Correlation Between the Operation Parameters and the Products of Incomplete Combustion in a Laboratory Scale Spouted Bed Incinerator

• Main Authors: Lai Yung Feng, 賴永
• Other Authors: Lin Chieh
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/31281358121951603278

碩士 === 國立屏東科技大學 === 環境工程與科學系 === 88 === Incineration is recognized as one of the most efficient processes to treat and dispose the waste stream. An obvious advantage of incineration is the large mass and volume reduction. The oxidation of hydrocarbon contents in the waste stream is a very complex process involving both propagation and chain-branching reactions. The major concern regarding air pollutant emissions from hazardous waste incineration system is to form some organic products of incomplete combustion (PICs). Some of them are thermally stable and suspected of being mutagenic and carcinogenic to human. The performance of incinerator was normally evaluated in terms of combustion efficiency (CE) and destruction and removal efficiency (DRE). However, some PICs formation can not associate with the quantitative values of CE and DRE. The objective of this research is to investigate the key operating parameters related to the formation and destruction of PICs. These parameters will include the bed height, the circulation reflux, the nature of auxiliary fuel, the votex secondary air flow, and the addition of the inorganic chlorine sources. A laboratory scale spouted bed combustion system is employed to simulate the hazardous waste incineration process. Toluene was chosen as a typical aromatic fuel structure for baseline combustion. Potassium chloride (KCl) is added into the system for incineration to represent the inorganic chlorine source. Samples, dust and temperature measurement can be taken from the side arms in the combustor at the different axial positions. Analyses for DRE and PICs are performed on gas chromatographs equipped with flame ionization detector and mass spectrum detector (GC/FID & GC/MSD). The on-line measurements were conducted under the bed surface and include DRE of fuel, and concentrations of two PICs of toluene; benzene and benzaldehyde. The off-line samples could be withdrawn simultaneously from the different post combustion locations in the same experimental run to observe the formation and destruction of the index PICs. The primary compounds under investigation are benzene, toluene, ethylbenzene, xylene (BTEX), benzaldehyde, phenol, chlorobenzene (CBs), chlorophenol (CPs), and polycyclic aromatics hydrocarbons (PAHs). The exhaust flus gas composition are taken periodically and monitoring via a portable basic smoke gas analyzer. The correlation between the combustion indicates and the PICs is the thrust of this study. The primary results of this study are summarized as follows: (1) The heat transfer and the heat capacity within the spouted bed were increased by increasing the particle circulation rate under the elevated bed temperatures. (2) The results of the on line analyses show that the maximum value of DRE in the bed region occurred in the spout-annulus interface. (3) Based on the results of two reproducible experiments, styrene shows more consistent concentration than other compounds of PICs between two runs. This compound could be chosen as the indices to represent the performance of incineration. (4) The oxygenated species concentration of PICs increases with adding the auxiliary votex air flow near inlet port. (5) The concentration of most PICs increases with adding the KCl powder in the post-combustion regime. The result does not detect the PICs of chlorobenzene (CBs), chlorophenol (CPs).