Discussion on steam condensate recovery

I think this solution is feasible; there is no need to use a closed system for the recycling of condensate water, as closed systems make it difficult to maintain stable pressure and temperature within the system. Additional measures such as level detection and flow control for pumps and valves can be implemented in such systems.

Hello, the original poster. What do you mean by safe discharge of closed-type condensate water? Are there any safety risks associated with the discharge process of condensate water?

What I’m referring to is a situation that may arise: in different processes, the required quality of steam may vary (in terms of pressure and temperature), and the pressure and temperature of the condensate water produced after steam does work will also differ. In such cases, if a closed-loop condensate recovery system is used, the fact that the condensate storage tank is under certain pressure may prevent high-quality condensate from being discharged properly. I’m not sure if my reasoning is sound; I hope experts can give me some advice!

I have an idea for this situation; take a look and see if there are any issues. Condensate water at different pressure levels entering the collection tank can be considered in two scenarios: In one scenario, the pressure difference between the various streams of condensate is small; in such cases, desalinated water can be sprayed inside the collection tank from above before being sent to the boiler system. One scenario is when there is a large pressure difference (that is, there is high-pressure condensate inside). In such cases, the high-pressure condensate can first be flashed; the resulting steam can be sent to other places where it can be utilized. The condensed water after flashing, along with the condensate at lower pressures, goes into a collection tank. Desalinated water is sprayed from above within this tank, and then the liquid is sent to the boiler system. We used to do it this way; since we weren’t very familiar with lithium bromide refrigerators, we weren’t quite clear about the advantages of the approach mentioned by the original poster. Could the original poster explain the principle and operation process of lithium bromide refrigerators?

This post was last edited by Miaomiao Tiandi Yishaou on June 19, 2012, at 22:10. The original poster’s reasoning is correct; it’s indeed not advisable to implement a closed-loop recovery system. This is especially true for large systems where condensate water from different pressure levels gets mixed together—implementing a closed-loop system would only lead to trouble. It would be better to find a professional specializing in lithium bromide units to develop a plan. But what about using lithium bromide units in summer? What to do in winter? Heating? It seems like a huge project.

What you’re concerned about makes sense; it would be best to use it for process cooling, to replace some screw compressors.

What the brother mentioned is also a good method, as the latent heat of condensate water is fully utilized as well. Actually, the reason I considered lithium bromide refrigeration is to make use of the heat value gradient of the condensate water, thereby reducing the enthalpy loss during the condensate recovery process. Because we know that, no matter what recycling method is used, the temperature of the condensate water when it enters the deaerator is 10–20 degrees lower than its temperature before being collected. If we use the condensate water from steam at a high temperature of 90–100 degrees to drive lithium bromide refrigeration, and then send the condensate water at around 65 degrees back to the deaerator, wouldn’t the heat loss during transportation be reduced? I don’t know much about the principle of lithium bromide; I only know that it is used for cooling through heat. The hot water with a temperature of over 70 degrees recovered from the factory can be used to produce cold water at 7–15 degrees, which is then used for the first stage of cooling in the process in order to reduce the power consumption of the screw motors.

If the pressure inside the tank is low (lower than the pressure of the condensate entering the tank), condensate at various pressures can enter the tank, and the flash vapor can be extracted via entrainment for reuse. I’m not sure if it’s feasible.

From an energy-saving perspective, things become much clearer. Firstly, it is possible to achieve complete recycling of condensate water. Our company has carried out many such project modifications, and the temperature of the water used to feed the boilers can reach 130 degrees. The return pipelines of all steam-using equipment can be collected together and fed into a recovery system, but it is necessary to ensure that the pressure in the recovery system is lower than that of the lowest-pressure steam-using equipment; otherwise, it will affect the return water pressure of those devices. I’m not very familiar with the lithium bromide units mentioned by the original poster; according to industry experts, they are units that use steam for cooling. What you mean by using this unit for cooling is essentially to make use of the low-pressure steam. However, true steam energy savings were not achieved. True energy savings mean that if a production line originally used 100 tons of steam per day, it uses 90 tons per day after the modification – that is energy saving. After cooling with lithium bromide units, the production line still uses 100 tons of steam per day; however, the workshop is able to be cooled as a result. The fully enclosed recycling system we use incorporates two types of energy-saving methods: 1. All return pipelines are connected to the recycling system for water-vapor separation; the vapor produced is then used to supply equipment that requires steam, thereby reducing or eliminating the need for fresh steam and achieving energy savings. 2. The condensate water, which has been cooled after the flash steam is extracted and is at a temperature of around 100–130 degrees, is then fed back into the boiler using a high-temperature pump designed to prevent cavitation, with all processes taking place in a fully sealed environment. This reduces the fuel costs required to raise the boiler’s make-up water temperature from 20 degrees to 100–130 degrees, and eliminates the cost of desalinated water. By combining the energy savings from these two aspects, we can help enterprises achieve energy savings of around 10-25% of their total steam consumption costs. If any experts have doubts about the views I’ve expressed, feel free to leave a message or contact me via WeChat or phone number listed below to discuss it

This solution seems to be the most reliable for now. However, the problem for our company is that there is no place where the steam can be reused; currently, the high-pressure and low-pressure systems are combined, and it is necessary to release steam and pressure in order to enable successful recovery. True closed-loop recovery is not possible, which is quite problematic. We have consulted many manufacturers, and all of them say it is not feasible