Abstract:
A closed system odorant chamber or wick-style odorizer and method for transferring odorant to an odorant chamber is described. Two cylinders are connected to the odorant chamber, which in turn may be connected to a gas line. The pressure differential between the two cylinders causes odorant to flow into the odorant chamber until an appropriate odorant level is reached. After filling up the odorant chamber, the two cylinders are disconnected from the odorant chamber. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure; and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims under 37 C.F.R. § 1.72.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to natural gas processing, and more particularly to an apparatus and method for transferring, in a closed system, odorant to an odorant chamber while the apparatus continues to odorize natural gas. 
     BACKGROUND OF THE INVENTION 
     Natural gas is odorless. For safety reasons, odorant must be added to natural gas in order to detect leaks in natural gas systems. Typically, odorant is transferred from an odorant storage chamber to natural gas flowing in a gas line. To accomplish this, several odorization systems are available. One type of odorization system is a farm tap or wick-style odorizer. 
     Farm taps are small inline odorization systems that are usually composed of an odorant chamber connected to a gas line by a fitting. Typically, a cotton wick is inserted through the fitting such that the majority of the wick is located in the odorant chamber, with the remaining smaller portion of the wick being exposed to the natural gas stream in the gas line. In the odorant chamber, the wick contacts and becomes saturated with the odorant. By capillary action, the odorant travels up the wick and then is vaporized into the natural gas stream in the gas line, resulting in odorized natural gas downstream of the odorizer. 
     Currently, farm taps require the owner or operator to physically pour odorant into the odorant chamber. This is usually accomplished by disconnecting the odorant chamber from the gas line and pouring the odorant through the opening to which the fitting is attached during odorizer operation. If the farm tap or wick-style odorizer is equipped with a second opening in addition to the opening at the connection between the chamber and the gas line, odorant may also be poured into the odorant chamber by unplugging the second opening and pouring the odorant in through the second opening. 
     Regardless of how pouring is accomplished, at least three problems exist with regard to the current practice of pouring odorant into the odorant chamber. First, pouring usually results in a sufficient amount of odor being released into the surrounding environment, creating nuisance and exposure problems for nearby residences or businesses. A second problem is that the set-up and physical pouring of the odorant is not time efficient. A third problem is that the odorant chamber is typically disconnected from the gas line during odorant pouring, temporarily halting natural gas odorization. This third problem is typical in farm tap styles where the pouring in of odorant requires the removal of the odorant chamber from the gas line. 
     Therefore, what is needed is an apparatus and method that allows odorant to be transferred to an odorant chamber without exposing odorant to the environment and creating a nuisance, wasting field personnel work time, and interrupting natural gas odorization. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus and method for transferring natural gas odorant to an odorant chamber in a closed system while continuing to odorize natural gas. Two odorant cylinders are connected to an odorant chamber, which in turn may be connected to a gas line. One odorant cylinder is initially filled with odorant while the other odorant cylinder is initially empty. The pressure differential between the two additional odorant cylinders causes the odorant to flow into the odorant chamber until an appropriate odorant level is reached. The initially empty odorant cylinder is vented to the atmosphere in conjunction with a filter to prevent any nuisance-creating odors from entering the surrounding environment. After filling up the odorant chamber, the two additional odorant cylinders are disconnected from the odorant chamber. Consequently, odorant transfer is accomplished without exposing the odorant to the surrounding environment and without interrupting the odorization of natural gas in the gas line. 
     Therefore, in accordance with the previous summary, objects, features, and advantages of the present invention will become apparent to one skilled in the art from the subsequent description and the appended claims taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To illustrate the manner in which the advantages and features of the invention are obtained, a more particular description of the invention will be given with reference to the attached drawings. These drawings only illustrate selected aspects of the invention and thus do not limit the invention&#39;s scope. In the drawings: 
         FIG. 1  is a diagram illustrating an example of one embodiment according to the present invention; and 
         FIG. 2  is a side, cut-away view illustrating the interface between the odorant chamber, nipple fitting, wick, and gas line of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The components of one embodiment of the present invention and their corresponding reference numerals in the drawings will first be described and then the details of the embodiment in operation will be described. Specific examples are given to illustrate aspects of the invention, but those of skill in the art will understand that other examples may also fall within the meaning of the terms used. 
     Referring to  FIG. 1 , the components of a farm tap or wick-style odorizer  8  are described. The reference numeral  10  refers, in general, to an odorant chamber, tank, or other storage device, which is also the main body of the farm tap  8 , and having the openings  10   a ,  10   b , and  10   c . A fitting  12 , such as a nipple, is used to connect a gas line  14  to the odorant chamber  10 . 
     Referring now to  FIG. 2 , the inner components of the farm tap  8  are described. A wick  16  is connected to the fitting  12  with the opposite ends of the wick protruding into the inner portion of the odorant chamber  10  and the inner portion of the gas line  14 , respectively. 
     Referring back to  FIG. 1 , the components used to supply odorant to the farm tap  8  are described. A fitting  18 , such as a coupling, is used to connect an inlet valve  20  to the opening  10   b . A connector  22 , such as a dripless quick disconnect connector, is used to connect an odorant line  24  to the inlet valve  20  in this embodiment. A connector  26 , such as a dripless quick disconnect connector, is used to connect a pressurized source cylinder  28 , which is initially filled with odorant, to the odorant line  24 . 
     Next, the components used to transfer excess odorant out of the farm tap  8  are described. A fitting  30 , such as a coupling, is used to connect an outlet valve  32  to the opening  10   c . A connector  34 , such as a dripless quick disconnect connector, is used to connect an odorant line  36  to the outlet valve  32 . A flow meter  38  is connected inline with the odorant line  36 . A connector  40 , such as a dripless quick disconnect connector, is used to connect an excess cylinder  42 , which is initially empty of odorant, to the odorant line  36 . A charcoal filter  44  is connected to the excess cylinder  42 . 
     In operation, the farm tap is first connected to the gas line  14 . The inlet valve  20  and the outlet valve  32  are connected to the openings  10   b  and  10   c , respectively. The inlet valve  20  and the outlet valve  32  are initially both in the “closed” position. The odorant chamber  10 , initially empty of odorant, is connected to the gas line  14  perpendicularly. The odorant chamber  10  is oriented such that, when the odorant chamber  10  is filled, the odorant will move up the wick, substantially in the opposite direction of gravity. This orientation also results in the opening  10   c  being at a higher elevation than the opening  10   b , with respect to the ground level. 
     When the farm tap  8  is empty or close to being empty, the components used to fill the odorant chamber  10  with odorant may be assembled. The pressurized source cylinder  28 , initially filled with odorant, is positioned at a convenient location in relation to the odorant chamber  10 . Using the connectors  22  and  26 , the odorant line  24  is connected to the inlet valve  20  and the pressurized source cylinder  28 , respectively. 
     In like manner, the excess cylinder  42 , initially empty of odorant, is positioned at a convenient location in relation to the odorant chamber  10 . Using the connectors  34  and  40 , the odorant line  36 , with the flow meter  38  connected inline with the odorant line  36 , is connected to the outlet valve  32  and the excess cylinder  42 , respectively. If not already connected, the charcoal filter  44  is then connected to the excess cylinder  42 . 
     After the above connections have been made, the charcoal filter  44  and the excess cylinder  42  are configured such that there exists a vent path from the excess cylinder  42 , through the charcoal filter  44 , and out to the atmosphere. The pressurized source cylinder  28  is configured such that, when subjected to a pressure differential, odorant is able to flow out of the pressurized source cylinder  28 , through the odorant line  24 , and into the odorant chamber  10 . 
     To create a pressure differential in the apparatus, the outlet valve  32  is first adjusted from the “closed” to the “open” position. Next, the inlet valve  20  is adjusted from the “closed” to the “open” position. At this point in time, the pressure difference between the pressurized source cylinder  28  and the atmosphere results in the odorant flowing from the pressurized source cylinder  28  to the odorant chamber  10  through the opening  10   b . The odorant level in the odorant chamber  10  rises, filling the odorant chamber  10  until the odorant level reaches the opening  10   c . At this point, the odorant level substantially ceases to rise towards the opening  10   a , instead flowing out of the odorant chamber  10  through the opening  10   c . The odorant flows through the odorant line  36 , resulting in the flow meter  38  indicating that the odorant is flowing through the odorant line  36 . This indication by the flow meter  38  signals that the odorant chamber  10  is adequately filled up with the odorant. At this point, the inlet valve  20  is then adjusted from the “open” to the “closed” position, preventing the odorant from flowing into the odorant chamber  10 . The outlet valve  32  is then adjusted from the “open” to the “closed” position, resulting in the odorant chamber  10  being non-pressurized and filled with the odorant. 
     The excess odorant that travels through the odorant line  36  collects in the excess cylinder  42 . This excess cylinder  42  is vented to the atmosphere, with the charcoal filter  44  serving to prevent odor from entering into the atmosphere. 
     After the odorant chamber  10  is filled with odorant, the odorant lines  24  and  36 , the source cylinder  28 , and the excess cylinder  42  may be removed from the vicinity of the odorant chamber  10  using the connectors  22 ,  26 ,  34 , and  40 , respectively. The use of dripless quick disconnect connectors to connect the aforementioned components is recommended to prevent any odorant from entering the surrounding environment or atmosphere during apparatus assembly or disassembly. 
     Several advantages result from the present invention. For one, the invention is a closed system so there is no pouring of odorant from any container into the odorant chamber  10 . This results in the odorant never being directly exposed to the surrounding environment, preventing nuisance and exposure problems. Also, not having to physically pour odorant significantly reduces the time required to fill the odorant chamber  10 . By using the pressure differential between the pressurized source cylinder  28  and the atmosphere, the time required to fill the odorant chamber  10  using the present invention is substantially less than the time required to pour odorant into the odorant chamber  10 . Additionally, the present invention does not interrupt the odorization of the natural gas stream in the gas line  14 . Since the odorant chamber  10  remains connected to the gas line, odorant may continue to travel up the wick  16  and into the gas line  14  before, during, and after the filling up of the odorant chamber  10  with odorant. 
     It is understood that several variations may be made in the foregoing without departing from the scope of the invention. For example, many different types of containers suitable for storing gas or odorant and rated at an acceptable pressure rating may be used instead of the odorant chamber  10 , the pressurized source cylinder  28 , or the excess cylinder  42 . Also, the number of connectors used in conjunction with the odorant lines  24  and  36  may be varied. Although the above-described embodiment uses two connectors with each of the odorant lines  24  or  36 , this number could be reduced to one connector per odorant line, with the odorant lines  24  and  36  being attached to the pressurized source cylinder  28  and the excess cylinder  42 , respectively, throughout the operation of the invention. Also, the odorant lines  24  and  36  may not be used at all, instead using another type of connection arrangement between the pressurized source cylinder  28  and the inlet valve  22 , and the excess cylinder  42  and the outlet valve  32 , respectively. Also, any type of valve may be used for either the inlet valve  22  or the outlet valve  32 , such as a ball or needle valve. In addition, any type of flow meter may be used for the flow meter  38 , such as a digital, mechanical, or glass flow meter, for example. 
     Although only one exemplary embodiment of this invention has been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiment without materially departing from the novel teachings and advantages of this invention. In some instances, some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.