The urban garbage problem has brought serious adverse effects to urban management, urban natural environment, residents' living environment, human health and people's mental state. Proper disposal of the increasing amount of urban waste has become an increasingly urgent issue in urban management. Common methods of disposal of municipal solid waste include: landfill, composting, pyrolysis, and incineration. According to the sustainable development strategy, the goal of waste treatment should be to achieve harmlessness, reduction and resource utilization. Incineration is the fastest and most effective technical method for waste reduction. At the same time, incineration can completely eliminate harmful bacteria and viruses and can recover energy. The main equipment for waste incineration treatment is the waste incinerator. After investigation, analysis and application research, it is found that the refractory materials used in the waste incinerator must have the following properties: (1) Excellent high-temperature volume stability: (2) Excellent high-temperature strength and wear resistance Damage performance (3) Excellent resistance to thermal shock stability caused by temperature fluctuations (4) Excellent corrosion resistance (CO, CI2, SO2, NO2, high temperature melt, alkali metal vapor, etc.); (5) Excellent construction performance Cost-effectiveness: (6) Excellent heat resistance and insulation performance. In the past 10 years, as waste incinerator technology has developed towards larger incinerators, resource utilization and automation, the refractory materials used in incinerators have also undergone major changes. The biggest technological progress is as follows: (1) The amount of amorphous refractory materials has increased to about 75%. It greatly simplifies the construction process of complex parts, enhances the integrity and air tightness of the furnace lining, and extends the service life. Its production process also saves energy and has a good performance-price ratio. (2) The application of refractory fiber can greatly reduce heat dissipation loss and heat storage loss. The incineration temperature of the garbage incinerator is not very high, and it still contains a certain amount of unburned combustibles, a certain amount of heavy metals and dioxins. If it is not handled properly, it will be placed or landfilled at will, which will cause serious harm to the atmosphere, groundwater, soil, etc. pollute. In order to solve the secondary pollution of waste incineration ash and slag, waste ash slag melting and solidification treatment technology will be used. This technology studies chromium-free (hexavalent chromium pollutes the environment) refractory materials, namely AL2O3-ZrO2, AL2O3-MgO, SiC and other refractory materials with good corrosion resistance and other high-temperature properties. It is the current research and Technical direction to solve the problem of service life of garbage ash melting furnace and the problem of industrialization promotion. This is also the focus and key to the promotion of garbage ash smelting treatment technology in my country and the research on the preparation technology and application technology of pollution-free refractory materials.
1: Types of garbage incinerators
(1) The push-type incinerator introduces combustion gas from the lower part of the grate and drags the grate to continuously burn the garbage. It is suitable for large-scale treatment of garbage and is widely used in garbage incineration in big cities.
(2) The fluidized bed incinerator uses heat storage sand as the heat medium to instantly incinerate garbage. Sand and reaction materials (containing high-alkali substances, etc.) are not burned. The working temperature is adjusted to a maximum of 1000°C to control the sintering of sand. In order to prevent overheating, sludge and other high-water-containing materials can be quickly incinerated. It is suitable for incineration of garbage, sewage sludge and industrial waste in medium and small cities.
(3) The rotary incinerator uses the radiant heat in the furnace to fully incinerate waste. It is mainly used for incineration of industrial waste such as sludge and waste liquid.
Two: SiC refractory materials for waste incinerators
The working temperature of waste incinerators for processing waste generally does not exceed 1200°C, but the gases (CI2, So2, CO etc.) The chemical attack on refractory materials is extremely serious.
Refractory materials for incinerators are roughly divided into refractory bricks and amorphous refractory materials. The former are mainly clay bricks, high alumina bricks and silicon carbide bricks; the latter are mainly clay, high alumina and silicon carbide castables and clay and high alumina plastics. With the enlargement of waste incinerator technology and resources, the refractory materials of incinerators have also undergone tremendous changes.
The temperature in the combustion chamber of the incinerator is as high as 1000~1300℃: the molten slag causes serious damage to the side wall refractory bricks, and accidents often occur. In terms of service life and corrosion resistance, it is advantageous to use SiC bricks.
Plastics and sodium chloride and other salts in the garbage cause serious corrosion to the pipe walls. In order to protect the water pipes, dense SiC castables have been used. The advantages are good durability and construction in the middle and upper parts. High efficiency, but the disadvantage is that it is difficult to disassemble.
Generally, SS-1 (SiC85%), SS-2 (SiC40%), and SA-1 (AL2O3 53%) are commonly used. The main reasons for using SiC refractory materials are that the slag is difficult to adhere and has good corrosion resistance.
According to experiments, the use of SiC furnace linings in incinerators can be determined based on ① operating temperature: ② metal oxides such as FeO: ③ use conditions of various oxidizing gases such as H2O and CO2 to determine the SiC content and material. In addition, the SiC-based furnace lining should not be used in the oxidizing atmosphere layer above the molten slag line. It is best to limit its use at the bottom of the furnace and should be used below the reducing atmosphere.
Summary: The proper disposal of urban garbage and industrial waste has become an urgent issue in contemporary urban management. However, with the development of waste incinerators in our country, the development of efficient and economical refractory materials for incinerators has become the key to promoting waste incineration technology.