US2918910A - Radiant steam generating unit with tubular furnace division wall sections spaced apart to form a gap aligned with the hopper bottom throat - Google Patents

Description

1959 L. M. FINK 18,910

1 RADIANT STEAM GENERATING UNIT WITH TUBULAR FURNACE DIVISION WALL. SECTIONS SPACED APART To FORM A GAP ALIGNED WITH THE HOPPER BOTTOM THROAT Filed Aug. 18, 1955 3 Sheet -Sheet 1 3 ANVENTOR.

Leroy M. Fir 1k ATTORNEY Dec. 29, 1959 L. M. FINK 2,918,910

RADIANT STEAM GENERATING UNIT WITH TUBULAR FURNACE DIVISION WALL SECTIONS SPACED APART TO FORM A GAP ALIGNED'WITH THE HOPPER BOTTOM THROAT Filed Aug. 18, 1955 3 Sheets-Sheet 2 ill INVENTOR.

Leroy M. Fink ATTORNEY Deg. 29, 1959 L. M. FINK 2,918,910

RADIANT STEAM GENERATING UNIT WITH TUBULAR FURNACE DIVISION WALL SECTIONS SPACED APART TO FORM A GAP ALIGNED WITH THE HOPPER BOTTOM THROAT Filed Aug. 18, 1955 3 Sheets-Sheet 3 FIG. 3

EN TOR.

y Leroy M. Fink AT TOR NEY United States Patent 2,918,910 RADIANT STEAM GENERATING UNIT WITH TU- BULAR FURNACE DIVISION WALL SECTIONS SPACED APART TO FORM A GAP ALIGNED WITH THE HOPPER BOTTOM THROAT Leroy M. Fink, Union, N.J., assignor to The Babcock & Wilcox Company, New York, N.Y., a corporation of New Jersey Application August 18, 1955, Serial No. 529,153

1 Claim. (Cl. 122-478) gases from fuel burning means, and the gases exit from the furnace through one or more gas passes in which there is disposed a convection section preferably including a steam reheater at least predominantly in one of the passes and a steam superheater at least the predominant part of which is disposed as within the second gas pass.

The ratio of fluid heating surface of the furnace to the total steam generating surface of the unit and the ratio of total furnace wall steam generating surface to the total furnace gas space are increased to a predetermined extent by the use of a substantial proportion of the total number of steam generating wall tubes to form upright furnace division walls separating the furnace into a plurality of sections or chambers through which the heating gases flow in parallel from the fuel burner means to the convection section.

The furnace of the steam generating unit of the invention is preferably of the hopper bottom type and the initial parts of the gas flow paths of the convection section are separated from the highest gas temperature parts of the furnace sections by an arch which may be described as extending into the furnace chamber and over a substantial part of the width of the lower section of the furnace. This arch preferably includes, or is defined by, parts of a plurality of the furnace wall steam generating tubes. The vertical plane adjacent the arch nose or the innermost part of the arch is coincident with upright gaps in the furnace division walls, the gaps being aligned vertically with the throat of the hopper bottom and providing for gas pressure equalization between the furnace sections separated by the division walls. Some of the division wall tubes extend upwardly through the arch and across the gas entrance of the convection section where these tubes have offset or zigzag formations some of which extend into the upright extension of the gaps and close off parts of these gap extensions, providing appropriate spaces within the convection gas pass for soot blowers.

The invention will be set forth concisely in the claim, but for a complete understanding of the invention, its advantages and uses, recourse should be had to the following description which refers to a preferred embodiment of the invention shown in the accompanying drawings.

In the drawings:

Fig. 1 is a diagrammatic view in the nature of a side sectional elevation of the illustrative unit;

'Fig. 2 is a plan section on the line 2.2 of Fig. 1; and

Fig. 3 is a vertical section on the line 3-3 of Fig. 1, along a plane disposed at right angles to the plane of Fig. 2.

The furnace of the steam generating unit shown in the drawingsis preferably of rectangular cross section hav- .ing a front wall 10, a rear wall 12, and. side walls 14 and ICC 16 which preferably include upright steam generating tubes leading from lower headers such as the lower headers 20-22 to the steam and water drum 24. The lower headers receive water from the water space of the drum 24 by means of one or more large diameter downcomers 26 which are appropriately connected to the lower headers, in a manner well understood in this art.

The steam generating'tubes 28 along the front wall 10 have their upper parts appropriately connected, as indicated at 30 to the steam and water mixture space of the drum 24 which may preferably include steam and water separating means of the type shown and described in the patent to Rowand et al. No. 2,289,970, July 14, 1942.

Some of the steam generating tubes 32 along the rear wall 12 have inwardly bent arch portions 34 included in the lower sides of the arch 36, and these tubes continue through the upper arch portions 38, included in the floor of the initial part of the convection gas pass, disposed above a high temperature section of the furnace. These tubes, or at least some of them, continue through the upright screen portions 40 and thence through the roof sections 42 along the roof of the initial part of the convection gas pass and then along the roof of the furnace to such connection with the drum 24 as indicated at 30. Others of the wall tubes 32 along the' rear furnace wall 12 continue directly upwardly as indicated at 44. Thence, they continue as the screen sections 46 widely spaced from the screen tube sections 40 across the gas flow in the convection gas pass. Thence, they continue through the roof of the convection gas pass as indicated at 48, and

thereafter they continue through the circulator sections 50 to appropriate connections with the drum 24.

The side walls 14 and 16 (Fig. 2) of the furnace likewise include upright vapor generating tubes connected at their lower ends of the headers 21 and at their upper ends to the header or headers 52 which is (or are) appro-- priately connected to the drum 24 by circulators such as 54 and 56.

The floor and roof of the rear portion of the convection gas pass include tubular sections 60 and 62 which are parts of conduits leading from the header 64 along the gas pass floor, thence through the screen sections 66 and 68, and thence through the roof sections 62 and the circulator sections 70 to the steam space of the drum 24. Thus, these tubes or conduits may constitute an initial part of the steam superheating means.

The furnace of the illustrative unit includesa hopper bottom with downwardly converging walls such as indicated at and 82 in Fig. 1. These walls preferably include the lower parts of the steam generating tubes 28 and 32 which are connected at their lower ends below the ash hopper discharge throat 84, to the headers 20 and 22.

At an elevation above the hopper bottom there are three horizontal rows of fuel burners 86 for firing the furnace. These burners are adapted to burn pulverized coal and they may also be combination burners, adapted to burn other fuels. The burners are disposed within a burner box 88 which is connected to receive high temperature secondary air, in a manner Well understood b those skilled in the art.

The furnace is divided into three sections, 90-92, by division walls 94 and 96, as indicated in Fig. 3. These division walls include closely or contiguously arranged upright vapor generating tubes appropriately connected into the fluidcirculation of the unit. Such connection may include the lower headers 98 and 100, the downcomers 102 and 104 appropriately connected to the water space of the drum 24. the upper headers 106 and 108, and appropriate circulators 109115 connecting the headers 106 and 108 to the steam and water mixture space of the drum 24 at distributed positions along the length of the drum, as indicated in Fig. 3

As indicated in Fig. 1 of the drawing, the tubes of each furnace division wall 94 and 96 are arranged to form a left-hand section 120 and a right hand section 122 separated by a gap 124, vertically aligned with the throat 84 of the furnace hopper bottom. The division wall tubes of the right hand sections 122 extend upwardly between adjacent tubular sections 34-38 of the arch 36 but at a position just above upper face of the arch these tubes are offset to the left as indicated at 126. These offset positions close off an upper part of the gap 124 and provide for an appropriate location for the soot blower 128. Above the offset positions 126 the pertinent division wall sections are offset to the right as indicated at 130 to provide for appropriate location of the soot blower 132 in the gas 124, and above the level of these second offset positions the pertinent division wall tubes again bend to the left where they continue through the roof of the furnace and/ or the gas pass to appropriate connections with one of the headers 1136 and M8. The pertinent upper parts of the furnace division wall tubes may be described as of Zigzag formation.

In the illustrative steam generating unit, steam, separated from the water in the steam and water mixture entering the drum 24 flows through the superheater supply tubes 140, through the tubular sections 79, the roof sections 62, the screen sections 65 and 68 and the floor tube sections 61), of the initial superheater section to the header 64. From this header the steam flows through appropriate circulators such as 142 and 14-4 to the headers 146148 disposed at both side walls of the convection section. From these headers the steam flows upwardly through superheater side wall tubes 150 to the upper side wall headers such as ll2. From these side wall headers the superheated steam flows through conduits to the intermediate header 156, From this header the steam flows downwardly through the inlet tube sections 158 and thence through the serially connected return bend tubes forming the banks 16i3162 of convection superheater tubes disposed as indicated in Fig. 1. From these banks of tubes the steam flows to the header 164 and thence through the tubes 166 to and through an attemperator 168 to the inlet header 170 of a convection secondary superheater consisting of serially connected return bend tubes such as 172 and 174 forming a bank of upright and horizontally spaced tubes disposed across the gas flow near the gas entrance of the convection section. The superheated steam leaves the secondary superheater outlet header 175 and is conducted to a steam turbine of a power plant, or to another point of use.

The Fig. 1 unit is also shown as including a reheater bank of tubes 180 formed by serially connected return bend tubes and including reheater headers 132 and 134.

In an alternate construction, insofar as reheater is concerned, the convection gas pass may be divided by steam generating tubes into a plurality of parallel gas passes with the superheater at least predominantly separated from the reheater in separate gas flows. In this modification the flow of heating gases through the separate gas passes may be controlled or proportioned in order to control superheat and reheat temperature over a wide range of vapor generating rate.

By such control, superheated and/or reheated steam temperature may be maintained at a predetermined value, or predetermined values by recirculating heating gases withdrawn through the opening 1%, beyond the convection gas pass and conducted to the throat 84 of the fur nace hopper bottom, in increasing percentages of the total gas flow, as the rate of vapor generation decreases through the lowermost part of the load range. This may be accomplished by a gas recirculation system including a gas recirculating fan 192, the inlet of which is connected by duct work 194 to the opening 1%. The outlet of the fan 192 is connected by duct work 1% to other . duct work components 198 and 200 leading to openings between the adjacent parts of the vapor generating tubes which are connected to the header 22. Appropriate control of the flow of recirculated gases for maintaining a predetermined superheated steam temperature on a wide load range, preferably takes place through the operation of known control elements combined so as to regulate the recirculated gas fiow in accordance with departures of superheated and/or reheated steam temperatures from an optimum value and in accordance with variations of steam flow.

As will be understood by those skilled in this art, the pr zre parts of the illustrative unit are insulated and enclosed by appropriate heat insulating and gas tight boundary constructions such as the roof 21b2, the front and rear walls 2% and 2th; and the side walls 298 and 238' associated with the roof. Similar casing comporents enclose the pressure parts and other sections of the unit. Some of these are indicated at 21221l8.

Whereas invention has been described with reference to a particular embodiment shown in the drawings it is to be appreciated that the invention is not limited to all of the details of that embodiment. It is, rather, to be taken as of a scope commensurate with the scope of the subjoined claim.

What is claimed is:

In a high pressure steam superheating and generating unit, wall means including closely arranged steam generating tubes and defining the upright boundary surfaces of a furnace, said means forming a gas outlet at the upper part of tne furnace, means supplying the furnace with high temperature heating gases at the lower part of the unit for upward flow through the furnace, gas pass Wall means forming a convection gas pass leading from the gas outlet of the furnace at a position remote from the entry of high temperature gases in a gas flow sense, said gas pass wall means including arch extending substantially into the heating gas now at a position above the lower part of the furnace and including therein parts of some of the steam generating wall tubes, means including the lower parts of some of the furnace wall tubes and defining a hopper bottom for the furnace with a throat of substantial width for the discharge of fuel ash therethrough at the lower part of the unit, other upright and closely arranged steam generating tubes included in a furnace division wall having two horizontally spaced apart division wall sections with a vertically extending gap therebetween, said gap being aligned with the throat of the hopper bottom and having one edge aligned with the nose of the arch, some of the division Wall tubes extending vertically through the arch into the convection gas pass and having their upper sections offset adjacent the gas entrance of the gas pass to form a substantially continuous division wall above the arch level, convection steam superheating means disposed within the convection pass, soot blowers appropriately distributed at positions Within the convection pass and in the spaces left by said offset division wall tubes, fuel burning means for each furnace section, and a recirculated gas system including a recirculated gas fan and fan inlet ductwork receiving partially cooled heating gases from a position downstream of the superheater in a gas flow sense and having fan outlet ductwork supplying recirculated gas at the hopper bottom for passage of the recirculated gases upwardly through the throat of the hopper bottom.

References Cited in the tile of this patent UNITED STATES PATENTS 2,330,240 Raynor Sept. 28, 1943 2,781,746 Armacost et al. Feb. 19, 1957 2,821,965 Vogel Feb. 4, 1958 FOREIGN PATENTS 109,224 Sweden Oct. 7, 1943 1,071,977 France Vlar. 10, 1954 1,045,900 France July 1, 1953

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