Tunnel kiln baking moisture control method

Abstract

The invention relates to the technical field of tunnel kilns, in particular to a tunnel kiln baking moisture control method which comprises the steps that an automatic control system is introduced, and the control system receives data of hot air moisture detectors installed at different positions; the amount of natural gas supplied to the combustion furnace is regulated and controlled, and a valve is adjusted to control heat and heat distribution; the control system regulates and controls the air volume of the air volume assembly, the air volume of the dust removal air feeder and the air volume of the dust removal induced draft fan in the baking stage to be 1800 cubic meters per hour. According to the method, the baking temperature and baking starting and stopping of the combustion furnace in the heating system and the air volume in the air volume system are monitored and regulated in real time through the automatic control system and the hot air moisture detector; accurate control is achieved, errors caused by manual operation are avoided, the production efficiency of the tunnel kiln can be remarkably improved, meanwhile, energy consumption of products per ton is reduced, and the purposes of energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel kilns, and in particular to a method for controlling moisture content in tunnel kiln baking. Background Art

[0002] A tunnel kiln is a continuous kiln that looks like a tunnel. It is mainly built of refractory materials, thermal insulation materials and building materials, and is equipped with kiln cars and other vehicles that are similar to tunnels. It is a modern continuous firing thermal equipment. Tunnel kilns are widely used in the roasting production of ceramic products and the baking of materials. They are also used in metallurgical industries such as abrasives. In addition, because tunnel kilns have a long length and a large baking space, tunnel kilns are often used to dry and bake the moisture in the products when baking large quantities of products.

[0003] In actual operation, the tunnel kiln is a semi-enclosed structure, so the air flow in its internal space is poor. Manual operation is very easy to cause danger. Manual empirical judgment and operation are prone to errors. The operation method and process are often summarized after many trials and errors, and the baking temperature, baking air volume and baking time cannot be accurately controlled, resulting in a waste of energy and time. For this reason, we propose a tunnel kiln baking moisture control method. Summary of the invention

[0004] Technical issues solved:

[0005] In view of the deficiencies in the prior art, the present invention provides a method for controlling moisture in a tunnel kiln baking, thereby solving the technical problems mentioned in the background technology.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] A method for controlling moisture in baking of a tunnel kiln is provided. An automatic control system is introduced. The control system receives data from hot air moisture detectors installed at different positions, and adjusts the amount of natural gas supplied to a combustion furnace and adjusts valves to control the amount of heat and heat distribution. The control system adjusts the air volume of an air volume component. The air volumes of a dust removal blower and a dust removal exhaust fan are both set to 1,800 cubic meters per hour during the baking stage. In addition, in the material baking area, the system controls the lifting plate in the tunnel kiln to guide the wind direction to blow toward the material to be baked. The control system adjusts the heat of the heating component. The hot air moisture detector is used to detect in real time that the moisture content of the hot air at the outlet is significantly reduced. The automatic control system controls the combustion furnace in the heating system to stop burning, and the residual heat is used to bake the moisture in the material.

[0008] The steps of the automatic control system participating in the baking process of the material to be baked are as follows:

[0009] S1: The operator sets the baking air volume to 1800 cubic meters per hour and the baking temperature to 120°C according to the material to be baked;

[0010] S2: Control the heating system through the automatic control system to start heating;

[0011] S3: Hot air moisture detector monitors the hot air moisture at the inlet, middle and outlet in real time;

[0012] S4: The temperature sensor at the outlet detects the outlet hot air temperature and transmits it to the automatic control system;

[0013] S5: The automatic control system adjusts the output efficiency of the heating system, and the temperature sensor detects that the set temperature has been reached;

[0014] S6: The moisture content of the hot air at the outlet decreases, and the automatic control system shuts down the heating system;

[0015] S7: Use the residual heat to dry the remaining moisture in the material to be baked.

[0016] In a possible implementation, a tunnel kiln is included, and hot air moisture detectors are installed at the inlet, middle section and outlet of each tunnel kiln. Air volume components are provided at the inlet and outlet of the tunnel kiln, and the inlet of the tunnel kiln is connected to a heating component.

[0017] In one possible implementation, the air volume component includes a connecting pipe, and multiple tunnel kilns are connected through the connecting pipe. An air supply duct is provided at the entrance of the tunnel kiln, a dust-removing supply air fan is provided at the left end of each air supply duct, and a dust-removing induced draft fan is provided at the right end of each induced draft duct. The air volume of the dust-removing supply air fan and the dust-removing induced draft fan is set to 1,800 cubic meters per hour.

[0018] In one possible implementation, the heating component includes a combustion furnace, a heat transfer pipe is installed on the top of the combustion furnace, the heat transfer pipe is connected to the combustion furnace through a one-way valve, the one-way valve is provided with a multi-branch valve, and a regulating valve is provided inside the branch valve. The temperature of the combustion furnace in the preheating stage is set to normal temperature -120°C, the time is about 2 hours, and the baking stage is set to 120°C.

[0019] In a possible implementation, a temperature sensor is provided at the exit of the tunnel kiln.

[0020] In a possible implementation, a plurality of the tunnel kilns are built in parallel.

[0021] In a possible implementation, a material loading vehicle is provided inside the tunnel kiln, and a plurality of lifting plates for guiding wind direction are installed on the inner wall of the baking section of the tunnel kiln, and the lifting and lowering of the lifting plates form an angle of 30° with the inner wall of the tunnel kiln.

[0022] In a possible implementation, the kiln wall, kiln roof, kiln car and other parts of the tunnel kiln need to use refractory materials with high temperature resistance and good heat insulation performance.

[0023] In a possible implementation, the air volume of the dust removal supply fan and the dust removal exhaust fan is only 1200 cubic meters per hour in the preheating stage, and is set to 1800 cubic meters per hour in the baking stage.

[0024] In a possible implementation, the automatic control system controls the amount of natural gas fuel supplied to the combustion furnace based on data from the temperature sensor, and keeps the natural gas supply rate unchanged while maintaining a baking temperature of 120°C.

[0025] Beneficial effects compared with the prior art:

[0026] 1. In this solution, the baking temperature of the combustion furnace in the heating system, the start and stop of baking, and the air volume in the air volume system are monitored and adjusted in real time through the automatic control system and the hot air moisture detector, so as to achieve precise control and avoid errors caused by manual operation;

[0027] 2. In this solution, the baking process and equipment parameters of the materials to be baked can be continuously optimized and adjusted through the automatic control system and hot air moisture detector to obtain the optimal baking process and equipment parameters, thus reducing the workload of operators;

[0028] 3. In this solution, the waste heat of the heating components can be used to bake out the final moisture of the material through the automatic control system and the hot air moisture detector, which can significantly improve the production efficiency of the tunnel kiln, while reducing the energy consumption per ton of product and achieving the goal of energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings.

[0030] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 This is a graph showing the relationship between moisture content and baking time of the spherical material of the present invention;

[0032] Figure 3 It is the relationship diagram of outlet hot air temperature-baking time-outlet hot air moisture of the present invention;

[0033] Figure 4 The present invention discloses a control process of the automatic control system for moisture in the tunnel kiln for baking.

[0034] Legend: 1. Tunnel kiln; 2. Combustion furnace; 3. Regulating valve; 4. Hot air moisture detector; 5. Dust removal induced draft fan; 6. Dust removal supply fan; 7. Connecting pipe. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention can be implemented in various forms, so the present invention is not limited to the embodiments described below. In addition, in order to more clearly describe the present invention, components that are not connected with the invention will be omitted from the drawings.

[0036] The technical solution in the embodiment of the present application is to solve the problems of the above-mentioned background technology, and the overall idea is as follows:

[0037] Please refer to Figure 1 This embodiment introduces a method for controlling moisture in a tunnel kiln, including a tunnel kiln 1. The tunnel kiln 1 uses a heat-insulating material on one side close to the inside of the kiln to prevent heat from dissipating out of the kiln through the kiln wall during the baking process. The kiln wall, kiln roof, kiln car and other parts of the tunnel kiln 1 need to use refractory materials with good high temperature resistance and heat insulation performance. The selection of refractory materials should be determined according to factors such as the working temperature and atmosphere of the kiln. For example, for a tunnel kiln 1 for firing ceramics, the kiln wall can use high-aluminum bricks, whose refractoriness is generally between 1770-1790°C, which can withstand the ceramic firing process. In order to meet the high temperature, lightweight refractory bricks or refractory fiber materials can be used for the kiln roof, which can not only reduce the weight of the kiln roof, but also have a good heat insulation effect. Hot air moisture detectors 4 are installed at the inlet, middle section and outlet of the tunnel kiln 1. The hot air moisture detector 4 is mainly used to collect the moisture content of hot air at different positions of each kiln, calculate and judge the moisture changes of the baking materials in each kiln section, and then use the control system to accurately regulate it. Air volume components are provided at the inlet and outlet of the tunnel kiln 1, and the inlet of the tunnel kiln 1 is connected to a heating component.

[0038] The air volume component includes a connecting pipe 7, which is a hollow ventilation pipe that connects the air passages of multiple tunnel kilns 1 to facilitate the transfer of heat in the passages between the multiple passages, thereby ensuring that each tunnel kiln 1 can obtain heat. An air supply duct is provided at the entrance of the tunnel kiln 1, and a dust-removing blower 6 is provided at the left end of each air supply duct. When in use, the dust-removing blower 6 sends the heat to the tunnel of the tunnel kiln 1 under the action of air supply. An induced air duct is provided at the exit of the tunnel kiln 1, and a dust-removing induced draft fan 5 is provided at the right end of each induced air duct. The dust-removing induced draft fan 5 removes dust and draws air inside the kiln when starting baking. Under the action of the dust-removing induced draft fan 5 and the dust-removing blower 6, it is ensured that the heat in each tunnel kiln 1 can be transmitted from the entrance to the exit, and the materials encountered during the transmission process are dried and baked.

[0039] According to different tunnel widths and different tunnel lengths, appropriate air volumes are set. A lifting plate is provided in the material baking area inside any tunnel kiln 1. One end of the lifting plate is rotatably connected to the inner wall of the tunnel kiln 1, and the other end is fixedly connected to an electric telescopic rod. The other end of the electric telescopic rod is connected to the inner wall of the tunnel kiln 1, and the electric telescopic rod vertically points to the center of the tunnel kiln 1. The lifting plate can be controlled to rotate around one end by telescoping the electric telescopic rod, so that the air volume supplied by the air volume component can follow the guidance of the lifting plate and pass more from the surface of the material to be baked, thereby increasing the probability of contact between the baking hot air and the material to be baked, and improving the baking efficiency of the material to be baked.

[0040] In the early stage of baking the materials to be baked, the main purpose is to discharge free water, and the air volume is 500-1200 cubic meters / hour. This is because there is more moisture in the materials at this time. If the air volume is too large, the moisture on the surface of the materials will evaporate quickly, and the internal moisture will not have time to diffuse to the surface of the materials, which will easily cause the materials to be baked insufficiently. Moreover, the temperature is relatively low at this stage, and a large amount of air is not needed to maintain combustion or heat transfer. The lower air volume can make the moisture in the materials to be baked evaporate and dry gently.

[0041] When the baking enters the stage of removing adsorbed water, the air volume can be appropriately increased to 1200-3000 cubic meters per hour. During this period, as the temperature rises to about 200-400°C, the adsorbed water in the material to be baked begins to be removed. Appropriately increasing the air volume will help to remove the generated water vapor in time, and at the same time ensure that the heat in the kiln is evenly distributed, avoiding local overheating or water vapor accumulation.

[0042] When baking different materials, too small air volume will result in poor baking effect, and too long baking time; too large air volume will damage the surface of some types of materials, and too large air volume will also cause the temperature in the tunnel kiln 1 to drop, increase the working intensity of the combustion furnace 2, and increase the energy consumption per ton of product, which is not conducive to energy conservation and emission reduction.

[0043] The heating component includes a combustion furnace 2, which is heated by natural gas. A heat transfer pipeline is installed on the top of the combustion furnace 2. The heat transfer pipeline is connected to the combustion furnace 2 through a one-way valve. The one-way valve is provided with multiple branch valves. A regulating valve 3 is provided inside the branch valve. The regulating valve 3 is mainly used to adjust the amount of heat transmission to ensure that when different materials are baked in different tunnel kiln holes 1, different tunnel kiln holes 1 are heated and baked according to different materials, so that the materials in each tunnel kiln hole 1 can obtain a better baking effect.

[0044] The combustion furnace 2 supplies heat to the tunnel kiln 1, so that the internal temperature range of the tunnel kiln 1 is 100-400°C. When the heat supply to the tunnel kiln 1 is too high, in order to maintain the excessively high baking temperature, the amount of fuel consumed will be greatly increased. Moreover, the excessively high temperature will also aggravate the heat loss in the kiln, because the temperature difference between the inside of the kiln and the outside increases, and the heat lost through conduction, radiation, etc. of the kiln body increases, resulting in energy waste and increased production costs; if the temperature is too low, the baking and drying speed will be slowed down, and the baked material will take a longer time to reach the qualified baking standard.

[0045] A temperature sensor is provided at the exit of each tunnel kiln 1 .

[0046] A plurality of tunnel kilns 1 are assembled in parallel, and the adjacent cave walls serve as both the kiln walls of the first tunnel and the kiln walls of the second tunnel, which fully utilizes the cave walls while saving space and construction costs.

[0047] A plurality of tunnel kilns 1 built in parallel are connected by a connecting pipe 7, ensuring that the heat entering the tunnel kiln 1 can be distributed in a plurality of tunnels, so that each tunnel kiln 1 can obtain stable heat to bake the materials in each tunnel. In addition, when there are not enough materials to be baked for a plurality of tunnel kilns 1 to bake at the same time, the connecting valve of the connecting pipe 7 can be adjusted to close so that the heat only passes through the tunnel to be baked.

[0048] Each tunnel kiln 1 is provided with a material loading vehicle, which is mainly used to load and transport materials into the tunnel. The loading vehicle is provided with a number of air holes, and will not cause local heat accumulation and uneven heating under high temperature conditions.

[0049] Good sealing is one of the key requirements of tunnel kilns. All connecting parts of the kiln body, such as the kiln door, the gap between the kiln car and the kiln wall, must be sealed to prevent heat loss and the entry of cold air from the outside. Sealing rubber, ceramic fiber sealing pads and other materials are usually used to fill the gaps. At the kiln door, a double sealing structure can be set up, such as installing high-temperature resistant rubber sealing strips on the edge of the kiln door, and using a mechanical clamping device after the kiln door is closed to ensure the sealing effect.

[0050] refer to Figure 2 - Figure 4 In this embodiment, spherical materials are used for baking. After the spherical materials to be baked are transported to different locations of different tunnel caves by material loading vehicles, hot air moisture detectors are installed at the exit, middle section and entrance. An automatic control system is added to the entire tunnel kiln to accurately control the baking process. The specific process steps are as follows:

[0051] S1: The operator sets the baking air volume to 1800 cubic meters per hour and the baking temperature to 120°C according to the material to be baked;

[0052] S2: Control the heating system through the automatic control system to start heating;

[0053] S3: Hot air moisture detector monitors the hot air moisture at the inlet, middle and outlet in real time;

[0054] S4: The temperature sensor at the outlet detects the outlet hot air temperature and transmits it to the automatic control system;

[0055] S5: The automatic control system adjusts the output efficiency of the heating system, and the temperature sensor detects that the set temperature has been reached;

[0056] S6: The moisture content of the hot air at the outlet decreases, and the automatic control system shuts down the heating system;

[0057] S7: Use the residual heat to dry the remaining moisture in the material to be baked.

[0058] In this embodiment, the baking air volume is set to 1800 cubic meters per hour according to the spherical material to be baked. For the spherical material to be baked, the baking temperature of the natural gas combustion furnace in the heating component is set to 120°C. The moisture content of the spherical material during baking is measured and plotted. Figure 3 As can be seen from the figure, at a baking temperature of 120°C, the moisture content in the spherical material gradually decreases with the increase of baking time, until the baking time reaches 12 hours, the moisture content in the spherical material is less than 0.5%, indicating that the spherical material to be baked is baked at a baking temperature of 120°C for 12 hours.

[0059] Based on the existing baking process, an automatic control system was introduced. According to the hot air moisture detector 4 at different positions, the initial moisture content of the hot air entering the tunnel kiln was detected, the change of the hot air moisture during the baking process and the moisture content of the hot air after the baking were monitored, and the Figure 4 As can be seen from the figure, after 2 hours of drying, the heating effect of the heating system on the tunnel kiln reaches the maximum and maintains the baking temperature at 120°C. The moisture content in the outlet hot air reaches a peak and remains stable until the 8th hour, after which it begins to decline. This shows that the internal moisture content of the spherical material decreases after the 8th hour, and the moisture content in the exhaust air decreases. At this time, the moisture content in the spherical material is only 1.2%. After baking for the 10th hour, the moisture content in the spherical material is only 0.5%, and the moisture content in the outlet hot air is only 0.3%.

[0060] After 10 hours, when the moisture content of the outlet hot air reaches 0.3%, the automatic control system shuts down the combustion furnace 2 of the heating system and utilizes the waste heat in the tunnel kiln. After the air volume system participates in air supply and exhaust for 2 hours, the moisture content of the spherical material can reach about 0.3%. This operation can save 10% of natural gas.

[0061] Tunnel kiln 1 is equipped with an automatic control system, which uses the real-time data from the hot air moisture detector to adjust the temperature of the combustion furnace in the heating system, the air volume released by the air volume control system, and the baking time of the heating system in tunnel kiln 1, so as to achieve precise control, optimize and adjust the baking process and equipment parameters, reduce human operation errors, and reduce labor costs. At the same time, it can also significantly improve the production efficiency of the tunnel kiln, reduce the energy consumption per ton of product, and achieve the goal of energy conservation and emission reduction.

[0062] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A method for controlling moisture content in a tunnel kiln, characterized in that: An automatic control system is introduced, and the control system receives data from hot air moisture detectors (4) installed at different positions, and adjusts the amount of natural gas supplied to the combustion furnace (2) and the regulating valve to control the amount of heat and heat distribution; the control system adjusts the air volume of the air volume component, and the air volume of the dust removal blower (6) and the dust removal exhaust fan (5) are both set to 1800 cubic meters per hour during the baking stage. In addition, in the material baking area, the system controls the lifting plate in the tunnel kiln (1) to guide the wind direction to blow the material to be baked; the control system adjusts the heat of the heating component, and the hot air moisture detector (4) detects in real time that the moisture content of the hot air at the outlet is significantly reduced, and the automatic control system controls the combustion furnace (2) in the heating system to stop burning, and uses the residual heat to bake the moisture in the material. The steps of the automatic control system participating in the baking process of the material to be baked are as follows: S1: The operator sets the baking air volume to 1800 cubic meters per hour and the baking temperature to 120°C according to the material to be baked; S2: Control the heating system through the automatic control system to start heating; S3: Hot air moisture detector monitors the hot air moisture at the inlet, middle and outlet in real time; S4: The temperature sensor at the outlet detects the outlet hot air temperature and transmits it to the automatic control system; S5: The automatic control system adjusts the output efficiency of the heating system, and the temperature sensor detects that the set temperature has been reached; S6: The moisture content of the hot air at the outlet decreases, and the automatic control system shuts down the heating system; S7: Use the residual heat to dry the remaining moisture in the material to be baked.

2. A method for controlling moisture content in a tunnel kiln as claimed in claim 1, comprising a tunnel kiln (1), characterized in that: A hot air moisture detector (4) is installed at the inlet, middle section and outlet of each tunnel kiln (1), an air volume component is provided at the inlet and outlet of the tunnel kiln (1), and the inlet of the tunnel kiln (1) is connected to a heating component.

3. A method for controlling moisture content in a tunnel kiln as claimed in claim 1, characterized in that: An air volume component comprises a connecting pipe (7), wherein the plurality of tunnel kilns (1) are connected via the connecting pipe (7), wherein an air supply duct is provided at the entrance of each tunnel kiln (1), wherein a dust removal air supply fan (6) is provided at the left end of each air supply duct, and a dust removal induced draft fan (5) is provided at the right end of each induced draft duct, wherein the air volume of the dust removal air supply fan (6) and the dust removal induced draft fan (5) is set to 1800 cubic meters per hour.

4. A method for controlling moisture content in a tunnel kiln as claimed in claim 1, characterized in that: The heating component comprises a combustion furnace (2), a heat transfer pipe is installed at the top of the combustion furnace (2), the heat transfer pipe is connected to the combustion furnace (2) through a one-way valve, the one-way valve is provided with a multi-branch valve, and a regulating valve (3) is provided inside the branch valve. The temperature of the combustion furnace (2) is set to room temperature - 120°C in the preheating stage for about 2 hours, and the baking stage is set to 120°C.

5. A method for controlling moisture content in a tunnel kiln as claimed in claim 1, characterized in that: A temperature sensor is provided at the outlet of the tunnel kiln (1).

6. A method for controlling moisture content in a tunnel kiln as claimed in claim 1, characterized in that: A plurality of the tunnel kilns (1) are built in parallel.

7. A method for controlling moisture content in a tunnel kiln as claimed in claim 1, characterized in that: The tunnel kiln (1) is provided with a material loading vehicle inside, and the inner wall of the baking section of the tunnel kiln (1) is provided with a plurality of lifting plates for guiding the wind direction, and the lifting and lowering of the lifting plates forms an angle of 30° with the inner wall of the tunnel kiln (1).

8. A method for controlling moisture content in a tunnel kiln as claimed in claim 1, characterized in that: The kiln wall, kiln roof, kiln car and other parts of the tunnel kiln (1) need to use refractory materials with high temperature resistance and good heat insulation performance.

9. A method for controlling moisture content in a tunnel kiln as claimed in claim 1, characterized in that: The air volume of the dust removal blower (6) and the dust removal exhaust fan (5) is only 1200 cubic meters per hour in the preheating stage, and is set to 1800 cubic meters per hour in the baking stage.

10. A method for controlling moisture content in a tunnel kiln as claimed in claim 1, characterized in that: The automatic control system controls the amount of natural gas fuel supplied to the combustion furnace (2) based on data from the temperature sensor, and keeps the natural gas supply rate unchanged while maintaining a baking temperature of 120°C.

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