Patent Publication Number: US-2022235661-A1

Title: Nitrogen driven dc generator

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. § 119 (a) and (b) to U.S. Provisional Patent Application No. 63/141,147, filed Jan. 25, 2021, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Industrial facilities and equipment are often found in remote regions, far from cities and towns and, often, far removed from reliable sources of power, e.g., electrical power supplied by an electrical power grid. Power is essential, however, to operate this equipment (e.g., metering stations, local control systems, etc.). At some sites, for example, industrial pipelines transporting oxygen or nitrogen may be monitored for irregularities, which sometimes may lead to leaks that discharge gases at significant environmental and financial costs 
     These remote systems often make use of alternative power sources to operate pumps and other components in lieu of the electrical power supply via connection with the electrical power grid. Although combustion-based devices (e.g., gas generators) may be used, preference is given to alternative energy sources (e.g., solar panels and wind turbines) to avoid fuel costs and hydrocarbon emissions. Some locations may also include storage devices to store energy from the alternative energy sources. The storage devices can supplement output from the alternative sources, e.g., during low-sun and/or low-wind conditions. 
     Batteries are one common type of storage device. These systems may utilize a number of batteries that form a system or an array. Examples of the array connect the batteries in parallel to meet the discharge and storage needs at each remote sight. However, batteries are known to discharge at slightly different rates. This characteristic can lead to voltage imbalances that impact the amount of current that is drawn from each battery found in the array. As a result, stronger batteries with charge levels that are relatively larger than the charge levels of weaker batteries in the array may tend to carry the weaker batteries when driving a load (e.g., the pump). Operation of the array in this manner can reduce the life-span of the batteries, which in turn will require maintenance at greater frequency to replace dead and/or under-performing batteries at the remote sight. 
     There is therefore a need within the industry for a reliable backup system for critical remote electrically powered systems. 
     SUMMARY 
     A man-portable backup power generation method including introducing a compressed nitrogen gas stream into an expander turbine, expanding the compressed nitrogen gas stream within the expander turbine, thereby producing a rotational mechanical output, and introducing the rotational mechanical output into a power generator coupled to the expander turbine, thereby producing an electrical output. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein: 
         FIG. 1  is a schematic representation of one embodiment of the present invention. 
         FIG. 2  is another schematic representation of one embodiment of the present invention. 
         FIG. 3  is another schematic representation of one embodiment of the present invention. 
         FIG. 4  is another schematic representation of one embodiment of the present invention. 
     
    
    
     ELEMENT NUMBERS 
     
         
           101 =nitrogen gas stream 
           102 =expander turbine 
           103 =power generator 
           104 =mechanical coupling (between expander turbine and power generator 
           105 =electrical output 
           106 =nitrogen pipeline 
           107 =compressed nitrogen storage tank 
           108 =control cabinet 
           109 =low pressure nitrogen exhaust stream 
           110 =main circuit breaker—AC/DC power supply (in control cabinet) 
           111 =electrical power grid 
           112 =electrical current sensor 
           113 =electrical power switch (to control cabinet) 
           114 =programmable logic controller 
           115 =nitrogen gas control valve 
       
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer&#39;s specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     One embodiment of the present invention utilizes a compressed gas (with for example, nitrogen being the most commonly available) from a pipeline or any other compressed gas source (such as a compressed nitrogen storage tank) to spin a miniature expander turbine which will in turn rotate a small power generator. This power may then be used locally, for example by a pipeline meter station. This turbine/generator may be small and potentially man-portable, possibly being no larger than a small suitcase. These turbine/generators may be placed within a commercially available protective case, such as a Pelican, or Seahorse case. Thus, they may be easily distributed as needed, for example throughout the network, for use during prolonged power outages. Permanent units may also be built into the control cabinets for locations where electrical power grid AC power is unavailable or unreliable. The turbine/generator may be available in several different sizes as required to accommodate different electrical loads. 
     The turbine/generator may comprise a nitrogen driven scroll-type expander that is coupled to a DC generator to provide emergency power to local pipeline stations. Scroll-type expanders are known in the art, as indicated for example in U.S. Pat. No. 4,314,796. This generator may be designed to run continuously however their normal duty would likely be to operate them in a standby mode and only utilize their capacity during a loss of AC or solar power. The backup power generation method may, during normal/standby operation have a compressed nitrogen stream flow rate of zero, wherein compressed nitrogen is not allowed to enter the expander turbine and the electrical output is zero. And may, during a loss of local power, allow the compressed nitrogen stream to enter the expander and the electrical output satisfies local demand. 
     The generator may be very small, possibly about the size of a large lunch box (for example 10″×10″×6″) and may be installed inside existing cabinets. The backup power generation method may include an expander turbine and power generator which, along with the associated control and ancillary equipment, have overall dimensions of less than 20 inches in width, 20 inches in depth, and 20 inches in height, preferably less than 15 inches in width, 15 inches in depth, and 15 inches in height, more preferably less than 10 inches in width, 10 inches in depth, and 10 inches in height. 
     The backup power generation method may include an expander turbine and a power generator which, along with the associated control and ancillary equipment, have a combined weight of less than 75 lb, preferably less than 50 lb, more preferably less than 35 lb. 
     The exhaust from the unit may provide the cabinet with a nitrogen purge. As these cabinets typically are already purged and this unit may be designed to utilize the existing tubing that&#39;s already in place. The generator unit may provide 30 VDC or less. The generator unit may be been designed to provide 24 VDC, a common voltage used in instrumentation devices. 
     In some embodiments, during operation, the unit may produce less than approximately 500 watts, preferably less than approximately 250 watts, more preferably less than approximately 125 watts or about 5 amps power. This DC power may be feed directly to the cabinet batteries providing charge and operating voltage. The existing flow computer may be used to open a solenoid valve when the voltage falls to a predetermined level, the open valve may provide nitrogen gas to the scroll expander and thus begin generating power. 
     As used herein, the term “approximately 500 watts” is defined as being between 480 and 520 watts as measured at the generator output. As used herein, the term “approximately 250 watts” is defined as being between 235 and 265 watts as measured at the generator output. As used herein, the term “approximately 125 watts” is defined as being between 115 and 135 watts as measured at the generator output. As used herein, the term “approximately 5 amps DC” is defined as being between 4 amps and 6 amps DC as measured at the generator output”. 
     When the batteries reach a sufficient level of charge the flow computer may (close the solenoid valve which in turn will shut down the scroll expander. The device, may be used to operate remote stations, it may be used on pig skids etc. Also, since the device is very small and designed to reside inside a locked cabinet, this device may be used in remoter areas, possibly in other countries, where solar panels are often stolen and AC power is intermittent or unavailable. 
     Turning to  FIGS. 1 to 4 , one embodiment of the present invention is presented. Nitrogen gas stream  101  may come from nitrogen pipeline  106 , compressed nitrogen storage tank  107 , or any other available source of compressed nitrogen (not shown). The flowrate of nitrogen gas stream  101  into man-portable backup power generator  100  is regulated by nitrogen gas control valve  115 . Nitrogen gas stream  101  then enters the inlet port of expander turbine  102 . Within expander turbine  102  the compressed nitrogen expands and produces a rotational mechanical output which is transferred, through mechanical coupling  104 , into power generator  103 . Power generator  103  thus produces electrical output  105 . 
     As indicated in  FIG. 1 , during normal, or standby, operation, electrical power is available from electrical power grid  111 . This electrical power is sensed by electrical current sensor  112 , which sends a signal to programmable logic controller  114 . If programmable logic controller  114  senses the availability of electrical power from electrical power grid  111 , it sends a signal to close nitrogen gas control valve  115 . Thus, no nitrogen enters expander turbine  102 , and no electrical output  105  is produced by power generator  103 . 
     As indicated in  FIG. 2 , during a loss of power from electrical power grid  111 , electrical current sensor  112  sends a different signal to programmable logic controller  114 . In this case, programmable logic controller  114  fails to sense electrical power from the electrical power grid  111 , and now it sends a signal to open nitrogen gas control valve  115 . Now, nitrogen enters expander turbine  102 , and electrical output  105  is produced by power generator  103 . Low pressure nitrogen exhaust stream  109  exits expander turbine  102  and is exhausted into the atmosphere. The flowrate of electrical output  105  is then controlled by electrical power switch  113 . Electrical power switch  113  closes, and thus allows electrical power to enter control cabinet  108 . 
       FIG. 3  illustrates a normal, or standby, operation as described above in  FIG. 1 , with the exception that man-portable backup power generator  100  is permanently installed in control cabinet  108 . In this operational scenario, no nitrogen gas  101  enters expander turbine  102 , no electrical output  105  is produced, and electrical power switch  113  is open. 
       FIG. 4  illustrates an operation during a loss of power as described above in  FIG. 2 , with the exception that man-portable backup power generator  100  is permanently installed in control cabinet  108 . In this operational scenario, nitrogen gas  101  enters expander turbine  102 , electrical output  105  is produced, and electrical power switch  113  is closed. This allows power to be provided to control cabinet  108 , specifically to main circuit breaker or AC/DC power supply  110 . In this scenario, low pressure nitrogen exhaust stream is used to purge control cabinet  108 . 
     It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.