US3102514A

US3102514A - High capacity, high temperature vapor generator

Info

Publication number: US3102514A
Application number: US844919A
Authority: US
Inventors: Wilbur H Armacost
Original assignee: Combustion Engineering Inc
Current assignee: Combustion Engineering Inc
Priority date: 1959-10-07
Filing date: 1959-10-07
Publication date: 1963-09-03
Anticipated expiration: 1980-09-03

Description

p 3, 1963 w. H. ARMACOST 3,102,514

HIGH CAPACITY, HIGH TEMPERATURE VAPOR GENERATOR Filed Oct. 7, 1959 2 Sheets-Sheet 1 INVENTOR.

Wilbur H. Armocost ll TTOR NE T Sept. 3, 1963 w. H. ARMACOST 3,102,514

HIGH CAPACITY, HIGH TEMPERATURE VAPOR GENERATOR 7 Filed Oct. 7, 1959 2 Sheets-Sheet 2 Fig. 3.

//// MEMOR- Wilbur H. Armocost BY (Mm JTTORNEY United States Patent Ofifice 3,1025 14 Patented Sept. 3, 1963 3,102,514 HIGH CAPACITY, HIGH TEMPERATURE VAPOR GENERATDR Wilbur H. Armacost, Scarsdale, N.Y., assignor to Combustion Engineering, Inc., New York, N.Y., a corporation of Delaware Filed Oct. 7, 1959, Set. N 844,919 11 Claims. (Cl. 122-480) This invention relates generally to vapor generators and particularly to modern vapor generators for generating high temperature, high pressure vapor, as for example, the steam generators employed in the utility industry.

In firing of these vapor generators, fuel and air are introduced into the furnace with the fuel being consumed therein and combustion gases passing upwardly therethrough and out an outlet laterally disposed in the upper portion of the furnace with the gases then passing through a suitable gas pass and with heat exchange surface being disposed in the upper portion of the furnace and in the gas pass. While there are various ways of introducing the fuel into the furnace, such as from each corner of the furnace and directed tangentially to an imaginary vertical cylinder in the furnace or from burners located in one or more walis and directed toward an opposite wall or by means of other various arrangements, it has been found that the temperature and gas flow in the upper region of the furnace, and accordingly in the gas pass leading from the furnace, is not uniform across the width of the furnace and that this transverse temperature and iiow gradient varies with varying load. As the pressure and temperature of the units increases the problem created as a result of this uneven heat distribution characteristic across the gas stream also increases with the problem being severe in supercritioal units, i.e., those operating above the critical pressure. The reason for this is that as the pressure and temperature increase the proportion of vapor heating surface, either initial superheater surface or reheating surface, relative to the total heat absorption of the unit increases. Much of this surface is in the form of tubular heat exchange sections that extend into the upper region of the furnace and into the gas pass leading substantial variation in temperature of the gases across the furnace and/or a substantial variation in the flow of these gases, the tubular elements at one lateral location or region of the gas pass, i.e., high gas temperature or high gas flow region, will absorb substantially more heat than in another that has a lower gas temperature or flow and in the case of vapor heating surface this will result in the metal temperature of these tubes being substantially higher, producing localized areas of high metal temperature. This is extremely in these localized areas are at their allowable limit.

In accordance with the present invention, the problem with regard to unequal heat distribution across the gas upper portion of the furnace and the gas pass leading therefrom of a high capacity vapor generator so that the gas stream is divided into at least three separate parallel streams disposed in side by side relation across what wouid ordinarily be the Width of the gas stream. It is stressed that an ordinary high capacity, high temperature vapor generator is partitioned in this manner so that each of the passageways thus formed has the same type of surface disposed therewithin with this being essential in order that gas liow may be independently controlled in each passageway to effect an equalization of the heat absorption from the gases in the several passageways without upsetting or changing the superheat and reheat steam temperatures relative to each other. In order to effect this result it is apparent that the ratio of superheat surface to reheat surface in each of the several passageways will be substantially the same.

Accordingly, it is an object of this invention to provide an improved high capacity, high temperature vapor generator employing convection superheat and reheat surface over which the combustion gases generated in the furnace pass.

ther and further objects of the invention will become apparent to those skilled in the art as the description proceeds.

With the aforementioned objects in view, the invention comprises an arrangement, construction and combination of the elements of the inventive organization and method in such a manner as to attain the results desired as hereinafter more particularly set forth in the following detailed description of an illustrative embodiment, said embodiment being shown by the accompanying drawing wherein:

FIG. 1 is a vertical sectional view, somewhat diagrammatic, showing a high capacity steam generator embodying the present invention;

FIG. 2 is a sectional view, taken generally along line 2-2 of FIG. 1, showing the arrangement of the division Walls for forming several gas streams, and;

FIG. 3 is a sectional view taken along line 33 of FIG. 1.

Referring now to the drawing, wherein like reference characters are used throughout to designate like elements, the illustrative and preferred embodiment of the invention depicted therein includes furnace 16 which has its walls lined with vapor generating tubes in a conventional manner and with these tubes communicating at their upper end with steam and water drum 12 which is disposed alongside the unit as indicated in FIGS. 1 and 2. Fuel and air are introduced into the furnace, as for example in a tangential manner, through burners 14 with the combustion gases generated by the burning of this fuel in the furnace passing upwardly therethrough and out the outlet 16 provided in the upper region of rear Wall 18.

Extending from outlet 16 is the lateraily disposed gas pass 20 which communicates with the downwardly extending gas pass 22.

In the normal operation of the furnace, the temperature and gas flow across the furnace have been found to var this variation changing with. varying with regard to the heat absorption of exchange surface the various heat that is disposed in the upper region of the furnace and in the gas passes 20 and 22 with the effect being severe with respect to vapor heating surface where the metal temperature may be quite close to the temperature of the gases passing thereover.

In the illustrative organization the heat exchange surface disposed in the upper region of the furnace and in

gas passes

20 and 22 is generally conventional with that of high capacity, high temperature vapor generators. Extending down into the upper region of

heat exchange sections

24 and 26 with these sections cor prising the high temperature superheater section with steam flowing from sections 24 through section 26. Downstream of heat exchange section 26 is heat exchange section 28 disposed in gas pass 28, and section 33 disposed in gas pass 22 with these heat exchange sections from which it is conveyed to its desired point of use. Below heat exchange section 30 and downstream thereof with regard to combustion gas flow are the

heat exchange sections

34 and 36 which comprise the economizcr surface of the unit with water entering the economizer through header 38 passing through

heat exchange surfaces

34 and 36 and then up the header 40 from which it enters the steam and water drum through conduits 42.

Each of the

heat exchange sections

24, 26, 28, 3t], 34 and 36 are comprised of tubular members that are positioned in side by side, relatively closely spaced relation across the width of the furnace or of the gas passes 20 or 22 as the case may be.

The gas flow over these various heat exchange sections is divided into three parallel streams with the flow in each of the streams being independently controlled in order that the effect of the unequal temperature and flow distribution across the gas pass stream issuing from the furnaces lower region may be overcome. It has been found that at least three controllable streams are desirable in order to get the degree of regulation required. In the illustrative organization the upper region of the furnace gas pass 20 and the upper region of gas pass 22 are partitioned by suprheater heat exchange surface in order to divide the gas stream as mentioned. This heat exchange surface takes the form of a pair of

walls

44 and 46 each of which is comprised of sinuously bent tubes as best shown in FIG. 1. These tubes, identified as 48, extend down from the horizontally disposed header 49 are bent in unison at 90 so they extend forwardly to the front wall 50 of furnace 10 where they are reversely bent in internested fashion and extend toward the rear of gas pass 22. The tubes in each of the wallslie in a common plane and the lower half of these tubes in the run extending from the front wall of the furnace toward the rear wall of gas pass 22 are terminated intermediate furnace 10 and gas pass 22 and are connected with header 51 while the remaining tubes extend on through the gas pass 22 and are connected with header 52. These tubes are in tangent relation so that they effectively form an imperforate wall and each of the walls is supported by bending a number of tubes as shown at 54- to form a loop that extends up through the roof of the furnace and gas passes 20 and 22 and then connecting these looped tube portions with suitable hangers 56 that are supported from structural members that form part of the unit. The region of gas pass 22 below the lower end of the

walls

44 and 46 is effectively partitioned by plate members 58 that in effect, form continuations of the wall.

It is essential that in the region of the vapor heating

heat exchange sections

24, 26, 28 and 30 that the partition means he vapor heating means and not vapor generating means or water heating means. This is necessary in order that the amount of heat absorbed by the partition walls will not be so excessive as to lower the gas temperature to such an extent that the heat imparted to the various vapor heating heat exchange sections will not be enough to produce the desired temperature.

The vapor heating surface that comprises the

walls

44 and 46 is the secondary or low temperature superheater surface of the illustrative organization with steam being received by headers 52 from drum 12 through tubes 60 and with steam issuing from header 49 through conduit 64 to the inlet header of superheater section 24.

Walls

44 and 46 together with side walls of the furnace and the gas passes form the

passageways

66, 68 and 70, each of which has the same type of heat exchange surface disposed therein, i.e., each has a portion of the

superheater sections

24 and 26, a portion of the

reheater sections

28 and 30, and a portion of the

economizer sections

34 and 36. The flow through each of the passageways is independently controlled by dampers 72 which are positioned at the outlet of each passageway and are organized for independent regulation with respect to each passageway. Accordingly the dew through each of the passage ways may be independently regulated as desired whereby, notwithstanding that a substantial temperature variation exists across the gas stream issuing from the lower region of the furnace or a substantial variation in the gas fiow exists theretacross, the heat absorption rate in each of the gas passes may be maintained generally constant, or, in other words, there will be no localized areas of high heat absorption and accordingly high metal temperature. Furthermore since each of the passageways contains the same type of heat exchange surface adjustment of the dampers to independently regulate the fiow through the various passageways will not upset or change the relation of the superheat temperature to the reheat temperature.

With regard to controlling the reheat and superheat temperature over varying load and with respect to each other the unit may be provided with any of the well known control organizations, as, for example, tilting burners, gas recirculation and desuperheating or combinations of these arrangements.

While I have illustrated and described a preferred embodiment of my novel organization, it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

What is claimed is:

1. A high capacity, high pressure vapor generator comprising an elongated furnace having an exit for combustion gases adjacent one end and fired at a region remote from said one end and including meansfor thus firing the same, means forming a convection heat exchange zone extending from the furnace through which combustion gases generated in the furnace pass, said zone having disposed therein only heat exchange sections that are consecutively arranged relative to gas flow with each section extending across the entire width of the stream of gases passing therethrough and with the upstream sections being steam heating sections and downstream sections being water heating sections, and with some of said steam heating sections being superheating sections and the remaining being reheating sections, means dividing the convection heat exchange zone into at least three separate passages continuous in side by side relation across the width of the stream of gases flowing thcrethrough with the ratio of superheat to reheat surface in one of the passages being a predetermined value and with this ratio in the other passages being substantially the same as said one passage and means operative to independently control the gas flow through each of said passages.

2. A high capacity high pressure vapor generator comprising an elongated furnace fired with a suitable fuel and having a combustion gas outlet adjacent one end, means for thus firing the furnace, passageway means extending from said outlet and together with said one end of the furnace forming a heat transfer zone, superheating heat exchange sections and reheating heat exchange sections disposed in said heat transfer zone with each section being comprised of tubes disposed in uniformly spaced relation across the entire width of the zone so the section effectively fills the same and so there are a plurality of consecutively arranged sections with respect to combustion gas flow, wall means comprised at least in part of vapor heating surface and dividing said heat transfer zone into at least three continuous passageways disposed in side by side relation across the width thereof with the ratio of superheat to reheat surface in one of the passageways being a predetermined value and with this ratio in the other passageways being substantially the same as said one passageway and means operative to independently regulate the flow through each passageway.

3. A vapor generator of the type described comprising an upright furnace into the lower region of which fuel is introduced and burned, means for introducing fuel into the furnace a lateral outlet in the upper end of the furnace for combustion gases, at gas pass extending horizontally from said outlet and a vertically disposed gas pass extending down from said horizontal gas pass, the upper region of the furnace and said gas passes forming a heat transfer zone through which the combustion gas stream generated in the furnace passes, a plurality of heat exchange sections disposed in this heat transfer zone with each section being comprised of sinuously bent tubular members and with each section extending the full width of the gas stream, the downstream sections relative to combustion gas flow being water heating surface and the upstream sections including both superheat and reheat sections, generally imperforate vertically disposed wall members dividing said heat transfer zone into at least three side by side passages across the width of the gas stream, each of said wall members including a group of coplanar adjacent tubes sinuously bent to extend horizontally back and forth along the upper end of the vertical gas pass, along the horizontal gas pass and along the upper end of the furnace, a header disposed above the furnace and to which one end of the tubes are connected, a header disposed below the horizontal gas pass to which a portion of the tubes are connected at their other end and a header disposed at the rear of the vertical gas pass to which the remainder of the tubes are connected at their other end, means for conveying steam through the tubes of said wall members, and means operative to adjustably and individually control the flow through the several passages.

4. In a high capacity, high pressure steam generator the combination of an elongated furnace, said furnace being tangentially fired and having a plurality of laterally space-d burners discharging tangent to an imaginary cylinder extending longitudinally of the furnace so that a burning mass is created that whirls generally about the axis of the furnace, said furnace having an outlet for combustion gases adjacent one end and directed laterally of the furnace, passageway means including a portion extending laterally of the furnace from said outlet and a portion extending in parallel relation with the furnace and connected with the laterally extending portion, said passageway having steam heating and water heating surface successively disposed therein in the direction of gas flow with the steam heating surface comprising a number of sections each section being comprised of tubular members disposed in spaced side-by-side relation across the width of the passageway, some of the steam heating sections being connected to initially superheat steam generated by the gcnenator and some being connected to reheat said steam, a plurality of wall members extending from the region of the furnace adjacent the outlet to a location in the passageway downstream of the water heating surface relative to combustion gas flow, with the wall members being in parallel relation and parallel with the direction of combustion gas flow and spaced across the width of the passageway so as to form at least three passages across said width and within which the proportion of supcrhcating to reheating surface is generally the same, the portion of each of the wall members in the end of furnace adjacent said outlet, in the lateral extending portion of the passageway and in the portion of the other passageway portion immediately adjacent the laterally extending portion being comprised of side-by-side sinuously bent tube members connected to receive steam generated by the steam generator, and means operative to individually and adjustable control the combustion gas flow through each of said passages.

5. In a vapor generator operating on the reheat cycle and including a furnace having firing means adjacent one end and a combustion gas outlet remote therefrom, a gas pass extending from said outlet having convection heat exchange surface of various types disposed therein including reheat and superheat, means dividing said gas pass into at least three continuous side-by-side passageways with the ratio of superheat to reheat surface in one of the passageways being a predetermined value and with the ratio in the other passageways being substantially the same as said one passageway, and means operative to contnollably proportion the combustion gas flow through the several passageways.

6. The organization of claim 5 wherein at least the upstream portion; relative to combustion gas flow, of the means dividing the gas pass into several passageways includes wall means comprised of vapor heating tubes.

7. In a vapor generator operating on the reheat cycle, an elongated furnace, means for introducing fuel and air into said furnace from a plurality of laterally spaced locations and tangent to an imaginary cylinder longitudinally disposed and centrally arranged with respect to the furnace so as to create a rotating mass of burning fuel rotating about the central axis of the furnace, said furnace having an outlet in a side wall thereof remote from the region of firing, a gas pass extending from said outlet and having disposed therein both convection reheating and convection superheating surface, means dividing said gas pass into at least three continuous passageways with the ratio of superheat to reheat surface in one of the passageways being a predetermined value and with this ratio in the other passageways being substantially the same as said one passageway, and means operative to independently control the combustion gas flow through the several passageways.

8. A vapor generator operating on the reheat cycle and having a furnace through which combustion gases are conveyed with an outlet being provided therefor, a gas pass extending from said outlet to receive said gases and having both superheater and reheater surface disposed therein, means dividing said gas pass into a plurality of continuous side-by-side passageways each of which contains superheater and reheater surface with the ratio of superheat to reheat surface in one of the passageways being a predetermined value and with this ratio in the other passageways being substantially the same as said one passageway so that varying the proportioning of the combustion gas flow between the several passageways does not appreciably affect the relative temperature of the superheat and reheat vapor, and means operative to independently control the flow through each passageway.

9. A vapor generator operating on the reheat cycle and comprising a furnace having suitable firing means and a combustion gas outlet, at gas pass extending from said outlet, heat exchange surface in at least the upstream portion of said gas pass including a heat exchange section for initially heating vapor produced by the generator and a heat exchange section for reheating the vapor after a portion of its energy has been utilized, each of these heat exchange sections being comprised of tubes disposed in planes uniformly spaced across the entire width of the gas pass, means dividing the gas pass in the zone of these heat exchange sections into a plurality of separate continuous side-by-side passageways across the width thereof with the ratio of superheat to reheat surface in one of the passageways being a predetermined value and with this ratio in the other passageways being substantially the same as said one passageway and means operative to controllably proportion the combustion gas flow between the several passageways.

10. A vapor generator operating on the reheat cycle and comprising an elongated furnace, said furnace being tangentially fired and having a plurality of laterally spaced burners discharging tangent to an imaginary cylinder extending longitudinally of the furnace so that a burning mass is created that whirls generally about the axis of the furnace, said furnace having an outlet for combustion gases remote from the region of firing and directed laterally of the furnace, at gas pass extending from said outlet, heat exchange surface in at least the upstream portion of said gas pass including a heat exchange section for initially heating vapor produced by the generator and a heat exchange section for reheating the vapor after a portion of its energy has been utilized, each of these heat exchange sections being comprised of tubes disposed in planes uniformly spaced across the entire width of the gas pass, means dividing the gas pass in the zone of these heat exchange sections into at least three separate continuous side-by-side passageways across the width thereof with the ratio of superheat to reheat surface in one of the passageways being a predetermined value and with this ratio in the other passageways being substantially the same as said one passageway and means operative to controllably proportion the combustion gas flow between the several passageways.

11. A vapor generator including an elongated furnace means for introducing fuel thereinto for burning therewithin, said furnace having an outlet adjacent one end and extending laterally therefrom, a passageway extending from said outlet for the conduction of combustion gases, a plurality of division walls disposed in spaced relation across the passageway and the region of the furnace opposite said outlet and dividing the passageway and the region of the furnace opposite said outlet into at least three parallel passages for combustion gases and which passages are disposed in side-by-ide relation across the Width of the passageway and said furnace portion, the upstream portion of the division walls being comprised of a vapor heating surface, heat exchange surface disposed in each of the passages including superheating surface and reheating surface with the ratio of superheat to reheat surface in one of the passages being a predetermined value and with this ratio in the other passages being substantially the same as said one passage, and means operative to individually and adjustably control the gas flow through the several passages.

References Cited in the file of this patent UNITED STATES PATENTS 2,107,440 Gordon Feb. 8, 1938 2,268,776 Pourchot Jan. 6, 1942 2,752,899 Kasak July 3, 1956 2,836,156 Schaap May 27, 1958 2,931,345 Raynor et al Apr. 5, 1960 2,977,937 Dietlhauser Apr. 4, 1961 FOREIGN PATENTS 744,797 reat Britain Feb. 15, 1956

Claims

1. A HIGH CAPACITY, HIGH PRESSURE VAPOR GENERATOR COMPRISING AN ELONGATED FURNACE HAVING AN EXIT FOR COMBUSTION GASES ADJACENT ONE END AND FIRED AT A REGION REMOTE FROM SAID ONE END AND INCLUDING MEANS FOR THUS FIRING THE SAME, MEANS FORMING A CONVECTION HEAT EXCHANGE ZONE EXTENDING FROM THE FURNACE THROUGH WHICH COMBUSTION GASES GENERATED IN THE FURNACE PASS, SAID ZONE HAVING DISPOSED THEREIN ONLY HEAT EXCHANGE SECTIONS THAT ARE CONSECUTIVELY ARRANGED RELATIVE TO GAS FLOW WITH EACH SECTION EXTENDING ACROSS THE ENTIRE WIDTH OF THE STREAM OF GASES PASSING THERETHROUGH AND WITH THE UPSTREAM SECTIONS BEING STEAM HEATING SECTION AND DOWNSTREAM SECTIONS BEING WATER HEATING SECTIONS, AND WITH SOME OF SAID STEAM HEATING SECTIONS BEING SUPERHEATING SECTIONS AND THE REMAINING BEING REHEATING SECTIONS, MEANS DIVIDING THE CONVECTION HEAT EXCHANGE ZONE INTO AT LEAST THREE SEPARATE PASSAGES CONTINUOUS IN SIDE BY SIDE RELATION ACROSS THE WIDTH OF THE STREAM OF GASES FLOWING THERETHROUGH WITH THE RATIO OF SUPERHEAT TO REHEAT SURFACE IN ONE OF THE PASSAGES BEING A PREDETERMINED VALUE AND WITH THIS RATIO IN THE OTHER PASSAGES BEING SUBSTANTIALLY THE SAME AS SAID ONE PASSAGE AND MEANS OPERATIVE TO INDEPENDENTLY CONTROL THE GAS FLOW THROUGH EACH OF SAID PASSAGES.