Suspension calcination system and method capable of adjusting activity of light calcined magnesia

Abstract

The invention relates to the technical field of magnesium oxide calcination, and particularly discloses a suspension calcination system and method capable of adjusting the activity of light calcined magnesium oxide. Comprising a multi-stage preheater, a suspension calcining furnace connected with the multi-stage preheater, a high-temperature section cyclone cooler which is respectively connected with the multi-stage preheater and the suspension calcining furnace and is used for conveying flue gas subjected to heat exchange to the suspension calcining furnace, and a low-temperature section cyclone cooler connected with the high-temperature section cyclone cooler, a plurality of layers of combustors used for realizing gradient distribution and partitioned combustion of the temperature in the suspension calcining furnace are arranged in the suspension calcining furnace; according to the invention, the distribution valve, the multi-layer combustor and the high-temperature section cyclone cooler are connected with the suspension calcining furnace, the distribution valve is adjusted for distribution circulation, the multi-layer combustor realizes partitioned combustion, and residual air after heat exchange of the high-temperature section cyclone cooler is used for cooperation, so that the activity index of light-burned MgO is adjusted and controlled in stable and continuous production, and the production efficiency is improved. The product quality requirement is met.

Description

Technical Field

[0001] The invention relates to the technical field of magnesium oxide calcination, and more particularly to a suspension calcination system and method capable of adjusting the activity of light-burned magnesium oxide. Background Art

[0002] As the main raw material for preparing light-burned magnesium oxide, the calcination process of magnesite has an important influence on the activity and purity of magnesium oxide. Studies have shown that calcination temperature, calcination time, heating rate and raw material particle size are key factors affecting the activity of light-burned magnesium oxide. The existing light-burned magnesium oxide production generally adopts the method of calcining blocky magnesite ore in a reverberatory kiln. During the production process, the temperature difference inside the kiln, that is, the middle temperature is high and the side wall temperature is low, resulting in uneven calcination. At the same time, the reverberatory kiln process has the disadvantages of high energy consumption, slow heat and mass transfer, unstable product properties and poor activity, which greatly limits the production and application of light-burned magnesium oxide. At present, high-energy consumption processes such as reverberatory kilns have been listed in the catalog of obsolete technologies.

[0003] In recent years, the suspension calcination technology, which has been more mature in the cement, alumina and other industries, has gradually been promoted and applied in related industries. In the technical field of calcining magnesia to prepare light-burned magnesia, suspension calcination has also become a green and low-carbon process system that has been promoted and adopted. In the suspension calcination system, magnesia is suspended and dispersed in the high-temperature flue gas in the form of fine powder particles for rapid gas-solid heat exchange, which has the characteristics of large heat transfer area, large comprehensive heat transfer coefficient, fast calcination speed and high decomposition rate.

[0004] The existing suspended calcination technology for preparing light-burned MgO is mainly borrowed from mature process systems such as the cement industry. However, due to the process characteristics of the suspended calcination equipment itself, the turbulence effect in the suspended calcination furnace is strong, the residence time of the MgCO3 mineral in the furnace is short, the heat transfer and reaction time are insufficient, and the decomposition reaction progress of different components in the magnesite is inconsistent, resulting in a part of the magnesite particles not being truly completely decomposed. The quality of the prepared light-burned magnesium oxide is uneven, and the product activity and loss on ignition are difficult to control. Especially when used as a building material or chemical product, the activity value of magnesium oxide will fluctuate, and sometimes magnesium oxide products with low activity do not meet the index requirements. Therefore, the effect of suspended calcination of magnesite in actual operation needs to be further optimized and improved.

[0005] The activity of light-burned MgO in the suspension calcination system is directly related to the calcination temperature, time and gas-solid heat exchange efficiency. Over-burning and under-burning in the suspension calcination furnace will lead to a decrease in the activity of MgO or even a loss of activity.

[0006] In the current suspension calcination technology and the process system described in the relevant patents, there are mainly the following problems in controlling and regulating the activity of light-burned MgO:

[0007] 1. The activity regulation method is single, which mainly controls the progress of the decomposition reaction by the calcination temperature, which often causes excessive calcination of the particle surface to form over-burned material, or incomplete reaction inside the particle to form under-burned material.

[0008] 2. It is impossible to achieve online real-time adjustment. Some suspended calcination technologies adjust the activity of light-burned MgO by setting up separate storage tanks or fluidized beds and other equipment to control the calcination reaction time, thereby improving the MgO activity index. However, this can easily cause discontinuity in the production process or make it impossible to achieve online real-time adjustment, which increases the complexity of the production process and reduces production efficiency. Summary of the invention

[0009] The technical problem to be solved by the present invention is to provide a suspension calcination system and method capable of adjusting the activity of light-burned magnesium oxide;

[0010] The solution adopted by the present invention to solve the technical problem is:

[0011] A suspension calcination system capable of adjusting the activity of light-burned magnesium oxide comprises a multi-stage preheater, a suspension calcining furnace connected to the multi-stage preheater, a high-temperature section cyclone cooler respectively connected to the multi-stage preheater and the suspension calcining furnace and conveying the flue gas after heat exchange to the suspension calcining furnace, and a low-temperature section cyclone cooler connected to the high-temperature section cyclone cooler; multiple layers of burners are arranged in the suspension calcining furnace for realizing temperature gradient distribution and zoned combustion in the suspension calcining furnace;

[0012] The multi-stage preheater is provided with a regulating distribution valve which is respectively connected to the suspension calcining furnace and the high temperature section cyclone cooler and is used to control the amount of high temperature light-burned MgO material entering the suspension calcining furnace and the high temperature section cyclone cooler.

[0013] In some possible embodiments, the multi-stage preheater includes at least three groups of preheaters, including a sub-final stage preheater connected to the suspension calcining furnace and a final stage preheater respectively connected to the sub-final stage preheater; the final stage preheater is respectively connected to the suspension calcining furnace and the high temperature section cyclone cooler; and the regulating dividing valve is arranged at the discharge port of the final stage preheater.

[0014] In some possible embodiments, the suspension calcining furnace is provided with a first feed port connected to the secondary final stage preheater, a second feed port connected to the final stage preheater, an air outlet connected to the final stage preheater, and an air inlet connected to the high temperature section cyclone cooler;

[0015] The multiple layers of burners include a burner 1 located below the first feed port, a burner 2 located below the second feed port, and a burner 3 located below the gas outlet and in the upper middle part of the suspension calcining furnace.

[0016] In some possible implementations, the burner 1, the burner 2, and the burner 3 are arranged along the axial direction of the suspension calciner, and multiple groups of burners are arranged along the circumferential direction of the suspension calciner.

[0017] In some possible implementations, the regulating dispensing valve is disposed at the discharge port of the last-stage preheater; the regulating dispensing valve is connected to the suspension calcining furnace and the high-temperature section cyclone cooler through pipelines.

[0018] In some possible implementations, a high-temperature section cooling air inlet pipe connected to a regulating dosing valve is externally connected to the high-temperature section cyclone cooler; and a low-temperature section cooling air inlet pipe connected to a discharge port of the high-temperature section cyclone cooler is externally connected to the low-temperature section cyclone cooler.

[0019] In some possible embodiments, the multi-stage preheater includes three groups of preheaters, including a first-stage preheater, a sub-final stage preheater connected to the suspension calcining furnace, and a final stage preheater respectively connected to the sub-final stage preheater; the first-stage preheater and the sub-final stage preheater, and the sub-final stage preheater and the final stage preheater are respectively connected through a flue gas rising duct; the discharge port of the first-stage preheater is connected to the flue gas rising duct between the sub-final stage preheater and the final stage preheater.

[0020] A suspension calcination method according to the suspension calcination system capable of adjusting the activity of light-burned magnesium oxide as described above,

[0021] The specific steps include:

[0022] Step S1: Magnesite powder enters the flue gas ascending pipe of the multi-stage preheater, and the magnesite powder is fully dispersed by the high-temperature flue gas rising at a high speed to form a gas-solid two-phase flow, and performs rapid gas-solid two-phase convection heat exchange, and the flue gas after heat exchange is discharged from the exhaust gas outlet of the preheater;

[0023] Step S2: After the magnesite powder is heat exchanged and separated step by step in the multi-stage preheater, it enters the suspension calcining furnace after passing through the second and last stage preheater, and is subjected to zone combustion and decomposition reaction under the cooperation of the multi-layer burners to obtain high-temperature light-burned MgO;

[0024] Step S3: After the high-temperature light-burned MgO material is preliminarily calcined and decomposed in the suspension calcining furnace, it enters the final preheater through a high-temperature pipeline connected to the final preheater for gas-solid material separation, and the material is divided by adjusting the dividing valve according to the activity of the light-burned MgO material. Part of the high-temperature light-burned MgO material enters the suspension calcining furnace again through the feed inlet 2 for calcination as a circulating material, and the rest of the high-temperature light-burned MgO material enters the high-temperature section cyclone cooler;

[0025] Step S4: The high-temperature light-burned MgO material entering the high-temperature section cyclone cooler is rapidly cooled by gas-solid heat exchange with the air entering the pipeline of the high-temperature section cooling air, and the residual air with a temperature of 600°C to 800°C after heat exchange enters the suspension calcining furnace;

[0026] Step S5: The MgO powder after heat exchange enters the low-temperature section cyclone cooler and exchanges heat with the air in the low-temperature section cooling air entering the pipeline. The residual air after heat exchange is discharged, and the MgO powder after heat exchange is cooled down to below 100°C again and sent to the magnesium oxide finished product warehouse.

[0027] In some possible implementations, in step S2, performing zoned combustion and decomposition reaction with the cooperation of multiple layers of burners to obtain high-temperature light-burned MgO specifically refers to:

[0028] According to the activity value and decomposition rate of light-burned MgO, the multi-layer burners are adjusted to control the temperature of the suspension calcining furnace between 700°C and 1050°C to perform zoned combustion and decomposition reactions to obtain high-temperature light-burned MgO.

[0029] In some possible implementations, the step S3 of dividing the materials by adjusting the dividing valve according to the activity of the light-burned MgO material specifically refers to:

[0030] According to the distribution ratio, the number of cycles of the high-temperature light-burned MgO material entering the suspension calcining furnace through the adjustment of the material distribution valve is calculated, and the balance of magnesium oxide in the suspension calcining furnace is calculated with and without material circulation, and n=1 / (1-η), where η is the distribution ratio and n is the number of cycles;

[0031] According to the material distribution ratio of the regulating valve, it is calculated that when the materials in the suspension calcination furnace reach equilibrium, the residence time of all materials in the suspension calcination furnace is t0, t0 = (1 + n × η) t;

[0032] Wherein, t is the time for the material to pass through the suspension calciner once;

[0033] According to the corresponding curve of the activity value and residence time of light-burned MgO, the online regulation target of magnesium oxide activity can be achieved by adjusting the opening of the feed valve.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention adjusts the connection between the material distribution valve, the multi-layer burner, and the high-temperature section cyclone cooler and the suspension calcining furnace, adjusts the material distribution circulation of the material distribution valve, and the multi-layer burner realizes the division combustion and the use of the residual wind after the heat exchange of the high-temperature section cyclone cooler, so as to adjust and control the activity index of the light-burned MgO in stable and continuous production to meet the product quality requirements;

[0036] The present invention adjusts the distribution amount of the high-temperature magnesium oxide material online and in real time through a regulating distribution valve independently arranged at the discharge port of the last-stage preheater. The distribution amount can be controlled between 0 and 100%, thereby adjusting the circulation amount of the high-temperature material. According to the requirements of different activities of the light-burned magnesium oxide, the calcination time of the material in the suspension furnace is controlled, and the activity and ignition loss index requirements of the product are met at the same time.

[0037] By arranging the burners in layers and zones in the suspension calcining furnace, the distribution of the burners is adapted to the feeding of the secondary and final preheaters, the circulating feeding realized by adjusting the feeding valve, and the distribution of the residual air after the heat exchange of the high-temperature section cyclone cooler. With the changes in the feeding amount and the furnace temperature, the fuel amount of each burner can be accurately controlled in zones, thereby controlling the furnace temperature in the suspension calcining furnace, optimizing the temperature field gradient in the furnace, reducing the temperature fluctuation in the furnace, avoiding the generation of local high temperature, reducing the energy consumption of the suspension calcining system, and effectively controlling the decomposition rate of magnesite and the activity of magnesium oxide;

[0038] The present invention forms a two-stage cyclone cooler system by combining a high-temperature section cyclone cooler with a low-temperature section cyclone cooler to cool the light-burned MgO material, effectively ensuring that the material cooling effect is less than 100°C, and can effectively improve the waste heat recovery efficiency. The waste heat wind temperature in the high-temperature section can be stably controlled at 600-800°C according to the material conditions, providing a strong guarantee for adjusting the activity of magnesium oxide and other indicators, and significantly reducing the standard coal consumption of the light-burned magnesium oxide calcining system; wherein the waste wind after heat exchange in the high-temperature section cyclone cooler enters the suspension calcining furnace, thereby increasing the temperature of the waste wind after heat exchange, and helping to stabilize the furnace fuel combustion and temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the present invention;

[0040] Among them: 1. Multi-stage preheater; 11. First-stage preheater; 111. Waste gas outlet; 12. Second-stage preheater; 13. Final-stage preheater; 2. Suspension calcining furnace; 21. Burner; 3. High-temperature section cyclone cooler; 31. High-temperature section cooling air entering pipeline; 4. Low-temperature section cyclone cooler; 41. Low-temperature section cooling air entering pipeline; 5. Adjusting dispensing valve. DETAILED DESCRIPTION

[0041] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. The "first", "second" and similar words mentioned in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, "one" or "one" and other similar words do not indicate a quantity restriction, but indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" refers to two or more. For example, multiple positioning columns refer to two or more positioning columns. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] The present invention is described in detail below.

[0043] like Figure 1 As shown:

[0044] A suspension calcination system capable of adjusting the activity of light-burned magnesium oxide comprises a multi-stage preheater 1, a suspension calcining furnace 2 connected to the multi-stage preheater 1, a high-temperature section cyclone cooler 3 respectively connected to the multi-stage preheater 1 and the suspension calcining furnace 2 and conveying the flue gas after heat exchange to the suspension calcining furnace 2, and a low-temperature section cyclone cooler 4 connected to the high-temperature section cyclone cooler 3; a plurality of layers of burners 21 for realizing a temperature gradient distribution and zoned combustion in the suspension calcining furnace 2 are arranged in the suspension calcining furnace 2;

[0045] The multi-stage preheater 1 is provided with a regulating distribution valve 5 which is respectively connected to the suspension calcining furnace 2 and the high temperature section cyclone cooler 3 and is used to control the amount of high temperature light-burned MgO material entering the suspension calcining furnace 2 and the high temperature section cyclone cooler 3.

[0046] The multi-stage preheater 1 is a prior art. When in use, the magnesite powder entering the multi-stage preheater 1 is fully dispersed by the high-temperature flue gas rising at a high speed to form a gas-solid two-phase flow, and the gas-solid two-phase rapid convection heat exchange is performed. The flue gas exhaust outlet 111 after heat exchange is discharged after dust collection; after step-by-step heat exchange and separation in the multi-stage preheater 1, the ore powder will enter the suspension calcining furnace 2. The multi-stage burner 21 makes the temperature gradient distribution of the suspension forging furnace reasonable, avoids local high temperature, and controls the temperature in the suspension forging furnace between 700°C and 1050°C;

[0047] After the suspension calcining furnace 2 initially completes the calcination and decomposition, the obtained high-temperature light-burned MgO material will enter the multi-stage preheater 1 for gas-solid material separation;

[0048] According to the activity of light-burned MgO, the material distribution is adjusted in real time by adjusting the material distribution valve 5, part of the material enters the suspension calcining furnace 2 again for re-calcination, and the other part enters the high-temperature section cyclone cooler 3 for rapid cooling; by adjusting the setting of the material distribution valve 5, the material distribution is accurately controlled, so as to accurately control the amount of material entering the suspension calcining furnace 2 for re-calcination, adjust the residence time of the material in the suspension calcining furnace 2, and control the activity value and ignition loss of magnesium oxide to meet the product index requirements;

[0049] The high temperature section cyclone cooler 3 exchanges heat with the lightly burned MgO material entering the interior, and the residual air after the heat exchange enters the suspension calcining furnace 2, and cooperates with the multi-layer burner 21 to provide efficient and high-temperature combustion-supporting air, stabilize the fuel combustion and temperature balance in the suspension calcining furnace 2, and also provide a strong guarantee for the regulation of the activity of the MgO material;

[0050] The light-burned MgO material after heat exchange with the high-temperature section cyclone cooler 3 will enter the low-temperature section cyclone cooler 4 to continue heat exchange, ensuring that the light-burned MgO finished material is cooled to below 100°C, and then sent to the magnesium oxide finished product warehouse.

[0051] In some possible embodiments, the multi-stage preheater 1 includes at least three groups of preheaters, including a first-stage preheater 11 provided with a waste gas outlet 111, a secondary and final-stage preheater 12 connected to the suspension calcining furnace 2, a final-stage preheater 13 respectively connected to the secondary and final-stage preheater 12, and several groups of preheaters arranged between the first-stage preheater 11 and the secondary and final-stage preheater; the final-stage preheater 13 is respectively connected to the suspension calcining furnace 2 and the high-temperature section cyclone cooler 3; adjacent preheaters are connected through a flue gas rising pipe; and the regulating distribution valve 5 is arranged at the discharge port of the final-stage preheater 13, that is, the bottom of the final-stage preheater 13.

[0052] Specifically, the multi-stage preheater 1 may have three to six stages;

[0053] When it is three-stage, the multi-stage preheater 1 includes three groups of preheaters, including a first-stage preheater 11, a sub-final stage preheater 12 connected to the suspension calcining furnace 2, and a final stage preheater 13 respectively connected to the sub-final stage preheater 12; the first-stage preheater 11 and the sub-final stage preheater 12, and the sub-final stage preheater 12 and the final stage preheater 13 are respectively connected through a flue gas rising pipe; the discharge port of the first-stage preheater 11 is connected to the flue gas rising pipe between the sub-final stage preheater 12 and the final stage preheater 13.

[0054] After being metered and transported, the magnesite powder is fed into the flue gas ascending pipe of the multi-stage preheater 1. For example, when three sets of preheaters are used, the magnesite powder enters the multi-stage preheater 1 from the flue gas ascending pipe between the first-stage preheater 11 and the second-final-stage preheater 12. The magnesite powder is fully dispersed by the high-temperature flue gas rising at a high speed in the flue gas ascending pipe to form a gas-solid two-phase flow, and a gas-solid two-phase rapid convection heat exchange is performed. The flue gas after heat exchange is discharged from the gas outlet after dust collection;

[0055] After the magnesite powder is heat exchanged and separated step by step in the multi-stage preheater 1, it enters the suspension calcining furnace 2 through the discharge pipe of the secondary and final preheater 12 to undergo a decomposition reaction of the magnesite powder to obtain a light-burned MgO material with a high temperature;

[0056] The high-temperature light-burned MgO material passes through the flue gas duct between the top of the suspension calciner 2 and the final preheater 13, and enters the final preheater 13 for gas-solid material separation; then the material is divided by adjusting the dividing valve 5, and part of the high-temperature light-burned MgO material enters the suspension calciner 2 as a circulating material, and the other part enters the high-temperature section cyclone cooler 3.

[0057] By adjusting the material distribution valve 5, the high-temperature material can be stably and controllably distributed and circulated, and the calcination time of the light-burned magnesium oxide can be reasonably adjusted to avoid insufficient activity caused by a short calcination time; at the same time, the burner 21 arranged in multiple layers in the suspension furnace can be precisely adjusted to match the distribution of the material in the suspension furnace, so as to achieve precise regulation and control of the activity of magnesium oxide; the activity of the light-burned magnesium oxide product (citric acid method) can be adjusted within the range of 30-300s, and the product loss on ignition can be adjusted within the range of 1% to 8%;

[0058] The high-temperature section cyclone cooler 3 and the low-temperature section cyclone cooler 4 form a two-stage cyclone cooling, which can effectively improve the waste heat recovery efficiency. The waste heat air temperature in the high-temperature section can be stably controlled at 600°C to 800°C according to the material conditions, which provides a strong guarantee for adjusting the activity of MgO and other indicators, and significantly reduces the standard coal consumption of the light-burning MgO calcining system;

[0059] The present invention can calcine various materials such as magnesite ore, flotation concentrate, tailings, etc., and can also realize the combustion of various fuels such as coal gas, natural gas or coal powder. By reasonably matching the separation efficiency and pressure loss of each stage of preheater, the material circulation inside the preheater is effectively reduced, and the heat exchange efficiency is improved. From the overall point of view, the reasonable configuration of the multi-stage preheater 1 system can make the system separation efficiency higher than 95%, which can significantly reduce the system energy consumption.

[0060] In some possible embodiments, the suspension calcining furnace 2 is provided with a feed port 1 connected to the secondary and final stage preheater 12, a feed port 2 connected to the final stage preheater 13, an air outlet connected to the final stage preheater 13, and an air inlet connected to the high temperature section cyclone cooler 3;

[0061] The air inlet is arranged at the bottom of the suspension calcining furnace 2, and a high-temperature air duct connected to the inside of the high-temperature cyclone cooler 3 and the air inlet is arranged at the top of the high-temperature section cyclone cooler 3; the material entering the high-temperature section cyclone cooler 3 for heat exchange has a residual air temperature of 600°C to 800°C after heat exchange; and then enters the suspension calcining furnace 2 through the high-temperature air duct;

[0062] The multiple layers of burners 21 include a burner 21 1 located below the first feed port, a burner 21 2 located below the second feed port, and a burner 21 3 located below the gas outlet and in the upper middle portion of the suspension calcining furnace 2 .

[0063] In some possible implementations, the burner 21 1, the burner 21 2, and the burner 21 3 are arranged along the axial direction of the suspension calcining furnace 2, and multiple groups of burners 21 are arranged along the circumference of the suspension calcining furnace 2;

[0064] Through the above arrangement, the calcining fuel is metered and sprayed into the suspension furnace through the multi-layer burner 21 for combustion. The wire accurately distributes the fuel ratio to ensure a reasonable distribution of the temperature field gradient in the furnace and avoid local high temperature. Based on the activity value and decomposition rate of light-burned MgO, the temperature in the suspension calcining furnace 2 is controlled between 700°C and 1050°C.

[0065] In some possible implementations, the regulating dispensing valve 5 is disposed at the discharge port of the last stage preheater 13 and is connected to a discharge pipe disposed at the discharge port; the regulating dispensing valve 5 is connected to the suspension calcining furnace 2 and the high temperature section cyclone cooler 3 through pipelines respectively;

[0066] The high-temperature light-burned MgO material passes through the flue gas duct and enters the final stage preheater 13 for gas-solid separation under the action of the flue gas. The solid material at the separation port will be divided by the adjustable dividing valve 5 through the discharge port of the final stage preheater 13 and then enter the suspension calcining furnace 2 and the high-temperature section cyclone cooler 3 respectively.

[0067] In some possible implementations, a high-temperature section cooling air inlet pipe 31 connected to the regulating dispensing valve 5 is externally connected to the high-temperature section cyclone cooler 3; a low-temperature section cooling air inlet pipe 41 connected to the discharge port of the high-temperature section cyclone cooler 3 is externally connected to the low-temperature section cyclone cooler;

[0068] After adjusting the dispensing valve 5 for dispensing, part of the solid materials entering the high-temperature section cyclone cooler 3 will enter the high-temperature section cooling air inlet pipe 31, exchange heat with the air in the high-temperature section cooling air inlet pipe 31, and enter the tank body of the high-temperature section cyclone cooler 3 under the action of the air. The residual wind with a temperature of 600°C to 800°C after heat exchange will enter the suspension calcining furnace 2. The solid materials after heat exchange will enter the low-temperature section cooling air inlet pipe 41 for heat exchange again, and enter the tank body of the low-temperature section cyclone cooler 4 driven by the air in the low-temperature section cooling air inlet pipe 41. The residual wind after heat exchange is discharged after dust removal treatment. The temperature of the residual wind after heat exchange between the low-temperature section cyclone cooler 4 and the solid is relatively low, so it will not enter the suspension calcining furnace 2, effectively avoiding the reduction of the temperature of the high-temperature section residual wind affecting the activity of MgO; the solid materials will be cooled to below 100°C after heat exchange by the low-temperature section cyclone cooler 4 and sent to the magnesium oxide finished product warehouse.

[0069] Furthermore, the high-temperature section cyclone cooler 3 and the low-temperature section cyclone cooler 4 can be designed as multi-stage coolers according to the cooling material needs to ensure the rapid cooling effect of the material;

[0070] A suspension calcination method according to the suspension calcination system capable of adjusting the activity of light-burned magnesium oxide as described above specifically comprises the following steps:

[0071] Step S1: The magnesite powder enters the flue gas ascending pipe of the multi-stage preheater 1, and the magnesite powder is fully dispersed by the high-temperature flue gas rising at a high speed to form a gas-solid two-phase flow, and the gas-solid two-phase rapid convection heat exchange is performed, and the flue gas after heat exchange is discharged from the preheater exhaust gas outlet 111;

[0072] Step S2: After the magnesite powder is heat exchanged and separated step by step in the multi-stage preheater 1, it enters the suspension calcining furnace 2 after passing through the secondary and final preheater 12, and is subjected to zone combustion and decomposition reaction under the cooperation of the multi-layer burners 21 to obtain high-temperature light-burned MgO;

[0073] The zoned combustion and decomposition reaction to obtain high-temperature light-burned MgO under the cooperation of the multi-layer burners 21 specifically refers to:

[0074] According to the activity value and decomposition rate of light-burned MgO, the multi-layer burners 21 are adjusted to control the temperature of the suspension calcining furnace 2 to be between 700°C and 1050°C for zoned combustion and decomposition reaction to obtain high-temperature light-burned MgO;

[0075] Step S3: the high-temperature light-burned MgO material after preliminary calcination and decomposition in the suspension calcining furnace 2 enters the final stage preheater 13 through a high-temperature pipeline connected to the final stage preheater 13 for gas-solid material separation, and is divided by adjusting the dividing valve 5 according to the activity of the light-burned MgO material. Part of the high-temperature light-burned MgO material enters the suspension calcining furnace 2 again for calcination through the feed port 2 as a circulating material, and the rest of the high-temperature light-burned MgO material enters the high-temperature section cyclone cooler 3;

[0076] The step S3 of dividing the light-burned MgO material by adjusting the dividing valve 5 according to the activity of the light-burned MgO material specifically refers to adjusting the dividing valve 5 to control the amount of the high-temperature light-burned MgO material entering the suspension calcining furnace 2 according to the activity of the light-burned MgO, and adjusting the residence time of the high-temperature light-burned MgO material in the suspension calcining furnace 2.

[0077] The specific adjustment method of adjusting the dispensing valve 5 is as follows:

[0078] According to the distribution ratio, the number of cycles of the circulating material entering the suspension calcining furnace 2 by adjusting the material distribution valve 5 is calculated, and the balance of magnesium oxide in the suspension calcining furnace 2 is calculated when there is no material circulation and when there is material circulation, and n=1 / (1-η), where η is the distribution ratio and n is the number of cycles;

[0079] The above formula shows that as the material splitting ratio increases, the number of cycles of the circulating material in the suspension calcining furnace 2 increases significantly;

[0080] According to the material distribution ratio of the regulating material distribution valve 5, it is calculated that when the materials in the suspension calcining furnace 2 reach equilibrium, the residence time of all the materials in the suspension calcining furnace 2 is t0, t0 = (1 + n × η) t, where t is the time for the materials in the suspension calcining furnace 2 to pass through once;

[0081] If the material distribution ratio is 50%, the residence time of all materials in the suspension calcining furnace 2 is t0, t0 = (1 + n × 50%) t = 2t.

[0082] At this time, according to the corresponding curve of the activity value and residence time of the light-burned MgO, the online adjustment target of the activity of magnesium oxide can be achieved by adjusting the opening of the distribution valve 5;

[0083] Step S4: The high-temperature light-burned MgO material entering the high-temperature section cyclone cooler 3 is rapidly cooled by gas-solid heat exchange with the air in the high-temperature section cooling air entering the pipeline 31, and the residual air with a temperature of 600° C. to 800° C. after heat exchange enters the suspension calcining furnace 2;

[0084] Step S5: After heat exchange, the MgO powder enters the low-temperature cyclone cooler 4 and exchanges heat with the air in the low-temperature cooling air entering the pipeline 41. The residual air after heat exchange is discharged, and the MgO powder after heat exchange is cooled down to below 100°C again and sent to the magnesium oxide finished product warehouse.

[0085] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A suspension calcination system capable of adjusting the activity of light-burned magnesium oxide, characterized in that: It comprises a multi-stage preheater, a suspension calcining furnace connected to the multi-stage preheater, a high-temperature section cyclone cooler connected to the multi-stage preheater and the suspension calcining furnace respectively and conveying the flue gas after heat exchange to the suspension calcining furnace, and a low-temperature section cyclone cooler connected to the high-temperature section cyclone cooler; multiple layers of burners are arranged in the suspension calcining furnace for realizing temperature gradient distribution and zoned combustion in the suspension calcining furnace; The multi-stage preheater is provided with a regulating distribution valve which is respectively connected to the suspension calcining furnace and the high temperature section cyclone cooler and is used to control the amount of high temperature light-burned MgO material entering the suspension calcining furnace and the high temperature section cyclone cooler.

2. A suspension calcination system capable of adjusting the activity of light-burned magnesium oxide according to claim 1, characterized in that: The multi-stage preheater includes at least three groups of preheaters, including a secondary and final stage preheater connected to the suspension calcining furnace, and a final stage preheater respectively connected to the secondary and final stage preheater; the final stage preheater is respectively connected to the suspension calcining furnace and the high temperature section cyclone cooler; the regulating dispensing valve is arranged at the discharge port of the final stage preheater.

3. A suspension calcination system capable of adjusting the activity of light-burned magnesium oxide according to claim 2, characterized in that: The suspension calcining furnace is provided with a first feed port connected to the secondary and final stage preheater, a second feed port connected to the final stage preheater, an air outlet connected to the final stage preheater, and an air inlet connected to the high temperature section cyclone cooler; The multiple layers of burners include a burner 1 located below the first feed port, a burner 2 located below the second feed port, and a burner 3 located below the gas outlet and in the upper middle part of the suspension calcining furnace.

4. A suspension calcination system capable of adjusting the activity of light-burned magnesium oxide according to claim 3, characterized in that: The burner 1, the burner 2 and the burner 3 are arranged along the axial direction of the suspension calcining furnace, and multiple groups of burners are arranged along the circumferential direction of the suspension calcining furnace.

5. A suspension calcination system capable of adjusting the activity of light-burned magnesium oxide according to claim 2, characterized in that: The regulating dispensing valve is respectively connected to the suspension calcining furnace and the high-temperature section cyclone cooler through pipelines.

6. A suspension calcination system capable of adjusting the activity of light-burned magnesium oxide according to claim 5, characterized in that: The high-temperature section cyclone cooler is externally connected with a high-temperature section cooling air inlet pipeline connected to a regulating dispensing valve; the low-temperature section cyclone cooler is externally connected with a low-temperature section cooling air inlet pipeline connected to a discharge port of the high-temperature section cyclone cooler.

7. A suspension calcination system capable of adjusting the activity of light-burned magnesium oxide according to claim 2, characterized in that: The multi-stage preheater includes three groups of preheaters, including a first-stage preheater, a sub-final stage preheater connected to the suspension calcining furnace, and a final stage preheater respectively connected to the sub-final stage preheater; the first-stage preheater and the sub-final stage preheater, and the sub-final stage preheater and the final stage preheater are respectively connected through a flue gas rising pipe; the discharge port of the first-stage preheater is connected to the flue gas rising pipe between the sub-final stage preheater and the final stage preheater.

8. A suspension calcination method of a suspension calcination system capable of adjusting the activity of light-burned magnesium oxide according to any one of claims 1 to 7, characterized in that: The specific steps include: Step S1: Magnesite powder enters the flue gas ascending pipe of the multi-stage preheater, and the magnesite powder is fully dispersed by the high-temperature flue gas rising at a high speed to form a gas-solid two-phase flow, and performs rapid gas-solid two-phase convection heat exchange, and the flue gas after heat exchange is discharged from the exhaust gas outlet of the preheater; Step S2: After the magnesite powder is heat exchanged and separated step by step in the multi-stage preheater, it enters the suspension calcining furnace after passing through the second and last stage preheater, and is subjected to zone combustion and decomposition reaction under the cooperation of the multi-layer burners to obtain high-temperature light-burned MgO material; Step S3: the high-temperature light-burned MgO material after calcination and decomposition in the suspension calcining furnace enters the final preheater through a high-temperature pipeline connected to the final preheater for gas-solid material separation, and the light-burned MgO material is divided by adjusting the dividing valve according to the activity of the light-burned MgO material. Part of the high-temperature light-burned MgO material enters the suspension calcining furnace again through the feed inlet 2 for calcination as a circulating material, and the remaining part of the high-temperature light-burned MgO material enters the high-temperature section cyclone cooler as a circulating material; Step S4: The high-temperature light-burned MgO material entering the high-temperature section cyclone cooler is rapidly cooled by gas-solid heat exchange with the air entering the pipeline of the high-temperature section cooling air, and the residual air with a temperature of 600°C to 800°C after heat exchange enters the suspension calcining furnace; Step S5: The MgO powder after heat exchange enters the low-temperature section cyclone cooler and exchanges heat with the air in the low-temperature section cooling air entering the pipeline. The residual air after heat exchange is discharged, and the MgO powder after heat exchange is cooled down to below 100°C again and sent to the magnesium oxide finished product warehouse.

9. The suspension calcination method of the suspension calcination system capable of adjusting the activity of light-burned magnesium oxide according to claim 8, characterized in that: In the step S2, the zoned combustion and decomposition reaction are carried out with the cooperation of the multiple layers of the burners to obtain the high-temperature light-burned MgO, which specifically refers to: According to the activity value and decomposition rate of light-burned MgO, the multi-layer burners are adjusted to control the temperature of the suspension calcining furnace between 700°C and 1050°C to perform zoned combustion and decomposition reactions to obtain high-temperature light-burned MgO.

10. The method for suspended calcination in a suspended calcination system capable of adjusting the activity of light-burned magnesium oxide according to claim 8, characterized in that: The step S3 of dividing the materials by adjusting the dividing valve according to the activity of the light-burned MgO material specifically refers to: According to the distribution ratio, the number of cycles of the high-temperature light-burned MgO material entering the suspension calcining furnace through the adjustment of the material distribution valve is calculated, and the balance of magnesium oxide in the suspension calcining furnace is calculated with and without material circulation, and n=1 / (1-η), where η is the distribution ratio and n is the number of cycles; According to the material distribution ratio of the regulating valve, it is calculated that when the materials in the suspension calcination furnace reach equilibrium, the residence time of all materials in the suspension calcination furnace is t0, t0 = (1 + n × η) t; Wherein, t is the time for the material to pass through the suspension calcining furnace once; According to the corresponding curve of the activity value and residence time of light-burned MgO, the online regulation target of magnesium oxide activity can be achieved by adjusting the opening of the feed valve.

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