Patent Publication Number: US-2022235686-A1

Title: Housing for a selective catalyst reactor, a kit of parts and a method

Description:
The invention relates to a housing for a selective catalyst reactor. 
     Combined heat and power systems, also known as CHP systems or cogeneration systems generate heat and power from the same energy source. Typically, a combustion engine running on gas or another fossil type fuel generates both heat and power for powering and heating large structures such as greenhouses, hospitals or universities. 
     Selective catalyst reactors are known for cleaning exhaust gases from a combustion engine of such a CHP system. In use, a selective catalyst reactor cleans exhaust gases by removing nitrogen oxides and related pollution gases. In this process, the exhaust gas is forced to flow along and through a catalyst such as palladium for generating a desired chemical reaction. 
     It appears, in practice, that selective catalyst reactor housings are relatively complex and expensive in construction due to specific requirements to dimensions, e.g. depending to the power of the combustion engine. Typically, a selective catalyst reactor housing is custom sized according to engine output parameters. 
     It is an object of the present invention to provide a housing for a selective catalyst reactor for processing exhaust gas from a combustion engine of a combined heat and power system that is easy to construct and/or less expensive. Thereto, according to the invention, a housing for a selective catalyst reactor for processing an exhaust gas from a combustion engine of a combined heat and power system is provided, the housing comprising an annular shaped plate structure forming an elongate accommodation wall defining an inner accommodation volume for containing a catalyst to be flown through by the exhaust gas, wherein the annular shaped plate structure includes a set of plate elements having the same, mainly the same or similar geometry and dimensions. 
     By applying plate elements have a standardized geometry and dimensions, a single type of plate element can be used for constructing a selective catalyst reactor housing. Then, the base element can be manufactured relatively easily in relatively large amounts, leading to lower cost price, while maintaining the flexibility of constructing selective catalyst reactors in a wide variety of sizes and geometries. 
     The set of plate elements may form corner elements of the annular  10  shaped plate structure. Then, the annular shaped plate structure may be formed by four corner elements mounted together. As an example, the corner elements may have a folded profile formed from a flat plate element. 
     Advantageously, the annular shaped plate structure may include an additional set of plate elements having the same, mainly the same or similar geometry, as a second set of plate elements having the same, mainly the same or similar geometry and dimensions. The plate elements of the second set may form intermediate plate elements located between adjacent corner elements. As an example, the intermediate elements may be generally rectangular shaped and mainly flat. By applying the intermediate plate elements, larger annular shaped plate structure can be formed. 
     Further, the annular shaped plate structure may include at least one window module provided with a movable window element, forming a third set or type of plate elements for forming the annular shaped plate structure. 
     Preferably, the corner elements and optionally the intermediate elements and/or the at least one window module are provided, along their circumferential contour, with an upstanding flange contacting a corresponding flange of an adjacent corner element, intermediate plate element or window module, thereby simplifying a method of constructing the annular shaped plate structure. 
     Advantageously, the corner elements, optionally with the intermediate elements and/or the at least one window module are arranged and mounted next to each other in a circumferential direction for forming the annular shaped plate structure, thus providing a simple and reliable construction technique. 
     Optionally, the housing for a selective catalyst reactor includes a single or a multiple number of annular shaped plate structures, preferably constructed using the standardized plate elements. 
     Further, the housing for a selective catalyst reactor may include a stiffening intermediate plate including a frame having the same, mainly the same or similar dimensions as the at least two annular shaped plate structures, in cross sectional view, the stiffening intermediate plate being provided with stiffening elements forming flow openings for accommodating the catalyst. The grating intermediate plate may be arranged between two adjacent annular shaped plate structures, aligned along a common longitudinal axis. 
     In addition, the housing for a selective catalyst reactor may include a gas inlet section formed as truncated cone having a proximal end with a relatively small entry opening for connection with an exhaust tube of the combustion engine, and a distal end with a relatively large exit opening for connection with an annular shaped plate structure or stiffening intermediate plate. Preferably, the entry opening of the truncated cone is eccentric relative to the exit opening of the truncated cone so as to provide an optimal flow characteristic of the exhaust gas. 
     It is noted that in this context the expression same, mainly the same or similar is to be understood as indicating that deviations are relatively small, e.g. smaller than circa 10%, smaller than circa 5% or even smaller, e.g. smaller than circa 2% or smaller than 1%. 
     Also, the invention relates to a kit of parts. 
     Further, the invention relates to a method for constructing a housing for a selective catalyst reactor. 
     Further advantageous embodiments according to the invention are described in the following claims. 
     It should be noted that the technical features described above or below may each on its own be embodied in a system and/or in a method, i.e. isolated from the context in which it is described, separate from other features, or in combination with only a number of the other features described in the context in which it is disclosed. Each of these features may further be combined with any other feature disclosed, in any combination. 
    
    
     
       The invention will now be further elucidated on the basis of a number of exemplary embodiments and an accompanying drawing. In the drawing: 
         FIG. 1  shows a schematic exploded perspective view of a housing for a selective catalyst reactor according to the invention; 
         FIG. 2A  shows a schematic exploded perspective view of an annular shaped plate structure of the housing for a selective catalyst reactor shown in  FIG. 1 ; 
         FIG. 2B  shows a schematic perspective view of a corner element, two intermediate elements and a window module of the annular shaped plate structure shown in  FIG. 2A ; 
         FIG. 2C  shows a schematic perspective view of an alternative embodiment of corner elements for implementation in the annular shaped plate structure shown in  FIG. 2A ; 
         FIG. 3  shows a schematic exploded perspective view of another housing according to the invention; 
         FIG. 4  shows a schematic exploded perspective view of an annular shaped plate structure of the housing shown in  FIG. 3 ; 
         FIG. 5  shows a schematic perspective view of a gas inlet section of a housing as shown in  FIG. 1 or 3 . 
         FIG. 6  shows a flow chart for a method according to the invention for constructing a housing for a selective catalyst reactor. 
     
    
    
     It is noted that the figures show merely preferred embodiments according to the invention. In the figures, the same reference numbers refer to equal or corresponding parts. 
       FIG. 1  shows a schematic exploded perspective view of a housing for a selective catalyst reactor  1 , also referred to as SCR device, according to the invention. The reactor  1  is arranged for processing an exhaust gas from a combustion engine of a combined heat and power system, also referred to as CHP system or cogeneration system generating heat and power from the same energy source such as a combustion engine running on gas or another fossil type fuel serving as a greenhouse gasses GHG mitigation option. 
     Typically, a selective catalyst reactor  1  is provided with a catalyst such as palladium that is exposed to the exhaust gas of the combustion engine for removing nitrogen oxides and related pollution gases thus cleaning the exhaust gas. 
     The housing of the SCR  1  shown in  FIG. 1  comprises a multiple number of annular shaped plate structures  2   a,b,c  arranged in series aligned along a common longitudinal axis L for forming an elongate accommodation wall defining an inner accommodation volume  3  for containing a catalyst to be flown through by the exhaust gas G in  entering the accommodation volume  3  from the right and leaving G ex  the accommodation volume  3  from the left. 
     According to an aspect of the invention, the annular shaped plates  2   a - c  structures each include a set of plate elements  4 ″ having the same, mainly the same or similar geometry and dimensions, and an additional set of plate elements  4 ″ having the same, mainly the same or similar geometry and dimensions. By using plate elements  4 ′.  4 ″ that have been standardized in geometry and dimensions or sizes, a large variety of SCRs can be constructed from the same standardized base units, the plate elements  4 ′,  4 ″. 
     Further, the annular shaped plate structures  2   a - c  in  FIG. 1  each includes a window module  5 ′ having a movable window element  5 ″, e.g. for loading and/or unloading catalyst blocks in the accommodation volume  3 , and/or for inspection purposes. The movable window element  5 ″ can be selectively removed or opened by loosing butterfly nuts  6 . In other implementations, another fixation technique can be applied for providing a movable window element  5 ″ with a structure allowing for pivotal and/or slidable movement. 
     The plate elements  4 ′ of the first set form corner elements of the annular shaped plate structures  2   a - c . Typically, the corner elements  4 ′ are located at corners of the annular shaped plate structures  2   a - c.    
     The plate elements  4 ″ of the second or additional set form intermediate elements located between adjacent corner elements  4 ′ of the annular shaped plate structures allowing housing designs having relatively large dimensions. 
     The window module  5 ′ forms an optional third type of element that is used for constructing the housing for the annular shaped plate structures  2   a - c.    
     As shown in  FIG. 1 , the corner elements  4 ′, intermediate elements  4 ″ and the window module  5 ′ are arranged and mounted next to each other in a circumferential direction C for forming the respective annular shaped plate structures  2   a - c . The intermediate elements  4 ″ are generally rectangular so as to facilitate an easy mounting process, e.g. using a welding technique. However, in principle, other geometries are applicable for the plate elements  4 , e.g. a triangular shape. 
     In the shown embodiment, the plate elements  4  are generally flat. In practice, the plate elements  4  may have another shape, e.g. slightly curved. Further, in the shown embodiment, the plate elements  4  have edge portions  4   a  extending generally transverse to the generally flat plane wherein the plate element  4  generally extends further simplifying a reliable mounting process. 
     Generally, the annular shaped plate structures  2   a - c  form closed loops for enclosing the accommodation volume  3  sidewardly. 
       FIG. 2A  shows a schematic exploded perspective view of an annular shaped plate structure  2   a - c  of the housing for a selective catalyst reactor  1  shown in  FIG. 1 , clearly showing the individual corner elements  4 ′, intermediate elements  4 ″ and the window module  5 ′. 
     Due to the use of the standardized plate elements  4 ′,  4 ″ and the window module  5 , the annular shaped plate structures  2  have the same, mainly the same or similar dimensions or sizes in the longitudinal direction L. Then, the annular shaped plate structures  2  can be easily arranged in series as a concatenation of structures defining an inner accommodation volume having constant or mainly constant cross sectional dimensions. 
       FIG. 2B  shows a schematic perspective view of a corner element  4 ′, two intermediate elements  4 ″ and a window module  5 ′ of the annular shaped plate structure shown in  FIG. 2A , in a de-assembled state. 
     The corner element  4 ′ has a folded profile with two plate shaped elements  41 ,  42  mutually connected via a folding line  43 . The two plate shaped elements  41 ,  42  are mainly transversely oriented with respect to each other. It is noted that the corner element  4 ′ may have another geometry. 
     The intermediate elements  4 ″ shown in  FIG. 2B  are generally flat having a rectangular shape. 
     The window module  5 ′ has a movable window element  5 ″ and hinge elements  5 ′″ allowing the movable window  5 ″ element to swivel. 
     As shown in  FIG. 2B  the corner element  4 ′, the intermediate elements  4 ″ and the window module are provided, along their circumferential contour RC, with an upstanding flange  4   a  contacting, in assembled state, a corresponding flange  4   a  of an adjacent corner element  4 , intermediate element  4 ″ or window module  5 ′. 
       FIG. 2C  shows a schematic perspective view of an alternative embodiment of corner elements  50 ,  51  for implementation in the annular shaped plate structure shown in  FIG. 2A . Each of the corner elements  50 ,  51  in  FIG. 2C  has a plate shaped basis  53 ,  54  provided, along a major part of its rectangular contour RC, with an upstanding flange  55 ,  56 . A remaining part of the rectangular contour RC, a single side of said rectangular contour RC extending in the longitudinal direction L is provided with an inclined flange  57 ,  58  oriented circa 135 degrees with respect to the plate shaped basis  53 ,  54  such that the inclined flanges  57 ,  58  contact each other, in assembled state, forming, together, a mainly orthogonal corner module. 
     Turning back to  FIG. 1 , the three annular shaped plate structures  2   a - c  have the same, mainly the same or similar geometry, i.e. a rectangular geometry such as a square geometry, in cross sectional view, the structures having a width dimension W and a height dimension H. Here, the width dimension W and the height dimension H, respectively, of the three annular shaped plate structures  2  are the same, mainly the same or similar, thereby contributing to a uniform structure of the housing of the SCR  1 . In principle, the width dimension W and the height dimension H may differ, e.g. if a locally higher segment of the housing of the SCR is desired. Further, a non-rectangular geometry may be applied, e.g. a triangular geometry. Also, theoretically, a specific annular shaped plate structure may have a deviating geometry such as a pentagon or another polygon. 
     It is noted that, generally, a cross sectional view is to be understood as a view along the longitudinal axis L, i.e. from a section transverse to said longitudinal axis L. 
     The shown housing for the SCR  1  further comprises four stiffening intermediate plates  7  including a frame  8  having the same, mainly the same or similar dimensions as annular shaped plate structures  2   a - c , in cross sectional view, the stiffening intermediate plate  7  further including stiffening elements  9  forming flow openings  10 . The flow openings  10  serve as a flow guiding optimization structure guiding the exhaust gas G in  flow through the inner accommodation volume  3  of the housing  1  in an optimized manner. 
     The stiffening intermediate plates  7  are generally arranged between two neighboring annular shaped plate structures  2 , aligned along the common longitudinal axis L. In the shown example, a first grating intermediate plate  7   a  is located to the left of the first annular shaped plate structure  2   a , while a fourth stiffening intermediate plate  7   d  is located to the right of the third annular shaped plate structure  2   c.    
     It is noted that, in principle, the housing of the SCR  1  can also be provided without stiffening intermediate plates, e.g. if a single annular shaped plate structure  2  is applied. 
     It is noted that instead of three annular shaped plate structures  2   a - c , another number of plate structures can be applied, such as a single annular shaped plate structure or two, four or five annular shaped plate structures. Further, all plate structures can be formed with same, mainly the same or similar dimensions using the standardized plate elements  4 ′,  4 ″. However, a subset of the annular shaped plate structures may be formed in another way, e.g. when a specific geometry or size is desired and/or dedicated material is to be used. In the shown embodiment, a third annular shaped plate structure  2   a , at the right hand side in  FIG. 1 , may be used for performing a first gas cleaning process, while a second annular shaped plate structure  2   b , at an intermediate position in  FIG. 1 , may be used for mixing purposes, and a first annular shaped plate structure  2   c , at the left hand side in  FIG. 1 , may be used for a second gas cleaning process. 
     The stiffening intermediate plates  7  are generally arranged between two neighboring annular shaped plate structures  2 , aligned along the common longitudinal axis L. In the shown example, a first stiffening intermediate plate  7   a  is located to the left of the first annular shaped plate structure  2   a , while a second stiffening intermediate plate  7   b  is located between the first and the second annular plate shaped plate structure  2   a;b , while a third stiffening intermediate plate  7   b  is located between the second and the third annular plate shaped plate structure  2   b;c , and a fourth stiffening intermediate plate  7   d  is located at the right of the third annular plate shaped plate structure  2   c.    
       FIG. 3  shows a schematic exploded perspective view of another housing  1  according to the invention, while  FIG. 4  shows a schematic exploded perspective view of an annular shaped plate structure  2   a - c  of the housing that is shown in  FIG. 3 . Here, the annular shaped plate structures  2   a - c  have been formed from corner elements  4 ′ and intermediate elements  4 ″ only, without the window module  5 ′ provided in the annular shaped plate structures of the embodiment shown in  FIGS. 1 and 2 . The housing  1  shown in  FIG. 3  and  FIG. 4  can be used for various types of units processing exhaust gas from a combustion engine of a combined heat and power system, including a heat exchange unit or a pre-mixing tube unit. 
       FIG. 5  shows a schematic perspective view of a gas inlet section  10  of a selective catalyst reactor housing  1  as shown in  FIG. 1 or 3 . The gas inlet section  10  is formed as truncated cone having a proximal end  11  with a relatively small entry opening  12  for connection with an exhaust tube of the combustion engine, for receiving an exhaust gas flow F MT  from a mixing tube, and a distal end  13  with a relatively large exit opening  14  for connection with an annular shaped plate structure  2   c  or a stiffening intermediate plate  7   d  of the housing  1 , for inducing an exhaust gas flow F SCR  into the housing  1 . In the shown embodiment, the entry opening  12  of the truncated cone  10  is eccentric relative to the exit opening  14  of the truncated cone  10 , as entry opening  12  is not aligned with the longitudinal axis L of the housing  1 . 
     It is noted that the shown gas inlet section  10  is optional. In principle, another gas inlet section can be applied to conduct exhaust gas from the combustion engine to the housing  1 , e.g. using a gas inlet section having an entry opening  12  that is aligned with the longitudinal axis L of the housing  1 , or using a gas inlet section having a staggered profile. 
     According to an aspect of the invention, a kit of parts can be provided for constructing a housing for a selective catalyst reactor  1 , the kit of parts comprising a set of plate elements  4  having the same, mainly the same or similar geometry and dimensions for being arranged and mounted next to each other in a circumferential direction C for forming an annular shaped plate structure  2  of the housing  1 . 
     The set of plate elements in the kit of parts may form corner elements for the annular shaped plate structure, the kit of parts optionally including intermediate plate elements to be located between adjacent corner elements in the annular shaped plate structure, the kit of parts further optionally including at least one window module provided with a movable window element. 
       FIG. 6  shows a flow chart for a method according to the invention for constructing a housing for a selective catalyst reactor  1 . The method  100  includes a step of providing  110  a kit of parts and a step of arranging and mounting the corner elements and optionally the intermediate elements and/or the at least one window module next to each other in a circumferential direction C for forming an annular shaped plate structure  2  of the housing  1 . 
     The step of arranging and mounting the respective elements may include a sub-step of provisionally fixing the respective elements to each other using provisional fixation elements such as a blind rivet, a sub-step of placing the provisionally fixed annular shaped plate structure in a mould or template, and a sub-step of permanently fixing the respective elements to each other. 
     It is noted that other sub-steps or techniques may be applicable, replacing at least one of the above described sub-steps or in addition to the above sub-steps. 
     The invention is not restricted to the embodiments described above. It will be understood that many variants are possible. 
     These and other embodiments will be apparent for the person skilled in the art and are considered to fall within the scope of the invention as defined in the following claims. For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments. However, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.