US1945204A - Boiler feed system - Google Patents

Description

Jan. 30, 1934. J. SIM

BOILER FEED SYSTEM Filed April 13, 1933 Patented Jan. 30, 1934 UNITED STATES PATENT OFFICE BOILER FEED SYSTEM Application April 13, 1933, Serial No. 666,045,.an1di in Great Britain June 11, 1932 9 Claims.

This invention relates to boiler feed systems of the type served by a constant speed motor-driven reciprocating pump.

In a boiler feed system of this type maximum economy of energy consumption by the pump is obtainable only by allowing the pump to feed the boiler or boilers at maximum pump capacity for a period, and then relieving the pump of load for another period.

The present invention provides an improved feed system for one or more steam boilers in which the pump is adapted to feed automatically at maximum operative economy.

A boiler feed system according to the invention comprises a constant speed reciprocating feed pump, a pressure actuated by-pass valve interposed between the discharge and the suction sides of said pump, a float-operated relay or relays for controlling the operation of said bypass valve, and an automatic feed regulating valve or valves interposed in the feed discharge line to the boiler or boilers.

According to one arrangement there is provided for the boiler or for each boiler a floatoperated relay responsive to changes of water level in the boiler and including two relay valves, one of said relay valves controlling or contributing to control the by-pass valve, and a pressure-actuated feed regulating valve controlled by the other relay valve.

Each relay comprises opposed relay valve elements the end faces of which are exposed to the fluid pressure in a common outlet so that said valve elements are maintained in axial balance under fluid loads.

The by-pass valve and the fiuid-pressure-actuated feed regulating valve or valves are each operated by actuating fiuid flowing through controllable orifices.

According to a modification there is fitted to the boiler or to each boiler, between the boiler and the pressure-actuated feed regulating valve, a float-controlled feed regulating valve responsive to changes of water level in the boiler. The relay is operated by a float housed in a float-box located above the boiler water level and piped to the steam space of the relative boiler and to the feed discharge line at a point between the feed regulating valves.

Boiler feed systems constructed in accordance with the invention are illustrated diagrammatically in the accompanying drawing in which Fig. 1 shows a first embodiment and Fig. 2 shows a modified arrangement.

In the boiler feed system shown in Fig. 1 there is piped to each of two boilers A a float-box D in which obtains the same water level as in the associated boiler. Housed within each float-box D is a float C adapted to actuate a pair of relay or leak-off valves E, F. A pressure-actuated bypass valve J influenced in closing direction by a light spring R is connected across the discharge and suction pipes K, L, respectively, of the feed pump B so that, when the by-pass valve J is open, the pump B discharges back to the suction pipe L. Attached to the by-pass valve J is a piston P working in a cylinder Q connected by way of a pipe 0 incorporating a controllable orifice Y to the pump discharge pipe K and by way of pipes M to the relay valves E, the arrangement being such that o the by-pass valve J will open only if both the relay valves E are shut, the shutting of one of the relay valves E by itself being unable to bring about opening of the by-pass valve J, so that the by-pass valve J will open only when both boilers A are fed to their working water level and no further feed is required. The relay valve E of the boiler in which the working water level is last restored is that one which controls the by-pass valve J, causing it to open when the boiler water level rises and the associated float C closes said relay valve E.

A pressure-actuated feed regulating or inlet valve N interposed in the feed supply pipe U to each boiler A is controlled by the associated relay valve F, each such feed regulating valve N being actuated by a piston S working in a cylinder T connected by way of a pipe V tothe relay valve F and connected to the feed pump discharge pipe K by way of a pipe W incorporating a controllable orifice X.

As will readily be understood, the valves N and the by-pass valve J are operated by the release or the building up of fluid pressure beneath their respective pistons S, P caused by the opening or closing of the respective relay valves F, E, the setting of the operation of the valves N, J being adjusted to suit requirements by adjustment of the effective areas of the orifices X, Y.

Exhausts a from the relay valves E, F may be returned to a feed tank or to the pump suction pipe L.

The operation of the system is as follows:- Assume that both boilers A are being fed in accordance with their steaming requirements and that each boiler in turn demands less and less feed water until no feed water is required at all, i. e., both boilers are shut down. The float C in the float-box D connected to the boiler which first ceases to require feed will rise and close the associated relay valve E. This closure of one relay valve E has no effect on the by-pass valve J, because the relay valve E of the other boiler is still open, so that the pump B continues to feed both boilers; the water level therefore in the first boiler continues to rise, and the associated float C rises further. The relay valve F of the first boiler will now open, being set to lag behind the associated relay valve E on rising water level, and the fluid pressure under the piston S of the associated inlet valve N will be released, followed by closure of said inlet valve N, so that the first boiler will receive no more feed. The pump B will, however, be still discharging its full capacity, so that the water level in the second boiler will rise, and, when the second boiler requires no more feed, its relay valves E, P will function similarly to the relay valves E, F of the first boiler. Until the feeding of the second boiler is accomplished the by-pass valve J remains shut, because both relay valves E must be shut before the by-pass valve J opens, the pump B meantime discharging its full capacity at maximum economy. When the relay valve E for the second boiler closes, the fluid pressure under the piston P of the by-pass valve J rises, so that the by-pass valve J opens against the action of its spring R and the pump B immediately by-passes its discharge back to the suction pipe L and the pump discharge pressure falls to that required to force the water through the by-pass valve J against the light spring load. The pump 3 therefore becomes unloaded but continues to run at constant speed, consuming minimum power; no water is then fed to the boilers and both boilers are shut down.

The action on a rising load is the converse.

The water level falls in the boiler which first requires water; the associated relay valve F is caused to close, and, since there is no pressure in the pump discharge pipe K, the related inlet valve N may not open but is ready to open immediately full discharge pressure comes on; the boiler water level therefore continues to fall and the associated relay valve E then opens and releases the low pressure existing in the by-pass valve cylinder Q so that the by-pass valve J closes under the action of its spring R; pressure immediately rises in the pump discharge pipe K and the inlet valve N opens and feed water enters the boiler. When the second boiler requires water, the related valves F, E and N are operated in the prescribed sequence.

If the absolute minimum power is required under by-pass conditions, the operating water for the by-pass valve J and the inlet valves N may be taken from the boiler or boilers; the by-pass valve J being held open independently of the pressure in the pump discharge pipe K. This pressure, therefore, can be arranged to fall to that required to overcome the frictional losses in the by-pass'piping and valves and to give velocity to the by-pass water.

In the modification shown in Fig. 2 the system is so arranged that the flow into the boilers A is sensibly constant. As shown in Fig. 2, the'floats C operating the relay valves E, F, are housed in float-boxes D located above the water level in the boilers A and piped at b to the steam spaces of the boilers and at d to the respective feed lines it. Afloat-controlled feed water regulating valve e of normal design is fitted to each boiler A in the usual manner to maintain a sensibly steady water level for the load; with this arrangement the feed supply to the boilers is sensibly constant, intermittent supply from the feed pump B being accommodated in the elevated float-boxes D and causing rise and fall of the floats C therein.

In the arrangements according to Figs. 1 and 2 the associated relay valves E, F are constituted by opposed valve elements the end faces of each pair of which are exposed to the fluid pressure in the common outlet at, so that said valve elements are maintained in axial balance under fluid loads.

I claim:-

1. A boiler feed system, comprising, in combination with a constant speed reciprocating feed pump, a suction pipe connected to said pump, a discharge pipe connected to said pump and leading to the boiler, a by-pass connection between said pipes, a by-pass valve controlling said bypass connection, a feed regulating valve fitted to said discharge pipe downstream of said by-pass connection, a float chamber in communication with the boiler, a float in said chamber responsive to changes of water level in said chamber, and a relay device operated by said float, said relay device effecting the successive closing of said feedregulating valve and opening of said by-pass valve on rising movement of said float and the successive closing of said by-pass valve and open ing of said feed regulating valve on falling movement of said float.

2. A boiler feed system, comprising, in combination with a constant speed reciprocating feed pump, a suction pipe connected to said pump, a discharge pipe connected to said pump and leading to the boiler, a by-pass connection between said pipes, a by-pass valve controlling said by-- pass connection, a feed regulating valve fitted to said discharge pipe downstream of said by-pass connection, a float chamber in communication with the boiler, a float insaid chamber responsive to changes of water level in said chamber,

and a relay device operated by said float, said i relay device effecting the successive closingof said feed regulating valve and opening of said by-pass valve on rising movement of said float and the successive closing of said by-pass valve and opening of said feed regulating valve on falling movement of said float, said relay device including two relay valve elements one of which effects the opening and closing of said by-pass valve, and the other of which elements effects the closing and opening of said feed-regulating valve.

3. A boiler feed system as claimed in claim 2, in which the valve elements have end faces subject to equal fluid pressures.

l. A boiler feed system, comprising, in combination with a constant speed reciprocating feed pump, a suction pipe connected to said pump, a discharge pipe connected to said pump and leading to the boiler, a by-pass connection between said pipes, a by-pass valve controlling said by- Lilli) pass connection, a piston connected to' said by- 1.

pass valve, a branch passage from said discharge pipe open to the underside of said piston, said branch passage incorporating a controllable orifice, a feed regulating valve fitted to said discharge pipe downstream of said by-pass connection, a float chamber in communication with the boiler, a float in said chamber responsive to changes of water level in said chamber and a relay device operated by said float, said relay device effecting the closing of said feed regulating valve and the opening of said by-pass valve in high positions of the float, and closing said bypass valve to bring about the opening of said feed regulating valve in low positions of the float.

5. A boiler feed system, comprising, in combination with a constant speed reciprocating feed pump, a suction pipe connected to said pump, a discharge pipe connected to said pump and leading to the boiler, a by-pass connection between said pipes, a pressure-actuated by-pass valve controlling said by-pass connection, a feed regulating valve fitted to said discharge pipe downstream of said by-pass connection, a vessel in communication with the boiler and subject to the same internal pressure as the boiler, a float responsive to changes of water level in said vessel, and a relay device operable by said float, said relay device eiiecting the closing of said feed regulating valve and the opening of said by-pass valve in high positions of said float and the closing of said by-pass valve to bring about the opening of said feed regulating valve in low positions of said float.

6. A boiler feed system, comprising, in combination with a constant speed. reciprocating feed pump, a suction pipe connected to said pump, a discharge pipe connected to said pump and leading to the boiler, a by-pass connection between said pipes, a by-pass valve interposed in said branch passage, a piston connected to said bypass valve, a cylinder accommodating said piston, a connection between said cylinder and said discharge pipe, 2, feed regulating valve fitted to said discharge pipe downstream of said by-pass connection, a vessel in communication with the boiler and subject to the same internal pressure as the boiler, a float responsive to changes of water level in said vessel, relay valves controlled by said float, and connections from one of said relay valves to said cylinder and from the other of said relay valves to said feed regulating valve, said float opening said relay valves in high positions of the float whereby to effect the closing of said feed regulating valve and the opening of said by-pass valve.

'7. A boiler feed system as claimed in claim 6 in which the connection between the cylinder and the discharge pipe incorporates a controllable orifice.

8. A boiler feed system, comprising, in combination with a constant speed reciprocating feed pump, a suction pipe connected to said pump, a discharge pipe connected to said pump and leading to the boiler, a by-pass connection between said pipes, a by-pass valve controlling said bypass connection, a feed regulating valve fitted to said discharge pipe downstream of said by-pass connection, a float chamber in communication with the boiler, a float in said chamber responsive to changes of water level in said chamber, a relay device operated by said float and comprising two relay valve elements, a connection between one of said valve elements and said by-pass valve, and a connection between the other of said relay valves and said feed regulating valve, said relay device effecting the successive closing of said feedregulating valve and opening of said by-pass valve on rising movement of said float and the successive closing of said by-pass valve and opening of said feed-regulating valve on falling move ment of said float.

9. A feed system for a plurality of boilers, com prising, in combination with a constant speed reciprocating feed pump, a suction pipe connected to said pump, a discharge pipe connected to said pump and leading to the boilers, a by-pass connection between said pipes, a by-pass valve controlling said by-pass connection, feed regulating valves, one for each boiler, fitted to said discharge pipe downstream of said by-pass connection, float chambers one in communication with each boiler, a float in each float chamber responsive to changes of water level in its respective chamber, and relay devices, one operated by each float, said relay devices effecting the successive closing of the several feed-regulating valves and opening of said by-pass valve on rising movement of the floats and the successive closing of said by-pass valve and opening of the several feed regulating valves on falling movement of the floats.

JAMES SIM.

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