WO2016128801A1

WO2016128801A1 - Dynamic discontinuous dryer

Info

Publication number: WO2016128801A1
Application number: PCT/IB2015/051420
Authority: WO
Inventors: Antonio SORGENTE
Original assignee: Sorgente Antonio
Priority date: 2015-02-12
Filing date: 2015-02-26
Publication date: 2016-08-18

Abstract

This is a dryer (1) comprising a casing (2) to contain the material to be treated (Min), means (3) to feed said material (Min) inside said casing (2), means (41, 42, 43) to blow hot air inside said casing (2), at least one reel (6) mounted inside said compartment (23) and comprising an axially rotating shaft (61) and one or more blades or screws (63, 64) mounted on said shaft (61), and wherein said at least one reel (6) is suited to move the material contained within said compartment (23).

Description

DYNAMIC DISCONTINUOUS DRYER

DESCRIPTION

This patent relates to dryers, and in particular concerns a new dynamic discontinuous dryer for material of various kinds, preferably wood, and/or waste and residues, predominantly organic.

The known art includes plants for the recycling of materials of various types, such as wood material in general, pellets, logs, and wood waste. These plants include, for example, shredders suited to reduce the material into fragments of varying particle size; refiners, suited to further reduce the ground material; chippers, suited to grind large pieces, etc.

The ground material, be it substantially wood or organic in origin, must be further treated before being put on the market for its intended end use.

A fundamental phase of the treatment of the ground material involves drying it, that is reducing the moisture content of the material up to an optimal value, which allows the subsequent stages to continue problem-free so as to obtain a quality product.

For example, in plants for the production of pellets, the milled wood material must be sent to the pellet production stages with an optimum moisture content of for example 12% -14%. A higher content would cause difficulties in the subsequent processing steps, for example in the phases of storage and bagging, since the volume of the material would be increased, yet the product obtained would be less solid, more flaky and commercially less valuable.

The known art also includes waste treatment systems, in particular for the organic fraction, which include, among others, grinders for the material, and dryers for the ground material.

Various types of dryers are known that can be broadly divided into two main categories, in particular, static or discontinuous dryers and dynamic dryers.

Static or discontinuous dryers essentially comprise a container suited to contain the material to be dried, the container comprising a bottom and side walls, a hopper for loading from above, a hot air generator, and forced hot air blowing means inside the container.

Static dryers are structurally very simple and inexpensive, but have some drawbacks, which considerably reduce their efficiency of use.

First they require greater drying times than dynamic dryers, thereby resulting in high energy costs.

In addition, static dryers do not allow the mixing for example of different types of material, which must therefore take place in an earlier or later stage.

Furthermore, the homogeneity of the moisture level inside the dryer is not guaranteed and may be optimal in the vicinity of the detection probe, but much lower in other areas of the container. The end result is the unnecessary expenditure of energy and unnecessarily prolonged drying times.

In contrast dynamic dryers are structurally and functionally more complex and therefore have higher costs.

Dynamic dryers comprise an axially rotating roller internally divided into cylindrical chambers, coaxial and communicating with each other, through which the material to be broken into small pieces circulates along a path, between an inlet at one end of the roller, and an outlet at the opposite end.

The path of the material and its travelling speed determines the period of time the material remains inside the dryer, that is, the drying period.

The drying is carried out by blowing forced hot air inside the roller.

Dynamic dryers process greater volumes of material per unit of time than static dryers, and also enable the attainment of material having a relatively homogeneous moisture level, since the material is continuously moved.

However, dynamic dryers cannot also implement an internal mixing function of various types of material.

Another drawback of dynamic dryers is that any corrections to the humidity value of the material detected in the material at the outlet are not specific for that part of the material.

In fact, if for example the moisture value at the outlet is detected to be greater than the optimal value for the material, the system increases the temperature of the forced air. In the meantime the material already contained in the dryer before the correction will come out with an incorrect humidity value, with the disadvantages already mentioned for the subsequent production stages.

To overcome all the above drawbacks a new type of dynamic discontinuous dryer has been designed and constructed, particularly for material of various kinds, and preferably wood, and/or predominantly organic waste and residues.

The main object of the present invention is to perform optimal and homogeneous drying of the material introduced, while optimizing energy consumption and drying times.

Another object of the present invention is to allow various modes of operation, while maintaining maximum efficiency.

A further object of the present invention is to also function as a mixer for the treatment of multiple types of material.

Yet another object of this invention is to also be used as a precise and gradual dispenser of dried material for the subsequent production stages.

Another object of this invention is that it can be used as a storage or accumulation environment.

Still another object of the present invention is to contain construction costs, while also ensuring high operational efficiency and optimization of consumption and drying times.

These and other aims, direct and complementary, are achieved by the new type of dynamic discontinuous dryer, particularly for material of a varied nature, and preferably wood, and/or predominantly organic waste and residues.

The new dryer comprises in its main parts a casing equipped with at least a bottom and side walls designed to create at least one compartment to contain the material to be treated, means to feed the material into the compartment, means to blow hot air inside the compartment, means to discharge the treated material, and wherein the dryer also includes at least one reel mounted inside the compartment comprising an axially rotating shaft and one or more blades or screws mounted on the shaft, and wherein the reel is suited to move the material contained inside the compartment. To ensure the proper movement and mixing of the material, without generating accumulation zones inside the compartment, the new dryer shall comprise at least one substantially horizontal double helix reel, with opposing blades to move the material inside the compartment in two opposite directions.

Alternatively, the dryer may comprise at least two of these reels, for example, substantially horizontal and parallel to each other, with opposing screws.

A further alternative solution is possible in which the dryer comprises at least one substantially vertical reel or in any case suited to lift the material, to then allow it to drop, thereby mixing it.

The action of this at least one reel has many functions and, in particular, serves to move the material contained in the compartment in order to equalize its moisture content.

In this way, when the optimal value of moisture is reached, which can be detected at any point inside the compartment, the drying process can be stopped because the mixing action performed by the at least one reel ensures that the entire mass of material is uniformly dried.

In this way, energy is not wasted to dry parts of the mass excessively, with consequent savings in terms of both energy consumption and time.

Another function performed by the at least one reel is to allow the mixing of different types of material such as, for example, wood of various species.

Thus this mixing step is carried out inside the dryer itself, without the need for stages and machinery in different places, as in the case of known dryers.

This means savings in terms of machinery costs and also processing times. The new dryer can also be optionally used without the mixing reel, or with the mixing reel at a standstill, thus operating as a discontinuous dryer of the known type, lengthening the drying time.

The new dryer can also be used as a storage tank, without blowing air, or as a normal mixer, without blowing air but with the mixing reel in motion.

The casing is preferably made of metal material.

The means to load the material inside the compartment preferably comprise at least one hopper for top loading, placed on the open top of the casing, and where loading may thus be carried out in various ways: by a mechanical shovel, with one or more conveyor belts, with one or more worm screws, etc.

The material is thus loaded into the compartment, up to a certain fill threshold.

The drying process begins at the end of the filling and consists of the blowing of hot air inside the compartment, which is forcibly made to pass into the mass of material, and the simultaneous movement of the material.

Upon reaching the desired moisture values of the material contained within the compartment, the material is discharged.

The means for discharging the material preferably comprise at least one screw on the bottom of the casing, such as a horizontal screw, which implements the complete emptying of the compartment, and can also be used for the accurate and gradual dosing of the material itself.

The new dryer also comprises means for the control of the parameters of the input and output material.

In the preferred solution, the new dryer comprises one or more loading cells and/or other means for weighing the material introduced into the compartment and/or means to measure the humidity of the material.

In particular the new dryer comprises at least one device to measure the moisture content of the material introduced into the compartment, wherein this measurement is conducted on the material before or after its insertion in the dryer. Knowing the weight and moisture content of the material introduced, and given the ideal humidity value at output, a simple algorithm is used to calculate the weight in water which must be evaporated from the mass of material.

For this purpose, the new dryer comprises automatic calculation and control systems, such as at least one electronic control unit.

The means for blowing hot air into the at least one compartment comprises at least one hot air generator, at least one fan suited to force the air into the compartment, and at least one system to distribute the hot air produced by the generator suited to distribute the hot air inside the compartment as consistently as possible.

The hot air, passing through the mass of material to be dried, causes the evaporation of part of the water contained in it and where that vapour naturally tends to rise upwards.

The casing is open at the top for this purpose, to allow the free discharge of the vapour, and/or comprises at least one suction system suited to convey the moisture laden air outside the casing.

This new dryer also preferably includes means and devices designed to collect or absorb any condensation, separating it from the material to be treated, in order to prevent the remixing of the condensate with the material.

Such condensate collection/absorption devices are preferably placed on the bottom of the casing.

During the drying process, the humidity value of the material is controlled before or after the material exits the dryer.

For example, for every 100 kg of material, assuming a 45% moisture content of the input material and optimally a 12% moisture content of the output material, a difference of 33% moisture is calculated, which corresponds to about 33 kg of water to be removed from the mass of material.

The hot-air generator can be of various types, depending on the type of heat source available. For example, the new dryer may comprise a biomass heat generator, with various capacities and power possible, and at least one heat exchanger for the input of hot air, for example at 70°C.

In this case the thermal power and the air flow rate are established as a function of the time required for drying and the hourly production required.

The heat generator may also comprise an internal combustion engine and at least one water/air exchanger, which uses the cooling water of the engine to heat the air, for example to 70°C.

In this case the air flow is established as a function of the flow of hot water available to be dissipated and the inlet temperature at the heat exchanger.

The new dryer can be applied in any industry: food, hospital, steel, wood processing, plastics, paper, rubber, etc., recovery, recycling or waste disposal.

The characteristics of the new dynamic discontinuous dryer will be better clarified by the following description with reference to the drawings, attached by way of non- limiting example.

Figure 1 shows a three-dimensional view of the new dynamic discontinuous dryer (1) according to a preferred embodiment. Figure la also shows the air removal ducts (43).

Figure 2 shows a cross section of the new dryer (1) where the components inside the drying casing (2) are visible.

Figure 3 shows a top view of the new dryer (1).

This is a new type of dryer (1) of the dynamic discontinuous type, particularly for material of various kinds, and preferably wood material, and/or predominantly organic waste and residues.

The new dryer (1) comprises at least one casing (2), or drying enclosure, equipped with at least a bottom (21) and side walls (22, 221, 222) suited to create at least one compartment (23) for the containment of the material to be treated.

The casing (2) has for example a substantially parallelepiped shape, with a main layout along the (X) direction.

The upper part (24) of the casing (2) is preferably completely or at least partially open to allow the loading of the material to be treated and to allow the free and natural release of vaporized water (W) during drying.

The new dryer also comprises at least one hopper (3) for top loading, mounted on the upper part (24) of the casing (2), for example in the vicinity of a side wall of the head (221) of the casing (2) itself.

The new dryer (1) comprises means to blow air into the compartment (23) and in particular comprises at least one hot air generator, not shown in the figures, with related fan suited to force air into the interior of the compartment (23).

The means for blowing air also comprise at least one system to distribute the hot air produced by the generator suited to distribute the hot air inside the compartment (23) as uniformly as possible. This distribution system comprises in particular one or more conduits or conveyors (41) located inside the compartment (23) of the casing (2), connected with holes (42) formed on the side walls (22, 221, 222).

For example, these ducts (41) are arranged in the direction of the main layout (X) and communicate with holes (42) formed on the side wall of the head (221) through which they are connected to the hot air generator, and on the opposite wall (222), through which they are connected to ducts (43) for the expulsion of air after its passage through the compartment (23).

The new dryer (1) also comprises means to discharge the treated material, comprising at least one horizontal screw (5) placed at or near the bottom (21) of the casing (2), rotated axially by at least one corresponding motor (52) and arranged in the direction of the main layout (X).

The screw (5) preferably covers the entire length of the casing (2) and communicates with the interior of the compartment (23) through a specific opening (51) on the bottom (21) of the casing (2). The screw (5) carries out the complete emptying of the compartment (23) and can also be used for the accurate and gradual dosing of the material itself.

The new dryer (1) also comprises at least one reel (6) mounted inside the compartment (23), preferably in the direction of the main layout (X) of the casing (2) and comprises a shaft (61) connected to a motor (62) for its axial rotation and a pair of opposing helical blades or screws (63, 64) mounted on the shaft (61), the first of which has a greater or external radius (63), for example right, and a second screw with a smaller or internal radius (64), for example left.

This reel (6) is suited to move the material contained in the compartment (23) and, thanks to the opposing screws (63, 64), the complete mixing of the material is ensured in the direction of the main layout (X), in both of the two opposite directions indicated by the arrows in Figure 2.

Thus the mass of material (Min) is fed into the compartment (23) of the casing (2) through the loading hopper (3).

Once loading is complete the ventilation means and the reel (6) to move the material are activated.

The fraction of water that vaporizes (W) is released through the open upper part (24) of the casing (2).

At the end of the drying process, that is, once the optimal moisture level of the material is reached, the discharge screw (5) is activated, which causes the dried material (Mout) to be discharged and the complete emptying of the compartment (23).

These specifications are sufficient for the expert person to make and use the invention. As a result, in the practical application there may be variations without prejudice to the substance of the innovative concept.

Therefore, with reference to the preceding description and the attached drawings the following claims are made.

Claims

1. Dynamic discontinuous dryer (1), particularly for material of various kinds, and preferably wood, and/or waste and residues of mainly organic origin, comprising at least one casing (2) equipped with at least a bottom (21) and side walls ( 22, 221, 222) suited to create at least one compartment (23) to contain the material to be treated (Min), means (3) to feed said material (Min) into said compartment (23), means (41, 42, 43) to blow hot air inside said compartment (23), characterized in that it also comprises at least one reel (6) mounted inside said compartment (23) and comprising an axially rotating shaft (61) and one or more blades or screws (63, 64) mounted on said shaft (61), and wherein said at least one reel (6) is suited to move the material contained within said compartment (23).

2. Dynamic discontinuous dryer (1) according to claim 1, characterized in that said means to blow hot air inside said compartment (23) operates substantially simultaneously with said at least one reel (6).

3. Dynamic discontinuous dryer (1) according to claim 1, characterized in that said means to blow hot air inside said compartment (23) operates substantially as an alternative to said at least one reel (6).

4. Dynamic discontinuous dryer (1) according to claims 1, 2 or 3, characterized in that it comprises at least one of said reels (6), mounted inside said compartment (23) in a substantially horizontal direction (X) and comprising said shaft (61) and a pair of opposing helical blades or screws (63, 64) mounted on said shaft (61), a first screw of which has a greater or external radius (63), right or left, and a second opposing screw with a smaller or internal radius (64), so as to move the material inside said compartment (23) in said direction (X), in both directions.

5. Dynamic discontinuous dryer (1) according to claims 1, 2 or 3, characterized in that it comprises at least two of said reels, both mounted inside said compartment (23) in a substantially horizontal direction (X), with opposing screws, so as to move the material inside said compartment (23) in said direction (X), in both directions.

6. Dynamic discontinuous dryer (1) according to claims 1, 2 or 3, characterized in that it comprises at least one of said reels, inside said compartment (23) in a substantially vertical direction or in any case suited to lift the material and then let it drop, thereby mixing the material.

7. Dynamic discontinuous dryer (1) according to any of the preceding claims, characterized in that it also comprises one or more means (5) for the release/unloading of the treated material (Mout), in turn comprising at least one substantially horizontal rotating screw (5), placed at or near the bottom (21) of the casing (2), suited to carry out the complete emptying of said compartment (23) and/or to dose the treated material (Mout) itself.

8. Dynamic discontinuous dryer (1) as per previous claims, characterized in that it comprises means for the control of the parameters of the material in and out, and in particular at least the moisture content of said material to be treated (Min) and said treated material (Mout) and/or one or more load cells and/or other means for weighing the material to be treated (Min) introduced into said compartment (23).

9. Dynamic discontinuous dryer (1) according to any of the preceding claims, characterized in that said means to blow hot air inside said at least one compartment (23) comprises at least one hot air generator, at least one fan suited to force air inside said compartment (23), at least one system to distribute the hot air produced by said generator, with conduits or conveyors (41) suited to distribute the hot air inside said compartment (23).

10. Dynamic discontinuous dryer (1) according to any of the preceding claims, characterized in that it comprises said heat generator (G) of a biomass type and at least one heat exchanger for the input of hot air.

11. Dynamic discontinuous dryer (1) according to any of the preceding claims, characterized in that said heat generator comprises a combustion engine and at least one water/air exchanger, which uses the engine's cooling water to heat the air.