Title of Invention

CONDENSATE DEPRESSION MONITOR

Abstract

A condensate depression monitor for Monitoring thermal loss in a condenser of a thermal power station comprising a condenser (1) with a pressure transducer (2) and a temperature transducer (3) for providing corresponding pressure and temperature analog signals, a multiplexer (4) for acquiring said analog signals and providing them to an A/D converter (7) for converting to digital signals, a microcontroller (8) for obtaining the digital signals. pertaining to pressure and temperature processing said digital signals for displaying the condensate depression on a seven segment LED display (11).

Full Text

The invention relates to a condensate depression monitor to monitor thermal loss in the condenser associated with thermal power station. Considerable thermal loss in the condenser due to cooling of condensate below its condensing temperature has been observed during energy audit studies conducted in Thermal power stations. The steam which enters the condenser is condensed to liquid form. The condensed liquid which is called feed water is then pumped by the condensate extraction pump into low pressure regenerative feed water heaters (LP heaters) where it gets heated up. There are disadvantages associated with the present system of low pressure regenerative feed water heater drain. The process involves heating of the feedwater in the condenser and subsequent heating in the feedwater heaters.After condensation, the liquid cools below its saturation point, for vacuum e.g. if the steam condenses at a of 10 kPA the saturation temperature is 46 C. However the condensate leaves the hotwell at 42 to 45 C, hence it is sub cooled by 1 to 4 C. This drop in the temperature of feed water leaving the hotwell below its saturation temperature is called as condensate subcooling or condensate depression and is in direct contrast to the heating requirements of the LP heaters. The margin by which the condensate is sub-cooled in the condenser will have to be compensated by additional loading on the LP heaters there by reducing thermal efficiency. If the margin of condensates depressions is precisely known control action can be taken either by human loop or through electronic controls. The overall saving in energy if the condensate depression is reduced to O C is about 0.1 X improvements in the overall efficiency of the unit. There is disadvantages associated with the present system of estimating the depression and subsequent control action. In the prevalent method of measuring condensate depression in the operator would read the pressure from the pressure transmitter and run to the steam tables to find the saturated temperature and manually estimate the depression and Mould run back to take some control action. By the time the operator finishes this drill the temperature would have changed and he may have to begin this all over again and this process would go on. Therefore the main object of the present invention is to provide a simple and effective condensate depression monitor. To circumvent this problem an instrument to display the condensate depression directly is very much essential as the depression is directly read out from the display which will enable corrective action to be taken immediately. According to this invention there is provided a condensate depression monitor for monitoring thermal loss in a condenser of a thermal power station comprising a condenser with a pressure transducer and a temperature transducer for providing corresponding pressure and temperature analog signals, a multiplexer for acquiring said analog signals and providing them to an A/D converter for converting to digital signals, a microcontroller for obtaining the digital signals pertaining to pressure and temperature processing said digital signals for displaying the condensate depression on a seven segment LED display. The nature of the invention, its objective and further advantages residing in the same will be apparent from the following description made with reference to non->limiting exemplary embodiments of the invention represented in the accompanying drawings. Figure 1 shows the block diagram existing method of control of condensate depression; Figure 2 shows the schematic diagram of condensate depression monitor according to the invention. Figure 3 shows a flow chart of the instrument to measure condensate as per invention. Figure 1 shows the method of condesate control according to the prior art. The condensor (1) is provided with a pressure gauge (12) and a thermometer (13) on which the operator constantly monitor by reading the pressure and temperature. The operator then refers to steam table (14) and calculates the depression (15). The operator then rushes to the control room (16) and adjusts inlet and outlet valves (17) as required. The present invention called condensate depression monitor is used to display the condensate sub-cooling in a condenser (1) of a thermal power station. The fundamental prinicpal behind the instrument is to give a temperature output based on a pressure measurement. Thus based on the vapors pressure relation between pressure and temperature the temperature is measured as an output parameter. The Block diagram of the digital instrument developed is pressure shown in Fig. 2. The analog signal pertain to and temperature (3) are acquired by the multiplexer (4) and properly amplified (5) to the range suitable to the A/D converter (7 ). The acquired signals are converted to digital signal by the analog to digital converter (7 ), The micro controller (8/ obtains this digital signal for processing, display and control action. The Microcomputer (8) used is Intel 8031. The implementation of this invention is a mixture of hard ware and software and can be broadly classified as follows: Figure 3 shows the flow chart of the instrument to measure condensate. i. Acquiring and processing the analog signal ( hard ware; ii. Software control for the above. The pressure transducer (2) which is used is an absolute pressure transducer (2), the transducer gives a 4 to 20 mA signal which is acquired along with the mV signal from the thermocouple of the temperature transducer (3) with the help of a multiplexer (4) circuit. The output of this multiplexer (4) is connected to an amplifier (5) IC to amplify the signal to a level acceptable to the analog to digital converter (7; IC. A sample and hold circuit (6^ IC is connected in between the multiplexer (4; and the ADC {1j to sample the circuit for a brief interval. The analog to digital converter {1j configured in unalarmed which accepts input analog signal in the range of 0 to 10 V. The micro controller (8) IC 8031, acquires, the digital signals pertain to the pressure and temperature from the initial storage in the random access memory (RAM; it also fetches the process control program from the EPROM performs the calculation as per the program stored and outputs the digital signal to IC 8279 through Buffers and latches (9) which effectively controls the display and keyboard (lO)o functins of the micro controller (8). The output of IC 8031 is passed through a prostate buffer and latches (9) to prevent the data bus from interfering with the address bus. A decoder is used to decode the 3 inputs to 8 outputs to facilitate the display on seven segment LED display (11). The signal once acquired has to be processed for the desired results. The digital signal pertaining to the pressure signal is processed to indicate the saturated temperature (T by sat using the formula shown below: Where A = +0.426776 E +02 B = +0.389270 E +04 C = -0.948654 E +01 Once Tsat. is computed The acquired physical temperature is subtracted from this to display condensate depression. In view of the transcendental functions involved in the calculation of the saturation temperature, the programming of the mathematical equations has to be done at High level language like C. Accordingly the program segments covering the A-D conversion and temperature display are written in ALP. However, the entire program is written as a single file in a PC and is compiled to the object code of 8031. This binary file is converted to hex and downloaded into the EPROM chip. The flow chart for the process is shown in Figure 3. A typical specification of the condensate depression monitor is given below: The invention described hereinabove is in relation to a non - limiting embodiment and as defined by the accompanying claims. WE CLAIM: 1. A condensate depression anointer for oionitorinQ thermal loss in a condenser of a thermal poker station comprising a condenser (1) with a pressure transducer (2} and a temperature transducer (3) for providing corresponding pressure and temperature analog signals, a multiplexer (4) for acquiring said analog signals and providing them to an A/D converter (7) for ccwiverting to digital signals; a microcontroller C8> for obtaining the digital signals pertaining to pressure and temperature processing said digital signals for displaying the condensate depression on a seven segment LED display (11). 2. The condensate depression monitor as claimed in claim 1, wherein the signal provided by the pressure transducer C2J is a 4 to 20 flag signal and the signal provided by the temperature transducer (3) is a mV signal. 3. The condensate depression monitor as claimed in claim 1, wherein said A/D converter (7) is configured in a univocal mode and an amplifier C5> is provided to amplify the signals which are acceptable inputs to the A/D converter C7), in the range of 7 to 10 volts. 4. The condensate depression monitor as claimed in claim 1, therein said microcontroller (8) is an 1C 8031 the output of which is passed through tristage buffers and latches (9) to prevent the data from interferring with the address bus. 5. The condensate depression monitor as claimed in claim 1, wherein a sample and hold circuit (6) is provided between said multiplexer (4) and said A/D converter (7> for sampling the circuit for brief intervals. 6. The condensate depression monitor substantially as herein described and illustrated in the accompanying drawings, of figure

Documents:

0024-mas-2001 abstract.jpg

0024-mas-2001 abstract.pdf

0024-mas-2001 claims.pdf

0024-mas-2001 correspondence-others.pdf

0024-mas-2001 correspondence-po.pdf

0024-mas-2001 description (complete).pdf

0024-mas-2001 drawings.pdf

0024-mas-2001 form-1.pdf

0024-mas-2001 form-19.pdf

0024-mas-2001 form-26.pdf

0024-mas-2001 petition.pdf

24-mas-2001 claims granted.pdf

24-mas-2001 description (complete) granted.pdf

24-mas-2001 abstract granted.pdf

24-mas-2001 drawing granted.pdf