U.S. patent application number 09/174131 was filed with the patent office on 2001-06-14 for integrated valve design for gas chromatograph.
Invention is credited to LECHNER-FISH, TERESA, XU, YANG.
Application Number | 20010003290 09/174131 |
Document ID | / |
Family ID | 22634957 |
Filed Date | 2001-06-14 |
United States Patent
Application |
20010003290 |
Kind Code |
A1 |
XU, YANG ; et al. |
June 14, 2001 |
INTEGRATED VALVE DESIGN FOR GAS CHROMATOGRAPH
Abstract
A gas chromatograph with multiple valves is disclosed. An
embodiment of the multi-valve gas chromatograph includes multiple
valves, multiple thermal conductivity detectors (TCD's), and a
manifold. This allows separation and measurement of a gas sample in
one compact integrated unit. The unit is particularly desirable
because the solenoids associated with the valves are attached
directly to the underneath of the manifold, thus eliminating the
need for tubing between the solenoids and the valves. Other
features may also be present. For example, a leak free multi-valve
block may include a first temperature zone heating the valves and
detectors and a second temperature zone heating the columns. The
leak free feature may be achieved by placement of tightening screws
through the center of each valve. Carrier gas insertion areas may
be provided in the multi-valve block to improve performance.
Improved separation of the temperature zones leading to further
gains in performance can be achieved by use of both a thermal
insulator and an air gap. Further, the temperature sensors placed
in the first temperature zone can be ideally located to minimize
measurement error, resulting in yet further performance gains.
Inventors: |
XU, YANG; (HOUSTON, TX)
; LECHNER-FISH, TERESA; (KATY, TX) |
Correspondence
Address: |
CONLEY ROSE & TAYON
P O BOX 3267
HOUSTON
TX
772533267
|
Family ID: |
22634957 |
Appl. No.: |
09/174131 |
Filed: |
October 16, 1998 |
Current U.S.
Class: |
137/885 ;
137/883; 137/884; 73/19.02 |
Current CPC
Class: |
Y10T 137/87885 20150401;
G01N 30/20 20130101; Y10T 137/87877 20150401; Y10T 137/8158
20150401; G01N 30/6047 20130101; G01N 30/30 20130101; G01N 30/66
20130101; Y10T 137/6606 20150401; Y10T 137/87893 20150401; F16K
11/022 20130101 |
Class at
Publication: |
137/885 ;
137/884; 137/883; 73/19.02 |
International
Class: |
F16K 031/126 |
Claims
What is claimed is:
1. A multi-valve assembly comprising: a plurality of plates and
diaphragms attached to form a plurality of valves, each valve
capable of being individually activated by actuation pressure,
wherein one of said plurality of plates is a manifold, and said
manifold includes a first common line passage suitable to carry an
actuation fluid applying said actuation pressure; a plurality of
actuation passages, there being at least as many of said actuation
passages as there are of said valves; said first common line
connecting to at least one of said plurality of actuation
passages.
2. the multi-valve assembly of claim 1, further comprising: a
plurality of solenoids attached to said manifold.
3. The multi-valve assembly of claim 2, wherein said plurality of
solenoids are attached directly to a bottom of said manifold, said
bottom being defined with respect to the remainder of said
plurality of plates.
4. The multi-valve assembly of claim 1, wherein said common line
passage connects to each of said plurality of actuation passages by
a groove in said manifold.
5. The multi-valve assembly of claim 1, wherein said manifold is
made from an insulative material.
6. The multi-valve assembly of claim 5, wherein said manifold forms
a portion of an insulative oven encapsulating the remainder of said
plates.
7. The multi-valve assembly of claim 5, further comprising at least
one of said valves attached to a length of tubing holding a fluid,
said tubing being inserted in insertion holes in at least one of
said plates, resulting in an efficient heat transfer between said
plate and said tubing.
8. The multi-valve assembly of claim 5, further comprising: a set
of tightening screws wherein each of said valves defines a valve
region and at least one of said set of tightening screws is
inserted through each of said valve regions.
9. A multi-valve device, comprising: at least two valves integrated
into a first region, said first region also including a first
heater, a gas stream property detector, and a first heat sensor; a
second heater and a second temperature sensor integrated into a
second region; said first temperature sensor and said gas stream
property detector lying on the same radian curve with respect to a
point lying in said second region.
10. the multi-valve device of claim 9 further comprising: a thermal
insulation; said first region and said second region being
separated by said thermal insulation.
11. The multi-valve device of claim 10, further comprising: an air
gap, said air gap also separating said first region and said second
region.
12. The multi-valve device of claim 9, wherein said first heater
lies along the outer periphery of said first region and said second
region lies inside said first region.
13. The multi-valve device of claim 12, wherein said heater is a DC
band heater.
14. The multi-valve device of claim 9, further comprising: a set of
screws, wherein one of said set of screws is located through a
center for each of said valves.
15. The multi-valve device of claim 9, fitter comprising: a
manifold with directly attached solenoids, said manifold providing
a passage for actuation fluid used by said solenoids, whereby said
actuation fluid passes from said manifold to said solenoid and then
through said manifold.
16. The multi-valve device of claim 9, further comprising:
insertion areas in said multi-valve device, said insertion areas
being suitable to hold coiled tubing.
17. The multi-valve device of claim 9, including at least five
valves.
18. A multi-valve block, comprising: means for directing a flow of
gas among a plurality of paths; means for detecting properties for
said flow of gas.
19. The multi-valve block of claim 18, further comprising: means
for heating at least a portion of said multi-valve block to a
predetermined temperature; means for detecting a temperature
proximate to said means for heating.
20. The multi-valve block of claim 18, further comprising: means
for ensuring that said paths are leak free, said means for ensuring
also being means to partially disassemble said multi-valve block.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] This invention relates to the field of gas chromatography.
In particular, this invention relates to a new gas chromatograph.
Even more particularly, this invention relates to a new gas
chromatograph having multiple valves and detectors.
[0005] 2. Description of the Related Art
[0006] The field of gas chromatography is concerned with analyzing
gas samples flowing through a process pipeline. A sample is
provided to a gas chromatograph, which then separates the sample
into portions and uses a variety of detectors to analyze the
concentration of particular components in the process stream.
[0007] Before now, a number of problems have existed with gas
chromatographs. For example, fast and accurate measurements are
desirable for any gas chromatograph. A gas stream flowing through
the process pipeline may be composed of many different classes of
components and ideally, each of these components would be analyzed.
However, conventional gas chromatographs cannot respond to process
changes as quickly as desired. Further, liquid contaminants in the
process stream can introduce further complications to any
analysis.
[0008] Another problem with previous gas chromatographs is a lack
of flexibility in analysis of the gas stream. It would often be
desirable to analyze different characteristics of the gas stream
without switching to another gas chromatograph. However, previous
gas chromatographs are restricted because of their limited number
of valves and by their lack of flexibility. As such, a gas
chromatograph is needed that can analyze complex process streams
with greater accuracy and speed.
[0009] Other problems with gas chromatographs have also existed in
the valve system contained in gas chromatographs. For example,
these valves are not easy to service. Maintenance may be necessary
because often the flows through a gas chromatograph are dirty, and
this contamination can affect the performance of key components in
the gas chromatograph. Substitution of clean components in the gas
chromatograph can minimize the problem, but disassembling the gas
chromatograph has in the past been a difficult and frustrating
experience. Thus, a need for a new gas chromatograph exists.
[0010] As known by those of ordinary skill, the prior art also
presents other problems that should be solved or minimized.
SUMMARY OF THE INVENTION
[0011] A disclosed embodiment includes a multi-valve assembly. This
multi-valve assembly includes a plurality of plates and diaphragms
attached together to form a plurality of valves. One of these
plates is a manifold that includes a common line passage and a
plurality of actuation passages, at least one of the activation
passages being connected to the common line passage, there being at
least as many actuation passages as there are valves. Alternately,
this embodiment may be seen as a multi-valve device including at
least two valves integrated into a first region that includes a
first region, a gas stream property detector such as a TCD, and a
first temperature sensor. A second region integrates a second
heater and a second temperature sensor, with the first region's
temperature sensor and gas stream property detector lying on the
same radial curve with respect to a point lying in the second
region.
[0012] The invention comprises a combination of features and
advantages which enable it to overcome various problems of prior
devices. The various characteristics described above, as well as
other features, will be readily apparent to those skilled in the
art upon reading the following detailed description of the
preferred embodiments of the invention, and by referring to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a more detailed description of the preferred embodiment
of the present invention, reference will now be made to the
accompanying drawings, wherein:
[0014] FIG. 1 is a simplified diagram of a gas chromatograph
system.
[0015] FIG. 2 is a simplified schematic of a gas chromatograph.
[0016] FIG. 3A is a schematic diagram of a valve in an ON
configuration.
[0017] FIG. 3B is a schematic diagram of a valve in an OFF
configuration.
[0018] FIG. 3C is a schematic diagram of a multiple valve system
for analyzing a sample.
[0019] FIG. 4 is an illustrative cut-away view of a valve.
[0020] FIG. 5 is an illustrative cut-away view of a solinoid.
[0021] FIG. 6 is an exploded isometric view of an embodiment of a
multi-valve block.
[0022] FIG. 7A is a top view of an upper piston plate for the
multi-valve block of FIG. 6.
[0023] FIG. 7B is a bottom view of an upper piston plate for the
multi-valve block of FIG. 6.
[0024] FIG. 8A is a top view of a lower piston plate for the
multi-valve block of FIG. 6.
[0025] FIG. 8B is a bottom view of a lower piston plate for the
multi-valve block of FIG. 6.
[0026] FIG. 9A is a top view of a base plate for the multi-valve
block of FIG. 6.
[0027] FIG. 9B is a bottom view of a base plate for the multi-valve
block of FIG. 6.
[0028] FIG. 10A is a top view of a primary plate for the
multi-valve block of FIG. 6.
[0029] FIG. 10B is a bottom view of a primary plate for the
multi-valve block of FIG. 6.
[0030] FIG. 11 is a sealing diaphragm for the multi-valve block of
FIG. 6.
[0031] FIG. 12 is a cushion diaphragm for the multi-valve block of
FIG. 6.
[0032] FIG. 13A is an upper actuator diaphragm for the multi-valve
block of FIG. 6.
[0033] FIG. 13B is a lower actuator diaphragm for the multi-valve
block of FIG. 6.
[0034] FIG. 14 is a cut-away view of a multi-valve assembly during
operation.
[0035] FIG. 15 is a top view of the bottom piece of insulation for
a multi-valve assembly oven.
[0036] FIG. 16 is a cross-section view of an embodiment of the
multi-valve assembly.
[0037] FIG. 17 is an exploded isometric view of a second embodiment
of a multi-valve block.
[0038] FIG. 18A is a top view of a primary plate for the
multi-valve block of FIG. 17.
[0039] FIG. 18B is a bottom view of a primary plate for the
multi-valve block of FIG. 17.
[0040] FIG. 19A is a top view of an upper piston plate for the
multi-valve block of FIG. 17.
[0041] FIG. 19B is a bottom view of an upper piston plate for the
multi-valve block of FIG. 17.
[0042] FIG. 20A is a top view of a lower piston plate for the
multi-valve block of FIG. 17.
[0043] FIG. 20B is a bottom view of a lower piston plate for the
multi-valve block of FIG. 17.
[0044] FIG. 21A is a top view of a base plate for the multi-valve
block of FIG. 17.
[0045] FIG. 21B is a bottom view of a base plate for the
multi-valve block of FIG. 17.
[0046] FIG. 22 is a view of a lower sealing diaphragm of FIG.
17.
[0047] FIG. 23 is a view of a lower actuator diaphragm of FIG.
17.
[0048] FIG. 24 is a view of a upper actuator diaphragm of FIG.
17.
[0049] FIG. 25 is a view of a cushion diaphragm of FIG. 17.
[0050] FIG. 26 is a view of an upper sealing diaphragm of FIG.
17.
[0051] FIG. 27 is a perspective view of a multi-valve assembly
including manifold and solenoids.
[0052] FIG. 28A is a top view of a manifold for the multi-valve
block of FIG. 17.
[0053] FIG. 28B is a bottom view of a manifold for the multi-valve
block of FIG. 17.
[0054] FIG. 29 is a first cross-sectional view of the second
embodiment of the multi-valve assembly
[0055] FIG. 30 is a second cross-sectional view of the second
embodiment of the multi-valve assembly.
[0056] FIG. 31 is an illustration of a gas chromatograph system
adapted for use in a refinery environment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0057] FIG. 1 shows a gas chromatograph system generally built in
accordance with the teachings herein. Gas flows through a process
pipeline 110, a sample of which is taken by a sample probe 120
prior to being introduced to gas chromatograph (GC) 100. The gas
sample may be filtered and heat traced generally along tubing 130
before flowing into gas chromatograph 100. This heating may be
required for gases that may condense into a part gas, part liquid
flow at cooler temperatures. After being analyzed by the gas
chromatograph, the gas sample is either returned into the process
pipeline 110, or vented to the atmosphere.
[0058] Referring to FIG. 2, gas chromatograph 100 includes valve
assembly 210 connected to multiple columns 220 and detectors 230,
in this case, thermal conductivity detectors (TCD). A gas sample
generally follows path 240 through valve assembly 210, columns 220
and TCDs 230. The valve assembly allows the selection of columns
220 which contain a liquid phase, or porous polymer, or other
material that acts to separate the gas sample into multiple
portions, each portion being sequentially released to the TCDs 230.
For example, a gas sample may contain various molecular weight
hydrocarbon components. Column 220 could separate the gas sample so
that lower molecular weight hydrocarbon components would elute from
the column first, followed by a higher molecular weight component,
etc.
[0059] Referring to FIGS. 3A and 3B, the operation of a valve is
shown. Valve 300 includes a plurality of valve ports, labeled 1-6.
It will be appreciated that more or fewer number of ports may also
be used. Incoming line 310 provides a gas sample to valve 300.
Exhaust line 320 expels the gas sample from the valve 300. Solid
lines 330 show open passages between ports, whereas dotted lines
340 indicate blocked passages between the ports.
[0060] A solenoid (not shown) places valve 300 into either an ON
position, as shown in FIG. 3A, or an OFF position, as shown in FIG.
3B. When a valve is in the ON position, gas flows from incoming
line 310, through port 1 to port 6, through line 315 and finally
through port 3 to port 2 and out exhaust line 320. When the valve
is in the OFF position, gas flows from incoming line 310, through
port 1 to port 2 and out through exhaust line 320.
[0061] FIGS. 3C and 3D illustrate how a pair of valves may operate
either alone or in combination with additional valves (not shown).
A first valve 300 includes an array of 6 valve ports. A second
valve 350 also includes an array of 6 valve ports. Associated
tubing 310, 315, 320, 325 and 390, and columns 360 and 370 are also
shown as well as dual TCD 380.
[0062] Incoming line 310 is attached to a sample transport line
(not shown). When first valve 300 in an OFF position, gas sample
flows from incoming line 310 to port 1 to port 2 of the valve 300
and out exhaust line 320. When valve 300 is in an ON position,
however, gas sample flows from port 1 to port 6 and then through
sample loop 315. That gas then flows from port 3 to port 2 of valve
300 and is expelled out exhaust line 320. At this time, the sample
loop 315 is filled with a gas sample. This means that, if valve 300
is turned OFF at this time, a gas sample is trapped within the
sample loop 315.
[0063] Turning now to valve 350, when it is in an OFF
configuration, carrier gas flows from carrier gas input line 390
through port 2 of valve 350, to port 1 and then through carrier
tubing 325. At this time, valve 300 is also in an OFF
configuration, so that the carrier gas in tubing 325 is forced
through port 5 to port 6 and through gas sample tubing 315.
Consequently, this action forces the gas sample down column 360 via
ports 3 and 4. The gas sample can then additionally be forced
through column 370 and into the dual TCD 380 via ports 4 and 3.
Many other port combinations also exist and are within the skill of
one in the art. Thus, the valves may be connected in series to form
"channels."
[0064] Each channel feeds into a corresponding TCD pair (a
measurement TCD and a reference TCD). Use of more than one TCD pair
results in a simultaneous analysis by the TCD's of the sample
flowing through their corresponding attached columns. This parallel
analysis results in a increased analysis speed as compared to
serial analysis. Further, because technology currently limits the
channels and the detector pairs to a one-to-one correspondence, the
number of channels in use at any particular time is limited both by
the number of valves and by the number of detectors. Of course, the
greater the number of valves, the greater the number of potential
channels, and the more potential for more parallel processing and a
faster overall system. But even if the number of detectors limits
the number of channels being used at any one time, a greater number
of valves results in a greater number of channels from which to
choose for each TCD. For example, a multi-valve system may have
sufficient valves to operate eight channels. Even if only two
detector pairs exist, such that only two channels can be in use at
any one time, the detector pairs can be designed to select which
channel among those eight channels it is connected to. This
dramatically increases the flexibility of the presently disclosed
gas chromatograph system.
[0065] Referring to FIG. 4, a cross-section of a partial valve
assembly is shown. Valve 400 includes a base plate 410 with
activation ports 412 and 414, a lower actuator diaphragm 420, a
lower piston plate 430 with associated long piston 435, upper
actuator diaphragm 440, upper piston plate 450 with associated
short piston 455, cushion diaphragm 460, sealing diaphragm 465, and
primary plate 470 with valve ports 472 and 474 therein. These valve
ports suitably could be ports 1 and 6 as shown in FIG. 3.
[0066] Referring back to FIG. 4, gas sample 480 enters valve port
472. This gas sample 480 travels out valve port 474 when long
piston 435 is in an elevated (closed) position and short piston 455
is not. Long piston 435 is elevated by gas pressure applied to
activation port A 412. This pressure deforms lower actuator
diaphragm 420 and forces long piston 435 in an upward direction in
lower piston plate 430. Upper end of long piston 435 then abuts
against primary plate 470. Similarly, short piston 455 is actuated
by gas pressure from activation port B 414, and forces gas sample
480 to path 485.
[0067] Whether a valve is in an ON or OFF position depends upon a
solenoid that applied gas pressure alternately to either activation
port A or activation port B. FIG. 5 generally illustrates the
operation of a solenoid. Solenoid 500 includes a common line port
510, exit port 520 corresponding to activation port A, exit port
530 corresponding to activation port B, release port 525 for exit
port A or exit port B, and control leads 540. Tubing 550 connects
to each of common line port 510, and exit ports 520 and 530. Exit
ports A and B connect to activation ports A and B in FIG. 4,
respectively. Common line port 510 connects to a gas under
pressure. Gas pressure applied to either of activation port A or
activation port B controls whether the corresponding valve is in an
ON or OFF position. Electrical control signals from leads 540
control whether common line 510 is connected to exit port A or exit
port B, and thus whether gas pressure is applied to activation port
A or activation port B. Some variation to the particulars of this
design is possible while still staying within the teachings of the
invention.
[0068] FIG. 6 shows an exploded view of an embodiment of the
multi-valve block 600 including an open area 605, base plate 610
with associated dowel pins to align components, a lower activator
diaphragm 620, a lower piston plate 630 with associated long
pistons 635, an upper activator diaphragm 640, an upper piston
plate 650 with associated short pistons 655, a cushion diaphragm
660, a sealing diaphragm 665, and a primary plate 670. Each piston
includes a lower base portion with a pole extending therefrom. Hole
sets 680 and 690 are suitable for two pairs of TCD'S. First set of
screws 615 for insertion through base plate 610, lower piston
plate, and upper piston plate are shown as well as a second set of
screws 675 for insertion through primary plate 670, upper piston
plate 650, and lower piston plate 630. In addition, because there
are five valves, five solenoids (not shown) are also present, each
controlling a different valve.
[0069] As can be seen, the multi-valve device 600 includes 5
valves, with each valve having six ports. By integrating multiple
valves into a single multi-valve block, a compact device is
achieved that can separate a gas sample into a large number of
columns as discussed above. This facilitates faster and more
precise analysis of the gases contained in the gas sample.
Manufacturing costs can also be reduced. The teachings herein can
be used to integrate more or fewer than 5 valves into a single
unit, and more or fewer valve ports per valve. For example, if a
greater number of valves is desired, up to 7 valves can easily be
located in the embodiment shown in FIG. 6.
[0070] One manner in which the embodiment of FIG. 6 makes faster
and more precise analysis of the gas sample is reduction of what is
known as "dead volume." Increased dead volume results when the
components of a gas chromatograph are widely spaced and undue
mixing of the fluid occurs. This mixing of the gas or fluid sample
results in a "band broadening." Band broadening is undesirable
because the area of a band of an analysis corresponds to
concentration and these bands should not overlap. Consequently, a
series of broad bands results in a much slower analysis than is
possible with a series of short, compact bands. Therefore, an
integrated, compact design is particularly desirable from a
performance perspective. Further, the illustrated geometry provides
sufficient area for a first and second set of TCD's. While these
TCD's may be located outside the multi-valve block if desired (e.g.
to integrate a greater number of valves into the multi-valve
block), the inclusion of the TCD's in the multi-valve block helps
further miniaturize the device and make it more compact.
[0071] FIGS. 7A and 7B show top and bottom views respectively of
the upper piston plate of FIG. 6. Referring to the top view of FIG.
7A, locations 701-705 for 5 valves are shown. Screw holes,
generally at 720, are also shown for accepting screws to tighten
together the primary plate with other plates. Holes 750 are for
screws from the bottom to tighten the plates together, while holes
760 are fore dowel pins to position the valves. Turning to the
bottom view of the upper piston plate shown in FIG. 7B, locations
701-707 are similarly shown. Each valve includes sufficient room
730, 735 for 3 piston bases and 3 piston poles. Raised edges 740
around the perimeter of each valve location are also shown. The
raised surfaces defined by the raised edges exist on both sides of
the upper and lower piston plates. A raised edge of 0.032 inches
could be used, for example. These raised edges 740 reduce the
surface area upon which the screws 615 and 675 provide force and
thereby reduce the chance of leakage.
[0072] Referring back to FIG. 6, it can be seen that two sets of
screws are shown corresponding to holes 720 and 750. These two sets
of screws that protrude through holes 720 and 750 simplify
maintenance of the invention. A bottom set of screws 615 extends
through the base plate 610, lower piston plate 630, and upper
piston plate 650. Screws 615 attach these plates together. A top
set of screws 675 extends through the primary plate and the upper
piston plate to hold those plates together. This dual screw set
approach simplifies maintenance because the loosening and removal
of screws 675 allows access and replacement of the sealing
diaphragm 665 and cushion diaphragm 660 without disassembly of a
greater number of plates than necessary. It is the sealing
diaphragm that becomes most contaminated by the dirty gas that
flows through the multi-valve. A relatively low torque of about 10
ft/lbs. has been found acceptable for these screw sets while making
the removal of these screws as easy as possible. The multi-valve
configuration also simplifies maintenance because, by virtue of
multiple valves in an integrated unit, replacement of only one
diaphragm is necessary rather than the multiple diaphragms that
would otherwise be necessary for multiple valves.
[0073] FIGS. 8A and 8B show the lower piston plate of FIG. 6. FIGS.
8A and 8B are the upper and lower views respectively of the lower
piston plate. Referring to FIG. 8A, once again, locations 801-805
are provided for the five valves, in addition to an area for two
sets of TCDs. Holes 820 and holes 825 accept tightening screws.
Also shown are five triangular grooves 830 and accompanying holes
840 within each groove. Gas from the solenoids travels through the
actuation holes 840 to the grooves 830. These grooves 830 provide a
path for the actuation gas that elevates the short pistons. Because
the valves of the illustrated embodiment have six ports, and thus
three short pistons per valve, a triangular shape is convenient
(but not necessary) to actuate all three short pistons
simultaneously. Turning now to the bottom view of FIG. 8B,
locations 801-807 are shown. Also generally shown at 840 are holes
connected to an actuator port through which gas exerts pressure.
These holes 840 correspond to the grooves 830 of FIG. 8A. As can be
seen, space 830 is provided for the base of long pistons 635.
[0074] FIGS. 9A and 9B show the top and bottom views respectively
of the base plate. Referring to FIG. 9A, similar to FIG. 8A, a
plurality of grooves 930 are shown, with each groove encompassing a
hole 940 for actuator gas. In addition, actuator holes 945
traveling up to the lower piston plate are additionally shown. FIG.
9B illustrates the bottom view of the base plate. Illustrated are
slot 960 and holes 970, 980, and 990. Slot 960 is present because
it simplifies the removal of diaphragms upon disassembly. In
particular, after a valve has been assembled, the diaphragms tend
to stick to a contact surface, and the slots provide an area where
the diaphragms can be easily grabbed onto. Hole 970 is a port A and
B common line that connects to port A and B on solenoids via
tubing. Holes 980 and 990 are screw holes. FIG. 9B also shows
cross-drill lines 962 and 964 representing drilled areas for
insertion of carrier and sample gas tubing. Holes at the entrance
to each insertion area are also shown. The carrier and sample gas
are quickly and reliably preheated in the insertion areas defined
by cross-drill lines 962 and 964 from the warmth in the multi-valve
block.
[0075] FIGS. 10A and 10B show the upper and lower view of a primary
plate of FIG. 6. Referring now to FIG. 10A shown are TCD holes
1050-1053 and associated tubing holes 1060-1063. Also shown is a
hole 1070 suitable for a RTD heat sensor. FIG. 10B shows a bottom
view of the primary plate. Included are holes 1010 to accept screws
and 1020 to accept dowel pins.
[0076] FIGS. 11-13 illustrate the diaphragms of FIG. 6. FIG. 11
shows the sealing diaphragm of FIG. 6. The sealing diaphragm is
preferably made from 2 mil thick Kapton.TM. made by DuPont with a
0.5 mil teflon coating on each side. FIG. 12 shows the cushion
diaphragm of FIG. 6. The cushion diaphragm is preferably about
0.002"thick and is made from Nomax paper by DuPont. FIGS. 13A and
13B illustrate upper and lower actuator diaphragms. Both actuator
diaphragms are preferably made from 3 mm thick Kapton.TM. made by
DuPont.
[0077] FIG. 14 illustrates a multi-valve block 1400 including a
spool 1410 with areas for a first RTD (Resistance Thermal Detector)
1420 and two TCD pairs 1425, an exterior surface 1430 to the
multi-valve block 1400, a band heater 1440 outside of the exterior
surface 1430, carrier gas preheat tubing 1450 located between the
exterior surface 1430 and the band heater 1450, and a base plate
610 as part of the multi-valve block. Spool 1410 contains one or
more cartridge heaters 1460 and a second RTD 1465. Referring back
to FIG. 6, a hole or open area 605 is present in the middle of the
multi-valve block. The open area 605 accommodates spool 1410 that
protrudes from the base plate 610. Columns 1470 wraps around the
spool 1410. Also shown are solinoids 1480 connected via tubing 1485
to the base plate at its lower end 1490. Band heater 1440 is an AC
band heater of approximately 200 Watts power.
[0078] During operation, a gas sample flows through tubing or
conduits 315 (not shown in FIG. 14) in the multi-valve block prior
to flowing through the piping of the columns 1470. In contrast, the
carrier gas flows through the carrier gas preheat tubing 1450 prior
to flowing through columns 1470. The carrier gas preheat tubing may
be located at different positions to heat the carrier gas to a
predetermined temperature. The carrier gas preheat tubing may be
just inside the band heater as shown in FIG. 14, or it may
preferably occupy insertion areas in the multi-valve block, as
explained in reference to FIG. 9. Thus, prior to being warmed by
the spool, both the carrier gas and the gas sample are heated to
approximately the temperature of the multi-valve block.
[0079] Thus, this arrangement provides for two heating zones. The
area proximate to the spool 1410 defines a second heating zone. A
first heating zone is defined by the temperature of the remainder
of the multi-valve block. The first RTD located in the multi-valve
block at 1420 measures the temperature of the first heating zone.
The second RTD located at 1465 within the spool 1410 measures the
temperature of the second heating zone. Two separate heating zones
are important because the gas flowing through the columns 1470
should ideally be about 3-5.degree. C. higher than the temperature
at each TCD (the temperature of the first heating zone). In
addition, the TCD's in the first heating zone should be kept to
within about 0.1.degree. C. of a predetermined temperature for
accurate analysis. The temperature variation in the second heating
zone should also be maintained within about a 0.1.degree. C.
tolerance. More heating zones may be added when desired to allow
the analysis of the complex samples.
[0080] In order to stabilize the temperatures in heating zones, an
"oven" is created from a thermal insulation material. This oven is
essentially a cylindrical sleeve that surrounds the rest of the
multi-valve device and keeps its temperature stable, except for the
solinoids, which must be kept away from the heat inside the oven.
Referring to FIG. 15, an illustrative bottom 1500 of this
insulation cylinder or sleeve is shown. As can be seen, it contains
a number of holes 1510, through which extend the tubing for the
solinoids and the legs of the base stand.
[0081] FIG. 16 illustrates the insulation 1610 for the "oven"
including the bottom 1500 of the insulation cylinder. As part of
them multi-valve block 1400, base plate 610 is adjacent to the
bottom of the insulation cylinder 1500. Legs 1600 to create
stand-off are made from Teflon.TM. 1605. Also shown is tubing 1485
that extends through the bottom piece 1500 to the lower surface
1490 of the multi-valve block 1400.
[0082] A second embodiment of the invention was developed
subsequent to the above embodiment and is shown in FIGS. 17-30.
This embodiment of the invention is believed to be improved in a
number of respects to the first embodiment. FIG. 17 shows an
exploded view of the second embodiment for a multi-valve block 1700
in an inverted configuration. Such an inverted configuration is
preferred to simplify assembly. FIG. 17 includes an Ultem.TM.
manifold 1780 with associated Ultem.TM. plug 1782. Also shown are
lower sealing diaphragm 1765, base plate 1710 with carrier gas
preheat coil insertion areas, lower actuator diaphragm 1720, lower
piston plate 1730 with associated long pistons 1735, upper actuator
diaphragms 1740, upper piston plate 1750 with associated short
pistons 1755, cushion diaphragm 1760, sealing diaphragm 1775, and
primary plate 1770 with associated guide pins 1172. Also shown are
an open area 1705 in the center of the multi-valve block, torque
screws 1790, and Belleville washers. Insulation plugs 1704 are
inserted after torque screws 1790 have been tightened through the
manifold 1780. Screws 1795 are also shown.
[0083] FIGS. 18A and 18B show the upper and lower view of a primary
plate of FIG. 17. Referring now to FIG. 18A, five valves 1801-1805
with 6 ports 1810 each are shown, as well as TCD holes 1850-1853
and associated tubing holes 1860-1863. A hole 1870 is suitable for
an RTD heat sensor, and is set by set screws in hole 1875. Holes
1820 are for tightening screws. Hole 1835 is for mounting support
of TCD terminal block. In contrast to the hole for the RTD heat
sensor of FIG. 10, RTD heat sensor hole 1870 is located in the same
radial circle as the TCD holes 1850-1853. As can be appreciated,
because the temperature at the TCD is extremely important to the
accurate measurement of the gas sample, a temperature sensor (RTD)
should be placed as close as possible to the TCD. RTD heat sensor
hole 1870 accomplishes this. But further, because of the mass of a
multi-valve block, temperature gradients across the block can be
significant. The placement of RTD heat sensor hole 1870 in the same
radial circle as the TCD holes minimizes error from any temperature
gradient across the multi-valve block. FIG. 18B shows a bottom view
of the primary plate. Included are holes 1810 corresponding to the
valve ports of FIG. 18A, and holes 1820 for tightening screws. Slot
1870 to simplify maintenance and dowel pin holes 1880 are also
shown.
[0084] FIGS. 19A and 19B show top and bottom views respectively of
the upper piston plate of FIG. 17. Referring to the top view of
FIG. 19A, locations 1901-1905 for 5 valves are shown. Screw holes,
generally at 1920, are also shown for accepting screws to tighten
together the multi-valve block. Holes 1940 are for screws from
bottom to tighten together the valve block. As explained with
respect to the first embodiment, the dual screw sets of this
embodiment considerably simplify maintenance of this embodiment as
compared to prior art valves. Turning to the bottom view of the
upper piston plate as shown in FIG. 19B, slots 1960 simplify
maintenance as generally explained above with respect to the first
embodiment. Locations 1901-1905 are for the five valves. Each valve
location 1901-1905 includes sufficient room 1930, 1935 for 3 piston
bases and 3 piston poles.
[0085] Unlike the upper piston plate of the first embodiment as
shown in FIG. 7, the second embodiment does not include raised
edges to reduce the chance of leakage. The raised edges 740 of the
first embodiment were not desirable because significant
manufacturing costs were required to obtain such an edge. Instead,
some other way of reducing the chance of leakage was sought. The
second embodiment reduces the chance of leakage without raised
edges by placement of the tightening holes 1920 within the confines
of each valve. In particular, the tightening holes 1920 are located
at the center of each valve. This results in a leak-free fit for
the multi-valve block without the added expense of raised
edges.
[0086] FIGS. 20A and 20B show the lower piston plate of FIG. 17.
FIGS. 20A and 20B are the upper and lower views respectively of the
lower piston plate. Referring to FIG. 20A, once again, locations
2001-2005 are provided for the five valves. Holes 2080 are screw
holes, while holes 2085 are dowel pin holes. Also shown are five
triangular grooves 2030 and accompanying holes 2040, as well as
holes 2020, to accept tightening screws in the center of each
groove 2030. Gas from the actuation ports flows through the holes
2040. The grooves 2030 provide a path for the actuation gas,
resulting in a simultaneous elevation and actuation of the short
pistons. Because the valves of the illustrated embodiment have six
ports, and thus three short pistons per valve, a triangular shape
is convenient (but not necessary) to actuate all three short
pistons simultaneously. The triangular grooves of the second
embodiment are somewhat larger than those of the first as shown in
FIG. 8, to accommodate the tightening holes 2020 in their centers.
Turning now to the bottom view of FIG. 20B, locations for the
valves are shown, in addition to slots 2060. As can be seen, FIG.
20B also includes space 2030 for the base of long pistons 635,
tightening screw holes 2020, and other features explained in
reference to other Figures herein.
[0087] FIGS. 21A and 21B show the top and bottom views respectively
of the base plate 1710. Referring to FIG. 21A, holes 2160 and a
plurality of triangular grooves 2130 are shown, with each groove
encompassing a hole 2140 for actuator gas. Additional holes 2145
forming a path for actuator gas to elevate the short pistons is
also shown. Line 2150 indicates an elevation edge down to an area
2152. Area 2152 is an insulating air gap whose function is
explained below. Other features are also shown that have been
explained in reference to the other Figures. FIG. 21B illustrates
the bottom view of the base plate 1710. Shown are actuator gas
paths 2155, as well as screw holes 2170 and 2180. Pin holes 2185,
and shape silhouettes 2190 are also shown. Shape silhouettes 2190
indicate the locations for the preheat coil insertion areas. The
carrier gas in these preheat coils is thus warmed by the
multi-valve block. Holes 2170 and 2180 are screw holes. Holes 2185
are dowel pin holes.
[0088] FIGS. 22-26 illustrate the diaphragms of the second
embodiment. In particular, FIG. 22 illustrates a lower sealing
diaphragm of the second embodiment. This diaphragm is preferably a
5 mil Teflon sheet and ensures a leak-free fit between the manifold
and the base plate. There is no corresponding diaphragm on the
first embodiment. FIG. 23 illustrates a lower actuator diaphragm of
the second embodiment. FIG. 24 illustrates an upper actuator
diaphragm of the second embodiment. FIG. 25 illustrates a cushion
diaphragm of the second embodiment. FIG. 26 illustrates an upper
sealing diaphragm of the second embodiment. Each diaphragm includes
holes whose purpose is explained with respect to other Figures.
These diaphragms are preferably made from the same material as the
corresponding diaphragms of the first embodiment.
[0089] Referring now to FIG. 27, the second embodiment includes an
insulation manifold 1780 instead of the base insulation piece of
the first embodiment. Also shown are solenoids 2980, the
multi-valve block, a column cup 2920, column support 2727, and a
column cover 2745. To simplify viewing of the multi-valve assembly,
not shown in FIG. 27 is the remainder of the oven insulation that
surrounds the multi-valve assembly. As can be seen, one advantage
of manifold 1780 is that the solenoids attach directly to its lower
surface and thus tubing between the solenoids and the multi-valve
block is eliminated. This elimination of tubing between the
solenoids and the multi-valve block results not only in a
substantial savings, but also a quicker response time during
analysis.
[0090] FIGS. 28A and 28B are top and bottom views of the manifold
1780. FIG. 28A shows a universal common line hole 2800 and a common
line gas passage 2810 from the common line hole 2800 to a center
groove 2820. Also extending from center groove 2820 are a plurality
of solenoid actuation passages 2831-2835, one for each solenoid
(not shown).
[0091] FIG. 28B illustrates many of the same elements as FIG. 28A.
Referring now to FIGS. 28A and 28B, during operation, a single tube
carrying actuator gas connects to universal common line hole 2800.
From there, actuator gas travels through common line gas passage
2810 to center groove 2820. Actuator gas then travels to each
individual solenoid via the solenoid passages 2831-2835. At that
time, the actuator gas enters each solenoid (not shown), the
solenoids being attached firmly to the bottom of the manifold by
use of screw holes 2860. The actuator gas travels through the
solenoids and exits through the actuator gas holes 2850 or 2855 to
place the valves in either an ON or OFF configuration.
[0092] FIG. 29 shows the multi-valve assembly of the second
embodiment during operation. To simplify viewing, the oven for the
multi-valve assembly is not shown. Multi-valve block 2900 includes
areas for a first RTD in the same radial plane as the hole for the
two TCD pairs 2925, an exterior surface 2930 to the multi-valve
block 2900, a band heater 2940 outside of the exterior surface
2930, carrier gas preheat coil 2950, and a base plate 1710. Spool
2910 contains a cartridge heater 2960 and a second RTD 2965. Unlike
the first embodiment, a thermal insulation cup 2920 and an air gap
2925 separate the spool and the base plate. The columns 2970 wrap
around the spool 2910. An ULTEM manifold 2990 is attached. Also
shown are solenoids 2980 connected to the manifold 2990 at its
lower end.
[0093] Referring back to FIG. 17, a hole or open area 1705 is
present in the middle of the multi-valve block. This open area
accommodates spool 2910. Thermal insulation cup 2920 and air gap
2925 insulate the spool from the base plate. Thermal insulation cup
2920 is preferably made from nylon. The thermal insulation cup and
air gap are significant features of the second embodiment because,
as explained, the multi-valve assembly defines two heating zones,
each of which should be carefully monitored and maintained. The
design of the second embodiment separates these two heating zones
by the thermal insulation cup and air gap and therefore helps to
achieve temperature stability in each.
[0094] Carrier gas preheat tubing 2950 is coiled in holes formed in
the body of multi-valve block 2900, and the carrier gas is thus
warmed by the heat in the multi-valve block. Band heater 2940 is a
DC band heater of approximately 30 Watts power. The substitution of
this DC band heater in lieu of the AC band heater of the first
embodiment improves the performance of the multi-valve assembly by
smoothing out the temperature fluctuations and eliminating
electrical noise, and is another improvement over the first
embodiment.
[0095] FIG. 30 illustrates a multi-valve assembly including oven
insulation. The multi-valve assembly includes a multi-valve block
3000 including a base plate 3010 and manifold 3040. Also shown are
torque screws 3020 with associated insulation plugs 1704, standoffs
3060, oven insulation 3050 and solenoid 3080. As can be seen,
solenoid 3080 is immediately adjacent the manifold 3040. Actuator
gas 3030 flows through the manifold to the solenoid, and then back
through the manifold to actuate the appropriate pistons. The oven
insulation 3050 of the second embodiment is generally of the same
material as the first embodiment, but it is covered with stainless
steel around its exterior 3055 to provide reinforcement.
[0096] In addition eliminating the need for tubing from the
solenoids to the multi-valve assembly, manifold 3040 offers a
number of advantages over a bottom piece of insulation. The
manifold has good insulation properties. It has been found that
ULTEM has the requisite mechanical strength and insulation
characteristics, and works very well for such an application,
although it is likely not the only appropriate material. ULTEM.TM.
is made by Commercial Plastics, Inc. As an additional feature,
instead of being far removed from the multi-valve block, the
manifold design allows placement of the solenoids adjacent to the
manifold and thus proximate to the base plate. This makes the whole
assembly more compact and also increases the response time.
[0097] The insulation material has also been modified by placing
steel around its exterior. This results in an increased resistance
to warping as well as increased durability and ruggedness.
[0098] The teachings herein can be adapted to a variety of
environments. FIG. 31 shows a multi-valve assembly 3100 suitable
for use in a refinery environment. A multi-valve block 3110
including a column area 3115, TCD 3120, auxiliary column oven 3130,
and surrounding environment, generally at 3140. With this
arrangement, the multi-valve block 3110 has room for a greater
number of valves because the TCD 3120 is located outside the
multi-valve block. This is a desirable feature when analyzing
complex refinery samples. Also shown is an auxiliary oven that may
be either warmer or cooler than the multi-valve block. This
auxiliary oven provides for a greater number of heating zones for
chromatography columns with a corresponding increase in analysis
flexibility. Further, because of the refinery environment in which
this arrangement can be used, by moving the gas sample analyzer (in
this case a TCD outside of the multi-valve block), a more stable
temperature is achievable around the TCD 3120. The heater in this
embodiment may preferably be an air-bath oven. This further
increases the accuracy of the system.
[0099] Thus, while preferred embodiments of this invention have
been shown and described, modifications thereof can be made by one
skilled in the art without departing from the spirit or teaching of
this invention. The embodiments described herein are exemplary only
and are not limiting. Many variations and modifications of the
system and apparatus are possible and are within the scope of the
invention. Accordingly, the scope of protection is not limited to
the embodiments described herein, but is only limited by the claims
that follow, the scope of which shall include all equivalents of
the subject matter of the claims.
* * * * *