In the process of producing pyrolysis oil from waste plastics, continuous pyrolysis equipment has demonstrated superior performance and significant advantages. Compared to batch pyrolysis equipment, continuous plastic pyrolysis system offers a substantial increase in processing capacity. A single continuous pyrolysis unit can have a maximum capacity of 20-30 tons, meeting the needs of large-scale production. This allows continuous pyrolysis equipment to complete tasks more efficiently when facing the ever-increasing volume of waste plastics.
The continuous plastic pyrolysis system allows for simultaneous operation of all functions, including feeding, pyrolysis, condensation, and slag discharge. This feature avoids frequent shutdowns and significantly saves time. The continuous process allows for continuous feeding and discharging, greatly improving the production efficiency of pyrolysis oil from plastic.
Both the feeding and slag discharge sections of the continuous pyrolysis equipment are completely sealed. This sealed design effectively reduces pollutant emissions, preventing dust and carbon black pollution.
During feeding, a sealed auger transports the plastic particles into the pyrolysis reactor. This prevents the waste plastic from contacting the outside air during transport, reducing odor and dust emissions.
During slag discharge, carbon black is continuously discharged through the sealed system, preventing carbon black from flying and minimizing environmental impact. This makes the continuous pyrolysis equipment far superior to traditional equipment in terms of environmental friendliness, better meeting the stringent environmental requirements of modern society.
Pre-treated plastic granules are fed into the pyrolysis reactor through a sealed auger. This process is crucial, as the sealed auger ensures a closed, oxygen-free environment within the furnace during feeding. An oxygen-free environment plays a key role in the smooth progress of the pyrolysis reaction. It prevents the plastic from oxidizing with oxygen during heating, thus ensuring the pyrolysis reaction proceeds successfully.
If a closed, oxygen-free environment cannot be maintained during feeding, oxygen will enter the furnace, causing the plastic to burn or oxidize. This consumes a large amount of energy and produces a large amount of waste gas, affecting the pyrolysis efficiency.
After the plastic particles enter the pyrolysis reactor, the burner is turned on to begin heating. During the heating process, different oil and gas release patterns occur as the temperature gradually rises.
When the temperature reaches approximately 160℃, a small amount of oil and gas begins to release. This is because at this temperature, some low-boiling-point components in the waste plastic begin to decompose, producing small-molecule gaseous hydrocarbons.
As the temperature further rises to 280-320℃, a large amount of oil and gas is released. Within this temperature range, most plastic molecules begin to undergo thermal pyrolysis. The molecular chains break, generating various gaseous and liquid hydrocarbon compounds. This is a stage with a higher oil yield.
As the temperature continues to rise, the amount of oil and gas released gradually decreases. When the temperature reaches a certain level, until no more oil and gas are released, it indicates that the plastic has been fully pyrolyzed.
This process requires precise control of the heating rate and temperature to ensure that the thermal pyrolysis reaction proceeds fully. Simultaneously, excessive pyrolysis should be avoided, as this would lead to a decrease in oil yield and a decline in oil quality.
The oil vapors released from the refinery successively enter a buffer tank, a horizontal condenser, a shell-and-tube condenser, and a condensing tower for thorough cooling.
The buffer tank buffers the flow rate of the oil vapors, ensuring a smooth entry into subsequent condensation equipment. It also settles some impurities, improving the purity of the oil vapors.
The condensers utilize heat exchange principles. They transfer heat from the oil vapors to the cooling medium, lowering the temperature and gradually liquefying the vapors. The condensing tower further enhances the condensation effect, ensuring the oil vapors are fully liquefied into oil. After multi-stage condensation, the liquefied oil is temporarily stored in an oil tank.
In this process, the rational design and efficient operation of the multi-stage condensation equipment are crucial for improving oil yield and oil quality. Poor condensation results in some oil vapors failing to liquefy. This unrefined vapor is directly released into the atmosphere, wasting energy and polluting the environment.
During pyrolysis, in addition to condensable oil and gas, a portion of non-condensable gases is also produced. These gases contain certain amounts of combustible components, such as methane and ethane.
To achieve energy recycling and reduce pollutant emissions, the remaining non-condensable gases are purified in a desulfurization and deodorization tower. They can then be directly returned to the refinery furnace for use as fuel. This approach is energy-saving, environmentally friendly, and reduces production costs.
Through these stringent purification measures, harmful substances in the flue gas are effectively removed. This ensures that the emitted flue gas meets environmental standards and reduces atmospheric pollution.
The carbon black remaining in the continuous oil refining furnace is continuously and sealedly discharged through the slag discharge system and collected in unified packages. Carbon black is one of the important by-products of pyrolysis waste plastics and has certain economic value.
The continuous sealed slag discharge system ensures that carbon black does not leak during the discharge process, avoiding environmental pollution. At the same time, the collected carbon black can be further processed, maximizing resource utilization.
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