Patent Application
20090056223
This invention relates generally to gasification systems, and more specifically to methods and apparatus for cooling synthetic gas (“syngas”) in gasifiers.
At least some known gasification systems convert a mixture of fuel, air or oxygen, steam, and/or limestone into an output of partially combusted gas, sometimes referred to as “syngas”. At least some known gasification systems use a separate gasifier, and a physically-large radiant cooler to gasify bottoms, to recover heat, and to remove solids from the syngas, to make the syngas useable by other systems. Further, at least some gasifiers include a quench chamber in which the syngas may be cooled. At least some known quench chambers include one or more quench rings that provide a constant film of water on the chamber walls and/or a dip tube.
At least some known methods of fabricating quench ring rims require a forged billet to be machined. However, such machining practices may increase the complexity, the capital expense, and the time necessary to complete the fabrication of such quench ring rims.
In one aspect, a method for fabricating a rim for use in a gasification system includes providing a hollow pipe, forming the pipe into a circular pipe, wherein a first end of the pipe is coupled to an opposite second end of the pipe, and cutting the pipe to form a rim having a desired circumference.
In another aspect, a method for fabricating a quench ring rim for use in a gasification system includes forming a hollow torroid by coupling a first end of a cylinder to a second opposite end of the cylinder, thereby defining an annular cavity within the torroid, and cutting the torroid to form an annular rim having a C-shaped cross-sectional profile.
In a further aspect, a quench ring rim for use in a gasification system includes an inner surface, an outer surface opposite said inner surface, a first rim edge, a second rim edge, an inner diameter defined by the radial distance between a bottom of said first rim edge and a top of said second rim edge, and an outer diameter defined by the radial distance between a top of said first rim edge and a bottom of said second rim edge. The rim is fabricated by providing a straight pipe having a desired length, diameter, and thickness, forming the pipe into a circular pipe by feeding the pipe through a pipe rolling machine, wherein a first end of the pipe is joined to a second end of the pipe, and wherein the first and second ends are sealed, and cutting the pipe along a desired circumference to form said rim having desired dimensions.
Synthetic gas, or “syngas,” as used herein refers to a gas mixture containing varying amounts of carbon monoxide and hydrogen. Syngas is formed by the gasification of a fuel containing carbon such that the fuel is converted to a gaseous product. Syngas may be created by steam catalytic oxidation of natural gas or liquid hydrocarbons to produce hydrogen. Alternatively, syngas may be created the gasification of coal and in some types of energy from waste gasification systems. Syngas may be used in power generation systems and/or for producing chemicals, such as ammonia or methanol. Syngas may also be used as an intermediate in producing synthetic fuel for use as a fuel or lubricant.
During operation, gasifier 100 converts a mixture of, for example, fuel and oxygen into an output of syngas. In some known gasifiers 100, the generated syngas includes slag, carbon dioxide, and/or other contaminant gases. In the exemplary embodiment, the syngas generated by gasifier 100 is cooled and scrubbed in quench section 106 before being channeled through quenched gas outlet 104. The contaminants may be separated from the syngas in quench section 106 and may be vented to the atmosphere.
In the exemplary method, first and second ends 302 and 304, respectively, are then sealed to complete the formation of circular pipe 400 such that an annular cavity is defined within pipe 400. In the exemplary embodiment, a penetration weld is used to seal ends 302 and 304. In alternative embodiments, other methods of sealing may be used. As shown in
In the exemplary method, pipe 400, when sealed, is heat treated for a pre-determined amount of time and at a pre-determined temperature. In the exemplary method, the pre-determined amount of time is between ten and fifty minutes or, more specifically, twenty to forty minutes or, even more specifically, approximately thirty minutes. Heat treatment in alternative embodiments may occur for a different elapsed period of time. In the exemplary method, the pre-determined temperature is based on the material composition of circular pipe 400. In the exemplary embodiment, pipe 400 is substantially composed of a nickel-iron-chromium metal alloy such as commercially available Incoloy 825. Alternative embodiments may use different materials or combinations of materials. In the exemplary embodiment, pipe 400 is heated at a temperature between 1600 and 2000° F. or, more specifically between 1700 and 1900° F. Alternative embodiments may use a different temperature range or a particular temperature. Further, alternative embodiments may use a different basis for determining the appropriate heat treatment temperature.
In the exemplary method, following the heat treatment, pipe 400 is cooled. In the exemplary embodiment, the cooling method includes exposing circular pipe 400 to ambient air until a pre-determined amount of time has elapsed and/or until pipe 400 may is at or below a pre-determined temperature. Alternative embodiments may use other cooling methods such as, but not limited to, liquid quenching.
Once circular pipe 400 has cooled, a quench ring may be formed by cutting circular pipe 400 along a circumference (not shown). For example, circular pipe 400 may be, but is not limited to being, cut using water-jet cutting. Alternative methods may use other cutting methods such as, but not limited to, plasma cutting and/or oxyfuel cutting.
During operation, quench ring rim 500 distributes a film of water around an inner surface (not shown) of a dip tube (not shown) and/or quench section 106 (as shown in
The above-described methods and apparatus facilitate reducing the time and materials necessary for fabricating a quench ring rim for use in a gasification system. Use of a straight pipe having desired dimensions facilitates reducing material waste compared to the use of a forged billet which requires material on the inner diameter billet to be scraped out and discarded during fabrication of a quench ring rim. The ability to reduce the time and materials necessary for fabricating a quench ring rim facilitates reducing the cost of manufacturing a gasification system.
Exemplary embodiments of methods and apparatus that facilitate fabricating a quench ring rim are described above. The methods and apparatus are not limited to the specific embodiments described herein, but rather, components of the methods and apparatus may be utilized independently and separately from the other components described herein. For example, the method of fabrication used to form the quench ring rim for use in a power plant may also be completed and/or used in combination with other industrial plant or component design and monitoring systems and methods, and is not limited to practice with only power plants as described herein. Rather, the present invention can be implemented and utilized in connection with many other component or plant designs and monitoring applications.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
