Abstract:
Disclosed is a method of removing a particulate layer from a gasification system component including locating a shedding apparatus in operable communication with the gasification system component. A force is transmitted from the shedding apparatus into the gasification system component and the particulate layer is shed from the gasification system component as a result of the force. Further disclosed is a syngas cooler for a gasification system including a vessel and a plurality of thermal energy transfer platens located in the vessel. A shedding apparatus is in operable communication with the plurality of platens and is capable of shedding a particulate layer from the plurality of platens by transmitting a force to the plurality of platens.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to gasification systems and processes. More particularly, the subject matter relates to removal of particulate layers from gasification system components. 
         [0002]    Gasification is a process for the production of power, chemicals, and industrial gases from carbonaceous or hydrocarbon feedstocks such as coal, heavy oil, and petroleum coke. Gasification converts carbonaceous or hydrocarbon feedstocks into synthesis gas, also known as syngas, comprising primarily hydrogen and carbon monoxide. The resultant syngas is a feedstock for making useful organic compounds or can be used as a clean fuel to produce power. 
         [0003]    In a typical gasification plant, a carbonaceous or hydrocarbon feedstock and molecular oxygen are contacted at high pressures within a partial oxidation reactor (gasifier). The feedstock and molecular oxygen react and form syngas. Non-gasifiable ash material and unconverted and/or incompletely converted feedstock are by products of the process and take essentially two forms: molten slag and smaller particles referred to as “fines”. In some gasification plants, a syngas cooler is located downstream of the gasifier. The syngas, ash, slag and fines cool as they travel through the syngas cooler. A quench process cools and saturates the syngas near the exit of the syngas cooler. Alternatively, in gasification plants without syngas coolers, the quench is located near the exit of the gasifier. Further, additional cooling and/or gas clean-up components may be disposed downstream of the quench. During the cooling process, however, deposits of soot and ash, for example, form on interior surfaces of the syngas cooler, and/or the quench and additional cooling components. The deposits in the syngas cooler create many problems. For example, the deposit layer prevents efficient heat transfer from taking place, resulting in a reduction in steam production from the gasification process. Also, deposits may include corrosive species, thus the removal of the corrosive deposits would prolong the life of components of the syngas cooler, for example, heat transfer tubes. Further, deposits often break off from the interior of the syngas cooler under some operating conditions, for example, startup and shutdown. Such spontaneous liberation of large deposits often results in plugging of downstream components of the syngas cooler. Finally, falling deposits create a hazard for workers performing maintenance and/or repairs in the syngas cooler. Therefore it is desirable to remove the deposits at regular intervals prior to the deposits developing into a substantial size. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    According to one aspect of the invention, a method of removing a particulate layer from a gasification system component includes locating a shedding apparatus in operable communication with the gasification system component. A force is transmitted from the shedding apparatus into the gasification system component and the particulate layer is shed from the gasification system component as a result of the vibration. 
         [0005]    According to another aspect of the invention, a syngas cooler for a gasification system includes a vessel and a plurality of thermal energy transfer platens located in the vessel. A shedding apparatus is in operable communication with the plurality of platens and is capable of shedding a particulate layer from the plurality of platens by transmitting a force to the plurality of platens. 
         [0006]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0008]      FIG. 1  is a plan view of an embodiment of a syngas cooler for a gasification system; 
           [0009]      FIG. 2  is a cross-sectional view of the syngas cooler of  FIG. 1 ; 
           [0010]      FIG. 3  is a cross-sectional view of another embodiment of a syngas cooler for a gasification system; 
           [0011]      FIG. 4  is a cross-sectional view of another embodiment of the syngas cooler of  FIG. 3 ; 
           [0012]      FIG. 5  is a cross-sectional view of an embodiment of a syngas cooler including a single support; 
           [0013]      FIG. 6  is a cross-sectional view of an embodiment of a syngas cooler including a helical manifold; 
           [0014]      FIG. 7  is an alternative embodiment of the syngas cooler of  FIG. 5 ; 
           [0015]      FIG. 8  is an alternative embodiment of the syngas cooler of  FIG. 6 ; 
           [0016]      FIG. 9  is a cross-sectional view of yet another embodiment of a syngas cooler; 
           [0017]      FIG. 10  is a cross-sectional view of still another embodiment of a syngas cooler; 
           [0018]      FIG. 11  is a detail view of an embodiment of the syngas cooler of  FIG. 10  having a mechanical crank; 
           [0019]      FIG. 12  is a detail view of an embodiment of the syngas cooler of  FIG. 10  having an electrical or pneumatic actuator; 
           [0020]      FIG. 13  is a detail view of an embodiment of the syngas cooler of  FIG. 10  having a hydraulic jet; 
           [0021]      FIG. 14  is a cross-sectional view of an embodiment of a syngas cooler including a shock tube; 
           [0022]      FIG. 15  is a cross-sectional view of another embodiment of the syngas cooler of  FIG. 14 ; and 
           [0023]      FIG. 16  is a cross-sectional view of yet another embodiment of the syngas cooler of  FIG. 15 . 
       
    
    
       [0024]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Shown in  FIG. 1  is an embodiment of a gasification system component, in this case a syngas cooler  10 . The syngas cooler  10  comprises a vessel shell  12  which defines an outer surface of the syngas cooler  10 . A plurality of internal components may be disposed inside of the vessel shell  12  in an interior  14  of the syngas cooler  10 . Many of these components, including a tube cage  16  and one or more sets of platens  18 , are configured and disposed to facilitate transfer of thermal energy from syngas in the syngas cooler  10  to the tube cage  16  and/or the platens  18 . While eight sets of platens  18  are shown in  FIG. 1 , it is to be appreciated that other quantities of sets of platens  18 , for example  10  or  12  sets of platens  18  may be arranged in the interior  14  of the syngas cooler  10 . As shown in  FIG. 2 , the tube cage  16  comprises a plurality of individual cage tubes  20  and each set of platens  18  comprises a plurality of platen tubes  22 . During operation of the syngas cooler  10 , particulates in the syngas accumulate and build up creating layers  24  of particulates on, for example, heat exchange surface such as the platen tubes  22  and the cage tubes  20 . The deposit layers  24  inhibit efficient thermal energy transfer from the syngas to the platen tubes  22  and the tube cages  20 . 
         [0026]    To periodically remove the layers  24 , in some embodiments the syngas cooler  10  includes one or more sprayers  26 , as shown in  FIGS. 1 and 2 . The sprayers  26  are disposed at the interior  14  of the syngas cooler  10 . When the sprayers  26  are activated, a high pressure flow  28  of fluid, in some embodiments, water, is directed from the sprayers  26  toward the platen tubes  22 , thereby removing the layers  24  therefrom. The flow  28  acts to remove the layers  24  by mechanically shearing the layers  24  from the platen tubes  22  and also by chemically dissolving the layers  24  in the flow  28 . Further, because of a temperature differential between the flow  28  and the layers  24 , when it impacts the layers  24  the flow  28  causes thermal contractions in the deposit layers  24  thus causing the layers  24  to fall off of the platen tubes  22 . As shown in  FIG. 2 , the sprayers  26  may be arranged around a circumference of the interior  14 , and as shown in  FIG. 1 , may also be arranged along a length of the interior  14 . Further, in some embodiments, each sprayer  26  is capable of spraying in a predetermined pattern along the platen tubes  22  to increase the amount of platen tube  22  surface exposed to the flow  28 . Alternatively, in some embodiments, the sprayers  26  are configured and disposed to spray solid projectiles, for example, ball bearings, of a desired size at the platen tubes  22  to remove the layers  24 . 
         [0027]    In some embodiments, the means to remove layers  24  from the sets of platens  18  is a mechanical structure that causes a vibration of the platen tubes  22  sufficient to cause the layers  24  to be liberated from the platen tubes  22 . For example, as shown in  FIG. 3 , a vibration manifold  30  is disposed in the interior  14  of the syngas cooler  10 . The vibration manifold  30  is mechanically attached to the sets of platens  18  by one or more struts  32 , which in some embodiments are springs. At least one support  34  extends through the vessel shell  12  from an exterior  36  of the syngas cooler  10  through a support opening  38 . In some embodiments, the support opening  38  includes a ball bearing  40  arrangement at which the support  34  is disposed. In the embodiment of  FIG. 3 , the manifold  30  is substantially circular in shape, and two supports  34  are utilized and are disposed at substantially the same circumferential position in the vessel shell  12 . It is to be appreciated that in other embodiments, as shown in  FIG. 4 , the supports  34  may be located at other relative circumferential locations, for example 180 degrees apart. Further, as shown in  FIG. 5 , a single support  34  may be utilized. Referring again to  FIG. 3 , flex hoses  42  are coupled to the supports  34  to provide a conduit for a flow of cooling fluid through the supports  34  and the manifold  30  to extend the useful life of the manifold  30  in the high temperature environment of the interior  14 . In the embodiment of  FIG. 3 , a vibratory force is initiated by an activator, such as a mechanical crank  44 . In some embodiments, the mechanical crank  44  is driven by a magnetic actuator comprising members of opposing polarity that urge rotation of the mechanical crank  44  without direct contact with the mechanical crank  44 . Turning of the mechanical crank  44  initiates a rotation of the support  34 , which induces a vibratory force in the manifold  30 . The vibration of the manifold  30  is transmitted to the sets of platens  18  via the one or more struts  32  thus causing the platen tubes  22  to vibrate and cause the layers  24  to be removed from the platen tubes  22 . While the manifold  30  shown in  FIG. 3  is substantially circular in shape, as shown in  FIG. 6 , the manifold  30  may be helical in shape extending in at least one direction along a manifold axis  46 . A helical manifold  30  allows for greater flexibility to improve the vibratory capacity of the manifold  30  and for the placements of additional struts  32  fixed to the platens  20  along a length of the platens  20 . 
         [0028]    Referring again to  FIG. 5 , in some embodiment the manifold  30  may be supported by a single support  34 . The support  34  extends through vessel shell  12  and comprises an outer support  50  that extends through the vessel shell  12 , and an inner support  52  that is affixed to the manifold  30 . The outer support  50  and the inner support  52  are coupled to each other by, for example, a bellows coupling  54 . In another embodiment, as shown in  FIG. 7 , the outer support  50  and inner support  52  are coupled to each other by a wound tube  56 . In the embodiment of  FIG. 5 , the vibratory force is initiated by one of several means including a mechanical hammer or crank  58 , an electrically or pneumatically-induced vibration, and/or by a fluid pulse through the outer support  50 . The force is transmitted through the outer support  50  and the bellows coupling  54  to the manifold  30  via the inner support  52 . The vibratory force is then transmitted through the one or more struts  32  to the platen tubes  22  to remove the layers  24 . Referring now to  FIG. 8 , some embodiments may include a helical manifold  30  together with the bellows coupling  54 . Further, the manifold  30  may be supported by more than one support  34 , for example, two supports  34 , each including a bellows coupling  54 . Use of the bellows couplings  54  allows the outer supports  50  to remain in a fixed position while the inner supports  52  freely vibrate in response to the vibratory force. 
         [0029]    Referring to  FIG. 9 , in some embodiments, the one or more struts  32  are coupled directly to the inner support  52  so the vibratory force is transmitted directly from the inner support  52  to the one or more struts  32 . Referring to  FIG. 10 , the vibratory force may be initiated internally to the inner support  52 . For example, referring to  FIG. 11 , the crank  58  may be disposed inside of the inner support  52  and when activated, initiates vibration of the inner support  52 . As shown in  FIG. 12 , an electrical or pneumatic actuator  60  may be similarly disposed in the inner support  52  to initiate vibration thereof. Further, as shown in  FIG. 13 , a hydraulic jet  62  or water hammer disposed in the inner support  52  may initiate vibration of the inner support  52 . Initiating the vibratory force in the inner support  52  increases efficient transmission of the vibratory force since it is not necessary to transmit the vibratory force to the inner support  52  via the outer support  50  and the bellows coupling  54 . 
         [0030]    Referring now to  FIG. 14 , some embodiments may utilize one or more shock tubes  64  to impart the vibratory force on the platens  20 . Each shock tube  64  includes a shock tube body  66  that extends through an opening  68  in the tube cage  16 . In one embodiment, since syngas is normally present in the shock tube  64 , a quantity of oxygen is injected into the shock tube  64 , which ignites the syngas fuel. The combustion process results in a shock wave  70  which imparts a force on the set of platens  18 . The force initiates vibration of the set of platens  18  which removes the layers  24  from the platen tubes  22 . As shown in  FIG. 15 , the one or more shock tubes  64  may be utilized to initiate vibration of a manifold  30 . The manifold  30  is coupled to one or more struts  32  which transmit the vibratory force initiated by the one or more shock tubes  64  to the sets of platens  18 . In this embodiment, flexibility in the manifold  30  design enables high tunability to achieve a desired amount of vibration. Further the manifold  30  serves to isolate the combustion process from the syngas in the syngas cooler  10 . In other embodiments, as shown in  FIG. 16 , the shock tube  64  apparatus is isolated from the manifold  30  by a diaphragm  72  disposed in the one or more supports  34 . When initiated, the shock tube  64  causes the diaphragm  72  to vibrate, which in turn transmits the vibration through a gas or fluid, for example, nitrogen, disposed in the support  34  and manifold  30 . The shock tube  64  exhausts through an exhaust tube  74  so that exhaust gases are isolated from the remainder of the system. 
         [0031]    It is to be appreciated that while the description of the embodiments herein are illustration in relation to a syngas cooler  10 , application of the embodiments to other components, for example, a quench or other components of a gasification system, is contemplated within the present scope. 
         [0032]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.