US1898078A - Steam generator - Google Patents

Description

W. M. CROSS STEAM GENERATOR Feb. 21, 193-3.

Fild May 26, 1927 Patented Feb. 21,1933

UNITED STATES- PATENT OFFICE WALTER M. CROSS, OF KANSAS CITY, MISSOURI, ASSIGNOR TO BAIBC'OCK & WILCOX 00.,

OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY STEAM GENERATOR 7 Application filed May 26, 1927. Serial No. 194,328.

This invention relates to improvements in steam generators, and refers more particularly to an apparatus and method for separating deleterious material from the feed water to a boiler or tube generator by the intersecond bank of heating tubes 6. Upon the.

four walls of the combustion chamber are arranged the tubes 7, and upon the ceiling of both the combustion and tube chamber are the tubes 8. A heat exchanger is shown at 9, a separator at 10. A manifold 11 is positioned at the side of the furnace, and has a series of connections 15, 16, 17 and 18, which serve to withdraw the boiler water from the furnace tubes. These connections are controlled by valves 12 and 13.

The generation of the steam is effected in the following manner, water is introduced through the line 19 from any convenient source, and is brought in heat exchange relation with the hot fluid withdrawn from the separator 10 through the line 20. The cooled discharge fluid is withdrawn through the pipe 20 After being preheated in the heat exchanger 9, the water is directed through the pipe 21 to the bank of tubes 5 in the lower portion of the tube chamber. The tubes in this bank, as well as the tubes throughout the furnace are serially connected, so as to provide a continuous passage for the water which is being heated. After circulation and pre heating in the tube bank 5, the water passes to the tubes 7, arranged upon the heat reflecting surfaces of the combustion chamber.

The passage of the water in this chamber is continuously around the four sides of the chamber, and besides its passage around the wall of the furnace, it also travels upwardly.

5Q due to the fact that the successive tiers of tubes are serially connected. Above the bridge wall 4, the tube travel is somewhat enlarged by extending the length of pipes to the opposite wall of the tube chamber. From the top tube 7 the fluid is conducted into the ceiling tubes 8, and thence through the intermediate connection designated as 22 to the tube bank 6, which for convenience we will call the superheater section, and thence through the outlet 23.

As suggested, there is connected into the wall tubes a plurality of pipes or leads 15, 16, 17 and 18, having communication with the manifold 11, and these connections are valved in order that the heated water may be drawn off at any desired or appropriate part of the system. The water diverted in this manner is passed to theseparator 10, where it is maintained at a fixed liquid level by means of the automatic liquid level control device 24, which regulates the valve 25 in the withdrawal line 20. The separator 10 serves, not onl as a separator for the diversion and with rawal of scale, or other objectionable soluble or insoluble salts, which produce crust or excessive accumulation of scale in the tubes of the furnace, but also as an equilibrium chamber in which a definite or predetermined percentage of vapor and liquid phase materials exist.

From the top of the separator is withdrawn the purified fluid medium through the mani fold 26 and thence is carried back in the form of steam to the furnace tubes through connections 14, controlled by valves 14, where it is further superheated and where the greatest percentage of scale would form were the impurities not separated out just prior to this intense heating of fluid.

When the water is withdrawn through the lower connection 15, the return fluid is introduced back into the coils 7 through the lowest return lead 14 from the manifold 26, thus supplying fluid to all of the tubes subjected to the furnace heat. In the same manner, when the Water is withdrawn from the upper connections 16, 17 or 18, the return in each case is through the return lead 14, adjacent and to the same tube 7 from which the withdrawal was made.

Valves 12 in bypass lines between the withdrawal and return connections serve to produce an uninterrupted flow when the connections are being used due to opening of valves 12 and closing valves 13 and 14.

By means of the manifold 11 there isrwithdrawn a selected amountof liquid during the continuous operation of the generator which will prevent concentration of solids which would normally cause excessive accumulation and formation of scale on the tubes and in the separator. Furthermore, by interposing a separator and selectively withdrawing the heated fluid at a predetermined temperature for settling in a quiescence stage accumulations of scale can more or less be eliminated from the tubes. The point of withdrawal of the heated fluid is carefully chosen at that point at which there is a considerable deposition of the impurities due to the increased vaporization of the liquid and its capability of holding such impurities in solution or in suspension therefore decreased. After removing the impurities the fluid is returned to the tubes so that there is a continuous, uninterrupted flow through the tubes and separtor from inlet to discharge.

In operation the feed water is introduced through the pipe 21 into the heating coils and is passed through the latter until it meets an open valve 13. The heated fluid passes through the pipe controlled by this open valve and through the header 11 into the separator 10. The steam or fluid from the separator flows back through the header 26 into the pipe on the same horizontal plane with the pipe through which water is led into manifold 11. All of the other valves 13 and 14 not in the two horizontal pipes mentioned would be closed and the corresponding bypasses open, except the by-pass between the two pipes 14 and 15 which are serving as out lets from and inlets to the coil.

Where the feed water used contains solid matter of various degrees of solubility and considerable impurities in suspension, difficulty is experienced in preventing excessive accumulation of incrustations upon the interior of the boiler tubes, for this reason excessive superheating. and advantageous conditions for proper efliciency. is sacrificed on account of these impure water conditions. With the present type of system and the use of a separator, as described, even the muddiest of river water and water containing a very high percentage of soluble material may be used in a system in which the water is carried to high temperatures and pressures, Without any particular difliculty or undue expense being occasioned by too frequent cleaning or failure of tubes, due to overheating. Lines for the withdrawal and return of the heated fluid at different stages in the radiant bank of the heating coil are provided for to furnish increased flexibility in the selectivity of the points where it is desirable to draw off the water for settling out the impurities.

The particular zone or point at which the water is drawn off from the generator to the separator will be ascertained by the conditions of operation in the system, and will be approximately at the point at which the deposition of the impurities tends to occur.

It Will be understood that the invention is not limited to the particular type of furnace construction or tube generator system shown, as the normal type of tube generator may be employed, the novelty lying primarily in the use of the separator and the withdrawal of the water from the system at a predetermined or selected point for such separation.

I claim as my invention:

1. In a steam generator, the combination with a heating means, comprising an elongated sinuous coil, a water separator interposed in the heating coil and manifold connections between the coil and separator for diverting fluid and solids through the separator and back to the coil during continuous operation, at one of a plurality of selected points.

2. A steam generator comprising a furnace having a system of heating tubes therein, a separator for eliminating impurities from the heated fluid flowing through said system, and means for interposing the separator in the tube system at any one of a plurality of predetermined points.

3. A steam generator having in combina-' tion a steam generating coil, means for heating said coil, means for extracting the mixture of steam and water from said coil selectively at any one of a plurality of points, means for separating the steam and water, means for returning the steam to said coil at the same point where the mixture was withdrawn so as to subject said steam to the super-heating action of the remainder of said coil and means for varying the point of extraction.

4. A steam generator having in combination a steam generating coil, means for heating said coil, a separating chamber, means for connecting said chamber to said coil at any one of a plurality of points for removing steam and water from said coil at said point, means for returning steam to said coil at said selected point, means for removing separated water from said separator'and means for heating incoming feed water by said separated water.

5. A steam generator comprising a furnace having heating tubes therein, inlet and discharge connections, a separator, and a plurality of controlling means including connections associated with the tubes at separated points along the tubes between said tubes and said separator intermediate the inlet and discharge for selectively bringing the separator into operation in the tube system at any one of a plurality of positions.

6. A method of generating steam and removing impurities therefrom, comprising heating a continuous sinuous stream of fluid under pressure, diverting the stream at any one of a plurality of selected positions to provide a relatively quiescent pool of fluid for deposition of separated'matter, and using a fluid Vehicle to remove the separated matter while joining the purified fluid to the continuous stream.

7. The process of generating and superheating steam which comprises causing water to flow through a steam generating zone, vaporizing part of the water, extracting the mixture of steam and water from said zone at any one of a plurality of points, and returning only steam to said zone at the point of extraction.

8. The process of generating steam which comprises causing water to flow through a steam generating zone, vaporizing part of the-water, extracting the mixture of steam and water from said zone at any one of a plurality of points and returning only steam to the point of extraction, and selecting the point of extraction in accordance with variations'in the physical composition of the fluid in the steam generating zone.

9. The process of generating and superheating steam which comprises causing water to flow through a steam generating coil, separating the steam from the unvaporized water and removing said water from said coil, passing the separated steam only through the remaining part of said coil for superheating said steam, and proportioning the superheating and vaporizing sections of said coil in accordance with variations in the physical composition of the fluid in the vaporizing section by separating and withdrawing the water from any one of a plurality of points.

10. The process of generating and superheating steam which comprises causing water to flow through a steam generating and superheating coil, extracting the mixture of steam and water from said coil at any one of a number of points, returning only steam to said coil at said point of extraction, superheating the returned steam by causing it to flow through the remainder of said coil, and selecting the point of extraction in accordance with operating conditions.

11. In a series boiler including a coil ar ranged in successive steam generating and superheating zones, and a steam and water cal composition of the fluid in the generating zone, and thereby the proportions of the generating and superheating zones of the coil.

12. A steam generator having in combination a steam generating and superheating coil arranged in successlve steam generating and superheating sections of variable proporheating coil sections in accordance with vari ations in the physical composition of the fluid in the enerating section.

13. steam generator having in combination a steam generating and superheating coil arranged in successive steam generating and superheating sections of variable proportions, means for heating saidcoil, a steam and water separator, connections between said separator and coil at a plurality of points for the withdrawal of the steam and water mixture and the return thereto of the separated steam at any one of said points, and means associated with said connections for varying the proportions of said generating and superheating. coil sections.

WALTER M. CROSS.

separator interposed in said coil and defining the point of separation between the steam generating and superheating zones, the process of generating and superheating steam which comprises supplying water to the coil, evaporating a portion of the water, and varying the point of interposition of the separator in accordance with variations in the physi-

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