Patent Description:
In particular, the present invention relates to a system and method configured to detect physical characteristics such as dimensions and average weight of wood pellets, provided, in particular, for being burned in thermal power plants arranged for the generation, for example, of thermal and/or electric energy.

Wood pellets (pellets) are a biofuel obtained by pelletizing wood, for example obtained from production waste (such as planing waste, sawdust, chips, cuttings) or from virgin wood trunks.

The main objective of pelletizing is to dimensionally standardize the biofuel obtainable from wood. The result of the pelletization is a densified product or pellet of cylindrical shape and small size which allows the product, despite being solid, to take characteristics similar to those of biomass comprised of liquids or fluids.

In particular, pellets have the ability to be easily transportable and storable thanks to the fact that they have a shape and size such as to fill small space.

Furthermore, pellets, in view of their combustion, can be managed automatically by way of augers or pneumatic modules to automatically feed thermal power plants or boilers, even the residential ones.

Therefore, thanks to their physical characteristics, wood pellets have many advantages compared to common firewood as they can be managed as a fluid.

As it is known, pellet physical characteristics are defined in various international standards and provide for a slightly variable diameter, for example among <NUM> and <NUM>, and for a very variable length, for example among <NUM> and <NUM>, even within the same supply or consignment.

A highly variable distribution of pellet physical characteristics can create different types of problems.

A first problem is that the transport of pellets, for example by way of a metering screw in automatic combustion feeding systems, is difficult if pellets are of very variable dimensions.

As a matter of fact, the variability of the dimensions directly affects the non-adherence to the fluid dynamics.

For example, a standardization of the dimensions within the ranges provided by the standards, ensures that the overall behavior of pellets, as a whole, is similar to that of liquids, in particular as regards the movement and occupation of spaces.

On the contrary, a high variability of the dimensions causes that empty spaces are created among the pellets so as to not allow a generally uniform behavior and to cause blocks, empty pockets and, consequently, a locally chaotic behavior.

Therefore, the variability of the average pellet dimensions affects both the regularity of boiler feeding and of optimization of storage volumes.

Furthermore, the greater adherence, of the pellet flow to a liquid flow, significantly improves the efficiency in the combustion chamber and consequently also provides an economic impact and an improvement in energy yield.

In summary, a reduced variability of the average pellet dimensions allows better efficiency in storage and handling and, in general, provides economic savings, in particular, as regards the use of the pellets for the production of thermal and/or electric energy.

A second problem, related to the first, is that the dimensions of the pellets, in particular in length, directly influence the "BULK DENSITY" and the energetic mass ("BULK") of the pellets.

This second problem provides important consequences on the combustion performance of the pellets as it affects the balance between combustible and comburent, and the emissions of flue gas due to the combustion.

As a matter of fact, the mass of the biofuel based on pellets depends on its "BULK DENSITY" and therefore on the distribution, in particular, of the average lengths of the pellets comprised in a certain supply.

For example, in a boiler the feed volume of the pellets (fuel) and the flow rate of the comburent for the combustion of the pellets will be influenced by the average dimensions of the pellets and therefore, in the event of a distribution of the average pellet dimensions in a very wide range, the combustion will not always be optimal.

As a matter of fact, pellets with high "BULK DENSITY" and high energetic mass ("BULK") will require, for the same volume, a greater flow rate of comburent to ensure complete combustion of the pellets and to avoid harmful emissions into the atmosphere.

On the contrary, with the same volume, pellets with low "BULK DENSITY" and low energy mass ("BULK") will require a lower combustion flow rate or a greater quantity of pellets to ensure complete combustion of the pellets and to avoid harmful emissions into the atmosphere.

The problem therefore emerges that, depending on the functional characteristics of each boiler, there will be optimal average values that allow the boiler to operate in the most efficient way possible from a thermal point of view.

In other words, there will be average values of the pellet dimensions depending on the specific characteristics of each type of boiler and it will be very important to solve the problem of knowing the distribution of the average pellet dimensions to ensure that these average dimensions are optimal for the type of boiler provided.

In summary, if a certain type of boiler works better with pellets in a certain size range, it will be appropriate to solve the problem of knowing for each supply not only the fact that the pellets have dimensions such as to optimize logistical aspects but also the fact that the dimensions are such to optimize aspects related to the thermal efficiency of the boilers.

From the above it emerges that the average physical characteristics of the pellets are of great importance to allow an optimal exploitation of the pellets as biofuel in the thermal power plants.

In order to know the average physical characteristics of a pellet supply, it is known that thermal plants, for example for industrial use, provide, directly or through appropriate laboratories, to carry out a sampling of the various supplies or consignments of pellets purchased, to verify the average physical characteristics thereof.

In particular, according to the prior art, it is provided that thermal plants or laboratories randomly extract, for example from each consignment, a certain number of pellets and subject them to a set of manual measurements to verify that the physical characteristics of the consignment fall within the average characteristics provided for in the purchase order and/or in specific standards for pellets.

The more general problem of the known process, completely manual, is that this process is expensive, ineffective, subject to even gross human errors, so there is a need to make this process less expensive, more effective and not subject to human errors.

It is also known some method and system for measuring physical characteristics of pellets or fruits or for implementing other features linked to the measurement of physical characteristics of pellets or fruits.

The known method is directed to optically measure at a certain rate wood pellet sizes by using a device comprising a LED panel and a RGB sensor.

The known method is useful for measuring a lot of pellets at a very high rate but provides some problem of precision.

From <CIT> it is known a Device for measuring a pellet size.

The device shows the problem to be very complex because it comprises a sensor made of an optical transmitter and the optical receiver symmetrically arranged on both sides of an electric translation stage.

For instance, from <CIT> it is known a legume sorting system, from <CIT> it is known a system and method for enabling graphic-based interoperability between computer executed operations and from <CIT> it is known an analysis system for rice ear traits based on LED red light transmission imaging.

The above other systems and methods do not solve the problem solved by the present invention.

The automation of the procedure for detecting pellet physical characteristics, however, is not trivial as it requires the combination of hardware devices and software modules in general not easily predictable in advance.

In summary, Applicant has noted that, although the need to measure the average physical characteristics of wood pellets is strongly felt as it is decisive for solving possible logistical problems and for identifying correct combustible/comburent ratios, the prior art is not able to solve the more general problem of automating the measurement of the physical pellet characteristics in an effective and accurate way.

As a matter of fact, the known art seems not able to effectively automate the measurement of pellet physical characteristics in a technically and economically feasible way.

The object of the present invention is to solve the more general problem described above of measuring the average physical characteristics of wood pellets.

Such an object is achieved by way of the system and method for measuring the physical characteristics of wood pellets as claimed.

The present invention also relates to a device provided in the system of the invention.

The claims as well as the description and figures are an integral part of the technical teaching provided herein about the invention.

The following summary of the invention is provided in order to provide a basic understanding of some aspects and features of the invention.

This summary is not an extensive overview of the invention, and as such it is not intended to particularly identify key or critical elements of the invention, or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented below.

According to a feature of the present invention, the system comprises a hardware device and program modules or software modules implemented, preferably, on a microprocessor.

One of the non-obvious choices underlying the system is to comprise an infrared (IR) sensor in the device and to comprise, among the program modules, an image conversion module, wherein the conversion module is configured to convert the scanned image, acquired by the IR sensor, to black and white, i.e. to a grayscale image.

Applicant has indeed noted, experimentally, that the use of an IR sensor and that the subsequent conversion of the image to black and white provides many advantages in order to fully and effectively automate the identification of physical characteristics of wood pellets (pellets).

In particular, Applicant has noted experimentally that the use of an IR sensor entails the advantages of:.

The Applicant has also experimentally noted that the use of a black and white image conversion module entails the advantages of:.

According to a feature of a preferred embodiment, the method for measuring physical characteristics of wood pellets comprises the steps of:.

The method provides that the image acquisition step comprises the step of acquiring an IR (infrared) image, and that the step of processing and measuring the dimensional characteristics of the group of pellets comprises a step of conversion of the cropped image into a grayscale image.

According to a further feature of the present invention, the device comprised in the system comprises a box, configured to contain, in use, a drawer inserted to size, through a door obtained in a lower area of the box, comprising, in use, a group of sampled pellets so as to allow measuring their physical characteristics, and a removable support configured to be applied and fixed to an upper wall of the box and comprising an IR or infrared sensor configured to acquire, in use, a graphical image of the drawer and of the group of pellets in the absence of artificial or natural lighting inside the box.

Other features defining the scope of the invention are defined in the appended claims.

These and further features and advantages of the present invention will appear more clearly from the following detailed description of preferred embodiments, provided by way of non-limiting examples with reference to the attached drawings, in which components designated by same or similar reference numerals indicate components having same or similar functionality and construction and wherein:.

In the present description, terms like: upper, lower, longitudinal, orthogonal, above, below, etc. are used to indicate elements or parts having orientation and position as conventionally defined in common use, so that, in the present description such term are to be interpreted in the way conventionally provided according to the common use, unless otherwise indicated.

The following description discloses a system <NUM> comprising a hardware device <NUM> and program modules (software modules) <NUM> implemented, preferably, on a microprocessor <NUM>.

One of the non-obvious choices underlying the system <NUM> is that the device comprises an infrared sensor (IR sensor) <NUM> and the program modules <NUM> comprise a conversion module of the images acquired by way of the IR sensor configured to convert the acquired image to a black and white image, i.e. to a grayscale image.

Applicant has indeed experimentally noted that the use of an IR sensor and that the subsequent conversion of the image to black and white entails at least the following advantages in order to fully and effectively automate the identification of the physical characteristics of the wood pellets.

In particular, the use of an IR sensor has the advantages of:.

Applicant has also experimentally noted that the use of a black and white image conversion module involves the advantages of:.

In particular, with reference to <FIG>, a system <NUM> for measuring the physical characteristics of wood pellets <NUM>, hereinafter simply named pellets <NUM> for simplicity, comprises a hardware device (device) <NUM> for recording and processing images, a microprocessor <NUM>, connected to the device <NUM> and comprising software modules <NUM> configured to process and save information arriving from the device and, preferably, a display-keyboard <NUM>, for example a Tablet of known type, connected to the microprocessor <NUM> and configured to interact with the microprocessor and to display the results of the microprocessor processing, as will be disclosed in detail herein below.

According to the preferred embodiment, the device <NUM> comprises a box <NUM>, for example a box of prismatic shape, preferably metallic, having, for example, a height of <NUM>, a depth of <NUM> and a width of <NUM>.

The device <NUM> also comprises a drawer (plate) <NUM> configured to be inserted to size, through a door <NUM> obtained in the box <NUM>, in a lower area (base area) 20a of the box. For example, the plate <NUM> has a depth of <NUM> and a width of <NUM> and is configured to contain, preferably leant in an orderly manner, a group of pellets in a number comprised, for example, among <NUM>-<NUM> pellets, sampled from a consignment of pellets.

Preferably the plate <NUM> comprises a black, i.e. a very dark colored bottom (background), and, in a predetermined position, for example near a vertex of the plate, a reference object <NUM> whose physical characteristics, such as width and length in mm, are known.

As a matter of fact, the accuracy of the measurements is linked to the precise acquisition of the contours of the reference object <NUM> by way of the IR sensor. Therefore, preferably, reference object <NUM> is characterized by white color with high reflectivity against the bottom (background) of plate <NUM> which, in particular, is covered with black acrylic paint with very high absorbance, for instance, a <NUM>% light absorbance.

The presence of the reference object <NUM> guarantees the possibility to obtain, by comparison, at least the dimensional characteristics of the pellets such as diameter and length, as easily understandable by a technician in the field.

The device, as already disclosed, comprises, preferably in the upper central position 20b of the box <NUM>, the infrared sensor <NUM>, for example the IR camera model Pi4 of the Raspberry Company. Preferably, the IR camera model Pi4 of the Raspberry Company uses IR refraction in the <NUM> band for the measurement of the physical characteristics of the wood pellets.

According to one embodiment that is considered preferable to simplify any maintenance interventions on the device <NUM>, the IR sensor <NUM> is comprised in a removable support <NUM> configured to be applied and fixed with screws to an upper wall of the box <NUM>.

In particular, according to this embodiment, the microprocessor <NUM> is preferably comprised in the removable support <NUM>. Even more particularly, according to this embodiment, the device comprises a lid <NUM> configured to close the box <NUM> so that, in use, no artificial or natural lighting can enter the box.

According to a variant of the embodiment disclosed above, it is also provided that the box <NUM> comprises one or more fans <NUM>, for example cooling fans, configured to ventilate, in particular, the microprocessor <NUM>, if it is provided that the microprocessor is comprised in the removable support <NUM>.

According to a further variant it is provided that the drawer <NUM> is shaped so as to comprise a positioning grid.

Preferably, according to this further variant, it is provided that the box <NUM> comprise a vibrator component mechanically connected to the drawer <NUM> and able to make the drawer to vibrate, in use, so that the individual pellets, thanks to the vibrations, are positioned according to the positioning grid, comprised in the drawer.

The microprocessor <NUM>, for example a microcomputer of known type as the micro model Pi4 of the Raspberry Company, is connected, in particular, to the IR sensor <NUM> and can be positioned both inside and outside the box <NUM>, without thereby departing from the scope of what has been disclosed and claimed.

The microprocessor <NUM> preferably comprises an operating system, libraries and program modules <NUM> written in a suitable programming language, and an archive (database) <NUM> wherein storing information and data concerning, in particular, the physical characteristics of the pellets are stored.

For example, the microprocessor <NUM> comprises the Linux Raspbian operating system, Pyton image recognition libraries and program modules written in Pyton language and implemented to realize the system and method according to the present invention, as disclosed in detail herein below.

In particular, according to the preferred embodiment, the program modules <NUM> comprise, for example:.

These program modules provide in general to display on the Tablet <NUM>, by way of a suitable graphical interface (GUI), the results of the processing step carried out on the sampled pellets.

Even more in particular, according to the preferred embodiment, the more general image acquisition step <NUM> comprises the following steps:.

The more general step configured to process the acquired image <NUM> comprises, for example, the following steps:.

The more general step of processing data concerning dimensional characteristics of the group of pellets <NUM> comprises, for example, one or more of the following steps, even if the list is purely indicative and not exhaustive:.

At the end of step <NUM> it is provided that it is possible to repeat the various steps from step <NUM> with the same pellet sample or with a different sample as a function of the quality of the results.

The operation of the system as disclosed above is the following.

After the preliminary steps, the operator, by using the Tablet <NUM>, enters the information necessary to the automatic processes <NUM>, <NUM>, configured to acquire and process the image.

At the end of these steps it will be possible for the operator to carry out the processes <NUM> provided for displaying on the Tablet <NUM> both the image, as obtained by way of the various processing steps, and the data relating the sampled pellets.

For example, the GUI <NUM> provided for the system <NUM> according to the present example of embodiment comprises:.

In particular, each row of the table comprises, for example, as shown in <FIG>, values such as:.

In summary, the presence of the Tablet <NUM> and of a specific GUI <NUM> configured to enter information, to view data and to physically characterize the pellets allows to:.

The system in the disclosed embodiment provides a preferably metallic box and a plate of predetermined dimensions compatible with the dimensions of the box. As easily understandable by a person skilled in the art, the material with which the box is made and the dimensions suggested as preferable are purely indicative and different dimensions, associated to different needs, can be provided, without departing from the scope of the invention as defined by the claims that follow.

The number of pellets, sampled from a consignment of pellets, to be checked may also vary from the values provided, without thereby departing from the scope of the invention as defined by the claims that follow.

The system and method as disclosed allows to obtain a plurality of advantages.

First of all, the times for checking the physical characteristics of the pellets are reduced by at least one numerical factor.

Secondly, by identifying the physical characteristics of each consignment of pellets as average and specific values, it is possible to optimize the combustion behavior of the pellets and, therefore, the performance and emissions due to the combustion of the pellets.

In addition, thanks to the identification of the average physical characteristics of each consignment of pellets, it is possible to solve extremely quickly possible logistics problems in the handling of the consignment of pellets.

It should not be overlooked that the automatic identification of the physical characteristics of the pellets improves the repeatability and reproducibility of the analysis of the consignment of pellets no longer linked to human factors dependent on the operator involved and on the manual measuring device, which is usually a mechanical caliber.

In summary, the disclosed system and method allows to simplify and provide accurate physical characteristics that are considered very important for:.

Claim 1:
A system (<NUM>) configured to measure dimensional characteristics of a plurality of wood pellets (<NUM>), comprising
- a device (<NUM>) configured to acquire images, said device comprising
- a box (<NUM>) comprising, inserted to size, a drawer (<NUM>), said drawer (<NUM>) being configured to comprise, in use, a group of wood pellets (<NUM>) sampled in order to measure the dimensional characteristics of said group of wood pellets,
- a sensor (<NUM>) configured to acquire, in use, a graphical image of the drawer (<NUM>) and of the group of wood pellets (<NUM>) comprised in the drawer,
and
- a microprocessor (<NUM>) connected to the device (<NUM>), and comprising
- program modules (<NUM>) configured to process and save information arriving from the device (<NUM>), said program modules comprising at least modules (<NUM>) both for converting the image acquired by the sensor (<NUM>) and for measuring the dimensional characteristics of the group of wood pellets (<NUM>),
characterized in that
- said sensor (<NUM>) is an IR sensor,
- said conversion and measurement modules (<NUM>) comprise at least one module for converting the image acquired by the IR sensor into a grayscale image,
- said drawer comprises, in a predetermined position, a reference object (<NUM>) in a colour with high reflectivity against the bottom colour of the drawer (<NUM>), said reference object comprising known dimensional characteristics,
and in that
said program modules (<NUM>) comprise
- further modules configured to calculate a pixel/mm ratio of said reference object comprising known dimensional characteristics, and to compare the dimensional characteristics of the reference object (<NUM>) with the dimensional characteristics of the group of sampled wood pellets.