The invention relates generally to gasifiers, and more particularly to a cooling chamber assembly for a gasifier.
In a normal coal gasification process, wherein a particulated carbonaceous fuel such as coal or coke or a carbonaceous gas is burned, the process is carried out at relatively hot temperatures and high pressures in a combustion chamber. When injected fuel is burned or partially burned in the combustion chamber, an effluent is discharged through a port at a lower end of the combustion chamber to a cooling chamber disposed downstream of the combustion chamber. The cooling chamber contains a liquid coolant such as water. The effluent from the combustion chamber is contacted with the liquid coolant in the cooling chamber, so as to reduce the temperature of the effluent. In certain applications, the cooling chamber may be used as a quench chamber for syngas. In certain other applications, the cooling chamber may be used as a scrubber for removing entrained solids from the generated syngas. In certain applications, a gasifier may be provided with both a quench system and a scrubber.
When the fuel is a solid such as coal or coke, the gasifier arrangement permits a solid portion of the effluent, in the form of ash, to be retained in the liquid pool of the cooling chamber, and subsequently to be discharged as slag slurry. A gaseous component of the effluent is discharged from the cooling chamber for further processing. The gaseous component, however, in passing through the cooling chamber, will carry with it a substantial amount of the liquid coolant. A minimal amount of liquid entrained in the exiting gas is not considered objectionable to the overall process. However, excessive liquid carried from the cooling chamber and into downstream equipment, is found to pose operational problems.
There is a need for an improved cooling chamber assembly for both quench and scrubber applications configured to remove entrained liquid content substantially from an effluent gas generated in a gasifier.
In accordance with one exemplary embodiment of the present invention, a gasifier includes a combustion chamber in which a combustible fuel is burned to produce a syngas and a particulated solid residue. A cooling chamber having a liquid coolant is disposed downstream of the combustion chamber. A dip tube is disposed coupling the combustion chamber to the cooling chamber. The syngas is directed from the combustion chamber to the cooling chamber via the dip tube to contact the liquid coolant and produce a cooled syngas. An asymmetric or symmetric liquid separator is disposed proximate to an exit path of the cooling chamber and configured to remove entrained liquid content from the cooled syngas directed through the annular passage to the exit path.
In accordance with another exemplary embodiment of the present invention, a finned asymmetric or symmetric liquid separator is disposed proximate to an exit path of the cooling chamber and configured to remove entrained liquid content from the cooled syngas directed through the annular passage to the exit path.
In accordance with another exemplary embodiment of the present invention, an asymmetric or symmetric faceted or round liquid separator is disposed proximate to an exit path of the cooling chamber and configured to remove entrained liquid content from the cooled syngas directed through the annular passage to the exit path.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
In accordance with the exemplary embodiments disclosed herein, a gasifier having a cooling chamber assembly configured to reduce temperature of syngas downstream of a combustion chamber is disclosed. The gasifier includes a cooling chamber containing a liquid coolant disposed downstream of the combustion chamber. A syngas generated from the combustion chamber is directed via a dip tube to the cooling chamber to contact the liquid coolant and produce a cooled syngas. The gasifier also includes a dip tube coupling the combustion chamber to the cooling chamber and configured to direct syngas from the combustion chamber to the cooling chamber to contact the liquid coolant and produce a cooled syngas. A draft tube is disposed surrounding the dip tube and defining an annular passage there between. A liquid separator is disposed proximate to an exit path of the cooling chamber and configured to remove entrained liquid content from the cooled syngas directed through the annular passage to the exit path. In one embodiment, the liquid separator is a symmetric liquid separator. In another embodiment, the liquid separator is an asymmetric liquid separator. In some embodiments, the cooling chamber is used for quench applications. In certain other embodiments, the cooling chamber is used for scrubbing applications. The cooled syngas is directed through the annular passage and impacted against the liquid separator so as to remove entrained liquid content from the cooled syngas before the cooled syngas is directed through the exit path. The features used to accomplish the removal of the entrained liquid are referred to herein as the “liquid separator”. The liquid separator may be a single component or an assembly. In some embodiments, the liquid separator includes a finned deflector coupled to the dip tube. In other embodiments, the liquid separator includes a conical shaped faceted or round separator. The provision of the exemplary liquid separator substantially reduces entrainment of liquid content in the syngas directed through the exit path to the downstream components. Specific embodiments are discussed in greater detail below with reference to the
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The combustible fuel is burned in the combustion chamber 14 to produce an effluent including syngas and a particulated solid residue. Hot effluent is fed from the combustion chamber 14 to the cooling chamber 16 provided at the lower end of the shell 12. The cooling chamber 16 is coupled to a pressurized source 30 and configured to supply a pool of liquid coolant 32, preferably water to the cooling chamber 16. The level of the liquid coolant in the cooling chamber 16 is maintained at a desired height to assure an efficient operation depending on the conditions of the effluent fed from the combustion chamber 14 into the cooling chamber 16. The lower end of the gasifier shell 12 is provided with a discharge port 34 through which water and fine particulates are removed from the cooling chamber 16 in the form of a slurry.
In the illustrated embodiment, a constricted portion 36 of the combustion chamber 14 is coupled to the cooling chamber 16 via a dip tube 38. The hot effluent is fed from the combustion chamber 14 to the liquid coolant 32 in the cooling chamber 16 via a passageway 40 of the dip tube 38. A ring 42 is disposed proximate to the dip tube 38 and coupled to the pressurized source 30 so as to sustain a dip tube inner wall in a wetted condition to best accommodate the downward effluent flow. A lower end 44 of the dip tube 38 may be serrated, and positioned below the surface of the liquid coolant 32 to efficiently achieve cooling of the effluent.
A draft tube 46 is positioned in the cooling chamber 16. The draft tube 46 includes an elongated cylindrical body 48 fixedly supported in the gasifier shell 12. A lower portion of the draft tube 46 is submerged in the liquid coolant 32. The cylindrical body 48 terminates adjacent to, but spaced at its upper end, from the ring 42. The cylindrical body 48 is also spaced from the dip tube 38 to define an annular passage 50. The syngas is contacted with the liquid coolant 32 to produce a cooled syngas. The cooled syngas is then passed through the annular passage 50 towards an exit path 52 of the cooling chamber 16.
As discussed above, the gaseous component of the effluent is discharged for further processing via the exit path 52 from the cooling chamber 16. In the illustrated embodiment, the cooling chamber 16 is a quench chamber. In certain other embodiments, the cooling chamber is a scrubber configured to remove entrained solids from the syngas. It is known conventionally that the gaseous component, however, in passing through a quench chamber, will carry with it a substantial amount of the liquid coolant. Excessive liquid carried from the cooling chamber and into downstream equipment, is found to pose operational problems.
In the illustrated embodiment, a liquid separator 54 is disposed proximate to the exit path 52 of the cooling chamber 16. It should be noted herein that in the illustrated embodiment, the liquid separator 54 is a symmetric liquid separator. The liquid separator 54 includes a deflector 56 coupled to the dip tube 38 and configured to redirect the flow of the cooled syngas from the annular passage 50 in a downward direction. In the illustrated embodiment, the deflector 56 may be spherical shaped. In other embodiments, other shapes of the deflector are also envisaged. A plurality of fins 58 are provided to the deflector 56. The cooled syngas redirected by the deflector 56 is forced to flow through a series of blockages, in other words the fins 58. As a result, the momentum of flow of the syngas is dissipated and available flow area is used more efficiently. The flow of syngas is more evenly distributed at an exit of the deflector 56. In the normal course of quench cooling, the cooled gas stream would convey with it a certain amount of liquid coolant. However, as the cooled gas stream impinges against the deflector 56 and the fins 58, flow velocity of the syngas is reduced, and the entrained liquid content is removed from the syngas. The deflector 56 also prevents sloshing of liquid coolant 32 to the exit path 52 of the cooling chamber 16.
In the illustrated embodiment, the deflector 56 may include a plurality of holes 57 for directing a portion of the cooled syngas to a region upstream of the deflector 56 in the cooling chamber 16. This facilitates to enhance syngas flow uniformity and also reduced entrainment of liquid content in the syngas. In certain embodiments, the deflector 56 may employ holes 56 and may not have fins 58. It should be noted herein that the illustrated gasifier is an exemplary embodiment and other configurations of gasifiers are also envisaged. It should noted herein that the term “cooling chamber” will refer to a quench system or a scrubber regardless of the gasifier configuration. Other embodiments of the liquid separator are discussed below with reference to subsequent figures.
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In the illustrated embodiment, a liquid separator 95 is disposed proximate to an exit of the annular passage 93. The liquid separator 95 includes a deflector 97 coupled to the dip tube 89 and configured to redirect the flow of the cooled syngas from the annular passage 93 in a downward direction. A plurality of fins (not shown) may be provided to the deflector 97. The cooled syngas redirected by the deflector 97 may forced to flow through a series of fins. As a result, the momentum of flow of the syngas is dissipated and available flow area is used more efficiently. The syngas then flows through a space 99 between the draft tube 87 and a wall 101 of the cooling chamber 85 in an upward direction and is exited from an upper side.
In accordance with the embodiments discussed herein, the provision of the deflector, fins, or combinations thereof facilitates to reduce cooled syngas flow velocity, and also to increase gas flow path distance between the liquid coolant and the exit path of the cooling chamber. This results in increased residence time of the gas and liquid coolant mixture in the cooling chamber leading to enhanced removal of entrained liquid content from the cooled syngas. In general, the deflector and the fins may create a tortuous path for the flow of syngas within the cooling chamber.
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In accordance with the embodiments discussed herein, the provision of the splash plates 105 and baffle elements 106 facilitates to reduce cooled syngas flow velocity, and also to increase gas flow path distance between the liquid coolant and the exit path of the cooling chamber. This results in increased residence time of the gas and liquid coolant mixture in the cooling chamber leading to enhanced removal of entrained liquid content from the cooled syngas. The amount of entrained liquid content in the syngas exiting the separator 102 is reduced as radial velocity is smaller than axial velocity of flow of syngas. In general, the splash plates 105 and baffle elements 106 may create a tortuous path for the flow of syngas within the cooling chamber. The separator also prevents re-entrainment of liquid content in the syngas.
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This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
This application is related to the following co-pending United States patent applications having Serial No. {Attorney Docket No. 235585-1}, entitled “QUENCH CHAMBER ASSEMBLY FOR A GASIFIER” and Serial No. {Attorney Docket No. 236150-1}, entitled “GASIFICATION SYSTEM FLOW DAMPING” assigned to the same assignee as this application and filed concurrently herewith, each of which is hereby incorporated by reference.