CN212504609U

CN212504609U - Device for preparing light-burned magnesium oxide through suspension calcination

Info

Publication number: CN212504609U
Application number: CN202021746152.3U
Authority: CN
Inventors: 王德喜; 董辉; 张继宇
Original assignee: Liaoning Shengshi Resources And Environment Technology Co ltd; Shenyang University of Technology
Current assignee: Shenyang University of Technology
Priority date: 2020-08-20
Filing date: 2020-08-20
Publication date: 2021-02-09
Anticipated expiration: 2030-08-20

Abstract

The utility model relates to a suspension is calcined and is prepared device of light-burned magnesia, the device's former feed bin and flash dryer intercommunication, flash dryer and the multistage preheating device of raw materials intercommunication, the multistage preheating device of raw materials respectively with the suspension calcine stove, exhaust treatment device, gas material separator intercommunication, exhaust treatment device communicates with suspension calcine stove and fume extractor respectively, the suspension calcine stove still respectively with gas material separator, product heat recovery device intercommunication, gas material separator and transition feed bin intercommunication, transition feed bin and product heat recovery device intercommunication, product heat recovery device and product feed bin intercommunication. The utility model solves the problems of poor waste heat recovery and utilization rate and uneven product quality of the existing light-burned magnesia calcining equipment, and can obviously reduce the energy consumption of the suspension calcining furnace.

Description

Device for preparing light-burned magnesium oxide through suspension calcination

Technical Field

The utility model relates to a production technology of light-burned magnesia, in particular to a complete device for producing light-burned magnesia by suspending and calcining magnesite powder, which realizes the utilization of flue gas and product waste heat.

Background

The main component of magnesite is magnesium carbonate, which is the most important magnesium-containing ore. China has abundant magnesite resources, has the advantages of being 36.42 hundred million t in resource amount, accounting for 28.85 percent of the total global amount, and has the characteristic of centralized resource distribution. Although China is a big country with magnesite resources, because of years of blind mining and extensive production modes, high-grade ores are gradually deficient, the product quality is unstable, the production efficiency is low, and the product additional value is low.

The light-burned magnesia is one of main products for calcining magnesite, is also a raw material of a plurality of subsequent products such as heavy-burned magnesia and magnesia cementing material, and has important influence on the comprehensive utilization of magnesite resources. The improvement of the light-burned magnesia production equipment is an effective way for breaking through the technical bottleneck of the development of the light-burned magnesia in China.

For a while, the production of the light-burned magnesium oxide in China continues to use the traditional reflection kiln for production, and has the advantages of small yield, large energy consumption, serious pollution, high labor intensity and low automation degree; the production mode takes blocky magnesite as a raw material, has small specific surface area, is easy to cause the conditions of over-burning on the surface and under-burning inside, and leads to unstable product quality. In recent years, the production of light-burned magnesia by suspension calcination of magnesite has come into the field of people, and because magnesite powder is used as a raw material, the method has the characteristics of uniform calcination, stable product quality, high activity, continuous production and the like.

The Chinese patent document with publication number CN208218696U discloses a light-burned MgO suspension calcination production device, which comprises a raw material bin, a cyclone preheating cylinder, a suspension calciner, three sets of combustion systems, a suspension cooling cylinder, a fluidized bed, a sleeve type water-cooled screw conveyor, a finished product bin and the like, can realize the accurate partition calcination of different active magnesium oxides, and has stable product quality; the device has carried out certain utilization to the flue gas waste heat, but has great problem to the waste heat utilization of product, does not utilize the heat of product in the suspension cooling section of thick bamboo, carries out waste heat recovery to the heat of the product that the cooling back temperature has reduced a lot on the contrary, and the waste heat that can utilize like this is very little, and waste heat recovery is not significant.

Chinese patent publication No. CN106007415A discloses a complete set of apparatus for preparing high-activity light-burned magnesia by suspension flash, which comprises a feeding device, a material preheating device, a suspension calciner, a product cooling device, and an exhaust gas treatment device; the complete equipment takes magnesite powder as a raw material, the materials are sequentially preheated, suspended calcined and cooled, the raw material is preheated by smoke, and the product preheats combustion-supporting air, so that the preliminary waste heat recovery is realized, the burning heat consumption of light-burned magnesia is reduced, the operating environment is improved, and the production efficiency is high; however, the device has some problems in the aspect of flue gas waste heat utilization, a process of directly mixing with cold air and performing heat exchange in a cyclone separator is adopted in the aspect of product waste heat recovery, and the operation enables combustion-supporting air to carry a large amount of products to re-enter a calcining furnace, so that the part of products are over-burnt, and the overall quality of the products is finally influenced.

Chinese patent publication No. CN104176757A discloses a suspension calcination process for light calcium carbonate, which comprises preheating, calcination, and carbonization steps, wherein the preheating step preheats the raw material using high-temperature flue gas generated in the calcination step as a heat source, and preheats combustion air using high-temperature products generated in the calcination step; however, the patent still adopts a gas-material direct contact process in the aspect of product waste heat recovery, and certain influence is generated on the product quality.

SUMMERY OF THE UTILITY MODEL

Utility model purpose:

the utility model provides a suspension is calcined and is prepared integrated equipment of light-burned magnesia, its aim at solve the waste heat recovery rate difference that current light-burned magnesia calcining equipment exists, the inhomogeneous problem of product quality.

The technical scheme is as follows:

a raw material bin of the device is communicated with a flash dryer, the flash dryer is communicated with a raw material multistage preheating device, the raw material multistage preheating device is respectively communicated with a suspension calcining furnace, a waste gas treatment device and a gas material separation device, the waste gas treatment device is respectively communicated with the suspension calcining furnace and a smoke exhaust device, the suspension calcining furnace is also respectively communicated with the gas material separation device and a product heat recovery device, the gas material separation device is communicated with a transition bin, the transition bin is communicated with the product heat recovery device, and the product heat recovery device is communicated with the product bin.

The raw material multi-stage preheating device comprises a first-stage preheating cyclone, a second-stage preheating cyclone and a third-stage preheating cyclone, a gas material outlet of the flash evaporation dryer is communicated with a gas material inlet of the first-stage preheating cyclone, a gas outlet of the first-stage preheating cyclone is communicated with the bag-type dust collector and the waste gas treatment device, a material outlet of the first-stage preheating cyclone is communicated with a gas material inlet of the second-stage preheating cyclone, a gas outlet of the second-stage preheating cyclone is communicated with an air inlet of the flash evaporation dryer, a material outlet of the second-stage preheating cyclone is communicated with a gas material inlet of the third-stage preheating cyclone, a gas outlet of the third-stage preheating cyclone is communicated with a gas material inlet of the second-stage preheating cyclone, a material outlet of the third-stage preheating cyclone is communicated with a gas material inlet.

The gas material separation device comprises a first-stage recovery cyclone and a second-stage recovery cyclone, a gas material inlet of the first-stage recovery cyclone is communicated with a gas material outlet of the suspension calcining furnace, a gas outlet of the first-stage recovery cyclone is communicated with a gas material inlet of the second-stage recovery cyclone, a gas outlet of the second-stage recovery cyclone is communicated with a gas material inlet of the multi-stage preheating device, and a material outlet of the first-stage recovery cyclone and a material outlet of the second-stage recovery cyclone are communicated with an inlet of the product heat recovery device.

The product heat recovery device comprises a primary heat exchanger and a secondary heat exchanger, wherein an air cold side inlet of the primary heat exchanger is connected with combustion air, an air hot side outlet of the primary heat exchanger is communicated with an air cold side inlet of the secondary heat exchanger, and an air hot side outlet of the secondary heat exchanger is communicated with a burner of the suspension calcining furnace.

The furnace body of the suspension calcining furnace is divided into an upper suspension calcining section and a lower heat preservation section, and a gas material outlet pipe is arranged between the suspension calcining section and the lower heat preservation section; the side wall of the upper part of the suspension calcining section is provided with a burner which is arranged along the tangential direction of the circumference of the suspension calcining section; the top of the suspension calcining section is provided with a secondary air and preheated material inlet device, the upper end of the secondary air and preheated material inlet device is provided with a preheated material inlet pipe and a secondary air inlet pipe, the preheated material inlet pipe and the secondary air inlet pipe are communicated in the secondary air and preheated material inlet device, and the bottom of the secondary air and preheated material inlet device is of a tubular structure with a wide inner cavity and a narrow outlet;

a material distribution cone is also arranged in the preheating material inlet pipe, one end of the material distribution cone, which penetrates out of the preheating material inlet pipe, is connected with a material distribution cone rapping device, and the material distribution cone rapping device is fixed at the top of the suspension calciner or on a secondary air and preheating material inlet device;

the inlet of the preheating material inlet pipe is positioned above the secondary air inlet pipe, and the included angle alpha between the axis of the preheating material inlet pipe and the vertical direction is 40-50 degrees; the axis of the middle part of the preheating material inlet pipe is superposed with the vertical direction, and the outlet of the preheating material inlet pipe is positioned above the outlets of the secondary air inlet device and the preheating material inlet device;

the diameter of the part of the distributing cone extending out of the preheating material inlet pipe is gradually increased from top to bottom, the distributing cone is of a horn-shaped structure, and one side of the horn-shaped part facing the preheating material inlet pipe is a smooth curved surface.

The first-stage heat exchanger and the second-stage heat exchanger are identical in structure and formed by stacking a plurality of heat exchange modules, each heat exchange module is formed by sequentially arranging a plurality of heat exchange plates, a flow channel is formed between each heat exchange plate and each heat exchange plate, and the flow channels of the materials and the combustion air are arranged at intervals in an alternating mode.

The inner wall of the flow passage is provided with a bulge; the materials and the combustion air in the first-stage heat exchanger and the second-stage heat exchanger adopt a counter-flow mode.

A secondary air fan is arranged on a pipeline communicated with the suspension calciner and the waste gas treatment device, a system fan is arranged on a pipeline communicated with the smoke exhaust device and a combustion-supporting air fan is arranged on a pipeline for introducing combustion-supporting air into the suspension calciner;

a secondary air valve is also arranged on a pipeline between the waste gas treatment device and the secondary air fan, a flue gas valve is also arranged on a pipeline between the system fan and the smoke exhaust device, and a combustion-supporting air valve is also arranged on a pipeline between the combustion-supporting air fan and the suspension calciner.

Has the advantages that:

the utility model provides a high-efficient, automatic, have flue gas and the complete sets of device of light-burned magnesia of magnesite powder production is calcined in suspension of material waste heat recovery.

a) The powder with small particle size and large specific surface area is adopted for calcination, the production period is short, the calcination is uniform, and the product quality is uniform and stable.

b) Through the utilization of the waste heat of the flue gas, the temperature of the raw materials can be raised to 400-550 ℃ after the raw materials are preheated by the preheating device step by step, the heat with the low-level calorific value of the fuel of about 22% can be recovered, and the energy consumption of the suspension calciner is reduced.

c) And taking part of the flue gas as secondary air distribution to return to the suspension calciner for adjusting the temperature and the air quantity of the flue gas and reducing the energy consumption of the suspension calciner.

d) The technical scheme of the dividing wall type heat exchanger is adopted to utilize the waste heat of the product, so that the mixing of materials and gas is avoided, the product can be directly discharged to a storage bin after being cooled, meanwhile, the combustion air is preheated to 100-200 ℃, the combustion temperature of the fuel is improved, and the heat of about 4% of the low-level calorific value of the fuel is recovered.

e) The utility model discloses a suspension calcining furnace has overcome the restriction of present suspension calcining magnesite production light-burned magnesia equipment to the high gas velocity of flow, can suspend and calcine under lower gas velocity of flow, and the gas material stroke shortens, and partial material accomplishes in the furnace body and keeps warm after the suspension is calcined, and the sintering is even, product activity is high, the steady quality, and device calorific loss is little, efficient.

To sum up, the utility model provides a waste heat recovery rate that current light-burned magnesia calcining equipment exists is poor, the inhomogeneous problem of product quality, the utility model discloses can show the energy consumption that reduces the burning furnace is forged in the suspension.

Drawings

FIG. 1 is a schematic view of the suspension calcination production apparatus for light-burned magnesia of the present invention;

FIG. 2 is a schematic structural diagram of a straight-barrel type suspension calciner;

FIG. 3 is a schematic view showing the arrangement direction of burners of a straight-barrel type suspension calciner;

FIG. 4 is a schematic structural view of a secondary air and preheated material inlet device of the straight-tube type suspension calciner;

FIG. 5 is a schematic diagram of the front side of a heat exchanger used in the product heat recovery unit;

FIG. 6 is a schematic side view of a heat exchanger used in the product heat recovery unit;

FIG. 7 is a schematic front view of a heat exchange module;

FIG. 8 is a schematic side view of a heat exchange module;

FIG. 9 is a schematic view of a cross-sectional view A-A of a heat exchange module;

FIG. 10 is a flow chart of the suspension calcination process for light-burned magnesia of the present invention;

reference numerals: 1 raw material bin, 2 flash dryer, 2-1 gas outlet I, 3 primary preheating cyclone, 3-1 gas inlet I, 3-2 gas outlet I, 3-3 material outlet I, 4 bag dust collector, 4-1 gas inlet I, 4-2 gas outlet II, 4-3 material outlet II, 5 secondary preheating cyclone, 5-1 gas outlet III, 5-2 gas inlet II, 5-3 material outlet III, 6 tertiary preheating cyclone, 6-1 gas inlet III, 6-2 gas outlet IV, 6-3 material outlet IV, 7 suspension calciner, 7-1 gas inlet IV, 7-2 gas outlet II, 7-3 material outlet V, 8 secondary heat exchanger, 9 secondary air blower, 10 primary recovery cyclone, 10-1 gas inlet V, 10-2 gas outlet V, 10-3 material outlet VI, 11 secondary recovery cyclone, 11-1 gas inlet VI, 11-2 gas outlet VI, 11-3 material outlet VII, 12 transition bin, 13 primary heat exchanger, 14 combustion air fan, 15 combustion air valve, 16 product bin, 17 waste gas treatment device, 17-1 gas inlet II, 17-2 gas outlet VII, 18 secondary air valve, 19 system fan, 20 flue gas valve, 21 smoke exhaust device, 22 kiln body, 23 suspension calcining section, 24 heat preservation section, 25 secondary air and preheating material inlet device, 26 preheating material inlet pipe, 27 secondary air inlet pipe, 28 burner nozzle, 29 gas material outlet pipe, 30 material outlet pipe, 31 air cold side inlet, 32 air hot side outlet, 33 material inlet, 34 material cold side outlet, 35 material inlet bin, 36 heat exchange module, 37 heat exchange plates, 38 light-burned magnesia powder runners, 39 preheated air runners, 39-1 holes, 40 distribution cones and 41 distribution cone rapping devices.

Detailed Description

The present invention will be further explained with reference to the accompanying drawings.

In the existing process for producing light-burned magnesia by suspension calcination of magnesite powder, flue gas and light-burned magnesia products have higher temperature when leaving the calciner, and waste heat has high utilization value.

And (3) waste heat utilization: combustion-supporting air is preheated through the primary heat exchanger 13 and the secondary heat exchanger 8 in sequence, enters the suspension calciner 7 through the burner 28, is mixed with fuel and then is combusted to generate high-temperature flue gas, and the high-temperature flue gas provides heat for the decomposition of magnesite in the suspension calciner 7; the flue gas is discharged out of the suspension calciner 7 from a gas material outlet pipe 29, the dust content is obviously reduced after the flue gas passes through a primary recovery cyclone 10 and a secondary recovery cyclone 11, and the flue gas enters a raw material multistage preheating device and is subjected to flash evaporation drying, preheating and drying. After the flue gas discharged by the multi-stage preheating device passes through the bag-type dust collector 4 and the waste gas treatment device 17, one part of the flue gas enters the smoke exhaust device 21 through the system fan 19, and the other part of the flue gas returns to the suspension calcining furnace 7 through the secondary air fan 9 to be used as secondary air for adjusting the temperature and the air quantity of the flue gas. The design of the multi-stage preheating device, the flash dryer and part of the flue gas reflux ensures that the flue gas waste heat discharged by the suspension calciner 7 is fully utilized; the product heat recovery device adopts a modularized dividing wall type heat exchanger, so that the heat of the material is fully recovered, the heat of the material is reduced, the temperature of combustion air is increased, and the direct contact between the combustion air and the product is avoided.

A device for preparing light-burned magnesium oxide by suspension calcination comprises a raw material bin 1, a flash dryer 2, a raw material multi-stage preheating device, a suspension calciner 7, a gas-material separation device, a product heat recovery device, a fan system, a bag-type dust collector 4, a waste gas treatment device 17 and a product bin 16; the device is characterized in that a feed opening of a raw material bin 1 of the device is communicated with a feed opening of a flash dryer 2, a gas outlet I2-1 of the flash dryer 2 is communicated with a gas inlet I3-1 of a multistage preheating device, a gas outlet III 5-1 of the multistage preheating device is communicated with an air inlet of the flash dryer 2, a material outlet IV 6-3 of the multistage preheating device is communicated with a gas inlet IV 7-1 of a suspension calciner 7, a gas outlet II 7-2 of the suspension calciner 7 is communicated with a gas inlet V10-1 of a gas-material separating device, a material outlet V7-3 of the suspension calciner 7 is communicated with a material hot side inlet 33 of a product heat recovery device, a gas outlet VI 11-2 of the gas-material separating device is communicated with a gas inlet III 6-1 of the multistage preheating device, a material outlet VI 10-3 and a material outlet VII 11-3 of the gas-material separating device are connected with a transition bin 12, the transition bin 12 is communicated with a material hot side inlet 33 of the product heat recovery device, and a material cold side outlet 34 of the product heat recovery device is communicated with the product bin 16; the gas outlet I3-2 of the multistage preheating device is also communicated with a gas inlet I4-1 of a bag-type dust collector 4, the gas outlet II 4-2 of the bag-type dust collector 4 is communicated with a gas inlet II 17-1 of a waste gas treatment device 17, the gas outlet VII 17-2 of the waste gas treatment device 17 is communicated with a smoke exhaust device 21, and meanwhile, the gas outlet VII 17-2 of the waste gas treatment device 17 is also communicated with a gas material inlet IV 7-1 of a suspension calcining furnace 7; the combustion air is connected to the burners 28 of the suspension calciner 7 via a product heat recovery device.

The raw materials in the raw material bin 1 are powdery. The powdery raw materials have small particle size and large specific surface area, are fully calcined in the suspension calciner 7, and have short production period, uniform calcination and uniform and stable product quality.

The material trend is as follows:

powdery materials enter a flash evaporation dryer 2 from a raw material bin 1 for drying, then enter a raw material multi-stage preheating device for heat exchange with recovered high-temperature flue gas, the temperature of the raw materials (materials) is improved, specifically, the powdery materials enter a primary preheating cyclone 3, a small amount of materials enter a bag-type dust remover 4 from the primary preheating cyclone 3 and then return to the primary preheating cyclone 3, a large amount of materials enter a secondary preheating cyclone 5, a tertiary preheating cyclone 6 and a suspension calcining furnace 7 from the primary preheating cyclone 3 in sequence, part of the materials directly enter a product heat recovery device (a secondary heat exchanger 8) from the suspension calcining furnace 7, part of the materials enter a gas-material separation device from the suspension calcining furnace 7, specifically enter a primary recovery cyclone 10, part of the materials enter a transition bin 12 from the primary recovery cyclone 10 and then enter a product heat recovery device (a primary heat exchanger 13) for full recovery, and part of, then the product enters a transition bin 12 and a product heat recovery device (a primary heat exchanger 13) in sequence, and the final product material enters a product bin 16 from the heat recovery device (the primary heat exchanger 13 and a secondary heat exchanger 8). The product heat recovery device adopts a modularized dividing wall type heat exchanger, so that the heat of the material is fully recovered, the heat of the material is reduced, the temperature of combustion air is increased, and the direct contact between the combustion air and the product is avoided.

Gas trend:

the combustion-supporting gas is discharged from a product heat recovery device (sequentially passes through a primary heat exchanger 13 and a secondary heat exchanger 8), the temperature of the combustion-supporting gas is increased by utilizing the waste heat of the product, so that the temperature of the combustion-supporting gas entering a suspension calciner 7 is high, the energy consumption in the suspension calciner 7 is reduced, the generated high-temperature flue gas carrying combustion products enters a gas-material separation device, specifically, a primary recovery cyclone 10 and a secondary recovery cyclone 11 are sequentially entered, and then sequentially enter a tertiary preheating cyclone 6, a secondary preheating cyclone 5, a flash evaporation dryer 2, a primary preheating cyclone 3, a bag-type dust collector 4 and a waste gas treatment device 17, namely, the materials and the high-temperature flue gas are fully separated through a multi-stage gas-material separation device to recover the materials, so that the content of the materials carried by the high-temperature flue gas is remarkably reduced, the high-temperature flue gas enters a raw material multi-stage preheating, the material temperature is increased, and the heat of the high-temperature flue gas is fully utilized. Then the flue gas discharged by the raw material multistage preheating device enters a bag-type dust collector 4, the materials carried in the recovered flue gas enter the raw material multistage preheating device, and finally the flue gas enters a waste gas treatment device 17, and the high-temperature waste heat part in the waste gas treatment device 17 is used as secondary air to flow back to the suspension calciner 7 for adjusting the temperature and the air quantity of the flue gas and reducing the energy consumption in the suspension calciner 7; and part enters the smoke exhaust device 21 to be exhausted. The design of the multi-stage preheating device, the flash evaporation dryer and part of the flue gas reflux ensures that the flue gas waste heat discharged by the suspension calcining furnace 7 is fully utilized.

The raw material multi-stage preheating device enables the residual heat of flue gas to be fully utilized, the raw material multi-stage preheating device comprises a primary preheating cyclone 3, a secondary preheating cyclone 5 and a tertiary preheating cyclone 6, a gas material outlet I2-1 of a flash evaporation dryer 2 is communicated with a gas material inlet I3-1 of the primary preheating cyclone 3, a gas outlet I3-2 of the primary preheating cyclone 3 is communicated with a gas inlet I4-1 of a bag-type dust collector 4, a material outlet I3-3 of the primary preheating cyclone 3 is communicated with a gas material inlet II 5-2 of the secondary preheating cyclone 5, a gas outlet III 5-1 of the secondary preheating cyclone 5 is communicated with an air inlet of the flash evaporation dryer 2, a material outlet III 5-3 of the secondary preheating cyclone 5 is communicated with a gas material inlet III 6-1 of the tertiary preheating cyclone 6, a gas outlet IV 6-2 of the tertiary preheating cyclone 6 is communicated with a gas material inlet II 5-2 of the secondary preheating cyclone 5, and a material outlet IV 6-3 of the three-stage preheating cyclone 6 is communicated with a gas material inlet IV 7-1 of the suspension calciner 7, and a gas material inlet III 6-1 of the three-stage preheating cyclone 6 is communicated with a gas outlet VI 11-2 of the gas material separation device.

The gas-material separation device enables the materials which are mixed by the smoke and the materials in the suspension calciner 7 and are not subjected to heat insulation to be subjected to gas-material separation again, the materials enter the suspension calciner 7 again for calcination, the smoke passes through the raw material multistage preheating device and enters the flash evaporation dryer 2 for drying, and the materials enter the transition bin for heat insulation operation. The gas material separation device comprises a primary recovery cyclone 10 and a secondary recovery cyclone 11, a gas material inlet V10-1 of the primary recovery cyclone 10 is communicated with a gas material outlet II 7-2 of the suspension calciner 7, a gas outlet V10-2 of the primary recovery cyclone 10 is communicated with a gas material inlet VI 11-1 of the secondary recovery cyclone 11, a gas outlet VI 11-2 of the secondary recovery cyclone 11 is communicated with a gas material inlet III 6-1 of the multi-stage preheating device, a material outlet VI 10-3 of the primary recovery cyclone 10 and a material outlet VII 11-3 of the secondary recovery cyclone 11 are both communicated with a transition bin 12, the transition bin 12 is communicated with an inlet of the product heat recovery device, and an outlet of the product heat recovery device is communicated with a product bin 16;

the product heat recovery device makes full use of the waste heat of the materials, the product heat recovery device comprises a primary heat exchanger 13 and a secondary heat exchanger 8, the product heat recovery device is used for heat exchange of powder and combustion-supporting air, the primary heat exchanger 13 and the secondary heat exchanger 8 are consistent in structure, and the primary heat exchanger 13 and the secondary heat exchanger 8 are sequentially connected end to end on a combustion-supporting air pipeline of the suspension calcining furnace 7. Specifically, an air cold side inlet 31 of a primary heat exchanger 13 is connected with combustion air, an air hot side outlet 32 of the primary heat exchanger 13 is communicated with the air cold side inlet 31 of a secondary heat exchanger 8, and the air hot side outlet 32 of the secondary heat exchanger 8 is communicated with a burner 28 of a suspension calciner 7; and a material hot side inlet 33 of the primary heat exchanger 13 is communicated with the transition bin 12, a material hot side inlet 33 of the secondary heat exchanger 8 is communicated with a material outlet IV 7-3 of the suspension calcining furnace 7, and material cold side outlets 34 of the primary heat exchanger 13 and the secondary heat exchanger 8 are both communicated with the product bin 16.

The combustion-supporting air is accelerated by the combustion-supporting air fan 14, enters the primary heat exchanger 13 to exchange heat with the material separated by the gas-material separation device, enters the secondary heat exchanger 8 to exchange heat with the material separated by the suspension calciner 7, and finally enters the burner 28 to provide the combustion-supporting air required by fuel combustion.

A secondary air fan 9 is arranged on a pipeline of the waste gas treatment device 17 communicated with the suspension calciner 7, a system fan 19 is arranged on a pipeline of the waste gas treatment device 17 communicated with the smoke exhaust device 21, and a combustion air fan 14 is arranged on a pipeline of the combustion air introduced into the suspension calciner 7; the overfire air blower 9, the system blower 19 and the combustion air blower 14 are used to provide motive power for gas movement. And part of the flue gas discharged by the waste gas treatment device 17 is returned to the suspension calciner as secondary air distribution for adjusting the temperature and the air volume of the flue gas, so that the energy consumption of the suspension calciner can be obviously reduced.

A secondary air valve 18 is also arranged on a pipeline between the waste gas treatment device 17 and the secondary air fan 9, and the secondary air valve 18 controls the flow of the flue gas which flows back to the suspension calciner by changing the opening degree of the valve, so that the temperature of the suspension calciner and the flow rate of the flue gas in the suspension calciner are controlled or adjusted; a flue gas valve 20 is also arranged on a pipeline between the system fan 19 and the smoke exhaust device 21, the flue gas valve 20 is used for controlling the flow of flue gas exhausted from the system, and is matched with the secondary air valve 18 to control the amount of the returned flue gas and maintain the pressure in the system to be stable; a combustion air valve 15 is further arranged on a pipeline between the combustion air fan 14 and the suspension calciner 7, and the combustion air valve 15 controls the air quantity entering the product heat recovery device by changing the opening of the valve, so that the combustion air quantity and the preheating temperature of the combustion air are adjusted according to the real-time production requirement.

The first-stage heat exchanger 13 and the second-stage heat exchanger 8 are similar to dividing wall type heat exchangers, the first-stage heat exchanger 13 and the second-stage heat exchanger 8 are identical in structure and are formed by stacking a plurality of heat exchange modules 36 in the vertical direction. The heat exchange module 36 is formed by sequentially arranging a plurality of heat exchange plates 37, the heat exchange plates 37 are used for separating materials and combustion-supporting air and are arranged in parallel according to a designed distance, preferably, an even number of heat exchange plates 37 are arranged in pairs, a flow channel is formed between each heat exchange plate 37 and each heat exchange plate 37, the flow channels of the materials and the combustion-supporting air are arranged at intervals in an alternating mode, namely, the flow channels of the materials, the combustion-supporting air, the materials and the combustion-supporting air are arranged at intervals and are alternately arranged in an alternating mode, so that the materials and the combustion-supporting air can be fully and uniformly contacted. The formed material flow channel is communicated up and down, the gas flow channel is sealed up and down, holes 39-1 are formed in the bottom and the top side face of the preheating air flow channel 39 and used for air entering and discharging, the section of the flow channel is rectangular, materials enter from the upper portion of the heat exchange module and are discharged from the lower portion of the heat exchange module, the movement directions of combustion air are opposite, two working media are not in contact and are not mixed, and heat exchange is conducted through the heat exchange plate 37. The number of the heat exchange modules can be adjusted according to the parameters of the yield, the temperature before and after material heat exchange and the like. The air cold side inlet 31 and the air hot side outlet 32 are cylindrical, and one side of the cylinder is provided with a row of circular tubular joints which are connected with holes 39-1 formed in the gas flow passage 39.

The heat exchange modules 36 are connected in series, specifically, the heat exchange module 36 at the lowest layer is connected with the air cold side inlet 31 through a pipe through an opening 39-1 at the bottom of the preheated air flow channel 39, the heat exchange module 36 at the uppermost layer is connected with the air hot side outlet 32 through a pipe through an opening 39-1 at the top of the preheated air flow channel 39, and between the adjacent heat exchange modules 36, the opening 39-1 at the top of the preheated air flow channel 39 of the heat exchange module 36 at the lower side is connected with the opening 39-1 at the bottom of the preheated air flow channel 39 of the heat exchange module 36 at the upper side through a U-shaped pipe, so that the adjacent two heat exchange modules 36 are penetrated.

The combustion air enters and fills the cylinder of the air cold side inlet 31 under the pushing action of the combustion air blower 14, then enters the preheated air flow channel 39 through the pipe connected with the hole 39-1 at the bottom of each preheated air flow channel 39 and completes the heat exchange with the material, and then enters the bottom of the next module air 36 from the opening 39-1 at the upper part of the preheated air flow channel 39 along the U-shaped pipe or enters the air hot side outlet 32 along the pipe.

As shown in fig. 8, the two sides of the heat exchange plates 37 are provided with protrusions, one side is provided with relatively dense protrusions, one side is provided with relatively sparse protrusions, and the protrusions between two adjacent heat exchange plates 37 are arranged in a staggered manner. The flow channel between two adjacent heat exchanger plates 37 is rectangular in cross-section. The bulges are used for increasing the contact area of the heat exchange plate 37 and materials or combustion air and improving the heat exchange effect, and the bulges arranged on the inner wall of the light-burned magnesia powder flow passage 38 for circulating the materials are fewer, so that the influence of the bulges on the circulation of the materials is avoided; the number of the bulges arranged on the inner wall of the preheating air flow channel 39 for circulating the combustion-supporting air is large, the influence of the bulges on the gas is small and can be ignored, and the contact surface area of the heat exchange plate 37 and the combustion-supporting air can be increased as much as possible, so that the heat exchange is facilitated.

The materials and the combustion air in the primary heat exchanger 13 and the secondary heat exchanger 8 both adopt a counter-flow mode. The material enters from the upper part of the heat exchanger, the lower part of the heat exchanger is discharged, the combustion-supporting air enters from the lower part of the heat exchanger, the upper part of the heat exchanger is discharged, and the two working media are not in direct contact, so that the material cannot permeate into the combustion-supporting air, the normal work of the burner can be ensured, and the calcined product is prevented from entering the calciner again; the number of the heat exchange modules can be adjusted according to the operating parameters so as to meet the requirement of heat recovery.

As shown in fig. 2, the suspension calciner 7 is in a straight-tube type, a furnace body 22 of the suspension calciner 7 is divided into an upper straight-tube type suspension calcination section 23 and a lower funnel-shaped heat preservation section 24, a gas material outlet pipe 29 is arranged between the suspension calcination section 23 and the lower funnel-shaped heat preservation section 24, the gas material outlet pipe 29 is used for connecting a gas material separation device, and the gas material outlet pipe 29 avoids the limitation of high gas flow velocity in the gas material ascending process and avoids the equipment complexity; the lateral wall of the upper part of the suspension calcining section 23 is provided with a burner 28, the burner 28 is connected with a gas pipeline and a combustion-supporting air pipeline, the gas is used for providing fuel for the calcining process, and the combustion-supporting air assists the combustion of the gas. A material outlet IV 7-3 is arranged at the bottom of the heat preservation section 24. The top of the suspension calcining section 23 is provided with a secondary air and preheated material inlet device 25, the upper end of the secondary air and preheated material inlet device is provided with a preheated material inlet pipe 26 and a secondary air inlet pipe 27, the preheated material inlet pipe 26 is used for communicating with a material outlet III 6-4, the secondary air inlet pipe 27 is used for communicating with a gas outlet VII 17-1, the lower end of the secondary air and preheated material inlet device is provided with a secondary air and preheated material inlet device 25, the preheated material inlet pipe 26 and the secondary air inlet pipe 27 are communicated in the secondary air and preheated material inlet device 25, the secondary air and preheated material inlet device 25 is of a tubular structure with a wide inner cavity and a narrow outlet. After secondary air enters the secondary air and preheating material inlet device 25, the inner cavity reaches a turbulent flow state and blows away materials, so that the materials are fully contacted with high-temperature flue gas in the suspension calcining furnace 7 and are fully calcined.

The burners 28 are arranged such that the gas is arranged in a tangential direction of the circumferential direction of the furnace body 22. Namely, the gas entering the furnace body 22 through the burner 28 enters the suspension calcining section 23 along the tangential direction of the circumference of the furnace body 22 to form a rotational flow carrying the material, so that the material completes the decomposition reaction in the rotational flow movement process, the decomposition reaction speed is improved, and the reaction is more sufficient; thereby effectively avoiding the conditions that the product is over-burnt outside and loses activity and the inside is under-burnt to cause incomplete decomposition of the raw materials.

The upper part of the heat preservation section 24 is in a straight cylinder shape, and the lower part of the heat preservation section 24 is in a funnel shape with gradually reduced sectional area. Because the material in the suspension calcining section 23 completes the decomposition reaction in the rotational flow movement process, the lower part of the heat preservation section 24 is funnel-shaped, which is more beneficial to the sedimentation of the material, so as to preserve the heat of the settled material.

The secondary air and preheating material inlet device comprises a preheating material inlet pipe 26, a secondary air inlet pipe 27, a distribution cone 40, a distribution cone rapping device 41 and a secondary air and preheating material inlet device 25, wherein the secondary air and preheating material inlet device is respectively communicated with the preheating material inlet pipe 26 and the secondary air inlet pipe 27, namely the secondary air and preheating material inlet device is a common inlet of preheating materials and preheating air secondary air, the preheating material inlet pipe 26 is arranged inside the secondary air inlet pipe 27, an inlet of the preheating material inlet pipe is positioned above the secondary air inlet pipe 27, an included angle alpha between the axis of the preheating material inlet pipe and the vertical direction is 45 degrees, the axis of the middle part is superposed with the vertical direction, an outlet is positioned above the secondary air and preheating material inlet device 25, the distribution cone 40 is also arranged in the preheating material inlet pipe 26, one end of the distribution cone 40 with a curved surface extends out of the outlet of the preheating material inlet pipe 26, and the other end passes through the pipe wall, and is connected with the material distributing cone rapping device 41, the material distributing cone rapping device 41 is fixed on the top of the furnace body 22 or on the secondary air and preheating material inlet device, plays a role in fixing the material distributing cone 40, and simultaneously performs periodic striking on the material distributing cone 40, the lower part of the preheating material inlet pipe 26 and the bottom of the secondary air inlet pipe 27 are provided with the secondary air and preheating material inlet device 25, and the secondary air and preheating material inlet device 25 at the bottom of the secondary air and preheating material inlet device are of a tubular structure with a wide inner cavity and a narrow outlet, so as to form a gradually reduced channel. The tapered channel makes the secondary air rotate in the secondary air and preheating material inlet device 25 of the secondary air and preheating material inlet device, the secondary air blows and evenly mixes the materials, and then the materials enter the suspension calcining section 23 to be calcined, thereby being beneficial to the materials to fully contact with combustion air in the suspension calcining section 23 and fully calcine.

The part of the distributing cone 40 extending out of the preheating material inlet pipe 26 is gradually increased in diameter from top to bottom, the overall appearance is similar to a horn-shaped structure, and one side of the horn-shaped preheating material inlet pipe 26 is a smooth curved surface. When the material moves to the position right above the secondary air and preheating material inlet device 25, the material falls under the action of gravity, and after passing through the curved surface of the distributing cone 40, the moving direction is changed from vertical downward to annular oblique downward movement, so that the dispersity of the material is improved, and the mixing of the gas material in the preheating material inlet device 25 is promoted.

The material distribution cone rapping device 41 is an existing device capable of providing periodic rapping, and one end of the material distribution cone rapping device 41 is connected with a motor, and the other end is connected with the upper end of the material distribution cone 40. Cloth awl rapping device 41 has carried out the fixed action to cloth awl 40 on the one hand, and on the other hand cloth awl rapping device 41 utilizes the motor to provide power, drives the tup through transmission and carries out periodic rapping to cloth awl 40, and the cycle can shorten according to the increase of input, makes a small amount of powder of adhesion on cloth awl 40 surface drop to preheating material inlet device 25 through rapping, avoids the powder to silt up on cloth awl 40 and blocks up preheating material inlet tube 26.

At present, the smoke and material inlets of a suspension calciner are arranged at the bottom of a furnace body, materials move upwards along with the smoke, and in order to meet the requirement of pneumatic transmission, a high gas flow rate is generally required to be set, and considering the condition that mutual bonding particle sizes of magnesite powder materials are increased in the calcining process, the gas flow rate is generally set between 15 and 20m/s, and the calcining process requires more than 2s of time, so that the stroke of the gas materials in the calciner is long, generally more than 30m, and the whole height of the device is high; according to the device, the gas material inlet is arranged above the furnace body, the gas material moves downwards, the gas flow velocity is reduced to be lower than 5m/s, the gas material stroke is obviously shortened, and the height of the suspension calcining furnace 7 is controlled to be 12-17 m.

The preheated material and the secondary air are fully mixed at a secondary air and preheated material inlet device 25, and are converged through a gradually-reduced channel and then enter the furnace body 22 for calcination. The materials and the gas are premixed, so that the dispersity of the materials is improved, and the subsequent calcination is more uniform.

The process method of the device comprises the following steps:

the method comprises the following steps: the magnesite powder enters a flash dryer 2 from a raw material bin 1, and is dehydrated and dried by using flue gas conveyed from a gas outlet III 5-1 of a multi-stage preheating device to obtain dried magnesite powder;

step two: in the step one, the dried magnesite powder enters a multi-stage preheating device, and the multi-stage preheating device preheats the dried magnesite powder to obtain the preheated magnesite powder; the gas discharged by the multistage preheating device enters a waste gas treatment device 17 through a bag-type dust collector 4;

step three: the preheated magnesite powder in the step two enters a suspension calciner 7 for calcination and heat preservation, the magnesite powder is calcined to obtain a light-burned magnesia product, and the light-burned magnesia product subjected to heat preservation enters a product heat recovery device; the light burned magnesia which is not subjected to heat preservation enters a gas-material separation device along with the flue gas for further gas-material separation, the separated material enters a transition bin 12 for heat preservation, the material after heat preservation enters a product heat recovery device for cooling and preheating combustion air, and the material is cooled at the same time; respectively entering a primary heat exchanger 13 or a secondary heat exchanger 8 to preheat combustion air;

the temperature of the flue gas entering the suspension calciner is adjusted by controlling the supply amount of the fuel and the supply amount of the secondary air, so that the temperature of the flue gas in the suspension calciner 7 is controlled to be 1100-1300 ℃;

controlling the temperature of the flue gas and the temperature of the flue gas discharged from the suspension calciner by changing the mass flow ratio of the material feeding amount to the high-temperature flue gas, wherein the mass flow ratio of the material feeding amount to the flue gas in the suspension calciner 7 is controlled to be 1: 1.5-1: 2, and the temperature of the flue gas discharged from the suspension calciner 7 is controlled to be 700-800 ℃;

the temperature of the light burned magnesium oxide entering the product heat recovery device is 550-650 ℃, the temperature can be reduced to 200-300 ℃ after heat exchange of the product heat recovery device, and combustion air can be preheated to 100-200 ℃ from room temperature;

the temperature of the flue gas discharged through the fume extractor 21 is lower than 120 ℃.

Step four: and (3) cooling the materials after heat preservation in a product heat recovery device: and (3) the material after heat preservation in the third step enters a product heat recovery device, and the light calcined magnesia after cooling enters a product bin 16 to obtain a final magnesia product.

The method comprises the following specific steps:

the utility model discloses in adopt the powder that the particle diameter is little, specific surface is big for calcining, production cycle is short, calcine evenly, product quality is even stable. Flotation magnesite powder in a raw material bin 1 enters a flash evaporation dryer 2 through conveying equipment, the flotation magnesite powder in the flash evaporation dryer 2 is subjected to dehydration drying treatment through smoke introduced from a secondary preheating cyclone 5, the treated gas enters a primary preheating cyclone 3 from a gas outlet I2-1 of the flash evaporation dryer 2, most of the material is discharged from a material outlet I3-3 of the primary preheating cyclone 3 and enters the secondary preheating cyclone 5, and a small part of the material enters a bag-type dust collector 4 along with the gas and then returns to a gas inlet I3-1 of the primary cyclone 3; the material discharged from the material outlet I3-3 of the primary preheating cyclone 3 enters a secondary preheating cyclone 5, gas and material are separated through the secondary preheating cyclone 5, the smoke is discharged into the flash evaporation dryer 2 through the gas outlet III 5-1 by the secondary preheating cyclone 5 for preheating the material, and the material is discharged from the material outlet III 5-3 of the secondary preheating cyclone 5 and enters a tertiary preheating cyclone 6; the materials are preheated in the tertiary preheating cyclone 6 by the flue gas from the secondary recovery cyclone 11, and then the materials are sent into the suspension calciner 7; the magnesite powder completes decomposition reaction in the suspension calcining section of the suspension calcining furnace 7, part of the material is kept in the heat preservation section for heat preservation, the material after heat preservation enters the secondary heat exchanger 8, the dissipated heat is used for preheating combustion-supporting air, and the cooled material enters the product bin 16; the other part of the materials enter a primary recovery cyclone 10 and a secondary recovery cyclone 11 from a gas material outlet pipe sequentially along with high-temperature flue gas, the separated materials enter a transition bin 12 for heat preservation, and the heat-preserved materials enter a primary heat exchanger 13 for preheating combustion air and then enter a product bin 16.

The combustion-supporting air is preheated by the primary heat exchanger 13 and the secondary heat exchanger 8 in sequence, enters the burner 28, is mixed with fuel and then is combusted to generate high-temperature flue gas, and the high-temperature flue gas provides heat for the decomposition of magnesite in the suspension calcination section; the flue gas is discharged out of the suspension calciner 7 from a gas material outlet pipe 29, the dust content is obviously reduced after the flue gas passes through a primary recovery cyclone 10 and a secondary recovery cyclone 11, and the flue gas enters a raw material multistage preheating device, namely the raw material is preheated and dried after passing through a tertiary preheating cyclone 6, a secondary preheating cyclone 5, a flash evaporation dryer 2 and a primary preheating cyclone 3; after the flue gas is treated by the bag-type dust collector 4 and the waste gas treatment device 17, one part of the flue gas enters a smoke exhaust device 21 (chimney) through a system fan 19, and the other part of the flue gas returns to the suspension calciner through a secondary air fan 9 to be used as secondary air.

In the device, the generation amount of the flue gas can be controlled by adjusting the fuel amount, and the secondary air amount shunted from the flue gas is controlled, so that the temperature in the suspension calciner 7 and the gas flow rate are controlled; the gas-material mass ratio is adjusted to change the temperature of the calcined material discharged from the hearth, so that the calcined material meets the calcination requirement of the product.

Example 1

The feed opening of the raw material bin 1 is communicated with the feed opening of the flash dryer 2 through conveying equipment (equipment with conveying function such as the existing spiral feeder); an air inlet of the flash evaporation dryer 2 is communicated with a gas outlet III 5-1 of the secondary preheating cyclone 5, and a gas material outlet I2-1 of the flash evaporation dryer 2 is communicated with a gas material inlet I3-1 of the primary preheating cyclone 3; a gas outlet I3-2 of the primary preheating cyclone 3 is communicated with a gas inlet I4-1 of a bag-type dust collector 4, and a material outlet I3-3 of the primary preheating cyclone 3 is connected with a gas material inlet II 5-2 of the secondary preheating cyclone 5; a gas outlet II 4-2 of the bag-type dust collector 4 is connected with a gas inlet II 17-1 of the waste gas treatment device 17, and a material outlet II 4-3 of the bag-type dust collector 4 is communicated with a gas material inlet I3-1 of the primary preheating cyclone 3; a gas outlet VII 17-2 of the waste gas treatment device 17 is divided into two branches, one branch is connected with a smoke exhaust device 21 after passing through a system fan 19 and a smoke valve 20, and the other branch enters a hearth from a gas material inlet IV 7-1 at the top of the suspension calciner 7 through a secondary air valve 18 and a secondary air fan 9; a gas material inlet II 5-2 of the secondary preheating cyclone 5 is communicated with a material outlet I3-3 of the primary preheating cyclone 3 and a gas outlet IV 6-2 of the tertiary preheating cyclone 6, and a material outlet III 5-3 of the secondary preheating cyclone 5 is communicated with a gas material inlet III 6-1 of the tertiary preheating cyclone 6; a gas material inlet III 6-1 of the three-stage preheating cyclone 6 is communicated with a gas outlet VI 11-2 of the secondary recovery cyclone 11, and a material outlet IV 6-3 of the three-stage preheating cyclone 6 is communicated with a gas material inlet IV 7-1 of the suspension calciner 7; a gas material inlet VI 11-1 of the secondary recovery cyclone 11 is communicated with a gas outlet V10-2 of the primary recovery cyclone 10, and a material outlet VII 11-3 of the secondary recovery cyclone 11 is communicated to a transition bin 12; a gas material inlet V10-1 of the primary recovery cyclone 10 is communicated with a gas material outlet II 7-2 of the suspension calciner 7, a gas outlet V10-2 of the primary recovery cyclone 10 leads to a secondary recovery cyclone 11, and a material outlet VI 10-3 of the primary recovery cyclone 10 is communicated to a transition bin 12; an outlet of the transition bin 12 is communicated with a material inlet of the primary heat exchanger 13, and a material outlet 13-2 of the primary heat exchanger 13 is communicated to a product bin 16; the top of the suspension calciner 7 is provided with a secondary air and preheated material inlet device which is respectively communicated with a secondary air fan 9 and a material outlet IV 6-3 of the tertiary preheating cyclone 6; a burner 28 is installed on the side wall of the upper part of the suspension calciner 7, the burner 28 is provided with a gas inlet pipe and a combustion air inlet pipe, the combustion air inlet pipe successively passes through the primary heat exchanger 13 and the secondary heat exchanger 8, and a combustion air pipeline is provided with a valve 15 and a fan 14; the bottom of the suspension calciner 7 is provided with a material outlet V7-3, and the material outlet V7-3 is communicated with a secondary heat exchanger 8.

The process method comprises the following steps:

The temperature of the flue gas entering the suspension calciner is regulated by controlling the fuel supply amount and the secondary air supply amount, and in the embodiment, the temperature of the flue gas is controlled at 1300 ℃.

The temperature of the flue gas and the temperature of the material discharged from the suspension calciner are controlled by changing the mass flow ratio of the material feeding amount to the high-temperature flue gas, in the embodiment, the mass ratio is 1:2 (the material feeding amount: the flue gas mass flow), and the temperature of the discharged flue gas is 750 ℃ under the operation condition.

In the embodiment, the particle size of the magnesite powder is less than or equal to 75 mu m, the discharging temperature of the calcined material is 710 ℃, the average temperature of the light calcined magnesia entering a heat exchanger is 650 ℃, the temperature after heat exchange is 200 ℃, and combustion-supporting air is preheated to 125 ℃ from 20 ℃.

In this example, the flue gas discharge temperature was 120 ℃.

Natural gas is adopted in the embodiment (the lower heating value is 36000kJ/Nm calculated according to third-party detection data³) As fuel, 1Nm per combustion³The actual required air amount of the natural gas is 10.85Nm³Yield 11.88Nm³The combustion products of (1). Under the preheating condition of the embodiment, the theoretical combustion temperature is 1932 ℃, the heat loss is considered, and the temperature of the flue gas discharged from the burner is 1642 ℃. The secondary air coefficient is 0.32, corresponding to a flow rate of 3.80Nm³/Nm³I.e. ensuring that the temperature of the gas in the furnace is 1300 ℃ and 1Nm is burned³The amount of the flue gas to be refluxed is 3.80Nm³。

In this embodiment, the waste heat recovery amount and the corresponding ratio of each waste heat recovery device are shown in table 1, for example, the first column in the table is a waste heat recovery link (device) in the system; the second column is the heat recycled by a waste heat recycling link (device) when unit fuel is consumed; the third column is the proportion (heat exchange quantity/low-level heating quantity) of the heat quantity recovered by each link (device) relative to the low-level heating quantity of the fuel. For a device system with annual output of 30000t, the recovery amount of waste heat is about 7.45 multiplied by 10⁶kJ/year, corresponding to 26.5% of the energy contained in the fuel, with a flue gas reflux of 5.05X 10 for recovering heat⁵kJ/year, accounting for 6.8% of total recovery amount, and the product waste heat recovery device recovers 1.19 × 10 heat⁶kJ/year, accounting for 16.0% of total recovery, and the heat recovery of the raw material multi-stage preheating device is 2.66X 10⁶kJ/year, accounting for 35.7% of total recovery, and the heat recovered by flash drier is 2.66X 10⁶kJ/year, which accounts for 44.4% of the total recovery.

TABLE 1 the utility model discloses the waste heat recovery condition of each waste heat utilization link (device)

Waste heat recovery project	Heat exchange capacity (kJ/Nm)³)	Percentage of relative fuel calorific value (%)
			Flue gas reflux	627	1.8
Product waste heat recovery device	1483	4.1
			Raw material multi-stage preheating device	3308	9.2
Flash evaporation dryer	4109	11.4
			Total of	9527	26.5

In the embodiment, the adopted raw material parameters are as follows: water content of about 11-12%, MgO 47.5%; 0.22-0.6% of CaO; SiO 2₂ 0.17～0.2％；Fe₂O₃ 0.1～0.32；Al₂O₃0.05 to 0.1; the particle size was 75 μm.

The parameters of the product light-burned magnesia are as follows: 86.21 percent of MgO; active MgO 66.09%; 3.91 percent of CaO; SiO 2₂0.70％；Fe₂O₃ 1.08％；Al₂O₃0.4 percent, meets the index requirements of the brand CBM85 and the following brands in YB/T5206-2004 standard of ferrous metallurgy industry of the people's republic of China-light burned magnesium oxide.

Claims

1. The device for preparing light-burned magnesium oxide by suspension calcination is characterized in that:

a raw material bin (1) of the device is communicated with a flash dryer (2), the flash dryer (2) is communicated with a raw material multi-stage preheating device, the raw material multi-stage preheating device is respectively communicated with a suspension calcining furnace (7), an exhaust gas treatment device (17) and a gas material separation device, the exhaust gas treatment device (17) is respectively communicated with the suspension calcining furnace (7) and a smoke exhaust device (21), the suspension calcining furnace (7) is also respectively communicated with the gas material separation device and a product heat recovery device, the gas material separation device is communicated with a transition bin (12), the transition bin (12) is communicated with the product heat recovery device, and the product heat recovery device is communicated with a product bin (16).

2. The apparatus for preparing light-burned magnesium oxide by suspension calcination according to claim 1, wherein:

the raw material multi-stage preheating device comprises a first-stage preheating cyclone (3), a second-stage preheating cyclone (5) and a third-stage preheating cyclone (6), a gas material outlet of the flash evaporation dryer (2) is communicated with a gas material inlet of the first-stage preheating cyclone (3), a gas outlet of the first-stage preheating cyclone (3) is communicated with the bag-type dust collector (4) and the waste gas treatment device (17), a material outlet of the first-stage preheating cyclone (3) is communicated with a gas material inlet of the second-stage preheating cyclone (5), a gas outlet of the second-stage preheating cyclone (5) is communicated with an air inlet of the flash evaporation dryer (2), a material outlet of the second-stage preheating cyclone (5) is communicated with a gas material inlet of the third-stage preheating cyclone (6), a gas outlet of the third-stage preheating cyclone (6) is communicated with a gas material inlet of the second-stage preheating cyclone (5), a material outlet of the third-stage preheating cyclone (6, and a gas material inlet of the three-stage preheating cyclone (6) is communicated with a gas outlet of the gas material separation device.

3. The apparatus for preparing light-burned magnesium oxide by suspension calcination according to claim 1, wherein: the gas material separation device comprises a first-stage recovery cyclone (10) and a second-stage recovery cyclone (11), a gas material inlet of the first-stage recovery cyclone (10) is communicated with a gas material outlet of the suspension calcining furnace (7), a gas outlet of the first-stage recovery cyclone (10) is communicated with a gas material inlet of the second-stage recovery cyclone (11), a gas outlet of the second-stage recovery cyclone (11) is communicated with a gas material inlet of the multi-stage preheating device, and a material outlet of the first-stage recovery cyclone (10) and a material outlet of the second-stage recovery cyclone (11) are communicated with an inlet of the product heat recovery device.

4. The apparatus for preparing light-burned magnesium oxide by suspension calcination according to claim 1, wherein: the product heat recovery device comprises a primary heat exchanger (13) and a secondary heat exchanger (8), an air cold side inlet (31) of the primary heat exchanger (13) is connected with combustion air, an air hot side outlet (32) of the primary heat exchanger (13) is communicated with an air cold side inlet (31) of the secondary heat exchanger (8), and an air hot side outlet (32) of the secondary heat exchanger (8) is communicated with a burner (28) of the suspension calciner (7).

5. The apparatus for preparing light-burned magnesium oxide by suspension calcination according to claim 1, wherein: a furnace body (22) of the suspension calcining furnace (7) is divided into an upper suspension calcining section (23) and a lower heat preservation section (24), and a gas material outlet pipe (29) is arranged between the suspension calcining section (23) and the lower heat preservation section (24); the side wall of the upper part of the suspension calcining section (23) is provided with a burner (28), and the burner (28) is arranged along the tangential direction of the circumference of the suspension calcining section (23); the top of the suspension calcining section (23) is provided with a secondary air and preheated material inlet device (25), the upper end of the secondary air and preheated material inlet device (25) is provided with a preheated material inlet pipe (26) and a secondary air inlet pipe (27), the preheated material inlet pipe (26) and the secondary air inlet pipe (27) are communicated in the secondary air and preheated material inlet device (25), and the bottom of the secondary air and preheated material inlet device (25) is of a tubular structure with a wide inner cavity and a narrow outlet;

a material distribution cone (40) is also arranged in the preheating material inlet pipe (26), one end of the material distribution cone (40) penetrating out of the preheating material inlet pipe (26) is connected with a material distribution cone rapping device (41), and the material distribution cone rapping device (41) is fixed on the top of the suspension calciner (7) or on a secondary air and preheating material inlet device (25);

the inlet of the preheating material inlet pipe (26) is positioned above the secondary air inlet pipe (27), and an included angle alpha between the axis of the preheating material inlet pipe (26) and the vertical direction is 40-50 degrees; the axis of the middle part of the preheating material inlet pipe (26) is superposed with the vertical direction, and the outlet of the preheating material inlet pipe (26) is positioned above the outlet of the secondary air and preheating material inlet device (25); the part of the distributing cone (40) extending out of the preheating material inlet pipe (26) is gradually increased in diameter from top to bottom and is of a trumpet-shaped structure, and one side of the trumpet-shaped part facing the preheating material inlet pipe (26) is a smooth curved surface.

6. The apparatus for preparing light-burned magnesium oxide by suspension calcination according to claim 1, wherein: the primary heat exchanger (13) and the secondary heat exchanger (8) are identical in structure and formed by stacking a plurality of heat exchange modules (36), each heat exchange module (36) is formed by sequentially arranging a plurality of heat exchange plates (37), a flow channel is formed between each heat exchange plate (37) and each heat exchange plate (37), and the flow channels of the materials and the combustion air are arranged at intervals in an alternating mode.

7. The apparatus for preparing light-burned magnesium oxide by suspension calcination according to claim 6, wherein: the inner wall of the flow passage is provided with a bulge; the materials and the combustion air in the primary heat exchanger (13) and the secondary heat exchanger (8) adopt a counter-flow mode.

8. The apparatus for preparing light-burned magnesium oxide by suspension calcination according to claim 1, wherein: a secondary air fan (9) is arranged on a pipeline of the waste gas treatment device (17) communicated with the suspension calciner (7), a system fan (19) is arranged on a pipeline of the waste gas treatment device (17) communicated with the smoke exhaust device (21), and a combustion air fan (14) is arranged on a pipeline of the combustion air introduced into the suspension calciner (7);

a secondary air valve (18) is also arranged on a pipeline between the waste gas treatment device (17) and the secondary air fan (9), a flue gas valve (20) is also arranged on a pipeline between the system fan (19) and the smoke exhaust device (21), and a combustion air valve (15) is also arranged on a pipeline between the combustion air fan (14) and the suspension calciner (7).