System of distributed configurable flowmeters

A system of one or more configurable flowmeters allows an individual, locally or remotely, to selectively activate one or more functions of the flowmeters. The individual is capable of selecting which parameter of the process flow that the flowmeter is to measure, thereby effectively providing latent functions that may be selectively brought on line or shut off. The system may also allow an individual, locally or remotely, to selectively activate one or more latent flowmeters in the system. The system may be a distributed control system (DCS), which receives input signals from conventional meters and devices in the process flow and provides control signals to one or more devices in the flow process. The system may also provide a method of flowmeter selection and billing.

TECHNICAL FIELD

The present disclosure relates to fluid flowmeters and, more particularly, to a system of distributed, configurable fluid flowmeters.

BACKGROUND

A fluid flow process (flow process) includes any process that involves the flow of fluid through pipes, ducts, or other conduits, as well as through fluid control devices such as pumps, valves, orifices, heat exchangers, and the like. Flow processes are found in many different industries such as the oil and gas industry, refining, food and beverage industry, chemical and petrochemical industry, pulp and paper industry, power generation, pharmaceutical industry, and water and wastewater treatment industry. The fluid within the flow process may be a single phase fluid (e.g., gas, liquid or liquid/liquid mixture) and/or a multi-phase mixture (e.g. paper and pulp slurries or other solid/liquid mixtures). The multi-phase mixture may be a two-phase liquid/gas mixture, a solid/gas mixture or a solid/liquid mixture, gas entrained liquid or a three-phase mixture.

Various sensing technologies exist for measuring various physical parameters of single and/or multiphase fluids in an industrial flow process. Such physical parameters include, for example, volumetric flow rate, composition, consistency, density, and mass flow rate.

In certain sensing applications, such as in industrial flow processes, it may be desirable to sense different parameters, the same parameter, or different locations, at different times throughout the industrial flow process. For example, it may initially be desirable to sense volumetric flow rate at a single or limited number of locations throughout an industrial flow process when plant first comes on line. Later, it may be desirable to sense volumetric flow rates at different locations in the process on a distributed basis throughout the process. Alternatively, it may be desirable to sense different parameters of interest at a later time, such as composition, density, and mass flow rate.

From a plant operator's standpoint, it is undesirable to pay for information that is not needed. Therefore, the operator may be willing to pay a premium for certain information at different times, and other different information at a later time. However, it may be extremely costly to intervene or install a meter or measuring device at the later time because of lost production or difficulty in installing a meter at the later time, particularly in harsh environments.

SUMMARY OF THE INVENTION

The above-described and other needs are met by a system of distributed selectable latent flowmeters. The system comprises a plurality of sensor heads and at least one signal processor connected to the plurality of sensor heads. Each of the sensor heads comprises an array of sensors disposed axially along a pipe, and each of the sensor heads provides pressure signals representative of unsteady pressures within a fluid flowing in the pipe. The at least one signal processor provides an output signal indicative of at least one parameter determined from the pressure signals from selected ones of the plurality of sensor heads. The at least one signal processor may select the selected ones of the plurality of sensor heads based on a selection signal. The at least one parameter includes may include: density of the fluid, volumetric flow rate of the fluid, mass flow rate of the fluid, composition of the fluid, entrained air in the fluid, consistency of the fluid, size of particles in the fluid, and health of a device causing the unsteady pressures to be generated in the pipe.

A status of the selection signal may be determined based on whether a user desires to retrieve the output signal, and it may be determined based on whether a user will pay for the output signal. The status of the selection signal may be provided from a location remote from the at least one signal processor, and the output signal may be provided to a location remote from the at least one signal processor.

A user of the system may be charged a fee based at least in part on the selected ones of the plurality of sensor heads and/or the output signal.

The at least one signal processor may include at least one first signal processor connected to the plurality of sensor heads, the at least one first signal processor determines the at least one parameter; and a second signal processor that selects the selected ones of the plurality of sensor heads based on the selection signal. In response to the at least one parameter, the second signal processor may provide a control signal to a device through which the fluid flows.

In one aspect of the invention the at least one parameter is selected from a plurality of parameters determined from the pressure signals. The at least one signal processor may select the at least one parameter based on a selection signal. The user of the system may be charged a fee based at least in part on the at least one parameter selected.

In another aspect of the invention, a method of paying for data indicative of parameters of a flow process comprises: installing a plurality sensor heads in the flow process, each of the sensor heads comprising an array of sensors disposed axially along a pipe, and each of the sensor heads providing pressure signals representative of unsteady pressures within a fluid flowing in the pipe; providing data to a user, the data being determined from the pressure signals from selected ones of the sensor heads; and charging the user a fee based at least in part on the selected ones of the sensor heads. The method may further comprise selecting the selected ones of the sensor heads based on a selection signal. The fee may further be based on one or more of the number of sensor heads selected, the amount of data retrieved by the user, and the length of time data is retrieved by the user. The fee may further be based on one or more of the number of sensor heads selected, the amount of data retrieved by the user, and the length of time data is retrieved by the user.

In another aspect of the invention, the data associated with the selected ones of the sensor heads is indicative of at least one parameter of the flow process, with the at least one parameter being selected from a plurality of parameters determined from the pressure signals from the selected ones of the sensor heads. In this embodiment, the fee may be based at least in part on the at least one parameter selected.

DETAILED DESCRIPTION

Referring toFIG. 1, a system10of one or more configurable flowmeters12allows an individual, locally or remotely, to selectively activate one or more functions of the flowmeter12. In other words, an individual is capable of selecting which parameter of the process flow that the flowmeter12is to measure, thereby effectively providing latent functions that may be selectively brought on line or shut off. The system10also allows an individual, locally or remotely, to selectively activate one or more latent flowmeters12in the system. The system10of configurable flowmeters12may be a distributed control system (DCS), which receives input signals from conventional meters and devices in the process flow. The system10also provides a method of flowmeter selection and billing. Each of these aspects of the present invention is described in further detail hereinafter.

Referring toFIG. 1, the system10includes a configurable flowmeter12, which is mounted to a pipe, duct or other form of conduit (hereinafter “pipe”)14having a single or multi-phase fluid13passing therethrough. The flowmeter12includes a sensor head (sensor array)11and a transmitter (signal processor)19. The sensor head11includes an array of sensors15,16,17, and18spaced axially along the pipe14to measure unsteady pressures created by sound propagating through the fluid13and/or unsteady pressures created by vortical disturbances (eddies) propagating within the fluid13. The pressure signals P1(t), P2(t), P3(t), P4(t) provided by each respective sensor15,16,17,18are indicative of unsteady pressure within the pipe14at a corresponding axial location of the pipe14. While the flowmeter12is shown as including four pressure sensors, it is contemplated that the flowmeter12may include an array of two or more pressure sensors, each providing a pressure signal P(t) indicative of unsteady pressure within the pipe14at a corresponding axial location of the pipe14.

The pressure signals P1(t), P2(t), P3(t), P4(t) provided by each respective sensor15,16,17,18are processed by a transmitter19, which applies this data to flow logic36executed by transmitter19to determine one or more parameters21of the flow process, such as volumetric flow rate, mass flow rate, density, composition, entrained air, consistency, particle size, velocity, mach number, speed of sound propagating through the fluid13, and/or other parameters of the fluid13. The flow logic36is described in further detail hereinafter.

The transmitter19may also apply one or more of the pressure signals P1(t), P2(t), P3(t), P4(t) and/or one or more parameters21from the flow logic36to diagnostic logic38. Diagnostic logic38is executed by transmitter19to diagnose the health of any device34in the process flow that causes unsteady pressures to be generated in the section of the pipe14where flowmeter12is disposed. InFIG. 1, device34is depicted as a valve; however, it is contemplated that device34may be any machinery, component, or equipment, e.g., motor, fan, pump, generator, engine, gearbox, belt, drive, pulley, hanger, clamp, actuator, valve, meter, or the like. The transmitter19may output one or more parameters21indicative of the health of the diagnosed device34. The diagnostic logic38is described in further detail hereinafter.

The flowmeter12may have a design comprising or similar to one or more of the flowmeters described in U.S patent application, Ser. No. 10/875,856, filed concurrently herewith, which is incorporated by reference herein in its entirety.

In the present invention, the flowmeter12is configurable to process the pressure signals P1(t), P2(t), P3(t), P4(t) to provide any desired parameter21or combination of parameters21in response to a data selection signal20generated by one of a local communication device26and a remote communication device28. Specifically, one or more of the output parameters21of the configurable flowmeter12is selectably provided to a local communication device26and/or a remote communication device28, in response to a data selection signal24. The data selection signal24is provided by one or both of the communication devices26,28. In response to the data selection signal24, a controller/transceiver22(signal processor) generates a control signal20. In response to the control signal20, the transmitter19processes the pressure signals P1(t), P2(t), P3(t), P4(t) to provide the one or more selected parameters21to the controller/transceiver22. The one or more selected parameters21are, in turn, provided to at least one of the communication devices26,28as data30.

It is contemplated that the flowmeter12has only a single function or a fixed set of functions that may be enabled or disabled in response to the control signal20or is otherwise enabled and disabled in response to the control signal20. In this manner, the flowmeter12itself can be considered latent and selectable. That is, the flowmeter12is either “on” (providing parameters12indicating the single or fixed set of functions) or “off” (providing no parameters12).

Alternatively, the transmitter19may provide all possible parameters21to the controller/transceiver22(irrespective of the control signal20), and the controller/transceiver22, in response to the data selection signal24, provides the selected parameters21to the desired communication device26,28.

The controller/transceiver22may include billing logic45, which provides a bill or other accounting data to an end user at the local or remote communication devices26,28, depending on whether the flowmeter12is selected (i.e., turned on) and depending on the parameters21parameters that the end user selects. The billing logic45is described in further detail hereinafter.

The system10may function as an “open loop” system, wherein the selected parameters21are provided as data30to the desired communication device26,28to allow operating personnel to monitor and record the selected parameters21. The system10may also function as a “closed loop” system, wherein, in addition to allowing operating personnel the ability to monitor the selected parameters21, the controller/transceiver22provides control signals39to control one or more devices34in the flow process. The one or more controlled devices34may or may not be a device34diagnosed by the diagnostic logic38.

Where system10functions as a closed loop system, the controller/transceiver22may apply one or more of the parameters21to control logic41executed by the controller/transceiver22. The control logic41may, for example, compare one or more parameters21to stored threshold values, set points, or user input parameters to determine an appropriate control signal39for causing the appropriate operating condition of the one or more devices34. For example, if fluid13flow is determined to be below a stored threshold value, control logic41may provide control signals34to valves and/or pumps in the flow process. In another example, if one or more parameters21indicates that a device34is malfunctioning, as may be determined by the diagnostic logic38, then the control logic41may provide a control signal39effective to stop operation of the device34.

Referring toFIGS. 2a-d, the data selection signal24may be a bit or group of bits that indicate to the controller/transceiver22which of the parameters21to provide to the communication devices26,28. For example, the bit pattern ofFIG. 2amay indicate that parameters21indicative of volumetric flow measurement, entrained air measurement, and gas volume fraction measurement are to be provided. The bit pattern ofFIG. 2bmay indicate that no measurements are to be provided, or that a parameter21indicative of a health of a diagnosed device34is to be provided. The bit pattern ofFIG. 2cmay indicate that all available parameters21are to be provided. The bit pattern ofFIG. 2dmay indicate that only a parameter21indicative of volumetric flow in the pipe14is to be provided.

Referring again toFIG. 1, the transmitter19and the controller/transceiver22may be any one or more signal processing devices for executing programmed instructions, such as one or more microprocessors or application specific integrated circuits (ASICs), and may include memory for storing programmed instructions, set points, parameters, and for buffering or otherwise storing data. For example, the transmitter19and the controller/transceiver may each be a general-purpose computer.

One skilled in the art will appreciate that the transmitter19and the controller/transceiver22may be separate devices that are located remotely from each other. For example, the transmitter19may be located proximate the sensor head11within an industrial plant, and the controller/transceiver22may be separately located in an electronics room or control room within the industrial plant. It is also contemplated that the transmitter19and the controller/transceiver22may be integrated into a single device, such as that indicated at43inFIG. 6, which is described in further detail hereinafter.

The local communication device26may communicate with the controller/transceiver22by wired or wireless connection or any combination of the two, and may be connected via a Local Area Network (LAN).

The remote communication device28may communicate with the controller/transceiver22by wired or wireless connection or any combination of the two, and may be connected by one or more network or dedicated transmission links of any size (e.g. LAN, Wide Area Network, Internet, phone line, satellite link, etc.).

It is contemplated that the flowmeter12may include the capability of providing the data30as a series (multiplexed) of signals or as parallel signals. It is also contemplated that the flowmeter12may include the capability of communicating using various protocols and systems currently in use in the industrial sensing area. For example, the flowmeter12may provide conventional 4-20 mA output signals formatted to the open protocol HART® (Highway Addressable Remote Transducer) digital communications format. Similarly, communication from the flowmeter12may be performed with an open and interoperable protocol, such as FOUNDATION™ Fieldbus that provides a digital communication link among intelligent field level and control devices via electrical lines. In other examples, the flowmeter12may be configured for use with other process protocols, including Device Bus, Sensor Bus, Profibus, Ethernet, TCP/IP, Blue Tooth, IEEE 102.11 b/c/g and others.

Referring now toFIG. 3, it is further contemplated that the controller/transceiver22may be used in a larger system60, such as a distributed control system (DCS), to monitor a plurality of flowmeters12and, optionally, to control a plurality of devices34in response to the parameters21received from the plurality of flowmeters12. The controller/transceiver22may also monitor a plurality of standard meters62, which may include consistency meters, density meters, standard flowmeters, pressure sensors, temperature sensors, and the like, and may control the plurality of devices39in response to signals received from these standard meters62. Also, as shown inFIG. 3, the unsteady pressure signals P1(t), P2(t), P3(t), P4(t) from a group of sensor heads (arrays)11may be provided to a single transmitter19.

In system60, the measured parameters21of the transmitter19servicing the group of sensor heads11, as well as the measured parameters21from the flowmeters12(which also include transmitters19as shown inFIG. 1), are provided to the controller/transceiver22, which controls the selection of the measured parameters21similar to that described hereinbefore. The one or more selected parameters21are provided to at least one of the communication devices26,28as data30, and may be applied by the controller/transceiver22to provide a control signal39to the devices34.

In the embodiment shown, the flowmeters12, transmitter19, standard meters64, and devices34separately communicate with the controller/transceiver22; however, it is contemplated that all or a portion of the flowmeters12, transmitter19, standard meters64, and devices34may be connected to a common cable, with the signals from the connected meters, transmitters, and devices being multiplexed on the common cable using any known multiplexing technique. This multiplexed arrangement is similar to that found in the PlantWeb® architecture manufactured by Emerson Corporation.

As previously described with respect to system10ofFIG. 1, the system60ofFIG. 3enables a user either locally or remotely to select any one or more of the flowmeters12and/or one or more transmitters19distributed throughout a flow process, and to further select a parameter21to be provided by any of the flowmeters12and transmitters19. This capability permits a user to disable particular meters or functions of a meter to provide latent meters and functions that may be accessed in accordance with a desired schedule or circumstance. Also, as described hereinbefore, the controller/transceiver22may include billing logic45(FIG. 1) which provides a bill or other accounting data to an end user at the local or remote communication devices26,28, depending on the flowmeters12selected and depending on the parameters21the end user selects. The billing logic45is described in further detail hereinafter.

FIG. 4shows the system60integrated in a pulp and paper application. Specifically,FIG. 4illustrates a schematic diagram of a paper machine wet end including a plurality of flowmeters12, sensor heads11, standard meters64, and devices34as part of the system60.

Referring toFIG. 5, the data selection signal24for use in the system60may be a word or group of words that indicate to the controller22which of the measured parameters21to provide to the communication devices26,28for each transmitter19. It will be appreciated that in the system60, each transmitter19may be associated with a flowmeter12or with a plurality of arrays11. In the data selection signal24ofFIG. 5, the first four bits may be associated with a first transmitter19, and the bit pattern of the first four bits may indicate that volumetric flow measurement, particle size measurement, and gas volume fraction measurement parameters21are to be provided. The next 4 bits may be associated with a second transmitter19, and the bit pattern of the second four bits may indicate that a volumetric flow rate measurement parameter21is to be provided. The next four bits may be associated with a third transmitter19, and the bit pattern of the next four bits may indicate that no measurements are to be provided, or that a parameter21indicative of a health of a diagnosed device34is to be provided. The final four bits may be associated with a fourth transmitter19, and the bit pattern provided by the final four bits may indicate that all available parameters21are to be provided. It will be appreciated that any known protocol may be used for data selection signal24.

Referring now toFIG. 6, a system40is shown, wherein pressure signals P1(t), P2(t), P3(t), P4(t) provided by one or more sensor heads11distributed throughout a flow process are processed by a transceiver/controller (signal processor)43to determine output data30indicative of one or more parameters of the flow process. As depicted inFIG. 7, the functionality of the transmitter19and the controller/transceiver22previously described with respect toFIGS. 1-5are integrated into the transceiver/controller43. As also previously described, the parameters21of the flow process may include volumetric flow rate, mass flow rate, density, composition, entrained air, consistency, particle size, velocity, mach number, speed of sound propagating through the fluid13, and/or other parameters of the fluid13. The parameters21may also indicate the health of a diagnosed device in the flow process.

The transceiver/controller43may be only one or more signal processing devices for executing programmed instructions, such as one or more microprocessors or application specific integrated circuits (ASICS), and may include memory for storing programmed instructions, set points, parameters, and for buffering or otherwise storing data.

Referring toFIGS. 6 and 7, the output data30on line44is provided to a display46or other visual, electronic, or printing device for communicating the various parameters21to an end user50. Also, the transceiver/controller43may be connected by a line49to a data entry device48, such as a keyboard and/or mouse. The transceiver/controller43, display46and data entry device48may be provided in a common device42, such as a personal computer or the like.

In the present embodiment, a sensor selection (on/off) signal51is provided to the transceiver/controller43and indicates to the transceiver/controller43which of the sensor heads11to use in generating the parameters21provided as output data30to the end user50. The sensor selection signal51may be provided from the keyboard48or from a remote link53(discussed hereinafter), or on a separate line (not shown), or by other means.

The transceiver/controller43may operate in many different ways to provide the selected output data30in response to the sensor selection signal51. For example, the transceiver/controller43may process pressure signals P1(t), P2(t), P3(t), P4(t) from each of the sensor heads11and provide output data30corresponding only to the selected sensor heads11. Alternatively, the transceiver/controller43may only process pressure signals P1(t), P2(t), P3(t), P4(t) from the selected sensor heads11and provide output data30corresponding to those sensor heads11.

In addition to or instead of sending the output data30to the display46, the remote link53may be used to communicate the sensor selection signal51and output data30between the device42and a remote location54. The remote location54may have a remote device58(e.g., a personal computer or the like) connected to the remote link53. The remote device58may comprise a remote transceiver55, a remote display60similar to the display46, and a data entry device62, such as a keyboard and/or mouse. The remote transceiver55may be similar to the transceiver/controller43if the same functions are performed, or may comprise different hardware and/or software if additional or different functions are performed as described herein.

The remote device58may retrieve or receive output data30or other signals from the device42and/or send the sensor selection signal51to the device42to activate or inactivate certain of the sensor heads11. The remote device58may perform the same functions as the device42and/or may do other processing on the measured data as desired and/or may process billing information, or perform other functions. Also, the remote device58may perform the billing and/or receive the payments electronically, such as by wire transfer or other electronic commerce or banking technique.

The remote link53may be partially or completely wired or wireless, and may comprise an internet link. The remote link53may be used to communicate output data30and/or to send the sensor selection signal51to activate or inactivate certain of the sensor heads11or data therefrom between the remote location54and the device42.

It is contemplated that the transceiver/controller43may process pressure signals P1(t), P2(t), P3(t), P4(t) from each of the sensor heads11and provide all available output data30for each of the sensor heads11to the remote device58. In this embodiment, the remote device58may, in turn, provide output data30to the remote display60for only those sensor heads11indicated in the sensor selection signal51. Also in this embodiment, the device42may send the sensor selection signal51to the remote device68for processing the data remotely.

Referring toFIG. 8, the sensor selection signal51may be a digital word or group of words that indicate to the device42which of the sensor heads11will be used in generating the parameters21provided as output data30. For example,FIG. 7shows a sensor selection signal51, where each bit in a 16 bit word represents the status (on/off) of data coming from a corresponding one of the sensor heads11.

Alternatively, the sensor selection signal51may be a code related to an end user, which pre-selects certain of the sensor heads11. For example, the user may enter a user code into the device42and, based on the user code, the device42selects predetermined ones of the sensor heads11. This code, for example, may be based on the location of the sensor head11or the parameters21desired by the user. Alternatively, the user may enter a user code and the user code is transmitted over the remote link53to the remote device58which selects the appropriate sensor selection signal51for that user and transmits the sensor selection signal over the remote link53to the device42for selection of the appropriate sensor heads11for that user. Alternatively, there may be a predetermined profile or schedule indicating which sensor heads11to select based on age of the equipment, elapsed time, user code, or other parameters, such selection may be periodic or cyclical, such as always selecting certain sensor heads11at certain times, and selecting certain other sensor heads11at certain other times in a repetitive or random pattern, thereby providing automatic reconfiguration of the selected sensor heads11without the need for user intervention.

The pressure sensors15-18described herein may be any type of pressure sensor, capable of measuring the unsteady (or ac or dynamic ) pressures within a pipe14, such as piezoelectric, optical, capacitive, resistive (e.g., Wheatstone bridge), accelerometers (or geophones), velocity measuring devices, displacement measuring devices, etc. If optical pressure sensors are used, the sensors15-18may be Bragg grating based pressure sensors, such as that described in U.S. patent application, Ser. No. 08/925,598, entitled“High Sensitivity Fiber Optic Pressure Sensor For Use In Harsh Environments”, filed Sep. 8, 1997, now U.S. Pat. No. 6,016,702, and in U.S. patent application, Ser. No. 10/224,821, entitled “Non-Intrusive Fiber Optic Pressure Sensor for Measuring Unsteady Pressures within a Pipe”, which are incorporated herein by reference. Alternatively, the sensors15-18may be electrical or optical strain gages attached to or embedded in the outer or inner wall of the pipe which measure pipe wall strain, including microphones, hydrophones, or any other sensor capable of measuring the unsteady pressures within the pipe14. In an embodiment of the present invention that utilizes fiber optics as the pressure sensors15-18, they may be connected individually or may be multiplexed along one or more optical fibers using wavelength division multiplexing (WDM), time division multiplexing (TDM), or any other optical multiplexing techniques.

For any of the embodiments described herein, the pressure sensors15-18, may be attached to the pipe by adhesive, glue, epoxy, tape or other suitable attachment means to ensure suitable contact between the sensor and the pipe14. The pressure sensors15-18may alternatively be removable or permanently attached via known mechanical techniques such as mechanical fastener, spring loaded, clamped, clam shell arrangement, strapping or other equivalents. Alternatively, the pressure sensors15-18may be embedded in the pipe14. The pressure sensors15-18may be selected from piezoelectric, piezoresistive, strain gauge, PVDF, optical sensors, ported ac pressure sensors, accelerometers, velocity sensors, and displacement sensors.

It is also within the scope of the present invention that any other strain sensing technique may be used to measure the variations in strain in the pipe14, such as highly sensitive piezoelectric, electronic or electric, strain gages attached to or embedded in the pipe14.

In certain embodiments of the present invention, a piezo-electronic pressure transducer may be used as one or more of the pressure sensors15-18and it may measure the unsteady (or dynamic or ac) pressure variations inside the pipe14by measuring the pressure levels inside of the pipe. In one embodiment of the present invention, the pressure sensors15-18comprise pressure sensors manufactured by PCB Piezotronics of Depew, N.Y. In one pressure sensor there are integrated circuit piezoelectric voltage mode-type sensors that feature built-in microelectronic amplifiers, and convert the high-impedance charge into a low-impedance voltage output. Specifically, a Model 106 B manufactured by PCB Piezotronics is used which is a high sensitivity, acceleration compensated integrated circuit piezoelectric quartz pressure sensor suitable for measuring low pressure acoustic phenomena in hydraulic and pneumatic systems. It has the unique capability to measure small pressure changes of less than 0.001 psi under high static conditions. The 106 B has a 300 mV/psi sensitivity and a resolution of 91 dB (0.0001 psi).

The pressure sensors15-18may incorporate a built-in MOSFET microelectronic amplifier to convert the high-impedance charge output into a low-impedance voltage signal. In this embodiment, the pressure sensors15-18are powered from a constant-current source and can operate over long coaxial or ribbon cable without signal degradation. Power to operate integrated circuit piezoelectric sensors generally takes the form of a low-cost, 24 to 27 VDC, 2 to 20 mA constant-current supply. The system10of the present invention may incorporate constant-current power for directly powering integrated circuit piezoelectric pressure sensors15-18.

Furthermore the present invention contemplates that each of the pressure sensors15-18may include a piezoelectric material to measure the unsteady pressures of the fluid13. The piezoelectric material, such as the polymer, polarized fluoropolymer, polyvinylidene fluoride (PVDF), measures the strain induced within the process pipe14due to unsteady pressure variations within fluid13. Strain within the pipe14is transduced to an output voltage or current by the attached piezoelectric pressure sensors15-18.

Preferably, the PVDF material forming each of the pressure sensors15-18is adhered to the outer surface of a steel strap that extends around and clamps onto the outer surface of the pipe14. The piezoelectric pressure sensors15-18are typically conformal to allow complete or nearly complete circumferential measurement of induced strain. The pressure sensors15-18can be formed from PVDF films, co-polymer films, or flexible PZT sensors, similar to that described in “Piezo Film Sensors technical Manual” provided by Measurement Specialties, Inc. of Fairfield, N.J., which is incorporated herein by reference. The advantages of this technique are the following:

2. Low cost

3. Measurement technique requires no excitation source. Ambient flow noise is used as a source.

4. Flexible piezoelectric sensors can be mounted in a variety of configurations to enhance signal detection schemes. These configurations include a) co-located sensors, b) segmented sensors with opposing polarity configurations, c) wide sensors to enhance acoustic signal detection and minimize vortical noise detection, d) tailored sensor geometries to minimize sensitivity to pipe modes, e) differencing of sensors to eliminate acoustic noise from vortical signals.

For the system60ofFIG. 6, the use of fiber optic based pressure sensors15-18in sensor heads11makes the system60particularly qualified for industrial applications requiring multiple sensor heads11. The use of multiplexed sensor heads11through the use of feedthroughs (or other known techniques) in a large multi-point process enables connectivity to the multiple sensor heads11through a single fiber optic cable. As a result, dedicated wiring to the transceiver/controller43and back to the sensor to provide a power signal is obviated.

Billing Logic

Referring toFIG. 9, an example of billing logic45is shown as may be applied to the embodiment ofFIG. 6. In the embodiment ofFIG. 9, the end user is only billed for and only pays for the sensor heads11that are selected (i.e., the “on” flowmeters) as indicated by a top level flow chart100. In particular, when a sensor selection signal51is received, the appropriate ones of the sensor heads11or data therefrom are selected as dictated by the sensor selection signal51described hereinbefore, as shown by a step104. Then, a bill or invoice is sent to the user (or customer) and the user pays only for the number of sensor heads11selected to receive data from, as indicated in step106. The sensor selection signal51may also be used to effectively shut off all sensor heads (e.g. prevent transceiver/controller43from processing pressure signals P1(t), P2(t), P3(t), P4(t) or from providing output data30) if a bill is not paid by the user. The cost to (or payment by) the user may be based on the number of sensor heads11selected, the amount of output data30provided or the length of time the output data30is provided, in a similar manner to that which is done for a utility company, a cable TV company, an internet service provider or the like.

Referring toFIG. 10, an example of billing logic45is shown as may be applied to the embodiments ofFIGS. 1 and 3. In the embodiment ofFIG. 10, the end user50is only billed for and only pays for the flowmeters12that are selected and the parameters21that are selected as indicated in the top level flow chart200. In particular when a data selection signal24is received (see step202), the appropriate ones of the flowmeters12are selected and the parameters21of each of the selected flowmeters are selected as dictated by the data selection signal24described hereinbefore, as shown by steps204,206. Then, a bill or invoice is sent to the user (or customer) and the user pays only for the usage of the flowmeters12selected to receive data from, as indicated in step208. For example, the user can be billed by the number of flowmeters12providing data, by the type of parameters21being provided by the flowmeters12, the length of time the flowmeters12are providing data, the length of time the user is receiving output data30, the amount of data provided, the activation of a previously latent flowmeter12and/or the number of flowmeters12installed in the flow process, in a similar manner to that which is done for a utility company, a cable TV company, an internet service provider or the like. The data selection signal24may also be used to effectively shut off all flowmeters12(e.g., prevent transmitter19from processing pressure signals P1(t), P2(t), P3(t), P4(t) or prevent controller/transceiver22from providing output data30) if a bill is not paid by the user.

In any of the embodiments described herein the selectability of the flowmeters12, sensor heads11, and parameters21may be limited to a remote service provided wherein the end user pays for the service or reconfiguring the system and/or pays for the particular usage of the meters as described hereinbefore. The remote user or service provider may also provide a plurality of sensor heads11and/or flowmeters12to the end user or customer at no cost, but charge the customer for their usage as described hereinbefore.

Also in any of the embodiments described herein, the flowmeters12and/or sensor heads11may also be used to provide diagnostic functionality. The sensor heads11and/or flowmeters12may be strategically placed to measure or periodically sample desired flow parameters at particular locations in the process to monitor measurements of other meters or output of particular valves or pumps to determine any drift or degradation of performance. The end-user may pay on a yearly basis for periodic diagnostics performed or pay each time diagnostics is performed. The present invention is flexible to permit the diagnostics to be at specific areas or locations of the plant, and thus enabling diagnostics being performed at different intervals as other areas.

Diagnostic Logic

Referring toFIG. 11, the diagnostic logic38measures the sensor input signals (or evaluation input signals), which may include one or more of the pressure signals P1(t), P2(t), P3(t), P4(t) and the parameters21, at a step70. Next, the diagnostic logic38compares the evaluation input signals to a diagnostic evaluation criteria at a step72, discussed hereinafter. Then, a step74checks if there is a match, and if so, a step76provides a diagnostic signal indicative of the diagnostic condition that has been detected and may also provide information identifying the diagnosed device. The diagnostic signal may be output as a parameter21.

Where the evaluation input signal is a parameter21, as may be output from the flow logic36, the diagnostic evaluation criteria may be based on a threshold value of the flow signal24. For example, the threshold value may be indicative of a maximum or minimum sound speed, mach number, consistency, composition, entrained air, density, mass flow rate, volumetric flow rate, or the like. If there is not a criteria match in step74, the diagnostic logic38exits.

Where the evaluation input signal includes one or more pressure signals P1(t), P2(t), P3(t), P4(t), the diagnostic evaluation criteria may be a threshold (maximum or minimum) pressure. Alternatively, the diagnostic evaluation criteria may be based on an acoustic signature, or a convective property (i.e., a property that propagates or convects with the flow). For example, the diagnostic logic38may monitor the acoustic signature of any upstream or downstream device (e.g., motor, fan, pump, generator, engine, gear box, belt drive, pulley, hanger, clamp, actuator, valve, meter, or other machinery, equipment or component). Further, the data from the array of sensors15-18may be processed in any domain, including the frequency/spatial domain, the temporal/spatial domain, the temporal/wave-number domain, or the wave-number/frequency (k-ω) domain or other domain, or any combination of one or more of the above. As such, any known array processing technique in any of these or other related domains may be used if desired.

For example, for three unsteady pressure signals, the equations in the frequency/spatial domain equation would be: P(x,ω)=Ae−ikrx+Be+iklx; the temporal/spatial domain would be: P(x,t)=(Ae−ikrx+Be+iklx)eiωt; and the k-ω domain (taking the spatial Fourier transform) would be:

P⁡(k,ω)=12⁢π⁢∫-∞+∞⁢P⁡(x,ω)⁢ⅇⅈ⁢⁢kx⁢ⅆx=A⁡(ω)⁢δ⁡(k-ωa)+B⁡(ω)⁢δ⁡(k+ωa)
where k is the wave number, a is the speed of sound of the material, x is the location along the pipe, ω is frequency (in rad/sec, where ω=2πf), and δ is the Dirac delta function, which shows a spatial/temporal mapping of the acoustic field in the k-ω plane.

Any technique known in the art for using a spatial (or phased) array of sensors to determine the acoustic or convective fields, beam forming, or other signal processing techniques, may be used to provide an input evaluation signal to be compared to the diagnostic evaluation criteria.

Flow Logic

Velocity Processing

Referring toFIG. 12, an example of flow logic36is shown. As previously described, each array of at least two sensors located at two locations x1,x2axially along the pipe14sense respective stochastic signals propagating between the sensors within the pipe at their respective locations. Each sensor provides a signal indicating an unsteady pressure at the location of each sensor, at each instant in a series of sampling instants. One will appreciate that each sensor array may include more than two sensors distributed at locations x1. . . xN. The pressure generated by the convective pressure disturbances (e.g., eddies120, seeFIG. 13) may be measured through strained-based sensors and/or pressure sensors. The sensors provide analog pressure time-varying signals P1(t),P2(t),P3(t),PN(t) to the flow logic36.

The flow logic36processes the signals P1(t),P2(t),P3(t),PN(t) to first provide output signals (parameters)21indicative of the pressure disturbances that convect with the fluid (process flow)13, and subsequently, provide output signals in response to pressure disturbances generated by convective waves propagating through the fluid13, such as velocity, Mach number and volumetric flow rate of the process flow13. The flow logic36processes the pressure signals to first provide output signals indicative of the pressure disturbances that convect with the process flow13, and subsequently, provide output signals in response to pressure disturbances generated by convective waves propagating through the process flow13, such as velocity, Mach number and volumetric flow rate of the process flow13.

The flow logic36receives the pressure signals from the array of sensors15-18. A data acquisition unit126(e.g., A/D converter) converts the analog signals to respective digital signals. The FFT logic128calculates the Fourier transform of the digitized time-based input signals P1(t)-PN(t) and provides complex frequency domain (or frequency based) signals P1(ω),P2(ω),P3(ω),PN(ω) indicative of the frequency content of the input signals. Instead of FFT's, any other technique for obtaining the frequency domain characteristics of the signals P1(t)-PN(t), may be used. For example, the cross-spectral density and the power spectral density may be used to form a frequency domain transfer functions (or frequency response or ratios) discussed hereinafter.

One technique of determining the convection velocity of the turbulent eddies120within the process flow13is by characterizing a convective ridge of the resulting unsteady pressures using an array of sensors or other beam forming techniques, similar to that described in U.S patent application, Ser. No. 10/007,736 and U.S. patent application, Ser. No. 09/729,994, filed Dec. 4, 200, now U.S. Pat. No. 6,609,069, which are incorporated herein by reference.

A data accumulator130accumulates the frequency signals P1(ω)×PN(ω) over a sampling interval, and provides the data to an array processor132, which performs a spatial-temporal (two-dimensional) transform of the sensor data, from the xt domain to the k-ω domain, and then calculates the power in the k-ω plane, as represented by a k-ω plot.

The array processor132uses standard so-called beam forming, array processing, or adaptive array-processing algorithms, i.e. algorithms for processing the sensor signals using various delays and weighting to create suitable phase relationships between the signals provided by the different sensors, thereby creating phased antenna array functionality. In other words, the beam forming or array processing algorithms transform the time domain signals from the sensor array into their spatial and temporal frequency components, i.e. into a set of wave numbers given by k=2π/λ where λ is the wavelength of a spectral component, and corresponding angular frequencies given by ω=2πv.

The prior art teaches many algorithms of use in spatially and temporally decomposing a signal from a phased array of sensors, and the present invention is not restricted to any particular algorithm. One particular adaptive array processing algorithm is the Capon method/algorithm. While the Capon method is described as one method, the present invention contemplates the use of other adaptive array processing algorithms, such as MUSIC algorithm. The present invention recognizes that such techniques can be used to determine flow rate, i.e. that the signals caused by a stochastic parameter convecting with a flow are time stationary and have a coherence length long enough that it is practical to locate sensor units apart from each other and yet still be within the coherence length.

Convective characteristics or parameters have a dispersion relationship that can be approximated by the straight-line equation,
k=ω/u,
where u is the convection velocity (flow velocity). A plot of k-ω pairs obtained from a spectral analysis of sensor samples associated with convective parameters portrayed so that the energy of the disturbance spectrally corresponding to pairings that might be described as a substantially straight ridge, a ridge that in turbulent boundary layer theory is called a convective ridge. What is being sensed are not discrete events of turbulent eddies, but rather a continuum of possibly overlapping events forming a temporally stationary, essentially white process over the frequency range of interest. In other words, the convective eddies120is distributed over a range of length scales and hence temporal frequencies.

To calculate the power in the kω plane, as represented by a k-ω plot (seeFIG. 14) of either the signals, the array processor132determines the wavelength and so the (spatial) wavenumber k, and also the (temporal) frequency and so the angular frequency ω, of various of the spectral components of the stochastic parameter. There are numerous algorithms available in the public domain to perform the spatial/temporal decomposition of arrays of sensor units15-18.

The present invention may use temporal and spatial filtering to precondition the signals to effectively filter out the common mode characteristics Pcommon modeand other long wavelength (compared to the sensor spacing) characteristics in the pipe14by differencing adjacent sensors and retain a substantial portion of the stochastic parameter associated with the flow field and any other short wavelength (compared to the sensor spacing) low frequency stochastic parameters.

In the case of suitable turbulent eddies120(seeFIG. 13) being present, the power in the k-ω plane shown in a k-ω plot ofFIG. 14shows a convective ridge124. The convective ridge represents the concentration of a stochastic parameter that convects with the flow and is a mathematical manifestation of the relationship between the spatial variations and temporal variations described above. Such a plot will indicate a tendency for k-ω pairs to appear more or less along a line124with some slope, the slope indicating the flow velocity.

Once the power in the k-ω plane is determined, a convective ridge identifier134uses one or another feature extraction method to determine the location and orientation (slope) of any convective ridge124present in the kω plane. In one embodiment, a so-called slant stacking method is used, a method in which the accumulated frequency of k-ω pairs in the k-ω plot along different rays emanating from the origin are compared, each different ray being associated with a different trial convection velocity (in that the slope of a ray is assumed to be the flow velocity or correlated to the flow velocity in a known way). The convective ridge identifier134provides information about the different trial convection velocities, information referred to generally as convective ridge information.

The analyzer136examines the convective ridge information including the convective ridge orientation (slope). Assuming the straight-line dispersion relation given by k=ω/u, the analyzer136determines the flow velocity, Mach number and/or volumetric flow, which are output as parameters21. The volumetric flow is determined by multiplying the cross-sectional area of the inside of the pipe with the velocity of the process flow.

Some or all of the functions within the flow logic365may be implemented in software (using a microprocessor or computer) and/or firmware, or may be implemented using analog and/or digital hardware, having sufficient memory, interfaces, and capacity to perform the functions described herein.

Speed of Sound (SOS) Processing

Referring toFIG. 15, another example of flow logic36is shown. While the examples ofFIGS. 15 and 16are shown separately, it is contemplated that the flow logic36may perform all of the functions described with reference toFIGS. 15 and 16. As previously described, the array of at least two sensors located at two at least two locations x1,x2axially along the pipe14sense respective stochastic signals propagating between the sensors within the pipe at their respective locations. Each sensor provides a signal indicating an unsteady pressure at the location of each sensor, at each instant in a series of sampling instants. One will appreciate that the sensor array may include more than two pressure sensors distributed at locations x1 . . .xN. The pressure generated by the acoustic pressure disturbances (e.g., acoustic waves122, seeFIG. 13) may be measured through strained-based sensors and/or pressure sensors. The sensors provide analog pressure time-varying signals P1(t),P2(t),P3(t),PN(t) to the flow logic36. The flow logic36processes the signals P1(t),P2(t),P3(t),PN(t) to first provide output signals indicative of the speed of sound propagating through the fluid (process flow)13, and subsequently, provide output signals in response to pressure disturbances generated by acoustic waves propagating through the process flow13, such as velocity, Mach number and volumetric flow rate of the process flow13.

The flow logic36receives the pressure signals from the array of sensors15-18. A data acquisition unit138digitizes pressure signals P1(t)-PN(t) associated with the acoustic waves122propagating through the pipe14. Similarly to the FFT logic12ofFIG. 12, an FFT logic140calculates the Fourier transform of the digitized time-based input signals P1(t)-PN(t) and provide complex frequency domain (or frequency based) signals P1(ω),P2(ω),P3(ω),PN(ω) indicative of the frequency content of the input signals.

A data accumulator142accumulates the frequency signals P1(ω)-PN(ω) over a sampling interval, and provides the data to an array processor144, which performs a spatial-temporal (two-dimensional) transform of the sensor data, from the xt domain to the k-ω domain, and then calculates the power in the k-ω plane, as represented by a k-ω plot.

To calculate the power in the k-ω plane, as represented by a k-ω plot (seeFIG. 16) of either the signals or the differenced signals, the array processor144determines the wavelength and so the (spatial) wavenumber k, and also the (temporal) frequency and so the angular frequency ω, of various of the spectral components of the stochastic parameter. There are numerous algorithms available in the public domain to perform the spatial/temporal decomposition of arrays of sensor units15-18.

In the case of suitable acoustic waves122being present in both axial directions, the power in the k-ω plane shown in a k-ω plot ofFIG. 16so determined will exhibit a structure that is called an acoustic ridge150,152in both the left and right planes of the plot, wherein one of the acoustic ridges150is indicative of the speed of sound traveling in one axial direction and the other acoustic ridge152being indicative of the speed of sound traveling in the other axial direction. The acoustic ridges represent the concentration of a stochastic parameter that propagates through the flow and is a mathematical manifestation of the relationship between the spatial variations and temporal variations described above. Such a plot will indicate a tendency for k-ω pairs to appear more or less along a line150,152with some slope, the slope indicating the speed of sound.

The power in the k-ω plane so determined is then provided to an acoustic ridge identifier146, which uses one or another feature extraction method to determine the location and orientation (slope) of any acoustic ridge present in the left and right k-ω plane. The velocity may be determined by using the slope of one of the two acoustic ridges150,152or averaging the slopes of the acoustic ridges150,152.

Finally, information including the acoustic ridge orientation (slope) is used by an analyzer148to determine the flow parameters relating to measured speed of sound, such as the consistency or composition of the flow, the density of the flow, the average size of particles in the flow, the air/mass ratio of the flow, gas volume fraction of the flow, the speed of sound propagating through the flow, and/or the percentage of entrained air within the flow.

Similar to the array processor132ofFIG. 12, the array processor144uses standard so-called beam forming, array processing, or adaptive array-processing algorithms, i.e. algorithms for processing the sensor signals using various delays and weighting to create suitable phase relationships between the signals provided by the different sensors, thereby creating phased antenna array functionality. In other words, the beam forming or array processing algorithms transform the time domain signals from the sensor array into their spatial and temporal frequency components, i.e. into a set of wave numbers given by k=2π/λ where λ is the wavelength of a spectral component, and corresponding angular frequencies given by ω=2πv.

One such technique of determining the speed of sound propagating through the process flow13is using array processing techniques to define an acoustic ridge in the k-ω plane as shown inFIG. 16. The slope of the acoustic ridge is indicative of the speed of sound propagating through the process flow13. The speed of sound (SOS) is determined by applying sonar arraying processing techniques to determine the speed at which the one dimensional acoustic waves propagate past the axial array of unsteady pressure measurements distributed along the pipe14.

The flow logic36of the present embodiment measures the speed of sound (SOS) of one-dimensional sound waves propagating through the process flow13to determine the gas volume fraction of the process flow13. It is known that sound propagates through various mediums at various speeds in such fields as SONAR and RADAR fields. The speed of sound propagating through the pipe14and process flow13may be determined using a number of known techniques, such as those set forth in U.S. patent application Ser. No. 09/344,094, filed Jun. 25, 1999, now U.S. Pat. No. 6,354,147; U.S. patent application Ser. No. 10/795,111, filed Mar. 4, 2004; U.S. patent application Ser. No. 09/997,221, filed Nov. 28, 2001, now U.S. Pat. No. 6,587,798; U.S. patent application Ser. No. 10/007,749, filed Nov. 7, 2001, and U.S. patent application Ser. No. 10/762,410, filed Jan. 21, 2004, each of which are incorporated herein by reference.

While the sonar-based flow meter using an array of sensors15-18to measure the speed of sound of an acoustic wave propagating through the mixture is shown and described, one will appreciate that any means for measuring the speed of sound of the acoustic wave may used to determine the entrained gas volume fraction of the mixture/fluid or other characteristics of the flow described hereinbefore.

The analyzer148of the flow logic36provides output parameters21indicative of characteristics of the process flow13that are related to the measured speed of sound (SOS) propagating through the process flow13. For example, to determine the gas volume fraction (or phase fraction), the analyzer148assumes a nearly isothermal condition for the process flow13. As such the gas volume fraction or the void fraction is related to the speed of sound by the following quadratic equation:
Ax2+Bx+C=0

wherein x is the speed of sound, A=1+rg/rl*(KeffP-1)−Keff/P, B=Keff/P-2+rg/rl; C=1-Keff/rl*ameas^2); Rg=gas density, rl=liquid density, Keff=effective K (modulus of the liquid and pipewall), P=pressure, and ameas=measured speed of sound.

Alternatively, the sound speed of a mixture can be related to volumetric phase fraction (φi) of the components and the sound speed (a) and densities (ρ) of the component through the Wood equation.

One dimensional compression waves propagating within a process flow13contained within a pipe14exert an unsteady internal pressure loading on the pipe. The degree to which the pipe displaces as a result of the unsteady pressure loading influences the speed of propagation of the compression wave. The relationship among the infinite domain speed of sound and density of a mixture; the elastic modulus (E), thickness (t), and radius (R) of a vacuum-backed cylindrical conduit; and the effective propagation velocity (aeff) for one dimensional compression is given by the following expression:

The mixing rule essentially states that the compressibility of a process flow (1/(ρa2)) is the volumetrically-weighted average of the compressibilities of the components. For a process flow13consisting of a gas/liquid mixture at pressure and temperatures typical of paper and pulp industry, the compressibility of gas phase is orders of magnitudes greater than that of the liquid. Thus, the compressibility of the gas phase and the density of the liquid phase primarily determine mixture sound speed, and as such, it is necessary to have a good estimate of process pressure to interpret mixture sound speed in terms of volumetric fraction of entrained gas. The effect of process pressure on the relationship between sound speed and entrained air volume fraction is shown inFIG. 17.

As described hereinbefore, the flow logic36of the present embodiment includes the ability to accurately determine the average particle size of a particle/air or droplet/air mixture within the pipe14and the air to particle ratio. Provided there is no appreciable slip between the air and the solid coal particle, the propagation of one dimensional sound wave through multiphase mixtures is influenced by the effective mass and the effective compressibility of the mixture. For an air transport system, the degree to which the no-slip assumption applies is a strong function of particle size and frequency. In the limit of small particles and low frequency, the no-slip assumption is valid. As the size of the particles increases and the frequency of the sound waves increase, the non-slip assumption becomes increasing less valid. For a given average particle size, the increase in slip with frequency causes dispersion, or, in other words, the sound speed of the mixture to change with frequency. With appropriate calibration the dispersive characteristic of a process flow13will provide a measurement of the average particle size, as well as, the air to particle ratio (particle/fluid ratio) of the process flow 13.

In accordance with the present invention the dispersive nature of the system utilizes a first principles model of the interaction between the air and particles. This model is viewed as being representative of a class of models that seek to account for dispersive effects. Other models could be used to account for dispersive effects without altering the intent of this disclosure (for example, see the paper titled “Viscous Attenuation of Acoustic Waves in Suspensions” by R. L. Gibson, Jr. and M. N. Toksöz), which is incorporated herein by reference. The model allows for slip between the local velocity of the continuous fluid phase and that of the particles.

The following relation can be derived for the dispersive behavior of an idealized fluid particle mixture.

In the above relation, the fluid SOS, density (ρ) and viscosity (φ)) are those of the pure phase fluid, vpis the volume of individual particles and φpis the volumetric phase fraction of the particles in the mixture.

Two parameters of particular interest in steam processes and air-conveyed particles processes are particle size and air-to-fuel mass ratio or steam quality. To this end, it is of interest to examine the dispersive characteristics of the mixture as a function of these two variables.FIGS. 18 and 19show the dispersive behavior in relations to the speed of sound for coal/air mixtures with parameters typical of those used in pulverized coal deliver systems.

In particularFIG. 18shows the predicted behavior for nominally 50 μm size coal in air for a range of air-to-fuel ratios. As shown, the effect of air-to-fuel ratio is well defined in the low frequency limit. However, the effect of the air-to-fuel ratio becomes indistinguishable at higher frequencies, approaching the sound speed of the pure air at high frequencies (above ˜100 Hz).

Similarly,FIG. 19shows the predicted behavior for a coal/air mixture with an air-to-fuel ratio of 1.8 with varying particle size. This figure illustrates that particle size has no influence on either the low frequency limit (quasi-steady) sound speed, or on the high frequency limit of the sound speed. However, particle size does have a pronounced effect in the transition region.

FIGS. 8 and 9illustrate an important aspect of the present invention. Namely, that the dispersive properties of dilute mixtures of particles suspended in a continuous liquid can be broadly classified into three frequency regimes: low frequency range, high frequency range and a transitional frequency range. Although the effect of particle size and air-to-fuel ratio are inter-related, the predominant effect of air-to-fuel ratio is to determine the low frequency limit of the sound speed to be measured and the predominate effect of particle size is to determine the frequency range of the transitional regions. As particle size increases, the frequency at which the dispersive properties appear decreases. For typical pulverized coal applications, this transitional region begins at fairly low frequencies, ˜2 Hz for 50 μm size particles.

Given the difficulties measuring sufficiently low frequencies to apply the quasi-steady model and recognizing that the high frequency sound speed contains no direct information on either particle size or air-to-fuel ratio, it becomes apparent that the dispersive characteristics of the coal/air mixture should be utilized to determine particle size and air-to-fuel ratio based on speed of sound measurements.

Some or all of the functions within the flow logic36may be implemented in software (using a microprocessor or computer) and/or firmware, or may be implemented using analog and/or digital hardware, having sufficient memory, interfaces, and capacity to perform the functions described herein.

WhileFIGS. 12 and 15depict two different embodiments of the flow logic36to measure various parameters of the flow process, the present invention contemplates that the functions of these two embodiments may be performed by a single flow logic36.

The present invention provides a system of one or more configurable flowmeters that allows an individual, locally or remotely, to selectively activate one or more functions of the flowmeter. The present invention also provides a system that allows an individual, locally or remotely, to selectively activate one or more latent flowmeters in the system. While various flowmeters are described herein as having configurable functions, it is contemplated that the flowmeters described herein may be selectable only to turn them on or off (e.g., latent/activated). Similarly, the flowmeters described herein may be only configurable, having functions that may be configured, but not being selectable to turn on/off. Furthermore, it is contemplated that the flowmeters described herein may be configurable (e.g., various functions) and selectable (e.g., on/off).

The system of configurable flowmeters may be a distributed control system (DCS), which receives input signals from conventional meters and devices in the process flow. The system also provides a method of flowmeter selection and billing. Such a system allows the user to install latent (or dormant) flowmeters when the plant is built (or at a later time) that are accessed by the user only when they are needed, thereby saving significant expense later in the life of the plant equipment or developing needs when more or different flowmeters and/or parameters are needed to be sensed by the user. The invention also allows for automatic flowmeter selection reconfiguration without user intervention.

It should be understood that, unless otherwise stated herein, any of the features, characteristics, alternatives or modifications described regarding a particular embodiment herein may also be applied, used, or incorporated with any other embodiment described herein.