US3498116A - Moisture determination apparatus - Google Patents

Description

March 3, 1970 SNELSQN 3,498,116

MOISTURE DETERMINATION l APPARATUS Filed OCt. 13, 1966 FIG. 2

. INVENTOR.

D.W. S N E LSON' ATTORNEYS United States Patent 3,498,116 MOISTURE DETERMINATION APPARATUS Dallas W. Snelson, Tulsa, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Oct. 13, 1966, Ser. No. 586,534 Int. Cl. G01n 5/02 US. CI. 7373 7 Claims ABSTRACT OF THE DISCLOSURE An apparatus for determining moisture content of liquid petroleum gas. The apparatus includes a flow distributor, a filter, and a flow control means which is adjustable to a calibrated setting.

This invention relates to the determination of the moisture content of fluids. In one aspect this invention relates to an apparatus for determining the moisture content of a fluid. In another aspect, this invention relates to an apparatus for determining the moisture content of a fluid, comprising adjustable snap acting means for changing from a flow restrictor in a flow passage to another position wherein the flow through the passage is unrestricted.

Knowledge of the mois ure content of various fluids often is an important consideration. 'For example, condensed moisture may interfere with the flow of gas in a pipeline and, under certain conditions of temperature and pressure, moisture may combine with a gaseous hydrocarbon to form gas hydrates. The solid product thus formed may collect in sufficient quantities to reduce the flow or even to plug completely the pipeline in which the flow is occurring. The specifications under which liquefied petroleum gases are sold often include moisture content. My invention is suitable for determining the moisture content of liquefied petroleum gas (LPG) hydrocarbons without resorting to laboratory analysis. A method suitable for determining the moisture content of fluids such as disclosed by Alquist, 3,196,667 (1965) can be employed. Since tests are conducted without resorting to laboratory analysis, problems have been encountered in alterations in the testing zone by friction wear upon the calibrating members and by mechanical rotation of one part of the member while the cooperating part remains stationary. Such variations in data as obtained by using field methods occur due to minor variations which are present when machined parts are produced to work in close tolerance.

According to my invention a moisture determination apparatus having a housing with a passage therethrough and an inlet and an outlet is connected to a fluid source, such as a liquefied petroluem gas line, by a connection nipple which is connected to the inlet end of the housing. Moisture determination apparatus is also provided with an adjustable flow control means which is operatively connected to the housing and adapted to enter into a second choke which is positioned downstream from a first choke, the two chokes serving to restrict the flow of fluid through the passage. The second choke restricts the flow through the passage more severely when the adjustable flow control means is positioned in an operating position. The adjustable flow control means is moved into two relative positions within the second choke. To change the relative positions one to the other, the choke means and the adjustable flow control means in one of the relative positions cooperates to form a very small flow passage and the second choke and the adjustable flow control member in the other of the relative positions cooperate to remove the flow control member from the path of flow of fluid through the second choke.

Further according to my invention a fluid distributor is 3,498,116 Patented Mar. 3, 1970 positioned within the passage adjacent the inlet within the housing to produce increased expansion of the fluid flowing through the moisture determination apparatus. The fluid distributor further provides a flow diversion of the fluid to provide equal distribution of flow across and through a filter which is also positioned within the passage downstream of the fluid distributor. The filter is maintained in position adjacent a first choke means by a resilient means abutting the fluid distributor and the filter to prevent fluid from bypassing the filter as it is forced through the passage.

Further according to my invention a locking means is carried by the stem of the flow control member. The locking means is contacted with a shoulder within the housing of the moisture tester apparatus to provide adjustable control for regulating the size of the annular passage formed by the second choke and one end of the stem.

Further according to my invention there is provided a moisture determination apparatus having a swivel ball joint incorporated within the flow control means thereby preventing circular movement of a snap acting cam actuator from altering the relative positions of the flow control member with respect to the second choke.

It is an object of the invention to provide an apparatus for determining the moisture content of fluids.

Another object of the invention is to provide an apparatus suitable for determining fluid moisture content under conditions of field operations which produce reproducible accurate data as to moisture content.

Another object of the invention is to provide an apparatus for determining moisture content having an adjustable flow control member so that the moisture determination apparatus can be adjusted for different fluids and different calibrations.

Other aspects, objects and advantages of the invention will be apparent to one skilled in the art from a study of the written description, the drawing and the claims.

In the drawing FIGURE 1 illustrates a combination of elements useful in determining the moisture content of a fluid.

FIGURE 2 is a vertical cross-section of a moisture determination apparatus according to the invention.

FIGURE 3 illustrates flow control member of the moisture determination apparatus of FIGURE 2.

Referring now to the drawings where like elements are designated by like numerals, and particularly to FIGURE 1, there is shown a source of liquefied petroleum gas (LPG) 10 in fluid communication through fluid conduit 13 with valve 11, pressure regulator 12 and moisture determination apparatus 20 respectively. Moisture determination apparatus 20 is provided with cam lever 58 which can be positioned to cause restriction of flow of LPG through moisture determination apparatus 20 in one posiging. This time is a function of the moisture content ofthe LPG flowing through the moisture determination apparatus. Liquefied gases containing known quantities of moisture are tested using moisture determination apparatus 20 to deermine time required for shutting off the restriction at various moisture concentrations, These results so obtained are then plotted to form a curve of freezing time versus moisture content. Upon determining the time required to shut off the flow of fluid through the.

moisture determination apparatus one can use the above curve of freezing time versus moisture content to determine the moisture content of the fluid being tested.

As shown in FIGURE 2, a moisture determination apparatus 20 is provided with an inlet 21, an outlet 22 and a flow passage 23 extending through housing 24 which comprises a plurality of sections, 28, 29, 32 and 34, subsequently described. Inlet 21 is provided with threads so that a connection nipple 26 having mating threads on one end can be attached to housing 24. Connection nipple 26 is provided with a connection nut 27 as shown and a passage in fluid communication with passage 23 of housing 24 thus enabling moisture determina tion apparatus 20 to be operatively connected to a fluid conduit carrying the fluid to be tested.

Housing 24 comprises a plug 28 which is operatively connected to filter housing 29 by mating threads 31 as shown. Filter housing 29 is operatively connected to control housing 32 by threaded connections 33. Control housing 32 is then connected to spring housing 34 by threaded connection 36. Spring housing 34 is provided with a coaxial bore 37 which is positioned furthermost removed from inlet 21 of moisture tester 20. When assembled, plug 28, filter housing 29, control housing 32, and spring housing 34 combine to form a continuous housing 24 for moisture determination apparatus 20.

The plug 28 has a distributor portion 38 disposed internally of the filter housing 29. Extending axially through the plug 28 is a bore 28a which forms part of the passage 23. The distributor portion 38 is provided with four circumferentially spaced orifices 35, three of which appear in FIGURE 2. The axes of the orifices 35 extend perpendicular to the axes of bore 28a so that the flow of fluids through plug 28 is diverted and distributed upon entering passage 23 defined by housing 29. Immediately downstream of the distributor portion 38 and disposed concentrically in passage 23 is a filter 39. Filter 39 is positioned within filter housing 29 and adjacent a choke 41 by means of a resilient element 42 which abuts fluid distributor 38 in filter 39. Resilient element 42 serves to maintain filter 39 against choke 41 at all times, thereby preventing the fluid passing through passage 23 from bypassing the filter 39 and thus contaminating downstream portions of moisture determination apparatus 20. Choke 41 is provided with four orifices 25 (two appearing in FIGURE 2) of fixed dimensions. The orifices 25 are radially spaced in the passage 23 thereby providing means for distributing the fluid immediately upstream of the flow control means which includes a choke nipple 43 and a stem 44 slidably mounted in the housing 24. Choke nipple 43 has formed therein an orifice 43a which cooperates with an end portion 49 of stem 44 to eifect throttling of flow therethrough. The choke nipple 43 is positioned within the control housing 32 and serves as a housing for body 40, an integral part of a stem 44. The choke nipple 43 and control housing 32 are maintained in assembled relation by pin 46. The choke nipple 43 is further provided with an opening 47 which is in fluid communication with outlet 22.

The stem 44 comprises the control body 40, a threaded portion 54 and a straight portion 48. Body 40 slidably fits internally ofthe choke nipple 43 and has end portion 49 in registry with the orifice 43a. End portion 49 is configurated to provide a radially outwardly taper in the direction of fluid flow. Orifice 43a is similarly tapered so that end portion 49 disposed therein defines an annular passage 51. O-ring 50 mounted on body 40 maintains a fluid seal for passage 23. Lock nuts 56 mounted on the threaded portion 54 of stem 44 provides the means for adjusting the flow area of annular passage '51. The lock nuts 56 are maintained in abutting relation to the end of choke nipple 43 by a compression spring 52 concentrically mounted on straight portion 48. Flanking collars 53 maintain the spring and stem 44 in the proper assembled relation. Thus ro ation of the lock. nuts 56 in one direction reduces the flow area in annular passage 51, andin the opposite direction enlarges it. This particular feature permits the flow control means to be adjusted precisely to the calibrated setting.

The spring 52 urges the stem 44 towards a first position wherein the tapered end 49 extends concentrically into the orifice 43a and therewith define the annular passage 51. The stem 44 is moved to a second position by means of a lever 58 disposed externally of the housing 24. The straight portion 48 extends through an aperture 37 formed in housing 24 presenting a projection 48a externally of the housing 24. The projection 48a is pivotally attached to a lever 58 by pin 59. Lever 58 comprises a handle 61, a recessed opening 62, and a cam surface 63. The lever 58 is disposed in a transverse attitude relative the stem 44 and is movable about pin 59 towards axial alignment with the stem 44. Cam surface 63 reacts with the housing 24 thereby causing the stem 44 to be moved to the right as viewed in FIGURE 2 to the second position. A flat portion of cam surface 63 maintains the assembly in the second position. In the second position, the flow area through orifice 43a is substantially greater than that provided with the assembly in the first position.

It has been found that in moving the lever 58 from the transverse to the axially aligned attitudes relative the stem 44, the reaction of the cam surface 63 on housing 24 creates lateral stresses on a rigid stem. Therefore, a pivotal connection in the form of a swivel ball joint 57 is provided. The ball joint 57 permits lateral movement of the straight portion 48 relative to the threaded portion 54 thereby eliminating the stresses.

In operation, moisture determination apparatus 20 is inserted in a flow line to be tested so that liquid enters flow determination apparatus 20 through inlet 21. As the fluid flows through inlet 21 and through flow passage 23 fluid distributor 38 serves to provide increased expansion of the fluid flowing through the flow smoother and thereby providing a flow diversion of the fluid to provide equal -di-stributi0n of the flow across filter 39. As the fluid passes through filter 39 it is restricted by choke 41 thereby causing an increased pressure and cooling eflect on the fluid flowing through choke 4.1. Flow control means comprising tapered end portion 49 of stem 44 and orifice 43a further restricts the flow thus increasing the pressure and upon passing therethrough the fluid is allowed to expand thereby causing a sudden cooling of the fluid before it passes through outlet 22. With the assembly in the second osition, the flow area of passage 51 is greatly increased resulting in substantially less expansion and consequent cooling. Where it is desired to make the desired moisture measurements cam lever 58 is positioned to advance stem 44 within spring housing 34 thereby causing the tapered end 49 of control body 40 to enter orifice 43a and form annular passage 51. This sudden closing off of the flow passage through orifice 43a reduces the flow through choke 43 a predetermined amount. Upon the fluid passing through annular passage 51 the fluid is subjected to a sudden expansion and supercooling eifect thus causing the moisture within the liquid to freeze and close off annular passage 51. After calibration curves have been run the time which it takes the moisture within the fluid passing through annular passage 51 to freeze and thereby cut off the flow of fluid through annular passage 51 and the size of annular passage 51 can be used to determine the amount of moisture present from curves drawn in the calibration of moisture tester apparatus 20. Annular passage 51 can be adjusted by adjusting lock nuts 56 on stem 48, thereby increasing the size of annular passage 51 by adjusting lock nuts 56 in such a manner as to partially withdraw the tapered end 49 of control body 40 from orifice 43a.

Also, in operation, maintenance of the control system is greatly simplified by means of the detachable units, in other words, the filter body, the control housing, and the spring housing. When necessary to inspect or adjust stem 44, spring housing 34 and control housing 32 can be separated thereby enabling the withdrawal of stem 44 without complete disassembly of the moisture determination apparatus 20. Further, since there is no friction contact between tapered end 49 of control body 40 and second orifice 43a, wear does not occur upon these elements thus changing the size of the elements because of operation. Further, swivel ball joint 57 of stem 44 prevents movement of cam lever 58 from influencing the position of tapered end 49 of control body 40 with relation to orifice 43a. Due to swivel ball joint 57 external pressure applied on cam lever 58 or the top portion of moisture determination apparatus 20 does not change the flow rate through orifice 43a. Swivel ball joint 57 allows the operator to rotate cam lever 58 within 360 without affecting the flow rate, thus reducing burdensome manufacturing tolerances.

Reasonable variations and modification are possible within the scope of the foregoing disclosure, the drawings and the appended claims to the invention, the essence of which is a moisture determination apparatus comprising adjustable flow passages for calibration, tapered replaceable sections in the flow control member and housing in a test zone, and a plurality of restricted flow passages to smooth flow into the test zone after liquid passes through a filter element, and means provided to prevent friction wear incorporated in the fiow control member and housmg.

That which is claimed is:

1. An apparatus for use in determining moisture content of liquid petroleum gas comprising:

(a) a housing having an inlet, an outlet and a passageway interconnecting said inlet and outlet;

(b) flow control means disposed in said housing for throttling the flow of gas through said passageway thereby causing expansion and cooling thereof comprising:

(1) an orifice,

(2) a stem slidably mounted in said housing and having an end portion in registry with said orifice, and

(3) means for moving said stem between a first and second position, said end portion in said first position and in cooperation with said orifice defining a first calibrated flow area, and said end portion in said second position and in combination with said orifice defining a second calibrated flow area, said second flow area being greater than said first flow area; and

(c) a flow restrictor of fixed dimension disposed in said passageway and upstream of said flow control means whereby gas flowing through said passageway is expanded through said flow restrictor and said flow control means.

2. The invention as recited in claim 1 wherein said end portion is configured to provide a continuous radially outwardly taper in the direction of fluid flow, said end position in said second position being removed from said orifice, said orifice having a tapered configuration conforming to that of said end portion, and said end portion n said first position being disposed in said orifice, said first fiow area defined thereby having a tapered annular configuration.

3. The invention as recited in claim 1 wherein said adjustment means includes locking means threadedly mounted on said stem and being rotatable in one direction to move said stem toward said first position and rotatable in the opposite direction to move said stem toward said second position.

4. The invention as recited in claim .1 wherein said stem extends through said housing presenting a portion externally thereof, and said means for moving said stem includes biasing means for urging said stern toward said first position and a lever mounted on said external portion of said stem and actuable to move said stem against the force of said biasing means to said second position.

5. The invention as recited in claim 4 wherein said lever is pivotally connected to said external portion of said stem and is normally disposed transverse said stern, and has a cam surface engageable with said housing, said lever being movable toward axial alignment with said stem about said :pivot connection, said cam surface reacting with said housing thereby moving said stem to said second position.

6. The invention as recited in claim 5 wherein said stern internally of said housing includes a pivot connection whereby lateral stresses created by said lever in moving toward axial alignment with said stem are eliminated.

7. The invention as recited in claim 6 wherein said pivot connection is a swivel ball joint.

References Cited UNITED STATES PATENTS 3,196,667 7/1965 Alquist et al. 73-61.1

RICHARD C. QUEISSER, Primary Examiner I. WHALEN, Assistant Examiner US. Cl. X.R. 7329

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