Process for fast and homogeneously heating a liquid product and apparatus for such process

A process for fast and homogeneously heating a liquid product to a heating temperature by resistive heating, the process comprising:

• (a) providing an apparatus comprising at least two heating chambers that are arranged in series, each chamber having an inlet for liquid at one end and an outlet for liquid at the other end, wherein each heating chamber defines a flow path for liquid between its inlet and its outlet and the arrangement of the at least two heating chambers in series defines a liquid flow path through the at least two heating chambers, wherein each heating chamber is provided with a first electrode at one end and a second electrode at its other end, and the first and second electrode of each chamber are separated by an electrical insulator, and the second electrode of a preceding chamber is the first electrode of the next chamber in series, the first and second electrodes together forming a connecting electrode, wherein the electrodes are arranged such that liquid flowing through the liquid flow path through the at least two heating chambers during normal operation of the apparatus is in contact with the first and with the second electrode of each heating chamber, wherein the first electrode of the first heating chamber and the second electrode of a last heating chamber are electrically grounded, wherein each connecting electrode is electrically connected to a direct current (DC) power source to apply an electrical charge to each connecting electrode, wherein the DC power source is configured to apply electrical potential as a function of time over the electrodes by applying the electrical potential for a first time period and then reversing the polarity of the electrical potential during a second time period after the first time period between the connecting electrode and the first electrode of the preceding chamber, and between the connecting electrode and the second electrode of the next chamber, so as to repeat consecutive applications of an electrical potential with continually reversing of the polarity over time across the electrodes of each heating chamber, and in which the electrical potential is applied so as to generate an electrical current through the liquid product in each of the heating chambers between the first and second electrodes, and wherein the continual reversion of the polarity of the electrical potential of each connecting electrode is at a frequency of at least 500 Hz, with the electrical charge of adjacent connecting electrodes being opposite;
• (b) continuously supplying the liquid product to the inlet of the first heating chamber and flowing the liquid product continuously through at least two heating chambers in such a way that the liquid product is in contact with the first electrode and with the second electrode of each heating chamber;
• (c) generating an electrical current through the liquid product flowing through the heating chambers by applying an electrical potential over the first electrode and the second electrode of each heating chamber so as to provide a constant electrical field strength between a connecting electrode and a first electrode of a preceding chamber, and between a connecting electrode and a second electrode of a next chamber,
• wherein the direction of the electrical current is continually alternated with a frequency of at least 500 Hz such that the electrical potential applied over said electrodes as a function of time has the shape of a block wave, to obtain heated liquid product, wherein the electrical current is provided by a DC power source configured to apply the electrical potential for a first time period and then reverse the polarity of the electrical potential during a second time period after the first time period between the connecting electrode and the first electrode of the preceding chamber, and between the connecting electrode and the second electrode of the next chamber, so as to repeat consecutive applications of the electrical potential with continually reversion of the polarity over time across the electrodes of each heating chamber;
• and wherein the electrical field strength that is applied over each heating chamber is from 0.1 kV/cm to 20 kV/cm;
• and
• (d) continually discharging heated liquid product from the last heating chamber in series via its outlet, wherein the liquid product has an electrical conductivity of at least 0.03 S/m.