Development of a New Waste-to-Energy System Using Plasma Gasification & Melting Technology

Liran Dor2, Qinglin Zhang1, Weihong Yang1, Wlodzimierz Blasiak1
1Energy and Furnace Technology Division, Royal Institute of Technology, Brinellvägen 23, S-10044 Stockholm, Sweden
2Environmental Energy Resources Ltd, 7 Jabotinski St., 52520 Ramat-Gan, Israel

Principal Contact: Qinglin Zhang, PhD candidate, Energy and Furnace Technology Division, Royal Institute of Technology, Brinellvägen 23, S-10044 Stockholm,
Sweden.
Phone: +46 87906545
Fax: +46 8207 681
Email: qinglin@kth.se


Abstract
Gasification is a promising waste-to-energy process. In recent years, a new gasification technology named Plasma Gasification Melting (PGM) has been developed. The idea of PGM is coupling the plasma vitrifying technology in an updraft fixed-bed gasifier. Compared to conventional gasification, PGM technology can significantly prevent the pollution by alkali and heavy metals in gasification ash, and increase the combustion value of syngas.
In this work, a waste-to energy system using PGM technology is introduced. Attentions are paid to the total energy efficiency of the system. The system includes three parts: the PGM reactor, the gas cleaning section and power generation section. In the PGM reactor section, the influence of operation parameters are studied, aiming at producing high LHV syngas, with optimal energy efficiency. In the power generation section, three different power generation methods, such as Rankine cycle, Internal Combustion Engine, and combined cycle are considered respectively. An Aspen model of the system was built, and validated by the test data of a demonstration PGM plant. Calculation was carried out to find out the optimal conditions for the waste-to-energy system. The optimal results, especially the energy efficiency results are compared with the energy efficiency of a traditional waste incineration process. Some suggestions about the arrangement of a real PGM plant are also given in this paper.


CFD Modeling of Municipal Solid Waste Gasification in a Fixed-Bed Plasma Gasification Melting Reactor
Paper #12
Qinglin Zhang1, Liran Dor2, Weihong Yang1, Wlodzimierz Blasiak1
1Energy and Furnace Technology Division, Royal Institute of Technology, Brinellvägen 23, S-10044 Stockholm, Sweden
2Environmental Energy Resources Ltd, 7 Jabotinski St., 52520 Ramat-Gan, Israel

ABSTRACT
A steady CFD model is developed to simulate the gasification of municipal solid waste (MSW) in a moving-bed Plasma Gasification Melting (PGM) reactor. In this model, the Eulerian-Eulerian multiphase model is conducted, and the solid phase is treated as a plastic fluid. The conservation equations of both gas and solid phases are solved respectively. The momentum conservation equations of the solid phase are simplified by disregarding the interphase forces between gas and solid. Both heterogeneous reactions and homogeneous reactions are defined in this model to express the detailed gasification chemistry inside the reactor. A two-step pyrolysis model was used in this work, and the pyrolysis mechanisms of cellulosic and plastic fractions are considered separately.
The predicted results of a base case are compared with the measured data of the trial reactor. The temperature distribution inside the PGM reactor is introduced. Based on the variation of temperature, the whole reaction shaft was divided into five layers. The 2D effect of the reactor is also discussed.
The influence of two dimensionless parameters: the equivalence ratio (ER) and dimensionless plasma energy ratio (DPER) are introduced and discussed. With the variation of ER, two typical temperature distributions can be found for PGM reactor. The turning point of these two distributions stands in the ER range 0.120-0.133. This turning point is the optimal operation condition of PGM air gasification. It is also found that when the energy request for gasification is satisfied, further increment of DPER value does not significantly influence the characters of PGM process.