Tundish with filter module

Abstract

A Filter module of a filtering system for a tundish is provided that includes a filter unit provided with channels extending from a channel inlet to a channel outlet, and a wall module with a wall defining an opening extending over an opening height from the floor. A bypass passage is defined between the wall module and the filter module of largest width such that a metal melt can only flow from the inlet portion to the outlet portion by flowing either through the channels of the filter unit or through the bypass passage. The wall module includes a wall ledge having a width. The filter module further includes a filter ledge having a width and being offset vertically relative to the wall ledge to form therewith a baffle.

1 . A tundish ( 10 ) for continuous metal casting, defining a cavity, wherein the cavity has a cavity height (h10) measured along a vertical axis (Z), a cavity length measured along a longitudinal axis (X), and a cavity width measured along a transverse axis (Y), with X⊥Y⊥Z, and wherein the cavity comprises:
 an inlet portion ( 10   i ) configured for receiving a flow of metal melt ( 20   m ) discharged by gravity from an outside of the tundish into the cavity of the tundish; 
 an outlet portion ( 10   o ) comprising an outlet ( 11   o ) configured for discharging the metal melt out of the cavity into a mould; 
 a filtering system separating over the whole cavity width the inlet portion ( 10   i ) from the outlet portion ( 10   o ), the filtering system comprising
 a filter module ( 1 ) extending over the whole cavity width and extending inside said cavity, wherein the filter module comprises an inlet side facing the inlet portion ( 10   i ) of the tundish and extending from a floor ( 10   f ) of the cavity to a top surface whose shortest distance from the floor measured along the vertical axis (Z) is equal to a minimum filter module height (h1), and wherein the filter module ( 1 ) comprises a filter unit ( 1   f ) extending over a filter height (hf) along the vertical axis (Z) and provided with channels ( 1   c ) extending,
 from a channel inlet, opening at an inlet side facing the inlet portion ( 10   i ) of the tundish, 
 to a channel outlet, opening at an outlet side of the filter module ( 1 ) facing the outlet portion and separated from the inlet side by a filter depth (tf), and 
 
 a wall module ( 2 ) comprising a wall extending over the whole cavity width and extending inside said cavity, and defining one or more openings ( 2   o ) distributed over a width of the wall and over an opening height (h2) measured along the vertical axis (Z) from the floor ( 10   f ), 
 wherein the filter module ( 1 ) is arranged closer to the outlet ( 11   o ) than the wall module ( 2 ), and a bypass passage ( 2   b ) is defined between the wall module ( 2 ) and the filter module ( 1 ) of largest width (t12) measured along the longitudinal axis (X), such that the metal melt can only flow from the inlet portion to the inlet side of the filter module ( 1 ) through the one or more openings, and from the one or more openings to the outlet portion by flowing either through the channels of the filter unit ( 1   f ) or through the bypass passage ( 2   b ), and 
 
 wherein, 
 a wall ledge ( 2 L) protrudes from the wall of the wall module ( 2 ) at a wall ledge distance (d2L) from the floor ( 10   f ) not larger than the minimum filter module height (h1) (i.e., d2L≤h1), and extends towards the inlet side of the filter module ( 1 ) without contacting the filter module ( 1 ), the wall ledge ( 2 L) having a width (t2L) measured along the longitudinal axis (X), wherein 20 mm<t2L<t12, 
 a filter ledge ( 1 L) protrudes from the inlet side of the filter module ( 1 ) at a filter ledge distance (d1L) from the floor ( 10   f ) greater than the opening height (h2) (i.e., d1L≥h2), and is offset relative to the wall ledge ( 2 L) (i.e., d1L≠d2L), the filter ledge extending towards the wall module ( 2 ) without contacting either the wall module or the wall ledge, the filter ledge ( 1 L) having a width (t1L) measured along the longitudinal axis (X), wherein 20 mm<t1L<t12, and 
 a ratio ((t1L+t2L)/t12), of the sum of the widths (t1L, t2L) of the filter and wall ledges ( 1 L,  2 L) to the largest width (t12) of the bypass passage ( 2   b ), is higher than 20% (i.e., 0.2≤(t1L+t2L)/t12). 
 
     
     
         2 . The tundish according to  claim 1 , wherein a ratio (h2/h1) of the opening height (h2) to the filter module height (h1) is between 20% and 95% (0.2≤h2/h1≤0.95). 
     
     
         3 . The tundish according to  claim 1 , wherein the ratio ((t1L+t2L)/t12), of the sum of the widths (t1L, t2L) of the filter and wall ledges ( 1 L,  2 L) to the largest width (t12) of the bypass passage ( 2   b ), is lower than 150% (i.e., (t1L+t2L)/t12≤1.5). 
     
     
         4 . The tundish according to  claim 1 , wherein the wall module ( 2 ) comprises a single opening ( 2   o ) extending from a lower boundary separated from the floor ( 10   f ) by a distance of 0% to 5% of the cavity height (h10) to a lower edge of the wall, defining the opening height (h2) as the distance separating the floor from the most remote point of the lower edge. 
     
     
         5 . The tundish according to  claim 1 , wherein the wall module ( 2 ) comprises more than one opening ( 2   o ), wherein a top opening is defined as the opening having a boundary most remote from the floor ( 2   f ), separated from the floor by the opening height (h2). 
     
     
         6 . The tundish according to  claim 1 , wherein a ratio (h2/h10) of the opening height (h2) to the cavity height (h10) is between 10% and 60% (0.1≤h2/h10≤0.6). 
     
     
         7 . The tundish according to  claim 1 , wherein a straight line extending between the floor ( 10   f ) in the inlet portion and the outlet portion passing through the bypass passage ( 2   b ) either,
 does not exist, or   forms an angle (θ) with the vertical axis (Z) of not more than 70°.   
     
     
         8 . The tundish according to  claim 1 , wherein the filter ledge distance (d1L) is larger than the wall ledge distance (d2L) (i.e., d1L>d2L). 
     
     
         9 . The tundish according to  claim 1 , wherein the wall module ( 2 ) comprises more than one wall ledge ( 2 L), parallel to one another, never contacting each other and distributed over a height of the wall module ( 2 ). 
     
     
         10 . The tundish according to  claim 1 , wherein the filter module ( 1 ) comprises more than one filter ledge ( 1 L), parallel to one another, never contacting each other and distributed over a height of the filter module ( 1 ). 
     
     
         11 . The tundish according to  claim 1 , wherein the bypass passage ( 2   b ) imposes an inversion of a flow direction component along the longitudinal axis (X) of the metal melt to flow from the inlet portion ( 10   i ) to the outlet portion ( 10   o ) of the cavity. 
     
     
         12 . The tundish according to  claim 1 ,
 a higher boundary of the filter unit ( 1   f ) is separated from the floor ( 10   f ) by a distance (hf+hd), such that a ratio ((hf+hd)/h2) of the distance ((hf+hd)) to the opening height (h2) is between 0.7 and 1.2 (i.e., 70%≤(hf+hd)/h2≤120%).   
     
     
         13 . The tundish according to  claim 1 , wherein a wall ledge ( 2 L) protrudes from a portion of a width of the wall. 
     
     
         14 . The tundish according to  claim 1 , wherein the filter ledge ( 1 L) protrudes from a portion of a width of the inlet side of the filter module ( 1 ), or a whole width of the inlet side of the filter module ( 1 ). 
     
     
         15 . The tundish according to  claim 1 , wherein a lower boundary of the filter unit ( 1   f ) is separated from the floor ( 10   f ) of the cavity by a lower distance (hd) of between 0 and 10 cm. 
     
     
         16 . The tundish according to  claim 1 , wherein a wall ledge ( 2 L) protrudes from a whole width of the wall.