Consider in large capacity situations with high (continuous/frequent) blowdown.
4. Improve combustion controls. 4a. Provide adequate heat input to meet demand.

4b. Minimise fuel/pollution. 4c. Protect personnel/equipment.

5. Waste heat recovery 5a. Economiser

5b. Air heater (recuperator)?

6. Install boiler blowdown heat recovery. 6. Consider in large capacity situations with high (continuous/frequent) blowdown.
7. Use process integration 7. Couple process units that have significantly different heat requirements (i.e. low-pressure

steam leaving a high-pressure steam consuming production process can be used for a process requiring low-pressure steam).

Heat Distribution

Low-cost / short term opportunities
Energy Saving Opportunity Action to Check
1. Repair/replace faulty insulation 1. Pipework insulation – especially around valves.
2. Repair inefficient steam traps/drains. valve spindles etc. 2. Regular checks for leaks throughout the system.
3. Insert valves to isolate “periodic-use” items in system. 3. Check system for periodic (e.g. seasonal, nightly) items (e.g. space heaters).
4. Remove/isolate “dead-legs” and redundant Pipework. 4. Check for dead-legs and redundant piping.
Higher cost / longer term opportunities
Energy Saving Opportunity Action to Check
1. Replace steam traps/drains with more efficient designs. 1. Monitor efficiency of, and heat losses from existing traps.
2. Replace or increase insulation 2. Check existing insulation; estimate heat losses in system.
3. Maximise condensate returns. 3. Measure “discarded” heat from condensate.
4. Redesign system to minimise pipe runs. -
5. Generation pressure reduction. -

Heat Utilisation

Energy Saving Opportunity
1. Plant insulation 6. Ensure plant at high load factor
2.Local burner efficiency 7. Eliminate uneconomic “hot standby” periods
3. Maximise heat transfer rate 8. Recycle waste heat to process
4. Improve controls (e.g. thermostats) 9. Recover heat, for use elsewhere
5. Consider alternative energy source 10. Train all staff to operate manual controls and to watch for energy saving opportunities.
Space heating
Low-cost / short term opportunities
Energy Saving Opportunity
1. Use heat only when area is occupied 6. Check condensate traps
2. Set thermostats to minimum for comfort 7. Vent air from hot water systems
3. Minimise loss of hot air 8. Time switches
4. Clean and effective heaters 9. Manual controls where appropriate
5. Maintain pipe insulation in unheated areas
Higher cost / longer term opportunities
Energy Saving Opportunity
1. Install more/more efficient thermostats 4. Change energy source
2. Use motorised valves to divide building into different zones 5. Change heating system – where:

Insulation: Good or Poor

Ventilation: High or Low

Use: Radiant Heat or Convective Heat

3. Air curtains 6. Improve building insulation

Electrical Energy


Energy Saving Opportunity
1. Try to ensure that motor capacity is not more than 25% in excess of full load. 4. Install variable speed drives
2. Install motor controllers (voltage, power factor and fixed speed controllers). 5. Install high efficiency motors
3. Build in “soft-start” facilities.

Compressed Air

Low-cost / short term opportunities
Energy Saving Opportunity
1. Switch off whenever possible. 5. Use lowest air intake temperature possible.
2. Install low-cost solenoid valves on air supply lines to individual machines. Switch off compressed air supply

as soon as machine is switched off.

6. Fit 2-speed motors.
3. Clean air intake filters regularly 7. Fix leaks
4. Use lowest possible operating pressure. Reduce pressure locally if possible. 8. Check on correct pressure setting regularly.
Higher cost / longer term opportunities
Energy Saving Opportunity
1. Fit a small (jockey) compressor to meet off-peak demand. 6. Air pre-cooling.
2. Duct air intake to ensure coolest possible. 7. If some users are using low pressure air (2.5 – 3 bar), install two separate systems.
3. Fit air flow and kWh meters to monitor power and air use. 8. Use frequency control for compressor.
4. Install modern controls on multi-compressor installations. 9. Use an individual compressed air supply for special applications.
5. Fit a standard heat recovery unit. 10. Replace pneumatic tools be electrical tools


Low-cost / short term opportunities
Energy Saving Opportunity
1. Switch off whenever possible.
2. Regular maintenance is necessary to maintain pump efficiency and prevent breakdown, especially when the

vacuum-space contains condensing vapours;

3. Fix leaks
Higher cost / longer term opportunities
Energy Saving Opportunity
1. Fit a standard heat recovery unit.
2. Use a central vacuum system with several delivery points


Design measures
Energy Saving Opportunity
1. Group refrigeration cells according to temperature.
2. Use an integrated plant layout – optimise use of evaporators or condensers (i.e. remove obstacles)
3. Limit energy losses through open doors
Low-cost / short term opportunities
Energy Saving Opportunity
1. Switch off lights, fans, pumps. etc., when not required. 7. Use load rescheduling (e.g. cool at night) where maximum-demand tariffs are in operation.
2. Repair damaged insulation/seals. 8. Minimise cooling space by installing removable plastic screens or panels or by filling cooling space with polystyrene foam blocks
3. Check for refrigerant contamination. 9. Switch off evaporator fans when compressor is off
4. Check for scaling on condenser and evaporator surfaces. 10. Regulate condenser pressure (and therefore temperature)
5. (Multi-compressor systems); set controls to activate minimum number of compressors. 11. Delayed start-up of compressors. Initially, only start-up of ventilation.
6. Monitor timing and duration of defrost cycles. Defrost on demand rather than at fixed intervals. 12. Increase the evaporation temperature.
Higher cost / longer term opportunities
Energy Saving Opportunity
1. Install kWh meters and instrumentation to monitor equipment and cold room. 7. Install frequency control (i.e. VRF) on chiller compressor.
2. Install an energy management system which analyses operation of the whole refrigeration system. 8. Install high efficiency or 2-rev electromotor on evaporation fan
3. Use effective insulation and sealing. 9. Build a cooled front space for refrigeration units.
4. Install efficient electronic expansion valves. Avoid “head pressure control” where possible. 10. Use hot refrigerant gas from the compressor for the initial stages of the defrosting cycle.
5. Recovery of waste heat at the condenser 11. Use excess heat from other production processes for the production of cooling using adsorption/absorption cooling.
6. Automatic bleeding of refrigerant to remove any penetrated air



Energy Saving Opportunity
1. Use the most efficient lamps consistent with required illumination levels and colour rendering. 8. Replace lamps which have exceeded their rated life.
2. Use the light output from lamps efficiently. 9. Use “switch-off” and “save-it” stickers as a tool of good housekeeping.
3. Maintain lamps and fixtures clear of light-blocking dust and dirt. 10. Consider new technologies in order to reduce installation cost, such as infrared switching.
4. Switch off lights where lighting is not needed. 11. Divide the lighting system of a large space into several independent lighting groups.
5. Consider automatic control of lighting (time clocks and/or photo cells). 12. Use presence detection switches
6. Make the best use of daylight. 13. Use a lighting system that is continuously variable (e.g. high-frequency fluorescent lighting).
7. Avoid the absorption of light by the surroundings (light-coloured wall, ceilings, and floors).

Building skin

Energy Saving Opportunity
1.Thermal insulation of floor 3.Thermal insulation of roof
2.Thermal insulation of walls 4. Use of double-glazed or solar shading glass windows

Central Heating

Low-cost / short term opportunities
Energy Saving Opportunity
1. Use a weather dependent control to regulate the temperature of the boiler water in relation to the outside temperature. 3. Insulate pipework
2. Install an advanced timer for the boiler operation schedule. 4. Insulate hot water storage tanks
Higher cost / longer term opportunities
Energy Saving Opportunity
1. Divide large interior spaces into smaller areas.
2. Use radiation heating in cases where large ventilation rates are required.
3. Use displacement ventilation in the case where the heated indoor areas are higher than 6 meters.

Ventilation system

Energy Saving Opportunity
1. Heat recovery of exhaust air using a rotary wheel.
2. Reduce the amount of ventilation air as much as possible by the installation of:

Timer switch; sensor; Air quality; Frequency control on the fan motor

3. Prevent infiltration through door openings with:
  • Thermal insulation
  • Draught curtains
  • Air cushion
  • Automatic door
  • Slip door
  • Rubber seal between door and doorpost instead of brushes or no sealing.

Exhaust systems

Energy Saving Opportunity
1. Use local exhaust ventilation systems. The purpose of a local exhaust system is to remove the contaminants (dust, fume, vapour etc.) at the source.
2. Some options for improving the efficiency of exhaust systems are:
  • Frequency control on the electromotor of the fan
  • Close exhaust points that are not in use.
  • Start up the exhaust system with all exhaust points closed.


Energy Saving Opportunity
1. Use thermal energy storage systems (i.e. ice banks)
2. Use shading devices for windows.