The application and development of waste incineration technology in foreign countries has a history of several decades, the more mature types of furnaces are pulse-throwing grate incinerator, mechanical grate incinerator, fluidized bed incinerator, rotary incinerator and CAO incinerator. For medical waste incineration commonly used incinerators are fixed grate furnace, rotary kiln incinerator and gasification pyrolysis incinerator.
1. Rotary kiln type incinerator
Rotary kiln is the activity of the hearth in the most widely used type of furnace. Furnace technology is mature, simple and flexible, widely used in the incineration of various types of solid, semi-solid and liquid wastes, especially suitable for incineration of high water content, difficult to deal with medical waste and hazardous wastes, it is to deal with a large amount of small footprint, harmful components of the high rate of breakage and the equipment is simple to be a long-term continuous operation of the characteristics of the countries are widely used.
The rotary kiln is a horizontal and rotatable cylindrical cylinder. Shell made of sheet rolls, lined with refractory materials; cylinder axis and the horizontal plane to maintain a certain angle of inclination, solid and viscous waste from the kiln head (upper), with the rotation of the kiln body slowly moving to the tail, the rotation of the kiln body so that the material in the combustion process and the combustion air fully in contact with the completion of drying, combustion, combustion, the whole process of combustion. Finally, the burning slag will be discharged from the tail. The materials which are not decomposed completely will enter the second combustion chamber for full combustion. The combustion air is taken from the silo to ensure that the odor of the silo is not leaked. The kiln shell is made of rolled and welded carbon structural steel plate. The refractory material inside the kiln is acid-resistant refractory clay brick.
The second combustion chamber is a cylindrical cylinder perpendicular to the ground, and its main role is to make further high temperature decomposition of the rotary kiln body of the unburned hazardous substances, but also some of the liquid waste can be sprayed into the incineration. In order to make the unburned material thoroughly decomposed, the second combustion chamber is equipped with a secondary air inlet device and furnace gas nozzle to ensure that the flue gas at high temperatures with full contact with oxygen and flue gas in the second combustion chamber retention time. The size of the air inlet of the second combustion chamber can be automatically adjusted according to the oxygen content of the flue gas at its outlet. The second combustion chamber is a refractory brick structure with an internal high alumina refractory layer, perlite and alumina silicate fiber felt for insulation, and an external heat-resistant steel plate. In order to ensure the safety of the system, there is an emergency discharge safety valve on the top of the second combustion chamber. The emergency discharge safety valve can be opened automatically according to the pre-set opening conditions.
2. Fixed grate incinerator
Grate incinerator is a kind of grate furnace, but also a kind of the simplest incinerator. Furnace shell with steel plate processing and welding, incineration chamber with refractory masonry or the use of prefabricated refractory materials, in the refractory bricks and steel shell filled with insulation materials between. The lower part of the incinerator is equipped with a fixed grate, and the feed opening can be set in the upper part of the incinerator, the front or the side.
The garbage to be processed by hand will be placed in the furnace, the manual flattening, so that it is evenly spread on the grate, the lower part of the grate that is for the ash pit and as a ventilated room, by the ash door at the natural ventilation into the combustion air, or the use of fans to force ventilation. In order to make the garbage incineration completely, in the incineration process, the need to turn the material layer, burned out of the ash fall in the grate below the ash pit, manual pick out. The side walls of the incinerator are equipped with combustion aids to enable the incinerator to start, stop and when the calorific value of the garbage is low. The temperature inside the incinerator is generally controlled at 700 ℃ - 800 ℃ or so, after the incineration of flue gas and unburned combustibles into the second combustion chamber for complete combustion, the temperature of the second combustion chamber is generally controlled at 900 ℃ - 1000 ℃ or so. Fixed grate incinerator structure is simple, easy to operate, due to manual operation, intermittent operation, poor labor conditions, low efficiency, dial material is not sufficient when the incineration will be incomplete, for the larger amount of garbage and difficult to burn solid waste is not applicable.
3. Gasification pyrolysis incinerator
Gasification pyrolysis incinerator has two incineration chamber, a combustion chamber and the two combustion chamber, the shell is welded with steel processing, the internal masonry refractory materials, the chamber with the furnace wall separation, the entire incinerator, the gas flow in the vertical direction constantly changing the direction of movement, so that from a combustion chamber out of combustible gases, combustible dust particles, such as sufficiently mixed to fully combustible.
Waste from the incinerator front end of the upper charging hopper through the chute into the pneumatic door will be sent to the waste of a combustion chamber, into a combustion chamber of the garbage through the temperature regulation, heated by the refractory wall or disposable burner, a combustion chamber air from the bottom, the top, the front of the blowing, the large particles in the second combustion chamber before entering the chamber, through the bottom of the furnace chamber mounted on the air nozzle burned out. At the bottom of the primary combustion chamber there are two ash conveyors, which automatically rotate the waste and transport the ash to the ash chamber, where it finally burns out and enters the ash hopper. The unburned flue gas is mixed in the inlet of the second combustion chamber, and then completely burned out in the second combustion chamber, with the temperature of the first combustion chamber being 500℃-800℃, and the temperature of the second combustion chamber being 900℃-1100℃, and the residence time being more than 2 seconds.
In the first combustion chamber, the second combustion chamber side walls are equipped with auxiliary burners, in the incinerator start and waste calorific value of low to maintain the temperature of the furnace when used.