Moisture removal for gasification quench chamber assembly   

Abstract: A gasification assembly that includes a quench chamber and downstream transfer piping is disclosed. The gasification assembly includes the quench chamber and a liquid coolant disposed therein, and a dip tube that is configured to couple a combustion chamber to the quench chamber and also configured to direct syngas from the combustion chamber to the liquid coolant and produce a cooled syngas. The assembly further includes a transfer pipe that is in fluid communication with the cooled syngas and configured to transfer the cooled syngas to a downstream scrubber component. The transfer pipe further includes an excess moisture removal device, which is configured to remove moisture from the cooled syngas.

The invention relates generally to gasifiers, and more particularly to moisture removal at or near the exit of a quench chamber.

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 quench chamber disposed downstream of the combustion chamber. The quench chamber contains a liquid coolant such as water. The effluent from the combustion chamber is contacted with the liquid coolant in the quench chamber; so as to reduce the temperature of the effluent.

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 quench chamber, and subsequently to be discharged as slag slurry. A gaseous component of the effluent is discharged from the quench chamber for further processing. The gaseous component, however, in passing through the quench 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 quench chamber and into downstream equipment, is found to pose operational problems.

In conventional systems, a baffle is placed in the gas exiting path in the quench chamber. Consequently, as liquid-carrying gas contacts the baffle surfaces, a certain amount of the liquid will coalesce on the baffle surfaces. However, the rapidly flowing gas will re-entrain liquid droplets by sweeping droplets from the baffle\'s lower edge.

There is a need for an improved quench chamber assembly configured to more effectively remove entrained liquid content substantially from the effluent gas.

In accordance with one exemplary embodiment of the present invention, a gasification assembly comprises a quench chamber having a liquid coolant disposed therein; a dip tube configured to couple a combustion chamber to the quench chamber and configured to direct syngas from the combustion chamber to the liquid coolant and produce a cooled syngas; and a transfer pipe in fluid communication with the cooled syngas, configured to transfer the cooled syngas to a downstream scrubber component, wherein the transfer pipe further comprises an excess moisture removal device, configured to remove moisture from the cooled syngas.

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:

FIG. 1 depicts a sectional elevation view of a gasification quench chamber assembly in accordance with an exemplary embodiment of the present invention;

FIG. 2 depicts a close-up sectional elevation view of a transfer pipe portion of a gasification quench chamber assembly in accordance with an exemplary embodiment of the present invention;

FIG. 3 depicts a top sectional view of the transfer pipe portion of a gasification quench chamber assembly in FIG. 2 in accordance with an exemplary embodiment of the present invention;

FIG. 4 depicts a close-up sectional elevation view of a transfer pipe portion of a gasification quench chamber assembly in accordance with an exemplary embodiment of the present invention;

FIG. 5 depicts an end sectional view of the transfer pipe portion of a gasification quench chamber assembly in FIG. 4 in accordance with an exemplary embodiment of the present invention;

FIG. 6 depicts a sectional elevation view of a transfer pipe portion of a gasification quench chamber assembly in accordance with an exemplary embodiment of the present invention; and

FIG. 7 depicts a sectional elevation view of a gasification quench chamber assembly in accordance with another exemplary embodiment of the present invention.

DETAILED DESCRIPTION

In accordance with the exemplary embodiments disclosed herein, a gasifier having a quench chamber assembly configured to reduce temperature of syngas downstream of a gasification chamber is disclosed. The gasifier includes a quench chamber containing a liquid coolant disposed downstream of the gasification chamber. A syngas generated from the gasification chamber is directed via a dip tube to the quench chamber to contact the liquid coolant and produce a cooled syngas. A baffle is disposed proximate to an exit path of the quench chamber. In some embodiments, a draft tube may be disposed surrounding the dip tube such that an annular passage is formed between the draft tube and the dip tube. The cooled syngas is directed through the annular passage (if present) and impacted against the baffle so as to remove entrained liquid content from the cooled syngas before the cooled syngas is directed through the exit path. In some embodiments, a deflector plate is disposed between the liquid coolant and the exit path of the quench chamber and configured to remove entrained liquid content from the cooled syngas and prevent sloshing of liquid content to the exit path. In some embodiments, the baffle is asymmetric or symmetric, either open or angular, to remove entrained liquid content from the cooled syngas. In other embodiments, the baffle itself can have channels or cut-outs and overlays to remove entrained liquid and prevent sloshing of liquid content to the exit path. In other embodiments only dip tube is present and the annular section is formed between the dip tube and the quench chamber wall. The provision of asymmetric or symmetric shaped baffle, deflector plate, swirl generator, or combinations thereof substantially reduces entrainment of liquid content in the syngas directed through the exit path to the downstream components (e.g., scrubber assembly, etc.). An entrainment mitigation mechanism, or moisture removal device, is provided at, or along, the transfer pipe exiting the quench chamber. Specific embodiments are discussed in greater detail below with reference to FIGS. 1-7.

Aspects of the present invention relate to a gasification component, namely, a gasification quench chamber assembly, which includes the quench chamber, proper, and other appurtenances such as the quench chamber exit pipe, or transfer line. Quench is typically presented downstream of the gasification chamber and used to reduce the temperature of the manufactured syngas as well as remove (at least partially) solids/fines. In some embodiments, there may be a radiant syngas cooler located intermediate the gasification chamber and the quench chamber. As is typical, the syngas is introduced into the quench chamber via a dip tube. The quench chamber contains a liquid coolant, which reduces the temperature of the syngas. After quenching, the syngas rises up, due to buoyancy. Other features found in quench chambers include an entrainment baffle(s), or splash plate(s), present near the exit of the dip tub. The purpose of the entrainment baffle(s) is ostensibly to knock off water droplets, which are entrained with the outgoing syngas. As the entrainment baffle(s) is not 100% efficient in removal of the liquid from the syngas, liquid is still present in the syngas exiting the quench chamber via the exit pipe. The amount of fines and liquid entrainment in the outgoing syngas also poses a significant challenge in the instrumentation and/or measuring the amount of liquid getting entrained in the quench chamber exit pipe.

Aspects of the present invention increase the overall effectiveness and efficiency of the gasification system by improving upon the removal of entrained liquid from the generated syngas. Further aspects of the present invention address improved removal of entrained liquid while reducing manufacturing costs and/or operating expenses. Aspects of the present invention offer a simplified design, which additionally improve the life of the assembly and reliability, availability, and maintenance of the gasification plant.

The entrainment mitigation mechanisms depicted in FIGS. 1-7 may be employed separately or in combination with one another. Moreover, as may be appreciated, the relative sizes, shapes, and geometries of the entrainment mitigation mechanisms may vary. The entrainment mitigation mechanisms may be employed along with a quench chamber during the initial manufacturing, or the entrainment mitigation mechanisms may be retrofit to existing quench units. Further, the entrainment mitigation mechanisms may be adjusted based on operational parameters, such as the type of carbonaceous fuel, the system efficiency, the system load, or environmental conditions, among others to achieve the desired amount of flow damping.

Referring to FIG. 1 depicts an exemplary embodiment of portions of a gasification system in accordance with aspects of the present invention. As shown, a gasification quench chamber assembly, or gasification assembly, 800 comprises a quench chamber 802 and a transfer pipe 870. The quench chamber 802 is in fluid communication with a gasification chamber 900, upstream, and quench chamber 802 is in fluid communication with a scrubber assembly 920, downstream, via the transfer pipe 870. In embodiments, the transfer pipe 870 may be additionally in fluid communication with the quench chamber 802 via a return tube 874. Similarly, in another embodiment, the transfer pipe 870 may additionally be in fluid communication with a heat source 910 (e.g., gas turbine, etc.) via a supply line 878 as shown in FIG. 7.

The quench chamber 802 comprises a dip tube 806 which is configured to couple the gasification chamber 900 to the quench chamber 802 and is further configured to direct syngas 1000 from the combustion chamber 900 to a liquid coolant 804 contained in a portion of the quench chamber 802. The quench chamber 802 may further include an inlet line 805 for providing any requisite liquid coolant 804 to the quench chamber 804. By introducing the syngas 1000 to the liquid coolant 804, the syngas 1000 is cooled and exits the quench chamber as cooled syngas 1002 via the transfer pipe 870 towards the scrubber assembly 920. Upon the cooling of the syngas 1000 in the quench chamber 802, slag or fines 810, may precipitate out of the syngas 1000 thereby settling at the bottom of the quench chamber 804. The quench chamber 804 may further comprise at least one baffle 808 that aids in knocking out and/or off water droplets entrained in the exiting syngas 1002.

It should be noted that various configurations of quench chamber could be employed without departing from aspects of the present invention. For example, although FIGS. 1 and 7 depict a quench chamber 802 having a dip tube-only configuration, the quench chamber 802 may alternatively employ a dip/draft configuration, a dip only configuration, a dip/draft with a quench ring configuration, and the like.

The transfer pipe 870 is configured to provide a means for transmitting the cooled syngas 1002 to the scrubber assembly 920 and other downstream components (not shown). The transfer pipe, or line, 870 further comprises an excess liquid removal device, or entrainment mitigation mechanism, 872 that is configured to further remove excess liquid (e.g., water, etc.) from the cooled syngas 1002 so that a cooled syngas 1006, with an even smaller amount of liquid, ultimately is conveyed to the downstream scrubber assembly 920 and other downstream components.

As shown in FIG. 1, the excess liquid removal device 872 employed by aspects of the present invention include one or more of applying a centrifugal action or force to remove excess liquid from the cooled syngas 1002; and/or perforating at least a portion of the transfer pipe 870 to provide an egress means for excess liquid (e.g., water droplets) in the cooled syngas 1002. In any event, excess liquid is effectively removed from the syngas prior to it reaching the scrubber assembly 920, resulting in an improved gasification process.

In an embodiment a water injection line may also be provided, as denoted by 950 and 960. In this manner, water may be added along the line 870 in one or more locations. For example, as shown, the injection line may be located anterior to the 876 as denoted by 950. The injection line may be located within the moisture removal device 870. The water injection line may be located in either of these locations, or both locations, as well as any location along the transfer line 870.

Referring to FIGS. 2 and 3, an excess liquid removing device 872 that employs perforations is shown. The transfer line 870 includes an excess liquid removing device 872 that comprises a plurality of perforations 880 configured to allow egress of moisture from the transfer pipe 870. To aid in the removal of moisture from the syngas 1004 a sleeve 889, such as a cold-water sleeve, may be provided, wherein the sleeve 889 partially or substantially surrounds a portion of the transfer pipe 870. The sleeve 889 may contain a cooling fluid (e.g., water) therein that has a temperature that is less than a temperature of the cooled syngas 1004 within the transfer pipe 870. In this manner, the sleeve 889 aids in further condensing moisture in the travelling syngas 1004 so that the moisture may drop or settle out via the plurality of perforations 880 and be collected via collection pipe 882 and returned via return line 874 back to the quench chamber 802 (FIG. 1).

Clearly other configurations than those depicted in FIGS. 2 and 3 may be provided without departing from aspects of the present invention. By way of example, and without limitation, other configurations of perforations may be provided. For example, the perforations may have different quantities, shapes, configurations, patterns, and the like, from those shown. Similarly, the sleeve may surround the transfer line 870 in a different manner. For example, the sleeve may fully or partially surround the transfer line 870. Similarly, the cooling fluid used in the cooling sleeve may be any suitable fluid that assists in condensing moisture out of the syngas 1004.

Referring to FIGS. 4 and 5, an excess liquid removing device 872 that employs centrifugal force or action is shown. The transfer line 870 includes an excess liquid removing device 872 that comprises a baffle 876 or similar means for exerting or employing centrifugal force to the syngas 1004. The baffle 876 may, for example, include one or blades or vanes that are curved or warped in relationship to the direction of travel of the syngas 1004 through the transfer line 870 (See e.g., FIG. 5). In consort with the baffle 876, a plurality of perforations 880 may be located on a wall of the transfer line 870 thereby providing an egress means for the moisture (e.g., water droplets) that is spun or forced towards the periphery of the transfer line 870 by the centrifugal force caused by the baffle 876. As shown, a return line 874 may be used to return any collected moisture from the perforations. The return line 874 maybe in fluid communication with the quench chamber 802 (FIG. 1).

Referring to FIG. 6, a cross section elevation view of another embodiment of a excess liquid removing device 2000 is depicted. The moisture removal device 2000 may comprise a pipe 2012 having one or more tees 2010 (e.g., two tees shown in embodiment in FIG. 6) extending therefrom. The pipe 2012 conveys outgoing syngas 3000 from a quench chamber 802 (FIG. 1) towards a scrubber assembly 920 (FIG. 1). The one or more tees 2010 along the pipe 2012 provide a fluid communication connection with an entrainment vessel 2020. Alternatively to having tees 2010 there may be one or more perforations, openings, and the like, that allow excess moisture to escape from the syngas that is travelling along the pipe 2012. In any event, the entrainment vessel 2020 gathers moisture 3030 therein and may have a controlled water level. The moisture 3030 may be continually flushed back to the quench chamber 802 by a water flow 3015 that is provided into the entrainment vessel 2020 via an input line 2030. The flushing back to the quench chamber 802 via return line 2035 may be continual or periodic so as to prevent plugging. The entrainment vessel 2020 may be designed so that any transient excess water flow (i.e., liquid entrainment) may flow back, as denoted by 3020, to the quench chamber 802 while maintaining an appropriate pressure drop. The return line 2035 may include a raised loop 2025 having a height, denoted by D, above the water level of the entrainment vessel 2020. The height, D, may be adjustable as required by the particular application in use. In this manner, excess moisture removed from the syngas may be readily removed and returned to the quench chamber 802 for reuse.

Referring to FIG. 7, the excess liquid removal device 872 in another embodiment of the present invention includes any combination of: applying a centrifugal action or force to remove excess liquid from the cooled syngas 1002; and/or, perforating at least a portion of the transfer pipe 870 to provide an egress means for excess liquid (e.g., water droplets) in the cooled syngas 1002; and/or, heating the exiting cooled syngas 1002 so as to evaporate out moisture droplets held in the exiting cooled syngas 1002. In any event, excess liquid is effectively removed from the syngas prior to it reaching the scrubber assembly 920, resulting in an improved gasification process.

The centrifugal action or force and perforation embodiments are discussed above, in reference to FIG. 1. As shown in FIG. 7, under another aspect of the present invention the excess liquid removing device 872 may use evaporation or evaporative means to remove moisture from the syngas 1002. The evaporative means may comprise injecting a fluid 912 at the existing syngas 1004, wherein the fluid 912 has a higher temperature than the temperature of the exiting syngas 1002, thereby aiding in evaporating at least a portion of the remaining moisture in the existing syngas 1002. In this manner, additional moisture is removed from the existing syngas 1002. As shown, the fluid 912 may comprise injecting, via an injection line 878, a hot syngas provided from a heat source 910 or the like. In an embodiment, the supplied hot syngas 912 is supplied from a heat source 910 that may be a gas turbine, a syngas cooler, a gasifier, and the like.

In accordance with one exemplary embodiment of the present invention, a gasification assembly comprises a quench chamber having a liquid coolant disposed therein; a dip tube configured to couple a combustion chamber to the quench chamber and configured to direct syngas from the combustion chamber to the liquid coolant and produce a cooled syngas; and a transfer pipe in fluid communication with the cooled syngas, configured to transfer the cooled syngas to a downstream scrubber component, wherein the transfer pipe further comprises an excess moisture removal device, configured to remove moisture from the cooled syngas.

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.