US2818819A - Automatic condensate return trap and steam system - Google Patents

Description

Jag. 7, 1958 T. c. HEARD I 2,318,819

. AUTOMATIC CONDENSATE RETURN TRAP AND STEAM SYSTEM Filegl April 9, 1954 2 Sheets-Sheet 1 THELBERT c. HEAR-D IN VEN TOR.

ATTOR/VE Y Jan. 7, 1958 "r. c. HEARD 2,813,819

AUTOMATIC COND'ENSATE RETURN TRAP AND STEAM SSTEM Filed April 9, 195 2 Sheets-Sheet 2 THELBERT c. H EARD INVENTQR.

ATTORNEY nited States Patent Ofiice Patented Jan. 7, 1958 AUTOMATIC CONDENSATE RETURN TRAP AND STEAM SYSTEM Thelbert C. Heard, Wichita, Kans.

Application April 9, 1954, Serial No. 422,152

2 Claims. (Cl. 103248) This invention relates to an improved condensate return trap which may be used in either low pressure or high pressure steam systems. It is most advantageous when used in a system which includes modulated control or" steam to the heat exchanger coils or other steam using devices. The invention also relates to an improved steam system in which condensate is prevented from accumulating in the steam using devices.

It is an accepted fact that conventional closed steam systems operate against a back pressure of 2 p. s. i. to p. s. i. in the wet return lines. Before the condensate dump trap for each steam using device can dump, internal pressure in the steam using device must build up to exceed this back pressure. When modulating valves are used to control the flow of steam into the respective steam using devices, such valves are ordinarily controlled by heat demand thermostats.

Those familiar with this art are aware that a thermostat controlled modulating valve, during a high percentage of its operating cycles, is barely cracked open and then closed as soon as. the heat demand is met. It is seldom open for a sufficient period to build up sufiicient internal pressure in the heating coil or other device to operate the dump trap against the normal back pressure in the condensate return line. Consequently, condensate accumulates in the line between the dump trap and the heating coil and then gradually fills the coil. The condensate thus accumulated in the coil limits the volume of steam which can enter the coil when the modulating valve cracks open. The reduced volume of steam entering the coil fails to satisfy the heat demand, and the modulating valve then opens wider and wider.

Steam under relatively high pressure is thus permitted to enter the coil, and immediately causes water hammer within the coil due to the partial blocking of the steam path by the accumulated condensate. As is well known, water hammer multiplies the entering pressure tremendously and causes joint leakage and other damage to the heating coil or other steam using device. Such damage results in a continuous high maintenance cost for the system.

It is a prime object of this invention to provide a steam system in which the dump traps for the respective steam using devices are relieved from dumping against any back pressure in the condensate return line, thus preventing the accumulation of condensate in the steam using devices, and consequently eliminating water hammer there- It is an additional important object of the invention to provide a float controlled automatic condensate receiver and booster trap which provides an atmospheric vent for the condensate return pipes leading from the dump trap of each steam using device in a steam system.

It is an additional object to provide a condensate return trap which periodically receives full steam pressure from the steam main, which, if the trap is installed at a level sufiiciently elevated above the condensate receiver or boiler, whichever the case may be, permits the condensate to drain from the trap to the receiver or boiler. If not installed at a suificiently elevated level, the steam pressure forces the condensate through the wet return line to a receiver located near the boiler.

The present invention not only reduces the cost of operation and maintenance in plants in which it is installed either initially or by conversion, but increases efliciency by maintaining all steam using devices free of condensate accumulation, thus permitting the maximum percentage of heat carried by the incoming steam to be utilized for the purpose intended.

General description Generally, a steam system embodying this invention includes a trap having a check valve controlled condensate inlet connected to the dump traps of various steam using devices, a check valve controlled condensate outlet connected to the main condensate return line, a valve controlled vent to atmosphere in the upper end of the trap above the high water line, a valve controlled inlet connected to a pressure steam line, a float, and float controlled means for simultaneously closing the vent valve and opening the steam inlet valve when the liquid level in the trap rises to a predetermined level, and for simultaneously closing the steam inlet valve and opening the vent valve when the liquid level drops to a predetermined level in the trap.

The details of the invention will be more clearly understood when the following description is read in connection with the accompanying drawings, in which:

Fig. l is a schematic view of a steam system illustrating the manner in which my condensate return trap may be connected therein;

Figs. 2 and 3 are similar side elevational views of a trap embodying my invention, with parts cut away and parts in section to illustrate details of construction and operation;

Fig. 4 is a fragmentary side elevational view of a portion of the mechanism shown in Figs. 2 and 3; and

Fig. 5 is an end view of that portion of the mechanism shown in Fig. 4, with parts shown in section.

In Fig. 1, a typical steam boiler adapted for heating purposes is shown at 10. The steam main is designated by the numeral 11, and supplies steam through a plurality of lead off lines 12 to respective steam using devices, such as the radiator 13. A thermostatically controlled valve 14 modulates the supply of steam to the radiator. The radiator is supplied with a conventional dirt trap or pocket 15, a strainer 16, and is connected by line 17 to a conventional condensate dump trap 18. Trap 18 periodically dumps condensate into a return line 19 provided with a check valve 20, and the condensate flows into the lower end of condensate return trap 21 through connecting pipe 53. As will be explained later in detail, condensate is periodically forced from trap 21 through return line 22, through check valve 23, and into a conventional surge tank, deaerating heater tank, or other conventional condensate receiver 24. Pump 25 picks up condensate from receiver 24 and forces it through return line 26 back into boiler 10. A steam supply line 27 supplies steam from main 11 to the trap 21 to force the condensate from the trap and into receiver 24, as will be explained below in detail.

Referring to Figs. 2 and 3, it will be seen that the trap 21 includes a heavy plate type cap 28, on which is mounted a pilot valve 29, a main valve 30, a vent pipe 31, and a rigid depending bracket 32 which supports the various parts of the valve controlling mechanism.

The housing of pilot valve 29 is connected at its upper end to steam supply pipe 27 by means of a branch pipe 33. Interiorly the housing is provided with an elongated valve chamber 34, which is provided with a valve seat 35 at its upper end. A valve 36 is reciprocable in chamber 34 by means of a combination stern and guide rod 37. This rod 37 extends downward through the lower end of the valve and into the interior ofthe trap. At a point below the valve seat 35, the valve housing 29is connected to the upper end of main valve 30 by means of a branch pipe 38. Thus when valve 36 is seated on its seat, as shown in Fig. 2, steam from pipe 27 is blocked from passing through the valve housing and through branch pipe 38, but when the valve 36 is unseated, as shown in Fig. 3, steam may pass through branch line 33 and branch line 38, and into the upper end of the housing of valve 30.

The interior of the housing of main valve 30 is divided into two valve chambers 39 and 40, by means of a partition 41. The chambers communicate through a port 42. Opposed valve seats 43 and 44 are provided on opposite sides of the partition 41. A valve body 45 is provided at one end with an operating plunger 46, and at its other end with a pair of opposed valve heads 47 and 48. The two valve heads are connected in tandem by means of a reduced diameter stem, which is smaller in diameter than the port 42 which connects the two valve chambers. As clearly shown, a compressed coil spring 49 bears against plunger 46 and normally .urges the valve body 45 in a direction to seat valve head 48 on valve seat 44. Itwill be noted that a plurality of lateral ports through the wall of the main valve housing connect the port 42 with the interior of the trap 21. These lateral ports are designated by the numeral 50. As shown, the valve chamber 40 in the main valve openly communicates with steam sulpply pipe 27 by means of a branch pipe 51. The upper chamber 39 of the main valve is in open communication with vent pipe 31 by means of a short conduit 52. It will be understood that the extreme lower end of vent pipe 31 is plugged, and is not in open communication with the interior of the trap 21. When the valve heads 47 and 48 are in the positions shown in Fig. 2, it will be seen that steam from supply pipe 27 is completely blocked by valve 48 from entering the interior of the trap 21. It will also be seen that the interior of the trap is vented-to atmosphere through the ports 50, the port 42, chamber 39, conduit 52, and vent pipe 31, the upper end of which is open. Thus condensate dumped by trap 18 is free to enter trap 21 through branch pipe 53, because there is no back pressure whatever in the space above the liquid level in this trap.

Float actuated valve controlling mechanism The major cooperating parts of the valve controlling mechanism are all pivotally mounted on the rigid depending bracket 32 inside the trap 21, and are removable as a unit with the cap 28. This mechanism includes a pilot valve control lever 54 pivotally mounted at 55 intermediate its ends. This lever oscillates in a plane common to the plane in which the guide rod 37 reciprocates. On one end of lever d, a weight is rigidly secured. The opposite end of lever 54 is bifurcated as at 57, to receive and guide the oscillation of a control lever detent 58, which is pivotally mounted intermediate its ends at 59. it will be understood that the mass of weight 56 is such, and the moment arm is such that when lever 54 is free to move under gravitational forces, it rotates clockwise (in Fig. 2), contacts the lower end of valve stem 37 and holds valve 36 on its seat against the pressure in pipe 33.

A control lever actuator 60 is mounted on a fixed pivot 61 to oscillate in a vertical plane common to the plane in which the control lever 54, the detent 58, and the valve guide rod 37 operate. On its outer end, this actuator 60 carries a weight 62, which weight normally urges the actuator to move toward the position shown in Fig. 3. This actuator includes an integral laterally projecting arm 63 which carries a freely rotatable roller 64 at its outer end, this roller being adapted to contact the lower edge of control lever 54 and to move the lever from the Fig. 2 position to the Fig. 3 position when the actuator moves clockwise.

An actuator detent 65 is pivotally mounted in a bifurcated bracket 66 mounted on the supporting bracket 32. This detent is substantially L-shaped, as clearly shown in Fig. 5, and serves to receive and hold the extreme inner end of actuator 60 when the actuator moves to the Fig. 2 position. The arm 66 of detent 65 projects laterally outward into the plane of travel of a float arm 67, which is also pivotally mounted on fixed pivot 61, and oscillates in a plane immediately adjacent the plane in which the actuator 60 oscillates. It will be noted that the float arm 67 and the actuator 60 are capable of free but limited independent movement.

An outwardly projecting pin 68, carried by the actuator 60, projects into the path of travel of the adjacent portion of the float arm 67. When the float arm moves counterclockwise, the actuator is forced to move in a similar direction as soon as the float arm contacts the pin 68. When the float arm 67 moves clockwise, 'however, it does not transmit motion to actuator 60.

Float arm 67 also carries a laterally projecting pin 69 which extends into the path of travel of the control lever detent 58, and serves to trip that detent in certain positions of the 'float arm, as will be explained. As shown, float arm 67 is provided with a conventional float 70.

Operation With the condensate return trap installed as shown in Fig. l, and with the various parts of the trap in the relative positions shown in Fig. 2, valve 36 is held on its seat by lever 54 and steam is blocked from reaching branch pipe 38. Likewise valve 48 is held on its seat both by spring 49 and by steam pressure in valve chamber 40, so steam is blocked from entering-the trap. The space above the liquid in the trap is vented to atmosphere, as previously described, and condensate from dump traps 18 is free to enter the trap without any resistance due to internal trap pressure.

As the liquid level in the trap rises float arm 67 moves to an intermediate position, shown in Fig. 4, the other members of the valve controlling mechanism remaining stationary. As the float continues to rise, the upper edge of arm 67 contacts projection 66 of detent 65 and rotates this detent counterclockwise (Fig. 5) until its upper end releases actuator 60.

Actuator 60 instantly moves clockwise (Fig. 4), roller 64 moves lever 54 counterclockwise allowing valve 36 to move downward oil its seat. The bifurcated end of lever 54 moves downward past the catch at the upper end of detent 58, and detent 58 (by its own weight distribution) moves slightly clockwise so that its catch engages lever 54, and holds it temporarily against clockwise movement.

Steam passes from pipe 33 through valve 29, through pipe 38 into the upper end of valve 30 and forces plunger 46 downward against the resistance of spring 49. This movement unseats valve 48 and very positively seats vent valve 47.

Steam rushes through pipe 51,valve chamber 40, port 42, and through ports into the upper .end of the trap. Condensate is thereby immediately forced from the trap through line 53, check valve 23, and in line 22 to receiver 24. Steam pressure closes check valve 20, of course. At this time, all trap parts are in their'Fig. 3 positions.

Float arm 67 moves counterclockwise as the liquid level drops. The offset end of arm 67-contacts pin 68 and forcibly moves actuator counterclockwise until its small end contacts projection 66 of detent .65 and moves the detent into its Fig. 5 position, in which position actuator 60 is again held against clockwise movement. Roller 64, of course, simultaneously moves out of contact 1 5 with lever 54, clearing the way for this lever to again move to its Fig. 2 position when it is released.

When float arm 67 has rotated a suflicient distance counterclockwise, pin 69 on float arm 67 contacts the concave edge of detent 58 and pivots the detent counterclockwise, forcibly moving the upper end of this detent away from contact with lever 54. Weight 56 promptly moves lever 54 clockwise, and valve 36 is thereby forced upward onto its seat shutting ofi steam flow from pipes 33 and 38. Steam above the piston in main valve 30 is bled ofi through pipe 38, chamber 34, and through the lower end of valve 29 along the stem 37.

Spring 49 moves valve body 45 upward seating valve 48 and cutting off steam flow into the interior of the trap. Valve 47 is unseated, the interior of the trap is again vented to atmosphere, and one operating cycle has been completed.

From the above description, it will be seen that I have provided a steam system which completely eliminates back pressure in the return lines into which the individual traps in the system discharge, thus eliminating all resistance to trap discharge, with consequent elimination of the accumulation of condensate in the respective steam using devices which normally results from back pressure resistance to trap discharge.

It will also be seen that the invention provides a trap which makes possible the automatic operation of such asystem.

Having described both phases of the invention with sufficient clarity to enable those familiar with this art to construct the trap and install and operate the system, I claim:

1. A condensate receiving trap for receiving condensate from a steam system and for periodically forcing accumulated condensate by steam pressure into a boiler return line, comprising: a pressure tank connected to a condensate inlet line and a condensate outlet line; a check valve in each of said lines to respectively prevent water in the tank from passing outward through the inlet line and from passing through the outlet line into the tank; a main steam control valve communicating with the interior of said tank and having two opposed valve head seats and tandem opposed valve heads on a single reciprocable valve element; a pressure steam inlet pipe connected to said control valve for delivery of steam under pressure to the interior of said tank when the first of said two valve heads is unseated and the second of said heads seated; a vent in said valve aflording communication between the interior of said tank and atmosphere only when the first of said heads is seated; spring means urging the valve element in a direction to seat the first of said heads; a separate gravity opened pilot valve on said tank having a reciprocable valve stem which projects into the interior of said tank; a pressure steam line which is an openly communicating branch of the above mentioned pressure steam inlet pipe communicating directly with the flow controlled by said pilot valve; a conduit connected to said pilot valve to conduct steam therefrom to one end of said control valve to move its valve element in a direction to unseat the first of said two control valve heads and to seat the second of said heads when the pilot valve is opened; a float within the tank; and mechanism within the tank connected to and actuated by said float for contacting said pilot valve stem and for closing and holding the pilot valve closed during the filling of said tank through the water inlet, and for releasing said valve to open when the float is raised to a ajpliedetermined level by the water accumulating in the 1:

2. In combination with a steam system, a condensate return trap inserted therein and comprising: a pressure tank having a check valve control condensate inlet and a check valve controlled condensate outlet; a main steam control valve which includes a casing which is in communication with a pressure steam supply line, with the interior of the pressure tank, and with the atmosphere, said casing including opposed valve head seats; a valve stem reciprocable in said casing and carrying opposed tandem valve heads for seating alternately on the respective seats, one head controlling the flow of pressure steam to the interior of the tank and the other head controlling the venting of the interior of the tank to the atmosphere; spring means urging the valve stem in a direction to seat one of said heads on its seat; a steam pressure actuated plunger carried by the valve stem for urging the stem in the opposite direction to seat the other valve head on its seat against said spring means, said casing affording connection to a second steam pressure supply line to actuate said plunger; a pilot valve controlling the flow of pressure steam into the casing from said second supply line and having a valve actuating element; a float within the tank; and mechanism actuated by said float for contacting the pilot valve actuating element, for closing and holding the pilot valve closed during filling of the pressure tank, and for releasing the pilot valve element to open the pilot valve when condensate in the tank accumulates to a predetermined level, the coordinated action between the pilot valve and the main valve being such that when the pilot valve is open only that head of the main valve which controls the flow of pressure steam to the interior of the tank is unseated, and when the pilot valve is closed only the vent control head of the main valve is unseated.

References Cited in the file of this patent UNITED STATES PATENTS 1,316,843 Lytton Sept. 23, 1919 1,895,813 Nash Jan. 31, 1933 1,922,164 Knefel Aug. 15, 1933 2,177,517 Cuthrell Oct. 24, 1939 2,612,118 Harvie Sept. 30, 1952

Images