Fluidized bed combustion of pesticide-manufacture liquid wastes

Abstract

Industrial liquid wastes can be in the form of solutions, suspensions, sludges, scums or waste oil and have organic properties. The objective of this work was to demonstrate the technical feasibility of a fluidized bed as a clean technology for burning liquid waste from a pesticide production plant. The combustion of liquid waste mixtures, obtained from realistic samples, was investigated in a pilot scale fluidized bed with quartz sand particles of 0.63-1.25 mm in diameter and 2610 kg/m3 in density at 800-950°C. To ensure complete combustion of liquid waste and additional fuel, the combustion chamber was supplied with excess air and the U/UmF (at ambient temperature) was in between 1.1 and 2.3. In the fluidized bed chamber, liquid waste, additional liquid fuel and air can be brought into intense contact sufficient to permit combustion in bed without backfire problems. The experimental results show that the fluidized bed furnace offers excellent thermal uniformity and temperature control. The results of the combustion tests showed that degradation of liquid wastes can be successfully realized in a fluidized bed with no harmful gaseous emissions by ensuring that the temperatures of both the bed and the freeboard are not lower than 900°C.

Industrijski tečni otpad može biti u obliku rastvora, suspenzija, mulja, pene, otpadnog ulja i generalno sadrži različite organske komponente. Predmet ovog rada je demonstracija tretmana tečnog otpada sa visokim sadržajem zagađujućih materija fabrike za proizvodnju pesticida metodom termičke destrukcije u fluidizovanom sloju peska kao tehnički praktične i optimalne tehnologije. Ispitivanja sagorevanja realnih tečnih otpadnih smeša fabrike pesticida su izvršena u poluindustrijskom-demonstracionom postrojenju, tj. u fluidizacionoj koloni sa slojem kvarcnog peska granulacije 0,63-1,25 mm i gustine 2610 kg/m3 na 800-950°C. U cilju obezbeđenja potpunog sagorevanja tečnog otpada, u fluidizacionu kolonu je uvođen vazduh u višku i odnos U/UmF (na temperaturi okoline) je iznosio između 1,1 i 2,3. U fluidizacionoj koloni se tečni otpad, dodatno tečno gorivo i vazduh mogu dovesti u stanje intenzivnog kontakta što omogućava stabilno i homogeno sagorevanje u sloju. Rezultati eksperimentalnih ispitivanja pokazuju da se u fluidizovanom sloju peska ostvaruje veoma dobra termička uniformnost i kontrola temperatura. Rezultati ispitivanja sagorevanja su pokazali da se tečni otpad sa visokim sadržajem zagađujućih materija može uspešno termički tretirati u fluidizovanom sloju peska bez emisije štetnih produkata sagorevanja, pod uslovom da su u sloju i iznad sloja obezbeđene temperature iznad 900°C.