Title of Invention

A METHOD OF ASH LEVEL MON ITORING ELECETROSTATIC PRECIPITATOR

Abstract

1. . A method of ash level monitoring for electrostatic precipitators' hopper, comprises A. Using an ash level sensor converting the variable RF admittance analog signal into variable frequency. B. Conversion of variable frequency into current modulation on the single twisted pair supply power 1 i n e . C. Trap the variable frequency from the power supply line using OPTO couplers. D. Reference frequency of each sensor stored in EEPROM data memory. E. Digital tuning to set the value for 'Ash high level ' . F. Integration of sensors. G. Alarm signal through Relay output.

Full Text

The present invention relates to ton i mprovrc rcl' ash level m o n i t o r i n g f o r e 1 e c t r o s t a t i c p r e c i p i t a t o r s . (Ft* Id of th* Electrostatic prec ipi t ators are used for collecting dust particles from dust laden gases. For example, in a thermal power plant electrostatic precipitator is used for collecting fly ash from exhaust gas or flue gas from the furnace. This reduces pollution of the atmosphere. The hoppers at the bottom of electrostatic precipi tator collects the fly ash and the ash is disposed to ash silos periodically by wet or dry ssh handling system. The ash level measurement, sensors probes are fixed on the hoppers at a definite level. Power and signal wires are run to their respective ash level indicators at ground level for h u m a n i n t e r a c t ion. Prior art In the conventional ash level indicator the probe head electronics contains RF admittance type sensing electronics. The analog signal from the sensor is passed on to analog window compare electronics in ash level indicator at hopper bottom. The set level is to be tuned very precisely by the analog potentiometer in the level indicator. This set point or the analog signal is prone to drift due to temperature variations and lead to unstable operation. Limited length of PTFE cable for signal and a separate cable for power supply has to be run between sensor and level indicator. In most cases individual level indicators with its sensor probes are required for every point of level measurement. Two cables - one for power and one for signal has to be run from (": a c h 1 e v e 1 i n d i c a t o r t o s e n s o r head. Object of t»ne Invention The ash level indicators as of now known in the art of electrostatic precipitators has certain limitations, vis. tuning the analog potentiometers for level setting in ash level indicators mounted near hopper bottom is very critical and unstable in operation. Healthy operation of every indicator can not foe ascertained easily. Limited length of PTFE insulated signal cable and power cable has to be run between sensor and lev e .1 i n d i c a t o r. Thus it is another object of this invention to propose such a method of ash level monitoring for use in electrostatic precipitators, which ensure reliable digital turning for level «_> "*" setting and for stable operation simple single twisted pair wire carrying signal and power between sensor probe and centralized ash level monitor. 64 numbers of sensors' healthiness and effective operation can be monitored by single ash level monitor at control room and has serial communication with the host system. BuMnitry of the Invention The present invention relates to a method of ash level monitoring for electrostatic precipitators. This ensures reliable digital tuning for level setting and for stable operation. A single twisted pair wire is used for carrying signal and power between sensor probe and centralized ash level monitor. 64 numbers of sensors' healthiness can be monitored by single «sh level monitor- at control room. It also has serial communication with the host system. This method is that the sensor's variable RF admittance analog signal is converted into variable frequency and the frequency is modulated on its power supply lines. At the monitoring end, the variable frequency is trapped from and processed indigital way for level setting and trouble shooting. Thus the present invention provides a method of ash level monitoring for electrostatic precipitators' comprising A. Using an ash level sensor converting the variable RF admaittance analog signal into variable frequency. B. Converting variable frequency into current modulation on the single twisted pair supply power line. C. Trapping the variable frequency from the power supply line using OPTO couplers, D. Actuating reference frequency of each sensor stored in EEPROM date menory? E. Digital tuning to set the value for 'Ash high 1 eve 1 ' j F. Integrating the sensors^ G. Signaling the alarm through Relay output. The invention will now be explained in further details with reference to the accompanying drawings, wherein - Fig.l shows the conventional ash level indicatory Fig.2 shows an improved ash level monitor. With reference to the drawings, in the conventional ash level indicator, the probe head e 1 ectron ics (0.1. ) contains RF admittance type 'sensing electronics. The analog signal from the sensor is passed on to analog window compare electronics (03) in ash level indicator at hopper bottom. The set level is to be tuned very precisely by the analog potentiometer in the level indicator. This set point or the analog signal is prone to drift-due to temperature variations and lead to unstable in operation. Limited length of FIFE cable (02) for signal and a separate cable for power supply has to be run between sensor and level indicator. In most cases individual level indicators with its sensor probes are required for every point of level measurement. Two cables - one for power and one for signal has to be run from each level indicator to sensor head. In the probe head electronics, the signal (RF admittance type) from the sensor (04) is converted into variable frequency. This frequency is super imposed in the power supply lines (signal twisted pair wire) feeds the power to the (•? 1 ectronics (ø5 ) . The centralized ash level monitor in the ESP control room has a digital scanner with OPTO coupled frequency / pulse trap circuit (06) at its front end. The power supply lines to every sensor is connected through its pulse trap circuit. The special microcontroller based integrated ash level monitor (07) can handle up to 64 sensors. The frequency output from the sensor of the empty hoppers can be stored as a reference value in the EEPROM of the microcontroller. Once the frequency crosses above the reference plus constant value, then it is declared that the hopper has reached the set point i. If the frequency from sensor- is far below or above normal operating range, then there could be fault :i. n t h e s e n sor e 1 ec t ron i c s ii. If there is no signal and the OPTO output is always high, then the signal cum power cable could b e t r u n c a t e c i. Hi. If there is no signal and the OPTO output is always low,, then the signal cum power cable could b e s h o r t c i r c: u i t e d . The above error status will be displayed with specific: sensor and cable number. the status of all hoppers with interactive alphanumeric display and supports link with host computer. The 64 relay outputs that provided in the integrated ash level monitor can be used to control any equipment like High Voltage Transformer based on the ash level reaching high. We c 1 aim; 1. . A method of ash level monitoring for electrostatic precipitators ' hopper, comprises A. Using an ash level sensor converting the variable RF admittance analog signal into variable frequency. B. Conversion of variable frequency into current modulation on the single twisted pair supply power 1 i n e . C. Trap the variable frequency from the power supply line using OPTO couplers. D. Reference frequency of each sensor stored in EEPROM data memory. E. Digital tuning to set the value for 'Ash high level ' . F. Integration of sensors. G. Alarm signal through Relay output. 2. The method as claimed in claim 1, wherein said variable frequency ranges from 100 Hz to 1500 Hz. 3. The method as claimed in claim 1, wherein said trap variable frequency is through Resistor and Capacitor (RC) network with OPTO coupler which separates the modulated frequency from the power supply lines. 4. The method as claimed in claim 1, wherein said EEPRQM is a part of Micro-controller in the monitoring system. 5. The method as claimed in claim 1, wherein said digital tuning is to set the value of "Ash Level High" by adding a constant value to the reference value of each sensor, the constant value is fed through the numeric key pad provided on the moni tor. 6. The method as claimed in cla'im 1, wherein said integration covers, 64 sensors with a common monitor. 7. The method as claimed in claim i, wherein said Relay output is for ash level high indication. 8. The method of Ash level Monitoring as disclosed in the complete specification and as illustrated by way of drawing.

Documents:

163-DEL-2003-Correspondence-Others-(20-10-2010).pdf

163-del-2003-correspondence-others.pdf

163-del-2003-correspondence-po.pdf

163-del-2003-description (complete).pdf

163-del-2003-description (provisional).pdf

163-del-2003-drawings.pdf

163-del-2003-form-1.pdf

163-DEL-2003-Form-15-(20-10-2010).pdf

163-del-2003-form-19.pdf

163-del-2003-form-2. 1.pdf

163-del-2003-form-2.pdf

163-del-2003-form-3.pdf

163-del-2003-form-5.pdf

163-del-2003-gpa.pdf