Pulverized coal multi-section grading injection belt type roasting system

Abstract

The utility model discloses a belt type roasting system for multi-section graded injection of pulverized coal. The system comprises a belt type roasting machine, a pulverized coal injection pipeline, a hot air circulating pipeline, a gas coal conveying reciprocating folding pipe and an ignition device. A pipeline for conveying secondary hot air to a roasting section is designed to be of a multi-section back-and-forth folded pipe type structure, a plurality of pulverized coal injection pipelines and independent ignition devices matched with the pulverized coal injection pipelines are connected to the pipeline, and the aim that cheap pulverized coal serves as heat supply fuel for roasting is achieved in a multi-section pulverized coal injection combustion mode. The method has the advantage of low production cost. Besides, the system does not need to change a main body of an existing belt type roasting machine, enlarges the application range of an existing belt type roasting device while not additionally increasing occupied space, provides a new development direction for a belt type roasting process in steel pellet production, and is suitable for popularization and application. And the method has remarkable social and economic benefits and excellent prospects of large-scale popularization, implementation and application.

Description

Technical Field

[0001] The utility model relates to steel metallurgy production equipment, in particular to a belt roasting system with multi-stage classification and injection of pulverized coal, belonging to the technical field of steel metallurgy production. Background Art

[0002] Oxidized pellets are an important type of burden for blast furnace smelting. Currently, the processes for producing oxidized pellets on the market mainly include three categories: the grate-kiln process, the traveling grate-roaster process, and the shaft furnace pelletizing process. Among them, the shaft furnace pelletizing process has been gradually phased out, with a market share of less than 5%; while the traveling grate-roaster process has become the mainstream of the future pellet market due to its advantages such as small floor area, good equipment integrity, and advanced energy consumption and emission indicators.

[0003] In the current trend of the steel market, vigorously developing low-cost pelletizing processes is the key to the future upgrading and transformation of the steel industry. Currently, as the mainstream pellet process, the traveling grate-roaster is restricted by equipment technology and can only use high-calorific-value gas (natural gas or coke oven gas) as fuel, resulting in the following problems: 1) High process cost: Since the traveling grate-roaster process currently must use high-calorific-value gas, and the price of this part of high-calorific-value gas is very high, the process cost of producing pellets by the traveling grate-roaster remains high; 2) Limited process suitability: It is uneconomical and unrealistic for many steel enterprises to specially introduce a high-cost gas pipeline to build a traveling grate-roaster pellet production line, which leads to the inability to select the traveling grate-roaster process. Summary of the Utility Model

[0004] Aiming at the problems of high production cost and limited application existing in the existing traveling grate-roasting process using high-calorific-value gas as fuel in the prior art, the utility model provides a belt roasting system with multi-stage classification and injection of pulverized coal. The system designs the pipeline for conveying secondary hot air to the roasting section as a multi-stage reciprocating and folding pipe structure, and is connected with a plurality of pulverized coal injection pipelines and independent ignition devices supporting the pulverized coal injection pipelines on the pipeline. The purpose of using cheap pulverized coal as the heating fuel for roasting is achieved through the multi-stage pulverized coal injection and combustion method, which has the advantage of low production cost. The system of the utility model does not need to modify the main body of the existing traveling grate-roaster, expands the application range of the existing traveling grate-roasting device without additional increase in site occupation, provides a new development direction for the traveling grate-roasting process in steel pellet production, has significant social and economic benefits, and has an excellent prospect for large-scale popularization and implementation.

[0005] To achieve the above technical objectives, the technical solutions adopted by the utility model are described as follows:

[0006] A belt roasting system for multi-stage classification and injection of pulverized coal, which system includes a belt roaster and a pulverized coal injection pipeline. According to the material flow direction, the belt roaster includes a drying section, a preheating section, a roasting section and a cooling section connected in series in sequence, and a hot air hood is provided above the drying section, the preheating section, the roasting section and the cooling section. The air outlet of the hot air hood above the cooling section is connected to the air inlet of the hot air hood above the roasting section through a hot air circulation pipeline and a pneumatic coal conveying reciprocating pipe in sequence. The pneumatic coal conveying reciprocating pipe includes multiple inclined pipes connected in series in sequence, wherein the air inlet end of the inclined pipe at the bottommost is lower than its air outlet end, and the air inlet ends of the remaining inclined pipes are all higher than their respective air outlet ends. In the vertical direction, the downward inclination directions of any two adjacent inclined pipes are opposite and are connected through a vertical pipe. At least one pulverized coal injection pipeline is connected to the pneumatic coal conveying reciprocating pipe, and an ignition device is further provided on the pneumatic coal conveying reciprocating pipe downstream of the pulverized coal injection pipeline.

[0007] Preferably, ignition devices are independently provided on multiple inclined pipes of the pneumatic coal conveying reciprocating pipe. A pulverized coal injection pipeline is connected upstream of each inclined pipe provided with an ignition device.

[0008] Preferably, the inclined pipes provided with ignition devices are the 2nd to 20th consecutive inclined pipes upstream of the pneumatic coal conveying reciprocating pipe, preferably the 3rd to 15th consecutive inclined pipes.

[0009] Preferably, a coal ash collecting hopper is further provided at the lowermost end of the pneumatic coal conveying reciprocating pipe. The upper end of the coal ash collecting hopper is connected to the lower side pipe wall of the lowermost end of the pneumatic coal conveying reciprocating pipe through a connecting plate and a weighing spring in sequence.

[0010] Preferably, the weighing spring is a spring with an elastic sealing air curtain.

[0011] Preferably, a coal ash conveying belt is further provided below the ash discharge port at the bottom of the coal ash collecting hopper.

[0012] Preferably, the pulverized coal injection pipeline includes a pulverized coal main pipe and pulverized coal branch pipes. The pulverized coal main pipe is connected to the pneumatic coal conveying reciprocating pipe through the pulverized coal branch pipes, and a pulverized coal injection valve is provided on the pulverized coal branch pipes.

[0013] Preferably, the pulverized coal branch pipes intersect the pneumatic coal conveying reciprocating pipe obliquely, and the injection direction of the pulverized coal is opposite to the hot air flow direction.

[0014] Preferably, the pulverized coal main pipe is connected to the pneumatic coal conveying reciprocating pipe through multiple pulverized coal branch pipes with pulverized coal injection valves.

[0015] Preferably, multiple pulverized coal branch pipes with pulverized coal injection valves are uniformly distributed along the circumferential direction of the pneumatic coal conveying reciprocating pipe in a spiral winding manner.

[0016] Preferably, the ignition device includes multiple pairs of arc positive rods and arc negative rods. The multiple pairs of arc positive rods and arc negative rods are oppositely arranged on the two side walls of the inclined folding pipe along the flowing direction of the air flow.

[0017] Preferably, a partition mechanism is further arranged in the inclined folding pipe at the bottom of the reciprocating folding pipe for pneumatic coal transportation. The partition mechanism includes an upper partition board and a lower partition board. The upper partition board is vertically arranged on the upper inner wall of the pipe cavity of the bottommost inclined folding pipe by an upper plate driving motor, and the lower partition board is vertically arranged on the lower inner wall of the pipe cavity of the bottommost inclined folding pipe by a lower plate driving motor. The vertical heights of the upper partition board and the lower partition board are respectively driven by the upper plate driving motor and the lower plate driving motor. In the axial direction of the bottommost inclined folding pipe, the upper partition board and the lower partition board are alternately arranged at intervals in sequence.

[0018] Preferably, a gas injection pipeline is further connected to the reciprocating folding pipe for pneumatic coal transportation.

[0019] Preferably, a steam injection pipeline is further connected to the reciprocating folding pipe for pneumatic coal transportation.

[0020] Preferably, along the width direction of the roasting section, several temperature measuring elements are arranged in the hot air hood above the roasting section.

[0021] Preferably, a pair of reciprocating folding pipes for pneumatic coal transportation are symmetrically arranged on both sides in the width direction of the hot air hood above the roasting section.

[0022] Preferably, along the flowing direction of the material, multiple pairs of reciprocating folding pipes for pneumatic coal transportation are arranged on both sides of the hot air hood above the roasting section.

[0023] Preferably, the drying section includes a drum drying section and a suction drying section. The cooling section includes a first cooling section and a second cooling section. The bottom air inlets of the first cooling section and the second cooling section are independently connected with cooling air inlet pipelines. The top air outlet of the first cooling section is connected with the hot air circulation pipeline. The top air outlet of the second cooling section is connected with the bottom air inlet of the drum drying section through a first hot air circulation pipeline. A second hot air circulation pipeline is led out from the hot air circulation pipeline and connected with the top air inlet of the preheating section. The bottom air outlet of the roasting section is connected with the top air inlet of the suction drying section through a third hot air circulation pipeline. The top air outlets of the drum drying section, the bottom air outlets of the suction drying section, and the bottom air outlets of the preheating section are all connected with an external exhaust air pipe.

[0024] In the present utility model, generally, a cooling fan blows cooling air into the cooling section through a cooling air inlet duct to cool the high-temperature materials in the cooling section. After heat exchange, hot air is formed, and the hot air after heat exchange enters the roasting section through a secondary air inlet mechanism (hot air circulation duct and gas-coal conveying reciprocating pipe) arranged above the roasting section to serve as combustion-supporting air; during this process, according to the actual working conditions, pulverized coal is sprayed into the gas-coal conveying reciprocating pipe and ignited by an ignition device to heat the hot air so that the temperature of the hot air finally entering the roasting section meets the roasting requirements. That is, by utilizing the idle space above the belt roasting device and arranging a multi-section gas-coal conveying reciprocating pipe with a certain height, a place is provided for the injection and combustion of pulverized coal, enabling pulverized coal to replace high-quality gas as the roasting heat supply fuel without additional installation of a combustion chamber or additional occupation of space, significantly reducing the production cost. Compared with high-quality gas, which is expensive and inconvenient to transport, pulverized coal has the advantages of wider distribution, easier source acquisition and transportation, and stronger practicability and economy; that is to say, the present utility model realizes the breakthrough of replacing expensive gas with cheap pulverized coal as the roasting heat supply fuel without reducing the quality of the roasted products, overcomes the deficiencies of high process cost and limited process suitability of the existing belt roasting device, and provides a new development path for the belt roasting process in iron ore pellet production.

[0025] In the present utility model, by utilizing the idle space above the belt roasting device, the traditional secondary air duct is designed into a multi-section gas-coal conveying reciprocating pipe structure with a certain height, and a plurality of pulverized coal injection pipes (composed of a pulverized coal main pipe, pulverized coal branch pipes, and pulverized coal injection valves, etc.) and supporting ignition devices are respectively connected to different pipe sections of the gas-coal conveying reciprocating pipe. Its function is to spray pulverized coal into different pipe sections of the gas-coal conveying reciprocating pipe, so that the pulverized coal is mixed with the secondary hot air and descends evenly, and then is ignited by the ignition device to burn, thereby increasing the temperature of the secondary hot air. It should be noted that there is a preferred scheme for the arrangement of the pulverized coal injection pipes here, that is, a plurality of pulverized coal branch pipes are evenly distributed in a circumferential spiral around the gas-coal conveying reciprocating pipe, and are inclined so that the injection of pulverized coal is reverse to the air flow. By adopting this annular spiral reverse injection method, the mixing rate of pulverized coal and secondary hot air can be effectively strengthened, preventing the occurrence of uneven pulverized coal concentration, and laying a foundation for the subsequent rapid and complete combustion of pulverized coal.

[0026] In the present utility model, multiple pulverized coal injection pipes are respectively connected to different pipe sections of the reciprocating bent pipe for pneumatic coal transportation to inject pulverized coal. According to the different combustion efficiencies of different pulverized coals, pulverized coal can be selectively injected from the pulverized coal injection pipes at different height positions. Generally, the pulverized coal with a longer burnout time or a larger particle size is injected at a position closer to the front (i.e., closer to the upstream end of the reciprocating bent pipe for pneumatic coal transportation), and vice versa. This enables the pulverized coal to burn out and allows the hot air at the highest temperature to quickly enter the roasting section, effectively reducing the heat loss during the flow of high-temperature hot air in the reciprocating bent pipe for pneumatic coal transportation. Further, the pulverized coal can also be dispersed and injected through multiple pulverized coal injection pipes (i.e., after determining the addition amount of pulverized coal per unit time, the pulverized coal to be added is evenly divided into multiple portions and injected simultaneously from multiple positions, which can enable the pulverized coal to burn simultaneously and contribute to improving the combustion efficiency. Compared with injecting all the pulverized coal from one position at the same time, the time required for pulverized coal injection and burnout can be significantly reduced. It should be noted that when the pulverized coal is injected in a multi-point manner, according to the direction of the air flow, the amount of pulverized coal injected at each position is equal or gradually decreasing, and it is adjusted according to the actual working conditions), enabling the pulverized coal to burn out faster and better, thereby improving the utilization efficiency of the pulverized coal.

[0027] In the present utility model, the reciprocating bent pipe for pneumatic coal transportation of the present utility model includes multiple obliquely bent pipes connected in series in sequence. The air inlet end of the obliquely bent pipe at the bottom is lower than its air outlet end, and the air inlet ends of the remaining obliquely bent pipes are all higher than their respective air outlet ends. In the vertical direction, the downward inclination directions of any two adjacent obliquely bent pipes are opposite and are connected by a vertical pipe. The ignition device is mainly arranged on multiple obliquely bent pipes (generally multiple obliquely bent pipes continuously from top to bottom) upstream of the reciprocating bent pipe for pneumatic coal transportation, and a pulverized coal injection pipe is connected to the upstream pipe body or the vertical pipe of each obliquely bent pipe provided with the ignition device. That is, the uniformly mixed coal-air mixture is heated and ignited by the ignition device, enabling the pulverized coal to quickly burn out in the reciprocating bent pipe for pneumatic coal transportation, thereby significantly increasing the temperature of the secondary hot air and ensuring the uniformity of the temperature in the roasting section, which helps to improve and guarantee the quality of the roasted products. In a preferred embodiment, the ignition device specifically includes a number of pairs of alternating current arc electrodes uniformly distributed and symmetrically arranged along the air flow direction on the two side pipe walls of the obliquely bent pipe. Each pair of electrodes consists of an arc positive electrode rod and an arc negative electrode rod, and its function is to form a breakdown arc between the positive and negative electrode rods to form a local high temperature, thereby igniting the pulverized coal flow passing between the electrode rods, enabling the pulverized coal to burn quickly while flowing downward in the reciprocating bent pipe for pneumatic coal transportation.

[0028] In the present utility model, due to the relatively high silicon content in coal ash, it is easy to cause the agglomeration of pellet ore. To prevent pulverized coal from entering the roasting material layer, a coal ash collection hopper is added at the lowest end of the reciprocating folding pipe for gas coal transportation (generally referring to the bottom end of the inclined folding pipe at the bottom). The upper end of the coal ash collection hopper is connected to the bottom end of the weighing spring through a connecting plate, and the upper end of the weighing spring is fixed on the wall of the lowest end of the reciprocating folding pipe for gas coal transportation (it should be noted that a dust fall port communicating with the coal ash collection hopper is opened at the lowest end of the reciprocating folding pipe for gas coal transportation). The purpose is to accumulate and weigh the coal ash generated by the combustion of pulverized coal in the reciprocating folding pipe for gas coal transportation under the action of gravity here, so as to judge whether there is coal ash entering the hot air hood in the roasting section or whether there is an abnormal condition where pulverized coal is not completely burned. It should be noted that the weighing spring is a weighing spring with an elastic sealing air curtain. The material of the elastic sealing air curtain can be any non-venting soft material and does not affect the expansion and contraction of the spring. Its main function is to ensure airtightness and prevent air leakage.

[0029] In the present utility model, the inclined folding pipe at the bottom of the reciprocating folding pipe for gas coal transportation is designed with an upward inclination (i.e., the air inlet end is lower than its air outlet end) where the bottom end is lower than the height of the air inlet of the hot air hood in the roasting section; a labyrinth partition mechanism is also added in the inclined upwardly arranged inclined folding pipe, which consists of an upper partition board, an upper board driving motor, a lower partition board, a lower board driving motor, etc. Among them, the lower and upper partition boards are respectively arranged in the front and back in the direction of the oncoming flow of pulverized coal (any setting angle should be included in the protection scope of the present utility model). The purpose is to block the pulverized coal and coal ash entrained in the secondary hot air reaching the bottom and continuing to flow through the inclined folding pipe to the roasting section under the action of the partition board, and make the blocked pulverized coal and coal ash sink to the lower coal ash collection hopper under the action of natural gravity.

[0030] In the present utility model, a number of temperature measuring elements are also arranged in the hot air hood above the roasting section. The purpose is to infer whether the temperature in the roasting chamber is uniform by measuring the temperature of the elements, and further infer whether there is unburned pulverized coal entering the roasting chamber and continuing to burn.

[0031] In the present utility model, when using the system described in the present utility model for production, the amount of pulverized coal injected is controlled through the pulverized coal injection pipeline according to the actual working conditions to ensure the stable operation of the system. Specifically: the system will first detect a number of working condition parameters in the current working condition (including pellet quality, required roasting temperature, calorific value of pulverized coal, etc.), and calculate the value of pulverized coal that should be injected. For example, if the amount of pulverized coal injected through the pulverized coal injection pipeline per unit time is set as W mf , Kg: then there is:

[0032] W mf =W qt ×C qt ×(T1 - T0)÷Q mf (1)

[0033] In formula (1), W qt is the mass of pellets flowing through the roasting section per unit time, in Kg. C qt is the specific heat capacity of the pellets, in KJ / (kg·°C). T1 is the target temperature to which the pellets in the roasting section need to be heated, in °C. T0 is the initial temperature of the pellets in the roasting section, in °C. Q mf is the calorific value of the pulverized coal, in KJ / Kg.

[0034] Furthermore, when the amount of pulverized coal injected through the pulverized coal injection pipe per unit time is W mf : The system automatically controls the opening of the pulverized coal injection valve according to this calculated value. At the same time, based on the pulverized coal injection value, it calculates the length range of the pipe section in the middle vertical pipe where the arc ignition area is required, as well as the pulverized coal ash generation value, etc. For example, if the length of the pipe section where the ignition device heats the reciprocating folding pipe for gas coal transportation is set as L, in m. The generated mass of pulverized coal ash is W mh , in Kg. Then there is:

[0035] L = W mf ×λ×V×d (2)

[0036] W mh = W mf ×η (3)

[0037] In formulas (2)-(3), λ is the length correction coefficient, with a value range of 7.4 to 13.1 (preferably 8 to 11.5). V is the hot air flow velocity entering the roasting section, in m / s. d is the particle size of the pulverized coal, in m. η is the pulverized coal ash generation coefficient, with a value range of 0.005 to 0.05.

[0038] It should be noted that the system turns on the corresponding arc elements according to the calculation results of formulas (2)-(3). For example, if the calculated height L requires turning on 5 pairs of AC arc electrodes, then 5 pairs of AC arc electrodes are turned on. If 10 pairs of electrode rods need to be turned on, then 10 pairs are turned on. After determining the number of pairs of AC arc electrodes to be turned on, the pulverized coal is injected and burned. During this process, the system will detect whether the weight of the pulverized coal ash measured in the ash discharge hopper is the same as the calculated pulverized coal ash generation value W mhEqual. If they are equal, the current adjustment ends. If not, it enters the feedback adjustment process. In the feedback adjustment process, the system will use several temperature measuring elements set in the hot air hood above the roasting section to detect whether the temperature values at different positions in the hot air hood of the roasting section are evenly distributed: If so, it indicates that the pulverized coal has been burned out in the reciprocating pipe for pneumatic coal transportation, but the coal ash has entered the roasting section. At this time, the system will send a signal to the labyrinth partition mechanism to increase the insertion depth of the partition plates (the upper partition plate and the lower partition plate), reducing the possibility of the pulverized coal being carried into the roasting section by the secondary hot air; If the temperature is not evenly distributed, it indicates that the pulverized coal has not been burned out in the reciprocating pipe for pneumatic coal transportation and there is still secondary combustion after entering the roasting section. At this time, the system will send a signal to the ignition device to extend the distance range of the ignition arc area on the reciprocating pipe for pneumatic coal transportation (i.e., increase the number of pairs of AC arc electrodes turned on). After this operation, the system will continue to detect the weight of the ash powder in the ash hopper and compare it with the calculated coal ash generation value. If they are still not equal, the steps of this process will be repeated until they are equal. If they are equal, the system defaults that the current adjustment ends.

[0039] It should be noted that all the formulas in the present invention are obtained by the inventor through fitting after experiments and engineering applications. All calculations are based on the values after unit conversion according to the regulations. The values after unit conversion are substituted into the formulas for calculation (after unit conversion, only the numerical values are substituted into the formulas for calculation, without substituting the units. The units are only used to adjust the magnitude of the numerical values).

[0040] In the present invention, the present invention also adds a gas injection device (a gas injection pipe with a control regulating valve) on the reciprocating pipe for pneumatic coal transportation. Its function is to assist combustion with gas when the pulverized coal injection amount cannot be increased, providing qualified high-temperature secondary hot air for the roasting section.

[0041] In the present invention, the present invention also adds a steam injection device (a steam injection pipe with a control regulating valve) on the reciprocating pipe for pneumatic coal transportation. Its function is to assist steam injection to react with the pulverized coal to produce water gas reaction when both the pulverized coal injection amount and the gas injection amount cannot be increased and the pulverized coal is difficult to burn out, strengthening the burnout rate of the pulverized coal and providing qualified high-temperature secondary hot air for the roasting section.

[0042] In the present invention, the system of the present invention has a function associated with an external automatic control and adjustment mechanism, realizing the automatic and precise control and adjustment of the system through the automatic control and adjustment mechanism, thereby ensuring the stability and safety of the system operation.

[0043] In the present utility model, in a preferred embodiment, the diameter of the hot air circulation pipeline is 5 - 300 cm, preferably 8 - 200 cm, and more preferably 10 - 100 cm. The diameter of the reciprocating pipe for pneumatic coal transportation is 1 - 200 cm, preferably 3 - 150 cm, and more preferably 5 - 80 cm. The diameter of the pulverized coal injection pipeline is 5 - 100 cm, preferably 8 - 80 cm, and more preferably 10 - 50 cm. The inclination angle of the inclined pipe is 10 - 80°, preferably 15 - 70°, and more preferably 20 - 60°. The thickness of the hot air hood is 0.1 - 80 cm, preferably 0.5 - 50 cm, and more preferably 1 - 30 cm.

[0044] Compared with the prior art, the beneficial technical effects of the present utility model are as follows:

[0045] 1: The present utility model utilizes the idle space above the belt roasting device. By setting a multi-section reciprocating pipe for pneumatic coal transportation with a certain height, a place is provided for the injection and combustion of pulverized coal, enabling the pulverized coal to replace high-quality gas as the roasting heating fuel without the need to additionally set up a combustion chamber or occupy additional space, significantly reducing the production cost.

[0046] 2: Compared with high-quality gas, which is expensive and inconvenient to transport, pulverized coal has the advantages of wider distribution, easier source acquisition and transportation, etc., and is more practical and economical; that is to say, the present utility model realizes the breakthrough of using cheap pulverized coal instead of expensive gas as the roasting heating fuel without reducing the quality of the roasted products, overcomes the deficiencies of the existing belt roasting device with high process cost and limited process suitability, and provides a new development path for the belt roasting process in iron and steel pellet production.

[0047] 3: The belt roasting system of the present utility model can be implemented without occupying additional space, and has low investment and operation costs. The overall structure is simple, and the operation is stable and reliable, having excellent practical application value in the future market. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic cross-sectional structure diagram of the roasting section described in the present utility model.

[0049] Figure 2 It is a schematic longitudinal cross-sectional structure diagram of the belt roasting machine described in the present utility model.

[0050] Figure 3 It is a schematic structure diagram of the pulverized coal injection pipeline described in the present utility model.

[0051] Figure 4 It is a schematic structure diagram of the pulverized coal injection pipeline of the present utility model when there are multiple pulverized coal branch pipes.

[0052] Figure 5This is a schematic cross-sectional view of the pulverized coal injection pipeline of the present utility model when it has multiple pulverized coal branch pipes.

[0053] Figure 6 This is a schematic diagram of the structure and distribution of the ignition device of the present utility model.

[0054] Figure 7 This is an enlarged schematic view of the coal ash collection hopper of the present utility model.

[0055] Figure 8 This is an enlarged schematic view of the partition mechanism of the present utility model.

[0056] Reference numerals: 1: belt grate; 101: drying section; 1011: drum drying section; 1012: suction drying section; 102: preheating section; 103: roasting section; 104: cooling section; 1041: first cooling section; 1042: second cooling section; 105: hot air hood; 106: cooling air inlet pipe; 107: first hot air circulation pipe; 108: second hot air circulation pipe; 109: third hot air circulation pipe; 110: exhaust air pipe; 2: pulverized coal injection pipeline; 201: pulverized coal main pipe; 202: pulverized coal branch pipe; 203: pulverized coal injection valve; 3: hot air circulation pipe; 4: reciprocating folding pipe for gas coal transportation; 401: inclined folding pipe; 402: vertical pipe; 403: gas injection pipeline; 404: steam injection pipeline; 5: ignition device; 501: arc positive electrode rod; 502: arc negative electrode rod; 6: coal ash collection hopper; 601: connecting plate; 602: weighing spring; 603: ash conveying belt; 7: partition mechanism; 701: upper partition board; 702: lower partition board; 703: upper plate driving motor; 704: lower plate driving motor; 8: temperature measuring element. Specific embodiments

[0057] The technical solutions of the present utility model will be illustrated by way of examples below. The scope of protection claimed by the present utility model includes but is not limited to the following embodiments.

[0058] A belt roasting system for multi-stage classification and injection of pulverized coal, which system includes a belt roaster 1 and a pulverized coal injection pipeline 2. According to the material flow direction, the belt roaster 1 includes a drying section 101, a preheating section 102, a roasting section 103, and a cooling section 104 that are connected in series in sequence. A hot air hood 105 is provided above the drying section 101, the preheating section 102, the roasting section 103, and the cooling section 104. The air outlet of the hot air hood 105 above the cooling section 104 is connected to the air inlet of the hot air hood 105 above the roasting section 103 through a hot air circulation pipeline 3 and a gas coal conveying reciprocating elbow 4 in sequence. The gas coal conveying reciprocating elbow 4 includes a plurality of inclined elbows 401 connected in series in sequence, wherein the air inlet end of the inclined elbow 401 at the bottommost part is lower than its air outlet end, and the air inlet ends of the remaining inclined elbows 401 are all higher than their respective air outlet ends. In the vertical direction, the downward inclination directions of any two adjacent inclined elbows 401 are opposite and are connected through a vertical pipe 402. At least one pulverized coal injection pipeline 2 is connected to the gas coal conveying reciprocating elbow 4, and an ignition device 5 is further provided on the gas coal conveying reciprocating elbow 4 downstream of the pulverized coal injection pipeline 2.

[0059] Preferably, ignition devices 5 are independently provided on each of the plurality of inclined elbows 401 of the gas coal conveying reciprocating elbow 4. A pulverized coal injection pipeline 2 is connected to the upstream of each inclined elbow 401 provided with an ignition device 5.

[0060] Preferably, the inclined elbows 401 provided with ignition devices 5 are the 2nd to 20th consecutive inclined elbows 401 upstream of the gas coal conveying reciprocating elbow 4, preferably the 3rd to 15th consecutive inclined elbows 401.

[0061] Preferably, a coal ash collection hopper 6 is further provided at the lowermost end of the gas coal conveying reciprocating elbow 4. The upper end of the coal ash collection hopper 6 is connected to the lower side pipe wall of the lowermost end of the gas coal conveying reciprocating elbow 4 through a connecting plate 601 and a weighing spring 602 in sequence.

[0062] Preferably, the weighing spring 602 is a spring with an elastic sealing air curtain.

[0063] Preferably, a ash conveying belt 603 is further provided below the ash discharge port at the bottom of the coal ash collection hopper 6.

[0064] Preferably, the pulverized coal injection pipeline 2 includes a pulverized coal main pipe 201 and pulverized coal branch pipes 202. The pulverized coal main pipe 201 is connected to the gas coal conveying reciprocating elbow 4 through the pulverized coal branch pipes 202, and a pulverized coal injection valve 203 is provided on the pulverized coal branch pipes 202.

[0065] Preferably, the pulverized coal branch pipes 202 intersect the gas coal conveying reciprocating elbow 4 obliquely, and the injection direction of the pulverized coal is opposite to the hot air flow direction.

[0066] Preferably, the pulverized coal main pipe 201 is communicated with the reciprocating bent pipe 4 for gas coal transportation through a plurality of pulverized coal branch pipes 202 each provided with a pulverized coal injection valve 203.

[0067] Preferably, a plurality of pulverized coal branch pipes 202 each provided with a pulverized coal injection valve 203 are uniformly distributed along the circumferential direction of the reciprocating bent pipe 4 for gas coal transportation in a spiral winding manner.

[0068] Preferably, the ignition device 5 includes a plurality of pairs of arc positive rods 501 and arc negative rods 502. The plurality of pairs of arc positive rods 501 and arc negative rods 502 are oppositely arranged on the two side walls of the inclined bent pipe 401 along the flowing direction of the air flow.

[0069] Preferably, a partition mechanism 7 is further provided in the inclined bent pipe 401 at the bottommost part of the reciprocating bent pipe 4 for gas coal transportation. The partition mechanism 7 includes an upper partition board 701 and a lower partition board 702. The upper partition board 701 is vertically arranged on the upper inner wall of the pipe cavity of the bottommost inclined bent pipe 401 through an upper plate driving motor 703, and the lower partition board 702 is vertically arranged on the lower inner wall of the pipe cavity of the bottommost inclined bent pipe 401 through a lower plate driving motor 704. The vertical heights of the upper partition board 701 and the lower partition board 702 are respectively driven by the upper plate driving motor 703 and the lower plate driving motor 704. In the axial direction of the bottommost inclined bent pipe 401, the upper partition board 701 and the lower partition board 702 are alternately arranged at intervals.

[0070] Preferably, a gas injection pipeline 403 is further connected to the reciprocating bent pipe 4 for gas coal transportation.

[0071] Preferably, a steam injection pipeline 404 is further connected to the reciprocating bent pipe 4 for gas coal transportation.

[0072] Preferably, along the width direction of the roasting section 103, a plurality of temperature measuring elements 8 are arranged in the hot air hood 105 above the roasting section 103.

[0073] Preferably, a pair of reciprocating bent pipes 4 for gas coal transportation are symmetrically arranged on both sides in the width direction of the hot air hood 105 above the roasting section 103.

[0074] Preferably, along the flowing direction of the material, a plurality of pairs of reciprocating bent pipes 4 for gas coal transportation are arranged on both sides of the hot air hood 105 above the roasting section 103.

[0075] Preferably, the drying section 101 includes a drum drying section 1011 and a suction drying section 1012. The cooling section 104 includes a first cooling section 1041 and a second cooling section 1042. The bottom air inlets of the first cooling section 1041 and the second cooling section 1042 are each independently connected to a cooling air inlet duct 106. The top air outlet of the first cooling section 1041 is connected to the hot air circulation duct 3. The top air outlet of the second cooling section 1042 is connected to the bottom air inlet of the drum drying section 1011 through a first hot air circulation duct 107. A second hot air circulation duct 108 is led out from the hot air circulation duct 3 and connected to the top air inlet of the preheating section 102. The bottom air outlet of the roasting section 103 is connected to the top air inlet of the suction drying section 1012 through a third hot air circulation duct 109. The top air outlets of the drum drying section 1011, the bottom air outlets of the suction drying section 1012, and the bottom air outlets of the preheating section 102 are all connected to an exhaust duct 110.

[0076] Example 1

[0077] As Figure 1-8 shown, a belt roasting system for multi-stage classification injection of pulverized coal includes a belt roaster 1 and a pulverized coal injection pipe 2. According to the material flow direction, the belt roaster 1 includes a drying section 101, a preheating section 102, a roasting section 103, and a cooling section 104 connected in series in sequence. A hot air hood 105 is provided over the drying section 101, the preheating section 102, the roasting section 103, and the cooling section 104. The air outlet of the hot air hood 105 above the cooling section 104 is connected to the air inlet of the hot air hood 105 above the roasting section 103 through a hot air circulation duct 3 and a gas coal conveying reciprocating elbow 4 in sequence. The gas coal conveying reciprocating elbow 4 includes a plurality of obliquely bent pipes 401 connected in series in sequence, wherein the air inlet end of the obliquely bent pipe 401 at the bottommost is lower than its air outlet end, and the air inlet ends of the remaining obliquely bent pipes 401 are all higher than their respective air outlet ends. In the vertical direction, the downward inclination directions of any two adjacent obliquely bent pipes 401 are opposite and are connected through a vertical pipe 402. At least one pulverized coal injection pipe 2 is connected to the gas coal conveying reciprocating elbow 4, and a ignition device 5 is further provided on the gas coal conveying reciprocating elbow 4 downstream of the pulverized coal injection pipe 2.

[0078] Example 2

[0079] Repeat Example 1, except that ignition devices 5 are independently provided on each of the plurality of obliquely bent pipes 401 of the gas coal conveying reciprocating elbow 4. A pulverized coal injection pipe 2 is connected upstream of each obliquely bent pipe 401 provided with an ignition device 5.

[0080] Example 3

[0081] Repeat Example 2, except that the obliquely bent pipes 401 provided with ignition devices 5 are the first to third consecutive obliquely bent pipes 401 upstream of the gas coal conveying reciprocating elbow 4.

[0082] Example 4

[0083] Repeat Example 3, except that a coal ash collecting hopper 6 is further provided at the lowest end of the reciprocating bent pipe 4 for gas coal transportation. The upper end of the coal ash collecting hopper 6 is sequentially connected to the lower side wall of the lowest end of the reciprocating bent pipe 4 for gas coal transportation through a connecting plate 601 and a weighing spring 602.

[0084] Example 5

[0085] Repeat Example 4, except that the weighing spring 602 is a spring with an elastic sealing air curtain.

[0086] Example 6

[0087] Repeat Example 5, except that a coal ash conveying belt 603 is further provided below the ash discharge opening at the bottom of the coal ash collecting hopper 6.

[0088] Example 7

[0089] Repeat Example 6, except that the pulverized coal injection pipe 2 includes a pulverized coal main pipe 201 and pulverized coal branch pipes 202. The pulverized coal main pipe 201 is connected to the reciprocating bent pipe 4 for gas coal transportation through the pulverized coal branch pipes 202, and a pulverized coal injection valve 203 is provided on the pulverized coal branch pipes 202.

[0090] Example 8

[0091] Repeat Example 7, except that the pulverized coal branch pipes 202 intersect the reciprocating bent pipe 4 for gas coal transportation obliquely, and the injection direction of the pulverized coal is opposite to the direction of the hot air flow.

[0092] Example 9

[0093] Repeat Example 8, except that the pulverized coal main pipe 201 is connected to the reciprocating bent pipe 4 for gas coal transportation through multiple pulverized coal branch pipes 202 with pulverized coal injection valves 203.

[0094] Example 10

[0095] Repeat Example 9, except that multiple pulverized coal branch pipes 202 with pulverized coal injection valves 203 are evenly distributed along the circumferential direction of the reciprocating bent pipe 4 for gas coal transportation in a spiral winding manner.

[0096] Example 11

[0097] Repeat Example 10, except that the ignition device 5 includes multiple pairs of arc positive rods 501 and arc negative rods 502. Multiple pairs of arc positive rods 501 and arc negative rods 502 are oppositely arranged on the two side walls of the inclined bent pipe 401 along the flow direction of the air flow.

[0098] Example 12

[0099] Repeat Example 11, except that a partition mechanism 7 is further provided in the inclined folding pipe 401 at the bottommost part of the reciprocating folding pipe 4 for pneumatic coal conveying. The partition mechanism 7 includes an upper partition board 701 and a lower partition board 702. The upper partition board 701 is vertically arranged on the upper inner wall of the pipe cavity of the bottommost inclined folding pipe 401 by an upper plate driving motor 703, and the lower partition board 702 is vertically arranged on the lower inner wall of the pipe cavity of the bottommost inclined folding pipe 401 by a lower plate driving motor 704. The vertical heights of the upper partition board 701 and the lower partition board 702 are respectively driven by the upper plate driving motor 703 and the lower plate driving motor 704. In the axial direction of the bottommost inclined folding pipe 401, the upper partition board 701 and the lower partition board 702 are alternately arranged at intervals in sequence.

[0100] Example 13

[0101] Repeat Example 12, except that a gas injection pipe 403 is further connected to the reciprocating folding pipe 4 for pneumatic coal conveying.

[0102] Example 14

[0103] Repeat Example 13, except that a steam injection pipe 404 is further connected to the reciprocating folding pipe 4 for pneumatic coal conveying.

[0104] Example 15

[0105] Repeat Example 14, except that along the width direction of the roasting section 103, a plurality of temperature measuring elements 8 are provided in the hot air hood 105 above the roasting section 103.

[0106] Example 16

[0107] Repeat Example 15, except that a pair of reciprocating folding pipes 4 for pneumatic coal conveying are symmetrically arranged on both sides in the width direction of the hot air hood 105 above the roasting section 103.

[0108] Example 17

[0109] Repeat Example 16, except that along the flow direction of the material, multiple pairs of reciprocating folding pipes 4 for pneumatic coal conveying are arranged on both sides of the hot air hood 105 above the roasting section 103.

[0110] Example 18

[0111] Repeat Example 17, except that the drying section 101 includes a drum drying section 1011 and a suction drying section 1012. The cooling section 104 includes a first cooling section 1041 and a second cooling section 1042. The bottom air inlets of the first cooling section 1041 and the second cooling section 1042 are independently connected to a cooling air inlet duct 106. The top air outlet of the first cooling section 1041 is connected to the hot air circulation duct 3. The top air outlet of the second cooling section 1042 is connected to the bottom air inlet of the drum drying section 1011 through a first hot air circulation duct 107. A second hot air circulation duct 108 is also led out from the hot air circulation duct 3 and connected to the top air inlet of the preheating section 102. The bottom air outlet of the roasting section 103 is connected to the top air inlet of the suction drying section 1012 through a third hot air circulation duct 109. The top air outlets of the drum drying section 1011, the bottom air outlets of the suction drying section 1012, and the bottom air outlets of the preheating section 102 are all connected to an exhaust air duct 110.

Claims

1. A belt roasting system for multi-stage classification and injection of pulverized coal, characterized in that: The system includes a traveling grate roaster (1) and a pulverized coal injection pipeline (2); according to the material flow direction, the traveling grate roaster (1) includes a drying section (101), a preheating section (102), a roasting section (103), and a cooling section (104) connected in series in sequence, and a hot air hood (105) is provided above the drying section (101), the preheating section (102), the roasting section (103), and the cooling section (104); the air outlet of the hot air hood (105) above the cooling section (104) is sequentially connected to the air inlet of the hot air hood (105) above the roasting section (103) through a hot air circulation pipeline (3) and a gas and coal conveying reciprocating elbow pipe (4); the gas and coal conveying reciprocating elbow pipe (4) includes a plurality of obliquely bent pipes (401) connected in series in sequence, wherein the air inlet end of the obliquely bent pipe (401) at the bottommost is lower than its air outlet end, and the air inlet ends of the remaining obliquely bent pipes (401) are all higher than their respective air outlet ends; in the vertical direction, the downward inclination directions of any two adjacent obliquely bent pipes (401) are opposite and are connected by a vertical pipe (402); at least one pulverized coal injection pipeline (2) is connected to the gas and coal conveying reciprocating elbow pipe (4), and a ignition device (5) is further provided on the gas and coal conveying reciprocating elbow pipe (4) downstream of the pulverized coal injection pipeline (2).

2. The system according to claim 1, wherein: Ignition devices (5) are independently provided on the plurality of obliquely bent pipes (401) of the gas and coal conveying reciprocating elbow pipe (4); a pulverized coal injection pipeline (2) is connected upstream of each obliquely bent pipe (401) provided with an ignition device (5).

3. The system according to claim 2, wherein: The obliquely bent pipes (401) provided with ignition devices (5) are the 2nd to 20th consecutive obliquely bent pipes (401) upstream of the gas and coal conveying reciprocating elbow pipe (4).

4. The system according to claim 3, wherein: The obliquely bent pipes (401) provided with ignition devices (5) are the 3rd to 15th consecutive obliquely bent pipes (401) upstream of the gas and coal conveying reciprocating elbow pipe (4).

5. The system according to claim 2, wherein: A coal ash collection hopper (6) is further provided at the lowermost end of the gas and coal conveying reciprocating elbow pipe (4); the upper end of the coal ash collection hopper (6) is sequentially connected to the lower side pipe wall of the lowermost end of the gas and coal conveying reciprocating elbow pipe (4) through a connecting plate (601) and a weighing spring (602).

6. The system according to claim 5, wherein: The weighing spring (602) is a spring with an elastic sealing air curtain.

7. The system according to claim 5, wherein: A coal ash conveying belt (603) is further provided below the ash discharge port at the bottom of the coal ash collection hopper (6).

8. The system according to claim 2, wherein: The pulverized coal injection pipeline (2) includes a pulverized coal main pipe (201) and pulverized coal branch pipes (202); the pulverized coal main pipe (201) is communicated with the gas and coal conveying reciprocating elbow pipe (4) through the pulverized coal branch pipes (202), and a pulverized coal injection valve (203) is provided on the pulverized coal branch pipe (202).

9. The system according to claim 8, wherein: The pulverized coal branch pipe (202) intersects the gas and coal conveying reciprocating elbow pipe (4) obliquely, and the pulverized coal injection direction is opposite to the hot air flow direction.

10. The system according to claim 8, wherein: The pulverized coal main pipe (201) is communicated with the gas and coal conveying reciprocating elbow pipe (4) through a plurality of pulverized coal branch pipes (202) with pulverized coal injection valves (203).

11. The system according to claim 10, wherein: A plurality of pulverized coal branch pipes (202) with pulverized coal injection valves (203) are uniformly distributed along the circumferential direction of the gas and coal conveying reciprocating elbow pipe (4) in a spiral winding manner.

12. The system according to claim 2, wherein: The ignition device (5) includes multiple pairs of arc positive rods (501) and arc negative rods (502); the multiple pairs of arc positive rods (501) and arc negative rods (502) are oppositely arranged on the two side walls of the inclined folding pipe (401) along the flowing direction of the air flow.

13. The system according to claim 2, wherein: A partition mechanism (7) is further arranged in the inclined folding pipe (401) at the bottommost part of the reciprocating folding pipe (4) for pneumatic coal transportation; the partition mechanism (7) includes an upper partition board (701) and a lower partition board (702); the upper partition board (701) is vertically arranged on the upper inner wall of the pipe cavity of the bottommost inclined folding pipe (401) through an upper plate driving motor (703), and the lower partition board (702) is vertically arranged on the lower inner wall of the pipe cavity of the bottommost inclined folding pipe (401) through a lower plate driving motor (704); the vertical heights of the upper partition board (701) and the lower partition board (702) are respectively driven by the upper plate driving motor (703) and the lower plate driving motor (704); in the axial direction of the bottommost inclined folding pipe (401), the upper partition board (701) and the lower partition board (702) are alternately arranged at intervals.

14. The system according to any one of claims 2-13, characterized in that: A gas injection pipeline (403) is further connected to the reciprocating folding pipe (4) for pneumatic coal transportation; and / or A steam injection pipeline (404) is further connected to the reciprocating folding pipe (4) for pneumatic coal transportation.

15. The system according to any one of claims 2-13, characterized in that: Along the width direction of the roasting section (103), a plurality of temperature measuring elements (8) are arranged in the hot air hood (105) above the roasting section (103).

16. The system according to any one of claims 2-13, characterized in that: A pair of reciprocating folding pipes (4) for pneumatic coal transportation are symmetrically arranged on both sides in the width direction of the hot air hood (105) above the roasting section (103).

17. The system according to claim 16, characterized in that: Along the flowing direction of the material, multiple pairs of reciprocating folding pipes (4) for pneumatic coal transportation are arranged on both sides of the hot air hood (105) above the roasting section (103).

18. The system according to any one of claims 1-13 and 17, characterized in that: The drying section (101) includes a blowing drying section (1011) and a suction drying section (1012); the cooling section (104) includes a first cooling section (1041) and a second cooling section (1042); the bottom air inlets of the first cooling section (1041) and the second cooling section (1042) are independently connected with cooling air inlet pipes (106); the top air outlet of the first cooling section (1041) is connected with the hot air circulation pipeline (3); the top air outlet of the second cooling section (1042) is connected with the bottom air inlet of the blowing drying section (1011) through a first hot air circulation pipeline (107); a second hot air circulation pipeline (108) is led out from the hot air circulation pipeline (3) and connected with the top air inlet of the preheating section (102); the bottom air outlet of the roasting section (103) is connected with the top air inlet of the suction drying section (1012) through a third hot air circulation pipeline (109); the top air outlets of the blowing drying section (1011), the bottom air outlets of the suction drying section (1012) and the bottom air outlets of the preheating section (102) are all connected with an exhaust air pipe (110).

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