Spontaneous condensation in flowing high pressure steam. by K. Zidi Download PDF EPUB FB2
Different from the isentropic expansion, in supersonic steam ﬂow non-equilibrium spontaneous condensation will occur in the form of “condensation shock” downstream of the nozzle throat at a certain value. Single- and two-ﬂuid models for steam condensing ﬂow modeling were introduced by Dykas and Wróblewski .
Gyarmathy, G., Burkhard, H. P., Lesh, F., Siegenthaler, A. Spontaneous condensation of steam at high pressure: first experimental results. Proceedings of Conference on Heat and fluid flow in steam and gas turbine plant,conference publication 3 (Institution of Cited by: The numerical simulations of condensation flow under low pressure and high pressure were also conducted to investigate the effect of inlet total pressure on the condensation characteristics.
Table 3 gives the boundary conditions in N3 nozzle. The pressure condition of No. N3 in Ji’s experiment is labeled as “Middle pressure”.Author: Wan Sun, Shuangtao Chen, Yu Hou, Shanshan Bu, Zaiyong Ma, Luteng Zhang. Cavitation is the term used to describe when condensate flashes into steam as it passes through a negative pressure in the eye of a centrifugal impeller.
Cavitation can be identified by a rattling like sound in the pump. It is the formation of steam pockets in the impeller eye. Condensate and flash steam (two-phase flow) discharging from a nonmodulating or elevated temperature process can operate in a pressurized condensate system.
A nonmodulating steam condition refers to a steam system process where no control valve modulates the steam flow into the process to maintain a desired temperature or pressure.
When the condensate flow reduces the float falls and closes the main valve, thus preventing the escape of steam Thermodynamic traps contain a disc which opens to condensate and closes to steam. In bimetallic thermostatic traps, a bimetallic element uses the difference in temperature between steam and condensate to operate the main valve.
Flashing lines also have two-phase flow — carrying both drained condensate and flash steam generated by high-temperature condensate discharging into a lower-pressure system. Steam can also enter a condensate system when steam traps require maintenance and leak, when bypass lines are open, or when outlet control valves remain open.
High pressure steam admitted through G-1 had pressurized the steam main and was sitting atop the condensate on the north side of C The south side of the valve was also under steam pressure which, based on testimony, was likely slightly less that that on the north side.
The flow of steam is typically much faster in steam distribution piping than in equipment and can reach speeds of over 30 m/s ( ft/s). At these speeds, when the cross-sectional area of a pipe section is completely filled by water, slugs of condensate can be carried through the piping at high velocity causing water hammer, which can cause.
Condensate pots play a key role in maximising the accuracy of differential pressure flow measurement on steam or vapour applications. When installed correctly, these simple devices can significantly improve flow measurement accuracy in differential pressure measurement systems by providing an interface between the vapour and liquid phases.
Gravity or atmospheric (condensate line pressure maintained at or close to zero psi) 2. Low pressure (1 to 15 psi) 3. Medium pressure (16 to 99 psi) 4. High pressure ( psi or higher) Pressurized condensate technology is not new since these systems can be documented back to Though the technology may be considered old, it has been.
As steam condenses in a process, flow is induced in the supply pipe. Condensate has a very small volume compared to the steam, and this causes a pressure drop, which causes the steam to flow through the pipes.
The steam generated in the boiler must be conveyed through pipework to the point where its heat energy is required. The unit is cross compound with single-flow, high-pressure and double-flow, low-pressure sections with in.
last-stage buckets at rpm and side exhaust to the condensers. The generators. According to the nucleation theory, working fluid experiences spontaneous non-equilibrium condensation in the wet expansion in a Laval nozzle, and this process is more complicated in a turbine with a high speed radial-inflow, which consists of three expansion components, the nozzle ring, vaneless space and rotor, and one pressure recover component, the diffuser.
A High-Resolution Numerical Method for Transonic Non-Equilibrium Condensation Flows Through a Steam Turbine Cascade,” Sixth International Symposium on Computational Fluid Dynamics, Lake Tahoe, NV, Sept. 4–8, pp. High pressure condensate can flash to steam in low pressure condensate systems causing problems with their operation and wasting steam.
Use a flash steam recovery system to flash high pressure condensate to steam and then inject the steam into the low pressure steam system. Supply Lines and Condensate. The pressure and the droplet radii distribution fit well with the experimental data for both the high pressure nozzle and the low pressure nozzle.
The S2 calculation method is also employed to predict the performance of a 3-stage low pressure steam turbine with spontaneous steam condensation, and the reasonable results are obtained. condensate flow both in steam and condensate pipelines.
In this study, major components of steam condensate system are presented, followed by a discussion of most common problems with condensate, such as water hammer, flash steam, pipe erosion and so on.
For optimum. Table Properties of Saturated Steam (Abstracted from Keenan and Keyes, THERMODYNAMIC PROPERTIES OF STEAM, by permission of John Wiley & Sons, Inc.) Col.
1 Gauge Pressure Col. 2 Absolute Pressure (psia) Col. 3 Steam Temp. (°F) Col. 4 Heat of Sat. Liquid (Btu/lb) Col. 5 Latent Heat (Btu/ lb) Col. 6 Total Heat of Steam (Btu/lb) Col.
7 Specific. The spontaneous condensation process takes place in many power engineering machines and devices, such as steam turbines, supersonic separators, ejectors etc.
Equipment vulnerable to erosion includes turbine blades, low-pressure steam piping, and heat exchangers that are subjected to wet steam. Feedwater and condensate piping subjected to high-velocity water flow are also susceptible to this type of attack.
Damage normally occurs where flow changes direction. METALLIC OXIDES IN BOILER SYSTEMS. Provide high pressure steam valve 12” and larger with an equalizing bypass valve assembly. Provide Flexitallic Model CG spiral-wound gaskets for steam and condensate flanged piping service.
PART 2: PRODUCTS Steam Piping: A. High pressure steam: 1. Piping shall be Schedule 80 seamless domestic black steel piping. Flow model Governing equations Wet steam is assumed to be a mixture of vapour at pressure p, temperature T g and density ˆ g, and liquid phase at the same pressure, temperature T l and density ˆ l.
The liquid phase consists of large numbers of spherical liquid droplets of various sizes (radius r). The wetness fraction y is given by: y.
low-pressure steam. Estimates the cost effectiveness of installing appropriate heat-recovery devices and interconnecting piping. High-Pressure Condensate Flashing High-Pressure Condensate, psig Percent of Condensate Flashed, lb steam/lb condensate Low-Pressure Steam, psig 50 30 15 5 A new dual-fluid model was proposed considering the phase transition along with the velocity slip between phases.
Based on this dual-fluid model, numerical simulations were conducted on the flow field in 2D Laval nozzle as well as in Bakhtar cascade. The simulated results were shown to be of high consistency with the experimental results, but the existing difference still implied that the.
As the traps cycle, high temperature condensate flows to High Pressure Condensate (HPR) receiver. Pressure in the HPR is maintained slightly below the lowest steam user in the system to facilitate the flow of condensate from the steam traps to the HPR.
When steam is generated in the boiler, the carbonates decompose and produce C02 gas which is. The steam's latent heat of condensation is passed to the water flowing through the tubes of the condenser.
After the steam condenses, the saturated liquid continues to transfer heat to the cooling water as it falls to the bottom of the condenser, or hotwell. This is called subcooling, and a certain amount is desirable.
The authors also determined the regions of unstable flow of the condensate film. The results of a theoretical and experimental study of high-speed condensation of steam at a low-pressure steam turbine are presented in Ref.
A comparison of theoretical and experimental results confirms the reliability of the theoretical model. Steam will flow from pan A via the condensate drain line to the other pans to equalise the pressures, and the condensate from the other pans will have to flow against this steam flow.
When the drainage points of different vessels at different pressures are connected to one trap, the vessel with the highest pressure (in this instance pan A) will impede the flow of condensate from the others. Water hammer in condensate transport piping occurs in many patterns, which are fundamentally all caused by the sudden condensation of steam.
The three most common patterns are discussed below. Chugging. When two transport lines converge, high-temperature flash steam can come in contact with low-temperature condensate.
Figure 9: Pressure caused by air or condensate lifts the disc permitting flow through the trap. Figure When steam arrives at the inlet port, blowby at a high velocity creates low pressure under the disc.
Some of the flashing condensate is blown past the disc into the upper chamber, forcing the disc downward. Figure Further flow is stopped.6.
Ensure both condensate pots are mounted at the same level. The higher connection point should be the reference. Consider both Vertical and horizontal steam pipelines.
7. The differential pressure measuring device (DP) should be mounted below both the condensate pots and the steam pipeline.
8.Flash Steam Venting • High pressure condensate discharge to open receiver • Install flash tank(s) (increase the back pressure to the existing system) and route to a lower pressure steam header or a specific user • Install a thermal compressor (keep the same back pressure to the existing system) to boost the vent/flash steam pressure to a.