Yingfeng Machinery－More Than 30 Years Experience In Clay Brick Making Machine ,Tunnel Kiln, Rotary Tunnel Kiln.

The Advantages Of The New Energy-Saving Mobile Rotary Tunnel Kiln

2026-03-16

Burning bricks requires coal or other fuels. How to maximize the thermal efficiency is the technical key of brick kiln design. The sintering temperature of brick is between 850 ° C and 1050 ° C. In order to save coal, the heat insulation effect of the kiln must be improved. The rotary tunnel kiln is stacked with refractory fiber cotton, which not only reduces the weight of the kiln body, reduces the thermal expansion and contraction stress of the kiln body, but also improves the thermal insulation performance of the kiln body. The kiln temperature is maintained for a long time, and the bricks consumed at one time increase in large area. The internal combustion heat energy can more effectively improve the kiln temperature and save fuel.

In ordinary tunnel kilns, in order to prevent high-temperature flue gas from flowing into the kiln car and burning out the wheels and bearings, it is also necessary to set up a gas source under the kiln car. In the whole heating system, the air supply pressure at the bottom and surface of the vehicle must be kept balanced, and the high temperature flue gas and cold air at the bottom of the vehicle must not rise to reduce the kiln temperature.

The bricks of the rotary tunnel kiln are directly stacked on the ground, without air supply under the vehicle, and the ground temperature is directly fully utilized. It is found that the aluminum silicate fiber blanket can still be calcined normally after 48 hours of coal and air shutdown in actual production, which is impossible for ordinary tunnel kilns. In the annular rotary tunnel kiln, when the firing temperature of bricks is reduced to room temperature, the heat released is enough to dry wet bricks of the same volume, so there is no need to build a hot air furnace, nor need to use the superheat roasting process to consume more coal to dry the heat.

In the heating system of the annular rotary tunnel kiln, dry air enters from the kiln tail and cools the sintered bricks through the cooling section to reduce the temperature of the sintered bricks at the outlet of the kiln tail to room temperature, that is, all the heat emitted by the sintered bricks is carried to the roasting section and drying section through the air entering the kiln for combustion support and drying. The energy saving of circular rotary tunnel kiln is its remarkable feature. Its reasonable process design, layout and simple logistics route also greatly reduce the energy consumption of the whole brick factory.

The circular rotary tunnel kiln fully adopts mechanized operation and automatic digital control system. The temperature in the kiln is directly displayed on the display screen of the control system. There is no need to hire high-paying fire-watching teachers, which fundamentally eliminates brick-making and greatly increases production.

Compared with the traditional tunnel kiln, the new energy-saving and environment-friendly mobile rotary tunnel kiln has great advantages. It can be predicted that the production mode of the new energy-saving and environment-friendly mobile rotary tunnel kiln will be widely used in the field of sintered bricks by comparing the Helu aluminum silicate fiber blanket.

Reasons and solutions of affecting bricks quality

Few points to be paid attention to when choosing a tunnel kiln ?

Related questions

How to Speed Up Tunnel Kiln Firing？

If you want higher brick output, lower energy consumption, and stable quality, mastering tunnel kiln fast firing technology is essential. For modern automatic brick plants, “dry bricks in, sparse setting, strong ventilation, stable temperature & fast pushing” has become the standard for high-efficiency production.

1. Improve green brick quality: dry and hot input

Control moisture content below 3% before entering the kiln.
Preheat green bricks to raise temperature before loading.
Dry, hot bricks fire faster, reduce cracking risk, and save fuel.

2. Optimize brick setting: sparse setting for fast firing

Reduce setting density by 10–15% vs traditional mode.
Keep uniform gaps between brick columns for smooth hot air flow.
Avoid blocking airflow; ensure even heating in preheating zone, firing zone, cooling zone.

3. Strengthen ventilation: balance exhaust & air volume

Properly open exhaust dampers to speed up flue gas flow.
Increase fan frequency reasonably to enhance oxygen supply.
Avoid over-ventilation which causes under-fired bricks.

4. Adjust firing temperature & fuel

Raise firing temperature by 10–15°C (within raw material limits) to shorten cycle.
Shorten holding time while ensuring sintering quality.
Increase internal combustion ratio, adopt small & frequent external coal feeding, or switch to natural gas/oil firing for faster, uniform heating.

5. Accelerate kiln car pace

Shorten car interval and match zone lengths reasonably.
Fast, stable pushing ensures continuous mass production.

By focusing on dry brick preparation, sparse setting, balanced ventilation, precise temperature control, and optimized fuel, your tunnel kiln can achieve higher capacity, lower cost, and consistent brick quality in competitive global markets.

How to Eliminate Spiral & S-Cracks in Clay Bricks？

Spiral cracks and S-cracks are the most frequent structural defects in clay brick manufacturing. These undesirable imperfections lead to high scrap rates, raw material waste, and poor finished brick appearance. This practical guide summarizes mature industrial solutions covering raw material treatment, extrusion optimization, moisture adjustment, equipment maintenance, and kiln processing, helping global brick manufacturers reduce defect rates and maximize production profits.

1. Optimize Raw Material Gradation & Reduce Clay Plasticity

Reasonable particle gradation is the foundation of crack prevention. Manufacturers should mix 20% to 30% coarse aggregates such as grog, shale, and coal gangue into raw clay. Coarse particles enhance interlayer friction and restrain clay internal sliding. Meanwhile, reduce high-plastic clay proportion and add limestone powder or quartz sand to lower drying sensitivity.

2. Balance Extrusion Speed & Optimize Clay Flow

To solve uneven flow velocity, install adjustable resistance bars at the extruder head to slow down the central clay flow and balance overall extrusion speed. Replace ordinary blades with variable-pitch spiral blades to reduce shear difference. Keep the gap between spiral blades and machine cylinder within 2mm for stable extrusion molding.

3. Precise Moisture Control for Raw Clay & Green Bricks

Control the raw clay moisture steadily between 18% and 22% according to local clay properties. Adopt staged slow drying technology for green bricks; keep the initial heating rate below 20°C/h to avoid surface crusting. Uniform moisture removal effectively prevents shrinkage cracks and layered cracks.

4. Standardize Daily Extruder Maintenance & Parts Replacement

Establish regular equipment inspection cycles. Timely replace worn spiral blades and damaged cylinder liners to guarantee stable pushing force. Check extruder head sealing and gaps weekly to avoid disordered clay flow caused by mechanical aging. Scientific maintenance reduces artificial brick defects greatly.

5. Upgrade Drying & Sintering Kiln Curves

Adopt gradient heating mode in drying chambers and tunnel kilns. Control the heating rate between 20°C/h and 30°C/h with sufficient constant-temperature holding time. During quartz crystal transformation (600℃-900℃), slow down heating speed below 40°C/h to relieve internal thermal stress.

Eliminating spiral and S-cracks requires systematic production management from raw materials to finished bricks. Scientific formula proportion, optimized extrusion equipment, precise moisture monitoring, standardized maintenance, and improved kiln technology can reduce brick scrap rates by 5%-10%. Stable product quality helps brick factories occupy more shares in the global construction material market.

How to Boost Brick Factory Output?

For modern brick factories pursuing stable production and high profits

low output and high defective rates have always been troublesome problems. Many brick plant owners blindly upgrade brick making machinery and increase production frequency, but ignore the core bottleneck restricting production efficiency—the drying process. In the actual brick production workflow, the drying section is the key link that determines the qualified rate of green bricks and the daily output of the entire brick factory. Relevant industry data shows that reducing the moisture content of bricks before entering the kiln can directly bring obvious output growth; every 1% reduction in kiln entry moisture can increase brick production by 3% to 5%.

Many brick factories have unreasonable drying settings, resulting in long drying cycles, damp green bricks, and mildewed blanks, which not only reduces the drying qualification rate but also causes adverse effects on the subsequent kiln firing process. To break the drying bottleneck of brick factories, enterprises need to optimize two core indicators: drying temperature and moisture exhaust efficiency.

First, reasonably increase the drying temperature according to the raw material characteristics, and ensure uniform temperature distribution in the drying chamber to avoid uneven drying of green bricks.
Second, strengthen the moisture exhaust system of the drying workshop, timely discharge water vapor generated in the drying process, and prevent water vapor from condensing on the surface of green bricks to cause secondary moisture regain.

In addition to temperature and moisture exhaust optimization, raw material management is also an auxiliary measure to improve drying efficiency. Brick factories need to maintain stable raw material ratio and uniform internal combustion blending. Frequent replacement and proportion adjustment of raw materials will lead to inconsistent moisture characteristics of raw mud, which increases the difficulty of drying control. Uniform internal combustion mixing can avoid local underfiring and reburning of bricks, reduce defective products caused by unreasonable combustion, and further cooperate with the drying process to improve the overall qualified rate of bricks.

For brick making equipment

the operating state of the molding end also indirectly affects the drying effect. The extruder needs to maintain a reasonable running speed while ensuring the compactness of the green bricks. The stable vacuum degree above 0.085 is an essential standard for high-quality brick blanks. Worn reamer blades should be replaced in a timely manner to prevent loose green bricks from being difficult to dry thoroughly. Only when the quality of molded bricks is up to standard can the drying link exert the maximum efficiency advantage.

In the production logic of brick factories, the optimization priority must be clear:

prioritize solving drying problems, then stabilize the firing process, and finally carry out equipment speed increase transformation.

It is necessary to clarify a core principle: the real output of a brick factory refers to the number of qualified bricks. Excessive defective products and reburning bricks will completely offset the production growth brought by equipment acceleration. Optimizing the drying system is the lowest-cost and highest-return way for most brick plants to increase production, which is suitable for small and medium-sized brick factories with limited transformation budgets.

How to Prevent Clay Bricks from Collapsing in Tunnel Kilns？

1. Pre-firing Material Constraints (The "Foundation" Stage)

Collapse often begins before the bricks even enter the kiln if the green body lacks physical integrity.

Moisture Threshold: The residual moisture content must be kept below 6%. High moisture levels drastically reduce the compressive strength of the bricks, causing the bottom layers to buckle under the weight of the stack.
Material Aging: Clay requires at least 3 days of aging to ensure uniform plasticity and water distribution. Insufficient aging leads to internal stresses and a fragile structure.
Mechanical Density: Ensure an extrusion pressure of ≥40kg/cm² to increase the density of the green body, making it more resistant to deformation at high temperatures.

2. Strategic Stacking Techniques (Mechanical Stability)

Stacking is not just about volume; it is about managing gravity and thermodynamics.

The "Four-Point" Standard: Stacks must be level, stable, vertical, and straight. Any minor deviation in the center of gravity will be amplified as the bricks soften in the heat.
Airflow Optimization: Follow the principle of "Dense Edges, Sparse Centers" and "Dense Tops, Sparse Bottoms." This balances the temperature across the kiln cross-section, preventing the edges from over-firing while the center remains under-fired.
Load Management: Due to the high sensitivity of clay, limit the stacking height to 12 layers or fewer. This minimizes the static pressure on the base bricks.

3. Dehumidification in the Preheating Zone (The "Critical" Stage)

This is the most common zone for collapses. If moisture is not evacuated efficiently, the bricks effectively "steam" and lose their rigidity.

Inlet Temperature Control: Keep the initial drying air below 116°C. Temperatures above this threshold cause the surface to harden too quickly, trapping steam inside and creating internal pressure.
Heating Rate: Maintain a steady rise of 6–8°C/h. Sudden temperature spikes, especially in winter, can cause thermal shock and structural failure.
Ventilation and Pressure: Ensure the exhaust fan provides sufficient negative pressure. Poor ventilation causes moisture to linger and re-condense on the bricks, leading to "soggy" bricks that collapse instantly.

4. Firing Zone Temperature Management (Thermodynamic Control)

Once the bricks reach high temperatures, preventing them from entering a pyroplastic state (melting) is vital.

Anti-Overfiring Measures: Strictly monitor the sintering peak. Exceeding the clay's softening point leads to viscous flow, where the bricks begin to behave like liquid and slump.
Internal Fuel Ratio: Control the amount of internal additives (coal powder or gangue). Excessive internal fuel generates uncontrollable heat within the stack, causing the bricks to "melt from the inside out."
Visual Monitoring: Use inspection holes to watch for "white-out" conditions or "shimmering/swaying" stacks, which are immediate warning signs of imminent collapse.

5. Infrastructure and Mechanical Integrity (Environmental Factors)

The physical environment of the kiln must remain consistent to prevent mechanical triggers.

Track Leveling: Regularly inspect kiln car tracks. Uneven rails cause vibration and jolting, which can topple a stack that is already weakened by heat.
Kiln Structure Maintenance: Check for sagging roof bricks or protruding exhaust ports. Mechanical obstructions are a frequent cause of "domino-effect" collapses during car movement.

How to Crusher Output in Sintered Brick Plants Efficiently？

In sintered brick production lines, the output and quality are often restricted by four key pieces of equipment: crushing equipment, belt conveyor equipment, vacuum extruders, and kiln thermal equipment. Among them, jaw crushers and hammer crushers, as common primary and secondary crushing equipment, directly determine the overall production efficiency of the entire line. Many brick plant operators are eager to maximize crusher output while ensuring the particle size of crushed materials—here are practical and actionable tips to achieve this goal.

First, ensure proper feeding. To make the jaw plates wear evenly and reduce operating costs, gangue or hard shale should be evenly distributed along the feeder inlet and fill the crushing chamber completely. Uneven feeding will not only accelerate jaw plate wear but also reduce crushing efficiency, leading to unnecessary energy waste.

Second, adjust the feeder amplitude reasonably. During normal use of the feeder, you can adjust the amplitude through the knob on the control box within the rated amplitude range according to the required productivity, so as to achieve stepless adjustment of the feeder. Sufficient amplitude ensures that materials enter the crushing chamber continuously and stably, avoiding gaps that affect output.

Third, pay attention to feeding precautions. It is crucial to prevent iron blocks from entering the crushing chamber, as iron blocks can damage jaw plates and other key components. The height of the materials to be crushed should not exceed the fixed jaw plate, and the maximum feed particle size should be smaller than the feed inlet—large blocks are likely to block the crushing chamber and reduce crushing efficiency.

Fourth, set a reasonable discharge port size. The discharge port is the distance between the two jaw plates at the lower end of the crushing chamber. Too small a discharge port will cause blockages and excessive energy consumption, leading to serious damage to the crusher; too large a discharge port will increase the load of the second crushing. Finding the optimal size according to the production needs is the key to improving output.

In addition, regular inspection and replacement of jaw plates, proper lubrication of bearings, and scientific adjustment of the discharge port opening are also essential links to ensure stable and high output of the crusher. By following these tips, sintered brick plants can effectively improve crusher production capacity while ensuring product quality.

Why Poor Drying & Dehumidification Causes Cracked Clay Bricks?

Clay sintered bricks are widely used in construction projects around the world, favored for their durability, thermal insulation, and environmental friendliness. However, many construction teams and brick manufacturers often encounter a frustrating problem: clay bricks crack, crumble, or have uneven texture after sintering. What most people don’t realize is that the root cause of these quality issues is often inadequate drying and dehumidification technology—a key step that is easily overlooked in the brick-making process.

As a professional engaged in the brick-making industry for years, we often receive questions like: “Why do my clay bricks crack after sintering?” “How to make clay bricks stronger and more durable?” Today, we will popularize the critical role of drying and dehumidification technology in clay sintered brick production, and tell you how to avoid common quality problems completely.

First, let’s understand the basic principle: clay raw materials contain a lot of moisture, and if this moisture is not fully removed before sintering, it will expand rapidly when heated in the kiln, generating huge internal pressure. This pressure will directly cause the bricks to crack, burst, or even break into pieces—just like the “tofu bricks” that have been exposed in some quality incidents, which are mostly related to insufficient drying and dehumidification before sintering. In addition, uneven drying will lead to inconsistent moisture content in different parts of the brick blank. During sintering, the shrinkage degree of each part is different, resulting in uneven surface, low compressive strength, and poor weather resistance of the finished bricks.

Many small and medium-sized brick factories still use traditional natural drying or simple hot air drying methods. These methods have obvious defects: natural drying is greatly affected by the weather, and it is easy to cause the brick blanks to get damp again or dry unevenly; simple hot air drying often leads to too fast surface drying and too slow internal moisture diffusion, forming a “dry shell” on the surface, which traps the internal moisture and eventually causes cracks during sintering. These problems not only reduce the qualified rate of bricks but also increase production costs and affect project progress.

The good news is that these quality problems can be completely solved with advanced drying and dehumidification technology. Our company’s clay sintered brick making machine is equipped with a high-efficiency intelligent drying and dehumidification system, which perfectly solves the pain points of traditional drying methods. The system can accurately control the temperature, humidity, and air flow during the drying process, realizing uniform drying of the brick blanks from the inside out. It can quickly and thoroughly remove the moisture in the clay, ensuring that the moisture content of the brick blanks before sintering is controlled at the optimal range of 2% or less—which is the key to ensuring the quality of sintered bricks.

With our machine, you don’t have to worry about cracked, crumbly, or uneven clay bricks anymore. The sintered bricks produced by our equipment have uniform texture, high compressive strength, strong weather resistance, and no cracks or defects. They fully meet the international construction quality standards and are widely used in residential buildings, industrial workshops, and municipal engineering. Whether you are a brick manufacturer or a construction enterprise, our machine can help you improve production efficiency, reduce waste, and create higher economic benefits.

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