Pressure Reducing Station - Operating Duration

Those figures suggest a continuous energy loss approaching 253kW.

Could a back-pressure turbine or a pressure exchanger be used instead of a pressure reducing station, in order to recover some of this energy?

The topic of the discussion is clearly shows the intension of the participant to avoid (optimize) any additional capital expenditure, be it pump,turbine or pressure exchnager etc AND whether pressure reducing station for continuous duty operation is recomended or not ?

At, say, £0.1GBP/kWh, there is an opportunity to recover over £220kGBP of energy. Capital cost is one of many considerations the original poster needs to consider in selecting the correct installation for the job at hand.

over £220kGBP of energy per annum

I am eager to learn more about pressure exchanger- This is something new to me, please provide basic operating principle.

Also, back pressure hydro turbine is again new thing.For steam application back pressure turbine is understood but for hydro turbine in will be interesting to add some more information.

Please help.

The cheapest way to drop the pressure and at the same time recover a lot of the power is to use a pretty standard Pump As Turbine (PAT). Plenty of information on the internet - try this one for starters

Very Nice & useful information regarding PAT, however here query has been asked by the participant not about energy saving or other possible alternative of mechanical equipment but technical recommendation & selection of continuous operating duty pressure reducing station.

Whether PRS can be recommended for continuous duty operation in cooling water circuit having silt level 2000 ppm to 5000ppm ?

Intriguing problem. Alas, I use non-SI units, so I will be doing a few conversions that should be checked.

First, the 20-to-6 bar reduction seems reasonable for a single stage. (300-to-90 psi in my world.) But hold it a minute: 300 psi x 2.31 ft/psi = 693 ft of head. What dam is this, anyway--Hoover, Three Gorges...?? Well, just a reality check.

650 m³/h x 265 g/m³ x 1 h/60 m = 2871 gpm. If we limit velocity to 4 ft/s to control pipe erosion with this amount of silt, we get 17.12-inch pipe; call it 450 mm or 18". The valve will be smaller. Flow = C_v x √ΔP; Cv = 2871/√(300-90) = 198.1; say 200.

I will come back to this again and look it up. I don't know what is available in abrasive-resistant regulators, which might entail elastomer rather than metal fluid-contact parts. In any case, this regulator won't be huge, and even a custom-built unit might be economical....

Well,to be more specific, whether with 5000 ppm silt level,does pressure reducing station can be recomended for feeding cooling auxiliary supply in hydroelectric project.

I don't know yet, but there might be ways to accommodate the silt problem. In particular, the elastomer-lined valve idea might have a fighting chance. (Just as a sandblasting hose is rubber-lined.) I really don't know why you are asking this question; although I haven't solved it yet, it is clearly on the agenda.

In the light of comments by PWSlack and TheProf, the pressure regulator approach I have been working on is not such a hot idea. You really would lose quite a lot of energy by just blowing it through a valve.

I understand the PAT concept, but I am not familiar enough with it to attempt a design selection. Now I'll go read some stuff.