Fluid handling – Systems – Multiple inlet with multiple outlet
Reexamination Certificate
2000-03-30
2002-04-02
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Systems
Multiple inlet with multiple outlet
C137S606000
Reexamination Certificate
active
06363966
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
It is often very important to know what fluids are flowing through a conduit such as a pipeline. For example, a buyer and seller of gas may agree upon a price for the fluid flowing through a process pipeline based upon the content of the fluid stream. Thus, the fluid content must be measured. Where multiple pipelines are positioned near one another, it may be economical to use a single meter or measurement device to monitor all of the fluid flows. The device used to extract and deliver the fluid to the measurement device is traditionally referred to as a sampling system.
FIG. 1
includes a stream sampling system (“sampling system”)
100
. Although only a single pipeline is shown, it is to be understood that multiple pipelines may be present. Sampling system
100
includes a sample point attached to pipeline
110
, an analyzer
130
, and tubing
120
from the sample point to the analyzer
130
. Analyzer
130
may include a stream switching system
140
and gas chromatograph
150
. In operation, fluid flow through a process pipeline
110
. The sample point (preferably a probe) obtains a sample of fluid and delivers it to analyzer
130
via tubing
120
. Analyzer
130
measures the content of the fluid sample and either returns the sample to the pipeline or vents the sample to the ambient environment.
One problem with such a layout is the large distance from the analyzer
130
to the pipeline
110
, which creates a large “dead volume” of fluid. Increased dead volume results in undue mixing of consecutive fluid samples. This mixing of fluid samples results in “carry over” between samples for gas chromatograph analysis. Carry over is undesirable because accurate analysis requires that the analysis is representative of the fluid in the process pipeline. Since the volume of transport tubing and stream sampling components must be flushed a minimum of ten times to ensure a representative sample, the “dead volume” results in significant lag time between sample analysis. Therefore, upon a sampling of fluid from the pipeline
110
, the “dead volume” of fluid must be vented or otherwise disposed of before the new sample can be measured at the analyzer
130
. Further, although the magnitude of the “dead volume” could be reduced by placing the analyzer
130
closer to the sample point
110
, regulations and safety concerns mandate a minimum 50 feet distance between them. If placed closer than 50 feet from the pipeline
110
, the analyzer
130
must be contained in an expensive explosion-proof housing.
FIG. 2
includes a stream switching system
140
attached to an analyzer oven
250
that is part of gas chromatograph
150
. Three pipes or tubes
210
,
220
,
230
attach to switching system
140
, and correspond to first, second and third flow paths. The first pipe or tube
210
connects to a first sample point
212
and carries a first sample of unknown composition from, for example, a process pipeline. Included along “stream
1
” are pressure regulator
214
and pressure gage
215
, shut-off valve
216
, particulate filter
217
, and a first stream switching valve
218
. Second pipe or tube
220
connects to a second sample point
222
and carries second gas stream of unknown composition. Included along “stream 2” are pressure regulator
224
and pressure gage
225
, shut-off valve
226
, particulate filter
227
, and a second stream switching valve
228
. The third pipe or tube
230
connects to a third sample point
232
and a calibration sample of known composition. Included along the third path are pressure regulator
234
and pressure gage
235
, shut-off valve
236
, particulate filter
237
, and a third switching valve
238
. Third switching valve
238
connects not only to filter
237
, through one port, but also to first and second switching valves
218
,
228
through another. Yet another port of third switching valve
238
attaches to regulator
240
and flow meter
245
. Flow meter
245
attaches through a relatively long tube to sample shut-off valve
255
housed in analyzer oven
250
. Shut off valve
255
connects to a sample valve in the oven, and then connects to the vent
260
. As can be appreciated, although only two streams of unknown fluids are shown, additional streams could be added by the use of a greater number of flow paths.
During operation, a gas chromatograph housed in analyzer oven
250
is calibrated using the calibration sample from sample point
232
. The pressure and flow rate of this stream are maintained by pressure regulator
234
, regulator
240
and flow meter
245
. Because the composition of the calibration sample is known, it may be used to calibrate the gas chromatograph. The calibration sample flows through third switching valve
238
, through the gas chromatograph
150
and out sample vent
260
. If a measurement of the fluid at sample point
222
is desired, the gas along the second pipe is allowed to flow by actuation of second stream switching valve
228
, through first stream switching valve
218
, and through third stream switching valve
238
. The third switching valve
238
is the only valve in the stream switching system that on its own can prevent or block the flow of fluid from all the sample points. Thus, this configuration is referred to as a “single block” stream switching system. One drawback of this design is that the fluid from sample point
222
flows through all of the first, second, and third switching valves prior to arrival at the gas chromatograph, and malfunction of only a single one of these switching valves prevents the measurement of a sample of fluid from stream
2
.
If after the above-described measurement of stream
2
, it is desired to measure the fluid from stream
1
, the system must be purged of the previous fluid sample. Purging of the old fluid stream from the system prevents contamination between the streams. Thus, the stream switching system of
FIG. 2
would switch from stream
2
to stream
1
. At that time, adequate accuracy by the gas chromatograph has likely been assured if all the other necessary criteria have been met. Many refer to a configuration having a single sample vent as a “single bleed” stream switching system.
Thus, a “dead volume” of fluid in a stream switching system is a significant problem. Another problem encountered in a stream switching system is the reliability and maintenance of the system. Because an operator may visit a particular stream switching system only infrequently, the system should be accurate, reliable, as immune to breakdown as possible, and simple to repair when problems do occur. This highly sought after combination of features is not available with current stream switching systems. It would also be desirable to have a multi-use gas sampling system that can be rapidly reconfigured in the field, at a sampling site, or in a manufacturing facility for semi-custom application.
Another drawback in many prior systems is their difficulty in analyzing a complex fluids because of limitations in the associated gas chromatographs. It would be desirable if a stream switching system could be developed that could quickly transfer fluid sample to the analyzer. This drawback also reduces the usefulness of a stream sampling system.
A stream sampling system is needed that is faster, more reliable, more flexible, and more accurate than previous stream sampling systems. Ideally, such a stream sampling system could reduce the adverse effects of “dead volume.” This ideal stream sampling system would also be less prone to breakdown than previous models, while providing much faster and more accurate measurements.
SUMMARY OF THE INVENTION
The invention features a stream switching system including a housing forming at least one common stream path. The common stream path of this housing includes an actuatable input port corresponding to a first fluid sample, an actuatable input port corresponding to a second fluid sample, and a first actuatable output port to direct the first and second f
Conley & Rose & Tayon P.C.
Daniel Industries Inc.
Hepperle Stephen M.
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