Electrification of an Ice Factory

Abstract

THE Grimsby Ice Company has now the largest ice factory in the world. The trawlers of Grimsby fish in the North Sea and off the west coast of Greenland, All the six hundred trawlers take supplies of ice when they set off for the fishing grounds, each boat taking about 15 tons when going to fish in the North Sea and four times as much when fishing in Icelandic waters. In the Metropolitan-Vickers Gazette for March and April, J. H. Lamb gives an interesting account of the electrification of the factory. The plant is capable of turning out 1,200 tons of crushed ice a day and delivering it into the holds of the fishing vessels by means of a fleet of motor lorries. Before reconstruction, the plant was driven by ponderous slow-speed engines. It has now been replaced by electrically driven compressors and all the auxiliary equipment has been completely electrified. The refrigerating medium is ammonia and the ammonia gas is raised in the compressors to a pressure of between 100 Ib. and 180 Ib. per sq. in. It is next cooled and liquified by passing through a condenser. The liquid then passes to the refrigerating plant in tubes surrounded by brine. The liquid expanding to its gaseous form absorbs heat from the brine which is cooled below 0° C. The cold brine is circulated in a large tank containing the cans which hold the pure water to be frozen. The four compressors are driven by four motors each of 600 horse power. These are supplied with electric power by the Grimsby Corporation, through a transmission line at 6,300 volts. The Ice Company is developing a new process of freezing which it is hoped will popularise frozen fish. Complaints have been made that frozen fish are ‘soft’ or ‘mushy’ when thawed. By rapidly freezing them the water between the flakes of the fish does not crystallise and when thawed it is stated that the fish is just as firm and white as fresh fish.