Operation & Maintenance of Power Plants
electrical energy. Te reheater
Fig. 2. The process overview.
turbine with reheating increases the efficiency of the system by more than 30 per cent, which means additional electricity production of over 30 per cent from the same amount of fuel!
The reheater Te high-pressure steam from the boiler (1) has a pressure of 130 bars. Tis means an evaporation temperature of 330˚C. Te steam flowing to the high-pressure stage (2) of the turbine is superheated by more than 100˚C. After this high-pressure stage, the steam has a pressure of 14 bars, at the corresponding temperature of more than 190˚C. Te steam first flows to the separators. Here any
water droplets formed in the turbine are collected and discharged. Ten the dry steam goes to the superheater (position 6 in Fig 2), where the temperature is increased by approximately 130˚C, from 190˚C to 320˚C. A portion of the high-pressure steam is used as a heating medium. Te superheated low-pressure steam flows through the red pipes to the low-pressure stage of the turbine (4). In addition to the separator and the reheater, both reheater units consist of a condensate vessel for the high-pressure condensate formed. Tese vessels are necessary for controlling the units. Te low- pressure steam from the turbine is condensed in the condenser (5). Te high-pressure stage of the turbine and the low-pressure stage transfer their mechanical energy to the generator (3), where it is converted into
units were so crucial to realising a properly working, highly-efficient installation, that AEB decided to purchase the installations themselves directly. When Bronswerk received the request for the reheaters, it proposed supplying the complete units, including separator, condensate vessel and the connecting piping. Te proper operation of the separator is crucial to the proper operation of the reheater. To prevent having the warranty spread over two suppliers, it was wise to keep everything
in one hand. AEB gave Bronswerk the opportunity to supply the complete installations.
Combination of techniques Te proposal by Bronswerk Heat Transfer contained a combination of techniques that together result in a compact and robust unit. Te High Pressure Compact Header, which had just been developed by Bronswerk, was provided for the high-pressure steam. To avoid vibrations due to high flow rates of the low-pressure steam in the condenser , a ‘no-tubes-in-windows’ type was used, while low-finned tubes provide good heat transfer to the low-pressure steam. For a company aspiring to be a market leader, it is
necessary to introduce a breakthrough development to the market every now and then. Te High Pressure Compact Header referred to here is just such a Bronswerk development. It is also essential to know the discipline to the finest detail. Tis makes it possible to use the right combination of existing and new technologies. Tis project shows that Bronswerk also masters these aspects.
AEB was so pleased with the design of the reheater unit that it also awarded Bronswerk the dump condenser. Ultimately, AEB now has an incinerator with uniquely high efficiency. l
For more information ✔ at
www.engineerlive.com/ipe
Johan van der Kamp and Hans van Essen are with Bronswerk Heat Transfer BV, Nijkerk, The Netherlands.
www.bronswerk.com
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