Rotary kiln with vacuum surface and production method thereof

Abstract

The invention relates to a technology for preventing heat loss of the outer surface of a high-temperature rotary kiln.

Description

Technical Field

[0001] The present invention relates to the cement industry and the ceramic industry.

[0002] The present invention particularly relates to a technology for preventing heat loss from the outer surface of a high-temperature rotary kiln. Background Art

[0003] Today, all industries that operate at high temperatures and use powdered products use rotary kilns. The outer surface of a rotary kiln is usually made of metal materials, which have high thermal conductivity. Although the inside of the rotary kiln is coated with refractory materials for thermal insulation, a large amount of heat is still lost from the outer surface of the rotary kiln. For example, a cement rotary kiln operating at 900°C has an outer surface temperature of about 300°C, and this part of the heat may be lost. In order to prevent such heat loss or to utilize the heat generated therein, various methods are used. For example, vacuum insulation panels (VIP) with low thermal conductivity are used to reduce heat loss; or the generated heat is transferred out through a heat exchanger and hot water is generated by this heat, thereby obtaining a method for generating hot water.

[0004] In the prior art, there have been some studies on energy conservation of rotary kilns. The article entitled "Empirical and Statistical Modeling of Heat Losses from External Surfaces of Cement Rotary Kilns" published by Ban§ et al. discusses the heat loss problem of rotary kilns. The study "Mathematical Modeling of Heat Recovery in Rotary Kilns" published by Sbgut et al. provides a mathematical model for heat recovery of rotary kilns. "Heat Transfer Modeling of Rotary Kilns: Part I, Experiments with Test Kilns" published by Barry et al. describes in detail the heat distribution on the walls of rotary kilns. "Energy Audit and Recovery of Dry Process Cement Rotary Kiln Systems - Case Studies" published by Engin et al. reports that the energy loss of cement production rotary kilns is 40%, of which 15% comes from the kiln surface, and recommends that a high-cost second layer of insulation should be applied to reduce heat losses. "Techno-economic Evaluation of Radiant Waste Heat Recovery Systems for Rotary Kiln Shells" published by Fierro et al. is a study on heat recovery from the surface of rotary kilns.

[0005] US Patent Document US5695329A proposes adding additional insulation materials to the outer surface of the rotary kiln. European Patent Document EP2799800B1 studies the prevention of heat loss by setting a vacuum insulation panel on the outside of the kiln body, but the effect is not good because the thermal conductivity of the material is much higher than that of a vacuum environment. Chinese Patent CN102818449A discloses the application of vacuum technology in certain areas inside the rotary kiln, but its purpose is not to prevent heat loss.

[0006] Although there have been several studies in this area, the current research results do not show the required effectiveness and practical level. Existing technologies cannot effectively prevent heat loss from the surface of rotary kilns. Solutions for heat loss from the surface of rotary kilns have not yet gone beyond reducing heat loss by recovering the lost heat or using insulation materials.

[0007] Therefore, due to the shortcomings of existing solutions, it is particularly necessary to carry out new technological research and development in related fields to prevent and eliminate these problems. Summary of the invention

[0008] The present invention relates to a rotary kiln system having a vacuum surface that meets the above needs, eliminates all disadvantages and provides some additional advantages.

[0009] The main purpose of this invention is to develop a system that retains or utilizes all the heat through the vacuum system.

[0010] Another object of the present invention is to develop a system that prevents a large amount of energy from being wasted.

[0011] A further object of the present invention is to provide less carbon (or fuel) emissions, thereby reducing carbon dioxide (CO 2 )emission.

[0012] Another object of the invention is to enable the invention to be partially applied to existing kilns and not just limited to the production of new kilns.

[0013] In order to achieve the above-mentioned purpose, the present invention provides a rotary kiln system, which has a vacuum surface, including a metal, polymer or composite material shell coated on the inner and outer surfaces, so that the rotary kiln forms a double-wall structure; a vacuum area is formed between the outer surface and the shell, and vacuum operation is performed in the area; a seal is used to connect the outer surface of the rotary kiln and the inner surface of the shell; the temperature of the inner surface of the kiln is monitored in real time by a temperature sensor, and the temperature sensor is preferably arranged on the inner surface of the shell.

[0014] The structural features and all advantages of the present invention will be more clearly understood in the following drawings and detailed description, and therefore, the evaluation should be made taking into account the detailed explanations and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Shown is a view of a rotary kiln with a vacuum surface.

[0016] Reference Numbers

[0017] 1 External surface

[0018] 2. Housing

[0019] 3 Refractory Bricks

[0020] 4 holes

[0021] 5 Seals

[0022] 6 Vacuum Zone

[0023] 7 Thermometer DETAILED DESCRIPTION

[0024] In the detailed description, the subject matter of the present invention is described in a manner that does not constitute any limiting effect, but is only used for a better understanding of the content of the present invention.

[0025] like Figure 1 Shown is a schematic diagram of a rotary kiln system with a vacuum surface of the present invention, which in its most basic form comprises:

[0026] - a metal, polymer or composite material shell (2) coated on the inner and / or outer surface (1) of the rotary kiln, so that the rotary kiln forms a double-walled structure;

[0027] - a vacuum zone (6) between the outer surface (1) and the housing (2), in which the vacuum operation is carried out;

[0028] - an air seal (5) for connecting the outer surface (1) of the rotary kiln with the inner surface of the outer shell (2);

[0029] - an aluminum foil / layer (sheet), preferably applied to the inner surface of the metal housing;

[0030] - An infrared thermometer (7), preferably installed inside the outer tube, for measuring the temperature value of the inner surface of the tube, and a solar panel is installed on the surface of the outer tube to meet the power demand of the thermometer (7).

[0031] In the present invention, a housing (2) is provided, which is evacuated to keep the outer surface (1) of the rotary kiln in a vacuum state with the outer area of ​​the housing (2). In this way, most or all of the heat loss from the outer surface of 300°C can be prevented. In addition, the present invention also provides a method for maintaining the operating temperature of the rotary kiln at 900°C with less energy (maintained at higher temperatures by laying refractory materials and generating heat). The system uses a medium with the lowest thermal conductivity, which depends on the vacuum degree. The fewer the gas molecules, the worse the thermal conductivity. Heat cannot be easily lost from the vacuum environment, or its loss is reduced to a minimum level. Refractory bricks (3) with low thermal conductivity are placed between the housing (2) and the outer surface (1) of the rotary kiln. Therefore, the distance between the housing (2) and the outer surface (1) of the rotary kiln is kept constant. Since the refractory bricks (3) have low thermal conductivity, the heat loss from these points is also minimized. The metal housing (2) is connected to the outer surface (1) of the rotary kiln at both ends by seals (5). The seal (5) can be made of titanium, stainless steel, aluminum or a copper ring. The seal (5) prevents air leakage and maintains a vacuum state in the system. Therefore, the area (6) between the outer surface (1) of the rotary kiln and the shell (2) can be evacuated. The vacuum area (6) is established by at least one vacuum pump located on the outer surface of the shell (1) and arranged in the hole (4), and the vacuum operation is completed through the hole (4). When the required vacuum value is reached, the vacuum pump located at the hole (4) is closed by a valve. In a preferred embodiment of the invention, a barometer is installed in the hole, and the vacuum value therein can be observed in real time. At the same time, the temperature of the inner surface of the rotary kiln can be measured in real time by a thermometer (7) installed on the inner surface of the shell.

[0032] Through the technical solution of the present invention, a metal shell (2) is added to the outer surface (1) of the rotary kiln, and the air therein is evacuated, thereby providing a vacuum environment, which is suitable for a system for preventing heat loss from the outer surface. Therefore, through the vacuum system, the loss of surface heat can be completely prevented. The invention reduces carbon emissions (or fuel), thereby reducing CO 2 The energy consumption is minimized by heat preservation. Since the invention can be applied to existing rotary kilns, there is no need to produce new rotary kilns. In addition, the invention can also be applied to the production of new rotary kilns. The energy saving effect achieved by the invention is not a one-time effect, but is continuously effective as the factory production continues.

Claims

1. A rotary kiln system with a vacuum surface, characterized in that: include: A metal or polymer or composite material shell (2) is coated on the inner and / or outer surface (1) of the rotary kiln, so that the rotary kiln forms a double-wall structure; A vacuum zone (6) is formed between the outer surface (1) and the outer shell (2) of the rotary kiln, and vacuum operation is performed in the vacuum zone; An air seal (5) is used to connect the outer surface (1) of the rotary kiln with the inner surface of the outer shell (2).

2. The system according to claim 1, characterized in that The inner surface of the housing (2) is coated with an aluminum foil or layer.

3. The system according to claim 1, characterized in that The air in the vacuum zone (6) is evacuated and filled with one of xenon gas, dichlorofluoromethane, chloroform or sulfur dioxide gas, and then re-vacuumed.

4. The system according to claim 1, characterized in that A hole (4) is provided at at least one point of the housing (2) for forming a vacuum operation, thereby forming a vacuum zone (6), and at least one vacuum pump and a valve are connected to the hole (4).

5. The system according to claim 1, characterized in that Refractory bricks (3) are arranged between the outer shell (2) and the inner surface (1) to maintain a fixed distance therebetween.

6. The system according to claim 1, characterized in that The air seal (5) is made of titanium, steel, iron, stainless steel, aluminum or a copper ring.

7. The system according to claim 1, characterized in that An infrared thermometer (7) is placed inside the outer tube to measure the temperature value of the inner surface of the tube, and a solar panel and a battery are arranged outside the outer shell to meet the power demand of the thermometer (7).

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