It is widely used in domestic hazardous waste disposal industry. The quality of refractory materials of rotary kiln affects whether the rotary kiln can operate stably. Fused magnesia The selection and maintenance of refractory materials for rotary kiln for hazardous waste treatment are analyzed for reference in practical engineering. Hazardous waste has corrosive, toxic, flammable, reactive, infectious and other hazardous characteristics according to the definition of the National Catalogue of Hazardous Wastes. It may cause harmful effects on the environment or human health and needs to be managed as hazardous waste. Among them, thermal treatment (incineration) of hazardous waste can not only completely eliminate the toxicity and harmfulness of waste, but also reduce the volume of hazardous waste to the greatest extent, which is the most powerful means of harmless and reduced waste. At present, most of the newly built hazardous waste incineration and disposal projects in China prefer rotary kilns as hazardous waste treatment furnaces, which can effectively treat hazardous wastes of different shapes and phases.
Rotary kiln incinerator, also known as rotary kiln, is a slightly inclined steel hollow cylinder lined with firebricks. Most waste materials are heated by the gas generated in the combustion process and the heat transmitted by the kiln wall. Solid waste is sent into the kiln from the front end for incineration, and the purpose of mixing waste is achieved by rotating. Proper inclination shall be maintained during rotation to facilitate the sliding of solid waste. In addition, waste liquid and waste gas can be sent from the kiln head or the secondary combustion chamber, and even the whole barrel of waste can be sent to the rotary kiln incinerator for combustion.
Rotary kiln incineration technology is the most mainstream technology in hazardous waste incineration technology at present, and is the most widely used furnace type, Light burned magnesium powder It is a multi-purpose incinerator with strong adaptability and can incinerate various solid, semi-solid, liquid and gaseous wastes. All kinds of combustible wastes of different shapes and shapes (particles, powders, blocks and barrels) can be sent to the rotary kiln for incineration.
When hazardous wastes are incinerated in a rotary kiln, they generally go through several stages, such as drying, pyrolysis, combustion and burnout. After these stages, the harmful components in hazardous wastes are fully decomposed and destroyed under the action of high temperature, forming high-temperature flue gas and slag. These high-temperature flue gas and slag will cause corrosive damage to the refractory laid in the rotary kiln.
(1) High temperature resistance. It can operate at high temperature above 800 ℃ for a long time.
(2) High strength and excellent wear resistance. Refractories in the rotary kiln need to have certain mechanical strength to withstand the expansion stress at high temperature and the stress caused by the deformation of the rotary kiln shell.
(3) Good chemical stability and thermal stability to resist the corrosion of chemical substances in flue gas and withstand the alternating thermal stress under incineration.
(4) Good thermal expansion stability. Although the thermal expansion coefficient of the rotary kiln shell is greater than the thermal expansion coefficient of the rotary kiln refractory, the shell temperature is generally about 150~300 ℃, and the temperature of the refractory is generally above 800 ℃, which may cause the refractory to be larger than the thermal expansion coefficient of the rotary kiln shell and easy to fall off.
(5) The porosity should be low. High porosity will make the flue gas easily penetrate into the refractory and corrode the refractory body.
