Molten Slag Waste Processing Prevents Dioxins
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Solution Overview
Problem
Current methods for processing solid municipal wastes face inefficiencies, including low incineration temperatures, incomplete combustion, formation of harmful substances like dioxins and furans, and unsuitable ash disposal, leading to environmental and economic challenges.
Innovation Solution
A method and unit for waste-free thermal processing that involves charging solid municipal wastes into a melting chamber with a superheated slag bath, optimizing oxygen flow, flux addition, and nitrogen drying to achieve higher temperatures and prevent dioxins and furans formation, while ensuring continuous and efficient slag management and gas handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If solid municipal wastes are incinerated at low temperatures (850°C to 1,150°C) using air oxidation, then the process is simpler to operate, but complete combustion cannot be achieved and harmful substances including dioxins and furans are formed
Solution Approach 1:
The invention changes the temperature parameter from low (850-1150°C) to high (1400-1500°C) and changes the oxidizing atmosphere from air to oxygen-containing gas, which enables complete combustion and eliminates dioxins and furans formation while maintaining operational feasibility
Solution Approach 2:
The invention uses oxygen-containing gas instead of air as the oxidizing medium, providing stronger oxidation capability that enables complete combustion at high temperatures and prevents the formation of harmful substances like dioxins and furans
2Object-affected harmful factors
If incineration temperature is raised to 1400°C to 1500°C for complete combustion, then harmful substances are eliminated, but the process becomes more complex due to low calorific value of damp wastes and large quantities of incombustible elements
Solution Approach 1:
The invention raises the temperature parameter to 1400-1500°C and changes the oxidizing atmosphere to oxygen-containing gas, which enables complete combustion of wastes with low calorific value and high incombustible content, simplifying the overall process by achieving waste-free processing
3Quantity of substance
If waste grading is performed to remove packaging cardboard, paper, glass, plastics, and scrap metal, then the weight of wastes to be processed is reduced, but the operation becomes costly and laborious
Solution Approach 1:
The invention extracts and removes incombustible elements such as glass, bones, metal, and construction debris directly from the incineration process stream, eliminating the need for costly and laborious pre-processing grading operations while maintaining efficient waste-free processing
Solution Approach 2:
The incineration system itself performs the function of separating and removing incombustible elements through the high-temperature oxygen-containing gas environment, making the process self-sufficient and eliminating the need for separate grading operations
4Productivity
If incombustible elements such as glass, bones, metal, and construction debris are present in large quantities, then the efficiency of incineration is reduced, but complete removal through grading is costly and laborious
Solution Approach 1:
The invention changes the temperature to 1400-1500°C and uses oxygen-containing gas, which enables efficient incineration even in the presence of large quantities of incombustible elements, achieving high productivity without costly grading operations
Solution Approach 2:
The system extracts and removes incombustible elements during the high-temperature oxygen-containing gas incineration process, maintaining high incineration efficiency without requiring expensive pre-grading operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the technical and economic efficiency of waste processing, prevents dioxins and furans formation, ensures complete combustion, and facilitates environmentally friendly disposal by maintaining high temperatures and optimizing slag composition and gas handling.
Implementation Method 1
a melting chamber (3) with a housing (5) cooled by a liquid metal coolant
Implementation Method 2
oxygen is blown by combined burner-tuyeres (4) into the working space of the melting chamber (3) to oxidize the organic components of the solid municipal wastes
Implementation Method 3
The organic components of the solid municipal wastes are oxidized rapidly in the oxygen atmosphere releasing a large amount of heat
Implementation Method 4
the mineral components of the solid municipal wastes melt and sink into the slag, the slag temperature rises to between 1500°C and 1650°C
Implementation Method 5
damp solid municipal wastes are dried in a rotating furnace (1) with gaseous nitrogen heated to between 200°C and 300°C by the heat given off by the liquid metal coolant
Implementation Method 6
gaseous nitrogen heated to between 200°C and 300°C by the heat given off by the liquid metal coolant in the secondary cooling system of the melting chamber (3)
Implementation Method 7
an airtight mechanism (2) for charging the dried wastes into the melting chamber (3) at a preset rate within the temperature range of 180°C to 600°C
Implementation Method 8
oxygen is blown by combined burner-tuyeres (4) into the working space of the melting chamber (3) at a rate of 250 to 390 nm 3
Implementation Method 9
combined burner-tuyeres (4) operated as oxygen tuyeres
Data Source
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AI summary
The method for the pollution-free thermal processing of solid municipal waste comprises drying the above-mentioned waste before feeding the waste into a smelting furnace with gaseous nitrogen which is heated to 200-300°C by the heat accumulated by a liquid-metal heat carrier during the cooling of the body of a smelting chamber, loading said waste at a controllable speed into the smelting chamber, and burning organic constituents in an oxygen atmosphere on a surface of molten slag produced in the smelting chamber from mineral constituents of the waste and from added fusing agents. The gases formed are transferred along a cooling pipe to a high-energy boiler where said gases are completely combusted and the heat from the gases being produced is utilized. The rate of continuous discharge of slag surplus from the chamber is maintained at a level ensuring the presence of a constant quantity of slag in the chamber. An apparatus for realizing the described method is described. The technical result involves preventing the formation of dioxins and furans by maintaining a rational ratio of the mass of waste being loaded in a unit of time to the mass of molten slag located in the smelting chamber, and increasing the degree of use of the heat removed by the nitrogen from the metal heat carrier in a system of secondary cooling of the smelting chamber.