US1702375A - Feed-water-control system - Google Patents

Description

Feb. 19, 1929. 1,702,375

J. M. BARRETT FEED WATER CONTROL SYSTEM Filed Sept. 24, 1926 2 Sheets-Sheet 1 W; f /MQJMYZZM aftouww Feb. 19, 1929. 1,702,375

J. M; BARRETT FEED WATER CONTROL SYSTEM Filed Sept 24, 1926 2 Sheets-Sheet 2 T le-r' 2 W 6 W/MW W aftozuzw Patented Feb. 19, 1929.

UNITED STATES PATENT OFFICE.

JOmPH I. BARRETT, OF FOSTOBIA, OHIO, ASSIGNOR TO THE BWARTWOU'I' COMPANY,

OF CLEVELAND, OHIO, A CORPORATION 01' OHIO.

IEED-WATER-CONTROL SYSTEM.

Application filed September 24, 1926. Serial No. 137,419.

This invention relates to an arrangement of auxiliary apparatus for handling boiler feed water. More particularly it is concerned with the protection of the economizer from high pressures or surges in pressure which cause leakage either in the economizer gaskets or fittings.

Another object is to so position the diaphragm actuated valves, the diaphragms of which are in contact with the feed water, that the water passing through these valves may be of a low temperature so that the diaphragm will not be injured by heat.

The tendency in modern power plant practice is toward building and using boilers adapted to carry higher pressures. Coincident with the use of higher pressures, has come the necessity of strengthening the shells of the boiler drums along with the tubes and pipes and valves and al of the other auxiliary equipment. To maintain the necessary boiler ratings, it has been increasingly necessary to generate steam more rapidly because of the limited space within the thickened shells of the tubes and drums. Thus it follows that the feed water pipes which carry water at high pressure have also to carry the water at high velocity because of the comparatively small size of the pipes. This effect is carried back to the pump which in turn must maintain a pressure greatly in excess of the boiler pressure to take care ofthe large drop due 'to line friction between the pump and the most remote boiler.

It happens then that in a bank of several boilers that the feed water pump may be maintaining a pressure 200 or 300 pounds greater than the boiler pressure, but that the feed water pressure at the most remote boiler will be but 50 or pounds in excess of that boiler pressure when all of the boilers are operating at high rating. Now in such a situation. if for any reason the load should suddenly decrease on all of the boilers so that none of them take any appreciable amount of feed water, the result would be a rapid pressure surge throughout the length of the feed water pipe or main. The applicant has found that under such circumstances the economizer is the most vulnerable point in the system. This is due to the fact that when the feed water valve is closed, the point of greatest variation in pressure is adjacent the feed water valve or near the feed water valve in the direction of the pump. This is of course the usual location of the economizer and it is at this point that the greatest sur es and most rapid pressure changes occur. he usual type of economizer is not well adapted to receive these surges in pressure and it is withthe thought of avoidin this or to remedying this situation that t e 'applicant has devised the present structure.

.In the drawings Fig. 1 is a lay-out of the apparatus between a boiler drum and the feed water head; Fig. 2 is a die ammatic showing of a bank of boilers with apparatus installed in accordance with my invention.

I show therefore in Fig. 1'- a boiler drum D, feed pipe 1 leading from the feed water header or main M. In the feed line I designate the economizer E. At 5, 6 and 7, I show a feed water regulating valve constructed on the principle shown in the patent to Copley No. 1,193,125 of August 1, 1916. This feed water apparatuscomprises a steam generator 5 positioned to intercept the line of normal water level in the boiler drum having fluid therein ada ted to expand in response to the difference In heat content between the steam and thewater in the boiler drum. The line 6 leads from the generator 5 to a diaphragm operated feed water regulating valve Wl'llCl'l is adapted to be opened as the water level in the boiler lowers and permits the generator 5 to exert a fluid pressure on the diaphragm. Adjacent the feed water valve 7 I install. a differential valve which may be of a type described in my co endin application, Serial No. 105,423 file Apri 29, 1926.

This valve com rises a diaphragm adapted to actuate the Va ve member. The diaphragm may be subjected to the pressure of the outlet side of the valve in a direction tending to close the valve and subject to pressure from another point beyond the valve between which points a difierence in pressure may be predetermined b a force exerted by a spring to supplement t e last named pressure u on the diaphragm. The valves 7 and 10 may fixed adjacent each other as shown in my copending application, Serial No. 27,735filed May 4, 1925 in a manner which I find adx antageous to maintain uniform flow of feed water to the boiler. The pipe 11 is arranged to lead from the upper chamber of the valve 10 to a point 15 conveniently located between the valve 7 and the economizer. Between the pipe 11 and the chamber of the valve 10, I show an auxiliary valve 18. Near. this point is also the valve 14 with the auxiliary connection 12 leading to the interior of the valve 10 into communication with the chamber on the ing the valve 13 and opening the valve 14.

As described in my copending application mentioned above, Serial No. 27,735 the cooperation between the valves 7 and 10 is such that a predetermined pressure drop is maintained between the point 15 and the outlet side of the valve 10.

In Fig. 2, I show by diagram, the arrangement of several boilers in a bank, all being fed by onemain feed Water head by means of a pump P. I designate the several boilers B and the economizer E positioned acent thereto. The valves 7 and 10 along with the auxiliary pipe lines 6 and 15 are shown in an arrangement similar to that depicted in Fi 1.

With the economizers spaced between the feed valves anol'the boilers, I am able to maintain 1n the economlzer a pressure which 18 only in excess of the boiler pressure by substantially the amount necessary to overcome the line friction between the economizer and the drum. When the boiler is in operation the flow of feed water must increase with the increase in boiler rating. Thus if the boiler is operating at a pressure of 500 pounds and the flow of water into the boiler is such that the line losses between the feed water valve and the boiler is 10 pounds and the line loss through the economizer is ten pounds more, it will be necessary to maintain just beyond the economizer at least 520 pounds pressure to maintain the flow of water. With the differential valve and the feed water regulating valve connected as shown, I set the differential valve so that the drop through the feed water valve may be any constant amount, for instance 20 ounds, so that the highest pressure to whic the economizer may be subjected is 540 pounds. At an overratmg with the line and friction losses in the economizer amonuting to 40 pounds, the drop through the feed water valve bein maintained at approximately 20 pounds, t e highest pressure to which the economizer is subjected may then be as high as 560 pounds. If in the event the feed water I valve should substantially close, the economizer pressure would merely fall to boiler pressure with no resulting harm to the economizer. Whereas, if the economizer were positioned between the feed water valve and the-feed water main or header, the pressure might run up 100 or 200 pounds depending upon the excess pump pressure and the rating at which the other boilers in th bank are feeding i It will be seen that in a construction according to my invention, I not only protect the economizer, but also protect the valves and the diaphragm therefor by reason of the fact that the temperature of water flowlng through the valves is much less than the water flowing between the economizer and the boiler.

I claim:

1. The combination of a boiler, an economizer connected thereto, a feed water yalve responsive to changes of thermal conditions in the boiler, and differential means for malntaining less than a predetermined amount the excess pressure in the economizer over the boiler pressure.

2. The combination of a boiler, an economizer connected thereto, a feed water valve for the boiler positioned beyond the economizer, and differential means for maintaining less than a predetermined amount the difier ence in pressure between the boiler and the line connecting the feed water valve to the economizer.

3. In combination a boiler, a feed water header adapted to carry pressure greatly in excess of the boiler pressure, a feed water line leading from said header to said boiler, an economizer positioned in said line, means adapted to regulate the flow through said feed water line in response to changes in the water level in the boiler and means for maintaining in the economizer fluid pressure ex ceeding only by a predetermined amount the pressure in the boiler.

4. In combination a boiler, a feed water header adapted to carry pressure greatly in excess of the boiler pressure, a feed water line leading from said header to said boiler, an economizer positioned in said line, means adapted to regulate the flow through said feed water line in response to changes in thermal conditions in the boiler and means for maintaining in the economizer fluid pressure exceeding only by a predetermined amount the pressure in the boiler, both saidmeans being positioned between the economizer and the main feed water header.

5. In a bank of boilers having a common feed water supply, the combination of a feed water pum adapted to force water to the bank of boilers, a header leading from said pump to all of the boilers, individual feed water lines leadin from the header to each boiler, an economizer connected in the feed water line adjacent each boiler and means interposed between the economizers and the headenin the feed water lines adapted to maintain in the economizer a pressure exceedlng by only a certain amount the pressure in each boiler.

6. The combination of a bank of boilers, a feed water pump adapted to force water thereto, a header leading from said pump to all of the boilers, individual feed water lines sponsive to changes in water level in the boiler connected in the line beyond the economizer, and means interposed between the economizer and the header in the feed water line adapted to maintain in each eoonomizer a pressure exceeding by only a certain amount the pressure in the boiler served thereby.

7. The combination of a bank of boilers, an economizer for each boiler, a pump for feeding water to the bank of boilers and feed water regulating means disposed beyond each economizer relative to each boiler, said means being adapted to protect the eoonomizers from pressure in excess of the boiler pressure plus the amount desired to facilitate the flow of feed water through each economizer into each boiler.

8. The combination of a boiler, an economizer therefor, and feed water regulating means disposed beyond the economizer relative to the boiler, said means being adapted to protect the economizer from pressure in excess of the boiler pressure plus an amount desired to facilitate the flow of feed water through the economizer into the boiler.

In testimony whereof, I hereunto aflix my signature.

JOSEPH M. BARRETT.

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