A stream with variable amount of CO and CO2 reacts with air. The influence of amounts of CO, CO2 and air as well as that of temperature on soot formation is calculated. This example includes an animated figure to show ChemSheet at work.
Building on the first example, here heat transfer of a pipe to the surroundings is modelled in Excel and the heat balance is used to determine the change in reaction temperature. This example includes an animated figure to show ChemSheet at work.
An example where thermochemical calculations were not only linked to heat transfer models but also to reaction kinetics is the titanium(IV)chloride burner, known for its wide industrial use in TiO2-pigment manufacture. Expensive process trials on scale-up of the plant could substantially be reduced.
The solubility of gases in aqueous solutions can be modelled in terms of temperature and partial pressures. The temperature-dependent Pitzer-Sechenow-model applied in ChemSheet provides for the salting-out and salting-in effects of various electrolytes on the dissolved gases.
STACK GAS MODELS (impurities such as Hg, As, etc.)
The speciation of mercury (Hg) emissions in flue gases of power plants has been simulated. The data can be used to optimise conditions for trace element recovery.
pH IN PROCESS SOLUTIONS
The pH of a caustic hydrogen peroxide solution used commonly in pulp bleaching was modelled withChemSheet. The simulation takes care of the metastable acidic behaviour of hydrogen peroxide and could be used as basis of a dynamic bleaching model. The pH-behaviour of the calcite containing stock solutions for paper machine wet-end chemistry has been simulated. The multi-component model permits the investigation of the effect of solubility agents and carbon dioxide on pH and calcite precipitation.
CVD PRODUCTION OF ULTRA-PURE SILICON
The yield of ultra-pure silicon deposited by thermal decomposition from SiHCl3 gas could be maximised after thermochemical analysis.
TEMPERATURE & HEAT IN REACTIVE SYSTEMS
The heat evolved in a complex aluminothermic system comprising of fast exothermic and endothermic reactions could be calculated to enable controlled feed of a chemically inert “heat sink”. In another example, design of reactor cooling and scale-up could be done.
CHEMICAL RECOVERY CYCLES
The behaviour of soluble and insoluble molybdates, used as bleaching activators, was modelled for the recovery boiler and furthermore for the green and white liquor tanks in the recovery cycle of kraft pulping plants. The model was used to avoid expensive trial runs.