Method and control system for monitoring the process of circulation of solid materials in a circulating fluidized bed reactor

Abstract

The invention relates to a method for monitoring a solid material circulation process in a circulating fluidized bed reactor, which at least comprises the steps of: selecting process variables of the solid material circulation process in the return path of the solid material and selecting performance indicators of the process from among the selected process variables for each performance indicator of the process; creating a multivariate model for each performance indicator using historical data of the process variables and the performance indicators; applying the current measured values of the process variables to the multivariate model to determine the modeled values of the performance indicators; comparing the modeled values of each performance indicator with the measured values of each performance indicator to check for the presence of anomalies between the modeled values and the measured values. As a result of this method, problems that may occur in the circulation of solid materials can be effectively predicted, so that corrective measures can be taken early enough to keep the process operable. The invention also relates to a control system for monitoring the solid material circulation process in a circulating fluidized bed reactor.

Description

Technical Field

[0001]

[01] The present invention relates to a method for monitoring the process of circulation of solid materials in a circulating fluidized bed reactor as described in the preamble of claim 1.

[0002]

[02] The present invention relates to a control system for monitoring the process of circulation of solid materials in a circulating fluidized bed reactor as described in the preamble of the second independent claim.

Background Art

[0003]

[03] In a circulating fluidized bed reactor, fine solid materials are utilized in the process by fluidizing the solid materials to such an extent that a significant portion of the materials is drawn from the reaction chamber into at least one solid material separator, and a part of the solid materials separated from the gas from the solid material separator can be led to a fluidized bed heat exchanger and circulated back from the fluidized bed heat exchanger to the combustion chamber. Such a CFB reactor is well applicable for generating electric power by combustion of fuel in the CFB reactor for steam generation, in which case the CFB reactor is usually referred to as a CFB boiler. Similarly, it is also known to use a CFB reactor for generating product gas such as gaseous fuel, and as a result, a reaction is carried out in the CFB reactor. When generating gaseous fuel from solid fuel, the CFB reactor is usually referred to as a CFB gasifier.

[0004]

[04] Difficult fuels may cause particle agglomeration in the fluidized bed material, which may further lead to more serious sintering of the solid materials and ultimately blockage in the solid return system and shutdown of the reactor if corrective procedures are not initiated in time. For example, due to continuously varying fuel quality, it may be impossible for an operator to recognize sintering by following conventional basic operating routines.

[0005]

[05] U.S. Patent No. 8,292,977 discloses a system for controlling the circulation rate of particles in a circulating fluidized bed furnace, where the particles are circulated between a fluidized bed combustion furnace for heating the particles and a fluidized bed gasification furnace for gasifying the raw material through heating of the raw material by the heated high-temperature particles. The control is based on the measurement of the pressure in the fluidized bed gasification furnace and the control of the exhaust gas rate from the fluidized bed gasification furnace.

[0006]

[06] Japanese Patent No. 4,254,004 discloses the control of the fluidization rate based on the estimation of external circulating solids in a circulating fluidized bed boiler. This estimation is based on the measurement of 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 anti-superheat water.

[0007]

[07] Japanese Patent No. 4,443,481 relates to a system for diagnosing the clogging of a fluid medium, comprising a plurality of differential pressure gauges for measuring the differential pressure at a predetermined location in the fluid medium circulation path and a plurality of thermometers for measuring the temperature at a predetermined location in the fluid medium circulation path, and providing determination result display means for displaying the fact that the fluid medium is clogged and the location where the fluid medium is clogged when the determination means determines that the fluid medium is clogged.

[0008]

[08] Even if a circulating fluidized bed (CFB) reactor has advantages over other combustion technologies, the problem of agglomeration, particularly regarding solid materials in CFB technology, is a concern because it can lead to unplanned shutdowns of the plant.

[0009]

[09] An object of the present invention is to provide a method for monitoring and a method for controlling the process of circulation of solid materials in a circulating fluidized bed reactor, in which unintended shutdowns can be avoided or at least minimized.

Summary of the Invention

[0010]

[0010] The object of the present invention can be achieved substantially as disclosed in the independent claims and other claims that describe further details of different embodiments of the present invention.

[0011]

[0011] According to the present invention, there is provided a method for monitoring the process of circulation of solid materials in a circulating fluidized bed reactor, the reactor comprising a reaction chamber, at least one solid material separator, and a return path between the at least one solid material separator and the reaction chamber. In this method, the process of circulation of solid materials comprises arranging the solid materials to be drawn in by a gas flow in the reaction chamber and further drawn from the reaction chamber into at least one solid material separator, and sending the solid materials from the solid material separator to the reaction chamber via the return path. The method comprises at least the following steps. a. Selecting a process variable of the process of circulation of solid materials in the return path, and selecting a performance index of the process of circulation of solid materials from among the selected process variables for each performance index of the process of circulation of solid materials; b. Using historical data of the process variables and performance indices of the process of circulation of solid materials to create a multivariate model for each performance index; c. Determining a modeled value of the performance index by applying a currently measured value of the process variable to the multivariate model; d. Comparing the modeled value of each performance index with the respective measured value of each performance index, and checking for the presence of an anomaly between the modeled value and the measured value.

[0012]

[0012] When the modeled value of a certain performance index is determined by using the online value process variable and the modeled value of the performance index is compared with the online value of each performance index, the method provides the effect that possible problems such as the risk of bed quality related and / or sintering of bed materials, and / or the risk of potential bed material blockage in the circulation of solid materials can be effectively predicted so that corrective measures can be taken early enough to keep the process operable.

[0013]

[0013] According to a preferred embodiment of the present invention, the method comprises the combustion of fuel in a circulating fluidized bed reactor, i.e., in a circulating fluidized bed boiler. Thus, according to a preferred embodiment of the present invention, the reaction chamber is a combustion chamber.

[0014]

[0014] According to another embodiment of the present invention, the method comprises producing a gaseous fuel by converting a combustible substance into a gaseous fuel in a circulating fluidized bed reactor, i.e., in a circulating fluidized bed gasifier.

[0015]

[0015] According to one embodiment of the present invention, the method may include, in combination with any one or more other steps of the method, indicating to the operator possible corrective measures to be taken to control the situation in a direction to reduce the tendency of solid materials to agglomerate, the corrective measures including at least one of the following. · Changing the fuel mixture by reducing the proportion of fuel that is prone to forming aggregates, · Introducing an additive such as clay (e.g., kaolin), or increasing the amount of such an additive, to raise the agglomeration temperature of the bed, and / or · Reducing the load of the reactor, and / or first reducing the load and then increasing the load to also reduce the agglomeration tendency, · Increasing the supply of make-up materials such as sand to the reaction chamber or the fluidized bed heat exchanger, · Discharging bottom ash from the reaction chamber, or increasing the discharge rate of bottom ash, to remove agglomerates from the reaction chamber, · Solid material removal from the return path that also enables removal of the agglomerated bed material.

[0016]

[0016] According to one embodiment of the present invention, the comparison between the modeled value of the performance indicator in step d above and the respective measured value of each performance indicator can be based on at least one of the following: difference, absolute value of the difference, or ratio.

[0017] According to one aspect of the present invention, the process of circulating the solid material comprises directly sending the solid material from the separator to the reaction chamber via a loop seal, with at least i. the pressure difference of the loop seal in the return path, and ii. the temperature in the loop seal in the return path of the circulation of the solid material are selected as performance indicators of the process of circulating the solid material.

[0018]

[0018] This aspect relates to an embodiment of the present invention in which the CFB reactor comprises a loop seal in the return path, and the selected performance indicators provide an efficient method for monitoring the process of circulating the solid material.

[0019] According to one aspect of the present invention, the process of circulating the solid material comprises directly sending the solid material from the separator to the reaction chamber via a return path, with at least i. the pressure difference in the return path, and ii. the temperature in the return path of the circulation of the solid material are selected as performance indicators of the process of circulating the solid material.

[0020]

[0020] This aspect relates to an embodiment of the present invention in which the return path of the CFB reactor does not comprise a loop seal, or the solid material is led from a position upstream of the loop seal to the reaction chamber.

[0021] According to one aspect of the present invention, the process of circulating the solid material comprises sending the solid material from the separator to the reaction chamber via a fluidized bed heat exchanger, with at least i. the pressure difference of the loop seal in the return path, and ii. the temperature in the loop seal in the return path of the circulation of the solid material, and iii. the pressure difference of the fluidized bed heat exchanger, and iv. the temperature of the solid material downstream of the heat exchange unit of the fluidized bed heat exchanger are selected as performance indicators of the process of circulating the solid material.

[0022]

[0022] This aspect relates to an embodiment of the present invention where the selected performance metric covers a CFB reactor having a loop seal and a fluidized bed heat exchanger in the return path. The selected performance metric provides an efficient way to monitor the process of solid material circulation at several important locations in the process.

[0023]

[0023] 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 of the fluidized bed heat exchanger. According to another aspect of the present invention, the temperature of the solid in the fluidized bed heat exchanger is measured above the fluidization nozzles at the bottom of the fluidized bed. 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 of the fluidized bed heat exchanger. Stated yet another way, the temperature of the solid material downstream of the fluidized bed heat exchange unit can be measured below the heat exchanger tubes of the fluidized bed heat exchanger and above the fluidization nozzles. The fluidized bed heat exchange unit may be optionally selected and can be, for example, an evaporator, a superheater, or a reheater, to name a few.

[0024]

[0024] According to one aspect of the present invention, the process of solid material circulation comprises directly sending the solid material from the separator through the loop seal to the reaction chamber, at least, i. the pressure difference across the loop seal in the return path, and ii. the temperature within the loop seal in the return path of the solid material circulation are selected as performance metrics for the process of solid material circulation, i. The process variables of the performance metric of the pressure difference across the loop seal in the return path include the total reaction gas flow rate supplied into the reactor, the product gas temperature upstream of the loop seal, and the bed temperature within the reaction chamber, ii. The process variables of the performance metric of the temperature within the loop seal in the solid material circulation include the total reaction gas flow rate supplied into the reactor, the temperature of the product gas upstream of the loop seal, and the bed temperature within the reaction chamber.

[0025]

[0025] According to one aspect of the present invention, in the case of a circulating fluidized bed boiler, the generated gas can be referred to as flue gas containing the products of the combustion reaction.

[0026]

[0026] 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 can be supplied to the reaction chamber so as to generate a generated gas mainly composed of carbon monoxide CO, hydrogen H2, and hydrocarbons C x H y H. The generated gas of the circulating fluidized bed gasifier can be referred to as synthesis gas.

[0027]

[0027] According to one aspect of the present invention, the process of circulating the solid material includes directly sending the solid material from the separator to the reaction chamber through the loop seal, and at least, i. the pressure difference of the loop seal in the return path, and ii. the temperature in the loop seal in the return path of the circulation of the solid material are selected as the performance indicators of the process of circulating the solid material, i. The process variables of the performance indicator of the pressure difference of the loop seal in the return path include the total combustion gas flow rate supplied into the reactor, the flue gas temperature upstream of the loop seal, and the bed temperature in the reaction chamber, ii. The process variables of the performance indicator of the temperature in the loop seal in the circulation of the solid material include the total combustion gas flow rate supplied into the reactor, the temperature of the flue gas upstream of the loop seal, and the bed temperature in the reaction chamber.

[0028]

[0028] According to one aspect of the present invention, the reaction gas is air. According to one aspect of the present invention, the reaction gas is air or a mixture of air and recirculated flue gas. According to one aspect of the present invention, the reaction gas is pure oxygen. According to one aspect of the present invention, the reaction gas is a mixture of oxygen and recirculated generated gas. According to one aspect of the present invention, in the case of a circulating fluidized bed boiler, the reaction gas can be referred to as combustion gas.

[0029]

[0029] According to one aspect of the present invention, the method comprises gasification of fuel in a CFB reactor, and the process of circulating the solid material comprises directly sending the solid material from the separator to the reaction chamber via a loop seal, at least i. the pressure difference of the loop seal in the return path, and ii. the temperature in the loop seal in the return path of the circulation of the solid material are selected as performance indicators of the process of circulating the solid material, i. The process variables of the performance indicator of the pressure difference of the loop seal in the return path include the total gas flow rate supplied into the reactor, the temperature of the product gas upstream of the loop seal, and the bed temperature in the reaction chamber, ii. The process variables of the performance indicator of the temperature in the loop seal in the circulation of the solid material include the total gas flow rate supplied into the reactor, the temperature of the product gas upstream of the loop seal, and the bed temperature in the reaction chamber. According to one embodiment, the circulating fluidized bed reactor is a circulating fluidized bed gasifier, and the fluidizing gas comprises at least one of the following: an inert gas, steam, oxygen, or a mixture thereof.

[0030]

[0030] According to one aspect of the present invention, the process of circulating the solid material comprises sending the solid material from the separator to the reaction chamber via a fluidized bed heat exchanger, at least i. the pressure difference of the loop seal in the return path, and ii. the temperature in the loop seal in the return path of the circulation of the solid material, and iii. the pressure difference of the fluidized bed heat exchanger, and iv. the temperature of the solid material downstream of the fluidized bed heat exchange unit are selected as performance indicators of the process in the steps of the process of circulating the solid material, i. The process variables of the performance indicator of the pressure difference of the loop seal in the return path include the total reaction gas flow rate supplied into the reactor, the temperature of the product gas upstream of the loop seal, and the bed temperature in the reaction chamber, ii. The process variables of the performance indicator of the temperature in the loop seal in the circulation of the solid material include the total reaction gas flow rate supplied into the reactor, the temperature of the product gas upstream of the loop seal, and the bed temperature in the reaction chamber. iii. The process variables of the performance index of the pressure difference of the fluidized bed heat exchanger include the total reaction gas flow rate supplied into the reactor, the temperature in the loop seal in the return path of the circulation of the solid material, the pressure difference of the loop seal, the gas flow rate to the fluidized bed heat exchanger, and the bed temperature in the reaction chamber. iv. The process variables of the performance index of the temperature of the fluidized bed heat exchanger include the total reaction gas flow rate supplied into the reactor, the temperature in the loop seal, the pressure difference of the loop seal, the gas flow rate to the fluidized bed heat exchanger, and the bed temperature in the reaction chamber.

[0031]

[0031] According to one aspect of the present invention, the total reaction gas flow rate is the total flow rate of the gas flow into the reaction chamber of the CFB reactor.

[0032]

[0032] According to one embodiment where the method includes the combustion of fuel in the presence of air, the total reaction gas flow rate is the total flow rate of the air flow into the reaction chamber of the CFB reactor.

[0033]

[0033] According to one embodiment where the method includes the combustion of fuel in the presence of air, the total air flow rate is the flow rate including the primary air flow supplied into the reaction chamber.

[0034]

[0034] According to one embodiment where the method includes the combustion of fuel in the presence of air, the total air flow rate is the flow rate including the primary air flow and the secondary air flow supplied into the reaction chamber.

[0035]

[0035] According to one embodiment where the method includes the combustion of fuel in the presence of air, the total air flow rate is the flow rate including the primary air flow, the secondary air flow, and the tertiary air flow supplied into the reaction chamber.

[0036]

[0036] According to one embodiment where the method includes the combustion of fuel in the presence of air, the total air flow rate is the flow rate including the primary air flow and the secondary air flow supplied into the reaction chamber and the air supplied into the fluidized bed heat exchanger.

[0037] According to one embodiment where the method comprises the combustion of fuel in the presence of air, the total air flow rate is the total flow rate of the air streams into the reaction chamber and into the fluidized bed heat exchanger.

[0038] According to one embodiment where the method comprises the combustion of fuel in the presence of air, the total air flow rate is the flow rate comprising the primary air flow and the secondary air flow supplied into the reaction chamber, into the fluidized bed heat exchanger, and into the loop seal.

[0039] According to one embodiment where the method comprises the combustion of fuel in the presence of air, the total air flow rate is the total flow rate of the air streams into the reaction chamber, into the fluidized bed heat exchanger, and into the loop seal.

[0040] According to one aspect of the present invention, the process of the circulation of the solid material comprises sending the solid material from the separator through the fluidized bed heat exchanger to the reaction chamber, with at least i. the pressure difference of the loop seal in the return path, and ii. the temperature in the loop seal in the return path of the circulation of the solid material, and iii. the pressure difference of the fluidized bed heat exchanger, and iv. the temperature of the solid material downstream of the fluidized bed heat exchange unit being selected as performance indicators of the process in the steps of the process of the circulation of the solid material, i. the process variables of the performance indicator of the pressure difference of the loop seal in the return path comprise the total combustion gas flow rate supplied into the reactor, the temperature of the product gas upstream of the loop seal, and the bed temperature in the reaction chamber, ii. the process variables of the performance indicator of the temperature in the loop seal in the circulation of the solid material comprise the total combustion gas flow rate supplied into the reactor, the temperature of the product gas upstream of the loop seal, and the bed temperature in the reaction chamber, iii. the process variables of the performance indicator of the pressure difference of the fluidized bed heat exchanger comprise the total combustion gas flow rate supplied into the reactor, the temperature in the loop seal in the return path of the circulation of the solid material, the pressure difference of the loop seal, the combustion gas flow rate to the fluidized bed heat exchanger, and the bed temperature in the reaction chamber, iv. The process variables of the performance index of the fluidized bed heat exchanger include the total combustion gas flow rate supplied into the reactor, the temperature inside the loop seal, the pressure difference of the loop seal, the combustion gas flow rate to the fluidized bed heat exchanger, and the bed temperature inside the reaction chamber.

[0041]

[0041] According to one aspect of the present invention, the total combustion gas flow rate is the total flow rate of the combustion gas flow into the reaction chamber of the CFB reactor.

[0042]

[0042] According to one aspect of the present invention, the total combustion gas flow rate is the flow rate including the primary combustion gas flow supplied into the reaction chamber.

[0043]

[0043] According to a preferred aspect of the present invention, the total combustion gas flow rate is the flow rate including the primary combustion gas flow and the secondary combustion gas flow supplied into the reaction chamber.

[0044]

[0044] According to another preferred aspect of the present invention, the total combustion gas flow rate is the flow rate including the primary combustion gas flow, the secondary combustion gas flow, and the tertiary combustion gas flow supplied into the reaction chamber.

[0045]

[0045] According to one aspect of the present invention, the combustion gas is air and recycled product gas. According to one aspect of the present invention, the combustion gas is oxygen and recycled product gas. According to one aspect of the present invention, the combustion gas is primary air and recycled product gas. According to one aspect of the present invention, the combustion gas is oxygen and recycled product gas.

[0046]

[0046] According to one aspect of the present invention, the bed temperature is the average bed temperature inside the reaction chamber, which is calculated from at least two measurement points inside the reaction chamber, and at least one of the measurement points is at the grid level of the chamber.

[0047]

[0047] According to one aspect of the present invention, creating a multivariable model involves · measuring the values of predetermined process variables, storing the measured values together with time stamps, thereby forming historical data of the process variables, and ·Measure the value of a performance metric, store the measured value together with a timestamp, thereby forming historical data of the performance metric, and ·Select valid historical data using a predetermined data filter, and comprise.

[0048]

[0048] According to one aspect of the present invention, creating a multivariable model comprises ·Measure the value of a predetermined process variable, store the measured value together with a timestamp, thereby forming historical data of the process variable, and ·Measure the value of a performance metric, store the measured value together with a timestamp, thereby forming historical data of the performance metric, and ·Select valid historical data using a predetermined data filter, and ·Update the multivariable model, and comprise.

[0049]

[0049] According to one aspect of the present invention, the data filter is configured to approve data older than a preset quarantine time. Advantageously, this ensures that the model is not taught potential abnormal operating values caused, for example, by the onset of agglomeration of solid materials within a loop seal. In other words, data related to the problem is not used in model training.

[0050]

[0050] According to one aspect of the present invention, the data filter is configured to approve data older than two weeks.

[0051]

[0051] According to one aspect of the present invention, the data filter is configured to approve data not older than two months.

[0052]

[0052] According to one aspect of the present invention, the data filter is configured to filter out any data from shutdown situations and / or any abnormal operations from historical data based on predetermined limits of input variables or external information on abnormal operations.

[0053] According to one aspect of the present invention, the method comprises at least the following steps. a. Selecting process variables of the process of the circulation of the solid material in the return path, and selecting performance indicators of the process of the circulation of the solid material from among the selected process variables for each performance indicator of the process of the circulation of the solid material; b. Using historical data of the process variables and performance indicators of the process of the circulation of the solid material to create a multivariate model for each performance indicator; The multivariate model is a multivariate linear regression having measured observed values of each of the first number (N) of process variables and different process variables of the process of the circulation of the solid material of the second number (P). y i =b 0 +b 1 x i,1 +b 2 x i,2 +...b P x i,P +ε i where i = 1, 2,... N, The method reads historical data of y = performance indicator and x i,1 , x i,2 ,..., x i,p which are process variables, and i , x i,1 , x i,2 ,..., x i,p solves for the constants b and factors b 0 , b 1 ,... b 2 ,... b P and performs fitting by minimizing the sum of the squares of the vertical deviations from each data point to the line that best fits the historical data. c. Determining a modeled value of the performance indicator by applying the currently measured values of the process variables to the multivariate model. ​d. Comparing the modeled values of each performance index with the respective measured values of each performance index, and checking for the presence of anomalies between the modeled values and the measured values.

[0054]

[0054] According to one aspect of the present invention, the method comprises at least the following steps. a. Selecting process variables of the process of the circulation of the solid material in the return path, and selecting performance indices of the process of the circulation of the solid material from among the selected process variables for each performance index of the process of the circulation of the solid material. b. Using historical data of the process variables and performance indices of the process of the circulation of the solid material to create a multivariate model for each performance index. The multivariate model is a multivariate linear regression having the measured observed values of each of the first number (N) of process variables and different process variables of the process of the circulation of the solid material of the second number (P). y i =b 0 +b 1 x i,1 +b 2 x i,2 +...b P x i,P +ε i However, i = 1, 2,... N, The method is such that y = performance index and x i,1 ,x i,2 ,...,x i,p are process variables, where y i ,x i,1 ,x i,2 ,...,x i,p reading the historical data of, constant b 0 and factor b 1 ,b 2 ,...b P solving, performing fitting by minimizing the sum of the squares of the vertical deviations from each data point to the line that best fits the historical data. Here, the steps of creating a multivariable model include measuring the values of predetermined process variables, storing the measured values together with time stamps, thereby forming historical data of the process variables, measuring the values of performance indicators, storing the measured values together with time stamps, thereby forming historical data of the performance indicators, selecting valid historical data using a predetermined data filter, and updating the multivariable model. c. Determining a modeled value of a performance indicator by applying a currently measured value of a process variable to the multivariable model; d. Comparing the modeled value of each performance indicator with the respective measured value of each performance indicator and examining for the presence of an anomaly between the modeled value and the measured value.

[0055]

[0055] According to one aspect of the present invention, the first number N of measured observed values is at least 10 times the second number P of different process variables.

[0056]

[0056] According to one aspect of the present invention, the multivariable mode is updated after a period triggered by the elapse of a certain predetermined time interval or by a trigger input.

[0057]

[0057] According to one aspect of the present invention, the risk index of each performance indicator is calculated using information on the presence of an anomaly.

[0058]

[0058] According to one aspect of the present invention, the risk index of each performance indicator is calculated using the anomaly between the modeled value and the measured value.

[0059]

[0059] According to one aspect of the present invention, the reactor includes at least a first return path, a first solid material separator and a reaction chamber, and a second return path between the second solid material separator and the reaction chamber. The method for the process of circulating solid materials in the first return path and the method for the process of circulating solid materials in the second return path are executed separately for the return paths.

[0060] A control system for monitoring the process of circulation of solid materials in a circulating fluidized bed reactor between a reaction chamber and at least one solid material separator and returning to the reaction chamber via a return path provided with a loop seal, and further a control system for controlling the process of circulation of solid materials, the control system comprising · access to performance indicators of the process of circulation of solid materials in the return path and source history data of process variables of each performance indicator, and · a multivariable model of each performance indicator, and · when executed in a data processing unit, 〇 executable instructions for updating a multivariable model of each performance indicator using historical data of predetermined process variables and performance indicators of the process of circulation of solid materials, resulting in a calibrated multivariable model, and a performance modeling unit comprising · an input for receiving measurement data of process variables and performance indicators of the process of circulation of solid materials, and · when executed in a data processing unit, 〇 determining a modeled value of a performance indicator by applying a currently measured value of a process variable to a calibrated multivariable model, and 〇 executable instructions for comparing the modeled value of each performance indicator with each measured value of the performance indicator and checking for the presence of an anomaly between the modeled value and the measured value, and a performance diagnosis module comprising comprising.

[0061]

[0061] According to one aspect of the present invention, the control system comprises measurement sensors for at least the following process variables. A pressure sensor for measuring the pressure drop in the loop seal, a product gas temperature sensor, and means for determining the total air flow to the reactor and the bed temperature in the reaction chamber of the reactor.

[0062]

[0062] According to one aspect of the present invention, there is provided a circulation of solid materials in a circulating fluidized bed reactor between a reaction chamber and at least one solid material separator and returning to the reaction chamber via a fluidized bed heat exchanger in a return path, wherein the control system comprises measurement sensors for at least the following process variables: a pressure sensor for measuring the pressure drop at the loop seal, a product gas temperature sensor upstream of the loop seal, a temperature sensor within the loop 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 within the fluidized bed heat exchanger, and means for determining the total air flow rate to the reactor and the bed temperature within the reaction chamber of the reactor.

[0063]

[0063] This provides the effect that problems that may occur in the circulation of solid materials can be effectively predicted. The detected abnormalities act as precursors to problems in the process of the circulation of solid materials, such as a tendency to sinter.

[0064]

[0064] By avoiding unnecessary stoppages, the availability of the CFB reactor is improved and the operating costs are reduced.

[0065]

[0065] Thus, by monitoring the measured values and the modeled values, the start of sintering of the solid material can be detected, and measures can be taken in a timely manner to cure the process or at least avoid the deterioration of sintering. In the CFB boiler application, this can help avoid the shutdown of the combustion boiler system due to solid material sintering and also avoid costly repairs. Advantageously, the anomalies detected in the solid material circulation provide information about the bed quality, preferably information about whether sintering is occurring in the solid material. Or, in other words, it becomes possible to receive information about problems related to solid circulation that may tend to lead to shutdown if no corrective measures are taken. Thus, the availability of the reactor can be improved and / or the operating costs can be reduced. The method is preferably executed automatically in a local reactor control system or remotely, preferably in a process intelligence system.

[0066]

[0066] The multivariable model may be an artificial intelligence tool. According to one embodiment of the present invention, the multivariable model can be a neural network.

[0067]

[0067] Preferably, the calibration of the model is not performed (i.e., calibration is omitted) for a predetermined time when an anomaly is detected. Additionally or alternatively, 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 circulating quality problems that may contaminate the calibration. This approach can be fine-tuned so that calibration is not performed for a predetermined time when a local temperature anomaly that meets a given threshold is detected. Then, only severe conditions that generate a sufficiently large anomaly signal can be selected to lead to the skipping of calibration for a predetermined period.

[0068]

[0068] According to one aspect of the present invention, in the method, estimating the risk index of the performance indicator is evaluated as follows. · The current data of the performance indicator (KPI) of the solid material circulation is measured. · Based on the current operating data of the reactor, at least one of the following is calculated. i) The average of the performance indicators ii) The standard deviation of the measured performance indicators iii) The difference between the maximum measured performance indicator value and the minimum measured performance indicator iv) The difference between the average performance indicator and the measured performance indicator · Using the calculation results of i), ii), iii), and / or iv), prepare the risk index of the performance indicator KPI.

[0069]

[0069] The calculation results of i), ii), iii), and / or iv) are compared with the corresponding predetermined limits to obtain the risk index of the average, standard deviation, the difference between the maximum KPI value and the minimum KPI value, and / or the difference between the average KPI value and the measured KPI value.

[0070]

[0070] KPI from the average KPI k ; In the calculation of the deviation for k = 1,..., K, the average includes all KPI measurement values except the measurement value of the KPI k .

[0071]

[0071] Preferably, in the method, v) The modeled values of the KPI k ; k = 1,...K are also calculated, and the residual between the measured value of the performance indicator and the modeled value of the performance indicator is also calculated. The result of step v) is also advantageously used in preparing the risk index, preferably thereby comparing the residual with the corresponding predetermined limit to obtain the sintering risk index of the KPI residual.

[0072]

[0072] According to one aspect of the present invention, in the method, estimating the risk index of the performance indicator means that the current data of the performance indicator (KPI) of the solid material circulation is measured, and v) the KPI kModeled values for k = 1,...K are calculated and evaluated such that a residual between the measured value of the performance indicator and the modeled value of the performance indicator is calculated. The result of step v) is also advantageously used in the preparation of the risk index, preferably thereby comparing the residual with a corresponding predetermined limit in order to obtain a sintering risk index of the KPI residual.

[0073]

[0073] Then, the final risk index can be, for example, the maximum value of the above risk index. By doing so, the prediction accuracy of the floor sintering index can be further improved.

[0074]

[0074] Advantageously, according to one aspect of the present invention, it is possible to identify the most important locations where the maximum risk of blockage or sintering occurs. This would be particularly advantageous when there are multiple separators and return path assemblies.

[0075]

[0075] In this context, the term floor temperature refers to a number that is a typical representation of the floor temperature, such as the average floor temperature. The floor temperature can be calculated by different methods, such as arithmetic mean, trimmed mean, or midrange, to name just a few. The calculation can include the desired amount of data at one or several locations within the CFB reactor.

[0076]

[0076] The exemplary embodiments of the present invention presented in this patent application should not be construed as imposing limitations on the applicability of the appended claims. The verb "comprise" is used in this patent application as an open limitation that does not exclude the presence of features not listed. The features recited in the dependent claims can be freely combined with each other unless otherwise explicitly stated. The novel features considered to be characteristics of the present invention are particularly described in the appended claims.

Brief Description of the Drawings

[0077]

[0077] Hereinafter, the present invention will be described with reference to the accompanying exemplary schematic diagrams.

[0078]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0079]

[0078] In the following, the description of the figures generally relates to an example of a method of air combustion of fuel in a CFB reactor. Even if some minor structural changes may be required, the CFB reactors and their embodiments described in the figures are equally applicable for generating synthesis gas by carrying out a gasification process in the reactor. Correspondingly, the described CFB reactors and their embodiments can be utilized for carrying out a so-called oxy-fuel combustion process, which means combustion using oxygen-enriched gas that may contain air and / or recycled product gas. FIG. 1 schematically shows a circulating fluidized bed reactor 10, specifically a circulating fluidized bed boiler 10 configured to generate superheated steam in a manner known per se. The circulating fluidized bed boiler is referred to as a CFB boiler for the sake of brevity. The CFB boiler 10 includes a combustion chamber 12, at least one solid material separator 14, and a solid material return channel 16. Generally, the route through which the separated solid material returns from the separator to the combustion chamber is called the return path 15. The combustion chamber 12 includes a tube wall, a so-called finned tube wall, with fins welded between the tubes. The wall tubes are connected to the water-steam circuit (not shown) of the boiler system. The solid material separator 14 is preferably cooled and also includes a tube wall similar to the combustion chamber 12. The combustion chamber 12 includes a windbox 18, which is configured to supply a fluidizing gas, typically air, through nozzles 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 the primary combustion air. The secondary air can be supplied into the combustion chamber 12 at a higher level through one or more air inlets 21. As mentioned above, the fluidizing gas and the combustion gas are usually air, but can also comprise recycled product gas and / or oxygen or a mixture thereof. Generally, it should be understood that the term product gas can be understood such that the gas exiting the separator 14 is the product gas of the reaction in the reaction chamber. For example, if the method includes gasification of a fuel material, the product gas is a combustible gas, a so-called synthesis gas, and if the method includes combustion of fuel in the reaction chamber and generation of steam by the released heat, the product gas can be referred to as flue gas.In some actual applications, such as so-called oxygen combustion, a portion of the flue gas may be recycled to the reaction chamber as fluidizing gas and can thus be referred to as recycled gas.

[0080]

[0079] The windbox 18, and other air inlets as well, are connected to an air source 24. This is an example of an air-operated CFB boiler. There is at least one inlet 22 for fuel connected to the combustion chamber 12. The operation of the CFB boiler involves the process of circulation of solid material, which can also be referred to as bed material in this context. The bed material can comprise sand, limestone, and / or clay, especially kaolin, and can also include unburned fuel. Due to the bed material within the boiler, the CFB boiler has a high heat transfer rate and a substantially uniform temperature distribution, as well as a fairly low and stable combustion temperature. Combustion of fuel in the circulating fluidized bed results in heating, evaporation of water in the water / steam circuit, and superheating of the steam, which can be used by itself-known methods, such as for power generation in a steam turbine generator, for example. The steam cycle is not described in more detail here.

[0081]

[0080] What is characteristic of a CFB boiler is that during its operation, the process of circulation of solid materials is maintained through a route formed by a combustion chamber, a separator, and a solid return path. Combustion of fuel in a CFB results in high-efficiency combustion of various solid fuels with low emissions, even when fuels with completely different calorific values are combusted simultaneously. Due to fluidization, as indicated by the arrows in Fig. 1, inside the combustion chamber 12, there is an upward internal movement of solid materials in the middle of the chamber and a downward flow of solids near the walls. The generated gas and solid materials flow from the combustion chamber 12 to a solid material separator 14 whose inlet is connected to the combustion chamber by a connector duct 26. The solid material separator 14, preferably a cooling cyclone separator, has a first outlet 28 for the generated gas and a second outlet 30 for the separated solid materials 32. The first outlet 28 of the separator is actually connected to a backpass 40. The backpass includes several heat exchanges that may include an air preheater 46, an economizer 44, and a superheater and reheater 42. The actual amount of different heat transfer surfaces in each of these components can be selected differently for each CFB boiler, for example, according to actual requirements.

[0082]

[0081] The solid material transported to the separator 14 by the generated gas is separated from the gas as indicated by the arrows in the figure. A second outlet 30, which may also be referred to as a particle outlet, is connected to the lower part of the combustion chamber 12 by a return path 15 for returning the separated solid material to the combustion chamber 12. A so-called loop seal 32 is provided in the return path 15, and this loop seal prevents backflow from the combustion chamber 12 to the particle outlet and enables the separated solid material to be controllably supplied back to the combustion chamber 12. The loop seal may also be referred to as a gas seal. The operation of the loop seal is controlled by fluidizing air that can be controllably supplied through the air inlet 23. Thus, the circulation of the solid material comprises a flow of solid material from the combustion chamber 12 to the solid material separator 14 and back from the solid material separator 14 to the combustion chamber 12 via the return path 15 and the loop seal 32. The process of the circulation of the solid material is maintained and controlled while the CFB boiler is operating. The general direction of movement of the solid material may also be used to reference positions within the CFB boiler, and that direction will become apparent in the above description.

[0083]

[0082] In a CFB boiler, the solid material circulation can be divided into two categories. That is, an internal circulation material flow, which means the solid material circulating inside the combustion chamber (12), schematically indicated by the upside-down U-shaped arrows in FIG. 1 and described above, and an external circulation material flow, which means the solid material circulating outside the combustion chamber, i.e., within the particle separator and the loop seal and the return path 15 (in FIG. 1). The external circulation material flow may also involve the treatment of the solid material in a fluidized bed heat exchanger, as shown in FIG. 3. Advantageously, according to one aspect of the present invention, the solid material in the return path may, in other terms, be referred to as the solid material in the external circulation of the CFB boiler.

[0084]

[0083] To monitor the process of the circulation of solid materials, the CFB boiler 10 is equipped with a plurality of sensors for obtaining online data of performance indicators and process variables. When the online data is stored after the moment of measurement, it becomes historical data. To execute the method according to the present invention, at least the following sensors and measurement points are arranged in the CFB boiler. · A first pressure sensor 101 arranged upstream of the loop seal 32 but downstream of the solid material separator, that is, between the loop seal and the solid material separator 14 · A second pressure sensor 102 arranged downstream of the loop seal 32, between the loop seal 32 and the combustion chamber 12 The purpose of the first and second pressure sensors is to determine the pressure difference provided by the loop seal 32. · A first temperature sensor 100 arranged within the loop seal 32 · A second temperature sensor 103 arranged upstream of the loop seal 32. In FIG. 1, it is shown that the second temperature sensor 103 is arranged at the first outlet 28 of the solid separator 14, which also represents the temperature of the solid material upstream of the loop seal 32 in the sense of FIG. 1. · A first air flow sensor 105 for measuring the primary air flow rate through the grid 20 of the CFB boiler · A second air flow sensor 106 for measuring the secondary air flow rate The purpose of the first and second air flow sensors is to determine the total air flow rate supplied into the CFB boiler. · Several third temperature sensors 104 connected to the combustion chamber 12 and arranged to determine the bed temperature within the combustion chamber 12

[0085]

[0084] In addition, as shown in FIG. 1, optionally, there may be an air flow sensor 109 for measuring the air flow rate to the loop seal, which may be included in the total air flow rate. The temperature sensor downstream of the second outlet 30 of the separator 14 provides a measured value representing the temperature of the solid material.

[0086]

[0085] The CFB boiler further comprises a control system 48 for passing numerical calculations related to the control of the CFB boiler and in particular to the monitoring of the process of the circulation of solid materials in the CFB boiler. It should be understood that FIG. 1 is an exemplary illustration of the process of the circulation of solid materials through a particular type of return path and an illustration of the process of the circulation of solid materials through one return path. If the CFB boiler comprises two or more return paths, as it often actually does, the present invention is separately applicable to each of the return paths. Advantageously, the CFB boiler may comprise a solid material separator 14 and a corresponding return path 15 on both sides of the combustion chamber 12 (not shown).

[0087]

[0086] FIG. 2 shows a general illustration of a method and a control system 48 in a control system capable of monitoring the process of the circulation of solid materials in the CFB reactor 10 such that conditions related to the circulation of solid materials that could lead to the shutdown of the reactor are observed early enough to take corrective measures and the shutdown of the reactor can be avoided.

[0088]

[0087] The control system 48 is involved in the execution of a method for monitoring the process of the circulation of solid materials in the circulating fluidized bed boiler 10. The control system comprises one or more computers and executable instructions, i.e., a computer program that, when executed in the control system 48, implements the method in the circulating fluidized bed boiler 10. The method comprises a. selecting performance indicators of the process of the circulation of solid materials and process variables of each performance indicator of the process of the circulation of solid materials, b. calibrating a multivariate model of each performance indicator using historical data of the process variables and performance indicators of the process of the circulation of solid materials, c. determining a modeled value of a performance indicator by applying a currently measured value of a process variable to the multivariate model, d. comparing the modeled value of each performance indicator with the respective measured value of each performance indicator and checking for the presence of an anomaly between the modeled value and the measured value and comprises.

[0089]

[0088] The control system includes a performance modeling unit 400. When executed in the control system 48, the modeling unit 400 calibrates a multivariate model of each performance index using historical data of predetermined process variables and performance indexes of the process of the circulation of the solid material, and provides executable instructions that result in the calibrated multivariate model.

[0090]

[0089] The performance modeling unit 400 has or provides access such as data transfer communication with a source 401 of a) performance indexes of the process of the circulation of the solid material obtained from the CFB boiler and b) historical data of the process variables of each performance index. The historical data is stored in a data medium used as the source 401 of the historical data, measures the values 101, 102, 103,... 109 (see FIG. 1) of a predetermined process variable over a period of time, stores the measured values together with time stamps, and thereby obtains the historical data of the process variable by forming the historical data of the process variable. Obtaining the historical data involves measuring the values of the performance indexes respectively, storing the measured values together with time stamps, and thereby forming the historical data of the performance indexes. The control system 48 includes a data filtering unit 406 configured to filter and remove invalid process data, and thus the historical data includes data that has undergone a filtering process using a predetermined data filter. Therefore, the historical data is data that describes the normal operating conditions of the CFB boiler 10.

[0091]

[0090] Advantageously, the filtering process 406 may comprise the following conditions or rules. First, the isolation time of the measured data is set such that only data older than a preset isolation time is approved. The isolation time varies depending on the case. In some practical applications, the isolation time can even be as short as 3 to 7 days. However, the isolation time is preferably 7 to 14 days, more preferably at least two weeks. In addition, it is preferable to filter out data that is too old and may no longer be used. Thus, a given data filter is configured to approve data that is not older than a given time, advantageously not older than two months. Also, the filter unit is configured to filter out from the historical data any data from a stopped situation and / or any data resulting from any abnormal operating conditions, based on, for example, a given limit of an input variable, or external information that renders the data unusable, or data of an abnormal operation.

[0092]

[0091] In this way, the model is based on historical data representing normal operating conditions. For example, the historical data related to the CFB boiler shown in FIG. 1 includes process variables and performance indicators: · The pressure value (sensor 101) upstream of the loop seal 32 but downstream of the solid material separator, i.e., between the loop seal and the solid material separator 14 · Downstream of the loop seal 32, the pressure value (sensor 102) between the loop seal 32 and the combustion chamber 12 · Or alternatively, the pressure difference across the loop seal 32 (combination of sensors 101, 102) · The temperature upstream of the loop seal 32 (sensor 103) · The total air flow rate supplied into the CFB boiler (sensors 105, 106) · The total bed temperature in the combustion chamber 12 (sensor 104) and includes data of.

[0093]

[0092] The performance indicators represent factors that describe the state of the process of the circulation of the solid material. In the case of the embodiment shown in FIG. 1, the performance indicators are, advantageously, i. the pressure difference of the loop seal in the return path, and ii. the temperature within the loop seal in the return path of the circulation of the solid material are.

[0094]

[0093] The data in the history data source 401 is used as an input to the modeling unit 400 configured to prepare and / or calibrate a multivariate model separately assigned for each performance indicator, in this case for two performance indicators. Thus, the performance modeling unit 400 provides a multivariate model for each performance indicator. Calibration can be repeated at predetermined intervals or periodically. This helps to keep the model in the actual state, reflecting the possible changes caused by the normal use of the CFB boiler, and the environmental conditions (changes in temperature, ambient humidity, ambient pressure) that can bring about changes in fuel quality and changes in operating parameters over time. Calibration can be blocked when an anomaly in the process is detected. By doing so, it can be ensured that the problems just progressing in the bed material circulation do not contaminate the calibration and the model.

[0095]

[0094] The model can be constructed by the modeling unit 400 using multivariate linear regression. In principle, the past input values of the model (i.e., the measurement history data) are used for the estimation of the coefficients of the model. The model is then used to estimate the dominant situation by utilizing the current online data and the estimated coefficients.

[0096]

[0095] For example, in linear regression, the response variable is expected to be a linear combination of the process variables. By fitting a linear equation to the history data, the relationship between multiple process variables and the performance indicators can be modeled using multiple linear regression.

[0097]

[0096] In the case of the embodiment shown in FIG. 1, the multivariate model of the loop seal temperature having the observed value of N is defined as follows. y i =b 0 +b 1 x i,1 +b 2 x i,2 +b 3 x i,3 +ε i However, y represents the value of the performance index as the loop seal temperature, x i,1 is the i-th value of the temperature (sensor 103) upstream of the loop seal 32, x i,2 is the i-th value of the total air flow rate (sensors 105, 106) supplied into the CFB boiler, x i,3 is the i-th value of the bed temperature (sensor 104) in the combustion chamber 12, b 0 is a constant, and b 1 ...b 3 are unknown coefficients specific to the KPI to be estimated, ε i has the experimental error of the model.

[0098]

[0097] In the case of the embodiment shown in FIG. 1, the multivariate model of the loop seal pressure difference having the observed value of N is defined as follows. y i =b 0 +b 1 x i,1 +b 2 x i,2 +b 3 x i,3 +ε i However, y represents the value of the performance index, x i,1 is the i-th value of the temperature (sensor 103) upstream of the loop seal 32, x i,2 is the i-th value of the total air flow rate (sensors 105, 106) supplied into the CFB boiler, xi,3 is the i-th value of the floor temperature (sensor 104) in the combustion chamber 12, b 0 is a constant, b 1 ...b 3 is a coefficient specific to the unknown KPI to be estimated, ε i has the experimental error of the model. Fitting is performed by minimizing the sum of the squares of the vertical deviations from the observed data at each data point to the line that best fits the data, which is the optimal coefficient value by minimizing the sum of the squared errors.

[0099]

[0098] The modeling unit 400 provides the necessary coefficients of the model based on the executable historical data, which is used to model the performance index by applying the online data of the process variables to the model. While the control system 48 and the CFB boiler 10 are operating, the historical data including the data of the process variables and the performance index is continuously read out 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, in order to learn the latest conditions of the normal operation of the process of the solid material circulation.

[0100]

[0099] The control system 48 is also provided with a performance diagnosis module 404. The performance diagnosis module is configured to receive the current online data of the CFB boiler of the performance index from the current data source 402, as well as the newly calibrated model of the process variables and the performance index from the modeling unit 400. The performance diagnosis module 404 includes instructions for determining the modeled value of the performance index by applying the currently measured value of the process variable to the calibrated multivariable model. In addition, the performance diagnosis module 404 is configured to compare the modeled value of each performance index with the respective measured value of the performance index and check for the presence of anomalies between the modeled value and the measured value. Based on the result of the comparison, one or more predetermined measures may be taken and generated as the diagnostic output 408.

[0101]

[0100] The existence of anomalies and the need for corrective measures can be recognized by estimating the risk index of each KPI. The performance diagnosis module 404 may comprise instructions for executing a method for estimating the risk index of a performance metric, which performs the following operations. · Current data of the performance indicator (KPI) of the solid material circulation is measured. · Based on the current data of the boiler, at least one of the following: i) The average of the performance indicators is calculated. ii) The standard deviation of the measured performance indicators is calculated. iii) The difference between the maximum measured performance indicator value and the minimum measured performance indicator is calculated. iv) The difference between the average performance indicator KPI and the measured performance indicator is calculated. · Using the calculation results of i), ii), iii), and / or iv), prepare the risk index of the performance indicator KPI. The calculation results of i), ii), iii), and / or iv) are compared with corresponding predetermined limits to obtain the risk indices of the average, standard deviation, the difference between the maximum KPI and the minimum KPI, and the difference between the average KPI and the measured KPI. In calculating the deviation of KPIk from the average, the average includes all KPI measurements except the measured value of KPIk.

[0102]

[0101] Preferably, in the method, further or alternatively, v) Modeled values of KPI k ; k = 1,... K are calculated, and the residual between the measured value of the performance indicator and the modeled value of the performance indicator is calculated. The result of step v) is also advantageously used in preparing the risk index, preferably by comparing the residual with the corresponding predetermined limit to obtain the sintering risk index of the KPI residual.

[0103]

[0102] Then, the final risk index can be, for example, the maximum value of the above risk indices. In this way, the prediction accuracy of the floor sintering index can be further improved.

[0104]

[0103] The inventors have observed that doing so provides an indication of the conditions in the process of the circulation of solid materials in a circulating fluidized bed boiler where the resulting risk index leads to a risk of boiler shutdown unless corrective measures are taken early enough so that the need to stop the boiler can be avoided.

[0105]

[0104] Optionally, the control system includes a storage device 410 for the historical coefficients of the models, where each calibrated model is stored. The performance diagnosis module 404 may include a model evaluation function for checking newly created models, and if it is found that the newly created model is incomplete, the model from the storage device 410 of the historical coefficients of the models is used until a complete new model can be provided.

[0106]

[0105] FIG. 3 schematically shows a circulating fluidized bed boiler 10 in which a fluidized bed heat exchanger 50 is provided in one of the return paths 15 (only one is shown for clarity). The return path 15 shown in FIG. 3 may be considered to be within the same CFB boiler disclosed in FIG. 1, that is, the CFB boiler may be provided with several return paths 15, and it should be understood that the fluidized bed heat exchanger 50 is preferably provided in two or more of these return paths 15. FIG. 3 also refers to an actual application where the CFB boiler has several return paths 15, and the fluidized bed heat exchanger 50 is provided in all of them. The method according to the invention is carried out separately for all of the return paths 15.

[0107]

[0106] The fluidized bed heat exchanger 50 is disposed in the return path 15 downstream of the loop seal 32 in the return channel 16. Solid material flows into the fluidized bed heat exchanger 50 through the loop seal 32, where a bubbling bed of the solid material is formed by introducing fluidizing air through the grid 52 at its bottom into the fluidized bed heat exchanger 50. The fluidized bed heat exchanger 50 is provided with a lifting chamber 54 having respective inlets 54 for the transport air. The lifting chamber transfers the solid material from the fluidized bed heat exchanger 50 back to the combustion chamber 12 via the return duct 55.

[0108]

[0107] The fluidized bed heat exchanger 50 is provided with one or more heat exchange units 58, which are preferably connected, for example, to a steam cycle. The heat exchange unit can be an evaporator, a steam superheater, and / or a steam reheater. The heat exchange unit comprises a heat transfer surface such as one or more tube bundles inside the bubbling bed of the solid material formed in the fluidized bed heat exchanger 50.

[0109]

[0108] In the CFB boiler, the solid material transported to the separator 14 by the product gas is separated from the gas as shown by the arrows in the figure. The second outlet 30, which can also be referred to as the particle outlet of the separator 14, is connected to the lower part of the combustion chamber 12 by a return path 15 for returning the separated solid material to the combustion chamber 12. The return path 15 is provided with a so-called loop seal 32, which prevents backflow from the combustion chamber 12 to the particle outlet and enables the separated solid material to be controllably fed forward within the return path 15. The operation of the loop seal is controlled by the fluidizing air that can be controllably supplied through the air inlet 23. Thus, the circulation of the solid material comprises the flow of the solid material from the combustion chamber 12 to the solid material separator 14, 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. While the fluidized bed heat exchanger 50 is operating, heat is transferred from the solid material to the steam flowing through the heat exchange unit 58, which cools the solid material before it is introduced to return to the combustion chamber 12.

[0110]

[0109] To monitor the process of the circulation of solid materials, the CFB boiler 10 according to the embodiment of FIG. 3 is provided with a plurality of sensors for obtaining online data of performance indicators and process variables. When the online data is stored after the moment of measurement, it becomes historical data. To execute the method according to the present invention, at least the following sensors and measurement points are arranged in the CFB boiler. · A first pressure sensor 101 arranged upstream of the loop seal 32 but downstream of the solid material separator, that is, between the loop seal and the solid material separator 14 · A second pressure sensor 102 arranged downstream of the loop seal 32, between the loop seal 32 and the fluidized bed heat exchanger 50 The purpose of the first and second pressure sensors is to determine the pressure difference provided by the loop seal 32. · A first temperature sensor 100 arranged within the loop seal 32 · A second temperature sensor 103 arranged upstream of the loop seal 32. FIG. 2 shows that the second temperature sensor 103 is arranged at the first outlet 28 of the solid separator 14, which also represents the temperature of the solid material upstream of the loop seal 32 in the sense of FIG. 2. · A first air flow sensor 105 for measuring the primary air flow rate through the grid 20 of the CFB boiler · A second air flow sensor 106 for measuring the secondary air flow rate The purpose of the first and second air flow sensors is to determine the total air flow rate supplied into the CFB boiler. Some third temperature sensors 104 connected to the combustion chamber 12 and arranged to determine the bed temperature within the combustion chamber 12 · A third air flow sensor 108 for measuring the air flow rate supplied to the fluidized bed heat exchanger 50 · A third pressure sensor 110 arranged upstream of the heat exchange unit 58 within the fluidized bed heat exchanger 50 · A fourth pressure sensor 112 arranged downstream of the heat exchange unit 58 within the fluidized bed heat exchanger 50 ·A third temperature sensor 114 disposed downstream of the heat exchange unit 58 within the fluidized bed heat exchanger 50

[0111]

[0110] The control system 48 described in FIG. 2 is applicable to the CFB boiler 10 described in FIG. 3 with the necessary modifications related to the data of the performance indicators and process variables. The actual exact location of the sensor can be determined as the case may be. For example, the third temperature sensor may, in some cases, be disposed between the lifting chamber 54 and the combustion chamber 12. This is because the temperature at that specific location 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 may be positioned differently as long as it represents the temperature of the solid material upstream of the loop seal 32.

[0112]

[0111] When applied to the CFB boiler according to FIG. 3, the control system 48 is involved in the execution of a method for monitoring the process of the circulation of the solid material in the circulating fluidized bed boiler 10. The control system includes one or more computers and executable instructions, that is, a computer program that, when executed in the control system 48, implements the method in the circulating fluidized bed boiler 10. The method includes a. Selecting performance indicators of the process of the circulation of the solid material and process variables of each performance indicator of the process of the circulation of the solid material, b. Calibrating a multivariable model of each performance indicator using historical data of the process variables and performance indicators of the process of the circulation of the solid material, c. Determining a modeled value of the performance indicator by applying the currently measured value of the process variable to the multivariable model, d. Comparing the modeled value of each performance indicator with the respective measured value of each performance indicator and checking for the presence of an anomaly between the modeled value and the measured value and comprises.

[0113]

[0112] The control system includes a performance modeling unit 400. When the modeling unit 400 is executed in the control system 48, it calibrates a multivariable model of each performance index using historical data of predetermined process variables and performance indices of the process of the circulation of the solid material, and provides executable instructions that result in the calibrated multivariable model.

[0114]

[0113] The performance modeling unit 400 has or provides access such as data transfer communication with a source 401 of a) performance indices of the process of the circulation of the solid material obtained from the CFB boiler and b) historical data of the process variables of each performance index. The historical data is stored in a data medium used as the source 401 of the historical data, measures the values 101, 102, 103,... 114 (see FIG. 3) of a predetermined process variable over a period of time, stores the measured values together with a time stamp, and thereby obtains the historical data of the process variable by forming the historical data of the process variable. Obtaining the historical data involves measuring the values of each performance index and storing the measured values together with a time stamp, thereby forming the historical data of the performance index. The control system 48 includes a data filtering unit 406 configured to filter and remove invalid process data, so that the historical data includes data that has undergone a filtering process using a predetermined data filter. Therefore, the historical data is data that describes the normal operating conditions of the CFB boiler 10. The filtering unit will be described in more detail in connection with the description of FIG. 2.

[0115]

[0114] The historical data related to the CFB boiler shown in FIG. 3 includes process variables and performance indices: · The pressure value (sensor 101) upstream of the loop seal 32 but downstream of the solid material separator, that is, between the loop seal and the solid material separator 14 · The pressure value (sensor 102) downstream of the loop seal 32, between the loop seal 32 and the fluidized bed heat exchanger 50 · Or alternatively, the pressure difference across the loop seal 32 (combination of sensors 101, 102) · Temperature inside the loop seal 32 (sensor 100) · Temperature upstream of the loop seal 32 (sensor 103) · Pressure value upstream of the heat exchange unit 58 in the fluidized bed heat exchanger 50 (sensor 110) · Pressure value downstream of the heat exchange unit 58 in the fluidized bed heat exchanger 50 (sensor 110) · Temperature downstream of the heat exchange unit 58 in the fluidized bed heat exchanger 50 (sensor 114) · Total air flow rate supplied into the fluidized bed heat exchanger 50 (sensor 108) · Total air flow rate supplied into the CFB boiler (sensors 105, 106) · Bed temperature in the combustion chamber 12 (sensor 104) comprises the data of

[0116]

[0115] The performance indicators represent factors that describe the process of the circulation of the solid material and the state of the fluidized bed heat exchanger. In the case of the embodiment shown in FIG. 3, the performance indicators are, advantageously, i. The pressure difference of the loop seal in the return path, and ii. The temperature inside the loop seal in the circulation of the solid material, iii. The pressure difference of the fluidized bed heat exchanger, iv. The temperature of the solid material downstream of the fluidized bed heat exchange unit are.

[0117]

[0116] The data within the history data source 401 is used as input to a modeling unit 400 configured to prepare and / or calibrate multivariate models separately for each performance metric, in this case two performance metrics. Thus, the performance modeling unit 400 provides a multivariate model for each performance metric. Calibration can be repeated at predetermined intervals or periodically. This helps keep the model in line with changes that may be caused by the normal use of the CFB boiler and environmental conditions (changes in temperature, ambient humidity, ambient pressure) that can lead to changes in fuel quality and changes in operating parameters over time. Calibration can be blocked when an anomaly in the process is detected. This way, it can be ensured that problems that are just occurring in the bed material circulation do not contaminate the calibration and the model.

[0118]

[0117] The model can be constructed by the modeling unit 400 using multivariate linear regression. In principle, past input values of the model (i.e., the measurement history data) are used to estimate the coefficients of the model. The model is then used to estimate the prevailing situation by utilizing the current online data and the estimated coefficients.

[0119]

[0118] For example, in linear regression, the response variable is expected to be a linear combination of the process variables. By fitting a linear equation to the history data, multiple linear regression can be used to model the relationship between multiple process variables and the performance metric.

[0120]

[0119] In the case of the embodiment shown in FIG. 3, the multivariate model of the temperature of the solid material downstream of a fluidized bed heat exchange unit (hereinafter, FBHX) having N observed values is defined as follows. y i =b 0 +b 1 x i,1 +b 2 x i,2 +b 3 x i,3 +b 4 xi,4 +b 5 x i,5 +ε i However, y represents the value of the performance index, x i,1 is the i-th value of the pressure difference across the loop seal 32 (sensors 110, 112), x i,2 is the i-th value of the temperature within the loop seal 32 (sensor 100), x i,3 is the i-th value of the total air flow rate supplied into the CFB boiler (sensors 105, 106), x i,4 is the i-th value of the bed temperature within the combustion chamber 12 (sensor 104), x i,5 is the i-th value of the air flow rate supplied to the chamber of the fluidized bed heat exchanger 50 (sensor 108), b 0 is a constant, b 1 ...b 5 is an unknown coefficient specific to the KPI to be estimated, ε includes the experimental error of the model.

[0121]

[0120] In the case of the embodiment shown in FIG. 3, the multivariable model of the pressure difference across the fluidized bed heat exchanger with N observed values is defined as follows. y i =b 0 +b 1 x i,1 +b 2 x i,2 +b 3 x i,3 +b 4 x i,4 +b 5 x i,5 +ε i However, y represents the value of the performance index, x i,1 is the i-th value of the pressure difference across the loop seal 32 (sensors 110, 112), x i,2is the i-th value of the temperature (sensor 100) within the loop seal 32, x i,3 is the i-th value of the total air flow rate (sensors 105, 106) supplied into the CFB boiler, x i,4 is the i-th value of the bed temperature (sensor 104) within the combustion chamber 12, x i,5 is the i-th value of the air flow rate (sensor 108) supplied to the chamber of the fluidized bed heat exchanger 50, b 0 is a constant, b 1 ...b 5 is an unknown coefficient specific to the KPI to be estimated, ε has the experimental error of the model. Fitting is performed by minimizing the sum of the squares of the vertical deviations from each data point to the line that best fits the observed data, which is the optimal coefficient value by minimizing the sum of the squared errors.

[0122]

[0121] The modeling unit 400 provides the necessary coefficients of the model based on the executable historical data, which is used to model the performance index by applying the online data of the process variables to the model. While the control system 48 and the CFB boiler 10 are operating, the historical data including the data of the process variables and the performance index is continuously read out 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, in order to learn the latest conditions of the normal operation of the process of the circulation of the solid material.

[0123]

[0122] The control system 48 is also provided with a performance diagnosis module 404, which is also applicable to a CFB boiler equipped with one or more fluidized bed heat exchangers. Therefore, the description or the performance diagnosis module related to FIG. 2 is also applicable to the embodiment of FIG. 3.

[0124]

[0123] Figure 4 depicts the results obtained by a method for monitoring the process of circulation of solid materials in the circulating fluidized bed boiler according to FIG. 3. Figure 4 discloses the online measurement results provided by the third temperature sensor 114. The third temperature sensor is located below the heat exchange unit 58 and near the grid of the chamber within the fluidized bed heat exchanger. Thus, the curve M114 indicates the temperature of the solid material downstream of the fluidized bed heat exchange unit, which is the temperature of performance indicator iv. Another curve P114 shown in Figure 4 indicates the modeled value of the performance indicator when the currently measured value of the process variable is applied to the multivariate model of the KPI. The horizontal axis indicates time, and the zero point is the actual time of boiler shutdown. As can be seen from the graph, after the modeled value of the model shows a deviation from the measured value for several hours, the process is too disrupted to recover, and no improvement measures will be able to prevent the shutdown. As is evident from this example, the model indicates an impending problem more than 30 hours before the shutdown becomes irreversible. Unfavorable conditions can be observed sufficiently early, within a sufficiently long time frame (hatched area), well in advance, before the actual problem occurs.

[0125]

[0124] Figure 5 schematically shows a circulating fluidized bed boiler 10 having, in one of the return paths 15 (only one is shown for clarity), a fluidized bed heat exchanger 50 and a bypass path 56 that connects the solid material return path 15 to the combustion chamber 12 at a location between the loop seal 32 and the fluidized bed heat exchanger 50. Thus, the bypass path 56 is arranged to controllably feed 0 to 100% of the solid material flow in the return path 15 directly to the combustion chamber, while sending the portion that may be re-mined to the fluidized bed heat exchanger 50. In this way, the process of circulating the solid material has two modes. That is, a first mode (bypass mode) in which the method is applied to the circulation of the solid material directly from the loop seal 32 to the combustion chamber 12 of the CFB boiler (when there is a flow of solid material through the bypass path), and a second mode in which the method is applied to the circulation of the solid material via the fluidized bed heat exchanger 50 from the loop seal 32 to the combustion chamber 12 of the CFB boiler (when there is a flow of solid material through the fluidized bed heat exchanger 50). Therefore, the embodiment shown in Figure 5 can be understood as a combination of the embodiments shown in Figures 1 and 3 in a single solid material return path 15 with respect to applying the method according to the present invention.

[0126]

[0125] Also, the return path 15 shown in Figure 5 may be considered to be within the same CFB boiler disclosed in Figure 1 or 3, that is, the CFB boiler may be provided with several return paths 15 with different settings, and it should also be understood that the fluidized bed heat exchanger 50 may be provided in two or more of those return paths 15, preferably. Figure 5 also refers to an actual application where the CFB boiler has several return paths 15 and the fluidized bed heat exchanger 50 is provided in all or some of them with a bypass path 55. The method according to the present invention is executed separately for all of the return paths 15.

[0127] In addition to or instead of having a bypass path 56, FIG. 5 discloses a solid material discharge path 56' connected to the solid material return path 15 at a location between the loop seal 32 and the fluidized bed heat exchanger 50. The location of the discharge path 56' or the extraction point of its material may be other than those shown here, if desired. The solid material discharge path 56' makes it possible to remove 0 to 100% of the solid material flow from the process of the solid material circulation. The portion of the removed material can be returned to the reactor 10 later, either as it is or after a desired treatment has been carried out on the solid material.

[0128] The control system 48 described in FIG. 2 is applicable to the CFB boiler 10 described in FIG. 5, with the necessary modifications related to the data of the performance indicators and process variables added.

[0129] An exemplary embodiment of the calculation of the residual-based KPI and risk index when the circulating fluidized bed boiler 10 is provided with a fluidized bed heat exchanger 50 in one of its return paths 15. The following steps are taken. · Step of creating a KPI model based on the pressure difference and temperature at the loop seal and the pressure difference and temperature in the fluidized bed heat exchange chamber. · Step of comparing the modeled value of the KPI with the measured value at the current time point (t). For example, the KPI of the modeled loop seal temperature can be calculated as follows. KPI loop seal temp.modelled (t):=y t =b 0 +b 1 x t,1 +b 2 x t,2 +b 3 x t,3 +ε t However, b 0 is a constant specific to the KPI (solved previously), and b 0 ...b 3 are known coefficients specific to the KPI (solved previously), x t,1is the t-th value of the temperature (sensor 103) upstream of the loop seal 32, x t,2 is the t-th value of the total air flow rate (sensors 105, 106) supplied into the CFB boiler, x t,3 is the t-th value of the bed temperature (sensor 104) in the combustion chamber 12. · Residual (KPI k,res (t), where k = 1 to K (K = number of KPIs), the comparison is made by calculating the deviation between the model output and the measured value. (For example, the modeled temperature - the measured temperature in the loop seal, i.e., KPI loop seal temp.res (t)=KPI loop seal temp.modelled (t)-KPI loop seal temp.meas (t))

[0130]

[0129] The residual limits for each KPI type are shown schematically in the following table.

[0131]

Table 1

[0132] However, A, B, C, and D represent predetermined limit values. · Calculate the risk index for each KPI as follows. r k =100×(|KPI k,res (t)-(l up,k +l lo,k ) / 2|) / ((l up,k -l lo,k ) / 2) However, |.| is the absolute value, and k = 1 to K (K = number of KPIs). · Calculate the overall risk index RI as follows. RI=max(r k ) However, r k = individual risks, and k = 1 to K (K = number of KPIs).

[0133]

[0130] As an example, the residual of the temperature in the loop seal is KPIloop seal temp,res (t) = KPI loop seal temp,modelled (t) - KPI loop seal temp,meas (t) = B up Assume that it is so. Next, using the above formula, obtain the loop seal temperature risk index. r loop seal temp = 100×(|B up -(B up + B lo ) / 2|) / ((B up - B lo ) / 2) B up = B and B lo = -B, then r loop seal temp = 100, and thus, the calculation of the overall risk index using the above formula results in RI = max(r k ) = 100.

[0134]

[0131] If there is no fluidized bed heat exchange chamber, proceed as in the above example, but omit the values (KPI) related to the fluidized bed heat exchange chamber.

[0135]

[0132] According to one aspect of the present invention, the overall risk index can be calculated using at least one of the following formulas. Maximum RI = max(r k ), Average RI = mean(r k ), Weighted average RI = Wmean(r k ), or Median RI = median(r k ).

[0136]

[0133] According to a preferred aspect of the present invention, the risk index of each KPI is limited to have a maximum value of 100 and a minimum value of 0, that is, r k = [0,..., 100]. Therefore, if the absolute value of KPI k is greater than the absolute value of the lower limit (l lo,k ) or the upper limit (l up,k ), then r k = 100. Generally, if KPI k does not belong to the interval [l lo,k , l up,k , then r k = 100. 100×(|KPIk (t)-(l up,k +l lo,k ) / 2|) / ((l up,k -l lo,k ) / 2)>100, then r k =100, otherwise r k =100×(|KPI k (t)-(l up,k +l lo,k ) / 2|) / ((l up,k -l lo,k ) / 2). It is also possible to have the condition written as such.

[0137]

[0134] In the above example, the table shows that the absolute limit values can be equal, but it is possible to define the upper and lower limits differently such that the absolute values of the upper and lower limits are different for the corresponding KPIs. However, note that l lo,k <l up,k .

[0138]

[0135] The above example is given only for the purpose of clarification and is not intended to limit the scope of the invention claimed. Also, instead of the residual, other mathematical comparisons, for example, calculating the ratio between corresponding values, are possible.

[0139]

[0136] In this specification, the invention has been described as examples related to what is currently considered the most preferred embodiment, but it is obvious to those skilled in the art that as technology progresses, the basic concept of the invention can be implemented in many ways. The details mentioned in relation to any of the above embodiments may be used in relation to another embodiment when such a combination is technically feasible.

[0140] Parts list Circulating fluidized bed boiler 10 Combustion chamber 12 Solid material separator 14 Solid material return path 15 Solid material return channel 16 Wind box 18 Grid 20 Air inlet 21 Loop seal fluidization air inlet 23 Air source 24 Fuel inlet 22 Duct 26 First outlet 28 Second outlet 30 Loop seal 32 Back pass 40 Superheater and optional reheater 42 Economizer 44 Air preheater 46 Control system 48 Fluidized bed heat exchanger 50 Grid of fluidized bed heat exchanger 52 Lifting chamber 54 Return duct 55 Bypass path 56 Heat exchange unit 58 First temperature sensor 100 First pressure sensor 101 Second pressure sensor 102 Second temperature sensor 103 Third temperature sensor 104 First air flow sensor 105 Second air flow sensor 106 Third air flow sensor 108 Fourth air flow sensor 109 Third pressure sensor 110 Fourth pressure sensor 112 Third temperature sensor 114 Performance modeling unit 400 Source of historical data 401 Source of current data 402 Performance diagnosis module 404 Data filter unit 406 Diagnostic output 408 Storage device for model historical coefficients 410

Claims

1. A method for monitoring the process of circulation of solid materials in a circulating fluidized bed reactor (10), wherein the reactor (10) comprises a reaction chamber (12), at least one solid material separator (14), and a return path (15) between the at least one solid material separator (14) and the reaction chamber (12), and in this method, the process of circulation of the solid materials comprises arranging the solid materials to be drawn in by the gas flow in the reaction chamber (12) and further drawn from the reaction chamber (12) into the at least one solid material separator (14), and sending the solid materials from the solid material separator (14) to the reaction chamber (12) via the return path (15), the method comprising at least the following steps: a. Selecting a process variable of the process of circulation of the solid materials in the return path (15), and selecting a performance index of the process of circulation of the solid materials from among the selected process variables for each performance index of the process of circulation of the solid materials; b. Using the historical data of the process variable and the performance index of the process of circulation of the solid materials to create a multivariate model for each performance index; c. Determining a modeled value of the performance index by applying the currently measured value of the process variable to the multivariate model; d. Comparing the modeled value of each performance index with the respective measured value of each performance index, and checking for the presence of an anomaly between the modeled value and the measured value; characterized in that it comprises the above. A method.

2. The process of circulation of the solid materials comprises directly sending the solid materials from the separator (14) to the reaction chamber (12) via a loop seal, at least, i. the pressure difference of the loop seal (32) in the return path (15), and ii. the temperature in the loop seal (32) in the return path (15) of the circulation of the solid materials, are selected as the performance indices of the process in step a), according to the method of claim 1.

3. The process of circulation of the solid materials comprises sending the solid materials from the separator (14) to the reaction chamber (12) via a fluidized bed heat exchanger (50), at least, i. the pressure difference of the loop seal in the return path (15), ii. the temperature within the loop seal (32) in the return path of the circulation of the solid material, and iii. the pressure difference of the fluidized bed heat exchanger (50), and iv. the temperature of the solid material downstream of the fluidized bed heat exchange unit (58) of the fluidized bed heat exchanger (50), are selected as performance indicators of the process in step a), the method according to claim 1. **Claim 4** i. The process variable of the performance indicator of the pressure difference of the loop seal in the return path (15) includes the total reaction gas flow rate supplied into the reactor (10), the temperature of the product gas upstream of the loop seal (32), and the bed temperature in the reaction chamber (12). ii. The process variable of the performance indicator of the temperature within the loop seal (32) in the return path (15) of the circulation of the solid material includes the total reaction gas flow rate supplied into the reactor (10), the temperature of the product gas upstream of the loop seal (32), and the bed temperature in the reaction chamber (12), the method according to claim 2. **Claim 5** i. The process variable of the performance indicator of the pressure difference of the loop seal in the return path (15) includes the total reaction gas flow rate supplied into the reactor (10), the temperature of the product gas upstream of the loop seal (32), and the bed temperature in the reaction chamber (12). ii. The process variable of the performance indicator of the temperature within the loop seal (32) in the return path (15) of the circulation of the solid material includes the total reaction gas flow rate supplied into the reactor (10), the temperature of the product gas upstream of the loop seal (32), and the bed temperature in the reaction chamber (12). iii. The process variable of the performance indicator of the pressure difference of the fluidized bed heat exchanger includes the total reaction gas flow rate supplied into the reactor (10), the temperature within the loop seal (32) in the return path (15) of the circulation of the solid, the pressure difference of the loop 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 variable of the performance indicator of the temperature of the fluidized bed heat exchanger includes the total reaction gas flow rate supplied into the reactor (10), the temperature within the loop seal (32) in the return path (15), the pressure difference of the loop seal, the gas flow rate to the fluidized bed heat exchanger (50), and the bed temperature in the reaction chamber (12), the method according to claim 3.

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 into the reaction chamber (12).

7. The method according to claim 3, characterized in that the bed temperature is the average bed temperature in the reaction chamber (12) calculated from at least two measurement points in the reaction chamber (12) where at least one is at the grid level of the chamber (12).

8. Creating the multivariable model comprises: - measuring values of predetermined process variables, storing the measured values together with a time stamp, thereby forming historical data of the process variables; - measuring values of performance indicators, storing the measured values together with a time stamp, thereby forming historical data of the performance indicators; - selecting valid historical data using a predetermined data filter; The method according to claim 1, 2 or 3, characterized by comprising the above.

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

10. The method according to claim 9, characterized in that the data filter is configured to approve data not older than two weeks.

11. The method according to claim 8 or 9, characterized in that the data filter is configured to approve data not older than two months.

12. The method according to claim 8, characterized in that the data filter is configured to filter and remove any data from shutdown situations and / or any abnormal operations from the historical data based on predetermined limits of input variables or external information of abnormal operations.

13. The multivariable model is a multivariable linear regression having measured observed values of each of a first number (N) of process variables and different process variables of the process of circulation of the solid material of a second number (P), y ｉ = b ０ + b １ x ｉ，１ + b ２ x ｉ，２ +... b Ｐ x ｉ，Ｐ + ε ｉ where i = 1, 2,... N, The method comprises: y is a performance indicator and x ｉ，１ , x ｉ，２ ,..., x ｉ，ｐ are process variables, where y ｉ , x ｉ１ , x ｉ２ ,..., x ｉｐ reading out the history data of the constant b ０ and the factor b １ , b ２ ,... b Ｐ and solving for performing the fitting by minimizing the sum of the squares of the vertical deviations from each data point to the line that best fits the historical data; The method according to claim 1 or 8, characterized by comprising the above.

14. The method according to claim 13, characterized in that the measured observed value N of the first number is at least 10 times that of at least one process variable of the second number (P).

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

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

17. The method according to claim 16, characterized in that the risk index of each performance indicator is calculated using the anomaly between the modeled value and the measured value.

18. When the reactor (10) comprises at least a first return path (15) between the first solid material separator (14) and the reaction chamber (12) and a second return path (15) between the second solid material separator (14) and the reaction chamber (12), The method according to any one of claims 1 to 17, characterized in that executing the method for the process of circulation of the solid material in the first return path (15) and executing the method for the process of circulation of the solid material in the second return path (15) are separate.

19. A control system (48) for monitoring the process of 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 returning to the reaction chamber (12) via a return path (15) provided with a loop seal, The control system (48) is - access to the performance indicators of the process of circulation of the solid material in the return path (15) and the source history data (401) of the process variables of each performance indicator, - a multivariable model of each performance indicator, - executable instructions that, when executed in the control system, update the multivariable model of each performance indicator using the history data of the predetermined process variables and the performance indicators of the process of circulation of the solid material, resulting in a calibrated multivariable model, comprising a performance modeling unit (400) - an input for receiving measurement data of the process variables and performance indicators of the process of circulation of the solid material, - When executed in the control system, by applying the currently measured value of the process variable to the calibrated multivariable model, determine the modeled value of the performance index, compare the modeled value of each performance index with the respective measured value of the performance index, and check for the presence of an anomaly between the modeled value and the measured value, executable instructions; A performance diagnosis module (404) comprising; A control system, characterized by comprising.

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

21. The control system for monitoring the process of circulation of solid materials 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 fluidized bed heat exchanger (50) in the return path (15), according to claim 21, characterized by measurement sensors for at least the following process variables: pressure sensors (101, 102) for measuring the pressure drop in the loop seal; a temperature sensor (103) in the loop seal (31); a product gas temperature sensor (103) downstream of the separator (14); pressure sensors (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); means for determining the total gas flow to the reactor (10) and the bed temperature in the reaction chamber (12) of the reactor (10).

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