Patent Grant
9880065
The present invention relates to a system for monitoring and annunciating leakage of gas vapors and/or volatile material from a volatile material compressor.
A volatile material (gas) compressor is a pressure vessel in which a piston, moved by a compressor piston rod, compresses a volume of volatile material by decreasing the space in which the volatile material is contained. As the pressure increases, the higher pressure volatile material attempts to escape along the surface of the compressor piston rod and out of the compressor cylinder through the opening for the compressor piston rod. Packing material, which may take the form of a series of special rings, contained in a packing case, surrounds the compressor piston rod and impedes the volatile material from escaping into the environment.
When the packing material comprises rings, the efficiency of the rings is determined by several factors which include the conditions of the compressor piston, the compressor piston rod, the packing case and the rings, themselves. Wear of the packing rings is expected, and the timing of their replacement is crucial to efficient operation of the compressor apparatus and other compressor equipment.
We observe that regulatory requirements in the area of pollution prevention are becoming more and more stringent. Depending on the particular volatile material being compressed, for example, a volatile material (VOC) which may be regulated by the Environmental Protection Agency (EPA), leaks of escaping VOCs from a compressor apparatus can represent significant loss of revenue and could trigger possible environmental fines for the compressor operator.
Similarly, national emission standards for hazardous air pollutants (NESHAP) established pursuant to Section 112 of the Clean Air Act (as amended Nov. 15, 1990) regulate specific categories of stationary sources that emit (or have the potential to emit) one or more hazardous air pollutants (HAPs) (see generally Title 40 of the Code of Federal Regulations). Some examples of HAPs include formaldehyde, benzene, 1,3-butadiene, acrolein, acetaldehyde, and toluene (see larger illustrative list in Table 1). Similarly, a set of pollutants commonly referred to as “Criteria Pollutants” face regulatory scrutiny. These pollutants are generated by combustion and include Nitrous Oxides (NOx), Carbon Monoxide (CO) and Volatile Organic Compounds (VOCs). These compounds are regulated by the New Source Performance Standards (NSPS). A third set of regulated (or potentially soon-to-be regulated) gases are greenhouse gases (GHG), for example, methane and carbon dioxide.
1X′CN where X = H′ or any other group where a formal dissociation may occur. For example KCN or Ca(CN)2
2Includes mono- and di- ethers of ethylene glycol, diethylene glycol, and triethylene glycol R—(OCH2CH2)n —OR′ where:
3Includes mineral fiber emissions from facilities manufacturing or processing glass, rock, or slag fibers (or other mineral derived fibers) of average diameter 1 micrometer or less.
4Includes organic compounds with more than one benzene ring, and which have a boiling point greater than or equal to 100° C.
5A type of atom which spontaneously undergoes radioactive decay.
A business that fails to monitor and take appropriate action to correct leaks of volatile organic compounds (VOCs), hazardous air pollutants (HAPs), Criteria Pollutants or greenhouse gases (GHGs) is taking a risk of having their operating permits suspended in addition to the possibility of incurring significant fines. As used herein, the term “volatile material” includes, without limitation, VOCs, HAPs, Criteria Pollutants and GHGs.
In addition to regulatory concerns, we speculate that the lost revenue of escaping VOCs and other volatile materials at the site of compression of these gases is a significant incentive to monitor compressor equipment to enable quick repair or replacement of compressor equipment in the event of detected volatile material leaks.
Currently within the industry, we have sometimes observed that the decision by the compressor operator regarding the timing of maintenance is left to either audible detection of volatile material leaks or physical detection of escaping gas by placement of the operator's hand on the compressor apparatus (to detect the stream of the escaping volatile material). Thus, there is a continuing need for a system that can reliably monitor and annunciate emissions of equipment, such as compressors of volatile materials such as VOCs.
In view of the aforementioned problems, it is an object of the present invention to provide a system for detecting, monitoring and annunciating volatile material leaks comprising a compressor apparatus sized and configured to compress a volatile material.
In an exemplary embodiment, the apparatus, adapted for use in a compressor, comprises a compressor cylinder containing a central space; a compressor piston slidably engaged within said central space; a compressor piston rod, wherein said compressor piston rod is attached to said compressor piston; a packing case seated on said piston rod and contained in said central space; a detector housing comprising a detector housing cavity, an inlet port, an outlet port and a detector port, wherein said inlet port opens into said detector housing cavity and wherein said inlet port is in fluid communication with an interior of said packing case; a detector piston slidably engaged in said detector housing cavity with an inlet side head and a detector pin head, wherein said outlet port is open or closed to said detector housing cavity with a sliding of said detector piston; a pin slidably engaged within said detector housing cavity, said pin comprising a first end adjacent to said detector pin head and a distal end slidably engaged in said detector port; a spring springingly seated on said pin between said detector pin head and said detector port; a block comprising a pin insertion port and an interior block cavity, wherein said pin insertion port opens into said interior block cavity, and wherein said pin insertion port is configured so that said pin is capable of entering said interior block cavity through said pin insertion port; and a first collection pipe, wherein said first collection pipe is connected to said block, and wherein an interior of said first collection pipe is in fluid communication with said interior block cavity.
Another exemplary embodiment provides system for observing discharge of a volatile material subject to government regulation of discharge into an environment which system comprises: a compressor for compressing said volatile material, comprising a compressor cylinder, a compressor piston, a compressor piston rod, packing material which may allow discharge of said volatile material over time; a volatile material discharge detector comprising a housing containing a detector housing cavity in fluid communication with said packing material and a detector piston which moves within said cavity as an amount of discharged volatile material from said packing material increases in said cavity; an alert pin which extends from said housing when an amount of volatile material is present in said detector housing cavity; a block secured to said detector housing, wherein said block further comprises an interior block cavity and a pin insertion port which opens into said interior block cavity, wherein said pin insertion port is in fluid communication with said alert pin; and a first collection pipe, wherein said interior block cavity is in fluid communication with an interior of said first collection pipe.
In an embodiment of the invention said electrical responses of said pressure transducer are collected and stored in a computer. Said collected and stored electrical responses, or associated stored data values, may be analyzed by a computer program in said computer thereby predicting a need to repair or replace said packing material in order to decrease said discharge of said volatile material. It is speculated that said computer program would allow an operator to identify trends in the data collected by correlating gas pressure measurements made by said transducer with lost volume of gas from said compressor apparatus, thus allowing said operator to predict the optimal time to schedule a repair of said compressor apparatus.
Another exemplary embodiment of the invention provides a detector comprising a housing containing a detector housing cavity configured to receive and discharge volatile material received from an external source, wherein an accumulation of said volatile material can create an increased pressure in said detector housing cavity; a detector piston slidably engaged within said cavity, which detector piston moves within said cavity in response to a pressure of said volatile material received from said external source; a spring positioned within said cavity which spring is compressed by sliding movement of said detector piston; a detector pin which travels in said cavity, proximate to said spring, which detector pin is capable of being forced to partially extend from said housing when said increased pressure overcomes a resistance of said spring; and a block secured to said detector housing, wherein said block further comprises an interior block cavity and a pin insertion port which open into said interior block cavity, wherein said pin insertion port is in fluid communication with said detector pin; and a first collection pipe, wherein said interior block cavity is in fluid communication with an interior of said first collection pipe.
Another embodiment of the invention includes a method for assessing leaks of a volatile material subject to regulation of said leaks into an environment, which method comprises: providing a fluid connection between a volatile material compressor apparatus and a volatile material leak detector; capturing a first leaked amount of said volatile material from said compressor apparatus; transferring said first leaked amount from said compressor apparatus to said leak detector; observing a change to said detector caused by said transfer of said first leaked amount; providing a fluid connection between said leak detector and a zero emission block; providing a fluid connection between an interior of said zero emission block and an interior of a first collection pipe; capturing within said interior of said zero emission block a second leaked amount of said volatile material from said leak detector; and transferring said second leaked amount through said first collection pipe to a volatile material recapture system, a volatile material disposal system, or a system which both captures and disposes of said volatile material.
The above and other objects and features of the present invention will become apparent from the drawings, the description given herein, and the appended claims.
For a further understanding of the nature and objects of the present invention, reference should be had to the following description taken in conjunction with appended claims and with the accompanying drawings in which like parts are given like reference numerals.
The images in the drawings are simplified for illustrative purposes and are not depicted to scale. Within the descriptions of the figures, similar elements are provided similar names and reference numerals as those of the previous figure(s). The specific numerals assigned to the elements are provided solely to aid in the description and are not meant to imply any limitations (structural or functional) on the invention.
The appended drawings illustrate exemplary configurations of the invention and, as such, should not be considered as limiting the scope of the invention that may admit to other equally effective configurations. It is contemplated that features of one configuration may be beneficially incorporated in other configurations without further recitation.
Turning now to the Figures,
A portion of compressor piston rod 26 is surrounded by a packing case 28 near where compressor piston rod 26 extends from compressor cylinder 20. Compressor piston rod 26 moves through packing case 28 when compressor apparatus 14 is in operation.
In the exemplary embodiment of
In an embodiment of the invention depicted in
Housing 32 defines an inlet port 60 which opens into cavity 34 and which has NPT threads to receive threaded tubing (not shown). A detector piston 36 is slidably engaged in cavity 34 and is forced away from inlet port 60 as pressure from entering volatile material 12 increases. Housing 32 also defines an outlet port 62 which opens to cavity 34 depending on the sliding travel position of detector piston 36 (described below). Outlet port 62 has NPT threads to receive threaded tubing (not shown). In an exemplary embodiment, inlet port 60 and outlet port 62 are 0.5 inches in diameter; in an alternative embodiment, said ports are 0.25 inches in diameter.
It is speculated that the amount of discharged volatile material 12 coming from leaking packing case 28 is directly proportional to the degree of wear of packing ring or packing material 56.
Detector piston 36 is adjacent to or integral with alert pin 42, said alert pin 42 arranged to travel in said cavity 34 and on a side of detector piston 36 opposite said inlet port 60. Thus, they may be of unitary construction. In an exemplary embodiment, detector piston 36 is made of Teflon. In an exemplary embodiment, alert pin 42 slides synchronously with detector piston 36. Pin 42 is slidably engaged within cavity 34 and has a first end 78 adjacent to detector pin head 74 of detector piston 36 and a distal end 80 slidably engaged in a detector port 72. A spring 38, sized and configured to offer resistance to movement of detector piston 36, is located around pin 42 at first end 78 of pin 42 and seated between detector piston 36 and a bushing 68 in cavity 34. Volatile material 12 presses against a head area or inlet side head 40 of detector piston 36 causing movement or sliding travel of detector piston 36 and detector pin head 74 and compressing spring 38. In an exemplary embodiment, spring 38 has an R value of 1 lb per inch; however, the R value of spring 38 may be adjusted to a desired R value to meet an acceptable lost volume of volatile material. In an exemplary embodiment, spring 38 is made of a material resistant to corrosion by, and/or nonreactive with, VOCs and HAPs, for example, stainless steel or an alloy such as Inconel® sold by Special Metals Corp.
NPT threaded outlet port 62 provides an avenue for eventual removal of discharged volatile material 12. Threaded tubing 58 (best seen in
As may be seen in
One embodiment of the present invention is a method for assessing leaks of a volatile material subject to regulation of leaks into the environment. The method comprises providing a fluid connection between a volatile material compressor apparatus, capable of having a leak of said volatile material, and a volatile material leak detector; allowing transfer of a leaked amount of the volatile material from the compressor apparatus to the detector; and observing a change to the detector caused by the transfer.
The transfer of the amount of said volatile material is from a packing case of the compressor apparatus through connecting tubing to an inlet port of a housing of the detector. The packing case surrounds a compressor piston, and packing material interior to the packing case emits the transferred amount of the volatile material which passes through the tubing into the housing through a pathway.
The method further comprises placing a detector piston in the housing of the detector whereby the detector piston is displaced as the transferred amount of the volatile material passes though the pathway.
The method further comprises overcoming resistance of a spring within the housing, which spring is configured to retard movement of the detector piston.
The method further comprises forcing an alert pin out of the housing as the detector piston moves, which alert pin is positioned proximate to the detector piston and whereby a change in position of the alert pin can be visibly observed.
The method further comprises calibrating the alert pin with marks to permit visual perception of a distance the alert pin is forced out of the housing.
The method further comprises auditing the transfer by aligning a pressure transducer in fluid communication with the pathway and monitoring electronic signals emitted by the pressure transducer in response to changes in pressure within the pathway. The electronic signals are analog or digital signals.
The method further comprises collecting and storing the electronic signals by a computer.
The method further comprises analyzing the electronic signals by a computer program of the computer and predicting, by said computer program, a need to repair or replace the compressor apparatus in order to decrease the leaks of the volatile material.
The method provides that the packing material, which surrounds a compressor piston rod, comprises at least one packing ring formed from a more wearable substance than that of the compressor piston rod such that wear to the at least one packing ring enables leaking of the volatile material from the packing case.
Interior block cavity 92 is an opening that extends from pin insertion port 94 to recapture port 89. As can be seen, a continuous passage is created by pin insertion port 94, interior block cavity 92, and recapture port 89, and this passages goes through gasket 81, gasket 82 and the body of block 83. Pin insertion port 94 and interior block cavity 92 have internal diameters which are at least large enough to ensure that zero-emission block 90 does not impede the extension of alert pin 42, as described herein.
In an exemplary embodiment, gasket 81 and gasket 82 are made of a polytetrafluoroethylene (PTFE) based material, although standard gaskets of any suitable material which is not reactive or porous to volatile material 12 may be used.
In exemplary embodiments, block 83 is comprised of glass, plastic, polycarbonate or other transparent or translucent material that is not reactive or porous to volatile material 12. The material of block 83 is selected based on environmental concerns, as we speculate that polycarbonate is less susceptible to breaking or fracturing than glass but may not be safely used at temperatures over 300 degrees Fahrenheit, whereas glass is more susceptible to breaking or fracturing than polycarbonate, but can withstand temperatures of up to 1500 degrees Fahrenheit.
Plate 84 is one quarter inch thick steel (in an exemplary embodiment, 3/16 stainless steel) or aluminum (in an exemplary embodiment, anodized aluminum) and further comprises recapture port 89. Recapture port 89 is in fluid communication with pin insertion port 94 and interior block cavity 92.
Recapture port 89 and fitting 91 each have NPT threads, and fitting 91 is threadedly (and thereby removably) secured into recapture port 89. Recapture pipe 93 is fastened to fitting 91, such that the interior of recapture pipe 93 is in fluid communication with interior block cavity 92.
Bolt 85, bolt 86, bolt 87, and bolt 88 are threaded bolts. However, any suitable fastener may be used.
As is demonstrated, interior block cavity 92 is in fluid communication with the interior of recapture pipe 93, such that escaping volatile gas 12 can travel through interior block cavity 92 and recapture port 89 into recapture pipe 93.
We speculate that the pressure in recapture pipe 93 is lower than the pressure in tubing 58 because more volatile gas 12 flows into tubing 58 than around pin 42; and, because of said difference in flow rate, a Venturi effect causes volatile gas 12 to be sucked out of recapture pipe 93 into tubing 58. Furthermore, in an exemplary embodiment, volatile gas 12 flows through tubing 58 until tubing 58 vents to the atmosphere, at which point volatile gas 12 escapes or is burned. In another embodiment, tubing 58 connects to a relatively larger containment vessel. We speculate that such embodiments prevent the pressure of volatile gas 12 in recapture pipe 93 from reaching equilibrium with the pressure of volatile gas 12 in tubing 58.
As used herein the phrase “in fluid communication with” signifies that some means of connecting the designated elements is employed, such as tubing, lines, conduit, pipes, manifolds or the like, as long as fluid can pass between the designated elements.
We speculate that the following Tables 2 and 3 point out the economic factors which come into play when assessing compressor equipment leaks of volatile materials. These tables were developed based on our speculation of natural gas (methane) pipeline compressor performance. Leak rates for both tables were calculated from EPA information and various psi ratings. These tables are meant to show an appreciation of the economic impact the claimed invention would have on the industry.
Table 2 relates to the breakeven point in months to replace packing in the pipeline compressors when the cost of natural gas is $4.00 per thousand cubic feet (mcf). The cost is broken down by size of compressor piston rod (rod) and includes parts and labor (P&L). Leak rates in standard cubic feet per hour (scfh) are given across the top of the table. The breakeven point or time in months to recoup the cost of repair of the packing is shown in italics. For example, if the cost of natural gas is $4.00 per thousand cubic feet, the compressor piston rod has a 2 inch diameter and the leak rate is 150 scfh, we speculate that the time in months to breakeven would be 0.7 months.
1.9
1.6
1.4
1.2
1.1
0.7
0.6
0.4
0.2
0.1
1.9
1.6
1.4
1.3
1.1
0.8
0.6
0.4
0.2
0.1
1.7
1.5
1.3
1.1
1.0
0.7
0.5
0.3
0.2
0.1
1.8
1.5
1.3
1.2
1.1
0.7
0.5
0.4
0.2
0.1
2.0
1.7
1.5
1.3
1.2
0.8
0.6
0.4
0.2
0.1
Table 3, below, relates to our speculation as to the months to pay for installing a packing leak detector (PLD) in line with the pipeline compressors when the cost of natural gas is $4.00 per thousand cubic feet (mcf). As in Table 2, the cost is broken down by size of compressor piston rod (rod) and includes parts and labor (P&L). Leak rates in standard cubic feet per hour (scfh) are given across the top of the table as calculated from available industry data as in Table 2. The estimated (our speculation) time in months to recoup the cost of installing the PLD is shown in italics. For example, if the cost of natural gas is $4.00 per thousand cubic feet, the compressor piston rod has a 2 inch diameter and the leak rate is 150 scfh, the estimated (our speculation) time in months to recoup the cost of installation would be 1.3 months.
3.2
2.7
2.4
2.1
1.9
1.3
0.9
0.6
0.4
0.2
3.2
2.7
2.4
2.1
1.9
1.3
0.9
0.6
0.4
0.2
3.2
2.7
2.4
2.1
1.9
1.3
0.9
0.6
0.4
0.2
3.2
2.7
2.4
2.1
1.9
1.3
0.9
0.6
0.4
0.2
3.2
2.7
2.4
2.1
1.9
1.3
0.9
0.6
0.4
0.2
The foregoing description of the embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.
This invention is susceptible to considerable variation in its practice. Therefore the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications presented hereinabove. Rather, what is intended to be covered is as set forth in the ensuing claims and the equivalents thereof as permitted as a matter of law.
This application is a continuation-in-part of, and claims priority to, U.S. Non-provisional application Ser. No. 13/204,659 (Miguez et al.), filed Aug. 6, 2011, which is incorporated herein by reference as if set forth in full below.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3181496 | Bilbrey | May 1965 | A |
| 4072126 | Kemp | Feb 1978 | A |
| 4130130 | Stewart | Dec 1978 | A |
| 4766765 | Ezekoye | Aug 1988 | A |
| 4770044 | Ferris | Sep 1988 | A |
| 20070193349 | Petrucelli | Aug 2007 | A1 |
| 20080012236 | Reilly | Jan 2008 | A1 |
| 20090211341 | Witt | Aug 2009 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13204659 | Aug 2011 | US |
| Child | 14517722 | US |
