# Partition of Cu and Pb in a Two-Stage Fluidized-Bed Waste Gasification System
## 1 Introduction  
Taiwan produces about 750 million metric tons of municipal solid waste (MSW) every year. The two predominant methods for MSW treatment are recycling and incineration. At present, there are 24 large incineration plants treating over 600 million tons of waste every year in Taiwan. In order to reduce the influence of MSW incineration, the government has been actively seeking treatment methods other than just recycling resources from waste and incineration. Since most of the waste is organic matter, if the incineration treatment could be transferred to a gasification treatment of waste, not only can the pollution from traditional incineration plants be solved, but we can also obtain reusable energy from the process. The mixture of gases obtained after gasification is called synthesis gas (syngas), and it contains mainly CO, CH\({}_{4}\), H\({}_{2}\), and other gases [1]. Syngas can be further purified and directly burned or used as raw chemical materials; thus, this technology is a promising alternative to incineration [2]. According to the literature, the parameters affecting the composition of the final syngas from the gasification process include the feed species, temperature, catalyst, feed diameter, bed material diameter, Equivalence ratio (ER), and Steam/Biomass ratio (S/B) [3; 4; 5; 6]. The ER is defined as the ratio of the actual amount of oxygen supplied to the gasifier to the amount of oxygen required for complete combustion of a given quantity of biomass. The S/B is the ratio of the amount of steam to the amount of biomass feed in the gasifier, and it is also an important parameter affecting gasification. Of thesefactors, the gasification temperature, ER, and S/B have the greatest influence on the gasification process. The gasification temperature directly affects the gasification reactions. [PERSON] et al. [7] pointed out that increasing the operating temperature could increase the yield of H\({}_{2}\) and CO by promoting some reactions, such as methane-steam reforming, water-gas reactions, and the Boudouard reaction. [PERSON] et al. [3] increased the gasification temperature from 650 to 850 \({}^{\circ}\)C, and the results showed that the carbon conversion efficiency (82%) and energy conversion efficiency (96%) were higher at 850 \({}^{\circ}\)C than at 650 \({}^{\circ}\)C. Furthermore, H\({}_{2}\) concentrations increased from 4% at 650 \({}^{\circ}\)C to 15% at 850 \({}^{\circ}\)C. [PERSON] et al. [8] also pointed out in their studies that increasing the gasification temperature could increase both the gas production rate and carbon conversion efficiency. [PERSON] et al. [9] and [PERSON] et al. [10] also indicated in their studies that an increase in gasification temperature resulted in increased H\({}_{2}\) content in the syngas. An increase in the ER value suggests that more oxygen has entered the gasifier, causing more carbon to be oxidized and the carbon conversion efficiency to increase. This results in more CO\({}_{2}\) in the produced syngas while decreasing the concentrations of CO and H\({}_{2}\)[11]. The same results were obtained when the ER value was increased in experiments conducted by [PERSON] et al. [12] and [PERSON] and [PERSON] [13]. However, having too high of an ER value means that excess oxygen is provided, so the reaction tends to be complete oxidization, reducing the gross heat value of the syngas [14]. If the results of previous studies are taken as a whole, then controlling the ER value of gasification within the range of 0.2-0.4 is the most appropriate approach [4]. The S/B is the ratio between the steam feed rate and biomass material feed rate in the gasifier and is also an important parameter affecting gasification. [PERSON] et al. [15] pointed out that when S/B was increased to 1.23, the H\({}_{2}\) percentage in the syngas and the total syngas production both increased, whereas the tar production decreased. [PERSON] et al. [16], [PERSON] et al. [17], and [PERSON] et al.