Patent Application
20130228073
The present disclosure generally relates to methods and apparatuses for scrubbing diesel exhaust gases, and more particularly relates to scrubbing methods and apparatuses that first cool the exhaust gases in a scrubbing vessel.
As is well known, the combustion of hydrocarbon-containing fuels, such as diesel, results in exhaust gases containing sulfur compounds including sulfur dioxide. Further, the presence of sulfur dioxide in the atmosphere has been linked to the formation of acid rain. Due to the ecological damage resulting from acid rain, various government standards have been established to reduce or prevent the emission of sulfur dioxide.
While land-based combustion plants have utilized a variety of methods to reduce or eliminate the emission of sulfur dioxide, many of these methods are inappropriate for shipboard plants. For instance, land-based scrubbing apparatuses largely can be designed and implemented without, or with little, concern regarding footprint size. However, there is an overriding interest in minimizing the footprint of ship-based scrubbers and other power and exhaust systems. Further, there is an interest in optimizing fuel and exhaust processing systems on ships.
In light of the above, the present disclosure provides a method and apparatus for scrubbing exhaust gases on a ship with a reduced footprint. Further, the present disclosure provides a method and apparatus for quenching exhaust gases to saturation temperatures to improve mass transfer during scrubbing. Also, the present disclosure provides a method and apparatus for scrubbing cooled exhaust gases to reduce the cost of downstream equipment. Furthermore, the present disclosure provides a method and apparatus for scrubbing exhaust gases that exhibits a reduced pressure drop on the diesel engine. Alternative or additional features and characteristics of the methods and apparatuses will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.
Methods and apparatuses for scrubbing diesel exhaust gases produced on a ship are provided. In accordance with one exemplary embodiment, a method for scrubbing diesel exhaust gases on a ship includes providing a scrubber vessel formed with a quench zone, a scrubbing zone, and a riser. Water is passed through the scrubbing zone and into the quench zone. The exhaust gases are delivered to the quench zone through the riser and enter the quench zone at a temperature of about 175° C. to about 340° C. The method includes cooling the exhaust gases to a temperature of about 60° C. to about 70° C. in the quench zone by contacting the exhaust gases with the water. The cooled exhaust gases are then scrubbed in the scrubbing zone.
In another embodiment, a method for scrubbing diesel exhaust gases produced on a ship includes flowing the exhaust gases from a diesel engine to a scrubber vessel. The exhaust gases are introduced to a chamber within the scrubber vessel and have a temperature of about 175° C. to about 340° C. Then the exhaust gases are cooled to a temperature of about 60° C. to about 70° C. Thereafter, the cooled exhaust gases are scrubbed.
In accordance with another exemplary embodiment, an apparatus for scrubbing diesel exhaust gases produced on a ship is provided. The apparatus includes a scrubber vessel formed with a quench zone, a scrubbing zone, and a riser. Further, a duct is configured to deliver the exhaust gases through the riser and into the quench zone at a temperature of about 175° C. to about 340° C. The apparatus includes a means for cooling the exhaust gases to about 60° C. to about 70° C. in the quench zone. Also, the apparatus includes a means for scrubbing the cooled exhaust gases in the scrubbing zone.
Exemplary embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:
The following detailed description is merely exemplary in nature and is not intended to limit the methods and apparatuses for scrubbing exhaust gases on a ship as claimed herein. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
As detailed below, the methods and apparatuses for scrubbing exhaust gases on a ship utilize a scrubber vessel that houses both a quench or cooling zone and a scrubbing zone. As a result, the footprint for cooling and scrubbing apparatuses is reduced. Further, the footprint of ducts connecting such apparatuses is eliminated.
In
Referring now to
The scrubber vessel 16 defines a chamber 52. A barrier 54 bounds an inlet zone 56 in the chamber 52 at the bottom end 44 of the vessel 16. Risers 58 pass through the barrier 54 and extend to openings 60 that are positioned in a quench zone 62. While two risers 58 are illustrated, the vessel 16 can be provided with six, eight, or more risers 58 as desired. As shown, the quench zone 62 is bounded by the barrier 54 and a vapor-liquid contact mechanism 64. The exemplary quench zone 62 includes splash or diffusion plates 66. Each plate 66 is positioned at a riser opening 60 to provide a selected flow path to diffuse the flow of exhaust gases 22 into the quench zone 62. Further, the plates 66 block or inhibit falling water drops 68 from entering the risers 58. Typically, any water droplets 68 that enter the risers 58 are atomized and carried back into the quench zone 62 by the flow of exhaust gases 22. The exemplary vessel 16 is further provided with baffles 72 that inhibit movement of any water collected on the barrier 54.
As shown, the vessel 16 is formed with a water outlet 74 adjacent the barrier 54. Water 32 landing on the barrier 54 flows out of the outlet 74 to the secondary basin 18. As a result, water does not rise to the level of the riser openings 60 and does not backflow into the risers 58 toward the engine 14. Such backflow is prevented even in rocking conditions experienced by the ship 12 on rough seas. As noted in
When the exhaust gases 22 enter the quench zone 62, they are typically at a temperature of about 175° C. to about 340° C. (about 350° F. to about 650° F.). Further, the velocity of the exhaust gases 22 from the engine to the vessel 16 is typically in the range of about 2000 feet/minute (ft/min) to about 5000 ft/min. In the quench zone 62, the velocity of the exhaust gases 22 is typically about 2500 ft/min to about 7000 ft/min. The pressure drop of the exhaust gases 22 exiting the diesel engine 14 is typically about 5 inches of water (inH2O) to about 10 inH2O and the pressure drop of the exhaust gases 22 after passing through the plates in the quench zone 62 is about 2 inH2O to about 7 inH2O. Upon impact with the water droplets 68, the exhaust gases atomize the droplets 68 into smaller drops, thereby increasing the surface area of the water. The water cools the exhaust gases 22 to a temperature of about 60° C. to about 70° C. (about 140° F. to about 160° F.), such as about 65° C. (about 150° F.) which is at or near the saturation temperature of the exhaust gases. The water further absorbs sound energy from the exhaust gases 22. In exemplary embodiments, the water removes particulates from the exhaust gases 22.
As shown, the cooled exhaust gases 82 flow from the quench zone 62 into the scrubbing zone 83. The cooled exhaust gases 82 flow in the same direction (upward in
Referring to
Referring back to
While the particular methods and apparatuses for scrubbing diesel exhaust gases on a ship as herein shown and disclosed in detail are fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that they are merely illustrative of exemplary embodiments and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.
