US2532951A

US2532951A - Steam flow control system

Info

Publication number: US2532951A
Application number: US234A
Authority: US
Inventors: Fred H Schaub
Original assignee: FRED H SCHAUB ENGINEERING CO I
Current assignee: FRED H SCHAUB ENGINEERING CO I; FRED H SCHAUB ENGINEERING Co Inc
Priority date: 1948-01-02
Filing date: 1948-01-02
Publication date: 1950-12-05
Anticipated expiration: 1967-12-05

Description

Dec. 5, 1950 F. H. scHAuB STEAM FLOW CONTROL SYSTEM Filed Jan. 2, 1948 i \Q A @JLW,

Patented Dec. 5, 1950 UNITED STATES PATENT OFFICE STEAM FLOW CONTROL SYSTEM Application January 2, 1948, Serial No. 234

6 Claims.

This invention relates to steam flow control systems and more particularly to systems for controlling the flow of processed steam to a plurality of steam using units.

In controlling a plurality of steam using units, it has heretofore been the usual practice to con nect the units such as presses, molds, or the like in parallel to a steam header and to equip each unit with an individual trap to pass condensate but to prevent the passage of steam. In the operation of such installations air tended to become trapped in the units to interfere with proper heating thereof by the steam and condensate would sometimes collect on the internal surfaces of the units interfering with uniform heating. Furthermore, a relatively long heat up time was required in starting the system after a shutdown due to the time required for the trap to pass the condensate and for the air in the units 7 to work its way out.

The present invention has for one of its objects the provision of a steam flow control system in which the steam using units heat up quickly when starting from a shut-down and in which uniform heating of the units is produced during operation. According to one feature of the invention air in the units and condensate formed therein are expelled quickly so that the units will heat rapidly.

Another object is to provide a steam flow control system in which a constant flow of steam is maintained through the steam using units to maintain them free from air and condensate and to produce uniform heating thereof.

Still another object is to provide a steam flow control system in which a plurality of units are operated in two groups, the first of which receives steam directly from the boiler or header and the other of which is supplied with steam by excess flow through the first group. Preferably the two groups are separated by an accumulator which serves to separate the steam and condensate so that dry steam is supplied to the second group of units. A further object is to provide an accumulator for a steam flow control system in which the condensatelevel isnormally maintained above the condensate discharge connection by controlling the condensate discharge in accordance with the level. According to a further feature, the condensate discharge is controlled by the pressure in the accumulator independently of the level.

The above and other objects and advantage of the invention will be more readily apparent when 7 nects.

read in connection with the accompanying drawing in which- Figure 1 is a diagrammatic View of a steam flow control system embodying the invention;

Figure 2 is a wiring diagram illustrating the control of the condensate discharge valve from the accumulator; and

Figure 3 is a diagrammatic detail section.

The system, as shown, is adapted to control the flow of steam through a plurality of steam using units such as pressers, molds and the like. The units may be identical or, if desired, several different types of units can be grouped together in a single system, the units preferably being such that they employ steam at substantially the same pressure. The units are divided into primary units, as indicated at I0, which represent the majority of the entire steam using capacity, and one or more secondary units I I which may be identical with the primary units If). Pref erably the units are so divided that the primary units will use the large majority on the order of about ninety (90%) per cent of the steam while the secondary unit or units will use the remainder.

As shown, the units are supplied with steam from a header [2 which may connect to the usual steam boiler, and condensate from the units is returned through a condensate return line l3 which may lead to a conventional vented receiver in the boiler room. The primary units are supplied with steam directly from the header through a manifold it connected to the header and having a tap-off l5 for each of the units it. The manifold may terminate in a branch header drip l6. Condensate, air and steam from each of the primary units Iii is discharged therefrom through a discharge line I6, each of which is equipped with an orifice I1 and a check valve E8 to prevent return flow. The branch header drip is similarly equipped with an orifice H and a check valve I8. The orifice I! may take any desired form being shown in Figure 3 as comprising an orifice plate l9 secured between two sections of conduit by a threaded collar 21. With this construction the orifice plate can easily be removed and changed so that the proper size orifice is employed foreach of the primary units. Condensate, steam and air passing through the primary units is collected in a condensate header 22 to which the branch headerdrip 56 also con- All of the condensate, air and steam collected in the header 22 is conducted to an accumulator which is. S own as comprising a vertically elon- 3 gated closed tank 23. The header 22 communicates with the tank intermediate its top and bottom and preferably at a point slightly above the normal condensate level in the tank. The steam and air separate from the condensate in the tank, the steam rising to the top, the air normally occupying the mid-section and the condensate falling to the bottom. The air will go off paltially with the steam from the top of the tank as described hereinafter and partially will be absorbed by the condensate in the bottom of the tank to flow ofi with the condensate and later to be liberated in the vented receiver in the boiler room. The condensate is conducted away from the tank through a conduit 24 connected to the lower portion of the tank, and steam is taken off from the top of the tank through a conduit 25.

The conduit 25 connects to the secondary steam using unit II to supply steam thereto. Condensate from the secondary unit I l fiOWs out through a conduit 25 through a flow control unit 27 and past a check valve 28 into a condensate return pipe 29 which connects to the pipe [3. The unit 21 is preferably an orifice type unit functioning generally as a trap means and including a plurality of spaced orifices of such a size that they will pass all of the condensate from the unit H and will normally pass a small amount of steam and air therewith. Thus the out flow from the secondary unit H is principally liquid condensate which may be mixed with a small amount of steam and air. A bypass 3! around the unit 2! may be provided for manual control when desired.

Flow of condensate through the discharge pipe 24 from the accumulator is controlled by a solenoid valve 32 in the pipe. Condensate passing the valve flows past a check valve 33 into the pipe 29 to return to the boiler room with the condensate from the unit ll. If desired, a valve bypass 34 may be provided around the valve 32 for man ual control. The valve 32 is normally controlled in response to the liquid level in the accumulator by an electric control unit indicated generally at 35. This unit may be of the type more particularly described and claimed in the Patent 2,467,073 to Benjamin L. Binford, granted on April 12, 1949. As shown diagrammatically in Figure 2, this unit comprises a non-magnetic conduit section 36 through which a magnetic armature 31 is moved by a float, not shown. As the level rises, the armature will move opposite a magnet 38 carried by a switch arm 39 to close the switch. When the level falls, the armature will move away from the magnet allowing the switch to open under the influence of gravity or of a spring as disclosed in said Binford application. The switch 39 is connected between a power source 4! and the coil of the solenoid valve 32, as shown in Figure 2, so that when the switch is closed the valve 32 will be open. Thus the liquid level in the accumulator tank is normally maintained approximately constant and above the connection of the condensate discharge conduit 25 with the tank. Thus only condensate can allow through the conduit 2 while the steam accumulates in the top of the tank and is withdrawn through the secondary .unit II.

In the event the secondary unit should become clogged or the accumulator should fail to function properly for some other reason, the pressure in the tank 23 tends to build up. In normal operation this pressure is slightly less than the pressure in the branch header H, but in the event of stoppage it will build up to approximately the same pressure as that in the branch header,

Since the primary units I0 could not receive steam under these conditions, means are provided to open the valve 32 in the event th pressure in the accumulator tank rises. This means, as shown, comprises a second switch 42 in parallel with the switch 39 which is adapted to be closed by a pressure responsive element 43 connected to the tank. Upon a rise in pressure, the switch 42 will close to open the valve 32 regardless of the condensate level in the tank so that steam can flow through the primary units and they will be maintained in proper operation. The entire electrical system may be connected to the line through a manual switch 44 so that it can be shut down when desired.

In normal operation assuming that the system has been shut down and the machines are cold, it may be started by opening the main valve as shown at 45 in the branch header or by opening the individual valve provided in the individual supply conduits l3. At this time steam flows into the relatively cold units IE3 and will condense fairly rapidly. The orifice unit ll will, however, pass the condensate and any entrapped air in the machines at a rapid rate so that the machines will heat quickly. Thereafter not only condensate but a certain amount of steam equal to approximately ten (10%) per cent of the machine capacity will flow through each of the machines and from its discharge conduit Hi. This condensate and steam together with condensate and steam passing the branch header drip 16 will be conducted to the accumulator tank 23 where the steam and condensate will separate. The condensate will be withdrawn through the conduit 24 while the steam will flow to the secondary unit H to heat it. Condensate and the small amount of steam passing the secondary unit will mix with the condensate from the conduit 24 and will be returned to the condensate return header l3.

With this system a constant flow of steam is maintained through the several steam using units so that they will be purged of air and condensate at all times and will heat quickly and remain at a uniform temperature. The only unit from which escaping steam is returned to the condensate return header is the secondary unit I l which represents only about ten (10%) per cent of the entire system capacity. Only a small amount of steam flows into the condensate return so that the system operates economically. The accumulator operates efficiently to separate excess steam flowing through the primary units from condensate from the primary units so that a relatively large excess of steam can be circulated through the primary units without loss. In the event that the secondary unit ll has a sudden large steam demand, the pressure in the accumulator will drop and the same pressure drop will occur in the condensate header 22. This will cause an increase in steam flow to the accumulator to meet the increased steam demand of the secondary unit so that it will operate properly. In the event the secondary unit ll does not demand enough steam, the pressure responsive control 43 will open the valve 32 to relieve excess pressure and maintain the proper flow of steam through the primary units. Thus efficient operating conditions are insured at all times.

While one embodiment of the invention has been shown and described in detail herein, it will he understood that this is illustrative only and is not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. A steam flow control system comprising a steam using unit, a conduit to connect the unit to a source of steam, an outlet conduit connected to the unit, an orifice in the outlet conduit to control the flow therethrough, an accumulator tank connected to the outlet conduit, a water outlet connection to the lower part of the accumulator tank, a second steam using unit connected to the top of the tank, a control valve in the water outlet connection, means responsive to the water level in the tank normally to maintain the level substantially constant above the water outlet connection, and means responsive to the pressure in the tank to open the valve when the pressure exceeds a preset value.

2. A steam flow control system comprising a steam using unit, a conduit to connect the unit to a source of steam, an outlet conduit connected to the unit, an orifice in the outlet conduit to control the flow therethrough, an accumulator tank connected to the outlet conduit, a water outlet connection to the lower part of the accumulator tank. a control valve in the water outlet connection,

means responsive to the water level in the tank normally to maintain the level substantially constant above the water outlet connection, means responsive to the pressure in the tank to open the valve when the pressure exceeds a preset value, and a second steam using unit connected to the upper part of the tank to receive steam therefrom,

3. A steam flow control system comprising a steam using unit, a conduit to connect the unit to a source of steam, an outlet conduit connected to the unit, an orifice in the outlet conduit to control the flow therethrough, an accumulator tank connected to the outlet conduit, a water outlet connection to the lower part of the accumulator tank, a control valve in'the water outlet connection, means responsive to the water level in the tank normally to maintain the level substantially constant above the water outlet connection, means responsive to the pressure in the tank to open the valve when the pressure exceeds a preset value, a second steam using unit connected to the upper part of the tankip receive steam therefrom, a condensate discharge conduit connected to the second unit, and trap means in the condensate discharge conduit to pass condensate while substantially preventing the flow of steam therethrough.

4. A steam flow control system comprising a plurality of steam using units, conduits to connect a majority of said units directly to a source 6 of steam, discharge conduits for said last named units formed with flow control orifices, an accumulator connected to the discharge conduits to receive steam and condensate therefrom, separate steam and condensate discharge conduits for the accumulator, means responsive to the condensate level and to the pressure in the accumulator to control the discharge of condensate therefrom, the steam discharge conduit being connected to the remainder of said units to supply steam thereto, a condensate discharge conduit for the said remainder of the units, trap means in the last named conduit to pass condensate while substantially preventing flow of steam therethrough, and a common condensate return conduit connected to the accumulator condensate discharge conduit and the trap means.

5. In a steam flow control system, an accumulator comprising a tank having an inlet for steam and condensate, a condensate outlet conduit connected to the lower part of the tank, a steam outlet conduit connected to the uper part of the tank, a valve in the condensate outlet conduit, means responsive to the liquid level in the tank to control the valve to maintain the level above the connection of the condensate outlet conduit, and means responsive to the pressure in the tank to open the valve when the pressure exceeds a predetermined value independent of the liquid level in the tank.

6. In a steam flow control system, an accumulator comprising a tank having an inlet for steam and condensate, a condensate outlet conduit connected to the lower part of the tank, a steam outlet conduit connected to the upper part of the tank, an electrically operated valve in the condensate outlet conduit, a control circuit for the valve including a, pair Of switches in parallel, means responsive to the liquid level in the tank to control one of the switches, and means responsive to the pressure in the tank to control the other of the switches.

FRED H. SCHAUB.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,758,295 Rosenblad May 13, 1930 1,916,073 Rosenblad June 27, 1933 1,968,171 Reiss July 31, 1934 2,341,738 Olin Feb. 15, 1944 2,366,332 Harrison et al Jan. 2, 1945