Pulverized coal coupled hot air direct current heat supply belt type roasting system

Abstract

The utility model discloses a pulverized coal coupling hot air direct current heat supply belt type roasting system. The system comprises a belt type roasting machine and an air and coal injection mechanism. According to the trend of materials, the belt type roasting machine comprises a drying section, a preheating section, a roasting section and a cooling section which are sequentially connected in series and a hot air cover arranged above the sections in a covering mode. And the air-coal injection mechanism comprises a hot air main pipe, a hot air branch pipe and a pulverized coal injection pipeline. Cheap pulverized coal can be used as heat supply fuel for the belt type roasting device, the belt type roasting device has the advantage of being low in production cost and can be achieved without changing a main body of an existing belt type roasting device, the application range of the existing belt type roasting device is greatly expanded, and the cost is reduced. A new development direction is provided for a belt type roasting process in steel pellet production, social and economic benefits are remarkable, and the method has an excellent prospect of large-scale popularization, implementation and application.

Description

Technical Field

[0001] The utility model relates to iron and steel metallurgy production equipment, in particular to a belt roasting system with pulverized coal coupled with hot air direct current heating, belonging to the technical field of iron and steel metallurgy production. Background Art

[0002] Oxidized pellets are an important type of furnace charge 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-rotary kiln process, and the shaft furnace pellet process. Among them, the shaft furnace pellet process has been gradually phased out, with a market share of less than 5%; and the grate-kiln process has become the mainstream of the future pellet market by virtue of its advantages such as small floor area, good equipment integrity, and advanced energy consumption and emission indicators.

[0003] In the current trend of the iron and steel market, vigorously developing low-cost pellet processes is the key to the future upgrading and transformation of iron and steel. Currently, as the mainstream pellet process, the grate-kiln process 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 grate-kiln process currently has to 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 entire grate-kiln 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 grate-kiln pellet production line, which in turn leads to the inability to select the grate-kiln process. Summary of the Utility Model

[0004] Aiming at the problems of high production cost and limited application existing in the existing belt roasting process using high-calorific-value gas as fuel in the prior art, the utility model provides a belt roasting system with pulverized coal coupled with hot air direct current heating. This system can use cheap pulverized coal as the heating fuel for the belt roasting device, has the advantage of low production cost, can be achieved without modifying the main body of the existing belt roasting device, greatly expands the application range of the existing belt roasting device, provides a new development direction for the belt roasting process in iron and 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 as follows:

[0006] A belt roasting system with pulverized coal coupled with hot air direct current heating, which includes a grate-kiln and a coal and air injection mechanism. According to the material flow direction, the grate-kiln includes a drying section, a preheating section, a roasting section, a cooling section connected in series in sequence, and a hot air hood covering above each section. The coal and air injection mechanism includes a main hot air pipe, a branch hot air pipe, and a pulverized coal injection pipeline.

[0007] The air inlet end of the main hot air pipe is connected to the top air outlet of the cooling section, and its air outlet end extends above the hot air hood in the roasting section. The hot air branch pipe is vertically arranged as a whole. Its upper end is connected to the air exhaust end of the main hot air pipe, and its lower end extends downward and is connected to the air inlet of the hot air hood above the roasting section. The pulverized coal injection pipe is connected to the upper part of the hot air branch pipe, and a heating ignition device is arranged in the middle of the hot air branch pipe.

[0008] Preferably, the hot air branch pipe includes an upper downward inclined pipe, a middle vertical pipe, and a lower upward inclined pipe. The top of the upper downward inclined pipe is communicated with the main hot air pipe, and its bottom end extends downward obliquely and is communicated with the top of the middle vertical pipe. The bottom end of the lower upward inclined pipe is communicated with the bottom end of the middle vertical pipe, and its top end extends upward obliquely and is communicated with the side air inlet of the hot air hood above the roasting section. The pulverized coal injection pipe is communicated with the upper downward inclined pipe, and the heating ignition device is arranged on the middle vertical pipe.

[0009] Preferably, the system further includes a coal ash collection and weighing mechanism, which includes an ash hopper, a bearing plate, and a weighing elastic member. The upper end of the ash hopper is connected to the lower end of the weighing elastic member through the bearing plate. The upper end of the weighing elastic member is connected to the lower side wall at the junction of the middle vertical pipe and the lower upward inclined pipe, and a dust falling port is opened on the pipe wall of the hot air branch pipe above the opening of the ash hopper. Preferably, a conveying ash belt is further arranged below the ash discharge port at the bottom of the ash hopper.

[0010] Preferably, the weighing elastic member is a weighing spring with an elastic sealing air curtain. The material of the elastic sealing air curtain can be any non-air-permeable soft material.

[0011] Preferably, the pulverized coal injection pipe includes a main pulverized coal pipe and pulverized coal branch pipes. The main pulverized coal pipe is communicated with the upper downward inclined pipe through the pulverized coal branch pipes, and a pulverized coal injection valve is arranged on the pulverized coal branch pipes. Preferably, the pulverized coal branch pipes intersect the upper downward inclined pipe obliquely, and the inclined direction of the pulverized coal branch pipes is opposite to that of the upper downward inclined pipe, that is, the injection direction of the pulverized coal is opposite to the hot air flow direction.

[0012] Preferably, the main pulverized coal pipe is communicated with the upper downward inclined pipe through multiple pulverized coal branch pipes with pulverized coal injection valves. Preferably, multiple pulverized coal branch pipes with pulverized coal injection valves are uniformly distributed along the circumference of the upper downward inclined pipe in a spiral winding manner.

[0013] Preferably, the heating ignition device is an arc heating electrode, which includes an arc positive electrode rod and an arc negative electrode rod. The arc positive electrode rod and the arc negative electrode rod are oppositely arranged on the pipe wall of the middle vertical pipe.

[0014] Preferably, multiple pairs of arc positive electrode rods and arc negative electrode rods are arranged on the pipe wall of the middle vertical pipe from top to bottom.

[0015] Preferably, the system further includes a partition mechanism, which includes an upper partition plate and a lower partition plate. The upper partition plate is vertically arranged on the upper inner wall of the lower upward inclined pipe cavity by an upper plate driving motor, and the lower partition plate is vertically arranged on the lower inner wall of the lower upward inclined pipe cavity by a lower plate driving motor. The vertical heights of the upper partition plate and the lower partition plate are respectively driven by the upper plate driving motor and the lower plate driving motor. In the axial direction of the lower upward inclined pipe, the upper partition plate and the lower partition plate are alternately arranged at intervals.

[0016] Preferably, a gas injection pipe is further connected to the upper downward inclined pipe.

[0017] Preferably, a steam injection pipe is further connected to the upper downward inclined pipe.

[0018] Preferably, along the width direction of the material flow, a plurality of temperature measuring elements are arranged in the hot air hood above the roasting section.

[0019] Preferably, along the width direction of the material flow, a pair of hot air branch pipes are symmetrically arranged on both sides of the hot air hood above the roasting section. Preferably, along the length direction of the material flow, multiple pairs of hot air branch pipes are arranged on both sides of the hot air hood above the roasting section.

[0020] 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. Cooling fans are connected to the bottom air inlets of both the first cooling section and the second cooling section. The top air outlet of the first cooling section is connected to the main hot air pipe. The top air outlet of the second cooling section is connected to the bottom air inlet of the drum drying section through a first hot air pipe. A second hot air pipe is also led out from the main hot air pipe and connected to the top air inlet of the preheating section. The bottom air outlet of the roasting section is connected to the top air inlet of the suction drying section through a third hot air pipe. 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 to exhaust air pipes.

[0021] In the present utility model, the cooling air for cooling the calcined materials is blown in by a blower, exchanges heat with the high-temperature materials in the cooling section, and the hot air after heat exchange enters the roasting section through the secondary air inlet mechanism (hot air main pipe and hot air branch pipes) arranged above the roasting section to serve as combustion-supporting air for the roasting heating system; during this process, according to the needs of the actual working conditions, pulverized coal is injected into the hot air branch pipes and ignited by a heating 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 changing the vertical height of the hot air branch pipes, a place is provided for the injection and combustion of pulverized coal, enabling pulverized coal to replace high-quality gas as the roasting heating fuel without the need to additionally install a combustion chamber or occupy extra space, significantly reducing the production cost. Moreover, compared with high-quality gas that 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 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.

[0022] In the present utility model, the idle space above the belt roasting device is utilized to increase the height of the traditional hot air branch pipes. That is, the hot air branch pipes include an upper downward inclined pipe communicating with the hot air main pipe, a middle vertical pipe, and a lower upward inclined pipe communicating with the inner cavity of the roasting section. A pulverized coal injection pipe (composed of a pulverized coal main pipe, pulverized coal branch pipes, and pulverized coal injection valves, etc.) is added to the upper downward inclined pipe, and its function is to inject pulverized coal into the pipe section of the upper downward inclined pipe so that the pulverized coal is mixed with the secondary hot air and descends uniformly. It should be noted that there is a preferred scheme for the layout of the pulverized coal injection pipe here, that is, multiple pulverized coal branch pipes are evenly distributed in a circumferential spiral around the upper downward inclined 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 enhanced, preventing the occurrence of uneven pulverized coal concentration and laying a foundation for the subsequent rapid and complete combustion of pulverized coal.

[0023] In the present utility model, the increase in the height of the traditional hot air branch pipe is mainly reflected in increasing the height of the middle vertical pipe, and a heating and ignition device is added to the middle vertical pipe. That is, the uniformly mixed coal-air mixed fluid is heated and ignited by the heating and ignition device, so that the pulverized coal can be quickly burned out in the middle vertical pipe, thereby significantly increasing the air temperature of the secondary hot air, ensuring the uniformity of the temperature in the roasting section, and helping to improve and guarantee the quality of the roasted products. In a preferred embodiment, the heating and ignition device specifically includes a plurality of pairs of AC arc electrodes symmetrically arranged from top to bottom on the middle vertical pipe. Each pair of electrodes consists of an arc positive electrode rod and an arc negative electrode rod. Its function is to form a breakdown arc between the positive and negative electrode rods to form a local high temperature, so as to ignite the pulverized coal flow beam walking between the electrode rods, so that the pulverized coal can flow downward in the vertical pipe section while burning rapidly.

[0024] In the present utility model, a coal ash collection and weighing mechanism is added at the bottom of the hot air branch pipe (specifically, at the junction of the bottom end of the middle vertical pipe and the bottom end of the lower upward inclined pipe) to prevent pulverized coal from entering the roasting material layer. Since the silicon content of the coal ash is relatively high, it is easy to cause the agglomeration of pellet ore. The coal ash collection and weighing mechanism consists of an ash collection hopper, a bearing plate, a weighing elastic member, etc. Among them, the upper end of the weighing elastic member is fixed on the bottom of the hot air branch pipe, its lower end is connected to one end of the bearing plate, and the other end of the bearing plate is connected to the weighing hopper. The purpose is to accumulate and weigh the coal ash burned out in the middle vertical pipe under the action of gravity here, so as to judge whether there is an abnormal condition that coal ash enters the hot air hood in the roasting section or there is unburned pulverized coal. It should be noted that the weighing elastic member is a weighing spring with an elastic airtight partition curtain. The material of the elastic airtight partition 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.

[0025] In the present utility model, the bottom end of the middle vertical pipe is designed to be lower than the height of the air inlet of the hot air hood in the roasting section, and it is connected to the air inlet of the hot air hood in the roasting section through a lower upward inclined pipe; a labyrinth partition mechanism is also added in the lower upward inclined pipe arranged obliquely upward. It consists of an upper partition board, an upper board driving motor, a lower partition board and 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 pulverized coal flow (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 carried in the secondary hot air reaching the bottom and continuing to flow to the roasting section through the lower upward inclined pipe under the action of the partition board, and make the blocked pulverized coal and coal ash settle to the lower coal ash weighing hopper under the action of natural gravity.

[0026] In the present utility model, a plurality of temperature measuring elements are further 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 unburned pulverized coal has entered the roasting chamber and continues to burn.

[0027] In the present utility model, when the system described in the present utility model is used 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 multiple working conditions 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:

[0028] W mf =W qt ×C qt ×(T1 - T0)÷Q mf (1)

[0029] In formula (1), W qt is the mass of pellets flowing through the roasting section per unit time (i.e., the total mass of pellets that need to be heated in the roasting section per unit time), Kg. C qt is the specific heat capacity of pellets, KJ / (kg·°C). T1 is the temperature to which the pellets in the roasting section need to be heated, °C. T0 is the initial temperature of the pellets in the roasting section, °C. Q mf is the calorific value of pulverized coal, KJ / Kg.

[0030] Furthermore, when the amount of pulverized coal injected through the pulverized coal injection pipeline per unit time is W mf : the system automatically controls the opening degree of the pulverized coal injection valve according to this calculated value. At the same time, according to the pulverized coal injection value, the vertical height range of the vertical pipe section in the middle where the arc needs to be ignited, and the coal ash generation value, etc. are calculated. For example, if the height at which the heating ignition device heats the hot air branch pipe is set as L, m. The generated mass of coal ash is W mh , Kg. Then there is:

[0031] L = W mf ×λ×V×d (2)

[0032] W mh =W mf ×η (3)

[0033] In formulas (2)-(3), λ is the height correction coefficient, and its value is 8.2 - 14.9 (preferably 9 - 12.5). V is the hot air flow velocity entering the roasting section, m / s. d is the particle size of pulverized coal, m. η is the coal ash generation coefficient, and its value is 0.005 - 0.05.

[0034] It should be noted that the system activates the corresponding arc elements according to the calculation results of formulas (2)-(3). For example, if the calculated height L requires activating 6 pairs of AC arc electrodes, then 6 pairs of AC arc electrodes are activated. After that, the system will detect whether the weight of the coal ash measured in the ash discharge hopper is equal to the calculated coal ash generation value W mh If they are equal, this adjustment ends; if not, it enters the feedback adjustment link. In the feedback adjustment link, 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 uniform: If so, it indicates that the pulverized coal has been burned out in the middle vertical pipe, 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 (upper partition plate and 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 uniform, it indicates that the pulverized coal has not been burned out in the middle vertical pipe and there is still secondary combustion after entering the roasting section. At this time, the system will send a signal to the heating ignition device to extend the distance range of the ignition arc area on the middle vertical pipe (that is, 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 discharge hopper and compare it with the calculated coal ash generation value. If they are still not equal, the steps of this link will be repeated until they are equal. If they are equal, the system defaults that this adjustment ends.

[0035] It should be noted that all the formulas in the present invention are obtained by the inventor through fitting based on experiments and engineering applications. All calculations are based on the values after converting to the specified units. The values after converting the units are substituted into the formulas for calculation (after converting the units, only the values are substituted into the formulas for calculation, without substituting the units. The units are only used to adjust the magnitudes of the values).

[0036] In the present invention, a gas injection device (a gas injection pipe with a control regulating valve) is additionally provided on the upper descending inclined pipe of the hot air branch pipe. Its function is to provide auxiliary gas combustion when the pulverized coal injection amount cannot be increased, and to provide qualified high-temperature secondary hot air for the roasting section.

[0037] In the present invention, a steam injection device (a steam injection pipe with a control regulating valve) is additionally provided on the upper descending inclined pipe of the hot air branch pipe. Its function is to provide auxiliary steam injection when both the pulverized coal injection amount and the gas injection amount cannot be increased and the pulverized coal is difficult to burn out, so that it reacts with the pulverized coal to produce the water gas reaction, enhancing the burnout rate of the pulverized coal and providing qualified high-temperature secondary hot air for the roasting section.

[0038] In the present invention, the system of the present invention has a function associated with an external automatic control and adjustment mechanism, and realizes the automatic and precise control and adjustment of this system through the automatic control and adjustment mechanism, thereby ensuring the stability and safety of the system operation.

[0039] In the present utility model, in a preferred embodiment, the diameter of the main hot air pipe is 5 - 300 cm, preferably 8 - 200 cm, and more preferably 10 - 100 cm. The diameter of the branch hot air pipe is 1 - 200 cm, preferably 3 - 150 cm, and more preferably 5 - 80 cm. The diameter of the pulverized coal injection pipe is 5 - 100 cm, preferably 8 - 80 cm, and more preferably 10 - 50 cm. The height of the vertical section of the branch hot air pipe is 0.3 - 10 m, preferably 0.8 - 8 m, and more preferably 1 - 5 m. The thickness of the hot air hood is 0.1 - 80 cm, preferably 0.5 - 50 cm, and more preferably 1 - 30 cm.

[0040] Compared with the prior art, the beneficial technical effects of the present utility model are as follows:

[0041] 1: The belt roasting system of the present utility model can implement heat supply roasting using inexpensive pulverized coal, which conforms to the characteristics of rich coal in China, that is, by applying the inexpensive resource coal, the process cost of the entire pellet production of the belt roaster is effectively reduced; in addition, due to the wide distribution of pulverized coal and the convenience of transportation and storage, the suitability and adaptability of the roasting process are greatly improved.

[0042] 2: The belt roasting system of the present utility model can be implemented without occupying additional space, and has low investment and operation costs, a simple overall structure, and stable and reliable operation, and has excellent practical application value in the future market. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic structural diagram of the belt roasting device of the system described in the present utility model.

[0044] Figure 2 It is a schematic cross-sectional structure diagram of the roasting section and the air-coal injection mechanism of the system described in the present utility model.

[0045] Figure 3 It is a schematic structural diagram of the pulverized coal injection pipe of the system described in the present utility model.

[0046] Figure 4 It is a schematic structural diagram of the pulverized coal injection pipe of the present utility model when there are multiple pulverized coal branch pipes.

[0047] Figure 5 It is a schematic cross-sectional structure diagram of the pulverized coal injection pipe of the present utility model when there are multiple pulverized coal branch pipes.

[0048] Figure 6 It is a schematic structure and distribution diagram of the heating ignition device of the present utility model.

[0049] Figure 7 It is a schematic structural diagram of the coal ash collection and weighing mechanism of the present utility model.

[0050] Figure 8 This is a schematic structural diagram of the partition mechanism of the present utility model.

[0051] Reference numerals: 1: drying section; 101: drum drying section; 102: extraction drying section; 2: preheating section; 3: roasting section; 4: cooling section; 401: first cooling section; 402: second cooling section; 5: hot air hood; 6: hot air main pipe; 7: hot air branch pipe; 701: upper downward inclined pipe; 702: middle vertical pipe; 703: lower upward inclined pipe; 8: pulverized coal injection pipe; 801: pulverized coal main pipe; 802: pulverized coal branch pipe; 803: pulverized coal injection valve; 9: heating ignition device; 901: arc positive electrode rod; 902: arc negative electrode rod; 10: coal ash collection and weighing mechanism; 1001: ash hopper; 1002: bearing plate; 1003: weighing elastic member; 1004: ash conveying belt; 11: partition mechanism; 1101: upper partition board; 1102: lower partition board; 1103: upper plate driving motor; 1104: lower plate driving motor; 12: gas injection pipe; 13: steam injection pipe; 14: temperature measuring element; L1: first hot air pipe; L2: second hot air pipe; L3: third hot air pipe. Specific embodiments

[0052] The technical solutions of the present utility model will be illustrated below. The scope of protection claimed by the present utility model includes but is not limited to the following embodiments.

[0053] A belt roasting system for pulverized coal coupled with hot air direct heating, the system comprising a belt roasting machine and a coal and air injection mechanism. According to the material flow direction, the belt roasting machine includes a drying section 1, a preheating section 2, a roasting section 3, a cooling section 4 connected in series in sequence, and a hot air hood 5 covering above each section. The coal and air injection mechanism includes a hot air main pipe 6, a hot air branch pipe 7, and a pulverized coal injection pipe 8.

[0054] The air inlet end of the hot air main pipe 6 is connected to the top air outlet of the cooling section 4, and its air outlet end extends above the hot air hood 5 at the roasting section 3. The hot air branch pipe 7 is arranged vertically as a whole. Its upper end is connected to the air exhaust end of the hot air main pipe 6, and its lower end extends downward and is connected to the air inlet of the hot air hood 5 above the roasting section 3. The pulverized coal injection pipe 8 is connected to the upper part of the hot air branch pipe 7, and a heating ignition device 9 is arranged in the middle of the hot air branch pipe 7.

[0055] Preferably, the hot air branch pipe 7 includes an upper downward inclined pipe 701, a middle vertical pipe 702, and a lower upward inclined pipe 703. The top end of the upper downward inclined pipe 701 is communicated with the hot air main pipe 6, and its bottom end extends downward obliquely and is communicated with the top end of the middle vertical pipe 702. The bottom end of the lower upward inclined pipe 703 is communicated with the bottom end of the middle vertical pipe 702, and its top end extends upward obliquely and is communicated with the side air inlet of the hot air hood 5 above the roasting section 3. The pulverized coal injection pipe 8 is communicated with the upper downward inclined pipe 701, and the heating ignition device 9 is arranged on the middle vertical pipe 702.

[0056] Preferably, the system further includes a coal ash collection and weighing mechanism 10, and the coal ash collection and weighing mechanism 10 includes an ash hopper 1001, a bearing plate 1002, and a weighing elastic member 1003. The upper end of the ash hopper 1001 is connected to the lower end of the weighing elastic member 1003 through the bearing plate 1002, the upper end of the weighing elastic member 1003 is connected to the lower side wall of the junction of the middle vertical pipe 702 and the lower upward inclined pipe 703, and a dust falling port is opened on the pipe wall of the hot air branch pipe 7 above the opening of the ash hopper 1001. Preferably, a conveying ash belt 1004 is further arranged below the ash discharge port at the bottom of the ash hopper 1001.

[0057] Preferably, the weighing elastic member 1003 is a weighing spring with an elastic sealing air curtain.

[0058] Preferably, the pulverized coal injection pipe 8 includes a pulverized coal main pipe 801 and pulverized coal branch pipes 802. The pulverized coal main pipe 801 is communicated with the upper downward inclined pipe 701 through the pulverized coal branch pipes 802, and a pulverized coal injection valve 803 is arranged on the pulverized coal branch pipe 802. Preferably, the pulverized coal branch pipe 802 intersects with the upper downward inclined pipe 701 obliquely and the inclination direction of the pulverized coal branch pipe 802 is opposite to the inclination direction of the upper downward inclined pipe 701, that is, the injection direction of the pulverized coal is opposite to the hot air flow direction.

[0059] Preferably, the pulverized coal main pipe 801 is communicated with the upper downward inclined pipe 701 through multiple pulverized coal branch pipes 802 with pulverized coal injection valves 803. Preferably, multiple pulverized coal branch pipes 802 with pulverized coal injection valves 803 are uniformly distributed along the circumferential direction of the upper downward inclined pipe 701 in a spiral surrounding manner.

[0060] Preferably, the heating ignition device 9 is an arc heating electrode, including an arc positive electrode rod 901 and an arc negative electrode rod 902, and the arc positive electrode rod 901 and the arc negative electrode rod 902 are oppositely arranged on the pipe wall of the middle vertical pipe 702.

[0061] Preferably, multiple pairs of arc positive electrode rods 901 and arc negative electrode rods 902 are arranged on the pipe wall of the middle vertical pipe 702 from top to bottom.

[0062] Preferably, the system further includes a partition mechanism 11, and the partition mechanism 11 includes an upper partition plate 1101 and a lower partition plate 1102. The upper partition plate 1101 is vertically arranged on the upper inner wall of the lumen of the lower upward inclined pipe 703 by an upper plate driving motor 1103, and the lower partition plate 1102 is vertically arranged on the lower inner wall of the lumen of the lower upward inclined pipe 703 by a lower plate driving motor 1104. The vertical heights of the upper partition plate 1101 and the lower partition plate 1102 are respectively driven by the upper plate driving motor 1103 and the lower plate driving motor 1104. In the axial direction of the lower upward inclined pipe 703, the upper partition plate 1101 and the lower partition plate 1102 are sequentially arranged at staggered intervals.

[0063] Preferably, a gas injection pipe 12 is further connected to the upper downward inclined pipe 701.

[0064] Preferably, a water vapor injection pipe 13 is further connected to the upper downward inclined pipe 701.

[0065] Preferably, along the width direction of the material flow, a plurality of temperature measuring elements 14 are arranged in the hot air hood 5 above the roasting section 3.

[0066] Preferably, along the width direction of the material flow, a pair of hot air branch pipes 7 are symmetrically arranged on both sides of the hot air hood 5 above the roasting section 3. Preferably, along the length direction of the material flow, a plurality of pairs of hot air branch pipes 7 are arranged on both sides of the hot air hood 5 above the roasting section 3.

[0067] Preferably, the drying section 1 includes a drum drying section 101 and a suction drying section 102. The cooling section 4 includes a first cooling section 401 and a second cooling section 402. Cooling air inlets at the bottoms of the first cooling section 401 and the second cooling section 402 are both connected with cooling fans. The top air outlet of the first cooling section 401 is connected to the hot air main pipe 6. The top air outlet of the second cooling section 402 is connected to the bottom air inlet of the drum drying section 101 through a first hot air pipe L1. A second hot air pipe L2 is also led out from the hot air main pipe 6 and connected to the top air inlet of the preheating section 2. The bottom air outlet of the roasting section 3 is connected to the top air inlet of the suction drying section 102 through a third hot air pipe L3. The top air outlets of the drum drying section 101, the bottom air outlets of the suction drying section 102, and the bottom air outlets of the preheating section 2 are all connected with exhaust air pipes.

[0068] Example 1

[0069] As Figure 1-8As shown in the figure, a belt roasting system for direct heating with pulverized coal coupled with hot air includes a belt roaster and a coal and air injection mechanism. According to the material flow direction, the belt roaster includes a drying section 1, a preheating section 2, a roasting section 3, a cooling section 4 connected in series in sequence, and a hot air hood 5 covering above each section. The coal and air injection mechanism includes a hot air main pipe 6, a hot air branch pipe 7, and a pulverized coal injection pipe 8.

[0070] The air inlet end of the hot air main pipe 6 is connected to the top air outlet of the cooling section 4, and its air outlet end extends above the hot air hood 5 at the roasting section 3. The hot air branch pipe 7 is integrally arranged vertically. Its upper end is connected to the air exhaust end of the hot air main pipe 6, and its lower end extends downward and is connected to the air inlet of the hot air hood 5 above the roasting section 3. The pulverized coal injection pipe 8 is connected to the upper part of the hot air branch pipe 7, and a heating and ignition device 9 is arranged in the middle of the hot air branch pipe 7.

[0071] Example 2

[0072] Repeat Example 1, except that the hot air branch pipe 7 includes an upper downward inclined pipe 701, a middle vertical pipe 702, and a lower upward inclined pipe 703. The top end of the upper downward inclined pipe 701 is communicated with the hot air main pipe 6, and its bottom end extends downward obliquely and is communicated with the top end of the middle vertical pipe 702. The bottom end of the lower upward inclined pipe 703 is communicated with the bottom end of the middle vertical pipe 702, and its top end extends upward obliquely and is communicated with the side air inlet of the hot air hood 5 above the roasting section 3. The pulverized coal injection pipe 8 is communicated with the upper downward inclined pipe 701, and the heating and ignition device 9 is arranged on the middle vertical pipe 702.

[0073] Example 3

[0074] Repeat Example 2, except that the system further includes a coal ash collection and weighing mechanism 10. The coal ash collection and weighing mechanism 10 includes an ash hopper 1001, a bearing plate 1002, and a weighing elastic member 1003. The upper end of the ash hopper 1001 is connected to the lower end of the weighing elastic member 1003 through the bearing plate 1002. The upper end of the weighing elastic member 1003 is connected to the lower side wall of the intersection of the middle vertical pipe 702 and the lower upward inclined pipe 703, and an ash falling port is opened on the pipe wall of the hot air branch pipe 7 above the opening of the ash hopper 1001.

[0075] Example 4

[0076] Repeat Example 3, except that a conveying belt 1004 is further arranged below the ash discharge port at the bottom of the ash hopper 1001.

[0077] Example 5

[0078] Repeat Example 4, except that the weighing elastic member 1003 is a weighing spring with an elastic sealing air curtain.

[0079] Example 6

[0080] Repeat Example 5, except that the pulverized coal injection pipeline 8 includes a pulverized coal main pipe 801 and pulverized coal branch pipes 802. The pulverized coal main pipe 801 is connected to the upper downward inclined pipe 701 through the pulverized coal branch pipes 802, and a pulverized coal injection valve 803 is provided on the pulverized coal branch pipe 802. Preferably, the pulverized coal branch pipe 802 intersects the upper downward inclined pipe 701 obliquely, and the inclined direction of the pulverized coal branch pipe 802 is opposite to the inclined direction of the upper downward inclined pipe 701, that is, the injection direction of the pulverized coal is opposite to the hot air flow direction.

[0081] Example 7

[0082] Repeat Example 6, except that the pulverized coal main pipe 801 is connected to the upper downward inclined pipe 701 through multiple pulverized coal branch pipes 802 with pulverized coal injection valves 803. Preferably, the multiple pulverized coal branch pipes 802 with pulverized coal injection valves 803 are uniformly distributed along the circumferential direction of the upper downward inclined pipe 701 in a spiral winding manner.

[0083] Example 8

[0084] Repeat Example 7, except that the heating and ignition device 9 is an arc heating electrode, including an arc positive electrode rod 901 and an arc negative electrode rod 902, and the arc positive electrode rod 901 and the arc negative electrode rod 902 are oppositely arranged on the pipe wall of the middle vertical pipe 702.

[0085] Example 9

[0086] Repeat Example 8, except that multiple pairs of arc positive electrode rods 901 and arc negative electrode rods 902 are arranged on the pipe wall of the middle vertical pipe 702 from top to bottom.

[0087] Example 10

[0088] Repeat Example 9, except that the system further includes a partition mechanism 11, and the partition mechanism 11 includes an upper partition board 1101 and a lower partition board 1102. The upper partition board 1101 is vertically arranged on the upper inner wall of the lower upward inclined pipe 703 through an upper plate driving motor 1103, and the lower partition board 1102 is vertically arranged on the lower inner wall of the lower upward inclined pipe 703 through a lower plate driving motor 1104. The vertical heights of the upper partition board 1101 and the lower partition board 1102 are respectively driven by the upper plate driving motor 1103 and the lower plate driving motor 1104. In the axial direction of the lower upward inclined pipe 703, the upper partition board 1101 and the lower partition board 1102 are alternately and spaced apart.

[0089] Example 11

[0090] Repeat Example 10, except that a gas injection pipeline 12 is further connected to the upper downward inclined pipe 701.

[0091] Example 12

[0092] Repeat Example 11, except that a steam injection pipe 13 is also connected to the upper downward inclined pipe 701.

[0093] Example 13

[0094] Repeat Example 12, except that along the width direction of the material flow, a number of temperature measuring elements 14 are arranged in the hot air hood 5 above the roasting section 3.

[0095] Example 14

[0096] Repeat Example 13, except that along the width direction of the material flow, a pair of hot air branch pipes 7 are symmetrically arranged on both sides of the hot air hood 5 above the roasting section 3.

[0097] Example 15

[0098] Repeat Example 14, except that along the length direction of the material flow, multiple pairs of hot air branch pipes 7 are arranged on both sides of the hot air hood 5 above the roasting section 3.

[0099] Example 16

[0100] Repeat Example 15, except that the drying section 1 includes a drum drying section 101 and a suction drying section 102. The cooling section 4 includes a first cooling section 401 and a second cooling section 402. Cooling air inlets at the bottoms of the first cooling section 401 and the second cooling section 402 are both connected to cooling fans. The top air outlet of the first cooling section 401 is connected to the hot air main pipe 6. The top air outlet of the second cooling section 402 is connected to the bottom air inlet of the drum drying section 101 through a first hot air pipe L1. A second hot air pipe L2 is also led out from the hot air main pipe 6 and connected to the top air inlet of the preheating section 2. The bottom air outlet of the roasting section 3 is connected to the top air inlet of the suction drying section 102 through a third hot air pipe L3. The top air outlets of the drum drying section 101, the bottom air outlets of the suction drying section 102, and the bottom air outlets of the preheating section 2 are all connected to exhaust air pipes.

Claims

1. A belt roasting system for pulverized coal coupled with hot air direct current heating, characterized in that: The system includes a traveling grate and an air-coal injection mechanism; according to the material flow direction, the traveling grate includes a drying section (1), a preheating section (2), a roasting section (3), a cooling section (4) connected in series in sequence, and a hot air hood (5) covering above each section; the air-coal injection mechanism includes a main hot air pipe (6), a hot air branch pipe (7), and a pulverized coal injection pipeline (8). The air inlet end of the main hot air pipe (6) is connected to the top air outlet of the cooling section (4), and its air outlet end extends above the hot air hood (5) at the roasting section (3); the hot air branch pipe (7) is integrally arranged vertically, its upper end is connected to the exhaust end of the main hot air pipe (6), and its lower end extends downward and is connected to the air inlet of the hot air hood (5) above the roasting section (3); the pulverized coal injection pipeline (8) is connected to the upper part of the hot air branch pipe (7), and a heating and ignition device (9) is arranged in the middle of the hot air branch pipe (7).

2. The system according to claim 1, characterized in that: The hot air branch pipe (7) includes an upper downward inclined pipe (701), a middle vertical pipe (702), and a lower upward inclined pipe (703); the top end of the upper downward inclined pipe (701) is communicated with the main hot air pipe (6), and its bottom end extends downward obliquely and is communicated with the top end of the middle vertical pipe (702); the bottom end of the lower upward inclined pipe (703) is communicated with the bottom end of the middle vertical pipe (702), and its top end extends upward obliquely and is communicated with the side air inlet of the hot air hood (5) above the roasting section (3); the pulverized coal injection pipeline (8) is communicated with the upper downward inclined pipe (701), and the heating and ignition device (9) is arranged on the middle vertical pipe (702).

3. The system according to claim 2, characterized in that: The system also includes a coal ash collection and weighing mechanism (10), and the coal ash collection and weighing mechanism (10) includes an ash hopper (1001), a bearing plate (1002), and a weighing elastic member (1003); the upper end of the ash hopper (1001) is connected to the lower end of the weighing elastic member (1003) through the bearing plate (1002), the upper end of the weighing elastic member (1003) is connected to the lower side wall of the intersection of the middle vertical pipe (702) and the lower upward inclined pipe (703), and an ash falling port is opened on the pipe wall of the hot air branch pipe (7) above the opening of the ash hopper (1001).

4. The system according to claim 3, characterized in that: A dust conveying belt (1004) is also arranged below the ash discharge port at the bottom of the ash hopper (1001).

5. The system according to claim 3, wherein: The weighing elastic member (1003) is a weighing spring with an elastic sealing air isolation curtain.

6. The system according to claim 2, wherein: The pulverized coal injection pipeline (8) includes a pulverized coal main pipe (801) and pulverized coal branch pipes (802); the pulverized coal main pipe (801) is communicated with the upper downward inclined pipe (701) through the pulverized coal branch pipes (802), and a pulverized coal injection valve (803) is arranged on the pulverized coal branch pipes (802).

7. The system according to claim 6, wherein: The pulverized coal branch pipe (802) intersects with the upper downward inclined pipe (701) obliquely, and the inclination direction of the pulverized coal branch pipe (802) is opposite to that of the upper downward inclined pipe (701), that is, the pulverized coal injection direction is opposite to the hot air flow direction.

8. The system according to claim 6, wherein: The pulverized coal main pipe (801) is communicated with the upper downward inclined pipe (701) through multiple pulverized coal branch pipes (802) with pulverized coal injection valves (803).

9. The system according to claim 8, wherein: A plurality of pulverized coal branch pipes (802) with pulverized coal injection valves (803) are uniformly distributed along the circumferential direction of the upper descending inclined pipe (701) in a spiral winding manner.

10. The system according to claim 2, wherein: The heating and ignition device (9) is an arc heating electrode, including an arc positive electrode rod (901) and an arc negative electrode rod (902). The arc positive electrode rod (901) and the arc negative electrode rod (902) are oppositely arranged on the pipe wall of the middle vertical pipe (702).

11. The system according to claim 10, wherein: A plurality of pairs of arc positive electrode rods (901) and arc negative electrode rods (902) are arranged on the pipe wall of the middle vertical pipe (702) from top to bottom.

12. The system according to claim 2, wherein: The system further includes a partition mechanism (11). The partition mechanism (11) includes an upper partition plate (1101) and a lower partition plate (1102). The upper partition plate (1101) is vertically arranged on the upper inner wall of the cavity of the lower ascending inclined pipe (703) through an upper plate driving motor (1103), and the lower partition plate (1102) is vertically arranged on the lower inner wall of the cavity of the lower ascending inclined pipe (703) through a lower plate driving motor (1104). The vertical heights of the upper partition plate (1101) and the lower partition plate (1102) are respectively driven by the upper plate driving motor (1103) and the lower plate driving motor (1104). In the axial direction of the lower ascending inclined pipe (703), the upper partition plate (1101) and the lower partition plate (1102) are alternately arranged at intervals.

13. The system according to any one of claims 2-12, characterized in that: A gas injection pipe (12) is further connected to the upper descending inclined pipe (701); and / or A steam injection pipe (13) is further connected to the upper descending inclined pipe (701).

14. The system according to any one of claims 1 to 12, characterized in that: Along the width direction of the material flow, a plurality of temperature measuring elements (14) are arranged in the hot air hood (5) above the roasting section (3).

15. The system according to any one of claims 1 to 12, characterized in that: Along the width direction of the material flow, a pair of hot air branch pipes (7) are symmetrically arranged on both sides of the hot air hood (5) above the roasting section (3).

16. The system according to claim 15, wherein: Along the length direction of the material flow, a plurality of pairs of hot air branch pipes (7) are arranged on both sides of the hot air hood (5) above the roasting section (3).

17. The system according to any one of claims 1 - 12, 16, characterized in that: The drying section (1) includes a drum drying section (101) and a suction drying section (102); the cooling section (4) includes a first cooling section (401) and a second cooling section (402). Cooling air inlets at the bottoms of the first cooling section (401) and the second cooling section (402) are both connected with cooling fans. The top air outlet of the first cooling section (401) is connected to the hot air main pipe (6). The top air outlet of the second cooling section (402) is connected to the bottom air inlet of the drum drying section (101) through a first hot air pipe (L1). A second hot air pipe (L2) is also led out from the hot air main pipe (6) and connected to the top air inlet of the preheating section (2). The bottom air outlet of the roasting section (3) is connected to the top air inlet of the suction drying section (102) through a third hot air pipe (L3). The top air outlets of the drum drying section (101), the bottom air outlets of the suction drying section (102), and the bottom air outlets of the preheating section (2) are all connected with external exhaust air pipes.

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