Abstract:
A method of assembling a syngas cooler is provided. The method includes coupling a supply line within a cooler shell, coupling a heat transfer panel within the cooler shell, and coupling a heat transfer enclosure within the cooler shell such that the heat transfer enclosure substantially isolates the heat transfer panel from the cooler shell. A manifold is coupled in flow communication with the supply line, the heat transfer enclosure, and the heat transfer panel.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to a syngas cooler, and, more particularly, to a heat recovery system for use with a syngas cooler. 
         [0002]    At least some known syngas coolers include platens and a tube wall to facilitate heat transfer from a syngas flow to a fluid flowing within the platens and/or tube wall. The platens in such syngas coolers are circumscribed by the tube wall. Known tube walls are designed to be gas-tight such that the syngas is effectively retained within the tube wall. As such the syngas contacts the tube wall rather than an outer shell of the cooler. Generally, the cooler outer shells are not as thermally tolerant as the tube wall. 
         [0003]    As least some known syngas coolers include a plurality of platen supply lines and a plurality of separate tube wall supply lines that are each coupled between the tube wall and the outer shell. The platen supply lines couple to a platen lower manifold. The tube wall supply lines are each coupled to a separate tube wall lower manifold such that the platens and the tube wall are supplied with heat transfer fluid through respective manifolds. In at least some known syngas coolers, the platen lower manifold is positioned upstream and radially inward from the tube wall lower manifold. In such coolers, the platen supply lines must pass through the tube wall to be coupled to the platen lower manifold. Unfortunately, such penetrations through the tube wall may undesirably allow heated syngas to flow through the tube wall and contact the outer shell, which may induce thermal stresses and/or premature wear to the outer shell of the cooler. To facilitate reducing syngas leakage, at least some known syngas coolers include a seal coupled between the platen supply line and the tube wall where each supply line passes through the tube wall. However, such seals may leak and allow heated syngas to escape from the tube wall. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    In one aspect, a method of assembling a syngas cooler is provided. The method includes coupling a supply line within a cooler shell, coupling a heat transfer panel within the cooler shell, and coupling a heat transfer enclosure within the cooler shell such that the heat transfer enclosure substantially isolates the heat transfer panel from the cooler shell. A manifold is coupled in flow communication with the supply line, the heat transfer enclosure, and the heat transfer panel. 
         [0005]    In another aspect, a manifold for use with a syngas cooler is provided. The manifold includes a first outlet configured to be coupled in flow communication with a heat transfer enclosure coupled within the syngas cooler. The heat transfer enclosure is configured to substantially encase a flow of heated gas through the syngas cooler. The manifold further includes a second outlet configured to be coupled in flow communication with a heat transfer panel coupled within the syngas cooler, and an inlet configured to be coupled in flow communication with a heat transfer medium supply line that extends through the syngas cooler. 
         [0006]    In a still further aspect, a heat recovery system for use with a gasifier system is provided. The heat recovery system includes a supply line configured to channel a heat transfer medium into the heat recovery system, and a heat transfer enclosure including a plurality of circumferentially-spaced tubes. The heat transfer enclosure is configured to substantially encase a flow of heated gas through the gasifier system. The heat recovery system further includes a heat transfer panel including a plurality of tubes, and an annular manifold. The annular manifold includes a first outlet coupled in flow communication with the heat transfer enclosure, a second outlet coupled in flow communication with the heat transfer panel, and an inlet coupled in flow communication with the supply line such that the heat transfer medium is channeled from the supply line to the heat transfer enclosure and the heat transfer panel via the manifold. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is schematic view of an exemplary integrated gasification combined cycle system. 
           [0008]      FIG. 2  is a schematic cross-sectional view of an exemplary syngas cooler that may be used with the system shown in  FIG. 1 . 
           [0009]      FIG. 3  is a cross-sectional view of an exemplary lower manifold that may be used with the syngas cooler shown in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]      FIG. 1  is a schematic diagram of an exemplary integrated gasification combined-cycle (IGCC) power generation system  10 . IGCC system  10  generally includes a main air compressor  12 , an air separation unit (ASU)  14  coupled in flow communication to compressor  12 , a gasifier  16  coupled in flow communication to ASU  14 , a syngas cooler  18  coupled in flow communication to gasifier  16 , a gas turbine engine  20  coupled in flow communication to syngas cooler  18 , and a steam turbine  22  coupled in flow communication to syngas cooler  18 . 
         [0011]    In operation, compressor  12  compresses ambient air that is then channeled to ASU  14 . In the exemplary embodiment, in addition to compressed air from compressor  12 , compressed air from a gas turbine engine compressor  24  is supplied to ASU  14 . Alternatively, compressed air from gas turbine engine compressor  24  is supplied to ASU  14 , rather than compressed air from compressor  12  being supplied to ASU  14 . In the exemplary embodiment, ASU  14  uses the compressed air to generate oxygen for use by gasifier  16 . More specifically, ASU  14  separates the compressed air into separate flows of oxygen (O 2 ) and a gas by-product, sometimes referred to as a “process gas”. The O 2  flow is channeled to gasifier  16  for use in generating partially combusted gases, referred to herein as “syngas” for use by gas turbine engine  20  as fuel, as described below in more detail. 
         [0012]    The process gas generated by ASU  14  includes nitrogen and will be referred to herein as “nitrogen process gas” (NPG). The NPG may also include other gases such as, but not limited to, oxygen and/or argon. For example, in the exemplary embodiment, the NPG includes between about 95% and about 100% nitrogen. In the exemplary embodiment, at least some of the NPG flow is vented to the atmosphere from ASU  14 , and at some of the NPG flow is injected into a combustion zone (not shown) within a gas turbine engine combustor  26  to facilitate controlling emissions of engine  20 , and more specifically to facilitate reducing the combustion temperature and reducing nitrous oxide emissions from engine  20 . In the exemplary embodiment, IGCC system  10  includes a compressor  28  for compressing the nitrogen process gas flow before being injected into the combustion zone of gas turbine engine combustor  26 . 
         [0013]    In the exemplary embodiment, gasifier  16  converts a mixture of fuel supplied from a fuel supply  30 , O 2  supplied by ASU  14 , steam, and/or limestone into an output of syngas for use by gas turbine engine  20  as fuel. Although gasifier  16  may use any fuel, gasifier  16 , in the exemplary embodiment, uses coal, petroleum coke, residual oil, oil emulsions, tar sands, and/or other similar fuels. Furthermore, in the exemplary embodiment, the syngas generated by gasifier  16  includes carbon dioxide. 
         [0014]    In the exemplary embodiment, syngas generated by gasifier  16  is channeled to syngas cooler  18  to facilitate cooling the syngas, as described in more detail below. The cooled syngas is channeled from cooler  18  to a clean-up device  32  for cleaning the syngas before it is channeled to gas turbine engine combustor  26  for combustion thereof. Carbon dioxide (CO 2 ) may be separated from the syngas during clean-up and, in the exemplary embodiment, may be vented to the atmosphere. Gas turbine engine  20  drives a generator  34  that supplies electrical power to a power grid (not shown). Exhaust gases from gas turbine engine  20  are channeled to a heat recovery steam generator  36  that generates steam for driving steam turbine  22 . Power generated by steam turbine  22  drives an electrical generator  38  that provides electrical power to the power grid. In the exemplary embodiment, steam from heat recovery steam generator  36  is supplied to gasifier  16  for generating syngas. 
         [0015]    Furthermore, in the exemplary embodiment, system  10  includes a pump  40  that supplies boiled water from steam generator  36  to syngas cooler  18  to facilitate cooling the syngas channeled from gasifier  16 . The boiled water is channeled through syngas cooler  18  wherein the water is converted to steam. The steam from cooler  18  is then returned to steam generator  36  for use within gasifier  16 , syngas cooler  18 , and/or steam turbine  22 . 
         [0016]      FIG. 2  shows a schematic cross-sectional view of an exemplary syngas cooler  100  that may be used with system  10 . In the exemplary embodiment, syngas cooler  100  is a radiant syngas cooler. Syngas cooler  100  includes a pressure vessel shell  102  having a top opening (not shown) and a bottom opening (not shown) that are generally concentrically aligned with each other along a cooler centerline  104 . As referred to herein, an “axial” direction is a direction that is substantially parallel to centerline  104 , an “upward” direction is a direction that is generally towards the top opening, and a “downward” direction is a direction that is generally towards the bottom opening. Syngas cooler  100  has a radius R measured from centerline  104  to an outer surface  106  of shell  102 . Furthermore, in the exemplary embodiment, a top (not shown) of cooler  100  includes a plurality of downcomer openings (not shown) and a plurality of riser openings (not shown) that circumscribe the top opening. In the exemplary embodiment, shell  102  is fabricated from a pressure vessel quality steel, such as, but not limited to, a chromium molybdenum steel. As such, shell  102  is facilitated to withstand the operating pressures of syngas flowing through syngas cooler  100 . Moreover, in the exemplary embodiment, the shell top opening is coupled in flow communication with gasifier  16  for receiving syngas discharged from gasifier  16 . The bottom opening of shell  102 , in the exemplary embodiment, is coupled in flow communication with a slag collection unit (not shown) to enable the collection of solid particles formed during gasification and/or cooling. 
         [0017]    Within shell  102 , in the exemplary embodiment, are a plurality of heat transfer medium supply lines (also referred to herein as “downcomers”)  108 , a heat transfer wall (also referred to herein as a “tube wall”)  110 , and a plurality of heat transfer panels (also referred to herein as “platens”)  112 . More specifically, in the exemplary embodiment, downcomers  108  are positioned radially inward of shell  102 , tube wall  110  is radially inward of downcomers  108 , and platens  112  are arranged within tube wall  110  such that tube wall  110  substantially circumscribes platens  112  or otherwise substantially encases platens  112 . Generally, in the exemplary embodiment, downcomers  108  are located at a radius R 1  outward from centerline  104 , and tube wall  110  is located at a radius R 2  from centerline  104 , wherein radius R 1  is longer than radius R 2  and radius R is longer than radii R 1  and R 2 . Alternatively, shell  102 , downcomers  108 , tube wall  110 , and/or platens  112  are arranged in other orientations. 
         [0018]    In the exemplary embodiment, downcomers  108  supply a heat transfer medium  114 , such as, for example, water from steam generator  36 , to syngas cooler  100 , as described herein. More specifically, downcomers  108  supply heat transfer medium  114  to tube wall  110  and platens  112  via a lower manifold  200 , as is described in more detail below. Lower manifold  200 , in the exemplary embodiment, is coupled proximate to the cooler bottom opening, and, as such, is downstream from the cooler top opening through which syngas enters cooler  100 . In the exemplary embodiment, downcomers  108  include tubes  116  fabricated from a material that enables cooler  100  and/or system  10  to function as described herein. Furthermore, in the exemplary embodiment, a gap  118  defined between shell  102  and tube wall  110  may be pressurized to facilitate decreasing stresses induced to tube wall  110 . 
         [0019]    In the exemplary embodiment, tube wall  110  includes a plurality of circumferentially-spaced, axially-aligned tubes  120  coupled together with a membrane (also referred to herein as a “web”) (not shown). Although in the exemplary embodiment, tube wall  110  includes only one row of tubes  120 , in other embodiments, tube wall  110  may include more than one row of tubes  120 . More specifically, in the exemplary embodiment, the membrane and tubes  120  are coupled together such that tube wall  110  is substantially impermeable to syngas. As such, tube wall  110  substantially retains the syngas in an inner portion  122  of cooler  100  that is effectively isolated from downcomers  108  and/or shell  102 . As such, tube wall  110  forms an enclosure through which syngas may flow. In the exemplary embodiment, heat is transferred from the syngas retained within tube wall  110  to heat transfer medium  114  flowing through tubes  120 . Tubes  120  and/or the membrane are fabricated from a material having heat transfer properties that enable cooler  100  to function as described herein. Furthermore, in the exemplary embodiment, tube wall  110  is coupled to risers extending through the top of shell  102  (not shown) such that the heated heat transfer medium  114  may be channeled from cooler  100  to, for example, heat recovery steam generator  36  (shown in  FIG. 1 ). 
         [0020]    In the exemplary embodiment, platens  112  each include a plurality of tubes  124  coupled together with a membrane  126 . Each platen  112  may include any number of tubes  124  that enables cooler  100  to function as described herein. Although platens  112  are shown in  FIG. 2  as being oriented generally radially with generally axially-aligned tubes  124 , platens  112  and/or tubes  124  may be oriented and/or configured in any suitable orientation and/or configuration that enables cooler  100  to function as described herein. In the exemplary embodiment, platen tubes  124  are each coupled to a lower inlet tube  128  and to an upper outlet tube (not shown). More specifically, in the exemplary embodiment, tubes  124  are aligned substantially perpendicular to lower inlet tube  128  such that tubes  124  extend from lower inlet tube  128  in an array. Alternatively, tubes  124  may be oriented ay any angle with respect to tube  128  and/or may be arranged in a different array from lower inlet tube  128 . 
         [0021]      FIG. 3  is a cross-sectional view of an exemplary lower manifold  200  that may be used with syngas cooler  100  (shown in  FIG. 2 ). Manifold  200  has a radius R 11  measured from a manifold center point  202  to an outer surface  204  of manifold  200 . In the exemplary embodiment, manifold  200  includes an annular ring portion  208 , a downcomer inlet  210 , a tube wall outlet  212 , and a platen outlet  214 . More specifically, in the exemplary embodiment, downcomer inlet  210  is coupled to downcomer  108  (shown in  FIG. 2 ), tube wall outlet  212  is coupled to tube wall  110  (shown in  FIG. 2 ), and platen outlet  214  is coupled to platen  112  (shown in  FIG. 2 ). Although  FIG. 3  shows only two downcomer inlets  210 , two tube wall outlets  212 , and two platen outlets  214  spaced about manifold  200 , manifold  200  may include more or less than two downcomer inlets  210 , more or less than two tube wall outlets  212 , and/or more or less than two platen outlets  214 . 
         [0022]    Furthermore, in the exemplary embodiment, the number of downcomer inlets  210 , the number of tube wall outlets  212 , and the number of platen outlets  214  are equal. Alternatively, the number of downcomer inlets  210 , the number of tube wall outlets  212 , and/or the number of platen outlets  214  may be different. In one embodiment, the number of downcomer inlets  210 , tube wall outlets  212 , and platen outlets  214  is equal to the number of platens  112  (shown in  FIG. 2 ) within cooler  100 . Moreover, in the exemplary embodiment, downcomer inlet  210 , tube wall outlet  212 , and platen outlet  214  are generally aligned in the same radial direction  206  such that downcomer inlet  210 , tube wall outlet  212 , and platen outlet  214  are arranged in a band  215  about annular ring portion  208 . Alternatively, downcomer inlet  210 , tube wall outlet  212 , and platen outlet  214  may be oriented in other alignments. For example, in an alternative embodiment, downcomer inlet  210  may be circumferentially-offset from tube wall outlet  212  and/or platen outlet  214 . 
         [0023]    In the exemplary embodiment, annular ring portion  208  includes a chamber  216  having a radius R 12  measured from a chamber center point  218  and an annular ring portion inner surface  220 . In the exemplary embodiment, chamber  216  receives heat transfer medium  114  discharged from downcomer inlet  210 . Further, in the exemplary embodiment, chamber  216  extends continuously within annular ring portion  208  such that chamber  216  is in fluid communication with each downcomer inlet  210 , each tube wall outlet  212 , and/or each platen outlet  214 . Alternatively, chamber  216  may be divided into a plurality of sub-chambers (not shown). 
         [0024]    In the exemplary embodiment, downcomer inlet  210  includes a substantially straight centerline  224  that extends radially outwardly from center point  218 . In an alternative embodiment, downcomer inlet centerline  224  may be non-linear. For example, in one embodiment, centerline  224  may be arcutate such that inlet  210  is arcuate. Alternatively, depending on the design of manifold  200 , centerline  224  may extend from a different point (not shown) such that centerline  224  is offset from center point  218 . In the exemplary embodiment, downcomer inlet  210  is aligned with respect to annular ring  208  such that downcomer inlet  210  is oriented at, but is not limited to being oriented at, an angle α between approximately 0° and approximately 180°, and more specifically, between approximately 0° and approximately 90°, wherein angle α is measured counter-clockwise from chamber radial direction  222  towards centerline  224 . Alternatively, downcomer inlet  210  may be oriented at any orientation that enables cooler  100  and/or manifold  200  to function as described herein. Furthermore, in an alternative embodiment, manifold  200  includes a plurality of downcomer inlets  210  that area circumferentially-spaced about annular ring portion  208  along the same manifold radial direction  206 . 
         [0025]    In the exemplary embodiment, tube wall outlet  212  has a substantially straight centerline  226  that extends radially outwardly from center point  218 . Alternatively, tube wall outlet centerline  226  may be non-linear. For example, in one embodiment, tube wall outlet centerline  226  may be arcuate such that outlet  212  is arcuate. Further, centerline  226  may extend from a different point (not shown) such that centerline  226  is offset from center point  218 . In the exemplary embodiment, tube wall outlet  212  is aligned with respect to annular ring  208  such that tube wall outlet  212  is oriented at, but is not limited to being oriented at, an angle β between approximately 0° and approximately 180°, and more specifically, between approximately 108° and approximately 170°, wherein angle β is measured counter-clockwise from chamber radial direction  222  towards outlet centerline  226 . Alternatively, tube wall outlet  212  may be oriented at any orientation that enables cooler  100  and/or manifold  200  to function as described herein. Furthermore, in an alternative embodiment, manifold  200  includes a plurality of tube wall outlets  212  that are circumferentially-spaced about annular ring portion  208  along the same manifold radial direction  206 . 
         [0026]    In the exemplary embodiment, platen outlet  214  has a substantially straight centerline  228  that extends radially outwardly from center point  218 . Alternatively, platen outlet centerline  228  may be other than straight. For example, in one embodiment, platen outlet centerline  228  may be arcuate such that outlet  214  is arcuate. Further, centerline  228  may extend from a different point (not shown) such that centerline  228  is offset from center point  218 . In the exemplary embodiment, platen outlet  214  is aligned with respect to annular ring  208  such that platen outlet  214  is oriented at, but is not limited to being oriented at, an angle γ between approximately 0° and approximately 180°, and more specifically, between angle β and approximately 170°, wherein angle γ is measured counter-clockwise from chamber radial direction  222  towards platen outlet centerline  228 . More specifically, platen outlet  214  is oriented such that tube wall outlet  212  is circumferentially-spaced between downcomer inlet  210  and platen outlet  214 . In one embodiment, platen outlet  214  is spaced approximately 18° from tube wall outlet  212 . Alternatively, platen outlet  214  may be at any orientation that enables cooler  100  and/or manifold  200  to function as described herein. Furthermore, in an alternative embodiment, manifold  200  includes a plurality of platen outlets  214  that are circumferentially-spaced about annular ring portion  208  with respect to radius R 12  along the same manifold radial direction  206 . 
         [0027]    In the exemplary embodiment, tube wall outlet  212  includes an orifice  230 , and platen outlet  214  includes an orifice  232 . Alternatively, either tube wall outlet  212  and/or platen outlet  214  does not include an orifice. In the exemplary embodiment, orifices  230  and  232  facilitate balancing and/or equalizing the flow of heat transfer medium  114  through tube wall  110  and/or platens  112 . For example, orifices  230  and  232  facilitate balancing and/or equalizing heat transfer medium pressure, mass flow rate, and/or any fluid characteristic of heat transfer medium  114  that enables cooler  100  and/or manifold  200  to function as described herein. 
         [0028]    During operation of cooler  100 , heat transfer medium  114  enters cooler  100  through downcomers  108  extending through the top portion of cooler  100 . More specifically, in the exemplary embodiment, water from steam generator  36  is channeled to downcomers  108  for use within cooler  100 . The heat transfer medium  114 , in the exemplary embodiment, is discharged from downcomers  108  into manifold  200  through downcomer inlets  210 . The heat transfer medium  114  is supplied to tube wall  110  and platens  112  via manifold  200 . More specifically, in the exemplary embodiment, the heat transfer medium  114  is discharged through tube wall outlets  212  and platen outlets  214  into tube wall  110  and platens  112 , respectively. As the heat transfer medium  114  flows through outlets  212  and  214  orifices  230  and  232  facilitate regulating the flow of heat transfer medium  114  into tube wall  110  and platens  112 , respectively. 
         [0029]    In the exemplary embodiment, syngas is discharged into cooler  100  from gasifier  16 . The flow of syngas through cooler  100  is retained within inner portion  122  of cooler  100  by tube wall  110 . The heat of syngas within tube wall  110  is transferred to heat transfer medium  114  with tube wall tubes  120  and platen tubes  124  to heat the heat transfer medium  114  and to facilitate cooling the syngas. More specifically, in the exemplary embodiment, the heat from the syngas heats water flowing through tubes  120  and/or  124  such that the water is converted to steam as it flows through tube wall  110  and/or platens  112 , and the syngas is cooled as it flows through cooler  100 . Further, in the exemplary embodiment, heated heat transfer medium  114  is discharged from tube wall  110  and platens  112  into risers, which channels the heated heat transfer medium  114  out of cooler  100 . In the exemplary embodiment, the heat transfer medium  114  is channeled through risers to steam generator  36  for use within gasifier  16 , syngas cooler  100 , and/or steam turbine  22 . 
         [0030]    The above-described methods and apparatus facilitate supplying a heat transfer medium to a syngas cooler such that the syngas is effectively isolated from the syngas cooler shell. By reducing penetrations through a tube wall within the syngas cooler, the above-described lower manifold facilitates reducing leaks of syngas through the tube wall. More specifically, by coupling the downcomers to a single lower manifold for both the tube wall and the platens, penetrations through the tube wall are facilitated to be reduced as compared to tube walls that include openings for downcomers to pass through for coupling to a separate platen lower manifold. Furthermore, by reducing the number of openings extending through the tube wall, seals at the openings are also facilitated to be reduced. As such, the above-described manifold facilitates reducing components within the syngas cooler, which facilitates reducing the cost of the syngas cooler, as compared to syngas coolers that include seals within the tube wall. 
         [0031]    The above-described manifold further facilitates reducing components within the syngas cooler by facilitating the elimination of multiple lower manifolds. More specifically, by using the above-describe manifold within a syngas cooler, the syngas cooler is facilitated to be simplified because the platen lower manifold and the tube wall lower manifold are the same component—namely, the above-described manifold. As such, syngas cooler components, such as, for example, manifolds, seals, and/or downcomers, are facilitated to be reduced within syngas cooler as compared to syngas coolers that include separate lower manifolds for the tube wall and the platens. Such reduction of components facilitates reducing cost and complexity of the syngas cooler, while facilitating increasing the serviceability of the syngas cooler. 
         [0032]    Exemplary embodiments of a method and apparatus for recovering heat within a syngas cooler are described above in detail. The method and apparatus are not limited to the specific embodiments described herein, but rather, components of the method and apparatus may be utilized independently and separately from other components described herein. For example, the lower manifold may also be used in combination with other heat transfer systems and methods, and is not limited to practice with only the syngas cooler as described herein. Rather, the present invention can be implemented and utilized in connection with many other heat transfer applications. 
         [0033]    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.