Temperature control system

Abstract

Temperature controllers are provided which employ a control element of variable area containing flowing heat transfer fluid. The area of the element available for temperature control is changed by opening and closing a bank of conduits in a cascade and the conduits are opened and closed according to a temperature measuring device in the medium whose temperature is to be controlled.

1 . A temperature control system comprising: a control element of variable area containing flowing heat transfer fluid wherein the area available is changed by opening and closing a bank of conduits in a cascade in which the conduits are opened and closed according to a temperature measuring device in the medium whose temperature is to be controlled.  
     
     
         2 . The temperature control system according to  claim 1  in which the heat transfer fluid flows with a Reynolds number greater than 2000.  
     
     
         3 . The temperature control system according to  claim 1  wherein the area of a heat transfer element that is available and the flow are controlled to provide a substantially constant thermal gradient between the process fluid and the heat transfer fluid.  
     
     
         4 . The temperature control system according to  claim 1 , wherein a Log mean thermal difference (LMTD) is greater than or equal to 1° C.  
     
     
         5 . The temperature control system according to  claim 4 , wherein the LMTD is greater than or equal to 10° C.  
     
     
         6 . The temperature control system according to  claim 5 , wherein the LMTD is greater than or equal to 20° C.  
     
     
         7 . The temperature control system according to  claim 6 , wherein the LMTD is greater than or equal to 100° C.  
     
     
         8 . The temperature control system according to  claim 1 , wherein the bank of conduits comprises a series of coils.  
     
     
         9 . A temperature control system according to  claim 8  in which the individual coils are sized according the following formula:  
         A=m.Cp .( tsi−tso )/( U.LMTD )  
       Where Q=designated nominal design load per coil (W) 
 U=overall heat transfer coefficient (W.m −1 .K −1 )  
 A=heat transfer area of the coil (m 2 )  
 (tsi−tso)=designated nominal temperature change in the heat transfer fluid between inlet and outlet. (° C.)  
 LMTD=Log mean thermal difference between the process and heat transfer fluid (C)  
 
     
     
         10 . The temperature control system according to  claim 9 , wherein the heat transfer fluid temperature (tsi−tso) rises by 0.01° C. or more.  
     
     
         11 . The temperature control system according to  claim 10 , wherein the heat transfer fluid temperature (tsi−tso) rises by 0.1° C. or more.  
     
     
         12 . The temperature control system according to  claim 11 , wherein the heat transfer fluid temperature (tsi−tso) rises by 1° C. or more.  
     
     
         13 . The temperature control system according to  claim 12 , wherein the heat transfer fluid temperature (tsi−tso) rises by 10° C. or more.  
     
     
         14 . The temperature control system according to  claim 1 , wherein the linear velocity of the heat transfer fluid is greater than 0.1 ms −1    
     
     
         15 . A temperature control system according to  claim 1 , wherein a linear velocity of the heat transfer fluid is greater than 1 ms −1 .  
     
     
         16 . The temperature control system according to  claim 15 , wherein the linear velocity of the heat transfer fluid is greater than 3 ms −1 .  
     
     
         17 . The temperature control system according to  claim 16 , wherein the linear velocity of the heat transfer fluid is greater than 5 ms −1 .  
     
     
         18 . A temperature control system which comprises a control element of variable area containing flowing heat transfer fluid wherein the area available is changed by opening and closing a bank of conduits in a cascade in which the conduits are opened and closed according to a temperature measuring device in the medium whose temperature is to be controlled, said system has sufficiently high resolution to enable a disturbance or deviation in the temperature of the process media to detected at a rate that will allow a real time correction to be made in the flow rate and heat transfer area such that the said disturbance or deviation results in a relatively minor change in the process temperature.  
     
     
         19 . The temperature control system according to  claim 1 , wherein said system can respond to a change in load of a process fluid within less than 2 seconds.  
     
     
         20 . The temperature control system according to  claim 19 , wherein said system can respond to a change in load of the process fluid within less than 10 seconds.  
     
     
         21 . The temperature control system according to  claim 3 , wherein the nominal capacity of said heat transfer element is not more than 0.1 Watt.  
     
     
         22 . The temperature control system according to  claim 21 , wherein the nominal capacity of said heat transfer element is not more than 1 Watt.  
     
     
         23 . The temperature control system according to  claim 22 , wherein the nominal capacity of said heat transfer element is not more than 10 Watts.  
     
     
         24 . The temperature control system according to  claim 23 , wherein the nominal capacity of heat transfer element is not more than 100 Watts.  
     
     
         25 . The temperature control system according to  claim 24 , wherein the nominal capacity of said heat transfer element is not more than 1000 Watts.  
     
     
         26 . The temperature control system according to  claim 25 , wherein the nominal capacity of said heat transfer element is not more than 10000 Watts.  
     
     
         27 . The temperature control system according to  claim 26 , wherein the nominal capacity of said heat transfer element is not more than 100000 Watts.