IN SITU FLUE GAS ANALYZER WITH IMPROVED PROCESS COMMUNICATION
An in situ flue gas analyzer includes a probe extendable into a flue. The probe has a measurement cell providing a signal responsive to a concentration of a gas within the flue. A controller is coupled to the probe and configured to provide an output based on the signal from the measurement cell. A first media access unit is coupled to the controller and is operably coupleable to a first process communication link. The first media access unit is configured to communicate in accordance with an all-digital process communication protocol. A second media access unit is coupled to the controller and is operably coupleable to a second process communication link. The second media access unit is configured to communicate in accordance with a second process communication protocol that is different than the all-digital process communication protocol. The first and second media access units are enabled simultaneously.
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The present application is based on and claims the benefit of U.S. Provisional Patent Application Ser. No. 61/806,621, filed Mar. 29, 2013, the content of which is hereby incorporated in its entirety.
BACKGROUNDIndustrial process industries often rely on energy sources that include one or more combustion processes. Such combustion processes include operation of a furnace or boiler to generate energy from combustion, which is then used for the process. While combustion provides relatively low-cost energy, its use is typically regulated and combustion efficiency is sought to be maximized. Accordingly, one goal of the process management industry is to reduce the production of greenhouse gases by maintaining combustion efficiency of existing furnaces and boilers.
In situ or in-process flue gas analyzers are commonly used for monitoring, optimizing and/or controlling combustion processes. Typically, these analyzers employ an oxygen sensor that is similar in both technology and application to oxygen sensors found in automobiles. Such sensors are heated to an elevated temperature and provide a sensor output that is indicative of a parameter of interest (oxygen) relative to the exhaust/flue gas stream. In situ or in-process analyzers are particularly advantageous because they have no moving parts or sampling apparatus resulting in an extremely reliable probe that requires very little maintenance. While in situ flue gas analyzers may be considered to be field devices in the sense that they are often located out in the field and subjected to climatological extremes of temperature, humidity, mechanical vibration, and electrical interference, they are substantially different from most field devices. While many field devices measure a single physical quantity, such as temperature, pressure or flow, of a process fluid, process analyzers actually measure the composition of flue gas process streams. Accordingly, the processing performed within a flue gas analyzer is relatively complex and high-speed. Thus, the flue gas analyzer must often perform significant calculations and analyses in order to effectively control a combustion process. Additionally, it must do so quickly since the flue gas concentration sensor signal can also vary quickly.
Traditionally, some in situ flue gas analyzers were provided that communicated in accordance with a hybrid digital-analog process communication protocol. An example of this process communication protocol is the digital Highway Addressable Remote Transducer (HART®) protocol. The HART® communication protocol specifies the manner in which digital information is arranged in digital packets (i.e., HART® packets) and the manner in which the digital packets are physically conveyed through the wired transmission media. Typically, an in situ flue gas oxygen transmitter, such as that sold under the trade designation Model 6888 Oxygen Transmitter from the Rosemount Analytical, Inc. business unit of Emerson Process Management, transmits its flue gas concentration information in accordance with an analog signaling technique, such as the well-known 4-20 milliamp signaling technique. Optionally, the transmitter can be configured or otherwise specified to provide an analog signal representing flue gas oxygen in the form of a raw millivolt signal in order to interoperate with a variety of systems. Additionally, since the HART® protocol superimposes digital information upon the analog process variable signal, it is also known for an in situ flue gas oxygen transmitter to transmit digital information to an optional user interface, such as the known Xi Electronics module available from Rosemount Analytical.
While existing products provide significant benefits for users thereof in the monitoring and/or controlling of combustion processes, the sheer volume of data generated by the analysis of the flue gas stream and the speed with which the constituents of the flue gas stream may change, can be a challenge for the communications of the flue gas analyzer. Providing an in situ flue analyzer with improved process communication abilities would benefit the art of process combustion monitoring and control.
SUMMARYAn in situ flue gas analyzer includes a probe extendable into a flue. The probe has a measurement cell providing a signal responsive to a concentration of a gas within the flue. A controller is coupled to the probe and is configured to provide an output based on the signal from the measurement cell. A first media access unit is coupled to the controller and is operably coupleable to a first process communication link. The first media access unit is configured to communicate in accordance with an all-digital process communication protocol. A second media access unit is coupled to the controller and is operably coupleable to a second process communication link. The second media access unit is configured to communicate in accordance with a second process communication protocol that is different than the all-digital process communication protocol. The first and second media access units are enabled simultaneously.
Burner 16 is operably coupled to a source of air or oxygen 18 and a source 20 of combustible fuel. Each of sources 18 and 20 is preferably coupled to burner 16 through a respective valve to deliver a controlled amount of oxygen and/or fuel to burner 16 in order to control the combustion process. Analyzer 10 measures the amount of oxygen in the combustion exhaust flow and provides an indication of the oxygen level to combustion controller 22. In the past, this signal was an analog signal either in the form of a 4-20 milliamp current loop or a raw millivolt signal. Controller 22 controls one or both of valves 24, 26 to provide closed loop combustion control. Analyzer 10 includes an oxygen sensor that typically employs a zirconia oxide sensor substrate to provide an electrical signal indicative of oxygen concentration, content or percentage in the exhaust. Zirconia oxide sensors operate at a temperature of about 700° Celsius and thus analyzer 10 includes, within probe assembly 12, an electrical heater that is operably coupled to AC power source 29. The oxygen sensor within probe 12 is similar in technology to oxygen sensors found in automobiles. Such sensors are highly effective in permitting control systems to maintain optimum fuel to ratios in order to achieve high efficiency, low NOx production, and also the least amount of greenhouse gas emissions possible.
In accordance with an embodiment of the present invention, analyzer electronics 42 also includes a plurality of media access units to communicate in accordance with a plurality of distinct process communication protocols, such as the HART® process communication protocol described above and the FOUNDATION™ Fieldbus (FF). In accordance with an embodiment of the present invention, analyzer electronics 42 communicates using a plurality of distinct process communication protocols simultaneously or at substantially the same time. Thus, communication in accordance with a first process communication protocol may be performed for a first purpose, such as combustion burner control, and communication in accordance with the second distinct process communication protocol may be done in order to provide a second purpose, such as interacting with an optional user interface, such as the Model Xi operator interface (shown in
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
Claims
1. An in situ flue gas analyzer comprising:
- a probe extendable into a flue, the probe having a measurement cell providing a signal responsive to a concentration of a gas within the flue;
- a controller coupled to the probe and configured to provide an output based on the signal from the measurement cell;
- a first media access unit coupled to the controller and operably coupleable to a first process communication link, the first media access unit being configured to communicate in accordance with an all-digital process communication protocol;
- a second media access unit coupled to the controller and operably coupleable to a second process communication link, the second media access unit being configured to communicate in accordance with a second process communication protocol that is different than the all-digital process communication protocol; and
- wherein the first and second media access units are enabled simultaneously
2. The in situ flue gas analyzer of claim 1, wherein the measurement cell includes an oxygen sensor.
3. The in situ flue gas analyzer of claim 1, wherein the all-digital process communication protocol is in accordance with the FOUNDATION Fieldbus protocol.
4. The in situ flue gas analyzer of claim 1, wherein a communication rate of the all-digital process communication protocol is faster than a communication rate of the second process communication protocol.
5. The in situ flue gas analyzer of claim 1, wherein the second process communication protocol is a hybrid process communication protocol.
6. The in situ flue gas analyzer of claim 5, wherein the hybrid process communication protocol superimposes a digital signal on an analog signal.
7. A process combustion control system comprising:
- a combustion source operably coupled to a source of fuel and a source of air, the combustion source being configured to provide combustion gasses through a flue;
- a combustion controller coupled to at least one of the source of fuel and source of air;
- an in situ flue gas analyzer coupled to the combustion controller and disposed to sense a concentration of a gas of interest within the flue and convey process information related to the concentration to the combustion controller in accordance with an all-digital process communication protocol; and
- wherein the in situ flue gas analyzer is communicatively coupled to a second device and communicates with the second device, in accordance with a second process communication protocol different than the all-digital process communication protocol, wherein communication with the combustion controller and the second device occurs substantially simultaneously.
8. The process combustion control system of claim 7, wherein the gas of interest is oxygen.
9. The process combustion control system of claim 7, wherein the in situ flue gas analyzer communicates with the combustion controller at a first communication rate, and communicates with the second device at a second rate that is less than the first rate.
10. The process combustion control system of claim 7, wherein the second device is a user interface.
11. The process combustion control system of claim 10, wherein the second process communication protocol is in accordance with the Highway Addressable Remote Transducer (HART) protocol.
12. A method of operating an in situ flue gas analyzer, the method comprising:
- disposing a probe of the in situ flue gas analyzer within a flue;
- measuring a concentration of a gas on interest using the probe;
- communicating information regarding the measured concentration to a combustion controller in accordance with an all-digital process communication protocol; and
- communicating with a second device in accordance with a second process communication protocol different than the all-digital process communication protocol.
13. The method of claim 12, wherein the all-digital process communication protocol is the FOUNDATION Fieldbus protocol.
14. The method of claim 13, wherein the second process communication protocol is the Highway Addressable Remote Transducer (HART) protocol.
15. The method of claim 12, wherein communication with the combustion controller and the second device occurs substantially simultaneously.
16. The method of claim 15, wherein communication with the combustion controller occurs at a first communication rate, and communication with the second device occurs at a second rate that is less than the first rate.
Type: Application
Filed: Mar 27, 2014
Publication Date: Oct 2, 2014
Applicant: Rosemount Analytical, Inc. (Solon, OH)
Inventors: Joseph C. Nemer (Mayfield Heights, OH), Behzad Rezvani (Irvine, CA), Anni S. Wey (Strongsville, OH), James D. Kramer (Homerville, OH)
Application Number: 14/227,476
International Classification: F23N 5/00 (20060101);