US 2150015 A
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March 7, 1939. R wrr 2,150,015
SALINITY INDICATOR SYSTEM Filed April 25. 1935 INVENTOR Egg/hand l .lilifiam SAT'i'ORN Y.
Patented Mar. 7, 1939 UNITED STATES PATENT OFFICE SALINITY INDICATOR SYSTEM:
Application April 23, 1935, Serial No. 17,807
This invention relates, generally, to means for detecting and indicating harmful impurities in boiler or evaporator water and the invention has reference, more particularly, to a novel salinity indicator system for disclosing the saline content of boiler or other water in which the presence of impurities is undesirable.
Boiler and evaporator water should be kept as clean and pure as possible in order to obtain efllcient boiler operation and to prevent injury to boilers and to operating equipment, such as turbines and engines. In some parts of the country and especially on steam vessels, the water used in boilers either contains or tends to become contaminated with injurious salts, such as magnesium chloride and calcium sulphate, that precipitate out as the boiler water is heated, causing the scaling of heating surfaces and resulting in the overheating and failure of such surfaces, while other salt impurities tend to produce priming, thereby resulting in injury or destruction of turbines, engines, etc. On steam vessels, sea water is generally used in condensers, with the result that any leakage of condenser tubes causes contamination of the boiler feed water.
The principal object of the present invention is to provide a novel salinity indicator system that serves to visually indicate the saline content of boiler water as well as further indicating immediately any change therein, so that steps can be promptly taken, when necessary, to make the required repairs or to otherwise correct for such salinity.
Another object of the present invention lies in the provision of a novel salinity indicator system having parts so arranged as to enable the user thereof to know at what point in the boiler water circulating system a leak or influx of salt-containing water occurs.
A third object of the present invention lies in the provision of a novel salinity indicator system of the above character that utilizes variations in the electrical conductivity of water, corresponding to changes in the percentage of electrolytic impurities, to determine the saline content of the water, the said system employing one or more pairs of electrodes immersed in the boiler water, there being applied a voltage across the electrodes of any selected pair, which voltage produces a current flow in the event that the water has a saline content, the said system having means for utilizing such current flow to de-- termine the percentage of salt present.
Still another object of the present invention is to provide a novel salinity indicator system of the above character that is so constructed and arranged as to give a substantially true indication of the salt content of the boiler water regardless of variations in the water temperature and of the frequency and/or voltage of the A. C. 5 utilized by the system.
Other objects and advantages will become apparent from the specification, taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated.
In the drawing,
Fig. 1 is a wiring diagram of the novel salinity indicator system of this invention, and
Fig. 2 is a view, in front elevation, of the indicating meter used in the system.
Referring now to the said drawing, leads I are connected to a suitable single phase A. C. supply, such as a 60 cycle, 115 volt source. Leads l have a double pole switch 2 included therein for controlling the supply of operating current to the 20 salinity indicator system. Leads 1 are shown connected to the ends of the primary winding of a step down transformer 3, illustrated as having two secondary windings 4 and 5. It is to be understood that the transformer 3 may be omit- 25 ted in instances where the supply voltage is suitable for direct connection to the system of this invention. Secondary winding 4 is shown as having a number of taps, to two of which are connected leads 8 serving to supply a pilot lamp 1, 30 or the pilot lamp may be connected across the primary of the transformer 3, if desired.
The terminals of secondary winding -5 are connected by leads 9 to terminals ill and H of an indicating means or meter l2. Connectedbetween posts i0 and II, as by means of leads l3 and I4, is a fixed field coil IS in series with a resistance IS. A holding coil l1 and a deflecting coil i8 cross one another substantially at right angles and are rigidly secured together to form the movable element'of the indicating meter or means [2, the said movable element carrying a pointer [9. These coils l1 and I 8 are mounted on a spindle for free rotation, there being no mechanical spring or other similar means for biasing the pointer iii to zero position on scale 22 (see Fig. 2).
Each of the windings l1 and i 8 has one of its ends connected to a common point 20 and this point is connected by lead l4 to terminal I I. The other end of the holding coil or winding I! is connected through a resistance 23 to lead l3, whereas the other end of the deflecting cofl or winding I8 is connected through a resistance 24 to a terminal 25 of meter l2. Terminal 2! is connected by a lead 23 through' a double pole switch 31 to a lead 23. Another terminal 23 of meter I2 is connected within this meter to lead i3 and this terminal is also connected by an outside lead 33 through switch 21 to a lead 3|.
Any one of a plurality of conductivity cells 32 is adapted to be selectively connected across the leads 23 and 3i by means of double pole switches 33. Each of the conductivity cells 32 consists of a pair of spaced electrodes 34 that are electrically insulated from one another within base plug 33 and are respectively connected to the respective poles of one of the switches 33.- The cells 32 are located at selected points in the boiler water circulating system, such as in condensers, feed water mains, etc., theelectrodes 34 being immersed in the flowing water. Although ordinarily a plurality of these cells 32 would be employed, yet in some installations only one of these cells need be used.
A checking resistor 33 is adapted to be connected across leads 23 and 3i by a double pole switch 33 for the purpose of checking the reading of meter II, as will further appear. As indicated in Fig. 2, this meter I2 is graduated in an accepted arbitrary scale of grains of chlorine per gallon", i. e., per gallon of water. The common point 20 of meter coils I1 and I3 is connected to a terminal 33 of meter I2, which terminal is connected by-a lead 33 to the adjustable arm 40 of a temperature compensating rheostat 4i Rheostat 4| is connected by a lead 42 to meter terminal 25.
With the parts of the system as thusly connected, it will be noted that holding coil I1 is connected in series with resistance 23 across leads 3. With switch 21 closed and one of the switches 33 leading to any selected cell 32 closed. it will be noted that deflecting coil is is connected in series with resistance 24 and such selected cell 32 across leads 9. This circuit is by way of terminal H, lead l4, coil l3, resistance 24, terminal 25, leads 23 and 23 to the cell 32, and from thence through leads ll, 30, terminal 29 and lead i3 to terminal ill. The temperature compensating rheostat 4| is connected in parallel with defled-1:128 coil l3 and resistance 24 by leads 39 and m use, with switch 2 closed, A. c. is supplied to transformer 3 so that pilot light 1 is lighted, showing that the system is in operation. v With switches 21 and 33 open, the cells 32 are open circuited and no current flows in deflecting coil i8 or in the temperature compensating rheostat 4|. Field coil I I and holding coil ll, however, are both connected across leads 3 and hence carry current, so that the movable holding coil I! will turn so as to tend to make its axis coincide with or lie parallel to that of coil i5, thereby also turningcoil l3 and causing pointer 13 to overlie the zero position on scale 22, as shown in Fig; 2. If switch 21 is now closed and one of the switches 33 also closed, the pointer is will move over the scale 22. provided that the feed water into which the selected conductivity cell is immersed, contains salt and is hence electrically conducting. In such case, current flows through deflecting coil l3 and resistance 24 in parallel with current passing through the temperature compensating rheostat 4|; both of these currents combining and passing through the selected cell 32. Thus, flux produced in deflecting coil l8 tends to cause the axis of this coil to move into parallelism with that of field coil l3, whereby coil l3 opposes coil i1 and effects a deflection of pointer it towards the right in Fig. 2, the magnitude of such deflection being a measure of the saline ccntentof the water as indicated by the reading of scale 22.
As the temperature of the feed or evaporator water increases, the degree of ionization of its saline content increases so that the electrical resistance of the feed water correspondingly decreases. and this would ordinarily cause an increase in the current flow through deflecting coil i 3, thereby giving a higher and incorrect reading, although the saline content has not actually changed. However, by turning the compensating rheostat arm 43 so as to decrease the compensating rheostat resistance 4| as the feed water temperature rises, the excess current flows through rheostat 4| instead of through deflecting coil i3 so that meter l2 therefore continues to give the correct salinity reading regardless of the change in temperature.
On the other hand, should the temperature of the boiler feed water fall, causing a decrease in the conductivity of the feed water, it is necessary to turn arm 40 so as to increase the resistance of rheostat 4|, thereby maintaining a constant current in deflecting coil i3 and a constant reading of the salinity indicator meter I2 for a constant saline content of the feed or evaporator water. Am 43 of rheostat 4i is adapted to move over a scale 43 on which feed water temperatures are indicated, so that by positioning arm 43 on that reading of scale 43 corresponding to the feed or evaporator water temperature at any time, proper compensation for variation of feed or evaporator water temperature is obtained.
Thus, by setting rheostat arm 40 over that reading on scale 43 corresponding to the feed water temperature at any time and closing any selected switch 33, the saline content of the water surrounding the particular conductivity cell 32 connected to the closed switch 33 is immediately indicated visually by meter l2, thereby enabling the engineer in charge to know the present saline content of that part of the feed water system into which the particular cell 32 is immersed. Thus, an increasing salinity reading enables the engineer to know at once of a leak occurring in any part of the boiler water circulating system, and by knowing the locations of cells 32 he also knows just where the leak or influx of salt water occurs as, for example, in a condenser having a defective tube.
Inasmuch as the fleld coil I! as well as the holding coil l1 and deflecting coil i8 are all connected in series with resistances directly across the leads 9, and as the currents carried by these coils are small, they really operate as voltage coils and hence are similarly affected by changes in line voltage and frequency, with the result that for constant salinity conditions the current differential between the holding coil and the deflecting coil varies substantially uniformly with the current in the field coil, so that the reading of meter l2, determined by the diiferential flux of coils i1 and i8 and by the flux of field coil i3, is largely unaffected by changes in line voltage or frequency, which is highly desirable, especially on shipboard where the A. 0. line voltage and frequency are apt to'vary. Thus, the indicator readings of the novel salinity system of this invention are highly accurate at all times, variations in supply voltage and frequency being automatically corrected for, while variations in boiler feed water temperature are corrected for by use of rheostat 4|. It is not feasible to use a. D. C. supply in this system owing to the creation of large errors in readings resulting from the polarlzafi'on and rapid deterioration of the cell electrodes 34.
lhe accuracy of the system may be checked at any time by means of checking resistor 36. This resistor has a resistance corresponding to the resistance between the electrodes of a conductivity cell 32 immersed in water having a definite temperature and salt concentration, for example, F. and a salt concentration equivalent to one grain of chlorine per gallon, respectively. Thus, with the temperature compensating rheostat arm ii] set over the 100 reading of scale 43 and switch 63 leading to checking resistor 36 closed, the meter l2 should read approximately 1 grain.
In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention. extends to such use.
Having described my invention, what I claim and desire to secure by Letters Patent is:
1. In a salinity indicator system for determining the saline content of boiler water, an A. C.
supply, a plurality of difierently positioned pairs of spaced electrodes immersedin said boiler water, a. checking resistor, meter indicating means having a deflecting coil, switching means for selectively connecting one of said pairs of electrodes in series with said deflecting coil across said A. C. supply, a holding coil connected independently across said A. C. and fixed at right angles with respect to said deflecting coil, a field coil inductively related to said deflecting and holding coils and independently connected across said A. C. supply, an indicator carried by said deflecting coil, and a salinity scale over which said indicator moves, said deflecting and holding coils being relatively movable with respect to said field coil, whereby said indicator is caused to indicate on said scale the conductivity and hence the relative salinity of the boiler water, and substantially independently of voltage and frequency variations, said switching means being also adapted for connecting said checking resistor in series with said deflecting coil for checking the readings of said meter indicating means.
2. In a salinity indicator system for determining the saline content of boiler water, an- A. C. supply, a plurality of pairs of spaced electrodes immersed in said boiler Water, meter indicating means having a salinity scale, a deflecting coil, an indicator carried by said deflecting coil and movable over said scale, a holding coil fixed at right angles to said deflecting coil and connected across said A. C. supply for normally urging said indicator to the zero point of said scale, and a field coil connected across said A. C. supply independently of though inductively coupled to said deflecting and holding coils, switching means for selectively connecting any desired pair of electrodes in series with said deflecting coil across said A. C. supply, and an adjustable temperature compensating resistance connected ln'shunt with said deflecting coil, whereby variations in the temperature of the boiler water are compensated for so as not to appreciably influence the reading of said meter indicating means, the series nature of said coils rendering the indications of said meter substantially independent of variations in line voltage and frequency.
3. In a salinity measuring and indicating device, an A. '0. supply, a pair of spaced electrodes adapted to be immersed in the fluid the salinity of which is to be determined, a meter responsive to the current flow between said electrodes for showing the saline content comprising mutually interacting coils fixed at right angles to each other and together rotatably mounted in a common field, and constituting aholding and a deflecting coil, a variable resistance calibrated in terms of the temperature of the fluid being tested and manually adjustable to compensate for variations in said temperature and a plurality of resistances, said electrodes being connected across the A. C. supply in series with a shunt circuit containing in one leg said variable resistance and in the other leg said deflecting coil and of said other resistances, the holding coil being connected across said supply in series with another resistance, and a stationary field coil for supplying said field also connected across said supply in series with a third resistance.
RAYMOND 1.. wn'mm.