Superheater

“ As a matter of fact, the efficiency of a boiler and superheater, where the latter is properly designed and located, will be slightly higher for the same set of furnace conditions than would the efficiency of a boiler in which no superheater were installed. A superheater, properly placed within the boiler setting in such way that products of combustion for generating saturated steam are utilized as well for superheating that steam, will not in any way alter furnace conditions. ”

“ Where a properly designed superheater is installed in a boiler the heating surface of the boiler proper, in the generation of a definite number of heat units, is relieved of a portion of the work which would be required were these heat units delivered in saturated steam. ”

“ The standard basis, however, of boiler evaporation is one of heat units and, considered from such a standpoint, again providing the efficiency of the boiler and superheater is as high, as of a boiler alone, there is no additional fuel required to generate steam containing a definite number of heat units whether such units be due to superheat or saturation. ”

“ The superheater of a marine boiler is provided with a safety valve, and sometimes with a pressure gauge to enable the comparing of the steam pressure with that in the boiler, and should also be provided with a gauge glass, to show when heavy priming is going on. ”

“ On this basis 100 degrees of superheat with an economical steam turbine would result in somewhat over 3 per cent of saving in the coal for equal boiler efficiencies. As a boiler with a properly designed superheater placed within the setting is more economical for a given capacity than a boiler without a superheater, the minimum gain in the coal consumption would be, say, 4 or 5 per cent as compared to a plant with the same boilers without superheaters. ”

“ Since, however, steam cannot, under any imagined set of conditions, take up more heat from a tube than would water at the same average temperature, this fact supports the contention made that the actual transfer rate in a boiler must increase quite rapidly with the temperatures. The actual transfer rates in superheaters are affected by so many conditions that it has not so far been possible to evolve any formula of practical value. ”

“ The economy thus lies in helping the coal, or other fuel, do its work, or, to put it more specifically, it conserves the heat previously put out by the coal, and thus saves by using part of the heat over again.
Superheaters.—Another refinement, and one which goes to the very essence of a heat motor, is the method of superheating the steam. ”

“ In buildings of the second class, such as residences, office buildings and hotels, we have been, as a rule, satisfied with sufficient heat, and have relied upon such ventilation as is secured by the natural circulation methods. In such buildings, therefore, the system of heating most used is that known as "direct radiation," in which radiators, or some form of radiating surface, are located in each room, and connected by an arrangement of piping to a central source of steam or hot-water supply. ”

“ In both the steam and water heating systems the band or collection of pipes in each room may be covered with ornamental radiating plates, or otherwise treated or arranged to render them sightly and effective. In one form of the hot-water system, however, the collection of a mass of pipes in the rooms is dispensed with, and the pipes are massed in an air chamber over or adjacent to the furnace, where they are employed to heat a current of air introduced from the outside, and which heated [Pg 208] pure air is conveyed through the house by flues and registers as in the hot-air furnace system. ”

“ Above them tower numerous furnace stacks and chimneys from the boilers, with the exhaust pipes of the engines and steam-hammers. Towards summer, when the days lengthen and the sun pours down interminable volumes of light and heat from a cloudless sky, or when the air without is charged with electricity and the thunder bellows and rolls over the hills and downs to the south, and the forked lightning flashes reveal every corner of the dark smithy so that the heat becomes almost unbearable, a large quantity of the glass is removed to aid ventilation ”

“ This means quick and positive venting for steam, vapor, or hot water installations and provides rapid circulation, causes radiator to heat up more rapidly.
Air Vent (Steam heating)
The air vent on each main, allows the air to escape so that the heat arrives more rapidly to radiator. This of course, saves fuel.
Heat Controls
To take the heating of your home out of the area of dreams and out of the expensive realm of “feeling,” some sort of heat regulating device is recommended. It is foolish to say “Do you think it is warm enough?” to a group in the room. For no two will think alike! ”

“ Next, steam heat, which includes hot-water heating. This is one of the abominations of our civilization, and one of the methods by which our race is committing suicide. There is nothing wrong about steam heat in itself; the room is warmed in a harmless way; but the trouble is it stays warm only so long as the doors and windows are kept shut. You are in an air-tight box, and can be warm provided you do not mind being suffocated. The moment you open a door or window, you have a cold draft on your feet, and if you wish to change the air entirely you have to let out all the heat ”

“ The super-heater comprises a hollow ring-shaped cast-iron piece arranged in the chamber of the generator, in which the gases are developed, and is thus heated to a high temperature. The mixture of air and steam circulates in this super-heater before traveling to the ash-pit.
The feeder of the Winterthur gas-generator (Fig. 122) is composed of a receptacle having the shape of a tank or basin containing water and located below a closed cylindrical box. In this box a piston moves, which is provided at its lower end with a needle-valve. ”

“ Heating the air by steam is the next most healthy means; as the surfaces used are heated a little hotter, less of it answers the same purpose. The first cost is therefore less. It is the most rapid and convenient means of conveying heat to any distant point of anything now in use. Under the pressure of an ordinary boiler it will travel seven miles in one minute. The time I hope is not far distant when the subject of heating and ventilation will receive an amount of attention due to its importance. ”

“ A slight warming produces a small reaction; and if the temperature is raised a little more, combination takes place with energy and an explosion is produced.
Heating and Ventilation of Electric-lighted Buildings.—In his paper on the Heating of Large Buildings, A. R. Wolff, consulting engineer, shows that the introduction of electric lighting with isolated generating plants in large buildings has had a sensible effect on the solution of the heating and ventilating problem by practically conditioning the use of exhaust steam for heating. ”

“ As a uniform temperature must be maintained in the house, the fires, where steam is used, need watching continuously during cold weather, for the moment the water ceases to boil, the pipes cool off and a considerable time is consumed in starting the heat running again. With hot water there is much more latitude in attention, for though the fires dwindle' the water which fills the pipes will carry heat for a long time, and it will circulate until the last degree is radiated. But a hot-water system costs in the installation about one fourth more than steam. ”

“ Where a house is heated by a furnace, the style of this should be selected with great care, special regard being had to the economy of fuel. The systems of steam-heating, hot-water heating, or hot-air heating have each their merits, depending on the location of the house and the climate of the region. The cellar can also be used as a storeroom for those things not affected by the heat of the furnace, such as perishable food requiring an ice-box or a cool place, vegetables, especially those with a penetrating odor ”

“ The question of practical efficiency is, therefore, more strictly speaking, only one of effectiveness of surface. That is, of two radiators under exactly the same conditions of temperature and surroundings, that one which has such an arrangement of its surfaces as to give out the most heat per square foot is the most effective, usually called the most efficient. In all tests of radiators, the heat given off is measured by connecting them so that the steam which condenses can be accurately weighed, its pressure, quality and temperature being determined at the same time. ”

“ Both hot water and steam are utilized. Hot water heating, however, is preferable to steam, as it gives a much steadier heat. The radiators arc proportioned to give an average temperature of 65 degrees F. in each room during the winter months. There are automatic regulating devices attached to the radiators, so if the temperature rises above or falls below a certain point the steam or hot water is automatically turned on or off. Some buildings are heated by the exhaust steam from the engines but most have boilers solely for the purpose. ”

“ For healthful ventilation the indirect system of steam heating is by far the best yet devised, for it not only warms the room, but insures perfect ventilation as well. In this system, the air for warming the room is introduced through registers, having first been heated by passing over coils of pipe or radiators suitably located in the air ducts. There is a large volume of pure air constantly entering the room, which must displace and drive out an equal quantity of impure air. ”

“ The heating is a single-pipe steam system, the heat generated by a boiler in each building. The principal rooms are heated by radiators, with heating risers used elsewhere. The hardware and lighting fixtures are simple and substantial. ”

“ In this event, auxiliary radiators may be placed under that register, and the operation of the heating apparatus greatly facilitated thereby. This plan is superior to a furnace, and can be applied to hot-water or steam apparatus in dwellings. The reason that it is superior to a furnace is that the supply of heat is more uniform. It does not require the constant firing or attention that is necessary in the case of a hot-air furnace. It may be known that the temperature does not change with the pressure of steam or in the same proportion. ”

“ Every passenger-carrying steamer is provided with refrigerating rooms for the storage of perishable provisions; and as the comfort of the passengers, not to say their luxury, is bound up with these compartments, it will be interesting to glance at the method employed for creating local frost amid surrounding heat.
The big principle underlying the refrigerator is this—that a liquid when turned into gas absorbs heat (thus, to convert water into steam you must feed it with heat from a fire) , and that as soon as the gas loses a certain amount of its heat it reverts to liquid form. ”

“ Heating might now be accomplished without dust and ashes, without the destructive effects of steam, if enough houses would take electricity to enable a company to supply it in the form of a sort of dado carrying wires safely embedded in a non-conducting substance, or in the form of a carpet threaded with conducting wire. Both heating and cooling apparatus could be installed in the shape of a motor to replace the punkah man and the present buzz-wheel fan, and to give fresh air without the opening of windows which leads to half our housekeeping miseries. ”

“ As long as the temperature at the heated side of the furnace wall is kept constant, the temperature gradient and the rate of heat conduction also remain constant. Increasing the thickness of the wall lengthens the path through which the heat must travel, decreasing the temperature gradient and the rate at which heat appears at the outside surface. Raising the temperature in the furnace increases the temperature gradient and the rate of heat conduction, much as raising the inlet pressure increased the rate of flow of water in the pipe. ”

“ The hot water in the radiators cools and, in cooling, gives up its heat to the rooms and thus warms them.
In hot-water heating systems, fresh air is not brought to the rooms, for the radiators are closed pipes containing hot water. It is largely for this reason that thoughtful people are careful to raise windows at intervals. Some systems of hot-water heating secure ventilation by confining the radiators to the basement, to which cold air from outside is constantly admitted in such a way that it circulates over the radiators and becomes strongly heated. ”

“ Now, to apply these principles to every-day life, to the heating and ventilation of our houses, taking the open fire first, we find that it acts like the sun, heating exclusively by direct radiation. The rays of heat fall upon the sides of the room, the floor and ceiling, and the solid substances in the room, which thus become partially heated, and in their turn become secondary radiators. This radiant heat from the fire does not heat the air in the room at all, but the air becomes partially warmed by coming in immediate contact with the sides of the room, the furniture, &c. ”

“ Heat loss in buildings.—There have been considered in previous chapters the various kinds of radiators in use and the amount of heat given off by them under different conditions; and the subject now approaches a study of the particular way in which the heat is utilized. The object of any heating system is, of course, to maintain a uniform temperature in the building in question, and to do this it is necessary: First, to replace the heat lost by convection and radiation from the windows and walls of the building to the colder surroundings outside ”