Grate kiln with stages of cooling utilizing hot air

Abstract

The application discloses a belt roaster with staged utilization of hot air in a staged cooling process, comprising: a blast drying section, an exhaust drying section, a preheating section, a roasting section, a soaking section, a first cooling section, a second cooling section and a third cooling section in sequence along the direction of material flow; wherein the hot air generated by the first cooling section, the second cooling section and the third cooling section has a temperature of not less than 1100 DEG C, 600-800 DEG C and not more than 300 DEG C respectively, and the hot air is delivered to the roasting section, the preheating section and the blast drying section through pipelines respectively. The application can fully recover high-temperature waste gas, the hot air with different temperatures is applied to suitable process sections, the energy utilization rate is improved, and low-calorific-value fuel can be used while reducing process energy consumption by combining gas preheating or oxygen-enriched primary air / full-oxygen combustion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pellet production. More particularly, the present application relates to a belt-type indurating machine. BACKGROUND

[0002] In the production process of the belt-type indurating machine, the cooling system is divided into a first cooling stage and a second cooling stage, and the cooling medium is ambient air, and a cooling fan is used to provide cooling air. The temperature of the finished pellets before entering the first cooling stage is about 1100-1200℃, and after passing through the first cooling stage and the second cooling stage, the temperature of the finished pellets is about 120℃. The cold air heated by the finished pellets is collected into the first cooling stage upper cover heat recovery air pipe and the second cooling stage upper cover heat recovery air pipe. The temperature of the hot air in the first cooling stage upper cover heat recovery air pipe is about 900-1000℃, and the hot air is sent to the burners of the induration stage and the preheating stage through a main heat recovery air pipe and branch pipes. The temperature of the hot air in the second cooling stage upper cover heat recovery air pipe is about 300℃, and the hot air is directly sent to the pellet drying stage through a main drying air pipe. Since the required temperature for induration is as high as 1300℃, and the temperature of the heat recovery air from the first cooling stage is only 900-1000℃, and the amount of hot air often exceeds the process requirement, it is necessary to set burners in the induration stage to supplement heat, which wastes a large amount of heat and limits the use of low-calorific-value combustion. In addition, since the required temperature for the preheating stage is about 550-900℃, and the temperature of the heat recovery air from the first cooling stage is 900-1000℃, it is necessary to mix low-temperature flue gas before the preheating stage to reduce the temperature, which wastes a large amount of heat. Therefore, it is necessary to design a technical solution that can overcome the above-mentioned defects to some extent. SUMMARY

[0003] An object of the present application is to provide a belt-type indurating machine with staged cooling stages utilizing hot air, which can fully recover high-temperature waste gas and improve energy utilization rate.

[0004] In order to achieve these objects and other advantages of the present application, according to one aspect of the present application, a belt-type indurating machine with staged cooling stages utilizing hot air is provided, which includes, in sequence along the direction of material flow, a pellet drying stage, a pellet drying stage, a preheating stage, an induration stage, a soaking stage, a first cooling stage, a second cooling stage, and a third cooling stage. The hot air generated by the first cooling stage, the second cooling stage, and the third cooling stage has a temperature of not less than 1100℃, 600-800℃, and not more than 300℃, respectively, and is delivered to the induration stage, the preheating stage, and the pellet drying stage through pipes.

[0005] Further, a first cooling stage upper cover heat recovery air pipe is arranged above the first cooling stage to collect the hot air generated by the first cooling stage, and a plurality of branch pipes are connected to the first cooling stage upper cover heat recovery air pipe to deliver the hot air to a plurality of burners in the induration stage.

[0006] Further, a cooling two-section upper cover heat recovery air pipe is arranged above the cooling two-section, for collecting the hot air generated by the cooling two-section, and a plurality of branch pipes are connected to the cooling two-section upper cover heat recovery air pipe, for respectively conveying the hot air to the plurality of burners on the preheating section.

[0007] Further, a cooling three-section upper cover heat recovery air pipe is arranged above the cooling three-section, for collecting the hot air generated by the cooling three-section, and conveying the hot air to the blast drying section.

[0008] Further, the burners are conventional air burners, oxygen-enriched burners or full-oxygen burners, the combustion chambers of the plurality of burners are in communication with the branch pipes, and the hot air generated by the cooling two-section or the hot air generated by the cooling three-section is used as the secondary air of the burners, when the burners are conventional air burners or oxygen-enriched burners, the primary air of the burners is provided by the combustion air fan.

[0009] Further, at least two cooling fans are further included, one of the cooling fans is used to supply air to the cooling one-section, and the other cooling fan is used to supply air to the cooling two-section and the cooling three-section.

[0010] Further, a heat exchanger is further included, which has a first medium channel and a second medium channel, the first medium channel is connected to the cooling one-section upper cover heat recovery air pipe, and the second medium channel is connected to the gas conveying pipe conveying gas to the burners of the preheating section and the calcination section.

[0011] Further, the cooling fan is a variable frequency fan.

[0012] Further, a controller is further included, which is electrically connected to the variable frequency fan, the temperature sensor, the air volume sensor and the electric valve, the temperature sensor is a plurality of and is distributed at intervals in the cooling one-section upper cover heat recovery air pipe, the air volume sensor is arranged in the cooling one-section upper cover heat recovery air pipe and is located downstream of the position connected to the heat exchanger, the electric valve is arranged in the cooling one-section upper cover heat recovery air pipe and is located downstream of the position connected to the heat exchanger, the controller is used to input the plurality of collected temperature values and air volume values into a neural network model, output the opening degree of the electric valve and the frequency of the variable frequency fan, and the neural network model is obtained according to historical data training.

[0013] The present application at least includes the following beneficial effects:

[0014] The present invention includes a first cooling section, a second cooling section, and a third cooling section. The hot air generated by the first cooling section, the second cooling section, and the third cooling section has a temperature of not less than 1100℃, 600-800℃, and not more than 300℃, respectively. The generated hot air is transported to the calcination section, the preheating section, and the blower drying section through pipelines. By classifying the cooling section and providing hot air of different temperatures to the calcination section, the preheating section, and the blower drying section, the heat is utilized in a tiered manner, thereby improving the energy utilization rate.

[0015] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0016] Fig. 1 This is a schematic diagram of the structure of one embodiment of this application;

[0017] Fig. 2 This is a schematic diagram of the calcination section according to one embodiment of this application;

[0018] Fig. 3 This is a schematic diagram of the structure of a cooling section of the upper heat return air duct according to one embodiment of this application. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0020] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0021] like Figs. 1-3 As shown, embodiments of this application provide a belt calciner with staged cooling and hot air utilization, which includes, in sequence along the material flow direction, a forced-air drying section 12, a forced-air drying section 15, a preheating section 10, a calcination section 7, a homogenization section 16, a first cooling section 1, a second cooling section 2, and a third cooling section 3; wherein, the hot air temperatures generated by the first cooling section 1, the second cooling section 2, and the third cooling section 3 are not less than 1100℃, 600~800℃, and not greater than 300℃, respectively, and the generated hot air is respectively transported to the calcination section 7, the preheating section 10, and the forced-air drying section 12 through pipelines;

[0022] In the above embodiment, the blast drying section 12, the preheating section 10 and the calcining section 7 can directly use the prior art, and an induced drying section 15 can be arranged after the blast drying section 12, and a soaking section 16 can be arranged after the calcining section 7, and the soaking section 16 after the soaking section 16 is divided into the cooling section 1, the cooling section 2 and the cooling section 3, and the temperature of the finished pellets before entering the cooling section 1 is about 1100-1200℃, the finished pellets are cooled by supplying air to the cooling section 1, the cooling section 2 and the cooling section 3 by arranging the cooling fans (4, 5), and the heat recovery air is generated; by adjusting the parameters of the cooling fans (4, 5), the hot air generated by the cooling section 1, the cooling section 2 and the cooling section 3 has a temperature of not less than 1100℃, 600-800℃ and not more than 300℃ respectively, the hot air with a temperature of not less than 1100℃ is transported to the calcining section 7 to supplement heat and combustion-supporting, which reduces the fuel consumption of the calcining section 7 and meets the temperature requirement of the calcining section 7, so that low-calorific-value fuel can be used; the hot air with a temperature of 600-800℃ and not more than 300℃ is transported to the preheating section 1- and the blast drying section 12, which can meet the requirements of preheating and drying the pellets; it can be seen that the cooling section is divided into three sections in the embodiment, and the hot air is supplied to the calcining section 7, the preheating section 10 and the blast drying section 12, which realizes the gradient utilization of heat and facilitates the adjustment of the air volume and temperature of the hot air and improves the energy utilization rate.

[0023] In another embodiment, a cooling section 1 upper cover heat recovery air pipe is arranged above the cooling section 1 to collect the hot air generated by the cooling section 1, a plurality of branch pipes 706 are connected to the cooling section 1 upper cover heat recovery air pipe 6 to transport the hot air to a plurality of burners 8 on the calcining section; a cooling section 2 upper cover heat recovery air pipe 9 is arranged above the cooling section 2 to collect the hot air generated by the cooling section 2, a plurality of branch pipes 706 are connected to the cooling section 2 upper cover heat recovery air pipe to transport the hot air to a plurality of burners 8 on the preheating section; a cooling section 3 upper cover heat recovery air pipe 11 is arranged above the cooling section 3 to collect the hot air generated by the cooling section 3 and transport the hot air to the blast drying section; the hot air with a temperature of not less than 1100℃ and 600-800℃ is directly supplied to the burners 8 of the calcining section and the burners 8 of the preheating section by the branch pipes to improve the utilization rate of the hot air, and the hot air with a temperature of not more than 300℃ is directly transported to the blast drying section to dry the pellets.

[0024] In another embodiment, the burner 8 adopts a conventional air burner, an oxygen-enriched burner or a full-oxygen burner, the combustion chambers of a plurality of the burners 8 are communicated with the branch pipes, and the hot air generated by the cooling second section 2 or the hot air generated by the cooling third section 3 is used as the secondary air of the burners 8; when the burners 8 adopt the conventional air burner or the oxygen-enriched burner, the primary air of the burners 8 is provided by the combustion air fan; specifically, the primary air 703 of the burner can be provided by the combustion air fan 701 and mixed with oxygen 709; or the combustion air fan 701 is cancelled and oxygen-enriched or full-oxygen is adopted to provide the primary air with an oxygen content of 25-100%; the gas supply system 702 can adopt natural gas, coke oven gas, mixed gas, converter gas, etc., thereby expanding the types of gas used, the burners 8 adopt the oxygen-enriched / full-oxygen burner to adapt to the oxygen-enriched / full-oxygen combustion condition, and the secondary air is the system backheating air 705 which is branched from the backheating air main pipe and connected with the combustion chambers 708 respectively; the combustion system provides sufficient heat source for the roaster cover, and then the hot gas flow is made to pass through the material layer by the fan suction to heat the material; the primary air adopts the oxygen-enriched / full-oxygen combustion, and the primary air can provide the oxygen demand of combustion, thereby achieving the three purposes of energy saving, using low-calorific-value fuel and reducing nitrogen oxides.

[0025] In another embodiment, the system further comprises at least two cooling fans (4, 5), one of which is used to supply air to the cooling first section 1 and the other of which is used to supply air to the cooling second section 2 and the cooling third section 3; specifically, two cooling fans (4, 5) are adopted.

[0026] In another embodiment, the system further comprises a heat exchanger 14 having a first medium passage and a second medium passage, the first medium passage is connected with the backheating air pipe of the cooling first section upper cover through the pipe 13, and the second medium passage is connected in the gas supply pipe which supplies gas to the burners 8 of the preheating section and the roasting section; that is, part of the high-temperature air in the cooling first section upper cover backheating air is extracted to preheat the gas, thereby increasing the gas heat content and reducing the amount of backheating air entering the roasting section.

[0027] In another embodiment, the cooling fans (4, 5) are variable-frequency fans, so that the frequency and the air volume can be adjusted in real time according to the demand.

[0028] In another embodiment, further comprising: a controller electrically connected with the variable frequency fan, the temperature sensors 601, the air volume sensor 603 and the electric valve 602, the temperature sensors 601 are multiple and are distributed at intervals in the cooling first section upper cover heat recovery air duct, the air volume sensor 603 is arranged in the cooling first section upper cover heat recovery air duct and is located downstream of the position connected with the heat exchanger 14, the electric valve 602 is arranged in the cooling first section upper cover heat recovery air duct 6 and is located downstream of the position connected with the heat exchanger 14, the controller is used for inputting the collected multiple temperature values and air volume values into a neural network model, outputting the opening of the electric valve 602 and the frequency of the variable frequency fan, and the neural network model is obtained according to historical data training; in the above embodiment, the temperature sensors 601 are arranged at intervals along the cooling first section upper cover heat recovery air duct 6 to detect the temperature values of each position point, the air volume sensor 603 is used to detect the air volume value of the cooling first section upper cover heat recovery air duct 6 entering the roasting section, the collected temperature values and air volume values are input into the neural network model to obtain the predicted electric valve 602 opening and variable frequency fan frequency, so that the electric valve 602 adjusts the opening, the variable frequency fan adjusts the frequency, and through the opening of the electric valve 602 and the frequency adjustment of the fan, the air volume entering the roasting section 7 is adjusted, and the remaining air volume enters the heat exchanger to preheat the fuel gas, which affects the fuel gas temperature entering the roasting machine, through the neural network model, the hot air temperature entering the roasting section 7, the air volume, and the air volume preheating the fuel gas are balanced, and the process requirements of the roasting are better adapted; the neural network model is trained according to the data collected during the actual operation of the roasting machine when the roasting process is good, training data with temperature values and air volume values as input and fan frequency and electric valve 602 opening as corresponding relationship are established, and the neural network model is obtained by training.

[0029] The number of devices and the scale of processing described herein are used to simplify the description of the present application. It is obvious to those skilled in the art that the belt roaster and the method of the present application can be applied, modified and changed.

[0030] Although the embodiments of the present application have been disclosed as above, they are not limited to the application and the embodiments listed in the specification, and can be fully applied to various fields suitable for the present application, and additional modifications can be easily realized by those skilled in the art, and therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A belt-type indurating machine utilizing hot air in stages of cooling, characterized in that, The blast drying section, the suction drying section, the preheating section, the calcining section, the soaking section, the first cooling section, the second cooling section and the third cooling section are sequentially arranged along the movement direction of the material flow. The hot air generated by the first cooling section, the second cooling section and the third cooling section has a temperature of not less than 1100℃, 600-800℃ and not more than 300℃ respectively, and is respectively delivered to the calcining section, the preheating section and the blast drying section through pipelines. A first cooling section upper cover return air pipe is arranged above the first cooling section and is used for collecting the hot air generated by the first cooling section, a plurality of branch pipes are connected to the first cooling section upper cover return air pipe and are used for delivering the hot air to a plurality of burners on the calcining section. A second cooling section upper cover return air pipe is arranged above the second cooling section and is used for collecting the hot air generated by the second cooling section, a plurality of branch pipes are connected to the second cooling section upper cover return air pipe and are used for delivering the hot air to a plurality of burners on the preheating section. At least two cooling fans are further included, one of the cooling fans is used for supplying air to the first cooling section, and the other cooling fan is used for supplying air to the second cooling section and the third cooling section, and the cooling fan is a variable frequency fan. The heat exchanger has a first medium channel and a second medium channel, the first medium channel is connected to the first cooling section upper cover return air pipe, and the second medium channel is connected to a gas delivery pipeline for delivering gas to the burners of the preheating section and the calcining section. The controller is electrically connected with the variable frequency fan, the temperature sensor, the air volume sensor and the electric valve, the temperature sensor is a plurality of and is spacedly arranged in the first cooling section upper cover return air pipe, the air volume sensor is arranged in the first cooling section upper cover return air pipe and is located downstream of the position connected with the heat exchanger, the electric valve is arranged in the first cooling section upper cover return air pipe and is located downstream of the position connected with the heat exchanger, the controller is used for inputting the collected temperature values and air volume values into a neural network model, outputting the opening degree of the electric valve and the frequency of the variable frequency fan, and the neural network model is obtained according to historical data training. A third cooling section upper cover return air pipe is arranged above the third cooling section and is used for collecting the hot air generated by the third cooling section and delivering the hot air to the blast drying section. The burners are conventional air burners, oxygen-enriched burners or full-oxygen burners, the combustion chambers of a plurality of the burners are communicated with the branch pipes, the hot air generated by the second cooling section or the hot air generated by the third cooling section is used as the secondary air of the burners, and when the burners are conventional air burners or oxygen-enriched burners, the primary air of the burners is provided by a combustion air fan.

2. The grate cooler according to claim 1, characterized in that, ​ 3. The grate cooler according to claim 1, wherein the hot air is supplied to the cooling steps. ​

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