GB2099982A

GB2099982A - Steam trap

Info

Publication number: GB2099982A
Application number: GB8211537A
Authority: GB
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1981-04-24
Filing date: 1982-04-21
Publication date: 1982-12-15
Also published as: FR2504640A1; BR8202321A; JPS586096U; DE8211685U1; ZA822744B; AR226405A1; DE3215104A1

Abstract

A float-type steam trap for use in a vertical in-line installation has a chamber 3 having an outlet valve 9, 10, 11 which is opened by a float 4 on rising of the condensate level within the chamber. Non-condensables are discharged through a vent 17 which incorporates a thermostatic valve 19. The vent 17 is connected to a discharge port 8 for venting to a condensate collection system. <IMAGE>

Description

SPECIFICATION Steam trap This invention relates to a steam trap, and in particular to a steam trap for use in a vertical, in-line installation, and which will operate with virtually no steam loss.

Steam traps have been used for years by the chemical and petroleum industries. Many of the existing traps operate with some steam loss. For years, industry did not consider the 2 to 5 pound loss per hour per trap as a problem. However, with the increased cost of energy, it has become important to conserve energy in every way feasible. Thus, there is a need for steam traps which are easy to install, inexpensive and operate with little or no steam loss.

The present invention provides a lightweight steam trap for a vertical in-line installation, the steam trap comprising a vertical base plate and a thin-walled shell removably attached to the base plate, the base plate and the shell defining a chamber, the base plate having a steam port at its top and a condensate port at its bottom, the steam port being connectible to a steam line and the condensate port being connectible to a condensate line, the steam port communicating with a first passageway provided in the base plate and leading to a first aperture opening into the top of the chamber, the first passageway changing direction such that it is substantially horizontal when it ends at the first aperture, the condensate port being substantially in vertical alignment with the steam port, the condensate port communicating with a second passageway provided in the base plate, the second passageway leading to a second aperture opening into the bottom of the chamber and to a third aperture opening into the chamber near the top and above normal condensate level, a thermostatic valve being associated with said third aperture, wherein a valve seat element is provided within the chamber, the valve seat element being attached to the second aperture, and wherein a float is provided within the chamber, the float being attached to one end of a lever arm, the other end of the lever arm being attached to a valve closure member which engages a passageway in the valve seat element, the lever arm being pivotally mounted within the chamber such that, when the float rises in a vertical direction due to the presence of condensate within the chamber, the valve closure member is disengaged from the passageway in the valve seat element.

The steam trap of the invention has many advantages. In particular, during normal operation, virtually no live steam will be lost. This can create a significant saving in energy as compared with many traps presently in use, which waste from 2 to 5 pounds per hour.

Advantageously, the lever arm is pivotally attached to the valve seat element.

This steam trap also provides a "fail-safe" feature.

Thus, in the event that the float valve does not work, for example because it is plugged by dirt, the condensate will rise and activate the thermostatic valve, and thus be released from the chamber. This operation can continue until the trap is opened and cleaned. Preferably, the thermostatic valve is constituted by a valve seat defined by a plug associated with the third aperture, a valve closure member, and a bellows for moving the valve closure member towards, and away from, the valve seat.

This steam trap is particularly designed for use in a vertical, in-line installation. Most of the prior art traps have side inlet and outlet connections. This is disadvantageous because the installation of such traps requires the use of pipe elbows and additional piping. The steam trap of the invention has inlet and outlet connection at the top and bottom respectively, so that pipe elbows and additional piping are not required.

Preferably, the second passageway has a restriction between the second and third apertures, and adjacent to the third aperture. This restriction is useful should the thermostatic valve fail, in that it reduces steam loss from the chamber whilst permitting non-condensables to flow out of the chamber.

Known float and thermostatic steam traps are conventionally housed in cast iron chambers. Such cast iron assemblies are heavy and cumbersone. On the other hand, the steam trap of the invention is housed in a small casing. Also for safety reasons some companies do not permit the use of cast iron for steam pressures over 125 psi. However, with the steam trap of the invention, the entire trap housing need not be constructed of cast iron that is to say the thin-walled shell can be constructed from stainless steel. This means that the trap will weigh significantly less, and be much easier to fabricate.

The trap can be easily dismantled for repair, that is to say, only the shell need be removed to expose all the internal parts of the trap for repair or cleaning, the base plate and piping remaining in their operational locations.

One form of steam trap constructed in accordance with the invention will now be described, by way of example, with reference to the accompanying drawing, the single Figure of which is a part-sectional side elevation of the steam trap.

Referring to the drawing, the steam trap has a housing constituted by a thin-walled cylindrical shell 1 and a vertical base plate 2. The interior of the housing forms a trap chamber 3. This design provides for access to the chamber 3 for installing the various internal elements, and for cleaning and maintenance.

The housing can be made from various metals, for example, the thin-walled sheel 1 can be steel or stainless steel. This feature enables part of the housing to be fabricated by stamping techniques. By "thin-walled" it is meant that the wall thickness need only be sufficient to stand the steam pressures to be encountered during operation. For example, for operations at pressures from 15 to 150 psig, the wall can be 0.060 inch in thickness. At pressures up to 250 psig the wall thickness can be 0.070 inch. The base plate2can be formed byforging and drilling. It could also be formed by casting.

The two parts of the housing are removably attached together to provide for easy assemblydisassembly and safety. Thus, the shell 1 can be attached to the base plate 2 by a locking ring 5 which is bolted (not illustrated) in place. A gasket 6 provides a seal to ensure that steam does not leak outside the chamber 3.

The top of the base plate 2 has an upper steam port 7 which will be attached to a steam line (not illustrated). This port 7 provides an entrance for steam and condensate into the trap chamber 3 through a passageway 23. The passageway 23 is initiallyvertical and it changes to horizontal as it ends at an aperture which opens into the chamber 3 to cause the steam to change direction as it enters the chamber. This will serve to deflect steam and condensate within the chamber 3, and prevents direct impingement of the steam and condensate on the internal working elements.

At the bottom of the vertical base plate 2 is a lower condensate port 8. The port 8 provides means for the discharge of condensate from the trap via a condensate line (not illustrated) to a condensate header or to the atmosphere, and communicates with the chamber via a passageway 14.

To provide for easy vertical, in-line installations, the upper steam port 7 and the lower condensate port8 are placed in vertical alignment.

A passageway 14 communicates with an aperture which opens into the bottom of the chamber 3, and in this aperture is attached a valve seat element 9. In the drawing, the element 9 is threaded into the aperture in the base plate 2. The valve seat element 9 has a passageway 10 that communicates with the passageway 14.

A valve closure member 11 engages the valve seat element 9, and seals the chamber 3 from the passageway 10. The valve closure member 11 is mounted on one end of a lever arm 12. The lever arm 12 is pivotally mounted within the chamber 3 by a pivot pin 13 and a support 15. The pivot support 15 is mounted on the valve seat element 9 for convenience of assembly. On the other end of the lever arm 12 is attached a float 4.

In operation, the condensate enters the chamber 3 through the upper port 7 and the passageway 23, and gathers at the bottom of the chamber. As the amount of condensate increases, it will cause the float 4 to rise. As the float 4 rises, it will cause the lever arm 12 to pivot around the pivot pin 13. This causes the valve closure member 11 to disengage from the valve seat element 9. The condensate will then drain out of the chamber 3 through the passageways 10 and 14. When the level of condensate is reduced, the float 4 will lower and cause the valve closure member 11 to seat itself on the valve seat element 9, and close the passageway 10. The rotation of the float 4 is selected such that the valve will open and close while the passageway 10 in the valve seal element 9 remains under the condensate level.By operating in this manner, essentially no steam is lost to the atmosphere through the passageways 10 and 14, and there is an almost continuous flow of condensate.

In view of the location of the valve closure member 11 and the seat 9 above the bottom of the chamber 3, the likelihood of the valve being clogged with dirt or the like is reduced. Any dirt in the condensate will collect at the bottom of the chamber 3, and can be removed when the trap is dismantled by removal of the shell 1.

Within the base plate 2, the passageway 14 also extends upwards from the lower condensate port 8 to an aperture which opens into the chamber 3 at a height which is above the normal level of condensate in the chamber when the trap is operating properly. This passageway communicates with a passageway 17 in a plug 18 of a thermostatic valve 19, the plug being attached to the aperture in the base plate 2.

If desired, the passageway 14 can have a restriction 16 near the opening to the thermostatic valve 19. This can be useful in the event the thermostatic valve 19 should fail, in which case the restriction, which may be for example 0.110 inch in diameter, would reduce steam loss from the chamber 3 and still be sufficient to permit the non-condensables to flow from the chamber. Alternatively, the passageway 17 in the plug 18 could be sized to perform this function.

The thermostatic valve 19 is mounted on the plug 18 by any suitable means. The valve 19 is conventional, and employs a bellows 20 which moves a closure member 21 into, and out of, the valve seat 22 defined by the plug 18.

Under normal conditions of operation, the bellows 20 remain expanded, and the valve 19 closed. When air, or other non-condensables, enter the chamber 3, they remain above the condensate; and, if they are not removed, they will prevent the flow of condensate into and out of the chamber. As these gases are cooler than steam, they cause the bellows 20 to contract, thus removing the closure member 21 from the valve seat 22. The gases then flow through the passageways 17 and 14, and are discharged through the condensate port 8. In usual operation this flow will be free of condensate.

The thermostatic valve 19 also serves as a fail-safe mechanism. If for some reason the float mechanism fails to open the valve to the passageway 10, the condensate will continue to rise. When it contacts the bellows 20, it will cause them to contract, and the condensate will be discharged through the passageway.

Claims

1. A lightweight steam trap for a vertical in-line installation, the steam trap comprising a vertical base plate and a thin-walled shell removably attached to the base plate, the base plate and the shell defining a chamber, the base plate having a steam port at its top and a condensate port at its bottom, the steam port being connectible to a steam line and the condensate port being connectible to a condensate line, the steam port communicating with a first passageway provided in the base plate and leading to a first aperture opening into the top of the chamber, the first passageway changing direction such that it is substantially horizontal when it ends at the first aperture, the condensate port being substantially in vertical alignment with the steam port, the condensate port communicating with a second passageway provided in the base plate, the second passageway leading to a second aperture opening into the bottom of the chamber and to a third aperture opening into the chamber near the top and above normal condensate level, a thermostatic valve being associated with said third aperture, wherein a valve seat element is provided within the chamber, the valve seat element being attached to the second aperture, and wherein a float is provided within the chamber, the float being attached to one end of a lever arm the other end of the lever arm being attached to a valve closure member which engages a passageway in the valve seat element, the lever arm being pivotally mounted within the chamber such that, when the float rises in a vertical direction due to the presence of condensate within the chamber, the valve closure member is disengaged from the passageway in the valve seat element.

2. A steam trap as claimed in claim 1, wherein the lever arm is pivotally attached to the valve seat element.

3. A steam trap as claimed in claim 1 or claim 2, wherein the second passageway has a restriction between the second and third apertures, and adjacent to the third aperture.

4. A steam trap as claimed in any one of claims 1 to 3, wherein the thermostatic valve is constituted by a valve seat defined by a plug associated with the third aperture, a valve closure member, and a bellows for moving the valve closure membler towards, and away from the valve seat.

5. A steam trap as claimed in any one of claims 1 to 4, wherein the thin-walled shell is constructed from stainless steel.

6. A steam trap as claimed in any one of claims 1 to 5, wherein the thin-walled shell is from 0.06 to 0.07 inch in thickness.

7. A lightweight steam trap substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.