Abstract:
Apparatus and methods are provided whereby a component can be cleaned while the furnace is operational. Additionally, particulates that have accumulated on the component can be collected and retained. The apparatus may include a portable frame, a tubular lance supported by the frame and having a nozzle at a distal end thereof, and a suction generator operatively connected to a proximal end of the lance to generate a suction at the nozzle. Manipulation of the lance to move the nozzle across a component allows accumulated particulates to be removed therefrom through the lance.

Description:
PRIORITY CLAIM 
       [0001]    This application is based on and claims priority benefits from UK Patent Application No. 1401604.2 filed on Jan. 30, 2014, the entire content of which is expressly incorporated hereinto by reference. 
       FIELD 
       [0002]    The present invention relates to cleaning of particulate material from refinery processes or power generation systems, including, but not limited to selective catalyst reduction (“SCR”) catalysts, or components of an SCR system, or convection sections of refinery processes or a power generation system. 
       BACKGROUND 
       [0003]    SCR systems are employed to remove Nitrogen Oxides (NOx) from spent flue gas. Nitrogen Oxides pose pollutions problems, whereas the NOx can react in the atmosphere with water vapor to produce to acid rain, or react with sunlight to produce ozone. NOx forms during combustion of fuel to heat furnaces, including but not limited to, hydrogen reformers, vacuum heaters, platformers, and other process heaters. NOx can form in three ways during combustion: Thermal, Fuel, and Prompt NOx. 
         [0004]    The purpose of a SCR system is to convert the Nitrogen Oxides into diatomic Nitrogen (N2). The system uses liquid ammonia and a porous catalyst to convert the NOx. The ammonia is injected with air into the flue gas at a controlled ratio, and the Nitrogen oxides react with the ammonia and oxygen to form diatomic Nitrogen and water. The catalyst increases the conversion rate to over 90%. The Nitrogen and water can then be safely released into the atmosphere. 
         [0005]    The interior of a furnace is lined with refractory ceramic fiber (RCF), insulating refractory brick, or a combination of the two. The RCF is composed of amorphous silica, that when subjected to elevated temperatures, such as in a platformer, will devitrify into crystalline silica and other components. Due to the gas velocity in the furnace, the crystalline silica is picked up in the gas flow and carried downstream. Likewise, the gas velocity and water vapor can act as an abrasive to the insulating refractory, and by a process known as silica migration, particulates from the insulating refractory can also be gathered and carried. Also, during combustion of fuel, in particular, oil, particulates can be generated and also carried downstream in a process known as oil dusting, for example. These particles can be deposited on the surface of the catalyst and contaminate the generally porous surface of a catalyst, or on heat transfer vanes of a convection section of a furnace. These cannot only reduce the effectiveness of the catalyst, but can also damage or poison the catalyst, leading to reduced performance. In the case of heat transfer vanes, the particulates act as insulators; this contamination thus reduces the heat transfer efficiency of the unit. 
         [0006]    In order to overcome such issues, various ways of cleaning the contaminated units have been employed. One known method involves use of a sonic horn, to generate sound waves to dislodge particulates from the contaminated unit, which are then expelled with the flue gas. However, these particles may also become lodged in the channels of the catalyst, or fall to the bottom of the unit and collect. Another method involves blasting, typically with dry ice, which as it sublimes in the region of the particulates causes them to be dislodged from the contaminated unit. 
       SUMMARY 
       [0007]    The embodiments disclosed herein seek to overcome or ameliorate at least one of the problems of the prior art or provide a useful alternative. Generally, methods and apparatus are provided whereby a component can be cleaned while the furnace is operational, or “on-line”. Additionally, particulates that have accumulated on the component can be collected and retained, whereas previously, these would have been exhausted into the atmosphere, causing pollution. 
         [0008]    According to some embodiments, an apparatus for removing accumulated particulates from a component will comprise a portable frame, a tubular lance supported by the frame and having a nozzle at a distal end thereof, and a suction generator operatively connected to a proximal end of the lance to generate a suction at the nozzle, wherein manipulation of the lance to move the nozzle across a component allows accumulated particulates to be removed therefrom through the lance. The nozzle may be comprised of graphite. According to some embodiments, the distal end of the lance may be at substantially a right angle relative to a longitudinal axis thereof. 
         [0009]    The suction generator may be a static venturi device having inlet and outlet ends for passage therethrough of a flow of pressurized fluid, and a suction port, and wherein the apparatus comprises a flexible hose connecting the proximal end of the lance to the suction port of the venturi device. Other suction generators, e.g., vacuum pumps, may however be satisfactorily employed. According to those embodiments wherein the suction generator is a venturi device, the device will include inlet and outlet ends for passage therethrough of a flow of pressurized fluid, and a suction port. A flexible hose may thus be provided to connect the proximal end of the lance to the suction port of the venturi device. A filter assembly having an inlet end may be fluid-connected to the outlet end of the venturi device. According to such embodiments, therefore, the filter assembly will thereby receive a flow of pressurized fluid with entrained particulates from the outlet end of the venturi device and discharge a substantially particulate-free pressurized fluid flow through the discharge end of the filter assembly. 
         [0010]    The frame may comprise a guide collar assembly having a tubular supporting collar surrounding the lance. The guide collar assembly according to some embodiments may include a support cradle, wherein the supporting collar is movably connected to the support cradle by a connection pin. Certain embodiments of the frame will be comprised of a separated pair of upright supports, and a gantry beam attached to and spanning the upright supports. The pair of upright supports may be height adjustable. A trolley may be movably coupled to the gantry beam such that a counterbalance device will interconnect the trolley and the lance. The counterbalance device may comprise a retractable tethering cable connected to the proximal end of the lance. 
         [0011]    Some embodiments will have a frame which includes at least one stabilization assembly for attachment to adjacent support beams in a vicinity of the component to be suction cleaned. The stabilization assembly may comprise a coupling member connectable to the frame, a connecting plate connectable to an adjacent support beam in the vicinity of the component, and a turnbuckle assembly interconnecting the coupling member and the connecting plate. 
         [0012]    In use, an apparatus according to the embodiments described herein may be positioned adjacent a component from which particulates are to be removed (e.g., SCR catalyst used in a SCR system), and operating the suction generator to generate a suction at the nozzle of the lance. The lance may be manipulated to move the nozzle across the component to cause particulates to be removed therefrom by the generated suction, following which the removed particulates may be transported from the component through the lance. 
         [0013]    As noted previously, the suction may be generated at the nozzle by means of a venturi device which generates a suction in response to a flow of pressurized fluid (air) therethrough. The particulates transported from the component through the lance will therefore be entrained in such fluid flow which can thereafter be directed to a filter assembly. The entrained particulates may thus be removed by suitable filter media in the filter assembly, following which substantially particulate-free fluid (air) may be discharged to the ambient environment. 
         [0014]    These and other aspects and advantages of the present invention will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof. 
     
    
     
       BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS 
         [0015]    The disclosed embodiments of the present invention will be better and more completely understood by referring to the following detailed description of exemplary non-limiting illustrative embodiments in conjunction with the drawings of which: 
           [0016]      FIG. 1  is a perspective view showing an apparatus according to an embodiment of the invention; 
           [0017]      FIG. 2  is an enlarged perspective view of the mounting assembly employed in the apparatus depicted in  FIG. 1 ; 
           [0018]      FIG. 3  is an even further enlarged perspective view of the guide collar assembly employed in the mounting assembly depicted in  FIG. 2 ; 
           [0019]      FIG. 4  is a further perspective view partly in section of the guide collar assembly taken along line  4 - 4  in  FIG. 3  and showing longitudinal movement of the vacuum lance permitted thereby; 
           [0020]      FIG. 5  is a perspective view partly in section of the guide collar assembly similar to  FIG. 4  but showing the pivotal movement of the vacuum lance permitted thereby; 
           [0021]      FIG. 6  is a perspective view partly in section of the guide collar assembly similar to  FIG. 4  but showing the latitudinal movement of the vacuum lance permitted thereby; 
           [0022]      FIG. 7  is view of a venturi effect device that may be used with the apparatus depicted in  FIG. 1 ; 
           [0023]      FIG. 8  is a cross-sectional elevational view of a filter assembly that may be used with the apparatus depicted in  FIG. 1 ; 
           [0024]      FIG. 9  is a perspective view showing an apparatus according to another embodiment of the invention; and 
           [0025]      FIG. 10  is a perspective view of a clamping assembly for use with the apparatus depicted in  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    An apparatus  10  according to an embodiment of the invention for removing accumulated particulates from an SCR or convection system (schematically represented by reference numeral  12 ) while the system  12  is operational is depicted the accompanying  FIGS. 1-6 . As shown, the apparatus  10  generally includes a frame assembly  14  comprised of a pair of spaced-apart vertical supports  16   a,    16   b  having lower ends received within a vertical branch  18   a,    20   a  of the tubular couplings  18 ,  20 , respectively. The frame  14  likewise has pairs of downwardly divergent leg supports  22 - 1 ,  22 - 2  and  24 - 1 ,  24 - 2  having upper ends received within a respective one of the leg branches  18 - 1 ,  18 - 2  and  20 - 1 ,  20 - 2 , respectively, of the couplings  18 ,  20 . Base supports  30 ,  32  span the distance between the lower ends of leg supports  22 - 1 ,  24 - 1  and  22 - 2 ,  24 - 2 , respectively. Casters  34  may be mounted to the lower end of each leg support  22 - 1 ,  22 - 2 ,  24 - 1  and  24 - 2  to allow the frame  14  to be maneuvered relative to an opening  12   a  in the system  12 . The upper ends of the vertical supports  16   a,    16   b  carry a mounting pad  36   a,    36   b  to which a gantry beam  38  is attached. The vertical supports  16   a,    16   b  are removably attached to the couplings  18 ,  20  by means a pin and aperture arrangement  18   b,    20   b  thereby allowing vertical height adjustment of the gantry beam  30  relative to the system opening  12   a  in the direction of arrow A 1 . 
         [0027]    A trolley  40  is moveably supported by the gantry beam  38  so as to be capable of reciprocal movements along the gantry beam  38  in the direction of arrow A 2 . The trolley  40  in turn dependently supports a counterbalance device  42  having a tethering cable  42   a  attached to a proximal end  50   a  of a rigid tubular vacuum lance  50 . The lance  50  includes a distal end  50   b  which in the embodiment shown is at substantially a right angle relative to the elongate axis of the lance  50 . 
         [0028]    The weight of the vacuum lance  50  is therefore counterbalanced by the counterbalance device  42  to allow an operator to insert the lance  50  into and remove it from the system  12  through opening  12   a.  The counterbalance device  42  thus assists the operator against gravity as the lance  50  and the nozzle  52  attached at its distal end  50   b  are guided into the system  12  through opening  12   a  during cleaning by allowing the tethering cable to be retracted and payed-out as the lance is raised and lowered, respectively, relative to the system  12 . The nozzle  52  is most preferably a graphite head which is sufficiently soft so as to avoid damage to the relatively delicate material of the SCR catalyst (not shown) in the system  12 . 
         [0029]    The distal end  50   b  of the lance  50  is received by a guide collar assembly  60  which is perhaps better viewed by the enlarged depictions thereof in  FIGS. 2-6 . In this regard, the collar assembly  60  includes a pair of spaced-apart cross-supports  62 ,  64  extending between and attached to the base supports  30 ,  32 . A rectangular parallelepiped shaped cradle box  66  is dependently supported by and attached between cross-supports  62 ,  64  by the connecting members  68 ,  70 . 
         [0030]    The lance  50  is received within a tubular supporting collar  72  which is pivotally attached to the cradle box  66  by opposed pins  74   a,    74   b . As is shown in  FIGS. 4-6 , the collar  72  has several degrees of freedom to allow movement of the lance  50  and the nozzle  52  attached to the distal end  50   b  thereof relative to the material being cleaned. Specifically, the collar  72  loosely surrounds the lance  50  to allow it to be moved reciprocally upwardly and downwardly in the direction of arrow A 3  in  FIG. 4 . In addition, the lance  50  may be pivoted about the longitudinal axis A L  of the pins  74   a,    74   b  in the direction of arrow A 4  as shown by  FIG. 5 . In addition, the pins  74   a,    74   b  are sufficiently long to allow for back-and-forth movements within the cradle box  66  as shown by arrow AS of  FIG. 6 . In addition to the movements shown in  FIGS. 4-6  by arrows A 3 -A 5 , the lance may also be rotated about its longitudinal axis to allow the nozzle  52  to be pivoted back and forth in a generally horizontal plane. Thus, the guide collar assembly  60  allows the lance  50  and the nozzle  52  attached at the distal end thereof to be manipulated and positioned as may be desired by the operator during the vacuum cleaning operation. 
         [0031]    The proximal end  50   b  of the lance  50  is attached via flexible hose  76  (see  FIG. 1 ) to the suction coupling  78   a  of a suction generator which in the embodiment shown is provided by a static venturi device  78  (see  FIG. 7 ). The venturi device  78  produces a reduced pressure (vacuum) in the hose  76  and thus at the nozzle  52  attached at the distal end of the lance  50  by a flow of compressed air entering the venturi device  78  at its inlet end  78 - 1  and being discharged at its outlet end  78 - 2 . As is well know, this flow of compressed air within the venturi device  78  creates reduced (vacuum) pressure at the suction coupling  78   a.  In this manner, therefore, a suction force is evident at the nozzle  52  attached at the distal end of the lance  50   b  by virtue of the hose  76 . Alternatively, other means of generating a suction may be employed, such as dynamic vacuum pumps and the like. 
         [0032]    As the nozzle  52  is moved across the SCR catalyst (or other material) within the system  12  as guided manually by an operator (as may be aided by a video camera (not shown) attached at the distal end  50   b  of the lance  50 ), loose particulates will be suctioned out of the system  12  and travel through the lance  50  and the hose  76  to the venturi device. The loose particulates thereby suctioned from the SCR catalyst material within the system  12  will therefore be entrained by the compressed air flowing through the venturi device  78  and discharged from its outlet end  78 - 2 . The outlet end  78 - 2  may therefore be connected by suitable hose (not shown) to the inlet end  80 - 1  of a filter assembly  80  as shown in  FIG. 8  so that the entrained particulates may be removed from the air flow through filter media  80   a.  Substantially particulate-free air may therefore be discharged to the ambient environment from the filter assembly  80  through outlet  80 - 2 . 
         [0033]    In use, the apparatus  10  is mounted above the furnace system  12  relative to the access opening  12   a  (which may approximately be 8″×24″). The operator will manipulate the lance  50  so that the nozzle  52  is moved across the catalyst to be cleaned associated with the system component. As this happens, the soft graphite head of the nozzle  52  minimizes damage to the component while allowing close contact. The reduced pressure generated at the nozzle  52  sucks accumulated particulates from the component. These liberated particulates then travel along the lance  50  and hose  76  to the venturi device  78  and then into the main airflow through the venturi  78  to the filter media  80   a  enclosed within the filter assembly  80 . The filter media  80   a  collects and retains the dislodged particulates while the airflow through the filter  30  continues and is discharged into the ambient atmosphere through outlet  80 - 2  thereby avoiding atmospheric pollution from the particulates removed from the component. 
         [0034]    Instead of cleaning a catalyst of an SCR system, the apparatus may be used to clean the convection section of a furnace. In this case, the graphite head of the nozzle may be replaced with a metal wire brush, as the heat transfer fins and pipes of the convection section are less prone to damage than the catalyst. While the same gantry and counterbalance can be used, in an alternative embodiment, the lance may be mounted on a balancing fulcrum, with the counterbalance mounted on an elongate rod on an opposing side of the balancing fulcrum. The lance, nozzle, reduced pressure generator, hose, and enclosed filter may be the same as described above. An access hole may be made in the convection section of the furnace to allow the lance and nozzle inside, to allow cleaning 
         [0035]    An alternative embodiment of an apparatus  100  according to the invention is shown in  FIGS. 9 and 10 . Specifically, the apparatus  100  will, like apparatus  10  described above include a gantry beam  102  connected to and spanning a pair of upright supports  104 ,  106 . Similarly, the gantry beam  102  will likewise support the trolley  40  which in turn dependently supports the counterbalance device  42  having a tethering cable  42   a  attached to a proximal end  50   a  of the tubular vacuum lance  50 . The weight of the vacuum lance  50  is therefore counterbalanced by the counterbalance device  42  to allow an operator to insert the lance  50  into and remove it from the system being vacuum cleaned. 
         [0036]    In the embodiment of the apparatus  100  depicted in  FIG. 9 , the upright supports  104 ,  106  include foot pads  104   a,    106   a  which are positioned on a rigid supporting surface of the system being vacuum cleaned. In order to stabilize the gantry beam  102  spanning the upright supports  104 ,  106 , a pair of stabilization assemblies  110  are provided. Each stabilization assembly includes at one end a U-shaped coupling member  112  which is sized and configured to be attached to a respective one of the upright supports  104 ,  106  by means of retaining bolts  114  (see  FIG. 10 ). A connection plate  116  is provided at an opposite end of the stabilization assembly  110 , the plate  116  having a raised lip bar  116   a  so as to engage a flange of an existing structural support beam SB associated with the system being cleaned. 
         [0037]    The U-shaped coupling member  112  and the connection plate  116  are respectively provided with threaded shafts  112 - 1  and  116 - 1  which are coaxially coupled to one another by a turnbuckle  120 . Thus, in thus the U-shaped coupling member  112  will be connected to one of the upright supports  104 ,  106  and the lip bar  116   a  of the connection plate  116  will be engaged with an edge of an adjacent one of the structural support beams SB. Thereafter, the turnbuckle  120  may be turned so as to drawn the U-shaped coupling member  112  and connection plate  116  toward one another. In such a manner, each stabilization assembly  110  will positively connect the upright supports  104 ,  106  to an adjacent respective structural support beam SB thereby stabilizing the gantry beam  102 . 
         [0038]    It will be understood that the description provided herein is presently considered to be the most practical and preferred embodiments of the invention. Thus, the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope thereof.