A method for formation of granules from a liquid product, comprising: - applying a granulator according to any one of claims 5 to 8, - forming a fluidisation zone in a fluidised bed on top of the air-distribution grate, - forming an injection zone (2, 12) in a fluidised bed where a feed stream of seed particles is contacted/coated by the liquid product by simultaneous injection of a feed stream of the seed particles through inlet and a feed stream of the liquid product in the form of a spray of dispersed liquid droplets through inlet, - forming a granulation zone (3, 13) in the fluidised bed where contacted/coated seed particles are dried, shaped and cooled to form granules, - extracting granules from the granulation zone (3, 13) and sorting the extracted granules into three fractions; undersize granules with too small diameters compared to the desired size range, on-size granules with diameters within the desired size range, and oversize granules with too large diameters compared to the desired size range, - passing the fraction of on-size granules to post-processing treatment for forming the product granules, - removing the fraction of oversize granules from the granulation process, and - passing the fraction of undersize granules into the feed stream of seed particles, characterised in that - the granules are made to pass through at least one classifier (3a, 21) placed in the granulation zone of the fluidised bed, which segregates the granules according to their size and which passes at least a part of the segregated undersize granules in an internal recirculation back into the injection zone (2, 12) for further enlargement, - heat is exchanged from the granulation zone in the classifier (3, 21) by use of heat exchanger tubes extending in a distance from each other across the horizontally oriented cross-sectional area of the classifier (3a, 21), and - the heat exchanger tubes are at several heights of the classifier (3a, 21). - applying a granulator according to any one of claims 5 to 8, - forming a fluidisation zone in a fluidised bed on top of the air-distribution grate, - forming an injection zone (2, 12) in a fluidised bed where a feed stream of seed particles is contacted/coated by the liquid product by simultaneous injection of a feed stream of the seed particles through inlet and a feed stream of the liquid product in the form of a spray of dispersed liquid droplets through inlet, - forming a granulation zone (3, 13) in the fluidised bed where contacted/coated seed particles are dried, shaped and cooled to form granules, - extracting granules from the granulation zone (3, 13) and sorting the extracted granules into three fractions; undersize granules with too small diameters compared to the desired size range, on-size granules with diameters within the desired size range, and oversize granules with too large diameters compared to the desired size range, - passing the fraction of on-size granules to post-processing treatment for forming the product granules, - removing the fraction of oversize granules from the granulation process, and - passing the fraction of undersize granules into the feed stream of seed particles, characterised in that - the granules are made to pass through at least one classifier (3a, 21) placed in the granulation zone of the fluidised bed, which segregates the granules according to their size and which passes at least a part of the segregated undersize granules in an internal recirculation back into the injection zone (2, 12) for further enlargement, - heat is exchanged from the granulation zone in the classifier (3, 21) by use of heat exchanger tubes extending in a distance from each other across the horizontally oriented cross-sectional area of the classifier (3a, 21), and - the heat exchanger tubes are at several heights of the classifier (3a, 21).