Catalytic incinerator Catalytic incinerator is also called catalytic incinerator and catalyst incinerator. Catalytic incineration method. Until now, almost all three wastes have been treated by oxidative combustion, which oxidizes and decomposes harmful wastes to CO2 and H2O at temperatures above 900 ° C, thereby purifying exhaust gas.Therefore, it consumes a lot of energy and is extremely uneconomical.The catalytic combustion method is used to make the organic waste gas into a harmless substance under flameless and low temperature (combustion reaction temperature is generally 250-500 ℃). The heat can be self-sufficient or only a small amount of heat must be added during combustion.The exhausted heat can be recovered and used.It has been used abroad for a long time. In recent years, a few research units in China have carried out development research.The characteristics of the catalytic incineration method: low ignition temperature, generally 200-280 ° C, short reaction time and high purification efficiency, thus saving a lot of energy, only one third of the oxidative incineration method. Catalyst types: Pt, Fe-Cr, Cu-Cr, Pt-Al2O3, etc. When using a catalytic incinerator, the preheating temperature and flow rate of the exhaust gas must be controlled, and the distribution must be uniform. Generally, the reaction temperature of the catalyst bed is not greater than 600 ° C, which ensures the use of the catalyst. Life span is 1 to 4 years. Catalytic combustion has been applied in the treatment of acrylonitrile tail gas in China.Practice has proved that the processing capacity is large (20000m3 / h), the exhaust gas is purified, the waste heat can be recovered, and the economic benefits are significant. Incinerator design principles The basic principle of the design of the garbage incinerator is to make the waste in the furnace according to the prescribed incineration temperature and sufficient residence time to achieve the full combustion effect.This requires the selection of a suitable hearth, reasonable design of the shape and size of the hearth, increasing the chance of garbage and oxygen contact, making the water vapor easy to evaporate and accelerate combustion during the incineration process, and controlling the flow rate and direction of air and combustion gas. Allows the gas to mix uniformly. Furnace type When selecting the furnace type, you should first see whether the combustion mode (gas-controlled or peroxy-combustion) of the selected furnace type is suitable for the nature of all wastes being processed.Peroxy-combustion means that a combustion chamber supplies sufficient air (that is, more than the theoretical air amount); gas-controlled combustion (hypoxic combustion) means that the amount of air supplied by a combustion chamber is about 70% to 80% of the theoretical air amount In a hypoxic state, the garbage is cracked into smaller molecules of hydrocarbon gas, CO and a small amount of fine carbon particles in this chamber, and then the sufficient air is supplied to the second combustion chamber to oxidize it into a stable gas.Due to the staged air supply, the combustion reaction can be stabilized, relatively less pollutants are generated, and the amount of air supplied in a combustion chamber is small, and the particulate matter is relatively small. It is designed for current incinerators More commonly used mode of operation. Generally speaking, peroxygen combustion incinerators are more suitable for incineration of non-combustible wastes or more stable incineration wastes, such as wood chips, paper, etc., while gas-controlled incinerators are more suitable for incineration of flammable wastes, such as plastics and rubber. And polymer petrochemical waste; grate-type incinerator is suitable for domestic waste; rotary kiln incinerator is suitable for hazardous waste. In addition, factors such as the structure and airflow mode of the combustion chamber, the air supply method, the quality of the stirring performance, and whether short-flow or bottom ash is easily disturbed should also be considered.The direction of the gas flow in the incinerator depends on the type of incinerator and the characteristics of the waste.The orientation of a multi-chamber incinerator is usually burned vertically upward; a rotary kiln incinerator usually burns downward; and liquid jet incinerators, exhaust gas incinerators, and other cylindrical incinerators can take any direction, depending on the specific form The form and nature of the waste to be incinerated.When the combustion products contain salts, the design type of vertical downward or downward oblique combustion should be adopted in order to eliminate salt from the system.The incinerator body can be a cylindrical, square or rectangular container.Cyclone and spiral combustion chamber incinerators use a cylindrical design; although liquid jet furnaces, waste gas incinerators, and multi-combustion chamber incinerators can be used in both square and rectangular designs, cylindrical combustion chambers are still better. structure type.Designing a refractory top as a square or rectangle is often very difficult.The secondary combustion chambers of large incinerators are mostly vertical cylinders or cuboids, equipped with emergency exhaust chimneys, and the secondary combustion chambers of small and medium-sized incinerators are mostly horizontal cylinders. Air supply method As for the single-combustion chamber incinerator, the air supply mode of the combustion air can be divided into two types: air supply on the hearth and air supply under the hearth. Generally, 100 to 300% of excess air is added, that is, the air ratio is 2.0 to 4.0.For a two-stage gas-controlled incinerator, add 70% to 80% of the theoretical air volume in one combustion chamber, and make up the air volume to 140% to 200% of the theoretical air volume in the second combustion chamber.The secondary air is mostly sprayed from both sides to accelerate the degree of indoor air mixing and mixing.In theory, the difference between forced ventilation and suction systems is small.The advantage of the suction system is that the leakage of incineration flue gas can be avoided, but because the system often contains acid gases generated by incineration, the corrosion of the equipment needs to be considered. Determination of furnace size The size of the waste incinerator is mainly determined by two factors, the volumetric heat intensity allowed by the combustion chamber and the residence time required in the high temperature furnace when the waste is incinerated.The usual method is to determine the size of the furnace according to the allowable heat intensity of the furnace, and then check it according to the residence time necessary for waste incineration.
Considering that the waste must be burned cleanly during the incineration of the waste, and the residence time of the harmful components in the waste in the furnace must be ensured, so the volume heat intensity value is selected to be lower than that of the general fuel combustion chamber.