CN111380357A

CN111380357A - Tunnel kiln

Info

Publication number: CN111380357A
Application number: CN201811638539.4A
Authority: CN
Inventors: 李有奇; 毕长禄; 孙爽; 赵继增; 刘雷
Original assignee: LUOYANG LIER ZHONGJING PHOTOVOLTAIC MATERIAL CO LTD
Current assignee: LUOYANG LIER ZHONGJING PHOTOVOLTAIC MATERIAL CO LTD
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2020-07-07

Abstract

The invention relates to a tunnel kiln, which comprises a kiln top structure and a kiln wall structure; the tunnel kiln comprises a preheating zone, a burning zone and a cooling zone; in the kiln top structure, the suspended ceiling materials of the preheating zone are heavy clay bricks and ceramic fibers; on one hand, the tunnel kiln is energy-saving and environment-friendly, the cost is low, and the obtained product has uniform quality; on the other hand, the whole tunnel kiln adopts a flat ceiling structure, so that the temperature difference in the kiln can be small by the flat ceiling, and the kiln temperature is easy to control.

Description

Tunnel kiln

Technical Field

The invention relates to the technical field of kilns, in particular to a tunnel kiln.

Background

The tunnel kiln is a main device for producing refractory products and is also a main energy consumption device of a refractory plant. Compared with the traditional down-draft kiln, the tunnel kiln has the advantages of high production efficiency and low fuel consumption, and is widely applied to the sintering and molding production of refractory materials at present.

The existing refractory brick tunnel kiln is a straight-through tunnel, the inner wall surface of the tunnel is coated with a refractory heat-insulating material, and the tunnel is divided into a kiln head, a preheating section, a firing section, a cooling section and a kiln tail in sequence along the depth direction of the tunnel. The kiln head is an inlet for conveying raw materials, namely refractory brick blanks, into a tunnel of the tunnel kiln, the preheating section is an area for heating and dehumidifying the raw materials, the burning section is a high-temperature sintering area for preserving heat of the raw materials for a certain time at the highest generation temperature in a fuel burning mode, the burning section is also used as a fuel combustion chamber of the tunnel kiln, the cooling section is an area for cooling and discharging clinker, namely burnt refractory bricks, and the kiln tail is an outlet for leaving the clinker from the tunnel kiln. And the bottom of the preheating section is provided with an inlet of a waste heat air passage, and the waste heat air passage is used for collecting flue gas waste heat in the tunnel kiln and sending the flue gas waste heat to a raw material drying kiln outside the tunnel kiln to dry raw materials in the raw material drying kiln. The raw material drying kiln is also connected with an outdoor air exhaust chimney, and the outdoor air exhaust chimney is used for exhausting water vapor in the raw material drying kiln and discharging the water vapor to the high-altitude environment. And a plurality of fuel natural gas nozzles are distributed on the side wall of one surface of the sintering section, and the natural gas nozzles spray natural gas into the sintering section for combustion. And an air blower is arranged on the kiln top at the middle front part of the temperature reduction section, sucks air in the environment and blows the air into the tunnel kiln to provide combustion air for natural gas combustion for the firing section. A plurality of radiating holes are formed in the two side walls of the rear portion of the cooling section, and clinker in the cooling section is cooled by means of natural convection heat exchange through the temperature difference between the inside and the outside of the radiating holes.

The characteristics of the calcined material and harmful components in the flue gas can seriously erode the kiln body material of the tunnel kiln, thereby not only damaging the kiln body and shortening the service life of the kiln body, but also being not beneficial to environmental protection; in addition, the reasonability of the kiln body structure can also greatly improve the firing efficiency of the kiln and the high-efficiency utilization of energy.

The invention is provided in view of the above.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a tunnel kiln.

In order to solve the problems, the invention adopts the following technical scheme:

a tunnel kiln comprises a kiln top structure and a kiln wall structure; the tunnel kiln comprises a preheating zone, a burning zone and a cooling zone; in the kiln top structure, the suspended ceiling material of the preheating zone is heavy clay brick and ceramic fiber.

Preferably, the ceiling material of the burning zone is selected from first-grade high-alumina bricks and ceramic fibers.

Preferably, the ceiling materials of the cooling zone are all made of novel high-temperature light refractory materials and ceramic fibers.

Preferably, the working layer of the kiln wall structure is made of high-alumina bricks of different grades according to different positions.

Preferably, other layers of the kiln wall structure are made of light refractory materials and ceramic fiber felts.

Preferably, mechanical lifting kiln doors are arranged at two ends of the tunnel kiln, and the kiln doors enable air flow in the kiln to form a relatively closed system.

Preferably, the tunnel kiln is provided with a kiln bottom pressure equalizing system.

Preferably, the preheating zone is provided with an air curtain fan.

Preferably, the tunnel kiln is provided with high-speed burners which are arranged in a staggered manner.

By adopting the technical scheme, the invention has the beneficial effects that:

the tunnel kiln is made of light energy-saving, corrosion-resistant and long-life materials, and the produced product has uniform quality, energy conservation, environmental protection and low production cost; in addition, the whole tunnel kiln adopts a flat ceiling structure, so that the temperature difference in the kiln can be small by the flat ceiling, and the kiln temperature is easy to control.

Drawings

FIG. 1 is a scanning electron microscope image of the activated alumina micropowder obtained by the process for producing the activated alumina micropowder of the present invention;

FIG. 2 is a scanning electron microscope image of the activated alumina fine powder obtained by the process for producing the activated alumina fine powder of the present invention.

Detailed Description

The present invention will be explained in more detail by the following examples, which are intended to protect all changes and modifications within the scope of the present invention, and the present invention is not limited to the following examples.

A process for preparing the activated alumina micropowder uses the tunnel kiln sintering method to produce the activated alumina micropowder.

The preparation process of the active alumina micropowder comprises the following raw materials:

(1) the main raw materials are as follows: industrial alumina powder;

(2) an additive; the additive comprises a binder; the binding agent comprises organic binding agents such as dextrin and polyvinyl alcohol or inorganic binding agents such as water and alumina sol;

the additive comprises other additives, and the other additives comprise inorganic additives such as boric acid and aluminum fluoride. The main purpose is to promote the sintering, crystallization and impurity removal of alumina.

The preparation process of the active alumina micro powder specifically comprises the following steps:

the first step is as follows: preparing a premix;

firstly, premixing an additive and a certain amount of industrial alumina powder with the granularity less than 100 meshes for a certain time through a vibration mill, a conical mixer or other mixing equipment, and uniformly mixing to obtain the required premix. Preferably, the additive is premixed with the commercial alumina powder for 30 to 60 minutes.

Wherein, the premix mainly comprises a certain amount of organic additives and inorganic additives of different types; wherein the addition amount of the organic additive is 0.5-2.5% of the final finished product material, and the addition amount of the inorganic additive is 1.0-3.5% of the final finished product material.

The main purpose of preparing the premix is to fully mix the additive with small content in the material and the main raw material, so as to avoid the condition that the additive is not uniform in the material.

The second step is that: mixing and grinding the premix and the main raw material;

the premix and the main raw material are mixed according to a set proportion, the premix and the main raw material are accurately weighed and then conveyed to a ball mill for grinding, and the fineness of the premix and the main raw material is ground to D90 which is less than or equal to 50 microns through the ball mill. And then conveying the ground mixture to a storage bin for later use through conveying equipment. Wherein the ratio of the premix to the raw materials is 1: 10.

the main purpose of the process link is to mix the premix and the main raw material, and the premix is fully and uniformly mixed into the main raw material, and the used equipment is a ball mill.

The third step: wet mixing the mixture;

the method comprises the steps of conveying the mixture in a bin to a sand mixer quantitatively through a screw conveyor, and adding a certain amount of water into the sand mixer, wherein the water adding amount accounts for 30-42% of the total mixture. Or adding alumina sol into the sand mixer for wet mixing, wherein the adding amount of the alumina sol accounts for 35-48% of the total mixture. After being uniformly mixed in a sand mixer, the mixed material is lifted to a hydraulic brick making machine through a belt with a large inclination angle.

The step is mainly used for carrying out wet mixing on the uniformly mixed mixture to prepare for forming.

The fourth step: pressing to make bricks;

and in the fourth step, a hydraulic brick press with the size not smaller than 500T is adopted to press the uniformly mixed wet materials into cuboid green bricks with certain shapes, and the green bricks are stacked on a kiln car by a robot automatic green brick stacking machine according to a certain stacking method.

The main purpose of the step is to press the mixture into a shaped product with a certain shape according to the process requirements, and then carry out loading and firing.

The fifth step: drying the green bricks;

driving the charging kiln car into an auxiliary kiln at the front end of the tunnel kiln for drying; the step effectively utilizes the waste heat of the tunnel kiln, and achieves the effect of energy conservation; and the drying effect is good, the green bricks are dried uniformly, the deformation degree is small, the moving links of the green bricks are relatively few, the brick crushing rate is low, the good working condition of the tunnel kiln is favorably kept, and the good calcining quality is favorably ensured.

The main purpose of the step is to finish baking the moisture in the green brick so as to avoid the cracking and bursting of the green brick in the firing process.

And a sixth step: firing the green bricks;

the total length of the tunnel kiln is set to be 80-100m according to requirements, a kiln body needs to comprise a preheating zone, a burning zone and a cooling zone, a kiln car with dried green bricks is conveyed to the tunnel kiln, the kiln car sequentially passes through the preheating zone, the burning zone and the cooling zone, and products (clinker) burned after being taken out of the tunnel kiln are conveyed to a crushing and micro powder preparation station through a trailer.

The step is the core procedure of the preparation process, and the main purpose is to treat the green brick at a specific transformation temperature and in a specific atmosphere for a corresponding heat preservation time so as to realize the transformation and crystallization of the crystal form of the alumina, discharge impurity components in the raw material and finally generate a qualified alumina micro powder product. Wherein the transformation temperature is 1300-1500 ℃, and the heat preservation time is 4-8 h.

The seventh step: crushing and preparing micro powder;

and crushing the sintered product (clinker), and grinding the crushed product in a ball mill until the required granularity composition is achieved.

And unloading the fired product into a crusher through a car unloader for crushing, and grinding the crushed product through a ball mill to obtain a finished product. The granularity of the finished product is kept between 1 micron and 5 microns.

The physicochemical indexes of the qualified products after sintering by adopting the high-temperature tunnel kiln are as follows:

the active alumina micropowder prepared by the preparation process has the characteristics of (1) high chemical stability, (2) low sodium oxide impurity content, (3) optimized and suitable particle size distribution, (4) good compatibility with other materials, and (5) high α phase inversion rate and small α original crystal size.

As shown in fig. 1-2, the activated alumina micro powder obtained by the preparation process of the present invention is obtained by scanning electron microscopy, and the observation of the crystal morphology shows that the single crystal of the calcined alumina micro powder is approximately spherical, so that the fluidity of the monolithic refractory material is significantly improved during the construction process, and the pores among the monolithic refractory material particles can be well filled, thereby improving the compactness of the monolithic refractory material.

The main equipment used in the preparation process of the active alumina micropowder is as follows:

(1) a raw material grinding ball mill. Mixing industrial alumina powder and additive and grinding. The method is mainly used for homogenizing raw materials and simultaneously grinding the raw materials to be beneficial to the later-stage green brick forming.

(2) And (5) sand mixing machine. The premix is wet mixed with water and other binders.

(3) Brick pressing and setting machine. The operation time of the press-mounting machine is the same as that of the sand mixer, and 10-20 bricks are discharged each time; the setting machine is a matched device of the brick press, and products pressed by the brick press are directly and orderly stacked on the kiln car.

(4) A crusher. Mainly adopts a jaw crusher or a roll crusher, and mainly aims to crush the fired finished brick blanks to reach the required granularity.

(5) A clinker grinding ball mill. And grinding the finished product material with proper granularity to reach the final micron-sized size of 1-5 microns.

A preparation process of active alumina micropowder, the preparation process is used for the firing furnace of the thermal engineering design mainly as the tunnel kiln, its working system mainly includes: (1) a tunnel kiln main body structure; (2) a ventilation system; (3) a kiln car operating system; (4) burner distribution and natural gas main pipe system; (5) a power supply and automatic control system; (6) drying and dust removal systems, and the like.

Preferably, the tunnel kiln is provided with high-speed burners which are arranged in a staggered manner, airflow and temperature forced stirring are formed in a burning zone, and the temperature difference of the inner section of the kiln is reduced;

preferably, the preheating zone is provided with an air curtain fan, and the air curtain fan can force airflow to flow downwards so as to reduce the temperature difference between the upper part and the lower part;

preferably, the tunnel kiln is provided with a kiln bottom pressure equalizing system so as to reduce the flow of up-down airflow of a kiln car and effectively reduce the temperature difference between the up-down airflow and the kiln car;

preferably, the kiln car adopts a light structure, so that the heat storage of the kiln car can be effectively reduced, and the heat efficiency is improved;

preferably, the working system adopts full-automatic control, so that accidents caused by manual misoperation can be effectively avoided;

preferably, the tunnel kiln is provided with a kiln door lifting safety alarm and a car pusher overload alarm, so that the whole working system is safer and more reliable;

preferably, the air curtain fan is adjusted by frequency conversion, so that the power consumption and the noise pollution can be effectively saved;

preferably, because the even effective assurance of goods heating temperature is put to the goods, operating system adopts the automatic dress brick of manipulator, and the brickwork joint is even, is favorable to the air current distribution, can effectively guarantee the homogeneity of goods heating.

Tunnel cave kiln major structure, its whole kiln adopts flat furred ceiling structure, and flat furred ceiling can make the difference in temperature little in the kiln, and the kiln temperature is controlled easily. The kiln body material lining is made of light energy-saving, corrosion-resistant and long-life materials in consideration of the characteristics of the calcined materials and the corrosion of harmful components in the flue gas to refractory materials.

Specifically, the tunnel kiln comprises a kiln top structure and a kiln wall structure; in the kiln top structure, the suspended ceiling materials of the preheating zone are heavy clay bricks and ceramic fibers, the suspended ceiling materials of the firing zone are first-grade high-alumina bricks and ceramic fibers, and the suspended ceiling materials of the cooling zone are all novel high-temperature light refractory materials and ceramic fibers, so that the kiln top has good heat insulation performance;

in the kiln wall structure, except that different high-alumina bricks are selected for different positions of the working layer of the kiln wall, other layers of the kiln wall all adopt light refractory materials and ceramic fiber felts, so that heat storage and heat dissipation losses of the kiln body are small, and the purpose of energy conservation is achieved.

And mechanical lifting kiln doors are arranged at two ends of the tunnel kiln, so that the air flow in the kiln forms a relatively closed system.

The selection of the type and the thickness of the material of each part of the tunnel kiln are determined by heat transfer calculation according to a product temperature curve.

Wherein the process flow of the materials in the tunnel kiln is as follows: drying → kiln car pusher enters tunnel kiln to burn → electric trailer → cooling kiln → material puller discharge → crushing → ball mill grinding → finished product packaging. The main technical indexes of the tunnel kiln are shown in the following table:

serial number	Item	Unit of	Index (I)
				1	Product(s)		Active Al₂O₃
2	Firing yield	％	≥98
				3	Firing cycle	min	40
4	Firing temperature	℃	1300-1500℃
				5	Kiln roof structure		Whole kiln flat ceiling

The active alumina micro powder prepared by the invention has high activity and small fineness, and can play the effects of reducing firing temperature and improving high-temperature performance index when being applied to a shaped product; the application of the amorphous refractory material can improve the filling performance and excellent sintering activity of particles, reduce the water absorption, and the water-containing slurry has better thixotropic fluidity, can improve the sintering density and high-temperature strength of the amorphous refractory material, enhances the performances of wear resistance, corrosion resistance, scouring resistance and the like of the amorphous refractory material, and is suitable for various casting materials of corundum, high-alumina, aluminum-magnesium and silicon-containing micro powder.

On one hand, the tunnel kiln has the advantages of uniform product quality, energy conservation, environmental protection and low production cost; in addition, the whole tunnel kiln adopts a flat ceiling structure, so that the temperature difference in the kiln can be small by the flat ceiling, and the kiln temperature is easy to control.

The invention adopts the tunnel kiln sintering method to produce the active alumina micropowder, the green brick is dried evenly, the degree of deformation is small, and the green brick moving link is relatively less, the brick rate is low, it is favorable to keeping the good working condition of the tunnel kiln, also favorable to guaranteeing the good calcination quality, the active alumina micropowder prepared can be used for light-admitting quality alumina sintered body, carrier for fluorescent body, single crystal material, advanced porcelain, artificial bone, semiconductor, integrated circuit base plate, recording tape filler, catalyst and its carrier, grinding material, laser material, cutting tool, etc., especially have important effects on the development of microelectronics and material industry, the invention has the advantages of simple operation, obvious effect, etc., suitable for large-scale popularization and application.

The present invention is not described in detail in the prior art.

The embodiments selected for the purpose of disclosing the invention are presently considered to be suitable, however, it should be understood that the invention is intended to cover all variations and modifications of the embodiments falling within the spirit and scope of the present inventive concept.

Claims

1. A tunnel kiln is characterized in that: the tunnel kiln comprises a kiln top structure and a kiln wall structure; the tunnel kiln comprises a preheating zone, a burning zone and a cooling zone; in the kiln top structure, the suspended ceiling material of the preheating zone is heavy clay brick and ceramic fiber.

2. The tunnel kiln of claim 1, wherein: the ceiling material of the burning zone selects first-grade high-alumina bricks and ceramic fibers.

3. The tunnel kiln of claim 2, wherein: and the ceiling materials of the cooling belt are all novel high-temperature light refractory materials and ceramic fibers.

4. The tunnel kiln of claim 1, wherein: and clay bricks of different grades are selected for the working layer of the kiln wall structure according to different positions.

5. The tunnel kiln of claim 4, wherein: and other layers of the kiln wall structure are made of light refractory materials and ceramic fiber felts.

6. The tunnel kiln of claim 1, wherein: and mechanical lifting kiln doors are arranged at two ends of the tunnel kiln, and the kiln doors enable the air flow in the kiln to form a relatively closed system.

7. The tunnel kiln of claim 1, wherein: the tunnel kiln is provided with a kiln bottom pressure equalizing system.

8. The tunnel kiln of claim 1, wherein: the preheating zone is provided with an air curtain fan.

9. The tunnel kiln of claim 1, wherein: the tunnel kiln is provided with high-speed burners which are arranged in a staggered mode.