A method for controlling an industrial cement manufacturing process, a method for determining one or more burning characteristics of a fuel during an industrial cement manufacturing process, and a cement plant

Abstract

The present disclosure provides a method (1000) for determining one or more estimated burning characteristics of an alternative fuel (Fkiln, Fcalc) during an industrial cement manufacturing process. The alternative fuel is based at least predominantly on one or more renewable raw materials and / or recycled materials. The method includes performing (1100) an online measurement to determine current measurement data ({md}) of the alternative fuel (Fkiln, Fcalc) to be burned during the industrial cement manufacturing process, and determining (1200), based on the current measurement data ({md}), at least an estimated first burning characteristic of the alternative fuel (Fkiln, Fcalc). The estimated first burning characteristics is at least indicative of a calorific value (cv) of the alternative fuel (Fkiln, Fcalc).

Description

[0001] A METHOD FOR CONTROLLING AN INDUSTRIAL CEMENT MANUFACTURING PROCESS, A METHOD FOR DETERMINING ONE OR MORE BURNING CHARACTERISTICS OF A FUEL DURING AN INDUSTRIAL CEMENT MANUFACTURING PROCESS, AND A CEMENT PLANT

[0002] TECHNICAL FIELD

[0003] Embodiments of the present disclosure relate to a method for controlling an industrial cement manufacturing process, in particular an industrial Portland cement manufacturing process, a method for determining, during an industrial cement manufacturing process, one or more estimated burning characteristics of a fuel, and a cement plant.

[0004] BACKGROUND

[0005] Concrete is a long and still widely used building material. Often, concreate is based on Portland cement acting as binder. Portland cement may be made from limestone, certain clay minerals, and gypsum, in kilns using high temperature to split off carbon dioxide and convert the raw material into clinker minerals (clinkerization process). In the kiln, the raw material is heated gradually to clinkerization temperature of e.g. 1450 °C.

[0006] Traditionally, fossil fuels like coal, pet coke, natural gas, and oil are employed as fuel in cement plants, in particular as a combustion source for the clinkerization process. The clinkerization process requires tight control to maintain stable and efficient clinker production. This control is facilitated by using fossil fuels as their calorific values are typically well known and vary not much from batch to batch. Accordingly, using fossil fuels contribute to a high quality of the manufactured cement.

[0007] Document FR 2 611 877 A2 describes a process for regulating a dry process cement manufacturing plant comprising a precalcining chamber, where the raw material is at least partially decarbonated, a tubular rotary kiln equipped with a burner at its clinker outlet end, a heat exchanger, where the raw material is preheated by means of exhaust gases from the rotary kiln and the precalcining chamber, and a clinker cooler. The theoretical amount of heat to be supplied to the kiln is periodically calculated as a function of the characteristics of the raw material and the fossil fuel, the target characteristics for the clinker and the parameters characterizing the operation of the plant. In particular, a calorific value of the solid fossil fuel (coal, lignite, petroleum coke) is determined based on atline measurements, i.e. by measuring (regularly) taken fuel samples (in a lab). Optionally, the quantity of heat supplied by an additional supply of fossil liquid or gaseous fuel, whose calorific value is usually known with sufficient precision, is taken into account. A setpoint value for the fuel flow rate supplied to the kiln is calculated corresponding to the calculated amount of heat, and the current setpoint value of the regulator for the fuel flow rate supplied to the kiln is gradually modified to bring it to the calculated setpoint value.

[0008] However, not least due to the required high temperatures, the carbon footprint of present cement production is large. According to estimates, cement productions currently contributes to about 8% of the worldwide carbon dioxide atmospheric emissions. Both global warming and ocean acidification, which are at least partly caused by carbon dioxide emissions, become an increasing problem. Thus, there is a great desire to reduce these emissions.

[0009] Accordingly, further improving cement manufacturing is desired.

[0010] SUMMARY

[0011] In view of the above, and for other reasons, there is a need for the present invention. Thus, according to the independent claims, respective typically computer-implemented methods, and a cement plant planning system as well as respective computer program products and computer- readable media for performing said methods are provided.

[0012] According to an aspect of the present disclosure, a method for determining one or more estimated burning characteristics of an alternative fuel during an industrial cement manufacturing process is provided. The alternative fuel is based at least predominantly on one or more renewable raw materials and / or recycled materials. The method includes performing an online measurement to determine current measurement data of the alternative fuel to be burned during the industrial cement manufacturing process, and determining, based on the current measurement data, at least an estimated first burning characteristic of the alternative fuel. The estimated first burning characteristics is at least indicative of a calorific value of the alternative fuel.

[0013] Accordingly, using even different types of alternative fuels for the clinkerization process, in particular as main or even only combustion source for cement clinkerization is significantly facilitated. This is because disturbances of the clinkerization process such as instabilities of the clinkerization process, which may otherwise be caused by the typically comparatively large fluctuations of the calorific value of alternative fuels (compared to fossil fuels like coal and pet coke having calorific values which are often well known and vary much less from batch to batch, respectively) can be compensated, even in real time. Note that the other major variables that affect the efficiency of the clinkerization process are raw meal feed rate, air flows, temperature and speed of the kiln. These variables are measurable online and can be further optimized using a multivariable controller such as advanced process control system, if the calorific value of the alternative fuel is measured online, preferably in real time. For example, an online fuel scanner such as a radiometric scanner may provide calorific values in real time that can be fed into an advanced process control system for forecasting, correcting and optimizing total energy release in the clinkerization process / combustion chamber(s).

[0014] In the result, a highly efficient cement manufacturing at same or even lower cost (through the use of waste and / or recycled material as fuel) with reduced carbon footprint can be provided.

[0015] The online measurement as well as determining the estimated burning characteristic(s) is typically done in real time, automatically, contactless, without taking a sample (as required for lab / atline measurements), along a transport route, in particular directly on the feed of the alternative fuel to a combustion chamber of the industrial cement manufacturing process such as the kiln and / or the precalciner, and / or during feeding the alternative fuel to the combustion chamber.

[0016] Typically, the alternative fuel is a non-fossil fuel.

[0017] The alternative fuel may consist of at least 80%, preferably at least 90%, more preferably at least substantially, e.g. completely, of the one or more renewable raw materials and / or recycled materials.

[0018] The alternative fuel may not include fossil fuels such as petroleum, natural gas and coal or a product derived therefrom for primary use such as coke and diesel.

[0019] Further, the alternative fuel may include combustible waste material, in particular combustible industrial waste material, and / or may be derived from combustible waste material.

[0020] The alternative fuel may be an alternative fuel composition and / or include at least one of: plastic waste, rubber waste such as shredded old tires, used oil and organic material such as waste paper, wood residues or would pellets.

[0021] For example, used tires are well suited as an alternative fuel (fuel substitute) in cement plants, because they have a calorific value of approx. 9.0 kWh / kg and a sulphur content of approx. 1.2 %. The combustible components of used tires (textile, rubber, carbon black, etc.) may be used to provide the required combustion energy, while the non-combustible components like steel are oxidized and may be used as additives in the cement production.

[0022] Burning the alternative fuel during the industrial cement manufacturing process is typically expected to reduce a carbon dioxide footprint by at least 20%, preferably at least 40% compared to burning a conventional fuel during the industrial cement manufacturing, such as coal, lignite, petroleum coke or mixtures thereof. The expected first burning characteristic may include the calorific value of the alternative fuel.

[0023] Preferably, the expected first burning characteristic of the alternative fuel and an expected second burning characteristic of the alternative fuel is be determined based on the current measurement data.

[0024] The term “current measurement data” as used herein shall refer to online measured data depending on and / or referring to physical and / or chemical properties of the (alternative) fuel such as particle size, granularity, viscosity, carbon content, hydrocarbon content, moisture content, composition such as chemical composition, and percentage of flammable substances.

[0025] Typically, the online measured data depends on and / or refers to physical and chemical properties of the (alternative) fuel.

[0026] Preferably, the online measured data are determined in real time, i.e. within real time, i.e. with a maximum delay of typically at most about 1 s, 0.5 s or even 0.2 s, or in near real-time, i.e. with a maximum delay of at most about 5 s or even less than 2 s and at the next possible time of the control, respectively, and / or shortly or immediately before burning the alternative fuel (in a combustion chamber), in particular at most 1 min prior to burning the alternative fuel, more preferably at most 20 s or even at most 10 s prior to burning the alternative fuel.

[0027] The expected second burning characteristic is typically at least indicative of a combustibility of the alternative fuel, include the combustibility of the alternative fuel or even be the combustibility of the alternative fuel. The expected second burning characteristics may also be or at least be representative of a particle size of the alternative fuel.

[0028] The term “burning characteristics” as used herein intends to describe parameters of a fuel which determine the properties and behaviors of a fuel (or any other substance) during a combustion process (under defined conditions), in particular the amount and rate of energy released during the combustion. The term “burning characteristics” shall encompass the terms “calorific value”, “combustibility”, “activation energy”, and “reaction rate constant”.

[0029] The term “calorific value” as used herein intends to describe the total energy that is released as heat when a specified amount of a fuel (or any other substance) undergoes complete combustion with oxygen under defined conditions, e.g. at standard conditions (e.g. at standard temperature and pressure).

[0030] The term “combustibility” as used herein intends to describe a measure (or even several measures) of how easily a fuel (or any other substance) bursts into flame through combustion or fire, e.g. at standard conditions. Examples of these measures are particle size, vapor pressure and flame point of the fuel.

[0031] The respective burning characteristic of the alternative fuel, i.e. the expected first burning characteristic and / or the expected second burning characteristic may in particular be calculated based on the current measurement data.

[0032] The respective burning characteristic of the alternative fuel may have an expected variability of at least 5% or even at least 10%, at least on a batch level.

[0033] Performing the online measurement to determine the current measurement data may include at least one of online measuring the current measurement data while the alternative fuel is being transported to and / or fed into a combustion chamber of a cement plant, in particular a cement kiln of the cement plant and / or a precalciner of the cement plant; online measuring the current measurement data while the alternative fuel is located on and / or in: a fuel conveyor belt, an alternative fuel stockpile, a feed chute, an alternative fuel hopper, an alternative fuel bin, a fuel inlet feed of the precalciner and / or a fuel inlet feed of the cement kiln; determining the current measurement data in real time, periodically, and / or at least 6 times per minute, preferably at least 12 times per minute; contactless measuring the current measurement data; and a spectroscopic measurement such as an X-ray fluorescence spectrometry, an infrared spectroscopy, in particular a near infrared spectroscopy, a terahertz spectroscopy or a Raman spectroscopy, and any combination thereof, for example a combination of near-infrared spectroscopy and X-ray fluorescence spectrometry.

[0034] According to another aspect of the present disclosure, a method for controlling an industrial cement manufacturing process, which is in the following also referred to as control method for short, includes determining one or more burning characteristic of an alternative fuel as explained herein, and controlling, based on the one or more estimated first burning characteristics of the alternative fuel, burning the alternative fuel during the industrial cement manufacturing process.

[0035] Preferably, the control method includes determining a currently required combustion energy and / or a currently required combustion rate for the industrial cement manufacturing process, in particular the currently required combustion energy and / or combustion rate for the clinkerization process, and controlling, based on the one or more estimated burning characteristics of the alternative fuel, burning the alternative fuel to provide at least substantially the currently required combustion energy and / or currently required combustion rate.

[0036] Preferably, at least the currently required combustion energy is determined.

[0037] However, more preferably both the currently required combustion energy and the currently required combustion rate are determined.

[0038] In particular, the currently required combustion rate may be determined based on the currently required combustion energy (so that the currently required combustion energy is met). This may facilitate controlling the clinkerization process, as the currently required combustion rate may be directly controlled via the feed rate of the alternative fuel.

[0039] Typically, burning the alternative fuel is controlled to provide / meet the currently desired combustion energy (per time interval) and / or the currently required combustion rate (as function of time), at least within given limits and / or with a given accuracy of at least 2% or even at least 1%.

[0040] The currently required combustion energy and / or the combustion rate is preferably determined based on at least one process parameter of the industrial cement manufacturing process, in particular based on one, several or even all of: a kiln temperature, a kiln velocity, air flow rate, a raw meal quality, a hotmeal quality and a clinker quality such as a (online-measured) free lime content.

[0041] Controlling the burning typically includes at least one of, preferably all of: close-loop control; determining, based on the one or more burning characteristics of the alternative fuel, a required feed rate of the alternative fuel for burning; changing the feed rate of the alternative fuel in accordance with the required feed rate; and controlling the feed rate of the alternative fuel.

[0042] Typically, the feed rate of the alternative fuel is determined (and controlled) such that the currently required combustion energy, preferably the currently required combustion energy and the currently required combustion rate are met.

[0043] Alternatively or in addition, controlling the burning may include taking into account a measured current density of the alternative fuel for determining the required feed rate of the alternative fuel. Alternatively or in addition, controlling the burning may include taking into account a (online) measured (current) density of the alternative fuel for determining the required feed rate of the alternative fuel.

[0044] Moreover, controlling the burning may include taking into account a burning characteristic of and / or an amount of energy a conventional (fossil) fuel like coal or pet coke, which is also to be burned during the industrial cement manufacturing process, and maximizing the feed rate of the alternative fuel while maintaining process stability, in particular maximizing the feed rate of the alternative fuel under the (secondary) constraint of maintaining process stability.

[0045] The currently required combustion energy or combustion rate preferably refers to at least one of: a clinkerization process, a combustion in a cement kiln, and a combustion in a precalciner.

[0046] Likewise, the feed rate of the alternative fuel may refer to a fuel supply of the cement kiln, and / or to a fuel supply of the precalciner.

[0047] The method explained herein may be performed repeatedly and / or periodically, preferably several times per minute, more preferably at least 6 times per minute or even 12 times per minute, for example, once every 5 seconds, once every two seconds or even once every second.

[0048] Further, the method explained herein may be performed by an advanced process control and / or by a plant control system, such as a distributed control system preferably configured to implement the advanced process control (system).

[0049] In particular, the current measurement data of the alternative fuel may be fed into an advanced process control system of the industrial cement manufacturing process to calculate the expected burning characteristics based on the current measurement data.

[0050] Suitable advanced process control (APC) solutions are commercially available (e.g. the APC solution offered by ABB as described in the publication “Advanced Process Control - The proven way to process optimization” available at: https: / / library.e.abb.com / public / fa34b897958489a9cl257ad7005753d5 / Brochure_APC_low.p df), even in the field cement production (e.g. the ABB Ability™ Expert Optimizer for cement).

[0051] The advanced process control (APC) system may include at least one of or even several of a rule-based control, a fuzzy logic control, a model predictive control, a look-up table, an inferential modelling, an artificial neural network, a (deep) neural network such as a recursive neural network, a regression, a principal component analysis, a state space and a Kalman filter.

[0052] According to another aspect of the present disclosure, a cement plant includes a combustion chamber comprising a fuel inlet feed for an alternative fuel, and a measuring device, which is arranged at, in and / or along a transport route for the alternative fuel to the fuel inlet feed and is configured to determine online measurement data of the alternative fuel. The online measurement data allow for determining at least an expected first burning characteristic of the alternative fuel. The expected first burning characteristics is at least indicative of a calorific value of the alternative fuel.

[0053] The measuring device may include or be a respective radiometric device whose measurement data at least allow conclusions to be drawn about the alternative fuel composition, in particular a spectroscopic device such as an X-ray fluorescence spectrometer, an infrared spectrometer, in particular a near infrared spectrometer, a terahertz spectrometer or a Raman spectrometer, and any combination thereof, for example a combination of a near-infrared spectrometer and an X-ray fluorescence spectrometer.

[0054] The measuring device may be implemented as an online radiometric alternative fuel quality analyzer which is configured to online determine the measurement data and provide the estimated burning characteristic(s).

[0055] For example, the measuring device may be similar to on-line radiometric coal quality analyzers used for coal excavation, processing and combustion optimization, which are configured to determine the calorific value (e.g. in MJ / kg or kWh / kg), flow rate (e.g. in t / h) and other values such as ash content of coal on a belt conveyor within specified time intervals, however adapted in software and / or hardware to expected alternative fuels or even alternative fuel compositions.

[0056] The alternative fuel is preferably a non-fossil fuel and / or based at least predominantly on one or more renewable raw materials and / or recycled materials.

[0057] Preferably, the cement plant has a cement plant controller which is functionally connected with the measuring device and configured to perform any of the method as explained herein.

[0058] Further, the cement plant may include a stockpile for the alternative fuel, a fuel inlet feed of the combustion chamber for a conventional fuel preferably at least substantially consisting of coal, lignite, petroleum, coke or mixtures thereof, a stockpile for the alternative fuel, and / or a stockpile for the conventional fuel.

[0059] According to yet another aspect of the present disclosure, a computer program product and / or a (non-volatile) computer-readable medium includes instructions which, when executed by a computing unit, in particular a computing unit of a cement plant controller as explained herein, cause the computing unit to carry out any of the method as explained herein.

[0060] Those skilled in the art will recognise additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

[0061] BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The components in the figures are not necessarily to scale, instead emphasis being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts. In the drawings:

[0063] Fig. 1A is a flow chart of a method for determining one or more estimated burning characteristics according to an embodiment; Fig. IB is a flow chart of a method for controlling an industrial cement manufacturing process according to an embodiment;

[0064] Fig. 1C is a flow chart of a method for controlling an industrial cement manufacturing process according to an embodiment; and

[0065] Fig. 2 is a schematic side section view of a cement plant according to embodiments of the present disclosure.

[0066] DETAILED DESCRIPTION

[0067] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0068] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment applies to a corresponding part or aspect in another embodiment as well.

[0069] Reference will now be made to FIG. 1A which shows the flow chart of a method 1000 for determining estimated burning characteristics.

[0070] In a first block 1100, (current / actual) measurement data {md} of an alternative fuel to be burned in combustion chamber during industrial cement manufacturing are determined.

[0071] Typically, a measuring device or even a measuring system (having two typically different measuring devices or more than two measuring devices) arranged at, in and / or along a transport route for the alternative fuel is used for online determining the measurement data {md}. Measurement (scanning) of the physical and chemical properties of the alternative fuel may be performed at the main fuel conveyor belts, sub alternative fuel conveyor belts, alternative fuel stockpiles, feed chutes, alternative fuel hopper, alternative fuel bin, calciner and / or kiln fuel inlet feed.

[0072] Preferably, an online radiometric alternative fuel quality analyzer is used as (respective) measuring device.

[0073] Thereafter, in a block 1200, the current measurement data {md} are used to determine at least one estimated burning characteristic 1 cv, cc} of the alternative fuel.

[0074] In the exemplary embodiment, estimated first and second burning characteristics cv, ccof the alternative fuel are determined: a calorific value cvof the alternative fuel and a combustibility ccof the alternative fuel.

[0075] In other embodiments, only the calorific value cvof the alternative fuel or more than two estimated burning characteristics are determined.

[0076] The estimated burning characteristic(s) of the alternative fuel may be determined from a lookup table and / or be calculated (online) using the current measurement data {md} as input (of a model).

[0077] In particular, the estimated burning characteristic(s) of the alternative fuel may be determined by the measuring device itself, in particular the online radiometric alternative fuel quality analyzer, or by an advanced process control system for the industrial cement manufacturing process and a cement plant, respectively.

[0078] Further, the APC system may adjust the estimated burning characteristic(s) of the alternative fuel received from the measuring device to the conditions in the combustion chamber, in particular the higher temperatures in the combustion chamber compared to the temperatures of the online measurements outside the combustion chamber. As indicated by the dashed arrow in Fig. 1A, blocks 1100 - 1200 may be performed several times and in a cyclic manner, respectively.

[0079] Fig. IB shows a flow chart of a method 2000 for controlling an industrial cement manufacturing process. Method 2000 is typically performed by an APC system.

[0080] In a first block 2100, one or more estimated burning characteristics {Cy , cc} of an alternative fuel are determined as explained above with respect to Fig. 1 A. In particular, block 2100 may correspond to method 1000.

[0081] In a subsequent block 2100, the one or more estimated burning characteristics are used for controlling the burning of the alternative fuel in a combustion chamber, in particular in a kiln of a cement plant, a precalciner of the cement plant or even in both the kiln and the precalciner.

[0082] In particular, a control command cmd for a supply of the alternative fuel may be determined so that a currently required combustion energy and / or a currently required combustion rate in the respective combustion chamber is (expected to be) met.

[0083] For example, the control command cmd may be issued to set a feed rate of the alternative fuel in accordance with a (currently) required feed rate to achieve the currently required combustion energy and / or a currently required combustion rate.

[0084] The control command cmd may be determined based on the calorific value cvof the alternative fuel and optionally based on the combustibility ccof the alternative fuel corresponding to a single measurement, or preferably to respective averaged values of e.g. five or ten measurements (e.g. by upsampling the respective values, particularly temporally upsampling the respective values). Accordingly, variations of the properties of the alternative fuel transported to the burning chamber can be taken into account for the control with only moderate changes to the control signals. This may be desirable for reasons of process stability.

[0085] Preferably, method 2000 implements a close-loop control. As indicated by the dashed arrow in Fig. IB, blocks 2100 - 2200 may be performed several times and in a cyclic manner, respectively.

[0086] Fig. 1C shows a flow chart of a method 2001 for controlling an industrial cement manufacturing process. Method 2001 is typically similar to method 2000 explained above with respect to Fig. IB and may also be performed by an APC system.

[0087] However, method 2001 further has a block 2200 in which the currently required combustion energy and / or the currently required combustion rate Prfor the industrial cement manufacturing process is determined and fed to block 2300 for determining the control command cmd.

[0088] The currently required combustion energy and / or the currently required combustion rate Prmay be determined based on (further) process parameters of the industrial cement manufacturing process, in particular a temperature and a speed in the combustion chamber, temperature Tkilnof the kiln and process velocity vkiinof kiln in the exemplary embodiment. Other process parameters that may additionally be taken into account for determining the control command cmd are the air flow rate, a raw meal quality and a clinker quality such as a such as a free lime content of the raw meal fed into the kiln and the precalciner, respectively. These process parameters may also be measured online.

[0089] Preferably, the currently required combustion energy and / or the currently required combustion rate Pris determined such that a stability criterion in the combustion chamber is met.

[0090] In particular, burning the alternative fuel may be controlled, e.g. via the feed rate of the alternative fuel under the additional constraint of maintaining process stability in the combustion chamber.

[0091] Accordingly, instability and / or inefficient combustion may safely be avoided. This also applies to embodiments in which an additional supply of fossil fuels is used for generating the currently required combustion energy and / or the currently required combustion rate.

[0092] In these embodiments, the control preferably tries to maximize contribution of the alternative fuel to the total required currently required combustion energy / rate, e.g. tries to maximize the feed rate of the alternative fuel, under the constraint of the maintaining process stability.

[0093] In particular, the advanced process control (APC) system, more particular its fuel management system, may maximize the alternative fuel consumption and minimize (traditional) fossil fuel consumption whilst maintaining stable energy into the clinkerization process.

[0094] Prior to the actual typically close-loop controlling, in particular by the (closed loop) APC system, one or more of the following processes may be performed: determining properties of the alternative fuels that can relate via calculation or inference to the calorific value and / or combustibility (by or based on online measurement s)), determining calorific value of the alternative fuel (by or based on online measurement(s)), in particular numerically determining the calorific value based on online measurement(s), determining combustibility of the alternative fuel (by or based on online measurement(s)), in particular numerically determining the combustibility based on online measurement(s), determining a mass of alternative fuels (by or based on online measurement s)), determining the particle size of alternative fuels (by or based on online measurement s)), and determining the currently required (total) energy (for the clinkerization process) based on: typically averaged calorific value of the alternative fuel, and typically at least one of typically averaged combustibility of the alternative fuel, and

[0095] (total) mass of the alternative fuel.

[0096] Reference will now be made to Fig. 2, which shows a schematic side view of a cement plant 500 having a cement kiln 100 with a cement preheater 10. Cement plant 500 may have a plurality of cement kilns 100.

[0097] The exemplary cement kiln 100 includes a rotary kiln 20 having kiln entrance 21 into which hotmeal exiting from the cement preheater 10 is fed, and the rotation of the rotary kiln 20 causes it gradually to move downhill to the other end of the rotary kiln 20.

[0098] The cement preheater 10 maybe a gas-suspension preheater, whereby hot exhaust gas Ekilnfrom the rotary kiln 20 is passed through a suspension of hotmeal so as to preheat the hotmeal. Additionally, the cement preheater 10 causes the hotmeal to be calcinated. The cement preheater 10 allows for high efficiency of the cement kiln 100 through heat transfer from the exhaust gas to the hotmeal. The hotmeal preheating takes place in a number of cement cyclones 11 - the cement preheater 10 as exemplarily shown in the figures includes two cement cyclones 11 cascaded in series. However, the cement preheater 10 may include any number of cement cyclones 11, arranged in series, in parallel, or in series-parallel combinations.

[0099] To further improve efficiency, the cement preheater 10 as exemplarily shown may optionally include a cement precalciner 12. Hot air Ecoolerexhausted from the cooler 30 is provided to the cement precalciner 12, as well as a precalciner fuel Fcalc. By combusting additional fuel in the precalciner 12, the hotmeal is further heated to a higher temperature than is possible with kiln exhaust only, allowing the hotmeal to be calcinated to a higher level and improving throughput. By implementing a cement preheater 10 with cement cyclones 11 and cement precalciner 12 for preheating the raw meal, a hotmeal may be prepared typically having a temperature of 700°C to 900°C with up to 90% calcination prior to entering the rotary kiln 20.

[0100] At the other end of the rotary kiln 20, a kiln fuel Fkiinis input via fuel inlet feed 20i for producing a large flame in the lower part of the rotary kiln 20. As hotmeal moves under the flame, it reaches its peak temperature, before dropping out of the rotary kiln 20 as clinker C into the cooler 30. Cooling air is provided by air blowers 32 and is drawn first through the cooler 30 and then exhausted through the rotary kiln 20 for combustion of the kiln fuel Fkiln. A portion of the cooler exhaust Ecooleris directed through a tertiary air pipe 31 for combustion in a precalciner 12.

[0101] In the context of the present disclosure, the term “raw meal” refers to the raw ingredients provided into the cement kiln 100 at the input to the cement preheater 10. The raw meal includes a ground mixture of limestone, clay or shale used for generating cement clinker. On the other hand, the term “hotmeal” refers to the ingredients of the raw meal at any point after drying and before clinkering. In other words, the term “hotmeal” refers to the partially- or completely-calcined kiln feed material present in the cement preheater 10, at any location in the cement preheater 10 between a point of initial drying of the raw meal and the point of entry into the rotary kiln 20. Further, in the context of the present disclosure, the term “clinker” refers to the solid material produced by a cement kiln such as the cement kiln 100, as a result of sintering of the hotmeal provided to the rotary kiln 20.

[0102] When referring to a raw meal quality (e.g. a raw meal lime content, a raw meal sulphur content, raw meal alkali content, etc.), the quality is to be thought of as a value which is preferably online measured before entry into the cement preheater or is measured / estimated from a sample of raw meal taken before entry into the cement preheater. Similarly, when referring to a hotmeal quality (e.g. a hotmeal sulphur content, hotmeal alkali content, etc.), the quantity is thought of as a value which is preferably online measured or is measured / estimated from a sample of hotmeal taken from any point in the cement preheater 10, including but not limited to the cement cyclones 11, the precalciner 12 and any ducting therebetween. Further, when referring to a clinker quality (e.g. a free lime content, a clinker sulphur content, etc.), the quality is thought of as a value which is preferably online measured or is measured / estimated from a sample of clinker taken at any point from the exit of the rotary kiln 20. That is, the clinker may be sampled prior to being cooled by the cooler 30, or after exiting the cooler 30.

[0103] In the exemplary embodiment, kiln fuel Fkiinis an an alternative (non-fossil) fuel as described herein, e,g, plastic waste or rubber waste.

[0104] Along a transport route for the alternative fuel Fkiln, for example at an alternative fuel conveyor belt, a measuring device D is arranged for online determining measurement data {md} of the alternative fuel Fkilnwhile the alternative fuel Fkiinis transported to / fed via the fuel inlet feed 20i into rotary kiln 20.

[0105] Measuring device D may be configured to send the measurement data {md} to a cement plant controller 200 which is functionally connectable with the measuring device D, for example via a wireless or wired data connection, in particular a data connection for interfacing with a data network such as a respective Internet Protocol (IP) network or a network based on serial-based protocols such as CAN.

[0106] Cement plant controller 200 may be provided or include a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and / or other programmable circuits, and may include memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), and computer readable nonvolatile medium. Further, controller 200 may be a plant control system, such as a respective distributed control system. Based on the received measurement data {md}, cement plant controller 200 may determine an expected first burning characteristic of the alternative fuel Fkiln, in particular a calorific value cvof the alternative fuel Fkiln, or the expected first burning characteristic and an expected second burning characteristics of the alternative fuel of the alternative fuel Fkiln, in particular a combustibility ccof the alternative fuel Fkiln.

[0107] Alternatively or in addition, measuring device D is configured to determine the expected burning characteristic(s) { cv, cc} and send the burning characteristic(s) {cv, cc} to cement plant controller 200.

[0108] In particular, measuring device D may be an online radiometric alternative fuel quality analyzer.

[0109] Based on process parameters such as the temperature Tkiinof rotary kiln 20 and the process velocity vkjinof rotary kiln 20, which may be directly measured or determined based on (online) measurements, as measured by the exemplary sensor S, cement plant controller 200 may determine a currently required combustion energy for rotary kiln 20 so that production requirements of the cement kiln 100 are expected to be met, in particular required quantity and / or quality requirements for the clinker C such as a (required) clinker rate of production Coutand a (required) clinker composition.

[0110] Typically, beside temperature Tkilnand the process velocity vkjin, a plurality of further process parameters is taken into account by controller 200 for determining the currently required combustion energy, in particular raw meal feed rate, raw meal quality, an air flows.

[0111] Based on the currently required combustion energy and the determine the expected burning characteristic(s) {cv, cc}, cement plant controller 200 may determine, typically calculate the currently required combustion rate for rotary kiln 20.

[0112] Thereafter, cement plant controller 200 may calculate a corresponding feed rate of the alternative fuel (corresponding to the currently required combustion rate of the alternative fuel for rotary kiln 20), and issue a corresponding control command cmd to an alternative fuel feed control device FC. Upon receiving control command cmd, fuel feed control device FC changes the feed rate of the alternative fuel accordingly.

[0113] Preferably, cement plant controller 200 implements APC-functionality for manufacturing the clinker with cement kiln 100.

[0114] In particular, cement plant controller 200 may implement a closed loop APC system.

[0115] As shown in Fig. 2, rotary kiln 20 may additionally be provided with a fuel inlet feed for a conventional fuel Fckiinto be burned (if required).

[0116] In this embodiment, in which both fuel types Fkilnand Fckiinare available, cement plant controller 200 typically maximizes the feed rate of the alternative fuel while maintaining process stability.

[0117] For example, conventional kiln fuel Fckiinmay be use, at least temporarily, only to compensate for undesirable fluctuations in the calorific value (and / or the combustibility) of alternative kiln fuel Fkiln, in particular fluctuations in the calorific value of the alternative kiln fuel Fkilnto lower values that would otherwise require high feed rates of the alternative kiln fuel Fkiln, which may cause a combustion instability.

[0118] The burning characteristic(s) of the conventional kiln fuel Fckiin, in particular at least its calorific value and preferably also the combustibility of the conventional kiln fuel Fckiinmay also be determined online, e,g, be provided to cement plant controller 200 by a respective on-line (radiometric) fuel quality analyzer (not shown) such as an on-line radiometric coal quality analyzer.

[0119] As further shown in Fig. 2, alternatively or in addition, cement plant controller 200 may, similar as explained for rotary kiln 20, control burning of alternative precalciner fuel Fcaic(that may be provided via alternative fuel inlet feed 12i) and optionally conventional precalciner fuel Fccaicin precalciner 12 of cement kiln 100.

[0120] However, for reasons of clarity, the typically existing measuring device(s) for online determining the burning characteristic(s) of precalciner fuel Fcalc(and optionally Fccaic) and sensor(s) for online determining process param eter(s) of cement preheater 10 and a fuel feed control device for alternative precalciner fuel Fcalcare not shown in Fig. 2.

[0121] According to an embodiment, the same alternative fuel is used as alternative kiln fuel Fkilnand alternative precalciner fuel Fcalc. In this embodiment, one measuring device D may be sufficient for providing the the burning character! stic(s) of the alternative fuel.

[0122] According to an embodiment, which may be combined with other embodiments described herein, a typically computer-implemented method for controlling an industrial cement manufacturing process includes determining an estimated burning characteristics of an alternative fuel while the alternative fuel is fed towards and / or into a combustion chamber of the industrial cement manufacturing process, typically in real time, and controlling, based on the estimated burning characteristic of the alternative fuel, burning the alternative fuel in the combustion chamber.

[0123] By determining burning characteristic(s) of the alternative fuel(s) based on online measurements of physical and / or chemical properties of the alternative fuel(s) in real time and / or during feeding the alternative fuel(s) towards combustion chamber(s) of cement kilns, and controlling the burning of the alternative fuel(s) based on the burning character! stic(s), preferably using advanced process control and / or further based on process parameters typically also determined online and / or in real time, the alternative fuel usage of cement plant may be maximized whilst maintaining stable combustion conditions. This leads to a lower ratio of conventional fuel (e.g. coal) to alternative fuel(s), reduced fuel costs and an improved CO2plant footprint. Although various exemplary embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that various changes and modifications can be made which will achieve some of the advantages of the invention without departing from the spirit and scope of the invention. It will be obvious to those reasonably skilled in the art that other components performing the same functions may be suitably substituted. It should be mentioned that features explained with reference to a specific figure may be combined with features of other figures, even in those cases in which this has not explicitly been mentioned.

[0124] Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper” and the like are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc. and are also not intended to be limiting. Like terms refer to like elements throughout the description.

[0125] As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

[0126] With the above range of variations and applications in mind, it should be understood that the present invention is not limited by the foregoing description, nor is it limited by the accompanying drawings. Instead, the present invention is limited only by the following claims and their legal equivalents. Reference numbers

[0127] 10 Cement preheater vuin process velocity of kiln

[0128] 11 Cement cyclone 200 plant controller

[0129] I la Cyclone barrel 500 cement plant

[0130] 1 lb Cyclone exit

[0131] 11c Cyclone exhaust l id Cyclone entry

[0132] 12 Precalciner

[0133] 12i alternative fuel inlet feed

[0134] 20 Rotary kiln

[0135] 20i alternative fuel inlet feed

[0136] 31 Kiln entrance

[0137] 30 Clinker cooler

[0138] 31 Tertiary air pipe

[0139] 32 Air blower

[0140] 100 Cement kiln

[0141] C Clinker

[0142] Cout Clinker rate of production cv1stburning characteristic

[0143] (calorific value) cc2ndburning characteristic

[0144] (combustibility)

[0145] D, S measuring device / sensor

[0146] Ecooier Cooler exhaust

[0147] EkiinKiln exhaust

[0148] EoutExhaust out

[0149] FC alternative fuel control device

[0150] Fcaicalternative precalciner fuel

[0151] Fccaicconventional precalciner fuel

[0152] Fkiin alternative kiln fuel

[0153] Fckiin conventional kiln fuel

[0154] Tkiin temperature of kiln

[0155] Rinraw meal input

Claims

Claims1. A method (1000) for determining one or more estimated burning characteristics of an alternative fuel (Fkiin, Fcaic) during an industrial cement manufacturing process, the alternative fuel (Fkiin, Fcaic) being based at least predominantly on one or more renewable raw materials and / or recycled materials, the method comprising:• performing (1100) an online measurement to determine current measurement data ({md}) of the alternative fuel (Fkiln, Fcalc) to be burned during the industrial cement manufacturing process; and• determining (1200), based on the current measurement data ({md}), at least an estimated first burning characteristic of the alternative fuel (F iin, Fcaic), the estimated first burning characteristic at least being indicative of a calorific value (Cy) of the alternative fuel (Fkiin, Fcaic).

2. The method (1000) of claim 1, wherein determining (1200) at least the expected first burning characteristic of the alternative fuel (Fkiin, Fcaic) comprises determining, based on the current measurement data, the expected first burning characteristic (cc) of the alternative fuel (Fkiin, Fcaic) and an expected second burning characteristic of the alternative fuel (Fkiin, Fcaic), the expected second burning characteristics at least being indicative of a combustibility (cc) of the alternative fuel.

3. The method (1000) of any of the preceding claims, wherein the expected first burning characteristic comprises the calorific value of the alternative fuel and / or wherein the expected second burning characteristic comprises the combustibility of the alternative fuel.

4. The method (1000) of any of the preceding claims, wherein determining (1200) at least the expected first burning characteristic of the alternative fuel (Fkiin, Fcalc) comprises:• calculating at least the expected first burning characteristic based on the current measurement data ({md}).

5. The method (1000) of any of the preceding claims, wherein the respective burning characteristic of the alternative fuel is expected to have and / or comprise a variability of at least 5% or even at least 10%.

6. The method (1000) of any of the preceding claims, wherein the alternative fuel is a non-fossil fuel, and / or wherein the alternative fuel (F^in, Fcaic) consists of at least 80%, preferably at least 90%, more preferably at least substantially, e.g. completely, of the one or more renewable raw materials and / or recycled materials, and / or wherein the alternative fuel comprises combustible waste material, in particular combustible industrial waste material, and / or is derived from combustible waste material, and / or wherein burning the alternative fuel during the industrial cement manufacturing process is expected to reduce a carbon dioxide footprint by at least 20%, preferably at least 40% compared to burning a conventional fuel during the industrial cement manufacturing, such as coal, lignite, petroleum coke or mixtures thereof, and / or wherein the alternative fuel does not include fossil fuels such as petroleum, natural gas and coal or a product derived therefrom for primary use such as coke and diesel, and / or wherein the alternative fuel is an alternative fuel composition and / or comprises at least one of: plastic waste, rubber waste such as shredded old tires, used oil and organic material such as waste paper, wood residues or would pellets.

7. The method (1000) of any of the preceding claims, wherein performing (1100) the online measurement comprises at least one of:• online measuring the current measurement data ({md}) while the alternative fuel (Fkiin, Fcaic) is being transported to and / or fed into a combustion chamber of a cement plant (500), in particular a cement kiln (100) of the cement plant (500) and / or a precalciner (12) of the cement plant (500);• online measuring the current measurement data ({md}) while the alternative fuel (Fkun, Fcalc) is located on and / or in: a fuel conveyor belt, an alternative fuel stockpile, a feed chute, an alternative fuel hopper, an alternative fuel bin, a fuel inlet feed (21 i) of the precalciner (12) and / or a fuel inlet feed (20i) of the cement kiln (100);• determining the current measurement data ({md}) in real time, periodically, and / or at least 6 times per minute, preferably at least 12 times per minute;• contactless measuring the current measurement data ({md}); and• a spectroscopic measurement such as an X-ray fluorescence spectrometry, an infrared spectroscopy, in particular a near infrared spectroscopy, a terahertz spectroscopy or a Raman spectroscopy, and any combination thereof, for example a combination of near-infrared spectroscopy and X-ray fluorescence spectrometry.

8. A method (2000, 2001) for controlling an industrial cement manufacturing process, the method comprising:• determining (2100) one or more estimated burning characteristics (Cy, cc) of an alternative fuel (Fkiin, Fcaic) in accordance with the method (1000) of any of the preceding claims; and• controlling (2300), based on the one or more estimated burning characteristics of the alternative fuel (Fkiin, Fcalc), burning the alternative fuel during the industrial cement manufacturing process.

9. The method (2001) of claim 8, comprising:• determining (2200) a currently required combustion energy and / or the currently required combustion rate (Pr) for the industrial cement manufacturing process; and• controlling (2300), based on the one or more estimated first burning characteristics of the alternative fuel (Fkiln, Fcalc), burning the alternative fuel to provide at least substantially the currently required combustion energy and / or the currently required combustion rate.

10. The method (2001) of claim 9, wherein the currently required combustion energy and / or the currently required combustion rate (Pr) is determined based on at least one process parameter (Tkiln, vkiin) of the industrial cement manufacturing process.

11. The method (2000, 2001) of any of claims 8 to 10, wherein controlling (2300) the burning comprises at least one of, preferably all of:• close-loop control;• determining, based on the one or more burning characteristics of the alternative fuel (Fkiin, Fcalc), a required feed rate of the alternative fuel for burning;• changing the feed rate of the alternative fuel in accordance with the required feed rate; and• controlling the feed rate of the alternative fuel.

12. The method (2000, 2001) of claim 11, wherein controlling (2300) the burning comprises:• taking into account a measured current density of the alternative fuel for determining the required feed rate of the alternative fuel.

13. The method (2000, 2001) of any of claims 8 to 12, wherein controlling (2300) the burning comprises at least one of, preferably all of:taking into account a burning characteristic of a conventional fuel (Fenin) to be burned during the industrial cement manufacturing process, and maximizing the feed rate of the alternative fuel while maintaining process stability.

14. The method (2000, 2001) of any of the proceeding claims 9 to 13, wherein the currently required combustion energy and / or the currently required combustion rate refers to at least one of: a clinkerization process, a combustion in a cement kiln (100), and a combustion in a precalciner (12), and / or wherein the feed rate of the alternative fuel refers to a fuel supply of the cement kiln (100), and / or wherein the feed rate of the alternative fuel refers to a fuel supply of the precalciner (12).

15. The method (2000, 1000) of any of the proceeding claims, wherein the method is performed repeatedly and / or periodically, preferably several times per minute, more preferably at least 6 times per minute or even 12 times per minute, for example, once every 5 seconds, once every two seconds or even once every second.

16. The method (2000, 1000) of any of the proceeding claims, wherein the method is performed by an advanced process control (APC) and / or by a plant control system, such as a distributed control system preferably configured to implement the advanced process control, and / or wherein the current measurement data ({md}) of the alternative fuel are fed into an advanced process control system of the industrial cement manufacturing process to calculate the expected first burning characteristic based on the current measurement data ({md}).

17. The method (2000, 1000) of claim 16, wherein the advanced process control and / or the plant control system comprises at least one of a rule-based control, a fuzzy logic control, a model predictive control, a look-up table, an inferential modelling, anartificial neural network, a deep neural network such as a recursive neural network, a regression, a principal component analysis, a state space and a Kalman filter.

18. A cement plant (500), comprising;• a combustion chamber comprising a fuel inlet feed ( 12i, 20i) for an alternative fuel (Fkiin, Fcaic); and• a measuring device (D) arranged at, in and / or along a transport route for the alternative fuel (Fkiln, Fcalc) to the fuel inlet feed (12i, 20i) and being configured to determine online measurement data ({md}) of the alternative fuel (Fkiin, Fcaic), the online measurement data ({md}) allowing for determining at least an expected first burning characteristic of the alternative fuel (Fkiln, Fcalc), the expected first burning characteristics at least being indicative of a calorific value of the alternative fuel.

19. The cement plant (500) of claim 18, further comprising at least one of• a cement plant controller (200) functionally connected with the measuring device (D) and configured to perform the method of any of the claims 1 to 17;• a stockpile for the alternative fuel;• a fuel inlet feed of the combustion chamber for a conventional fuel (Fcknn, Fccaic) preferably at least substantially consisting of coal, lignite, petroleum, coke or mixtures thereof;• a stockpile for the alternative fuel; and• a stockpile for the conventional fuel, wherein the alternative fuel (Fkiln, Fcalc) is preferably a non-fossil fuel and / or based at least predominantly on one or more renewable raw materials and / or recycled materials.

0. A computer program product or a computer-readable medium comprising instructions which, when executed by a computing unit, in particular a computing unit of a cement plant controller (200), cause the computing unit to carry out the method of any of the claims 1 to 17.

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