Boiler chain grate for egg tray drying
A boiler chain grate is a continuous hot air drying equipment commonly used in the egg tray drying process. Its core advantage lies in its chain drive, which enables continuous conveying and uniform heating of egg trays. It is suitable for the low-temperature drying requirements of pulp egg trays (the mainstream material), while also ensuring high efficiency and energy consumption.
AGICO also provides other drying machines for pulp tray drying, such as civil engineering drying line, metal drying line, box type drying machine, brick drying line…
Core advantages of the boiler chain grate
Continuous operation and high efficiency
The boiler chain grate enables 24/7 continuous feeding, drying, and discharging, eliminating the need for frequent starts and stops. A single production line can produce 5,000-20,000 egg trays per hour (adjusted to egg tray specifications and grate width), making it suitable for large-scale egg tray production.
Uniform drying and high egg tray qualification rate
The Boiler Chain Grate’s stable transmission speed (adjustable from 0.5 to 2 m/min) ensures that each egg tray remains in the drying chamber for a consistent period of time.
The drying chamber features multiple hot air conditioning zones (e.g., high-temperature rapid dehydration in the front section and low-temperature shaping in the back section) to prevent deformation and cracking of pulp egg trays due to local overheating. This typically results in a qualified rate exceeding 98%.
Temperature control adapts to the characteristics of egg trays
Pulp egg trays (primarily made of waste paper pulp) have poor heat resistance (easily carbonized above 90°C). The chain grate uses a hot air heat exchanger to precisely control the hot air temperature (50-80°C) and adjust the hot air speed (1-3m/s) to balance dehydration speed and egg tray shape stability.
Wide fuel compatibility and controllable energy consumption.
Based on regional fuel costs, you can choose from biomass pellets (environmentally friendly and low-cost), natural gas (clean but expensive), coal (requires supporting environmental protection equipment), and other fuel options. By optimizing combustion efficiency (such as segmented grate air distribution and waste heat recovery), energy consumption per ton of egg tray drying can be controlled to 80-150kg of standard coal (depending on the fuel type).
Key Control Parameters for Egg Tray Drying (Adjustable Based on Egg Tray Type)
To ensure drying efficiency and equipment stability, the following parameters require focused monitoring:
| Parameter Category | Control Range | Core Impact |
| Hot Air Temperature | 50-80℃ (for Pulp Egg Trays) | Dehydration is slow when below 50℃; egg trays are prone to deformation when above 80℃ |
| Chain Grate Speed | 0.5-2m/min | Insufficient drying if the speed is too fast; low efficiency if the speed is too slow |
| Drying Chamber Humidity | ≤40% (Exhaust Port Humidity) | High humidity leads to reduced drying efficiency |
| Fuel Combustion Temperature | 600-1200℃ (Grate Area) | Insufficient heat exchange if the temperature is too low; fuel waste if the temperature is too high |
| Hot Air Velocity | 1-3m/s (Inside Drying Chamber) | Poor heat exchange if the velocity is too low; egg trays are easy to be blown over if the velocity is too high |
Civil Construction Chamber
Boiler chain grate drying chambers are constructed using civil construction. In some industrial drying projects, civil construction drying chambers offer unique advantages due to their stable structure and well-planned space, making them suitable for drying egg trays with chain grate heaters.
Civil construction drying chambers are typically constructed of brick-concrete with thick walls (typically 240mm or 370mm), providing effective insulation and reducing heat loss.
The layout of the civil construction drying chamber must precisely align with the hot air output of the chain grate heater. A dedicated hot air inlet can be installed on the side or bottom of the drying chamber, connected to the heater heat exchanger via a high-temperature-resistant air duct.
Ventilation and moisture removal are key design considerations for civil construction drying chambers. During the egg tray drying process, a large amount of water evaporates, which needs to be removed promptly. Multiple moisture-draining vents should be located on the top or sides of the drying chamber. The area should be calculated based on the drying chamber volume and egg tray production, typically accounting for 2%-5% of the chamber’s surface area. Air inlets should also be located on the bottom or sides to draw in fresh, cool air, ensuring optimal convection.
Core working principle of chain grate for egg tray drying
Combustion Heat Exchange + Chain Conveying + Hot Air Drying
When chain grates are used for egg tray drying, the overall process can be divided into two major steps: fuel combustion heat exchange and continuous drying of the egg trays.
Fuel combustion and hot air generation
The lower part of the chain grate is the combustion system. Fuel (commonly found in biomass pellets, coal, natural gas, etc.) is evenly spread on the grate. Staged air supply controls combustion intensity, generating high-temperature flue gas (typically 600-1200°C).
The high-temperature flue gas enters the hot air heat exchanger (to prevent direct contact with the egg trays and contamination), where it undergoes heat exchange with cold air to generate clean hot air (the hot air temperature for drying is 50-80°C and requires precise control).
The low-temperature flue gas after heat exchange undergoes environmentally friendly treatment, including dust removal and desulfurization, before being discharged, meeting current industrial waste gas emission standards.
Continuous egg tray drying in a boiler chain grate stoker process
Wet egg trays to be dried (pulp egg trays with a moisture content of approximately 60%-70%) are evenly placed on a high-temperature chain grate (the grates are typically mesh or plate-shaped to prevent the trays from getting stuck) via a feed conveyor.
The chain grate carries the egg trays at a constant (adjustable) speed into a sealed drying chamber. Clean hot air in the drying chamber, using either an upward and downward blowing or side-blowing method, fully contacts the egg tray surface and quickly removes moisture.
The dried egg trays (with a moisture content reduced to 8%-12%) are discharged from the chain grate and cooled in the cooling section before entering the subsequent finishing process.
The humid air evaporated during the drying process is discharged through a dehumidification fan, and some of the excess heat is recovered in the hot air system, reducing energy consumption.
Chain grate operational precautions
Before feeding, ensure the egg trays are evenly spaced to avoid stacking (wet pulp egg trays have low strength and are prone to deformation).
When starting the machine, preheat the hot air system and wait until the hot air temperature stabilizes to the set value before feeding to prevent moisture absorption from the egg trays caused by cold air.
Regularly clean pulp residue from the chain grate gap to prevent jamming and air flow obstruction. Check the hot air heat exchanger weekly for scaling (which affects heat transfer efficiency).
