International Journal of Emerging Technology and Advanced Engineering - PDF document

International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 4 , Issue 2 , February 2014 ) 267 Contrivance of Optical Foam Detection System for Transformer Oil Filtering M achine Dhiraj Ladhe 1 , Pranay Chavan 2 , Nikhil Jain 3 , Animesh Degaonkar 4 1 , 2 , 3 , 4 Universal College of Engineering and R esearch, Sasewadi, Pune Abstract — In recent manufacturing industries it is the competition and maximum trials to automate the system, decrease the working cost and maximize the ease of work. Similarly the manufactures of transfo rmer oil fi ltering machine requires a constant observation by human personnel to check the rise of foam level in the degassing chamber. The foam can cause the problems in working of the vacuum pump so it is important to safeguard it. F or this purpose we developed an optical based systems which can overcome the system constraints like temperature, pressure and detect rise in foam automatically and activate the control system with the help of relay. The developed optical foam detection systems are non - intrusive, cheap a nd easy to implement. Keywords — Foam Detection, Optical Sensor, Retro - reflective. I. I NTRODUCTION Untreated transformer oil in a working transformer usually contains dissolved water in the range of 50 to 60 PPM and dissolved gases in the range of 10% to 12%. Dissolved moisture and gases along with other contaminants (like sludge) impair the efficiency of the transformer. It is evident that the content of dissolved moisture, gases and other contaminating agents of oil are distinct in the transformer and mainly depend on the place of application of the transformer, like the distribution level transformer, transmission level transformer, generation level transformer, locomotive transformer, furnace transformer etc. In order to achieve the desired transformer perfo rmance and an improved transformer life, it is essential to maintain the oil parameters to the prescribed levels as per the standards. Oil parameters, more appropriately the dielectric properties of oil as insulating media, can be maintained at prescribed levels by regular filtration, degasification and dehumidification of oil. Degasification and dehumidification of oil is based on the principle of separation of components (gases, water) under distinct pressures (here vacuum), viz. on component parameters l ike, solubility in case of gases and boiling point in case of moisture. Transformer oil filter machines provide appropriate and customized solutions for distinct transformer oil filtration. This process foam presents in transformer oil degassing chamber . T here are two reasons for foaming, first: air enters from the inlet side connection (inlet hose) of the machine, second: high moisture and gas content in the oil. Under high vacuum condition in the degassing chamber, the dissolved moisture and gases as well as the leakage air entering from the inlet side, have a tendency of expanding which is seen in the form of foam. Excess foaming is not a desirable feature as it contaminates the vacuum pump oil and makes it turbid. Foam should not exceed level in degassin g column. Maintaining the oil level in the degassing chamber is crucial. Excess rise of the level may cause oil to flow in the vacuum pump, in fo rm of foam. If this foam is not detected then it will be passed to the vacuum pump which is un desirable. So the detection of this foam is major problem in oil filtering industries due to certain constraint on it like temperature and pressure of the system. II. E XISTING T ECHNIQUES F OR F OAM D ETECTION 1. DP gauges 2. Capacitance probes 3. Electromagnetic radiation 4. Neutral backsca tter 5. Sonic echo devices 6. Flow meters 7. Sight glasses Most of these do not of fer early foam detection. These devices only detect foam after severe foaming has occurred and often not until the foam has upset downstream operations . [4] Because foam buildup can o ccur in many production, refining and petrochemical processes, the need for a technology that acts as an early warning system, accurately detects the presence of foam, responds to changing foam concentrations . For this purpose we design a system which over comes the constraint and gives fast output signal to the control circuitry. International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 4 , Issue 2 , February 2014 ) 268 III. T HE D EVELOPED F OAM D ETECTION S YSTEM The present work is concern with the development of optical foam detect ion system in transformer oil filtering plant. As the study of above co ntact type detection methods gives us undesirable performance of system due to their restriction of temperature limi t that is ambient temperature. F or this purpose we developed a non - contact type optical foam detection system which does not have any constr aint like pressure a nd temperature. Optical sensors work by converting the rays of light i nto electric signals. Generally an electrical trigger is connected with the optical sensor. There are different types of optical sensors, such as photo - detectors, fib er optics, and proximity detectors. [1] [2] [3] Fig. 1 De - gassing chamber with apparatus setup under foaming condition . In the above foam detection system we used the photoelectric sensor for detecting the presence of an obstruction which is in the form of severe foam. We placed the sensor on to the toughened glass window by mechanical support. The required supply to the sensor is provided by a power modulator or an adapter and the output signal of sensor is given to the cont rol circuitry for alarm purpo se, w hich operate under faulty condition. A. Photoelectric S ensor Photoelectric Sensors detect objects, changes in surface conditions, and other items through a variety of optical properties. A Photoelectric S ensor consists primarily of an E m itter for emittin g light and a R eceiver for receiving light. When emitted light is interrupted or reflected by the sensing object, it changes the amount of light that arrives at the Receiver. The Receiver detects this change and converts it to an electrical output. The li ght source for the majority of Photoelectric Sensors is infrared or visible light (generally red, or green/blue for identifying colors). F eatures of Photoelectric S ensor 1) Long Sensing Distance : A Through - beam Sensor, for example, can detect objects more tha n 10 m away. This is impossible with magnetic, ultrasonic, or other sensing methods. 2) Virtually No Sensing Object Restrictions : These Sensors operate on the principle that an object interrupts or reflects light, so they are not limited like Proximity Sensor s to detecting metal objects. This m eans they can be used to detect virtually any object, including glass, plastic, wood, and liquid. 3) Fast Response Time : The response time is extremely fast because light travels at high speed and the Sensor performs no me chanical operations because all circuits are comprised of electronic components. 4) High Resolution : The incredibly high resolution achieved with these Sensors derives from advanced design technologies that yielded a very small spot beam and a unique optical system for receiving light. These developments enable detecting very small objects, as wel l as precise position detection with high resolution. 5) Non - contact Sensing : There is little chance of damaging sensing objects or Sensors because objects can be detect ed without physical contact. This ensures years of Sensor service. 6) Color Identification : The rate at which an object reflects or absorbs light depends on both the wavelength of the emitted light and the color of the object. This property can be used to det ect colors. 7) Easy Adjustment : Positioning the beam on an object is simple with models that emit visible light because the beam is visible. [5] [6] B. Sensing Method of S ensor There are three sensing methods that is diffuse type, retro - reflective type and beam type. For this type of application retro - reflective type method is suitable. International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 4 , Issue 2 , February 2014 ) 269 1) Retro - reflective T ype : The Emitter and Receiver are installed in the same housing and light from the Emitter is normally reflected back to the Receiver by a Reflector installed on the opposite side. When the sensing object interrupts the light, it reduces the amount of light received. This reduction in light intensity is used to detect the object . Fig. 2 Retro - reflective priciple Features of R etro - reflective Sensing distance ran ges from several centimeters to several meters. Simple wiring and optical axis adjustment (labor saving). Operation not greatly affected by the color or angle of sensing objects. Light passes through the sensing object twice, making these Sensors suitable f or sensing transparent objects. C. Selection Factors for S ensor 1) Sensing object :  Size and shape (vertical x horizontal x height)  Transparency (opaque, semi - transparent, transparent)  Velocity V (m/s or units/min.) 2) Sensor :  Sensing distance (L)  Restrictions on s ize and shape  Need for side - by - side mounting  Mounting restrictions (angling, etc.) 3) Environment :  Ambient temperature  Presence of splashing water, oil, or chemicals  Others D. Process Flow of Foam Detection S ystem Fig. 3 Process flow of foam detectio n system When there is a formation of foam in degassing cham ber during transformer oil filte ring process, the photoelectric sensor with retro - reflective type senses the obstruction to the signal which is send by transmitter and receive by reciever of senso r . Then this signal is passed to the relay circuit in the system to operate the alarm circuit in the plant to stop the formation of the foam. This is very simple and highly reliable with the mechanical disturbance of the machine. IV. C ONCLUSION The photoelectr ic sensor and the relay circuit were the basic components employed in the development of the optical foam detection systems presented in this work. International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com ( ISSN 2250 - 2459, ISO 9001:2008 Certified Journal, Volume 4 , Issue 2 , February 2014 ) 270 This system also detects the small amoun t of foam present in the system. This technique of foam d etection is very cost effective as compared to other once because it mini mise the labour cost due to auto mated system of f oam detection. Our designed optical foam detection system using phot o electric sensor for transformer oil filte ring machine is highly e fficie nt and reliable with minimisin g the labour and operating cost. REFERENCES [1] MUSAZZI, Sergio. Optical particle sizes for on - line applications in industrial plants. Optical and Lasers in Engineering , v.39, p.141 - 154, July 2001 [2] HORVAT, Daria Laser ultrasonics for bubbly flow detection. Ultrasonics , v 36, n 1 - 5, p. 565 - 568, February 1998 [3] RAMAYA, A. Venkata. Bubble detection with horizontal pressure gradient mesuarements in gas - fluidised beds. Powder Technology, v.97, p.7 7 - 84, November 1997 [4] G.Fransen, R. Carbajal, and I. Guevara, Agar Corporation, Foam Detection in Process Units, 31 May – 3 June 2009 [5] Chen Jie, Huang Hong. Sensor and Detection Techniques. [M] Beijing: High Education Press. [6] Liu Yingchun. Design Principle of Se nsor and Application. [M] Changsha: National University of Defense Technology Press.