PL189243B1 - Method of obtaining a fuel from composts made on the basis of dewatered sludges from sewage treatment plants - Google Patents

Abstract

The method of obtaining fuel from composts, produced on the basis of dehydrated sewerage sediments from a sewerage-treatment plant, consists in carrying out the processes of fragmentation, drying in the atmosphere of hot air and waste gases, followed by consolidation. Unique characteristics: Fragmented compost is subjected to vibration and shifted by vibration on a shaker conveyor during the drying process. Once dried to the hydration level of 30 percent, 40 percent by mass of the compost is subjected to consolidation. Then, the compost is mixed with at least 60 percent by mass of fine coal. The mixture is formed into heaps and moulded in the form of briquettes with permanent shape.

Description

The subject of the invention is a method of obtaining fuel from composts produced on the basis of dewatered sewage sludge from a sewage treatment plant.

The Polish patent application No. 314 758 discloses a method of processing dehydrated sewage sludge into compost easily absorbed by plants. According to this known method, the bedding sludge is mixed with an organic carbon carrier and the obtained mixture is poured into heaps around the aeration and suction installation, respectively on the layer of previously composted raw material, and the stacked heaps are subjected to anaerobic fermentation, after which, while controlling the temperature, they are aerated by suction alternately with blowing fresh air. The compost obtained from the neutralization and utilization of sewage sludge in wastewater treatment plants has been widely used in agriculture, forestry and reclamation of degraded land as a material improving the soil structure and sources of nutrients for plants. Considerable amounts of compost produced from sewage sludge, limiting the conditions of its storage, created unexpected possibilities for the development of its incineration techniques.

There are known methods of producing solid fuel from compacted combustible materials with a structure that differs significantly from composts produced on the basis of dewatered sewage sludge from sewage treatment plants, in which grinding, drying in hot air and flue gas atmosphere and thickening are used. In these known methods of fuel production, the comminuted semi-finished products are concentrated by known methods before drying and adding appropriate reagents, and after the product is thickened, the reduction or removal of moisture is carried out by drying in a rotary drying device, in the form of a cylinder with an internal helical structure moving and shifting the material into it. inside. The heat was obtained from the exhaust gases from the external combustion installation. Technologies of known methods limited the possibilities of their direct use in the production of fuels from composts based on sewage sludge.

According to the invention, the shredded compost is vibrated and moved by a vibrating movement in a vibrating conveyor during drying, and after drying to 30% hydration, the compost in an amount of up to 40% by weight is subjected to compacting and mixed with coal dust in a minimum amount of 60% by weight, and then placed into prisms or into compacts with a permanent shape in the form of briquettes.

The method according to the invention enables ecological management, especially the conversion of an excessive amount of compost based on sewage sludge from sewage treatment plants into a valuable energy product for use in municipal boiler houses with fixed or movable grates, which was previously impossible to implement. The produced fuel allows for the economic use of slag and dust from the boiler room and also reduces it

189 243 costs of consumption of coal used in boiler houses. Effective drying of the fragmented compost particles reduces the content of harmful factors in the exhaust gas.

Example. To obtain fuel from compost produced on the basis of dewatered sewage sludge from wastewater treatment plants, compost obtained according to the technology described in the description of the invention No. 314 758 is used. The compost mass is crushed in known grinding devices. The shredded compost is then transferred to a vibrating conveyor of known design placed in a drying chamber and subjected to vibrations. The heat of drying is the hot air and exhaust gases from the coal-fired boiler installation of the plant's boiler room. The vibrated compost in the atmosphere of hot air and exhaust gases moves with a vibrating movement in a vibrating conveyor. After drying to 30% hydration, the compost in the amount of 40% by weight is subjected to compacting and mixed in known drum mixers with pulverized coal in the amount of 60% by weight, and then stacked or formed into pellets in the form of permanently shaped briquettes in known devices. The obtained fuel is a valuable commercial product with high energy values for use in municipal boiler houses with fixed or movable grates.

189 243

Publishing Department of the UP RP. Circulation of 50 copies

Price PLN 2.00.

Claims (1)

Patent claim A method of obtaining fuel from composts produced on the basis of dewatered sewage sludge from a wastewater treatment plant, using the processes of comminution, drying in hot air and flue gas atmosphere and compaction, characterized by the fact that the fragmented compost is subjected to vibrations and shifted by vibrating movements in a vibrating conveyor during drying After drying to 30% hydration, the compost in an amount of 40% by weight is subjected to compacting and mixed with a minimum amount of coal dust from 60% by weight, and then piled or formed into compacts in the form of permanently shaped briquettes.