Pump Casing

Abstract

The invention relates to a pump housing ( 2 ) comprising a dual-wall casing ( 3 ) which enables a first fluid ( 4 ) to flow at least partially around a compression chamber ( 5 ) for compressing a second fluid ( 6 ), said compression being performed with at least two elongated rotors ( 7, 8 ). The dual-wall casing ( 3 ) comprises: (i) a first wall ( 10 ) which defines the volume of the compression chamber ( 5 ), and (ii) a second wall ( 11 ) which extends around the first wall ( 10 ) at a distance ( 12 ) from same such as to enable the first fluid ( 4 ) to flow therethrough. The pump housing ( 2 ) consists of two subassemblies ( 13, 14 ), namely a first subassembly ( 13 ) and a second subassembly ( 14 ), which are assembled along a sealing surface ( 15 ) that is essentially orthogonal to the longitudinal axes ( 70, 80 ) of the rotors ( 7, 8 ). Both the first subassembly ( 13 ) and the second subassembly ( 14 ) are characterised in that they consist of a rigid element ( 16 ) which is moulded from a first thermally-conductive material and which comprise two opposing faces, namely a first face ( 18 ) and a second face ( 19 ). According to the invention, the above-mentioned first wall ( 10 ), which is moulded with the rigid element ( 16 ), is disposed beyond the first face ( 18 ) such as to extend essentially orthogonally thereto, while the second wall ( 11 ) is also disposed beyond the first face ( 18 ) such as to extend essentially orthogonally thereto, but in parallel to a fourth face ( 21 ) of the first wall ( 10 ) without being joined to same. In addition, cut-outs ( 23 ) are recessed into the first face ( 18 ) such that each cut-out forms at least one housing for a first member ( 9 ) that is used to guide the rotation of one of the opposing ends ( 71, 72, 81, 82 ) of one of the rotors ( 7, 8 ).

1 . Pump casing having a double-walled shell which permits the circulation of a first fluid, in particular a heat-transfer medium, at least partially about a chamber of compression of a second fluid, the compression being accomplished by means of at least two elongated rotors, which, having longitudinal axes, are situated in said compression chamber,
 the rotors being guided in rotation about their longitudinal axes by the elements, referred to as first elements for guiding in rotation, positioned at the level of opposite ends which these rotors comprise,   the double-walled shell having, on the one hand, a first wall which determines the volume of the compression chamber, and, on the other hand, a second wall which extends around the first wall with a certain spacing intended for the circulation of the first fluid,   said pump casing being made up of two subassemblies, referred to as first and second, which are assembled along a joint face substantially orthogonal to the longitudinal axes of the rotors,   each first subassembly and second subassembly being characterized in that it comprises a rigid element which, cast in a first thermally conducting material, has two opposite faces, being a first face and a second face, with   situated beyond the first face,   on the one hand, the first wall which, cast with this rigid element, extends substantially orthogonally to said first face and is
 transversally delimited between two opposite faces, referred to as third face and fourth face, the third face delimiting the compression chamber laterally, the fourth face constituting a surface of exchange with the first fluid, 
 longitudinally limited by a fifth face which defines at least one bearing area for joining with the fifth face of a first subassembly or second subassembly with which it must be joined along the joint face in a manner so as to constitute a pump casing, 
   on the other hand, the second wall which extends substantially orthogonally to said first face and parallel to the fourth face of the first wall, while being without any connection to said fourth face,   situated set back with respect to the first face, cutouts which each constitute at least one accommodation for a first element for guiding in rotation of one of the opposite ends of one of the rotors.   
   
   
       2 . Pump casing according to  claim 1 , wherein on at least one of said first and second subassemblies, the first wall is connected to the rigid element which bears it through a connecting part which elicits a displacement of said first wall in a first direction substantially orthogonal to the joint face, and this by elastic deformation of said connecting part. 
   
   
       3 . Pump casing according to  claim 1 , wherein each cutout situated set back with respect to the first face, likewise constitutes an accommodation for a second element intended to ensure the tightness between each of the opposite ends of an elongated rotor and the rigid element in which the cutout under consideration is situated. 
   
   
       4 . Pump casing according to  claim 1 , wherein the first subassembly and the second subassembly constituting the pump casing are joined by means of third elements which pull the one toward the other in a manner so as to apply tightly, one against the other, the fifth faces of the rigid elements of each first subassembly and second subassembly. 
   
   
       5 . Pump casing according to  claim 4 , wherein the first subassembly and the second subassembly constituting the pump casing are joined by means of third elements consisting of tension rods which:
 each extend in a second direction substantially orthogonal to the joint face and of which at least certain ones pass through the space situated between the first wall and the second wall of each first subassembly and second subassembly,   find support at the level of the second face of each rigid element which comprises one of said first and second subassemblies.   
   
   
       6 . Pump casing according to  claim 1 , wherein:
 the first subassembly and the second subassembly constituting the pump casing are joined by means of third elements which pull said first and second subassemblies, one toward the other, in a manner so as to apply tightly, one against the other, the fifth faces of the rigid elements of each first subassembly and second subassembly,   the second wall of each first subassembly and second subassembly extend beyond the first face and comprise a face which, referred to as the sixth face, extends in a second plane parallel to the fifth face of the same first or second subassembly, but set back with respect to this fifth face, in a manner such that when the fifth faces of the first subassembly and of the second subassembly rest one against the other, the sixth faces of these subassemblies are spaced apart by a predetermined value “E”, such that an interstice remains between them.   
   
   
       7 . Pump casing according to  claim 6 , wherein:
 at least one of the fifth faces of the first subassembly and of the second subassembly which rest one against the other, bears at least one first gasket which co-operates with the other fifth face and ensures the peripheral tightness of the compression chamber at the level of the two fifth faces placed resting one against the other,   at least one of the sixth faces of the first subassembly and of the second subassembly which are situated vis-à-vis, rest one against the other through the agency of at least one second gasket which ensures the peripheral tightness of the space situated between the first wall and the second wall, in spite of the interstice of predetermined value “E” which remains between these sixth faces.   
   
   
       8 . Pump casing according to  claim 1 ,wherein the bearing area for joining constituted by the fifth faces of two first and second subassemblies intended to be joined have complementary elements of transversal positioning, male and female, in such a way as to enable the relative transversal positioning of the two first and second subassemblies. 
   
   
       9 . Pump casing according to  claim 1  and intended to accommodate at least two elongated rotors, the longitudinal axes of which are situated in a same plane, wherein the bearing area for joining made up of the fifth face of each first or second subassembly has two complementary elements of transversal positioning, male and female, which are situated in said third plane. 
   
   
       10 . Pump casing according to  claim 1 , wherein the first and the second subassemblies, which it comprises, are composed such that the joint face is situated at between a quarter and three quarters of the distance which separates the first faces opposite said joined first and second subassemblies. 
   
   
       11 . Pump casing according to  claim 1 , wherein the first and the second subassemblies which it comprises are composed such that the joint face is situated substantially in the middle of the distance which separates the first faces opposite said joined first and second subassemblies. 
   
   
       12 . Pump casing according to  claim 1  and having at least one first channel which permits the injection into the chamber of a third fluid, referred to as dilution fluid, and this from the exterior of the chamber, this body being wherein at least this first channel intended to route the third fluid, introduced through an entry situated in the rigid element and expelled into the compression chamber through at least one exit orifice situated at the level of the third face, is made in the thickness of said first wall. 
   
   
       13 . Pump casing according to  claim 1 , wherein the second wall of each first and second subassembly is formed by molding from a cast (duplicate molding). 
   
   
       14 . Pump casing according to  claim 1 , wherein the second wall of each first and second subassembly is formed by duplicate molding of a second material identical to the first material constituting the first wall. 
   
   
       15 . Pump casing according to  claim 1 , wherein the second wall of each first and second subassembly is formed by duplicate molding of a second material different from the first material constituting the first wall. 
   
   
       16 . Pump casing according to  claim 1  and intended to house two elongated rotors disposed parallel in the compression chamber, said compression chamber comprising a first orifice for admission of the second fluid and a second orifice for outflow of said second fluid characterized in that the rigid element of each first and second subassembly comprises a second channel which opens out into the first face through an aperture which, constituting one of said first orifice or second orifice, is provided with a plane of symmetry which is, on the one hand, situated at mid-distance between the longitudinal axes of the elongated rotors and, on the other hand, perpendicular to the third plane which contains the longitudinal axes of said rotors. 
   
   
       17 . Pump casing according to  claim 16 , wherein the second channel is determined by transverse sections which each have a plane of symmetry that is, on the one hand, situated at mid-distance between the longitudinal axes of the elongated rotors and, on the other hand, perpendicular to the third plane which contains the longitudinal axes of said rotors. 
   
   
       18 . Pump casing according to  claim 1 , wherein each first and second subassembly which it comprises possesses a plane of symmetry which is, on the one hand, situated at mid-distance between the longitudinal axes of the elongated rotors and, on the other hand, perpendicular to the third plane which contains the longitudinal axes of said rotors. 
   
   
       19 . Pump casing according to  claim 1 , wherein the second orifice for outflow of the second fluid is well formed and disposed in the subassembly which comprises it in a way so as to permit removal by gravity of any condensates situated in the lower part of the compression chamber. 
   
   
       20 . Pump comprising a pump casing according to  claim 1 .