A method of monitoring circulation of solid material in a circulating fluidized bed reactor including a reaction chamber, at least one solid material separator, and a return path between the separator and the chamber. The method includes selecting process variables of the process of circulating of solid material in the return path, and selecting performance indicators of the process of circulation of solid material amongst the selected process variables for each performance indicator of the process of circulation of material, creating a multivariate model for each performance indicator, using history data of the process variables and the performance indicators, determining a modelled value of the performance indicators, by applying current measured values of the process variables to the multivariate model, and comparing the modelled value of each performance indicator to a respective measured value and inspecting a presence of an anomaly between the modelled value and the respective measured value.
Legal claims defining the scope of protection, as filed with the USPTO.
.-. (canceled)
. A method of monitoring a process of circulation of solid material in a circulating fluidized bed reactor, the reactor comprising a reaction chamber, at least one solid material separator, a return path between the at least one solid material separator and the reaction chamber and, in which method, the process of circulation of the solid material comprises arranging solid material to be entrained by gas flow in the reaction chamber, and to entrain further from the reaction chamber to the at least one solid material separator and passing solid material from the solid material separator via a return path to the reaction chamber, the method comprising the following steps:
. A method according to, wherein the multivariate model is updated after a period of time triggered by a lapse of a constant predetermined time interval, or by a trigger input.
. A method according to, wherein, when the reactor comprises at least a first return path between a first solid material separator and the reaction chamber and a second return path between a second solid material separator and the reaction chamber, the method further comprises separately performing the method concerning the process of circulation of the solid material in the first return path and the method concerning the process of circulation of the solid material in the second return path.
. A method according to, wherein the first number of measured observations N is at least ten times the second number (P) of different process variables.
. A method according to, wherein a risk index for each performance indicator is calculated using information of a presence of the anomaly.
. A method according to, wherein calculating the risk index for each performance indicator uses an anomaly between the modelled value and the respective measured value.
. A method according to, wherein:
. A method according to, wherein the aggregate reaction gas flow rate is total flow rate of gas flows into the reaction chamber.
. A method according to, wherein the bed temperature is an average bed temperature in the reaction chamber, which is calculated from at least two measurement points in the reaction chamber, at least one of which is at a grid level of the reaction chamber.
. A method according to, wherein the aggregate reaction gas flow rate is a total flow rate of gas flows into the reaction chamber.
. A method according to, wherein the bed temperature is an average bed temperature in the reaction chamber, which is calculated from at least two measurement points in the reaction chamber, at least one of which is at a grid level of the reaction chamber.
. A method according to, wherein creating the multivariate model comprises:
. A method according to, wherein the data filters are configured to approve data that is not older than two months.
. A method according to, wherein the data filters are configured to filter out from history data at least any data from shut down situations and from any abnormal operation, based on predefined limits for input variables or external information of abnormal operation.
. A method according to, wherein the data filters are configured to approve data that is older than a pre-set quarantine time.
. A method according to, wherein the data filters are configured to approve data that is older than two weeks.
. A control system for monitoring a process of circulation of solid material in a circulating fluidized bed reactor between a reaction chamber and at least one solid material separator, and to the reaction chamber via a return path comprising a loop seal, the control system comprising:
. A control system according to, further comprising measurement sensors for at least the following process variables:
. A control system according to, further comprising:
Complete technical specification and implementation details from the patent document.
This application is a U.S. national stage application of International Patent Application No. PCT/EP2022/063560, filed May 19, 2022, now published as International Publication No. WO 2023/222228 A1 on Nov. 23, 2023.
The present invention relates to a method of monitoring a process of circulation of solid material in a circulating fluidized bed reactor.
The present invention relates to control system for monitoring a process of circulation of solid material in a circulating fluidized bed reactor.
In circulating fluidized bed reactors fine solid material is utilized in the process by fluidizing the solid material to an extent that considerable portion of the material is entrained from the reaction chamber to a at least one solid material separator, from the solid material separator a portion of the solid material separated from gas may be led to a fluidized bed heat exchanger and from the fluidized bed heat exchanger circulated back to the combustion chamber. Such a circulating fluidized bed (CFB) reactor is well applicable to produce power by combustion of fuel in the CFB reactor for generation of steam, in which case, the CFB reactor is usually referred to as a CFB boiler. Likewise, it is also known to utilize a CFB reactor for producing product gas, such as gaseous fuel, resulting in reactions taken place in the CFB reactor. In the case of producing gaseous fuel from solid fuel, the CFB reactor is usually referred to as a CFB gasifier.
Challenging fuels may cause particle agglomeration in the fluidized bed material, which can further lead to more severe sintering of the solid material and eventually to blockage in the solids return system and shutdown of the reactor, if corrective procedures are not started in time. For example, with continuously fluctuating fuel quality, sintering may be impossible for operators to recognize by following the conventional basic operative routine.
U.S. Pat. No. 8,292,977 discloses a system for controlling a circulatory amount of particles in a circulating fluidized bed furnace wherein particles are circulated between a fluidized bed combustion furnace for heating of the particles and a fluidized bed gasification furnace for gasification of raw material through heating of the raw material by the heated hot particles. Control is based on measurement of pressure in the fluidized bed gasification furnace and controlling the exhaust rate from the fluidized bed gasification furnace.
Japanese Patent Document JP4254004B2 discloses a controlling fluidization rate based on estimating external circulation solids in circulating fluidized bed boiler. The estimation is based on measuring temperature and pressure in the reactor, and an external fluidized bed superheater heat exchanger, as well as outlet steam temperature and amount of de-superheating water.
Japanese Patent Document JP4443481B2 relates to a system for diagnosing a flow medium clogging comprising a plurality of differential pressure gauges that measure the differential pressure at a predetermined location in the flow medium circulation path, a plurality of thermometers that measure the temperature at a predetermined location in the flow medium circulation path, provide a determination result display for displaying the fact that the flow medium is clogged and the location where the flow medium is clogged when the determination device determines that the flow medium is clogged.
Even if a circulating fluidized bed (CFB) reactor has it benefit over other combustion technologies, in particular an agglomeration problem relating to the solid material in CFB technology is of concern, since it can lead to unscheduled shutdowns of the plant.
An object of the invention is to provide a method of and a control system for monitoring a process of circulation of solid material in a circulating fluidized bed reactor by means of which unintentional shutdowns can be avoided or at least minimized.
Objects of the invention can be met substantially as is disclosed in the independent claims and in the other claims describing more details of different embodiments of the invention.
According to the invention, a method of monitoring a process of circulation of solid material in a circulating fluidized bed reactor, which reactor comprises a reaction chamber, at least one solid material separator, a return path between the at least one solid material separator and the reaction chamber and, in which method, the process of circulation of solid material comprises arranging solid material to be entrained by gas flow in the reaction chamber, and to entrain further from the reaction chamber to the at least one solid material separator and passing solid material from the solid material separator via the return path to the reaction chamber. The method comprises at least the following steps:
When the modelled value of a performance indicator is determined by making use of on-line values, process variables and the modelled value of the performance indicator is compared to the on-line values of a respective performance indicator, the method provides an effect by means of which possible problems, such as related bed quality and/or risk of sintering of bed material, and/or risk of potential bed material blockages in circulation of solid material can be effectively foreseen so that remedial actions can be taken early enough to maintain the process operational.
According to a preferable aspect of the invention, the method comprises combustion of fuel in the circulating fluidized bed reactor, that is, in a circulating fluidized bed boiler. Thus, according to a preferable aspect of the invention, the reaction chamber is a combustion chamber.
According to another aspect of the invention, the method comprises producing gaseous fuel by transforming combustible substance into gaseous fuel in the circulating fluidized bed reactor, that is, in a circulating fluidized bed gasifier.
According to an aspect of the invention, the method may include, in combination with any other step or steps of the method, indicating to the operator of possible remedial actions to be taken, which controls the circumstances to a direction decreasing the tendency of agglomeration of solid material, including at least one of the following:
According to an aspect of the invention, the comparison between the modelled value of the performance indicators to a respective measured value of each performance indicator in step (d.) above may be based on at least one of the following: difference, absolute value of the difference, or ratio.
According to an aspect of the invention the process of circulation of solid material comprises passing solid material from the separator directly to the reaction chamber via a loop seal, wherein at least:
This aspect relates to an embodiment of the invention where the CFB reactor comprises a loop seal in the return path and the selected performance indicators provides an efficient manner of monitoring the process of circulation of solid material.
According to an aspect of the invention the process of circulation of solid material comprises passing solid material from the separator directly to the reaction chamber via the return path, wherein at least:
This aspect relates to an embodiment of the invention where the return path of the CFB reactor is not provided with a loop seal or the solid material is directed to the reaction chamber from a position upstream the loop seal.
According to an aspect of the invention the process of circulation of solid material comprises passing solid material from the separator via a fluidized bed heat exchanger to the reaction chamber, wherein at least:
This aspect relates to an embodiment of the invention where the selected performance indicators cover a CFB reactor comprising a loop seal and a fluidized bed heat exchanger in the return path. The selected performance indicators provide an efficient manner of monitoring the process of circulation of solid material at some critical positions of the process.
According to an aspect of the invention, the temperature of solid material downstream the fluidized bed heat exchange unit is measured at the bottom portion of the fluidized bed heat exchanger. According to another embodiment of the invention, the temperature of the solids in the fluidized bed heat exchanger is measured at the bottom portion of the fluidized bed, above fluidization nozzles. Generally, the term “downstream the heat exchange unit” may be understood as downstream or below heat exchange tubes of the unit, which extend into the fluidized bed heat exchanger. In other words, the temperature of solid material downstream the fluidized bed heat exchange unit may be measured below the heat exchange unit in the fluidized bed heat exchanger. Further, in terms, the temperature of solid material downstream the fluidized bed heat exchange unit may be measured below the heat exchanger tubes in the fluidized bed heat exchanger and above the fluidization nozzles. The fluidized bed heat exchange unit may be chosen according to the need to be, for example, an evaporator, a superheater or a reheater, to name a few.
According to an aspect of the invention, the process of circulation of solid material comprises passing solid material from the separator directly to the reaction chamber via a loop seal, wherein at least:
According to an aspect of the invention, in the case of a circulating fluidized bed boiler, the product gas can be called flue gas containing products of combustion reactions.
According to an aspect, in the case of a circulating fluidized bed gasifier, when gasifying carbonaceous fuels, such as biofuels or waste derived fuels, air and/or oxygen, as well as steam, may be supplied to the reaction chamber so as to generate product gas in which the main components comprise carbon monoxide CO, hydrogen H, and hydrocarbons CH. The product gas of the circulating fluidized bed gasifier may be called syngas.
According to an aspect of the invention, the process of circulation of solid material comprises passing solid material from the separator directly to the reaction chamber via a loop seal, wherein at least:
According to an aspect of the invention, the reaction gas is air. According to an aspect of the invention, the reaction gas is air, or a mixture of air and recirculated flue gas. According to an aspect of the invention, the reaction gas is pure oxygen. According to an aspect of the invention, the reaction gas is a mixture of oxygen and recirculated product gas. According to an aspect of the invention, in the case of a circulating fluidized bed boiler, the reaction gas can be called combustion gas.
According to an aspect of the invention, the method comprises gasification of fuel in the CFB reactor and the process of circulation of solid material comprises passing solid material from the separator directly to the reaction chamber via a loop seal, wherein at least:
According to an aspect of the invention, the process of circulation of solid material comprises passing solid material from the separator via a fluidized bed heat exchanger to the reaction chamber, wherein at least:
According to an aspect of the invention, the aggregate reaction gas flow rate is total flow rate of gas flows into the reaction chamber of the CFB reactor.
According to an embodiment when the method comprises combustion of fuel in a presence of air, the aggregate reaction gas flow rate is total flow rate of air flows into the reaction chamber of the CFB reactor.
According to an embodiment, where the method comprises combustion of fuel in a presence of air the aggregate air flow rate is a flow rate comprising primary air flows fed into the reaction chamber.
According to an embodiment when the method comprises combustion of fuel in a presence of air, the aggregate air flow rate is a flow rate comprising primary air and secondary air flows fed into the reaction chamber.
According to an embodiment when the method comprises combustion of fuel in a presence of air, the aggregate air flow rate is a flow rate comprising primary air, secondary air, and tertiary air flows fed into the reaction chamber.
According to an embodiment when the method comprises combustion of fuel in a presence of air, the aggregate air flow rate is flow rate comprising primary air and secondary air flows fed into the reaction chamber and air fed into the fluidized bed heat exchanger.
According to an embodiment when the method comprises combustion of fuel in a presence of air, the aggregate air flow rate is a total flow rate of air flows into the reaction chamber and into the fluidized bed heat exchanger.
According to an embodiment when the method comprises combustion of fuel in a presence of air, the aggregate air flow rate is a flow rate comprising primary air and secondary air flows fed into the reaction chamber and the fluidized bed heat exchanger, and into the loop seal.
According to an embodiment when the method comprises combustion of fuel in a presence of air, the aggregate air flow rate is a total flow rate of air flows into the reaction chamber, the fluidized bed heat exchanger and into the loop seal.
According to an aspect of the invention, the process of circulation of solid material comprises passing solid material from the separator via a fluidized bed heat exchanger to the reaction chamber, wherein at least:
According to an aspect of the invention, the aggregate combustion gas flow rate is a total flow rate of combustion gas flows into the reaction chamber of the CFB reactor.
According to an aspect of the invention, the aggregate combustion gas flow rate is a flow rate comprising primary combustion gas flows fed into the reaction chamber.
According to a preferable aspect of the invention, the aggregate combustion gas flow rate is a flow rate comprising primary combustion gas and secondary combustion gas flows fed into the reaction chamber.
According to another preferable aspect of the invention, the aggregate combustion gas flow rate is a flow rate comprising primary combustion gas, secondary combustion gas and tertiary combustion gas flows fed into the reaction chamber.
According to an aspect of the invention, the combustion gas is air and recirculation product gas. According to an aspect of the invention, the combustion gas is oxygen and recirculation product gas. According to an aspect of the invention, the combustion gas is primary air and recirculation product gas. According to an aspect of the invention, the combustion gas is oxygen and recirculation product gas.
According to an aspect of the invention the bed temperature is an average bed temperature in the reaction chamber, which is calculated from at least two measurement points in the reaction chamber, at least one of which is at a grid level of the chamber.
According to an aspect of the invention, creating the multivariate model comprises: measuring values of predetermined process variables, storing the measured values with a time stamp thus forming the history data of process variables, measuring values of performance indicator, storing the measured values with a time stamp thus forming the history data of performance indicators, and selection of valid history data using predetermined data filters.
According to an aspect of the invention, creating the multivariate model comprises: measuring values of predetermined process variables, storing the measured values with a time stamp thus forming the history data of process variables, measuring values of performance indicator, storing the measured values with a time stamp thus forming the history data of performance indicators, selecting valid history data using predetermined data filters, and updating the multivariate model.
According to an aspect of the invention, the data filter is configured to approve data that is older than a pre-set quarantine time. Advantageously, by this way, the model will not be taught with potential abnormal operation values, for example, due to start of agglomeration of solid material in the loop seal. In other words, problem-related data is not used in model training.
Unknown
October 9, 2025
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