How to recover steam condensate water

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How to recover steam condensate: Steam turns into condensate after releasing heat. The quality of steam condensate makes it highly suitable as boiler feed water. Moreover, high-temperature condensate contains a large amount of heat; making effective use of steam condensate can significantly improve the efficiency of the entire steam system. The most common use of condensate is to pump it into the boiler feed tank or deaerator. 1. The equipment or process is located far away from the boiler room. 2. The condensate water needs to be lifted to a higher position. 3. A negative pressure may exist in the steam space. If the temperature of the condensate water is low, there will be only water in the discharge pipeline of the condensate water pump; therefore, when selecting it, it is sufficient to consider the amount of condensate water without taking secondary steam into account. The flow rate used in selection is the pump’s discharge rate. For long pipelines (over 100m), pipeline friction and inertia must be taken into account. The flow rate of water in the recovery pipe is usually higher than that in the drain pipe. This will result in a smaller pipe size, but it will also increase friction losses. Therefore, it is necessary to ensure that the back pressure of the condensate water system does not affect the pump’s displacement. There are two basic types of pumps, and Hangzhou Watt Energy Saving Engineering Co., Ltd. believes that each has its own advantages and applications; a brief introduction to each will be provided below. Electric centrifugal pumps use centrifugal force to pump liquids. Typically, the impeller is installed inside the volute, and its high-speed rotation generates pressure energy. The liquid entering the pump is directed toward the center of the rotating impeller. At this point, the liquid gains high speed. The design of the pump’s volute enables kinetic energy to be converted into pressure energy to the greatest extent possible. Centrifugal pumps are the most common; they are suitable for a variety of applications, whether with hot or cold water. Therefore, it is often used as a condensate water recovery pump. This type of pump is most suitable for situations where a large amount of condensate needs to be recovered. For example, when recovering condensate from the collection points of many process streams, electric pumps are the natural choice. However, when the temperature of the condensate water approaches the saturation temperature, cavitation occurs in the electric pump. Electric pumps are usually combined into a complete set of equipment known as a condensate recovery system, which includes: · a water storage tank · a control system operated by sensors or floats · one or more pumps; in the case of a single-pump system, the capacity of the pump should be 1.5 times that of the recovery system. For a dual-pump system, the rated capacity of each pump is 1.1 times that of the recovery system. For dual-pump systems, a cascade control system is required to manage the operation of the pumps. One of the pumps serves as the working pump, while the other is a backup pump that is used when the amount of condensate water exceeds the processing capacity of a single pump. By using level control, when the working pump fails, the water level in the tank rises, thereby switching to the backup pump. Increasing the pump’s displacement is mainly done to: · Take into account the starting conditions · Provide a safety factor. Watt mechanical pumps can be used in almost all applications where electric pumps are used, and they are particularly suitable for condensate applications. A mechanical pump includes a pump body (into which condensate flows by gravity), a float, and an automatic mechanism (that activates a set of valves). When steam enters the pump, the condensate is forced out and flows through the outlet check valve to the recovery pipe. Subsequently, the mechanism acts to open another valve, releasing steam (or compressed air), allowing more condensate to re-enter the pump. Watt mechanical pumps do not require electricity. There are also no issues with wear or leakage of the bearing seals, nor motor burnout. Installation has become simpler, and there is less need for maintenance. Mechanical pumps can also handle saturated condensate without experiencing cavitation issues. In pressurized (closed) systems, where the temperature of the condensate is above 100°C, mechanical pumps can also be used. In a vacuum condition, electric pumps will be ineffective, while mechanical pumps can still function. It should be noted that, due to the cyclic motion of the pump, a water tank is required for mechanical pumps. When the pump drains water, condensate cannot enter the pump body; therefore, a tank is necessary to store the condensate generated in the pump’s circulation area. Typically, mechanical pumps handle less condensate water than electric pumps. Mechanical pumps demonstrate their value in the following situations: · when the condensate water is under vacuum · in spaces with limited space (mechanical pumps require less maintenance, which is an advantage) · in hazardous environments · in areas without power supply. Like electric pumps, Hangzhou Watt’s mechanical pumps are also available as complete sets, usually including a tank and a pump. Since the pump operates automatically, no additional control system is required. This also means that the pump is completely self-regulating. Compared to electric pumps, the selection of mechanical pumps is more complex, as the flow of condensed water in the recovery pipe is intermittent. The pump operates in a cycle as the tank fills or empties. Thus, the instantaneous flow rate of water discharged by the pump can be several times the amount recovered per hour. The instantaneous flow rate is what needs to be used when selecting the diameter of the drainage pipe. It can be seen that the approaches to choosing mechanical pumps and electric pumps are completely different.