By Lin Yongchun 1 Zhang Juncang 1 Shi Xiaoming 1 Yan Kaifang 2

(Shaanxi Baoshen machinery (Group) Co., Ltd., Meixian County,

Shaanxi 722300 Xianyang ceramic research
Design Institute of China building materials, Xianyang 712021, Shaanxi)

[Abstract]:
According to the quality defects such as "embossing" and "black center" fracturing deformation of the internal combustion or super internal combustion one-time code firing process products in the sintering wall material products industry, Shaanxi Baoshen machinery (Group) Co., Ltd Developed and manufactured the chain plate secondary code burning fast drying equipment, which has the characteristics of low cost, high output, low energy consumption, product quality improvement, environmental pollution and easy to reach the standard, and has obtained the national patent. This kind of drying form and chain plate transmission structure is the first in China, which brings good news for the improvement of product quality in the industry.

[Key words]: 
wall material sintering; chain plate drying; secondary code sintering; product quality

      The Ministry of industry and information technology, the Ministry of environmental protection and the State Administration of work safety issued a document on November 11, 2017 with the Ministry of industry and information technology of the people’s Republic of China (MIIT) Lianyuan [2017] No. 279, some opinions on accelerating the transformation and development of sintering brick and tile industry. The release of this important document has played a guiding role in guiding the brick and tile industry to vigorously develop advanced products, resolutely eliminate backward production capacity, promote green manufacturing, promote energy conservation and emission reduction, promote the utilization of national waste, improve quality and safety, and also pointed out the direction for the future development of sintering wall material production and equipment. In order to adapt to the "development of brick and tile products in the direction of high content, high porosity, high strength, multi-function and self decoration", promote the resource utilization of solid waste, improve the ecological environment and reduce the emission of air pollution, in view of the many quality defects in the primary code firing process, Shaanxi Baoshen machinery (Group) Co., Ltd. (hereinafter referred to as Baoshen group), in accordance with the spirit of No. 279 document, studies The chain plate fast drying kiln (hereinafter referred to as dryer) is designed and developed, which is the second code firing equipment with the same cost as the first code firing process. In November 2018, the Group invested more than 10 million yuan to upgrade the original experimental plant and put it into operation in May 2019. After half a year’s commissioning, it exceeded the expected results. It has realized the investment of the brick and tile enterprises in the first code burning, built the second code burning production line, and greatly improved the product quality. The dryer has obtained the national utility model patent, and has applied to accept the national invention patent. This R & D and design result will become one of the main drying forms of the industry’s secondary code firing process in the future, with a promising market prospect.

• [ Main technical parameters ]

According to the actual operation for more than half a year, the actual production data of the dryer is as follows:

1.1. Bearing capacity:
   Each meter of single-layer solid brick can be coded 300 pieces, the upper and lower two layers can be coded 600 pieces, each wet brick is calculated as 3.1kg, the whole dryer chain plate can code 64800 wet bricks, and the weight of wet bricks is 200.88t. The weight of porous brick and hollow brick after folding standard brick is lower than that of solid brick, and there is no problem for the weight of dryer bearing tension. The design is considered as 300t, and the safety factor is large.

1.2 Production capacity: 
    When the hole rate of bearing porous brick is 21.6% (19 Ф 20mm holes), the daily production capacity is calculated to be about 200000 pieces, and the output of hollow brick or hollow block with hole rate more than 35% is more than 300000 standard bricks.

1.3 Water removal:
    ① 240 × 115 × 90mm porous brick, with hole rate of 21.6%, single wet brick weighs 4, 51kg, 3.86kg after drying, and single wet brick weighs 0.65kg; ② 240 × 115 × 150 mm hollow brick, with hole rate of 36%, single wet brick weighs 6.18kg, 5.09kg after drying, and single water removal of 1.09Kg; ③ standard solid brick, single wet brick weighs 3.1kg, 2.7kg after drying, and single dry brick weighs 0.4KG.

1.4. Moisture content:
    The drying cycle of porous brick is 3.5-4.5 hours, and the moisture content of the body after drying; The drying cycle of hollow brick is 2-3 hours, and the moisture content of green body after drying is 4.17%; the drying cycle of solid brick is 5-6 hours, and the moisture content of green body after drying is 5.56%. The qualified rate of drying is 100%.

1.5. Dryer of Baoshen group brick factory: 
    External dimension LXWXH (m): 108*3.2*2.5
(See 1a and 1b for the schematic diagram of the dryer); the air supply temperature is 80 ℃ ~ 280 ℃; the traveling speed of the chain plate is 0.3 ~ 1.2m/min; the drying cycle is 2 ~ 6h, including 6h for solid bricks, 4 ~ 5h for porous bricks, 2 ~ 3H for hollow bricks or blocks with high void ratio, and the air volume for moisture discharge is less than 100,000 m3/h.

Figure 1a schematic diagram of dryer length direction

Fig. 1b schematic diagram of dryer width direction

2. [ Main technical advantages ]

2.1 Advantages of energy saving and consumption reduction:
    According to the actual situation of porous brick production, when the firing temperature is 900 ℃ ~ 950 ℃, the energy consumption per kilogram of finished products is about 260kcal, which is 16% lower than that before transformation, and the daily coal consumption is 4.16t. Annual coal saving is more than 1200t. The reduction of energy consumption directly reduces the emission of harmful components such as sulfur gas and smoke & dust,etc. The annual energy consumption cost is saved over 600,000 Chinese yuan(CNY) (500 yuan< CNY > per ton of standard coal).

2.2 Advantages of solid waste utilization:
    Solid waste has two different characteristics: one is the possibility of high plasticity, high water content, high shrinkage and high sensitivity, such as river, lake mud, urban sludge, construction foundation excavation or drilling sludge, urban subway underground channel slag, oil well drilling slag mud and other brick making; the other is low plasticity, low viscosity and low crack resistance, such as slag, fly ash, chemical slag, building soil and so on. Although the former has a high plasticity index and is easy to extrude, these solid waste materials are easy to deform and crack when they are made by one-time code firing process. Although the latter has a low plasticity index and is extruded under high extrusion pressure and high vacuum degree, due to the dispersion of raw materials and the characteristics of not easy to polymerize, the use of one-time code firing will often cause fracturing and affect the firing yield. However, there are no pressure deformation and cracking problems when using the secondary code firing dryer, single layer or low layer drying. Fig. 2 the following picture shows the primary code firing kiln of fly ash in a factory. Due to the principle error of the manufacturer’s process route and code way, the 4-5 layers under the brick stack are all waste products due to fracturing and other reasons. This kind of raw material should be burnt in two times. This kind of dryer is more suitable for recycling all kinds of solid waste.

Fig. 2: photo of lower layer fracturing of fly ash in a factory

2.3 Advantages of brick billet body drying:
    The dryer developed by Baoshen group can draw the residual heat from the cooling belt of the kiln through the pipeline and enters the dryer in multiple points. The clean hot air passes through the billet body from the bottom to the top, and there are multiple circulation fans, so as to ensure the consistency of section temperature, pressure and humidity of different sections of the dryer, ensure the uniform heating and free shrinkage around the body, and avoid Shrinkage stress crack due to drying. Due to the forming level and the change of raw materials, the speed of chain plate is changed accordingly at any time, and the drying cycle is adjusted to ensure that the qualified rate of drying is almost 100%.

2.4 Advantages of product Improvement: 
With China national comprehensive ban policy concern the production of solid clay brick gradually strengthened, the dryer developed and manufactured by Baoshen group is more suitable for the production of hollow bricks and blocks with energy-saving and heat preservation performance requirements.. The production of wall brick with decoration function can achieve no "embossing" on the strip surface and meet the requirements of masonry clear wall. No matter the product specifications and models are transformed to meet the market demand, the technical parameters of the dryer are adjusted in a wide range, which will lay a solid foundation for the enterprises’ future development of high-quality , diversified and multi specification products.
2.5. Waste steam emission advantages: 
   The emission of air pollution in brick and tile industry, smoke and dust particles and other indicators are greatly affected by the conversion of oxygen content and the air volume of moisture discharge. The dryer developed by Baoshen group has sufficient hot air exchange and oxygen content of about 18%. The daily output of 200000 porous bricks is less than 10m3 / h. If 40m3 air volume is required for evaporation of 1kg water, the air volume is more than 300000 m3. According to the calculation of 200000 fast 240 × 115 × 90mm porous bricks (21.6%) per day, the air volume of the new dryer is less than 10m3 / h, only about 1 / 3 of the traditional air volume. It not only saves electricity, but also helps to reach the standard after pollutant emission conversion. Due to the high temperature of the hot air, it is beneficial to reduce the air volume, which is also consistent with the theoretical calculation.

2.6. Advantages of firing operation: 
   After drying, the moisture content of the green body has dropped below the critical moisture content, and the drying shrinkage of the green body has basically stopped. Only the firing shrinkage is considered after re coding kiln, but the firing shrinkage is small, which ensures the stability of the green stack during firing. Since more than half a year of production, there has been no collapse of the tunnel kiln. The embossing, black center and shrinkage stress crack are eliminated or reduced. As far as the number of kiln layers is concerned, as long as the range of firing temperature is allowed, there is no problem that the number of kiln layers is more than 18. The length of the tunnel kiln can be shortened properly with the increase of the amount of billets.

2.7 advantages of construction and installation:
   Factory made, short construction period, good quality, avoiding wet construction of tunnel drying chamber. New type dryer, on-site construction, installation, commissioning, short construction cycle, to achieve early production.

2.8 Advantages of design adjustment:
   Adjustable for different raw materials and products, regarding to the size of the product specification,the length ,height and drying cycle of the dryer can be adjusted respectively;
according to the porosity of the product, the chain plate speed can be adjusted to change the drying cycle. Small size, low void rate or solid brick products can be stacked in 1-3 layers so as to improve the output. According to the temperature and pressure of air supply, the air inlet position and hot air circulation system can be adjusted. Baoshen dryer is equipped with temperature, pressure, humidity and wind speed sensors to realize the air flow balance of the dryer, the upper and lower temperatures are the same, the humidity of each drying section is kept constant, and the technical parameters of the dryer are adjusted more simply and conveniently.
3. [Cost comparative analysis]

Take the following Figure 3 of primary code firing and Figure 4 of secondary code firing for instance,e.g. 200,000 pieces output per day, 4.6-4.8m tunnel kiln. The cost of drying kiln, tunnel kiln and workshop in the traditional one-time code firing process is compared and analyzed, but it does not include the equipment before the billet cutter, desulfurization and dust removal, power distribution and automation equipment, road hardening and other expenses.

Figure 3: plan of traditional one-time code firing process

Figure 4: process plan of the second code firing of the dryer of Baoshen group

3.1. Traditional one-time code burning process:
The process occupies a leading position in the existing brick factory, and its cost is: ① a tunnel drying room (calculated as 90m for example), including civil engineering, foundation work, fan, jacking machine, exit pulling machine, track, track foundation, track installation, three drying doors, air supply and tide discharge pipes, etc., with an estimated cost of 950,000 Chinese yuan (CNY); ② The roasting tunnel kiln is calculated as 140m, including the civil engineering, foundation and slab positioning machine of the tunnel kiln; the estimated cost is 3.5 million Chinese yuan (CNY); ③ 160 kiln cars are needed for drying, burning and the estimated cost is 4 million Chinese yuan (CNY); ④ the estimated cost is 700,000 Chinese yuan (CNY) for the top car machine, exit pulling machine, track, track foundation, track installation, 3 kiln doors, pipes on the kiln, etc.; ⑤ the workshop is about 9600 square meters. The simple workshop is calculated as 260 Chinese yuan (CNY) / square meter, and the estimated cost is 2.5 million Chinese yuan (CNY); ⑥ the estimated price of the whole rotary billet machine system is 450,000 Chinese yuan (CNY). The above total estimate is 12.1 million Chinese yuan (CNY).

3.2. The second code firing dryer of Baoshen group: 
① The estimated cost of tunnel kiln is 3.1 million Chinese yuan (CNY) based on 120m;
② Approx.65 kiln cars are needed, with an estimated cost of 1.63 million Chinese yuan (CNY);
③ The estimated cost of overhead crane, exit puller, track, track foundation, track installation, three kiln doors, and kiln pipes, etc. is 350,000 Chinese yuan (CNY);
④ The estimated cost of dryer: including kiln body, code dryer, code kiln car, etc. is 5.05 million Chinese yuan (CNY);
⑤ The plant is about 7200m2. The simple workshop is calculated as 260 Chinese yuan (CNY)/ m2, and the estimated cost is 1.87 million Chinese yuan (CNY). The above total estimated cost is 12.15 million RMB yuan (CNY).

3.3 Estimation of existing secondary code burning:
① Code burning system: including transport and grouping, pallet transportation and loading and unloading, code machine, dry blank grouping, 2 code kiln car robots, control system, etc., with an estimated price of 4.45 million Chinese yuan (CNY);
② Drying equipment: including 90 cyclones, 4 drying ferries, 2 drying traction positioning, 120 drying cars, 1920 pallets, etc.with an estimated price of 10.7 million Chinese yuan (CNY);
③ The estimated cost of tunnel kiln is 3.1 million Chinese yuan (CNY);
④ There are 65 kiln cars, with an estimated cost of 1.63 million Chinese yuan (CNY);
⑤ There are three kiln doors and pipes on the kiln, with an estimated cost of 350000 Chinese yuan (CNY);
⑥ The construction of drying room, including civil engineering and track installation, with an estimated cost of 1.9 million Chinese yuan (CNY);
⑦ There are 9500m2 workshops, with an estimated cost of 2.47 million yuan. The above total estimated cost is 24.6 million RMB yuan (CNY).

3.4 cost comparison and analysis

(1) Traditional one-time code burning: the estimated cost is 12.1 million Chinese yuan (CNY).Two natural dehydration cooling channels are considered: the estimated cost is 13.6 million Chinese yuan (CNY).

(2) Secondary code burning: the estimated cost is 24.6 million Chinese yuan (CNY).

(3) Baoshen dryer: the estimated cost is 12.15 million RMB yuan (CNY).

Based on the analysis of the above estimated cost, the dryer of Baoshen group’s second code is 50,000 Chinese yuan (CNY) higher than that of the first code procedure, only 0.41% higher. If considering the natural dehydration of two cooling channels after forming, the estimated cost is increased by more than 1.5 million Chinese yuan (CNY), 12% higher than the cost of the new dryer. Compared with the existing process of the second code procedure, the dryer of Baoshen group is 12.25 million Chinese yuan (CNY)lower, 49.8% lower. This comparative analysis fully shows that Baoshen group’s new type of secondary code firing dryer solution is one of the first options for new construction and transformation of brick and tile enterprises, which not only ensure the brick billets and finished products’ qualities are excellent, but also achieve outstanding price advantages and good market prospects.

4. [Peroration]

The technical solution of chain plate twice code firing fast drying kiln is in the leading position in the world and the first technical know-how in China, which fills the blank of drying equipment technology in the industry. Compared with the traditional drying kiln, it is simple in structure, convenient in construction, economical and practical, energy-saving and efficient, and even in drying,There is no waste product, which can meet the production requirements of hollow brick, sintered thermal insulation block and decorative clear water wall sintered brick, shorten the drying cycle, and provide the thermal efficiency of brick making. It is more than 12 million Chinese yuan (CNY)lower than the cost of the secondary code burning workmanship in the current market. One-time investment of code burning, which can ensure the realization of secondary code burning, and the process is simple and efficient. It will surely bring tangible benefits and substantial improvement of product quality for more enterprises both home and abroad in brick making industry.

[References]

[1]. Lin Yongchun
- General Manager of BaoshenGroup
- Excellent individual of national building materials industrial machinery standardization;
- Exellent leader of National Building Materials Industry Quality Management Group Activities;
- The excellent worker of national building materials machinery industry standardization in 2010
- Excellent worker of building materials machinery industry standardization in 2011;
- The honorary title of outstanding leader of national building materials industry quality in 2012;
- Outstanding enterpreneur of national building materials machinery industry in 2013;
- Building Industry Standard Innovation Award in 2015;

- A drafter of JC/T662.2011 Mixsing-extruder Used in Walling Materials Industry;
- Executive director of the fifth Council of China Brick & Tiles Industrial Association;

- Chinese Professional Manager Qualification Certificate holder;

- ZPM690x3x2 automatic setting machine wins the second prize of the national Building;

- A member of techical committee for standardization of national building materials industry machinery;

- A member of technical committee for standardization of national building materials equipment;

- Excellent individual of Shaanxi Building Materials Industry;
- The first prize of Shaanxi Building Materials Industry Technology Innovation Award;
- The Third Prize of Shaanxi Science & Technology Award;
- The Ninth Youth Science and Technology Award of Shaanxi Province;
- The vacuum extruding,setting and carrying production line wins the second prize of Building Materials Industry Technology Innovation Award;
- Youth shock worker
- The outstanding builder of socialist cause with Chinese Characteristics of Shaanxi Province;
- Youth Science and Technology Award of Shaanxi Province;
- Broker Qualification Certificate holder;
- Excellent rural practical talent title of Baoji city;
- “star of Start-ups” of Baoji city in 2009;
- Excellent Communist Party Member of Non-Public-owned Enterprise of Baoji city;
- ZMP690x3x2 Automatic Setting Machine wins the second prize of Science and Technology Award of Baoji city;
- Deputy to the people’s congress of Baoji city;
- Model Worker title of Baoji city;
- Excellent Private Technopreneur;
- The Outstanding Builder of Socialist Cause With Chinese Characteristics of Baoji city.

[1].Zhang Jun Cang
- Senior engineer of Baoshen Group.

[1]. Shi Xiaoming
- Senior engineer of Baoshen Group.

[2]. Yan Kaifang
- Vice president of national wall material science and technology information network;
- Vice president of China building materials Xianyang ceramic research and Design Institute and China building materials Xi’an wall material research and Design Institute.