One of the ways to recycle waste is pyrolysis. Pyrolysis is a method of thermal decomposition of polymeric materials or organic substances under the action of temperature in the absence of an oxidizing environment. In contrast to the methods of combustion and gasification during pyrolysis, the aim is usually to obtain products in the processing of raw materials or waste.
As a result of the pyrolysis of polymeric materials, three competing products are inevitably formed: liquid products, coke residue and gas. The yield of these products depends on the conditions of the process and the properties of the processed raw materials. At elevated temperatures, the main product is pyrolysis gas, as a product of a more complete thermal decomposition of high-molecular-weight organic compounds into low-molecular ones. At low intensity of the process (heating rate) and increased pressure, the prevailing product is coke residue or char, as a product of secondary and tertiary processes, mainly synthesis and condensation from intermediate products. At high intensity and moderate temperature (usually for most organic polymers 450-550 degrees C) the main product is liquid organic products.
Table 1
Types of pyrolysis
Different types of raw materials give different yields of products. Table 2 presents material balances in the processing of various types of raw materials by the method of fast ablative pyrolysis.
Table 2
Material balance for various types of raw materials
Thus, the pyrolysis technology allows you to implement a flexible solution for the processing of a wide class of polymer waste and biomass into fuel and chemical products, and the waste management business using such equipment pays for itself quickly and brings high income.
What is a pyrolysis plant
Pyrolysis plants have a very extensive classification and many types. Distinguish between batch and continuous installations, classified by the device of the reactor, condenser and process type. However, each pyrolysis unit typically has a reactor (retort, in the case of a batch process), a condenser, and an energy module (furnace). Sometimes, when the goal is to obtain only a solid product, the condenser is excluded from the circuit and the entire vapor-gas mixture is burned in the furnace. Some designs to reduce energy losses provide for combining the reactor and the energy module, however, in this case, temperature control becomes more complicated and higher requirements are imposed on the construction materials of the reactor, since the pyrolysis process temperature and the effective combustion temperature of the pyrolysis gas are significantly different. Installations of a periodic type are less effective compared to continuously operating ones, since as a result of cyclic heating, it is difficult to ensure product quality stability. And if the retort is cyclically removed from the high-temperature zone, then the thermal efficiency is reduced, due to the need to warm up and cool the retort comparable to the load by weight during each cycle. In addition, the structural material of the reactor during cyclic operation has a low resource as a result of frequent “stresses” caused by heating – cooling.
According to the degree of automation, pyrolysis plants are distinguished into fully automated complexes, partially automated and mechanized installations that require manual labor, and non-mechanized solutions that have lost their importance. The control of temperature and pressure is important in the pyrolysis process, since the safety of the process and the quality of the products depend on these parameters.
FPP02 plant for waste processing is a specialized technical complex that processes waste in several process stages.
The main ones are:
- preparation of raw materials,
- drying,
- pyrolysis,
- condensation.
Depending on the type of raw material and its particle size distribution, its preliminary grinding, sorting or cleaning is initially carried out.
Further, depending on the moisture content of the raw material, it is dried to a moisture content no higher than 15%. Drying of wet and hydrophilic materials is necessary to increase the efficiency of the pyrolysis plant. The fact is that wet raw materials are problematically heated to temperatures above the boiling point of water, since the phase transition (evaporation) process is associated with very substantial heat consumption, sometimes different from the specific energy cost of thermal decomposition by an order. As a result, the pyrolysis reactor turns into a large “pan” in which water boils away, but not pyrolysis. Evaporate water from raw materials is more efficiently in special dryers. In addition, evaporated water in the pyrolysis reactor also degrades the quality of pyrolysis products. Therefore, the drier the raw materials, the more efficient the pyrolysis process will be.
Fast pyrolysis is a thermal decomposition of biomass without oxygen access at temperatures of 450-550 ° C, high heating rates of 500-1000 ° C / s and a low residence time of products in the reaction space (up to 5 seconds). As a result of the process vapor-gas mixture is formed.
Condensation is the transition of a substance from a gaseous to a liquid or solid state. As a result of rapid cooling and condensation, the vapor-gas mixture of the pyrolysis process is transformed into liquid and solid products.
To implement the above-mentioned process steps, the FPP 02 Fast pyrolysis plant consists of the following main blocks and elements:
- Feeding module
- Reactor
- Energy module
- Condensation module
- Cleaning module
- Discharging module
- Mechanized supply warehouse
The principle of the plant
The technological process in the FPP 02 plant is carried out as follows: the crushed and dried raw materials are fed into the feed bin of the feeding module, from where it is fed to the reactor through a two-valve lock device. In the reactor, under the action of heat generated in the energy module, in the absence of oxygen, mechanically activated thermal decomposition of the raw material is carried out, resulting in the formation of coal and steam-gas mixture. The gas-vapor mixture is fed to the cleaning module, where the gas-vapor mixture is separated from the coal dust and then fed to the condensation module. Fine coal from the reactor is fed with a screw feeder to the discharging module, where it is accumulated and distributed. It is possible to feed char either for unloading or for burning into the energy module.
The fast cooling and condensation of the vapor-gas mixture in the condensation module allows the separation of the liquid component and combustible gas. In this case, the combustible gas is fed for combustion into the energy module in order to provide energy for the pyrolysis process.
Such a scheme can be used for the utilization of various materials, it can be used as an installation for processing oily wastes. Control is carried out from a separate room in which the operator’s console is installed. From here, the operator controls the process and, if necessary, regulates the pyrolysis temperature.
What waste can be processed with the plant
The waste processing complex allows the utilization of the following materials:
- sorted industrial and household wastes;
- waste of the enterprises of oil refining industry;
- waste of woodworking industries;
- car tires and other rubber products;
- plastics;
- various types of peat and slate;
- sludge deposits formed in sewer systems;
- recycled sleepers;
- bird litter and litter mass;
- waste of agro-industrial complex;
- Tetra Pak.
Such a complex for processing household waste will be especially useful for the utilization of organic waste from farms, poultry farms and agricultural fields (manure, husks, straw, leaves, food waste).
Benefits of a waste treatment facility
Equipment for the pyrolysis of waste which can create a complete complex for processing pre-sorted garbage (organic part) for a small amount of money, can be used both in large enterprises and in small workshops. Such devices do not require the organization of large landfills for disposal, and for installations there is no need to build special rooms with any special requirements.
The FPP 02 fast pyrolysis plant is adapted for operation in open areas and works well even when exposed to external factors such as temperature drops or rain and snow.
The main advantage of such devices for large enterprises is the absence of the need for additional expenses for the export and disposal of their own waste by third parties. Consequently, you can save on additional labor and transport. One such plant pays off within no more than three years of use.
We offer pyrolysis plants at a reasonable price. Our experts will help to deliver and install the equipment, after which it can be operated without the need to perform any additional actions. Service maintenance and repair can also be provided by representatives of our company. As part of an individual warranty service contract, we provide after-sales service.