Method and system for roasting by adopting electric hot air

Abstract

According to the method and system for roasting through the electric hot air, metal oxide pellet materials are conveyed to an oxidizing roasting device, air is heated through an electric heat storage device, and the hot air is obtained; and hot air is conveyed to an oxidizing roasting device, in the oxidizing roasting device, the metal oxide pellet materials are roasted through the hot air, and oxidized pellets are obtained. Stable fluctuation-free hot air is prepared through green electricity, then the metal oxide pellet materials are subjected to oxidizing roasting through high-temperature hot air, and pellets are obtained. According to the method and the system provided by the invention, the replacement of fossil energy by green electricity is realized, the consumption of fossil energy such as coal and natural gas is avoided, the emission of pollutants is reduced, and the zero emission of carbon is realized.

Description

Technical Field

[0001] The invention relates to a method and system for roasting oxidized pellets, and in particular to a method and system for roasting oxidized pellets by using hot air, and belongs to the technical field of pellet ore metallurgy. Background Art

[0002] In the steelmaking process, pelletizing is a key core link, and its role is to provide high-quality low-sulfur pellets for ironmaking blast furnaces / hydrogen-based shaft furnaces. As the country's requirements for energy conservation and emission reduction in the steel industry, especially dual carbon, continue to increase, pellets will occupy an increasingly large market share in the future. Both short-process hydrogen-based shaft furnaces and long-process blast furnaces will require a large supply of pellets.

[0003] The pelletizing process is roughly divided into seven steps from beginning to end, namely batching - mixing - pelletizing - laying - roasting - cooling. The roasting step is to roast the pelletized ore after laying at high temperature to produce a liquid phase with a certain strength, and at the same time discharge the pollutants such as sulfur contained in it from the flue gas. Its operation quality directly affects the quality indicators of the entire pelletizing process.

[0004] The schematic diagram of the existing pellet roasting process is as follows: Figure 1-Figure 3 As shown: After being dried and preheated, the green balls are transported to the roasting hood or rotary kiln through a trolley or distributor. Figure 1 The method is top-burning roasting, that is, a burner 2 is arranged on the top of the roasting hood 1 to directly roast the pellets in the lower part of the hood. Figure 2 The method is side-fired roasting, that is, a burner 2 is arranged on the side of the roasting hood 1, and the high-temperature flue gas generated by the burner is used to roast the pellets in the hood. Figure 3 The method is rotary roasting, that is, a burner 2 is arranged at one end of a rotary kiln 3 of a rotary device to roast the pelletized mineral material which is constantly turned in the kiln.

[0005] Compared with the future low-carbon and green dual-carbon requirements, the current pellet roasting process technology has the following three major defects:

[0006] 1. The energy system needs to be innovated: At present, my country's pellet energy system is mainly based on fossil fuels, especially anthracite, coke oven gas, and coke-high mixed gas. The carbon emissions generated by the combustion of these fuels are huge, and the low oxygen content in the flue gas is not conducive to the oxidation roasting of pellets. Under the dual background of the dual carbon strategy requirements and the gradual maturity of green electricity technologies such as wind power generation and solar energy in some regions, the energy system for pellet roasting urgently needs to be upgraded to clean green electricity energy systems such as wind power and solar energy;

[0007] 2. The heating method needs to be innovated: At present, the heating method for pellet roasting in my country is usually direct heat exchange, that is, the burner flame directly performs high-temperature heat exchange on the pellet to be roasted. This heating method is easy to cause uneven heating of the pellets, uneven roasting quality, and local high temperature will also cause the pellets to stick together. In contrast, the indirect heat exchange of first preparing hot air and then introducing the hot air into the pellet material layer for heating and roasting will be more conducive to the roasting production of pellets;

[0008] 3. Unstable energy supply status: At present, some processes use heat storage chambers to prepare hot air for roasting pellets. Since the heat in the heat storage chamber is most sufficient right after the energy storage is completed, the temperature of the hot air prepared at this time is the highest, and the temperature of the hot air decreases as time goes by. As a result, the energy supply status of the roasted pellets on the heated side is unstable, the production efficiency is low, and the quality of the oxidized pellets obtained is unstable. Summary of the invention

[0009] In view of the technical problems of using fossil energy, direct burner combustion for heating, and unstable heating in the prior art, the present invention proposes a method and system for roasting using electric hot air, wherein the metal oxide pellet material is transported to an oxidation roasting device, and the air is heated by an electric heat storage device to obtain hot air; the hot air is transported to an oxidation roasting device, and the metal oxide pellet material is roasted by the hot air in the oxidation roasting device to obtain oxidized pellets. Green electricity is used to prepare stable and non-fluctuating hot air, and then the metal oxide pellet material is oxidatively roasted using high-temperature hot air to obtain pellet ore. The method and system provided by the present invention realize the replacement of fossil energy with green electricity, avoid the consumption of fossil energy such as coal and natural gas, reduce the emission of pollutants, and achieve zero carbon emission.

[0010] According to a first embodiment provided by the present invention, a method for roasting using electric hot air is provided.

[0011] A method for roasting using electric hot air, characterized in that the method comprises the following steps:

[0012] 1) transporting the metal oxide pellet material to an oxidation roasting device; using an electric heat storage device to heat the air to obtain hot air;

[0013] 2) The hot air is transported to an oxidation roasting device, in which the hot air roasts the metal oxide pellet material to obtain oxidation pellets.

[0014] Preferably, two or more groups of electric heat storage devices are connected in parallel to the oxidation roasting device.

[0015] Preferably, the device further comprises an air mixing chamber, and the hot air obtained by heating the electric heat storage device is mixed in the air mixing chamber and then transported to the oxidation roasting device.

[0016] In the present invention, the oxidation roasting device is any one of a rotary kiln, a belt roasting machine, and a vertical furnace.

[0017] Preferably, two sets of electric heat storage devices are connected in parallel to the air mixing chamber, and the method further comprises:

[0018] 3) The electric heat storage device of the first group is connected to the air mixing chamber through the first hot air duct, the electric heat storage device of the second group is connected to the air mixing chamber through the second hot air duct, and the air outlet of the air mixing chamber is connected to the oxidative roasting device through the third hot air duct;

[0019] It also includes a first air short circuit and a second air short circuit, the first air short circuit connects the air intake duct and the first hot air duct of the first group of the electric heat storage device; the second air short circuit connects the air intake duct and the second hot air duct of the second group of the electric heat storage device;

[0020] A first short-circuit control valve is provided on the first air short circuit, and a second short-circuit control valve is provided on the second air short circuit; a first flow detector, a first temperature detector, and a first flow control valve are provided on the first hot air duct; a second flow detector, a second temperature detector, and a second flow control valve are provided on the second hot air duct; the flow rate of the hot air in the first hot air duct is detected by the first flow detector, and the temperature of the hot air in the first hot air duct is detected by the first temperature detector; the flow rate of the hot air in the second hot air duct is detected by the second flow detector, and the temperature of the hot air in the second hot air duct is detected by the second temperature detector; the first short-circuit control valve, the second short-circuit control valve, the first flow control valve, and the second flow control valve are adjusted to control the temperature and air volume of the hot air mixed in the air mixing chamber and transported to the oxidation roasting device.

[0021] Preferably, the method further comprises:

[0022] 4) Detect the liquid phase temperature T required for metal oxide pellets 液相化 , ferrous content in metal oxide pellets K 亚铁 , detect the feeding amount λ per unit time in the oxidation roasting device, detect the moisture content ω of the metal oxide pellet material, calculate the temperature T of the hot air required for the metal oxide pellet material in the oxidation roasting device; calculate the hot air volume W required per unit time based on the calculated required hot air temperature T; specifically:

[0023] T=T 液相化 ×(1-K 亚铁 )×γ 亚铁 ;

[0024]

[0025] Where: γ 亚铁 is the heat release coefficient of ferrous reaction; C 热风 is the heat coefficient of hot air; θ物料 is the calcination parameter of metal oxide pellets; θ 水蒸气 is the heat coefficient required for water evaporation.

[0026] Preferably, the method further comprises:

[0027] 5) closing the first flow control valve and the second flow control valve; closing the second group of electric heat storage devices and the first short-circuit control valve; introducing air into the first group of electric heat storage devices and opening the first group of electric heat storage devices;

[0028] 6) The electric heat storage device of the first group heats the air to obtain heat-saturated hot air I; the electric heat storage device of the first group and the first short-circuit control valve are closed, and cold air is introduced into the electric heat storage device of the second group and the electric heat storage device of the second group is opened; at the same time: the first flow control valve, the second flow control valve, and the second short-circuit control valve are opened; the hot air I is mixed with the cold air input through the second air short circuit in the air mixing chamber, and then enters the oxidation roasting device; the temperature of the hot air in the first hot air duct is detected by the first temperature detector, and the temperature of the cold air in the second hot air duct is detected by the second temperature detector; the opening of the first flow control valve and the second flow control valve is controlled so that:

[0029] W1+W2≥W;

[0030]

[0031] Where: W1 is the hot air delivery volume in the first hot air duct; W2 is the cold air delivery volume in the second hot air duct; T1 is the temperature of the hot air delivered in the first hot air duct; T2 is the temperature of the cold air delivered in the second hot air duct;

[0032] 7) After the hot air I in the first group of electric heat storage devices is exhausted, the second group of electric heat storage devices heats the air to obtain heat-saturated hot air II; the second group of electric heat storage devices and the second short-circuit control valve are closed, cold air is introduced into the first group of electric heat storage devices and the first group of electric heat storage devices is opened; at the same time: the second flow control valve, the first flow control valve, and the first short-circuit control valve are opened; the hot air II is mixed with the cold air input through the first air short circuit in the air mixing chamber, and then enters the oxidation roasting device; the temperature of the cold air in the first hot air duct is detected by the first temperature detector, and the temperature of the hot air in the second hot air duct is detected by the second temperature detector; the opening of the first flow control valve and the second flow control valve is controlled so that:

[0033] W1'+W2'≥W;

[0034]

[0035] Wherein: W1' is the cold air delivery volume in the first hot air duct; W2' is the hot air delivery volume in the second hot air duct; T1' is the temperature of the cold air delivered in the first hot air duct; T2' is the temperature of the hot air delivered in the second hot air duct;

[0036] 8) Repeat steps 6) and 7) to continuously deliver hot air having a temperature greater than or equal to T and a flow rate greater than or equal to W into the oxidation roasting device.

[0037] According to a second embodiment provided by the present invention, a system for roasting using electric hot air is provided.

[0038] A system for roasting using electric hot air, the system comprising an electric heat storage device and an oxidation roasting device. The air inlet of the electric heat storage device is connected to an air delivery pipeline. The air outlet of the electric heat storage device is connected to the roasting section of the oxidation roasting device.

[0039] Preferably, the system comprises two or more groups of electric heat storage devices. The system also comprises an air mixing chamber. The air outlets of the electric heat storage devices are all connected to the air mixing chamber. The air outlet of the air mixing chamber is connected to the oxidation roasting device.

[0040] Preferably, the oxidation roasting device is any one of a rotary kiln, a belt roasting machine, and a vertical furnace.

[0041] Preferably, the air outlet of the air mixing chamber is connected to the roasting section of the belt roasting machine or the vertical furnace.

[0042] Preferably, the electric heat storage device is an electric heating wire heating device, a microwave heating device, an arc heating device or a plasma heating device.

[0043] Preferably, two groups of electric heat storage devices are connected in parallel to the air mixing chamber. The electric heat storage devices of the first group are connected to the air mixing chamber through the first hot air duct. The electric heat storage devices of the second group are connected to the air mixing chamber through the second hot air duct. The air outlet of the air mixing chamber is connected to the oxidation roasting device through the third hot air duct.

[0044] Preferably, the system further comprises a first air short circuit and a second air short circuit. The first air short circuit connects the air intake duct and the first hot air duct of the first group of the electric heat storage devices. The second air short circuit connects the air intake duct and the second hot air duct of the second group of the electric heat storage devices.

[0045] Preferably, the first hot air duct is provided with a first flow detector, a first temperature detector and a first flow control valve.

[0046] Preferably, the second hot air duct is provided with a second flow detector, a second temperature detector and a second flow control valve.

[0047] Preferably, a first short-circuit control valve is provided on the first air short-circuit, and a second short-circuit control valve is provided on the second air short-circuit.

[0048] In the present invention, the liquid phase temperature of the metal oxide pellet material is required to be T 液相化 Generally, it is 1200℃-1400℃. (It is related to the metal oxide pellet material. The composition of the metal oxide pellet material is determined and can be obtained through experimental testing)

[0049] In the present invention, the ferrous content K in the metal oxide pellet material is 亚铁 Generally, it is 5%-40%. (It is related to the metal oxide pellet material. The composition of the metal oxide pellet material is determined and can be obtained through experimental testing)

[0050] In the present invention, the feeding amount per unit time of the rotary kiln is generally 150-300 t / h. (Determined according to the specifications of the rotary kiln)

[0051] In the present invention, the loading rate per unit time of the vertical furnace is generally 100-150 t / h. (Determined according to the specifications of the vertical furnace)

[0052] In the present invention, the feeding amount per unit time of the belt roasting machine is generally 200-400 t / h. (Determined according to the specifications of the belt roasting machine)

[0053] In the present invention, the water content ω of the metal oxide pellet material is generally 3%-12%. (It is related to the metal oxide pellet material, and the composition of the metal oxide pellet material is determined and can be obtained through experimental detection)

[0054] In the present invention, the ferrous reaction heat release coefficient γ 亚铁 Generally, it is 0.8-1.8, a dimensionless number. (It is related to the grade of iron ore and the composition of metal oxide pellet materials. The content of other components affects the heat release coefficient of ferrous reaction. The composition of metal oxide pellet materials is determined and can be obtained through experimental testing.)

[0055] In the present invention, the hot air specific heat coefficient C 热风 Generally 1.25-1.45 kJ / m 3 .℃. (related to the temperature and pressure of hot air)

[0056] In the present invention, the calcination parameter θ of the metal oxide pellet material is 物料 Generally, it is 500-750kJ / kg. (It is related to the metal oxide pellet material. The composition of the metal oxide pellet material is determined and can be obtained through experimental testing)

[0057] In the present invention, the heat coefficient θ required for water evaporation 水蒸气Generally it is 1500kJ / kg.

[0058] In view of the problems existing in the prior art of using fossil energy to oxidize and roast metal oxide materials, the present invention provides a roasting method using electric energy as energy. Since it is difficult to combine the electric energy device with the roasting device in the prior art and it is difficult to directly install it on the existing roasting device, the present invention proposes to heat the air with electric energy to obtain high-temperature hot air or hot wind, and then transport the hot air or hot wind to the roasting device, thus achieving a technical breakthrough in using electric energy for roasting. By using electric energy as energy, no fuel needs to be added to the metal oxide material. Since the hot air or hot wind itself contains sufficient oxygen, the metal oxide material can be directly oxidized and roasted using the hot air or hot wind.

[0059] The inventor uses electric energy to heat the air, and conveys the heated hot air or hot wind to the oxidation roasting device. After conducting experiments, it is found that the air heated by the energy storage device has large temperature fluctuations of the hot air or hot wind, which causes the technical problem that the quality of the oxidized pellets cannot be guaranteed. Since the energy storage device (electric heat storage device and gas heat storage device) itself has the process of absorbing and releasing heat, after the air passes through the energy storage device, the temperature fluctuation of the hot air or hot wind is greater than 100°C and cannot be stabilized within the same range. After the hot air or hot wind with large temperature fluctuations is conveyed to the oxidation roasting device, the metal oxide material is unstable in the oxidation roasting process, which seriously affects the metal crystallization rate and strength of the oxidized pellets. In response to this technical problem, the inventor proposes to use two or more groups of electric heat storage devices in parallel, and the two parallel groups of electric heat storage devices are connected to the air mixing chamber, and the air outlet of the air mixing chamber is then connected to the oxidation roasting device. The first group of electric heat storage devices heats the air. After heating to obtain hot air, the first group of electric heat storage devices stops running and slowly discharges the hot air; at the same time, the second group of electric heat storage devices starts running (heating the air). When the hot air in the first group of electric heat storage devices is discharged, the second group of electric heat storage devices also completes the heating of the air at the same time. At this time, the second group of electric heat storage devices stops running and slowly discharges hot air; at the same time, the first group of electric heat storage devices starts running (heating the air); and so on. In the process of the present invention, the working process of the first group of electric heat storage devices is: heating air-stop heating and discharge hot air-heating air-stop heating and discharge hot air, and so on; the working process of the second group of electric heat storage devices that operate synchronously with the first group of electric heat storage devices is: stop heating-heating air-stop heating and discharge hot air-heating air, and so on. Therefore, the first group of electric heat storage devices and the second group of electric heat storage devices work in opposite ways at the same time, heating the air and discharging the hot air at intervals, thereby achieving continuous hot air input in the air mixing chamber; at the same time, the electric heat storage devices are operated and shut down for repair, thereby ensuring the efficiency and stability of heating the air.

[0060] In the present invention, the speed at which the first group of electric heat storage devices or the second group of electric heat storage devices discharge hot air or hot air is controlled according to the amount of hot air required by the oxidation roasting device; the power of the other group of electric heat storage devices is adjusted according to the discharge speed of the electric heat storage devices that discharge hot air or hot air, so as to ensure that the heating of the air by the electric heat storage devices is synchronized with the speed at which the other group of electric heat storage devices discharge hot air. In other words, one group of electric heat storage devices is discharging hot air, and the other group of electric heat storage devices is heating the air, and the work of the two groups of electric heat storage devices is completed at the same time. After each group of electric heat storage devices has completed the discharge of hot air and the heating of air, the working processes of the two groups of electric heat storage devices are interchanged, and the electric heat storage device that has finished discharging hot air starts to heat the air, and the electric heat storage device that has finished heating the air starts to discharge hot air, and this alternation is carried out to ensure the continuity and stability of the hot air.

[0061] In the present invention, in order to stabilize the temperature stability of the hot air delivered to the oxidation roasting device, an air mixing chamber is provided to mix the hot air generated by the first group of electric heat storage devices (or the second group of electric heat storage devices) with the cold air delivered by the air short circuit next to the second group of electric heat storage devices (or the first group of electric heat storage devices). According to the temperature of the hot air and the cold air, the amount of hot air and the temperature of the hot air required by the oxidation roasting device, the control valves on each pipeline are adjusted to ensure the amount of hot air and cold air entering the air mixing chamber respectively. Through the mixing in the air mixing chamber, the temperature and amount of hot air delivered to the oxidation roasting device are ensured. In the present invention, through the provision of the air mixing chamber, according to the temperature of the hot air obtained by heating the electric heat storage device and the temperature of the hot air required by the oxidation roasting device, the temperature of the hot air obtained by heating the electric heat storage device is adjusted by delivering cold air through the air short circuit, thereby ensuring that the temperature of the hot air delivered to the oxidation roasting device is a temperature suitable for the oxidation roasting of the metal oxide material.

[0062] For the oxidation pelletizing process, the hot air volume and hot air temperature during oxidation roasting directly affect the effect of oxidation roasting, the strength of the obtained oxidation pellets, the content of trivalent iron in the oxidation pellets and the particle size of the oxidation pellets. The hot air volume and hot air temperature are stable, which can ensure that the iron oxides in the metal oxide pellet materials are fully oxidized and crystallized at the same time to form crystalline pellets, thereby ensuring the strength of the oxidation pellets. Oxidation roasting is to oxidize low-valent iron into trivalent iron as much as possible. The hot air volume and hot air temperature are stable, which can ensure that as much iron in other valence states as possible is oxidized into trivalent iron, thereby increasing the proportion of trivalent iron in the oxidation pellets and improving the iron grade of the oxidation pellets. The hot air volume and hot air temperature are unstable. The metal oxide pellet material is a spherical material that has been pelletized. Due to the uneven heating of the spherical material, the metal oxide pellet material is easily crushed, and the crushed metal oxide pellet material is more likely to be liquidized. The liquidized metal oxide pellet material is easy to cause the agglomeration of other metal oxide pellet materials, resulting in the particle size of the obtained pellets, resulting in uneven particle size of the obtained oxidized pellets, which seriously affects the subsequent process of the oxidized pellets (electric furnace or blast furnace process). The hot air volume and hot air temperature are stable, so that the metal oxide pellet material is heated evenly and stably, which can greatly reduce the bursting of the metal oxide pellet material, thereby reducing the crushing of the metal oxide pellet material, and then ensuring the uniformity of the particle size of the oxidized pellets.

[0063] In the present invention, the oxidation roasting device can be any one of the prior art, such as a rotary kiln, a belt roasting machine or a vertical furnace.

[0064] In the present invention, according to the source of the metal oxide pellet material, after mixing and pelletizing, it is transported to the oxidation roasting device. After the material is determined, the required temperature of the liquid phase of the metal oxide pellet material is determined and can be obtained through laboratory testing. The ferrous content in the metal oxide pellet material and the moisture content of the metal oxide pellet material can be obtained by detection. According to the scale of the oxidation roasting device, the loading amount of the oxidation roasting device per unit time can be determined. Through the detected data, the inventors have experimentally summarized the temperature of the hot air required for the oxidation roasting of the metal oxide pellet material in the oxidation roasting device, and the required hot air temperature T can be calculated. Then, combined with the ferrous reaction heat release coefficient, the hot air specific heat coefficient, the heat coefficient required for water evaporation, and the roasting parameters of the metal oxide pellet material, the hot air volume required for the oxidation roasting of the metal oxide pellet material in the oxidation roasting device can be calculated. The ferrous reaction heat release coefficient, the hot air specific heat coefficient, the heat coefficient required for water evaporation, and the roasting parameters of the metal oxide pellet material can all be obtained by querying data or testing.

[0065] By adopting the method of the present invention, the hot air volume and hot air temperature required for the oxidation roasting of metal oxide pellet materials in the oxidation roasting device are calculated, and according to the hot air temperature discharged by the electric heat storage device, the hot air volume discharged by the electric heat storage device and the amount of air transported by the air short-circuit next to another group of electric heat storage devices are adjusted, thereby adjusting the hot air temperature and hot air volume entering the oxidation roasting device, thereby ensuring that the metal oxide pellet materials are stably oxidized and roasted in the oxidation roasting device, thereby ensuring the quality of the oxidized pellets.

[0066] In the present invention, the electric heat storage device may be any electric heat storage device in the prior art. Specifically, a component heated by electric energy is arranged in a heat storage material (e.g., a heat storage brick), and a passage for air circulation is arranged between the heat storage materials. The heat storage material is heated by energizing the component heated by electric energy, and air passes through the heat storage material and is heated by the heat storage material to obtain hot air. The component heated by electric energy may be any one of an electric heating wire heating device, a microwave heating component, an electric arc device, and a plasma heating device.

[0067] The method provided by the present invention is used to carry out oxidation roasting of metal oxide pellets. Figure 8As shown, the liquid phase temperature of the material, roasting parameters, ferrous content in the material, moisture content in the material, and the feeding amount per unit time of the oxidation roasting device are detected; then the target hot air flow rate W and hot air temperature T for oxidation roasting of metal oxide pellet materials using the oxidation roasting device are calculated. Two electric heat storage devices are used, numbered as heat storage chamber 1 and heat storage chamber 2. First, air is introduced into heat storage chamber 1 and the electric heating of heat storage chamber 1 is turned on. After heat storage chamber 1 completes air heating, the electric heating of heat storage chamber 1 and the first air short-circuit valve next to heat storage chamber 1 are turned off. Air is introduced into heat storage chamber 2 and the electric heating of heat storage chamber 2 is turned on. The temperature of the hot air discharged from heat storage chamber 1 and the temperature of the cold air are detected. The flow rate W1 of the hot air discharged by the first hot air duct and the air flow rate W2 of the second air short-circuit are calculated. The second air circuit breaker valve, the first flow control valve and the second flow control valve next to heat storage chamber 2 are opened. The hot air with a flow rate W1 delivered by the first hot air duct and the air with a flow rate W2 delivered by the second air short-circuit are delivered to the mixing chamber for uniform mixing. The hot air with a hot air flow rate W and a hot air temperature T is delivered to the oxidation roasting device. After the hot air in the heat storage chamber 1 is exhausted and the heat storage chamber 2 heats the air to obtain heat-saturated hot air; turn off the electric heating of the heat storage chamber 2 and the first air short-circuit valve next to the heat storage chamber 2; introduce air into the heat storage chamber 1 and turn on the electric heating of the heat storage chamber 1, detect the temperature of the hot air discharged from the heat storage chamber 2 and the temperature of the cold air, calculate the flow rate W2' of the hot air discharged by the second hot air duct and the air flow rate W1' of the first air short-circuit, open the first air circuit breaker valve, the first flow control valve, and the second flow control valve next to the heat storage chamber 1, and transport the hot air with a flow rate W2' transported by the second hot air duct and the air with a flow rate W1' transported by the first air short-circuit to the mixing chamber for uniform mixing, and the hot air with a hot air flow rate W and a hot air temperature T is transported to the oxidation roasting device.

[0068] In the present invention, the length of the electric heat storage device is 0.5-50 m, preferably 1-30 m, more preferably 2-20 m. The height of the electric heat storage device is 0.2-20 m, preferably 0.5-10 m, more preferably 1-8 m.

[0069] Preferably, the electric heat storage device is composed of refractory bricks and electric heating wires. The electric heat storage device is formed of refractory bricks into a box with a cavity structure, and the electric heating wire is arranged in the refractory bricks. The cavity is used for air circulation and heating of the air. The electric heat storage device has an air inlet and an air outlet, and the electric heating wire is controlled by power on and power off.

[0070] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0071] 1. Green electricity energy is used to replace traditional fossil energy. Clean, zero-carbon wind and solar green electricity energy is introduced instead of traditional fossil energy. It is not only environmentally friendly, but also the oxygen content of the hot air generated will not be reduced, which is more conducive to the oxidation roasting operation of pellets, and carbon emissions have been greatly reduced;

[0072] 2. Indirect heat exchange is used instead of direct heat exchange, abandoning the traditional heat exchange method of direct flame baking and roasting of materials. An indirect heat exchange method of first preparing high-temperature hot air and then roasting the pellet materials with high-temperature hot air is introduced. Stable constant temperature hot air is more conducive to the uniform calcination of pellets than unstable flame baking.

[0073] 3. Develop a binary alternating heat storage hot air calcination process and a binary alternating heat storage hot air preparation system. This avoids the problem of unstable hot air temperature and flow caused by the gradual decrease of heat storage ball energy in the traditional heat storage chamber. The system of the present invention can continuously and stably provide constant temperature hot air for pellets through detection devices and control systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 It is the first oxidation pellet roasting process in the prior art;

[0075] Figure 2 This is the second oxidation pellet roasting process in the prior art;

[0076] Figure 3 This is the third oxidation pellet roasting process in the prior art;

[0077] Figure 4 This is a system configuration diagram of the present invention using electric hot air for roasting;

[0078] Figure 5 This is a detailed configuration diagram of the system for roasting using electric hot air in the present invention;

[0079] Figure 6 This is a schematic diagram of the system structure of the present invention using electric hot air for roasting

[0080] Figure 7 It is a partial enlarged view of the system of the present invention that adopts electric hot air for roasting;

[0081] Figure 8 The present invention is a process flow chart of roasting by using electric hot air.

[0082] Reference numerals:

[0083] 1: electric heat storage device; 2: oxidation roasting device; 3: air mixing chamber; 401: first short-circuit control valve; 402: second short-circuit control valve; 501: first flow detector; 502: second flow detector; 601: first temperature detector; 602: second temperature detector; 701: first flow control valve; 702: second flow control valve; L0: air delivery duct; L1: first hot air duct; L2: second hot air duct; L3: third hot air duct; L4: first air short circuit; L5: second air short circuit. DETAILED DESCRIPTION

[0084] The technical solution of the present invention is illustrated below by way of example, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0085] A system for roasting using electric hot air, the system comprising an electric heat storage device 1 and an oxidation roasting device 2. The air inlet of the electric heat storage device 1 is connected to an air delivery pipeline L0. The air outlet of the electric heat storage device 1 is connected to the roasting section of the oxidation roasting device 2.

[0086] Preferably, the system comprises two or more groups of electric heat storage devices 1. The system further comprises an air mixing chamber 3. The air outlets of the electric heat storage devices 1 are all connected to the air mixing chamber 3. The air outlet of the air mixing chamber 3 is connected to the oxidation roasting device 2.

[0087] Preferably, the oxidation roasting device 2 is any one of a rotary kiln, a belt roasting machine, and a vertical furnace.

[0088] Preferably, the air outlet of the air mixing chamber 3 is connected to the roasting section of the belt roasting machine or the vertical furnace.

[0089] Preferably, the electric heat storage device 1 is an electric heating wire heating device, a microwave heating device, an arc heating device or a plasma heating device.

[0090] Preferably, two groups of electric heat storage devices 1 are connected in parallel to the air mixing chamber 3. The electric heat storage devices 1 of the first group are connected to the air mixing chamber 3 through the first hot air duct L1. The electric heat storage devices 1 of the second group are connected to the air mixing chamber 3 through the second hot air duct L2. The air outlet of the air mixing chamber 3 is connected to the oxidative roasting device 2 through the third hot air duct L3.

[0091] Preferably, the system further comprises a first air short circuit L4 and a second air short circuit L5. The first air short circuit L4 connects the air intake duct of the first group of the electric heat storage device 1 and the first hot air duct L1. The second air short circuit L5 connects the air intake duct of the second group of the electric heat storage device 1 and the second hot air duct L2.

[0092] Preferably, the first hot air duct L1 is provided with a first flow detector 501 , a first temperature detector 601 , and a first flow control valve 701 .

[0093] Preferably, the second hot air duct L2 is provided with a second flow detector 502 , a second temperature detector 602 , and a second flow control valve 702 .

[0094] Preferably, a first short circuit control valve 401 is provided on the first air short circuit L4, and a second short circuit control valve 402 is provided on the second air short circuit L5.

[0095] Example 1

[0096] like Figure 1 As shown, a system using electric hot air for roasting includes an electric heat storage device 1 and a group of oxidation roasting devices 2. The air inlet of the electric heat storage device 1 is connected to the air delivery pipeline L0. The air outlet of the electric heat storage device 1 is connected to the roasting section of the oxidation roasting device 2. The electric heat storage device 1 is an electric heating wire heating device.

[0097] Example 2

[0098] like Figure 4-6 As shown, a system for roasting using electric hot air includes an electric heat storage device 1 and an oxidation roasting device 2. The air inlet of the electric heat storage device 1 is connected to the air delivery duct L0. The air outlet of the electric heat storage device 1 is connected to the roasting section of the oxidation roasting device 2. The system includes two groups of electric heat storage devices 1. Two groups of electric heat storage devices 1 are connected in parallel to the air mixing chamber 3. The electric heat storage devices 1 of the first group are connected to the air mixing chamber 3 through the first hot air duct L1. The electric heat storage devices 1 of the second group are connected to the air mixing chamber 3 through the second hot air duct L2. The air outlet of the air mixing chamber 3 is connected to the oxidation roasting device 2 through the third hot air duct L3.

[0099] Example 3

[0100] Repeat Example 2, except that the system also includes a first air short circuit L4 and a second air short circuit L5. The first air short circuit L4 connects the air intake duct of the first group of the electric heat storage device 1 and the first hot air duct L1. The second air short circuit L5 connects the air intake duct of the second group of the electric heat storage device 1 and the second hot air duct L2. The first hot air duct L1 is provided with a first flow detector 501, a first temperature detector 601, and a first flow control valve 701. The second hot air duct L2 is provided with a second flow detector 502, a second temperature detector 602, and a second flow control valve 702. The first air short circuit L4 is provided with a first short circuit control valve 401, and the second air short circuit L5 is provided with a second short circuit control valve 402.

[0101] Example 4

[0102] Example 3 is repeated, except that the oxidation roasting device 2 is a rotary kiln and the electric heat storage device 1 is a microwave heating device.

[0103] Example 5

[0104] Example 3 is repeated, except that the oxidation roasting device 2 is a belt roasting machine, and the air outlet of the air mixing chamber 3 is connected to the roasting section of the belt roasting machine. The electric heat storage device 1 is an electric arc heating device.

[0105] Example 6

[0106] Example 3 is repeated, except that the oxidation roasting device 2 is a vertical furnace, and the air outlet of the air mixing chamber 3 is connected to the roasting section of the vertical furnace. The electric heat storage device 1 is a plasma heating device.

[0107] Example 7

[0108] A method for roasting using electric hot air, using the device described in Example 4, the method comprising the following steps:

[0109] 1) transporting the metal oxide pellet material to the oxidation roasting device 2, and using the electric heat storage device 1 to heat the air to obtain hot air;

[0110] 2) The hot air is transported to the oxidation roasting device 2, in which the hot air roasts the metal oxide pellet material to obtain oxidation pellets.

[0111] Example 8

[0112] A method for roasting using electric hot air, using the device described in Example 4, the method comprising the following steps:

[0113] 1) transporting the metal oxide pellet material to the oxidation roasting device 2; using the electric heat storage device 1 to heat the air to obtain hot air;

[0114] 2) The hot air is transported to the oxidation roasting device 2, in which the hot air roasts the metal oxide pellet material to obtain oxidation pellets.

[0115] The flow rate of the hot air in the first hot air duct L1 is detected by the first flow detector 501, and the temperature of the hot air in the first hot air duct L1 is detected by the first temperature detector 601; the flow rate of the hot air in the second hot air duct L2 is detected by the second flow detector 502, and the temperature of the hot air in the second hot air duct L2 is detected by the second temperature detector 602; the first short-circuit control valve 401, the second short-circuit control valve 402, the first flow control valve 701 and the second flow control valve 702 are adjusted to control the temperature and air volume of the hot air mixed in the air mixing chamber 3 and transported to the oxidation roasting device 2.

[0116] Example 9

[0117] Repeat Example 8, except that the method further comprises:

[0118] 4) Detect the liquid phase temperature T required for metal oxide pellets 液相化 , ferrous content in metal oxide pellets K 亚铁 , detect the feeding amount λ per unit time in the oxidation roasting device 2, detect the moisture content ω of the metal oxide pellet material, calculate the temperature T of the hot air required for the metal oxide pellet material in the oxidation roasting device 2; calculate the hot air volume W required per unit time based on the calculated required hot air temperature T; specifically:

[0119] T=T 液相化 ×(1-K 亚铁 )×γ 亚铁 ;

[0120]

[0121] Where: γ 亚铁 is the heat release coefficient of ferrous reaction; C 热风 is the heat coefficient of hot air; θ 物料 is the calcination parameter of metal oxide pellets; θ 水蒸气 is the heat coefficient required for water evaporation.

[0122] Example 10

[0123] like Figure 7 As shown, Example 8 is repeated, except that the method further comprises:

[0124] 5) Close the first flow control valve 701 and the second flow control valve 702; close the second group of electric heat storage devices 1 and the first short-circuit control valve 401; introduce air into the first group of electric heat storage devices 1 and open the first group of electric heat storage devices 1;

[0125] 6) The first group of electric heat storage devices 1 heats the air to obtain heat-saturated hot air I; the first group of electric heat storage devices 1 and the first short-circuit control valve 401 are closed, and cold air is introduced into the second group of electric heat storage devices 1 and the second group of electric heat storage devices 1 is opened; at the same time: the first flow control valve 701, the second flow control valve 702, and the second short-circuit control valve 402 are opened; the hot air I is mixed with the cold air input through the second air short circuit L5 in the air mixing chamber 3, and then enters the oxidation roasting device 2; the temperature of the hot air in the first hot air duct L1 is detected by the first temperature detector 601, and the temperature of the cold air in the second hot air duct L2 is detected by the second temperature detector 602; the opening of the first flow control valve 701 and the second flow control valve 702 is controlled so that:

[0126] W1+W2≥W;

[0127]

[0128] Wherein: W1 is the hot air delivery volume in the first hot air duct L1; W2 is the cold air delivery volume in the second hot air duct L2; T1 is the temperature of the hot air delivered in the first hot air duct L1; T2 is the temperature of the cold air delivered in the second hot air duct L2;

[0129] 7) After the hot air I in the first group of electric heat storage devices 1 is exhausted, the second group of electric heat storage devices 1 heats the air to obtain heat-saturated hot air II; close the second group of electric heat storage devices 1 and the second short-circuit control valve 402, introduce cold air into the first group of electric heat storage devices 1 and open the first group of electric heat storage devices 1; at the same time: open the second flow control valve 702, the first flow control valve 701, and the first short-circuit control valve 401; the hot air II is mixed with the cold air input through the first air short circuit L4 in the air mixing chamber 3, and then enters the oxidation roasting device 2; the temperature of the cold air in the first hot air duct L1 is detected by the first temperature detector 601, and the temperature of the hot air in the second hot air duct L2 is detected by the second temperature detector 602; the opening of the first flow control valve 701 and the second flow control valve 702 is controlled so that:

[0130] W1'+W2'≥W;

[0131]

[0132] Wherein: W1' is the cold air delivery volume in the first hot air duct L1; W2' is the hot air delivery volume in the second hot air duct L2; T1' is the temperature of the cold air delivered in the first hot air duct L1; T2' is the temperature of the hot air delivered in the second hot air duct L2;

[0133] 8) Repeat steps 6) and 7) to continuously deliver hot air with a temperature greater than or equal to T and a flow rate ≥ W to the oxidation roasting device 2.

[0134] The same batch of metal oxide pellets were processed by the devices of Example 1 and Example 3. The oxidation roasting device was a rotary kiln. The same specification of electric heat storage device was used. The power of the electric heat storage device was controlled to be the same. The performance of the oxidized pellets was tested respectively, and the results were as follows:

[0135]

[0136] Among them: the strength of the oxidized pellets is tested in accordance with GB / T 14201-2018. The trivalent iron content in the oxidized pellets is the ratio of the content of ferric oxide in the oxidized pellets to the iron-containing compounds (elemental iron and iron oxides) in the entire oxidized pellets (the purpose of the oxidized pellet process is to convert all valence iron into trivalent iron for blast furnace reduction smelting), which is obtained through test detection. The particle size qualification rate of the oxidized pellets refers to the blast furnace's requirement for the particle size of the pellets entering the furnace, which is generally between 16-20mm. Those below 16mm or above 20mm are considered to be unqualified products. The proportion of qualified products in each ton of finished pellet ore is the particle size qualification rate.

[0137] Application Examples

[0138] The material composition of metal oxide pellets: iron ore powder (particle size 2mm), bentonite, quicklime, water. The materials are mixed and pelletized to obtain metal oxide pellets with a particle size of 16-20mm.

[0139] Detect various indicators of metal oxide pellet materials: liquid phase required temperature T 液相化 :1250℃;Fe content K in metal oxide pellets 亚铁 : 10%;

[0140] Detect the feeding amount per unit time λ in the oxidation roasting device 2: 200000 kg / h; Detect the moisture content ω of the metal oxide pellet material: 5%;

[0141] γ 亚铁 The heat release coefficient of ferrous iron reaction is 1.1; C 热风 Hot air specific heat coefficient: 1.35kJ / m 3 .℃;θ 物料 The calcination parameters of metal oxide pellets are: 600 kJ / kg; θ 水蒸气 The heat coefficient required for water evaporation is 1500kJ / kg.

[0142] A method for roasting using electric hot air, using the device described in Example 4, the method comprising the following steps:

[0143] 1) transporting the metal oxide pellet material to the oxidation roasting device 2, and using the electric heat storage device 1 to heat the air to obtain hot air;

[0144] 2) conveying the hot air to the oxidation roasting device 2, in which the hot air roasts the metal oxide pellet material to obtain oxidation pellets;

[0145] 3) Detecting the flow rate of the hot air in the first hot air duct L1 by the first flow detector 501, and detecting the temperature of the hot air in the first hot air duct L1 by the first temperature detector 601; detecting the flow rate of the hot air in the second hot air duct L2 by the second flow detector 502, and detecting the temperature of the hot air in the second hot air duct L2 by the second temperature detector 602; adjusting the first short-circuit control valve 401, the second short-circuit control valve 402, the first flow control valve 701 and the second flow control valve 702 to control the temperature and air volume of the hot air mixed in the air mixing chamber 3 and transported to the oxidation roasting device 2;

[0146] 4) Detect the liquid phase temperature T required for metal oxide pellets 液相化 , ferrous content in metal oxide pellets K 亚铁 , detect the feeding amount λ per unit time in the oxidation roasting device 2, detect the moisture content ω of the metal oxide pellet material, calculate the temperature T of the hot air required for the metal oxide pellet material in the oxidation roasting device 2; calculate the hot air volume W required per unit time based on the calculated required hot air temperature T; specifically:

[0147] T=T 液相化 ×(1-K 亚铁 )×γ 亚铁 =1237.5℃;

[0148]

[0149] Where: γ 亚铁 is the heat release coefficient of ferrous reaction; C 热风 is the heat coefficient of hot air; θ 物料 is the calcination parameter of metal oxide pellets; θ 水蒸气 The heat coefficient required for water evaporation;

[0150] 5) Close the first flow control valve 701 and the second flow control valve 702; close the second group of electric heat storage devices 1 and the first short-circuit control valve 401; introduce air into the first group of electric heat storage devices 1 and open the first group of electric heat storage devices 1;

[0151] 6) The electric heat storage device 1 of the first group heats the air to obtain heat-saturated hot air I; the electric heat storage device 1 of the first group and the first short-circuit control valve 401 are closed, and cold air is introduced into the electric heat storage device 1 of the second group and the electric heat storage device 1 of the second group is opened; at the same time: the first flow control valve 701, the second flow control valve 702, and the second short-circuit control valve 402 are opened; the hot air I is mixed with the cold air input through the second air short circuit L5 in the air mixing chamber 3, and then enters the oxidation roasting device 2; the temperature of the hot air in the first hot air duct L1 is detected to be 1400°C by the first temperature detector 601; the temperature of the cold air in the second hot air duct L2 is detected to be 30°C by the second temperature detector 602; the opening of the first flow control valve 701 is controlled so that the hot air delivery volume in the first hot air duct L1 is 71223m 3 / h; the opening degree of the second flow control valve 702 makes the cold air delivery volume in the second hot air duct L2 9585m 3 / h; Satisfy:

[0152] W1+W2≥W;

[0153]

[0154] 7) After the hot air I in the first group of electric heat storage devices 1 is exhausted, the second group of electric heat storage devices 1 heats the air to obtain heat-saturated hot air II; close the second group of electric heat storage devices 1 and the second short-circuit control valve 402, introduce cold air into the first group of electric heat storage devices 1 and open the first group of electric heat storage devices 1; at the same time: open the second flow control valve 702, the first flow control valve 701, and the first short-circuit control valve 401; the hot air II is mixed with the cold air input through the first air short circuit L4 in the air mixing chamber 3, and then enters the oxidation roasting device 2; the temperature of the cold air in the first hot air duct L1 is detected by the first temperature detector 601 to be 30°C; the temperature of the hot air in the second hot air duct L2 is detected by the second temperature detector 602 to be 1380°C; the opening of the second flow control valve 702 is controlled so that the hot air delivery volume in the second hot air duct L2 is 72278.3m 3 / h; the opening degree of the first flow control valve 701 makes the cold air delivery volume in the first hot air duct L1 8529.7m 3 / h; Satisfy:

[0155] W1'+W2'≥W;'

[0156]

[0157] 8) Repeat steps 6) and 7) to continuously transport the temperature greater than or equal to 1237.5°C and the flow rate greater than or equal to 80808m 3 / h of hot air.

Claims

1. A method for roasting using electric hot air, characterized in that: The method comprises the following steps: 1) transporting the metal oxide pellet material to an oxidation roasting device (2); using the electric heat storage device (1) to heat the air to obtain hot air; 2) The hot air is transported to the oxidation roasting device (2), and in the oxidation roasting device (2), the hot air roasts the metal oxide pellet material to obtain oxidation pellets.

2. The method according to claim 1, characterized in that: Two or more groups of electric heat storage devices (1) are connected in parallel to an oxidation roasting device (2); Preferably, it also includes an air mixing chamber (3), and the hot air obtained by heating the electric heat storage device (1) is mixed in the air mixing chamber (3) and then transported to the oxidation roasting device (2).

3. The method according to claim 1 or 2, characterized in that: The oxidation roasting device (2) is any one of a rotary kiln, a belt roasting machine and a vertical furnace.

4. The method according to claim 2 or 3, characterized in that: Two groups of electric heat storage devices (1) are connected in parallel to the air mixing chamber (3), and the method further comprises: 3) the first group of electric heat storage devices (1) are connected to the air mixing chamber (3) via a first hot air duct (L1), the second group of electric heat storage devices (1) are connected to the air mixing chamber (3) via a second hot air duct (L2), and the air outlet of the air mixing chamber (3) is connected to the oxidative roasting device (2) via a third hot air duct (L3); It also comprises a first air short circuit (L4) and a second air short circuit (L5), wherein the first air short circuit (L4) is connected to the air intake duct of the first group of the electric heat storage devices (1) and the first hot air duct (L1); and the second air short circuit (L5) is connected to the air intake duct of the second group of the electric heat storage devices (1) and the second hot air duct (L2); The first air short circuit (L4) is provided with a first short circuit control valve (401), and the second air short circuit (L5) is provided with a second short circuit control valve (402); the first hot air duct (L1) is provided with a first flow detector (501), a first temperature detector (601), and a first flow control valve (701); the second hot air duct (L2) is provided with a second flow detector (502), a second temperature detector (602), and a second flow control valve (702); the flow rate of hot air in the first hot air duct (L1) is detected by the first flow detector (501). The temperature of the hot air in the first hot air duct (L1) is detected by a first temperature detector (601); the flow rate of the hot air in the second hot air duct (L2) is detected by a second flow detector (502); and the temperature of the hot air in the second hot air duct (L2) is detected by a second temperature detector (602); and the first short-circuit control valve (401), the second short-circuit control valve (402), the first flow control valve (701) and the second flow control valve (702) are adjusted to control the temperature and air volume of the hot air that is mixed in the air mixing chamber (3) and then transported to the oxidation roasting device (2).

5. The method according to claim 4, characterized in that: The method further includes: 4) Detect the liquid phase temperature T required for metal oxide pellets 液相化 , ferrous content in metal oxide pellets K 亚铁 , detecting the feeding amount λ per unit time in the oxidation roasting device (2), detecting the moisture content ω of the metal oxide pellet material, calculating the temperature T of the hot air required for the metal oxide pellet material in the oxidation roasting device (2); and calculating the hot air volume W required per unit time based on the calculated required hot air temperature T; specifically: T=T 液相化 ×(1-K 亚铁 )×γ 亚铁 ; Where: γ 亚铁 is the heat release coefficient of ferrous reaction; C 热风 is the heat coefficient of hot air; θ 物料 is the calcination parameter of metal oxide pellets; θ 水蒸气 is the heat coefficient required for water evaporation.

6. The method according to claim 5, characterized in that: The method further includes: 5) closing the first flow control valve (701) and the second flow control valve (702); closing the second group of electric heat storage devices (1) and the first short-circuit control valve (401); introducing air into the first group of electric heat storage devices (1) and opening the first group of electric heat storage devices (1); 6) The first group of electric heat storage devices (1) heats air to obtain heat-saturated hot air I; the first group of electric heat storage devices (1) and the first short-circuit control valve (401) are closed, and cold air is introduced into the second group of electric heat storage devices (1) and the second group of electric heat storage devices (1) is opened; at the same time: the first flow control valve (701), the second flow control valve (702), and the second short-circuit control valve (402) are opened; the hot air I is mixed with the cold air input through the second air short circuit (L5) in the air mixing chamber (3), and then enters the oxidation roasting device (2); the temperature of the hot air in the first hot air duct (L1) is detected by the first temperature detector (601), and the temperature of the cold air in the second hot air duct (L2) is detected by the second temperature detector (602); the openings of the first flow control valve (701) and the second flow control valve (702) are controlled so that: W1+W2≥W; Wherein: W1 is the hot air delivery volume in the first hot air duct (L1); W2 is the cold air delivery volume in the second hot air duct (L2); T1 is the temperature of the hot air delivered in the first hot air duct (L1); T2 is the temperature of the cold air delivered in the second hot air duct (L2); 7) After the hot air I in the first group of electric heat storage devices (1) is completely discharged, the second group of electric heat storage devices (1) heats the air to obtain heat-saturated hot air II; the second group of electric heat storage devices (1) and the second short-circuit control valve (402) are closed, cold air is introduced into the first group of electric heat storage devices (1) and the first group of electric heat storage devices (1) are opened; at the same time: the second flow control valve (702), the first flow control valve (701) and the first short-circuit control valve (401) are opened; the hot air II is mixed with the cold air input through the first air short circuit (L4) in the air mixing chamber (3) and then enters the oxidation roasting device (2); the temperature of the cold air in the first hot air duct (L1) is detected by the first temperature detector (601), and the temperature of the hot air in the second hot air duct (L2) is detected by the second temperature detector (602); the openings of the first flow control valve (701) and the second flow control valve (702) are controlled so that: W1'+W2'≥W; Wherein: W1' is the cold air delivery volume in the first hot air duct (L1); W2' is the hot air delivery volume in the second hot air duct (L2); T1' is the temperature of the cold air delivered in the first hot air duct (L1); T2' is the temperature of the hot air delivered in the second hot air duct (L2); 8) Repeat steps 6) and 7) to continuously deliver hot air having a temperature greater than or equal to T and a flow rate greater than or equal to W into the oxidation roasting device (2).

7. A system for roasting using electric hot air or a system for the method according to any one of claims 1 to 6, characterized in that: The system comprises an electric heat storage device (1) and an oxidation roasting device (2); the air inlet of the electric heat storage device (1) is connected to an air delivery pipeline (L0); and the air outlet of the electric heat storage device (1) is connected to a roasting section of the oxidation roasting device (2).

8. The system according to claim 7, characterized in that: The system comprises two or more groups of electric heat storage devices (1), and the system also comprises an air mixing chamber (3); the air outlets of the electric heat storage devices (1) are all connected to the air mixing chamber (3), and the air outlets of the air mixing chamber (3) are connected to the oxidation roasting device (2); and / or The oxidation roasting device (2) is any one of a rotary kiln, a belt roasting machine, and a vertical furnace; preferably, the air outlet of the air mixing chamber (3) is connected to the roasting section of the belt roasting machine or the vertical furnace; and / or The electric heat storage device (1) is an electric heating wire heating device, a microwave heating device, an arc heating device or a plasma heating device.

9. The system according to claim 7 or 8, characterized in that: Two groups of electric heat storage devices (1) are connected in parallel to an air mixing chamber (3); the electric heat storage devices (1) of the first group are connected to the air mixing chamber (3) via a first hot air duct (L1), and the electric heat storage devices (1) of the second group are connected to the air mixing chamber (3) via a second hot air duct (L2); the air outlet of the air mixing chamber (3) is connected to the oxidation roasting device (2) via a third hot air duct (L3); Preferably, the system further comprises a first air short circuit (L4) and a second air short circuit (L5), wherein the first air short circuit (L4) connects the air intake duct and the first hot air duct (L1) of the first group of the electric heat storage devices (1); and the second air short circuit (L5) connects the air intake duct and the second hot air duct (L2) of the second group of the electric heat storage devices (1).

10. The system according to claim 9, characterized in that: The first hot air duct (L1) is provided with a first flow detector (501), a first temperature detector (601), and a first flow control valve (701); the second hot air duct (L2) is provided with a second flow detector (502), a second temperature detector (602), and a second flow control valve (702); the first air short circuit (L4) is provided with a first short circuit control valve (401), and the second air short circuit (L5) is provided with a second short circuit control valve (402).

Images