What Is the Difference Between a Seal Pot and a Condensate Pot

Improper application of seal pots and condensate pots can lead to serious issues in machinery operations. Though these vessels may look similar, they serve distinct purposes in managing fluids. Confusing the two is a common mistake that compromises equipment reliability and performance.

This article clears up the confusion, detailing the specific roles of seal pots vs. condensate pots. Armed with this knowledge, engineers and technicians can select and leverage the right vessel to optimize their systems.

What is a Seal Pot

A seal pot, also known as a seal flush pot, is a specialized component used in mechanical seal systems to maintain a constant pressure on the seal faces. Its primary role is to provide a barrier fluid that lubricates and cools the mechanical seal, preventing process fluid from entering the seal chamber.

The seal pot is typically constructed as a cylindrical vessel that can be pressurized with an inert gas, such as nitrogen, or a clean fluid compatible with the process fluid. This pressurized barrier fluid is circulated through the mechanical seal, absorbing heat and contaminants before returning to the seal pot for cooling. By maintaining a higher pressure in the seal pot than the process fluid, a positive flow of clean barrier fluid across the seal faces is ensured.

What is a Condensate Pot

A condensate pot, also referred to as a knockout pot or vapor-liquid separator, is a vessel designed to separate liquid droplets from a gas or vapor stream. Its primary function is to remove entrained liquid particles, preventing them from entering downstream equipment and processes.

The working principle of a condensate pot relies on the difference in density between the gas and liquid phases. As the vapor stream enters the pot, it encounters a series of baffles or a mesh pad that causes the flow to change direction abruptly. This sudden change in direction, combined with the force of gravity, causes the heavier liquid droplets to separate from the gas phase and collect at the bottom of the vessel.

Key Differences between Seal Pots and Condensate Pots

Primary Function

The primary function of a seal pot is to maintain a liquid seal that prevents the escape of steam or non-condensable gases from the system. This is achieved by maintaining a constant water level in the pot, which acts as a barrier between the steam space and the atmosphere.

The primary function of a condensate pot is to collect and remove condensate from steam lines or equipment. As steam cools and condenses, it forms liquid water known as condensate. If not properly removed, condensate can cause issues such as reduced heat transfer efficiency, pipe hammering, and corrosion. Condensate pots provide a collection point for this liquid, allowing it to be drained from the system.

Working Principle

Seal pots operate on the principle of creating a liquid seal. Steam enters the pot and condenses, raising the water level. Any excess water is drained through an outlet, maintaining a constant water level. The depth of the liquid seal is determined by the height difference between the inlet and outlet connections. As long as this seal is maintained, steam or gases cannot escape.

Condensate pots work by providing a low point in the steam system where condensate can naturally collect due to gravity. As steam flows through pipes or equipment, it cools and condenses. This liquid water flows to the lowest point in the system, which is the condensate pot. From there, it can be drained manually or automatically using steam traps or pumps.

Application

Seal pots are commonly used in steam headers, steam turbines, and pressure reducing valve stations.

Condensate pots are widely used in steam distribution lines, heat exchangers, and process equipment.

Placement in System

Seal pots are typically located at high points in steam systems, such as the top of steam headers or upstream of steam consuming equipment. This placement allows them to effectively prevent the escape of steam from the system. The inlet connection is usually located near the top of the pot, while the outlet is placed lower to set the liquid seal level.

Condensate pots are located at low points in steam lines or at the bottom of equipment where condensate naturally collects. They are often placed immediately upstream of steam traps or condensate pumps to ensure reliable drainage. In some cases, condensate pots may be equipped with multiple inlets to collect condensate from different parts of the system.