How to properly recover condensate water

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This post was last edited by hjztbwg on 2015-9-25 09:23. How to properly recover condensate: Condensate in steam systems can be recovered in three ways: a) By gravity. This is the best method for recovering condensate. In such systems, the condensate flows back to the boiler thanks to gravity, through properly arranged condensate pipes. The design of these pipes does not include any points where the flow is obstructed, which prevents backpressure from being created on the steam traps. To achieve this, there must be a height difference between the outlet of the condensate collection system and the inlet of the boiler feed water tank. In practice, it is difficult to use gravity to recover condensate, as the boilers and processing equipment in most factories are located on the same level. b) Recovery through backpressure: With this method, condensate water is recovered by utilizing the steam pressure in the check valve. The condensate pipes are raised to a height higher than that of the boiler feed water tank. Therefore, the steam pressure in the check valve must be sufficient to overcome the static head, the frictional losses in the condensate pipes, as well as any backpressure from the boiler feed water tank. During a cold start, when the amount of condensate is highest and the steam pressure is low, it becomes impossible to recover the condensate, which can lead to delays in startup as well as the risk of water hammer. When the steam equipment is equipped with a temperature control valve system, changes in steam pressure depend on changes in steam temperature. Similarly, steam pressure is unable to remove condensate water from the steam space and return it to the main condensate pipeline; this leads to water accumulation in the steam space, temperature imbalances, thermal stress, and potentially water hammer and damage, resulting in a decline in process efficiency and quality. c) By utilizing a condensate recovery pump, the recovery of condensate can be achieved by mimicking gravity. The condensate is discharged under the force of gravity into a condensate collection tank that is connected to the atmosphere. There, a recirculation pump sends the condensed water back to the boiler room. The choice of pump is crucial. Centrifugal pumps are not suitable for this purpose, as they draw water by rotating their pump rotor; this rotation reduces the pressure of the condensed water, with the pressure reaching its lowest level when the drive is idle. At a condensed water temperature of 100°C and atmospheric pressure, such a pressure drop causes some of the condensed water to cease being in liquid form (the lower the pressure, the lower the saturation temperature). The excess energy then evaporates part of the condensed water back into steam. When the pressure rises, these vapor bubbles burst, and the liquid condensed water rushes forward at high speed – this phenomenon is known as cavitation, and it can damage the pump’s blades and bearings as well as burn out the pump’s motor. To prevent this from happening, it is possible to increase the pump’s head or reduce the temperature of the condensed water. Increasing the head of a centrifugal pump can be achieved by raising the height of the condensed water collection tank above the pump by several meters; a height of more than 3 meters is common. This ensures that the condensed water from the processing equipment flows into the collection tank. Raising the height of the pipes behind the check valve also creates backpressure, making it harder for the condensed water to escape from the steam space. The temperature of the condensed water can be reduced by using a large, uninsulated collection tank, allowing the water inside to rise from a lower level to a higher one over enough time to bring its temperature down to 80°C or lower. In this process, 30% of the heat in the condensed water is lost. For each ton of condensed water recovered in this way, 83,000 KJ of energy or 203 liters of fuel oil are wasted. The Watt Energy-saving Automatic Condensed Water Recirculation Pump is specifically designed to handle condensed water at temperatures of up to 100°C. It operates using a float mechanism to drive the pump’s circulation, and it does not cause cavitation damage. It has no moving parts at high speeds, and it uses steam as its power source, eliminating the need for electricity, level control, or other mechanical components. All of these features simplify installation and ensure reliable operation over many years. When condensed water reaches the pump, it activates the float mechanism, thereby starting the pump’s circulation. This pump automatically adjusts to the amount of condensed water that needs to be pumped, adapting to fluctuations in the amount of condensed water in industrial steam systems.