CONTINUAL PRODUCTION LINE FOR THE MANUFACTURING OF CLAY

PRODUCTS

Field of invention

The subject invention refers to a continual line for the production of clay products, such as e.g. bricks and roof tiles, which are used as basic construction materials. As such, this invention is classified in accordance to the International Classification of Patents (8th edition) in the B category (production processes), to be exact, in class B28 - the processing of cement, clay or rock, subclass B28 C - preparation of clay, i.e. the production of mixtures containing clay, and is correctly classified in class 1/22 - devices or processes for obtaining or processing clay together with ingredients for treatment assisted by heating, moistening or vacuum treatment (B28 C 1/22). It is likewise possible to classify the subject invention in class B28 C 9/00 - general arrangement or formational plan for the production of clay products.

Technical problem

The production of clay products used for constructional purposes (bricks and roof tiles) is a process that has been well-known for a long series of years and a large number of production processes exist that are automated to a certain extent. Due to the nature of the production process of constructional brick itself, which is always executed in very large quantities in order reach an economically satisfying production, it is very important that the production process itself is automated as much as possible, i.e. the production process should be maximally economical and flexible for everyday use. The mentioned technical problem is solved in its entirety with the use of the production line according to this invention.

Solution to the technical problem

The technical solution of the invention enables the realization of the production line of clay products, which is very flexible in the production process (the possibility of running the line in only 1,5-2 hours) and is 75% more economical than any known clay production process. The mentioned is attained with a production process that includes drying in three intermediate phases, where the pressed products are dried in order for excess moisture to escape. The necessary conditions are reached with the use of an appropriate drying regime attained with the assistance of a climatic device, while natural gas infra-heaters are used in

the preheating and baking phases, reaching the desired preheating (150-450 °C) and baking temperatures (450-1200 °C). During the final cooling phase, due to energy efficiency, the products are conveyed into a climatic chamber where circulation of the surrounding air takes place.

State of the art

The current production process of clay products includes five basic production phases: pressing of the clay, drying the products, baking the clay products in ovens set at a temperature of 600-1200 °C, cooling the clay products and packaging of the final products onto palettes. Because of the nature of this type of production, which is demanded in very large quantities, a substantial amount of automation is required during the entire process. In this manner, an existing clay product production line is designed to the degree that the clay products are pressed and then immediately and automatically arranged in wagons that are conveyed through a drying chamber and then rearranged on fire-clay wagons, which travel through an oven, where the clay products are heated to temperature of 600-1200 °C. After that process, the clay products are dried and stacked and packaged onto palettes. Because of such a process, which though continuous, requires manipulation of the final product throughout the entire process, i.e. during transitions from phase to phase (drying - baking), the final product undergoes the possibility of suffering a decrease in quality. The quality of a brick or roof-tile that undergoes manipulation in intermediate phases is lessened. Likewise, in order to achieve an economically justified (profitable) production, a very large manufacturing capacity is required in order to financially cover the very large energy demands of this type of production. This production is constantly on the edge of economical justification because of such demands. Because of the necessity for a large capacity, the clay-baking oven has large dimensions. To achieve high temperatures in the oven (approximately 1100 °C) such an oven is constantly in function, i.e. it is necessary to constantly maintain a high temperature inside the oven, which requires very large quantities of natural gas or other power sources for heating. The shutting down of such production lines is executed exclusively for maintenance and the cost of the reactivation of production is approximately 30000-60000 EUR, depending on the capacity and size of the oven. If the oven is not heated to its production temperature, it is not possible to reactivate the production line; the cost of power sources for achieving optimal production conditions totals 30000-60000 EUR. With known methods of clay product manufacturing, such large

ovens are the source of large heat losses because an immense volume of air in the oven as well as the amour of the oven must be needlessly heated.

The impossibility of shutting down the classic production process (oven) in any given moment when demand is reduced poses a problem with the storage of the excessively manufactured products, i.e. maintaining uninterrupted production, while during winter periods such storage in most cases does not satisfy current demand.

Disadvantages of the classic production process using large ovens are as follows:

- immediate changes in the production program are not possible

- the need for a diverse fleet of machinery is present due to the need for manipulation of the product between the individual phases in the technological process between individual technological stages, due to rearrangements and in case of delays, useful technological parameters are lost (the product is cooled), which leads to the elongation of the process and an increase in the number of low-quality products (rejects)

- because it is impossible to reach a constant temperate inside the oven and insure identical technological parameters, the quality of the final product inside one packet fluctuates

- a large amount of natural gas is emitted into the environment due to classical incineration and as a result, a less profitable process

- relatively long and complicated installation of the machinery, which is not mobile

With the production line of clay products according to this invention, all stated disadvantages are avoided. The mentioned production line is composed of the familiar pressing process of the product, after which the product is placed on a conveyor belt with a continuous transit, and without additional manipulation of the product, advances to the following phases: drying (wet phase, partially dry phase and dry phase), preheating, baking and cooling. Natural gas infra-heaters are used for heating and baking the products, where direct transition of heat from the surface of the heater on the final product is achieved. The necessary temperature required by each individual product is attained while heat losses are reduced to a minimum. Upon cooling, the cooled final product departs the production line and is packaged on palettes with classical machines for the packaging of clay products.

The essence of the invention

The continuous production line with natural gas infra-heaters according to this invention contains an entire series of preferences in comparison with the existing clay product production line. Due to its modulation, this production line may be placed in practically any industrial hall because no negative byproducts are created during the operation of the production line and only protection from rain and moisture is required. Individual components of the production line (modules) are composed of parts with a length of approximately 2 meters and with their arrangement with one another, it is possible to assemble a production line with individual and separate production phases (drying, preheating, baking, cooling). Using such parts, assembly (e.g. in a place where quality raw materials are abundant - clay) is possible in a short period of time, as is disassembly in case of the depletion of raw materials and the need to relocate production to another position. Due to maximum modulation, it is very simple to increase the production capacity of the production line as well as expanding the product assortment - with the addition of a series of components parallel with the existing elements of the production line. Production of clay products on the production line according to this invention insures maximum equality and a guaranteed quality with every unit of the product. Reason being . that with classical baking processes in standard ovens, the temperature is not completely uniform in all parts of the oven; while attempting to reach optimal conditions, some areas of classical ovens are significantly overheated in comparison with ideal conditions while other areas of the oven are at temperatures lower than desired. Hence, with the use of infra- heaters the transition of heat is direct, from the surface of the heater onto the final product, where exactly the temperature required by each type of product, depending on its dimensions and sort, is achieved. What results is optimal quality as well as 75% less energy consumption (natural gas for heating). The burning of natural gas within the natural gas infra-heaters is the most ecologically acceptable solution for the use of thermal energy in a technological process. Use of the production line in accordance with this invention as well as the use of natural gas infra-heaters creates a direct transition of heat from the infra- heaters onto the final product, and in fact all transited energy is used for baking the product. The production line itself has an insulation function during the preheating and baking phases as opposed to the classical process, in which the oven has an accumulating function.

Brief description of the figures

• Figure 1 schematically presents the construction of the continual production line for the manufacturing of clay products with all fundamental elements of the system

• Figure 2 presents possibilities in the assembly of the production line in regards to the each phase of the process, which depends on the space available at any given location

Description of the preferred realization method of the invention

This production line according to this invention is schematically shown in figure 1 , where it can be seen that it is composed of 4 basic phases: the drying phase (A), the preheating phase (B), the baking phase (C) and the cooling phase (D). During the arrangement of the individual phases, a modular element (1) of approximately 2 meters in length is used. Every element is basically of an equivalent construction with a conveyor belt (2), which continues from one module to another. The conveyor belt (2) is driven with one or more motors (3), and the speed of the belt can vary anywhere from 2-10 cm/s depending on the technological process for each individual type of product. Nevertheless, the desired speed of the belt is 5 cm/s. The modules (1) that are used to construct the preheating (B) and the baking (C) phases have natural gas infra-heaters on their top and bottom surfaces (4), with which is achieved the necessary temperature required by the process. Depending on demand, the number of infra-heaters (4) on each module can range from 3-7, yet 5 heaters on each module is the desired amount. The power of each infra-heater (4) is 30-60 kW while the desired power is 45 kW per heater. In the case where a larger number of infra- heaters (4) are used, while the temperature requirements are lowered (e.g. in the preheating phase (B)) adjustments are made that for example only 3 heaters are in use while in such a case, the heaters operate with decreased pressure of natural gas, with which a lower power of the heater is achieved.

The production process of the defined product (7) is carried out in the following manner: 1. Upon preparation and processing of the clay with the standard preparation process, the attained material is pressed in extruders. Upon exiting the extruders, the clay is cut at the desired length. Each individual product (7) is then automatically placed onto the continual production line in accordance with this invention.

2. The product then enters into an insulated chamber where the drying phase (A) begins, which consists of three intermediate phases (wet phase, partially dry phase and dry phase). The intermediate phases differ due to only the differing parameters imposed in the climate chamber (5). During the drying phase moisture is drawn out of the product in order to avoid expansion of the moisture remaining in the clay that may result in the explosion of the clay and destruction of the product (7) during the preheating and baking phases. The temperature in this phase changes from the entry temperature of 20 °C to a temperature of 150 °C at the exit. The duration of the drying phase is about 20-40 minutes, depending on requirements of each individual type of product and the given speed of the conveyor belt (2).

3. Exiting the drying phase (A), the products (7) preheated to a temperature of roughly 150 °C enter the preheating phase (B), which is a necessary phase so that the products avoid an abrupt temperature increase that may lead to destruction of the product, hi this phase the products (7) continue their course on the conveyor belt (2) while individual modules (2) are equipped with infra-heaters (4) whereby only three heaters are active in the wanted process, because they emit a sufficient amount of heat for preheating. In this phase, with duration of 15-30 minutes and recommended duration of 20 minutes, the temperature of the product increases to approximately 450 °C and continue on the conveyor belt (2) into the baking phase (C).

4. hi the baking phase (C), using all 5 infra-heaters (4) or 7 infra-heaters in a more powerful variation, the final product is gradually being baked at a starting temperature of 450 °C up to 1200 °C, with a recommended baking temperature of 1100 ⁰ C. The duration of the baking phase (C) is 20-40 minutes, while the optimal time for the product to reside in the oven is approximately 30 minutes.

5. Upon exiting the oven, the cooling phase (D) begins. The finalized product (7) is situated on the conveyor belt, which exits the oven with a temperature of approximately 1100 °C and enters a cooling chamber where air at room temperature (8) flows onto the products and in this manner cools the product to its final temperature of approximately 50 °C. The flowing air (8) is heated upon contact with the heated products and through recirculation (6) is lead to the climate chamber (5) where it is used in the drying phase (A). The duration of the cooling phase (D) is 10-20 minutes, recommended 15 minutes.

6. Being cooled at a temperature of approximately 50 °C, the finalized product leaves the production line and is packaged using known packaging metho ^' ds, which are not

the subject of this invention, onto palettes in the most durable position for transportation.

Using natural gas infra-heaters (4) for heating and baking the products, the production line can be turned on and off in short periods of time, without compromising the quality or economics of the product. A larger starting capacity enables operation without reserves of the types of product demanded on the market at that moment, which means operation with minimal fixed costs and maximum flexibility.

In the described manner, the final product is protected from unnecessary manipulations during the production process, and is of maximum quality with minimum energy invested into its baking.

In case of a shutdown in production due to a possible malfunction on individual sections of the production system, technological parameters are not lost, but the quality of the final product is increased above regulated standards, since the product longer inhabits an environment with an increased temperature whereby improved exploitation of the product's properties is obtained.

With use of the modular elements (1), arrangement of the production line is possible, considering the individual phases of the process, in a large number of different formations depending on the space available, and possible arrangement variations of the production line are shown in figure 2:

- a straight production line - figure 2.1 a discontinued production line - figure 2.2 an angled and angularly discontinued production line - figure 2.3

Constructing the continual production line in such a manner fully allows supervision and operation of the production line by remote control, as well as complete control of all technological parameters along the production line. It is likewise possible to easily integrate this process into the surveillance system of such a business activity. This invention is not limited to the outlined construction; to a professional in this field, it will be clear that the described process is merely one possible realization of this invention and the use of the portrayed devices can be exchanged with their equivalents that yield the same results, without alterations of the invention as described.