Method for determining local temperature anomalies in the fluidized bed of a combustion boiler, method for assessing the risk of bed sintering in a fluidized bed combustion boiler, and combustion boiler system

Abstract

To improve bed control in fluidized bed combustion boiler systems. A method for determining local temperature anomalies in a fluidized bed of a combustion boiler, a method for calibrating a numerical model of a fluidized bed of a combustion boiler, a method for assessing the risk of bed sintering in a fluidized bed combustion boiler, a method for controlling a fluidized bed boiler, and a combustion boiler. A specific method for monitoring the condition of a fluidized bed is proposed to improve the control of a fluidized bed boiler system (10). In the method for controlling a fluidized bed boiler system (10), for example, a local bed temperature anomaly and / or a bed sintering index are monitored, and upon detection of a local bed temperature anomaly and / or a bed sintering index exceeding a predetermined standard, the operation of the combustion boiler system (10) is automatically adjusted and / or a boiler operator is informed that a local bed temperature anomaly and / or a bed sintering condition has been detected.

Description

[Technical Field]

[0001] The present invention relates to the control of a fluidized bed combustion boiler, such as a circulating fluidized bed (CFB) boiler or a bubbling fluidized bed (BFB) boiler. [Background technology]

[0002] Combustion boilers, such as grate boilers and fluidized bed boilers, are typically utilized to generate steam that can be used for a variety of purposes, such as power generation and heating.

[0003] In a fluidized bed boiler, fuel and solid particulate bed material are introduced into a furnace, and fluidizing gas is introduced from the bottom of the furnace to fluidize the bed material and fuel. Combustion of the fuel occurs within the furnace. In BFB combustion, the fluidizing gas passes through the bed so that it forms bubbles in the bed. In a BFB, the fluidized bed can be controlled rather conveniently by controlling the fluidizing gas supply and the fuel supply.

[0004] In CFB combustion, the fluidizing gas is passed through the bed material. Most of the bed particles are entrained in the fluidizing gas and carried along with it. The particles are separated from the fluidizing gas and recycled back into the furnace.

[0005] In all boilers, regardless of combustion technology, combustion conditions such as oxygen and fuel mixture may not be ideal. Summary of the Invention [Problem to be solved by the invention]

[0006] It is a first object of the present invention to improve bed control in a fluidized bed combustion boiler system. This object can be achieved by the method according to independent claim 1.

[0007] It is a second object of the present invention to improve the accuracy of bed control in a fluidized bed combustion boiler system. This object can be achieved by a method according to the parallel independent claim 6.

[0008] It is a third object of the present invention to improve bed control in a fluidized bed combustion boiler system. This object can be achieved by a method according to the parallel independent claim 9.

[0009] It is a fourth object of the present invention to improve bed control in a fluidized bed combustion boiler system. This object can be achieved by a method according to the parallel independent claim 12.

[0010] The dependent claims describe advantageous embodiments of the method. [Means for solving the problem]

[0011] With regard to the first object of the present invention, a method for determining local temperature anomalies in a fluidized bed of a combustion boiler system comprising a furnace having a boiler grid with at least three temperature sensors, which together define a measurement grid and each represent a measurement point, comprises: - measuring the floor temperature at a measuring point; - calculating bed temperatures for the measurement points using at least one numerical bed temperature model to obtain calculated bed temperatures under normal operating conditions of the combustion boiler system; - comparing the measured floor temperature to the calculated floor temperature for at least some of the measurement points and determining that a local temperature anomaly exists if the measured floor temperature exceeds an anomaly threshold; Includes.

[0012] In this method, the at least three temperature sensors used to monitor the bed temperature, together with the numerical bed temperature model, provide a high degree of accuracy in fluidized bed temperature measurements to the extent that localized bed temperature anomalies can be detected.

[0013] Without being bound by theory, localized anomalies may be found to be related to the onset of sintering in a fluidized bed, particularly when bed temperature is measured at the boiler grate. The inventors have observed that localized temperature anomalies serve as a precursor to the onset of sintering in a fluidized bed. Therefore, by monitoring measured bed temperature along with calculated bed temperature, the onset of sintering in a bed can be detected, and measures can be taken in advance to repair the bed, or at least to prevent sintering from worsening. This can help avoid shutdowns of a combustion boiler system due to sintering in the bed and costly repairs. It is advantageous that bed temperature anomalies provide information about bed quality, preferably whether sintering is occurring in the bed. Or, in other words, it is possible to receive information about bed-related problems that could lead to shutdowns if corrective action is not taken. Thus, boiler availability can be improved and / or operating costs can be reduced. The method is preferably performed automatically, either by a local boiler control system or a remote, preferably a process intelligence system.

[0014] The calculated bed temperature for the measurement point can be obtained in the following way. - Numerical models between boiler operating data, i.e., at least primary air flow, fuel moisture, main steam flow, flue gas oxygen, and bed pressure, and measured bed temperatures at each measurement point, are prepared and calibrated; - current operating data of the boiler is monitored, including measured bed temperature at each measurement point and at least primary air flow, fuel moisture, main steam flow, flue gas oxygen, and bed pressure; - for at least one measurement point, a numerical model is used to calculate a calculated temperature using current operating data and measured bed temperatures of at least two other measurement points; - The calculated temperature and the measured floor temperature are compared against anomaly criteria, and if the anomaly criteria are met, it is determined that a local temperature anomaly exists.

[0015] Calibration may be performed in a delayed manner, preferably using historical data from at least M days ago, where M is at least 3, preferably M is at least 7, and more preferably M is at least 14. In this way, there can be greater assurance that emerging bed quality problems will not adversely affect the calibration.

[0016] According to one embodiment of the present invention, the calculated bed temperature model is: y=b0+b1×x1+b2×x2+b3×x3+b4×x4+b5×x5+b6×x6 can be obtained from where: b0···b6 are the model coefficients obtained from the linear regression model x1 = total air flow, primary air flow (x 1Prim ) and secondary air flow rate (x 1sec ) x2=fuel moisture x3 = Floor temperature measurement (x) adjacent to the output floor temperature measurement (y) 3a , x 3b ) average x4=flue gas oxygen content x5 = average bed pressure x6 = average recirculation gas flow rate

[0017] According to one embodiment, fuel moisture may be calculated or measured.

[0018] According to one embodiment of the present invention, the calculated bed temperature model is: y=b0+b1×x1+b2×x2+b3×x3+b4×x4+b5×x5+b6×x6 can be obtained from where: b0···b6 are the model coefficients obtained from the linear regression model. x1 = total air flow, primary air flow (x 1Prim ) and secondary air flow rate (x 1sec ) x2 = H2O content of flue gas x3 = Floor temperature measurement (x) adjacent to the output floor temperature measurement (y) 3a , x 3b ) average x4=flue gas oxygen content x5 = average bed pressure x6 = average recirculation gas flow rate

[0019] According to one embodiment of the present invention, the calculated bed temperature may be obtained using artificial intelligence tools. According to one embodiment of the present invention, the calculated bed temperature may be obtained using neural networks.

[0020] Upon detecting a local temperature anomaly, calibration is preferably not performed (i.e., calibration is skipped) for a predetermined time. In addition to or instead of a boiler shutdown situation, abnormal operation and / or abnormal bed conditions are preferably removed or omitted from the calibration data. This approach can help avoid bed quality issues that may adversely affect calibration. This approach can be fine-tuned so that upon detecting a local temperature anomaly that meets a given threshold, calibration is not performed for a predetermined time. In that case, only conditions severe enough to generate a sufficiently large anomaly signal can be selected to skip calibration for a predetermined time.

[0021] Regarding the second object of the present invention, there is provided a method for calibrating a numerical model of a fluidized bed of a combustion boiler system comprising a furnace having a boiler grid with at least three temperature sensors which together define a measurement grid and each represent a measurement point, the combustion boiler system being configured to generate measured bed temperatures at each of the measurement points, preferably as used in the context of the method for the first object of the present invention, comprising: - current operating data of the boiler including measured bed temperature at each measurement point and at least primary air flow rate, fuel moisture content, main steam flow rate, flue gas oxygen, and bed pressure are monitored and collected to provide historical data; - A numerical model between the boiler operating data, i.e. at least the primary air flow rate, fuel moisture, main steam flow rate, flue gas oxygen, and bed pressure, and the measured bed temperature at each measurement point is fitted using at least one numerical fitting method, preferably a numerical regression method, advantageously least squares fitting.

[0022] In this way, a calibrated numerical model can be generated that produces results of suitable accuracy under different operating conditions of the combustion boiler system.

[0023] Calibration may be repeated at predetermined intervals, such as periodically, to help keep the calibration realistic, reflecting possible wear and tear on the combustion boiler system, as well as changes in fuel quality, environmental conditions (changes in temperature, ambient humidity, ambient pressure) that may lead to changing operating parameters over time.

[0024] If a local temperature anomaly is detected, the calibration can be aborted, thus providing greater assurance that an ongoing floor quality problem will not adversely affect the calibration.

[0025] With regard to the third object of the present invention, a method for assessing the risk of sintering of a boiler bed of a fluidized bed combustion boiler system comprising a furnace having a boiler grid with at least three temperature sensors, which together define a measurement grid and each of which is representative of a measurement point, comprises: - the current operating data of the boiler, i.e. the measured bed temperature, are measured at each measuring point; - Based on the current operating data of the boiler, i) the average of the measured bed temperatures is calculated; ii) the standard deviation of the measured bed temperatures is calculated; iii) the difference between the maximum measured bed temperature and the minimum measured bed temperature is calculated; iv) For the measured bed temperature, the spreading rate is calculated; - using the results of calculations i), ii), iii) and iv), a bed sintering index is prepared; Includes.

[0026] One possibility for a definition of the sintering index that is preferably used may be the following: i) the average of the measured bed temperatures is calculated; ii) the standard deviation of the measured bed temperatures is calculated; iii) the difference between the maximum measured bed temperature and the minimum measured bed temperature is calculated; iv) Spraying rate for measured bed temperature

[0027]

number

[0028] Similarly, v) Calculated bed temperature T for the same measurement point Ci , I=1,...,n is calculated, and the measured bed temperature T Mi , i=1,···,n and the calculated floor temperature are calculated. It is compared with a corresponding predetermined limit value to obtain an index of risk of sintering for the bed temperature residual.

[0029] The final risk index may then be, for example, the maximum of the above risk indices.

[0030] The inventors have thus observed that the resulting bed sintering index is indicative of fluidized bed conditions that could lead to boiler shutdown if not treated early enough to take corrective action so that the need to shut down the boiler can be avoided, as will be discussed in more detail with reference to FIG.

[0031] The method further comprises: v) A calculated bed temperature for the same measurement point is calculated and the residual between the measured bed temperature and the calculated bed temperature is calculated, and the result of step v) is also used to prepare a bed sintering index.

[0032] In this way, the accuracy of the prediction of the bed sintering index can be further improved.

[0033] In the method according to the third object of the invention, the calculated bed temperature can be obtained using the method according to the first object of the invention.

[0034] Regarding the fourth object of the present invention, there is provided a method for controlling a fluidized bed boiler system, comprising: Local bed temperature anomalies and / or bed sintering index are monitored; Upon detecting a local bed temperature anomaly and / or bed sintering index exceeding a predetermined standard, the system automatically adjusts the operation of the combustion boiler system and / or indicates to the boiler operator that a local bed temperature anomaly and / or bed sintering condition has been detected.

[0035] In this manner, the combustion boiler system may be automatically controlled to prevent bed sintering, or alternatively, operators may be notified of local bed temperature anomalies and / or bed sintering conditions and may take action to prevent bed sintering.

[0036] The automatic adjustment of boiler operation may include at least one of: a) increasing or decreasing combustion air supply; b) increasing or decreasing fuel supply; c) increasing or decreasing bed material supply and / or bed material removal; d) adjusting recirculation gas flow rate; and e) temporarily limiting boiler load.

[0037] The combustion air preferably comprises primary air and secondary air. The recycle gas stream preferably comprises or consists of a recycle portion of the flue gas.

[0038] According to one embodiment of the present invention, the automatic adjustment or so-called corrective action is - Change the fuel mixture - Induces an air pulse through the primary air nozzles in the boiler grate - introducing a feed additive such as clay, which may be a hydrous clay (e.g., kaolin), or increasing the amount of such a feed additive; It includes at least one of the following:

[0039] The measured bed temperature may begin to drop during the early stages of sintering, and therefore, an abnormal bed condition may be determined during bed monitoring when it is determined that the bed temperature has dropped below the modeled bed temperature and exceeded the abnormal threshold.

[0040] Local bed temperature anomalies can be monitored using the method according to the first object of the present invention.

[0041] The bed sintering index can be monitored using a method according to the third object of the present invention.

[0042] In the method, local bed temperature anomalies and / or monitored sintering indices are preferably monitored using a numerical model. A delayed calibration of the numerical model can be used to reduce or avoid the influence of recent bed conditions on the calibration data.

[0043] Advantageously, the delay calibration is performed using a method according to the second object of the invention.

[0044] The combustion boiler system is adapted to carry out the method according to any one of the objects of the present invention.

[0045] The method and the combustion boiler will now be described in more detail with reference to exemplary embodiments shown in the accompanying drawings of Figures 1 to 8B. [Brief explanation of the drawings]

[0046] [Figure 1] FIG. 1 is a diagram of a CFB boiler system. [Figure 2] FIG. 1 is a diagram of a BFB boiler system. [Figure 3] 1 is a diagram of a boiler grate and its measurement arrangement. [Figure 4] FIG. 1 is a diagram of a method for calculating the risk of sintering. [Figure 5] FIG. 10 is a diagram illustrating a method for calculating residuals. [Figure 6] FIG. 1 is a diagram of a method for delay calibration. [Figure 7] FIG. 10 shows the results obtained using the residual calculation method. [Figure 8A] FIG. 8 is a diagram showing the results of the risk calculation method used on actual operating data of a combustion boiler system for the situation in FIG. 7. [Figure 8B] FIG. 8 is a diagram showing the results of the risk calculation method used on actual operating data of a combustion boiler system for the situation in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0047] In all figures, the same reference numerals refer to the same technical features.

[0048] 1 shows a combustion boiler system 10 that is a CFB boiler and includes a furnace 12 having tube walls 13 (typically including a front wall 132, a rear wall 134, and side walls 131, 133) connected to a water-steam circuit of the combustion boiler system 10. Water may be supplied from a water tank to an economizer, from the economizer via a steam drum to an evaporative heat transfer surface such as the tube walls 13, then via the steam drum to a superheater and then to a turbine. The flue gas flow path may include an economizer and / or a superheater and / or a reheater.

[0049] Fluidizing gas (such as air and / or oxygen-containing gas) is typically supplied from fluidizing gas supply 153 below grate 250 via primary fluidizing gas supply 151 so that primary fluidizing air enters the furnace through nozzles in grate 250 (to fluidize the fuel and bed material), and via secondary fluidizing gas supply 152 (to supply oxygen-containing gas, such as air, to control combustion). As a result, the bed material is fluidized, and the oxygen-containing gas necessary for combustion is supplied into furnace 12. Furthermore, fuel is supplied into furnace 12 via fuel supply 22.

[0050] Combustion can be adjusted by controlling the fuel supply 22 (e.g., by decreasing or increasing the fuel supply 22) and by controlling the fluidization gas supply (e.g., by decreasing or increasing the supply of oxygen or oxygen-containing gas, preferably combustion air, into the furnace 12). The fuel can be supplied with additives, particularly additives that function as alkaline sorbents, such as CaCO and / or clay. Additionally or alternatively, NOx reducing agents, such as ammonium or urea, can be supplied into or above the combustion zone of the furnace 12.

[0051] The fluidizing medium introduced into the furnace may include sand, limestone, and / or clay, and may particularly include kaolin. One effect of the bed, and combustion in general, is that in the water-steam circuit, water and steam are heated at the tube walls 13, converting the water to steam.

[0052] The bottom ash falls to the bottom of the furnace 12 and can be removed by an ash chute (omitted from Figure 1 for clarity), but a portion of the ash, the so-called fly ash, is carried along with the flue gases.

[0053] Combustion products such as flue gases, unburned fuel, and fluidized bed material pass from the furnace 12 to a particle separator 14, which may include a vortex finder 103. The particle separator 14 separates the flue gases from the solids. Particularly in larger combustion boilers 10, there may be two or more (two, three, ...) separators 14, preferably arranged in parallel with each other.

[0054] The solids separated by separator 14 pass through a loop seal 120, preferably located at the bottom of separator 14. The solids then pass to a fluidized bed heat exchanger (FBHE) 100, which also has a heat transfer surface (e.g., including, but not limited to, tubes and / or heat transfer panels), such that FBHE 100 collects heat from the solids to further heat the steam in the water-steam circuit.

[0055] The FBHE 100 may be fluidized, equipped with heat transfer tubes or other types of heat transfer surfaces, and arranged as a reheater or superheater. From the FBHE outlet 105, steam is sent to the high-pressure turbine (if the FBHE 100 is a superheater) or the intermediate-pressure turbine (if the FBHE 100 is a reheater). The FBHE inlet 104 preferably comes from an economizer (if the FBHE 100 is a superheater) or the high-pressure turbine (if the FBHE 100 is a reheater).

[0056] The solids can exit the FBHE 100 and enter the furnace 12 via the return flow path 102. In large combustion boilers 10 in particular, there may be two or more (two, three, ...) loop seals 120 and FBHEs 100, and return flow paths 102, preferably arranged in parallel with one another, such that for each separator 14 there is a respective loop seal 120, FBHE 100, and return flow path 102. In practice, some of the FBHEs 100 are arranged as superheaters and some are arranged as reheaters.

[0057] The flue gases are passed from the separator 14 to a crossover duct 15 from which they are passed to a rear flue 16 (preferably a vertical flue) from which they are passed via a flue gas duct 18 to a chimney 19 .

[0058] The rear flue 16 is connected to several heat transfer surfaces 21 i (where i=1, 2, 3, . . . , k, where k is the number of heat transfer surfaces). In FIG. 1, of these heat transfer surfaces, heat transfer surfaces 211, 212, 213, 214, . . . , 215, 216, 217, 218, 219, 220, 2210, 2221, 2222, 223 k The heat transfer surface 21 k indicates an air preheater. Other heat transfer surfaces 211-21 k-1 may include an economizer, a superheater, and a reheater. The actual number of different heat transfer surfaces in each of these components may be selected differently for each combustion boiler, depending, for example, on the actual needs. There may also be further components with heat transfer surfaces 21.

[0059] The combustion boiler system 10 includes multiple sensors and a computer unit. In fact, one medium-sized (100-150 MWth) combustion boiler system 10 may generate 100 million measurements per day, requiring 25 GB of storage space. Figures 1 and 2 show some of the sensors and computer unit. Examples of sensors include a temperature sensor measuring the output steam temperature at the outlet 105 of the FBHE 100, a pressure sensor measuring the pressure in the FBHE 100 chamber, a temperature sensor measuring the flue gas outlet temperature at the separator 14, a temperature sensor measuring the temperature in the loop seal 120, and a pressure sensor measuring the pressure in the loop seal.

[0060] Process data can be collected from the sensors by a distributed control system (DCS) 301. Data collection is most conveniently done via, for example, a fieldbus 378. The DCS 301 can have a display / monitor 302 for displaying operational status information to operators. An EDGE server 303 can process the measurement data obtained from the sensors, such as filtering and smoothing. There may also be local storage 304 for storing the data.

[0061] The DCS 301, display / monitor 302, EDGE server 303, and local storage 304 may reside within a combustion boiler network 370 (with local storage 304 preferably connected directly to the EDGE server 303). The combustion boiler network 370 is preferably separate from a fieldbus 380 used to communicate measurements from sensors to the DCS 301 and / or EDGE server 303. There may be an open platform communication server between the DCS 301 and the EDGE server 303 to improve system interoperability.

[0062] The combustion boiler network 370 may be connected to the Internet 300, preferably via a gateway 308. In this situation, measurement results may be transferred from the combustion boiler network 370 to a cloud service, such as a process intelligence system 305 located in a computational cloud 306. The applicant currently operates a cloud service that runs the analytics platform. The cloud service may operate in a virtualized server environment, such as Microsoft® Azure®, a virtualized, easily scalable environment for distributed computing and cloud storage for data. Other cloud computing services may also be suitable for running the analytics platform. Furthermore, instead of or in addition to a cloud computing service, a local or remote server may be used to run the analytics platform.

[0063] Figure 2 shows a fired boiler system 10 that is a BFB boiler. A BFB boiler differs from a CFB boiler in that the fluidized bed is a bubbling bed rather than a circulating bed. Therefore, the separator 14, loop seal 120, FBHE 100, and return flow path 102 are not required.

[0064] At least one superheater 14 is typically located within the furnace 12, preferably at the top of the furnace 12. The inlet 143 of the superheater 14 preferably comes from a steam drum 200 or another superheater, and the outlet 144 leads to a high pressure turbine.

[0065] Preferably, they are positioned above the boiler grate 250 and together define a measurement grid, each having a measurement point P i , i=1, . . . , n i 1. A method for determining local temperature anomalies in a fluidized bed of a combustion boiler system 10 including a furnace 12 having a boiler grate 250 comprising: - Floor temperature T Mi , i=1,...,N is the measurement point P i , i=1,···,N, - Measuring point P i , i=1, . . . , n are calculated using at least one numerical bed temperature model to obtain a calculated bed temperature T Ci , i=1,...,n, - Measuring point P i , i=1,...,n, for at least some of the measured bed temperatures T Mi is the calculated bed temperature T Ci and if it exceeds the abnormal threshold (for example, ΔT = T Mi -T Ci is calculated for all i and ΔT > ΔT limit ), it is determined that a local temperature anomaly exists.

[0066] Measurement point P i , i=1,...,N, the calculated floor temperature T Ci , i=1,...,N are preferably obtained in the following way. - Boiler operating data, i.e. at least 1x primary air flow, 2x fuel moisture, 3x main steam flow, 4x flue gas oxygen, and 5x bed pressures, and i , i=1,...,N) Mi , i=1,···,N, a numerical model f is prepared and calibrated, i.e., f(x1, x2, c3, x4, x5)=T Mi , - Each measurement point P i , i=1,...,N, the measured bed temperature T Mi , i=1,···,N and the current operating data of the boiler including at least primary air flow rate x1, fuel moisture x2, main steam flow rate x3, flue gas oxygen x4, and bed pressure x5 are monitored; - at least one measuring point P j , j = 1,...,n, the numerical model calculates the temperature T using the current operating data and the measured bed temperatures at at least two other measurement points. Cj is used to calculate - Calculated bed temperature T Ci and measured floor temperature T Miis compared against an anomaly criterion, and if the anomaly criterion is met, it is determined that a local temperature anomaly exists.

[0067] Calibration may be performed in a delayed manner, preferably using historical data from at least M days ago, where M is at least 3, preferably M is at least 7, and more preferably M is at least 14.

[0068] Upon detecting a local temperature anomaly, calibration may not be performed for a predetermined time period. In particular, upon detecting a local temperature anomaly that meets a given threshold, calibration may not be performed for a predetermined time period.

[0069] Both define a measurement grid, and each has a measurement point P i , i=1, . . . , N i 1. A method for calibrating a numerical model of a fluidized bed of a combustion boiler system 10 comprising a furnace 12 having a boiler grate 250 comprising: i , i=1,...,N, the measured bed temperature T Mi A method configured to generate - Each measurement point P i , i=1,...,n, the measured bed temperature T Mi , i=1,···,N and the current operating data of the boiler including at least primary air flow rate x1, fuel moisture x2, main steam flow rate x3, flue gas oxygen x4, and bed pressure x5 are monitored and collected to become historical data; - Boiler operating data, i.e. at least 1x primary air flow, 2x fuel moisture, 3x main steam flow, 4x flue gas oxygen, and 5x bed pressure, and i , i=1,...,n, the measured bed temperature T Mi , i=1,...,N, the numerical model f is fitted using at least one numerical fitting method, preferably a numerical regression method, advantageously least squares fitting.

[0070] 3 shows an example in which the boiler grate 250 is equipped with eight temperature sensors 20 (hence N=5). In principle, any number of temperature sensors 20 (but at least three) can be used.

[0071] The calibration is preferably repeated at predetermined intervals, such as periodically.

[0072] If a local temperature anomaly is detected, the calibration can be aborted.

[0073] 1. A method for assessing the risk of bed sintering in a fluidized bed combustion boiler system (10) comprising a furnace (12) having a boiler grid (250) with at least three temperature sensors (20i) that together define a measurement grid and each represent a measurement point Pi, i=1, . . . , n, comprising: - the current operating data of the boiler, i.e. the measured bed temperatures TMi, i = 1,...,N, are measured at each measuring point Pi, i = 1,...,n, - Based on the current operating data of the boiler, i) the average of the measured bed temperatures is calculated; ii) the standard deviation of the measured bed temperatures is calculated; iii) the difference between the maximum measured bed temperature and the minimum measured bed temperature is calculated; iv) Spraying rate for measured bed temperature

[0074]

number

[0075] According to one embodiment of the present invention, in the calculation of the dispersion degree i=1:N, N is the total number of bed temperature measurements, x i are the individual floor temperature measurements,

[0076]

number

[0077] Preferably, the method also includes: v) Calculated bed temperature T for the same measurement point Ci , I=1,...,n is calculated, and the measured bed temperature T Mi , i=1,...,n and the calculated bed temperature are calculated. The result of step v) is also advantageously used to prepare a bed sintering index.

[0078] In a method for controlling a fluidized bed boiler system 10, local bed temperature abnormalities and / or bed sintering indices are monitored, and upon detecting a local bed temperature abnormality and / or bed sintering index that exceeds a predetermined standard, operation of the combustion boiler system 10 is automatically adjusted and / or a boiler operator is informed that a local bed temperature abnormality and / or bed sintering condition has been detected.

[0079] The automatic adjustment of boiler operation may include at least one of: a) increasing or decreasing the primary air supply 151 and / or secondary air supply 152; b) increasing or decreasing the fuel supply 20; c) increasing or decreasing the bed material supply and / or bed material removal; and / or d) adjusting (preferably increasing) the recirculation gas flow rate; and / or e) temporarily limiting the boiler load.

[0080] Automatic adjustments or so-called corrective measures are - Change the fuel mixture - Causes an air pulse through the primary air nozzle - introducing a feed additive such as clay, which may be a hydrous clay (e.g., kaolin), or increasing the amount of the feed additive; It may include one of:

[0081] Local bed temperature anomalies and / or monitored sintering indices are preferably monitored using a numerical model. Preferably, delayed calibration of the numerical model is used to reduce or avoid the influence of recent bed conditions on the calibration data.

[0082] The combustion boiler system 10 is configured to carry out the method according to any one of the preceding claims.

[0083] FIG. 4 illustrates a possible use of the present method in a fluidized bed combustion system 10, and more particularly in a DCS 301 and / or EDGE server 303, or in a process intelligence system 305.

[0084] As a data input (step J1), fuel moisture is provided to the method, which can be measured from the fuel, obtained from flue gas analysis, or entered manually.

[0085] In step J3, the bed temperature is modeled.

[0086] In step J5, floor diagnosis is performed. As a result, the residual ΔT = T C -T M is obtained.

[0087] Figure 5 shows the possible inputs to the bed diagnostic step J5. Possible inputs provided are primary air flow, secondary air flow, flue gas oxygen, flue gas H2O, and bed pressure. These can be measured during operation of the combustion boiler, preferably by the DCS 301 or the EDGE server 303.

[0088] Corrective action can be taken automatically (preferably by DCS 301, EDGE Server 303, or Process Intelligence System 305), or the action can be taken manually by boiler operators.

[0089] FIG. 6 illustrates the principle of delay calibration.

[0090] The inventors analyzed actual boiler operation data collected during operation of the combustion boiler system 10 until the system was shut down due to bed sintering. The inventors were able to show that their method can be used to detect localized bed temperature anomalies and that localized bed temperature anomalies tend to act as precursors to bed sintering (see FIG. 7). Using their method, localized bed temperature anomalies and sintering conditions can be observed early enough, within an appropriately long and early enough action window, before an actual problem occurs. In the example of FIG. 7, the action window was approximately 45-25 hours before the combustion boiler system 10 had to be shut down due to bed sintering issues.

[0091] 8A and 8B show the temperature sensor measurement data for each of the temperature sensors 201-208 resulting in the curves shown in Figure 7. Thus, at least eight temperature sensors 20 are sufficient to allow a sufficiently long action window for automatic control of the combustion boiler system 10 or manual control by the boiler operator to reliably detect sintering problems early enough to prevent shutdown of the combustion boiler system 10.

[0092] It is obvious to those skilled in the art that with technological advances, the basic idea of ​​the present invention can be implemented in many ways. Therefore, the present invention and its embodiments are not limited to the above examples, but can vary within the scope of the claims and their legal equivalents.

[0093] In the appended claims and the foregoing description of the invention, unless the context requires otherwise, either expressly or by necessary implication, the word "comprises" or variations such as "comprises" or "comprising" are used in the inclusive sense, i.e., to specify the presence of stated features, but are not used to exclude the presence or addition of further features in various embodiments of the invention. [Explanation of symbols]

[0094] 10 Combustion boiler system 12 Furnace 13 Pipe wall 14 Particle separator 15 Crossover duct 16 Rear flue 18 Flue gas duct 19 Chimney 20 j Temperature sensor (i=1, 2, 3, . . . , 8) twenty one i Heat exchanger (j=1, 2, 3,...,k) 22 Fuel supply section 100 Fluidized Bed Heat Exchanger (FBHE) 102 Return flow path 103 Vortex Finder 104 FBHE Entrance 105 FBHE Exit 120 Loop Stickers 131 Side wall 132 Front wall 133 Side wall 134 Back wall 143 Superheater inlet 144 Superheater outlet 151 Primary fluidization gas supply section 152 Secondary fluidization gas supply section 153 Fluidization gas supply section 180 Flue gas recirculation section 200 steam drums 203 Superheater 250 grid 300 Internet 301 Distributed Control System (DCS) 302 Display / Monitor 303 EDGE Server 304 Local Storage 305 Process Intelligence System 306 Computational Cloud 308 Gateway 370 Combustion Boiler Network 380 Fieldbus

Claims

1. Both define a measurement grid, and each has a measurement point (P ｉ , i=1, . . . , n) ｉ 1. A method for determining local temperature anomalies in a fluidized bed of a combustion boiler system (10) comprising a furnace (12) having a boiler grate (250) comprising: - Each measurement point (P ｉ , i = 1, ..., N) Ｍｉ , i=1, ..., N) and current operating data of the boiler including at least primary air flow rate (x1), fuel moisture (x2), main steam flow rate (x3), flue gas oxygen (x4), and bed pressure (x5) are monitored; - Boiler operating data, i.e. at least primary air flow (x1), fuel moisture (x2), main steam flow (x3), flue gas oxygen (x4), and bed pressure (x5) and the temperature at each measurement point (P ｉ , i=1,...,N) Ｍｉ , i = 1, ..., N), a numerical model (f) is prepared and calibrated; - the measurement point (P ｉ , i=1, . . . , n) are calculated using the numerical model to obtain a calculated bed temperature (T Ｃｉ , i=1,...,n), - the measurement point (P ｉ , i=1, . . . , n), the measured bed temperature (T Ｍｉ ) is the calculated bed temperature (T Ｃｉ ) and if it exceeds the anomaly threshold, it is determined that a local temperature anomaly exists.

2. - at least one measurement point (P ｊ , j is 1, ..., n), the numerical model calculates the calculated bed temperature (T Ｃｊ ) is used to calculate - the calculated bed temperature (T Ｃｉ ) and the measured bed temperature (T Ｍｉ 2. The method of claim 1, wherein the temperature anomaly is compared against an anomaly criterion and a local temperature anomaly is determined to exist if the anomaly criterion is met.

3. The method of claim 1 , wherein the calibration is performed in a delayed manner using historical data.

4. The method of claim 1 or 3, wherein upon detection of a local temperature anomaly, the calibration is not performed for a predetermined time.

5. The method of claim 4 , wherein upon detecting a local temperature anomaly that meets a given threshold, the calibration is not performed for a predetermined time.

6. 3. The method of claim 1, wherein upon detection of a local bed temperature anomaly, the method automatically adjusts the operation of the combustion boiler system (10) and / or indicates to a boiler operator that a local bed temperature anomaly has been detected.

7. The boiler operation data and the measured bed temperature (T Ｍｉ , i=1, ..., N), - Each measurement point (P ｉ , i = 1, ..., n) Ｍｉ , i=1, ..., N) and current operating data of the boiler including at least primary air flow rate (x1), fuel moisture (x2), main steam flow rate (x3), flue gas oxygen (x4), and bed pressure (x5) are monitored and collected as historical data; - Boiler operating data, i.e. at least primary air flow (x1), fuel moisture (x2), main steam flow (x3), flue gas oxygen (x4), and bed pressure (x5) and the temperature at each measurement point (P ｉ , i = 1, ..., n) Ｍｉ , i=1,...,N), a numerical model (f) between the The method according to any one of claims 1 to 5, wherein the method is calibrated so that

8. The method of claim 7 , wherein the calibration is repeated at predetermined intervals.

9. 9. The method of claim 7 or 8, wherein the calibration is aborted upon detection of a local temperature anomaly.

10. 1. A method for assessing the risk of bed sintering in a fluidized bed combustion boiler, comprising: - the combustion boiler system (10) together define a measurement grid, each of which has a measurement point (P ｉ , i=1, . . . , n) ｉ a furnace (12) having a boiler grate (250) with - Current operating data of the boiler, i.e., measured bed temperature (T Ｍｉ , i=1,...,N) are the measurement points (P ｉ , i=1,...,n), - based on the current operating data of the boiler, i) an average of the measured bed temperatures is calculated; ii) the standard deviation of the measured bed temperatures is calculated; iii) the difference between the maximum measured bed temperature and the minimum measured bed temperature is calculated; iv) The degree of dispersion relative to the measured bed temperature [Equation 1] is calculated, - Using the results of calculations i), ii), iii) and iv), a bed sintering index is prepared.

11. moreover v) Calculated bed temperature (T Ｃｉ , I=1,...,n) is calculated, and the measured bed temperature (T Ｍｉ 11. The method of claim 10, wherein a residual between the calculated bed temperature and the calculated bed temperature is calculated, and the result of step v) is also used in preparing the bed sintering index.

12. Calculation bed temperature (T) Ｃｉ , I=1,・・・,n)が, - the measurement point (P ｉ , i=1,...,n) are calculated using at least one numerical bed temperature model between boiler operating data and the measured bed temperatures to obtain a calculated bed temperature (T Ｃｉ , i = 1, ..., n) The method of claim 10, wherein the

13. 13. The method of claim 10, wherein upon detecting a bed sintering index exceeding a predetermined standard, the method automatically adjusts the operation of the combustion boiler system (10) and / or indicates to a boiler operator that a bed sintering condition has been detected.

14. 12. The method of claim 11, wherein the automatic adjustment of boiler operation comprises at least one of: a) increasing or decreasing the combustion air supply (151, 152); b) increasing or decreasing the fuel supply (20); c) increasing or decreasing the bed material supply and / or bed material removal; d) adjusting the recirculation gas flow rate; e) temporarily limiting the load of the boiler.

15. A combustion boiler system (10) configured to carry out the method according to any one of claims 1 to 14.

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