The present invention relates to a system for obtaining accurate and representative emissions samples, such as emission samples from power generating facilities. A particular embodiment of the invention comprises a system for collecting representative samples of fly ash produced by coal combustion.
Coal-fired power plants, which utilize coal combustion to produce electricity, are a major source of energy today. In coal-fired plants, pulverized coal is burned in a boiler, and the heat generated from the combustion heats water, which produces steam. The steam flows to a turbine that spins a generator to produce electricity. A byproduct of the coal combustion process includes air borne emissions, such as fly ash. Fly ash is typically a fine powdery material, the composition of which can vary depending on the composition of the coal being burned, and the efficiency of the processes and equipment utilized in the coal-fired plant.
Coal combustion emissions, such as fly ash, often contains unwanted pollutants, and therefore can be subject to government environmental regulations. Violations of such environmental laws can result in significant financial penalties for a power generating facility, as well as hurt the relationship between the power facility and the people of the surrounding communities. As such, it is important for power plants to accurately monitor the emissions it is generating, including collecting and analyzing samples of fly ash produced by combustion of coal and other fossil fuels. Collection of fly ash samples has typically been done by plant workers manually collecting samples at the outlet duct. Such manual collection methods are typically work intensive and time consuming for plant workers. In addition, such manual collection methods often garner unrepresentative samples that do not accurately reflect the overall composition of the vast majority of fly ash being emitted from the plant.
Therefore, one object of the present invention is to provide a system for collecting representative samples of power plant emissions. Another object of the invention is is to provide an automated system for collecting fly ash samples that can minimize the amount of worker time needed to collect fly ash samples.
These and other objects of the invention can be achieved in the various embodiments of the invention described below. In one embodiment of the invention, an apparatus for collecting emission samples comprises a plurality of elongate tubes, each of the plurality of tubes including an opening formed therein for positioning in an emission producing facility, and the openings reside at varying spaced-apart points in the facility. Suction means are operatively connected to the plurality of tubes to suction gas in the facility through the openings and into the tubes, so that emissions carried in the suctioned gas are drawn into the plurality of tubes. A collection container is operatively connected to the plurality of tubes and the suction means, such that the emissions are suctioned into the tubes and deposited into the collection container.
According to another embodiment of the invention, the plurality of elongate tubes is comprised of at least four elongate tubes of varying length, and the opening of each tube is proximate a first terminal end of each respective tube, such that the tube openings reside at varying depths when positioned in the facility.
According to another embodiment of the invention, the suction means comprises an aspirator operatively connected to the plurality of elongate tubes, wherein the aspirator suctions gas in the facility through the openings of the tubes and into the tubes.
According to another embodiment of the invention, the emissions producing facility is a power plant, and a pipe is connected to the aspirator, such that the pipe supplies compressed air from the power plant, and further comprising a valve operatively connected to the pipe and the aspirator for controlling the flow of the compressed air to the aspirator.
According to another embodiment of the invention, the emissions producing facility can be a power plant having an outlet duct, and the tube openings are positioned in the outlet duct. Flue gas flows in the outlet duct along an axis that is substantially parallel to the outlet duct, and the tube openings are positioned to face the flow of flue gas.
According to another embodiment of the invention, the elongate tubes are adapted for being positioned through a top surface of the outlet duct, and each elongate tube includes a nozzle residing substantially parallel to the outlet duct that defines the tube opening, such that the tube openings face the flow of flue gas.
According to another embodiment of the invention, there are means for measuring and controlling the flow of gas in each of the elongate tubes, so that a substantially isokinetic sample of gas from the facility can be collected in each tube.
According to another embodiment of the invention, a substantially equal portion of emissions can be collected in each of the elongate tubes.
According to another embodiment of the invention, the means for measuring and controlling the flow of gas comprises an orifice and a control valve operatively connected to each of the elongate tubes.
According to another embodiment of the invention, there are a plurality of thermocouples, and each of the thermocouples is operatively connected to one of the elongated tubes and positioned proximate the tube opening.
According to another embodiment of the invention, there are a plurality of gas sampling ports, and each of the elongated tubes is in communication with one of the plurality of gas sample ports, such that a sample of gas flowing through each of the tubes can be obtained.
According to another embodiment of the invention, the emissions comprise fly ash produced by combustion of fossil fuel.
According to another embodiment of the invention, the sampling apparatus includes a cyclone separator having a first opening in communication with the plurality of elongate tubes, a second opening in communication with the suction means, and a third opening in communication with the collection container. The separator receives the gas suctioned through the tubes and creates a cyclone of the suctioned gas, such that the fly ash in the suctioned gas is separated from the gas and deposited into the collection container.
According to another embodiment of the invention, a filter is operatively connected intermediate the suction means and the cyclone separator to capture fly ash escaping the second opening of the cyclone separator while the suction means is operative. The filter is positioned above the cyclone separator, and the cyclone separator is positioned above the collection container, so that the fly ash captured on the filter returns to the cyclone separator and the collection container when the suction means is turned off.
According to another embodiment of the invention, the collection container is removably connected to the cyclone separator proximate the third opening, so that fly ash collected in the collection container can be removed and transported.
According to another embodiment of the invention, an apparatus for collecting samples of fly ash produced in an emission producing facility comprises at least one probe comprising a plurality of elongate tubes. Each of the plurality of tubes include an opening formed therein for positioning in an outlet duct of the facility, and the openings reside at varying depths of the outlet duct when positioned in the outlet duct. An aspirator is operatively connected to the plurality of tubes to suction flue gas in the facility through the openings and into the tubes, so that fly ash present in the suctioned flue gas is drawn into at least one of the plurality of tubes. A collection container is operatively connected to the plurality of tubes and the aspirator, such that the fly ash present in the suctioned flue gas is deposited into the collection container.
According to another embodiment of the invention, the probe includes at least four elongate tubes of varying length, and the opening of each tube is proximate a first terminal end of each respective tube, so that the tube openings of each probe reside at varying depths when positioned in the outlet duct of the emission producing facility.
According to another embodiment of the invention, the probe includes a cyclone separator having a first opening operatively connected to the plurality of elongate tubes, a second opening operatively connected to the aspirator, and a third opening operatively connected to the collection container. The cyclone separator receives the flue gas suctioned through the tubes and creates a cyclone of the suctioned flue gas, so that the fly ash in the suction gas is separated from the flue gas and deposited into the collection container.
According to another embodiment of the invention, a method for collecting samples of fly ash emissions from an emission producing facility includes providing an apparatus comprising a plurality of elongate tubes of varying length, each tube having an opening proximate a first terminal end of the tube, an aspirator operatively connected to the plurality of tubes, and a collection container operatively connected to the plurality of tubes and the aspirator. At least a portion of each of the plurality of elongate tubes is positioned in an outlet duct of the facility, such that the tube openings reside within the outlet duct. The aspirator is turned on so that flue gas and fly ash present in the flue gas is suctioned in through the tube openings and into the plurality of tubes. The flow of the flue gas in each of the tubes is measured and controlled so that a substantially isokinetic sample of gas from the outlet duct can be collected in each tube, and the fly ash is deposited into the collection container.
According to another embodiment of the invention, the collection container is removed from the apparatus after the suctioned fly ash has been deposited into the collection container.
Objects of the invention have been set forth above. Further objects and advantages of the present invention may become apparent as the description of the invention proceeds when taken in conjunction with the following drawings, in which:
Referring now to the drawings, in which like numerals represent like components throughout, a multi-point emission sampling system according to a preferred embodiment of the invention for use in an emission producing facility is illustrated in
As shown in
As shown in
As shown in
The system 10 includes suction means for suctioning gas into the tubes 12, 14, 16, 18 through the openings 32, 34, 36, 38, and up the tubes 12, 14, 16, 18, such as an aspirator 50, shown in
The system 10 includes means for controlling the flow of gas in each of the elongate tubes 12, 14, 16, 18 of each probe 11. For example, as shown in
The tubes 12, 14, 16, 18 can also include gas sampling ports 64 that allow for obtaining a sample of the gas flowing through each tube 12, 14, 16, 18. The system 10 can also include thermocouples 66 operatively connected to each tube 12, 14, 16, 18 for obtaining data regarding the temperature in the outlet duct 110. The sensors of the thermocouples 66 are preferably positioned proximate the openings 32, 34, 36, 38 of the tubes 12, 14, 16, 18.
In a preferred method of using the multi-point emission sampling system 10, the system 10 can be used to obtain fly ash samples from the coal-fired power plant 100. As shown in
As shown in
Flue gas flows through the outlet duct 110 to exit the power plant 100. As the flue gas flows in a stream that is substantially parallel to the outlet duct 110, the aspirator 50 suctions at least some of the exiting flue gas “G” into the tube openings 32, 34, 36, 38 of the probes 11, as shown in
As shown in
The suctioned flue gas flows up the tubes 12, 14, 16, 18. Because each tube 12, 14, 16, 18 includes an orifice 60 and a control valve 62 installed, the gas flow in each tube 12, 14, 16, 18 can be individually measured and controlled. As such, the gas flow through each tube opening 32, 34, 36, 38 can be controlled so that it is substantially equal to the flow of gas in the outlet duct 110, and a substantially isokinetic sample of flue gas can be obtained from each tube 12, 14, 16, 18. Also, a substantially equal amount of flue gas can be obtained from each tube 12, 14, 16, 18, and the tubes 12, 14, 16, 18 can be blown back if pluggage should occur.
As shown in
The separated fly ash “A” is held in the collection container 44, thereby providing an accurate and representative sampling of the fly ash “A” being produced and emitted from the power plant 100. As noted above, the collection container 44 can be removable from the separator 40. Accordingly, the container 44 holding the fly ash sample can be removed, such as by unscrewing complementary threads, and transported away from the system 10 to a remote destination, such as a laboratory for analysis. Laboratory analysis of the fly ash sample can determine the presence of multiple pollutants, including dioxin and heavy metals such as lead and mercury. Also, the fly ash sample can be analyzed for particle sizing to determine pulverizer performance.
It should be noted that while the multi-point emission sampling system 10 is described above as being used in the outlet duct 110 of a power plant 100, the system 10 can be used in other ways and environments. For example, the system 10 can be utilized at the precipitator inlet in order to collect a fly ash sample for analysis in order to determine additives and dosages required for precipitator performance. The system 10 can also be utilized as a tool for collecting ash, gas and temperature measurements to determine flue gas due point, in order to avoid ash collector and back end corrosion. Furthermore, the system 10 can be utilized for combustion tuning and optimization. The system 10 can be used in a variety of dust laden work environments, such as coal fired boilers, oil fired boilers, wood fired boilers, kilns and cement manufacturing facilities, to collect representative emission samples. The emission samples can be comprised of particles ranging in size from one micron to one-eighth of an inch.
Because it is automated, the multi-point emission sampling system 10 can minimize the labor required to collect an accurate fly ash sample. The system 10 is capable of collecting individual samples per probe 11 and/or per tube opening 12, 14, 16, 18 to determine the level of carbon in the fly ash or the limiting oxygen index (LOI) across the outlet duct 110 to assist with combustion and performance tuning. Preferably, the system 10 can operate in a temperature range of ambient to 800 degrees Fahrenheit, and can operate in a duct static pressure range from −60″ w.c. to 60″ w.c. The system 10 can be used to collect samples of solid particles from nearly zero to 525 grains/ft3 (equivalent to one pound of ash per pound of flue gas at standard conditions), but sampling times can vary.
A multi-point emission sampling system, and methods of using same are described above. Various details of the invention may be changed without departing from its scope. The foregoing description of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation—the invention being defined by the following claims and equivalents thereof.