Systems and methods of monitoring and controlling heat transfer operations

Abstract

A heat exchanger includes a combustion section, a decoupler or exit manifold section, heat transfer tubes, sensing tubes, and a controller. The combustion section is configured to receive and combust a fuel to produce a combustion stream. The heat transfer tubes are configured to receive the combustion stream from the combustion section, where the heat transfer tubes are configured to transfer heat from the combustion stream to a heat transfer medium that is external to the heat transfer tubes. The transfer of heat yields a cooled combustion stream. The sensing tubes are configured to yield one or more temperature measurements, where the sensing tubes are disposed in proximity to the plurality of heat transfer tubes. One or more temperature sensors are configured to measure the temperature of the heat transfer medium in the vicinity of the sensing tubes. The decoupler section is configured to receive the cooled combustion stream. The controller is configured to regulate a firing rate of the combustion section. The heat exchanger can include electrically heated tubes, in which the power input is regulated by the controller.

Description

Attorney Docket No.: 47565-0067WO1 SYSTEMS AND METHODS OF MONITORING AND CONTROLLING HEAT TRANSFER OPERATIONS CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Patent Application No. 63 / 697,679, which was filed on September 23, 2024, and is incorporated by reference herein in its entirety. TECHNICAL FIELD

[0002] This description generally relates to systems and methods of monitoring and controlling heat transfer operations relating to heat exchangers, pulse heaters, or the like, and more specifically, in fluidized bed applications. BACKGROUND

[0003] In general, heat transfer operations involving heater tubes can be performed using a thermal device such as heat exchanger (including a pulse combustion heat exchanger) or the like. For instance, the heat exchanger allows continuous or intermittent heat transfer between fluids. It may be necessary to ensure optimal performance and safe operation of the heat exchanger. SUMMARY

[0004] Implementations according to this disclosure includes a heat exchanger for accurately measuring temperatures of heat transfer tubes at multiple locations and controlling its operations based on the measured temperatures. The heat exchanger includes a combustion section, heat transfer tubes, sensing tubes, one or more temperature sensors, a decoupler section or exit manifold section, and a controller. The combustion section is configured to receive and combust a fuel to produce a combustion stream. The heat transfer tubes are configured to (i) receive the combustion stream from the combustion section and (ii) transfer heat from the combustion stream to a heat transfer medium that is external to the plurality of heat transfer tubes, where said transfer of heat yields a cooled combustion stream. The sensing tubes are configured to yield one or more temperature measurements, where the sensing tubes are disposed in proximity to the heat transfer tubes. The one or more temperature sensors measure temperature of the fluidized bed or heat transfer medium that is external to the heat transfer tubes and heat sensing tubes. TheAttorney Docket No.: 47565-0067WO1 decoupler section or exit manifold section is configured to receive the cooled combustion stream. The controller is configured to regulate a firing rate of the combustion section.

[0005] Implementations according to this disclosure includes a method of determining temperature within a reactor. The method includes (i) measuring a temperature Ti,p for each ithsensing tube of at least one heat exchanger at each plane p of the heat exchanger, (ii) measuring at least one temperature Tbed,kof a heat transfer medium that is external to the heat exchanger, and (iii) determining a difference between each Ti,pand Tbed,kto obtain a delta temperature ΔTi,p. Each ithsensing tube of the heat exchanger is disposed in proximity to a j number of heat transfer tubes of the heat exchanger. The heat transfer medium is disposed within the reactor and is in contact with the i number of sensing tubes and j number of heat transfer tubes. Measuring Ti,p and Tbed,k can be performed in any order. Each of i, j, p, and k is, independently, an integer of 1 or more.

[0006] Implementations according to this disclosure includes a heat exchanger for accurately measuring temperatures of heat transfer tubes at multiple locations and controlling its operations based on the measured temperatures. The heat exchanger includes a flue gas plenum, heat transfer tubes, sensing tubes, one or more temperature sensors, an exit manifold section, and a controller. The flue gas plenum receives a combustion stream from a combustor. The heat transfer tubes are configured as tube within tube such that the combustion stream travels away from the flue gas plenum in the inner tube and returns in the outer tube, where the outer tubes are configured to transfer heat from the combustion stream to a heat transfer medium that is external to the heat transfer tubes and where said transfer of heat yields a cooled combustion stream. The sensing tubes are configured to yield one or more temperature measurements, where the sensing tubes are disposed in proximity to the heat transfer tubes. The one or more temperature sensors are configured to measure temperature of the fluidized bed or the heat transfer medium that is external to the heat transfer tubes and the heat sensing tubes. The exit manifold section is configured to receive the cooled combustion stream. The controller is configured to regulate a firing rate of the combustor.

[0007] Implementations according to this disclosure includes a heat exchanger for accurately measuring temperatures of heat transfer tubes at multiple locations and controlling its operations based on the measured temperatures. The heat exchanger includes heat transfer tubes or thermowells, sensing tubes, one or more temperature sensors, and one or more controllers. The heat transfer tubes or thermowells are configured toAttorney Docket No.: 47565-0067WO1 enclose electrical heater rods or heating elements, where the heat transfer tubes are configured to transfer heat from the heater rods or elements to a heat transfer medium that is external to the plurality of heat transfer tubes. The sensing tubes are configured to yield one or more temperature measurements, where the sensing tubes are disposed in proximity to the plurality of heat transfer tubes. The one or more temperature sensors are configured to measure temperature of the fluidized bed or heat transfer medium that is external to the heat transfer tubes and the heat sensing tubes. The one or more controllers are configured to regulate power input to groups of heater rods or heating elements.

[0008] The details of one or more embodiments of the subject matter of this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a diagram of an example heat exchanger system.

[0010] FIG.2 is a sectional view of heat transfer tubes and heat sensing tubes of an example heat exchanger system.

[0011] FIG. 3 is a diagram of an example processor-based computing device.

[0012] FIGS.4 and 5 are flow chart diagrams of example processes for monitoring and controlling heat transfer operations.

[0013] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION

[0014] The heat exchanger facilitates heat transfer operations by allowing continuous or intermittent heat exchange between fluids. The heat exchanger is used in various industrial processes where thermal energy needs to be efficiently transferred from one fluid to another.

[0015] The operating environment for a heat exchanger can be demanding. One application of heat exchanger is providing indirect heat into a fluidized bed steam reformer to generate syngas from carbonaceous material. This demanding environment can be characterized by various factors including the following: [1] elevated temperature of tubes (650 to 900 °C); [2] external pressure on tubes (e.g., 0 to 5 barg); [3] operation in the creep-Attorney Docket No.: 47565-0067WO1 fatigue or creep-buckling range; [4] potential for fouling due to the presence of eutectic formers or low melting compounds (alkalis, silicates, chlorides, etc.) and / or hot corrosion due to chlorine, sulfur, and nitrogen species; [5] potential for local tube thinning due to erosion; and [6] potential for non-uniform fluidization or poor fluidization quality due to process excursions or lack of control on fluidized bed operating parameters.

[0016] Heat exchangers, particularly in a bundle form, can include many long tubes connected to one or two tube sheets. For instance, in an elevated temperature fluidized bed, heat transfer from these tubes occurs through particle convection, radiation, and gas convection. The high heat flux characteristics of these heat exchangers can cause divergence in that if local heat transfer is hindered (due to stagnant particles, fouling, etc.), the tube surface temperature can increase over time. If not properly monitored and controlled, this can lead to several failure modes such as [1] exceeding the design limit of mean metal temperature in one or more tubes or leading to creep-fatigue or creep-buckling failure and tube breach or [2] tube collapse due to external pressure and excessive local tube temperature.

[0017] In the event of the failure of only a few tubes, it may be possible to take a short outage, plug the breached tubes, and continue heat transfer operations. However, if large number of tubes are breached, the heat exchanger may need to be replaced or repaired by retubing. Such actions would adversely impact end product generation and the overall efficiency of heat transfer operations.

[0018] Implementations according to this disclosure address heat exchanger issues described above by at least [1] monitoring and accurately measuring temperatures of heat transfer tubes at multiple locations and [2] controlling, based on the measured temperatures, heat transfer operations including regulation of firing rate of the heat exchanger.

[0019] For instance, temperatures can be monitored and measured at different planes and / or locations in proximity to the heat transfer tubes and a fluidized bed or heat transfer medium that is external to the heat exchanger. For instance, a reactor can include the heat exchanger having the heat transfer tubes, and there can be fluidized bed or heat transfer medium external to the heat transfer tubes. Once the temperatures are measured at different planes and / or locations, the temperature differences between (i) each of the measured temperatures and (ii) temperature of the fluidized bed or heat transfer medium can be determined. Such temperature differences can be averaged and compared to a threshold value to determine whether or not firing rate of heat exchanger needs to beAttorney Docket No.: 47565-0067WO1 modulated, or to control operation of the heat exchanger. In some implementations, temperatures can be monitored and measured at different planes and / or locations in real- time, intermittently, or periodically over a recurring time period. Further, in some implementations, the temperatures that are measured over a certain time period can be used to determine the temperature differences (between (i) each of the measured temperatures and (ii) temperature of the fluidized bed or heat transfer medium) over the certain time period. Such temperature differences can be averaged and the average value can be compared to a respective threshold value to thereby control the operation of the heat exchanger.

[0020] For instance, heat sensing tubes configured to measure temperatures at different locations along the respective heat sensing tubes can be strategically disposed in proximity to heat transfer tubes of the heat exchanger. Such heat sensing tubes can be communicatively connected to (e.g., wired or wirelessly connected to, in data communication with) a controller that controls the heat transfer operations of the heat exchanger.

[0021] Further, such heat sensing tubes can be used to obtain temperature measurements at multiple planes and / or locations along the axis of each of the heat sensing tubes. For instance, the heat sensing tubes can be equipped with or have multiple internal temperature sensors positioned at multiple axial locations along the axis or longitudinal length of each heat sensing tube. For instance, the temperature sensors can be disposed within a lumen of each of the one or more of the heat sensing tubes.

[0022] Moreover, temperature of the fluidized bed or heat transfer medium that is external to these heat sensing tubes can be measured. For instance, the reactor can include the heat exchanger and the heat sensing tubes, and there can be fluidized bed or heat transfer medium external to the heat exchanger and heat sensing tubes. For instance, one or more of the heat sensing tubes that are in direct contact with the fluidized bed or the heat transfer medium can measure such temperature. In some implementations, temperature sensors such as thermocouple(s), and / or fiber optic temperature sensors can be disposed at one or more locations or zones of interest near or at the heat exchanger or bed’s surface to measure the temperature of the fluidized bed. For instance, temperature sensors such as infrared thermometers or pyrometers configured to measure temperature by detecting the infrared radiation emitted by the surface of the fluidized bed can be disposed in proximity to or at the heat exchanger or bed’s surface to measure the temperature of the fluidized bed.Attorney Docket No.: 47565-0067WO1

[0023] Such heat sensing tubes and / or temperature sensors can be communicatively connected to a controller of the heat exchanger so as to monitor and control the operation of the heat-exchanger. For instance, the controller can monitor and receive temperature measurements and perform temperature-related computations or determinations. For instance, the controller can determine average temperature(s) or average temperature difference(s) of the heat transfer tubes in real-time, intermittently, or over a certain time period, which can accurately represent the status of the heat transfer tubes. Further, based on such average temperature(s) and / or comparing such average temperature(s) or temperature difference(s) to respective threshold value(s), the controller can control the heat transfer operations, including regulation of firing rate of the heat exchanger.

[0024] FIG. 1 is a diagram of an example heat exchanger system 100. The system 100 can include a heat exchanger 102 and a controller 130 that is communicatively connected to (e.g., wired or wirelessly connected to, in data communication with) the heat exchanger 102.

[0025] The heat exchanger 102 can include a combustion section 104, a heat transfer section 106, and a decoupler section 108.

[0026] The combustion section 104 can receive and combust a fuel to produce a combustion stream. For instance, the combustion section 104 can include a combustion chamber where the fuel can be mixed with air, an oxidizer, or the like to produce the combustion stream.

[0027] The heat transfer section 106 can include heat transfer tubes 110 configured to receive the combustion stream from the combustion section 104. For instance, as the combustion stream flows through these heat transfer tubes 110, heat can be transferred from the combustion stream to a heat transfer medium, such as water, oil, another fluid, or fluidized bed particles that is external to the heat transfer tubes 110. The heat transfer tubes 110 can be configured to transfer heat from the combustion stream to such heat transfer medium, where the transfer of heat can yield a cooled combustion stream.

[0028] The heat transfer section 108 can further include heat sensing tubes 112 that are disposed in between or proximity to the heat transfer tubes 110 and configured to measure temperatures at different locations along the respective heat sensing tubes 112, which will be described in more details below. Moreover, although only two heat sensing tubes 112 are shown in FIG. 1, there can be more than two heat sensing tubes 112.Attorney Docket No.: 47565-0067WO1

[0029] The decoupler section 108 can receive the cooled combustion stream from the heat transfer section 106. In some implementations, the decoupler section 108 can separate, redirect, decouple pulsations, or further process the remaining gases after they have released most of their heat. The decoupler might include mechanisms to adjust the flow of the cooled gases, manage pressure differentials, or direct the gases to exhaust systems, further treatment, or recirculation.

[0030] The controller 130 can control at least some operations of the heat exchanger 102. The controller 130 can be a processor-based device that is (i) disposed at or within the heat exchanger 102 or positioned outside the heat exchanger 102, and (ii) communicatively connected to the heat exchanger 102. For example, the controller 130 can be a computing device (such as a computing device 300 shown in FIG. 3) including an end-user device, programmable logic controller (PLC), information appliance, mobile computer, handheld computer, cloud-based platform, distributed computing platform, and the like. The controller 130 can include or run a software or an application for (i) monitoring and determining temperature measurements and performing temperature computations associated with the heat sensing tubes 112 and external heat transfer medium 122, and (ii) controlling the operations of the heat exchanger 102. For example, the controller 130 can regulate a firing rate of the combustion section 104 based on the temperature measurements or temperature computations using the temperature measurements, as will be further described below.

[0031] Regarding the heat transfer section 108, each of the heat sensing tubes 112 can include one or more temperature sensors (e.g., thermocouples) disposed at each of the one or more of the heat sensing tubes 112. In some implementations, one or more temperature sensors can be disposed within a lumen of each of the one or more of the heat sensing tubes 112. For example, each of the one or more of the heat sensing tubes 112 can include multiple temperature sensors. For example, multiple temperature sensors can be positioned at different axial locations along a length of each of the one or more heat sensing tubes 112. For example, multiple temperature sensors within each of the one or more heat sensing tubes 112 can be used to determine an axial temperature measurement for a respective heat sensing tube of the heat sensing tubes 112.

[0032] In operation, the heat sensing tubes 112 can be used to monitor and determine temperatures at (i) different planes and / or locations in proximity to the heatAttorney Docket No.: 47565-0067WO1 transfer tubes and (ii) outside the bundle of the heat transfer tubes 110 and the heat sensing tubes 112.

[0033] For example, determining temperatures at different planes and / or locations in proximity to the heat transfer tubes can include measuring temperatures Ti,p at different planes or locations of the heat exchanger 102 (for example, Ti,p denotes the temperature of ithheat sensing tube 112 at pthplane), which will be further described below.

[0034] For example, determining temperatures outside the bundle of the heat transfer tubes 110 and the heat sensing tubes 112 can include measuring temperature Tbed of a fluidized bed or heat transfer medium 122 that is external to the heat exchanger 102. For instance, a reactor can include the heat exchanger 102 and the heat sensing tubes 112, and there can be fluidized bed or heat transfer medium external to the heat exchanger 102 and the heat sensing tubes 112.

[0035] First, each of the heat sensing tubes 112 can measure a temperature Ti,pfor each ithheat sensing tube (of the heat sensing tubes 112) at a plane p of the heat exchanger 102 (or a plane of each of the heat transfer tubes 110 or each of the heat sensing tubes 112), where each ithsensing tube can be disposed in proximity to one or more of j number of the heat transfer tubes 110. For example, for illustrative purposes, a first plane and pthplane are shown in FIG. 1. Moreover, for illustrative purposes, a first heat sensing tube’s first plane temperature measurement location 116 and a pthplane temperature measurement location 114 are shown in FIG. 1, as well as a second heat sensing tube’s first plane temperature measurement location 120 and a pthplane temperature measurement 118. The temperature sensors of the heat sensing tubes 112 can be disposed at or in vicinity of each of the temperature measurement locations 114, 116, 118, and 120 to measure temperatures at each of the temperature measurement locations 114, 116, 118, and 120. Although only two heat sensing tubes 112, four temperature measurement locations 114, 116, 118, and 120, and two planes (with dotted lines) are shown in FIG. 1, there can be more than two heat sensing tubes 112, more or less than four temperature measurement locations, and more than two planes.

[0036] For purposes of illustrating heat transfer tubes and sensing tubes in a plane, FIG. 2 shows a sectional view of heat transfer tubes (e.g., the heat transfer tubes 110) and heat sensing tubes (e.g., the heat sensing tubes 112) at pthplane of an example of the heat exchanger system 100. For example, plain circle illustrations indicate the heat sensing tubes in the pthplane and bold circle illustrations indicate the heat transfer tubes in the pthAttorney Docket No.: 47565-0067WO1 plane. For example, one of the plain circles indicates the ithheat sensing tube and one of the bold circles indicates jthheat transfer tube in the pthplane. For example, each of i, j, and p can be, independently, an integer of 1 or more.

[0037] Referring back to the operation of the heat exchanger system 100 of FIG.1, one or more of the temperature sensors such as thermocouples can measure a temperature Tbedof a fluidized bed or heat transfer medium 122 that is external to the heat exchanger 102. For example, the fluidized bed or the heat transfer medium 122 can be in contact with one or more of the heat sensing tubes 112 and / or one or more of the heat transfer tubes 110. In FIG. 1, fluidized bed or heat transfer medium 122, which is external to the heat exchanger 102, is shown. Although the box representing the heat exchanger 102 appears to capture fluidized bed or the heat medium 122, the box is drawn for sole purpose of aiding illustration of a connectivity between the heat exchanger 102 and the controller 130. Accordingly, regardless of the box illustration of the heat exchanger 102, it should be construed from FIG. 1 that the fluidized bed or heat transfer medium 122 is external to the heat exchanger 102.

[0038] In some implementations, temperature sensors such as thermocouples and / or fiber optic temperature sensors can be disposed at one or more locations or zones of interest around or at the heat exchanger 102 or bed’s surface to measure the temperature of the fluidized bed or heat transfer medium 122. For instance, temperature sensors such as infrared thermometers or pyrometers that are configured to measure temperature by detecting the infrared radiation emitted by the surface of the fluidized bed can be disposed around or at the heat exchanger 122 or bed’s surface to measure the temperature of the fluidized bed or heat transfer medium 122.

[0039] In some implementations, measurement of Ti,p and Tbed can be performed in any order.

[0040] In some implementations, measuring Ti,pand Tbedcan be performed at successive time periods. In some implementations, the successive time periods can range from 1 to 30 minutes and in particular between 3 and 15 minutes.

[0041] After measuring Ti,pand Tbedat multiple different locations and the controller 130 receives measurements of data including Ti,pand Tbed, the controller 130 can determine differences between each Ti,p and Tbed to obtain each respective temperature difference ΔT.Attorney Docket No.: 47565-0067WO1

[0042] After determining each respective temperature difference ΔT for multiple locations, the controller 130 can determine one or more average values ΔTavg of multiple ΔT values.

[0043] In some implementations, the controller 130 can determine ΔTavg over the axis (e.g., axial length, longitudinal axis) of each of the heat sensing tubes 112, respectively. For example, ΔTavgover longitudinal axis (ΔTavg, axial) can be determined for each heat sensing tube by averaging temperature measurements obtained by the temperature sensors of the heat sensing tubes 112 disposed at or in vicinity of multiple temperature measurement locations (e.g., a group of measurement locations 114, 116, a group of measurement locations 118, 120) over longitudinal axis of each heat sensing tube of the heat sensing tubes 112. For example, the controller 130 can average a group of ΔTi,p values for the p number of planes of each ithsensing tube to yield an i number of axial average values (e.g., i number of ΔTavg, axialvalues). For example, for illustrative purposes, in case the temperature measurements are obtained over the two heat sensing tubes 112 and two number of planes (e.g., first plane and pthplane being second plane, as depicted in FIG. 1), the temperature measurements can correspond to (i) ΔT1,1at temperature measurement location 116 and ΔT1,2at temperature measurement location 114, from which ΔTavg, axialof the first heat sensing tube can be obtained, and (ii) ΔT2,1 at temperature measurement location 120 and ΔT2,2at temperature measurement location 118, from which ΔTavg, axialof the second heat sensing tube can be obtained, thus yielding two axial average values for the corresponding two heat sensing tubes.

[0044] In some implementations, the controller 130 can determine ΔTavg over all (or two or more) of the heat sensing tubes 112 at targeted one or more planes. For example, ΔTavg of targeted plane(s) (ΔTavg, pth plane) can be determined for each of the specific plane(s) by averaging temperature measurement obtained by the temperature sensors disposed at or in vicinity of multiple temperature measurement locations (e.g., a group of measurement locations 114, 118, a group of measurement locations 116, 120) at each plane of the targeted one or more planes. For example, the controller 130 can average a group of ΔTi,p values for the i number of sensing tubes at each pthplane to yield a p number of plane average values, (e.g., p number of ΔTavg, pth planevalues). For example, for illustrative purposes, in case the temperature measurements are obtained over the two number of planes (e.g., first plane and pthplane being second plane, as depicted in FIG. 1) of two heat sensing tubes 112, the temperature measurements can correspond to (i) ΔT1,1at temperature measurementAttorney Docket No.: 47565-0067WO1 location 116 and ΔT2,1 at temperature measurement location 120, from which ΔTavg, 1st plane can be obtained, and (ii) ΔT1,2 at temperature measurement location 114 and ΔT2,2 at temperature measurement location 118, from which ΔTavg, 2nd planecan be obtained, thus yielding two plane average values.

[0045] Throughout this disclosure, ΔTavg, axial values and ΔTavg, pth plane values can be collectively referred to as ΔTavgvalues.

[0046] In some implementations, the controller 130 can determine average of Ti,pfirst and thereafter determine the ΔTavg values between the average of Ti,p and the Tbed.

[0047] After determining ΔTavgvalues, the controller 130 can determine (i) a bundle average value of ΔTavgvalues, (ii) a rolling average value of ΔTavgvalues, and / or (iii) bundle rolling average values of ΔTavg values.

[0048] For example, the bundle average value corresponds to an average value of (i) the p number of plane average values (ΔTavg, pth plane) and (ii) i number of axial average values (ΔTavg, axial).

[0049] For example, the rolling average value corresponds to an average value of one or more ΔTavgvalues over certain time periods. As described above, measuring Ti,pand Tbedcan be performed at successive time periods, before determining ΔTavgvalues. In some implementations, the rolling average value corresponds to an average value of one or more pth planevalues over certain time periods. In some implementations, the rolling average value corresponds to an average value of one or more ΔTavg, axialvalues over certain time periods.

[0050] For example, the bundle rolling average value corresponds to an average value of two or more of successive bundle average values over certain time periods.

[0051] After determining i) the bundle average value, (ii) the rolling average value, and / or (iii) the bundle rolling average value, one or more of these values can be compared to respective threshold value(s). For example, the controller 130 can compare one or more of i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or (iv) ΔTavg values to respective threshold value(s). In some implementations, each of the threshold values can be established according to guidelines for each of i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavg values (including ΔTavg, pth plane, ΔTavg, axial values, and / or their rolling averages).Attorney Docket No.: 47565-0067WO1

[0052] Based on the comparison of above-noted value(s) to respective threshold value(s), the controller 130 can control heat transfer operations of the heat exchanger 102. For example, based on the one or more values of (i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or (iv) ΔTavg values or their rolling averages being greater than or equal to respective threshold value(s), the controller 130 can control the heat transfer operations of the heat exchanger 102. For example, controlling the heat transfer operations can include regulating a firing rate (e.g., powering rate) of the combustion section 104.

[0053] In some implementations, based on one or more of value of the i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavg values being greater than or equal to respective threshold value(s), the controller 130 can decrease the firing rate or stop operation of the heat exchanger 102.

[0054] In some implementations, based on one or more values of the i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavg values being less than the respective threshold value(s), the controller 130 can increase or maintain the firing rate of the heat exchanger 102.

[0055] In some implementations, the controller 130 or other computing device (e.g., the user device, a third-party device, a server) in data communication with the controller 130 can incorporate a machine-learning (ML) model (which may be a deep-learning model) trained to control the heat transfer operations based on one or more values of the i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavg values. For example, the training data and output data can be logged (e.g., stored or transmitted for storage) in the controller 130 or other computing device to train the machine-learning model. The training data can include the i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavg values and output data can include data representing controlling of heat exchanger operations.

[0056] In some implementations, there can be multiple heat exchangers in a reactor, where operations described herein can be applied to one or more of the multiple heat exchangers having heat transfer tubes (e.g., the heat transfer tubes 110) and heat sensing tubes (e.g., the heat sensing tubes 112).

[0057] In some implementations, the implementations described in this disclosure, including the operations described with respect to the heat exchanger system 100 can beAttorney Docket No.: 47565-0067WO1 applied to a heat exchanger having electrical heating elements or fire rods in supplant of heat transfer tubes.

[0058] FIG. 3 is a diagram of an example processor-based computing device 300. The computing device 300 can implement a temperature determination (e.g., computation) and heat exchanger operations control technique or run an application or software related to the temperature determination and heat exchanger operations control technique, as described above with respect to FIG.1. The computing device 300 is representative of the type of computing device that can correspond to, can be present in, or can be used in conjunction with at least some aspects of the controller 130 of FIG. 1 and / or other devices at least partially implementing functionality or techniques described with respect to the system 100 of FIG. 1. The computing device 300 is illustrative only and does not exclude the possibility of another processor- or controller-based system being used in or with any of the aforementioned aspects of the controller 130.

[0059] In one aspect, the computing device 300 can include one or more hardware and / or software components configured to execute software programs, such as software for obtaining, storing, processing, and analyzing signals, data, or both. For example, the computing device 300 can include one or more hardware components such as, for example, a processor 305, a random-access memory (RAM) 310, a read-only memory (ROM) 320, a storage 330, a database 340, one or more input / output (I / O) modules 350, and an interface 360. Alternatively, and / or additionally, the computing device 300 can include one or more software components such as, for example, a computer-readable medium including computer-executable instructions for performing techniques or implement functions of tools consistent for the position and corrosion determination. It is contemplated that one or more of the hardware components listed above can be implemented using software. For example, the storage 330 can include a software partition associated with one or more other hardware components of the computing device 300. The computing device 300 can include additional, fewer, and / or different components than those listed above. It is understood that the components listed above are illustrative only and not intended to be limiting or exclude suitable alternatives or additional components.

[0060] The processor 305 can include one or more processors, each configured to execute instructions and process data to perform one or more functions associated with the computing device 300. The term “processor,” as generally used herein, refers to any logic processing unit, such as one or more central processing units (CPUs), PLCs, digital signalAttorney Docket No.: 47565-0067WO1 processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and similar devices. As illustrated in FIG. 3, the processor 305 can be communicatively coupled to the RAM 310, the ROM 320, the storage 330, the database 340, the I / O module 350, and the interface 360. The processor 305 can be configured to execute sequences of computer program instructions to perform various processes (for example, techniques), such as those described herein for determining temperature differences, the bundle average value, the rolling average value, the bundle rolling average values, ΔTavg values, controlling and automating heat exchanger operations, etc. The computer program instructions can be loaded into the RAM 310 for execution by the processor 305.

[0061] The RAM 310 and the ROM 320 can each include one or more devices for storing information associated with an operation of the computing device 300 and / or the processor 305. For example, the ROM 320 can include a memory device configured to access and store information associated with the computing device 300, including information for identifying, initializing, and monitoring the operation of one or more components and subsystems of the computing device 300. The RAM 310 can include a memory device for storing data associated with one or more operations of the processor 305. For example, the ROM 320 can load instructions into the RAM 310 for execution by the processor 305.

[0062] The storage 330 can include any type of storage device configured to store information that the processor 305 can use to perform processes consistent with the disclosed implementations. The database 340 can include one or more software and / or hardware components that cooperate to store, organize, sort, filter, and / or arrange data used by the computing device 300 and / or the processor 305. For example, the database 340 can include end-user profile information, historical activity and end-user specific information, predetermined menu / display options, and other end-user related data. Alternatively, the database 340 can store additional and / or different information. The database 340 can be used to store data relating to determination of temperature differences, the bundle average value, the rolling average value, the bundle rolling average values, ΔTavgvalues, controlling and automating of heat exchanger operations, etc.

[0063] The I / O module 350 can include one or more components configured to communicate information with a user associated with the computing device 300. For example, the I / O module 350 can include one or more buttons, switches, or touchscreensAttorney Docket No.: 47565-0067WO1 to allow a user to input parameters associated with the computing device 300. The I / O module 350 can also include a display including a graphical user interface (GUI) and / or one or more light sources for outputting information to the user. The I / O module 350 can also include one or more communication channels for connecting the computing device 300 to one or more secondary or peripheral devices such as, for example, a desktop computer, a laptop, a tablet, a smart phone, a flash drive, or a printer, to allow a user to input data to or output data from the computing device 300.

[0064] The Interface 360 can include one or more components configured to transmit and receive data via a communication network, such as the Internet, a local area network, a workstation peer-to-peer network, a direct link network, a wireless network, or any other suitable communication channel. For example, the interface 360 can include one or more modulators, demodulators, multiplexers, demultiplexers, network communication devices, wireless devices, antennas, modems, and any other type of device configured to enable data communication via a communication network.

[0065] FIG. 4 is a flow chart diagram of an example process for monitoring and controlling heat transfer operations. In particular, the example process 300 [1] can monitor temperatures of heat transfer tubes (e.g., the heat transfer tubes 110) based on heat sensing tubes (e.g., the heat sensing tubes 112) and [2] control heat transfer operations including regulation of firing rate of heat exchanger (e.g., the heat exchanger 102). The process 300 can be implemented by a processor-based system for monitoring and controlling heat transfer operations, such as the heat exchanger system 100 and in conjunction with the example implementation described in this disclosure.

[0066] At 402, temperatures of the heat sensing tubes are measured.

[0067] For example, each of the heat sensing tubes can include one or more temperature sensors that can measure temperatures at different locations of a respective heat sensing tube. For example, multiple temperature sensors can be positioned at a different axial location along a length (or longitudinal axis) of each heat sensing tube to thereby measure temperatures at different locations of a respective heat sensing tube or one or more heat transfer tubes in vicinity of the respective heat sensing tube. For example, one or more temperature sensors can be disposed within a lumen of each heat sensing tube.

[0068] For example, each temperature sensor of each heat sensing tube can measure a temperature Ti,p for a respective ithheat sensing tube (of the heat sensing tubes) at a respective plane p of the heat exchanger (or a respective plane of each of the heat transferAttorney Docket No.: 47565-0067WO1 tubes or each of the heat sensing tubes), where each ithsensing tube can be disposed in proximity to one or more of j number of the heat transfer tubes. For example, each of i, j, and p can be, independently, an integer of 1 or more.

[0069] At 404, temperature of fluidized bed or heat transfer medium (e.g., the fluidized bed or heat transfer medium 122) is measured. For example, one or more temperature sensors can measure temperature Tbed,kof the fluidized bed or heat transfer medium at one or more locations external to the heat exchanger. For example, the fluidized bed or the heat transfer medium can be in contact with one or more of the heat sensing tubes and / or one or more of the heat transfer tubes, and the one or more temperature sensors that is in contact with or in the closest vicinity to the fluidized bed or heat transfer medium can measure the temperature of the fluidized bed or heat transfer medium. Further, for example, Tbed,k can represent the temperature of the fluidized bed or heat transfer medium for the kthmeasurement, where k is an integer of 1 or more. In some cases, Tbed,kcan represent the temperature of the fluidized bed or heat transfer medium at kthlocation, where k can be an integer of 1 or more.

[0070] In some implementations, temperature sensors such as thermocouples and / or fiber optic temperature sensors can be disposed at one or more locations or zones of interest around or at the heat exchanger or bed’s surface to measure the temperature of the fluidized bed or heat transfer medium. For instance, temperature sensors such as infrared thermometers or pyrometers that are configured to measure temperature by detecting the infrared radiation emitted by the surface of the fluidized bed can be disposed around or at the heat exchanger or bed’s surface to measure the temperature of the fluidized bed or heat transfer medium.

[0071] In some implementations, measurement of Ti,p and Tbed,k can be performed in any order.

[0072] In some implementations, measuring Ti,pand Tbed,kcan be performed at successive time periods. In some implementations, the successive time periods can range from 1 to 30 minutes. In some implementations, the successive time periods can range from 3 to 15 minutes.

[0073] At 406, differences between each of temperatures of sensing tubes and temperature of fluidized bed are determined to obtain multiple ΔT. After measuring Ti,p and Tbed,k (e.g., Tbed,k is the bed temperature local and close to Ti,p) at multiple different locations and the controller 130 receives measurements of data including Ti,pand Tbed,k, aAttorney Docket No.: 47565-0067WO1 controller (e.g., the controller 130) that is installed at or communicatively connected with the heat exchanger can determine differences between each Ti,p and Tbed,k to obtain each respective temperature difference ΔT.

[0074] Further, after determining each respective temperature difference ΔT for multiple locations, the controller can determine one or more average values ΔTavg of multiple ΔT values. In some implementations, the controller 130 can determine ΔTavgover the axis (e.g., axial length, longitudinal axis) of each of the heat sensing tube, respectively. For example, ΔTavg over longitudinal axis (ΔTavg, axial) can be determined for each heat sensing tube by averaging temperature measurements obtained by the temperature sensors that are disposed at or in vicinity of multiple temperature measurement locations over longitudinal axis of each heat sensing tube of the heat sensing tubes. For example, the controller can average a group of ΔTi,p values for the p number of planes of each ithsensing tube to yield an i number of axial average values (e.g., i number of ΔTavg, axialvalues).

[0075] In some implementations, the controller can determine ΔTavg over all (or two or more) of the heat sensing tubes at targeted one or more planes. For example, ΔTavg of targeted plane(s) (ΔTavg, pth plane) can be determined for each of the specific plane(s) by averaging temperature measurement obtained by the temperature sensors disposed at or in vicinity of multiple temperature measurement locations at each plane of the targeted one or more planes. For example, the controller can average a group of ΔTi,pvalues for the i number of sensing tubes at each pthplane to yield a p number of plane average values, (e.g., p number of ΔTavg, pth plane values).

[0076] In some implementations, the controller can determine the average of Ti,p first and thereafter determine the ΔTavgvalues between the average of Ti,pand the average of Tbed, k.

[0077] After determining ΔTavg values, the controller can determine an average value of ΔTavgvalues. In some implementations, the controller can determine an average of multiple ΔTavg, pth plane values at two or more targeted planes. In some implementations, the controller can determine an average of multiple ΔTavg, axial values of two or more of the heat sensing tubes. In some implementations, the controller can determine an average of all of the measured ΔTavg, pth planeand ΔTavg, axialvalues.

[0078] At 408, firing rate of combustion section (e.g., the combustion section 104) is regulated. For example, after determining the average value of ΔTavg values, such average value can be compared to a respective pre-determined threshold value. Based onAttorney Docket No.: 47565-0067WO1 the comparison, the controller can control heat transfer operations of the heat exchanger. For example, based on the average value of ΔTavg values being greater than or equal to respective threshold value, the controller can control the heat transfer operations of the heat exchanger. For example, controlling the heat transfer operations can include regulating a firing rate (e.g., powering rate of electric heat exchanger) of a combustion section of the heat exchanger.

[0079] In some implementations, based on the average value of ΔTavgvalues being greater than or equal to the respective threshold value, the controller can decrease the firing rate or stop operation of the heat exchanger.

[0080] In some implementations, based on the average value of ΔTavgvalues being less than the respective threshold value, the controller can increase or maintain the firing rate of the heat exchanger.

[0081] In some implementations, the controller or other computing device in data communication with the controller can incorporate a ML model (which may be a deep- learning model) trained to control the heat transfer operations based on one or more values of the average value of ΔTavgvalues. For example, the training data and output data can be logged in the controller or other computing device to train the ML model. The training data can include the ΔTavg values and the average value of ΔTavg values, and output data can include data representing controlling of heat exchanger operations.

[0082] FIG. 5 is a flow chart diagram of an example process for monitoring and controlling heat transfer operations. In particular, the example process 400 [1] can monitor temperatures of heat transfer tubes and [2] control heat transfer operations including regulation of firing rate of heat exchanger. The process 300 can be implemented by a processor-based system for monitoring and controlling heat transfer operations, such as the heat exchanger system 100, and in conjunction with the example implementations and the example process 400, as described in this disclosure.

[0083] At 502, temperatures of sensing tubes (e.g., the sensing tubes 112) are measured. As the technique used in step 502 can be the same as the technique used in step 402 of FIG. 4, the technique is not repeated here.

[0084] At 504, temperature of fluidized bed or heat transfer medium (e.g., the fluidized bed or heat transfer medium 122) is measured. As the technique used in step 504 can be the same as the technique used in step 404 of FIG. 4, the technique is not repeated here.Attorney Docket No.: 47565-0067WO1

[0085] At 506, differences between each of temperatures of sensing tubes and temperature of fluidized bed are determined to obtain multiple ΔT. As the technique used in step 506 can be the same as the technique used in step 406 of FIG. 4, the technique is not repeated here.

[0086] At 508, [1] ΔTavg, pth plane and / or [2] ΔTavg, axial are determined. For example, after determining each respective temperature difference ΔT for multiple locations, the controller can determine one or more average values ΔTavgof multiple ΔT values. These can be simple averages or rolling averages.

[0087] In some implementations, the controller can determine ΔTavgover the axis (e.g., axial length, longitudinal axis) of each of the heat sensing tube, respectively. For example, ΔTavg over longitudinal axis (ΔTavg, axial) can be determined for each heat sensing tube by averaging temperature measurements obtained by the temperature sensors disposed at or in vicinity of multiple temperature measurement locations over longitudinal axis of each heat sensing tube of the heat sensing tubes. For example, the controller can average a group of ΔTi,p values for the p number of planes of each ithsensing tube to yield an i number of axial average values (e.g., i number of ΔTavg, axialvalues).

[0088] In some implementations, the controller can determine ΔTavgover all (or two or more) of the heat sensing tubes at targeted one or more planes. For example, ΔTavg of targeted plane(s) (ΔTavg, pth plane) can be determined for each of the specific plane(s) by averaging temperature measurement obtained by the temperature sensors disposed at or in vicinity of multiple temperature measurement locations at each plane of the targeted one or more planes. For example, the controller can average a group of ΔTi,p values for the i number of sensing tubes at each pthplane to yield a p number of plane average values, (e.g., p number of ΔTavg, pth plane values).

[0089] In some implementations, the controller can determine the average of Ti,p first and thereafter determine the ΔTavgvalues between the average of Ti,pand the average of Tbed,k.

[0090] In some implementations, after determination of [1] ΔTavg, pth plane value and / or [2] ΔTavg, axialvalue, the example process 500 can directly proceed to step 512, where such ΔTavg, pth planevalue and / or ΔTavg, axialvalue can be compared with respective threshold value(s). For example, as described above with respect to the discussion of the heat exchanger system 100 of FIG.1, the controller can compare ΔTavg, pth plane value and / or ΔTavg,axialvalue to a respective pre-determined value. When the [1] ΔTavg, pth planevalue and / or [2]Attorney Docket No.: 47565-0067WO1 ΔTavg, axial value is / are greater than respective threshold value(s), the example process 500 can proceed to step 514. Otherwise, the example process 500 can go back to step 502.

[0091] At 510, after determining ΔTavgvalues, the controller 130 can determine (i) a bundle average value of ΔTavg values, (ii) a rolling average value of ΔTavg values, and / or (iii) bundle rolling average values of ΔTavg values.

[0092] For example, the bundle average value corresponds to an average value of (i) the p number of plane average values (ΔTavg, pth plane) and (ii) i number of axial average values (ΔTavg, axial).

[0093] For example, the rolling average value corresponds to an average value of one or more ΔTavgvalues over certain time periods. As described above, measuring Ti,pand Tbed,k can be performed at successive time periods, before determining ΔTavg values. In some implementations, the rolling average value corresponds to an average value of one or more ΔTavg, pth planevalues over certain time periods. In some implementations, the rolling average value corresponds to an average value of one or more ΔTavg, axial values over certain time periods.

[0094] For example, the bundle rolling average value corresponds to an average value of two or more of successive bundle average values over certain time periods.

[0095] In some implementations, the certain time periods can range from 1 to 30 minutes. In some implementations, the certain time periods can range from 3 to 15 minutes.

[0096] At 512, after determining i) the bundle average value, (ii) the rolling average value, and / or (iii) the bundle rolling average values, one or more of these values can be compared to respective threshold value(s). For example, the controller can compare one or more of i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavg values (including ΔTavg, pth plane and ΔTavg, axial values) to respective threshold value(s). As described above with respect to the discussion of the heat exchanger system 100 of FIG. 1, each of the threshold values can be established according to guidelines for each of the of i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavg values. In some implementations, the pre-determined threshold value can be about 5°F, 10°F, 15°F 20°F, 25°F, 30°F, 35°F, 40°F, 45°F, 50°F, or greater.

[0097] When i) the bundle average value, (ii) the rolling average value, and / or (iii) the bundle rolling average values is / are greater than respective threshold value(s), theAttorney Docket No.: 47565-0067WO1 example process 500 can proceed to step 514. Otherwise, the example process 500 can go back to step 502.

[0098] In some implementations, based on one or more values of the i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavg values (based on simple or rolling average) being less than the respective threshold value(s), the example process 500 does not directly go back to step 502 and the controller can increase or maintain the firing rate of the heat exchanger.

[0099] At 514, firing rate of combustion section of the heat exchanger can be regulated. For example, based on one or more of value of the i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavgvalues (based on simple or rolling average) being greater than or equal to respective threshold value(s), the controller can decrease the firing rate or stop operation of the heat exchanger.

[0100] In some implementations, the controller or other computing device (e.g., the user device, a third-party device, a server) in data communication with the controller can incorporate a ML model trained to control the heat transfer operations based on one or more values of the i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavgvalues based on simple or rolling average. For example, the training data and output data can be logged (e.g., stored or transmitted for storage) in the controller or other computing device to train the machine-learning model. The training data can include the i) the bundle average value, (ii) the rolling average value, (iii) the bundle rolling average value, and / or iv) ΔTavg values and output data can include data representing controlling of heat exchanger operations.

[0101] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular implementations. Certain features that are described in this specification in the context of separate implementations can also be implemented, in combination, in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations, separately, or in any sub-combination. Moreover, although previously described features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can, in some cases, be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.Attorney Docket No.: 47565-0067WO1

[0102] As used in this disclosure, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” has the same meaning as “A, B, or A and B.” In addition, it is to be understood that the phraseology or terminology employed in this disclosure, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.

[0103] As used in this disclosure, the term “about” or “approximately” can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range.

[0104] Values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “0.1% to about 5%” or “0.1% to 5%” should be interpreted to include about 0.1% to about 5%, as well as the individual values (for example, 1%, 2%, 3%, and 4%) and the sub- ranges (for example, 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “X, Y, or Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.

[0105] Particular implementations of the subject matter have been described. Other implementations, alterations, and permutations of the described implementations are within the scope of the following claims as will be apparent to those skilled in the art. While operations are depicted in the drawings or claims in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed (some operations may be considered optional), to achieve desirable results. In certain circumstances, multitasking or parallel processing (or a combination of multitasking and parallel processing) may be advantageous and performed as deemed appropriate.

[0106] Moreover, the separation or integration of various system modules and components in the previously described implementations should not be understood as requiring such separation or integration in all implementations, and it should be understoodAttorney Docket No.: 47565-0067WO1 that the described components and systems can generally be integrated together or packaged into multiple products.

[0107] Accordingly, the previously described example implementations do not define or constrain the present disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of the present disclosure.

Claims

Attorney Docket No.: 47565-0067WO1 CLAIMS 1. A heat exchanger comprising: a combustion section configured to receive and combust a fuel to produce a combustion stream; a plurality of heat transfer tubes configured to receive the combustion stream from the combustion section, wherein the plurality of heat transfer tubes is configured to transfer heat from the combustion stream to a heat transfer medium that is external to the plurality of heat transfer tubes, and wherein said transfer of heat yields a cooled combustion stream; a plurality of sensing tubes configured to yield one or more temperature measurements, wherein the plurality of sensing tubes is disposed in proximity to the plurality of heat transfer tubes; one or more temperature sensors configured to measure temperature of the fluidized bed or the heat transfer medium that is external to the heat transfer tubes and the heat sensing tubes; a decoupler section or exit manifold section configured to receive the cooled combustion stream; and a controller configured to regulate a firing rate of the combustion section.

2. The heat exchanger of claim 1, wherein at least one of the plurality of sensing tubes comprises one or more temperature sensors within a lumen of the at least one sensing tube.

3. The heat exchanger of claim 2, wherein the at least one sensing tube comprises a plurality of temperature sensors, and wherein each of the plurality of temperature sensors is positioned at a different axial location along a length of the at least one sensing tube.

4. The heat exchanger of claim 3, wherein each of the plurality of temperature sensors is configured to yield an axial temperature measurement of the at least one sensing tube.Attorney Docket No.: 47565-0067WO1 5. The heat exchanger of any one of claims 1-4, wherein the controller is configured to increase or decrease the firing rate based on the one or more temperature measurements.

6. A method of determining temperature within a reactor, the method comprising: measuring a temperature Ti,pfor each ithsensing tube of at least one heat exchanger at each plane p of the heat exchanger, wherein each ithsensing tube of the heat exchanger is disposed in proximity to a j number of heat transfer tubes of the heat exchanger; measuring at least one temperature Tbed,kof a heat transfer medium that is external to the heat exchanger, wherein the heat transfer medium is disposed within the reactor and is in contact with the i number of sensing tubes and j number of heat transfer tubes, and wherein measuring Ti,pand Tbed,kcan be performed in any order; and determining a difference between each Ti,p and Tbed,k to obtain a delta temperature ΔTi,p, wherein each of i, j, p, and k is, independently, an integer of 1 or more.

7. The method of claim 6, further comprising: averaging a group of ΔTi,pvalues for the i number of sensing tubes at each pthplane to yield a p number of plane average values (e.g., an average for each group of ΔTi,pvalues in which each p for each ΔTi,p value in the group is the same, and in which a p number of such averages are obtained for each value of p); averaging a group of ΔTi,pvalues for the p number of planes of each ithsensing tube to yield an i number of axial average values (e.g., an average for each group of ΔTi,p values in which each i for each ΔTi,p value in the group is the same, and in which an i number of such averages are obtained for each value of i), wherein averaging the group of ΔTi,p values for the i number of sensing tubes and the p number of planes can be performed in any order; and averaging the p number of plane average values and i number of axial average values to yield a bundle average value.

8. The method of claim 6 or 7, wherein said measuring Ti,p and said measuring Tbed,k are performed at successive time periods starting from time 0.Attorney Docket No.: 47565-0067WO1 9. The method of claim 8, wherein the successive time periods may range from 1 to 30 minutes and in particular between 3 and 15 minutes.

10. The method of claim 9, wherein two or more of (2, 3, 4 etc.) successive plane average values are averaged sequentially to yield rolling plane average values.

11. The method of claim 9, wherein two or more of (2, 3, 4 etc.) successive axial average values are averaged sequentially to yield rolling axial average values.

12. The method of claim 9, wherein two or more of (2, 3, 4 etc.) successive bundle average values are averaged sequentially to yield rolling bundle average values.

13. The method of any one of claims 6-12, wherein firing rate of the heat exchanger is increased or decreased based on the ΔTi,p, Tbed,k and the plane, the axial , and / or the bundle rolling average values.

14. The method of claim 13, wherein the firing rate is decreased based on the ΔTi,p, Tbed,k, the plane rolling average value, the axial rolling average value, and / or the bundle rolling average value that is greater than their predetermined values respectively.

15. The method of claim 14, wherein the predetermined value is about 5°F, 10°F, 15°F 20°F, 25°F, 30°F, 35°F, 40°F, 45°F, 50°F, or greater.

16. The method of any one of claims 6-15, wherein the reactor comprises an n number of heat exchangers, and wherein n is an integer of 1 or more.

17. The method of claim 16, wherein said measuring the Ti,p comprises measuring Ti,p for each nthheat exchanger, and wherein said measuring Tbed,kcomprises measuring Tbed,kin proximity to each nthheat exchanger.

18. The method of claim 17, further comprising:Attorney Docket No.: 47565-0067WO1 averaging a group of ΔTi,p values for the i number of sensing tubes at each pthplane for each nthheat exchanger to yield a p number of plane average values for each nthheat exchanger (e.g., an average for each group of ΔTi,pvalues in which each p for each ΔTi,p value in the group is the same, and in which a p number of such averages are obtained for each value of p); averaging a group of ΔTi,pvalues for the p number of planes of each ithsensing tube for each nthheat exchanger to yield an i number of axial average values for each nthheat exchanger (e.g., an average for each group of ΔTi,p values in which each i for each ΔTi,pvalue in the group is the same, and in which an i number of such averages are obtained for each value of i), wherein averaging the group of ΔTi,pvalues for the i number of sensing tubes and the p number of planes can be performed in any order; and averaging the p number of plane average values and i number of axial average values to yield a bundle average value for each nthheat exchanger.

19. The method of any one of claims 6-18, wherein the heat exchanger is the heat exchanger of any one of claims 1-5.

20. A heat exchanger comprising: a flue gas plenum receiving a combustion stream from a combustor; a plurality of heat transfer tubes configured as tube within tube such that the combustion stream travels away from the flue gas plenum in the inner tube and returns in the outer tube, wherein the plurality of outer tubes is configured to transfer heat from the combustion stream to a heat transfer medium that is external to the plurality of heat transfer tubes, and wherein said transfer of heat yields a cooled combustion stream; a plurality of sensing tubes configured to yield one or more temperature measurements, wherein the plurality of sensing tubes is disposed in proximity to the plurality of heat transfer tubes; one or more temperature sensors configured to measure temperature of the fluidized bed or the heat transfer medium that is external to the heat transfer tubes and the heat sensing tubes; an exit manifold section configured to receive the cooled combustion stream; and a controller configured to regulate a firing rate of the combustor.Attorney Docket No.: 47565-0067WO1 21. The heat exchanger of claim 20, wherein at least one of the plurality of sensing tubes comprises one or more temperature sensors within a lumen of the at least one sensing tube.

22. The heat exchanger of claim 21, wherein the at least one sensing tube comprises a plurality of temperature sensors, and wherein each of the plurality of temperature sensors is positioned at a different axial location along a length of the at least one sensing tube.

23. The heat exchanger of claim 22, wherein each of the plurality of temperature sensors is configured to yield an axial temperature measurement of the at least one sensing tube.

24. The heat exchanger of any one of claims 18-23, wherein the controller is configured to increase or decrease the firing rate based on the one or more temperature measurements.

25. A heat exchanger comprising: a plurality of heat transfer tubes or thermowells configured to enclose electrical heater rods or heating elements, wherein the plurality of heat transfer tubes is configured to transfer heat from the heater rods or elements to a heat transfer medium that is external to the plurality of heat transfer tubes; a plurality of sensing tubes configured to yield one or more temperature measurements, wherein the plurality of sensing tubes is disposed in proximity to the plurality of heat transfer tubes; one or more temperature sensors configured to measure temperature of the fluidized bed or heat transfer medium that is external to the heat transfer tubes and the heat sensing tubes; and one or more controllers configured to regulate power input to groups of heater rods or heating elements.Attorney Docket No.: 47565-0067WO1 26. The heat exchanger of claim 25, wherein at least one of the plurality of sensing tubes comprises one or more temperature sensors within a lumen of the at least one sensing tube.

27. The heat exchanger of claim 26, wherein the at least one sensing tube comprises a plurality of temperature sensors, and wherein each of the plurality of temperature sensors is positioned at a different axial location along a length of the at least one sensing tube.

28. The heat exchanger of claim 27, wherein each of the plurality of temperature sensors is configured to yield an axial temperature measurement of the at least one sensing tube.

29. The heat exchanger of any one of claims 25-28, wherein the one or more controllers are configured to increase or decrease the firing rate based on the one or more temperature measurements.

30. The heat exchanger of any one of claims 25-28, wherein the one or more controllers incorporate a machine-learning (ML) model that is trained based on at least one of (i) the one or more temperature measurements and the temperature of the fluidized bed or heat transfer medium or (ii) temperature values that are determined based on the one or more measurements and the temperature of the fluidized bed or heat transfer medium, and wherein the one or more controllers are configured to, based on the ML model, increase or decrease the firing rate.

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