WO2013039461A1 - Kiln for firing ceramic articles - Google Patents

Abstract

The kiln for firing ceramic articles relates to a technical field, more specifically to continuous firing kilns and can be used for heat treating ceramic construction articles, in particular hollow bricks and blocks. The kiln for firing ceramic articles consists of a main channel (2) which is filled with the articles (3), and a circulation channel (4) with devices for the movement of a gas (6), which devices provide for the circulation of the gas by bleeding same from the main channel (2) and returning it to the main channel (2) from the opposite end. Furthermore, the firing kiln is divided into sections by partitions with openings. Also, the partitions between the sections are additionally provided with guide elements in the form of dampers (11) for generating a flow of gas between the sections. Additionally, a heat exchanger (12) equipped with a ventilator is situated in the circulation channel (4).

Description

 Ceramic kiln

 Technical field

 The invention relates to the field of technology, namely, to continuous kilns and can be used for heat treatment of building ceramic products, in particular, hollow bricks and blocks.

 State of the art

The known device for the thermal treatment of ceramic hollow products (patent application WO 2008/063538 A2, IPC ⁶ C04B 35/638, F27B 9/00) is selected as the prototype (Appendix 1 - application, Appendix 2 - translation) and consists of a main channel filled products and a circulation channel with fans that provide gas circulation by taking gas from the main channel and returning it to the main channel from the opposite side. It should be noted that in the known device for the heat treatment of hollow products, a gas circulation system is created that improves the uniformity of the heat treatment of hollow products, but has the following disadvantages.

With the created gas circulation in the main channel of the furnace, there is an active mixing of gas flows along the entire length of the channel, which excludes the possibility of heating, firing and cooling of hollow products in strict accordance with technology. Another disadvantage of the known device is that, together with the combustion products, steam is removed from the furnace, which is formed during the evaporation of water from the loaded raw products, while the heat expended on steam generation is removed along with the steam from the furnace.

 Disclosure of invention

 The basis of the invention, the device is tasked by improving the design of the furnace by introducing additional elements to provide a predetermined and controlled mode of heating, firing and cooling of products, which will ensure strict implementation of the firing technology and, accordingly, the quality of the fired products.

The next objective of the invention to the device is that in the furnace by the maximum degree of heat recovery of the products of combustion, steam and air to achieve maximum savings of thermal energy used for firing ceramic products.

In the claimed device, the problem is solved in that in a kiln for firing ceramic products, including a main channel filled with products and a circulation channel with gas moving devices that circulate gas by taking gas from the main channel and returning it to the main channel from the opposite side, according to the invention , the furnace is divided into sections by partitions with holes.

To eliminate active mixing of the gas, which is a coolant, transverse partitions with openings that are capable of passing through limited gas flow and prevent intensive mixing of gas along the length of the furnace.

 The task set as the basis of the invention is also achieved by the fact that in the partitions between the sections of the furnace, guide elements are additionally made - dampers for creating a directed gas flow between the sections, cutting off part of the circulation stream of the previous section and feeding it to the next section. The implementation of dampers with adjustable tilt makes it possible to change the speed and direction of gas movement between sections.

 Thus, by improving the design of the furnace, an intense circulating gas flow is formed in the main channel, which ensures uniform temperature in each section in width and height in the working space of the main channel and a controlled gas flow along the main channel, which reduces the firing time while improving quality products.

 The device of the kiln for firing ceramic products has another improvement, due to which an additional technical result is obtained.

 The next task, which is the basis of the invention is achieved by the fact that in the circulation channel of the furnace is additionally installed at least one heat exchanger.

To return the heat of vaporization to the process - to the heating zone of products, you need this steam or pass the gas-vapor mixture through a heat exchanger, which is located in the circulation channel in the heating zone. In this heat exchanger, not only the vapor-gas mixture is cooled, but also the condensation of the vapor. Thus, the heat of condensation and heated gas mixture is used to heat products.

 The heat exchanger can additionally be equipped with a fan to provide the necessary gas flow rate.

Using this combination of essential features, including distinctive features, allows, in comparison with the prototype:

- provide a predetermined and controlled mode of heating, firing and cooling of products;

 - achieve maximum heat energy savings.

 Description of drawings

 The description of the kiln for firing ceramic products is confirmed by the drawings, where:

 FIG. 1 - shows a cross section of a kiln for firing ceramic products,

 FIG. 2 - execution of transverse partitions with holes in the furnace in the context of figure 1 along the section aa,

 FIG. 3 - the execution of the guide elements in the furnace in the context of figure 1 along the section aa,

 FIG. 4 - execution of the heat exchanger in the furnace in the context of figure 1 along section A-A.

The invention is described in detail with reference to the drawings. The kiln for firing ceramic products is shown in Fig. 1 and consists of an external casing 1, a main channel 2, which is filled with hollow products 3 and a circulation channel 4, separated from the main channel 2 by partitions 5 and necessary to create an intense circulating gas flow that helps to accelerate heat transfer . Fans 6 are installed in the upper part of each section of the main channel 2, for gas extraction from the upper part of the main channel 2 and its supply to the lower part through the circulation channel 4.

 The entire length of the furnace is divided into sections by transverse partitions 7 (Fig. 2) with holes 8, while in the case of a furnace with mechanical movement of hollow products 3, the transverse partitions 7 are made of two parts: a fixed part 7, blocking the circulation channel 4 and the movable part 1a (Fig. 1) moving together with hollow articles 3.

To ensure the directed movement of gas inside the furnace between the sections, inlet 9 (Fig. 2) and exhaust 10 fans can be installed.

In the transverse partitions 7 (Fig. 3) with openings 8, guide elements are additionally made - shutters 1 1 with an adjustable slope, while the openings 8 are made according to the dimensions of the shutters 11 and in this case there is no need to install fans 9 and 10. In the circulation channel 4 (Fig. 4), a heat exchanger 12 is additionally installed, which is additionally equipped with a fan 13.

 Heating of products can take place from any source of heat: by burning fuel, using an electric heater, or in another way.

 The design of the kiln for firing ceramic products is applicable both to furnaces with mechanical movement of products, and to furnaces with a fixed arrangement of products.

 An embodiment of the invention

 The kiln for ceramic works as follows.

 The main channel 2 is filled with hollow products 3 either in each section separately - for furnaces with a fixed arrangement of products 3, or through the outer sections - for furnaces with mechanical movement of products 3. The furnace has three zones: a heating, firing and cooling zone. The processes of heat and mass transfer in the furnace are similar to the processes occurring in conventional tunnel and ring furnaces. In the proposed furnace due to the presence of fans 6, the intensity of heat and mass transfer is significantly increased.

The heat exchange between the gas medium of the furnace (coolant) and the void products 3 (Fig. 1) within each section is due to the multiple passage of gas around and through the void products 3 by taking gas from the top part of the main channel 2 by the fan 6 and feeding it through the circulation channel 4 to the lower part of the main channel 2. The transfer of thermal energy between the sections (along the main channel 2) is carried out by moving the gas (coolant) through the holes 8 (figure 2) in the partitions 7.

 The first way to optimize the heat transfer process between sections of the furnace is done by selecting the size of the holes 8 in the partitions 7, while the gas itself is moved by creating a pressure difference between the sections, for example, fans 9 and 10. The second way to optimize the heat transfer process between the sections of the furnace is done by adjusting the slope shutters 11 (Fig. 3).

The steam generated in the furnace, as well as the combustion products (when using fuel), by the guide flaps 11 (Fig. 4) are supplied to the furnace section from which they are taken through the heat exchanger 12, while the incoming gases are cooled in the heat exchanger 12 and the steam is partially condensed, which provides heating of the hollow products 3 (not shown conditionally), filled into the furnace. With a large pressure drop in the heat exchanger 12, a fan 13 is used to ensure the necessary gas flow through it. When using a fan 13, the steam-gas mixture can be supplied to the section from which it is taken to the heat exchanger 12, can be made through openings 8 without shutters 11 due to vacuum, created by the fan 13. Industrial applicability

 The above information confirms that the advanced ceramic kiln is industrially applicable using different versions. As a result of the application of the proposed solutions, high-quality calcined products were obtained due to the strict implementation of the firing technology with minimal energy costs. A pilot sample of a ceramic products kiln was manufactured, the operational characteristics of which confirmed the achievement of the desired technical result.

Claims

Formula  A kiln for firing ceramic products, including a main channel filled with products and a circulation channel with gas transfer devices that provide gas circulation by taking gas from the main channel and returning it to the main channel from the opposite side, characterized in that the furnace is divided into sections by openings with openings . The furnace according to claim 1, characterized in that in the partitions between the sections additionally made guide elements for creating a gas flow between the sections. The furnace according to claim 1, characterized in that at least one heat exchanger is additionally installed in the circulation channel.  The furnace according to claim 3, characterized in that the heat exchanger is additionally equipped with a fan.