Heated comb system for depositing a clear bitumen or binder onto a wet polyester mat using a cryogenic liquid such as liquid nitrogen.

Abstract

A process for solidifying bitumen or a clear binder for bagging purposes, characterized by the following measures: a device for freezing or cooling products is provided, comprising a porous conveyor, isolated by an enclosure, and means for impregnating said conveyor with cryogenic liquid; means are provided for depositing products to be cooled or frozen onto the porous support impregnated with cryogenic liquid so as to ensure total or partial freezing of the product; strips of binder or bitumen are deposited on the conveyor to allow cooling of such deposits within the device; the strips are cut at the device outlet or downstream of the product outlet. Figure 1

Description

Title of the invention: Heated comb system for depositing a bitumen or clear binder onto a wet polyester mat using a cryogenic liquid such as liquid nitrogen

[0001] The present invention relates to the field of manufacturing and / or packaging processes for bitumen or clear vegetable binders.

[0002] In the road sector, light-colored plant-based binders are of great interest because of their environmental, practical and aesthetic advantages.

[0003] It should be noted that light-colored binders are characterized by their lack of pigmentation and sometimes their transparency, unlike traditional bituminous road binders, which are dark due to the presence of asphaltenes in bitumen. The family of light-colored binders includes plant-based binders, derived from bio-based materials, and synthetic binders ("mineral" or "hydrocarbon") composed primarily of petroleum products. This lack of dark pigmentation allows them to be easily colored with a wide range of light and bright colors. They also allow the natural color of aggregates to stand out for projects related to active transportation (bike paths, parking lots) and urban development (parks, schoolyards, city centers).

[0004] Combined with light-colored aggregates, they help reduce the urban heat island effect, since light-colored pavements absorb less solar radiation energy. At the same time, light-colored binders also serve to delineate specific traffic zones to improve user safety.

[0005] Plant-based (or "bio-based") clear binders are composed primarily of ingredients of plant origin and therefore have a high renewable carbon content. They are manufactured by mixing several bio-based organic compounds, modified or unmodified, to improve their resistance to oxidation. These compounds generally come from the wood sector used by the paper industry and are extracted from by-products that are now being repurposed. Examples include tall oil pitch and plant resins, whose resin compounds have a strong binding capacity.

[0006] Plant-based binders offer a number of advantages over hydrocarbon binders. Even though they still tend to oxidize more quickly and have lower softening temperatures, these alternative binders are already preferred solutions for aesthetic coatings, localized repairs, and low-traffic areas, with very interesting performance.

[0007] The volume of Life Cycle Assessment (LCA) data available on plant-based binders is still limited due to the relative newness of these solutions. Nevertheless, studies conducted to date clearly demonstrate their potential for reducing the environmental impact of infrastructure. This is explained, among other things, by: • the renewable nature of raw materials; • lower manufacturing temperatures; and • low ecotoxicity.

[0008] Furthermore, clear plant-based binders are compatible with applications for recycling asphalt aggregates and for use in emulsions for the production of cold-mix asphalt, further reducing the carbon footprint of construction sites compared to traditional methods. For these various applications, the formulator has considerable freedom to adapt the rheological and mechanical properties of the plant-based binder. Nature of ingredients, origin, proportions, additives: the possibilities are numerous for specifically tailoring the penetrability, softening temperature, or even the viscoelastic properties of plant-based binders.

[0009] Apart from the component assembly stage, the manufacturing processes are very similar to those used for bituminous binders. The same methods can therefore be used to process bio-based binders. However, to preserve the transparency of the binders and comply with current quality and safety standards, companies wishing to produce and apply plant-based binders must have dedicated machines and equipment, preferably mobile and of a size adapted to current production volumes.

[0010] It is therefore advantageous for this industry to be able to bag these binders in packaging in order to supply user sites.

[0011] The present invention then aims to propose a new method of production and packaging of bitumen or clear binders (vegetable based).

[0012] A current process for manufacturing binders is known, comprising essentially the following steps: - we have a cold base powder, we proceed to grind it into a fine cold powder at a temperature typically in the range of 5°C-20°C; - we have a hot liquid (typically at 120°C-150°C), in particular what is called an "HMPL" (the technical term for "High Melting Point Liquid"); - all the components of the clear binder (liquid and solid) are then mixed and heated (for example around 110 to 150°C); - then, to carry out its conditioning, this mixture is cooled to a temperature typically between -10°C and ambient temperature; - the bagged material will be heated to the point of use, typically between 120 and 150°C.

[0013] We can therefore see that a significant amount of energy is required for these different stages.

[0014] As will be seen in more detail below, the present invention proposes the use of a porous conveyor tunnel, in particular with a polyester belt such as that described in document EP-0576 665, under the following conditions.

[0015] It is known that these porous belt tunnels have shown extremely interesting performance for the total or partial freezing ("crusting") of food products that are very difficult to process in traditional tunnels (fruits, balls, etc.), and thus in a tunnel of this type: • a porous support (e.g. polymer, e.g. polyester) is impregnated with a cryogenic liquid, the pore size of which is such that the cryogenic liquid (typically liquid nitrogen) is retained there; • then the article (fragile, sticky or deformable products such as particles, pellets, etc.) is brought into contact with the surface of the impregnated porous support, so as to ensure the partial or total freezing of the article by heat transfer between the article and the cryogenic liquid retained in the porous support; and • the item is then recovered, whether frozen completely or partially.

[0016] And it is the merit of the present invention to have considered the usefulness of such tunnels in the food industry in this application of solidification and bagging of binders, by depositing strips of bitumen on such a mat, and then by cutting these strips for grammage.

[0017] The contribution of this technical proposal is to allow the lower part of the bitumen to be instantly fixed by means of the high energy of the liquid nitrogen impregnated and trapped in the mat, in order to prevent the product from sticking and passing through the mesh of the polyester mat.

[0018] The difficulty with bitumen, as we know, is its very high viscosity, its high temperature and its low water content, which makes it a product with a completely different behavior from a food sauce, for example.

[0019] In addition to a cryogenic liquid spray ramp, the tunnel may include a conveyor immersion tank in liquid nitrogen. Optionally, the tunnel may also include fans in the upper part of the tunnel to increase convection transfer over the top of the product.

[0020] Let us explain what happens if a quantity of liquid bitumen is deposited on the surface of the impregnated porous mat, a deposit which can be carried out by any means A phenomenon known to those skilled in the art typically forms a "puddle" of bitumen on the conveyor, for example, a circular puddle which, given the viscosity of the product, is significantly thicker in the center than at the edges. The consequence is incomplete cooling of the bitumen; at the tunnel exit, the edges of the puddle are sufficiently rigid and no longer adhere to the polyester belt, while in the center of the "puddle" the bitumen still sticks to the belt, thus jamming the installation.

[0021] It is therefore advantageous to implement a comb, typically positioned a few centimeters downstream of the product deposit zone at the tunnel inlet, a few centimeters that will allow the product to spread out before reaching the comb. The comb is placed at a chosen height above the conveyor belt, a height that will define the product height along the rest of the porous strip within the tunnel (and therefore at its exit), a strip that then proceeds to a cutting operation.

[0022] Given the melting temperatures of common bitumens (around 130-150°C), according to a preferred embodiment of the invention, to prevent the comb from becoming clogged with bitumen, it is preferable to heat the comb continuously, above the temperature at which the bitumen is deposited on the mat.

[0023] The advantages of using such a comb can be summarized as follows: the puddle is spread with a uniform thickness (thickness adjustable via the positioning of the comb). a better distribution of the bitumen on the carpet. The comb helps to remove air bubbles created by the sublimation of liquid nitrogen upon contact with the hot product. By creating furrows in the “puddle”, we increase the surface area for exchange with nitrogen in the upper part. The grooves also allow for better lateral conductive heat transfer and therefore homogenize the temperature across the width.

[0024] The shape of the comb can be variable, and adopt any shape that can create grooves, for example: triangular in shape, crenellated in shape, tooth-shaped in shape, stem-shaped, etc...

[0025] The attached [Fig.1] illustrates an example of a comb shape: in the left part of the figure we visualize an example of a comb with triangular teeth, above a previously deposited puddle, while in the right part of the figure we visualize the result after the passage of the comb over the puddle.

[0026] The present invention relates to a method for solidifying a bitumen or a clear binder for the purpose of bagging it, characterized in that the following measures are carried out: we have a device for freezing or cooling products, comprising a porous conveyor, suitable for transporting within the device the products to be frozen or cooled, isolated by an enclosure, as well as means for impregnating said conveyor with cryogenic liquid, the size of the pores of the conveyor being such that cryogenic liquid can be retained there; means are available for depositing products to be cooled or frozen onto the porous support impregnated with cryogenic liquid in such a way as to ensure total or partial freezing of the products by heat transfer between each product and said cryogenic liquid retained in said porous support; strips of binder or bitumen are deposited on the conveyor to allow such deposits to cool in the device; At the exit of the device or downstream of the product exiting the device, a cutting operation is carried out on the strips before directing the product to a possible weighting operation.

[0027] According to one of the embodiments of the invention, a comb system is provided, positioned downstream of the product deposit area at the device's inlet, at a chosen height above the conveyor belt, a height which will allow the product height present on the rest of the conveyor's path towards its exit from the device to be defined.

[0028] According to one embodiment of the invention, the comb has a shape enabling the creation of grooves, and in particular one of the following shapes: Triangular comb, crenellated comb, toothed comb, rod-shaped comb

[0029] According to one of the embodiments of the invention, the comb is heated to a temperature at or above the melting temperature of the bitumen or binder being treated.

Claims

Demands

1. A process for solidifying a bitumen or a clear binder for the purpose of bagging it, characterized in that the following measures are carried out: - a device for freezing or cooling products is provided, comprising a porous conveyor, suitable for transporting the products to be frozen or cooled within the device, isolated by an enclosure, as well as means for impregnating said conveyor with a cryogenic liquid, the size of the pores of the conveyor being such that cryogenic liquid can be retained therein; - means are provided for depositing products to be cooled or frozen onto the porous support impregnated with cryogenic liquid in such a way as to ensure total or partial freezing of the product by heat transfer between each product and said cryogenic liquid retained in said porous support;- Strips of binder or bitumen are deposited on the conveyor to allow the cooling of such deposits in the device; - At the exit of the device or downstream of the product exit of the device, the strips are cut before the product is directed to a possible weighting operation.

2. A method according to claim 1, characterized in that a comb system is provided, positioned downstream of the product deposit area at the device inlet, at a chosen height above the conveyor belt, a height which will allow the product height present on the rest of the conveyor path towards the device's exit to be defined.

3. A method according to claim 2, characterized in that the comb has a shape enabling the creation of grooves, and in particular one of the following shapes: - Triangular comb - Crenellated comb - Toothed comb 7 - Comb in the shape of rods

4. A method according to claim 2 or 3, characterized in that the comb is heated to a temperature at or above the melting temperature of the bitumen or binder being treated.

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