Patent Application
20170159933
The disclosed technology relates generally to detection and/or treatment of combustible gas within dwellings.
Flammable gases, such as carbon monoxide can be toxic, (carbon monoxide is toxic at concentrations (0.4%) below the flammability limit (12.5%)) as well as cause destruction when combusted. Other combustible gases, such as methane, act as an aphyxiant. Fires in enclosed containers and rooms can produce sufficient pressure to burst walls, scattering burning fuel over a large area with potentially catastrophic results. Tremendous motivation thus results to reduce the flammability of fuels in enclosed areas. Where the fuel is toxic and is present in living spaces, reduction of flammability is insufficient and fuel concentrations must be reduced below harmful levels for breathability.
In dwellings (home, office, or other buildings where people live, work, or enter) carbon monoxide, a by-product of combustion, is a consistent worry. The gas is present whenever fuel is burned, produced gas or oil furnaces, gas refrigerators, gas clothes dryers, gas ranges, gas water heaters or space heaters, fireplaces, charcoal grills, and wood burning stoves. Fumes from automobiles and gas-powered lawn mowers also contain carbon monoxide and can enter a home through walls or doorways if an engine is left running in an attached garage.
Ignition and flame propagation is only possible when three conditions are present: fuel, oxygen (oxidizer) and an ignition source. Experience tells us that relying on eliminating all ignition sources, as was attempted with the LZ 129 Hindenburg and TWA Flight 800, can have disastrous consequences. The fuel and oxidizer must be in a range of concentration ratios to burn. If there is too little oxygen and too much fuel, or vice versa, or both are too low, then the mixture cannot support combustion. Thus, if either the oxygen concentration, fuel concentration or both can be sufficiently reduced, then even an open flame will not ignite the mixture.
Oxygen and fuel concentrations are both decreased by controlled combustion, either at normal flame temperatures or at catalytically reduced temperatures. The return of products of combustion to the system further dilutes the fuel and oxygen concentrations.
What is needed is a way to not only detect the presence of harmful, dangerous, and/or combustible gases, but also to remediate (remove or render non-harmful and non-dangerous) the gas.
A “room” for purposes of this disclosure is a space enclosed by a floor, walls, and ceiling designed for human entrance there-in (at least 1 meter high, 1 meter wide, and 1 meter long), with only a minority (less than 50%) or minimal (less than 1%, 5%, 10%, or 15%) of the floor, walls, and ceiling having openings to other spaces. The method proceeds by maintaining a first flow rate of ambient air from the room into an interior of a device.
“Interior” is defined as having walls defining it's space separate from outside of its space, with portals or passageways from the space to the outside being minimal (less than 1%, 5%, 10%, or 15%).
One can use one or both of a pilot flame(s) or catalytic converter(s) in embodiments of the disclosed technology.
A method of leak detection (that is, detecting the results of a leak and/or gases produced but not necessarily ‘leaked’) and/or remediation of combustible gas in a room is carried as follows. A pilot flame is maintained within an interior of the device. A first flow rate of ambient air from the room into the interior of the device is maintained. A temperature detection device (e.g. digital or analog thermometer measuring expansion of a liquid, solid, or gas) is used to detect a rise in temperature caused by an increase in heat release as the pilot flame increasing in size. Thus, the temperature detection device is inside or on the exterior of the device. The pilot flame increases in size due to combustion of gases in the ambient air. In an alternative embodiment, one can use a carbon monoxide or other noxious and flammable gas detector. In either case, based on the detecting, the flow rate is then changed to a second flow rate above the first flow rate (the rate of flow is increased). The combustible gas is then more quickly combusted within the interior of the device and a resultant gaseous product is exhausted.
The exhausting can be back in the room, such as through a room air filter. A further step, while carrying out the step of burning, can be carried out to detect oxygen levels within the interior of the device. Flow rate can be adjusted based on the oxygen levels to provide a desired threshold for optimal combustion within the interior of the device. A further step of detecting a rise in pressure and oxygen concentration of air passing through the device can be carried out, while lowering the flow rate based on a rise in pressure.
Simultaneous to the burning, at least some of the gas is rendered inert by a catalytic converter in an embodiment of the disclosed technology. After the second flow rate is achieved for a pre-determined period of time (e.g. 1 minutes, 5 minutes, 10 minutes, 30 minutes, or an hour) and the temperature remains above a pre-determined amount (e.g. a temperature within 5, 10, or 20 degrees Celsius above that of ambient air) within the device, a further step of introducing cooling water into the device can be carried out.
The device described above is, as follows, in embodiments of the disclosed technology. The device remediates gas in a room with an inlet open to ambient air within a room and a first interior space having at least one sensor therein. An outlet is also open to the outside of the device. A first flame arrestor quench screen is situated between the first interior space and an impeller. A second flame arrestor quench screen is situated between a combustion chamber and the outlet, the impeller causing air flow in a direction from the inlet to the outlet. For added safety, flame arrestors cover all of the inlet and outlet ports of the device. A pilot flame is situated within the combustion chamber. (A “chamber” is defined as an “interior space” within another interior space where the interior spaces can share zero, one, two, or three walls and the chamber lacks portals opening directly between the chamber and the outside of the device.)
The outlet can be open to the ambient air within the room. The at least one sensor can be at least two of a pressure sensor, temperature sensor, and oxygen concentration sensor. A catalytic converter and/or a pilot flame can be situated downstream from the impeller. A pressure release valve can also be situated downstream from the impeller.
Upon detection of one of an increase in pressure, an increase in temperature, or a decrease in oxygen concentration by a respective sensor, the rotation rate of the impeller is increased. A cold water inlet, in embodiments of the disclosed technology, is opened upon detection of a temperature above a pre-defined threshold for a pre-defined period of time. The water absorbs some of the heat of combustion and exist the device for safe disposal to a drain or exterior space. The detection spoken of is based on output from the temperature sensor.
Embodiments described with reference to the device of the disclosed technology are equally applicable to methods of use thereof.
“Substantially” and “substantially shown,” for purposes of this specification, are defined as “at least 90%,” or as otherwise indicated. Any device may “comprise” or “consist of” the devices mentioned there-in, as limited by the claims.
It should be understood that the use of “and/or” is defined inclusively such that the term “a and/or b” should be read to include the sets: “a and b,” “a or b,” “a,” “b.”
A leak detection and remediation method and device for combustible gas in a room is disclosed. An inlet and outlet opening between ambient room air and the interior of a device are used with several sensors. Flame arrestor quench screens are used to control a fire within a chamber having an impeller causing air flow. A pilot flame situated within the combustion chamber burns combustible gas while temperature, pressure, and oxygen sensor devices are used to modify air flow as necessary for optimum combustion within the device.
Embodiments of the technology will become clearer in view of the following description of the figures.
Air from a room and/or from outside the remediation device is drawn into the inlet 11 in Zone 1 by the suction produced by impeller 31. In Zone 1, the temperature of the gas is approximately equal to that in the living space, but the pressure is reduced due to the suction. The gas passes through a flame arrestor quench screen 13 before passing through a housing 21 which can be insulated from fire (non-flammable) and blast resistant. The air then enters into Zone 2 (the arrows in outline indicate direction of flow). A reusable pressure relief valve and outlet system 201 are used in embodiments of the disclosed technology to prevent pressure inside the device from becoming too high.
In Zone 2, the pressure remains reduced due to the suction. The gas is analyzed for temperature using a temperature sensing device (thermocouple) 26, pressure using a pressure sensing device (piezoelectric pressure transducer) 27, and oxygen concentration using an oxygen concentration measurement device 28 before passing through another flame arrestor quench screen 29 to Zone 3.
Zone 3 begins with variable-speed electric impeller 31 that draws in the gas. In Zone 3, downstream of impeller 31, the pressure and temperature are greater than the room pressure and temperature respectively in embodiments of the disclosed technology. Temperature sensors 32 and pressure sensors 33 monitor the unburned gas. Some of the gas, in embodiments of the disclosed technology, proceeds to an electrically heated catalytic converter 35, while the remainder, such as is sufficient for wall-cooling, proceeds through a bypass 36. In the event of excessive pressure build up in Zone 3, reusable pressure relief valve and outlet system 37 vents excess gas outside the system. The gases recombine in Zone 4.
Zone 4 comprises or contains the partially combusted gases so the gas temperature is the hottest in the system and is typically greater than 100° C. to avoid water condensation. Temperature, pressure and oxygen content are monitored by respective sensors 41, 42 and 43 respectively. Pressure in Zones 3 and 4 are controlled by balancing the gas inflow driven by impeller 31 and electrically-controlled throttle valve 45. In the event of excessive pressure build up in Zone 4, reusable pressure relief valve and outlet system 44 vents excess gas outside the system. The gas then passes through flame arrestor quench screen 46 to Zone 5.
The gas, now comprises nitrogen and a higher than atmospheric and/or room level of carbon dioxide, as well as a lower than atmospheric and/or room level of oxygen passes out of the remediation device through flame arrestor quench screen 501 and through outlet 502 back to the room or to the outside.
A temperature sensor (e.g. thermometer) is used in step 230 to determine if there is a temperature rise inside, on the inner surface of, or the outer surface of the remediation device 200. In other embodiments, the temperature is measured within the room, being the ambient room temperature. When the temperature rises above a pre-defined threshold, such as above 100, 120, or 150 degrees Celsius when measuring areas outside of the Zone where the pilot flame is located. In other embodiments, the temperature threshold rise is defined based on a baseline temperature measured near the pilot flame, such as a thermometer in the same Zone. In such a case, the temperature rise in step 230 is 10 degrees, 20 degrees, or 40 degrees Celsius over the baseline set by the pilot flame alone. The temperature rise in any of these embodiments is due to an increase in heat release as the pilot flame increases in size due to the incineration of combustible gases entering into the remediation device. If no temperature rise happens, then step 210 and 220 are repeated cyclically until this situation changes and the temperature rises in step 230.
Once the temperature rise is detected, the rise being above any of the thresholds defined in the previous paragraph, the flow rate of air into the remediation device is increased in step 240. This is in order to increase the rate at which the gas is combusted, and create a safe atmosphere of the ambient air 110 in the room 100. For example, the first flow rate can be 25 standard cubic feet per minute (SCFM) for a room with 1000 cubic feet (or within 10% of this size). The increased flow rate can be 250 SCFM. A 24 square inch opening (such as 2″×12″ rectangular gas inlet opening or 2.75″ radius circular inlet) provides adequate gas sampling with minimal noise at the low flow rate and satisfactory performance even for higher flow rates. The maximum heat release in the event of a methane leak occurs if the mixture is 9.5% methane and 90.5% air (19% O2 and 71.5% of N2 and trace gases). Combusting 250 SCFM results in a lower heating rate (based on the lower heating value) of 380 Kilowatts.
In step 250, gas is burned within the device, referring to combustible gas beyond that which is supplied to support the pilot flame. This is described further with reference to
For purposes of this disclosure, central air is defined as devices and methods of structural cooling of a building (or, at least, multiple rooms) in which a centralized unit cools or heats air before circulating it throughout the multiple rooms or building. This is in direct contrast with systems that rely on individual units in an individual room. The air which is heated or cooled by a central air system is usually transported to various rooms by duct work.
Further, if the pressure is above a pre-defined threshold in step 272, the flow rate of the air into the remediation device 200 can be adjusted. Pressure too high is dangerous and can cause malfunction or explosions. Therefore, pressure overrides oxygen level bounds (e.g. step 272 overrides step 270), and can cause a lowering of the air flow rate in step 255 to decrease the rate of combustion. When the pressure is back to safe levels or further below same, the air flow rate can again be increased.
Still further, it is desired in some embodiments of the disclosed technology to ensure that combustion lasts only for a certain amount of time such as 10 minutes, 15 minutes, 30 minutes, 60 minutes, or 6 hours. Allowing combustion to proceed longer might be the result of unsafe conditions for which operation of the device and the flame associated therewith will only produce more danger when the goal of the device is to reduce danger. Thus, in a situation where one must remediate for too long a period of time or at too high of temperatures or at too high of pressures (for a period of time) can be dangerous. When such conditions are reached, then water is inputted into the device 200 in step 280 from a water source 290. The pilot light is obviously also shut off and gas supply is reduced to zero. In this manner, the device stops functioning as a safety precaution. Pressure release or the ceasing of the pilot light takes place, in embodiments, at 75 psig or less. The temperature of a methane-air flame can exceeds 3500° F., but sufficient cooling will insure no other part of the device exceeds 1800° F. In the embodiment using a catalytic converter, operating temperatures range from 400 to 1800° F. Those portions of the device expected to be exposed to elevated temperatures are manufactured of materials capable of withstanding such heat. Similarly, those portions of the device expected to be exposed to elevated pressures are manufactured of materials capable of withstanding such forces.
While the disclosed technology has been taught with specific reference to the above embodiments, a person having ordinary skill in the art will recognize that changes can be made in form and detail without departing from the spirit and the scope of the disclosed technology. The described embodiments are to be considered in all respects only as illustrative and not restrictive. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. Combinations of any of the methods, systems, and devices described hereinabove are also contemplated and within the scope of the invention.
