Mirosław Grabowski

Minimum energy consumption in sugar production by cooling crystallisation of concentrated raw juice

Abstract The sugar manufacturing process based on cooling crystallisation of concentrated raw juice is considered. Micro-filtration and softening of raw juice makes it possible to obtain white sugar by three-or four-stage cooling crystallisation. Prior to crystallisation, raw juice should be concentrated by multistage evaporation in a pressure range below the atmospheric pressure. The preferred evaporator arrangement is backward feed. As the temperature of vapours and condensates leaving the evaporator station is low, the opportunities for heat recovery are limited. In order to save energy, vapour recompression can be applied. For a given evaporator structure, the energy consumption depends on the parameters of the evaporation process. The minimum energy consumption of the novel process should thus be determined by simultaneously carrying out energy targeting and optimisation of evaporation. It is assumed that the consumption of utilities in the sugar factory is balanced with the supply of heat and power from the factory’s own power plant. Energy systems employing various CHP technologies and various evaporator stations optionally combined with vapour compressors are studied. A range of feasible solutions is defined in terms of minimum energy consumption and combined heat transfer area of the evaporator station and the heat exchanger network.

Photographic Technique Application to the Determination of Void Fraction in Two-Phase Flow Boiling in Mini Channels

The study deals with experimental investigations into heat transfer flow boiling in rectangular, vertical and horizontal mini-channels. The dedicated measurement system was designed to observe flow boiling in the mini-channel. The main task of the system is to record images of two-phase flow with a high-speed video camera, which is equipped with the synchronous movement system. The data, in the form of the footage of two-phase flow structures, were subjected to the analysis with the scripts, developed for that purpose in the MathWorks Matlab 2010b environment. The scripts allowed the determination of void fraction for each pattern of two-phase flow structures observed, at various heat fluxes and various volume fluxes, for two spatial orientations of the mini-channel: vertical and horizontal.

Applications of Process Integration Methodologies in Beet Sugar Plants

Abstract: This chapter discusses the applications of Process Integration methods to the design of energy systems, and water and wastewater systems, of beet sugar plants. Characteristic features of conventional sugar plants based on purification of raw beet juice and evaporating crystallisation are reviewed, the design of plant retrofit aimed at improvements in energy and water use is discussed, and case studies are presented. A concept of the sugar production process based on cooling crystallisation of raw beet juice is then outlined, and the design of an energy system and a water and wastewater system for a conceptual beet sugar plant employing the new process is discussed.

Experimental Data Acquisition System for Flow Boiling in Mini Channels

The study discusses experiments on ethanol flow boiling in mini-channels. Pre-set thermal and flow parameters (pressure and temperature at the inlet, mass flux, the heat flux delivered to the heater) and temperature, pressure and void fraction measurements obtained in the experiment provided data for further simulation computations. On the basis of high-speed camera images, void fraction in the mini-channel was determined. Thermograms of the heater surface and the surface in the adiabatic part of the mini-channel allowed producing temperature profiles along the channel length. The read and computed parameters satisfy the expected dependences (especially that for void fraction as a function of volume flux and heat flux). Those were used to solve inverse heat conduction problems.