Low-temperature pyrolysis system and method for domestic waste based on decoupled combustion

Abstract

The invention discloses a household garbage internal circulation sealed low-temperature pyrolysis system based on decoupling combustion. A pyrolysis section comprises a drying drum and a pyrolysis drum. A scrubbing section comprises two stages of scrubber towers. A heat recovery section comprises a smoke and pyrolyzed gas waste heat recovery device. Household garbage is sent into the drying drum to be dried firstly and then sent into the pyrolysis drum to be pyrolyzed, so that pyrolysis gas and carbon residues are generated. The drying and pyrolysis process is divided into a starting stage and a normal operation stage. During the starting stage, air and gas output by a gas storage device are mixed, pass through a combustor of the drying drum and a combustor of the pyrolysis drum and burn in a cavity of the drying drum and a cavity of the pyrolysis drum correspondingly to supply heat, and accordingly high-temperature smoke is generated. During the normal operation stage, the high-temperature smoke in the cavity of the pyrolysis drum is sent into the cavity of the drying drum to be subjected to heat exchange and drying, and the combustor of the drying drum becomes an auxiliary heat source. The pyrolyzed gas sequentially enters the first stage of scrubber tower and the second stage of scrubber tower to be purified. According to the household garbage internal circulation sealed low-temperature pyrolysis system based on decoupling combustion, waste heat is sufficiently utilized to generate high-temperature steam, the smoke is exhausted after being cooled and purified, the generation of dioxin is effectively controlled, and resource recovery, reduction and low carbon of the household garbage are achieved.

Description

technical field [0001] The invention relates to the harmless treatment of household garbage and its resource recycling technology, in particular to a low-temperature pyrolysis system and method for household garbage based on decoupling combustion. Background technique [0002] Now, my country produces more than 200 million tons of municipal solid waste every year, and the annual growth rate of waste has reached more than 10%. In recent years, although some achievements have been made in the treatment of domestic waste in my country, the overall capacity is still obviously insufficient. The growth rate of waste treatment capacity obviously lags behind the growth rate of waste generation. The suburbs have occupied a large area of ​​land, and some cities are already facing the threat of "garbage siege". [0003] At present, there are three main methods of municipal solid waste treatment widely used in my country and even in the world, including landfill, incineration, and compo...

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Problems solved by technology

However, the landfill treatment method has disadvantages such as occupying a large amount of land resources, polluting leachate, and methane gas produced by fermentation intensifying the greenhouse effect.

However, the composting method has problems such as a large area, a long conversion process, difficult to stabilize the state, and difficult to control the product quality. At the same time, the waste treated by composting in my country is basically mixed waste, which has not been strictly classified, so it is inevitable in the composting process. Mixed with a large amount of toxic and harmful substances such as heavy metals, coupled with the unorganized emission of methane and other greenhouse gases, it is very easy to cause serious pollution to the surrounding environment

Among the above three methods, the incineration method is the most effective treatment method for waste reduction, which can reduce the volume of waste by 85% and the weight by more than 75%. However, incineration of waste has hidden dangers of environmental pollution, especially the dioxin produced by incineration Ying has irreversible "three-induced" toxicity, which is extremely harmful to human health, and has become the most concerned issue at present.

In addition, there are some restrictions on the incineration of waste:

[0004] (1) my country's municipal solid waste is basically mixed and collected, with complex components, and incineration generally requires the minimum calorific value of waste to be 3360kJ kg -1 As mentioned above, when the calorific value of the garbage is too low, it is necessary to add fuel to assist combustion, which will cause an increase in operating costs. At present, except for a few economically developed cities in my country, garbage sorting and collection in other cities have not been generally carried out, so mixed Domestic waste has a low calorific value and is not suitable for incineration;

[0005] (2) The investment and operating costs of incineration treatment equipment are relatively high. Most of the waste incineration power plants built in my country in the early stage imported foreign technology and equipment, and the investment cost was expensive. In recent years, with the localization of imported equipment and independent innovation of technology, domestic Technology and equipment have been developed and applied. Although the investment of incineration plant units has been reduced, the investment and operation costs of incineration treatment are still high for areas with average economic affordability.

At present, domestic waste pyrolysis treatment technology has been studied to a certain extent, such as the invention patent with the publication number CN103242134A and the name "A Method for Pyrolysis and Gasification Purification of Household Waste". Under certain conditions, oxygen is introduced to carry out combustion and cracking reactions, and the combustible gas generated by the pyrolysis of garbage is used comprehensively to synthesize chemical raw materials to realize the resource utilization of domestic waste. Complex, so this increases the difficulty of synthesizing chemical raw materials, and the disposal of garbage under high temperature and aerobic conditions, the subsequent purification process costs are high, and the exhaust emissions are also large

Another example is an invention patent with the publication number CN 102660306 A and titled "Countercurrent Rotary Household Garbage Pyrolysis Carbonization Furnace System and Garbage Treatment Process". Combustion supplements the heat source to realize the reduction and recycling of waste. However, this process does not dry and pretreat domestic waste, but uses a method of drying while pyrolyzing, which will increase the energy consumption of the system and reduce the treatment efficiency. At the same time, direct discharge of a large amount of flue gas after cooling treatment will also have a certain impact on the atmospheric environment, especially in today's society plagued by smog, the follow-up treatment of flue gas cannot be ignored

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