Using chemical data to estimate resultant slurry properties after the adiabatic mixing of ice, salt and water, or mixtures therof

Ice pigging is a novel technique used to remove pipe fouling in a range of industries. Pumping ice slurries made from NaCl-water solutions through pipe-work and process equipment removes sediment by providing shear at the pipe walls and can aid product recovery or act as a pre clean-in-place procedure. Altering properties such as solids fraction, temperature and ice particle size of the slurries used by adding ice, water or salt is a potentially crucial practice for optimising the process efficiency. Slurry temperature is governed by the salt concentration of the liquid phase as determined by the liquidus on the phase diagram of the NaCl+H2O system. As elements are added, ice melts or freezes, diluting or concentrating the surrounding solution. Assuming adiabatic mixing and disregarding the heat of dilution, the resulting temperature depends on the starting enthalpy, and the specific heat capacities (cp) of the constituent parts, which are functions of temperature and salt content. Using published curves for the NaCl+H2O liquidus and the specific heat capacities of ice and brine, an enthalpy balance is solved for the resultant mixture concentration under adiabatic conditions using a Newton-Raphson method. The subsequent equations are then used to build a model that predicts mixture properties with known input properties. Experiments are subsequently undertaken where various slurries mixtures are assembled whilst their temperature and salt content are monitored. Approximating the heat gained from the environment, experimental results are compared to those of the numerical model.