Steam Trap Steam Trap. Principle of steam trap operation

Steam is one of the most efficient coolants, which instantly transfers all the heat energy to the consumer when in contact with the heat exchanger. In addition, the gaseous phase is easy to give the required characteristics - the necessary temperature and pressure. But with the interaction of steam and equipment, a large amount of condensate forms, which leads to water hammering, a decrease in thermal power and deterioration of the quality of the gaseous phase. To control water droplets on the surface of the pipes, a steam trap must be used. In foreign enterprises, such a fixture is referred to as a "vapor trap", which fully reflects the functional purpose of the device.

Steam Traps

Steam traps are one of the types of industrial pipeline fittings that are designed to prevent the condensate from falling out when using steam and to more efficiently use its thermal energy.

As a result of a series of experiments it was proved that the introduction of a steam trap into the complex of equipment retains up to 20% of the useful energy of the hot steam.

Types of steam traps

Depending on the design and implementation of the principle of operation, the pipe fittings can be mechanical, thermodynamic or thermostatic. Any type of steam trap should meet two basic requirements:

• Removal of condensate without losses of the gaseous phase;
• Automatic air bleeding from the system.

The condensate is formed due to steam losses of heat in the heat exchangers, and also at the time of warming up of the piping installations, when a part of the gaseous phase turns into water. Loss of a large amount of moisture reduces the energy efficiency of equipment, accelerates its wear. Therefore, it is so important to fight it.

Mechanical Steam Traps

Mechanical fittings are the most reliable, and from that popular, "trap for steam." Its principle of operation is based on the difference in the densities of water vapor and condensate, and the main actuating element is the float. Depending on the design of the float, the following types of reinforcement are distinguished:

• Steam traps steam or spherical open or closed type;
• A bell-type float element, or an inverted closed steam trap.

Each type of armature works according to its specific scheme, has advantages and disadvantages, knowledge of which will allow to realize the most effective scheme of work at the enterprise.

Steam Traps with Spherical Float

The basis of the construction of this type of fittings is a spherical float. It is located in the internal cavity of the exhaust valve and is connected to the valve-lever. In addition, the thermostatic valve is included in the steam trap. The principle of operation of a steam trap with a spherical float can be divided into two stages:

1. Condensate flows through the pipe into the device, fills the internal cavity and lifts the float, which pulls the lever-valve and opens the hole for water removal.
2. When a hot steam enters the appliance, the thermo-valve is triggered, the steam begins to accumulate in the cavity and causes the float to sink to the bottom, the outlet opening overlaps.

This is how the condensate separates from the steam. Due to the presence of the thermostatic valve in the construction, the gas is automatically removed and the air film is prevented from entering the cavity, which jams the device.

Advantages and disadvantages

A typical representative of an armature with a spherical float is a steam trap FT-44. The main pluses and minuses of devices will be analyzed on his example. The main thing that experts note is the device's insensitivity to variable loads. The device is capable of continuously removing condensate both at the vapor saturation temperature and at high loads. Steady and continuous separation of non-condensable gases is the next advantage of the reinforcement. All this combined with a long service life is due to the simple design of the device.

The main disadvantage of the device is its large dimensions, which increases the loss of heat to non-insulated housing elements. High sensitivity to water hammering and exacting to "clean steam" (possibly silt valve) - two more minuses of steam traps of this type.

Bell type steam traps

As is clear from the title, the main element of this type of steam trap is the bell, or the float is an "inverted glass". The device itself has a cylindrical shape, rather cumbersome (more than the previous representative), but it has a large set of advantages. In the initial position, the inverted float is at the bottom of the valve and its bottom rests against a vertical tube. A glass slide lever is attached to the glass, which is located in the valve cover. The separation of steam from condensate occurs in four steps:

1. Through the inlet pipe water enters the device, fills the internal cavity and pours out under pressure through an open spool.
2. Steam, entering the system, begins to press the bottom of the float, causing it to float in the condensate and close the valve.
3. Steam, being inside the glass, begins to decompose into a liquid and gaseous phase. The latter passes through a special channel in the bottom, enters the spool and pushes it away.
4. The condensate and the remains of the gaseous phase through the hole in the bottom leave the glass, the float begins to release, reopening the spool.

A cyclic repetition of the described operations leads to a complete and effective separation of the acute vapor from the condensate. This technology was patented in 1911, but to this day remains relevant.

Advantages and disadvantages

A vivid representative of the "inverted glass" type of valves is the Zamkon Steam Steam Trap. Pros and cons of devices of this category will be analyzed on his example. Here too large dimensions are considered a minus, which significantly affects the loss of thermal energy on non-insulated elements. Another disadvantage is the specialists refer to the limited capacity, which prevents the use of valves on high-performance equipment.

The benefits of a steam trap are much greater. Firstly, the spool is not subject to contamination, which increases the reliability of the device. Secondly, the armature is not afraid of water hammering. Thirdly, condensate removal is possible even at high temperatures.

In the event of failure, the exhaust valve remains open, which saves a set of equipment from breakage. Finally, all additional components and assemblies, such as filters or check valves, are installed directly into the steam trap body. This reduces the loss of thermal energy and reduces the overall dimensions of the entire set of devices.

Thermal fittings

Thermostatic and thermodynamic steam traps function due to the ability of different media to expand and contract with increasing or decreasing temperature. Together with the increase in temperature, for example, when steam enters, the locking element expands and closes the channel, which drains the condensate.

The principle of operation of other devices is based on changing the pressure inside the system as a result of the interaction of a dense (cold) and rarefied (hot) medium. The main elements in such devices are bimetallic plates. In the photo, the steam trap is presented with a bimetallic element. This kind of equipment has a complex design and is rarely used in practice. Low popularity is also due to a complex, and often impossible, repair. The use of this type of equipment is justified only at particularly responsible industrial plants.