Scale-up of the carbonate looping process to a 20 MWth pilot plant based on long-term pilot tests
INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL
Authors: Hilz, Jochen; Haaf, Martin; Helbig, Martin; Lindqvist, Niklas; Stroehle, Jochen; Epple, Bernd
Abstract
An efficient post-combustion capture technology is the carbonate looping (CaL) process reducing the amount of CO2 released by fossil fuelled power and industrial plants. Limestone based sorbents are circulated between two interconnected circulating fluidized bed (CFB) reactors. In a first reactor, the carbonator, the main part of CO2 contained in the flue gas of an upstream emission source is absorbed by CaO. The CO2 is released and the sorbent regenerated under oxy-firing conditions in a second reactor, the calciner. Numerous experimental pilot tests in semi-industrial scale proved the feasibility of this technology, whereof complementary results are published in this paper. A demonstration plant constitutes the next step of developing the CaL technology. This paper presents the development of a 20MW(th) demonstration pilot considered as a milestone with regard to industrial application of the technology to answer remaining technological and economic questions. A conceptual design for this 20MW(th) demonstration pilot is presented. An existing 600MW(el) power station serves as a host unit for the boundary conditions of this demonstration pilot.
Kinetics and fusion characteristics of municipal solid waste incineration fly ash during thermal treatment
FUEL
Authors: Zhang, Sheng; Chen, Zhiliang; Lin, Xiaoqing; Wang, Fei; Yan, Jianhua
Abstract
During the thermal treatment of municipal solid waste incinerators (MSWI) fly ashes (FA), the fusion characteristics, kinetics, and phase transition are the theoretical basis on heavy metals solidification improvement and energy consumption reduction. In this study, the thermal behavior of MSWI FA from two typical furnaces in China, i.e., grate furnaces (GF) and circulating fluidized bed (CFB), are systematically investigated. The results show that FA melting can be divided into five stages but with different positions and areas of weightlessness peaks between two types of FA. We identify four kinetic models from which to obtain the apparent activation energy and pre-exponential factor during the melting transition. The apparent activation energy of GF FA ranges from 466 to 1016.2 kJ/mol, which is generally higher than that of CFB FA (380.1-636.6 kJ/mol). The weightlessness rate of GF FA is approximately three times that of CFB FA because of its high chloride load. Silicon dioxide (SiO2) in FA is prone to react with other compounds to form low-melting-temperature minerals at 1100 degrees C, such as Ca-2 MgSiO2O7. Therefore, the fusion temperatures of CFB FA with a higher content of SiO2 are about 150 degrees C lower than that of GF FA, which is consistent with the theory that the fusion temperature of FA is at its lowest when the ratio of basic to acid oxides approaches 1. Finally, SiO2-CaO-Al-2O(3) ternary phase diagrams, ash fusion temperatures, and several fouling and slagging indices are verified to predict the ash fusion characteristics of MSWI FA.