Influence of Sodium Oxide on the Fusion of Solid Municipal Waste Ash
- PDF / 655,567 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 97 Downloads / 188 Views
USTION, EXPLOSION, AND SHOCK WAVES
Influence of Sodium Oxide on the Fusion of Solid Municipal Waste Ash M. V. Tsvetkova, *, D. N. Podlesniia, V. M. Freimana, b, E. A. Salganskya, Yu. Yu. Tsvetkovaa, I. V. Zyukina, b, A. Yu. Zaichenkoa, and M. V. Salganskayaa, b aInstitute
of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia b Moscow State University, Moscow, 119991 Russia *e-mail: [email protected] Received January 9, 2020; revised January 9, 2020; accepted February 20, 2020
Abstract—The model composition of municipal solid waste (MSW) and its ash chemical composition are characterized. Mineral compounds and melting points are studied using a variety of analytical methods, including XRD, FTIR, and AFT. The main parameters of slag formation are calculated: base-to-acid ratio, slag viscosity index, and fouling coefficient. Solid municipal waste ash contains significant amounts of CaO, SiO2 and Al2O3. Using the Terra program, thermodynamic calculations of the chemical equilibria of the CaO–SiO2–Al2O3–Na2O systems containing from 5 to 25% sodium oxide are performed. It is experimentally shown that each 5 wt % increase in the Na2O content reduces the characteristic melting temperatures of MSW ash by 30–50°С. Keywords: municipal solid waste, ash fusion temperatures, slagging, mineral compounds, thermodynamic calculations DOI: 10.1134/S1990793120040260
INTRODUCTION In Russia, more than 60 million tons of municipal solid waste (MSW) are generated annually, of which only 7–8% is recycled [1]. Most of the waste is sent to landfills, which occupy vast territories of the earth, and with the self-ignition of MSW, the environment is polluted by waste gases. In addition, landfills are a source of contamination of both surface and underground water due to the drainage of landfills by precipitation. Nowadays, one of the promising methods for the thermal processing of MSW is gasification in the mode of filtration combustion [2–6]. This technology in countercurrent systems has several advantages: high level of purity of waste gases, efficient process, the possibility of using low-calorie and finely dispersed waste [7–10]. Upon gasification of MSW, a product gas is formed (a mixture of CO, H2, CO2, etc.), which, after purification, can be used to produce thermal or electric energy [11–15].
When the temperature in the reactor increases above the deformation temperature (DT) of the ash, the sintering of the charge is observed, which prevents the unloading of the ash residue. To prevent the slagging of ash, it is important to know the chemical composition and characteristic melting temperatures of the ash before starting the incineration of MSW so as not to exceed the DT, and/or apply other methods to prevent ash slagging [16]. The melting characteristics of ash are closely related to its composition, which mainly consists of eight oxides: SiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, K2O, and TiO2. As a rule, these oxides are divided into two groups: acid oxides, which increase the melting
Data Loading...
