Solidification

Drum Flaker

Practically oriented solutions The transformation of a molten product to a solid product is advantageous for storage, transport, handling and safety. There are a number of common forms: flakes, pastilles or prills. The drum flaker responds to the demand for transforming molten product to easily manageable congealed flocks using very simple and reliable processing.

Flakes from a drum flaker

How the GMF-Gouda drum flaker works The drum flaker is used to transform a molten product into a solid. In a continuous process a thin layer of the product adheres to the outside of the rotating drum. The product congeals when it comes into contact with the surface of the drum flaker, which is cooled from inside. The crystallization heat is transferred from the product via the drum to the cooling agent and the desired temperature is achieved. When the drum has almost completed a full revolution the product is removed from the drum with a knife scraper. During this process, the product is transformed to easily processable flakes, depending on the type of product and process parameters.

Cut-away model of a drum flaker showing the knife and the integrated transport screw.

Various models The drum flaker is available in different models, adaptable to products with different properties. The two most common applications are described below.

Rendition of a drum flaker with a dip pan

Drum flaker with dip pan This model of drum flaker has the drum turning continuously through a heated melt in a dip pan under the drum. As the drum turns and is immersed in the melt a thin film of liquid product attaches to the exterior of the drum. The film begins to cool and coagulate on the drum. A precondition for using this method is that the product has a low viscosity and good adhesive properties.

Drum faker with overhead application roll This system has a heated application drum positioned above the drum flaker. The molten product is applied to the drum in the small trough shaped space between the application roll and the drum flaker. Contact with the warm application roll ensures that the product remains fluid. During production, the product flows through the pre-set gap between the application roll and the drum and adheres to the drum's surface. In this way the shape and thickness of the flakes can be accurately controlled. This method is often used for products with an average to high viscosity.

Rendition of a drum flaker with     an overhead application drum

Other designs Due to the large variety of products in the chemical and food industry, GMF-Gouda also has other configurations. These not only reflect a change in design but also in control options and the use of different materials of construction. Naturally, there are products that do not conform to the above-mentioned specifications. For example, products with either bad adhesive properties, or products with bad coagulation characteristics. GMF-Gouda offers an extensive range of special machines for these situations. The drum surface can be tooled with specially shaped grooves for products with bad adhesive properties. Choices of materials Most drums are made of stainless steel. Aside from the choice of different qualities of stainless steel, chromed, Hastelloy or steel drums can also be supplied. The final choice depends on the product properties with respect to corrosion and adhesion. The result is a durable drum with a uniform stability and uniform heat distribution over the entire surface.

Advantages of the GMF-Gouda drum flaker The concept of the drum flaker in relation to other congealing technologies has a number of advantages:

Efficient use of space Just as with the Disc Pastillator, the floor space of the Drum Flaker is decidedly less than required by other congealing techniques. The reason for this is on the one hand the efficient cooling technique used and on the other because of 100% use of the available cooling surface.

The difference in required floor space

Cooling system To congeal a molten product the crystallization heat of the product must be removed. This is transferred via the drum flaker's wall. The heat is relayed via the drum body to the cooling agent, which is usually water. The cooling water is sprayed with a special spray pattern against the inside of the drum using a central spray pipe. A drum flaker's cooling system Spraying cooling agent against the inside of the drum is done in such a way that the product is cooled in the most efficient way possible. This makes it possible to achieve higher capacity. This method of cooling has the additional advantage that the drum is kept at an absolutely uniform temperature over the entire length resulting in a more homogenous product. The warmed up cooling water is continuously drained from the drum to be re-cooled elsewhere. The drum flaker has a completely closed cooling system. Due to the closed cooling system the product cannot come into contact with cooling agent This eliminates the negative effects of coolant fumes (water vapour) in the process environment. Due to the closed cooling system, condensation on the process side of the drum surface is a thing of the past. This means that hygroscopic products can also be flaked with excellent results. The entire cooling water system is constructed of stainless steel. The entire cooling water system can be accessed for inspection and maintenance without disassembling the drum flaker.

Special casing for poisonous and dangerous substances Considering the current strict environmental and health regulations, most drum flakers are equipped with a completely sealed casing. This not only ensures that the operators do not come into contact with poisonous or dangerous substances, but also protects the product from external influences. Products sensitive to oxygen, in particular, can be protected effectively by nitrogen gas blanketing, for example.

Closed model for a protected process environment

Some products leave heavy sublimate residue on the inside of the casing, however using a design with a warmed wall can limit regular cleaning to a minimum. The casing around the drum flaker makes it possible to protect the product and the environment. The advantages are clear: products that smell bad, products that are toxic, products that are hygroscopic, products that oxidize, etc., can now be flaked in a protected environment. Facilities to make the drum flaker inert, using a protective layer of gas like nitrogen, are already present. This means that the production quality is maintained at a constant, high level.

Minimal production of dust The design of GMF-Gouda's blade holders has a distinct number of advantages: The knife holder (in which the knife is placed) is so rugged, and of a specific sort of material, so that the scraping process cannot cause vibrations; The rugged design achieves an equal division of pressure across the total length of the drum. By ruling out vibrations the product film is removed equally everywhere and the product cannot run under the knife; The design of the knife holder is such that the knife can be quickly inspected and/or replaced. It is also equipped with a system for direct and even knife pressure adjustment. The knife pressure for each product can therefore be set to achieve the optimal scraping results in combination with a minimum of knife wear. This adjustment is outside the process environment. Knives are available in various materials, varying from steel to bronze and plastic. The choice of material is dependent on the product to be processed. The shape of the flakes, to some extent, can be determined in advance by the choice of scraper system.

Advantages of the GMF Gouda drum flaker
Reliable and economical process; Completely sealed cooling system; No contamination possible between coolant and product; Limited floor space required; Gastight casing, thus it is possible to inert the process; Unit designed for easy access for maintenance and cleaning; Wide choice of construction materials; Easy maintenance.	Standard closed drum flaker model with integrated transporter,      set on a solid base frame

Pilot plant ensures process data GMF-Gouda has an extended database with knowledge and experience of a large number of products at its disposal. For products that have not previously been tested, or for existing processes that are candidates for a closer optimization, the pilot plant can be used. All processes can be copied in our laboratory. The reliability of this process is evident from the success of hundreds of installations worldwide. In certain cases, tests can also be carried out at the customer's facility. To this end, mobile test machines can be hired for certain periods.

Test facilities Feasibility test We need a small amount of product to judge if the product can be flaked. Trial run We need about 1 kg of product to determine the products behaviour on a pilot drum flaker and to produce a small sample. Guarantee test For a guarantee test we need between 50 and 100 kg of product to establish the capacity and process parameters. Based on this process guarantees are given and an extensive report is made.

A section of the test factory where products are tested