Chain grate machine preheating one-stage ladder air supply system and air supply method

Abstract

The present invention relates to a chain grate preheating stage step air supply system and air supply method, comprising a chain grate, which is divided into a drying stage, a draining stage, a preheating stage and a second preheating stage in sequence along the material flow direction, and is characterized in that: it also includes a second cooling stage exhaust gas pipeline, a combustion chamber and a regulating valve, the second cooling stage exhaust gas main pipe is connected to the chain grate preheating stage upper cover through an exhaust gas branch pipe, a regulating valve is arranged on the exhaust gas branch pipe I, a combustion chamber I is arranged on the exhaust gas branch pipe II, a combustion chamber II is arranged on the exhaust gas branch pipe III, and a combustion chamber III is arranged on the exhaust gas branch pipe IV, and a temperature detection device I, a temperature detection device II, a temperature detection device III and a temperature detection device IV are arranged on the side of the chain grate preheating stage upper cover. According to actual production needs, the air flow temperature change gradient in the process of pellet heating can be controlled, and a suitable temperature field is established in the preheating stage upper cover, which can prevent the green balls from bursting and adapt to the changes in raw material conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of pellet production in the iron and steel metallurgical industry, and specifically relates to a chain grate preheating machine.

[0002] The invention relates to a step-by-step air supply system and an air supply method. Background Art

[0003] At present, the chain grate machine-rotary kiln-ring cooler process is one of the main production processes for iron ore pellet production.

[0004] The green pellets are heat treated on the chain grate machine, and the drying and preheating process of the green pellets is completed by cross-flow heat exchange between the hot air flow and the material layer. According to the traditional hot air process, the chain grate machine is divided into four sections according to the hot air flow temperature and the way it passes through the material layer. Along the material forward direction, they are the blast drying section, the exhaust drying section, the preheating section 1 and the preheating section 2. The hot air flow temperature required for each section of the chain grate machine is determined according to the pelletizing test results.

[0005] Blast drying is the first process of processing green balls on the chain grate machine. The heat source for blast drying is the cooling exhaust gas from the upper cover of the third cooling section of the ring cooler (hereinafter referred to as "third cooling section exhaust gas"). The hot air flows from bottom to top through the green ball material layer to initially remove the moisture from the green balls. In order to meet the emission standards, the wet exhaust gas passing through the material layer needs to be dedusted by the furnace cover dust collector before being discharged.

[0006] Exhaust drying is the second process of processing green balls on the chain grate machine. The heat source for exhaust drying is the hot flue gas from the heat recovery blower of the chain grate machine (hereinafter referred to as "heat recovery air", the temperature is generally 350~450℃). The hot air flows from top to bottom through the green ball material layer to remove moisture from the green balls.

[0007] The preheating section is the transition link on the chain grate machine. The heat source of the preheating section is the hot exhaust gas from the upper cover of the second cooling section of the ring cooler (hereinafter referred to as "second cooling section exhaust gas", the temperature is generally 600~800℃). The traditional practice is that the exhaust gas from the second cooling section enters the cover from the top of the upper cover of the preheating section, and the hot air flows from top to bottom through the green ball material layer to remove all the remaining moisture in the green balls, and heat the dry balls to make them heat up as needed.

[0008] The flue gas from the exhaust drying section and the preheating bellows is collected and treated by the main electrostatic precipitator, main exhaust fan, desulfurization and denitrification device before being discharged.

[0009] The second preheating stage is the last link in the processing of raw balls on the chain grate machine. The hot flue gas from the rotary kiln passes through the material layer from top to bottom, preheating the dry balls at an appropriate temperature for a certain period of time so that the dry ball strength meets the requirements for entering the kiln. The flue gas that passes through the material layer is used as "reheated air" and is sent by the heat recovery fan to the upper cover of the exhaust drying section as a heat source.

[0010] After the drying and preheating process, the green balls complete the dehydration and heating process. The pellets with a certain strength enter the rotary kiln and complete the roasting process of the pellets in the kiln. The high-temperature pellets after roasting are unloaded from the rotary kiln into the ring cooler, and the cooling process of the pellets is completed on the ring cooler.

[0011] In the production process using the above traditional air flow, the temperature of the exhaust gas in the second cooling section, which is used as the heat source for the preheating stage, is usually low. In order to meet the production needs, an auxiliary heating device is usually set up to supplement the heat. The commonly used heating methods have the following problems:

[0012] 1) One method is to set an auxiliary heating device on the side wall of the upper cover of the chain grate preheating section. The disadvantage is that in the limited upper cover space, the hot flue gas provided by the auxiliary heating device cannot be fully mixed with the secondary cooling section exhaust gas entering the upper cover from the top, making it difficult to achieve uniform heating of the material layer;

[0013] 2) Another method is to install an auxiliary heating device on the hot exhaust gas pipeline leading to the upper cover of the preheating section of the chain grate machine to heat the gas in the pipeline as a whole. This method can make the temperature of the hot exhaust gas entering the upper cover of the preheating section uniform, overcoming the problem of uneven heating of the material layer. However, it also has the problem that the temperature field in the upper cover of the preheating section cannot be adjusted as needed, and the temperature of the pellets cannot be avoided from rising sharply after entering the preheating section. Green balls with poor drying effect will crack or even burst when suddenly exposed to high temperature, affecting production and pellet quality.

[0014] In addition, when different raw materials are used, the appropriate thermal system for the drying and preheating process of the pellets may vary greatly. In order to make the pellets evenly heated during the heating process and the heating process can correspond to different thermal systems, the hot air supply method of the preheating section of the chain grate machine should be optimized to make the heating process of the pellets in the preheating section controllable, prevent the cracking of the raw balls, ensure the drying and preheating effect of the pellets on the chain grate machine, and improve the adaptability of the chain grate machine to raw materials. Summary of the invention

[0015] The purpose of the present invention is to provide a chain grate preheating stage stepped air supply system and air supply method, which are used to control the air flow temperature entering the upper cover of the chain grate preheating stage, improve the adaptability of the chain grate to raw materials, and create conditions for energy conservation, emission reduction and efficient operation of the chain grate-rotary kiln pellet production system.

[0016] The objective of the present invention is achieved through the following technical solutions:

[0017] The chain grate machine preheating stage stepped air supply system of the present invention comprises a chain grate machine, which is divided into a drying section, a draining section, a preheating stage one and a preheating stage two in sequence along the material flow direction, and is characterized in that it also comprises a second cooling stage exhaust gas main pipe, a combustion chamber and a regulating valve connected to the second cooling stage upper cover of the ring cooler; the second cooling stage exhaust gas main pipe is connected to the top of the chain grate machine preheating stage upper cover through a plurality of exhaust gas branch pipes, a regulating valve is arranged on the exhaust gas branch pipe I, a combustion chamber I is arranged on the exhaust gas branch pipe II, a combustion chamber II is arranged on the exhaust gas branch pipe III, and a combustion chamber III is arranged on the exhaust gas branch pipe IV; and temperature detection devices I, temperature detection devices II, temperature detection devices III and temperature detection devices IV are arranged on the side of the chain grate machine preheating stage upper cover.

[0018] Furthermore, the temperature detection device I corresponds to the exhaust gas branch pipe I, the temperature detection device II corresponds to the exhaust gas branch pipe II, the temperature detection device III corresponds to the exhaust gas branch pipe III, and the temperature detection device IV corresponds to the exhaust gas branch pipe IV.

[0019] Furthermore, the chain grate machine preheating step air supply system also includes a control system, which is connected to temperature detection device I, temperature detection device II, temperature detection device III and temperature detection device IV, and controls the regulating valve and combustion chamber I, combustion chamber II and combustion chamber III.

[0020] The present invention provides an air supply method for preheating a step air supply system using the above-mentioned chain grate machine, comprising the following steps:

[0021] S1. Set the temperature value of the upper cover of the chain grate preheating section. When the value of the temperature detection device I is lower than or higher than the set value, the control system automatically controls the opening of the regulating valve to make the temperature of the area corresponding to the exhaust branch pipe I in the upper cover of the chain grate preheating section reach the set value;

[0022] S2. When the temperature of temperature detection device II, temperature detection device III and temperature detection device IV is lower than or higher than the set value, the control system automatically controls the heating intensity of the combustion chamber on the corresponding branch pipe, so that the temperature in the upper cover of the chain grate preheating section and the corresponding area of ​​the exhaust branch pipe II, exhaust branch pipe III and exhaust branch pipe IV reaches the set value.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] 1) By adjusting the heating intensity of the auxiliary heating device, the airflow entering the upper cover of the chain grate preheating section can reach the required temperature, and the pellets in the width direction of the chain grate can be heated evenly;

[0025] 2) The heating intensity of each combustion chamber can be adjusted separately, which can control the air flow temperature in the hot air branch pipe corresponding to different combustion chambers. According to production needs, the air flow temperature gradient during the pellet heating process can be controlled, and a suitable temperature field can be established in the upper cover of the preheating stage, which can prevent the green balls from bursting and adapt to changes in raw material conditions;

[0026] 3) The chain grate preheating stage air supply system of the present invention has a simple structure, occupies a small space, is easier to operate, and can be modified using the original system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a schematic diagram of a chain grate machine preheating step air supply system. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] like Figure 1 As shown, a chain grate preheating stage step air supply system of the present invention comprises a chain grate 1, which is divided into a drying section, a draining section, a preheating stage 1 and a preheating stage 2 in sequence along the material flow direction, and is characterized in that it also comprises a secondary cooling stage exhaust gas main channel 2 connected to the secondary cooling stage upper cover of the ring cooler, a combustion chamber and a regulating valve 4, the secondary cooling stage exhaust gas main channel 2 is connected to the top of the chain grate 1 preheating stage upper cover through a plurality of exhaust gas branch pipes, and the plurality of exhaust gas branch pipes are exhaust gas branch pipes Ⅰ2-1, exhaust gas branch pipe Ⅱ2-2, exhaust gas branch pipe Ⅱ2-3, exhaust gas branch pipe Ⅱ2-4, exhaust gas branch pipe Ⅱ2-5, exhaust gas branch pipe Ⅱ2-6, exhaust gas branch pipe Ⅱ2-7, exhaust gas branch pipe Ⅱ2-8, exhaust gas branch pipe Ⅱ2-9, exhaust gas branch pipe Ⅱ2-10, exhaust gas branch pipe Ⅱ2-11, exhaust gas branch pipe Ⅱ2-12, exhaust gas branch pipe Ⅱ2-13, exhaust gas branch pipe Ⅱ2-14, exhaust gas branch pipe Ⅱ2-15, exhaust gas branch pipe Ⅱ2-16, exhaust gas branch pipe Ⅱ2-17, exhaust gas branch pipe Ⅱ2-18, exhaust gas branch pipe Ⅱ2-19, exhaust gas branch pipe Ⅱ2-21 -2, it is composed of an exhaust gas branch pipe III2-3 and an exhaust gas branch pipe IV2-4, a regulating valve 4 is arranged on the exhaust gas branch pipe I2-1, a combustion chamber I3-1 is arranged on the exhaust gas branch pipe II2-2, a combustion chamber II3-2 is arranged on the exhaust gas branch pipe III2-3, a combustion chamber III3-3 is arranged on the exhaust gas branch pipe IV2-4, and a temperature detection device I5-1, a temperature detection device II5-2, a temperature detection device III5-3 and a temperature detection device IV5-4 are arranged on the side of the upper cover of the preheating section of the chain grate machine 1.

[0030] The temperature detection device Ⅰ5-1 described in the present invention corresponds to the exhaust gas branch pipe Ⅰ2-1, the temperature detection device Ⅱ5-2 corresponds to the exhaust gas branch pipe Ⅱ2-2, the temperature detection device Ⅲ5-3 corresponds to the exhaust gas branch pipe Ⅲ2-3, and the temperature detection device Ⅳ5-4 corresponds to the exhaust gas branch pipe Ⅳ2-4.

[0031] The chain grate machine preheating step air supply system of the present invention also includes a control system, which is connected with temperature detection device Ⅰ5-1, temperature detection device Ⅱ5-2, temperature detection device Ⅲ5-3, temperature detection device Ⅳ5-4, and controls regulating valve 4 and combustion chamber Ⅰ3-1, combustion chamber Ⅱ3-2 and combustion chamber Ⅲ3-3.

[0032] The chain grate machine of the present invention is used to preheat a step air supply system, and the air supply method thereof comprises the following steps:

[0033] S1. Set the temperature value of the upper cover of the chain grate preheating section. When the value of the temperature detection device Ⅰ5-1 is lower than the set value, the control system automatically controls the opening of the regulating valve 4 to be closed. When it is higher than the set value, the control system automatically controls the opening of the regulating valve 4 to be opened, so that the temperature of the area corresponding to the exhaust gas branch pipe Ⅰ2-1 in the upper cover of the chain grate preheating section reaches the set value.

[0034] S2. When the temperature detection device Ⅱ5-2, the temperature detection device Ⅲ5-3 and the temperature detection device Ⅳ5-4 are lower than the set value, the control system automatically controls to increase the heating intensity of the combustion chamber on the corresponding branch pipe, so that the temperature of the upper cover of the chain grate machine preheating section and the area corresponding to the exhaust gas branch pipe Ⅱ2-2, the exhaust gas branch pipe Ⅲ2-3 and the exhaust gas branch pipe Ⅳ2-4 reaches the set value; when the temperature detection device Ⅱ5-2, the temperature detection device Ⅲ5-3 and the temperature detection device Ⅳ5-4 are higher than the set value, the control system automatically controls to reduce the heating intensity of the combustion chamber on the corresponding branch pipe, so that the temperature of the upper cover of the chain grate machine preheating section and the area corresponding to the exhaust gas branch pipe Ⅱ2-2, the exhaust gas branch pipe Ⅲ2-3 and the exhaust gas branch pipe Ⅳ2-4 reaches the set value.

[0035] By adopting the chain grate machine preheating stage air supply system of the present invention, the heating intensity of each combustion chamber can be adjusted individually, and the air flow temperature in the hot air branch pipe corresponding to the different combustion chambers can be controlled. According to actual production needs, the air flow temperature change gradient during the pellet heating process can be controlled, and a suitable temperature field can be established in the upper cover of the preheating stage, which can prevent the green pellets from bursting and adapt to changes in raw material conditions.

[0036] The invention has a simple structure, occupies a small space, and is easier to operate. It can be used for newly-built production lines, and can also be used to transform existing systems.

Claims

1. A chain grate preheating stage step air supply system, comprising a chain grate, wherein the chain grate is sequentially divided into a drying section, a drying section, a preheating stage 1 and a preheating stage 2 along the material flow direction. Features: Also includes a second cooling section exhaust pipe main channel connected to the ring cooler second cooling section upper cover, a combustion chamber and a regulating valve second cooling section exhaust main pipe connected to the top of the chain grate preheating section upper cover through a plurality of exhaust branch pipes, a regulating valve is provided on the exhaust branch pipe Ⅰ, a combustion chamber Ⅰ is provided on the exhaust branch pipe Ⅱ, a combustion chamber Ⅱ is provided on the exhaust branch pipe Ⅲ, a combustion chamber Ⅲ is provided on the exhaust branch pipe Ⅳ, and a temperature detection device Ⅰ, a temperature detection device Ⅱ, a temperature detection device Ⅲ and a temperature detection device Ⅳ are provided on the side of the chain grate preheating section upper cover; The temperature detection device I corresponds to the exhaust gas branch pipe I, the temperature detection device II corresponds to the exhaust gas branch pipe II, the temperature detection device III corresponds to the exhaust gas branch pipe III, and the temperature detection device IV corresponds to the exhaust gas branch pipe IV; The chain grate machine preheating step air supply system also includes a control system, which is connected to temperature detection device I, temperature detection device II, temperature detection device III and temperature detection device IV, and controls the regulating valve and combustion chamber I, combustion chamber II and combustion chamber III.

2. A chain grate machine preheating one step of air supply method, using the chain grate machine preheating one step of air supply system according to claim 1, It is characterized in that The steps include: S1. Set the temperature value of the upper cover of the chain grate preheating section. When the value of the temperature detection device I is lower than or higher than the set value, the control system automatically controls the opening of the regulating valve to make the temperature of the area corresponding to the exhaust branch pipe I in the upper cover of the chain grate preheating section reach the set value; S2. When the temperature of temperature detection device II, temperature detection device III and temperature detection device IV is lower than or higher than the set value, the control system automatically controls the heating intensity of the combustion chamber on the corresponding branch pipe, so that the temperature in the upper cover of the chain grate preheating section and the corresponding area of ​​the exhaust branch pipe II, exhaust branch pipe III and exhaust branch pipe IV reaches the set value.

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