US2013704A - Control apparatus for furnace air - Google Patents

Description

Sept. 10, 1935. J. H. WALKER CONTROL APPARATUS FOR FURNACE AIR 2 Sheets-Sheet 1 Filed July 15, 1929 Inventor H.WaIKer' W 4 fitter-neg J. H. WALKER 2,013,704

CONTROL APPARATUS FOR FURNACE AIR Sept. 10, 1935.

Filed July 15, 1929 2 Sheets-Sheet 2 INVENTOR @777 35/2. ila l/(e'r ATTORN EYAS' Patented Sept. 10, 1935 UNHTED STATES imam R; OFFECE James E. Walker, Detroit, Mich assignor to American Engineering Company, Philadelphia, Pa., a corporation of Pennsylvania,

Application July 15, 1929, Serial No. 378,265

6 Claims.

This invention relates to an improved means for measuring, distributing and controlling the air supply to various sections of a fuel bed in a furnace, and has for its object an improved organization of parts whereby. wasteful variations in the flow of air passing through the fuel bed at one point as compared with another on the grate may be noted and corrected, not only for the purpose of equalizing the combustion process in various parts of the fuel bed, some of which may have become coked or clogged with ash to a greater extent than at other points, but as well for the purpose of avoiding waste due to the production of unburned or partially burned l5 gases in certain parts, due to the deficiency in the supply of air, as well as to counteract the other extreme resulting through an excess flow of air through parts of the fuel bed that have been burned through prematurely, thus carrying with them heat units which are not recoverablefor any useful purpose.

In the drawings:

' Figure 1 is a front elevational view with a portion of the wall broken away to show some of the operating elements of my improved apparatus.

Figure 2 is a preferred form of draft-regulating means for any one of the several divisional units into which the grate space may be divided.

Fig. 3 is a vertical longitudinal section of my mechanism taken substantially along line 3-3 of Fig. 1, and

Fig. 4 is an enlarged detail view partly in elevation and partly in section, taken on line 6-4 of a Fig. 3 and looking in the direction of the arrows 85 there shown.

Referring first to Figs. land 3, A represents a bed or mass of fuel resting upon the grate or similar perforated support B, the exact details of which are, for the purposes of this invention, immaterial, as is also whether it is horizontally positioned or inclined at an angle to the horizontal. Positioned below the grate is the shell or air duct C, from which part or all of the air supply required for combustion rises, due to the variance in static pressure between that existing in the chamber C and that in the space above the fuel bed. Such variance in pressure may either be produced by a forced draft leading into the shell 0, or by the diminution of static pressure,

as by the action of the chimney, above the grate B, or by a combination of both of. these. The

grate B is divided intc sections, as along the and bottom, and each of which receives its separate or individual supply of air through one tube or chamber or another such as D, D, etc. Thus, insofar as the air supplied to any section of the grate is concerned, whether near the center thereof or near one side, the combustion process 8 might normally be appreciably variant, due to the relative permeability of the fuel mass thereabove, and-each section being capable of regulation and variance independently of the others.

Leading from the'throat K of each draft sec- 10 tion D, D, etc. is a pipe such as L, L etc., each of which connects with the end of one of the small tubes shown as O, 0'', O and 0 respectively of the multiple manometer N, which is a wellknown commercial and scientific article, consisting of a chamber partially filled with liquid, the walls of those portions of each of the tubes 0, 0', etc., immediately adjacent the manometer N being so angled and being transparent, as indicated at, Y, Y, Y and Y respectively, that a 20 small vertical displacement of the fluid level in the manometer N causes a measurable movement of the fluid within the tube. Also leading from an appropriate point in the shell or chamber 0 is a compensating pipe P, through which the 25 pressure at any time prevailing within the shell C is transmitted to the surface of the fluid in the manometer N, thus efi'ecting variations in its level therewithin accordingly, which variations are in turn transmitted into the several tubes of the 30 series 0, these changes being individually observable as to the conditions prevailing in the corresponding of the compartments D, D, etc., through the medium of the transparent portions of the series Y, Y, etc. 35

'A preferred form of damper or throat control for each of the compartments D, D, etc., is shown in Figure 2. It consists essentially of a straight or chimney portion E and a cornice or transition portion-F the several lines of union of 40 which provide at the top of the structure thus constituted a connection of the shape and size of that section of the grate with which the particular unit is immediately associated, thus of course leaving between the straight wall portions 45 E such spaces as X, which are of course closed against the upward egress of air through the shell C because of the union of the meeting edges of the adjacent transition or cornice pieces F of the several compartments thus constituted, along the lines Z already mentioned. Near the top of each compartment is pivotally supported a damper or closure member M, while the bottom or lower portions of two of the sides of the r' chimney structure E, such as H and I are in wardly curved as shown, one of these plates or wall pieces as H being hinged, as at J, and the other being preferably leftstationary. There is thus constituted by these. members and the flat or stationary sides G a, throat or air passage or orifice K of variable size and of generally Venturi character. It is a well-known fact that whereas in a Venturi tube of fixed dimensions the differential pressure at one end as compared with that prevailing at the throat diminishes very rapidly as the flow decreases and vice versa, adjustment of the cross sectional area of the throat will enable the regulation of the differential pressure for any given flow, so as to produce a deflection which is measureable, and is within the range of the manometer. I have shown the means for positively effecting such an adjustment in the provision of threaded shafts R which ride upon correspondingly internally threaded sleeves such as S, attached to the hinged side or plate as H. This adjustment may be effected either as to individual units, or if desired to a group of units at the same time, by means of shafts Q provided with hand wheels T. As shown more particularly in Fig. 3, the shafts Q are suitably journaled in one of the walls of the furnace, and in the stationary sides of the chimneys E. The hand wheels T are conveniently located outside of the shell C.

When there is a flow through the various chimneys or compartments D, the pressure prevailing in the throats of these compartments being less than the pressure in the subjacent chamber C the differences in pressure as shown by the displacement of the fluid in the transparent observation portions of the several tubes of the series is a measure of this flow according to well-known hydraulic principles. If then the several throats K are adjusted so as to be of equal area, and if a variance occurs to these several flows, due to any of the reasons above mentioned, such as variance in the degree to which any portion of the fuel bed may have become coked, the presence of fused ash at certain points or lack of homogeneity of the fuel, such variance can be compensated for and offset by a manipulation tion measurable within the range of the manometer. The relative magnitude of the air flows within the several compartments being thus regulatable, the tendency of one section of the fuel bed to burn through more rapidly than another can easily be counteracted according to the observed relative displacement of the liquid in the manometer tubes. The absolute quantities of air supplied through the shell C can also be simply computed from the manometer indications with the area of the several throats K properly taken into account.

It is of course to be understood that in place of the Venturi tube for the measurement of the flow through the medium of indicated pressure differentials, such other and functionally equivalent means as an orifice plate, a restricting nozzle or the like could easily be substituted t e efor without departure from the spirit of my invention.

What I claim is:

1. Means for ascertaining and regulating the flow of air through the various parts of a fuel sup- 5 porting grate, comprising in combination, a grate for supporting a fuel bed, a plenum chamber for supplying air thereto, one or more ducts interposed and forming the only connection between said plenum chamber and that portion of the grate overlying each duct, each duct having a throat-opening, a damper member in each duct independently operable to selectively control the air gdelivered therefrom, externally observable means-indicating the differences in pressure betweenthe throat of each of said ducts and the plenum chamber, whereby said dampers may be adjusted to insure the proper amount of air to the sections of the fuel bed overlying said ducts.

2. Means for ascertaining and regulating the air flow through the various parts of a fuel supporting grate, comprising in combination, a grate for supporting a fuel bed and a plenum chamber for supplying air thereto, one or more ducts interposed ,and forming a connection between said plenum chamber and that portionof the grate overlying eachduct, a damper member in each duct independently operable to selectively control the air delivered therefrom, externally observable means indicating the differences in pressure between the throat of each' of said ducts and the plenum chamber, comprising manometers,- each being in communication with said plenum chamber and said throats, thereby enabling said damp.- ers to be adjusted in accordance with the readings of said manometers.

3. Means for ascertaining and controlling the flow of air through the various parts of the fuel bed, comprising in combination, a grate for supporting said fuel bed, a pressure chamber for sup- 40 plying air thereto, one or more ducts interposed and forming the only connection-between said pressure chamber and that portion of the grate overlying each duct, each duct having a throat opening, damper means in each duct independently operable to selectively control the air de- ,livered therefrom, and flow measuring apparatus including externally observable means operatively connected to each of said ducts at the throat thereof, and to said chamber, said externally observable means thereby indicating in effect the difference between the total pressure and the static pressure of the air flowing through each of said ducts at the point of attachment of said apparatus thereto, whereby said damper means may be adjusted to insure the proper amount of air to the sections of the fuel bed overlying said ducts.

4. Means for ascertaining and regulating the air flow through the various parts of a fuel sup- 0 porting grate, comprising in combination, a grate for supporting a fuel bed and a plenum chamber for supplying air thereto, a plurality of ducts interposed and forming the only connection between said plenum chamber and that portion of the grate overlying each duct, each duct having an adjustable throat, a damper ineach duct independently operable to selectively control the air delivered therefrom, externally observable means indicating the differences in pressure between the throat of each of said ducts and the plenum chamber, and means operable for adjusting the cross sectional area of said throats whereby variation of the area of the throats effect a variance in the differential pressure between said throats and the enabling the magnitude of said differential pressure to be kept within limits necessary to produce observable actuation of said observable means.

5. Means for ascertaining and regulating the flow of air through the various parts of a fuel supporting grate, comprising in combination, a grate for supporting a fuel bed and a plenum chamber for supplying air thereto, a plurality of ducts interposed and forming the only connection between said plenum chamber and that portion of the grate overlying each duct, each duct having an adjustable throat of substantially Venturi cross section, a damper in each duct independently operable to selectively control the air delivered therefrom, externally observable means indicating the differences in pressure between the throats of each of said ducts and the plenum chamber, and means for adjusting the cross sectional area of said throats, whereby variation of the area of the throats efiects a variance in the differential pressure between said throats and the plenum chamber for any given air flow. thereby enabling the magnitude of said difierential pressure to be kept within the limits necessary to produce observable actuation of said observable means.

6. Means for ascertaining and regulating the air flow through the various parts of a fuel supporting grate, comprising, in combination, a grate for supporting a fuel bed and a plenum chamber for supplying air thereto, a plurality of ducts, interposed and forming the only connection between said plenum chamber and that portion of the grate overlying each duct, each duct having an adjustable throat of substantially Venturl cross-section, a damper member in each duct independently operable to selectively control the air delivered therefrom, externally observable means indicating the diflerences of pressure between the throats of each of said ducts and the plenum chamber, comprising manometers each being in communication with said plenum chamber and said throat, and means operable for simultaneously adjusting the cross-sectional area of each of said throats, whereby variation of the area of the Venturithroats effects a variance in the differential pressure between said throats and the plenum chamber for any given air flow, thereby enabling the magnitude of said differential pressure to be kept within limits necessary to produce observable actuation of the mariometers.

JAMES H. WALKER.

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