US2175526A - Apparatus for introducing an odorant fluid into a gas line - Google Patents

Description

Oct. 10, 1939. R. M. HUTCHISON El AL 2,175,526

APPARATUS FOR INTRODUCING AN ODORANT FLUID INTO A GAS LINE Filed April 7, 195a 2 Sheets-Sheet 1 Oct. 10, 1939. R. M. HUTCHISON ET AL 2,175,526

APPARATUS FOR INTRODUCING AN ODORANT FLUID INTO A GAS LINE Filed April '7, 1938 2 Sheets-Sheet 2 Patented Oct. 10, 1939 PATENT OFFICE AlPARATUS FOR INTRODUCING AN ODOR- ANT FLUID INTO A GAS LINE Robert M. Hutchison and Frank Y. "Hutchison, Houston, Tex.

Application April 7, 1938, Serial No. 200,800 1 Claim. (01. 261-121 This invention pertains to anapparatus and method for introducing a fluid, as for example an odorant, into a line in which another fluid, as

for example natural gas, is flowing.

I Previous attempts have been made to' devise methods and apparatus for introducing an odorant into gas which is used for domestic or industrial purposes in order that a leak which otherwise might be dangerous will be evidenced by 10 a disagreeable odor.

These prior attempts have not been successful for various reasons, as for example, their inability to handle the preferred types of odorants or by reason of the fact that the odorant is-introduced 1. at an uneven rate so as to result in a very strong odor at times and a scarcely noticeable odor at Y other times.

' An object of this invention is to provide a method and apparatus by which the preferred commercial types of odorants may be introduced into a pipe line at the desired rate and in an economical manner and whereby the odorant will be introduced at a rate which is substantially proportional to the rate of flow of the gas in the 28 line.

A further object of the invention is the provision of a method and apparatus which will require a minimum of attention on the part of; an operator and which will not, under any circumstances, .0 introduce a dangerously excessive amount of the odorant into the gas line.

Still another object of the invention is the provision of an apparatus having a storage tank'ior the odorant which can be refilled without interrupting odorization.

Other objects and advantages of the invention will be apparent. from the accompanying description. and'drawings which describe and illustrate a preferred form of the invention for the purpose 40 o! exempliflcation.

In the drawings: 4

Figure 1 is a tic elevation of the apparatus showing its attachment, to a pipe line;

a Figure 2 is also an elevation of the apparatus 46 taken at a right angle tothe view shown in Figurel;

figure 3 is a detailed view, partly in section, or a portion of the apparatus shown'in Figures 1and2,and 1' Figure 4 is a View, partly'in section, takenon thelineHoIFigure3.

The odorant which is used is a volatile liquid which will vaporize rapidly under ordinary at-- mospheric conditions of temperature and presi sure and having ingredientswhich contribute a strong odor to the vapor, as for example, sulfides and mereaptans. Most commercial odorizing liquids of this type consist principally of mixtures of hydrocarbons having a relatively wide boiling range, the various component hydrocarbons havodor. This particular product has a boiling range v of 90F. to 400 F. and in this respect, resembles gasoline. Because of its wide boiling range, it is very diflicult to handle this odorant in the ordinary by-pass method of odorization. The lighter fractions of the liquid evaporate first, and as the heavier fractions become preponderant, the rate of evaporation decreases.

Furthermore; in the ordinary by-pass method, the composition and charaet'eristicsof the vapor emanated constantly change, as will be apparent from the following considerations. Each compound in the mixture exerts a partial pressure equal to the moi-fraction times its true vapor pressure it in a pure state under the same conditions of temperature and outside pressure; and therefore, at any definite temperature, each of the components exerts its own partial pressure dependent entirely upon its own moi-fraction in the combination.

If an inert gas is passed through or over such a mixture of compounds, the rate of evaporation of each individual compound is determined by its vapor pressure (when in a pure state) times the mol-fraction. Certain components will, therefore, vaporize more rapidly than the others, thus bringing about the lowering of these mol-fractions. This results in a proportional lowering of inafter to be described, an odorant of this type stant. rate and wherein the composition of the vapor is substantially constant. The liquid odor-.

' successfully we refer to Pentalarm having a boiling range of 130 F. to 200 F. i

Referring more particularly to thedrawinga-i wherein like reference characters indicate like parts, the numeral l indicates an ordinary pipe line adapted to carry gas into which it is desired to introduce an odorant, the direction of flow therein being indicated by an arrow. Pipes 2 and 3, provided with valves 2' and 3', connect the enclosed odorizing chamber with the pipe line I, and a conventional restricting means 3, preferably consisting of a disc having an orifice of reduced diameter, is placed in the pipe line I between the pipes 2 and 3; The restricting means 4 creates a pressure differential on either side thereof and causes a portion of the gas-to flow from the pipe line i, through the pipe 2 into the enclosed odorizing chamber, and back to the pipe line -I through the pipe 3. The amount of gas flowing through the odorizer may be regulated by,an angle valve 4' provided in the pipe, 3. During its travel through the odorizing chamher this portion of the gas will become odorized, as will hereinafter be described, and after its return to the pipe line I it will mix with' the re mainder of the gas therein.

The odorizing apparatus consists, in part, of a storage compartment or reservoir for the liquid odorant and a compartment into which the liquid odorant may overflow in the event that it is introduced into the apparatus at too rapid a rate.

In the illustrative embodiment of theinventionof a cylindrical support 3, and the overflow compartment 1 is provided at its lower end with an outletpipe ll extending through an aperture in said support and equipped with a valve ll. 7

The storage compartment 6 is provided at its upper end with a supply pipe l2, equipped with a valve l3, and itis also provided at its upper end with a vent pipe ill having thereon a valve ii. A gauge glass 13' is preferably connected to the storage compartment 3 by pipes I1 and I3 in the usual manner in order that the amount of liquid in the storage tank can be readily ascertained.

The overflow compartment I is provided adjacent its'upper end with a relatively large aperture I3 (Figs. 3 and 4) and a cylindrical housing 23 is secured about the periphery of the aperture, as for example by welding,*projecting laterally outwardly from the overflow compartment. The housing 23 is provided at its outer end with a flange 2! to which a header 22 is securedby means of bolts and nuts 23, 23. A vessel 24, hereinafter referred to as the float compartment, is secured to the header 22 and amuse projects'inwardly therefrom within the housing 23-. As shown, the bottom of the float compartment 24 is curved to conform roughly with the curvature of the housing 23 and the side walls 25,-" are vertical. The header 22 forms one of the end walls of the float compartment, and the other end wall is shown at 26: An aperture 21 is preferably provided in one of the side walls 23 a short distance below its upper edge.

A relatively small compartment generally designated at 23, hereinafter referredito as the hubbling compartment, is secured to the end wall 26 of the float compartment 24 and lies within the upper'portion of the overflow compartment. The bubbling compartment may be cylindrical as shown in the drawings, one end being closed by the vertical wall 29 and the other-being partially closed by the end wall 26 of the float compartment 23, leaving an opening 33 through which gas may pass from the bubbling compartment to the interior of the housing 20.

Liquid odorant passes from the storage compartment 6 to'the float compartment 24 through a pipe 3|, the liquid in the float compartment being maintained at the desired level (substantiallythat shown in the drawings) in a manner hereinafter described. The liquid odorant, passing through the aperture 32 in the end wall 23, will partially flll the bubbling compartment 23, and, obviously, the level of the liquid in the bubbling compartment will be the same as the level of the liquid in the float compartment.

The pipe 2, which, as stated above, supplies gas to the odorizing chamber, enters the header 22 and there communicates with a horizontal conduit formed of two pipes joined at their ends by a conventional coupling 34. The conduit 33 extends inwardly to a point within the bubbling compartment 23, and at its inner end is provided with an elbow joint 35 which curves downwardly and supports a short vertical pipe 36. The lower end of the pipe 36 is threaded into a disc 31 and the disc is provided with a peripheral skirt 38 extending downwardly and threaded at its lower end. A perforated cap 39 is threaded to the lower end of the skirt, and, as indicated in the drawings, the cap 39 is positioned slightly below the normal level of the liquid within the bubbling compartment 23.

' sure differential of from two to three pounds.

will cause a portion of the gas on the upstream side to flow from the pipe line I through the pipe 2 and the conduit 33 and downwardly withinthe bubbling compartment 23 through the pipe 33', and thence into the liquid odorant in the bubbling compartment through the perforated cap 33. The gas will then pass upwardly through the liquid and out of the bubbling compartment through the opening 33 and into the upper portion of the overflow compartment 1 by way of the aperture IS. The gas then passes out of the odorizing chamber and back into the main pipe line through the pipe 3 which is connected to the upper portion of the overflow compartment 1.

As the gas passes from the perforated cap 33 and bubbles up through the liquid odorant contained in the bubbling compartment, the liquid odorant will evaporate and the vapor therefrom will mix with the gas. As the liquid evaporates, it is replaced by the flow of liquid from'the storage tank 6 into the-float compartment 23 and from the latter, through the aperture 32 into the bubbling compartment.

Although the gas may passinto the housing and contact the surface of the liquid in the float compartment 24 during its passage through theodorizlng apparatus, this will not occur until after the gas has been'substantially saturated with vapor in the bubbling compartment, and, therefore, there is very little evaporation of the liquid odorant in the float compartment.

At the start, there, are certain fractions of liquid odorant in the bubbling compartment which, due to large mol-fractions, or high vapor pressure, or both, evaporate more rapidly than the remainder of the associated components. This initial higher rate of vaporization results in the lowering of the moi-fractions of these components thus leading to a resultant lowering of their rate of vaporization and a proportional increase in the rates of vaporization of the other components by reason of the increase in the molfraction of the less volatile components.

Partly owing to the relatively small size of the bubbling compartment in which the vaporization takes place, it will be found that very soon after the apparatus hasbeen placed in operation, the relative quantities of the various components in the vapor will be equal to their relative quantities in the original liquid or in other words, that the composition of the vapor is the same as the composition of the original liquid. Furthermore, the rate of evaporation quickly becomes constant.

Aslong as the conditions of gas flow through the apparatus do notvary, the vapor phase balance is maintained, or in other words, the rate of evaporation of the liquid and the characteristics of the vapor remain constant. A change in the pressure or rate of flow of the gas will result in a temporary change in the rate of evaporation vapor phase balance wherein the rate of evaporaor in the proportions of the various components of the vapor but anew vapor phase balance will qu'ckly be obtained, and the input of liquid odorant will again exactly equal the output.

In order to quickly reach and maintain this tion and the composition of the vapor is constant, it is apparently necessary to use a relatively' small bubbling compartment and to contact the gas with the liquid only at the surface of the liquid, thus taking advantage of the fact that evaporation of a liquid in the presence of a gas is more rapid if the relative quantity of the liquid is small. The dimensions of the bubbling compartment, and the depth of the outlet ports below the liquid therein are only great enough to insure that the, gas will actually bubble through the liquid and not force the liquid out of the compartment when flowing at a maximum rate. The quantity of the liquid which is acted upon by the gas may be still further reduced by the provision of a plate 40, having a central aperture 48', transversing the bubbling compartment a short distance below the perforated plate 39.

Furthermore, it appears to be highly desirable, if not essential, to replenish the supply, in the bubbling compartment, at or near the surface of the liquid and the aperture 32 is located accordingly.

To prevent the accumulation of heavier fractions or liquid in the bubbling compartment, we have provided a pipe 4| which is connected at one end to the bottom of the bubbling compartment 2! and at the other end to the lower portion of erations will flow of! through the pipe 4| and i will flow back into the float compartment.

The liquid odorant in the float compartment 24 and bubbling compartment 28 is normally maintained at the desired level by employing what will be hereinafter referred to as the barometric feed principle. For this purpose a seal pipe 42 is provided comprising a pipe which extends from the top of the reservoir 5 to the header'22 where it connects with one end of a pipe 43, the other end of the pipe extending downwardly to a point below the level at which it is desired to maintain the liquid odorant. Communication between the interior of the apparatus and the outside atmosphere is shut off by closing,

In other word's, the downward pressureper' square inch on the liquid in the reservoir 6 will be equal to the downward pressure per square inch on the liquid in the float chamber 24 minus the weight of a one-inch vertical column of liquid extending from the level of the liquid in the float chamber to the level of the liquid in the reservoir 6. It follows therefore that if liquid is taken from the compartment 24, in the absence of changes in pressure, it will be replaced by additional liquid flowing from the reservoir 6 through the pipe 3| into the float chamber '24, and gas will bubble back into the space above the liquid in the reservoir. Hence, there will be no material variation in the level of the liquid in the absence of sudden changes in pressure.

However, if there should be a sudden drop in the pressure of the gas within the housing 20 or if there should be a sudden increase in the pressure of the gas acting on the liquid in the reservoir 6, the level of the liquid in the compartment 24 will rise very rapidly. To safeguard against this eventuality, we have provided a .valve 44 actuated by a float 45 within the float compartment 24. The valve I4 and the height of the float 45 are so adjusted that the valve is normally open, but if a sudden and rapid flow of liquid into the float compartment 24 should occur, the valve II will close and prevent the flow of further liquid from the reservoir 8.

In the event that the float valve should mu to function or in the event that the seal pipe 42, which is not controlled by the float valve, cona large amount of liquid, a sudden change in pressure may cause the liquid in the float compartment 2 to overflow through the aperture the storage compartment 8 may be ascertained v by opening the valves 4 and l! and permitting the fluid from the storage tank to enter the gauge glass Ii through the pipe-ll.

In order to discover whether any liquid is flowing at any particular time from thesstorage compartment 6 to the float chamber 24, flow may be established directly from the gauge glass through a pipe 43, controlled by a valve 4! into the pipe 3|. tween the storage-compartment 6 and the junction of the pipe 48, and if this valve is closed, and there is any flow through the pipe 3i, there will be a violent fluctuationof the level of the liquid in the gauge glass.

In order to replenish thesupply of liquid in the storage compartment 6, the valves 49 and 50 are closed to temporarily stop the flow of liquid from the storage tank into the float chamber,-

and a valve 5|, which is provided in the seal pipe 42, is closed to maintain the level of fluid in the seal pipe. The valves I3 and I! in the supply pipe and vent pipe, respectively, are then opened, and liquid may be introduced through the supply pipe I 2. The valves l3 and I l are then closed before the valves 49, 5B, and 5| are opened.

Since in normal operation the pressure on the surface of the liquid in reservoir 6 usually differs from atmospheric pressure, the normally existing hydrostatic equilibrium will be broken by opening either of the valves [3 or I 5, but, after they are closed, equilibrium will quickly be restored,

. and by reason of the provision of the three different controls, mentioned above, (1) the barometric teed, (2), the float valve, and (3) the provision for overflow, this temporary disturbance does not interrupt and, in fact, has no substantial effect on the odorization of the gas.

The rate-of evaporation of a given liquid odorant in a given apparatus of this type will depend upon the rate of flow of the gas through the bubbling compartment, and this, of course, depends upon the rate of flow of the gas in the main pipe I.

Although the rate of evaporation is, to a slight extent, inversely proportional to the pressure of of the gas in the pipe line, a vapor phase balance can quickly be obtained for any pressure condition. It will be noted that the rate of flow of the gas through the main and the odorizer A valve 50 is provided in the pipe 3| be-- may difl'er widely under the same conditions of' pressure. Consequently, the advantage of providing an odorizer which will supply the odorant in quantities proportional to the rate of flow of the gas will be apparent.

The apparatus does not require the attention of an operator except for an occasional inspection of the gauge glass and replenishment of fluid in the storage compartment. When the apparatus is decommissioned the fluid therein may be withdrawn through a valve 52 provided for this purpose in the float compartment.

It is obvious that many changes might be made in the apparatus without departing from the scope of the invention, and such modifications as will be obvious to those skilled in the art are to be regarded as within the purview of the invention.

We claim:

In apparatus for introducing an odorous vapor into a confined stream of inflammable gas, an elongated upright chamber having a partition intermediate its ends which divides the chamber into an upper compartment and a lower compartment, the upper compartment being adapted to hold a supply of volatile liquid, the lower compartment having an aperture in one side thereof and adjacent the said partition, a housing secured to the lower compartment at the aperture and extending outwardly therefrom, a header removably secured to and closing the end of said housing; a vessel secured to and supported by the inner wall of the header and extending inwardly therefrom, a conduit for conducting the volatile liquid from the upper compartment to the vessel. means for controlling the liquid level in the vessel, a conduit for conducting gas into contact with the liquid in the vessel, a passageway providing communication between the upper part of said vessel and the lower compartment, and an outlet for the gas, the vessel and the outlet being located a substantial distance above the bottom of the lower compartment whereby the latter acts as a receptacle for any liquid which may overflow from the vessel.

ROBERT M. HUTCHISON.

F. Y. HUTCHISON.

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