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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Please provide me more detailss…. In actual practice, you cannot permit the desuperheater outlet temperature reach saturation temperature since you have no idea of the quality of the fluid other that it could be all saturated liquid, all saturated vapor or some mixture of the two states.
The disadvantages include the potential for carryover of water into piping and tube bundles harpsand the significant distance of the measured setpoint from the spray-water injection point. Others use a combination of steam and fuel flow that boilrr spray flow based on the relative difference between fuel and steam flows.
September 18, at ni Multiple cracks are observed on the surface as well as on the weld joint of the spray nozzle dislodged from the attemperator. Author links open overlay panel Goutam Mukhopadhyay Sandip Bhattacharyya.
Modern PID control blocks allow you to expose the tuning settings to be connected to external signals.
Failure analysis of an attemperator in a steam line of a boiler – ScienceDirect
The spray pattern was ineffective. A characterizer can be used very effectively in feedforward control where the relationship between the disturbance and the required compensating control action is nonlinear.
I read the article and found it to give an objective assessment on APC in power plants. Jacques, Thank you for article, curious to know how I can implement gain scheduling in Yokogawa.
If you have disturbances affecting your reboiler, then yes, consider using cascade control. This loop measures boilfr desuperheater outlet temperature and manipulates the control valve position to match bouler desuperheater outlet temperature to its set point coming from the main steam temperature controller Figure 2. The gain of the desuperheater outlet temperature loop will be affected greatly by steam flow rate.
Would such a cascade arrangement be practical work for, say column overhead temperature master to reboiler steam temperature slave? But for secondary atomization to occur, the dynamic forces acting on a droplet must be greater than the viscous forces holding the droplet together and depends on the relative velocity between the steam and water droplet. Variable-area probe-style attemperators were a popular choice for low- to medium-flow applications and sometimes still are when orders for plants powered by gas turbines surged in the late s Fig 8.
The material is found to be nickel based Inconel as obtained by chemical analysis. So even a 2: In the plant where I worked, the main and re-heat steam temperature control loop is cascade without feedforward demand. There are scores of superheater and reheater surface arrangements, many unique.
One of the reasons many superheaters and reheaters are not working as envisioned is because they were designed for operating criteria that never materialized. Yet other systems e. A reheater attemperator is not shown, although one exists. Atgemperator addition, at high loads the pressure differential between the feedwater pump discharge and steam pressure will be lower, reducing the spray flow rate for a given spray valve position assuming the absence of a flow control loop on the desuperheater spray flow.
Final-stage or terminal attemperators can be another component of concern. Difference between attemperator and desuperheater thanks all, very informative comments and helps a lot. Hi All, What are the technical differences between an attemperator and desuperheater. Join your peers on the Internet’s largest technical engineering professional community. With apologies to E F Hutton, when Bob Anderson talks about heat-recovery steam generators most everyone listens.
May 8, at 7: Independent voice of the gas-turbine-based generation sector. Instead, it will accumulate below the lower headers and possibly flow up into the harps—a condition conducive to extensive tube failures.
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. It is is very informative detail. Adding to the challenge, steam temperature is affected by boiler load, rate of change of boiler load, air flow rate, the combination of burners in service, and the amount of soot on the boiler tubes.
If the spray water flow rate to the attemperator is measured, a flow control loop can be implemented as a tertiary inner loop to provide very fast disturbance rejection.
Difference between attemperator and desuperheater An attemporator controls steam temperature while a desuperheater removes whatever superheat there is in steam and reduces the temperature to a point at or nearly at saturation temperature.
Water injection boiker done in a device called an attemperator or desuperheater. But cascaded reboiler outlet temperature control could be very beneficial too. Overspray is generally defined as an attemperator outlet steam temperature of less than 50 deg F above the prevailing saturation temperature.
Or at least the ones I put in had to. It’s easy to join and it’s free. To present it in a block diagram, it will look similar as in the figure above, except you will have three function generator or f x blocks, one for each of the tuning settings.
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November 12, at 6: Promoting, selling, recruiting, coursework and thesis posting is forbidden. Designers must ensure total evaporation ahead of the temperature sensor in the steam outlet pipe refer back to Fig 1.
In addition to specifying that the attfmperator flow-control element be located outside the hot steam environment, engineers at Control Components Inc, Rancho Santa Margarita, Calif, suggest adding a thermal barrier to separate the hot and cold working elements to mitigate the intensity of thermal cycles experienced by critical components Fig This control loop kn be tuned for the fastest possible response without overshoot, but even then the loop will respond relatively slowly due to the long dead time and time lag of the superheater.
Firstly, I cannot thank you enough for this incredibly educational and useful website. Anderson next explained how attemperation works and what can go wrong with any desuperheater system, including the following:.
August 24, at 2: Students Click Here Join Us! Moreover, how can I represent integrated gain scheduling feedback loop in the form of controller bolock diagram.
You can touch upon the integral windup problem frequent in STC.