The organizers of WieTec offer a national integrated service platform for the transformation of scientific and technological achievements in the ecological environment industry. The platform brings together cutting-edge environmental technologies of scientific research institutes in the industry, covering environmental technology areas such as wastewater, sludge, solid waste, exhaust gas, and comprehensive environmental management. The introduction of the “13th Five-Year Plan” pointed out that the treatment of the air, sewage, and sludge are the three main directions for domestic environmental protection treatment in the future, and the goals, tasks and layout of sludge treatment were clarified. The sludge drying incineration heat treatment technology, as the fastest and most complete final disposal technology for sludge reduction, stabilization, and harmlessness, has developed into one of the mainstream mature technologies abroad. This issue of WieTec technology recommendation introduces the flash sludge drying coupled with pyrolysis and gasification technology. This technology is a set of closed-loop sludge treatment and processing technology that uses flash dryers and fluidized bed biomass pyrolysis and gasification.
1.Transportation and storage
The sludge with a water content of 60% -80% in the sewage treatment plant is unloaded into the wet sludge storage system by a sludge transporter, and then transported to the sludge transfer warehouse by a pump or a belt.
The sludge in the sludge transfer bin is quantitatively transported by a screw conveyor to the wet sludge in a dual-flow flash dryer. After the wet sludge is fluidized in the dryer by high-speed airflow, it is carried out by hot flue gas from a hot blast stove. Drying, the moisture content of sludge can be dried from 80% to 30% -40%. The fluidized and dried sludge enters the cyclone separator and bag filter to remove the dust with the gas to achieve sludge gas separation.
- Pyrolysis and gasification
The granular dry sludge collected by the dust collector is then transported to the gasifier and the biomass fuel is pyrolyzed and gasified in the gasifier under anoxic conditions. With the help of part of the air (or oxygen), the sludge and Biomass synergistically undergoes pyrolysis, oxidation, reduction, and reforming reactions. The tars associated with pyrolysis are further thermally cracked or catalytically cracked into small molecule hydrocarbons to obtain combustible gases containing CO, H?, and CH?. The combustible gas produced by the gasifier enters the hot blast stove as the hot blast stove gas for combustion.
The combustible gas is completely burned in a hot blast stove. The high-temperature hot flue gas (temperature: 800-1000 ° C) is cooled by heat exchange and passed into a flash dryer to dry the sludge. The air from the heat exchanger is used as combustion air enters the hot blast stove, which further improves the efficiency of heat energy utilization.
- Exhaust gas treatment
After the flue gas and sludge are separated, the waste heat is recovered through a heat exchanger for air distribution or whitening in the drying system, and then enters the washing tower for secondary dust removal and cooling, and is sent to the biological deodorization system for deodorization treatment into the atmosphere.
- Ash treatment
The waste slag after the pyrolysis and gasification of the gasifier is cooled to below 150 ° C by a cooling screw, and then pumped into the ash slag bin through a bin pump. The ash slag can be used for soil improvement and construction of raw materials.
The sludge flash-drying coupled pyrolysis and gasification technology has outstanding advantages such as high thermal efficiency, large degree of reduction, resource recycling, energy conservation and environmental protection, and wide applicability. Its main characteristics are reflected in the following aspects:
- The pioneering combination of cyclone flash drying technology and fluidized bed gasification combustion technology that forms a closed cycle system.
- Innovatively developed fluidized bed gasification technology for sludge and biomass, combined with a cyclone furnace for secondary combustion of gas, and fully released sludge and biomass thermal energy.
- Innovatively developed sludge air fluidization device based on cyclone drying? achieves fluidization and atomization of high-moisture sludge, thus forming a sludge flash drying technology that can be used at both high and low temperatures.
Sources of technology: “National Eco-Environmental Science and Technology Achievement Comprehensive Service Platform” and “Advanced and Applicable Technologies for Pilot-free Cities”.
The National Eco-Environmental Science and Technology Achievement Transformation Comprehensive Service Platform (hereinafter referred to as the “Platform”) is organized and guided by the Ministry of Ecology and Environment with the aim of? fighting pollution and strengthening the construction of ecological environment technical service systems.
At present, the platform brings together more than 4,000 environmental management technology and management achievements organized by the Ministry of Ecology and Environment in the past ten years, including more than 2,500 national major scientific and technological achievements in “water pollution prevention and control and treatment” and 1,000 achievements in environmental protection public welfare projects.