Applicable materials and production process steps of continuous carbonization production line

Applicable materials

Agricultural waste

A large amount of waste generated in agricultural production, such as rice husks, peanut shells, corn cobs, bagasse, and various types of straw (corn stalks, sorghum stalks, sesame stalks, cotton stalks, bean stalks, etc.), are all high-quality raw materials for continuous carbonization production lines. These wastes are widely available and low-cost. After carbonization, they can be converted into high-value-added products, such as used to make activated carbon, provide adsorption materials for industrial production; made into biochar-based fertilizer, improve soil structure, increase soil fertility, and promote crop growth.

Forestry waste and products

Forestry waste and related products are also ideal materials. Wood chips, bamboo chips, branches, bark, coconut shells, palm shells, etc. can be processed into high-quality charcoal through continuous carbonization production lines. This type of charcoal is deeply loved by consumers in the barbecue field because of its smokeless and high calorific value. In the metallurgical industry, it can be used as a reducing agent to participate in the metal smelting process; in the chemical industry, it is also an important raw material.

Other biomass materials

Biomass materials such as hemp stalks and tobacco stems can also be effectively utilized in the continuous carbonization production line. Carbonized hemp stalks and tobacco stems can be used in different industrial and agricultural fields, expanding the application scope of biomass resources.

Production process steps

Raw material preparation

Strictly screen all kinds of materials, and use screening equipment to remove impurities such as stones and metals mixed in them to prevent these impurities from damaging subsequent production equipment. According to the material characteristics and production requirements, use a crusher to crush the materials to a suitable size. Generally, the material particle size is required to be no more than 2 cm. This can increase the surface area of ​​the material, so that it can be heated more evenly during the subsequent drying and carbonization process, and improve production efficiency and product quality.

Drying treatment

Select a suitable dryer, such as a drum dryer, airflow dryer, etc., to dry the crushed materials and reduce their moisture content to less than 15%. During the drying process, the temperature and time must be accurately controlled. Usually, the drying temperature is between 100-150℃, and the time depends on the initial moisture content of the material and the performance of the equipment, generally 1-3 hours. If the temperature is too high or the time is too long, the material may be over-dried or even cause combustion; if the temperature is too low or the time is too short, the ideal drying effect cannot be achieved, affecting the subsequent carbonization.

Gasification in gasifier

The dried raw materials are ignited in the gasifier, and the flue gas produced by the combustion of the raw materials contains combustible gases such as carbon monoxide, hydrogen, and methane. Through a series of flue gas purification equipment, such as cyclone separators, bag dust collectors, spray towers, etc., impurities such as dust and tar in the flue gas are removed to turn the flue gas into clean combustible gas. These combustible gases serve as an important heat source for the early heating of the carbonizer and provide energy support for the subsequent carbonization process.

Feeding

When the temperature of the carbonization furnace is heated by the combustible gas generated by the gasifier to reach the temperature required for material carbonization (usually around 400°C), the feeder is started to continuously transport the raw materials to the carbonization host. The feeding process should be kept stable and uniform to avoid feeding too fast or too slow, which will affect the continuity and stability of carbonization.

Main engine pyrolysis and carbonization

Pyrolysis drying: At the beginning of heating, the water in the material begins to evaporate, which is a process of discharging steam. The higher the moisture content of the material, the longer the process lasts, and the working time required for the gasifier to maintain the temperature also increases accordingly. This stage is an endothermic reaction, and heat needs to be continuously provided from the outside to ensure the smooth progress of the drying process.

Pre-carbonization: When the water in the raw material is completely evaporated, as the temperature continues to rise and reaches above 300℃, the raw material enters the pre-carbonization stage. At this time, unstable components such as hemicellulose in the raw material begin to decompose, and flue gas containing a variety of combustible gases (such as carbon monoxide, methane, ethylene, etc.) is produced and discharged. These combustible gases have a certain calorific value and can be recycled later.

Flue gas recovery: The flue gas discharged in the pre-carbonization stage will not be directly discharged into the atmosphere, but enter a special flue gas purification equipment. After purification, the impurities in the flue gas are removed and turned into mixed fuel gas, which is used as a heat source for the carbonization process again to achieve energy recycling. At the same time, during the purification process, components such as tar and wood vinegar will be separated and precipitated, which can be further processed and utilized.

Pyrolysis carbonization: As the temperature continues to rise, the raw materials begin to decompose rapidly, and complex thermochemical reactions occur, generating a large amount of gas, tar and biochar. At this stage, the temperature and reaction time must be strictly controlled to ensure that the quality and output of biochar meet the expected requirements.

Cooling and discharging

The temperature of the carbonized material (biochar) is high and needs to be cooled. Forced cooling methods such as air cooling or water cooling can be used to quickly reduce the temperature of biochar through special cooling equipment such as cooling conveyors and cooling water tanks. During the cooling process, it is necessary to prevent high-temperature biochar from spontaneous combustion or oxidation when in contact with air, which will affect the quality of the product. The cooled biochar is discharged from the carbonization furnace and sent to the storage area or to the subsequent processing link through conveying equipment such as belt conveyors and screw conveyors.

Subsequent processing

According to the different uses of biochar, it is further processed. If it is to be made into barbecue charcoal, it may be necessary to add a binder, and go through processes such as molding and drying; if it is used to produce activated carbon, it needs to be activated to improve its adsorption performance. At the same time, the by-products such as gas and tar produced during the carbonization process are collected, separated and purified to maximize the recycling of resources and reduce pollution to the environment.

The continuous carbonization production line realizes the efficient conversion of biomass and the recycling of resources through the effective use of a variety of materials and scientific and reasonable production process steps. It has important significance and broad development prospects in the fields of environmental protection and economy.