Abstract:
Apparatus for removing coked refractory from the inside of a cylindrical structure used in a fluid catalytic converter. A body is received within the structure and movable along its length. A rotatable nozzle assembly delivers jets of water under high pressure to the surface of the coked refractory to disintegrate it by hydrodemolition.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/273,082 filed Oct. 13, 2011. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to hydrodemolition devices and methods for removing refractory from refractory-lined structures. 
       BACKGROUND OF THE INVENTION 
       [0003]    Hydrodemolition—or hydraulic demolition—is a well known art practiced by forcing an erosive material, generally a liquid such as water, through nozzles at sufficiently high pressure to produce a jet stream that disintegrates the constituent building material, normally concrete, of which buildings and structures are made. 
         [0004]    The term “refractory” as used herein refers to heat resistant material. 
         [0005]    The term “refractory-line structure” or “RLS” refers to a pipe, riser, cyclone, boiler, kiln, oven, or other structure having an inner lining made of refractory. 
         [0006]    The terms “cut,” “cutting,” and “cutter,” etc. as used herein refer to the use of hydrodemolition technology to remove refractory from an RLS. 
         [0007]    The use of refractory to line conduits, risers, boilers, cyclones, kilns, and the like is a well known art and essential in many industries. For instance, in the art of fluid catalytic conversion (FCC) of hydrocarbons to produce petroleum products, refractory protects the was of reactor risers from the extreme temperatures required to crack the hydrocarbon feedstocks. 
         [0008]    Because refractory cokes, the working life-time of refractory is limited. Once coking becomes severe it is necessary to remove the coked refractory and replace it with fresh material. Failure to do so results in poor riser hydrodynamics, which causes sub-optimal, inadequate fuel and catalyst mixing. The ultimate result is decreased hydrocarbon conversion and product yield, which increases the price of the petroleum products to consumers. 
         [0009]    Currently, removing coked refractory from RLS&#39;s is an arduous and expensive process for it must be done manually. The material is chipped away by hammers and chisels. For instance, it may take as many as twenty shifts in order to remove coked refractory from a refinery riser. Given that such a refinery may be producing millions of dollars of product per day, the costs of down time for refractory removal also adds significantly to the cost of petroleum products. Consequently, a system and a method are needed to more quickly and efficiently remove refractory from RLS&#39;s, 
         [0010]    The present invention is such as system and method that employs hydrodemolition techniques and novel equipment in order to exploit the power of hydrodemolition. 
       SUMMARY OF THE INVENTION 
       [0011]    In order to address some of the shortcomings in the prior art, some aspects of the present invention provide an apparatus for the removal of refractory material lining the inside surface of a cylindrical structure, the apparatus comprising: a traveler adapted to being received within the structure and being moved along the length of the structure in a manner that allows the traveler to be intentionally moved by an operator; a rotatable nozzle assembly defining an axis of rotation and being connected to the traveler, the nozzle assembly comprising one or more nozzles lines each terminating in a nozzle head that rotates about the axis of rotation, the nozzle assembly being configured in a manner that each nozzle head is suitably spaced from the refractory to be able to deliver a jet of fluid under pressure to the refractory; a nozzle rotation means for rotating the nozzle assembly; and a conduit means in fluid communication with the nozzle assembly suitable for delivering a flow of fluid to the nozzle assembly under sufficient pressure to cut the refractory material lining the structure. 
         [0012]    In some embodiments, the nozzle assembly may be connected to the traveler in a manner that the axis of rotation of the nozzle assembly is approximately coincident with a central axis defined by the structure. 
         [0013]    In some embodiments, the securing assembly may comprise one or more engagement members for contacting the inside surface of the structure or the refractory material, and an extension means cooperating with each engagement member to provide a biasing force to the engagement member towards such contact. 
         [0014]    In some embodiments, the traveler may comprise a frame having at least three engagement members radiating outward from the frame in a manner to position the frame centrally within the structure, and the nozzle assembly being connected to the frame in a manner that the axis of rotation of the nozzle assembly is approximately coincident with the central axis defined by the structure. 
         [0015]    In some embodiments, each engagement member may comprise a skid configured to slide along the refractory material as the apparatus is moved within the structure by an operator. 
         [0016]    In some embodiments, each nozzle head of the nozzle assembly may be approximately equidistant from the axis of rotation. 
         [0017]    In some embodiments, the rotation means may be any one or a combination of the following: an exchanger that is powered by pressurized liquid or gas; an electric motor; a pneumatic motor; and a hydraulic motor. 
         [0018]    In some embodiments, each extension means may be any one or a combination of the following: a spring; a hydraulic extender; and a pneumatic extender. 
         [0019]    In some aspects, the present invention further provides a method of removal of refractory material lining the inside surface of a cylindrical structure, the method comprising the steps of: providing an apparatus in accordance with any of the above described embodiments; placing the apparatus in the structure so that the axis of rotation of the nozzle assembly is approximately coincident with the central axis defined by the structure; applying fluid at a high pressure to the nozzle assembly through the conduit means whereby high pressure jets of the fluid are forced against the refractory through the nozzle heads; and moving the traveler over the refractory in order to cut the refractory with the high pressure jets. 
         [0020]    In some embodiments, fluid is water at pressures between 20,000 p.s.i. and 40,000 p.s.i. 
         [0021]    In some embodiments, the method may further include the step of providing an extension at a terminal end of the structure wherein the extension is adapted to permit the traveler to continue to move within the extension even after the traveler has been moved out of the structure so as to maintain an operative orientation of the nozzle assembly for a distance sufficient to enable the refractory material to be removed up to the terminal end of the structure. 
         [0022]    The foregoing was intended as a summary only and of only some of the aspects of the invention. It was not intended to define the limits or requirements of the invention. Other aspects of the invention will be appreciated by reference to the detailed description of the preferred embodiments. Moreover, this summary should be read as though the claims were incorporated herein for completeness. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    For the better understanding of the present invention and to show more clearly how it may be carried into effect, reference is made by way of example to the accompanying drawings in which: 
           [0024]      FIG. 1  is a cross-sectional view of an embodiment of an apparatus in accordance with the present invention within a cylindrical RLS in which the refractory has been partially removed; 
           [0025]      FIG. 2  is a top view looking down of the apparatus of  FIG. 1  in the vertically oriented RLS, wherein the refractory and RLS appear as concentric rings about a central axis; and 
           [0026]      FIG. 3  is a cross-sectional view of another embodiment of an apparatus in accordance with the present invention within a cylindrical RLS in which the refractory has been partially removed. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0027]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the exemplary embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the invention as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the invention. 
         [0028]    With reference to the figures,  FIG. 1  is a cross-sectional view a cylindrical RLS  100 , with the refractory  101  partially removed.  FIG. 2  is a top view looking down into the vertically oriented RLS  100 , wherein the refractory  101  and RLS  100  appear as concentric rings about a central axis  113 , shown in  FIG. 1 . By way of example, the RLS may be a riser, although the scope of the invention goes well beyond risers to include any type or manner of RLS. As is common in the art, a plurality of anchors  110  extend from the side of the RLS in order to hold and stabilize the refractory. 
         [0029]    The system of the invention includes a rotating nozzle assembly  104  that comprises one or more rigid nozzle lines  112  connected to nozzle heads  105 . The nozzle assembly is caused to rotate about an axis of rotation by a nozzle rotation means  106 . The axis may be approximately coincident or co-extensive with a central axis  113  of the RLS. The rotation means may be an exchanger that is powered by pressurized liquid or gas; it may be an electric motor, pneumatic motor, or hydraulic motor. 
         [0030]    The nozzle assembly and rotation means are carried on a traveler  102 . One function of the traveler is to allow the nozzle assembly to ride within the RLS along the central axis  113 , and thereby keep the nozzle heads  105  properly spaced from the refractory  100  in order to deliver an optimum jet of fluid under to sufficient pressure to cut the refractory. The fluid, which is normally water, is delivered to the nozzle assembly by a conduit means  109 , which may be a pipe or a hose. 
         [0031]      FIG. 2  shows how the traveler comprises a chassis or frame having engagement members such as wheels  103  attached thereto. In the embodiment shown, three sets of wheel assemblies are employed. The wheel assemblies are positioned at approximately 120° intervals about the inner circumference of the RLS  100 . In this way, the center of the traveler, particularly the axis of rotation of the nozzle assembly  104 , can be maintained approximately coincident with the RLS axis  113 . The number of wheel assemblies can vary depending on the shape of the 
         [0032]    RLS so long as there are at least a sufficient number to keep the traveler, particularly the nozzle assembly  104 , approximately centered in the RLS. 
         [0033]    The wheel assemblies may comprise one or more wheels, chassis members, and an extension means, which forces the wheels against the refractory. In  FIG. 1 , spring  107  acts as the extension means by putting pressure against the wheels, forcing them against the refractory. Other devices for effectuating the extension means include hydraulic and pneumatic extenders or shock-absorber devices  201  such as shown in  FIG. 2 . Accordingly, the wheel assemblies together with the extension means provides an embodiment of a securing means on the traveler that secure the traveler within the structure in a manner that allows the traveler to be intentionally moved by an operator. In  FIGS. 1 and 2 , the wheels  103  of the traveler are pressed against the refractory, thereby keeping the traveler centered in the riser. Nozzle line  112  and nozzle head  105  express high pressure fluid supplied by means of conduit  109 . An attachments means such as suspending cable  108  holds the traveler at the appropriate position within the RLS. 
         [0034]    In a vertically oriented RLS, the traveler can be conveniently suspended in the 
         [0035]    RLS and moved up and down by means of an attachment means such as a suspension line  108  connected to a hoist (not shown). The suspension line is attached to an attachment member such as an eye  111  or other attachment point on the traveler. 
         [0036]    The method of using the system to remove refractory from an RLS includes the steps of: 1) providing the system; 2) placing the system in the RLS so that the center of rotation of the nozzle assembly  104  is approximately coincident with the central axis  113 ; 3) applying fluid at a high pressure to the nozzle assembly through the conduit  109  whereby high pressure jets of the fluid are forced against the refractory  101  through the nozzles  105 ; and 4) moving the traveler  102  over the refractory in order to cut the refractory with the high pressure jets. The pressure of the fluid will vary according to the thickness and quality of the refractory. Generally, a pressure of between 20,000 p.s.i. and 40,000 p.s.i. is sufficient. In many situations in which the RLS is vertical it will be preferred to begin the process at the bottom of the RLS and move the traveler upwards. However, in some difficult cases it may be necessary to move the rotating nozzles up and down multiple times over a given length of refractory. 
         [0037]      FIG. 3  shows another embodiment of the apparatus in accordance with the present invention.  FIG. 3  shows the top of the RLS  100  with the traveler  102  just about to complete the removal of the refractory. The traveler  102  in this embodiment has engagement members that comprise skids  300  instead of wheels. Accordingly, the skids together with the extension means provides another embodiment of a securing means on the traveler that secures the traveler within the structure in a manner that allows the traveler to be intentionally moved by an operator. The skids  300  have the advantage of reducing the number of moving parts of the invention. The traveler could employ a combination of skids and wheels. 
         [0038]    Also shown in  FIG. 3  are structure extensions  301 . Such extensions are attached to the RLS and allow the traveler to maintain its orientation along axis  113  even after the traveler has been lifted outside the RLS. The skids or wheels merely is travel along the structure extensions beyond the upper end of the RLS. 
         [0039]    The invention has been described here with respect to a particular, preferred embodiment, Those of skill in the art will recognize that the scope of the invention obviously extends beyond this particular embodiment, For instance, various forms and designs of travelers and different types of nozzle rotators will, upon reading this disclosure, be obvious to those of skill in the art for accomplishing the disclosed functions. While the component elements of the invention well known, these elements perform in a different way to produce a different result that what has been described in, or is obvious from, the existing art. The novel and non-obvious arrangement of those elements results in the unexpected features, functions, uses, and advantages of the invention.