US2358785A

US2358785A - Steam generator

Info

Publication number: US2358785A
Application number: US206737A
Authority: US
Inventors: Blizard John
Original assignee: Foster Wheeler Inc
Current assignee: Foster Wheeler Inc
Priority date: 1938-05-09
Filing date: 1938-05-09
Publication date: 1944-09-26
Anticipated expiration: 1961-09-26

Description

J. BLIZARD STEAM GENERATOR Filed y 1938 Q Q Q 3 heets-Sheet 1 INVENTOR JOHN BL/ZA/PD ATTORNEY 1 Sept. 26, 1944. BUZARD 7 2,358,785

STEAM GENERATOR Filed May 9, 1938 3 Sheets-Sheet 2 INVENTOR f0f/A/ 54 /Z/4 73 ATTORNEY Patented Sept. 26,

' UNITED STATES PATENT OFFICE STEAM GENERATOR Application May 9, 193a, Serial No. 206,737

Claims.

' and efliciently produce saturated steam and simultaneously to produce superheated steam at all ratings of the steam generating section and at the desired degrees of superheat up to maxi-' mum superheat at all ratings. The arrangements are extremely compact and they are particularly well adapted to marine installations but they are also well adapted to land installations of every description.

This application is a continuation-in-part of my application Serial No. 35,279, filed August 8, 1935.

The nature of the invention, its several features and advantages, will be understood from the following description when considered in connection with the accompanying drawings, forming a part thereof, and in which:

Fig. l is a more or less diagrammatic illustration. in partial vertical section, of a steam generator marine installation embodying the invention;

Fig. 2 is a sectional view taken on line 2-2 of Fig. 1;

Fig. 3 is a vertical sectional view through an air casing at the front of a steam generating section embodying the invention;

Fig. 4 is a horizontal sectional view on line t-l of Fig. 3, and

Fig. 5 is a sectional view showing the operating means for the dampers disclosed in Figs. 3 and 4.

Like characters of reference refer to the same or to similar parts throughout the several views.

Referring to Figs. 1 and 2 of the drawings, reference character l0 designates the hull of a ship having a deck I I. In the particular arrangement illustrated in Fig. l, two'generating units are disposed transversely of the longitudinal axis of the ship and back to back. Any number of pairs of such units may be utilized in a ship or any number of single units may be used in either a marine or stationary environment. The steam generating unit includes a setting l2 having asteam and water drum IS in the upper part of the setting, and two spaced water drums II and ii in the lower part of the setting. A main bank of steam generating tubes 16, which may for convenience but without limiting effect he referred to as a first bank, connects the drums I 3 and I5, and a bank, or screen, of suitable spaced steam. generating tubes I! which may be referred to without limiting effect as a second bank connects the drums l3 and H. The tubes of the bank I! may be arranged as shown in Figs. 1 and 2 in a plurality of parallel rows with the tubes of one row staggered with respect to the tubes of an adjacent row, or the bank I! may consist of but a single row of tubes in some instances. The banks of tubes I6 and I1 and the lower and side walls of the setting I! form a boiler or saturated steam furnace chamber l8 which is fired by a plurality of fluid burners l9 which may burn pulverized fuel, gas or oil or a combination of such fuels, to provide a stream or a plurality of streams of products of combustion in the furnace chamber. In the arrangement shown, the burners I! are disposed in a side wall of the setting and fire substantially parallel to the axes of the boiler drums. These burners may be disposed in any other convenient location. In some instances a single burner l9 may sufllce.

A superheater furnace 20 in the setting I2 is defined by the tubes II, the front, side and upper walls of the setting and the drum I3. A superheater is disposed in the furnace 20 and in the form shown in Fig. 1 consists essentially of headers 2|. and 22 supported on the setting, and a plurality of loop tubes 23 connecting these headers, th tubes being arranged in a single row and being disposed along the front and upper walls of the setting, adjacent the drum I3 and adjacent the tubes 11. It will be understood that the superheater tubes may be arranged in a plurality of spaced, parallel rows if desired, with the tubes of one row staggered or in line with the tubes of an adjacent row. Any other type or form of superheater with the tubes thereof suitably placed may be ;used in lieu of the form disclosed in Fig. 1. A steamline 24 connects the upper portion of the steam and water drum It with the superheater inlet header 2|. The superheater furnace 20 is fired by a plurality of fluid burners 25 which are disposed, as shown, in the same side wall of the setting as the burners I9. In some instances a single burner 25 may suflice. A gas outlet 26 extends from the rear of the setting adjacent the rear wall 21 and connects with a stack 28. In the form shown, the gas outlet is not controlled by dampers or the like. An economizer 29 or other heat recovery device, is disposed in the fiue 20 but may be omitted, if desired.

During operation of the form of generator heretofore described, if a low degree of superheat only is desired, one or more of the burners l9 are fired and the burners 25 are not operated. The one or more streams of products of combustion or I l I gases so produced flow through the furnace l8 and over the tubes l and out through flue 25 over the economizer 23 to the stack 28. Some of the gases also flow over or in contact with the tubes I1 and a comparatively small quantity of these gases will pass over those portions of the superheater tubes which are disposed adjacent the tubes I1, and since comparatively little of the heat radiated from the gases reaches the superheater tubes, the steam passing through the superheater will be superheated only to a small extent. On the other hand, if a high degree of superheat at low loads is required, one or more burners 25 is or are operated and the burners l3 are not operated. Under these circumstances, the gases so produced will flow through the superheater furnace 20, over the portions of the superheater tubes adjacent the bank l1, over the tubes ll, through furnace l8, over the tubes l5 and out through flue 25 and stack 28. In other words, all the gases produced in the superheater furnace flow over all the steam generating tubes and give up heat to produce saturated steam. For other operating conditions, both the boiler and superheater furnaces l8 and 20 respectively, may be fired at the same time and the number of burners l9 and burners 25 in operation at any time as well as the intensity with which the burners are fired will depend upon the load on the generator and the required degree of superheat of the steam. Saturated steam may be withdrawn through outlet connection 30.

Figs. 3 and 4 illustrate an arrangement for separately controlling the supply of air to the burners l9 and 25 which fire the boiler furnace and the superheater furnace respectively. It is well known that the rate at which heat is given up to heating surface exposed to the radiation of a flame increases as the rate of firing increases and decreases as the ratio of airto fuel increases. This principleis employed in the arrangements shown in Figs. 3 and 4 with a steam generator embodying the invention, to vary the degree of superheat. In the arrangement disclosed, the setting 3| has its four vertical walls surrounded by a wind box 33. Air under pressure is introduced into the wind box at the rear of the setting and flows throughout the wind box to the part thereof which is disposed outside of the front wall 34 ofthe setting in which the burners l9 and 25 are located. In the form shown, downcomers 35 connect the upper drum l3 and the lower drum l4 and downcomers 36 connect the upper drum and the lower drum l5.

- These downcomers are disposed in the wind box 32 so that they are in a temperature zone which is considerably lower than that of the boiler and superheater furnace; As shown, the number of downcomer tubes connecting the drums l3 and I4 are greater than the number connecting the drums l3 and I5, but the number of downcomers in each group may be varied to obtain the results desired. It will be understood. however, that the use of the downcomers heretofore mentioned is not essential to the operation of the generator, and that they may be omitted if desired. The group of burners I9 for firing the boiler furnace is surrounded by a metallic casing or closure 31 which extends between the front wall 34 of setting 3| and the casing 33. A similar enclosure or metallic casing 38 surrounds the superheater burners 25. Each

casing

31 and 38 is provided with a plurality of openings each of which is controlled by a damper 39. The casing 31 is provided with an opening in each of the five sides thereof, whereas the casing 38 is provided with similar air openings in only three sides thereof, but if the constructional arrangement permits, there may be damper controlled openings in each of the sides thereof.

One of the dampers 39 and the operating means therefor is shown in greater detail in Fig. 5 of the drawings. The damper 39 is mounted at both ends so as to swing or oscillate about its longitudinal axis and to engage the

spaced stops

40 and 4| when it is in closed position. A lug 42 having spaced upstanding ears 43 between which extends a pin 44 is fixed to one face of the damper 39 in a position midway of the ends of the damper but with pin 44 at one side of the longitudinal axis thereof as clearly shown in Fig. 5. A bolt 45 has a head 46 on one end with a slot 41 through which passes the pin 44. The other end portion 48 of the bolt is threaded and carries a nut 49 fixed to the operating hand wheel 50. Nut 49 is held in position by split cap 5| which is bolted to flanged sleeve 52 which in turn is secured to the casing 33 of the wind box. A stop collar 53 is carried on bolt 45 in such fixed position that it engages the inner end of sleeve 52 when the damper is in fully opened position as indicated in dotted lines in Fig. 5. The outer end of the bolt- 45 carries a pin 54 which moves in a slot in a sleeve 55 to indicate the position of the damper. The sleeve 55 adjacent the slot may be calibrated to indicate the degree to which the damper is opened or closed. Damper operating means other than that disclosed may be utilized if desired. With this or an equivalent arrangement, the amount of air supplied to the burners l9 and 25 may be separately controlled and regulated as desired to obtain the combustion conditions required. In this manner, the degree of superheat may be readily controlled by operation of .the dampers without changing the rate of supply of fuel to the burners in either of the furnaces. For example, if air is supplied to the burners in both furnaces at a. constant pressure and it is desired to raise the superheat without varying the relative rate of supply of fuel to the burners or to the furnaces, this may be accomplished by partially closing the dampers which control the supply of air to the burners for the superheater furnace which will increase the temperature in the superheater furnace and thus result in an increase in the superheat. Or, if both furnaces are running with all dampers wide open and a lower degree of superheat is -desired, the dampers surrounding the burners is are partially closed thus increasing the air pressure in the wind box 33, more air is supplied to the superheater furnace, and the superheat is lowered. Conversely, if a higher superheat is desired, the dampers surrounding the superheater furnace burners 25 are partially closed, less air is supplied to the superheater burners and the superheat is raised.

In marine installations, when closed stokeholds are used, a wind box or the equivalent need not be employed. In such instances the supply of air to the burners l9 and 25 may be controlled by enclosing the burners similarly to the manner described with one or more dampers to control the supply of air into the enclosure and thence to the burners.

With the arrangement herein disclosed, it will be percelyed that anextremely compact steam generating and superheating unit has been provided which possesses great flexibility of control of the production of superheated steam of the desired degree of superheat at all rates of steaming. Great economy and emciency are provided due to the flow over the steam generating elements of the unit of all products of combustion generated in the superheater furnace.

Although a preferred form of the invention has been disclosed, the principles of the inven' tion may be embodied in other forms of generat' ing and superheating units.

Various changes may be made in the forms of the several parts or features of the generators herein disclosed, and in their relative location and arrangement without departing from the principles of the invention. Accordingly, the invention is not to be limited excepting by the scope of the appended claims.

What is claimed is:

1. A vapor generator comprising a setting, vapor generating tubes in the setting, a boiler furnace in the setting, fuel burner means for firing the boiler furnace, a superheater in the setting outside of the boiler furnace, separate fuel burner means for firing the superheater, means for separately supplying fuel and air to the superheater firing means, a gas outlet for the setting so located that the gases produced in the superheater furnace flow into the boiler furnace and over the vapor generating tubes prior to flowing into, the gas outlet, means for varying the quantity of air supplied to the superheater firing means while maintaining substantially constant the quantity of fuel supplied thereto to control the degree to which the vapor is superheated, and means for varying the quantity of air supplied to the boiler furnace burner means.

2. A vapor generator comprising a. setting, vapor generating tubes in the setting, a boiler furnace in the setting, one or more burners for firing the boiler furnace, a superheater in the setting outside of the boiler furnace, one or more burners for firing the superheater, means for separately supplying fuel and air to said burners, a gas outlet for the setting so located that the gases produced in the superheater furnace flow into the boiler furnace and over the vapor generating tubes prior to flowing into the gas outlet, means for separately enclosing the one or more burners for firing the furnace and the one or more burners for firing the superheater to prevent access of air thereto, and means for separately controlling said enclosures to vary the quantity of air supplied to said burners, the arrangement being such that the degree to which the vapor is superheated is varied by varying the quantity of air supplied to the burners for firing the superheater while maintaining substantially constant the quantity of fuel supplied thereto.

3. A vapor generator comprising a setting, vapor generating tubes in the setting, a boiler furnace in the setting, one or more burners for firing the boiler furnace, a superheater in the opening in each casing through which air is Supplied to the burners therein, and a damper for controlling each opening to thereby control the quantity of air supplied to said burners, the arrangement being such that the degree to which the vapor is superheated is varied by varying the quantity of air supplied to the burners for firing the superheater while maintaining substantially constant the quantity of fuel supplied thereto.-

4. A vapor generator comprising a setting, vapor generating tubes in the setting, a boiler furnace in the setting, one or more burners for firing the boiler fumace; a superheater in the setting outside of the boiler furnace, one or more burners for firing the superheater, means for supplying fuel to said burners, a gas outlet for the setting so located that the gases produced in the superheater furnace flow into the boiler furnace and over the vapor generating tubes prior to flowing into the gas outlet, an air casing outside at least one wall thereof, an enclosure in the air casing for enclosing the one or more. burners for firing said furnace, an enclosure in the air casing for enclosing the one or more burners for firing the superheater, each enclosure having one or more openings therein through which air from the casing enters the enclosure for the burners therein, and a damper for controlling each of said openings to vary the quantity of air supplied to each enclosure and the one or more burners therein, the arrangement being such that the degree to which the vapor is superheated is varied by varying the quantity of air supplied to the burners for firing the superheater while maintaining substantially constant the quantity of fuel supplied thereto.

5. The method of generating and superheating vapor which comprises passing liquid through a vapor generating zone, supplying fuel and air to a combustion zone for the vapor generating zone, passing vapor from the vapor generating zone through a superheating zone, suppling fuel and air to a superheater combustion zone, causing the gases produced in the superheater combustion zone to flow into the combustion zone prior to flowing through the vapor generating zone, controlling the degree to which the vapor is superheated by varying the quantity of air supplied to the superheater combustion zone while maintaining substantially constant the quantity of fuel supplied thereto, and controlling the quantity of air supplied to the combustion zone for the vapor generating zone.

JOHN BLIZARD.