Abstract:
A wireless temperature sensor for use in monitoring the temperature of a fluid or gas in a mixing vessel. The wireless temperature sensor comprises a temperature probe for contacting the fluid or gas and generating a signal based on the gas/fluid temperature; a temperature reader for receiving the signal generated by the temperature probe and determining therefrom a temperature reading of the fluid or gas; and a radio frequency (RF) transceiver for transmitting the temperature reading determined by the temperature reader to a control apparatus external to the mixing vessel.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present application relates generally to process control system and, more specifically, to a wireless temperature probe for measuring temperatures of a fluid or gas and wirelessly transmitting the measurements to a control system. 
     BACKGROUND OF THE INVENTION 
     Processing facilities are typically managed using process control systems. Among other functions, these control systems often regulate the temperature of materials, particularly fluids and/or gases, undergoing a catalytic process in a mixing vessel in the processing facilities. For example, the temperature may be controlled by measuring the temperature of a fluidized bed of catalyst and increasing or decreasing the flow rate(s) of material(s) into the mixing vessel in order to raise or lower the temperature. Exemplary processing facilities include manufacturing plants, chemical plants, oil refineries, and ore processing plants, among others. 
     Conventional process control systems typically measure the temperature of a fluid or gas in a mixing vessel by means of a temperature probe that contacts the gas or the surface of the fluid. Alternatively, the temperature probe may be placed in the wall of the mixing vessel and contact the outer perimeter of the gas or fluid. However, neither of these arrangements provides an accurate temperature profile in a process reactor that has a fluidized bed of catalyst. These types of processes are often exothermic or endothermic in nature and a substantial difference in temperature may exist between the center region of the catalytic material and the surface or outer perimeter of the gas or fluid. However, due to high temperatures and/or the corrosiveness of materials in the mixing vessel, it may not be practical to place a temperature probe in the interior region of the mixing vessel and run wiring to the control system on the exterior of the mixing vessel. 
     Therefore, there is a need in the art for improved apparatuses and methods for measuring the temperature of materials in a processing system. In particular, there is a need for a temperature probe that can measure temperatures in a fluidized bed of catalytic materials in the interior of a mixing vessel without requiring extensive wiring to communicate with a control system on the exterior of the mixing vessel. 
     SUMMARY OF THE INVENTION 
     To address the above-discussed deficiencies of the prior art, it is a primary object to provide a wireless temperature sensor for use in monitoring the temperature of a fluid or gas in a mixing vessel. The wireless temperature sensor comprises: 1) a temperature probe for contacting the fluid or gas and generating a signal according to the temperature of the fluid or gas; 2) a temperature reader for receiving the signal generated by the temperature probe and determining therefrom a temperature reading of the fluid or gas; and 3) a radio frequency (RF) transceiver for transmitting the temperature reading determined by the temperature reader to a control apparatus external to the mixing vessel. 
     Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts: 
         FIG. 1  illustrates an exemplary process control system according to one embodiment of this disclosure; 
         FIG. 2  illustrates an exemplary mixing vessel holding a fluid containing catalytic material and controlled by an external control system according to an exemplary embodiment of the disclosure; and 
         FIG. 3  illustrates a wireless temperature sensor for monitoring the temperature profile in the mixing vessel according to an exemplary embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 through 3 , discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged process control system. 
       FIG. 1  illustrates exemplary process control system  100  according to one embodiment of this disclosure. The embodiment of process control system  100  shown in  FIG. 1  is for illustration only. Other embodiments of process control system  100  may be used without departing from the scope of this disclosure. 
     In this example embodiment, process control system  100  includes one or more process elements  102 , including exemplary process elements  102   a  and  102   b . Process elements  102   a  and  102   b  represent components in a process or production system that may perform any of a wide variety of functions. For example, process elements  102   a  and  102   b  may represent motors, catalytic crackers, valves, mixing vessels, or other industrial equipment in a production environment. Process elements  102   a  and  102   b  may represent any other or additional components in any suitable process or production system. Each of process elements  102   a  and  102   b  includes any hardware, software, firmware, or combination thereof for performing one or more functions in a process or production system. While only two process elements  102   a  and  102   b  are shown in this example, any number of process elements  102  may be included in a particular implementation of the process control system  100 . 
     Two controllers  104   a  and  104   b  are coupled to process elements  102   a  and  102   b . Controllers  104   a  and  104   b  control the operation of process elements  102   a  and  102   b . For example, controllers  104   a  and  104   b  may monitor the operation of process elements  102   a  and  102   b  and provide control signals to process elements  102   a  and  102   b . Each of controllers  104   a  and  104   b  includes any hardware, software, firmware, or combination thereof for controlling one or more of process elements  102   a  and  102   b . In an advantageous embodiment, process elements  102   a  and  102   b  comprise mixing vessels containing wireless temperature sensors that are wirelessly monitored by controllers  104   a  and  104   b  in order to control a catalytic process occurring in the mixing vessels. 
     Two servers  106   a  and  106   b  are coupled to controllers  104   a  and  104   b . Servers  106   a  and  106   b  perform various functions to support the operation and control of controllers  104   a  and  104   b  and process elements  102   a  and  102   b . For example, servers  106   a  and  106   b  may log information collected or generated by controllers  104   a  and  104   b , such as status information (i.e., temperature) related to the operation of process elements  102   a  and  102   b . Servers  106   a  and  106   b  may also execute applications that control the operation of controllers  104   a  and  104   b , thereby controlling the operation of process elements  102   a  and  102   b . In addition, servers  106   a  and  106   b  may provide secure access to controllers  104   a  and  104   b . Each of servers  106   a  and  106   b  includes any hardware, software, firmware, or combination thereof for providing access to or control of controllers  104   a  and  104   b.    
     One or more operator stations  108   a  and  108   b  are coupled to servers  106   a  and  106   b , and one or more operator stations  108   c  are coupled to controllers  104   a  and  104   b . The operator stations  108   a  and  108   b  represent computing or communication devices providing user access to servers  106   a  and  106   b , which may then provide user access to controllers  104   a  and  104   b  and process elements  102   a  and  102   b . Operator stations  108   c  represent computing or communication devices providing user access to controllers  104   a  and  104   b  (without using resources of servers  106   a  and  106   b ). As particular examples, operator stations  108   a - 108   c  may allow users to review the operational history of process elements  102   a  and  102   b  using information collected by controllers  104   a  and  104   b  and/or servers  106   a  and  106   b . Operator stations  108   a - 108   c  may also allow the users to adjust the operation of process elements  102   a  and  102   b , controllers  104   a  and  104   b , or servers  106   a  and  106   b . Each one of operator stations  108   a - 108   c  includes any hardware, software, firmware, or combination thereof for supporting user access and control of system  100 . Operator stations  108   a - 108   c  may, for example, represent personal computers. 
     In this example, at least one of operator stations  108   b  is remote from servers  106   a  and  106   b . The remote station is coupled to servers  106   a  and  106   b  through network  110 . Network  110  facilitates communication between the various components in system  100 . For example, network  110  may communicate Internet Protocol (IP) packets, frame relay frames, Asynchronous Transfer Mode (ATM) cells, or other suitable information between network addresses. Network  110  may include one or more local area networks (LANs), metropolitan area networks (MANs), wide area networks (WANs), all or a portion of a global network such as the Internet, or any other communication system or systems at one or more locations. 
     In this example, system  100  also includes two additional servers  112   a  and  112   b . Servers  112   a  and  112   b  execute various applications to control the overall operation of system  100 . For example, system  100  may be used in a processing or production plant or other facility, and servers  112   a  and  112   b  may execute applications used to control the plant or other facility. As particular examples, servers  112   a  and  112   b  may execute applications such as enterprise resource planning (ERP), manufacturing execution system (MES), or any other or additional plant or process control applications. Each of servers  112   a  and  112   b  includes any hardware, software, firmware, or combination thereof for controlling the overall operation of system  100 . 
     As shown in  FIG. 1 , system  100  includes various redundant networks  114   a  and  114   b  and single networks  116   a  and  116   b  that support communication between components in system  100 . Each of networks  114   a  and  114   b  and networks  116   a  and  116   b  represents any suitable network or combination of networks facilitating communication between components in system  100 . For example, each of networks  114   a ,  114   b ,  116   a  and  116   b  may represent an Ethernet network. Process control system  100  may have any other suitable network topology according to particular needs. 
     Although  FIG. 1  illustrates one example of process control system  100 , various changes may be made to  FIG. 1 . For example, an alternative control system may include any number of process elements, controllers, servers, and operator stations. 
       FIG. 2  illustrates process element  102 , which is controlled by external controller  104  according to an exemplary embodiment of the disclosure. Process element  102  comprises exemplary mixing vessel  210 , temperature  230 , and flow valves  240  and  250 . Mixing vessel  210  holds fluid  220 , which contains a catalytic material, among other materials. Although fluid  220  has been selected to demonstrate the operation of the present invention, this is by way of example only and should not be construed to limit the scope of the claims of the present invention. Those skilled in the art will readily understand that the present disclosure applies to gases as well as fluid and that, in an alternate embodiment of the present invention, mixing vessel  210  may hold gas  220 , instead. 
     The reaction process occurring in mixing vessel  220  may be an endothermic or exothermic chemical reaction. To properly control the chemical reaction, controller  104  requires an accurate temperature profile of the fluidized bed of catalytic material in mixing vessel  210 . In response to the temperature profile, controller  104  may control the temperature of the fluidized bed of catalytic material and fluid  220  by, among other things, regulating the input flow of material into mixing vessel  210  and regulating the output flow of material from mixing vessel  210 . Controller  104  regulates the input flow rate via input valve  240  and regulates the output flow rate via output valve  250 . 
     Controller  104  comprises central processing unit (CPU)  260  and radio frequency (RF) transceiver  270 . According to the principles of the present disclosure, RF transceiver  270  wirelessly communicates with temperature sensor  230  according to any conventional radio protocol, including, for example, an IEEE-802.11 standard protocol, a Bluetooth standard protocol, an ISA100 standard protocol, and/or other radio protocols. Temperature sensor  230  may be placed at any advantageous position within mixing vessel  210 , without concern to wiring. Thus, temperature sensor  230  may be positioned to obtain the most accurate temperature reading feasible. During operation, temperature sensor  230  transmits to RF transceiver  270  the recorded temperature readings at predetermined intervals of time and CPU  260  records the temperature profile in order to control valves  240  and  250  and regulate the temperature of fluid  220 . Since temperature sensor  230  also contains a transceiver, two-way communications are possible and temperature sensor  230  may record one or more temperature readings in response to a command message from CPU  260 . 
       FIG. 3  illustrates wireless temperature sensor  230  for monitoring the temperature profile in mixing vessel  210  according to an exemplary embodiment of the disclosure. Temperature sensor  230  comprises controller  310 , RF transceiver  320 , and temperature reader  330 , which are housed in interior space  360  of casing  350 . Temperature sensor  230  further comprises temperature probe  340 , which is mounted on, or embedded in, the outer surface of casing  350 . Temperature sensor  230  further comprises an internal battery (not shown), which provides power to controller  310 , RF transceiver  320 , and temperature reader  330 . 
     Casing  350  is a relatively thick-walled device, made from insulation material  355 , which shields the internal components of temperature sensor  230  from the extremes of temperature in fluid  220 . In an advantageous embodiment, casing  350  may be a double-walled device, wherein the space between the interior insulation wall and the exterior insulation wall is a vacuum, thereby providing additional insulation properties. Furthermore, in one embodiment, interior space  360  may also contain vacuum that provides insulation for controller  310 , RF transceiver  320 , and temperature reader  330 . In still another embodiment, interior space may be filled with a coolant liquid prior to use to further protect controller  310 , RF transceiver  320 , and temperature reader  330 . 
     Temperature probe  340  contacts fluid  220  and generates an electrical signal according to the temperature of fluid  220 . Temperature probe  340  is electrically coupled to temperature reader  330 , which monitors the electrical signal generated by temperature probe  340  and determines the temperature of fluid  220 . Controller  310  receives the recorded temperature readings from temperature reader  330  and forwards the recorded temperature readings to RF transceiver  320 . RF transceiver  320  then communicates with RF transceiver  270  and transfers the recorded temperature readings to controller  104 , as described above in  FIG. 2 . 
     Wireless temperature sensor  230  enables controller  104  to build an accurate temperature profile of fluid  220  and the fluidized bed of catalyst that may exist in mixing vessel  210 . The positioning of wireless temperature sensor  230  near the catalyst enables wireless temperature sensor  230  to record the actual temperature of the catalytic reaction, rather than the temperature on the surface of fluid  220  or near the outer perimeter of mixing vessel  210 . This is particularly advantageous for enabling controller  104  to regulate strongly exothermic or endothermic reactions. 
     Although the present disclosure has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.