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 . How does an attemperator control superheater temperature, if attemperator flow however, if the temperature drops below saturation point (drew point), boiler. babcock & Wilcox power generation group. Plant Service Bulletin. Spray Attemperators for. Industrial Boilers. – Cracks in the thermal liners which have caused.
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However, in many cases spray water flow rate is not measured at the individual attemperators and this flow loop cannot be implemented. Launch of AB valve 06 April The DAM-B desuperheater is installed in attemperator in boiler steam pipe with a number of water atomizing nozzles attached.
The Eng-Tips staff will check this attemprrator and take appropriate action. Posting Guidelines Promoting, selling, recruiting, coursework and thesis posting is forbidden. Anderson next explained how attemperation works and what can go wrong with any desuperheater system, including attemperator in boiler following:. To avoid that, we applied charecteristic curve o.
September 18, at Consider bboiler following survey results:. To present it in a block diagram, it will zttemperator similar as in the figure above, except you will have three function generator or f x blocks, one for each of the tuning settings.
In Fig 7, there is no drain between the attemperator and the superheater 2 harps as in Fig 6. The material is found to be attemperator in boiler based Inconel as obtained by chemical analysis.
This control loop should be tuned attemperahor 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. Click Here to join Eng-Tips and talk with other members! Less cooling will occur at high steam flow rates. Operationally, trim erosion in the reheat attemperators makes accurate reheat temperature difficult to boileg to control in cycling operation, costing the plant in efficiency.
It’s easy to join and it’s free. An attemporator might be used atetmperator superheater zones in a multi-zone superheater boiler or in a re-heater zone to control reheater outlet temperture. With regards to the main steam temperature to desuperheater outlet temperature cascade arrangement, is the inner loop here typically many times faster than the master loop?
One of the reasons many superheaters and reheaters are not working as envisioned is because they were designed for operating criteria that never materialized.
He said that use of a ring-style attemperator might reduce the downstream straight run by the equivalent boiled a few pipe diameters. I would like to see you write about the boiler-turbine co-ordinated control.
Steam AttemperatorAttemperation is the primary technique used for controlling the degree of superheat in a boiler. Depending on where the disturbances originate from, you may even want to implement a steam flow controller to deal with valve nonlinearities and steam pressure changes. In essence, when boiler load is increasing, the spray water flow rate will be increased to counter the excess heat being transferred to the steam, and vice versa.
Steam Temperature Control | Control Notes
This is slightly off topic but still relevant question for Control engineers at a time when Advanced process control schemes attemperator in boiler becoming more prevalent.
The example below shows two attemperators 3 and 4 installed in a desalination plant, controlling the steam turbine input temperature. Other methods of steam temperature control include flue gas recirculation, flue gas bypass, and tilting the angle at which the burners fire into the furnace. 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.
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After separation from the boiler water in the drum, the steam is superheated to improve the thermal attemperator in boiler of the boiler-turbine unit. Desuperheaters are generally found in steam lines away from the boiler or boiler outlet piping where there is a downstream use for saturated steam.
Attemperator in boiler, From the attemperator in boiler you gave me it is not possible to tell exactly what the problem is. This will have a negative impact on the stability of the main steam temperature control loop unless gain scheduling is implemented. This objective is maximized by the ring-type attemperator. Final desuperheaters are not intended for use after startup. Recent Posts F users share best practices with colleagues Special Report: In actual practice, you cannot boileg 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.
Because of the slow response of the main steam temperature control attrmperator, improved disturbance rejection can be achieved by implementing a secondary inner control loop at the desuperheater.
It complies with all existing standards and is always pressure tested on both the steam side as well as the water side.
A proper liner is an important element in every desuperheating station. Overspray is generally defined as an attemperator outlet steam temperature of less than 50 deg F above the prevailing saturation temperature.
Anderson said that best attemperation results in E- and F-class combined cycles, based on his experience, are being achieved by variable-area spring-loaded spray nozzles Fig 9. Instead, it will accumulate below the lower headers and possibly flow up into the harps—a condition conducive to extensive tube failures.
This page may be out of date. March 20, at Why attemperator in boiler we use superheated steam for a steam turbine rather than saturated steam?
Steam that can instead be used for the desalination plant. Would such a cascade arrangement be practical work for, say column overhead temperature master to reboiler steam temperature slave? The desuperheater outlet temperature control loop will provide a gradual recovery when this happens. August 3, at 9: