CN113603373B

CN113603373B - Fluidized calcining lime kiln and lime production process

Info

Publication number: CN113603373B
Application number: CN202111018765.4A
Authority: CN
Inventors: 李国安; 李想
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-09-01
Filing date: 2021-09-01
Publication date: 2022-06-03
Anticipated expiration: 2041-09-01
Also published as: CN113603373A

Abstract

The invention discloses a fluidized bed calcining lime kiln and a lime production process, wherein the lime kiln comprises a fluidized bed kiln, a raw material conveying mechanism, a raw coal conveying mechanism and a finished product processing mechanism, wherein the raw material conveying mechanism and the raw coal conveying mechanism are arranged on two sides of the fluidized bed kiln; and discloses a production process of boiling calcined lime, which comprises the following steps: crushing limestone into limestone powder with the granularity less than 2mm by a crushing machine and a roller press, wherein the granularity of the limestone powder is less than 2 mm; step two, raw coal preparation: crushing raw coal particles into raw coal powder with the granularity of less than 5mm through a crushing structure; step three, lime calcination: weighing limestone powder and raw coal powder, and conveying the limestone powder and the raw coal powder into a combustion chamber in a kiln body; air is conveyed into the combustion chamber through the air blast assembly and the air distribution assembly, and limestone powder is calcined; and step four, processing a finished product. Improves the production efficiency of lime and reduces environmental pollution.

Description

Fluidized bed calcining lime kiln and lime production process

Technical Field

The invention relates to the technical field of lime production, in particular to a fluidized bed calcination lime kiln and a lime production process.

Background

Lime, also known as lime, is popular with lime and has the main chemical component of calcium oxide (CaO). The lime is widely applied to metallurgy, chemical industry, light industry, building materials, refractory materials, thermal power generation, agriculture and environmental protection engineering, such as alkali making, bleaching powder, sugar making, calcium carbide, fertilizers, disinfectants, sewage purification and the like. According to statistics, the annual lime consumption of metallurgical enterprises reaches more than 1.5 hundred million tons, the annual consumption of the chemical industry also exceeds 1.0 hundred million tons, and the annual demand of the building material industry exceeds 3.0 hundred million tons. These industries have been the most rapidly developing industries in recent years. Annual production is essentially increasing at a rate of over 20%. The main materials and auxiliary materials which can be needed by the lime-lime kiln are not correspondingly increased, so that the lime tension is caused, the explosion of the lime kiln is stimulated, and the environment is seriously polluted. Therefore, in order to treat the pollution of the soil burning kiln, a lime kiln with a new modern technology must be implemented to solve the problem of demand.

The lime is used as a basic raw material for production, is directly related to the quality of industrial products and the production cost, and influences the benefit of the products. But the quality of the common lime produced by many small and medium enterprises in China is poor at present, the activity is only 180-200 ml (4N-HCl, 10min), the CaO content is only 70-80%, and the raw and over-burnt rate reaches or even exceeds 30%. The method can only be applied to sintering processes of metallurgical enterprises or some low-end chemical enterprises, and cannot enter high-end markets at all.

In general standard quicklime, the content of calcium oxide is more than 90%, the raw and over-burnt rate is less than 10%, and the active calcium is more than 300%. Conventional lime firing uses solid fuels including: coal and coke. With the increasing awareness of energy conservation and the national requirements for environmental protection, gaseous fuels such as: various combustible gases such as blast furnace gas, coke oven gas, natural gas, generator gas, methane and the like are used for firing lime. The lime kiln is divided into a mixed burning kiln according to fuel: i.e. burning solid fuels, coke breeze, coal, etc. Gas-fired kiln: the gas burning kiln comprises blast furnace gas, coke oven gas, calcium carbide tail gas, generator gas, natural gas and the like. According to the kiln type, there are vertical kiln, rotary kiln, sleeve kiln, double-chamber kiln, beam lime kiln, etc.

With the regeneration of the kiln types, the rapid development and the technical progress of the lime industry are powerfully promoted. The lime calcining process is developing towards a new technology with environment protection, energy saving function, mechanization and higher automation degree, and large-scale and intelligent production. However, no matter how these limekilns change, they are consistent and not fundamentally changed based on the principle of the earth kiln calcining lime. There is still a high demand for fuel. High production cost, high energy consumption, great waste and great pollution.

Disclosure of Invention

The invention aims to provide a boiling calcining lime kiln and a lime production process, which aim to solve the problems in the prior art.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a boiling calcining lime kiln which comprises a boiling kiln, a raw material conveying mechanism, a raw coal conveying mechanism and a finished product processing mechanism, wherein the raw material conveying mechanism and the raw coal conveying mechanism are arranged on two sides of the boiling kiln.

The fluidized bed kiln comprises a kiln body, wherein the bottom end of the kiln body is fixedly communicated with an air distribution assembly, the air distribution assembly is communicated with an air blowing assembly, a combustion chamber, a fluidized bed chamber, a heat exchange area, a decomposition reaction area and a decomposition area are sequentially arranged in the kiln body from bottom to top, and the decomposition area above the kiln body is communicated with a gooseneck.

The raw material conveying mechanism comprises a roller press, a V-shaped powder concentrator and a storage bin communicated with a discharge port of the V-shaped powder concentrator, a limestone feeding assembly is arranged at a feed port of the roller press, a discharge port of the roller press and a feed port of the V-shaped powder concentrator are connected with a first material conveying assembly in an outgoing mode, and a first metering feeding assembly is connected between the storage bin and the fluidized bed kiln; the raw coal conveying mechanism comprises a coal storage bin, and a second metering feeding assembly is connected between the coal storage bin and the fluidized bed kiln.

The finished product processing mechanism comprises a double-pipe cyclone dust collector communicated with the gooseneck and a plurality of groups of discharge pipes communicated with the combustion chamber, the double-pipe cyclone dust collector and the discharge pipes are communicated with a grate cooler together, and a finished product conveying belt is arranged below the grate cooler.

Preferably, the air distribution assembly comprises an air distribution plate, an equal-pressure chamber is fixedly connected below the air distribution plate, and the equal-pressure chamber is communicated with an air outlet of the air blowing assembly; the air distribution plate is provided with a plurality of groups of through holes, an air cap is fixedly connected inside the through holes, the air cap comprises a cylinder clamped inside the through holes and a conical cover cap fixedly connected to the top end of the cylinder, the conical cover cap is arranged on one side of the combustion chamber, and a plurality of groups of air outlets are formed in one side of the combustion chamber of the cylinder; the wind distribution plate sequentially comprises a fireproof pouring layer, a heat insulation material layer and a substrate layer from top to bottom.

Preferably, the kiln body is of a cylindrical structure, the kiln body comprises a shell, a lining and a heat preservation layer fixedly arranged between the shell and the lining, the shell is made of a steel plate, the lining is made of wear-resistant refractory materials or refractory pouring materials, and the heat preservation layer is formed by stacking heat insulation materials such as diatomite heat preservation bricks, calcium silicate boards and fiber mats.

Preferably, a raw material inlet and a raw coal inlet are respectively formed in two side walls of the boiling chamber of the kiln body, and the raw material inlet and the raw coal inlet are respectively communicated with the first metering and feeding component and the second metering and feeding component; the side wall of the kiln body in the combustion chamber is provided with a gas fuel reserved opening and/or a liquid fuel reserved opening.

Preferably, the gooseneck is fixedly connected with the kiln body through a flange, and two ends of the gooseneck are fixedly connected with expansion joints.

Preferably, the flue gas outlet end of the double-tube cyclone dust collector is fixedly communicated with the feed inlet end of a V-shaped powder concentrator, the air outlet end of the V-shaped powder concentrator is fixedly communicated with a C2-level cyclone preheater, the air outlet end of the C2-level cyclone preheater is fixedly communicated with a C-level double-tube cyclone preheater, and the C-level double-tube cyclone preheater is communicated with a bag type dust collector; and the material separating ports on the bag type dust collector, the C-level double-pipe cyclone preheater and the C2-level cyclone preheater are communicated with the storage bin through a conveying belt.

Preferably, a cold area waste gas outlet of the grate cooler is respectively communicated with an air inlet of the air blowing assembly and a feed inlet of the V-shaped powder concentrator; the air blowing assembly comprises a high-pressure air blower, and an air outlet of the high-pressure air blower is communicated with an air inlet of the air distribution assembly through an air duct.

A boiling calcined lime production process is based on any one of the above boiling calcined lime kilns, and comprises the following steps:

step one, raw material preparation: crushing limestone into limestone particles with the particle size of less than 25mm by a crushing machine; grinding limestone particles by a roller press to form limestone powder, wherein the granularity of the limestone powder is less than 2 mm; the limestone powder is scattered by the V-shaped powder concentrator and then enters a storage bin;

step two, raw coal preparation: crushing raw coal particles into raw coal powder with the granularity of less than 5mm through a crushing structure, and storing the raw coal powder in a coal storage bin;

step three, lime calcination: limestone powder and raw coal powder are weighed by the first metering feeding component and the second metering feeding component from the storage bin and the coal storage bin respectively and are conveyed into a combustion chamber in the kiln body; air is conveyed into the combustion chamber through the air blast assembly and the air distribution assembly, and limestone powder is calcined;

step four, finished product treatment: carrying out gas-dust separation on the dusty gas conveyed by the gooseneck through a double-pipe cyclone dust collector, and cooling the finished products subjected to treatment by a grate cooler; and (4) after the calcination, the finished product staying in the kiln body enters a grate cooler through a discharge pipe, and after the finished product is cooled by the grate cooler, a finished product conveying belt is carried out and conveyed to be stored in a warehouse.

Preferably, in the third step, the temperature of the boiling chamber is controlled to be 900-1000 ℃, and the height of the boiling chamber is between 1.0 and 1.5 meters.

Preferably, in the fourth step, the dust-containing gas generated in the gooseneck is subjected to gas-dust separation by a double-tube cyclone dust collector, the separated waste gas and the cold zone waste gas of the grate cooler enter the V-shaped powder concentrator to scatter and dry limestone powder, the waste gas generated by the V-shaped powder concentrator enters the C2-level cyclone preheater to dry materials, and the waste gas generated by the C2-level cyclone preheater dries the materials in the C-level double-tube cyclone preheater.

The invention discloses the following technical effects: the invention arranges the air distribution component at the bottom of the kiln body, the air scattered in each direction blown by a plurality of air caps on the air distribution component is polymerized into the scorching limestone powder which is supported by an air cushion bed and is fluidized by dozens of times and is rapidly mixed with the raw coal powder, the mixture jumps up and down in a high temperature state, the limestone powder and the raw coal powder are mutually rubbed, collided and cracked, the temperature of a boiling layer is generally controlled at 900 plus material and 1100 ℃, the height of the boiling layer is about 1.0 to 1.5 meters when the material runs, so the whole material layer is equivalent to a large heat storage pool, the limestone carries out violent heat exchange by virtue of high temperature, and calcium carbonate in the limestone is decomposed into calcium oxide and carbon dioxide quicklime in a short time.

Limestone powder and raw coal powder entering the fluidized bed kiln are heated and then are rolled by high-temperature airflow to move upwards along the kiln body, and heat exchange is carried out at the same time, because the materials are influenced by bulges on the inner wall of the kiln body in the rising process, the materials continuously flow in a convection mode and move back and forth, so that the retention time of the materials is increased, the materials are circularly decomposed, and the time for calcium carbonate to be heated and decomposed is sufficiently ensured. The coarse limestone particles fall into the fluidized bed to roll up and down and collide violently, and the limestone particles absorb heat and decompose continuously.

After being heated, the powdery material entering the fluidized bed is rolled by high-temperature airflow, enters a heat exchange area, a decomposition reaction area and a decomposition area on the upper part of the kiln body to the gooseneck, and is decomposed while moving upwards, and the dust-containing gas discharged from the kiln is collected by a cyclone separator, and then the product is cooled and put in storage, so that the energy consumption is reduced, and the heat efficiency is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic view of the structure of a boiling calcination lime kiln of the present invention;

FIG. 2 is a flow chart of the lime production process of the present invention;

FIG. 3 is a schematic view of the fluidized bed kiln of the present invention;

FIG. 4 is a schematic structural view of the air distribution assembly of the present invention;

FIG. 5 is a schematic view of the structure of the hood of the present invention;

FIG. 6 is a production flow chart of lime powder according to the present invention;

FIG. 7 is a flow chart of the process for producing raw coal fines in accordance with the present invention;

the device comprises a boiling kiln 1, a kiln body 101, a housing 1011, a lining 1012, an insulating layer 1013, an air distribution component 102, an air distribution plate 1021, an air distribution plate 1022, an isostatic chamber 1023, a through hole 1024, an air cap 1025, an air outlet 1025, a blower component 103, a combustion chamber 104, a boiling chamber 105, a heat exchange zone 106, a decomposition reaction zone 107, a decomposition zone 108, a gooseneck 109, a raw material inlet 110, a raw coal inlet 111, an expansion joint 112, a roller press 201, a V-shaped powder concentrator 202, a storage bin 203, a limestone feeding component 204, a first material conveying component 205, a first metering feeding component 206, a cyclone preheater 207, a C2-grade cyclone preheater 208, a C1-grade double-pipe cyclone preheater 209, a bag-type dust collector 301, a coal storage bin 302, a second metering feeding component 401, a double-pipe dust collector 402, a discharge pipe 403, a grate cooler and a finished product conveying belt 404.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Referring to fig. 1-7, the invention provides a fluidized bed calcination limekiln, which comprises a fluidized bed kiln 1, a raw material conveying mechanism and a raw coal conveying mechanism which are arranged at two sides of the fluidized bed kiln 1, and a finished product processing mechanism;

the fluidized bed kiln 1 comprises a kiln body 101, the bottom end of the kiln body 101 is fixedly communicated with an air distribution assembly 102, the air distribution assembly 102 is communicated with an air blast assembly 103, a combustion chamber 104, a fluidized bed chamber 105, a heat exchange area 106, a decomposition reaction area 107 and a decomposition area 108 are sequentially arranged in the kiln body 101 from bottom to top, and a bulge is arranged between each two adjacent chambers and/or areas; the decomposition area 108 above the kiln body 101 is communicated with a gooseneck 109.

The raw material conveying mechanism comprises a roller press 201, a V-shaped powder concentrator 202 and a storage bin 203 communicated with a discharge port of the V-shaped powder concentrator 202, a limestone feeding assembly 204 is arranged at a feed port of the roller press 201, the discharge port of the roller press 201 and a feed port of the V-shaped powder concentrator 202 are connected with a first material conveying assembly 205, and a first metering and feeding assembly 206 is connected between the storage bin 203 and the fluidized bed kiln 1; the raw coal conveying mechanism comprises a coal storage bin 301, and a second metering and feeding assembly 302 is connected between the coal storage bin 301 and the boiling kiln 1.

The finished product processing mechanism comprises a double-pipe cyclone dust collector 401 communicated with the gooseneck 109 and a plurality of groups of discharge pipes 402 communicated with the combustion chamber 104, the double-pipe cyclone dust collector 401 and the discharge pipes 402 are communicated with a grate cooler 403 together, a finished product conveying belt 404 is arranged below the grate cooler 403, and the grate cooler 403 is a shell fully-closed mechanism, so that energy loss is prevented, dust leakage is prevented, and the environment is polluted.

In a further optimized scheme, the air distribution assembly 102 comprises an air distribution plate 1021, an equal-pressure chamber 1022 is fixedly connected below the air distribution plate 1021, and the equal-pressure chamber 1022 is communicated with an air outlet of the air blowing assembly 103; the air distribution plate 1021 is provided with a plurality of groups of through holes 1023, an air cap 1024 is fixedly connected inside the through holes 1023, and the air cap 1024 is formed by casting and finish machining heat-resistant alloy steel; the spraying direction of the air outlet 1025 is not perpendicular to the height direction of the kiln body 101, so that the spraying direction of the air outlet 1025 is perpendicular to the height of the kiln body 101. The air distribution plate 1021 comprises a fireproof pouring layer, a heat insulation material layer and a substrate layer from top to bottom in sequence, and the substrate layer and a housing of an isostatic chamber 1022 are both made of common steel plates.

According to the further optimized scheme, the kiln body 101 is of a cylindrical structure and comprises an outer shell 1011, an inner lining 1012 and a heat insulation layer 1013 fixedly arranged between the outer shell 1011 and the inner lining 1012, the outer shell 1011 is a steel plate, the inner lining 1012 is an abrasion-resistant refractory material or a fire-resistant pouring material, and the heat insulation layer 1013 is formed by stacking heat insulation materials such as diatomite heat insulation bricks, calcium silicate boards and fiber mats. The service cycle of the lime kiln at high temperature is ensured, and the shell of the kiln body 101 is effectively ensured to be in a low-temperature state all the time.

In a further optimization scheme, the kiln body 101 is respectively provided with a raw material inlet 110 and a raw coal inlet 111 on two side walls of the boiling chamber 105, and the raw material inlet 110 and the raw coal inlet 111 are respectively communicated with the first metering and feeding component 206 and the second metering and feeding component 302; the kiln body 101 is provided with a gas fuel reserving opening and/or a liquid fuel reserving opening on the side wall of the combustion chamber 104.

In a further optimized scheme, the gooseneck 109 is fixedly connected with the kiln body 101 through a flange, and two ends of the gooseneck 109 are fixedly connected with expansion joints 112.

According to a further optimized scheme, the smoke outlet end of the double-tube cyclone dust collector 401 is fixedly communicated with the feed inlet end of the V-shaped powder concentrator 202, the air outlet end of the V-shaped powder concentrator 202 is fixedly communicated with a C2-grade cyclone preheater 207, the air outlet end of the C2-grade cyclone preheater 207 is fixedly communicated with a C1-grade double-tube cyclone preheater 208, and the C1-grade double-tube cyclone preheater 208 is communicated with a bag type dust collector 209; the separated material openings of the bag type dust collector 209, the C1-grade double-pipe cyclone preheater 208 and the C2-grade cyclone preheater 207 are communicated with the storage bin 203 through a conveyor belt.

In a further optimized scheme, a cold area waste gas outlet of the grate cooler 403 is respectively communicated with an air inlet of the air blowing assembly 103 and a feed inlet of the V-shaped powder concentrator 202; the air blowing component 103 comprises a high-pressure air blower, and an air outlet of the high-pressure air blower is communicated with an air inlet of the air distribution component 102 through an air duct.

The boiling calcining lime kiln adopts three automatic control systems of computer control, electric transmission control and instrument control, wherein the electric system adopts PLC control configuration control, the monitoring part adopts complete instrument signal data, and advanced telecommunication systems are adopted among all subsystems and remote stations. The bottom of the kiln is provided with a plurality of discharging points, a discharging opening is made of heat-resistant steel, an electric actuator is controlled, and the discharging speed is automatically controlled by the sensing change of the temperature and the pressure in the kiln. The system realizes electromechanical integrated control and thermotechnical control intelligent design, and the thermotechnical control cabinet selects an intelligent digital display meter. The temperature, coal, air flow and pressure of the kiln can be detected by instruments, related thermal signals are connected with an upper computer through a PLC, a kiln operator can master working conditions according to detection data and receiving increasing and decreasing switch signals, and the requirements of remote central control and field control can be met through adjustment operation of a configured PLC control system. The whole operation control system is simple and easy to master, and the labor intensity is low; the required amount of personnel is small. The large-scale lime production is facilitated, the equipment structure is compact, the factory floor area is small, the unit production cost is low, the comprehensive energy consumption is low, and the engineering investment is about 50% of that of other kiln types on the same scale.

A boiling calcined lime production process comprises the following steps:

step one, raw material preparation: crushing limestone into limestone particles with the particle size of less than 25mm by a crushing machine; grinding limestone particles by a roller press 201 to form limestone powder, wherein the granularity of the limestone powder is less than 2 mm; the V-shaped powder concentrator 202 scatters the limestone powder and then enters the storage bin 203.

The limestone for mining is crushed by a double-rotor hammer crusher, and when the feed particle size is less than or equal to 1000mm, the discharge particle size is less than or equal to 25 mm. The limestone out of the crusher is conveyed to a limestone pre-homogenization yard by a rubber belt conveyor, or if the ingredients of the limestone are uniform, the quality is stable, and the pre-homogenization yard can be omitted.

The rate of decomposition of limestone is closely related to temperature and particle size. Therefore, the calcination of limestone by grinding from lump to fine particles is the best method for effectively increasing the decomposition reaction rate. Limestone coarse materials from a storage yard are conveyed into a roller press 201 through a rubber belt conveyor to be extruded, the shape of the materials extruded by the roller press 201 is sheet powder with the granularity less than or equal to 2mm, the powder block materials are conveyed into a V-shaped powder concentrator 202 through a lifter, simultaneously material cakes and dried materials are scattered, the separated coarse particle materials fall into a storage bin 203, and the materials are metered and fed into a kiln under the control of an electronic scale.

High-temperature mixed gas from kiln discharge tail gas and cooling lime enters the V-shaped powder concentrator 202, the scattered materials and dried materials in the V-shaped powder concentrator 202 enter the C2-level cyclone preheater 207 and the C1-level double-pipe cyclone preheater 208 together with the powdery materials in sequence to continuously exchange heat with the materials, the preheated powder is collected and conveyed into the kiln, and the discharge concentration of dust-containing gas is less than or equal to 30mg/Nm after being purified by the bag dust collector³And is discharged to the atmosphere.

Step two, raw coal preparation: raw coal particles are crushed into raw coal powder with the granularity of less than 5mm through a crushing structure and stored in the coal storage bin 301. The coal car is transported into the factory, and is loaded into the unloading pit by the loader, and is sent into the coal pre-homogenizing storage yard by the plate type feeder and the rubber belt conveyor. The method is characterized by comprising the following steps of arranging a long coal pre-homogenization storage yard, carrying out pre-homogenization treatment on raw coal in a top-stacking end-fetching mode, and conveying the raw coal out of the pre-homogenization storage yard to a crusher for crushing by a rubber belt conveyor to obtain the granularity of less than or equal to 5 mm; enters the coal storage bin 301 for standby.

Step three, lime calcination: limestone powder and raw coal powder are weighed by the first metering and feeding component 206 and the second metering and feeding component 302 from the storage bin 203 and the coal storage bin 301 respectively and are conveyed into the combustion chamber 104 in the kiln body 101; air is sent into the combustion chamber 104 through the air blowing assembly 103 and the air distribution assembly 102, and the limestone powder is calcined.

The limestone powder and the raw coal powder which are respectively metered enter the fluidized bed kiln 1 at the same time. After entering, raw materials and fuel are injected into a hearth from air outlets 1025 of a plurality of air caps 1024 on an air distribution plate 1021 through an isobaric chamber 1022 with the air blast assembly 103, air scattered in all directions is polymerized into burning limestone powder and raw coal powder which are dozens of times above fluidization supported by an air cushion bed, the limestone powder and the raw coal powder are rapidly mixed and jump up and down in a high-temperature state, and are mutually rubbed, collided and cracked, rapidly heated and ignited, the temperature of a boiling layer is generally controlled at 900-.

Limestone powder and raw coal powder entering the fluidized bed kiln are heated and then are rolled up by high-temperature airflow to move upwards along the kiln body, and heat exchange is carried out at the same time, because the materials are influenced by bulges on the inner wall of the kiln body in the rising process, the materials continuously flow in a convection mode and move back and forth, so that the retention time of the materials is increased, and the materials are circularly decomposed, the retention time of the materials in the kiln body is more than 5 seconds due to the design of the kiln body, and the time for heating and decomposing calcium carbonate is sufficiently ensured. The coarse particle limestone falls into the boiling bed to roll up and down and collide violently, and the limestone absorbs heat and decomposes continuously. The calcination time can be flexibly controlled, the calcined lime is discharged along a plurality of groups of discharge pipes 402 at the bottom of the air distribution plate, and the discharged lime is conveyed and stored in a warehouse by a heat-resistant rubber belt conveyor after being cooled by a grate cooler 403.

Step four, finished product treatment: the dust-containing gas conveyed by the gooseneck 109 is subjected to gas-dust separation by a double-pipe cyclone dust collector 401, and the finished products after treatment are cooled by a grate cooler 403; and after the calcination, the finished product staying in the kiln body 101 enters the grate cooler 403 through the discharge pipe 402, and after the finished product is cooled by the grate cooler 403, the finished product is conveyed to a finished product conveyor belt 404 and is conveyed to be stored in a warehouse. The lime discharged from the kiln enters a finished product round warehouse for storage through a hoister, a lime bulk loading device is arranged on the side of the warehouse, a truck loader is used for tank trucks to leave a factory in bulk, a packaging machine is arranged at the bottom of the warehouse, and the packaged bagged lime is directly conveyed into the finished product warehouse through a bag unloading conveying system.

In the fourth step, the dust-containing gas generated in the gooseneck 109 is subjected to gas-dust separation by the double-pipe cyclone dust collector 401, the separated waste gas and the waste gas in the cold area of the grate cooler 403 enter the V-type powder concentrator 202 to scatter limestone powder and dry the limestone powder, the waste gas generated by the V-type powder concentrator 202 enters the C2-level cyclone preheater 207 to dry the material, and the waste gas generated by the C2-level cyclone preheater 207 dries the material in the C1-level double-pipe cyclone preheater 208.

The main component of limestone is calcium carbonate, while the main component of lime is calcium oxide. The basic principle of lime burning is to decompose calcium carbonate in limestone into calcium oxide and carbon dioxide quicklime by means of high temperature. It has the reaction formula:

CaCO2＝CaO+CO2-695kcal·kg^-1

the traditional technological process is that limestone and fuel are put into a lime kiln (if gas fuel is sent in through a pipeline and a burner) to be preheated to 850 ℃ and then start to be decomposed, and then calcination is finished at 1200 ℃, and after cooling, the limestone and the fuel are discharged out of the kiln. Thus completing the production of the quicklime product. Different kilns have different preheating, calcining, cooling and ash discharging modes. However, the process principle is the same: the quality of the raw materials is high, and the quality of the lime is good; the fuel has high heat value and low quantity consumption; limestone particle size is in direct proportion to calcination time; the quicklime activity is inversely proportional to the calcination time and the calcination temperature. Due to the process limitation of calcining the blocky limestone, the calcining time and the calcining temperature are extremely difficult to control, so the phenomena of raw burning and overburning are serious, and the activity quality of the lime is influenced.

The fuel used by the boiling kiln is mainly poor coal, the heating value is more than or equal to 4180kj/kg, and the boiling kiln has wide fuel adaptability, sufficient combustion and high efficiency. The solid fuel with QyDW of 4180KJ/kg (1000kcal/kg) can be combusted, and the production cost of a factory is reduced. Meanwhile, gas or liquid fuel such as natural gas, coal gas (blast furnace gas), oil and the like can also be used. The method has important significance for solving the problem of reasonable utilization of coal resources in China and reducing secondary environmental pollution caused by abandonment and landfill of a large amount of various coal gangues and inferior coals generated by coal mining.

Any lime kiln with the existing structure can only be used for one type of solid, gas and liquid fuel correspondingly, the kiln type is also specially designed for different fuel types, and the same type of lime kiln cannot be suitable for various types of fuel. The lime-burning fuel is wide in range, solid fuel, gas fuel and liquid fuel. Coke and coal gas are commonly used. But more environment-friendly and more beneficial to energy saving are coal gas, including blast furnace gas, converter gas, coke oven gas, calcium carbide tail gas (coal gas), generator gas and the like. Because the gas fuels are waste utilization and have the property of circular economy, a large amount of energy can be saved, the environment is protected, and the economic benefit of enterprises is improved. Solves the problem that different fuels are suitable for the same lime kiln.

The temperature of the boiling layer is generally controlled at 900-1100 ℃, when the furnace runs, the height of the boiling layer is about 1.0-1.5 m, the added fuel only accounts for 8%, so the whole material layer is equivalent to a large 'heat storage tank', the original (combustion) material is mixed with dozens of times of scorching particles after entering the boiling layer, the mixture jumps up and down in a high-temperature state, is subjected to mutual friction, collision and cracking, is rapidly heated and is ignited and combusted, and the coal particles are burnt from small to large; the boiling kiln can maintain stable combustion even for poor fuel with much ash, much water and low volatile matter, and the combustion intensity is 3-4 times of that of a common combustion furnace.

When the calcination temperature is constant, the particle size of the limestone is proportional to the time of the decomposition reaction, and at 1000 ℃, the time of the decomposition reaction of limestone particles having a particle size of 0.1mm is not longer than 1 second. Limestone entering a fluidized bed kiln is basically pulverized after being rolled by a roller press, the particle size of the limestone is less than or equal to 2mm and less than or equal to 80 microns and less than or equal to 50 percent, the pulverized material entering the fluidized bed is heated and then is rolled by high-temperature airflow to enter a heat exchange area, a decomposition reaction area and a decomposition area at the upper part of a kiln body to a gooseneck, decomposition is completed while ascending, dust-containing gas after being discharged from the kiln is collected by a cyclone separator, and then products are cooled and stored in a warehouse, so that the energy consumption is reduced, and the heat efficiency is improved. The coarse particle limestone rolls up and down in the fluidized bed, collides violently and absorbs heat continuously for cyclic decomposition. The coarse particles of limestone with the particle size of 2mm can be completely decomposed only by staying on the boiling bed for 30 seconds at the temperature of 1000 ℃. The calcined lime is discharged out along the discharge opening at the bottom of the air distribution plate, cooled and stored in a warehouse.

The fluidized bed kiln changes the problems that the calcining zone of the common blocky mixed lime kiln is easy to drift and difficult to control, and the lime quality is influenced by the phenomena of raw burning and over-burning. The fuel in the fluidized bed furnace is fully combusted, the burnout rate is more than or equal to 99 percent, and the combustion metering and the regulation are flexible and accurate. The uniform temperature distribution in the calcining process in the kiln is ensured, the airflow flows and is uniformly distributed in the kiln without dead angles, the heat exchange efficiency is high under the condition of calcium carbonate powder, the reaction speed is high, the decomposition rate is high, and the temperature and material retention can be flexibly adjusted; the technical measures effectively avoid the unburnt and overburnt limestone, and ensure the stable quality of lime products, energy conservation and consumption reduction. The combustion has the characteristics of large contact area between air and raw materials, high relative movement speed, long retention time of the raw materials in a fluidized bed, easy regulation, high combustion and heat exchange speed, high burnout rate, stable temperature field, uniform calcination, high decomposition rate and the like, greatly overcomes the bad phenomena of unburnt or overburnt limestone caused by uneven heating, and ensures that the lime product has high activity index.

Due to the rapid calcination and rapid cooling, the lime has high activity and active performance; the indexes of the lime taken out of the kiln are as follows:

1. the volume density is small: 1.4-1.8 g/cm³

2. High porosity: > 50%

3. Large specific surface area: 1.6-2.0 m²/g

4. Fine crystal grains: 3 μm

5. The activity degree is high: not less than 300ml (4N-HL-10min)

6. The purity of CaO is high, generally more than 90%.

Because the whole calcining process of the boiling kiln is equivalently carried out in a sealed container, the discharge points are concentrated, and the greatest benefit is that the dust removal is convenient. The flue gas is discharged from a kiln top flue gas pipeline, and is subjected to secondary dust removal purification and desulfurization treatment to achieve harmless and pollution-free standard emission.

Because the kiln has full fuel combustion, the system basically completes the whole production process in a sealed state, the kiln body has good heat preservation, small heat dissipation loss, full recovery of waste heat for secondary air use, the exhaust temperature of waste gas is controlled below 100 ℃, and the thermal efficiency of the system is more than 90 percent; therefore, the energy consumption is reduced to the lowest, the lime firing heat consumption is less than or equal to 850kc 1/kg, and the energy consumption is reduced by 10-30% compared with that of any other forms of lime kilns. The energy-saving effect is obvious.

The fluidized bed furnace and the calcining process thereof can be used for calcining lime and other industrial raw materials or products. Such as: industrial gypsum, kaolin, carbide slag, iron concentrate, sulfur concentrate, siderite, copper, zinc, lead leaching waste residue and the like. Because the discharge speed can be adjusted at will, the equipment can adjust the retention time of the materials in the roasting furnace according to production requirements when being used as the roasting kiln, thereby achieving the production effect.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. A boiling calcining lime kiln is characterized in that: comprises a boiling kiln (1), a raw material conveying mechanism, a raw coal conveying mechanism and a finished product processing mechanism, wherein the raw material conveying mechanism and the raw coal conveying mechanism are arranged on two sides of the boiling kiln (1);

the fluidized bed furnace (1) comprises a furnace body (101), the bottom end of the furnace body (101) is fixedly communicated with an air distribution assembly (102), the air distribution assembly (102) is communicated with an air blowing assembly (103), a combustion chamber (104), a boiling chamber (105), a heat exchange area (106), a decomposition reaction area (107) and a decomposition area (108) are sequentially arranged in the furnace body (101) from bottom to top, and the decomposition area (108) above the furnace body (101) is communicated with a gooseneck pipe (109);

the raw material conveying mechanism comprises a roller press (201), a V-shaped powder concentrator (202) and a storage bin (203) communicated with a discharge hole of the V-shaped powder concentrator (202), a limestone feeding assembly (204) is arranged at a feed hole of the roller press (201), a first material conveying assembly (205) is connected between the discharge hole of the roller press (201) and the feed hole of the V-shaped powder concentrator (202), and a first metering feeding assembly (206) is connected between the storage bin (203) and the fluidized bed kiln (1); the raw coal conveying mechanism comprises a coal storage bin (301), and a second metering and feeding assembly (302) is connected between the coal storage bin (301) and the fluidized bed kiln (1);

the finished product processing mechanism comprises a double-pipe cyclone dust collector (401) communicated with the gooseneck (109) and a plurality of groups of discharge pipes (402) communicated with the combustion chamber (104), the double-pipe cyclone dust collector (401) and the discharge pipes (402) are communicated with a grate cooler (403) together, and a finished product conveying belt (404) is arranged below the grate cooler (403);

the air distribution assembly (102) comprises an air distribution plate (1021), an equal-pressure chamber (1022) is fixedly connected below the air distribution plate (1021), and the equal-pressure chamber (1022) is communicated with an air outlet of the air blowing assembly (103); the air distribution plate (1021) is provided with a plurality of groups of through holes (1023), an air cap (1024) is fixedly connected inside the through holes (1023), the air cap (1024) comprises a cylinder clamped inside the through holes (1023) and a conical cover cap fixedly connected to the top end of the cylinder, the conical cover cap is arranged on one side of the combustion chamber (104), and a plurality of groups of air outlets (1025) are formed in one side of the combustion chamber (104) of the cylinder; the wind distribution plate (1021) comprises a fireproof pouring layer, a heat insulation material layer and a substrate layer from top to bottom in sequence.

2. The boiling calcined lime kiln of claim 1, wherein: the kiln body (101) is cylindrical structure, the kiln body (101) includes shell (1011), inside lining (1012) and fixed heat preservation (1013) of setting between shell (1011) and inside lining (1012), shell (1011) is the steel sheet, inside lining (1012) are wear-resistant refractory material or fire-resistant castable, heat preservation (1013) are thermal-insulated materials such as diatomaceous earth insulating brick, calcium silicate board and fibrofelt and pile up and form.

3. The boiling calcined lime kiln of claim 1, wherein: the kiln body (101) is provided with a raw material inlet (110) and a raw coal inlet (111) on two side walls of the boiling chamber (105), and the raw material inlet (110) and the raw coal inlet (111) are respectively communicated with a first metering and feeding component (206) and a second metering and feeding component (302); the side wall of the combustion chamber (104) of the kiln body (101) is provided with a gas fuel reserved opening and/or a liquid fuel reserved opening.

4. The boiling calcined lime kiln of claim 1, wherein: the gooseneck (109) is fixedly connected with the kiln body (101) through a flange, and expansion joints (112) are fixedly connected to the two ends of the gooseneck (109).

5. The boiling calcined lime kiln of claim 1, wherein: the smoke outlet end of the double-tube cyclone dust collector (401) is fixedly communicated with the feed inlet end of the V-shaped powder concentrator (202), the air outlet end of the V-shaped powder concentrator (202) is fixedly communicated with a C2-grade cyclone preheater (207), the air outlet end of the C2-grade cyclone preheater (207) is fixedly communicated with a C1-grade double-tube cyclone preheater (208), and the C1-grade double-tube cyclone preheater (208) is communicated with a bag type dust collector (209); and the separated material openings of the bag type dust collector (209), the C1-grade double-pipe cyclone preheater (208) and the C2-grade cyclone preheater (207) are communicated with the storage bin (203) through a conveyor belt.

6. A boiling calcination lime kiln in accordance with claim 1, characterized in that: a cold area waste gas outlet of the grate cooler (403) is respectively communicated with a gas inlet of the air blowing assembly (103) and a feed inlet of the V-shaped powder concentrator (202); the air blowing component (103) comprises a high-pressure air blower, and an air outlet of the high-pressure air blower is communicated with an air inlet of the air distribution component (102) through an air duct.

7. A process for producing boiling calcined lime, which is based on the boiling calcined lime kiln of any one of claims 1 to 6, and is characterized in that: the method comprises the following steps:

step one, raw material preparation: crushing limestone into limestone particles with the particle size of less than 25mm by a crushing machine; grinding limestone particles through a roller press (201) to form limestone powder, wherein the particle size of the limestone powder is less than 2 mm; the limestone powder is scattered by the V-shaped powder concentrator (202) and then enters the storage bin (203);

step two, raw coal preparation: raw coal particles are crushed into raw coal powder with the granularity of less than 5mm through a crushing structure and stored in a coal storage bin (301);

step three, lime calcination: limestone powder and raw coal powder are weighed by the first metering and feeding assembly (206) and the second metering and feeding assembly (302) from the storage bin (203) and the coal storage bin (301) respectively and are conveyed into a combustion chamber (104) in the kiln body (101); air is conveyed into the combustion chamber (104) through the air blowing component (103) and the air distribution component (102), and limestone powder is calcined;

step four, finished product treatment: carrying out gas-dust separation on the dust-containing gas conveyed by the gooseneck (109) through a double-pipe cyclone dust collector (401), and cooling the separated finished product through a grate cooler (403); and after the calcination is finished, the finished product staying in the kiln body (101) enters a grate cooler (403) through a discharge pipe (402), and the finished product is cooled through the grate cooler (403), conveyed by a finished product conveyor belt (404) and conveyed to be stored in a warehouse.

8. The process for producing boiling calcined lime according to claim 7, wherein: in the third step, the temperature of the boiling chamber (105) is controlled at 900-1100 ℃, and the height of the boiling chamber (105) is between 1.0 and 1.5 meters.

9. The process for producing boiling calcined lime according to claim 7, wherein: in the fourth step, dust-containing gas generated in the gooseneck (109) is subjected to gas-dust separation through a double-pipe cyclone dust collector (401), separated waste gas and waste gas in a cold area of the grate cooler (403) enter the V-shaped powder concentrator (202) to scatter limestone powder and dry the limestone powder, waste gas generated by the V-shaped powder concentrator (202) enters the C2-level cyclone preheater (207) to dry materials, and waste gas generated by the C2-level cyclone preheater (207) dries materials in the C1-level double-pipe cyclone preheater (208).