US2311661A - Condensation temperature measuring apparatus - Google Patents

Description

W. H. HOWE Feb. 23, 1943.

CONDENSATION TEMPERATURE MEASURING APPARATUS Filed Sept. 23, 1939 INVENTOR 1 M MFAEO h. /-/0 w. 61/12), EM 1' AA7WAQ ATTORNEYS Patented Feb. 23, 1943 CONDENSATION TEMPERATURE MEASURING APPARATUS Wilfred H. Howe, Sharon, Mass, assignor to The Foxboro Company, Foxboro, Mass., at corporation Massachusetts Application September 23, 1939, Serial No. 296,211

9 Claims.

This invention relates to indicating, recording, and controlling apparatus, and more in particular to apparatus for aiding in the measurement of the condensing temperature of a flowing stream of a condensable vapor or gas such, for example, as steam.

An object of this invention is to provide apparatus for obtaining a continuous sample of a stream of fiuid from which a record of its characteristics may be obtained. A further object is to provide apparatus of the above character for continuously removing non-condensable gas, such as air, from the vicinity of a thermometer bulb responsive to the condensing temperature of a condensable gas such as steam. A still further object is to provide apparatus of the above character which is sturdy in construction and dependable in operation for the continuous measurement of the condensing temperature of a flowing stream of a condensable gas containing non-condensable gases. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts, and in the several steps and relation and order of each of the same to one or more of the others, all as will be illustratively described herein, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing, in which are shown two of the various possible embodiments of this invention:

Figure 1 is a sectional view with a portion of the connecting pipe broken away; and

Figure 2 is a view similar to the lower portion of Figure 1 and showing a modified form of tube construction.

In steam heated apparatus, utilizing the condensation of steam, the useful temperature for measurement and control purposes is the condensing temperature of the steam; this temperature is termed the saturation temperature. This temperature is the temperature that saturated steam would have at the pressure of the steam in the apparatus. Often, however, the temperature of the steam flowing to the apparatus is higher than its saturation temperature.

Steam temperature at the point of supply exceeds the saturation temperature if the steam contains superheat; that is, if the steam is at a temperature above the condensing tempera ture corresponding to the steam pressure of the system.

To remove this excess heat and obtain the saturation temperature, it has been the practice to Withdraw steam from the steam line into a condensing chamber, the pressure in which is the same as that in the steam line. In the condensing chamber the excess heat carried by the steam is dissipated, and the steam is caused to condense. The temperature of this condensing steam is measured to obtain the temperature desired. However, if a non-condensable gas such as air is present in the steam, the air tends to accumulate in the condensing chamber to a much greater concentration than that existing in the original steam-air mixture in the steam line. When such an accumulation of air is present in the condensing chamber, the condensing temperature measured is lower than the actual condensing temperature of the steam-air mixture in the steam line, and the temperature reading is therefore incorrect. In the present embodiment, this problem is solved by causing a circulation within the condensing chamber sufiicient to withdraw air from the condensing chamber to keep the air ,in the steam-air mixture therein from concentrating to a point over that existing in the steam line where the desired temperature reading will not be obtained. Preferably this circulation is adjustable and does not induce sufiicient flow to interfere with the dissipation of the heat of superheat and the normal condensation of the steam upon the thermometer bulb.

Illustratively, in Figure 1 of the drawing steam flows from left to right in a pipe 2. A condensing chamber is attached to the pipe 2 through a T-coupling joint 4 into which is threaded connecting pipe 6 at right angles to pipe 2. Pipe 6 is connected at its upper end through an eccentric coupling 8 to a larger pipe I 0, the joints being welded. The upper end of pipe l0, covered by a T-cap l2, forms a thermometer well, indicated at l9. Extending downwardly into this well is a thermometer. bulb l8.

From the top of thermometer bulb I8 a tube 22 extends, which tube may be connected with a suitable recorder or indicator not shown, The thermometer bulb is supported by a ridge 24 at its upper end clamped between the adjacent beveled surfaces of a pair of nested screw sleeves l6 and 20; screw sleeve 16 is threaded. into T-cap l 2, and screw sleeve 20 in turn is threaded into screw sleeve 16. At the left, T-cap l2 may be connected through a pipe M to a pressure gauge (not shown).

The upper end of the tube is open to the interior of T-cap i2, and the lower end extends into the path of the flowing steam in pipe 2. The lower' end of the tube is cut away,-as indicated at 28, at an angle of 60140 provide an opening which faces downstream of the flowing steam.

During operation the interior of the condensing chamber is, of course, exposed to the same pressure that exists in the steam line 2, and the interior walls of the condensing chamber are in contact with the same steam that exists in the pipe 2. The condensing chamber, however, is not insulated from heat flow and so dissipates some of the heat of the steam in the condensing chamber, thereby not only removingthe superheat from the steam but also causing condensation of some of the steam in the chamber. This condensation, of course, causes fresh steam to enter from the pipe 2, the condensate flowing down the walls of the condensing chamber back into pipe 2.

In addition to this circulation caused by the condensing oi the steam in the condensing chamber, the steam flowing past the end of the tube 28 reduces the pressure in the lower end of the tube below that pressure existing at the top of the condensing chamber sufficiently to cause air and steam to flow down through the tube to maintain a steam-air mixture in the vicinity of the bulb l8 substantially equal to' that existing in the main steam line..

As pointed out above, as the steam flows upwardly toward bulb I8, the superheat is dissipated through the walls to the atmosphere, and steam condenses in the vicinity of the bulb. AE- cordingiy, the flow induced by the tube should not be great enough to interfere with the compiete removal of this superheat and the steam condensation. To this end, the angle of the tube with respect to the steam flow in the pipe 2 may be adjusted by rotating the pipe 6 in the T-coupling 4 to adjust the eflfective pressure drop set by the. tube between the pressure at its top and the pressure in the steam line 2. Such an adiustment is desirable to meet different conditions under which the apparatus may be used. Such difierent conditions may be, for example, different steam velocities in the steam line 2.

In obtaining this adjustment, as shown in Figure 2, a modified form of tip on the tube 26 may be used. Thus, a disc 38 is welded to the upstream side of the tip 28 to increase the effectiveness of the tube when the velocity of the steam in the steam line 2 is low.

As many possible embodiments may be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, allwithout departing from the scope of the invention, it is to be undcrstood that all matter hereinabove set forth, or shown in the accompanying drawing, is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In apparatus for measuring the condensing temperature of a stream of condensable gas flowing through a pipe and containing noncondensable gases, the combination with said pipe of a dead-end condensing chamber opening into and extending from said pipe, said condensing chamber being provided to remove superheat from the condensable gas entering said condensing chamber, a temperature responsive bulb located in the dead end 01 said condensing chamber and responsive to the condensing temperature of the condensable gas condensing thereon, meanaproviding a passageway opening into said dead end and into said stream of gas, the opening of said passageway into said stream of gas being so located with respect to the direction of flow of said stream of gas as to cause a continuous flow of gas in 'said passageway.

2. In apparatus for measuring the condensing temperature or a condensable gas flowing through a pipe, the combination of, a condensation chamber connected to receive the condensable gas from the pipe and adapted to remove heat from the condensable gas to thereby cause condensation within said condensation chamber, a temperature responsive device positioned within said condensation chamber, and a tube extending from said condensation chamber to said pipe, the end of said tube at said pipe being so located with respect to the direction of flow of gas in said pipe as to cause a flow of gas through said tube to cause desired gas circulation in the vicinity of said temperature measuring device.

- 3. In apparatus of the class described, the combination of, a pipe carrying a stream of fluid material such as steam, a condensing tube extending substantially at right angles to said pipe and connected at one end to said pipe, means for closing the other end of said condensing tube to form a condensing chamber, and a conduit having one end located in said condensing chamber and the other end extending into the stream of fluid, the extended end of said conduit being provided with an opening so located with respect to the direction of flow of fluid in said stream as to cause said conduit to deliver fluid from said condensing tube to the stream of fluid.

4. In apparatus for measuring the condensing temperature of a superheated flowing condensable gas such as steam containing non-condensable gases such as air, in combination, a dead-end condensing chamber connected directly to a line through which the gas mixture is flowing for removing superheat from and condensing a portion of the gas mixture entering said chamber, a thermometer bulb in said chamber for measuring the condensing temperature of the condensable gas. a tube in said condensing chamber extending from its dead end into the stream 01 flowing gas mixture for continuously removing from the chamber non-condensable gas entering with the condensed condensable gas, and means to adjust said tube in said stream to regulate circulation of the gas mix ture through the condensing chamber induced by the tube.

5. In apparatus of the class which is used for measuring the condensation temperature of flowing steam in which a condensing chamber is connected directly to the steam line and as the steam flows into the condensing chamber it loses any superheat which it has and a portion of the steam condenses, and wherein the temperature of the condensing steam is measured. the combination with said condensing chamber of a tube which extends from said condensing chamber to the stream of flowing steam, the end of said tube which is in contact with the stream of flowing steam being so located with respect to the direction of flow of steam as to cause the withdrawal of non-condensable gases from the vicinity where the temperature is being measured, and means for changing the location oi the end of said tube to vary the rate of withdrawal of said non-condensable gases.

6. In apparatus of the class which is used for measuring the condensation temperature of flowing steam in which a condensing chamber is connected directly to the steam line and as the steam flows into the condensing chamber it loses any superheat which it has and a portion of the steam condenses, and wherein the temperature of the condensing steam is measured, the combination with said condensing chamber of a tube which extends from said condensing chamber to the extreme of flowingv steam to withdraw gases from the vicinity where the temperature is being measured, the end of said tube which extends into the stream being cut at an angle to provide an opening lacing downstream of the direction of flow.

7. In apparatus of the class which is used for measuring the condensation temperature of flowing steam in which a condensing chamber is connected directly to the steam line and as the steam flows into the condensing chamber is loses any superheat which it has and a portion of the steam condenses, and wherein the temperature of the condensing steam is measured, the combination with said condensing chamber of a tube which extends from said condensing chamber to the stream of flowing steam to withdraw gases from the vicinity where the temperature is being measured, the end of said tube which extends into the stream being provided with a disc positioned on the upstream side of the tube with respect to the fiow of the steam to reduce the pressure in the vicinity of the end of the tube below the static pressure of the steam.

8. In apparatus of the class described, the combination of, a pipe carrying a stream of condensable vapor such as steam and contaminated by vapor non-condensable at the condensing temperature of the main portion of the vapor, a condensing tube connected at one end to said pipe, means closing the other end of said condensing tube to form a condensing chamber, said condensing chamber being adapted to condense the vapor therein and to return the condensate to said stream, and a tube connecting said condensing chamber to the stream of vapor and having one end so connected into the stream of vapor that the effective pressure at such end is lower than the effective pressure at the other end thereof, whereby a continuous flow of vapor is maintained from the condensing chamber through the tube into the stream of vapor to prevent collection of said non-condensable vapor in said condensing chamber.

9. In apparatus of the class described, the combination of, a pipe carrying a stream of condensable vapor such as steam and contaminated by vapor non-rondensable at the condensing temperature of the main portion of the vapor, a heat dispensing condensing tube connected at one end to said pipe and closed at the other end, said condensing tube thereby forming a condensing chamber to condense therein vapor entering said condensing chamber from said pipe, and a tube having one end terminating in said condensing tube and having its other end terminating in said stream of vapor in such a manner as to maintain a pressure difference between the ends or the tube and a resulting continuous flow through said tube, whereby the accumulation of non-condensable vapor is prevented in said condensing chamber.

WILFRED H. HOWE.

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