MODERN CONVENIENCES

Te Awamutu Courier, Volume 53, Issue 3783, 17 July 1936, Page 9

MODERN CONVENIENCES

HOT WATER CIRCULATION. Some time ago, following the prediction by an eminent physicist that man would never tap and control the supplies of atomic energy, I discussed the question of possible supplies of energy for the future, writes R.S. B. in the Melbourne Age. Whether one subscribes to the pessimistic view regarding intra-atomic sources or not, there is no doubt that we should avoid squandering our stores of natural energy and should use them as efficiently as possibly. The technical journals during the past few months have contained some interesting information about the progress that has been made in this direction, though the stimulus to these efforts is not a moral regard for the welfare of our descendants, but the more immediate urge of trade competition and industrial efficiency. Sir Frank Smith, in discussing the progress of the last few years, stated that the power stations of Great Britain as a whole generated almost exactly twice as much electrical energy from each ton of coal burned in 1934 as they did from a ton in 1920. Nevertheless the new Battersea station produces 50 per cent, more energy per ton than this average. If the other power stations were as efficient as Battersea, the power requirements of Great Britain could be supplied, using several millions of tons less of coal a year than at present. REVOLUTIONARY IDEA. A few outstanding power stations convert almost 30 per cent, of the heat energy of the coal into electrical energy, but for the great majority of stations the figure is still nearer to 20 per cent. Bearing this in mind, the suggestion recently made by Messrs. Donkin, Monkhouse, and other notable engineers, that we should make use of at least 70 per cent of the energy from coal, sounds quite revolutionary. Actually this is not so, but before giving an outline of the new ideas it is perhaps advisable to explain briefly why even the best power plants attain such a low efficiency at present.

Burning coal produces heat at a very high temperature—or highgrade heat energy as it may be called —and if we are going to convert much of that heat to mechanical or electrical energy we must begin to do so while it is till at a high temperature. In the steam engine, however, the steam never reaches anything approaching the temperature of the burning coal; in effect, the heat has already become comparatively low grade energy before the steam begins to drive the piston or turbine. Much of the improved efficiency to which reference has been made is due to using steam at higher pressures (and temperatures) and an essential feature of the new scheme is to begin using the steam at still higher temperatures. On the other hand, there are many purposes for which high-grade heat energy is not required. For instance, the open fire is a pleasant heat at, perhaps, 200 degrees Fahrenheit, but it would be uncomfortable if it raised the temperature of the room by more than a few degrees. Similarly, for all purposes requiring hot water, only low-grade energy is needed. In cold lands appreciable amounts of heat are used for horticultural purposes, and this is obviously not required at a high temperature. HIGH TEMPERATURE PIPES. The possibility of utilising 70 per cent, or more of the heat energy depends on the proper layout of an industrial town whereby all the fuel is burned at the "thermal electric stations.” The high-grade energy is, as it were, skimmed off and converted to electric power and the balance of heat conveyed by circulating steam or hot water under high pressure to where it may be used in such industries as soap boiling, confectionery

and food factories, and for all domestic and factory heating. In some systems in actual operation the water is circulated at a temperature almost 200 deg. Fahrenheit above its normal boiling point, so that by a suitable tapping device high-pressure steam can be drawn from these hotwater mains.

The really effective operation of such a system depends on the industrial unit being organised so as to maintain a correct balance between the demands for electric power and for heat. Obviously the construction programmes of the Soviet Union offer a better chance of achieving this organisation than do old-established industrial towns, and there are already many of these thermal electric stations in the U.S.S.R. In 1930 a station was erected in Moscow to operate at a steam pressure of 60 atmospheres and by 1935 one station was using steam at 130 atmospheres, or more than 18001 b. per square inch. From this station run 15 kilometres of heat-circulating mains (high pressure water pipes) whereby the heat that has not been converted to electric power is distributed to the neighbouring section of the city. The ultimate aim of the Soviet is to abolish the burning of fuel in the home, shop or factory, with an estimated saving of one-fifth of the fuel. ONLY SMALL HEAT LOSSES. Probably most people would feel a little dubious as to the amount of heat that would reach the more distant parts of the system in a climate such as that of Moscow. Actual experience has shown that the heat losses from the pipes are not very great, and in Moscow the pipes are simply coated with cement made of pumice and buried in the ground. The case is also cited by one writer of an English colliery where all the miners’ cottages up to two miles distant are heated by hot water circulated from the colliery. The pipes are buried in the ground without any kind of lagging round them, and the drop in temperature at the extreme point is only 10 degrees Fahrenheit. This figure, of course, does not enable us to decide how much heat is lost from the pipes per day, but merely tells that the water is circulating at such high speed that it goes right round the system without much drop in temperature. It seems clear, however, that heat may be economically distributed by means of hot water circulating in pipes, and this is the chief feature of the new propbsals.

An illustration of the indirect benefits that would result in industrial centres from the efficient burning of all the coal is contained in a report made a few years ago by the Air Pollution Advisory Board of Manchester. This states that atmospheric contamination adds at least £250,000 a year to the cost of household washing in Manchester, and causes a reduction of from 20 per cent, to 50 per cent, in effective sunlight as compared with a town a few miles away.