GB2105028A - Boiler feed contamination monitor - Google Patents

Boiler feed contamination monitor Download PDF

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Publication number
GB2105028A
GB2105028A GB08126175A GB8126175A GB2105028A GB 2105028 A GB2105028 A GB 2105028A GB 08126175 A GB08126175 A GB 08126175A GB 8126175 A GB8126175 A GB 8126175A GB 2105028 A GB2105028 A GB 2105028A
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United Kingdom
Prior art keywords
water
contamination
detector
monitor
detectors
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08126175A
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GB2105028B (en
Inventor
Gillies David Pitt
Simon Edwin Avis
Stephen Ian Norman Gregorig
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ITT Industries Ltd
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ITT Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ITT Industries Ltd filed Critical ITT Industries Ltd
Priority to GB08126175A priority Critical patent/GB2105028B/en
Priority to ES1982266978U priority patent/ES266978Y/en
Publication of GB2105028A publication Critical patent/GB2105028A/en
Application granted granted Critical
Publication of GB2105028B publication Critical patent/GB2105028B/en
Expired legal-status Critical Current

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47Scattering, i.e. diffuse reflection
    • G01N21/49Scattering, i.e. diffuse reflection within a body or fluid
    • G01N21/53Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
    • G01N21/532Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke with measurement of scattering and transmission
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/18Water
    • G01N33/1826Organic contamination in water
    • G01N33/1833Oil in water
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00Water conservation; Efficient water supply; Efficient water use
    • Y02A20/20Controlling water pollution; Waste water treatment

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

Contamination, particularly oil in water, is detected by passing the water through a cell (1) across which a laser beam is directed from a window (3) to a window (6) and to a direct detector (5). Oil droplets in the water cause scattering of the laser beam to another window (9) at an angle to the laser beam, and thence to a scatter detector (8). From the outputs of the detectors (5, 8) an output signal related to the contaminant (oil) level in the water is obtained. The output signal is applied to a sample valve trigger (16) circuit which is such as to actuate a valve to obtain a sample of the water when a predetermined contamination level is exceeded. The output can also be applied to a chart recorder (14) and a direct contamination-reading instrument (15) if desired. Thus contamination levels are monitored "on line" with provision for confirmatory chemical analysis when predetermined contamination levels are exceeded. <IMAGE>

Description

SPECIFICATION Boiler feed contamination monitor This invention relates to the detection of contamination in water, in particular, but not exclusively, oil, in boiler feed water, such as for large steam turbine electricity generating sets.
Water quality monitoring is an essential aspect of generating electricity with steam turbines. The turbines are supplied with very high pressure super-heated steam, for example at 165 bars and 568"C. Some of the steam condenses within the turbine chamber and is pumped out for future recirculated use.
Pressure within the turbine chamber is kept high in order to prevent the oil-lubricated turbine bearings leaking into the chamber, since it is important that deposits do not form within the boiler tubes at these pressures. A very thin film of oil on the tube inner surface has the same insulating effect as scale many times the thickness of the oil. Explosions are possible if the pipes become constricted and hot spots occur, and there is also an increase in system inefficiency.
Generally the feed water systems are of a closed type in order to prevent contamination from the outside, and the water is conditioned in order to make it suitable for boiler feed.
The higher the temperatures and pressures employed the less tolerance there is to any form of contamination. Filtering, de-aerating and de-ionising etc. and the addition of conditioning chemicals are employed to condition the water before use. However, oil leaking into the system from the turbine bearings can cause serious trouble particularly if scale of any type is present, since it causes scale to form faster and increases the overheating effects. This is particularly important in high pressure boilers. Emulsified oil is exceptionally difficult to remove from the feed water, and usually even passes the filters employed. In addition to oil, the feed water may be contaminated with extraneous particulates, such as rust.In shift systems now being employed some boilers are shut down during "off-peak" hours, and during subsequent start up the water can contain relatively high concentration levels of rust, for example, such as 1 ppm, and such water must not be recirculated. Thus upon bringing the boilers back into operation it is critical for water quantity to be rendered acceptable as quickly as possible whereby to minimise the quantity of make-up water that has to be used. The cost of the highly pure water necessary for use in high pressure systems is rising rapidly and boiler water, in particular, condensate, monitoring for water quality, oil content and other suspended soilds is an important economic consideration in plant operation. There is, therefore, a requirment for simple on-line instruments to monitor water quality from both safety and economic points of view.
According to the present invention there is provided a water contamination monitor comprising a cell through which the water is allowed to flow, a light source coupled to one side of the cell, one or more detectors arranged at an angle to the light beam to detect light scattered from contamination in the water, means to provide an electrical output related to the contaminant level from the detector output or outputs, and trigger circuitry arranged to provide an actuating signal for operating water sample valve means, in use of the monitor, for a predetermined time upon detection of predetermined contamination levels whereby to obtain a sample of the water having contamination above the predetermined level.
According to another aspect of the present invention there is provided a method of monitoring the quality of boiler feed water for electricity generating sets comprising the steps of passing the water through a conduit, passing a light beam through the water in the conduit, detecting with respective detectors the light beam both after direct passage through the water and after scattering thereof by contamination in the water, obtaining a signal related to the contamination level from the detector outputs and applying the signal to a circuit arranged to trigger a water sampling valve when a predetermined contamination level is exceeded, whereby to obtain a sample of the contaminated water for chemical analysis.
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a schematic of a contamination detector and sample arrangement according to the present invention; Figure 2 is an exploded view of the detector cell of the arrangement of Fig. 1; Figure 3 shows schematically the light paths through the cell; Figure 4 shows an optical transmitter (laser drive) circuit with automatic gain control; Figure 5 shows an optical receiver and amplifier circuit; Figure 6a shows a possible sampling system relative to contaminant level; Figure 6b shows a triggered sampling system relative to contaminant level, and Figure 7 shows a contaminant sampling trigger circuit.
The contamination detector and sample arrangement shown in Fig. 1 comprises a lightscattering cell 1 through which water whose quality is to be monitored is passed. Block 2 comprises a light source, for example, a semiconductor infra-red laser and a drive circuit therefor. The laser, which may be of the GaA1 As or GaA1 P type, is coupled to a window 3 in the cell 1 via a fibre optic system 4 and transmits light in the infra-red region of the spectrum across the cell to a laser output level detector 5 (direct) via a window 6 and a fibre optic system 7. Contamination in the water, for example oil droplets, scatters the laser light, which scattered light is detected by a scatter detector 8 via a window 9 and a fibre optic system 10. The window 9 is ar ranged at a relatively small angle a (Fig. 3).
typically 5 to 20 , to the laser incident beam.
The output of the light scatter detector 8 is fed via an amplifier 11 to a subtractor 1 2 which subtracts from it the amplifier output of the direct detector 5, which output is amplified in an amplifier 1 3. The output of the subtractor 1 2 is a continuous corrected contamination level reading which can be fed to a chart recorder 14 and/or a display 1 5 and which is applied to circuitry 16, described in more detail hereinafter with reference to Fig.
6, serving to trigger a water sampling device when a particular contaminant level is reached. As an alternative to using fibre optic connector systems, the laser and the detectors may be mounted directly on the cell.
The light-scattering cell 1 is shown in more detail in Figs. 2 and 3. The cell 1 comprises a central annular body 20 to which frusto-conical conduits 21 are secured via gaskets 22.
Light from the laser (not shown in Figs. 2 and 3) is fed to the window 3 via optical fibre system 4 and hence to direct window 6 and scatter window 9 and the respective detectors via optical fibre systems 7 and 10, respectively. An inwardly directed plate member 23 collimates the light beam entering the cell so as to reduce spurious reflections. Our Patent Specification No. 1556029 (G. D. Pitt-H. J.
Smith 19-4) and our co-pending Application No. 36060/77 (Serial No. ) ( G. D.
Pitt-S. I. N. Gregorig 22-1) relate to oil-inwater detectors employing such cells. More than one scatter detecor may be employed in the water monitor of the present invention, as is described in the prior art.
One example of the laser and drive circuit (optical transmitter) block 2 of Fig. 1 is shown in Fig. 4. The circuit has laser automatic gain control (AGC) comprising the upper half of the circuit of Fig. 4, a detector 24 being employed within the transmitter block to provide output control. The pulse width and repetition rate of laser L1 is defined by monostables M1 and M2, one output of M2 being fed back to Ml. 4 . The other output of M2 is fed via an emi-tter follower transistor TR1 and current amplifier transistors TR2 and TR3 to power output stage comprising transistors TR4 and TR5.The circuit further includes resistors R1 and R20 and capacitors C1 to C11. The laser L1 may be a type LB1-02 Gallium Aluminium Arsenide solid state laser available from ITT Components Group (Paignton). The laser is pulsed at 22kHz for 1,us. The output control was included to keep the light output to within + 1.5% over a temperature range of 50"C.
An example of optical receiver circuit is shown in Fig. 5 and comprises scatter detector 8 with associated amplifying circuitry including five integrated circuits D1, D2, D3, D4 and D5, and direct detector 5 with associated amplifying circuitry including four integrated circuits D6, D7, D8 and D9 The circuit further includes resistors R21 to R40 and capacitors C12 to C25. Circuitry IC1.
IC2, D1, D2, D3, D4, D6, D7 and D8 comprise integral circuit operational amplifiers type 3140, whereas IC3, D5 and D9 comprise integrated circuit operational amplifiers type 741. The detectors 5, 8 and 24 may comprise Hewlett Packard's diodes HP5082-4203 which have high speed response.
In use of the monitor comprising the cell 1, and its associated laser drive and direct and scatter detector and amplification circuitry shown schematically in Fig. 1, the call is arranged such that boiler feed water for an electricity generating set is passed therethrough, typically the cell is arranged to sample the turbine chamber condensate but other sampling positions may be employed. In dependence of the number of scatter detectors employed and their angular positions relative to the direct detector, different contaminants, generally oil and/or rust, can be monitored as described in the specifications referred to above, for example.
In the case of electricity generating sets very low oil contamination levels can cause problems as mentioned above and levels or less than 0.5 ppm of oil in water must be detectable. Indeed a level of 0.5 ppm is generally regarded as an acceptance maximum. At these very low contamination levels it is advisable to also carry out a sample chemical analysis. Conventionally, sample chemical analysis is carried out on samples taken at intervals, however it is possible with such methods to miss contamination in the system (Fig. 6a) unless very concentrated sampling procedures are employed which are both costly and time consuming.
It is thus proposed to employ a scatter cell to continuously monitor the contamination level and upon detection of the onset of contamination at a predetermined level (an alarm level) to cause operation of a sample taking device (Fig. 6b), whereby the contaminant level can be checked by chemical analysis. Such chemical analysis also provides assistance in calibrating the scatter cell monitor.
Generally the monitor should be such as to have a low response to rust relative to its response to oil, the scatter detector angle being chosen accordingly. Background solids levels up to the order of 40 ppb (largely rust) are generally to be expected and acceptable, however rust at relatively high levels 1 ppm is not acceptable in water to be recirculated and such a contamination level must be detectable with the monitor used for detecting oil or in another detecting system. For oil levels of 0.5 ppm scatter angles of 7 < and 15 have proved advantages.
As will be apparent from the above it is thus desirable to be able to monitor the water quality with an "on-line" instrument such that excessive water wastege can be avoided when using the shift-system, and to minimise the quantity of make-up water that has to be used. Using an on-line monitor with an automatic sampler operable at an alarm level means that less uncontaminated water will be wasted by virtue of the fast response of the monitor, resulting in large water and energy cost savings.
A suitable trigger circuit to operate a solenoid valve for sample collection when contamination above a preset alarm level is detected by the monitor is shown in Fig. 7. The circuit comprises a comparator (IC4 and IC5) to trigger a bistable, comprising one half of IC6, and also includes capacitors C26 to C31 and resistors R41 to R50. When the bistable is triggered a monostable, comprising the other half of IC6, is set for a predetermined time. A relay RL1 then operates a solenoid valve (not shown) connected to terminals A and B so that a sample is automatically taken from the main water flowstream for the predetermined time. For example a one litre sample of contaminated water may be taken in a time of 60 seconds. Once a sample has been taken no further sample can be taken until a reset button SW2 has been operated. This serves also to extinguish D10 which is an LED indicator that is illuminated when a sample is being taken. Switch SW1 comprises four presettable switches (0 to 1) arranged so that a binary coded number defines the quantity of contaminant triggering the sample taken, and thus permits different alarm levels to be set.

Claims (11)

CLAIMS:
1. A water contamination monitor comprising a cell through which the water is allowed to flow, a light source coupled t'o one side of the cell, one or more detectors arranged at an angle to the light beam to detect light scattered from contamination in the water, means to provide an electrical output related to the contaminant level from the detector output or outputs, and trigger circuitry arranged to provide an actuating signal for operating water sample valve means, in use of the monitor, for a predetermind time upon detection of predetermined contamination levels whereby to obtain a sample of the water having contamination above the predetermined level.
2. A water contamination monitor as claimed in claim 1, further comprising a detector arranged on the opposite side of the cell and aligned with the light beam, and wherein the outputs of the scattered light detector or detectors is modified by the output of the aligned detector.
3. A water contamination monitor as claimed in any one of the preceding claims wherein the laser is driven by a drive circuit and wherein a further detector is arranged on the one side of the cell for use in regulating the laser output.
4. A water contamination monitor as claimed in any one of the preceding claims wherein the laser and the detector or detectors are coupled to the cell via respective fibre optic systems.
5. A water contamination monitor as claimed in any one of the preceding claims wherein the laser is of the gallium aluminium arsenide or gallium aluminium phosphide type.
6. A water contamination monitor as claimed in any one of the preceding claims wherein the trigger circuitry includes switch means whereby different predetermined contamination levels may be selected.
7. A water contamination monitor as claimed in any one of the preceding claims and primarily for detecting oil contamination in the boiler feed water of electricity generating sets, wherein the scattered light detectors or detectors are arranged at angles between 5" and 20 to the laser beam.
8. A water contamination monitor as claimed in any one of the preceding claims in combination with a solenoid valve comprising the sample valve means, and wherein the trigger circuitry includes a relay which is activated for the predetermined time upon detection of predetermined contamination levels and serves to correspondingly actuate the solenoid valve.
9. A water contamination monitor substantially as herein described with reference to and as illustrated in Figs. 1, 2, 3, 4, 5, 6b and 7 of the accompanying drawings.
1 0. A method of monitoring the quality of boiler feed water for electricity generating sets comprising the steps of passing the water in a conduit, passing a light beam through the water in the conduit, detecting with respective detectors the light beam both after direct passage through the water and after scattering thereof by contamination in the water, obtaining a signal related to the contamination level from the detector outputs and applying the signal to a circuit arranged to trigger a water sampling value when a predetermined contamination level is exceeded, whereby to obtain a sample of the contaminated water for chemical analysis.
11. A method of monitoring the quality of water substantially as herein described with reference to Figs. 1, 2, 3, 4, 5, 6b and 7 of the accompanying drawings.
GB08126175A 1981-08-27 1981-08-27 Boiler feed contamination monitor Expired GB2105028B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB08126175A GB2105028B (en) 1981-08-27 1981-08-27 Boiler feed contamination monitor
ES1982266978U ES266978Y (en) 1981-08-27 1982-08-23 "A TEAM FOR THE CONTROL OF WATER POLLUTION".

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08126175A GB2105028B (en) 1981-08-27 1981-08-27 Boiler feed contamination monitor

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GB2105028A true GB2105028A (en) 1983-03-16
GB2105028B GB2105028B (en) 1985-04-03

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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0144928A2 (en) * 1983-12-08 1985-06-19 Hoechst Aktiengesellschaft Photometric head for small sample volumes
GB2150688A (en) * 1983-12-13 1985-07-03 Kollmorgen Tech Corp Photoelectric monitoring of emulsions
GB2157428A (en) * 1984-04-11 1985-10-23 Wehr Corp Fluid particle sensor
WO1987003091A1 (en) * 1985-11-19 1987-05-21 Consilium Marine Ab A method and apparatus for detecting the concentration of contaminants in a liquid
GB2203542A (en) * 1987-04-14 1988-10-19 Secr Defence Measuring particle size distribution
GB2251682A (en) * 1990-12-03 1992-07-15 Great Lakes Instruments Inc Turbidimeter
GB2256043A (en) * 1991-03-19 1992-11-25 Welsh Water Enterprises Ltd Organic pollutant monitor
GB2264882A (en) * 1992-03-10 1993-09-15 Achenbach Buschhuetten Gmbh A method and device for filtering liquids, especially rolling oil
US5420432A (en) * 1991-03-19 1995-05-30 Welsh Water Enterprises Limited Organic pollutant monitor
US5682231A (en) * 1995-07-06 1997-10-28 Holsen; John R. Device and method for determining contamination of a light permeable material utilizing the values of detected light below the saturation intensity of a sensor
DE102004047417B4 (en) * 2003-09-29 2007-01-04 Gebauer, Gerd, Dr. Macromolecular and aerosol diagnostics in gaseous and liquid environments
DE102006030734A1 (en) * 2006-06-30 2008-01-03 Gebauer, Gerd, Dr. Measuring arrangement for determination of thickness of size distribution, dielectric absorbing and optical material properties of scattering bodies, has process chamber with electromagnetic waves and matter waves
CN100427922C (en) * 2005-07-22 2008-10-22 公安部沈阳消防研究所 Smoke concentration detector
EP2541233A1 (en) * 2010-02-25 2013-01-02 Hitachi High-Technologies Corporation Automatic analysis device

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0144928A3 (en) * 1983-12-08 1986-01-08 Hoechst Aktiengesellschaft Photometric head for small sample volumes
EP0144928A2 (en) * 1983-12-08 1985-06-19 Hoechst Aktiengesellschaft Photometric head for small sample volumes
GB2150688A (en) * 1983-12-13 1985-07-03 Kollmorgen Tech Corp Photoelectric monitoring of emulsions
GB2157428A (en) * 1984-04-11 1985-10-23 Wehr Corp Fluid particle sensor
WO1987003091A1 (en) * 1985-11-19 1987-05-21 Consilium Marine Ab A method and apparatus for detecting the concentration of contaminants in a liquid
GB2203542A (en) * 1987-04-14 1988-10-19 Secr Defence Measuring particle size distribution
GB2251682B (en) * 1990-12-03 1994-12-14 Great Lakes Instruments Inc Turbidimeter signal processing circuit
GB2251682A (en) * 1990-12-03 1992-07-15 Great Lakes Instruments Inc Turbidimeter
GB2256043B (en) * 1991-03-19 1995-01-04 Welsh Water Enterprises Ltd Organic pollutant monitor
GB2256043A (en) * 1991-03-19 1992-11-25 Welsh Water Enterprises Ltd Organic pollutant monitor
US5420432A (en) * 1991-03-19 1995-05-30 Welsh Water Enterprises Limited Organic pollutant monitor
GB2264882A (en) * 1992-03-10 1993-09-15 Achenbach Buschhuetten Gmbh A method and device for filtering liquids, especially rolling oil
GB2264882B (en) * 1992-03-10 1996-01-17 Achenbach Buschhuetten Gmbh A device for filtering liquids, especially rolling oil
US5682231A (en) * 1995-07-06 1997-10-28 Holsen; John R. Device and method for determining contamination of a light permeable material utilizing the values of detected light below the saturation intensity of a sensor
DE102004047417B4 (en) * 2003-09-29 2007-01-04 Gebauer, Gerd, Dr. Macromolecular and aerosol diagnostics in gaseous and liquid environments
CN100427922C (en) * 2005-07-22 2008-10-22 公安部沈阳消防研究所 Smoke concentration detector
DE102006030734A1 (en) * 2006-06-30 2008-01-03 Gebauer, Gerd, Dr. Measuring arrangement for determination of thickness of size distribution, dielectric absorbing and optical material properties of scattering bodies, has process chamber with electromagnetic waves and matter waves
EP2541233A1 (en) * 2010-02-25 2013-01-02 Hitachi High-Technologies Corporation Automatic analysis device
EP2541233A4 (en) * 2010-02-25 2014-05-21 Hitachi High Tech Corp Automatic analysis device
US8858882B2 (en) 2010-02-25 2014-10-14 Hitachi High-Technologies Corporation Automatic analysis device

Also Published As

Publication number Publication date
ES266978Y (en) 1984-02-01
GB2105028B (en) 1985-04-03
ES266978U (en) 1983-07-16

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732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19980827