Which kind of kiln is better for building a brick factory or renovating an old one?

First, the reason for choosing a tunnel kiln

In recent years, with the gradual implementation of the wall reform policy in various provinces and cities, the implementation is getting stronger and stronger, and many regions have formulated strict production technology standards according to the characteristics of brick and tile production, and have specific requirements for production equipment and kilns, focusing on eliminating backward production capacity, improving production technology, improving firing efficiency, and converting production methods, and carrying out fruitful work.

1. The product quality of tunnel kiln firing is stable and high, which is the first reason to choose tunnel kiln.

With the continuous revision of the national standards for brick and tile products, the continuous improvement of technical indicators, and the improvement of various performance requirements for products, the products produced by the production line using wheel kilns and some old kilns have low strength, large dimensional error, unstable product quality, product quality lower than national standard requirements, and some are unqualified products. The products produced by the tunnel kiln have accurate size, beautiful shape, high strength and stable quality, which fully meet the requirements of the national standard.

2. Carrying out technical transformation of the production line and improving its production technology level is the second reason for choosing tunnel kilns.

Most of the original brick and tile production enterprises are produced and managed in an extensive form, and the process level of the brick factory is low, and the equipment used can only produce the most ordinary and low-end products. The production process mainly relies on manpower, belongs to labor-intensive enterprises, the entire production process rarely uses mechanized, high degree of automation equipment, most enterprises rarely consider the use of fully automatic production equipment. With the continuous improvement of production technology, the performance of brick and tile machinery and equipment is gradually improved, and the brick and tile production process is further improved. With the in-depth development of energy conservation and emission reduction, the requirements for kiln exhaust emissions are becoming more and more stringent, and the general kiln can no longer meet the requirements, and only the choice of tunnel kiln can make the exhaust gas emissions in the production process meet the requirements of national standards. Tunnel kiln production continuous, short firing cycle, large output, good quality, high heat utilization rate, good waste heat utilization, fuel saving are its basic characteristics. Not only is the operation easy to operate when burning the fire, but also the operation of installing the kiln and leaving the kiln are carried out outside the kiln, which significantly improves the working conditions of the operators and reduces the labor intensity. If the investor has sufficient funds, it is conducive to the implementation of automatic operation of palletizing and unloading bricks, and it is the only choice for brick and tile enterprises to upgrade the technology of the production line and improve the mechanization and automation level of the production process.

3. Reducing the impact of human factors on production is the third reason for choosing tunnel kilns

There are more labor used in the production process, there are operators in each key link, most of the production process is maintained by the experience of operators, without accurate measurement, operators cannot operate according to accurate process parameters. This leads to a strong arbitrariness of production, production can not be run according to reasonable parameters, human factors on production output, product quality, production efficiency, enterprise benefits have a greater impact. In the new production process, we can try to use mechanized and highly automated equipment, the parts that can use machinery, never use labor, and use semi-automatic equipment where automation equipment can be used, so as to minimize the impact of human factors on production. For firing equipment, various operations of the tunnel kiln can be automatically controlled, from kiln door lifting, automatic jacking of the top machine, automatic return of the tractor, automatic control of the fan, automatic monitoring of the kiln temperature, automatic adjustment of the kiln temperature, automatic addition of fuel, etc. do not require manual operation, which can meet the requirements of automatic production and reduce the impact of human factors on production, which is incomparable with other forms of kilns.

4. Improving labor productivity and reducing production costs is the fourth reason for choosing tunnel kilns

The brick and tile industry is a labor-intensive industry, and now the labor resources are becoming more and more tight, the number of employees is decreasing, and few people of the younger generation are willing to engage in this industry, resulting in most of the employees in this industry aged 40~50 years old, labor productivity is relatively low. At the same time, personnel salaries are rising, and the cost of human resources is getting higher and higher. If the production line with a high degree of mechanization and automation is used for production, the use of machines instead of manual operations as much as possible reduces the use of post personnel, which can not only reduce the labor wages in the production process, but also reduce the scrap rate of the production process and ensure the stable quality of the production products. Tunnel kiln is such firing equipment, it can use manual operation, can also be without manual operation, fully automated operation, which not only reduces the occupation of labor resources, reduces the cost of production human resources of enterprises, but also can produce stable product quality and stable output of the production line.

Second, the selection of tunnel kiln should pay attention to the problem

Although the tunnel kiln is a very good firing equipment in the brick and tile industry, but if the choice is improper, it still cannot achieve its best use effect, and even gives people the illusion that the tunnel kiln is not good to use, can not be used, and is not as good as other kilns, destroying the reputation of the tunnel kiln.

1. Select mature technical solutions to ensure that the production line meets the standard and reaches the production

When using tunnel kiln to burn bricks, various parameters used in production should be determined according to the basic properties of raw materials. The firing output of the kiln is that the performance indicators of the firing product meet the requirements of the national standard, rather than how much is fired casually, and the output of the kiln is how much. Some kiln fired products are only 3mm~4mm on the surface, and the inside is not burned through, so that products that do not meet the requirements of the national standard cannot be used as the basis for calculating the output of tunnel kilns. The length, width and height dimensions of the kiln are calculated according to the output of the kiln, and the heating of raw materials, cooling speed, raw material firing time, maximum firing temperature, firing temperature range and other factors should be considered when calculating the length, width and height size of the kiln. The tunnel kiln should also have a complete working system, and the various parameters of the working system must be calculated in detail, so as to ensure the normal operation of the tunnel kiln, so as to achieve the correct construction and correct use of the tunnel kiln, in order to ensure that the tunnel kiln is fired to meet the standard and production.

Now tunnel kiln construction can be described as a "chaotic" word, various kiln construction companies have sprung up, and various experts have appeared, with the momentum of "how bold people are and how productive the kiln is", entering the brick kiln construction market. Closely focusing on the concept of "less investment, high output" to grasp the investor's psychology of "less input and more output", no matter what kind of raw materials, the investor does not understand the firing situation to make it on the project. There is also a set of drawings to go around the world, no matter what raw materials are used to produce the same process, the same kiln, the result is very tragic, many 3.6m wide tunnel kiln investors can only reach 50% of the production claimed at the time of construction, or even less. Some so-called experts do not even understand the basic principle of the kiln, even the firing time and firing temperature range of the raw materials are not clear, and the production quality of the tunnel kiln built is very poor, so that the final kiln production yield of the investor is only 50%~60%.

2. Rationally layout the system of the tunnel kiln to make it stable in firing

According to the definition of tunnel kiln, the tunnel kiln should be provided with a ventilation system, fuel combustion system, vehicle inlet system, sealing system, and these subsystems constitute the working system of the tunnel kiln. The close cooperation of various systems can make the tunnel kiln work normally. According to the requirements of the firing atmosphere in the kiln, the number and location of fans used in the kiln are equipped, the wind pressure of the fan is determined according to the shape of the fired products and the density of the kiln, and the ventilation capacity of the fan is determined according to the output. According to the fuel used to determine the fuel combustion system, what kind of combustion equipment to use, the layout location of the combustion equipment, the number of the number of combustion equipment to make the temperature in the kiln as uniform as possible. The main contents of the vehicle entry system are the way to enter the vehicle and the time interval of entering the vehicle. The sealing system includes the sealing of the kiln car and the kiln body, the sealing of the kiln door and the kiln body, the sealing of the pipeline and the kiln body, the sealing between the kiln car, so much sealing has only one purpose, that is, to isolate the inside of the tunnel kiln from the external atmosphere, so that the tunnel kiln inside to form a good firing space, so that the semi-finished products are fired into finished products inside the kiln. The division of the three belts in the firing process of the tunnel kiln should be carried out according to the basic properties of the raw materials, and should not be arbitrarily divided, so as to ensure the normal production and stable work of the tunnel kiln.

Now the use of tunnel kilns in the industry is a bit chaotic, and the phenomenon of arbitrarily setting up tunnel kiln systems is more common. Many nominal tunnel kilns actually only use a shell of the tunnel kiln, and the bones are still a wheel kiln, but the wheel kiln is put out of the kiln, which leads to a decline in firing quality, and it is not known why. Some are obviously wheel kilns, but they should be called tunnel kilns, what movable tunnel kilns, rotary tunnel kilns, rotary tunnel kilns and other various new kilns, in fact, is a wheel kiln, completely use the wheel kiln working system and operation method, the quality of the fired product is comparable to the wheel kiln, and some are even inferior to the wheel kiln. This kind of kiln can only be used in the southern regions with higher temperatures, and for the northern provinces, it cannot be produced in winter. Compared with tunnel kilns of the same size, the investment of this kiln only reduces the kiln car cost of general tunnel kilns, but its firing output is only 50% of the tunnel kiln, or even lower. But it is such a kiln claims to be a high-tech product, and in the wide promotion, which recalls a yard fired wheel kiln promoted a few years ago, at that time was also claimed to be an advanced scientific and technological achievement, only a few years, now there are several in normal production, time is a good touchstone, I hope this situation will not happen in the industry again.

3. Recognize the importance of kiln cars and ensure the stable quality of fired products

Kiln car is an indispensable equipment in the production process of tunnel kiln, and it is also a key equipment related to the performance of tunnel kiln and whether it can be used normally. To let the kiln car play the role of key equipment, the first thing is to keep a good seal between the kiln car and the tunnel kiln body, so that the kiln inside and outside the kiln are completely isolated, so that the cold air outside the kiln can not enter the kiln at will, and the hot air in the kiln will not leak into the kiln, so that the firing process in the kiln can proceed smoothly. Secondly, the seal between the kiln cars should also be firm, as mentioned above. Third, the kiln car should run smoothly, so as to avoid the occurrence of kiln reversal, uneven firing, and difficulty in entering the car. Fourth, the insulation layer on the kiln car is very important, if the insulation layer of the kiln car has a good insulation effect, it can make the temperature in the kiln tend to be consistent, the quality of the fired products is uniform, the color is the same, if the insulation effect of the kiln car is not good, then it will make the temperature difference between the upper and lower kilns is large, the fired products are cooked or coke is cooked, in short, the product quality is uneven, and the color difference is large.

Since the kiln car is a relatively large investment project during the construction of the tunnel kiln, some investors arbitrarily change the material and thickness of the kiln car insulation layer in order to save investment, so that the insulation performance of the kiln car decreases. In order to make more profits, some kiln companies also replace the insulation materials of the kiln cars with non-thermal insulation materials, or reduce the thickness of the insulation materials. The evil consequences caused by this are not only the large temperature difference in the kiln, the quality of the fired products is different, but also the temperature under the car is high, the damage to the kiln car bearings and steel structure is aggravated, and the service life of the kiln car is affected. Some factories have been built for less than a year, kiln cars often have problems, need to replace bearings, not only aggravate the rise in production costs, but also change the understanding of tunnel kilns, feel that tunnel kilns are inferior to other kilns. In fact, the root is in the insulation layer of the kiln car, and the seemingly simple insulation layer problem is not dealt with. Some kiln cars do not reduce the thickness and material of the insulation layer, but the insulation effect is still very poor, and its essence is that the use of thermal insulation materials is biased, and good things are used but do not play the role of good things. Many industry colleagues asked me why some tunnel kilns have a temperature of only 40 °C ~ 50 °C, and people can smoothly check under the car, while some people have a high temperature under the car, and people can't get into the car at all. In fact, the reason is very simple, it is caused by the gap in the insulation layer of the kiln car.

　　三、隧道窑施工中应注意的问题

　　隧道窑性能的好坏不但取决于设计的完整与否，而且与施工的关系非常密切，每一施工步骤的质量都影响隧道窑的质量及使用性能。

　　1、施工材料要有保证

　　在窑炉设计过程中，考虑了各种材料的材性和使用要求，材料的使用部位和厚度都是经过计算得出的。为了保证施工质量，施工过程中不得随意更改材料的使用位置和使用量，也不得更改使用材料的品种和质量等级。如果要进行代换，结构材料的强度等级必须高于原设计所用材料的强度等级，欲替换的保温材料的导热系数必须小于原来所用材料的导热系数。

　　2、按照设计要求施工

　　在隧道窑的使用过程中，充分考虑了施工过程中应该达到的技术要求，施工难度及其解决的办法。设计中使用了许多规范和标准，这些标准和规范包括国家级标准和规范、省部级标准和规范、地方级标准和规范、行业标准和规范。施工要求中对各部位提出具体要求，这些要求都是符合施工规范和标准要求的，如果要对其进行更改，则必须参照规范及标准的相应条目，按照规范和标准的要求进行更改，不能随意更改。施工所用材料一般选用国家标准公布的材料，如果要变更材料的规格型号，则应该对照国家标准，用性能更高的材料代替原设计使用材料。