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  1. Drexl

    Pressure drop - low quality steam at low pressures

    Hi, I was wondering if anyone know a proper pressure drop correlation for 1. Low quality steam x=0.1-0.3 2. Low pressure 0.2-1.5 bar(a) I have a flash tank connected to the condenser by a short pipe. At a disturbance case I expect extreme flow to the tank and would like to calculate what the...
  2. Drexl

    Power plant water chemistry literature

    Hi, I'm looking for comprehensive and modern literature on power plant water chemistry. Anyone have any suggestions? What i'm looking for: -History/evolution of water treatment -Used treatment programs -Used chemicals -Description of mechanisms - stress corrosion cracking, FAC, pitting, erosion...
  3. Drexl

    Steam turbine - sudden temperature change

    Hi, I'm looking at having two boilers connected in parallel that are delivering steam at different temperatures. If one of the boilers trip, I get a sudden drop in mass flow and a sudden change in temperature of the live steam. Would any turbine specialist be so kind to give some guiding values...
  4. Drexl

    Gland sealing steam

    Hi, Could someone describe in reasonable detail why a high pressure steam turbine needs gland sealing steam supply? Drex
  5. Drexl

    PED classification of branch pipes

    Hi, PED category for pipes (I-III, SEP) is selected based on medium, maximum allowable pressure and nominal size. Does there exist a consensus regarding where to draw the border between categories at branch-off pipes? For example a DN250 feedwater pipe with a DN50 branch off. 1. First...
  6. Drexl

    Turbine bleed pressure

    Hi, I was wondering how high of a pressure the turbine bleeds, extraction piping and pre-heater can experience in case of blocked passage after the pre-heater (assuming no safety valves on the pre-heater shell sides). To formulate the question in another way, what would be a good design basis...
  7. Drexl

    Control valve range

    Hi, Does anyone know any respectable source for range (of travel or Kv/Cv) in which different types of control valves can perform well. One rule of thumb i've heard is 10%-90% of travel, but i'm looking for something more comprehensive on the topic. best regards Drex
  8. Drexl

    Back-pressure

    Hi, I have a safety valve including inlet and outlet piping and can say that the system is ok (<3% inlet loss, <10% outlet loss) with a superimposed back-pressure equal to atmosphere. If I lower the superimposed backpressure, e.g. the pressure in the tank in which the safety valve outlet pipe...
  9. Drexl

    Restriction after control valve

    Hi, I have an installation with restrictions after control valves and I'm looking to calculate pressure drop vs flow for all of them. The type of restrictions are: 1) Perforated plates with various amount of holes and hole diameter 2) Tank diffuser, pipe extends into tank and has large number...
  10. Drexl

    Turbine in plant simulation

    Hi, I'm doing a general simulation of a power plant and was looking for a GENERAL model for the turbine. Basically the turbine is modeled as P = em * et * ms * (hin - h'out) P : Electrical power (kW) em : Mechanical efficiency et : Thermodynamic efficiency ms : Steam mass flow (kg/s) hin ...
  11. Drexl

    Solubility of gases at higher temperatures

    Hi, I was wondering if anyone knows any sources for solubility of gases such as hydrogen, oxygen and nitrogen in water at elevated temperatures, 20-300 degC? thanks Drex
  12. Drexl

    Erosion/corrosion rate

    Hi, I'm preparing for a meeting where we are reviewing a piping system including steam and condensate piping. All carbon steel pipes have an corrosion/erosion allowance of 1 mm. I would like to evaluate if this assumption is reasonable. Do you know of any reference (hopefully a standard) that...
  13. Drexl

    HP Piping material

    Hi, I'm wondering roughly in what pressure/temperature ranges it is reasonable to use the following materials for piping in boiler plants. P235GH P265GH 16Mo3 13CrMo4-5 10CrMo9-10 Reasonable involves availability in europe, price and of course material properties. thanks for replies,
  14. Drexl

    Pressure drop over valves

    Hi, I had two questions regarding pressure drop in valves, hopefully quite easy for you guys. 1. I'm performing a pressure drop calculation on various pipes, still in early design stage. Valve types are specified but no exact models, so I can't ask the manufacturer for Kv-values. I have used...
  15. Drexl

    Safety valve specification

    Hi, I'm reviewing some safety devices for boiler and piping system according to european standards (EN 754-7..). The set pressure of the safety valves is the design pressure of the system, and the pressure can exceed this by 10% when the safety device is operating. The standard specifies that...
  16. Drexl

    Pressure - temperature rating for piping components

    Hi, I'm designing a piping system for steam, say with Design pressure 12 bar(g) Design temperature 200 degC Material P235GH Picking flanges according to EN 1092 is very easy. I just look at the one PN-class at the time until i find one that satisfies my pressure/temperature combination. But...

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