Energy use,energy savings and emission analysis in the Malaysian rubber producing industries

In this paper an analysis of energy use and energy conservation in the Malaysian rubber producing industries is presented. It has been found that rubber industries consume a substantial amount of energy. Excessive use of energy is usually associated with many industrial plants worldwide, and rubber plants are no exception. This study is based on the realization that enormous potential exists for cost-effective improvements in the existing energy-using equipment. Through the method of a walkthrough energy audit, power rating, operation time of energy-consuming equipment/machineries and power factor were collected. The data were then analyzed to investigate the breakdown of end-use equipment/machineries energy use. The results of the energy audit in the Malaysian rubber and rubber producing industries showed that the electric motor accounts for a major fraction of total energy consumption followed by pumps, heaters, cooling systems and lighting. Since the electric motor takes up a substantial amount of the total energy used in rubber industries, energy-savings strategies such as the use of high efficient motors, and variable speed drive (VSD) have been used to reduce energy consumption of motors used in rubber industries. Energy-savings strategies for compressed-air systems, boilers, and chillers have also been applied to estimate energy and cost savings. It has been found that significant amount of energy and; utility bills can be saved along with the reduction of emission by applying the foretold strategies for energy using machineries in the rubber industries.     

Analysis of electrical motors load factors and energy savings in an Indian cement industry

Electric motors consume in between 30% and 80% of the total industrial energy use for few selected countries around the world. It was identified that many motors are operated under loaded conditions. In some cases, motors are operated even at 3-16% of their full loads. These low loads can be optimized with the application of variable speed drives (VSD) to match the load requirements. Based on the estimation, it has been found that annually about 1,865,925 MWh of energy can be saved for 60% speed reduction when VSDs are used. It was also found that about 2,122,675 tons CO₂emission could be avoided annually by using VSDs for Low Tension (LT) motors for 60% speed reduction. It was also estimated that annually about 4,600,386 MWh of energy can be saved for High Tension (HT) motors for 60% speed reduction using VSDs. The average payback period (PBP) for implementing VSDs for LT and HT motors found to be very low (i.e. about 2 days). In this particular study it is observed that installing both LT and HT capacitors to improve power factor found to be not economically viable owing to low level of energy savings.     

Energy and emission analysis for industrial motors in Malaysia

The industrial sector is the largest user of energy in Malaysia. Industrial motors account for a major segment of total industrial energy use. Since motors are the principle energy users, different energy savings strategies have been applied to reduce their energy consumption and associated emissions released into the atmosphere. These strategies include using highly efficient motors, variable speed drive (VSD), and capacitor banks to improve the power factor. It has been estimated that there can be a total energy savings of 1765, 2703 and 3605 MWh by utilizing energy-efficient motors for 50%, 75% and 100% loads, respectively. It was also found that for different motor loads, an estimated US$115,936 US$173,019 and US$230,693 can be saved in anticipated energy costs. Similarly, it is hypothesized that a significant amount of energy can be saved using VSD and capacitor banks to reduce speed and improve the power factor, thus cutting energy costs. Moreover, a substantial reduction in the amount of emissions can be effected together with the associated energy savings for different energy savings strategies. In addition, the payback period for different energy savings strategies has been found to be reasonable in some cases.     

A review on compressed-air energy use and energy savings

Compressed-air systems account for about 10% of total industrial-energy use for few selected countries as found in literatures. Compressed air is typically one of the most expensive utilities in an industrial facility. This paper describes a comprehensive literature review about compressed air energy use, savings, and payback period of energy efficient strategies. This paper compiles latest literatures in terms of thesis (MS and PhD), journal articles, conference proceedings, web materials, reports, books, handbooks on compressed air energy use, efficiency, energy savings strategies. Computer tools for compressed air analysis have been reviewed and presented in this paper. Various energy-saving measures, such as use of highly efficient motors, VSD, leak prevention, use of outside intake air, reducing pressure drop, recovering waste heat, use of efficient nozzle, and use of variable displacement compressor to save compressed-air energy have been reviewed. Based on review results, it has been found that for an electric motor used in a compressed-air system, a sizeable amount of electric energy and utility bill can be saved using high efficient motors and applying VSDs in matching speed requirements. Also, significant amounts of energy and emission are reducible through various energy-saving strategies. Payback periods for different energy savings measures have been identified and found to be economically viable in most cases.     

A review on electrical motors energy use and energy savings

The industrial sector is the largest users of energy around the world. Industrial motor uses a major fraction of total industrial energy uses. This paper describes a comprehensive literature review about electric motor energy analysis. This paper compiles latest literatures in terms of thesis (MS and PhD), journal articles, conference proceedings, web materials, reports, books, handbooks on electrical motor energy use, losses, efficiency, energy savings strategies. Different types of losses that occur in a motor have been identified and ways to overcome these losses explained. An energy audit that helps to identify motor energy wastages have been discussed extensively. As motors are the major energy users, different energy savings strategies such as use of high-efficient motor, variable speed drive (VSD), and capacitor bank to improve the power factor to reduce their energy uses have reviewed. Different policy measures (i.e. regulatory, voluntary and incentives based) to save motor energy use have been reviewed and presented in this paper. In this review, computer tools that can be used to analyze electric motors energy used has been discussed. Cost parameters to carry out economic analysis have been shown as well. Moreover, payback period for different energy savings strategies have been identified.     

Optimal control of pump rotational speed in filling and emptying a reservoir: minimum energy consumption with fixed time

An effective way to save energy in pumping systems with low static head is to control the pump’s rotational speed with a variable-speed drive (VSD), which allows changing of the rotational speed when necessary. VSDs can be utilized to control batch transfer systems, for example, in filling or emptying a tank or a reservoir. In the literature, such processes have been optimized only with respect to energy consumption, but the time limit has been ignored. This means that pumping time can be very long. Our paper deals with this optimization problem and considers both pumping time and energy demand, which are often conflicting criteria. We derived a general optimal control law for rotational speed, which can easily be implemented in existing VSDs in the market. Minimum energy and minimum time schemes are special cases of this general new scheme. A constant flow rate scheme, suggested in the literature, is verified to give an optimum solution if the efficiency of the pump remains constant during operation. In addition to energy consumption, rotational speed control can have a favorable effect on the pump’s lifetime, as pointed out in the paper.     

Using multi‐stack and variable‐speed‐drive systems to reduce laboratory exhaust fan energy

In buildings that contain laboratories, fume hoods are normally used to control contaminant concentrations. Exhaust stacks with a constant exit velocity are required to make sure that dangerous concentrations do not occur in occupied areas near the building or on the roof top. To achieve constant velocity when exhaust flow rates are less than design, makeup air is introduced to the system at the inlet of the exhaust fan. Since laboratory exhaust airflow is often significantly less than the design airflow, exhaust fans consume significantly more energy than is necessary. To reduce exhaust fan energy, techniques involving multiple exhaust stacks and a variable speed drive (VSD) can be applied to laboratory exhaust systems. The potential fan energy savings depend on optimal selection of the number of stacks, the sizes of the stacks, and the exhaust system ductwork design. This paper introduces application principles, describes the optimal methods of stack sizing, and presents an example to demonstrate these methods. Published in 2005 by John Wiley & Sons, Ltd.     

基于变频控制技术的燃油气锅炉燃烧器的开发和应用

针对燃油、气或油气两用锅炉节能减排的需要,结合国内外燃烧器技术发展成果和趋势,提出了变频燃烧器设计理念并开发了相应的燃烧器产品,理论和应用证明,变频燃烧器较传统恒速燃烧器具有调节精准、灵活、节能、环保的特点,推广应用可使燃油、气锅炉的日常运行热效率提高1～2个百分点.     

An end-use energy analysis in a Malaysian public hospital

The commercial sector consumes 8–50% of the total energy consumption for a few selected countries around the world. An energy audit was conducted in a Malaysian public hospital to identify energy using equipment and their energy consumption breakdown. Different energy saving measures have been identified and applied for electrical motors used in this hospital. It was estimated that this hospital consumed about 19,311 MW h for the year 2008. It was also estimated that about 212 MW h, 250 MW h and 317 MW h of annual energy can be saved using energy-efficient motors at 50%, 75% and 100% loads, respectively. In addition, use of variable speed drives are expected to save 1735 MW h, 4048 MW h and 6361 MW h of annual energy consumption for 20%, 40% and 60% speed reductions, respectively. It was found that the payback period for using high efficiency motors at different loads is less than a year which is economically very viable. However, the use of variable speed drives was found to be economically viable for larger motors for higher speed reductions. The study also found that a sizeable amount of emissions can be reduced for the different energy savings measures applied for electrical motors.     

Optimization of water-cooled chiller system with load-based speed control

This study investigates the energy performance of chiller and cooling tower systems integrated with variable condenser water flow and optimal speed control for tower fans and condenser water pumps. Thermodynamic-behaviour chiller and cooling tower models were developed to assess how different control methods of cooling towers and condenser water pumps influence the trade-off between the chiller power, pump power, fan power and water consumption under various operating conditions. Load-based speed control is introduced for the tower fans and condenser water pumps to achieve optimum system performance. With regard to an example chiller system serving an office building, the optimal control coupled with variable condenser water flow could reduce the annual system electricity use by 5.3% and operating cost by 4.9% relative to the equivalent system using constant speed fans and pumps with a fixed set point for cooling water temperature control.     

Chillers energy consumption, energy savings and emission analysis in an institutional buildings

Chillers consume more than 40% of the total energy used in the commercial and industrial buildings for space conditioning. In this paper, energy consumption by chillers and chilled water pumps, condenser pumps and fan motors has been estimated using data collected by a walkthrough energy audit for the 16 faculties of the University of Malaya. It has been estimated that chillers and motors and pumps used in chillers consume 10,737 MWh (i.e. 51% of total energy consumption) of electric energy for different percentage of loadings. As chillers are major energy users, variable speed drives are applied in chillers to reduce their energy consumption. It has been estimated that about 8368 MWh annual energy can be saved by using efficient chillers at different loadings. It has also been found that about 23,532 MWh annual energy can be saved for chilled water supply pumps, condenser pumps and cooling tower fan motors by matching required speeds using variable speed drives for 60% of speed reduction. About 1,274,692 kg of CO₂ emission could be avoided for using energy efficient chillers at 50% load. It has been also found that about 2,426,769 kg CO₂ emission can be reduced by using variable speed drives for 60% speed reductions. Payback periods found to be only few months for using variable speed drives in chilled water pumps, condensers and fan motors.     

Optimal control of operation efficiency of belt conveyor systems

The improvement of the energy efficiency of belt conveyor systems can be achieved at equipment or operation levels. Switching control and variable speed control are proposed in literature to improve energy efficiency of belt conveyors. The current implementations mostly focus on lower level control loops or an individual belt conveyor without operational considerations at the system level. In this paper, an optimal switching control and a variable speed drive (VSD) based optimal control are proposed to improve the energy efficiency of belt conveyor systems at the operational level, where time-of-use (TOU) tariff, ramp rate of belt speed and other system constraints are considered. A coal conveying system in a coal-fired power plant is taken as a case study, where great saving of energy cost is achieved by the two optimal control strategies. Moreover, considerable energy saving resulting from VSD based optimal control is also proved by the case study.     

End-use energy analysis in the Malaysian industrial sector

The industrial sector is the second largest consumer of energy in Malaysia. In this energy audit, the most important parameters that have been collected are as follows: power rating and operation time of energy-consuming equipments/machineries; fossil fuel and other sources of energy use; production figure; peak and off-peak tariff usage behavior and power factor. These data were then analyzed to investigate the breakdown of end-use equipments/machineries energy use, the peak and off-peak usage behavior, power factor trend and specific energy use. The results of the energy audit showed that the highest electrical energy-using equipment was an electric motor followed by pumps and air compressors. The specific energy use has been estimated and compared with four Indonesian industries and it was found that three Malaysian industries were more efficient than the Indonesian counterpart. The study also found that about 64% electrical energy was used in peak hours by the industries and the average power factor ranged from 0.88 to 0.92. The study also estimated energy and bill savings using highly efficient electrical motors along with the payback period.     

Modeling and analysis of variable speed single phase induction motors with iron loss

Despite their usual low power ratings of single phase induction motors, they consume a considerable part of total motors energy consumption due to their large and ever-increasing quantity. The recent rising of oil prices and environmental crises has fortified the idea of energy saving practices in all applications; particularly in single phase induction motors due to their typical low efficiency. An essential requirement for this practice is the modeling and analysis of machine electrical losses under variable frequency operation. In this paper an improved steady state model of single phase induction motors is derived to investigate major motor characteristics like torque–speed, input power, output power, etc. A special emphasis is placed on accurately representing core losses at variable frequency. The winding currents phase difference is reintroduced as a fundamental motor variable to determine motor performances including losses and efficiency. An advanced computerized motor test setup is designed and built for on-line measurement of motor characteristics at different supply and operating conditions. The extensive experimental results, in good agreement with the simulation results based on the mentioned analysis, confirm the validity of the proposed model.     

Energy,exergy and economic analysis of industrial boilers

In this paper, the useful concept of energy and exergy utilization is analyzed, and applied to the boiler system. Energy and exergy flows in a boiler have been shown in this paper. The energy and exergy efficiencies have been determined as well. In a boiler, the energy and exergy efficiencies are found to be 72.46% and 24.89%, respectively. A boiler energy and exergy efficiencies are compared with others work as well. It has been found that the combustion chamber is the major contributor for exergy destruction followed by heat exchanger of a boiler system. Furthermore, several energy saving measures such as use of variable speed drive in boiler's fan energy savings and heat recovery from flue gas are applied in reducing a boiler energy use. It has been found that the payback period is about 1 yr for heat recovery from a boiler flue gas. The payback period for using VSD with 19 kW motor found to be economically viable for energy savings in a boiler fan.     

Applying condensing-temperature control in air-cooled reciprocating water chillers for energy efficiency

This paper reports on the modelling and findings of the energy performance of an air-cooled reciprocating multiple-chiller plant under the conventional head pressure control and the new condensing-temperature control in a subtropical climate. The simulation model was validated using the operating data of an existing chiller plant. As noted from this existing air-cooled reciprocating chiller plant, there was a substantial efficiency drop at part-load resulting from the head pressure control. If operating at variable lower condensing-temperatures based on the established operating mode of the condenser fans and compressors, it is shown that the chiller consumption can be maintained below 2 kW/refrigeration ton throughout the entire range of outdoor temperature and part-load conditions, giving an average efficiency of 1.08 kW/refrigeration ton. The energy imposition due to cycling on more condenser fans can be compensated by the reduced compressor consumption. Potential energy savings of 18.2 and 29% in the annual chiller consumption are achievable by applying the condensing-temperature control to two existing chiller plants studied. This supports the need to develop the condensing-temperature control as an improvement to the conventional head pressure control.     

Energy efficiency in pumps

In this paper, “energy efficiency” studies, done in a big industrial facility’s pumps, are reported. For this purpose; the flow rate, pressure and temperature have been measured for each pump in different operating conditions and at maximum load. In addition, the electrical power drawn by the electric motor has been measured. The efficiencies of the existing pumps and electric motor have been calculated by using the measured data.

Potential energy saving opportunities have been studied by taking into account the results of the calculations for each pump and electric motor. As a conclusion, improvements should be made each system. The required investment costs for these improvements have been determined, and simple payback periods have been calculated.

The main energy saving opportunities result from: replacements of the existing low efficiency pumps, maintenance of the pumps whose efficiencies start to decline at certain range, replacements of high power electric motors with electric motors that have suitable power, usage of high efficiency electric motors and elimination of cavitation problems.     

永磁调速节能技术在大功率循环水泵上的应用

永磁调速是目前最先进的非机械联接调速节能技术,本文对啮合面调整式大功率永磁调速器的构成、调速节能原理和应用情况做了简要阐述;分析胜利发电厂热网系统中的大功率循环水泵进行永磁改造后的调节特性,并与采用工频调速、变频调速两种方式的循环水泵进行节能效果的对照试验,将其应用情况以及节电经济性进行了分析,试验结果表明永磁调速节能效果明显,在大功率水泵风机等场合具有广阔的应用前景。     

水轮机节能技术在石化行业循环水冷却塔中的应用

水轮机利用循环水泵的富余扬程带动风机运转,以取代风机电机,实现节能的目的。以高效反击混流式水轮机在青岛石化循环水冷却塔中的应用为例,通过监测单开水轮机风机或电动风机时循环水的温降程度,来对比两种风机的运行效果,并在维持系统管网压力、流量不变的条件下,监测水轮机风机正常运行、转速减半、停运至系统稳定,以及重开风机系统、恢复稳定状态下的运行数据,测试水轮机风机运行对循环水系统的影响,从而验证水轮机节能技术的应用效果及经济效益。结果证明,循环水系统存在富余能量,水轮机利用该富裕能量带动风机运转,不增加循环水系统新的能耗;且水轮机风机降温效果与电动风机相当,可替代电机风机运行,满足精细化操作需要。采用水轮机运转风机,可优化循环水系统配置,减少维护保养费用,经济效益较高,具有较好的推广价值。     

变频装置在火电厂高压水泵电机节能中的应用

结合浙江浙能兰溪发电有限责任公司4台660 MW超临界机组凝结水泵变频改造,介绍变频调速实现水泵电机节能的工作原理,分析变频节能效果,总结变频技术实现节能降耗的效果。