US1920776A - High pressure boiler - Google Patents

Description

W. R. WOOD HIGH PRESSURE BOILER Filed April 2, 1930 2 sheets sheet l INVENTOR.

W A? BY WML WTM ATTORNEYS.

Aug. 1, 1933. w. R WOOD 1,920,776

HIGH PRESSURE BOILER Filed April 2, 1950 2 Sheets-Sheet 2 z/ Kw T ATTORNEYS.

Patented Aug. 1, 1%33 nns 1,926,776 I men rnnssnnn cornea Wilfred lit. Wood, London, England, assignor to International Combustion Engineering Corporation, New York, N. 5.6., a Corporation of Delaware Application April 2,1934 Serial No. 440,883 3 Claims. (Ci. l22--235) 5 The chief object of the invention is reduce the cost of such installations while still retaining effectiveness and obtaining development of high capacities from a relatively small installation.

One of the chief items of expensein high pressure boilers is the cost of drums which must have thick walls in order to provide ample ligament strength to withstand the pressures.

According to my invention I propose to greatly reduce this cost item and otherwise simplify the installation.

Superheaters are also costly, and it is. another object of the invention to provide a combination and arrangement of parts such that a small superheater may be employed, while still retaining the other advantages of my invention.

The, boiler is. such that the gases leave at a high temperature and to reduce the temperature, I provide convection heat devices independent of the boiler, such as a reheater or economizer, boiling or non-boiling, followed by a metallic air preheater.

I I also provide an arrangement whereby the air for combustion is always highly heated yet protected from overheat, While at the same time the temperature of reheat is under control.

The preferred arrangement for accomplishing the foregoing, I together with such other objects and advantages as may hereinafter appear, is

5 illustrated in the accompanying drawings, where- .Fig. l is a vertical section through an installation embodying my improvements, and Fig. 2 is a cross section taken on the line 2-2 of Fig. 1. g g V 1Incarrying out my invention l provide a combustion chamber A which preferably almost wholly defined by evaporating elements. More specifically the boiler elements are arranged so as to constitute a six-sided box which is, the combustion chamber. To this end I provide an upperfldrum 7 and a pair of headers 8. The rear wall of the combustion chamber is defined by a row of tubesS which; rise from the headers 8 to the drum 7. The bottom or" the combustion space is defined by two rows of tubes 10. which incline forwardly and upwardly from one of the headers 8 to the headers 11. These tubes 10 are spaced wide enough apart to permit the free gravitation of refuse particles to the ash pit 12 beneaththe rows of tubes 10," The front wall'oi the combustion chamber is defined by the upright tubes 13 which rise from the headers 11 to the header means 14; By employing pairs of headers 8, 11 and 14, the front and rear wall tubes can be placed surhciently close to practically make a continuous water wall.

The top of the combustion chamber is defined by preferably two ormore rows of tubes 15 which incline inwardly and upwardly from the header 1d and then bend sharply upward at their inner ends for connection with the drum 7. These tubes are spaced far enough apart to permit of the free passage of the gases of combustion to the space 16 thereabout and in which is located the superheater. 17. The tubes 9 pass upwardly through the spaces betweenthe tubes 15. The

sides of the combustion chamber are defined by the upright tubes 18, the lower ends of the tubes of each side wall preferably passing to the exterior for connection to the headers 19 and the upper ends preferably passing to the exterior for connection to the headers 20. The tubes 18 present a substantially continuous water wall. The headers 19 are supplied from the lower of the headers 8 by means of tubes 21 which lead inwardly from the header 8 and then bend out for connection to the headers 19, the number of the tubes 21 and their points of connection with the headers 19 being such as to adequately supply the tubes 18 with substantially uniform distribution or supply as between such tubes. Similarly the headers 20 are provided with a plurality of pipes 22 which. lead inwardly and then rearwardly for connection with the drum 7. Downcomers 23 lead from the drum '2 to the headers 8, these being of suflicient size and number to secure adequate supply for the drum or header 8.

Fuel to be burned in suspension, preferably powdered coal, is admitted in the lower part of the combustion chamber by burner means 24 located at the corners and disposed so as to deliver luel and flame streams tangent to an imaginary circle, thus producing a vortical turbulent iu-el and flame stream with intense combustion. Preferably combustion is completed 100 within the combustion space so that only gases of combustion pass between the tubes 15 and sweep over the superheater 17 on their way to the offtake 25; After leaving the superheater the gases over the inner ends of the tubes 15and 105 the upper ends of the tubes 9 and 23.

, An arch 26 is carried on the tubes 15, the length of this arch being adjusted to give the desired temperature for the superheater 17. By adding to or removing tile from the arch the sweep of the gases over the superheater 17 and their velocity may be regulated, giving control of superheater temperatures. All the. gases sweep over the superheater which may therefore be made small. I

It will be seen from the foregoing that the boiler is a very simple one and because of the small number of tubes connected to the drum 7, it can be made of a size only large enough to secure adequate steam release and of a thin walled thickness. In this connection very strong ligaments can be secured by simply carrying the points of connection of the tubes 22, 15, 9 and 23 circumferentially around the drum '7 with relatively wide spacing.

Because most of the tubes of the boiler are subject to radiant heat and because of the intense combustion, there is a very high rate of heat transfer and a large steaming capacity from a relatively small installation obtained.

"The gases, however, enter the top of the offtake 25 at a relatively high temperature because of the very small amount of convection surface of the boiler. I meet this condition by providing convection heat absorbing elements located. in

' and is further lowered by passing through the combustion air preheater 29 which serves to' lower the final or stack temperature'to an allowable limit from the standpoint of economical operation. I

It will be noted that the convection elements in the offtake are not connected to the boiler proper. If these convection elements were connected to the drum '7 and to the header 8, the drum would have to be made much larger and of great wall thickness in order to provide adequate ligament strength.

The combination and arrangement of parts, therefore, is such as to carry forward the idea of small, thin walled, relatively inexpensive drum 50 the sweeping .of the cooler gases adjacent the tubes into the main body of the fuel and flame, which ensures more complete combustion of all combustibles and lowers the mean temperature. This temperature, however, is high.

There will be very little water in the boiler, and steam may be gotten up very rapidly. The primary heater is in a high temperature and hence can be made quite small.

It will be seen on inspection of Fig. 2 that the reheater is composed of sections, the first few sections 27 occupying the full cross sectional space of the offtake, while the sections 28 are arranged in two groups separated from one another to provide a space 30 in which I locate a pipe or conduit 31 controlled by a damper 32. By adjustment of the damper the amount of gases passing over the sections 28 may be varied so as to control the temperature of reheat. With' the damper full closed, all of the gases will pass over the sections 28. With the damper full open only a small portion of the gases will pass over the sections 28. The surface presented by the sections 27, however, is ample at all times to protect the metallic air heater from overheat. The control provided makes it possible to secure sufficiently high reheat, even at relativelylow ratings.

I claim 1. In a high pressure reheat-type boiler installation; a generally box-like combustion chamber substantially completely defined, in its upright walls, by rows of tubes adapted for radiant heat transfer; a water wall at the bottom of the chamber; a plurality of water tubes extended across an-upper portion of the chamber; means for burning fuel in suspension in said chamber;

a superheater above the tubes last mentioned; an ofltake communicating with the chamber laterally of said superheater and having a pass extended downwardly adjacent one side wall of the chamber and a pass extended upwardly for discharge of the products of combustion, whereby to provide a generally compact installation; a reheater in an advance portion of the first pass of said oiftake including tubes extended generally transversely of the direction of flow through said pass; by-pass means associated with a portion of the reheater tubes, the'remainder of the reheater tubes and said by-pass means being constructed to provide for the passage of substantially all products of combustion through the said remainder with different adjustments of said by-pass means; and additional heat absorption elements in the second pass of the offtake; whereby nearly the whole of the heat available from the fuel and flame stream and products of combustion is transferred to the water tubes defining the combustion chamber by radiation and to the superheater and the reheater by convection.

2. In a high pressure pulverized fuel burning boiler installation; a combustion chamber substantially completely defined by top and bottom and generally upright Water walls; a single drum, located above the combustion chamber proper, through which substantially all of the tubes of said walls are connected for circulation; a superheater disposed generally laterally of said drum and above the top water wall of said chamber; an offtake communicating laterally with the furnace through said superheater at one side of the latter, the offtake being extended downwardly from a point below said drum along an upright wall of the chamber and having an additional pass extended upwardly for discharge of the products of combustion; a reheater disposed in an advance portion of said ofitake' and having tubes extended transversely of the flow of the products of combustion therethrough, said reheater being divided generally into two portions, with the tubes in one portion extended substantially across the offtake from side to side thereof and with the tubes in the other portion spaced from each other and terminating in such manner as to provide a gas by-pass passage; bafile means in said passage for controlling gas flow therethrough; and additional heat absorption surfaces in the upwardly extended pass of the offtake.

3. In a high pressure reheat-type boiler installation; a generally box-like combustion chamber substantially completely defined, in its upright walls, by rows of tubes adapted for radiant heat transfer; a plurality of water tubes extended across an upper portion of the chamber; means for burning fuel in said chamber; a superheater above the tubes last mentioned; an ofitake comto provide for the passage of substantially all products of combustion through the said remainder with different adjustments of said bypass means; and additional heat absorption elements in the second pass of the offtake; whereby nearly the whole of the heat available from the fuel and flame stream and products of combustion is transferred to the water tubes defining the combustion chamber by radiation and to the superheater and the reheater by convection.

w. R, WOOD.

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