Insert for a flow through heater

Abstract

When feedback loop control is used for controlling a temperature of liquid at an outlet ( 5 ) of a flow through heater, a volume of an ineffective portion ( 4 ) of the flow through heater at the outlet ( 5 ) constitutes a dead volume which causes a delay in the feedback process. In order to minimize the delay, an insert ( 6 ) is applied, which serves for reducing the dead volume by occupying most of this volume. In a practical case, the insert ( 6 ) comprises a duct system ( 12 ) for conveying liquid from a liquid conveying conduit ( 2 ) of the flow through heater to an outlet ( 10 ) of the insert ( 6 ). Preferably, a volume of such a liquid conveying duct system ( 12 ) is relatively small, so that the presence of the duct system ( 12 ) in the insert ( 6 ) does not spoil the dead volume reducing effect of the application of the insert ( 6 ).

1 . Device for heating liquid, comprising:
 a flow through heater ( 1 ) having a conduit ( 2 ) for conveying liquid and means ( 3 ) for heating the liquid while flowing through the conduit ( 2 );   means ( 7 ) for detecting a temperature of liquid at an outlet ( 5 ) of the flow through heater ( 1 ), which are part of a device for controlling a temperature of liquid at the outlet ( 5 ) of the flow through heater ( 1 ); and   an insert ( 6 ) which is partially inserted in the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ), at an outlet side of the flow through heater ( 1 ), wherein a portion ( 8 ) of the insert ( 6 ) that is located inside the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ) is occupying at least a substantial portion of space which is present in a portion ( 4 ) of the liquid conveying conduit ( 2 ) which is not directly associated with the heating means ( 3 ) of the flow through heater ( 1 ).   
     
     
         2 . Device according to  claim 1 , wherein only little play is present between an inner surface of the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ) and an outer surface of the portion ( 8 ) of the insert ( 6 ) that is located inside the liquid conveying conduit ( 2 ). 
     
     
         3 . Device according to  claim 1 , wherein the insert ( 6 ) comprises a duct system ( 12 ) for conveying liquid from the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ) to an outlet ( 10 ) of the insert ( 6 ), and wherein a diameter of the duct(s) ( 13   a,    13   b,    14 ) of the liquid conveying duct system ( 12 ) is significantly smaller than a diameter of the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ) at the outlet ( 5 ) of the flow through heater ( 1 ). 
     
     
         4 . Device according to  claim 3 , wherein the liquid conveying duct system ( 12 ) of the insert ( 6 ) comprises at least two ducts ( 13   a,    13   b,    14 ) which are oriented at an angle with respect to each other. 
     
     
         5 . Device according to  claim 4 , wherein the liquid conveying duct system ( 12 ) of the insert ( 6 ) comprises at least one duct ( 13   a,    13   b ) for letting in liquid to the duct system ( 12 ), wherein this at least one inlet duct ( 13   a,    13   b ) is oriented substantially perpendicular to a flow direction of liquid in the flow through heater ( 1 ), and is extending from one side of the insert ( 6 ) to another; and a duct ( 14 ) for letting out liquid from the duct system ( 12 ), wherein this outlet duct ( 14 ) is oriented substantially parallel to the flow direction of liquid in the flow through heater ( 1 ), and wherein the at least one inlet duct ( 13   a,    13   b ) and the outlet duct ( 14 ) are connected to each other. 
     
     
         6 . Device according to  claim 3 , wherein the insert ( 6 ) further comprises a duct ( 15 ) which is extending from an outer surface of the insert ( 6 ) to the liquid conveying duct system ( 12 ), in a portion ( 11 ) of the insert ( 6 ) that is located outside of the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ), and wherein the means ( 7 ) for detecting a temperature of liquid at the outlet ( 5 ) of the flow through heater ( 1 ) are associated with this duct ( 15 ). 
     
     
         7 . Device according to  claim 3 , further comprising means ( 16 ) for sealing a space between an outer surface of a portion ( 8 ) of the insert ( 6 ) that is located inside the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ) and an inner surface of the liquid conveying conduit ( 2 ). 
     
     
         8 . Method for increasing accuracy in controlling a temperature of liquid at an outlet of a flow through heater ( 1 ) having a conduit ( 2 ) for conveying liquid and means ( 3 ) for heating the liquid while flowing through the conduit ( 2 ), wherein at least a substantial portion of space which is present in a portion ( 4 ) of the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ) which is not directly associated with the heating means ( 3 ) of the flow through heater ( 1 ) is filled up by providing an insert ( 6 ) and introducing at least a portion ( 8 ) of the insert ( 6 ) into the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ), at an outlet side of the flow through heater ( 1 ). 
     
     
         9 . Method according to  claim 8 , wherein only little play is allowed between an inner surface of the liquid conveying conduit ( 2 ) of the flow through heater ( 1 ) and an outer surface of the portion ( 8 ) of the insert ( 6 ) that is inserted in the liquid conveying conduit ( 2 ).