US2156610A - Boiler - Google Patents

Description

y 1939- J. M. SHI MER 2,156,610

I BOILER Filed Nov. 16, 1936 4 Sheets-Sheet l 4 INVENTOR Q ATTO I? N EY'S y 2, 1939- J. M. SHIMER 2,156,610

BOILER 'Fi led Nov. 16, 1936 4 Sheets-Sheet 2 INVENTOR 24 QfOH/V MJH/ME/P.

ATTO RN EYS BOILER Filed Nov. 16, 1936. 4 Sheets-Sheet s INVENTOR Jo H/V MSH/MER. BY

ATTO R N EYS Patented May 2, 1939 PATENT Torrie];

BOILER John M. Shimer, Dallas, Tex., assignor to Oil Well Supply Company, Dallas, Tex., a corporation of New Jersey Application November 16, 1936, Serial No. 111,149

Claims.

My invention relates to a fire tube boiler of the locomotive type, particularly to a boiler for use in the drilling of petroleum wells and other uses where a portable boiler is required or one that may be moved from one location to another.

Boilers heretofore used in oil field Work have been of the locomotive type without insulation against loss of heat. Consequently the loss of heat by radiation is high, increasing with the area of boiler wall. A length is reached at which the amount of heat absorbed by the boiler water from the combustion gases does not very greatly exceed that lost by radiation from the boiler surface required to recover this heat. The boilers have therefore been generally arranged to provide an exhaust gas temperature of about 750 F. in normal operation.

In my invention a more efficient use of the heat of the boiler flue gases is obtained by providing shorter length of boiler so that a smaller heat radiating boiler surface is provided and in using the higher temperatures of the flue gases resulting from this shortening in superheating' steam from the boiler. For example, instead of having an exhaust flue gas. temperature of 750, the temperatures from the fire tubes of the boiler in my invention may be from 1000 to 1200 F. and the heat of these hotter gases is then absorbed in superheater tubes supplied with steam' from the boiler and with which the hot flue gases are brought into contact before passing to the exhaust stack. Inasmuch as the use of steam is generally variable and to avoid overheating the superheater tubes at times of low steam consmnption, by-pass exhausts are provided for the flue gases-so arranged that when the temperature .of the superheated steam rises beyond certain limits the flue gases are lay-passed direct to the exhaust stack or partly by-passed instead of through thesuperheater. This arrangement also tends to insure a supply of superheated steam at approximately constant temperature. For convenience in cleaning the fire tubes of the boiler the superheater is made detachable so that it may beremoved from the smoke box of the boiler as a unit giving free access to the ends of the fire tubes. A cover may be bolted to the end of the smoke box on removal of the superheater unit so that the boiler may be used independently.

The various features of the invention are illustrated by way of example in the accompanying drawings, in which- Fig. 1 isa plan View: Fig. 2a vertical longitudinal section of a fire'tube boiler embodying the preferred form of the invention; Fig. 3 is an end view of the boiler superheater taken from the superheater end of the boiler; Fig. 4 is a vertical section on a line 4-4 of Fig. 2; and Fig. 5 is a detail view partly in section of the tempera- 5 ture control mechanism.

In the accompanying drawings the invention is shown as applied to a boiler l0 having the usual fire box II and steam and water cylinder l2 through which the fire tubes 13 extend to connect the combustion chamber l l with a smoke box M. This smoke box I4 is provided with an exhaust flue l5 having a control damper l6 and.

connected to a stack l1.

The front end of the smoke box M opens into an extension or superheater chamber l 8 in which are banks of steam pipes I9 supplied with steam from the boiler l0 through a takeoff pipe 29 and a branch pipe ii that leads to a manifold 22 at the upper end of the bank of tubes IS. The steam passing through the banks of tubes i9 is received in a lower manifold 23 at the bottom of the bank of tubes and withdrawn through a supply pipe 24. The superheater chamber I8 is closed by a baffle 25 to the smoke box M from its upper end to about the middle level of the smoke box thus causing the gasesto pass from the smoke box into the lower part of the superheater chamber I8. A horizontal bafile 26 extends from the lower edge of the baflle 25 to 'a distance short of 'the front end of the superheater chamber to cause the gases to flow forwardly in the lower half of the superheater chamber, thence to pass upwardly in front of the front edge of the baille 2E3 into the upper part of the superheater chamber as indicated by the solid line arrows. An exhaust flue 21 extending upwardly from the rearmost part of the superheater chamber draws the gases 'backwardly above the baffle 26 from whence they pass into the stack IT to which the flue 21 is connected. The flue 2'! is provided-with a' damper 28 which is mounted on a shaft 29 coaxially with the shaft of thedamper 16. The plane of the damper 28 isv at a right angle or at from the 7 understood that various other shapes and sizes of superheater chambers may be employed. For convenience in removing the superheater chamber, it is mounted on a framework comprising a pair of skids 3| so that upon detachment from the smoke box it may be slid sidewise or at right angles to boiler.

The dampers l6 and 28 are thermostatically controlled so that the damper i6 will open more widely and the damper 28 be moved toward closed position when the temperature of the superheater steam passing through the pipe 24 increases beyond that for which the apparatus is set. For this purpose a thermally expansible fluid container of any suitable type in the steam pipe 24 is connected by means of a tube 32 to a cylinder 33 where it moves a piston stem 34 downwardly against the tension of a spring 35. The lower end of the piston rod 34 is adjustable and pivotally connected to a horizontal lever 36 at a point between the ends of the lever. One end of the lever 36 is pivotally connected to a valve stem Bl which extends into a valve cylinder 38 and is attached therein to a sliding piston valve 39. Steam is supplied from the pipe 24 or other source to a tube 4|! to the valve cylinder 38 at a point between a pair of outlet tubes4l and 42. The valve 39 in its normal position closes both the ports to the tubes 4| and 42 from the steam admitted through the tube 40. When moved upwardly from its position it puts the tube 4| in communication with the supply pipe 4|! and steam then passes through pipe 4| to the lower end of a valve actuating cylinder 43 to the part to which the pipe 4| is connected. When the valve 39 is lowered from its position communication between the supply pipe 40 and the outlet pipe 4| is maintained closed but communication is open to the pipe 42 so that steam flows from the supply pipe 40 through the pipe 42 to the upper part of the cylinder 43 to which the pipe 42 is connected.

A piston 44 is positioned in a cylinder 43 between the ports of the pipes 4| and 42 therein so that when steam is admitted by the pipe 4| to the lower part of the cylinder 43 it forces the piston 44 upwardly and when steam is admitted through the pipe 42 to the upper part of the cylinder 43 it forces the piston 44 downwardly. With the upward movement of the piston 44 the steam displaced may pass through the pipe 42 and vent below the valve 39 to the atmosphere through a suitable vent 43' in the valve chamber 38 and similarly when the piston 44 is moved downward the exhaust steam is exhausted through pipe 4| and above the valve 39 through vent 44 to the atmosphere.

It will therefore be apparent that with an increase in temperature of the steam in the pipe 24 the expansible fluid would pass through the pipe 32 to the upper end of the cylinder 33 and will displace the piston rod 34 downwardly against the action of the spring'35 thus moving downwardly the lever 36 and the valve stem 37 to open a passage through the valve chamber 38 from the pipe 4|! to the pipe 4| and to exhaust steam through the pipe 42. Thus steam will be admitted to the lower part of the cylinder 43 to force the piston 44 upwardly. When the exp ansible fluid contracts with a drop in temperature of the steam passing through the pipe 24 the spring 35 will lift the piston rod 34, lever 3'6, valve stem 31 and valve 39 to admit steam from the pipe 49 and through the pipe 42 to the upper part of the cylinder 43 and to exhaust it through the pipe 4| from the lower part. It will therefore be apparent that the piston 44 rises with an increased temperature of steam in the pipe 24 and falls with the falling temperature.

The movements of the piston 44 are transmitted to the dampers i6 and 28 by means of a piston rod 45 extended upwardly through a suitable stuffing box 46 in the cylinder 43 and connected through the link 41, lever 48, rotatable about pivot 48, adjustable link 49 and crank arm with the shaft 29 with which the dampers l6 and 28 are rotated. Thus, when the piston 44 rises with an increase in temperature, it swings the dampers clockwise as shown in Fig. 3 thereby closing the damper 28 and opening the damper I6 causing less of the fire tube gases to pass into the super-heater and more of them to by-pass through the flue I5 directly into the stack l'l. Conversely when the temperature of superheated steam drops the piston 44 also is lowered, rotating the dampers 28 and I6 counter-clockwise so that 28 rotates toward open position and Hi towards closed position to increase the amount of hot gases passing'through the superheater and a decreased quantity by-passed through the flue l5.

It will be noted that the lever 36 is pivoted at one end to the piston rod 45 and at the other to the valve stem. 37. When the expansible liquid of the thermostatic element forces the piston rod or stem 34 downwardly, the lever 3'8 pivots on its connection to the piston rod 45 thereby pushing downwardly the valve stem 3? and opening the passage 42 for the supply of fluid to the upper side of the piston 44. This causes a lowering of the piston rod 45 whereupon the lever 36 pivots about its connection to the thermostatic piston rod 34 lifting the valve stem 3'! until the passage to the tube 42 is closed. Therefore with each position of the thermostatic element piston 34 steam will be supplied either through the pipe 4| or the pipe 42 until the piston 44 and piston rod 45 take a corresponding position. From this it will be apparent that with each temperature of the steam in the pipe 24 the thermostatic element will move the dampers l6 and 28 through the lever 36 to a definite position. For example,

a higher temperature will tilt the dampers l6 and 28 to by-pass more of the exhaust gases through the exhaust l5 and less throughthe superheater, whereas a drop to a lower temperature will set the dampers to a definite position supplying a larger proportion of the hot gases through the superheater and a lesser proportion through the flue i5.

Through this controlled apparatus therefore the temperature of the superheated steam supplied through the pipe 24 is kept within fixed limits and excessive temperatures that might burn out or injure the tubes is of the superheater are avoided. In the event that the superheater should be injured or placed out of commission, it may be disconnected from the pipe 20 by a valve 5| in the pipe 2| and the offtake pipe 24 may be closed by a valve 52. Steam may then be b-y-passed to the pipe 24 directly from the oiTtake pipe 28 through a by-pass pipe 53 connected between the pipes 20 and 24 and normally closed by a valve 54. 'The boiler may be provided with the usual dial thermometer 55. When the superheater is to be disconnected from the smoke box of the boiler its steam connections with the connecting pipe 2| may be disconnected at the flanged union 55 and its connection to the supply pipe 24 may be opened at the flanged union 51.

Through the above invention therefore I have provided a boiler in which the heat of the combustion gases is more effectively employed since it is used to superheat steam rather than for the generation of steam for which a larger surface exposed to the atmosphere would be required. Also the superheater being readily detachable leaves the front ends of the fire tubes readily accessible for cleaning. The danger inherent in boilers of this type in which the demand for steam varies Widely and irregularly of burning of the superheater tubes at times of low steam consumption is avoided.

What I claim is:

1. A locomotive type fire tube boiler having a smoke box, a superheater chamber extending forwardly from said smoke box and communicating therewith, superheater tubes in said chamber, a baflle in said superheater chamber so constructed and arranged as to cause gases from said smoke box to pass forwardly to the lower part of said superheater chamber thence upwardly and rearwardly, exhaust flues one for said smoke box and one for said superheater chamber and thermostatically operated dampers in said flues to control the alternative passages of exhaust gases through one or the other of said flues.

2. A locomotive type fire tube boiler having a smoke box, a superheater chamber extending from said smoke box, superheater tubes in said superheater chamber, exhaust flues and dampers therein from said smoke box and said superheater chamber respectively, means controlled thermostaticallyby steam from said superheater tubes to position the said dampers to definite positions for each temperature of said steam, said means comprising a steam cylinder and piston, a valve for controlling the admission of steam to opposite sides of said cylinder and piston, a valve having a valve stem, a lever pivoted between said valve stem and said piston and a thermostatically actuated rod pivotally connected to said lever between said valve stem and said piston.

3. A boiler comprising a fire box, a smoke box, a steam and water cylinder between the fixe box and the smoke box, said cylinder containing a plurality of fire tubes to conduct gases of combustion from the fire box to sad smoke box, a superheater chamber forwardly of the said smoke box, bafile means to direct gases of combustion from the smoke box into the lower portion of said superheater chamber then forwardly and rearwardly therein, a smoke stack, conduit means to conduct gases of combustion from the smoke box to said stack, conduit means to conduct gases of combustion from the superheater chamber to said stack, means to pass steam from said steam and water cylinder through said superheater chamber countercurrent to the passage of gases of combustion therethrough, and damper means in each said conduit to regulate the amount of said gases passing through said superheater chamber into said stack.

4. The combination of claim 3, the length of said steam and water cylinder being such as to provide in said smoke box a gas temperature at least sufiicient to superheat the steam in said superheater chamber.

5. The combination of claim 3, in which means actuated by the temperature of the superheated steam is provided to regulate the said damper means to obtain a substantially constant superheated steam temperature under varying load conditions.

JOHN M. SHIMER.

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