US1063585A - Steam-superheater. - Google Patents

Description

J.C.PARKER. 4 STEAM SUPERHEATER. APPLICATION FILED NOV. 28, 1908.

1,063,585, Patented June 3,1913.

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JOHN C. PARKER, OF PHILADELPHIA, PENNSYLVANIA.

STEALLSUPERHEATEB;

Specification of Letters Patent.

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Patented June 3, 1913.

Application filed November 28, 1908. Serial No, 464,931

To all whom it may concern:

Be it known that 1, JOHN G. PARKER, a citizen of the United States, residing in the city of Philadelphia, county of Philadelphia, and State of Pennsylvania, have in vented certain Improvements in Steam- Superheater's.

My invention is 'a superheater which will maintain, in relation to the generator, an

approximately constant efficiency ratio or a substantially equal rate of heat absorption by the saturated and the superheated steam, under the widest variations of steam output, so that the superheat temperatures Will remain practically the-same through different ratesof working and the highest eiliciency be attained, while the super-heater tubes,

' subjected to the highest heating efiects, are

designed so that steam actively flowing therethrough will protect them by carrying away substantially the same number of heat units-per-unit of area and time as are car ried awayfrom the similarly situated generator tubes, and when there is no steam or insuflicient steam therein to carry away the heat, said superheater tubes are'protect-ed. by the automatic admission'oit water thereto, the water being evaporated and automatically excluded by the rise of temperature and the pressure of the steam generated thereby.

The characteristic features of my improvements will fully appear from the following description and the accompanying drawing in illustration thereof.

In the drawing, the super-heater is illustrated as applied to a conventional type of steam generator shown in sectional elevation.

The drawing represents furnace walls 1 and 2 with the grate 3 disposed between them, and, supported by the walls, the head ers 4t and 5 with the tubes 6 connecting them, the headers being connected by the respective conduits 7 and 8 with the steam and water drum 9. A baillc 10 directs the heated products of combustion from the primary combustion chamber 11 through the pass 12 adjacent to the bridge wall 2, whence the hot gases are carried along the tubes 6 by the batlles 1.0 and 10", escape into the chamber 13 containing the-drum 9, and flow thence through the due 1a.

A conduit 1-3 is carried, within the furnace walls, from the top of the drum 9 to are disposed in the primary combustion a,

chamber 11, directly below the tubes 6, in the. path of the products of combustion flowing to the pass 12. A conduit 19, within the furnace walls, leads from the box 17 to the drum 20 which is placed in the chamber 13 above the drum 9. A conduit 21, having an inlet at a level above the bottom of the drum 20, leads from this drum. to the steam space in the top of the drum 9 and has the automatically closing valve 22 for preventing reverse flow therethrough. A conduit 23, having an inlet lower than the inlet to the conduit 21, leads from the bottoni of the drum 20 to the box 16 and has therein the automatically closing valve 24 for preventing reverse flow therethrough.

Steam is generated and evolved from the water circulating through the tubes (3, collects in the top of the drum 9, 'fiows through the conduit 15 to the box 16,thence through the tubes 18 into the box 1?, and thence through the conduit 19 into the drum 20.

ater collected in thedruni 20 may dis charge through the conduit 21, down to the top thereof, into the drum 9, and the remainder through the tube 23, the box 16 and the tubes 18 when the pressure of steam from these tubes tending to close the valve 24 is less than the pressure of water from the drum tending to openit. W hen the tires are banked or are being started. and there is insufficient steam or no steam flowing through the tubes 18 of the superheater, the

said. tubes will be supplied with water from the superheated steam drum or reservoir 20. The evaporating water in the superheater and the steam genera ted therefrom discharges through. the conduit- 19 intothe drum 29. There is thus provided a separate circuit comprising the superheater tubes and the superheater drum, with means for holdin alimited 'uantit 7 of water in the en mi:-

heater drum and delivuing it to the superheatertubes when the steam ceases to circulate therethrough sufficiently.

The superheater tubes, located so that they are subjected to substantially the same direct action oi 11119 tire and consequent high heating effects as the lower geherator tubes,

are of small bore, preferably about one inch in internal'diameter, ,with consequent high heat transmitting capacity so unit of SUP. face for a given frictionfl'loss or drop in pressure; with greater ability to withstand hea'ter tubes is to be avoided since proper circulation is prevented thereby and-it is desirable that the loss in. pressure due to such friction should not exceed ten pounds at the rated capacity of the boiler, while itis preferable that it should not be more than five pounds. with a 'given number and length of tubes, both friction and velocity decrease with an increase in the diameter of the tubes until a point is reached where the tubes will be destroyed because the heat is not carried away with sullicient rapidity and also there is a loss in superheating eiiiciency. If the tubes are large in diameter, in order to obtain the desired degree of superheat and protect the tubes an objectionable resistance, in excess of the practicable drop in pressure, would be developed owing to the internal friction between the particles of steam, which would have no useful effect in the absorption of heat and the protection of the tubes, a

comparatively small number of the steam particles coming or being kept in contact with the heating surfaces. In other words, if all of the steam were passed through a single tube of large diameter an excessive the relatively sn'iall rn'oportion of the steam heat particles in intact with the heating surface per unit of cross section and the high pressure requisite for moving the film of steam in contact with the tube at a suflicientl'y high rate. In practice it is found that it is not desirable to use a tube of more than about one inch or less than about threefourths inch internal diameter, the length being determined. by the degree of superdesired and the number by the permissible drop in pressure horsepower required. With the practicable length and number of tubes, I have found that for economy, cfliciency and safety, their internal diameters should not be more than an inch and a quarter and. generally not less than three-quarters of an inch.

The lower diameters with proportionately increasing numbers and decreasing lengths are theoretically preferable, but below the given limit increase the expense, while the and the diameter of one inch and, with some designs, slightly more have been found capable of withstamling the highest heating ell'ects of the tire. A typical construction that has been used successfully directly over the lire, in a one thousand horse power boiler with the production of one hundred and fifty dcgrccs of superheat at one hundred and seventy-lite pounds pressure, comprises fifty tubes, fourteen feet in length and one inch in internal diameter. 1 have found that a. substantial increase in this diameter cannot be made with safety without an im practicable increase in the length or an im- PllttlltfllJle decrease in the number of these heater tubes.

It has been proposed to use superhcuter tubes directly over the fire but they have failed because it was not understood how to prevent them from burning out and attain the elliciency ratio, attained by my improvements.

Having described my invention, I claim:

1. In a superhcatcr, the combination of a furnace and a generator having a steam collecting chamber, with a set of superheater tubes exposed to the direct action of the furnace fire, a conduit for carrying steam from said collecting chamber to said superhcater tubes, a reservoir, a conduit for carrying steam from said superheater tubes to said reservoir, and a conduit for carrying water from said reservoir to said superheater tubes.

2. In asuperheater, the combination of a generator with a set of supcrheater tubes, a conduit for carrying steam from said generator to said superhcater tubes, a reservoir, a conduit for carrying steam from said superheater tubes to said reservoir, a conduit having an inlet above the bottom of said reservoir for carrying water therefrom to said gei'icrator, and a conduit for carrying water from said reservoir to said superheater tubes.

In a supcrheater, in combination with a generator, a set of superl'ieater tubes, a conduit for carrying steam from said generator to said superheater tubes, a reservoir, a conduit for carrying water from said reservoir to said superhcater tubes, :1 check valve for preventing reverse ilow through the second named conduit, and a conduit -for carrying water from said reservoir to said generator, said last named conduit having an inlet above the inlet to said second named conduit.

4, In a superheater, in combination with a generator having a steam collecting chamber, a set ofsuperheater tubes, a conduit leading from said collecting chamber to said supei'healer tubes, a reservoir, a conduit leading from said superheatcr tubes to said reservoir, a conduit having an inlet above the bottom of said reservoir and leading therefromflo said collecting chamber, a.

for preventing reverse fiovv through said last named conduit.

5. In a superheafr, the combination, of a furnace and a generator, with a set of superheater tubes, a conduit for carrying steam from said generator to said tubes, a reservoir, a conduit for carrying steam from said tubes to'said reservoir, anda conduit for carrying Water from said reservoir to said generator.

(3. "In a superheater, the combination of l a furnace and a generator, with a set, of

superheater tubes,'a conduit for carrying steam from said generator to said tubes, a

reservoir, a conduit for carrying stea mfrom said tubes to said reservoir, and a further conduit for carrying Water from said reservoir to said tubes.

In Witness whereof I have hereunto set my name this 24th day of'Novembr A., D. 1908, in the presence of the subscribing Wit-' nesses.

JOHN C. PARKER. Vitnessesz ROBERT JAMES EARLEY, CHARLES N. BUTLER.

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