Benefits and methods of condensate recovery

Benefits and methods of condensate recovery

1. Why should we recycle condensate

　　Steam as a clean and safe energy carrier is widely used in various industries. After the steam releases the latent heat of vaporization in the steam-using equipment, it becomes saturated condensate at almost the same temperature and pressure. Since the use pressure of steam is greater than the atmospheric pressure, the heat of the condensed water can reach 25% of the enthalpy of evaporation, and The higher the pressure and temperature, the more heat the condensate has, and the greater the proportion of the total heat of steam. It can be seen that recovering the heat of condensed water and using it effectively has great potential for energy saving.

　　 2. The benefits of condensate recovery

　　 (1) Save boiler fuel (2) Save industrial water (3) Save boiler feed water cost (4) Improve factory environment, eliminate steam cloud and fog (5) Improve boiler actual thermal efficiency

　　 3. How to recover condensate

　　The condensate recovery system recovers the high temperature condensate discharged from the steam system, which can maximize the use of the heat of the condensate, save water and fuel. Condensate recovery system can be roughly divided into open recovery system and closed recovery system.

　　 open recovery system is to recover the condensed water into the boiler feed water tank. In the process of condensate recovery and utilization, one end of the recovery pipeline is open to the atmosphere, that is, the condensate water collection tank is open to the atmosphere. When the pressure of the condensed water is low and the reuse site cannot be reached by self-pressure, the condensed water is pressure sent by a high-temperature water pump. The advantages of this system are simple equipment, convenient operation, and small initial investment; but the system occupies a large area, the economic benefits obtained are poor, and the environmental pollution is large, and because the condensed water directly contacts the atmosphere, the dissolved oxygen concentration in the condensed water Increased, easy to produce equipment corrosion. This system is suitable for small steam supply systems, systems with small condensed water and less secondary steam. When using this system, the discharge of secondary steam should be minimized.

　　 Closed recovery system is that the condensate collection tank and all pipelines are under constant positive pressure, and the system is closed. Most of the energy contained in the condensed water in the system is directly recovered into the boiler through certain recovery equipment, and the recovered temperature of the condensed water is only lost in the cooling part of the pipe network. Due to the closure, the water quality is guaranteed, reducing the water treatment cost recovered into the boiler. . Its advantages are good economic benefits of condensate recovery and long working life of the equipment, but the initial investment of the system is relatively large and the operation is inconvenient.

　　4. How to choose the recycling method

　　 For different condensate renovation projects, the choice of recovery method and recovery equipment is a crucial step in whether the project can achieve the investment objective. s*First, the condensate volume of the condensate recovery system must be accurately grasped. If the condensate volume is not calculated correctly, the diameter of the condensate pipe will be selected too large or too small. Secondly, it is necessary to correctly grasp the pressure and temperature of the condensate water, the method, equipment, and pipe network used in the recovery system are all related to the pressure and temperature of the condensate water. Third, the selection of traps in the condensate recovery system should also be noted. Improper selection of traps will affect the pressure and temperature of the condensate recovery system, as well as the normal operation of the entire recovery system.

　　 When selecting a system, it is not that the higher the recovery efficiency, the better, but also economic issues, that is, while considering the waste heat utilization efficiency, the initial investment must also be considered. Due to the higher efficiency of the closed recycling system and less environmental pollution, it is often given priority.

　　 5. Thermal economy analysis of condensate recovery project

For the closed condensate recovery system, investment is mainly used for trap unit, return water pipe network and recovery equipment-pumps, hot water tanks, heat exchangers, expansion vessels, high-performance recovery devices, etc., as well as heat preservation and pipe network materials , Technical services, engineering construction costs, etc. The economic benefits of recycling projects are analyzed from the following aspects:

　　1) The closed recovery system is operated in a closed manner, and the pressure is increased to reduce the benefits of steam leakage;

　　 2) Recycling of condensed water to save the value of softened water;

　　3) The condensate recovery increases the boiler inlet water temperature and saves fuel consumption.

　　 Of course, there are certain social benefits. Usually, we use the investment recovery period often used in engineering technology to determine the rationality and feasibility of the project investment.

　　 VI. Conclusion

The steam condensate recovery method needs to be selected according to the application and the amount of condensate. The selection of the appropriate condensate recovery method not only makes the system design simple, but also eliminates the problems in the system operation and maintenance from the root cause, so that the steam The condensate recovery work can proceed smoothly.