20 Nov Most attemperation that I am familiar with in this setting is to spray water into the steam line in the boiler, before it gets to the turbine. There are temperature limits . Product – DAM-B Steam Attemperator. DAM-B: Steam AttemperatorAttemperation is the primary technique used for controlling the degree of superheat in a boiler. Spray flow attemperator is used for controlling superheater outlet steam temperature in power house. The attemperator undergoes cyclic thermal load and.
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This is slightly off topic but still relevant question for Control engineers at a time when Advanced process control schemes are becoming more prevalent. Unfortunately, turbines and superheater tubes do not like water. Yet other systems e. Emerson Ovation require you to place a scaling block between the two controllers.
The process dead time of the superheater increases with a decrease in boiler load because of the slower rate of steam flow at lower loads. The ring design also ensures distribution of spray flow across the entire cross section of steam flow. After separation from the boiler water in the drum, the steam is superheated to improve the thermal efficiency of the boiler-turbine unit.
To compensate for this, a feedforward control signal from the boiler master to the steam temperature controller can be implemented. Are you an Engineering professional? Because of the changing dead time and lag of the superheater, the integral and derivative times must be scheduled in addition to the controller gain. Is the use of a Model predictive controller to provide set-points to the spray control valves for steam temperature control a cost effective approach?
Water injection is done in a device called an attemperator or desuperheater. Resources Few production environments have the luxury of ordering new equipment to replace existing machines on their shop floor. Posting Guidelines Promoting, selling, recruiting, coursework attempsrator thesis posting is forbidden.
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Steam Temperature Control | Control Notes
A characterizer can be used very effectively in feedforward control where the relationship between the disturbance and the required compensating control action is nonlinear. Ravi, there are several designs for this feedforward of which some seem to work better than others depending on the particular situation, boiler design, fuel type, attempeator. At first, the main and re-heat steam temperatures swinged and it affected MW and steam pressure.
Difference between attemperator and desuperheater Isn’t this semantics?
Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework. Overspray, or the introduction of unvaporized spray water into downstream harps, causing damaging thermal transients. Promoting, selling, recruiting, coursework and thesis posting is forbidden.
Spray flow attemperator is used for controlling superheater outlet steam temperature in power house. Anderson showed cutaway drawings of a few other attemperators of the multi-port mast type, some designs quite involved, but all with serious limitations in cycling service. By joining you are opting in to receive e-mail.
Designing HRSG desuperheaters for performance and reliability
So how can we generate the feed forward signal logic from the fuel flow or boiler master demand to compensate this deviation? Anderson pointed to boiled as the leading cause of piping failures in combined-cycle plants.
In Fig 5, the long runs of piping connecting primary and secondary superheaters and reheaters have only one drain each. The investigation consists of visual inspection, chemical analysis, characterization of microstructures, energy dispersive spectroscopy, measurement of hardness and fractography. Attemperxtor the desired outlet temperature.
Presence of chromium carbide precipitations are observed inside the grains and along the grain boundaries. With apologies to E F Hutton, when Bob Anderson talks about heat-recovery steam generators most everyone listens. In the plant where I worked, the main and re-heat steam temperature control loop is cascade without feedforward demand.
The spray water comes from upstream of the feedwater control valves, and changes in feedwater control valve position will cause changes in spray water pressure, and therefore disturb the spray water flow bokler. The Eng-Tips staff will check this out and take appropriate action.
However, here the pipe housing the attemperator is too short to permit adequate residence time for evaporation at high spray flows.