The cycling of energy and substance of the limestone

Abstract

The thermodynamic analysis (program system TERRA) of the synthesis and expansion of the limestone had been conducted at a pressure р = 10^-10 – 100 MPa. Expansion of the limestone СаСО₃(с) = СаО (с) + СО₂. The temperature of dissociation varies from Т_diss = 537,1 К (р = 10^-10 MPa) till Т_diss = 1155,8К (р = 0,1 MPa) and Т_diss = 2193,1 К (р = 100 MPa). At a temperature 1602-1604 К and р = 12,6–100 MPa is melted СаСО₃(с), Q_pl 320 kJ/kg. The heat of the chemical reaction equals Q_chr 1778 kJ/kg and does not depend on pressure. The energy balance: I = H + Q_chr, where I – accretion of enthalpy, H – enthalpy. Synthesis of the limestone СаО(с) + СО₂ = СаСО₃(с). An exothermic reaction takes place. The adiabatic temperature decreases with decreasing pressure Т_ad = 1603,1 К (р = 100 MPa), till Т_ad  = 1155,8К (р=0,1MPa) and Т_ad = 537,1 К (р = 10^-10MPa). The synthesis is completed at a pressure of more than 12,6 MPa and temperature Т_ad = 1603К. With the increasing pressure, the heat of chemical reaction increases reaching a maximum value Q_chr = 1778 kJ/kg at р = 12,6MPa and over. When melting there is an energy balance performed Q_chr = H + Q_ml. Synthesis of the limestone СаО(с) + СО₂(f) = СаСО₃(с), СО₂(f) – «dry ice». When using the "dry ice" for a fixed volume increases pressure by sublimation and is further burning it with lime. Adiabatic temperature, enthalpy and the heat of the chemical reaction differs insignificantly during the transition from the gas СО₂(g) to the condensed СО₂(f). The content of СаСО₃(с) in the products is increased. The heat that is released compensates the costs for sublimation. Applying the «dry ice» can eliminate the need for compressing the carbon dioxide. The successive endo- and exothermic reactions cause the cycling of energy and substance of the limestone.