THE MUMBAI REGIONAL CENTRE
INDIAN INSTITUTE OF CHEMICAL ENGINEERS
Volume 4 ................................................................................................................................................................................. Issue 2 May 2005
Energy is the theme of this issue of the Newsletter, and it comes to you at a time when our world’s hunger for energy appears insatiable. There have been several price surges of crude oil in the past, but what is unique about the present price spiral is that this is the first one driven by demand and not supply. The rising energy costs have once again brought energy management into sharp focus. The twin pillars of energy management are energy conservation and utilisation of alternate energy sources. While our government twiddles with the pricing of petroleum products, many others are subsidising the use of bio-diesel and ethanol. Even without the subsidy, the price of bio-fuels and fossil fuels have started to converge.
MRC had recently organised an extremely interesting talk on energy conservation through the use of variable speed drives. Sadly the attendance was thin. For all those who missed out on an excellent lecture, the complete presentation is provided in this issue. Monthly lectures are important to strengthen the fellowship and professional bonding among chemical engineers, and it is hoped that members attend in large numbers. Members are also requested to suggest potential topics or speakers from their contacts to sustain these programmes and make them rewarding.
Prof. S.P.Mahajan, Council Member passed away this month. May his soul REST IN PEACE
Oil continues to remain the dominant source of energy with a share of 40% in primary energy. Coal is another important primary energy source. Year 2004 witnessed extreme turbulence in world energy market with unprecedented growth in demand. Renewable energy sources, which are abundant in India, should be exploited fully as this can replace a substantial part of oil consumption.
One of the best options available is to promote energy conservation efforts. Since 1973, US Economy has grown 126% while energy usage has increased by only 30% owing to energy efficiency efforts, a clear indicator of opportunities for energy optimisation without affecting productivity.
Energy conservation potential of Indian economy has been assessed at 23% with maximum potential in industrial and agricultural sectors. Energy saving of about 10% is possible by replacing substandard foot valves by energy efficient ones and by replacing rusted GI pipes with low friction PVC pipes. Energy saving can be achieved in domestic sector by using energy savers in lighting circuits, air-conditioners, refrigerators & geysers, energy efficient fluorescent lamps in place of conventional bulbs etc.
Transport sector consumes about 22% of the commercial energy and is the second largest consumer of energy next to Industry. Energy conservation in this sector can be achieved by promoting energy efficient modes of transportation like electric traction instead in railways. Efficiency of road transport can be improved by adopting energy efficient engine technologies in vehicles and improving the maintenance practices.
Prof. S.P Mahajan, - An Obituary
(22/9/39 to 12/5/05)
Prof. Sudarshan Prasad Mahajan was born on Sept. 22nd 1939 and obtained his B Tech degree in Chemical Engineering from Punjab University, Chandigarh in 1962. He joined IIT Bombay and obtained his M.Tech in Chemical Engineering in 1964 and then joined the faculty as lecturer. He was awarded the Ph.D in 1973 from IITB. His main areas of interest were Environmental Engineering and Multi-phase flow applications. He was also a visiting professor at Asian Institute of Technology, Bangkok and Institut fur Technische Thermodynamik und Kaltetechnik, University of Karlsruhe, Germany. He became full professor at IIT Bombay in 1984. He was head of IITB’s Centre for Environmental Science and Engineering, prior to his retirement from IIT in 2001. Prof. Mahajan has over 80 publications to his credit. He is the author of the book, Pollution Control in Process Industries, Tata McGraw Hill, New Delhi, 2002. Prof. Mahajan had also collaborated with Lund University, Sweden, Twente University, Netherlands and Commonwealth Institute of Learning, Canada, in environmental studies.
Prof. Mahajan was actively involved with the IIChE and was a council member from 1997 to 2000. He was again elected to the council in 2003. Besides, he was a member of the executive committee of the Mumbai Regional Centre.
VARIABLE SPEED DRIVES
The most commonly used form of power is electricity. Most of this power is used in the industries for running motors. Amongst these motors, most commonly used ones are induction motors. Sometime, especially in the high power levels, synchronous motors are also used. These motors run at a speed proportional to the frequency of power supply. Variable Speed Drives allow us to change the frequency of power supply to the motors, thereby change the speed of motor itself. These VSDs are electronic equipment to be provided between the source of power and the motors to change the frequency of power supply to the motors.
Electric motors running at constant speed are designed to deliver much higher amount of power than needed for the applications for they are being used. The extra power is then nullified in some braking devices like control valves in the case of fluid flows. VSDs allow us to deliver just the required amount of power, thereby avoid the wastages in the braking devises.
This course covers the energy savings in handling of fluids where the pumps, compressors or blowers themselves are used as final control elements by providing VSDs for them. This discuses the potential areas for energy savings depending on the plant topologies. This also covers many applications like cooling towers, boiler feed water pumps etc. Control strategies for some complex applications are also covered. This also tells about retrofitting the VSDs into the existing motors or how to use them in the case of new motors.
In the second part of the course, this covers the functioning of VSDs. This also discusses precautions one needs to take during the selection of these drives. This also discusses how the drives can inject harmonics and corrupt the source of power supply, and thereby cause problems to other equipment in the neighborhood. An introduction is made to the IEEE519 standards, which talks about the permitted levels of harmonics that can be tolerated. How to minimize the generation of harmonics and how to provide mitigation if they are getting injected into the system is also covered.
In today’s competitive world one needs to innovate to survive in business. This innovation is essentially to reduce the gap between the value and the cost of the products they supply. This presentation essentially covers the cost reduction by saving an expensive input in almost every industry, i.e. electricity. The most commonly used form of energy is electricity for running motors. Amongst these motors, most commonly used ones are induction motors. Sometime, especially in the high power levels, synchronous motors are also used. These motors convert much more energy than needed by running at a higher speed. This is because they run at a speed proportional to the frequency of power supply, which was earlier, difficult to vary. Variable Speed Drives allow us to change the frequency of power supply to the motors, thereby change their speed. These VSDs are electronic equipment to be provided between the source of power and the motors. Electric motors are designed to deliver much higher amount of power than needed for the applications for they are being used. The extra power is then nullified in some braking devices like control valves in the case of fluid flows. VSDs allow us to deliver just the required amount of power, thereby avoid the wastages in the braking devises.
Fig. 1 shows the conventional method of controlling flow in a pump discharge.
In this method, pump is designed to deliver much more pressure than needed since the control valve do its job of regulating the pressure only by wasting it. In order to avoid the wastage of power, the pump itself should be capable of delivering just the required amount of energy under varying load conditions.
In Fig.2 one can see the power coming to the motor from a variable speed drive. Here the motor delivers just the required amount of power. Since the motor itself can do the functions of the final control elements, it obviates the need for any control valves and saves power.