Types and characteristics of garbage incinerators

Garbage incinerators are a kind of equipment for treating solid waste. It burns the garbage into ash and smoke through high temperatures, thereby reducing the volume of garbage and disposing of harmful substances. The following are several common types of waste incinerators.

Five types of garbage incinerators

Grate-Type Incinerator

The grate-type incinerator operates continuously and can process over 200 tons of waste per day. It is equipped with a furnace grate at the bottom, and waste is supplied through the upper hopper. The waste to be burned is placed on the furnace grate, and combustion air is blown in from the bottom of the furnace for drying and direct incineration. When using a grate-type incinerator for waste disposal, there is generally no need for waste sorting or crushing, except for large items. The surface temperature of the waste layer can reach up to 800°C, and the temperature range of the flue gas is between 2800 and 1000°C. The incinerator has only one combustion chamber, ensuring reliable combustion, good utilization of residual heat, stable combustion performance, and high burnout rate. Solid waste stays in the furnace for about 1 to 3 mga oras, while gases remain for only a few seconds. This type of incinerator is tall and slim, with a large volume. It requires advanced operational techniques, comes at a higher cost, and the grate must withstand high temperatures, and corrosion, and have good mechanical properties, or it may be prone to damage.

CAO (Controlled Air Oxidation) incineration system

The CAO (Controlled Air Oxidation) incineration system is a new type of waste incinerator with a processing capacity of up to 150 tons per day. Its key features include a two-stage process: first, the waste undergoes thermal oxidation decomposition, followed by gasification and combustion. This results in stable combustion with high burnout efficiency. However, the combustion process is slow, and it demands precise control of oxygen levels and furnace temperatures. If the waste has high moisture content and lacks oil-assisted ignition, stable combustion may not be achieved. The system consists of two combustion chambers: solid waste stays in the first chamber (at temperatures of 600-800°C) for about 3-6 mga oras, while gases pass through the second chamber (at temperatures of 800-1000°C) for approximately 1-3 seconds, driven by a propeller.

Fluidized bed incinerator

The fluidized bed incinerator is made up of porous distribution plates. A large amount of quartz sand is added into the furnace, heated to over 600°C, and hot air (above 200°C) is blown from the bottom, causing the sand to boil. Then, the waste is introduced. The waste boils along with the hot sand, quickly becoming dried, ignited, and burned. Before entering the furnace, the waste needs to be sorted and crushed (10-30cm). Inside the furnace, it undergoes suspended combustion. This high-efficiency process leads to thorough burning. However, the incinerator’s waste processing capacity is limited to under 150 tons per day. The temperature inside the furnace is even, and the combustion rate is relatively fast. Solid waste stays in the furnace for 1-2 mga oras, while gases remain in the furnace for just a few seconds.

Rotary Kiln Industrial Waste Incinerator

The rotary kiln incinerator consists of a rotary kiln, waste feeding device, secondary combustion chamber, and burner, and is equipped with a furnace grate at the rear for secondary incineration. This type of rotary kiln furnace is suitable for processing large-scale waste and industrial waste (such as sludge, paint residue, plastics, etc.) without the need for prior classification or crushing of the waste. It has a processing capacity of over 200 tons per day. Solid waste remains in the rotary kiln for 2-4 hours at a temperature of approximately 900°C. The temperature in the rear incineration chamber is between 1000-1200°C. The resulting ash particles after incineration are small, and the burnout efficiency is relatively high.

Characteristics of four types of garbage incinerators

From the above four types of waste incinerators, it can be observed that conventional waste incinerators generally operate at relatively low combustion temperatures, typically below 1000°C. As a result, some combustible materials may not undergo complete combustion. Hazardous waste components, such as those found in medical waste, are not thoroughly processed, which can adversely affect local soil and water quality, leading to secondary environmental pollution. Additionally, low-temperature incineration can generate dioxins that are harmful to both the natural environment and human health. To ensure comprehensive combustion and achieve zero emissions of dioxins, many advanced technologies have been employed in solid waste treatment since the 1980s. These include ultrasonic methods, gasification-melting techniques, waste-derived fuel approaches, and photochemical oxidation technologies.

Plasma Gasifier

Compared to traditional combustion techniques, plasma technology ionizes the air, reaching temperatures of 3000°C to 10000°C within a fraction of a second. This high temperature causes toxic substances to rapidly break down, preventing the formation of dioxins. Hazardous gases and heavy metals are rendered harmless after treatment in the plasma furnace. When waste is fed into the plasma gasification furnace, organic waste undergoes rapid dehydration, pyrolysis, and decomposition, producing a mixture of combustible gases mainly composed of H2, CO, and some organic gases. This is further subjected to secondary combustion to achieve reduction and harmlessness. Inorganic materials (such as metals, salamin, etc.) melt under the high-temperature plasma, achieving reduction. Compared to traditional combustion, plasma technology provides a more thorough treatment of hazardous waste, generating a crystalline residue that poses no danger and can be used in construction materials without the need for burial. Through this process, waste volume is significantly reduced, toxic substances are broken down, and incineration ash forms glass slag, transforming into harmless material. Plasma technology for high-risk waste is the trend in hazardous waste treatment.

The working temperature range of the plasma gasification furnace is 1200°C to 1700°C, with temperatures near the plasma torch reaching up to 1700°C. This instant high-temperature places demanding requirements on the refractory material’s resistance to thermal stress. The process involves intense thermal radiation, causing rapid heating of the refractory material’s surface, resulting in significant temperature gradients and thermal stress. Additionally, the gasification of waste produces a large amount of water vapor, which, when rising, can severely corrode the refractory material in the upper lining of the furnace.