A proper FSS unit design is to be made in accordance with local regulations prior to a FSS unit installation. All necessary additional pipeline ancillaries, safety and control devices are to be included in order to ensure safe and long-term operation of equipment. |
In most applications of the FSS unit, the presence of a PRLS bypass group in the configuration is necessary. Exclusion of the PRLS group from the configuration is possible only if the circuit into which the separated flash steam is discharged is equipped with its own bypass device, or the steam is simply discharged into the atmosphere. In all other cases, the absence of a bypass group can lead to an uncontrolled increase in pressure in the separator vessel and termination of condensate drainage from the steam-using equipment. |
Setting the opening pressure of the valve, which is part of the PRLS group, determines the maximum working pressure of the secondary boiling steam in the separator vessel Pfs, which, in turn, determines the amount (fraction) of flash steam. To determine the proportion of flash steam, you can use the chart below. It is necessary to know the condensate pressure before the trap Pc installed on the steam consumer at maximum load, and also to set the value of the flash steam pressure in the separator vessel Pfs. As an example, the diagram shows the situation when the pressure before the condensate drain is 7.5 barg, pressure in the separator vessel is 0.5 barg. Under such conditions, about 0.12 kg of flash steam per 1 kg of condensate will form, or 12%. If several consumers are connected to one separator vessel, for each of them it is necessary to make a separate calculation and then add the results. |
If it is planned to utilize the heat of as much of the flash steam as possible (for example, before condensate enters the vented tank), then, as can be seen from the diagram, the pressure of the flash steam in the Pfs vessel should be as low as possible so that the greatest possible amount of low-grade steam is formed. At the same time, the lower the steam pressure in the separator vessel, the more difficult it is to use this steam in the process. In addition, the performance of some plants, for example, thermocompression units, significantly depends on this value. It is especially necessary to carefully consider cases where among consumers there are packages, the condensate from which is discharged into the vessel, in which the steam consumption depends on the temperature of the medium being heated (various heating circuits with temperature control – pasteurizers, air heaters, air conditioners, etc.). For the correct choice of the vapor pressure in the separator vessel, contact the specialists of Steam Control Engineering, LLC (OOO). |
In the case when the FSS unit is used for direct return of condensate to the boiler (FSS-…/PMTe configuration), the pressure in the separator vessel Pvp should be as high as possible in order to preserve the temperature and energy potential of the condensate and to minimize the amount of flash steam, for utilization of which it is necessary to find a consumer of thermal energy. For the correct choice of the vapor pressure in the separator vessel and the unit configuration, contact Steam Control Engineering, LLC (OOO) specialists. |
FSS-../STm and FSS-../-STe configurations are used when the liquid phase is discharged from the vessel into the circuit, where there is no backpressure, for example, into an open vented tank. Even under such conditions, it is desirable to place the vessel itself and the trap above vented tank to provide condensate drainage under the influence of gravitational forces at launch moments or in other cases when pressure in the separator vessel is close to zero. |
The FSS-HEX-.. configurations can be used to organize a heat recovery system for continuous purging of steam boilers or the liquid phase of contaminated condensate, which is impractical to return for reuse in the boiler room. At the same time, if it is planned to send the separated flash steam to the atmospheric deaerator, it is advisable to include the PRLS group with the pressure setting slightly higher than the nominal pressure in the deaerator (for example, if the nominal vapor pressure in the deaerator is 0.2 barg, then the opening start pressure for PRLS group valves should be taken at 0.25-0.27 barg). Otherwise, there may be situations where the flash steam will not be disposed of in the deaerator, which will lead to the triggering of the safety valve installed on the deaerator. |