US1883950A - Method of and apparatus for feeding water to boilers - Google Patents

Description

Oct. 25, 1932. J ss c 1,883,950

METHOD OF AND APPARATUS FOR FEEDING WATER TO BOILERS Filed April 27. 1927 2 Sheets-Sheet 1 Oct. 25, 1932. f J ss c 1,883,950

METHOD OF AND APPARATUS FOR FEEDING WATER TO BOILERS Filed April 27, 1927 2 Sheets-Sheet 2 Patented Oct. 25, 1932 UNITED. STATES PATENT OFFICE :rosnrn KISSICK, or WHITE PLAINS, NEW YORK, ASSIGNOR T0 KISSICK-FENNO 00. me,

- A CORPORATION or new YORK METHOD OF AND APPARATUS FOR FEEDING WATER TO BOILERS Application filed April 27,

In boilers operating at high rating and containing a small quantity of water, relative to the quantity of water evaporated, there is a large quantity of steam bubbles mixed with the water in the boiler and upon increase in the rating the steam bubbles become more numerous. If the load drops these bubbles condense and allow the level of the water to fall with the result that the water goes out of sight in the boiler gage glass.

- The principal object of the present invention is to automatically feed water to a boiler of the type indicated in such a way that when an increasing load goes off and the bubbles collapse, the water level will not go out of sight in the boiler gage but will fall back to a proper and safe position; and generally stated, this object is attained, according to my invention, by causing the rate of change of inflow to exceed the rate of change of outflow while the inflow and the outflow increase, and in causing the rate of change of inflow to be greater than the rate of change of outflow while the inflow and the outflow decrease.

The invention also comprises the improve ments to be presently described and finally claimed. 7

In the following description reference will be made to the accompanying drawings form ing part hereof and in which Figure 1 is a diagrammatic view illustrating features of the invention, and

Fig. 2 is a similar view illustrating a modification.

1 represents an ordinary water tube'boiler having a drum 2 where steam-is liberated. 3 represents a saturated steam line for conveying saturated steam into the superheater 4, from whence the steam passes by line 5 to the point where it is used. This type of apparatus is well known in the art and forms no part-of this invention.

An auxiliary reservoir 6 is connected to the boiler drum by means of a pipe 7 having therein valve 8, and this connection is made above the highest water level in the drum.

The reservoir 6 also has a connection 9 into the drum 2 below the lowest water level. Ordinarily the water level in the reservoir 6 will be the same as in the drum 2; however,

1927. Serial No. 186,887.

an additional connection is made into reservoir 6, and this additional connection consists of the pipe 10 which is tapped out of the superheated steam line, passes through coil 11 in reservoir 6, and returns to, the line 5 through pipe 12.

Between the points where pipelO and pipe 12 are connected to pipe 5 there is a drop in pressure. This drop in pressure may be provided by a diaphragm 18 and the drop in pressure is a function of the steam flow therefore there will always be a circulation of superheated steam through pipe 10, coilll, and pipe 12, the rate of circulation being a function of the drop in pressure across the diaphragm 13 which in turn is a function'of the quantity of steam passing through line 5.

Inasmuch as the steam passing through coil 11 is, due to the fact thatvit is superheated, considerably hotter than the water in reservoir 6, there will be some steam generated in reservoir 6. If valve 8 is throttled the steam generated in reservoir 6 will not be able to flow freely back into the drum 2, and thus a slight excess pressure will be built up above the level of water in reservoir 6, tending to depress it., By properly proportioning the flow of superheated steam to coil 11, and by proper adjustment of valve 8, it will thus be seen that the water level in reservoir 6 can be made to assume a height which is partly due to the steam flow and partly due to the head of water in drum 2.

It is a simple matter to connect an ordinary water regulator to reservoir 6 and have I it control the main feed valve. For the purpose of illustration I have shown one type of regulator which consists of a cylinder 14 in which the water level stands at the same height as in reservoir 6. Inside of the cylinder 14:, is a pipe 15 filled with liquid and connected by extension 15 to diaphragm 16 of feed valve 17. As the water level in reservoir 6 and in the cylinder lowers, more of the pipe 15 is exposed to the temperature of the steam, thus the liquid in pipe 15 absorbs more heat and there is a resulting increase in pressure which is conveyed to diaphragm 16 tending to partially open the valve 17 in the feed line 25. Parts 14, 15, 16 and 17 are well known in the art and form no part of this invention.

It is evident that the liquid level in reservoir 6 may be depressed either by an increase in boiler outflow or by low level in the drum 2. Either one of these effects would tend to open the valve 17 by the action of the regulator 15. This, of course, is the desired result because in either case more water should be fed into the boiler. i

In the arrangement thus described the flow of water through valve 17 would depend upon the degree of opening of this valve if pressure differential across valve 17 were maintained constant. In practice it is not always possible to maintain a constant differential, therefore in order to have the flow through the valve 17 proportional to its opening, adifferential control valve 18 is inserted in the feed line.' This'can be of several types but for the purpose of illustration I have shown a valve having a. diaphragm 19 with a connection 20 at the inlet side of valve 17 and a con nection 21 at the outlet side of valve 17. These two pressures both act on the diaphragm and tend to move the valve stem 22 up or down as the case may be. A lever 23 with weight 2 1 is provided so that by setting the weight 24 at any desired position along the lever, the valve 18 will only function when there is a departure from the predetermined pressure across the valve 17.

It is thus evident that by the addition of regulating valve 18 the flow of water through the valve 17 may be independent of fluctuations in feed line or drum pressure and therefore the flow will only depend upon the steam output and the water level.

The construction and mode of operation of the apparatus shown in Fig. 2 are as described above eXcept as follows:

' Heat is supplied to the coil 11 from the furnace gases by way of the pipes 26 and 27. This will operate more quickly on the water level in the chamber 6 because the furnace conditions in the boiler with changes in load have to change before there is any change in the steam output. The pipe 27 is connected to the gas passage in the boiler in one of the later passes than the pipe 26, so that there is a difference in pressure which varies with the rate at which the boiler is operated and the quantity of gases flowing through the coil 11 varies with the boiler output.

It is a feature of the invention that the pressure effect of the heating coil in chamber 6 becomes greater as the boiler outflow increases thus, the liquid level in chamber 6 will balance a higher level in the boiler drum and as the regulator 15 tries to keep a uniform level in chamber 6 the tendency is to carry a progressively higher level in drum 2 as the boiler outflow increases. To increase the level in drum 2 it is evident that on increasing load the rate of water inflow must be greater than the steam outflow. In other words, the rate of water inflow must exceed the boiler steam outflow. Conversely on low loads the pressure generated in chamber 6 will be so small that the pressure will readily equalize through valve 8 and the level in drum 2 and chamber 6 will be practically equal; therefore, a lower level will be car ried in drum 2. That is, on decreasing loads the rate of water inflow must be less than steam outflow. In both cases whether on in creasing or decreasing load the rate of change of speed of movement of valve 17 will be greater than the rate of change of the demand.

The function of the auxiliary reservoir 6 will be further understood by considering the related action of the level in drum 2 and reservoir 6 under changing load conditions. If the boiler load be increased suddenly, the heat input to coil 11 will be increased and the level in 6 depressed; also on an increasing load there is always a drop in steam pressure in drum 2 but this drop in pressure will not immediately equalize into the top of chamber 6 due to the throttle action of valve 8, and for the purpose of illustration it may be said that some of the steam at higher pressure is trapped above the water level in chamber 6, thus forcing the level still lower than was due to the action of the heat input to coil 11 alone. In other words, the Water level in 6 overtravels and the feed water regulator will open so that the rate of feed water input exceeds the steam output. On a decreasing load the sequence of events occurs in the reverse order and the level in chamber 6 overtravels upwards.

. It will be obvious to those skilled in the art to which the invention relates that modifications may be made in details of construction and arrangement and in matters of mere form without departing from the spirit of the invention which is not limited to such matters or otherwise than the prior art and the appended claims may require.

I claim: I

1. The method of feeding water to a boiler according to water level and boiler output which consists in causing the inflow to substantially equal the outflow while the load is constant, and in causing the rate of change of inflow to exceed the rate of change of outflow while the inflow and the outflow increase, and in causing the rate of change of inflow to be greater than the rate of change of outflow while the inflow and the outflow decrease.

2. The method of feeding water to a steam boiler which consists in establishing a steam generating body of water in communication with the boiler, generating steam in said body of water proportionate to increased heat due to increasing-boiler load, applying the pressure of such steam on the body of water to depress its level and cause it to balance a higher level in the boiler, and regulating the feed water inflow in response to said body of water.

3. Means for feeding water to a steam boiler which comprise an auxiliary reservoir connected to the steam and water spaces of the boiler, a restriction in the connection between the reservoir and the steam space, means associated with the reservoir and responsive to heat, said heat being proportionate to boiler load and adapted by steaming the water in the reservoir to depress the level in the reservoir and to balance a higher level in the boiler, and a feed water regulator constructed and arranged to be operated by the V resultant level in the reservoir.

4. Means for feeding water to a steam boiler which comprise an auxiliary reservoir, connections between the reservoir and the steam and water spaces of the boiler and of which the connection to the steam space is restricted in respect to the connection to the water space, a feed water control operatively arranged in respect to the level in the reservoir, and means associated with the reservoir and responsive to heat, said heat being proportionate to boiler load and adapted by steaming the water in the reservoir to depress the level in the latter and to balance a higher level in the boiler.

5. The combination of a steam boiler having a feed water valve and an auxiliary reservoir connected to the steam and water spaces of the boiler, a coil arranged in the reservoir and connected across a pressure drop in the combustion. gas passages of the boiler whereby the fluid level in the reservoir is established by combustion gas flow and boiler water level, and mechanism for controlling the feed valve from the water in the reservoir.

6. The combination of a steam boiler having a feed water valve and an auxiliary reservoir connected to the steam and water spaces of the boiler, a heating means arranged in the reservoir and connected across a pressure drop in the combustion gas passages of theboiler whereby the fluid level in the reservoir is established by combustion gas flow and boiler water level, and mechanism for controlling the feed valve from the water in the reservoir.

7 A method of feeding water to a steam boiler according to water level and boiler output consisting in causing the water level to become progressively higher as the load increases and progressively lower as the load decreases.

8. Means for feeding water to a steam boiler which comprise an auxiliary reservoir connected to the steam and water spaces of the boiler, a feed control responsive to the level in the reservoir including a feed water valve, means associated with the reservoir and responsive to heat, said heat being proportionate to boiler load and adapted by steaming the water in the reservoir to depress the level in the latter and to balance a higher level in the boiler, and means for maintaining a predetermined drop across the feed valve.

9. The combination of a steam boiler having a feed water valve, and mechanism for controlling the feed valve, said mechanism being cooperatively responsive both to the water level in the boiler and to the flow of the hot gases which heat the boiler.

10. A method of feeding water into a boiler according to water level and boiler output, in which the rate of change of water input is greater than the rate of change of boiler output, with the input varying in the same direc tion as the output.

JOSEPH KISSICK.

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