Method and control system for monitoring solid material circulation process in circulating fluidized bed reactor

Abstract

The invention relates to a method for monitoring a solid material circulation process in a circulating fluidized bed reactor (10), comprising at least the following steps: selecting a process variable of the solid material circulation process in a solid material return path (15), and selecting a performance indicator of the solid material cycle process among the selected process variables for each performance indicator of the solid material cycle process; creating a multivariable model for each performance index by using historical data of process variables and performance indexes of the solid material cycle process; determining modeled values of the performance metrics by applying the current measurements of the process variables to the multivariable model; and comparing the modeled value for each performance metric with a respective measured value for each performance metric and checking for the presence of an anomaly between the modeled value and the measured value. The method provides an effect by means of which possible problems in the circulation of the solid material can be effectively anticipated so that remedial actions can be taken sufficiently early to maintain the normal operation of the process. The invention also relates to a control system (48) for monitoring a solid material circulation process in a circulating fluidized bed reactor (10).

Description

Technical Field

[0001] The invention relates to a method for monitoring the circulation of solid material in a circulating fluidized bed reactor according to the preamble of claim 1.

[0002] The invention relates to a control system for monitoring the circulation of solid material in a circulating fluidized bed reactor according to the preamble of the second independent claim. Background Art

[0003] In a circulating fluidized bed reactor, fine solid material is used in the process by fluidizing the solid material to such an extent that a substantial portion of the material is entrained from the reaction chamber to at least one solid material separator, from which a portion of the solid material separated from the gas can be directed to a fluidized bed heat exchanger, and from which it is circulated back to the combustion chamber. Such a CFB reactor is well suited for generating electricity by burning a fuel in the CFB reactor to generate steam, in which case the CFB reactor is often referred to as a CFB boiler. Likewise, it is also known to utilize a CFB reactor to produce a product gas, such as a gaseous fuel that results in a reaction in the CFB reactor. In the case of producing a gaseous fuel from a solid fuel, the CFB reactor is often referred to as a CFB gasifier.

[0004] If corrective procedures are not initiated promptly, challenging fuels may cause particle agglomeration in the fluidized bed material, which may further lead to more severe sintering of the solid material and ultimately to plugging of the solids return system and shutdown of the reactor. For example, in the case of continuous fluctuations in fuel quality, operators may not be able to identify sintering by following normal basic operating routines.

[0005] US 8292977 discloses a system for controlling the amount of particle circulation in a circulating fluidized bed furnace, wherein the particles circulate between a fluidized bed combustion furnace (for heating the particles) and a fluidized bed gasification furnace (for gasifying the raw materials by heating the raw materials with the heated hot particles). The control is based on measuring the pressure in the fluidized bed gasification furnace and controlling the exhaust rate of the fluidized bed gasification furnace.

[0006] Document JP4254004B2 discloses controlling the fluidization rate based on estimating the external circulating solids in a circulating fluidized bed boiler. The estimation is based on measuring the temperature and pressure in the reactor and the external fluidized bed superheater heat exchanger as well as the outlet steam temperature and the amount of desuperheating water.

[0007] JP4443481B2 relates to a system for diagnosing blockage of a flow medium, the system comprising: a plurality of differential pressure gauges, which measure differential pressures at predetermined positions in a circulation path of the flow medium; a plurality of thermometers, which measure temperatures at predetermined positions in a circulation path of the flow medium, and a determination result display device is provided. When the determination device determines that the flow medium is blocked, the determination result display device is used to display the fact that the flow medium is blocked and the position where the flow medium is blocked.

[0008] Although circulating fluidized bed (CFB) reactors have benefits over other combustion technologies, agglomeration issues associated with solid materials in CFB technology are of particular concern as they can lead to unplanned plant shutdowns.

[0009] The object of the present invention is to provide a method and a control system for monitoring the circulation of solid material in a circulating fluidized bed reactor, by means of which unintentional shutdowns can be avoided or at least minimized. Summary of the invention

[0010] The objects of the invention may be substantially met as disclosed in the independent claim and in the other claims describing more details of different embodiments of the invention.

[0011] According to the method of the present invention for monitoring a solid material circulation process in a circulating fluidized bed reactor, the reactor comprises a reaction chamber, at least one solid material separator, a return path between the at least one solid material separator and the reaction chamber, and in the method, the solid material circulation process comprises arranging the solid material to be entrained by the gas flow in the reaction chamber, and further entrained from the reaction chamber to the at least one solid material separator and conveying the solid material from the solid material separator to the reaction chamber via the return path. The method comprises at least the following steps:

[0012] a. selecting a process variable of the solid material circulation process in the return path, and selecting a performance indicator of the solid material circulation process among the selected process variables for each performance indicator of the solid material circulation process,

[0013] b. Use the historical data of process variables and performance indicators of the solid material cycle process to create a multivariate model for each performance indicator

[0014] c. Determine the modeled value of the performance indicator by applying the current measured values ​​of the process variables to the multivariable model

[0015] d. Compare the modeled value of each performance indicator with the corresponding measured value of each performance indicator, and check for the presence of anomalies between the modeled value and the measured value.

[0016] When determining the modeled value of a performance indicator by utilizing an online value process variable and comparing the modeled value of the performance indicator with the online value of the corresponding performance indicator, the method provides an effect by means of which possible problems (such as bed quality-related problems and / or risks of bed material sintering, and / or potential risks of bed material blockage in the solid material circulation) can be effectively foreseen, so that remedial actions can be taken early enough to maintain normal operation of the process.

[0017] According to a preferred aspect of the invention, the method comprises burning the fuel in a circulating fluidized bed reactor, ie in a circulating fluidized bed boiler. Thus, according to a preferred aspect of the invention, the reaction chamber is a combustion chamber.

[0018] According to another aspect of the invention, the method comprises producing a gaseous fuel by converting a combustible material into a gaseous fuel in a circulating fluidized bed reactor (ie, in a circulating fluidized bed gasifier).

[0019] According to one aspect of the invention, the method may include, in conjunction with any other one or more steps of the method, indicating to an operator possible remedial actions to be taken which control the situation in a direction that reduces the tendency of the solid material to agglomerate, the remedial actions comprising at least one of the following:

[0020] - Changing the fuel mixture by reducing the proportion of fuels that are prone to agglomerate formation

[0021] - introducing additives such as clay (e.g. kaolin), or increasing the amount of such additives, thereby increasing the agglomeration temperature of the bed, and / or

[0022] - Reducing the load on the reactor, and / or first reducing the load and then increasing the load, which also reduces the tendency to agglomeration

[0023] - increasing the supply of constituent materials such as sand to the reaction chamber or fluidized bed heat exchanger,

[0024] - Discharge bottom ash from the reaction chamber or increase the rate of discharge of bottom ash, which removes agglomerates from the reaction chamber

[0025] - Removal of solid material from the return path, which also makes it possible to remove agglomerated bed material.

[0026] According to an aspect of the invention, the comparison between the modeled values ​​of the performance indicators and the corresponding measured values ​​of each performance indicator in step d above may be based on at least one of: a difference, an absolute value of the difference, or a ratio.

[0027] According to one aspect of the present invention, the solid material circulation process comprises transferring the solid material from the separator directly to the reaction chamber via a ring seal, wherein at least

[0028] i. Pressure difference of the ring seal in the return path

[0029] ii. The temperature in the ring seal in the return path of the solid material circulation is selected as a performance indicator of the solid material circulation process.

[0030] This aspect relates to embodiments of the invention in which the CFB reactor includes a ring seal in the return path and selected performance indicators provide an efficient way of monitoring the solid material circulation process.

[0031] According to one aspect of the present invention, the solid material circulation process comprises conveying the solid material from the separator directly to the reaction chamber via a return path, wherein at least

[0032] i. Pressure difference in the return path

[0033] ii. The temperature in the return path of the solid material circulation is selected as a performance indicator of the solid material circulation process.

[0034] This aspect relates to embodiments of the invention in which the return path of the CFB reactor is not provided with a ring seal or solid material is directed to the reaction chamber from a location upstream of the ring seal.

[0035] According to one aspect of the present invention, the solid material circulation process comprises transferring the solid material from the separator to the reaction chamber via a fluidized bed heat exchanger, wherein at least

[0036] i. Pressure difference of the ring seal in the return path

[0037] ii. Temperature in the ring seal in the return path of the solid material circulation

[0038] iii. Pressure difference of fluidized bed heat exchanger,

[0039] iv. the temperature of the solid material downstream of the heat exchange unit in the fluidized bed heat exchanger,

[0040] was chosen as a performance indicator for solid material recycling processes.

[0041] This aspect relates to embodiments of the invention in which the selected performance indicators cover a CFB reactor including a ring seal and a fluidized bed heat exchanger in the return path. The selected performance indicators provide an efficient way of monitoring the solid material circulation process at some key locations of the process.

[0042] According to one aspect of the present invention, the temperature of the solid material downstream of the fluidized bed heat exchange unit is measured at the bottom portion of the fluidized bed heat exchanger. According to another embodiment of the present invention, the temperature of the solid in the fluidized bed heat exchanger is measured at the bottom portion of the fluidized bed, above the fluidizing nozzle. Generally, the term "downstream of the heat exchange unit" can be understood as downstream or below the heat exchange tubes of the unit extending into the fluidized bed heat exchanger. In other words, the temperature of the solid material downstream of the fluidized bed heat exchange unit can be measured below the heat exchange unit in the fluidized bed heat exchanger. In addition, in other words, the temperature of the solid material downstream of the fluidized bed heat exchange unit can be measured below the heat exchange tubes in the fluidized bed heat exchanger and above the fluidizing nozzle. The fluidized bed heat exchange unit can be selected as an evaporator, a superheater or a reheater as needed, to name a few.

[0043] According to one aspect of the present invention, the solid material circulation process comprises transferring the solid material from the separator directly to the reaction chamber via a ring seal, wherein at least

[0044] i. The pressure difference of the ring seal in the return path, and

[0045] ii. The temperature in the ring seal in the return path of the solid material circulation is selected as a performance indicator of the solid material circulation process,

[0046] And among them

[0047] i. Performance Indicator - The process variables of the pressure difference of the ring seal in the return path include: the total reaction gas flow rate supplied to the reactor, the product gas temperature upstream of the ring seal, and the bed temperature in the reaction chamber.

[0048] ii. Performance Indicator - Temperature in the Ring Seal during Solid Material Circulation The process variables include: the total reaction gas flow rate fed to the reactor, the temperature of the product gas upstream of the ring seal, and the bed temperature in the reaction chamber.

[0049] According to one aspect of the present invention, in the case of a circulating fluidized bed boiler, the product gas may be referred to as flue gas containing combustion reaction products.

[0050] According to one aspect, in the case of a circulating fluidized bed gasifier, when gasifying a carbonaceous fuel (such as a biofuel or a waste-derived fuel), air and / or oxygen and steam may be supplied to the reaction chamber to generate a product gas, wherein the main components include carbon monoxide CO, hydrogen H2 and hydrocarbons C x H y The product gas of a circulating fluidized bed gasifier may be referred to as syngas.

[0051] According to one aspect of the present invention, the solid material circulation process comprises transferring the solid material from the separator directly to the reaction chamber via a ring seal, wherein at least

[0052] i. The pressure difference of the ring seal in the return path, and

[0053] ii. The temperature in the ring seal in the return path of the solid material circulation is selected as a performance indicator of the solid material circulation process,

[0054] And among them

[0055] i. Performance Indicator - Pressure difference of the ring seal in the return path The process variables include: the total combustion gas flow rate supplied to the reactor, the flue gas temperature upstream of the ring seal, and the bed temperature in the reaction chamber.

[0056] ii. Performance Indicator - Temperature in the Ring Seal During Solid Material Circulation The process variables include: the total combustion gas flow rate fed into the reactor, the temperature of the flue gas upstream of the ring seal, and the bed temperature in the reaction chamber.

[0057] According to one aspect of the invention, the reaction gas is air. According to one aspect of the invention, the reaction gas is air, or a mixture of air and recycled flue gas. According to one aspect of the invention, the reaction gas is pure oxygen. According to one aspect of the invention, the reaction gas is a mixture of oxygen and recycled product gas. According to one aspect of the invention, in the case of a circulating fluidized bed boiler, the reaction gas may be referred to as combustion gas.

[0058] According to one aspect of the invention, the method comprises gasifying fuel in a CFB reactor, and the solid material circulation process comprises transferring the solid material from a separator directly to a reaction chamber via an annular seal, wherein at least

[0059] i. The pressure difference of the ring seal in the return path, and

[0060] ii. The temperature in the ring seal in the return path of the solid material circulation is selected as a performance indicator of the solid material circulation process,

[0061] And among them

[0062] i. Performance Indicator - The process variables of the pressure difference of the ring seal in the return path include: the total gas flow rate supplied to the reactor, the product gas temperature upstream of the ring seal, and the bed temperature in the reaction chamber.

[0063] ii. Performance indicator - process variables of temperature in the ring seal during solid material circulation include: total gas flow rate fed into the reactor, temperature of product gas upstream of the ring seal, bed temperature in the reaction chamber. According to an embodiment, the circulating fluidized bed reactor is a circulating fluidized bed gasifier, and wherein the fluidizing gas comprises at least one of the following: an inert gas, steam, oxygen or a mixture thereof.

[0064] According to one aspect of the present invention, the solid material circulation process comprises transferring the solid material from the separator to the reaction chamber via a fluidized bed heat exchanger, wherein at least

[0065] i. Pressure difference of the ring seal in the return path

[0066] ii. Temperature in the ring seal in the return path of the solid material circulation

[0067] iii. Pressure difference of fluidized bed heat exchanger,

[0068] iv. Temperature of solid material downstream of the fluidized bed heat exchange unit

[0069] is selected as a performance indicator of the process in a step of a solid material recycling process, and wherein

[0070] i. Performance Indicator - Pressure difference of the ring seal in the return path. Process variables include: total reaction gas flow rate supplied to the reactor, temperature of product gas upstream of the ring seal, bed temperature in the reaction chamber,

[0071] ii. Performance Indicator - Temperature in the Ring Seal during Solid Material Circulation The process variables include: the total reaction gas flow rate fed to the reactor, the temperature of the product gas upstream of the ring seal, the bed temperature in the reaction chamber,

[0072] iii. Performance Indicator - Pressure difference of fluidized bed heat exchanger The process variables include: the total reaction gas flow rate fed to the reactor, the temperature in the ring seal in the return path of the solid material circulation, the pressure difference of the ring seal, the gas flow rate to the fluidized bed heat exchanger, the bed temperature in the reaction chamber,

[0073] iv. Performance Indicator - Temperature of Fluidized Bed Heat Exchanger The process variables include: total reaction gas flow rate fed to the reactor, temperature in the ring seal, pressure difference of the ring seal, gas flow rate to the fluidized bed heat exchanger, bed temperature in the reaction chamber.

[0074] According to one aspect of the present invention, the total reactant gas flow rate is the total flow rate of the gas flow entering the reaction chamber of the CFB reactor.

[0075] According to embodiments wherein the method comprises combusting the fuel in the presence of air, the aggregate reactant gas flow rate is the total flow rate of the air flow entering the reaction chamber of the CFB reactor.

[0076] According to embodiments wherein the method comprises combusting the fuel in the presence of air, the aggregate air flow rate is a flow rate including the primary air flow supplied to the reaction chamber.

[0077] According to embodiments wherein the method comprises combusting the fuel in the presence of air, the total air flow rate is a flow rate comprising the primary air flow and the secondary air flow supplied to the reaction chamber.

[0078] According to embodiments wherein the method comprises combusting the fuel in the presence of air, the total air flow rate is the flow rate comprising the primary, secondary and tertiary air flows supplied to the reaction chamber.

[0079] According to an embodiment wherein the method comprises combusting the fuel in the presence of air, the total air flow rate is the flow rate comprising the primary and secondary air flows fed into the reaction chamber and the air fed into the fluidized bed heat exchanger.

[0080] According to embodiments wherein the method comprises combusting the fuel in the presence of air, the combined air flow rate is the total flow rate of the air flow entering the reaction chamber and the air flow of the fluidized bed heat exchanger.

[0081] According to embodiments wherein the method comprises combusting the fuel in the presence of air, the total air flow rate is the flow rate comprising the primary and secondary air flows supplied to the reaction chamber and the fluidized bed heat exchanger and to the annular seal.

[0082] According to embodiments wherein the method comprises combusting the fuel in the presence of air, the aggregate air flow rate is the total flow rate of the air streams entering the reaction chamber, the fluidized bed heat exchanger, and entering the annular seal.

[0083] According to one aspect of the present invention, the solid material circulation process comprises transferring the solid material from the separator to the reaction chamber via a fluidized bed heat exchanger, wherein at least

[0084] i. Pressure difference of the ring seal in the return path

[0085] ii. Temperature in the ring seal in the return path of the solid material circulation

[0086] iii. Pressure difference of fluidized bed heat exchanger,

[0087] iv. Temperature of the solid material downstream of the fluidized bed heat exchange unit

[0088] The performance indicators of the process are selected as steps in the solid material recycling process,

[0089] And among them

[0090] i. Performance Indicator - Pressure difference of the ring seal in the return path. Process variables include: total combustion gas flow rate fed to the reactor, temperature of product gas upstream of the ring seal, bed temperature in the reaction chamber,

[0091] ii. Performance Indicator - Temperature in the Ring Seal during Solid Material Circulation Process variables include: Total combustion gas flow rate fed to the reactor, temperature of product gas upstream of the ring seal, bed temperature in the reaction chamber

[0092] iii. Performance Indicator - Pressure difference of fluidized bed heat exchanger The process variables include: total combustion gas flow rate fed to the reactor, temperature in the ring seal in the return path of the solid material circulation, pressure difference of the ring seal, combustion gas flow rate to the fluidized bed heat exchanger, bed temperature in the reaction chamber,

[0093] iv. Performance Indicator - Temperature of Fluidized Bed Heat Exchanger The process variables include: total combustion gas flow rate fed to the reactor, temperature in the ring seal, pressure difference of the ring seal, combustion gas flow rate to the fluidized bed heat exchanger, bed temperature in the reaction chamber.

[0094] According to one aspect of the present invention, the aggregate combustion gas flow rate is the total flow rate of the combustion gas flow entering the reaction chamber of the CFB reactor.

[0095] According to an aspect of the present invention, the total combustion gas flow rate is a flow rate including a primary combustion gas flow supplied into the reaction chamber.

[0096] According to a preferred aspect of the present invention, the total combustion gas flow rate is a flow rate including a primary combustion gas flow and a secondary combustion gas flow supplied into the reaction chamber.

[0097] According to another preferred aspect of the present invention, the total combustion gas flow rate is a flow rate including a primary combustion gas flow, a secondary combustion gas flow, and a tertiary combustion gas flow supplied into the reaction chamber.

[0098] According to one aspect of the invention, the combustion gas is air and recycled product gas. According to one aspect of the invention, the combustion gas is oxygen and recycled product gas. According to one aspect of the invention, the combustion gas is primary air and recycled product gas. According to one aspect of the invention, the combustion gas is oxygen and recycled product gas.

[0099] According to one aspect of the invention, the bed temperature is an average bed temperature in the reaction chamber, which is calculated from at least two measurement points in the reaction chamber, at least one of which is at a grid height of the chamber.

[0100] According to one aspect of the invention, creating a multivariate model includes

[0101] - measuring the value of a predetermined process variable and storing the measured value together with a time stamp, thus forming historical data of the process variable,

[0102] - measuring the value of the performance indicator and storing the measured value together with a timestamp, thus forming historical data of the performance indicator,

[0103] - Select valid historical data using pre-determined data filters.

[0104] According to one aspect of the invention, creating a multivariate model includes

[0105] - measuring the value of a predetermined process variable and storing the measured value together with a time stamp, thus forming historical data of the process variable,

[0106] - measuring the value of the performance indicator and storing the measured value together with a timestamp, thus forming historical data of the performance indicator,

[0107] -Select valid historical data using pre-determined data filters, and

[0108] -Update the multivariate model.

[0109] According to one aspect of the invention, the data filter is configured to approve data older than a preset quarantine time. Advantageously, in this way, the model will not be trained with potentially abnormal operating values ​​(e.g. due to solid material starting to agglomerate in the ring seal). In other words, data related to the problem is not used in model training.

[0110] According to an aspect of the invention, the data filter is configured to approve data older than two weeks.

[0111] According to an aspect of the invention, the data filter is configured to approve data that is no older than two months.

[0112] According to an aspect of the invention, the data filter is configured to filter out any data from a shutdown situation and / or from any abnormal operation from the historical data based on predefined limits of input variables or external information of abnormal operation.

[0113] According to one aspect of the present invention, the method comprises at least the following steps:

[0114] a. selecting a process variable of the solid material circulation process in the return path, and selecting a performance indicator of the solid material circulation process among the selected process variables for each performance indicator of the solid material circulation process,

[0115] b. Using historical data on process variables and performance indicators of the solid material recycling process, create a multivariate model for each performance indicator,

[0116] The multivariate model is a multivariate linear regression as follows with a first number (N) of measured observations for each process variable of the solid material cycle process and a second number (P) of different process variables

[0117] y i =b0+b1xi，1 +b2x i,2 +...b P x i，P +ε i

[0118] where i=1,2,...N

[0119] And the method comprises reading y i 、x i,1 、x i,2 , …, x i,p Historical data, where y = performance indicator, and x i,1 、x i,2 , …, x i,p is the process variable,

[0120] And solve the constant b0 and factors b1, b2, ...b p

[0121] The fit is performed by minimizing the sum of the squares of the vertical deviations from each data point to the line of best fit to the historical data.

[0122] c. Determine the modeled value of the performance indicator by applying the current measured values ​​of the process variables to the multivariable model

[0123] d. Compare the modeled value of each performance indicator with the corresponding measured value of each performance indicator, and check for the presence of anomalies between the modeled value and the measured value.

[0124] According to one aspect of the present invention, the method comprises at least the following steps:

[0125] a. selecting a process variable of the solid material circulation process in the return path, and selecting a performance indicator of the solid material circulation process among the selected process variables for each performance indicator of the solid material circulation process,

[0126] b. Using historical data on process variables and performance indicators of the solid material recycling process, create a multivariate model for each performance indicator,

[0127] The multivariate model is a multivariate linear regression as follows with a first number (N) of measured observations for each process variable of the solid material cycle process and a second number (P) of different process variables

[0128] y i =b0+b1x i,1 +b2x i,2 +...b P x ，iP + εi

[0129] where i=1,2,...N

[0130] And the method comprises reading y i 、x i,1 、x i,2 , …, x i,p Historical data, where y = performance indicator, and x i,1 、x i,2 , …, x i,p is the process variable,

[0131] And solve the constant b0 and factors b1, b2, ...b p

[0132] and fits by minimizing the sum of the squares of the vertical deviations from each data point to the line of best fit to the historical data,

[0133] Wherein creating the multivariate model comprises: measuring the value of a predetermined process variable, storing the measured value together with a time stamp, thereby forming historical data of the process variable; measuring the value of a performance indicator, storing the measured value together with a time stamp, thereby forming historical data of the performance indicator; selecting valid historical data using a predetermined data filter; and updating the multivariate model,

[0134] c. Determine the modeled value of the performance indicator by applying the current measured values ​​of the process variables to the multivariable model

[0135] d. Compare the modeled value of each performance indicator with the corresponding measured value of each performance indicator, and check for the presence of anomalies between the modeled value and the measured value.

[0136] According to an aspect of the invention, the first number N of measurement observations is at least 10 times greater than the second number P of different process variables.

[0137] According to an aspect of the invention, the multivariate pattern is updated after a period of time either triggered by the elapse of a constant predetermined time interval or by a trigger input.

[0138] According to one aspect of the present invention, a risk index for each performance indicator is calculated using information on the presence of anomalies.

[0139] According to one aspect of the invention, a risk index for each performance indicator is calculated using anomalies between modeled values ​​and measured values.

[0140] According to one aspect of the present invention, the reactor includes at least a first return path between a first solid material separator and a reaction chamber and a second return path between a second solid material separator and the reaction chamber, wherein a method regarding a solid material circulation process in the first return path and a method regarding a solid material circulation process in the second return path are respectively implemented on the return paths.

[0141] A control system for monitoring a solid material circulation process in a circulating fluidized bed reactor between a reaction chamber and at least one solid material separator and reaching the reaction chamber via a return path including a ring seal; and furthermore, a control system for controlling a solid material circulation process, wherein the control system comprises

[0142] A performance modeling unit, the performance modeling unit comprising

[0143] - Access means for storing and recording the performance indicators of the solid material circulation process in the return path and the source historical data of the process variables for each performance indicator

[0144] -Multivariate models for each performance indicator

[0145] - executable instructions which, when executed in a data processing unit,

[0146] o updating the multivariable model for each performance indicator using historical data of predetermined process variables and performance indicators of the solid material cycle process to produce a calibrated multivariable model,

[0147] A performance diagnosis module, the performance diagnosis module includes

[0148] - an input device for receiving measured data of process variables and performance indicators of the solid material circulation process,

[0149] - executable instructions which, when executed in a data processing unit,

[0150] oDetermine the modeled value of the performance indicator by applying the current measured value of the process variable to the calibrated multivariable model

[0151] o Compare the modeled value for each performance indicator with the corresponding measured value of the performance indicator and check for the presence of anomalies between the modeled value and the measured value.

[0152] According to one aspect of the invention, the control system comprises measuring sensors for at least the following process variables: a pressure sensor for measuring the pressure drop in the ring seal; a product gas temperature sensor; and means for determining the total air flow rate to the reactor and the bed temperature in the reaction chamber of the reactor.

[0153] According to one aspect of the invention, solid material circulates in a circulating fluidized bed reactor between a reaction chamber and at least one solid material separator and reaches the reaction chamber via a fluidized bed heat exchanger in a return path, and the control system includes measurement sensors for at least the following process variables: a pressure sensor for measuring the pressure drop in the ring seal; a product gas temperature sensor upstream of the ring seal; a temperature sensor in the ring seal; a pressure sensor for measuring the pressure drop in the fluidized bed heat exchanger; a temperature sensor for measuring the temperature of the solid material downstream of the fluidized bed heat exchange unit in the fluidized bed heat exchanger; and a device for determining the total air flow rate to the reactor and the bed temperature in the reaction chamber of the reactor.

[0154] This provides an effect by means of which possible problems in the solid material circulation can be effectively foreseen. The detected anomalies are precursors to problems in the solid material circulation process, such as a sintering tendency.

[0155] Since unnecessary shutdowns are avoided, the availability of the CFB reactor is increased and operating costs are reduced.

[0156] Thus, by monitoring the measured and modeled values, the onset of solid material sintering can be detected and measures can be taken in time to repair the process, or at least avoid that the sintering gets worse. In CFB boiler applications, this can help avoid shutdowns of the combustion boiler system due to solid material sintering and also avoid expensive repairs. Advantageously, anomalies detected in the solid material circulation give information about the bed quality, preferably whether sintering has occurred in the solid material. Or in other words, information about solid circulation related problems can be received, which may have a tendency to lead to shutdowns if remedial action is not taken. Thus, the availability of the reactor can be improved and / or the operating costs can be reduced. The method is preferably performed automatically in a local reactor control system or remotely, preferably in a process intelligence system.

[0157] The multivariate model may be an artificial intelligence tool. According to an embodiment of the present invention, the multivariate model may be a neural network.

[0158] Preferably, when an anomaly is detected, calibration of the model is not performed for a predefined time (i.e., calibration is omitted). In addition to or as an alternative to boiler / reactor shutdown situations, abnormal operations and / or abnormal conditions are preferably filtered out or omitted from the calibration data. This approach can help avoid possible cycle quality problems from contaminating the calibration. This approach can be fine-tuned so that when a local temperature anomaly that meets a given threshold is detected, calibration is not performed for a predefined time. Then, only sufficiently severe conditions that produce a sufficiently large abnormal signal can be selected to cause calibration to be skipped within a predefined time period.

[0159] According to an aspect of the present invention, in the method, a risk index for a performance indicator is evaluated as follows.

[0160] - Current data on performance indicators (KPIs) for measuring solid material recycling,

[0161] - Based on the current operating data of the reactor, calculate at least one of the following:

[0162] i) Average value of performance indicators;

[0163] ii) measure the standard deviation of the performance indicator;

[0164] iii) the difference between the maximum measured performance indicator value and the minimum measured performance indicator value;

[0165] iv) the difference between the average performance index and the measured performance index;

[0166] - Using the calculation results from i), ii), iii) and / or iv), prepare a risk index for the performance indicator KPI.

[0167] The calculated results from i), ii), iii) and / or iv) are compared with corresponding predefined limits to obtain risk indices for the mean, standard deviation, difference between maximum KPI value and minimum KPI value, and / or difference between average KPI value and measured KPI value.

[0168] In KPI k (k=1,K) In the calculation of the deviation from the average KPI, the average includes the KPI k All KPI measurements except the measurement results of

[0169] Preferably, in the method,

[0170] v) Calculate KPIs k (k=1, ..., K) and calculate the residual between the measured value of the performance indicator and the modeled value of the performance indicator. The result from step v) is advantageously also used to prepare a risk index, preferably such that the residual is compared with the corresponding predefined limit, thereby obtaining a sintering risk index for the KPI residual.

[0171] According to an aspect of the invention, in the method, the risk index for the performance indicator is evaluated, so that current data of the performance indicator (KPI) of the solid material cycle is measured, and

[0172] v) Calculate KPIs k(k=1, ..., K) and calculate the residual between the measured value of the performance indicator and the modeled value of the performance indicator. The result from step v) is advantageously also used to prepare a risk index, preferably such that the residual is compared with the corresponding predefined limit, thereby obtaining a sintering risk index for the KPI residual.

[0173] For example, the final risk index may then be the maximum of the above risk indices. In this way, the prediction accuracy of the bed sintering index may still be improved.

[0174] Advantageously, according to an aspect of the invention, the most critical locations where the greatest risk of blockage or sintering occurs can be located. This will be particularly advantageous in the case of several separator and return path components.

[0175] In this regard, the term bed temperature refers to a number that is a typical representation of the bed temperature, such as an average bed temperature. The bed temperature may be calculated in different ways, such as an arithmetic mean, a truncated mean, or a mid-range number, to name a few. The calculation may include data of a desired amount in one or several locations in the CFB reactor.

[0176] The exemplary embodiments of the invention presented in this patent application should not be interpreted as limiting the applicability of the appended claims. The verb "comprise" is used in this patent application as an open limitation, which does not exclude the presence of unrecited features. Unless explicitly stated otherwise, the features recited in the dependent claims may be freely combined with each other. In particular, novel features that are considered to be characteristic of the invention are set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0177] In the following, the present invention will be described with reference to the accompanying exemplary schematic drawings, in which

[0178] Figure 1 A circulating fluidized bed reactor according to an embodiment of the present invention is shown in FIG.

[0179] Figure 2 A control system according to an embodiment of the present invention is shown in FIG.

[0180] Figure 3 A circulating fluidized bed reactor according to another embodiment of the present invention is shown in FIG.

[0181] Figure 4 The results obtained with the method according to the invention are shown in figure, and

[0182] Figure 5 A circulating fluidized bed reactor according to another embodiment of the present invention is shown in FIG. DETAILED DESCRIPTION

[0183] In the following, the accompanying drawings illustrate examples of methods generally related to the air combustion of fuel in a CFB reactor. Even though some minor structural changes may be required, the CFB reactor and its embodiments described in the accompanying drawings are also suitable for producing synthesis gas by implementing a gasification process in the reactor. Accordingly, the described CFB reactor and its embodiments can be used to implement a so-called oxy-combustion process, meaning combustion using an oxygen-rich gas that may contain air and / or recycled product gas. Figure 1 Schematically depicting a circulating fluidized bed reactor 10, specifically a circulating fluidized bed boiler 10, which is configured to produce superheated steam in a manner known per se. For simplicity, the circulating fluidized bed boiler will be referred to as a CFB boiler. The CFB boiler 10 includes a combustion chamber 12, at least one solid material separator 14, and a solid material return channel 16. Typically, the route of the separated solid material from the separator back to the combustion chamber is referred to as the return path 15. The combustion chamber 12 includes a tube wall, a so-called finned tube wall, in which the fins are welded between the tubes. These wall tubes are connected to the water steam circuit of the boiler system (not shown). The solid material separator 14 is preferably cooled, also similar to the combustion chamber 12 including a tube wall. The combustion chamber 12 includes a wind box 18, which is configured to supply a fluidizing gas, typically air, through a nozzle of a grid 20 at the bottom of the combustion chamber 12. The air introduced through the grid acts as a fluidizing gas and is primary combustion air. Secondary air can be supplied to the combustion chamber 12 at a higher altitude via one or more air inlets 21. As previously discussed, the fluidizing gas and the combustion gas are typically air, but they may also include recycled product gas and / or oxygen or a mixture thereof. It should be understood that, in general, the term product gas may be understood as meaning that the gas leaving the separator 14 is the product gas of the reaction in the reaction chamber. For example, if the process comprises gasification of a fuel material, the product gas is a combustible gas, so-called syngas, and if the process comprises burning a fuel in a reaction chamber and producing steam with released heat, the product gas may be referred to as flue gas. In some practical applications, such as so-called oxygen combustion, part of the flue gas may be recycled back to the reaction chamber as fluidizing gas, and therefore it may be referred to as recycled gas.

[0184] The wind box 18 and other air inlets are connected to an air source 24. This is an example of a gas-driven CFB boiler. At least one fuel inlet 22 is connected to the combustion chamber 12. The operation of the CFB boiler involves a solid material circulation process, which at this point can also be referred to as bed material. The bed material may include sand, limestone and / or clay (in particular, it may include kaolin), as well as unburned fuel. Due to the bed material inside the boiler, the CFB boiler has a high heat transfer coefficient and a substantially uniform temperature distribution, and has a relatively low stable combustion temperature. The combustion of the fuel in the circulating fluidized bed causes heating, thereby evaporating the water in the water-steam circuit and superheating the steam, which can be used in a known manner as such, for example, to generate electrical power in a steam turbine generator. The steam cycle will not be described in more detail here.

[0185] A CFB boiler is characterized in that during its operation, a solid material circulation process is maintained via the route formed by the combustion chamber, the separator and the solid return path. The combustion of fuels in a CFB results in efficient combustion of various solid fuels and low emissions, even when fuels with completely different calorific values ​​are burned simultaneously. Due to fluidization, the solid material moves internally inside the combustion chamber 12, generally upwards in the middle section of the chamber, while near the walls the solids flow downwards, as indicated by Figure 1 . The product gas and solid material flow from the combustion chamber 12 to the inlet of the solid material separator 14, which is connected to the combustion chamber via a connecting pipe 26. The solid material separator 14, preferably a cooling cyclone separator, comprises a first outlet 28 for the product gas, and a second outlet 30 for the separated solid material 32. The first outlet 28 of the separator is actually connected to a return 40. The return comprises a plurality of heat exchange devices, which may include an air preheater 46, an economizer 44, and a superheater and reheater 42. For example, the actual amount of different heat transfer surfaces in each of these components may be selected differently for each CFB boiler according to actual needs.

[0186] The solid material conveyed by the product gas to the separator 14 is separated from the gas, as depicted by the arrows in the figure. The second outlet 30 (which may also be referred to as the particle outlet) is connected to the lower part of the combustion chamber 12 via the return path 15 to return the separated solid material to the combustion chamber 12. The return path 15 is provided with a so-called ring seal 32, which prevents backflow from the combustion chamber 12 to the particle outlet and allows the separated solid material to be controllably supplied back to the combustion chamber 12. The ring seal may also be referred to as an air seal. The operation of the ring seal is controlled by fluidizing air, which may be controllably supplied through the air inlet 23. Therefore, the solid material circulation includes causing the solid material to flow from the combustion chamber 12 to the solid material separator 14, and from the solid material separator 14 to flow back to the combustion chamber 12 via the return path 15 and the ring seal 32. During the operation of the CFB boiler, the solid material circulation process is maintained and controlled. The general direction of movement of the solid material can be used to refer to the position in the CFB boiler, which direction becomes clear in the above description.

[0187] In CFB boilers, solid material circulation can be divided into two categories: internal circulation material flow, which means that solid material circulates inside the combustion chamber (12), which is Figure 1 The inverted U-shaped arrow in FIG. 1 is schematically depicted and as discussed above; and external circulation material flow, meaning that solid material flows outside the combustion chamber (i.e., in the particle separator and the ring seal and return path 15 (in Figure 1 External circulation material flows may also involve the handling of solid materials in fluidized bed heat exchangers, such as Figure 3 Advantageously, according to an aspect of the present invention, in other words, the solid material in the return path may be referred to as solid material in the external circulation of the CFB boiler.

[0188] In order to monitor the solid material circulation process, the CFB boiler 10 includes a plurality of sensors for obtaining online data of performance indicators and process variables. When the online data is stored after the measurement time, it becomes historical data. In order to implement the method according to the present invention, at least the following sensors and measurement points are arranged to the CFB boiler:

[0189] a first pressure sensor 101 , which is arranged upstream of the ring seal 32 but downstream of the solid material separator, ie between the ring seal and the solid material separator 14 ;

[0190] A second pressure sensor 102, which is arranged downstream of the ring seal 32 and between the ring seal 32 and the combustion chamber 12;

[0191] The purpose of the first and second pressure sensors is to determine the pressure difference provided by the ring seal 32 .

[0192] A first temperature sensor 100 , which is arranged in the ring seal 32 ;

[0193] - A second temperature sensor 103, which is arranged upstream of the ring seal 32; Figure 1 As shown in FIG. 1 , the second temperature sensor 103 is arranged at the first outlet 28 of the solid separator 14. Figure 1 In the sense of

[0194] - a first air flow rate sensor 105 for measuring the primary air flow rate through the grid 20 of the CFB boiler;

[0195] - A second air flow rate sensor 106 for measuring the secondary air flow rate;

[0196] The purpose of the first and second air flow rate sensors is to determine the aggregate air flow rate supplied to the CFB boiler.

[0197] A plurality of third temperature sensors 104 , connected to the combustion chamber 12 and arranged to determine the bed temperature in the combustion chamber 12 .

[0198] Additionally, there may be an air flow rate sensor 109 for measuring the air flow rate to the seal, which may optionally be included in the total air flow rate, such as Figure 1 A temperature sensor downstream of the second outlet 30 of the separator 14 provides a measurement representative of the temperature of the solid material.

[0199] The CFB boiler also includes a control system 48 for managing numerical operations related to the control of the CFB boiler, and in particular for monitoring the solid material circulation process in the CFB boiler. It should be understood that Figure 1 is an exemplary description of a solid material circulation process via a certain type of return path and a description of a solid material circulation process via one return path. If the CFB boiler comprises more than one return path (in practice, this is often the case), the present invention can be applied to each return path separately. Advantageously, the CFB boiler can be provided with a solid material separator 14 and a corresponding return path 15 on opposite sides of the combustion chamber 12 (not shown in the figure).

[0200] exist Figure 2 In the present invention, there is a general illustration of the method and control system 48 in a control system by which the solid material circulation process in the CFB reactor 10 can be monitored so that indications of conditions related to the solid material circulation that may lead to a shutdown of the reactor are observed early enough to take corrective action and a shutdown of the reactor can be avoided.

[0201] The control system 48 participates in implementing a method for monitoring the solid material circulation process in the circulating fluidized bed boiler 10. The control system includes one or more computers and executable instructions (i.e., computer programs) that, when executed in the control system 48, implement the method in the circulating fluidized bed boiler 10. The method includes

[0202] a. Selecting the performance index of the solid material circulation process and the process variable for each performance index of the solid material circulation process,

[0203] b. using the historical data of process variables and performance indicators of the solid material cycle process to calibrate the multivariable model for each performance indicator,

[0204] c. determining a modeled value of the performance indicator by applying the current measured value of the process variable to the multivariable model,

[0205] d. Compare the modeled value of each performance indicator with the corresponding measured value of each performance indicator, and check for the presence of anomalies between the modeled value and the measured value.

[0206] The control system includes a performance modeling unit 400. The modeling unit 400 includes executable instructions that, when executed in the control system 48, calibrate the multivariable model for each performance indicator using historical data of predetermined process variables and performance indicators of the solid material recycling process to produce a calibrated multivariable model.

[0207] The performance modeling unit 400 has or is provided with access means, such as data transmission communication with a) performance indicators of the solid material circulation process obtained from the CFB boiler and b) a historical data source 401 of process variables for each performance indicator. The historical data is stored in a data medium, which serves as the historical data source 401, obtained by measuring predetermined process variables 101, 102, 103, ... 109 (see Figure 1 ), and storing the measured values ​​together with a time stamp, thus forming historical data of the process variable. Acquiring historical data involves measuring the values ​​of the performance indicators, respectively, and storing the measured values ​​together with a time stamp, thus forming historical data of the performance indicators. The control system 48 includes a data filter unit 406, which is configured to filter out invalid process data, and thus the historical data includes data that has been subjected to a filtering process using a predetermined data filter. Therefore, the historical data is data describing normal operating conditions of the CFB boiler 10.

[0208] Advantageously, the filtering process 406 may include the following conditions or rules. First, an isolation time is set for the measured data so that only data older than a preset isolation time is approved. The isolation time depends on the situation. In some practical applications, the isolation time may even be as short as three to seven days. However, preferably, the isolation time is seven to fourteen days; even more preferably, at least two weeks. In addition, it is preferred to filter out data that may be outdated because it is too early, and therefore the predetermined data filter is configured to approve data that is no earlier than a predetermined time, advantageously no earlier than two months. In addition, the filter unit is configured to filter out any data from shutdown situations and / or data originating from any abnormal operating conditions from the historical data, for example based on predefined limits for input variables or external information that sets data as unavailable or abnormal operation.

[0209] Thus, the model is based on historical data representing normal operating conditions. Figure 1 The historical data related to the CFB boiler shown in includes data on the following process variables and performance indicators:

[0210] - a pressure value upstream of the ring seal 32 but downstream of the solid material separator, ie between the ring seal and the solid material separator 14 (sensor 101 );

[0211] - pressure value downstream of the ring seal 32, between the ring seal 32 and the combustion chamber 12 (sensor 102);

[0212] - or alternatively, the pressure difference across the ring seal 32 (combined sensors 101, 102)

[0213] - Temperature upstream of the ring seal 32 (sensor 103)

[0214] - Total air flow rate supplied to the CFB boiler (sensors 105, 106)

[0215] - Aggregate bed temperature in the combustion chamber 12 (sensor 104 ).

[0216] Performance indicators represent factors that describe the state of solid material cycle processes. Figure 1 In the case of the embodiment shown, the performance indicators are advantageously

[0217] i. The pressure difference of the ring seal in the return path, and

[0218] ii. Temperature in the ring seal in the return path of the solid material circulation

[0219] The data in the historical data source 401 are used as input to the modeling unit 400, which is configured to prepare and / or calibrate a multivariate model assigned individually for each performance indicator (in this case, for both performance indicators). Thus, the performance modeling unit 400 provides a multivariate model for each performance indicator. The calibration can be repeated at predefined time intervals or periodically. This helps to keep the model realistic, reflecting possible changes caused by normal use of the CFB boiler, but also changes in fuel quality, environmental conditions (temperature, ambient humidity, ambient pressure changes), which may cause operating parameters to change over time. When an anomaly is detected in the process, the calibration can be blocked. In this way, it can be ensured that a problem that has just occurred in the bed material circulation will not contaminate the calibration and the model.

[0220] The model can be constructed by the modeling unit 400 using multivariate linear regression. In principle, the coefficients of the model are estimated using past input values ​​of the model (i.e., measured historical data). The model is then used to estimate the current situation by utilizing current online data and the estimated coefficients.

[0221] For example, in linear regression, the response variable is expected to be a linear combination of the process variables. Multiple linear regression can be used to model the relationship between multiple process variables and a performance indicator by fitting a linear equation to historical data.

[0222] exist Figure 1 In the case of the embodiment shown in , a multivariate model of the ring seal temperature with N observations is defined as follows:

[0223] y i =b0+b1x i，1 +b2x i,2 +b3x i，3 +ε i ,

[0224] in

[0225] y represents the value as a performance indicator of the ring seal temperature,

[0226] x i,1 is the ith temperature value upstream of the ring seal 32 (sensor 103)

[0227] x i,2 is the i-th total air flow rate value supplied to the CFB boiler (sensors 105, 106)

[0228] x i,3 is the i-th bed temperature value in the combustion chamber 12 (sensor 104)

[0229] b0 is a constant, b1…b3 are the unknown KPI-specific coefficients to be estimated, and

[0230] εi includes the experimental error of the model.

[0231] exist Figure 1 In the case of the embodiment shown in , a multivariate model of the annular seal pressure difference with N observations is defined as follows:

[0232] y i =b0+b1x i,1 +b2x i,2 +b3x i,3 +ε i ,

[0233] in

[0234] y represents the value of the performance indicator,

[0235] x i,1 is the ith temperature value upstream of the ring seal 32 (sensor 103)

[0236] x i,2 is the i-th total air flow rate value supplied to the CFB boiler (sensors 105, 106)

[0237] x i,3 is the i-th bed temperature value in the combustion chamber 12 (sensor 104)

[0238] b0 is a constant, b1…b3 are the unknown KPI-specific coefficients to be estimated, and

[0239] ε i Include the experimental error of the model.

[0240] The fit is performed by minimizing the sum of squares of the vertical deviations from each data point to the line that best fits the observed data, that is, the optimal coefficient values ​​are obtained by minimizing the sum of squared errors.

[0241] The modeling unit 400 provides the required coefficients of the model, which are based on the available historical data, for modeling the performance indicators by applying the online data of the process variables to the model. During the operation of the control system 48 and the CFB boiler 10, the historical data including the data of the process variables and the performance indicators are continuously read and stored in the historical data source 401. The modeling unit 400 is configured to update or calibrate the model (i.e., the coefficients of the model) so that the model learns the latest conditions of the normal operation of the solid material circulation process.

[0242] A performance diagnostic module 404 is also provided in the control system 48. The performance diagnostic module is configured to receive current online data of the performance indicator from the CFB boiler via the current data source 402, and the process variables and the newly calibrated model of the performance indicator from the modeling unit 400. The performance diagnostic module 404 includes instructions for determining the modeled values ​​of the performance indicators by applying the current measured values ​​of the process variables to the calibrated multivariate model. In addition, the performance diagnostic module 404 is configured to compare the modeled value of each performance indicator with the corresponding measured value of the performance indicator and check for the presence of anomalies between the modeled value and the measured value. Based on the comparison results, one or more predetermined measures that can be taken are generated as diagnostic outputs 408.

[0243] By estimating the risk index of each KPI, it can be recognized that anomalies exist and remedial actions are required. The performance diagnosis module 404 may include instructions for implementing a method for estimating the risk index of a performance indicator, the method performing the following actions:

[0244] - Current data on performance indicators (KPIs) for measuring solid material recycling,

[0245] - Based on the current data of the boiler, do at least one of the following

[0246] i) Calculate the average value of the performance index;

[0247] ii) calculating the standard deviation of the measured performance indicator;

[0248] iii) calculating the difference between the maximum measured performance indicator value and the minimum measured performance indicator value;

[0249] iv) calculating the difference between the average performance indicator KPI and the measured performance indicator;

[0250] - Using the calculation results from i), ii), iii) and / or iv), prepare a risk index for the performance indicator KPI. Compare the calculation results from i), ii), iii) and / or iv) with the corresponding predefined limits to obtain a risk index for the mean value, standard deviation, difference between the maximum KPI value and the minimum KPI value and / or difference between the average KPI value and the measured KPI value. k The calculation of the deviation from the average KPI includes the average value divided by the KPI k All KPI measurements except the measurement results of

[0251] Preferably, in the method, also or alternatively

[0252] v) Calculate KPIs k(k=1,…,K) modeled values ​​and calculating the residual between the measured value of the performance indicator and the modeled value of the performance indicator. The result from step v) is advantageously also used to prepare a risk index, preferably such that the residual is compared with the corresponding predefined limit, thereby obtaining a sintering risk index for the KPI residual.

[0253] For example, the final risk index can be the maximum value among the above risk indexes. In this way, the prediction accuracy of the bed sintering index can still be improved.

[0254] The inventors have observed that in this way, the risk index generated provides an indication of conditions in the solid material circulation process in a circulating fluidized bed boiler that may lead to a boiler shutdown unless addressed, taking corrective action early enough that the need to shut down the boiler can be avoided.

[0255] Optionally, the control system includes a model history coefficient storage device 410 in which each calibrated model is stored. The performance diagnostic module 404 may include a model evaluation function that checks the newly created model and, if the newly created model is found to be incomplete, uses a model from the model history coefficient storage device 410 until a complete new model can be provided.

[0256] Figure 3 A circulating fluidized bed boiler 10 is schematically shown, which is provided with a fluidized bed heat exchanger 50 at one of its return paths 15 (only one is shown for clarity). It should be understood that Figure 3 The return path 15 shown in FIG. 1 can be considered as Figure 1 In the same CFB boiler disclosed in , this means that the CFB boiler may be provided with several return paths 15 , wherein more than one return path 15 is preferably provided with a fluidized bed heat exchanger 50 . Figure 3 It also relates to an application in which the CFB boiler comprises several return paths 15, all return paths 15 being provided with a fluidized bed heat exchanger 50. The method according to the invention is carried out in connection with all return paths 15 respectively.

[0257] The fluidized bed heat exchanger 50 is arranged to the return path 15 downstream of the ring seal 32 in the return channel 16. The solid material flows into the fluidized bed heat exchanger 50 through the ring seal 32, and at the fluidized bed heat exchanger 50, fluidizing air is introduced into the fluidized bed heat exchanger 50 through the grid 52 at the bottom of the fluidized bed heat exchanger 50 to form a bubbling bed of solid material. The fluidized bed heat exchanger 50 is provided with a lifting chamber 54, which has a corresponding inlet 54 for conveying air. The lifting chamber conveys the solid material from the fluidized bed heat exchanger 50 back to the combustion chamber 12 via a return pipe 55.

[0258] The fluidized bed heat exchanger 50 is provided with one or more heat exchange units 58, which are preferably connected to, for example, a steam cycle. These heat exchange units can be evaporators, steam superheaters and / or steam reheaters. These heat exchange units include heat transfer surfaces, such as one or more tube bundles inside the bubbling bed of solid material formed by the fluidized bed heat exchanger 50.

[0259] In a CFB boiler, solid material conveyed by the product gas to the separator 14 is separated from the gas, as depicted by the arrows in the figure. The second outlet 30 (which may also be referred to as the particle outlet of the separator 14) is connected to the lower part of the combustion chamber 12 via a return path 15 so that the separated solid material is returned to the combustion chamber 12. The return path 15 is provided with a so-called ring seal 32, which prevents a backflow from the combustion chamber 12 to the particle outlet and enables a controllable forward supply of the separated solid material in the return path 15. The operation of the ring seal is controlled by fluidizing air, which may be controllably supplied via the air inlet 23. Thus, the solid material circulation comprises causing the solid material to flow from the combustion chamber 12 to the solid material separator 14, and from the solid material separator 14 to the fluidized bed heat exchanger 50 via the return channel 16, and from the fluidized bed heat exchanger 50 back to the combustion chamber 12. When the fluidized bed heat exchanger 50 is operating, heat is transferred from the solid material to the steam flowing in the heat exchange unit 58 , which cools the solid material before it is introduced back into the combustion chamber 12 .

[0260] In order to monitor the solid material recycling process, according to Figure 3 The CFB boiler 10 of the embodiment includes a plurality of sensors for obtaining online data of performance indicators and process variables. When the online data is stored after the measurement time, it becomes historical data. To implement the method according to the present invention, at least the following sensors and measurement points are arranged to the CFB boiler:

[0261] a first pressure sensor 101 , which is arranged upstream of the ring seal 32 but downstream of the solid material separator, ie between the ring seal and the solid material separator 14 ;

[0262] A second pressure sensor 102 is arranged downstream of the ring seal 32 and between the ring seal 32 and the fluidized bed heat exchanger 50;

[0263] The purpose of the first and second pressure sensors is to determine the pressure difference provided by the ring seal 32 .

[0264] - a first temperature sensor 100 arranged in the ring seal 32;

[0265] - A second temperature sensor 103 arranged upstream of the ring seal 32; Figure 2 As shown in FIG. 1 , the second temperature sensor 103 is arranged at the first outlet 28 of the solid separator 14. Figure 2 In the sense of

[0266] - a first air flow rate sensor 105 for measuring the primary air flow rate through the grid 20 of the CFB boiler;

[0267] - A second air flow rate sensor 106 for measuring the secondary air flow rate;

[0268] The purpose of the first and second air flow rate sensors is to determine the aggregate air flow rate supplied to the CFB boiler. A plurality of third temperature sensors 104 connected to the combustion chamber 12 are arranged to determine the bed temperature in the combustion chamber 12;

[0269] a third air flow rate sensor 108 for measuring the air flow rate supplied to the fluidized bed heat exchanger 50;

[0270] a third pressure sensor 110 arranged upstream of the heat exchange unit 58 in the fluidized bed heat exchanger 50;

[0271] A fourth pressure sensor 112 arranged downstream of the heat exchange unit 58 in the fluidized bed heat exchanger 50

[0272] A third temperature sensor 114 arranged downstream of the heat exchange unit 58 in the fluidized bed heat exchanger 50 .

[0273] Figure 2 The control system 48 described in Figure 3 The CFB boiler 10 described in the above is similar to the CFB boiler 10 described in the above, but requires necessary modifications related to the data of the performance indicators and process variables. The actual accurate position of the sensor can be determined according to the situation. For example, in some cases, the third temperature sensor can be arranged between the lifting chamber 54 and the combustion chamber 12, because the temperature at a specific position represents the temperature of the solid material downstream of the heat exchange unit 58. Similarly, the temperature sensor 103 at the outlet 28 of the separator 14 can be positioned differently as long as it represents the temperature of the solid material at the upstream position of the ring seal 32.

[0274] When applied according to Figure 3 When the CFB boiler is operated, the control system 48 is involved in implementing a method for monitoring the solid material circulation process in the circulating fluidized bed boiler 10. The control system includes one or more computers and executable instructions (i.e., computer programs) that, when executed in the control system 48, implement the method in the circulating fluidized bed boiler 10. The method includes

[0275] a. Selecting the performance index of the solid material circulation process and the process variables for each performance index of the solid material circulation process,

[0276] b. Using the historical data of process variables and performance indicators of the solid material cycle process to calibrate the multivariable model for each performance indicator

[0277] c. Determine the modeled value of the performance indicator by applying the current measured value of the process variable to the multivariable model

[0278] d. Compare the modeled value of each performance indicator with the corresponding measured value of each performance indicator, and check for the presence of anomalies between the modeled value and the measured value.

[0279] The control system includes a performance modeling unit 400. The modeling unit 400 includes executable instructions that, when executed in the control system 48, calibrate the multivariable model for each performance indicator using historical data of predetermined process variables and performance indicators of the solid material recycling process to produce a calibrated multivariable model.

[0280] The performance modeling unit 400 has or is provided with access means, such as data transmission communication with a) performance indicators of the solid material circulation process obtained from the CFB boiler and b) a historical data source 401 of process variables for each performance indicator. The historical data is stored in a data medium, which serves as the historical data source 401, obtained by measuring predetermined process variables 101, 102, 103, ... 114 (see Figure 3 ) and storing the measured values ​​together with a time stamp, thus forming historical data of the process variable. Acquiring historical data involves measuring the values ​​of the performance indicators, respectively, storing the measured values ​​together with a time stamp, thus forming historical data of the performance indicators. The control system 48 includes a data filter unit 406, which is configured to filter out invalid process data, and thus the historical data includes data that has been subjected to a filtering process using a predetermined data filter. Therefore, the historical data is data describing the normal operating conditions of the CFB boiler 10. In combination Figure 2 The description of FIG. 1 describes the filter unit in more detail.

[0281] and Figure 3 The CFB boiler related historical data shown in the figure includes the following process variables and performance indicators:

[0282] - a pressure value upstream of the ring seal 32 but downstream of the solid material separator, ie between the ring seal and the solid material separator 14 (sensor 101 );

[0283] - pressure value downstream of the ring seal 32, between the ring seal 32 and the fluidized bed heat exchanger 50 (sensor 102);

[0284] - or alternatively, the pressure difference across the ring seal 32 (combined sensors 101 , 102 );

[0285] - Temperature in the ring seal 32 (sensor 100);

[0286] - Temperature upstream of the ring seal 32 (sensor 103);

[0287] - a pressure value upstream of the heat exchange unit 58 in the fluidized bed heat exchanger 50 (sensor 110);

[0288] - a pressure value downstream of the heat exchange unit 58 in the fluidized bed heat exchanger 50 (sensor 110);

[0289] - the temperature downstream of the heat exchange unit 58 in the fluidized bed heat exchanger 50 (sensor 114);

[0290] - the total air flow rate fed into the fluidized bed heat exchanger 50 (sensor 108);

[0291] - Total air flow rate fed into the CFB boiler (sensors 105, 106);

[0292] - Bed temperature in the combustion chamber 12 (sensor 104 ).

[0293] Performance indicators represent factors that describe the solid material circulation process and the state of the fluidized bed heat exchanger. Figure 3 In the case of the embodiment shown, the performance indicators are advantageously

[0294] i. The pressure difference of the ring seal in the return path, and

[0295] ii. Temperature in the ring seal during solid material circulation

[0296] iii. Pressure difference of fluidized bed heat exchanger,

[0297] iv. The temperature of the solid material downstream of the fluidized bed heat exchange unit.

[0298] The data in the historical data source 401 are used as input to the modeling unit 400, which is configured to prepare and / or calibrate a multivariate model assigned individually for each performance indicator (in this case, for both performance indicators). Thus, the performance modeling unit 400 provides a multivariate model for each performance indicator. The calibration can be repeated at predefined time intervals or periodically. This helps to keep the model realistic, reflecting possible changes caused by normal use of the CFB boiler, but also changes in fuel quality, environmental conditions (temperature, ambient humidity, ambient pressure changes), which may cause operating parameters to change over time. When an anomaly is detected in the process, the calibration can be blocked. In this way, it can be ensured that a problem that has just occurred in the bed material circulation will not contaminate the calibration and the model.

[0299] The model can be constructed by the modeling unit 400 using multivariate linear regression. In principle, the coefficients of the model are estimated using past input values ​​of the model (i.e., measured historical data). The model is then used to estimate the current situation by utilizing current online data and the estimated coefficients.

[0300] For example, in linear regression, the response variable is expected to be a linear combination of the process variables. Multiple linear regression can be used to model the relationship between multiple process variables and a performance indicator by fitting a linear equation to historical data.

[0301] exist Figure 3 In the case of the embodiment shown in , a multivariate model of the temperature of the solid material downstream of a fluidized bed heat exchanger unit (hereinafter, FBHX) with N observations is defined as follows:

[0302] y i =b0+b1x i,1 +b2x i,2 +b3x i,3 +b4x i,4 +b5x i,5 +ε i ,

[0303] in

[0304] y represents the value of the performance indicator,

[0305] x i,1 is the i-th pressure difference on the ring seal 32 (sensors 110, 112),

[0306] x i,2 is the ith temperature value in the ring seal 32 (sensor 100)

[0307] x i,3 is the i-th total air flow rate value supplied to the CFB boiler (sensors 105, 106)

[0308] x i,4 is the i-th bed temperature value in the combustion chamber 12 (sensor 104)

[0309] x i,5 is the value of the ith air flow rate supplied to the chamber of the fluidized bed heat exchanger 50 (sensor 108)

[0310] b0 is a constant, b1…b5 are the unknown KPI-specific coefficients to be estimated, and

[0311] ε includes the experimental error of the model.

[0312] exist Figure 3 In the case of the example shown in , a multivariate model for the pressure difference across a fluidized bed heat exchanger with N observations is defined as follows:

[0313] y i =b0+b1x i,1 +b2x i,2 +b3x i,3 +b4x i,4 +b5x i,5 +ε i ,

[0314] in

[0315] y represents the value of the performance indicator,

[0316] x i,1 is the i-th pressure difference on the ring seal 32 (sensors 110, 112),

[0317] x i,2 is the ith temperature value in the ring seal 32 (sensor 100)

[0318] x i,3 is the i-th total air flow rate value supplied to the CFB boiler (sensors 105, 106)

[0319] x i,4 is the i-th bed temperature value in the combustion chamber 12 (sensor 104)

[0320] x i,5 is the value of the ith air flow rate supplied to the chamber of the fluidized bed heat exchanger 50 (sensor 108)

[0321] b0 is a constant, b1…b5 are the unknown KPI-specific coefficients to be estimated, and

[0322] ε includes the experimental error of the model.

[0323] The fit is performed by minimizing the sum of squares of the vertical deviations from each data point to the line that best fits the observed data, that is, the optimal coefficient values ​​are obtained by minimizing the sum of squared errors.

[0324] The modeling unit 400 provides the required coefficients of the model, which are based on the available historical data, for modeling the performance indicators by applying the online data of the process variables to the model. During the operation of the control system 48 and the CFB boiler 10, the historical data including the data of the process variables and the performance indicators are continuously read and stored in the historical data source 401. The modeling unit 400 is configured to update or calibrate the model (i.e., the coefficients of the model) so that the model learns the latest conditions of the normal operation of the solid material circulation process.

[0325] A performance diagnostic module 404 is also provided in the control system 48, which is also applicable to CFB boilers provided with one or more fluidized bed heat exchangers. Figure 2 Related description or performance diagnostic modules are also available Figure 3 Embodiment of the invention.

[0326] Figure 4 Describe the basis Figure 3 Results obtained from a method for monitoring a solid material circulation process in a circulating fluidized bed boiler. Figure 4 Disclosed are online measurements provided by a third temperature sensor 114. The third temperature sensor is located in the fluidized bed heat exchanger below the heat exchange unit 58, close to the grid of the chamber, and therefore the curve M114 shows the temperature of the performance indicator, i.e. the temperature of the solid material downstream of the fluidized bed heat exchange unit. Figure 4 Another curve P114 shown in , plots the modeled value of the performance indicator when the current measured value of the process variable is applied to the multivariate model of the KPI. The horizontal axis shows time, where time zero is the actual shutdown time of the boiler. As can be seen in this graph, the modeled values ​​of the model show deviations from the measured values ​​a few hours before the process is too disturbed to recover, and no remedial action can prevent the shutdown. As can be clearly seen from this example, the model will indicate an impending problem more than 30 hours before the shutdown, which will be irreversible. The adverse condition can be observed early enough within a time window (shaded area), which is long enough and far enough in advance of the actual problem.

[0327] Figure 5A circulating fluidized bed boiler 10 is schematically depicted, which is provided with a fluidized bed heat exchanger 50 and a bypass path 56 at one of its return paths 15 (only one is shown for clarity), and the bypass path 56 connects the solid material return path 15 to the combustion chamber 12 at a position between the ring seal 32 and the fluidized bed heat exchanger 50. Therefore, the bypass path 56 is arranged to controllably convey 0-100% of the solid material in the return path 15 directly to the combustion chamber, while conveying the possible remaining part to the fluidized bed heat exchanger 50. This solid material circulation process includes two modes: a first mode (bypass mode), in which the method is applied to the circulation of solid materials directly from the ring seal 32 to the combustion chamber 12 of the CFB boiler (when there is solid material flowing through the bypass path); and a second mode, in which the method is applied to the circulation of solid materials from the ring seal 32 to the combustion chamber 12 of the CFB boiler via the fluidized bed heat exchanger 50 (when there is solid material flowing through the fluidized bed heat exchanger 50). Therefore, in terms of applying the method according to the invention, Figure 5 The embodiment shown in can be understood as Figure 1 and Figure 3 The embodiments shown in FIG. 1 are combined in a single solid material return path 15 .

[0328] It should also be understood that Figure 5 The return path 15 shown in FIG. 1 can be considered as Figure 1 or Figure 3 In the same CFB boiler disclosed in , this means that the CFB boiler may be provided with several return paths 15 with different arrangements, wherein more than one return path 15 is preferably provided with a fluidized bed heat exchanger 50 . Figure 5 It also relates to practical applications in which the CFB boiler comprises several return paths 15, all or some of which are provided with a fluidized bed heat exchanger 50 having a bypass path 55. The method according to the invention is carried out in connection with all return paths 15 respectively.

[0329] In addition to or as an alternative to having the bypass path 56, Figure 5 , a solid material discharge path 56' is disclosed, which is connected to the solid material return path 15 at a position between the ring seal 32 and the fluidized bed heat exchanger 50. If desired, the position of the discharge path 56' or its material extraction point can be different from that shown here. With the help of the solid material discharge path 56', 0-100% of the solid material flow can be removed from the solid material circulation process. The removed material portion can be later returned to the reactor 10 as such, or returned to the reactor 10 after the desired treatment of the solid material.

[0330] Figure 2 The control system 48 described in Figure 5The CFB boiler 10 described in the foregoing is also described with necessary modifications with respect to data regarding performance indicators and process variables.

[0331] An exemplary embodiment of calculating residual-based KPIs and risk indices for a case where a circulating fluidized bed boiler 10 is provided with a fluidized bed heat exchanger 50 at one of its return paths 15. The following steps are taken:

[0332] Create KPI models based on the pressure difference and temperature in the ring seal and the pressure difference and temperature in the fluidized bed heat exchange chamber

[0333] Compare the modeled value of the KPI with the measured value at the current time point (t). For example, the KPI for the modeled ring seal temperature can be calculated as follows:

[0334] KPI loop seal temp,modelled (t):=y t =b0+b1x t，1 +b2x t,2 +b3x t，3 +ε t

[0335] where b0 is a KPI-specific constant (solved for previously), and b0...b3 are known (solved for previously) KPI-specific coefficients, and

[0336] x t,1 is the tth temperature value upstream of the ring seal 32 (sensor 103)

[0337] x t,2 is the tth total air flow rate value supplied to the CFB boiler (sensors 105, 106)

[0338] x t,3 is the t-th bed temperature value in the combustion chamber 12 (sensor 104 ).

[0339] Compare the calculated deviations between the model output and the measured values ​​to obtain the residuals (KPI k,res (t), where k = 1 to K (K = number of KPIs) (e.g. modeling temperature - measured temperature in the ring seal, i.e. KPI loop seal temp,res (t) = KPI loop seal temp,modelled (t)-KPI loop seal temp,means (t)).

[0340] The residual limit for each KPI type is schematically shown in the following table:

[0341]

[0342] Where A, B, C and D describe predefined limit values.

[0343] The risk index for each KPI is calculated as follows:

[0344] r k =100x(|KPI k,res (t)-(l up,k +l o,k ) / 2|) / ((l up,k -l lo,k ) / 2)

[0345] where |.| is an absolute value, k = 1 to K (K = number of KPIs)

[0346] The overall risk index RI is calculated as follows:

[0347] RI=max(r k ),

[0348] where r k = single risk, and where k = 1 to K (K = number of KPIs).

[0349] As an example, let us assume that the temperature residual in the ring seal is

[0350] KPI loop seal temp,res (t) = KPI loop seal temp,modelled (t)-KPI loop seal temp,meas (t) = B up Then, using the above formula, we get the ring seal temperature risk index:

[0351] r loop seal temp =100×(|B up -(B up +B lo ) / 2|) / ((B up -B lo ) / 2).

[0352] If B up =B and B lo = -B, then r loop seal temp =100, and therefore the overall risk index is calculated using the above formula to obtain RI=max(r k )=100.

[0353] The case without the fluidized bed heat exchange chamber is similar to the above example, but the values ​​(KPI) related to the fluidized bed heat exchange chamber are omitted.

[0354] According to one aspect of the present invention, the overall risk index may be calculated using at least one of the following formulas: Maximum RI = max(r k ), average value RI = mean(r k), weighted average RI = Wmean(r k ) or median RI = median(r k ).

[0355] According to a preferred aspect of the present invention, the risk index for each KPI is limited to have a maximum value of 100 and a minimum value of 0, that is, k =[0,...,100]. Therefore, if KPI k The absolute value is greater than the lower limit (l lo,k ) or upper limit (l up,k ), then r k =100. Usually, if KPI k Does not belong to the interval [l lo,k ,l up,k ], then r k = 100. You can also write the condition as if 100x(|KPI k (t)-(I up，k +I lo，k ) / 2|) / (I up，k -I lo,k ) / 2)>100, then r k =100, otherwise r k =100x(|KPI k (t)-(l up,k +l lo,k ) / 2|) / ((l up,k -l lo,k ) / 2).

[0356] In the above example, the table shows that the absolute limit values ​​may be equal, however, the upper and lower limits may be defined in different ways so that the absolute values ​​of the upper and lower limits are different for the corresponding KPI. However, it should be noted that lo,k <l up,k .

[0357] The above examples are for clarity purposes only and are not meant to limit the scope of the claimed invention. In addition, instead of residuals, other mathematical comparisons can be performed, for example, calculating the ratio between corresponding values.

[0358] Although the present invention has been described herein by way of example in conjunction with what is currently considered to be the most preferred embodiment, it will be apparent to those skilled in the art that, as technology advances, the basic concept of the present invention may be implemented in a variety of ways. The details mentioned in conjunction with any of the above embodiments may be used in conjunction with another embodiment when such a combination is technically feasible.

[0359] Parts List Circulating Fluidized Bed Boiler 10 Combustion Chamber 12

[0360] Solid material separator 14 Solid material return path 15 Solid material return channel 16 Wind box 18

[0361] Grid 20

[0362] Air inlet 21

[0363] Ring seal fluidization air inlet 23 air source 24

[0364] Fuel inlet 22

[0365] Pipeline 26

[0366] First Exit 28

[0367] Second exit 30

[0368] Ring seal 32

[0369] Return 40

[0370] Superheater and optional reheater 42 Economizer 44

[0371] Air preheater 46

[0372] Control system 48

[0373] Fluidized bed heat exchanger 50 Fluidized bed heat exchanger grid 52 Rising chamber 54

[0374] Return pipe 55

[0375] Bypass route 56

[0376] Heat exchange unit 58

[0377] First temperature sensor 100

[0378] First pressure sensor 101

[0379] Second pressure sensor 102

[0380] Second temperature sensor 103

[0381] The third temperature sensor 104 The first air flow rate sensor 105 The second air flow rate sensor 106 The third air flow rate sensor 108 The fourth air flow rate sensor 109

[0382] The third pressure sensor 110

[0383] Fourth pressure sensor 112

[0384] Third temperature sensor 114 performance modeling unit 400

[0385] Historical Data Source 401

[0386] Current data source 402

[0387] Performance diagnostic module 404 data filter unit 406 diagnostic output 408

[0388] Model history coefficient storage device 410.

Claims

1. A method for monitoring a solid material circulation process in a circulating fluidized bed reactor (10), the reactor (10) comprising a reaction chamber (12), at least one solid material separator (14), a return path (15) between the at least one solid material separator (14) and the reaction chamber (12), and in the method, the solid material circulation process comprises arranging the solid material to be entrained by the gas flow in the reaction chamber (12), and further entrained from the reaction chamber (12) to the at least one solid material separator (14) and conveying the solid material from the solid material separator (14) to the reaction chamber (12) via the return path (15), characterized in that The method comprises at least the following steps: a. selecting a process variable of the solid material circulation process in the return path (15), and selecting a performance indicator of the solid material circulation process from the selected process variables for each performance indicator of the solid material circulation process, b. using the historical data of the process variables and the performance indicators of the solid material circulation process, creating a multivariate model for each performance indicator, c. determining a modeled value of the performance indicator by applying the current measured value of the process variable to the multivariable model, d. Compare the modeled value of each performance indicator with the corresponding measured value of each performance indicator, and check for the presence of anomalies between the modeled value and the measured value.

2. The method according to claim 1, wherein the solid material circulation process comprises transferring the solid material from the separator (14) directly to the reaction chamber (12) via a ring seal, characterized in that At least i. The pressure difference of the ring seal (32) in the return path (15) ii. The temperature in the ring seal (32) in the return path (15) during the circulation of solid material is selected as a performance indicator for the process in step a).

3. The method according to claim 1, wherein the solid material circulation process comprises transferring the solid material from the separator (14) to the reaction chamber (12) via a fluidized bed heat exchanger (50), characterized in that At least i. The pressure difference of the ring seal in the return path (15) ii. The temperature in the ring seal (32) in the return path during the solid material circulation iii. The pressure difference of the fluidized bed heat exchanger (50), iv. the temperature of the solid material downstream of the fluidized bed heat exchange unit (58) in the fluidized bed heat exchanger (50), is selected as a performance indicator of the process in step a).

4. The method according to claim 2, characterized in that i. Performance indicator - process variables of the pressure difference of the ring seal in the return path (15) include: the total reaction gas flow rate supplied to the reactor (10), the temperature of the product gas upstream of the ring seal (32), and the bed temperature in the reaction chamber (12), ii. Performance Indicator - Process variables of the temperature in the ring seal (32) in the return path (15) in the solid material circulation include: the total reaction gas flow rate supplied to the reactor (10), the temperature of the product gas upstream of the ring seal (32), and the bed temperature in the reaction chamber (12).

5. The method according to claim 3, characterized in that i. Performance Indicator - The process variables of the pressure difference of the ring seal in the return path (15) include: the total reaction gas flow rate supplied to the reactor (10), the temperature of the product gas upstream of the ring seal (32), the bed temperature in the reaction chamber (12), ii. Performance indicator - the temperature in the ring seal (32) in the return path (15) in the solid material circulation. The process variables include: the total reaction gas flow rate supplied to the reactor (10), the temperature of the product gas upstream of the ring seal (32), the bed temperature in the reaction chamber (12), iii. The process variables of the performance indicator - pressure difference of the fluidized bed heat exchanger include: the total reaction gas flow rate supplied to the reactor (10), the temperature in the ring seal (32) in the return path (15) in the solid circulation, the pressure difference of the ring seal (32), the gas flow rate to the fluidized bed heat exchanger (50), and the bed temperature in the reaction chamber (12). iv. The process variables of performance indicator - temperature of fluidized bed heat exchanger include: the total reaction gas flow rate supplied to the reactor (10), the temperature in the ring seal (32) in the return path (15), the pressure difference of the ring seal, the gas flow rate to the fluidized bed heat exchanger (50), and the bed temperature in the reaction chamber (12).

6. The method according to claim 4 or 5, characterized in that The total reaction gas flow rate is the total flow rate of the gas flow entering the reaction chamber (12).

7. The method according to claim 3, characterized in that The bed temperature is an average bed temperature in the reaction chamber (12), which is calculated based on at least two measurement points in the reaction chamber (12), at least one of which is at a grid height of the chamber (12).

8. The method according to claim 1, 2 or 3, characterized in that Creating the multivariate model involves - measuring the value of a predetermined process variable, storing said measured value together with a time stamp, thus forming historical data of the process variable, - measuring the value of the performance indicator, storing said measured value together with a time stamp, thus forming historical data of the performance indicator, - Select valid historical data using pre-determined data filters.

9. The method according to claim 8, characterized in that The data filter is configured to approve data older than a preset quarantine time.

10. The method according to claim 9, characterized in that The data filter is configured to approve data older than two weeks.

11. The method according to claim 8 or 9, characterized in that The data filter is configured to approve data that is no older than two months.

12. The method according to claim 8, characterized in that The data filter is configured to filter out from the historical data any data from a shutdown situation and / or from any abnormal operation based on predefined limits of input variables or external information of abnormal operation.

13. The method according to claim 1 or 8, characterized in that The multivariate model is a multivariate linear regression as follows having a first number (N) of measured observations for each process variable of the solid material cycle process and a second number (P) of different process variables y i =b0+b1x i，1 +b2x i，2 +...b P x i，P +e i where i=1,2,...N And the method comprises reading y i 、x i1 、x i2 ,...x ip Historical data, where y = performance indicator, and x i,1 、x i,2 ,...x i,p is the process variable, And solve the constant b0 and factors b1, b2, ...b p And the fit is performed by minimizing the sum of the squares of the vertical deviations from each data point to the line of best fit to the historical data.

14. The method according to claim 13, characterized in that The first number N of measurement observations is at least 10 times greater than the second number (P) of different process variables.

15. The method according to claim 1 or 14, characterized in that The multivariable pattern is updated after a period of time either triggered by the elapse of a constant predetermined time interval or by a trigger input.

16. The method according to claim 1, characterized in that The risk index for each performance indicator is calculated using the information on the presence of anomalies.

17. The method according to claim 16, characterized in that A risk index for each performance indicator is calculated using anomalies between the modeled values ​​and the measured values.

18. A method according to any one of the preceding claims, when the reactor (10) includes at least a first return path (15) between a first solid material separator (14) and the reaction chamber (12) and a second return path (15) between a second solid material separator (14) and the reaction chamber (12), the method is characterized in that the method is implemented with respect to the solid material circulation process in the first return path (15), and the method is implemented with respect to the solid material circulation process in the second return path (15), respectively.

19. A control system (48) for monitoring the circulation of solid material in a circulating fluidized bed reactor (10) between a reaction chamber (12) and at least one solid material separator (14) and reaching the reaction chamber (12) via a return path (15) including an annular seal, characterized in that The control system (48) includes a performance modeling unit (400) comprising means for accessing performance indicators of the solid material circulation process in the return path (15) and source historical data (401) of process variables for each performance indicator, -Multivariate models for each performance indicator - executable instructions which, when executed in the control system, o updating the multivariable model for each performance indicator using historical data of predetermined process variables and performance indicators of the solid material recycling process to produce a calibrated multivariable model, A performance diagnosis module (404), the performance diagnosis module (404) comprising - input means for receiving measurement data of process variables and performance indicators of said solid material circulation process, - executable instructions which, when executed in the control system, o Determining a modeled value for the performance indicator by applying the current measured value of the process variable to the calibrated multivariable model o Comparing the modeled value of each performance indicator with the corresponding measured value of the performance indicator and checking for the presence of anomalies between the modeled value and the measured value.

20. The control system for monitoring the solid material circulation process in a circulating fluidized bed reactor (10) according to claim 19, characterized in that The invention comprises measuring sensors for at least the following process variables: a pressure sensor (101, 102) for measuring the pressure drop in the ring seal; a product gas temperature sensor (103) downstream of the separator (14) and means for determining the total gas flow rate to the reactor (10) and the bed temperature in the reaction chamber (12) of the reactor (10).

21. A control system for monitoring the circulation of solid material in a circulating fluidized bed reactor (10) between a reaction chamber (12) and at least one solid material separator (14) and via a fluidized bed heat exchanger (50) in the return path (15) to the reaction chamber (12) according to claim 21, characterized in that The invention comprises measuring sensors for at least the following process variables: a pressure sensor (101, 102) for measuring the pressure drop in the ring seal; a temperature sensor (103) in the ring seal (31); a product gas temperature sensor (103) downstream of the separator (14); a pressure sensor (110, 112) for measuring the pressure drop in the fluidized bed heat exchanger; a temperature sensor (114) for measuring the temperature of the solid material downstream of the heat exchange unit (58) in the fluidized bed heat exchanger (50); and means for determining the total gas flow rate to the reactor (10) and the bed temperature in the reaction chamber (12) of the reactor (10).

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