Patent Publication Number: US-2023155218-A1

Title: Fire suppression system for lithium-ion battery containers

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. Pat. Application No. 17/580,922, filed Jan. 21, 2022, which claims the benefit of U.S. Provisional Pat. Application No. 63/247,493, filed Sep. 23, 2021, both of which are incorporated by reference herein in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is generally directed toward a fire suppression system for use in mitigating fires caused by runaway thermal events in lithium-ion battery cells located within battery storage containers. 
     Description of the Prior Art 
     Alternative electrical power generation, such as solar and wind farms, is rapidly gaining ground against fossil-fuel power generation facilities in terms of overall market share. The downside to such alternative power generation is the problem of aligning power production with consumer demand. At times, alternative power generation facilities simply cannot produce enough power to meet consumer demand, such as at nighttime or cloudy weather, or in periods of calm winds. Moreover, even in the case of conventional power generation, consumer demand for power can outstrip the utility’s generating capacity, such as during extreme weather events. 
     To address these problems, utilities have increasingly invested in energy storage technologies, such as battery farms, in order to fill in the gap between generating capacity and consumer demand. The battery farms generally comprise one or more enclosed structures in which modular battery assemblies are stored. The battery assemblies comprise a plurality of individual battery cells stacked together into modules, which are then placed on shelves within a rack. The battery modules are charged during periods in which the utility has excess generating capacity, and then discharged during the aforementioned periods in which demand outstrips generation capability. 
     While generally safe, lithium-ion batteries can experience untoward thermal events resulting from runaway chemical reactions within one or more battery cells. If detected quickly, the affected cells can be taken offline and the threat posed by the cell is mitigated. However, if the thermal event cannot be stopped, a fire or other hazardous condition, which could lead to an explosion, can develop. Thus, systems should be in place to prevent propagation of the thermal event to adjacent battery cells. There are both active and passive systems designed to prevent thermal event propagation. A passive system may involve venting of the affected battery module and/or use of fire-retardant materials in the construction of the battery module. Active systems generally involve the deployment of a fire suppressing agent into the area surrounding the battery cell suffering the thermal event. 
     While it is hoped that the on-site active anti-propagation system is effective in extinguishing the fire, such is not always possible. Therefore, it is an important feature of the active anti-propagation system to buy time for human intervention to either physically remove the affected battery module from the system or provide fire fighting support. However, in some instances, the battery farms are quite remote from first responders, and the time for the first responders to arrive on scene could be greater than the protection time afforded by the anti-propagation systems. 
     Thus, there is a need in the art for a fire suppression system that can be used with battery storage facilities that can provide fire suppression until first responders can arrive to take further action, but also a failsafe to prevent an explosion from occurring should the fire suppression means be exhausted before the first responders can arrive. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the problems mentioned above and by providing a fire suppression system for use with one or more battery containers. 
     According to one embodiment of the present invention the fire suppression system comprises a water storage tank and a propellant tank connected to the water storage tank that is operable to deliver a pressurized gas to the water storage tank. A conduit network is connected with the water storage tank and extends into the one or more battery containers. The one or more battery containers comprise a plurality of battery racks each of which is configured to hold a plurality of battery modules. The conduit network comprises a plurality of nozzles, each being operable to deliver water from the water storage tank to one or more battery modules. A controller is coupled to the water storage tank that is operably connected to one or more exhaust fans located within the one or more battery containers. The controller is configured to actuate the one or more exhaust fans upon receiving a signal representing an operational condition associated with the water storage tank. 
     According to another embodiment of the present invention, there is provided a fire suppression system for use with one or more battery containers. The fire suppression system comprises an enclosure that is external to the one or more battery containers and having a water storage tank and a propellant tank connected to the water storage tank. The propellant tank is operable to deliver a pressurized gas from the propellant tank to the water storage tank. A conduit network is connected with the water storage tank and extends into the one or more battery containers. The conduit network is pre-charged with water under pressure provided by the pressurized gas from the propellant tank. The one or more battery containers comprise a plurality of battery racks, each of which is configured to hold a plurality of battery modules made up of a plurality of battery cells. The conduit network comprises a plurality of heat actuated nozzles each operable to deliver water from the water storage tank to a respective battery module. A controller is coupled to the water storage tank that is operably connected to one or more exhaust fans located within the one or more battery containers. The controller is configured to actuate the one or more exhaust fans and vent an interior compartment within the battery container in which the one or more battery racks are located upon receiving a signal representing an operational condition associated with the water storage tank. 
     According to still another embodiment of the present invention there is provided, a method of suppressing a fire within one or more battery containers. The method comprises providing a water storage tank and a propellant tank connected to the water storage tank. The propellant tank is configured to introduce a pressurized gas into the water storage tank. A conduit network is provided that is connected with the water storage tank and that extends into the one or more battery containers. The one or more battery containers comprise a plurality of battery racks, each of which is configured to hold a plurality of battery modules. The conduit network comprises a plurality of nozzles each operable to deliver water from the water storage tank to one or more battery modules. A flow of the water is delivered from the water storage tank through at least one of the plurality of nozzles in response to detection of a thermal event occurring within at least one of the battery modules. An operational condition associated with the water storage tank is detected and then one or more exhaust fans located within the one or more battery containers are activated in response to the detection of the operational condition associated with the water storage tank. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a fire suppression system installed within a lithium-ion battery container according to one embodiment of the present invention; 
         FIG.  2    is a side elevation view of the fire suppression system illustrating the water-delivery conduit network; 
         FIG.  3   a    is a close-up view of the fire suppression system enclosure containing the water storage tank and propellant tank, and of a portion of the protected battery container; 
         FIG.  3   b    is a close-up view of the protected battery container and water-delivery conduit network having nozzles installed corresponding with individual battery modules; and 
         FIG.  4    is a schematic side view illustration of a battery rack containing battery modules and the water delivery conduit with nozzles for delivering water to each module. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While the drawings do not necessarily provide exact dimensions or tolerances for the illustrated components or structures, the drawings are to scale with respect to the relationships between the components of the structures illustrated in the drawings. 
     Turning now to  FIG.  1   , a fire suppression system  10  for protecting a battery container  12  is shown. In one or more embodiments, the battery container  12  may comprise an enclosed structure  14  inside of which a plurality of battery modules  16  are located. Enclosed structure  14  may be any suitable enclosure, such as a stand-alone building, a room within a building, and a mobile container (e.g., a shipping container). 
       FIG.  6    depicts an exemplary battery rack assembly  18  comprising a plurality of battery modules  16  installed therein. The rack assembly  18  can be configured with ducts or channels  20  to facilitate cooling or venting of the battery modules  16  as indicated by the arrows. Each battery module  16  comprises a plurality of individual battery cells stacked together. The battery cells can be of any chemistry (preferably lithium ion) or configuration, such as cylindrical or prismatic. 
     Returning to  FIG.  1   , the battery container  12  includes one or more fans  22  installed therein. One function of fans  22  is to provide ventilation within battery container  12 . In particular, fans  22  are configured to withdraw vapors or gases from within the enclosed structure  14  and direct them to a location outside of the enclosed structure. The placement of fans  22  as depicted in  FIG.  1    is merely exemplary and other designs and configurations are possible without departing from the scope of the present invention. In addition, duct work, not shown, can be provided to direct the gases to a safe venting location. 
     Fire suppression system  10  comprises at least one water storage tank  24  and at least one propellant tank  26  that is connected to storage tank  24  via conduit  28 . It is noted that conduit  28  is only illustrated schematically and that various controls and valves may be present as needed, especially if multiple tanks  24  and/or  28  are present. The water storage tank  24  is configured to store an amount of water, under pressure supplied by a pressurized gas from propellant tank  26 , that is sufficient to provide a flow of water to one or more portions of the enclosed structure  14  for a predetermined period of time. This functionality is discussed in further detail below. The pressurized gas within propellant tank  26  is preferably an inert gas, such as nitrogen or carbon dioxide; however, any inert gas that is without a component that could serve as an oxidizing agent for a fire, especially a battery fire, can be used. 
     In one or more embodiments, water storage tank  24  and propellant tank  26  are located within an enclosure  30  that is separate from battery container  12 . For example, enclosure  30  may be located outdoors or housed in a different building that is remote from battery container  12 . A climate control unit  32  may be installed within enclosure  30   to provide heating or cooling as needed to maintain a desired operational temperature within the enclosure. 
     Fire suppression system  20  also comprises a controller  52  that is coupled to the water storage tank  24 , and preferably to a switch assembly  34  (wired connections not shown) attached to the tank  24 . The controller  52  is also connected with the one or more fans  22  located in battery container  12  and configured to actuate fans  22  upon receiving a signal representing an operational condition associated with the water storage tank, preferably from the switch assembly  34 . Controller  52  may comprise an addressable or conventional control panel, such as a digital, peer-to-peer, bi-directional communication system available under the name CHEETAH Xi by Fike Corporation, Blue Springs, Missouri. 
     In certain embodiments, controller  52  comprises additional functionality beyond detecting water storage tank operational conditions and fan control. For example, the controller  52  can use various technologies to detect smoke, flame, or off gases generated by batteries experiencing a thermal event. Smoke detection can be achieved through use of photo-electric smoke detectors, or air sampling smoke detectors, such as the VESDA detectors by Xtralis. Thermal or heat detection can be achieved through monitoring of the sprinkler heads, use of heat detectors, linear heat detection cables, fiber optic linear heat detection cables, and thermal video analytic imaging. Gas detection can be achieved through the use of stand-alone gas detectors such as hydrogen detectors (available from Honeywell Analytics), in rack gas detection (LI-ION TAMER by Xtralis), and smoke detectors with in-line SCL gas sensor for hydrogen or carbon monoxide detection (available from Xtralis). Controller  52  can also provide integration to building management systems or a programable logic controller (PLC) via gateway to provide messaging from the fire panel. Controller  52  can also be configured to shut down charging circuits of batteries upon detection of a thermal event. Controller  52  can be configured to provide communication a central station or facility manager via a communicator and/or computer graphics workstation. Controller  52  can also activate local notification systems such as horns, bells, and strobes. 
     As can be seen in  FIG.  3   a   , water storage tank  24  comprises a switch assembly  34  that is configured to detect a condition associated with the water level within the storage tank and communicate that condition to controller  52 . Switch assembly  34  can be configured to detect an absolute water level within storage tank  24 , flow of water out of storage tank  24 , or otherwise a change in the amount of water present within storage tank  24 . As illustrated, switch assembly  34  comprises a float switch located within storage tank  24 . A float  36  is slidably received on rod  38  and a water level within the tank can be detected, and optionally compared with an earlier water level measurement to determine whether water is flowing out of the tank. Other types of switches and sensor arrangements can be employed without departing from the scope of the present invention, such as reed switches, magnetic switches, and flow meters. In addition, switch assembly  34  may comprise more than one switch and/or multiple types of switches. 
     The water storage tank  24  is connected to a conduit network  40  that extends into battery container  12 . The conduit network  40  generally comprises one or more supply pipes  42  that connect the water storage tank  24  with a distribution header  44  located within the battery container  12 . The distribution header  44  may be equipped with an outlet section  45  for coupling of the network with headers located in additional battery containers. A plurality of water delivery pipes  46  extend from header  44  and connect header  44  with a collector pipe  48 . As depicted in the Figures, one water delivery pipe  46  is provided for each rack assembly  18 , although it is within the scope of the present invention for conduit network  40  to be configured differently. 
     Each delivery pipe  46  comprises a plurality of water nozzles or heads  50  distributed along the length thereof. In one or more embodiments, at least one nozzle  50  is provided for each battery module located within rack assembly  18 , although this need not always be the case depending upon how rack assembly  18  is configured. Nozzles  50  may comprise any kind of fire suppression system nozzle or head known to those in the art. However, in one or more embodiments, the nozzles  50  are passive and do not require input of any other sensor or device in order to activate. Exemplary nozzles  50  include those comprising a heat-sensitive element, such as a glass bulb or fusible link, that breaks or is sufficiently distorted upon exposure to elevated temperature conditions, typically between 70-95° C., which then permits water to flow through the nozzle. Thus, nozzles  50  may be configured to release a flow of water upon exposure to a nearby elevated temperature condition that is associated with a thermal event occurring within a battery module  16 . 
     Optionally, fire suppression system  10  can further comprise an inert agent fire suppression system  54  that works alongside the water delivery system. Inert suppression system  54  comprises one or more inert suppressant tanks  56  connected to a distribution conduit  58 , which comprises one or more nozzles  60  configured to disperse the suppressant into the protected area within battery container  12 . Inert agent fire suppressants are known in the art and can include inert gas agents (e.g., nitrogen, argon, carbon dioxide, and mixtures thereof), NOVEC 1230, and FM-200. The inert agent fire suppression system  54  is configured to deprive an environment that is subject to or at risk of developing a fire of oxygen or so that combustion of materials within the environment cannot be sustained, or to interfere with the ability of oxygen present within the environment to combust with the fuel source. Suppression system  54  may be actuated through direct sensing of a fire hazard within the protected space using, for example temperature sensors, hydrogen detectors, or smoke detectors. Suppression system  54  may also be activated by the release of water from fire suppression system  10 , and thus also be under the operational control of controller  52 . 
     In one or more embodiments, the battery container  12  comprises a first compartment  62  in which the inert agent tank  56  is located, and a second compartment  64  in which the battery rack assemblies  18  and battery modules  16  are located. The at least one nozzle  60  is installed within the second compartment  64  and configured to introduce the inert suppressing agent into the second compartment alone. Although, it is certain possible for the inert suppressing agent to also be introduced into the first compartment  62  should such be deemed a necessary design requirement. In certain embodiments, the inert agent fire suppression system  54  is not intended to directly suppress a fire or thermal event arising within the battery module itself, although such can be a secondary effect of such a system. Rather, the inert agent system  54  has a primary function of preventing spread of a battery fire to ancillary components within the battery container  12 , such as circuit boards, wire jackets, and insulation material. 
     As noted above, fire suppression system  10  can be configured to protect a plurality of battery containers  12 . However, in one embodiment, the inert agent fire suppression system  54  is configured to protect a single battery container  12 . Thus, each battery container  12  may be equipped with its own inert agent fire suppression system  54 , even though it shares fire suppression system  10  with multiple containers. 
     During operation of fire suppression system  10 , water storage tank  24  can be filled to the desired level for the given application. In addition, propellant tank  26  can be charged with pressurized gas sufficient for delivery of the water contained within tank  24 . In one or more embodiments, the water storage tank and the propellant tank are configured to deliver a flow of water to the one or more battery modules affected by a thermal event for at least 10, 15, 20, 25, or 30 minutes from initiation of the water flow. In particular embodiments, the water storage tank  24  is configured to hold at least 100 gallons of water, or from about 100 to about 500 gallons of water, and propellant tank is charged with at least 1000 psi, or from about 1000 to about 3500 psi, of the pressurized gas. 
     In one or more embodiments, the conduit network  40  is pre-charged with water under pressure provided by the pressurized gas from the propellant tank  26  so that the flow of water can be immediately delivered to the battery module experiencing a thermal event. Thus, all gas contained within the conduit network can be bled from the system through conduit outlet  66 , which may be equipped with a valve (not shown). 
     Once the system is charged, it stands ready for deployment when a thermal event is occurs, which triggers opening of one or more of the nozzles  50 . The opening of one or more nozzles causes water to flow out of water storage tank  24  and into the conduit network  40 . In one embodiment, controller  52  then may receive a signal from switch assembly  34  indicating the release of water from the storage tank  24 . This signal may cause controller  52  to commence a timer programmed to countdown a predetermined length of time. In certain embodiments, the timer is set to count down a period of at least 5, 10, 15, 20, or 25 minutes, upon elapse of which controller  52  actuates one or more of fans  22  to ventilate enclosed structure  14 . 
     In an alternate embodiment, once the flow of water from storage tank  24  into conduit network  40  begins, controller  52  may be alerted by take no immediate action. In such embodiment, the switch assembly  34  monitors the water level within storage tank  24  and sends signals to controller  52  indicating the water level. Controller  52  is preprogramed to delay actuation of fans  22  until a predetermined water level is reached. Once the predetermined water level is reached, controller  52  actuates one or more of fans  22  to ventilate enclosed structure  14 . 
     In one or more embodiments, the flow of water is directed out of the one or more nozzles  50 , into the rack assembly  18  and around one or more battery modules  16  that are experiencing the fire or thermal event. The flow of water is preferably sufficient to contain the thermal event within the affected battery module  16  and retard and/or prevent the propagation of the thermal even to adjacent battery modules. Once commenced, the flow of water continues until water storage tank  24  is empty, or the flow is cutoff via operator intervention, such as closing a valve within the conduit network  40 . 
     If the battery container  12  is so equipped, the inert agent fire suppression system  54  can be activated simultaneous with fire suppression system  10 , or whenever conditions warrant its activation. Because fans  22  are purposefully kept from being operated until a predetermined amount of water from storage tank  24  has been delivered, ventilation of the enclosed structure  14  is delayed, which keeps the inert fire suppressant within the enclosed structure for as long as practical and prevents the system from actively drawing in fresh air into the battery container  12 , which could worsen the fire or thermal event. 
     It is intended that the flow of water to the affected battery module(s)  16  last for at least as long as it should take first responders to arrive on the scene to take further steps to control the fire hazard, including attaching an external water supply to conduit network  40  so that the flow of water can be continued even after the supply within tank  24  has been exhausted. However, the time for first responders to arrive can be dependent upon factors outside the control of the operators of the battery container  12 . Therefore, it is possible that storage tank  24  may become depleted before responders arrive. As the level of water within the storage tank  24  draws down, the mission of fire suppression system  10  can change from that of fire suppression and anti-propagation to that of explosion risk mitigation. Lithium-ion battery fires and thermal events can result in the generation of explosive and toxic gases such as hydrogen, carbon dioxide, carbon monoxide, and hydrogen fluoride. A buildup of these gases within the battery container  12  can result in conditions that are quite hazardous to the first responders once they arrive on scene. Therefore, fire suppression system  10  actuates fans  22  to vent or exhaust the gases within container  12  to prevent or mitigate the dangers to first responders. Fans  22  can continue to ventilate container  12  until the first responder or container operator deems it safe to discontinue their usage. 
     System  10  can be further configured so that actuation of fans  22  is a failsafe operation. For example, if a thermal event is detected by a sensor, such as a hydrogen detector sensing the presence of hydrogen off gas from a battery cell, controller  52  can send a signal to (i) shut down charging circuits of the affected battery modules and/or adjacent modules, and (ii) activate fans  22  to keep the container atmosphere from reaching a lower explosive limit. However, should the ventilation fans  22  not be activated in response to the initial detection of the thermal event, controller  52  is configured to receive a signal representative of a second supervised or lower level of water within tank  24  and activate the ventilation fans  22 .