Energy efficiency and utilization in industrial sectorpptx

energy system engineering

1. 1 Md. Mizanur Rahman MEng(Sweden), PhD (Finland), CEng Chartered Energy Engineer (EI, UK) Certified Energy Manager School of Mechanical Engineering Universiti Teknologi Malaysia Office: C23-228, UTM, JB Cell: 0176480491 Email: [email protected] Significant Energy Users (SEU)

2. BOI L ERS

3. Introduction BURNER WATER S OUR C E B R I N E SO F T E N E R S CHEMICAL FEED F U EL BLOW DOWN SEPARATOR VE NT VE NT EXHAUST GAS STEAM TO PROCESS S T A C K D EAE R A T OR PUMPS Figure: Schematic overview of a boiler room BOILER ECO- N O M I - ZER

4. Assessment of a Boiler Heat Balance An energy flow diagram describes geographically how energy is transformed from fuel into useful energy, heat and losses FUEL INPUT STEAM O U T P U T St o c h i o me t r i c Excess Air Un burnt Stack Gas Ash and Un-burnt parts of Fuel in Ash Blow D o w n Convection & Radiation

5. Assessment of a Boiler Heat Balance Balancing total energy entering a boiler against the energy that leaves the boiler in different forms Heat in Steam BOILER Heat loss due to dry flue gas Heat loss due to steam in flue gas Heat loss due to moisture in fuel Heat loss due to unburnts in residue Heat loss due to moisture in air Heat loss due to radiation & other unaccounted loss 12.7 % 8.1 % 1.7 % 0.3 % 2.4 % 1.0 % 100.0 % Fuel 73.8 %

6. Assessment of a Boiler Heat Balance Goal: improve energy efficiency by reducing avoidable losses Avoidable losses include: Stack gas losses (excess air, stack gas temperature) Losses by unburnt fuel Blow down losses Condensate losses Convection and radiation

7. Assessment of a Boiler Boiler Efficiency Thermal efficiency: % of (heat) energy input that is effectively useful in the generated steam BOILER EFFICENCY CALCULATION 2) INDIRECT METHOD: The efficiency is the different between losses and energy input 1) DIRECT METHOD: The energy gain of the working fluid (water and steam) is compared with the energy content of the boiler fuel.

8. Assessment of a Boiler Boiler Efficiency: Direct Method Boiler efficiency (  ) = Heat Input M x (h g – h f ) x 100 m x GCV Heat Output x 100 = h g - the e n t h a l py of sa tur a t e d s t ea m i n k J / k g of s t ea m h f -t he e n t h a lpy of f ee d w a t e r in kJ / k g of w a t e r Parameters to be monitored: Quantity of steam generated per hour (M) in kg/hr Quantity of fuel used per hour (m) in kg/hr The working pressure (in N/m 2 ) and superheat temperature ( o C), if any The temperature of feed water ( o C) Type of fuel and gross calorific value of the fuel (GCV) in kJ/kg of fuel

9. Assessment of a Boiler Boiler Efficiency: Direct Method Advantages Quick evaluation Few parameters for computation Few monitoring instruments Easy to compare evaporation ratios with benchmark figures Disadvantages No explanation of low efficiency Various losses not calculated

10. Assessment of a Boiler Efficiency of boiler (  ) = 100 – (i+ii+iii+iv+v+vi+vii) Boiler Efficiency: Indirect Method Principal losses: Dry flue gas Evaporation of water formed due to H 2 in fuel Evaporation of moisture in fuel Moisture present in combustion air Unburnt fuel in fly ash Unburnt fuel in bottom ash Radiation and other unaccounted losses

11. Assessment of a Boiler Boiler Efficiency: Indirect Method Required calculation data Ultimate analysis of fuel (H 2 , O 2 , S, C, moisture content, ash content) % oxygen or CO 2 in the flue gas Flue gas temperature in ◦C (T f ) Ambient temperature in ◦C (T a ) and humidity of air in kg/kg of dry air GCV of fuel in kJ/kg % combustible in ash (in case of solid fuels) GCV of ash in kJ/kg (in case of solid fuels)

12. Assessment of a Boiler Boiler Efficiency: Indirect Method Advantages Complete mass and energy balance for each individual stream Makes it easier to identify options to improve boiler efficiency Disadvantages Time consuming Requires lab facilities for analysis

13. Energy Efficiency Opportunities 1. Stack Temperature Control Keep as low as possible If >200°C then recover waste heat 2. Feed Water Preheating Economizers Potential to recover heat from 200 – 300 o C flue gases leaving a modern 3-pass shell boiler 3. Combustion Air Preheating If combustion air raised by 20°C = 1% improve thermal efficiency

14. 4. Minimize Incomplete Combustion Symptoms: Smoke, high CO levels in exit flue gas Causes: Air shortage, fuel surplus, poor fuel distribution Poor mixing of fuel and air Oil-fired boiler: Improper viscosity, worn tops, cabonization on dips, deterioration of diffusers or spinner plates Coal-fired boiler: non-uniform coal size Energy Efficiency Opportunities

15. Energy Efficiency Opportunities 5. Excess Air Control Excess air required for complete combustion Optimum excess air levels varies 1% excess air reduction = 0.6% efficiency rise Portable or continuous oxygen analyzers Fuel Kg air req./kg fuel %CO 2 in flue gas in practice Solid Fuels Bagasse Coal ( bituminous) Lignite Paddy Husk Wood 3.3 10.7 8.5 4.5 5.7 10-12 10-13 9 -13 14-15 11.13 Liquid Fuels Furnace Oil LSHS 13.8 14.1 9-14 9-14

16. Energy Efficiency Opportunities Radiation and Convection Heat Loss Minimization Fixed heat loss from boiler shell, regardless of boiler output Repairing insulation can reduce loss Automatic Blow Down Control Sense and respond to boiler water conductivity and pH

17. Energy Efficiency Opportunities Scaling and Soot Loss Reduction Every 22 o C increase in stack temperature = 1% efficiency loss 3 mm of soot = 2.5% fuel increase Reduced Boiler Steam Pressure Lower steam pressure = lower saturated steam temperature = lower flue gas temperature Steam generation pressure dictated by process

18. Energy Efficiency Opportunities Variable Speed Control for Fans, Blowers and Pumps Suited for fans, blowers, pumps Should be considered if boiler loads are variable Control Boiler Loading Maximum boiler efficiency: 65-85% of rated load Significant efficiency loss: < 25% of rated load

19. Energy Efficiency Opportunities Proper Boiler Scheduling Optimum efficiency: 65-85% of full load Few boilers at high loads is more efficient than large number at low loads Boiler Replacement Financially attractive if existing boiler is Old and inefficient Not capable of firing cheaper substitution fuel Over or under-sized for present requirements Not designed for ideal loading conditions

20. Energy Efficiency Opportunities Losses 17 % Stack & Enthalpy Blowdown Radiation Un burnt 80 % Steam 3 % Distribution losses Process consumption 57% 20 % Flash and Condensate 77 % Steam Energy

21. Energy Efficiency Opportunities Sr. Typical % Loss No Sources of losses. Gas Oil Coal 1 Sensible heat in dry flue gas. 4. 4. 8 6. 5 2 Sensible heat in the moisture in the air. 0. 10 0. 12 0. 18 3 Sensible heat in the H2O in the flue gas. 0. 88 0. 51 1. 6 4 Latent heat in the H2O in the Flue 9. 1 5. 2 3. 6 5 Losses due to unburnt (refuse) carbon in the fuel 0. 0. 1. 6 Losses due to combustibles in the flue gas 0. 0. 07 0. 5 7 Other losses (Radiation, Leakage, Blowdown, etc. ) 1. 1. 2. 26 T ot a l 15. 08 11. 07 15. 6

22. What can be controlled? Stack loss - by controlling excess air Enthalpy loss – by reducing stack temperature Blowdown loss - by automatic control Radiation loss - by proper insulation

23. Oil/Gas fired boilers - Cost of ownership

24. Solid fuel fired boilers, Cost of ownership

25. Optimize boiler efficiency, reduce losses

26. AIR COMPRESSORS

27. Compressed air is a versatile tool used widely throughout industry for a variety of purposes. Unfortunately, running air compressors (AC) often uses more energy than any other equipment. Air compressor efficiency is the ratio of energy input to energy output. Many air compressors may be running at efficiencies as low as 10 percent. Improving AC efficiency can yield significant savings to the facility.

28. AIR COMPRESSOR EFFICIENCY When talking about the efficiency of air compressors, it is important to remember that the compressor itself is only one part of the system; therefore, it is important to look at the whole system when discussing AC efficiency. Compressed air is the product of a system comprised of the air compressor followed by after-coolers, receivers, air dryers, air storage tanks, supply lines and possibly sequencers and multiple compressor units.

29. D Compn!ssed Air Supply I A ftercooler ASME Code Compn!ssed AirTanlc Particulate Filter Air Dryer Abrasive Blast Cabinet Inline Ambient Air Dryer (if blast cabinet is mon! than 75' from air compn!ssor) (Ptirtubuhan Synrikzli Syrim [email protected] Tf!il"!l'II M.t,J,, • Ma l ays i a lls sociatio n of En ergyServ i ce Companie s

30. Compressor Types and Typical Operating Efficiency Compressor Type Operating Efficiency (kW / 100 cfm) Single-acting, air cooled reciprocating air compressor 22 to 24 Double-acting, water cooled reciprocating air compressor 15 to 16 Single stage, lubricant-injected rotary screw compressor 18 to 19 Two stage, lubricant-injected rotary screw compressor 16 to 17 Lubricant-free rotary screw air compressor 18 to 22 Centrifugal air compressor 16 to 20

31. ENERGY USE The total energy use of a compressor system depends on several factors. The air compressor type, model and size are important factors in the compressor’s energy consumption, but the motor power rating, control mechanisms, system design, uses and maintenance are also fundamental in determining the energy consumption of a compressed air system.

32. SYSTEM CONTROLS Match the controls. System controls are one of the most important elements of a compressed air system, and are also a central factor in air compressor system efficiency. Controls are designed to match the compressor output with the system demand. Controls may manage a single air compressor, or involve the orchestration of multiple air compressors to satisfy system needs.

33. SINGLE UNIT CONTROLS Start/stop – turns compressors on and off according to discharge pressure. Load/unload – leaves motor running continuously, but unloads compressor according to discharge pressure. Modulating – controls inlet volume to satisfy flow need. Multistep – for compressors designed to operate at multiple partially loaded conditions.

34. SYSTEM DESIGN Save for times of need. The first aspect involves choosing a receiver, or storage tank, to fit the needs of the system demand and prevent system pressure from dropping below minimum required pressure during times of peak demand. A drop in pressure will cause end tools to function improperly. The common response to the tool malfunction is to increase the system pressure. The energy used in increasing system pressure could have been saved through the use of a properly sized receiver.

35. Straighten the path. The second aspect of system design is the layout and design of the air delivery system. Narrow delivery lines, looping and sharp bends in the lines can create pressure drops in the system and reduce end use pressure. The common response to this is to increase compressor pressure and use more energy; this could have been avoided through better system design.

36. Use cooler intake air. A third design aspect that may have a significant impact on air compressor efficiency is the intake air temperature. The energy required to compress cool air is much less than that required to compress warmer air. Reducing the intake temperature by moving the compressor intake outside the building and into a shaded area may drastically lower the energy required for compression.

37. Single vs. multiple compressors. In some systems, it may be more efficient to use a series of smaller compressors rather than one larger compressor. Additional smaller compressors can be brought on-line, or shut down as needed. Recover waste heat. Recovered waste heat can be used to preheat process and boiler water, for space heating, and more.

38. Discourage inappropriate uses. Because compressing air is one of the most expensive sources of mechanical energy in the industrial setting, it is often financially beneficial and more energy efficient to use alternative tools or methods when possible. Some common uses of compressed air that may be accomplished by other means are: Personal cooling; Cleaning where dry cleanup would be appropriate; Drying; Mixing, atomizing and aspirating; Process cooling; and Moving parts.

39. MAINTENA N CE Fix the leaks. This is the area where the most significant changes can occur. In addition to having a great impact on energy use, improvements here are also often relatively cheap and have immediate results. The number one source of energy loss in an air compressor system can usually be traced to wasted air. Wasted air is lost through leaks in the system. Although leaks are often very small, significant amounts of air can be lost. The air lost is proportional to the size of the orifice and a function of the air compressor supply pressure.

40. Change the filters. Another important element of the system is filters. Filters are located throughout the system to ensure clean air for end uses. Often these filters are not known of or are simply not checked. Dust, dirt, moisture and grease can clog the filters leading to a pressure drop in the system. This pressure drop is not often seen for what it is and more compression energy is used to compensate for the clogged filters resulting in increased energy use.

41. 42 Industrial System Efficiency: Capturing and Sustaining Energy Savings Case Study – Energy savings opportunities in a compressed air system in a Vietnamese footwear manufacturer.

42. 43 Industrial System Efficiency: Capturing and Sustaining Energy Savings The footwear factory is located outside Ho Chi Minh City and employs about 4500 workers. The cost of electricity to operate the compressed air system has been estimated to be about $470,000 USD per year. There are 38 operating compressors driven by 37 kW motors.

43. 44 Industrial System Efficiency: Capturing and Sustaining Energy Savings A project team was established to study the compressed air system in order to optimize energy efficiency. One of the aspects of the study was to perform a leak survey.

44. 45 Industrial System Efficiency: Capturing and Sustaining Energy Savings The study found that as much as 86% of the compressed air was lost to leakage!

45. 46 Industrial System Efficiency: Capturing and Sustaining Energy Savings Through a combination of leak management, control optimization and compressor relocation, the factory estimates it will save about $196,000 USD per year in electrical costs. The payback for the investment required to correct existing problems is, on average, less than 6 months.

46. 47 Case Study – Improving Performance in a Small Compressed Air System at a Containerboard and Packaging Material Manufacturer

47. 48 Original compressed air system used two 150 horsepower and one 125 horsepower compressors All three compressors operated with modulation controls at an average of 43% of full capacity There was no master controller Average monthly electrical expense for the compressors was $9,486.00 USD Improvements in a Compressed Air System

48. 49 Improvements in a Compressed Air System Optimization included four base- load compr e s s ors and one variable speed trim compressor

49. 50 Improvements in a Compressed Air System Supply piping was modified to minimize turbulence and pressure drops

50. 51 Improvements in a Compressed Air System Main header piping was oversized to reduce velocities and allow for future growth of supply

51. 52 Improvements in a Compressed Air System A master controller was added that both controls the compressors and has data collection and reporting functions

52. 53 Improvements in a Compressed Air System The results include: 46% reduction in energy consumption Less than 2-year payback, not including heat recovery savings – $4,000 to $5,000 USD savings per month

53. MO T ORS

54. ENERGY EFFICIENT MOTORS The cost premium for HEM is about 50 to 150 percent above the cost of an average motor. An HEM comes with higher capital cost but there will be a significant amount of energy savings during its life-span.

55. Many users are still making their motor purchasing decisions based on initial purchase costs. The fact is that on average the initial purchase cost of a motor only makes up 2% of the total cost of ownership. The total electricity consumed to operate the motor over its lifetime of 15 over years makes up 97% of its total cost. At 5000 hours per year, typical payback period is about 4 years without tax relief.

56. lnpllf Power 100% Stray load ot a l Iron core Sta or Rotor losses resislan e resistance Windage. & fri · c ti o n losses Lassos .8%

57. Motors convert electrical energy into mechanical energy to drive machinery. During this conversion, some energy is lost. Current motors feature improved designs and incorporate the latest developments in materials technology. The most efficient of these motors are termed High Efficiency Motors (HEMs)

58. Along with the international discussion on energy efficiency a worldwide harmonized energy efficiency classification system has been established for low-voltage three-phase asynchronous motors. The efficiency factor defines the efficiency of motors when transforming electrical into mechanical energy. For many years low- voltage three-phase motors have been sold in three efficiency classes EFF3, EFF2 and EFF1. Energy efficiency classification systems have been introduced and well-proven in many countries all over the world. They unfortunately differ from each other in terms of scope, wording and values. That was the reason for the International Electrotechnical Commission IEC to develop and publish an energy efficiency standard which replaces all the different national issues. In parallel IEC developed and issued a new standard for the determining the motor efficiencies. The new standard IEC 60034-30 defines and harmonizes worldwide the efficiency classes IE1, IE2 and IE3 for low-voltage three-phase motors.

59. New international efficiency classes of motors (IE = International Efficiency) The new EN 60034-30:2009 defines worldwide the following efficiency classes of low-voltage three-phase asynchronous motors in the power range from 0.75 kW to 375 kW. IE1 = Standard Efficiency (comparable to EFF2) IE2 = High Efficiency (comparable to EFF1) IE3 = Premium Efficiency The higher the efficiency class the higher is the complexity of motor production and the higher is the amount of material to be used (as for instance copper). The motor price will increase accordingly. In relation to the motor life time the purchase price is only a few percentage points and due the saved energy cost the pay-back period is short.

60. Key design features of HEMs include: Improved fan design - Reduces windage losses and improves air flow Better slot design - Improves both efficiency and power factor Improved core design - Lowers flux density and increases cooling capacity, reducing magnetic and load losses Optimised air gap - Reduces current requirements and stray load losses

61. These features result in other advantages besides energy savings: Higher power factor, Longer lifespan and fewer breakdowns, Run cooler and less susceptible to voltage and load fluctuations, and Produce less waste heat and noise. Motor efficiency classification labels will be labelled on rating plates and technical data tables in manufacturers' catalogues.

62. Efficiency Class Definition for 4-Pole Motors Motor Capacity (kW) Motor Efficiency (%) Motor Class IE3 Motor Class IE2 Motor Class IE1 0.75 82.5 79.6 72.1 1.1 84.1 81.4 75.0 1.5 85.3 82.8 77.2 2.2 86.7 84.3 79.7 3 87.7 85.5 81.5 4 88.6 86.6 83.1 5.5 89.6 87.7 84.7 7.5 90.4 88.7 86.0 11 91.4 89.8 87.6 15 92.1 90.6 88.7 18.5 92.6 91.2 89.3 22 93.0 91.6 89.9 30 93.6 92.3 90.7 37 93.9 92.7 91.2 45 94.2 93.1 91.7 55 94.6 93.5 92.1

63. 75 95.0 94.0 92.7 90 95.2 94.2 93.0 110 95.4 94.5 93.3 132 95.6 94.7 93.5 160 95.8 94.9 93.8 200 96.0 95.1 94.0 220 96.0 95.1 94.0 250 96.0 95.1 94.0 300 96.0 95.1 94.0 330 96.0 95.1 94.0 375 96.0 95.1 94.0

64. Only motors of IE2 (High Efficiency) and IE3 (Premium Efficiency) classification as shown in the Table should be used where operating hours exceed 750 per year. Decisions on motor selection between IE2 and IE3 should be done on an economic justification basis.

65. ''Right-size'' the Motor C h oose t h e correct rat i ng for the application Overs i zed moto r s have l ower e ff iciencya nd p ower factor Highest eff i c i e n cy 75 - 100 % o f rated load Serv i ce fac t or is for short- t e r m o p e r ation llotDr Efflcle nq, M Load Molor Powe r Fa clor vs L oad 97 96 95 94 92 9 1 90 69 25 50 - - - - - ------ l I 93 -tl--- -+- - - - - - ---- 1 1 :: : : : R ffi 1 1 := : I Ften i Lm M. B O -11-- - - ... 75 7 - t f------ + +-- - - - - - - ------l 75 1 1 5 1 00 PBrc&nl L Dlld 1 25 1 51] 25 5 75 1 00 1 1 5 1 25 1 5(] Pe rc:e11 t L ,oad (Ptirtubuhan Synrikzli Syrim [email protected] Tf!il"!l'II M.t,J,, • Ma l ays i a lls sociatio n of E nergy Serv i ce Compan i e s

66. Proper operations and maintenance of motors can result in significant energy savings, in the region of 10% to 15% of motor energy consumption costs, depending on existing maintenance practices. This will be covered under the following aspects: - Proper commissioning Maintenance Records Motor set up and alignment Motor cleaning Motor lubrication and bearing maintenance Motor condition assessment Electrical performance assessment Switching off when not needed Reducing motor loads Checking supply voltage characteristics Slowing down loads for pumps and fans

67. Variable Speed Drives (VSD) or adjustable speed drives are devices to control the speed of motors. Traditionally load demand on constant speed motors is regulated by the following methods: Air flow by adjustable dampers Fluid pumping by throttling valves. It is estimated that about 60% to 70% of motors in industry are related to centrifugal or flow applications such as fans, blowers, compressors and pumps. Controlling the speed of motors in response to the load demand is therefore a means of energy optimisation.

68. CONCLUSIONS Use life cycle costs - not initial costs Survey motors available – look out for HEMs Right-size motors Add drives where appropriate