The main principle of domestic waste incineration power generation is to use domestic waste as fuel, put it into the boiler for combustion, and input the superheated steam generated by it into the steam turbine to realize the process of converting heat energy into electric energy. The entire technological process is mainly composed of waste receiving and conveying system, waste incinerator system, waste heat recovery system, turbo generator and thermal system, flue gas purification system, ash treatment system, landfill leachate treatment system, etc. This time, we will introduce the waste incineration power generation process in this order.
Front-end reception – garbage receiving and conveying system
The garbage truck enters the factory through the logistics gate of the factory area. After being weighed by the floor scale, the vehicle drives into the garbage unloading hall according to the instructions, and dumps the garbage into the garbage storage pit. After the car passes through the rear bucket, several tons to more than 20 tons of garbage are unloaded into the garbage storage pit. According to the requirements, the garbage in the garbage storage pit will stay for 7-10 days. After fermentation and dehydration, the calorific value is significantly improved, which can meet the requirements Furnace incineration requirements.
During the process of waste incineration for power generation, the escape of odorous gas has a certain impact on the surrounding environment and the health of operators. Therefore, deodorization in the process of waste incineration for power generation is a problem that plagues operators. Usually, the staff will install a primary fan on the upper part of the garbage storage pit, and the air in the garbage storage pit will be drawn to the incinerator by the primary fan, so that the odor will also enter the furnace and be incinerated, and converted into odorless gas to control odor and methane gas accumulation. In addition, by means of pumping air and other means, the garbage storage pit is kept at negative pressure to prevent the odor in the pit from overflowing.
At present, the reciprocating grate furnace waste incineration technology is basically adopted at home and abroad. The garbage grab lifts the waste in the warehouse to the feeding hopper, and continuously feeds the waste to the grate inlet through the feeding chute. Under the action of the pusher, the garbage first enters the drying area of ​​the grate furnace, and through the action of the grate, the garbage moves forward on the grate to the burning area, and finally reaches the burning area, ensuring that the garbage is kept at a high temperature of 850°C~1100°C Get fully burned.
The upper part of the incinerator is the boiler. The temperature of the flue gas from the incinerator is about 850 ° C. First, part of the heat is absorbed by the water-cooled wall tube of the first channel on the upper part of the incinerator, and then the flue gas continues to wash the screen-type heating surface and superheater. Most of the heat in the flue gas is absorbed here, and finally the remaining heat is absorbed when passing through the economizer, and the tail gas is discharged to the flue gas purification system.
Back-end processing – environmental protection system
Flue gas purification system
The flue gas purification system mainly consists of: furnace denitrification system, semi-dry comprehensive reaction tower, activated carbon adsorption system, bag filter system, flue gas discharge system, flue gas online monitoring system and fly ash conveying system.
The denitrification system in the furnace mostly adopts the process of selective non-catalytic reduction (SNCR). In this process, 20% ammonia solution is sprayed into the area where the furnace temperature is 850-1000 ° C. As the reducing agent of the SNCR process, ammonia water is rapidly thermally decomposed into NH3 and Other by-products, NH3 then undergoes a reduction reaction with NOx in the flue gas to generate N2.
The temperature of the flue gas at the boiler outlet is about 220°C. The flue gas is introduced into the comprehensive reaction tower from the top, and enters the reaction tower from the lower part of the comprehensive reaction tower to form an upward airflow, which fully contacts with the slaked lime powder sprayed from the slaked lime system on the top of the tower, and reacts to form a powder Calcium salt, to achieve the purpose of cooling down and removing heavy acid gas from flue gas. In order to better remove dioxins, heavy metals and other substances, activated carbon is sprayed into the flue gas pipe at the outlet of the comprehensive reaction tower.
The particles carried in the flue gas are blocked by the filter cloth of the bag filter to form a filter layer. When the flue gas passes through the filter layer formed by particles, the gaseous pollutants can still react with the unreacted lime and activated carbon in the filter layer to obtain Purify further. The treated flue gas is led by the induced draft fan to the chimney for discharge, and the chimney is equipped with an online flue gas monitoring system.
In addition, the incinerator also adopts controlled combustion to reduce the generation of dioxins. The specific measures are: control the temperature of the incinerator to incinerate waste at 1050 ° C; control the residence time of the flue gas in the high temperature area above 850 ° C for no less than 2 seconds; Measures such as wall tube absorption minimize the residence time of flue gas from high temperature to low temperature (400-200°C).

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