US2285442A - Vapor generator - Google Patents

Description

June 9, 1942.

VAPOR GENERATOR Filed Sept. 22, 1958 4 Sheets-Sheet l Fig 1 ATTORNEY.

Howard Jfferr H. J. KERR 2,285,442

INVENTOR.

June 9,1942, H, J, KERR 2,285,442

VAPOR GENERATOR Filed Sept. 22, 1938 4 Sheets-Sheet 2 36 H m Firsifuper/zmier INVENTOR.

: 1 fz owczmJKerr ATTORNEY.

June 9, 1942. H. J. KERR VAPOR GENERATOR Filed Sept. 22, 1938 f} I 4 Sheets-Sheet 3 4 Fa n... 2M;

a s u U 1 is 5 4 INVEM'OR.

Howard Jfferr' Rmm June 9, 1942.

H. J. KERR 2,285,442 7' VAPOR GENERATOR Filed Sept. 22, 1958 -4 Sheets-Sheet 4 INVENTOR.

Howard J Kerr I ATTORNEY.

- values to 950 .and it will also vary Patented June 9, 1942- Howard J. Babcock Kerr, Westiield, N. J., assignor to The & Wilcox Company, Newark, N. 3., a

corporation of New Jersey Application September 22, 1938, Serial No. 231,124 9 Claims. 1 (Cl. 122-235) This invention relates to vapor generators. In the generation of power by steam plants,

' the operating conditions of boilers as to. steam pressure, steam temperature or superheat, feed water temperature, vary widely as do also the hourly steam generating and quality or kind of fuel. At the present time, pressures from low up to more than 2000 lb. per sq. inch are being used, and steam temperatures from saturation F. or more, while the temperature of water entering the boiler unit mayrange from value down to relatively low With such wide ranges of operating conditions, there is a corresponding range for the fraction of heat absorbed per pound of steam to heat the water to saturation temperature, evaporate the water at this temperature and to in spite of recognition of the fact that this practice increases the cost, and makes it impossible change a given boiler to meet new operating conditions imposed on it, as to fuel, per cent of heat absorbed in water heating, steam generation, and superheating and as to temperature of superheatedsteam.

With any one. boiler arrangement selected to meet given operating conditions, the results normally vary with load in such a way as to make it'necessary to add special control or adjustment features as corrective measures. Steam temperature is one result that varies with load, with the degree of slagging of heating surface, in addition to the rise of superheater metal temperature that takes place in starting when there is no steam flow, or when there is a sudden decrease in load; or a maladjustment of combustion conditions. The temheat liberation furnace.

An object of my invention is to provide a boiler; in which such operating conditions-may;

original distribution of its tube heatmg surface, and in which this disposal may be be met by altered later on to meet new operating-conditrouble and expense, and in which for any given heating surface distribution, the desired operating results may be face, changes of fuel, or changes in feed water temperature.

My boiler is characterized by a multiplicity in any one of various satisfactory ways, selected with reference to the effects When the same sort of fluid cooled walls is used for the main and for the auxiliary furnaces, the former will be hotter than the latter for the same volumetric be hotter than the gases leaving the auxiliary The relative meantemperatures of the main and furnace and all auxiliary beyond their respective gas exits, and flow as one stream in a flue toward the stack.

In all cases steam generating tubes are located in the walls of the main furnaceand across the path of gases leaving the main furnace. Also,

may be bare or covered superheat can be held to 7 control of combustion in the auxiliary furnace in and superheat requiring a in all cases, water heating or economizer tubes" are located in the fiue conducting the mixed gases from all furnaces toward the stack, and at least part of these tubes are arranged for water flow counter-current to the mixed gas now. Also in all cases superheater tubes are located in the path of gases leaving one or more of the auxiliary furnaces, or in their walls, or both. All of these tubes are called primary tubes and they are supplemented by other sets called secondary tubes. 7

Secondary steam gene ating tubes may be located so as to receive heat from the fuel burned in any of the auxiliary furnaces, secondary economizer tubes may be located so as to receive heat from the fuel burned in the main or any of the auxiliary furnaces, and secondary superheater tubes may be located so a to receive heat from the fuel burned in the main or in any of the other'auxiliary furnaces, according to the major operating requirement to be met. When the major operating requirement is changed by circumstances, this distribution of such secondary tubes may be changed without changing the location and distribution of the primary tubes and without changes in the general structure of the boiler, except that the burners and the covering of wall tubes may also be changed.

Accordingly, my boiler comprises, a main furnace and at least one auxiliary furnace, with fluid cooling of the walls, a common fiue leading gases to the stack, and tube surface divided into primary and secondary, the primary tube surface including steamgenerating tubes receiving heat from fuel burned in'the main furnace, economizer tubes in the common flue receiving heat from the gases from all furnaces, and superheater tubes receiving heat from the fuel burned in an auxiliary furnace. The remaining surfaces being considered as forming the whole L secondary surface.

In the operation of the illustrative installation the rate of steam generation is controlled solely by the rate of burning fuel in the main furnace and the superheat or steam temperature is controlled solely by the rate of burning fuel in an auxiliary furnace, the heat absorption in the economizer being the result of the operation ofa plurality of furnaces and t tubes between them and the economizer. For a given rate of steam generation, or load, the any desired value by he heat absorbed by spite of variations of* dirtiness or slagging of the tubes, and also be maintained in spite of change of load. Steam can be raised from cold without damage to the superheater by deferring the operationof the auxiliary furnace. As shown, both furnaces are fired by pulverized coal for dry ash removal from a common collecting chamber, but

the auxiliary furnace will normally be colder than the main furnace, and for this reason the main furnace'may be made hot enoughfor wet or molten ash removal while the auxiliary remains cold enough for dry ash removal.

For different operating conditions of pressure relatively larger amount of .heat of superheat, and a smaller amount of heat of vaporization, some of the steamgenerating tubes maybe omitted and secondary superheater tubes installed in their place.

Also if ,the steam turbine receiving the boiler output of high pressure steam is to be operated in two stages with reheat of steam between them, a second auxiliary furnace may be added to provide the heat and independently control the temperature of the low pressure steam.

It is to be understood that, while the steam generating tubes are shown to be in natural circulation relationship to the boiler drum, this is not a limitation, and forced circulation arrangements including the once through type may replace naturalcirculation within the scope of my invention.

Objects of my invention, other than those indicated above, will appear as the description proceeds.

The invention will be described with reference to the accompanying drawings in which a preferred embodiment of the invention is disclosed.

In the drawings:

Fig. 1 is a vertical section through a part of a steam generating installation constructed in accordance with the teachings of the invention. This view is taken on the section line L4, as it is indicated in Fig. 2;

Fig. 2 is a vertical section taken at right angles to the section plane of Fig. 1. It is taken on the section line 2-2 of Fig. 1;

Fig. 3 is a horizontal section line 3-3 of Fig. 2;

Fig. 4 is another horizontal section taken through the main and auxiliary furnaces on the plane indicated by the section line 4-4 of Fig. 2;

Fig. 5 is a detail view indicating a horizontal section of a furnace wall which may be employed in some parts of the installation;

Fig. 6 is a detail view illustrating a modified form of the furnace wall in horizontal section;

Fig. '7 is a horizontal section of a furnace wall construction which may be employed in parts of the installation;

Fig. 8 is a vertical section taken on the section line 88 of Fig. 2; and

Fig. 9 is a fragmentary view of the reheat'er wall tubes indicating welds to secure these sinuous tubes together at their inter-sections.

Fig. 2 of the drawings indicates a construction in which there are three furnaces. The main furnace I0 is fired in accordance with the demand for steam, its gases passing directly upwardly from the furnace across a bankof steam generating tubes l2.

The main furnace is flanked on either side by auxiliary furnaces I4 and "5. Each of these furnaces is independently fired, the combustion gases from the furnace l4 passing through an outlet l8 and joining the gases of the main furnace at a position beyond the bank of steam generating tubes. auxiliary furnace l6 likewise pass through an outlet 20 and join the gases of the main furnace section taken 'on the I at a similar position.

In the furnaces I4 and Hi there are types of auxiliary heating equipment which require degrees of' heating varying from the heating required by the main furnace III which is governed by steam demand.

As indicated in Fig. 2 of the drawings, the auxiliary heating equipment subject only to'the heat of the furnace I6 is a superheater having return bend tube coils 22 extending across the path of the furnace gases at a position beneath the furnace gas outlet 20. These coils receive steam from the boiler steam and water drum 24 through the agency of'saturated steam supply tubes 26 which have connections 28 leading to the steam space of the drum. These tubes are connected at their other ends to the super- The gases from the other heater inlet header 30 to which the coils 22 are connected, as shown.

From the coils 22 steam flows tubes 32 agency utilizing the steam.

The superheater furnace I6, being independently fired by burners similar to the burner '44 shown in Fig. 1 of the drawings, may be operated to control the final temperature or superheat of and in this case the burner for the auxiliary furnace I6 is operated at a very low rating.

The auxiliary heater subject only to the heat of the auxiliary furnace -I4 is a reheateruseful in connection with the operation of a multiple stage steam turbine receiving steam from the superheater header 42. In this case, the steam exhausted from one stage of the turbine is reheated and then used in another stage.

The steam to be header '50 and capable of being independently fired solely from requirements of the auxiliary heater which is subject only to the heat of that furnace. I

The furnaces I and I6 are separated by wall tubes connected into boiler circulation in a suitable manner. The tubes 10 are connected to the header I2 and at their The tubes 86 are connected at their lower ends to the header 92 which may have direct connection with the water space. of the drum 24.

-To form the furnace gas outlet at the top of the auxiliary furnace I6 successive tubes III are bent out of their normal plane, as indicated, and the furnace gas outlet I 8 for the auxiliary spaces between the tubes. At a still higher level and between the top of the furnace) and the furnaces I4 and I6 the tubes 10 and 80 may be enclosed by refractory elements as indicated in Fig. 5 of the drawings. These refractory elements are shown as the C-tile I00.

Fig. 3 of the drawings shows three of the burners 44 for the main furnace I0, an independently fired burner I02 for the furnace I 4,

I connected into the boiler circulation.

at their upper ends with the header Fig. 1 also shows the wall I 2II'of the three furnaces as defined by wall tubes I22 connected I24 and at their lower ends with the header I 26. The op- The upper ends of the steam generating tubes extending across the outlet of the main furnace III are connected to a header construction I from which risers I52 extend past the flue I54 and along the roof I56 to the steam space of the drum 24 the economizer outlet header I 68.

Referring again indicated in Fig. 2

of the drawings, it will be seen that the three furnaces I0, I 3, and I6'com- 3 furnace It is similarly formed at the opposite. side of the installation.

At the lowermost levels in tubes 80 A header construction I60 is in to the furnace construction crating tubes positioned so as to be exposed to the heat of the middle furnace chamber between said walls,a reheater subject'to the heat of one of the remaining furnace chambers, and a superheater subject to the heat of a third furnace burners for said chambers being independently operated from the standpoint of steam demand, reheat requirements, and superheat requirements, respectively.

2. In a steam boiler, fluid conducting tubes defining the walls right tubes connected into the boiler circulation and arranged as walls extending into said combustion space and dividing it into three furnace chambers, steam generating so as to be exposed to the heat of the middle furnace chamber between said walls, a reheater subject to the heat of one of the remaining fur- .nace chambers, a superheater subject to the heat of the third furnace chamber, and independently operable fuel burning means firing the middle furnace in accordance with steam demands while the second and third furnaces have similarly operable fuel burning means firing them to meet the requirements of reheating and superheating respectively.

3. In a steam boiler, a plurality of adjacent furnaces, rowsof water tubes extending across the'outlet of one of said furnaces and connected .into the boiler circulation, and a superheater disposed beyond said tubes relative to gas flow, wall defining water cooled tubes between said furnaces, a steam reheater directly heated by the second of said furnaces, means for firing said first mentioned furnace, and means for independently firing to effect reheat control, extensions of said wall defining tubes being disposed at a position beyond said reheater and extending across the path,

of the gases passing from the second furnace. 4. In asteam boiler, a plurality of adjacent furnaces, rows, of water tubes extending across the outlet of one of said furnaces and connected into the boiler circulation, and a superheater disposed beyond said tubes relative to gas flow, wall defining water cooled tubes between said furnaces, a steam reheater of the radiant type directly heated by the second of said furnaces,

means for firing said first mentioned furnace,

and means for independently firing the second of said furnaces to effect reheat control, extensions of said wall defining tubes being disposed at a position beyond said reheater and across the path of the gases passing from the second furnace.

5. In a steam boiler, a plurality of directly laterally adjacent said similarly constructed furnaces, a bank of water tubes extending across the outlet of one of said furnaces and connected into the boiler circulation, a first superheater section including tubes disposed in a gas pass beyond said bank of tubes, anda partition wall separating said one furnace from a second of said furnaces and including water cooled tubes connected into the boiler circulation, all of said partition wall tubes receiving heat from a plurality of furnaces, a second superheater section heated only by the gases passing from said second furnace, means for connecting said superheater sections in series as to steam flow, means for firing said first mentioned furnace, and means for independently firing the second of said furnaces to effect superheat control.

6. In a water tube steam boiler installation, a

tubes positioned the second of said furnaces plurality of heated by the gases laterally adjacent furnaces of similar construction, imilarly arranged means for independently firing the separate furnaces, a bank of convection tubes heated directly from one of said furnaces, a superheater section subject to the heat of the gases of said one furnace at a position beyond said bank of tubes, and a second superheater section subject to the heat of a second of said furnaces and connected to the first superheater section for series flow of steam therethrough, the second furnace having its gases joining those from the first furnace at a position rearwardly of the first superheater section, the

second furnace being fired primarily from the standpoint of superheat requirements so as to effect superheat control.

7. In a water tube steam boiler installation a and arranged as a wall separating said furnaces,

pulverized fuel burners similarly arranged with respect to said furnaces and firing them with downward projection of fuel into the furnaces, a first superheater including tubes heated by the gases rising in one of the furnaces, a second superheater connected to the first superheater for a series flow of steam therethrough and heated by the gases from a second of said furnaces, a reheater heated by the gases rising from a third of said furnaces, and means including convection heat absorbing surfaces positioned in a gas pass leading from a superheater gas outlet and the reheater gas outlet, said water cooled v I partition tubes having upper parts extending to a position beyond a superheater relative to gas flow. l

8. In a water tube steamboiler installation a plurality of adjoining similar furnaces, water tubes connected into the boiler-circulation and arranged as a wall separating said furnaces, pulverized fuel burners similarly arranged with respect to said furnaces and firing them with downward projection of fuel into the furnaces, a first superheater including tubes heated by the gases rising in one of the furnaces, a second superheater connected to the first superheater for a series flow of steam therethrough and from a second of said furnaces, and means providing convection heat absorbing surfaces positioned in a gas pass leading from a superheater, said water cooled partition tubes having upper parts extending to a. position beyond a superheater relative to gas flow so ,that gases of the superheater pass between said upper parts,

9. In a steam boiler, a plurality of adjacent furnaces, steam generating 4 across the outlet of one of said furnaces and connected into the boiler circulation, and a superheater disposed beyond said tubes relative to gas flow, wall defining water cooled tubes between said furnaces, a steam reheater directly heated by the second of said furnaces, means forfiring said first mentioned furnace, means for independently firing the second of said furnaces to effect reheat control, extensions of said wall defining tubes-being disposed across the path of the gases from the second furnace at a position beyond said reheater, means providing a single gas pass or flue beyond said furnaces, and means heating surface in said gas pass, the gases from said furnaces joining at a position forwardly of said surface.

HOWARD J. KERR.

tubes extending CERTIFICATE OF CORRECTION.

Patent No. 2,28 ,1m2. June 9, 191g.

of the above numbered patent requiring correction as follows; .Page h, first column, line'5 7, claim 5, for "said" read "and"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 15th day of April, A. D. 19b5,.

- Henry Van Arsdele, (Seal) Acting Commissioner of Patents

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