Heat exchanging element for a heat exchanger, method of manufacturing a heat exchanging element for a heat exchanger, heat exchanger, and retrofitting method for a heat exchanger

Abstract

A heat exchanging element for a heat exchanger is provided with a coating that prevents, or at least reduces, the amount of contaminating materials to be abrade from the heat exchanger and into the heat exchange media. A method for producing a heat exchanging element for a heat exchanger, a heat exchanger per se, and a method for retrofitting an existing heat exchanger, provide for the occurrence of impurities caused by abrasion in one or more heat exchanging media and/or corrosion to be prevented or at least reduced by providing the coating.

1 . A heat exchanging element for a heat exchanger, the heat exchanging element comprising:
 a body containing or essentially consisting of one or more materials selected from the group consisting of graphitic materials, graphites, and open-pored, unsintered silicon carbide materials;   said body being formed with a first contact region and a second contact region for separate contact in terms of flow with a first heat exchanging medium forming a first process medium and with a second heat exchanging medium forming a second process medium, respectively, for effecting separate heat exchange; and   a coating with one or more materials selected from the group of materials consisting of silicon carbide materials, carbide oxide materials, silicide materials, tungsten titanate materials, oxide materials, pyrocarbon, diamond, and derivatives and combinations thereof;   said coating being disposed on at least one of said first and second contact regions and partially or completely coating the respective said contact region.   
     
     
         2 . The heat exchanging element according to  claim 1 , which comprises an impregnation composed of an impregnating material containing or consisting of one or more materials selected from the group consisting of resin materials, phenol resin materials, and derivatives and combinations thereof. 
     
     
         3 . The heat exchanging element according to  claim 2 , wherein said impregnation with the impregnating material is formed entirely or partially on and/or in said coating and/or entirely or partially on and/or in said first contact region and said second contact region. 
     
     
         4 . The heat exchanging element according to  claim 1 , wherein said coating is a CVD coating. 
     
     
         5 . The heat exchanging element according to  claim 1 , wherein said coating is a chemical and/or physical conversion area. 
     
     
         6 . The heat exchanging element according to  claim 5 , wherein said conversion area is formed by a process involving an entire or partial chemical and/or physical conversion of a material forming said first contact region and/or said second contact region. 
     
     
         7 . The heat exchanging element according to  claim 1 , wherein said coating is a plasma-sprayed coating or a flame-sprayed coating. 
     
     
         8 . The heat exchanging element according to  claim 1 , wherein said body is formed as a heat exchanger plate or a recuperator plate of a plate heat exchanger or a plate recuperator. 
     
     
         9 . The heat exchanging element according to  claim 1 , wherein said body is formed as a heat exchanger core or recuperator core of a block heat exchanger or block recuperator. 
     
     
         10 . The heat exchanging element according to  claim 1 , wherein said body is formed as a heat exchanger tube or recuperator tube of a tubular heat exchanger or tubular recuperator. 
     
     
         11 . The heat exchanging element according to  claim 1 , wherein:
 a material of said heat exchanging element body and the material of said coating are coordinated with each other in such a way that   a ratio between a thermal expansion coefficient for the material of the heat exchanging element body and a thermal expansion coefficient for the material of said coating and/or an impregnating material exhibits a value ranging between about 1.2 and about 0.8.   
     
     
         12 . The heat exchanging element according to  claim 11 , wherein the ratio between the thermal expansion coefficients lies within a range of approximately 1.05 and 0.95 in a temperature range from about 1200° C. to about 2400° C. or a partial range thereof. 
     
     
         13 . The heat exchanging element according to  claim 11 , wherein the heat exchanging element body is a graphite substrate and the material of said coating is a CVD-SiC material. 
     
     
         14 . A method of manufacturing a heat exchanging element for a heat exchanger, the method which comprises:
 providing a heat exchanging element body for a separate heat exchange in terms of flow between a first heat exchanging medium as a process medium and a second heat exchanging medium as a service medium with a first contact region and with a second contact region for separately contacting the first heat exchanging medium or second heat exchanging medium in terms of flow;   the heat exchanging element body containing or consisting of one or more materials selected from the group of materials consisting of graphite materials, graphites and open-pored and unsintered silicon carbide materials; and   coating at least one of the first and second contact regions entirely or partially with one or more materials selected from the group consisting of silicon carbide, silicon carbide materials, carbide oxide materials, silicide materials, tungsten titanate materials, and derivatives and combinations thereof.   
     
     
         15 . The method according to  claim 14 , which comprises impregnating the heat exchanging body with an impregnation composed of an impregnating material containing or consisting of one or more materials from the group consisting of resin materials, phenol resin materials and derivatives and combinations thereof. 
     
     
         16 . The method according to  claim 15 , which comprises forming the impregnation with the impregnating material entirely or partially on and/or in the coating and/or entirely or partially on and/or in the first contact region and second contact region. 
     
     
         17 . The method according to  claim 14 , which comprises coating by chemical vapor deposition. 
     
     
         18 . The method according to  claim 14 , wherein the coating step comprises chemically and/or physically converting a material of the first and/or second contact region. 
     
     
         19 . The method according to  claim 14 , wherein the coating step comprises plasma spraying and/or flame spraying. 
     
     
         20 . The method according to  claim 14 , which comprises configuring the heat exchanging element as a heat exchanger plate of a plate heat exchanger, as a recuperator plate of a plate recuperator, as a heat exchanger core of a block heat exchanger, as a recuperator core of a block recuperator, as a heat exchanger tube of a tubular heat exchanger, or as a recuperator tube of a tubular recuperator. 
     
     
         21 . The method according to  claim 14 , which comprises:
 coordinating a material of the heat exchanging element and the material of the coating with each other in such a way that   a ratio between a thermal expansion coefficient for the material of the heat exchanging element body and a thermal expansion coefficient of the material of said coating and/or an impregnating material exhibits a value ranging between about 1.05 and about 0.95 within a temperature range from about 1200° C. to about 2400° C. or a partial range thereof.   
     
     
         22 . The method according to  claim 21 , which comprises forming the heat exchanging element body as a graphite substrate and coating the contact surfaces with a CVD-SiC material coating. 
     
     
         23 . A heat exchanger, comprising: one or more heat exchanging elements according to  claim 1 . 
     
     
         24 . A method of retrofitting a heat exchanger, the method which comprises:
 replacing one or more heat exchanging elements with one or more heat exchanging elements according to  claim 1 ; and/or   converting one or more conventional heat exchanging elements into one or more heat exchanging elements by   providing one or more heat exchanging element bodies containing or consisting of one or more materials selected from the group of materials consisting of graphite materials, graphites and open-pored and unsintered silicon carbide materials, and   coating at least one of the first and second contact regions entirely or partially with one or more materials selected from the group consisting of silicon carbide, silicon carbide materials, carbide oxide materials, silicide materials, tungsten titanate materials, and derivatives and combinations thereof.