Simulation assumptions. The general characteristics (completion, rock properties, etc.) applied in the WellboreKIT simulations are given in Table 2 to Table 4. Table 10 below provides the other characteristics, especially the boundary conditions of the modelling, specific to L8 and L10a. Since WellboreKIT assumes a constant flow rate over a given period of time, the average injection rate during logging is taken. The temperature profile in the well at the beginning of the logging was calculated using the average injection flow since the beginning of the drilling (89.8 days for L8 and 144.8 days for L10a). This has the effect to overestimate the cooling of the newly drilled parts of the well. WellboreKIT developments are on-going to remove these current limitations. Table 10: Characteristics of the L8 and L10a logging operations used in the WellboreKIT simulation. Injection period assumed in simulation 4.8 hours 4.8 hours The SFT was inverted stepwise (see Eq. 3) by specifying individual depth intervals, selected due to the variation of the input data and the prior knowledge:
Simulation assumptions. The following general assumptions were made during the simulation experiment:
1. In order to mitigate the effect of network delay, the simulation experiment was conducted on a single stand alone computer, therefore, it is assumed that network delay is zero.
2. The providers of the P-SLA approach lack information about a specific consumerís business need and only delivered its service based on general knowledge of the market. This is realistic because the provider normally does not consult each consumer in packaging its service and so would not know their individual needs.
Simulation assumptions. The cement kiln simulation has been performed by exploiting a combination of basic 0D modules, gas/solid streams and a set of operating parameters assumed as input variables. Main assumptions are reported in Table 3.1, which gathers the most important inputs derived from the reference mass and energy balance provided by VDZ. In particular, gas/solid mass flow rates and key temperatures have been maintained equal to the values reported in the reference VDZ plant. Raw Meal/Fuel/Air inlet temperature, °C 60/60/15 Fuel composition (% wt.) and heating value 69% C, 4% H, 0.5%S, 0.48%N, 9%O, 16.5%Ash, 0.5%H2O, 0.02% Cl; LHV= 27 MJ/kg Raw Meal composition (% wt.) 79.3% CaCO3, 13.8% SiO2, 3.3% Al2O3, 2.0% Fe2O3, 1.5% MgCO3 Number of stages 5 Cyclones efficiency (1st - 5th stage)*, % 95.2/86.01/85.97/85.74/75.6 Heat loss, kJ/kgclk 19 Fuel Consumption, kg/kgclk 0.072 Calcination efficiency, % 94.2 Transport air + primary air flow rate, kg/kgclk 0.022 Tertiary air temperature (cooler outlet / calciner inlet), °C 1137/1049.8 Tertiary air mass flow rate (kg/kgclk) 0.8 Heat loss, kJ/kgclk 95.6 Fuel consumption, kg/kgclk 0.045 Gas outlet temperature, °C 1078.5 Transport air + primary air flow rate, kg/kgclk 0.098 Secondary air temperature, °C 1137 Secondary air mass flow rate (kg/kgclk) 0.3 Free CaO in clinker, %wt. 0.76 Heat loss, kJ/kgclk 180 Clinker final temperature, °C 114.9 Exhausts temperature, °C 284.9 Heat loss, kJ/kgclk 11.1 It has to be remarked that some simplifying assumptions have been made with respect to the reference VDZ simulation, that does not affect significantly the quality of the final result. In particular: gas-solid contactors are assumed to be ideal mixers: in each preheating stage, gas and solid streams reach the equilibrium temperature at the riser outlet. Considering the temperature differences of few degrees between the solids and the gases, this assumption has a limited effect on the temperature profile along the preheating tower. Some chemical species present in low amount in the solids population are not considered when calculating the mass and energy balances. The species ignored are some intermediate calcium aluminates and calcium ferrites (CaO*Al2O3 and 2CaO*Fe2O3) that are formed in the calciner and then remain as minor clinker constituents. In addition, all sodium, potassium and chlorine compounds are also left out from the simulation. The mass flow rate of SiO2 fed to the cement plant is tuned to match the concentration ratio C...
