WO2024042184A1

WO2024042184A1 - Method and facility for producing granules based on insect frass, and resulting granules.

Info

Publication number: WO2024042184A1
Application number: PCT/EP2023/073274
Authority: WO
Inventors: Bastien OGGERI; Audrey SCHULLER; Simon CALVET; Clémentine LÉVÊQUE
Original assignee: Innovafeed
Priority date: 2022-08-25
Filing date: 2023-08-24
Publication date: 2024-02-29
Also published as: FR3138979A1

Abstract

The present invention relates to a method and a facility for producing granules based on insect frass, comprising a frass drying step and a granulation step, which are characterized in that they include an additional step of adjusting the moisture content of the dried frass after said drying step and before entering the granulation equipment. The invention also relates to the resulting granules.

Description

METHOD AND INSTALLATION FOR PRODUCING GRANULES BASED ON INSECT FRASS AND GRANULES THUS OBTAINED.

Field of the invention

The present invention relates to the field of treatment of frass which is a co-product of insect breeding consisting of larval droppings and remains of substrate not consumed by the larvae and larval moults. The present invention relates in particular to the frass of the black soldier fly Hermetia Illucens.

In recent years, the food industry has become interested in the breeding of insects, and in particular the black soldier fly, because of their ability to convert organic waste, such as fruits and vegetables ( including coffee pulp), meat and fish, bread and cereals and manure, into products of market value, such as livestock feed (terrestrial or aquatic) or animal feed ingredients, animal feed pets, foodstuffs for human consumption and growth supplements for plants.

Facilities for the mass breeding of insects, and in particular black soldier flies, have therefore been developed and solutions have been sought to recycle the droppings and waste resulting from these industrial breeding operations.

It appeared necessary to provide on industrial breeding sites for black soldier flies, and more generally insects, equipment to automatically collect the frass and transform it to allow its valorization in the form of value-added phytosanitary products. Indeed, due to its composition, frass is an excellent fertilizer. To be used optimally, it is necessary to transform it into granules: this allows it to be spread with standard agricultural equipment and also to increase its density in order to be able to transport it more easily.

State of the art

We know of patent US20160297720A1 which describes a method of converting natural waste (for example, droppings produced by mealworms/Tenebrio moiltor) to produce a biofertilizer using the infusion to extract nutrients from mealworm droppings. Saturated mealworm castings can be dried and processed to form a pelletized fertilizer.

Patent US9394208B2 describes a process for converting light and powdery mealworm droppings into a suitable fertilizer product. The methods may include saturating mealworm castings using an infusion process with a liquid such as water until a high temperature is reached. Mealworm castings can be restocked and the brewing process can be repeated until the targeted NPK rating is reached. The infusion process can produce a liquid extract that can be used as a foliar spray, pest repellent, or irrigation. Saturated mealworm castings can be dried and made into fertilizer pellets or a granular soil-like product. In some examples, a binding agent such as dried mashed potato extract may be added to the saturated mealworm castings.

Disadvantages of the prior art

The problem that arises with the granulation of frass is the control of the hygrometry upstream and downstream of the granulation equipment. The material must be sufficiently dry during granulation so that the granules are sufficiently inert to be stored. But if the material is too dry during the granulation process, this affects the quality of the granules which can become more fragile and therefore more prone to breakage during handling, thus generating dust.

Furthermore, the operation of granulation equipment is very sensitive to the consistency of the incoming material, and optimum adjustment of drying upstream is delicate because it depends on numerous parameters including humidity and ambient temperature, and because the effects Adjustable parameters have high inertia.

Solution provided by the invention

In order to remedy these drawbacks, the present invention proposes, in its most general sense, a process for producing granules based on insect frass comprising a step of drying the frass and a granulation step characterized in that it comprises a additional step of adjusting the humidity level of the dried frass after said drying step and before entering the granulation equipment.

Advantageously, said frass is constituted by a mixture of at least one of the following components: residues of the substrate for breeding insect larvae, their droppings and larval moults.

According to one variant, said frass has a humidity level of between 6 and 10% at the outlet of the dryer and a humidity level of between 10 and 20% at the entrance to the granulation equipment.

Preferably the adjustment of the humidity level of the frass is carried out using rehumidification equipment comprising a controlled means of water and/or steam injection.

According to an advantageous variant, said water and/or steam injection means is controlled by at least one humidity sensor and a PID controller according to an output setpoint value of between 10 and 20%.

Advantageously, the process includes an additional sieving step between the drying step and the rehumidification step.

According to a particular mode of implementation, the process includes an additional step of sanitizing the granules from the granulation equipment (80).

Advantageously, said hygienization step does not require any energy input to raise the temperature of the granules, the granules being sufficiently heated during the granulation step.

The invention also relates to an installation for producing granules based on insect frass comprising drying equipment and granulation equipment characterized in that it further comprises rehumidification equipment receiving the dried frass from said drying equipment and before introduction into said granulation equipment.

Preferably, the installation further comprises hygienization equipment receiving the granules from said granulation equipment.

Preferably, said rehumidification equipment comprises an automatic means of control by a humidity sensor at the outlet of the dryer and a humidity setpoint value at the inlet of the granulation equipment.

Advantageously, said rehumidification means consists of a mixer comprising means for injecting water and/or steam.

The invention also relates to soil amendment granules obtained by the above-mentioned process, characterized in that they consist of a mixture of at least one of the following components: residues of the substrate for breeding insect larvae , their droppings and larval molts.

Detailed description of a non-limiting example of production

The present invention will be better understood on reading the description which follows, concerning a non-limiting example of embodiment illustrated by the appended drawings:

there represents a functional diagram of the invention.

General principle

The object of the present invention is to treat and valorize the waste from the production of insect larvae, namely frass corresponding to the mixture of residues from the larvae rearing substrate, larval droppings and larval moults.

The frass and larvae mixture from the breeding site is sorted by particle size. In fact, frass is mainly made up of a wet powder, with a particle size of less than a millimeter. The larvae can be compared to cylinders with a diameter between 3 and 5 mm and a length between 8 and 12 mm. A separation by particle size is therefore carried out using a sieve.

The sieve technology used to separate the larvae from the frass is a trampoline sieve. The mesh of the sieve evolves with a trampoline effect, that is to say that the mesh extends then relaxes, creating a rebound effect of the material. This sieve is particularly suitable for clogging materials such as frass which is a powdery material with variable humidity between 25 and 60% RH.

The frass passes through the mesh gradually along the length of the sieve. The frass is collected under the sieve. The larvae remain above the mesh and travel along the entire length of the sieve. The width and length of the sieve are chosen to ensure the treatment of the nominal instantaneous flow rate of incoming material (mixture of larvae and frass), and also to ensure the best separation between the larvae and the frass.

The frass thus separated is transferred into a buffer hopper (1) of 10 m ³ with a rectangular section upstream of the dryer (10). It is then transferred to the dryer (10) and can then be screened again (40) before being transferred to a buffer hopper (50). The humidity of the dried and sieved frass is then adjusted in rewetting equipment (70) before granulation in granulation equipment (80). The granules are then subject to treatment by hygienization equipment (90) then cooling (100) then are stored in a silo (110).

The following description presents in more detail some of the equipment and some of the stages of frass processing between the separation of the larvae, and the storage (110) in the form of pellets.

Frass handling

The purpose of storage in a buffer hopper (1) is to maintain flexibility between the management of the frass processing workshop, and the production of raw frass from the turning of the breeding modules upstream and therefore from the zone breeding.

Convective drying of frass

un équipement de manutention (11) assurant le dosage, la répartition du frass sur la bande, et l’extraction du frass séché en sortie du sécheur ;
un sous-système aéraulique (12) assurant le chauffage et le soufflage de l’air de séchage ;
un sous-système de métrologie (13) pour la mesure d’humidité du frass en amont et aval du procédé de séchage.

The frass coming from the sieve is first subjected to convective drying: air at room temperature is heated, then sucked through a homogeneous layer (constant thickness) of moist frass. By loading itself with humidity, the hot air dries the frass which transfers part of its water into the air flow. Therefore the hot air cools drying the frass. This drying is carried out by an installation having several subsystems:

handling equipment (11) ensuring the dosage, distribution of the frass on the belt, and the extraction of the dried frass at the outlet of the dryer;
an aeraulic subsystem (12) ensuring heating and blowing of the drying air;
a metrology subsystem (13) for measuring frass humidity upstream and downstream of the drying process.

Depending on the speed of the dryer (incoming flow), the drying time can vary between 20 and 120 minutes. The drying temperature is, for example, approximately 55°C, but can be increased to 110°C.

Distribution and homogenization of frass on the dryer belt (10)

The dryer (10) is fed via two screws rotating in opposite directions in order to distribute the frass over the entire width of the strip (which advances under the distribution screws) at constant thickness. The thickness is regulated by a system allowing the height of the screws to be adjusted and a ruler fixing the frass height. The torque is monitored on each of the screws in order to detect frass “holes”: a torque that is too low below a given threshold value indicates a hole or a thickness of frass that is too low.

Maintaining a consistent thickness and absence of frass "holes" on the belt is critical to the operation of the dryer: hot air must be distributed evenly as it passes through the dryer belt and the frass that is above. Without a uniform thickness, or if there are frass holes, the hot air passes through preferential paths, and then disrupts drying and its homogeneity.

As it passes through the dryer (10), the frass is also homogenized using two turning screws separating the dryer belt (10) into three zones of approximately equal length. As a non-limiting example, the dryer belt has dimensions of 20 m long and 6 m wide.

Drying is carried out by air flows passing through the layer of frass on the dryer belt (10), and coming from a hot air circuit (12) through ducts spaced along the transport belt.

Extraction of dried frass

The dried frass is collected at the outlet of the dryer (10) by an endless screw located under the outlet of the dryer belt. It allows the frass to be collected over the entire width of the belt (6 m) and to send the flow of dried frass to the chain conveyor used for downstream handling.

Aeraulics

Air heating is carried out in a water/air circuit using hot water. As an indication, air heating can, with some modifications, be carried out with steam.

Hot water management

A control valve at the dryer inlet regulates the flow of hot water supplied to the dryer. The temperature of the water entering the exchangers varies between 50 and 70°C.

Heating the ambient air

The air is sucked in by the dryer fans (10) through 4 water/air exchangers located on the roof of the dryer. In order to avoid creating too much depression in the workshop, openings were installed in the cladding to be able to capture the outside ambient air. The fans are sized to suck up to 230,000 m3/h at heated air temperatures between 55°C and 110°C.

Instrumentation

température de l’air : air ambiant, air chauffé (en sortie de chacun des 4 échangeurs), air rejeté (en sortie de chacun des 4 ventilateurs) ;
température de l’eau : eau chaude entrée sécheur, eau chaude sortie sécheur ;
humidité absolue et relative : air ambiant, air rejeté (en sortie de chacun des 4 ventilateurs) ;
débit d’eau chaude ;
débit d’air aspiré.

In order to monitor drying performance and control the dryer, different types of sensors can measure the following quantities:

air temperature: ambient air, heated air (at the outlet of each of the 4 exchangers), rejected air (at the outlet of each of the 4 fans);
water temperature: hot water entering dryer, hot water leaving dryer;
absolute and relative humidity: ambient air, exhaust air (at the outlet of each of the 4 fans);
hot water flow;
intake air flow.

Ventilation

Ambient air is sucked in by 4 fans. The fans are used to compensate for air pressure losses through the exchangers, the frass layer, the belt, and the air ducts towards the exhaust to the atmosphere.

Frass moisture measurement

The humidity of the frass is measured continuously at the inlet and outlet of the dryer by two identical capacitive sensors (13). This technology is also used further in the process to measure humidity before dosing water into the granulation equipment.

Sieving dried frass

This second sieve (40) of the frass line intervenes after the drying phase in the dryer (10) to eliminate elements with a particle size greater than 2.0 mm and any residual larvae dried by the dryer.

The sieve technology (40) used is a sieve with a possible sieving particle size range of 0.020 to 30mm: the mesh size selection was chosen at 2mm in order to exclude any larva still present in the frass flow dried.

The dried frass is dispersed on the surface of the sieve (40) thanks to the slope of the latter and the vibrations produced by two motorcycle vibrators (one on each side of the sieve), and is unclogged by the bouncing of the balls. The sufficiently fine frass passes through the mesh gradually along the length of the sieve and falls into the buffer hopper. The larvae and frass of too large a particle size pass through the sieve (40) on the mesh and then fall into a chute leading to the chain conveyor in the direction of the waste bins.

Buffer storage and dosing

Once the frass is dry and sifted, it is temporarily stored in a 3 m ³ buffer hopper (50). The purpose of this hopper (50) is to store the frass to ensure a stable supply of the granulation equipment (80).

The granulation equipment (80) is fed using a dosing screw (60) located under the hopper which will regulate the sending of frass to the mixer (70) and then to the granulation equipment ( 80). The screw motor (60) is equipped with a variator which allows you to choose its speed in order to send a greater or lesser flow rate to the granulation equipment. For example at minimum screw feed speed (5% at the variator), the flow rate of frass sent to the granulation equipment is 0.3 t/h.

Water and steam injection

Between the dosing screw (60) and the granulation equipment there is a mixer (70). The frass enters the dryer (10) with a humidity of approximately 30 to 60% and leaves the dryer (10) at a humidity between 6 and 10% depending on several parameters (dryer settings, type of frass entering, drying conditions). atmosphere, etc.).

The invention relates to "over-drying" of frass before a re-wetting step in re-wetting equipment, here a mixer (70), just before the granulation step by the granulation equipment (80).

The humidity level of the frass must be between 10 and 20% at the entrance to the granulation equipment to allow optimal granulation.

The role of the mixer (70) is to homogenize the frass before introduction into the granulation equipment with two possible additions: water and steam.

The addition of steam will make it possible to control the temperature of the frass entering the granulation equipment and to raise it to temperature before granulation if necessary. The addition of steam also makes it possible to re-moisten frass that is too dry.

simplifier le pilotage du sécheur (10) car il n’y a pas de cible précise d’humidité en sortie et donc moins de surveillance à effectuer ;
éliminer les variations d’humidité en entrée de l’équipement de granulation (80) : simplification du pilotage également car, une fois la capacité nominale atteinte après le démarrage, il n’y a plus de facteur perturbant et l’équipement peut fonctionner de manière stabilisée ;
assurer une qualité de granulés stable au fil des productions : ayant fixé une consigne d’humidité fixe en entrée de l’équipement de granulation au régulateur PID, le frass est toujours granulé à la même humidité. En fixant également une capacité de l’équipement de granulation nominale et un taux de compression, une production uniforme de granulés est assurée.

The addition of water makes it possible to rehumidify frass that is too dry and thus obtain very precise humidity at the entrance to the granulation equipment (80). A choice of control can thus be made to simplify the operation of the dryer: overdry the frass in the dryer and then rehumidify in the mixer (70). This choice has three major advantages:

simplify the control of the dryer (10) because there is no precise output humidity target and therefore less monitoring to be carried out;
eliminate variations in humidity at the inlet of the granulation equipment (80): simplification of control also because, once the nominal capacity is reached after start-up, there is no longer a disturbing factor and the equipment can operate continuously. stabilized manner;
ensure stable granule quality throughout production: having set a fixed humidity set point at the input of the granulation equipment to the PID regulator, the frass is always granulated at the same humidity. By also setting a nominal pelletizing equipment capacity and compression ratio, uniform pellet production is ensured.

How the water addition works

The addition of water is controlled by a PID controller with several modes, the most advanced of which, Cascade mode, allows you to set a desired humidity setpoint at the input of the granulation equipment: the controller then calculates a dose of adapted water and controls the opening of the proportional water valve to obtain this flow.

consigne d’humidité cible voulue donnée par l’opérateur,
humidité réelle mesurée du frass en entrée du malaxeur via un capteur d’humidité (3^ème mesure de la ligne frass après les deux mesures amont et aval sécheur),
débit de l’équipement de granulation à l’instant t,
débit réel d’eau injectée via un débitmètre en ligne installé entre la vanne de régulation d’eau et les buses d’injection d’eau dans le malaxeur.

To calculate this water dose, the controller retrieves the following information:

desired target humidity setpoint given by the operator,
actual humidity measured from the frass at the mixer inlet via a humidity sensor ( ^3rd measurement of the frass line after the two measurements upstream and downstream of the dryer),
flow rate of the granulation equipment at time t,
actual flow rate of water injected via an in-line flow meter installed between the water control valve and the water injection nozzles in the mixer.

The controller is responsible for adapting its valve opening setpoint to follow variations in measured humidity and frass flow rate in the granulation equipment in order to ensure stable inlet humidity at the given setpoint.

Granulation

To be granulated, the frass is injected via the mixer (70) into the body of the granulation equipment (80) and is crushed there by rollers on a compression die. It is compressed in the holes of the die and the granules are then cut by knives under the die.

The pressure on the roller head to crush the frass is applied by a hydraulic unit.

The choice of die will determine a compression rate and a diameter of granules, on which the quality and characteristics of the granules produced will depend (for example durability, fines rate, degradability).

Extraction of steam

A steam extraction system from the granulation equipment was installed to prevent the steam produced during handling from being sent to the hygienizer. Sending these mist would cause condensation in the chain conveyor and accumulations of debris which could ultimately obstruct the ducts.

The system consists of a coreless screw connected to the outlet of the granulation equipment (via a removable conduit) and to the dryer to be able to recover the condensates deposited in the suction duct and return them to the dryer. The system is depressurized by the dryer fans and allows the suction of vapors in the pipe.

Overall control strategies for the dryer (10) and granulation (80)

The granulation process is strongly dependent on the frass to be transformed, and in particular its particle size, chemical composition, temperature and even its humidity level. The quality of the pellets produced is therefore also strongly impacted by fluctuations in these characteristics.

The humidity of the frass entering the granulation equipment is particularly critical and impacts the quality of the granules at the outlet, but also the nominal capacity of the granulation equipment.

Frass Pellets Specifications

Durabilité : ce critère caractérise la tendance des granulés de frass à produire des fines (de la poussière de frass sec) lorsque soumis à des efforts liés à de la manutention (mécanique, ou lors de transport et manipulation de contenants type sacs). Un granulé de bonne qualité correspond à une durabilité la plus élevée possible.
Taux de fines : le frass en granulés doit avoir un taux de fines le plus faible possible avant d’être conditionné afin que l’utilisateur final qui utilise les granulés ait un minimum de pertes.
Tenue du granulé ou dégradabilité : un bon granulé d’engrais organique doit pouvoir également se dissoudre facilement dans l’eau afin de pouvoir relâcher les nutriments qu’il contient dans les sols

Frass granules are intended to be spread and must meet certain quality criteria.

Durability: this criterion characterizes the tendency of frass granules to produce fines (dry frass dust) when subjected to forces linked to handling (mechanical, or during transport and handling of bag-type containers). A good quality pellet corresponds to the highest possible durability.
Fines content: granulated frass must have the lowest possible fines content before being packaged so that the end user who uses the granules has a minimum of losses.
Holds the granule or degradability: a good organic fertilizer granule must also be able to dissolve easily in water in order to be able to release the nutrients it contains into the soil

Two parameters greatly influence these parameters: the humidity level of the frass entering the granulation equipment and the compression rate of the die.

The acceptable humidity (with respect to the quality criteria above) at the inlet of the granulation equipment was determined between 10 and 20%. Outside of these limits, a pellet is considered to have unsatisfactory quality. For a humidity of less than 10%, the motor intensity of the granulation equipment is unstable due to an incoming frass that is too dry (too hard to granulate) and for a humidity greater than 20%, the granules produced do not hold together well. and have an unsatisfactory appearance.

Operation of the dryer and importance of adding water

The humidity of the frass entering the dryer (10) is experienced and depends on a multitude of factors inherent to the breeding conditions of the insect larvae. It is therefore extremely difficult to establish a drying regime giving a stable humidity at the dryer outlet within the admissible humidity range.

Le frass est sur-séché dans le sécheur afin de pouvoir ajuster le taux d’humidité en sortie en continu par l’adjonction d’eau.
L’équipement de granulation fonctionne avec du frass en entrée à une humidité qui ne fluctue pas.
Les pertes de frass dont l’humidité n’est pas admissible en entrée de l’équipement de granulation sont éliminées.

Without adding water, only a fraction of the dryer outlet frass (10) is granulated. The addition of water, however, makes it possible to change the overall line control strategy as follows.

The frass is over-dried in the dryer in order to be able to continuously adjust the output humidity level by adding water.
The pelletizing equipment operates with frass input at a humidity that does not fluctuate.
Losses of frass whose humidity is not admissible at the entrance to the granulation equipment are eliminated.

Adding steam

The addition of steam was intended to improve the quality of the frass granules by allowing control of the temperature of the dry frass at the entrance to the granulation equipment (80), and therefore to influence its texture (and therefore the quality pellets at the outlet). On products containing starch, for example, steam allows the product to be partially cooked.

Hygienization

The need for hygienization of frass arises mainly from a regulatory constraint on the production of organic fertilizers based on slurry (category of animal by-product of frass according to French regulations). The latter requires maintaining the slurry at a temperature of at least 70°C for at least 1 hour. This makes it possible to eliminate different types of potentially harmful pathogens contained in the product before spreading.

The heat released by the granulation process is used to heat the granules: at the compression ratios used (greater than or equal to 5.5:1), the temperature of the granules leaving the granulation equipment is greater than 80° vs. A hygienizer (90) is therefore designed to maintain this temperature for at least 1 hour. This approach makes it possible to reuse part of the thermal energy released by the granulation in order to heat the frass, without having to add a dedicated heating step in the process. This therefore leads to considerable energy savings.

The hygienizer (90) is fed by a chain conveyor directly from the granulation equipment (80). The conveyor is insulated and traced to avoid loss of temperature of the granules during this transfer phase.

Un mode « batch », constitué d’une phase de remplissage et d’une phase d’hygiénisation. Lors de l’hygiénisation, l’alimentation de l’hygiéniseur est interrompue (manutention arrêtée) afin d’assurer au moins 1 heure de maintien à une température supérieure ou égale à 70°C.
Un mode continu pour lequel le remplissage et la vidange de l’hygiéniseur (90) peuvent être simultanés. Dans ce cas, c’est le volume de l’enceinte qui assure un temps de résidence d’1 heure grâce à une limitation sur le débit d’extraction des granulés de frass.

Two operating modes have been defined and implemented.

A “batch” mode, consisting of a filling phase and a sanitation phase. During hygienization, the power supply to the hygienizer is interrupted (handling stopped) to ensure at least 1 hour of maintenance at a temperature greater than or equal to 70°C.
A continuous mode for which the filling and emptying of the hygienizer (90) can be simultaneous. In this case, it is the volume of the enclosure which ensures a residence time of 1 hour thanks to a limitation on the extraction rate of the frass granules.

Before the start of production, the hygienizer enclosure (90) is heated to a temperature above 70°C.

The pellets exit the pelletizing equipment at a temperature of approximately 80°C - 90°C. They are maintained at this temperature in the conveyor between the granulation equipment and the hygienizer which is traced and insulated.

During their stay in the hygienizer (90), the granules remain at a temperature above 70°C thanks to the thermal insulation and the tracing of the enclosure which counteracts energy losses, in particular losses through the walls.

Three temperature measurements allow the enclosure temperature to be checked at three different heights in the hygienizer (90). If the temperature of the pellets in the enclosure is maintained above 70°C during the one-hour hygienization period (the three temperature probes indicate a temperature above 70°C), the heat treatment is validated and the batch can be sent to the cooler. If the temperature ever drops below 70°C, the pellets are discarded via a bypass hatch between the hygienizer (90) and the cooler.

Cooling

The hot granules leaving the hygienizer are sent via a chain conveyor to a counter-current cooler (100).

The supply of hot pellets to the cooler is regulated by a rotary inlet valve, and an equalization system in the enclosure ensures a uniform layer over the entire surface.

The cooling air is drawn directly into the workshop, passes through the layer of granules and is discharged outside the building after being filtered through 2 pocket filters.

The emptying mechanism is made up of a movable bottom which undergoes a back and forth movement intermittently (on level triggering) allowing a layer of granules to be released at each opening.

An emptying cycle (opening/closing) is triggered by reaching the intermediate level determining a sufficiently high level of pellets in the enclosure and therefore a sufficiently long residence time to cool the first pellets entered.

The level is a rotating vane sensor that triggers when pellets block the movement of the vane.

At each emptying cycle, the level in the cooler drops and you must then wait for refilling to this same pallet to retrigger an emptying cycle.

Transfer to storage

At the outlet of the cooler (100), the pellets fall into a small buffer hopper and are then sent to a chain conveyor via an extraction screw. This makes it possible to avoid overloading the conveyor at each emptying cycle but to regulate its supply.

The hopper is secured by a high level (a rotating vane sensor again) and if this level is reached, the cooler extraction cycles are blocked.

Sending to the storage silo (110) is done by two chain conveyors in series.

A bypass is installed on the second conveyor, allowing the pellets not to be sent to the silo if necessary.

Storage

The storage method used is a silo (110) with a capacity of 428m ³ with a conical cell. It can store around 300 tonnes of pellets.

The emptying is done by gravity thanks to a 45° cone and a manual opening/closing hatch, the granules are then sent to a chain conveyor for extraction from the silo, then to a bucket elevator to raise them to level high enough for truck loading.

A metal chute is installed between the elevator pier and the loading sleeve.

The loading module is a flexible automatic cuff.

Shipping

Loading is done by dump truck or tanker truck. In both cases, an automatic loading sequence allows the silo extraction equipment to be started as well as the cuff to start emptying into the truck.

A load is made up of approximately 25-30 tonnes of pellets depending on the truck.

Claims

Process for producing granules based on insect frass comprising a step of drying the frass and a granulation step characterized in that it comprises an additional step of adjusting the humidity level of the dried frass after said drying step and before entering the granulation equipment (80).
Process for producing granules based on insect frass according to claim 1 characterized in that said frass is constituted by a mixture of at least one of the following components: residues of the substrate for rearing insect larvae, their droppings and larval molts.
Process for producing granules based on insect frass according to claim 1, characterized in that said frass has a humidity level of between 6 and 10% at the outlet of the dryer (30) and a humidity level of between 10 and 20% at the entrance to the granulation equipment (80).
Process for producing granules based on insect frass according to the preceding claim, characterized in that the adjustment of the humidity level of the frass is carried out using rehumidification equipment (70) comprising controlled means for injecting water and/or steam.
Process for producing granules based on insect frass according to the preceding claim, characterized in that said water and/or steam injection means is controlled by at least one humidity sensor and a PID controller as a function of 'an output setpoint value between 10 and 20%.
Process for producing granules based on insect frass according to claim 1, characterized in that it comprises an additional sieving step between the drying step and the rehumidification step.
Process for producing granules based on insect frass according to claim 1, characterized in that it comprises an additional step of hygienizing the granules from the granulation equipment (80).
Process for producing granules based on insect frass according to the preceding claim, characterized in that said hygienization step does not require any energy input to raise the temperature of the granules, the granules being sufficiently heated during granulation stage.
Installation for producing granules based on insect frass comprising drying equipment (10) and granulation equipment (80) characterized in that it further comprises rehumidification equipment (70) receiving the dried frass from said drying equipment (10) and before introduction into said granulation equipment (80).
Installation for producing granules based on insect frass according to claim 9 characterized in that it further comprises hygienization equipment (90) receiving the granules from said granulation equipment (80).
Installation for producing granules based on insect frass according to claim 9 characterized in that said rehumidification equipment (70) comprises automatic means of control by a humidity sensor at the outlet of the dryer (10) and a value humidity setpoint at the inlet of the granulation equipment (80).
Installation for producing granules based on insect frass according to claim 9 characterized in that said rehumidification means (70) is constituted by a mixer comprising means for injecting water and/or steam.
Soil amendment granules obtained by the process according to claim 1, characterized in that they consist of a mixture of at least one of the following components: residues of the substrate for rearing insect larvae, their droppings and larval molts.