The present invention relates to spot fluid sampling systems. First disclosed is a “moveable end” (ME) fluid sampling system, which employs a method of collection wherein the initial cylinder volume of the collection vessel or sampling cylinder is zero. In this embodiment, a spot sample cylinder is inserted into the pressurized fluid source, said sample cylinder employing a piston or moveable end to configured to initially be situated in a position wherein the sample cavity has no volume so as to dispense with the necessity of purging same, the moveable end formed to reposition as the sample cavity is filled, thereby expanding the cavity upon sampling.
The present invention also relates to a new and unique cap/body (CB) sample cylinder system having a size and design to enable it to be inserted into a pressurized process with an insertion device. In the preferred embodiment of the CB sample system, the cap functions as a fill/empty valve. The cap and body of the cylinder are designed to eliminate the necessity of purging the sample pathway. The sample cylinder's internal cavity it may be evacuated by pulling a deep vacuum and/or filling with a diluent gas that cannot be detected by the analyzer which will analyze the sampled fluid.
The CB cap to body seal does not require the normally employed sealing materials such as elastomers or plastics. In the preferred embodiment, the cap and body are preferably constructed of metal, and when assembled are formed to provide a metal to metal seal to retain pressurized fluids in the internal cavity of the sample cylinder. A unique housing and method for evacuating the sample gas from the CB sample cylinder is also provided.
In many cases, the cost of installing an “on line” analyzer for a natural gas or other process stream cannot be justified. In such cases, a “spot” sample is taken periodically, or a composite sample is taken over a period of time. A “spot sample” generally consists of extracting a sample of the gas at a “spot”, or single point in time.
A composite sample is generally taken by a sampling apparatus (composite sampler) which extracts a small volume (bite) of gas sample periodically, which is collected in a sample cylinder. A typical composite sampler will control the sampling interval based on time or flow volume. Flow volume information, or electric pulse, is usually provided by an external flow computer. A typical composite collection period is 30 days. There are two basic types of sample cylinders utilized for spot and composite sampling. They are the constant volume and constant pressure types of sample cylinder. Constant pressure types of sample cylinders are of the floating piston or bladder (bag) type.
Gas Processors Association Standard Publication 2166 entitled “Obtaining natural Gas Samples for Analysis by Gas Chromatography” details several spot sampling methods in its 1986 revision and its draft. The main thrust of the GPA 2166 standard deals with methods for purging the sample cylinder, dealing with entrained liquid using the GPA or other type separator, and prevention of condensation of gas components.
American Petroleum Institute Manual of Petroleum Measurement Standards, Chapter 14, Section 1, revised in 2001, the contents of which are incorporated herein by reference, addresses spot sampling issues.
The hydrocarbon dew point temperature (HCDPT) and its impact on the sampling of natural gas is the main focus of the API 14.1 standard. This is evident in the opening paragraph “14.1 introduction”. Refer to 14.1.6, here the standard calls out issues which need to be addressed when sampling natural gas. Issues include ambient temperature condition and phase-change characteristics. In 14.1.6.6, it makes clear that no part of the spot sampling system should be allowed to fall below the HCDPT, otherwise biased analytical results and non-representative samples are likely to result. Maintaining the sample system at, or above, the HCDPT is recommended.
In 14.1.6.6.4 (Sample containers), it states that the cylinder temperature must be kept above the HCDPT. Note that the author is a member of the API 14.1 working group responsible for the writing standard. The reason for this recommendation is to insure that the cylinder temperature is “above” as opposed to “equal” to or above” the HCDPT due to the uncertainty of measuring the HCDPT. It is well known, from a thermodynamic standpoint, that maintaining a gas at or above the HCDPT will not yield condensation.
The entire API 14.1-2004 document is rich in thermodynamic and practical information. For example, in Appendix A, “The Phase Diagram” and A.1 phase changes in general. In referring to the API 14.1-2004 document, especially its Appendix A and to the paper “Accuracy of Natural Gas Sampling Techniques, and the Impact of Composition Measurement Errors on Flow Rate and Heating Value Determination”, K. A. Behring, Flomeko '98, the 9th Int Conf on Flow Measurement, Lund, Sweden (Jun. 15-17, 1998), one can conclude that condensation of portion of a gas phase and/or vaporization of a liquid wherein the resulting vapor becomes intermixed with the gas phase will likely (almost certainly) result in product composition changes in the gas phase.
It is well known and understood that even small changes in the composition of a natural gas sample can have a significant impact on its heating value (BTU content) and other important physical properties some of which are utilized for making flow rate calculations. The heating value and flow rate (volume) of the natural gas key factors in determining its monetary value.
In summary, the cost of adhering to the API 14.1 and GPA 2166 standards, in particular the cost and attention required to maintain all parts of the prior art sampling system and cylinders above the HCDPT, results in the very frequent improper sampling of natural gas. Again, even small changes made to the current and prior art sampling procedures often result in inaccurate, non-representative samples.
The problems are primarily due to the current art of having the sample conditioning system and the sample containment cylinders external to the vessel or pipeline. Spot and composite sample have traditionally been taken in that manner ever since spot samples were first taken. This requires the use of costly equipment, especially in cold climates and/or wet gas (high HCDPT) applications.
The present invention overcomes the expense and reliability problems associated with prior art spot sampling techniques in the above scenarios by inserting the sample cylinder of the present invention inside of the pressurized containment vessel or pipeline when taking a sample.
In the first embodiment of the present invention (
A “zero volume sample cavity” such as the M.E. sample cylinder (or any other zero volume sample cavity configuration) can eliminate the need for purging the cylinder. This is important as cylinder purging represents one of the largest and most frequent sources of analytical error in the sampling of natural gas.
To further enhance the sampling system of the present invention, a second embodiment of the invention (ex.
An alternative to fully evacuating the CB sample cylinder is to purge said cylinder before sample collection with a diluent gas, such as helium, which cannot be detected by the sample fluid analyzer.
Still another technique of the present invention is to first purge the CB sample cylinder with a diluent gas which cannot be detected by the sample fluid analyzer, followed by reducing the diluent gas pressure in the cylinder to essentially zero by evacuation.
In each of the above cases, the cap is sealed to the CB sample cylinder body after purging and/or evacuation of the internal cylinders cavity, preferably while utilizing a custom housing for that purpose, also disclosed in the present application.
Insertion of either sample cylinder directly into the process source of fluid for the sample eliminates the requirement for purging any tubing/piping interconnection(s) between the process and sample cylinder, when traditional external filling method is utilized.
Purging of the interconnecting tubing/piping and sample cylinder is the greatest source of error in spot sampling. The present invention eliminates this source of error. The present invention can also be filled external to the source fluid. Due to its design, the sample path from the source of fluid to the cylinder is minimized, thereby limiting the exposure to ambient temperature during the sampling process.
For a further understanding of the nature and objects of the present invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawings, in which like parts are given like reference numerals, and wherein:
The first embodiment of the sample cylinder of the present invention is shown in
As shown, moveable end 35 slidingly engages the inner wall of sample cavity 29 to form a sliding barrier which is fluid sealed or fluid impermeable via seal 36, which can comprise, for example, an o-ring. In the exemplary embodiment, valve chamber 42 has an inner wall forming a threaded connection for threadingly engaging threaded plug 30′ having first 70 and second 70′ ends, the first end 70 having hex recess 30 formed therein, the second end 70′ having valve stem/poppet 31 engaged thereto.
As shown in
In
This moveable end (ME) sample cylinder may be inserted into a pressurized fluid source for obtaining a sample by a number of means. One such means utilizes a packing gland or dynamic pressure seal type of insertion device, similar to that used for insertion of probes, sensors, corrosion coupons etc. A second type of insertion means to insert the ME sample cylinder into a pressurized process utilizes a pressure balance approach similar to that described in U.S. Pat. No. 7,472,615 by Mayeaux entitled “Portable Insertable Probe assembly”, the contents of which are incorporated herein by reference.
Referring to
Once the sample cavity has reached the first end 37, and is thereby filled, the threaded plug 30 may be turned 72′ a second direction via hex recess 30 to close 73′ valve 40, capturing and retaining the fluid in the sample cavity, thereby providing a filled sample cylinder, which may be then removed 71′ from the pressurized fluid source for analysis or other purpose.
With the ME sample cylinder inserted into the pressurized fluid source, the above sample has been taken at prevailing temperature and pressure, providing an accurate sample of the contents of the pressurized fluid source.
A method of using the ME sample cylinder of the present invention may thereby be summarized as follows:
As an alternative to the zero volume methodology, above, a sample cylinder or other sample container may be evacuated prior to use to insure non-contamination of the sample cavity. Unlike the zero volume methodology above, evacuation of the sample cylinder prior to the sampling process eliminates the necessity of a moveable fluid barrier to selectively provide zero volume in the exemplary method illustrated in steps a-h, above. An alternative to evacuation could comprise the utilization of an inert gas, such as helium or the like, which could be provided at a pressure less than the process fluid to prevent contamination prior to sampling.
The present concept of spot sampling using a pre-evacuated sample cylinder is detailed in
By loosening 21 the cap from the body via turning the cap or body so as to loosen the threaded engagement 10′ between cap threads 10 and body threads 9, body seal 7 surface and cap seal 8 surface are separated 21′ from one another other, forming a space therebetween to allow fluid passage into 22 and out 22′ of cavity 6 via a fluid pathway which passes between separated body seal 7 surface and cap seal 8 surface, as well as the space forming the groove 13 between the body and cap. Body and cap threads 9, 10, respectively, in the present embodiment preferably have a tolerance relative one another so as to facilitate the passage of pressurized fluid therebetween when loosened so that the cap need not be fully removed from the body for the passage to occur, with fluid passage preferably possible upon separation of the cap seal 8 from the body seal 7.
Continuing with
When CB sample cylinder is inserted 23 into housing 14a,
It is noted here that the term “sampling cylinder” or “micro cylinder” is not intended to limit the structure to sampling, or containers which may be used for other purposes, such as collection and storage. Accordingly, the terms “sampling cylinder”, “micro cylinder” or the like should be considered in the present disclosure as synonymous with storage cylinder, collection cylinder, or like devices.
During sampling, one inserts the CB sample cylinder into the fluid process and loosens the cap 2 from the body 3 so as to separate the body seal 7 from the cap seal 8, so as to allow the passage of the sample to pass directly into 22 the sample cylinder, at which point the cap 2 is tightened upon the body 1, causing the body seal 7 and cap seal 8 to engage, thereby containing the sample situated therein.
After the sample is collected, the CB sample cylinder is placed into the housing 14a, the cap 2 is loosened from the body 3, again separating the body seal 7 from the cap seal 8, allowing the passage of the sample from the sample cylinder, and through threaded port 18 for analysis, storage, further processing, etc.
The CB sample cylinder, having no contaminates in its sample cavity by virtue of lowering the pressure to essentially zero or having residual gas which cannot be detected by the sample fluid analyzer, at the beginning of a sampling procedure, and eliminating liquids and particles from the sample gas entering the sample cylinder, the three largest sources of error in spot sampling are eliminated.
Again, preventing vapor/liquid equilibrium changes (which alter the gas phase composition) is accomplished by sampling at the prevailing source fluid conditions of pressure and temperature, since the cylinder is immersed “in” the fluid source.
By providing a phase separation membrane during sampling, and allowing the sample gas to flow through a phase separation membrane designed to reject liquids (all types) and particles before entering the sample cylinder, entrained liquids are eliminated. The separated liquid can either be drained back into the pressurized process, or captured for analysis or the like.
Removing entrained liquids (in the case of gas sources such as natural gas) by using a phase separating membrane, which rejects liquids while allowing gases and vapors to flow through, eliminates the equilibrium changes by sampling only the gas phase of the fluid source at the prevailing pressure temperature conditions of the gas source. Particles are removed with the phase separating membrane and/or any other type suitable particulate filter prior to entry into the sample cylinder.
Having a near zero cylinder volume or undetectable diluent gas in the sample cavity can eliminate the need for purging the cylinder, which said cylinder purging represents one of the largest and most frequent sources of analytical error in the sampling of natural gas. Insertion of the ME or CB sample cylinder into a pressurized fluid process utilizing the dynamic sealing and pressure equalization can be accomplished with sample probes or the like.
Another option for opening and closing the valve formed by body sealing surfaces 7 and cap sealing surface 8 when the sample cylinder is in the housing is accomplished with the alternative design housing 14b,
Flat blade screwdriver 16 engaged 24′ in slot 4a permits rotation 24″ of the body 3 to facilitate the opening 24A and closing 24B of valve 20 formed by sealing surface 7 and sealing surface 8, respectively. This embodiment is different in that the body is turned relative to the cap, as opposed to the cap being turned relative to the body (shown in the embodiment of
An example of a method of sampling utilizing the apparatus of the present invention may comprise the steps, for example, of:
A. Providing a sample container comprising: A body therein a sample cavity, said body being formed so as to be immersed into a pressurized fluid process, and having threads and a sealing surface, a threaded cap with metal sealing surfaces being formed so as to mate with said threaded section and sealing surface of said body;
B. Inserting said container into a pressurized fluid;
C. Allowing the temperature of said container to reach equilibrium with the temperature of said pressurized fluid;
D. Loosening said threaded cap from said body threads, and allowing fluid from said pressurized process to migrate into said sample cavity;
E. Tightening said threaded cap to said threaded body so as to isolate said sample cavity;
F. Withdrawing said sample container from said pressurized process.
Once again referring to
Alternatively, but in similar fashion, diluent fluid may be introduced via pressurized flow through port 18 to flow into cavity 6 to urge contaminants from said cavity 6, or a combination of diluent fluid and evacuation may be used. A second port may be provided through sidewall 80 of housing, communicating with said containment zone 13′ for egress of diluent fluid in such an operation. Said cap is then tightened to said body so that seals 7, 8 are engaged, the sample cylinder is removed, then the sample is taken.
For example, the sample cylinder may be placed into a fluid to be sampled, where it is allowed to reach the temperature of the fluid, then the cap and/or body of the sample cylinder is loosened to separate seals 7, 8, so that fluid can flow into cavity 6 for sampling, then the cap is tightened to the body to close seals 7, 8, containing the fluid in the cavity for sampling.
The sample cylinder may then be placed into the housing, the cap loosened relative the body (or visa versa) to separate the seals 7, 8, allowing extraction of the fluid therein via containment zone 13′ and port 18.
The invention embodiments herein described are done so in detail for exemplary purposes only, and may be subject to many different variations in design, structure, application and operation methodology. Thus, the detailed disclosures therein should be interpreted in an illustrative, exemplary manner, and not in a limited sense.
The present application is continuation in part of U.S. patent application Ser. No. 12/344,418 filed Dec. 26, 2008 entitled “Devices for Obtaining Cylinder Samples of Natural Gas or Process A Gas, and Methods Therefore”, which Ser. No. 12/344,418 application is a divisional of U.S. patent application Ser. No. 11/151,018, U.S. Pat. No. 7,481,125, filed Jun. 13, 2005, which claims the benefit of Provisional Application 60/646,314 filed Jan. 24, 2005 entitled “Devices for Obtaining Cylinder Samples of Natural Gas or Process Gas”; which Ser. No. 11/151,018 application is also a continuation in part of U.S. patent application Ser. No. 10/631,501, U.S. Pat. No. 7,225,690 filed Jul. 31, 2003, entitled “Multi-Cavity Sample Cylinder with Integrated Valving”, which Ser. No. 10/631,501 application claims the benefit of Provisional Application 60/400,736 having a filing date of Aug. 2, 2002; which Ser. No. 11/151,018 application is also a continuation in part of U.S. patent application Ser. No. 10/408,026, U.S. Pat. No. 6,904,816, which is a divisional of U.S. patent application Ser. No. 09/915,192, U.S. Pat. No. 6,701,794 filed Jul. 25, 2001, which claims the benefit of Provisional Application 60/221,335 filed Jul. 26, 2000, and is a continuation in part of Ser. No. 09/162,239 now U.S. Pat. No. 6,357,304, having a filing date of Sep. 28, 1998, which is a continuation in part of U.S. patent application Ser. No. 08/701,406, now U.S. Pat. No. 5,841,036, filed Aug. 22, 1996.
Number | Name | Date | Kind |
---|---|---|---|
3203247 | Bicek | Aug 1965 | A |
3273647 | Briggs, Jr. et al. | Sep 1966 | A |
3638499 | Saint-Andre | Feb 1972 | A |
3831953 | Leibfritz et al. | Aug 1974 | A |
3835710 | Pogorski | Sep 1974 | A |
3848579 | Villa-Real | Nov 1974 | A |
3872721 | Ilfrey | Mar 1975 | A |
4014216 | Thornton et al. | Mar 1977 | A |
4112768 | Holland et al. | Sep 1978 | A |
4157040 | Barton et al. | Jun 1979 | A |
4175424 | Bimond et al. | Nov 1979 | A |
4269064 | Johnson et al. | May 1981 | A |
4346613 | Turner et al. | Aug 1982 | A |
4402911 | Walters | Sep 1983 | A |
4459266 | Lamoreaux | Jul 1984 | A |
4628750 | Welker | Dec 1986 | A |
4800763 | Hakkers et al. | Jan 1989 | A |
4821585 | Kempe | Apr 1989 | A |
4865729 | Saxena et al. | Sep 1989 | A |
4865811 | Newton et al. | Sep 1989 | A |
4928541 | Toon et al. | May 1990 | A |
4974456 | Ortiz et al. | Dec 1990 | A |
5191801 | Allen et al. | Mar 1993 | A |
5205988 | Tanaka et al. | Apr 1993 | A |
5303599 | Welker | Apr 1994 | A |
5369034 | Hargett et al. | Nov 1994 | A |
5406855 | Welker | Apr 1995 | A |
5442969 | Troutner et al. | Aug 1995 | A |
5536474 | Ungerer et al. | Jul 1996 | A |
5637792 | Kimura et al. | Jun 1997 | A |
5677478 | Murphy, Jr. | Oct 1997 | A |
5794695 | Peterson | Aug 1998 | A |
5814741 | Wang et al. | Sep 1998 | A |
5844123 | Marsh et al. | Dec 1998 | A |
5899349 | Moore | May 1999 | A |
6021661 | Lowell et al. | Feb 2000 | A |
6354345 | Nabity et al. | Mar 2002 | B1 |
6405580 | Kirts et al. | Jun 2002 | B2 |
6539312 | Nimberger et al. | Mar 2003 | B1 |
6659177 | Bolze et al. | Dec 2003 | B2 |
6675664 | Lilienthal et al. | Jan 2004 | B1 |
6793819 | Glenwright et al. | Sep 2004 | B2 |
RE39457 | Guirguis | Jan 2007 | E |
7178415 | Britt | Feb 2007 | B2 |
7552648 | McMechan et al. | Jun 2009 | B2 |
8556826 | Wan et al. | Oct 2013 | B2 |
20030033858 | Lambert et al. | Feb 2003 | A1 |
20030051565 | Nimberger | Mar 2003 | A1 |
20030089526 | Beeker | May 2003 | A1 |
20030103551 | Haddad et al. | Jun 2003 | A1 |
Number | Date | Country |
---|---|---|
3310032 | Sep 1984 | DE |
6-288880 | Oct 1994 | JP |
1250251 | Aug 1986 | SU |
1520382 | Nov 1989 | SU |
9502176 | Jan 1995 | WO |
Entry |
---|
Manual of Petro Meas Stde Ch 14, Sec 1, Collecting and Handling of Natural Gas Samples for Custody Transfer, API (4th Ed, Aug. 1993), pp. 2, 3, 6, and 12. |
Technical Memorandum—Metering Research Facility Program; Gas Research Institute, Transmission Operations, Apr. 1998, pp. 32-33. |
The Calibration Station (Newsletter of Colorado Engineering Experiment Station, Inc.) vol. 1, Fall Winter 1997, pp. 1-2. |
Welker, Thomas F., Sample Conditioning, 1997 Proceedings of AM SCH of Gas Measurement Tech, pp. 79-81. |
Ting, V.C., Effect of Entrained Liquid on Orifice Measurement, Sep. 1998, Proceedings of AM Sch of Gas Measurement Tech, pp. 85-88. |
A+ Corp, Prairieville, LA Series 100 Genie Membrane Separators Brochure, Rev Aug. 1998, pp. 1-7. |
A+ Corp, Prairieville, LA Series 200 Genie Membrane Separators Brochure, Rev Mar. 1996, pp. 1-6. |
A+ Corporation, “Series 100 Genie Membrane Separators”, Aug. 1998, pp. 1-7. |
NB9103334, Discrete Depth Groundwater Sampler, Sample Container and Monitor. Mar. 1, 1991, IBM Technical Disclosure Bulletin, Volume No. 33, Issue No. 10B, Page No. 334-335. |
Number | Date | Country | |
---|---|---|---|
60646314 | Jan 2005 | US | |
60100736 | Aug 2002 | US | |
60221335 | Jul 2000 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 11151018 | Jun 2005 | US |
Child | 12344118 | US | |
Parent | 09915192 | Jul 2001 | US |
Child | 10408026 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 12344118 | Dec 2008 | US |
Child | 12968017 | US | |
Parent | 10631501 | Jul 2003 | US |
Child | 11151018 | US | |
Parent | 10408026 | Apr 2003 | US |
Child | 10631501 | US | |
Parent | 09162239 | Sep 1998 | US |
Child | 09915192 | US | |
Parent | 08701406 | Aug 1996 | US |
Child | 09162239 | US |