Energy efficiency

Energy efficiency in industry is a priority around the world. A significant indirect

benefit is CO2 reduction: This is of importance in the light of global warming and the Kyoto protocol. The following short articles give an overview of several typical applications in industry where drives technology in combination with

electrical motors result in energy savings and CO2 reduction.

As brass as you (a leading manufacturer of brass and to start the motors and then gradually copper products) by measuring the opened to the right position for oper- like energy used during a typical working ation. This was a complex method of week. The audit mainly covered the control that led to considerable fume extraction filter plant for the energy loss in the system. As we have brass casting process, which consists a variable rather than a fixed load, we of two Luhrfilter filtration plants, one decided to employ variable speed with a 250kW fan and the other with drives to regulate the speed of the three 132 kW fans. The airflow from fans.” the fans was controlled by using dampers as restrictors. It took only two months to replace the old damper system with ABB vari- The results pointed to potential ener- able-speed drives and since then esti- gy savings with ABB drives of at least mated energy savings (to date) are in £25,000 ($44,650) a year on a 250kW the region of 3,250,000kWh (assuming fan, and £15,000 ($27,300) a year for 4 pence per kWh electricity price). each of three smaller fans – a saving With an estimated 65% of industrial of £70,000 ($127,300) a year and a Fitting the drives also had other bene- electrical energy used by electric payback period of just 9 months. In fits besides energy saving. The swarf any case, the total savings achieved drying plant is served by three 132kW motors, it is no wonder major energy for the installation proved to be much extraction fans. A pressure transducer, users in industry increasingly see en- higher, some £130,000 ($236,500) mounted in the ducting, feeds infor- ergy reduction as a key to increasing a figure verified by Boliden’s own mation back to each variable speed their profitability and competitiveness. energy measurement system. drive. This not only controls the dri- ve’s operating parameters but it also entral Electrical, one of ABB’s Ian Davey, Engineering Manager for tackles environmental issues by help- Cchannel partners in the UK, car- Boliden, outlined the problems caused ing to control emissions. In fact, ried out an energy audit on the filtra- by the old system: “The orifice avoided CO2 emissions amount to tion plants belonging to Boliden MKM dampers employed had to be closed approximately 1,625 tonnes.

Under e-scaling pumps in a hot-rolling wanese steel company used a me- Dmill are used to remove scale from chanical return (bypass) valve con- pressure the surface of hot steel. They work by trolled by an external PID controller. taking the low pressure water from the When peak pressure was required, water supply plant and creating the the return valve was closed and the high-pressure water that is sprayed on- maximum amount of water was fed The use of variable speed drives for to the surface of the hot steel, which in to the de-scaling pumps. When de- flow and pressure control of electric turn removes the scale. These pumps scaling was not required, the return motors results in very definite energy are placed before the mill stand and valve was opened to reduce the water and cost savings. A pump, controlled operate when steel passes through the supply. But because the system had rolling mill. It is only during this phase fixed-speed booster pumps, they by a variable speed drive, running at that the high-pressure water is needed. operated at full speed irrespective of half speed consumes only about one- the water pressure needed. Because eighth of the energy compared to one To regulate the pressure of the water of this, huge amounts of energy were running at full speed! fed to the de-scaling pumps, a Tai- being totally wasted. A solution was

22 ABB Review 3/2005 Energy efficiency needed whereby the speed water pressure bringing im- of the motor was reduced proved steel quality. On top so that no more energy of this, maintenance costs than necessary was con- are lower and product quali- PID Return sumed during peak pres- Controller Valve ty has improved consider- sure times. Melt Shop ably. ACS1000 ACS1000 VFD 2 VFD 1 The solution came in the Energy and water costs have form of ABB’s ACS1000 Slab Caster been reduced significantly: variable speed drives which Water estimated energy savings were retrofitted to the fixed Treatment (to date) are in the region of speed booster pump mo- Hot Rolling Mill 2,930,000kWh; estimated Constant tors. This means that high- Pressure Descaling annual water savings amount pressure water is now sup- 5.6 kg/cm2 Pump to approximately 65,000 Water plied only when needed. Process tonnes; and CO2 emissions In addition, the use of Pool Booster have been cut by about drives makes the system Pumps 1,465 tonnes. response faster than a tradi- Waste Water Path Clean Water Path tional system with return valves. This stabilizes the

Increasing gener- ainuun Voima Oy’s 240 MW CHP back calculation has to indicate a full K(Combined Heat and Power) plant return on investment in less than two is located in Kajaani, Finland. In 2003, years. That being the case, since its ation capacity ABB delivered its medium voltage installment, Kainuun Voima estimates drive, the ACS1000, for a new feed- that the ACS1000 has saved about water pump application in the plant. 1 GWh of energy annually (enough One way of saving money is by saving for 50 electrically-heated or 200 cen- energy. And the rewards are not too Kainuun Voima’s criterion for energy- trally-heated households) and reduced efficiency investments is that the pay- CO emissions by about 500 tonnes bad either. 2 per year. On top of this, the reduction in operating costs has more than justi- fied the company’s investment in elec- trical variable speed drives. The Kyoto protocol took effect in the middle of February and since then,

spot trading of CO2 emissions has been picking up. Kainuun Voima’s en- ergy efficiency improvement scheme recently qualified for investment sup- port from the Ministry of Trade and Industry.

Impressive com- tions in a variety of applications and that controls the system pressure, air industries. delivery, oil temperature and duty cycle directly from the drive. pressor functions With energy savings a top priority, Curtis-Toledo wanted to upgrade its This innovative approach eliminated ABB’s ACS800 drive and custom soft- screw compressors with adjustable- separate logic controllers and uses the ware is a unique solution when it speed drives to provide and control ACS800 drive to control the speed of the comes to energy savings and opera- airflow supplies in direct response motor. At the same time, its processing tion efficiency in screw compressors. and proportion to real-time operating power and extensive I/O act like a tradi- (load) conditions. To satisfy the com- tional programmable logic controller. pany’s needs for energy efficiency and t. Louis-based Curtis-Toledo Inc. is ease of use, ABB created a unique With a drive built into the compressor Sa 150-year-old OEM of industrial air control package: the ABB ACS800 as an integral part of the machine, the compressors (in the range 5–300hp) drive was built into the compressor compressors operate at greater effi- used to power equipment and opera- and coupled with customized software ciency. This includes matching air vol-

ABB Review 3/2005 23 Energy efficiency ume to demand as the variable-speed “This whole application is about saving With a 75kW machine running 5000 slows the motor down when air de- energy, so having a touch screen that hours per year, energy savings of mand decreases. Software control en- displays the calculated energy savings about 200,000kWh (50 percent) have ables the drive to regulate and change as the machine is running is the been recorded. This figure may be ex- speed to match the exact air demands biggest benefit, followed by its ability ceeded depending on the air demands from the plant or process. to monitor the working conditions of of the facility. Avoided CO2 emissions the compressor,” says Jerry Elson, na- have amounted to 100 tonnes. The ABB drive software was designed tional sales manager for Curtis-Toledo. to include a formula that continuously calculates the energy savings so the End users can expect annual energy end user can see the dollar savings on cost savings with a 12 to 18 month demand by viewing a touch screen. return on investment on the drive.

Wheels of steel Dunlop company meet new health “Apart from energy saving, the drives and safety levels set at 80dbA! bring much greater reliability to our turn energy into process. Star-delta starting stresses Four of the drives, rated from 37 to the motor, whereas the smooth start 55kW, are used on water pumps with- of variable speed drives has a direct gold in four cooling towers. Two 37kW impact on maintenance costs,” says drives are used on filtration paint line Phil Smith, Maintenance Services Over 1,000 MWh of energy is being pumps within the company’s wheel Administrator. “Pumps will run longer saved each year at Magnetto-Topy’s paint line and a further 37kW drive as they are running slower and with controls a compressor house pump. less vibration. The reliability of the steel wheel manufacturing plant in drives now means I rarely go near the Coventry following the installation of The cooling tower drives have replaced system.” seven ABB drives. star-delta switching which was used to turn the pumps on and off. With this Keeping up to date with the demands agnetto-Topy’s outstanding ener- arrangement, the pumps ran at full of the environmental system, ISO Mgy saving, which translates into speed (on 50 Hz) regardless of produc- 14001 is a key factor in choosing vari- 500 tonnes of avoided CO2 emissions, tion needs. Now Magnetto-Topy is able able speed drives. In addition, Mag- was achieved with a £23,000 invest- to reduce the running speed on one netto-Topy aims to claim its Climate ment that will provide pay back in pump, rated at 55kW, to 35 Hz, result- Change Levy (CCL) allowance, for just over one year. In addition, the ing in a 53 percent energy saving. On which it needs a 10 percent saving pump noise has been significantly re- three other pumps the running speed over 10 years. “We are on target to duced and this will help the former has been reduced to between 40 to achieve it this year, which means we 45 Hz, reducing energy consumption won’t have to buy carbon permits” by between 33 percent and 46 percent. says Pound.

Pump house noise is reduced by an Paul Stafford, Director of Drives at average of 10 percent by operating Sentridge (ABB Drives Alliance part- the drive at a higher switching fre- ner) concludes: “In a time of econom- quency. Using this switching frequen- ic uncertainty, costs saving procedures cy, the motors are perceived to be op- are usually implemented on the facto- erating silently, because the sensitivity ry floor, therefore why not reduce of human hearing decreases rapidly long-term costs through energy con- above 15kHz. servation? Installing a variable speed drive not only lowers energy bills and Magnetto-Topy is the UK’s only pro- pays for itself in about a year in our ducer of steel wheels and it presently case, but it also conserves the valu- produces up to 100,000 wheels each able energy needed on a daily basis”. week. Dave Pound, Operations Man- ager, says “the electricity costs alone needed to make each wheel is esti- mated at 14p. The energy reduction saves at least 1p. This may not sound much, but when we are producing so many wheels and with pressure on to reduce overheads, then 1p per wheel mounts up to a tidy sum.”

One of the overhead costs under scrutiny is the maintenance budget.

24 ABB Review 3/2005 Energy efficiency

Pump it up and autochanging, are uti- lized, as is the drive’s PID

SLC AB controller.

An ABB AC drive has been Piskovy filtr Operation is now fully auto- used to upgrade the water Vyveva 1 matic and parameters can be supply system at a phar- Vyveva 2 set and changed quickly and maceuticals plant in the Piskovy filtr easily. The pressure in the FM C2 C1 Czech Republic. The up- system is held constant, grade has produced esti- there has been a significant mated annual savings of C3 reduction in vibration and around w 100,000 through noise levels, and reliability has improved dramatically. reduced energy consump- MAX At the same time wear and tion and major improve- TLAK PROVOZ tear has been minimized. ments in the reliability and MAX MAX HLADINA HLADINA operating lifetime of electri- HLADINA The use of the AC drive has cal and mechanical compo- MIN MIN also provided considerable nents. MIN financial benefits. In the six HAV.MIN Hydrofor Hydrofor months before the project, Studna 80 m3 an average of 0.417kWh of he pumping station at electricity was consumed Tthe plant has three for every cubic meter of pumps: two 70 liters per water pumped. This figure second and one 50 liters fell to 0.299kWh/m3 (a fall per second. The supply system Drives Alliance Partner, involved of 28.3 percent) for the six months pipework has a maximum capacity of replacing the existing direct motor after completion of the project. Total 70 liters per second. Prior to the up- control with an ABB variable speed electricity savings in the first year grade, the pumps were used in on/off drive. have been estimated at around mode with control provided by two m 3,800 or 96,000kWh, and CO2 emis- pressure switches, with a minimum of Following the upgrade, one of the sions are down by 48 tonnes. 300kPa and maximum of 600kPa. On- 70 liters per second pumps is kept in ly one pump – selected manually – reserve. Of the two pumps controlled The indirect savings resulting from the was run at a time. The system was by the drive’s PFC macro, the second upgrade are even greater – in the case subject to very frequent start and stop 70 liters per second pump is run as a of one end user, about m 100,000 per sequences (the maximum time be- variable speed unit, while the 50 liters year. This figure is a result of reliable tween start and stop being less than per second pump is run at constant motor operation, significantly reduced 10 minutes) resulting in damaged speed. Overall control and monitoring contactor failure rate, increased relia- motor windings, burnt-out contactors, is performed by an SLC 500 A–B PLC bility in the pipe system and other and deterioration of pipe seals. unit. The InTouch software provides a components, and reduced mainte- screen display of the system’s opera- nance and servicing costs. The upgrade project, implemented in tion. All the features of the PFC close co-operation with ABB’s local macro, including the sleep function

paper, film or foil, this solution is a use load-cell systems to monitor the Triple punch quantum leap in operating, mainte- web tension, and a setpoint controller nance and cost benefits. that feeds the difference between the What do you get if you combine an desired unwind tension (setpoint) and AC motor, drive, and load cell from According to Bob Sarnelli, product the measured tension from the load manager, ABB Inc., Automation Tech- cells to the air-brake control. Air ABB? The answer is a new era of nologies, Web Tension Products, “All brakes, however, and their air-supply electronic, integrated web speed and the mechanical considerations of system have many application short- tension control for small-horsepower keeping an air-powered brake, and comings and invariably become prob- unwind applications. the air line and air supply to them lematic as they age. functioning are gone. In addition, the he products and expertise of three electronic control replacing it erases Since the basic operation of the brake TABB business units – Motors, Dri- all those mechanical headaches and is to apply holdback force (torque), ves and Load Cells/Tension Control – provides superior unwinder control.” why not use a motor in a mode that have been combined so that an AC requires force (torque) to turn it? The motor can be used to replace a tradi- The function of the brake is to control idea of using a motor as a brake is not tional mechanical-brake-and-air-supply the tension of the unwind material in- entirely new and has been used suc- system. For any processor unwinding to the process. Most configurations cessfully in unwinding applications, but

ABB Review 3/2005 25 Energy efficiency mostly in large applications that require manager of system integrator sales, of New York had a two-roll unwinder high horsepower, ie, above 25hp, such ABB LV Drives, New Berlin, Wisconsin. with two, ten-year old mechanical air as paper manufacturing where the rolls brakes and a host of repeating prob- are extremely large. Because AC drives and motors have lems. Product quality and production continued to add performance features were suffering. Rather than replace the Historically, the biggest obstacle to us- while reducing price per horsepower, mechanical brakes with a new, more ing a motor as a brake on small-horse- AC drive/motor solutions have, accord- modern mechanical brake, ABB was power unwinder applications has been ing to Hollis, become “extremely com- contracted to install a 5hp AC four- cost. “But with all the recent leaps Vari- petitive with mechanical brakes.” pole motor, a 4:1 gear reducer, and an able Frequency AC Drive (VFD) tech- ABB ACS800 Direct Torque Control nology has made, the AC drive/motor The performance and cost advantages (DTC) drive with built-in flux braking. solution now provides performance of using an AC motor-brake system and control superior to the traditional have been proven in a plastic film DC installations,” notes Chuck Hollis, application. IR Industries in the state

Upgrading without investing

In the city of Turku (Finland) many heating, ventilation, and air-condition- ing (HVAC) systems in many of the city’s municipal buildings have been upgraded using an Energy Saving Company (ESCO). In 2004, the HVAC systems in the office of the city’s har- bor were also revamped but this time, ABB technology was fundamental to the project’s success.

lso called “performance contracting” Aor “third-party financing”, an Energy Service Company (ESCO) develops, in- stalls and finances projects designed to improve the energy efficiency and main- tenance cost for facilities over a several- year period. YIT Building Systems is such a company and was contracted to do the HVAC projects in Turku. The city itself is not investing anything into energy efficiency, but is paying a service fee – in proportion to the energy cost savings achieved – to YIT.

YIT modernized the air-conditioning system of the city’s harbor office in 2004. Many system improvements were done, but central to energy effi- ciency improvement was the decision to install ABB drives and eff1-rated motors to the air handling units. The tions, but they also allow for substan- a 12 month period) which represents drives enable the ventilation fans to tial heating energy savings. This be- a 40 percent saving in heating costs. operate at a suitable air flow based on comes possible because the office’s Corresponding CO2 emissions were demand, and eff1 motors guarantee exhaust fan can now be operated at reduced by 67.2 tonnes. high electrical-to-mechanical power the smallest capacity needed for any conversion efficiency. situation. During the first five months of the operation, YIT Building Sys- The drives not only save electrical tems recorded a thermal energy sav- power in part load ventilation condi- ing of 97,865kWh (234,900kWh over

26 ABB Review 3/2005 Energy efficiency

It has a total treatment capacity of voltage drives and by doing this, the Drinking and 4.3 million cubic meters per day. The treatment plant‘s system efficiency has treated water is distributed by three increased by 15–30 percent (depend- “driving” in transmission pumping stations and 20 ing on the required operating speed). distribution pumping stations through In the first year of their operation, the Bangkok a 20,000km pipeline network. first two ABB drives have contributed more than $120,000 to energy cost Supplying a city of 11 million people Most of MWA’s pumping stations were savings. This figure translates into with clean water is no easy task. equipped with eddy current coupling monthly energy savings of approxi- drives that controlled the speed of the mately 180,000 kWh and does not The fluctuating demand must be treatment plant’s water pumps. Even take into account any additional sav- met uncompromisingly and equip- though they operated with varying ings from improved maintenance. ment must perform as expected. speed, MWA had excess energy losses CO2 emissions have been reduced by ABB technology is keeping the water of almost 15–30 percent because of about 90,000kg per month. flowing. the outdated technology. As electricity costs amount to almost 50 percent of Other practical plusses include a more WA (Metropolitan Water Works their production cost, MWA was look- flexible pump operation, increased MAuthority), a Thai state enter- ing for ways to increase the efficiency lifetime of motors and pumps, easier prise charged with operating the of their pumping stations. maintenance and full automatic con- world’s biggest tap water treatment trol. plant, supplies the drinking water for It was decided to replace the coupling Bangkok’s 11 million plus citizens. drives with ABB’s ACS 1000 medium

“Driving” through of a regenerative AC drives’ front end, combined with ABB’s unique LCL the snow (Lower Control Limit) filter, enables lifts to run at full power, in 80 percent “brownout” conditions! This ride- With an objective of reducing power through ability means that even when consumption and motor maintenance, there’s a dramatic short-term reduc- tion in voltage from the utility grid, the two longest AC-powered ski-lifts the drive sustains full power to the in the U.S, Breckenridge Ski Resort in motor and lift so that operation is not Colorado and Sugarbush Resort in interrupted. Vermont, have installed 900 hp and 700 hp fully regenerative AC drives Harmonic mitigation is built into and AC motors from ABB for the ABB’s regenerative drives via technol- resorts’ Independence and Green ogy that eliminates the need for large, expensive, custom “mountain wide” Mountain Express lifts, respectively. tuned harmonic-trap filters. The har- monics generated by a typical DC reckenridge’s lift is a 7,150-feet- drive would be approximately seven Blong (2,180m) detachable six- times those generated by ABB’s re- pack; the top-powered Green Moun- generative AC drive with its unique tain Express runs to 6,250 feet LCL filter. This is a result of the AC (1,905m), with a vertical rise of 1,500 drive’s ability, as an active filter, to feet. Both lifts were built by Leitner- shape the current sinusoidally. Poma. According to Jason Lisai, direc- tor of planning for Sugarbush, “We expect the lift to operate at “When the decision was made to up- around 95 percent efficiency as op- grade the ski-lift systems, we wanted posed to DC systems where we nor- to use the best available technology.” mally expect 91 percent,” says Gabe Clink of Leitner-Poma, “makes a very Arnold, CEO project manager for Effi- strong case that an AC drive is the Drives technology is certainly impres- ciency Vermont, the state’s utility environmentally sound way to go.” sive when you consider that regenera- watchdog reviewing the Sugarbush AC tive drives have the ability to use the drive system. That difference should energy a motor produces when it is be- lead to savings of around 25,000kWh ing turned, rather than being required per season. With the reduced power to turn the load it is connected to. consumption an AC drive/motor com- bination yields combined with the fact The IGBT-based (Integrated Gate that an AC motor is virtually mainte- Bipolar Transistor) switch construction nance free, this, according to Tom

ABB Review 3/2005 27