Feasibility study of the energy and economic gain that can be achieved by driving the boiler feedwater pump with a backpressure steam turbine

The low-pressure steam requirement in the iron and steel production plant is obtained through pressure reduction stations with unrestrained expansion. In this study, the feasibility of obtaining the low-pressure steam that is needed in the plant in a backpressure turbine instead of pressure reduction stations has been studied. In this way, it is foreseen that a significant amount of wasted energy during the unrestrained expansion in pressure reduction stations, can be recovered as shaft work during the expansion process performed in the turbine. The obtained shaft work is planned to be used in the boiler feedwater pump drive. It is aimed to increase the efficiency of the system by the deactivation of boiler feedwater pump electric motors and as well as bringing the energy that is lost during the unrestrained expansion of the superheated steam to the system through the pump drive. The estimated size of energy saving of the system could be reached to 33.74%. The annual size of achievable saving has been determined by approximately 8,094,810 kWh and economically $509,973. The payback period of the estimated $683,079 investment is 1.34 years. A determined amount of saving is also equivalent to the reduction of 7,285,329 kg CO2 emission, annually.

ANALISIS PENGARUH VIBRASI TERHADAP PERFORMA BOILER FEEDWATER PUMP (BFP) 3B PLTU ASAM ASAM

Pada Desember 2016 hingga Januari 2017, terjadi penurunan kinerja PLTU Asam Asam Unit 3 yang signifikan dalam penyediaan tenaga listrik. Hal ini dikarenakan adanya permasalahan pada Boiler Feedwater Pump (BFP) 3B. Kemudian masalah harus diselesaikan oleh Turbin dan Kru Pemeliharaan Tambahan dengan beberapa perbaikan. Perbaikan BFP 3B berada pada masalah jarak jalan internal dan masalah poros tekuk. Setelah diperbaiki, data perhitungan menunjukkan bahwa efisiensi total pompa meningkat sebesar 10%, dan zona getaran berpindah dari zona D (berbahaya) ke zona A (aman untuk pengoperasian berkelanjutan). In December 2016 until January 2017, there was a significant decreasing performance of Unit 3 PLTU Asam Asam in supplying electric power. This was because of some problems in Boiler Feedwater Pump (BFP) 3B. Then the problems have to be solved by the Turbine and Auxiliary Maintenance Crew by some repairs. The repair of BFP 3B are in the internal running clearance problem and bending shaft problem. After the repair of them, calculation data show that the pump total efficiency increasing by 10 %, and the vibration zone move from D zone (dangerous) to A zone (safe for continuous operation).

Study on Measures During Loss of Normal Feedwater Accident for AP1000 NPP in Lower Power Operation

If an accident occurred in a plant in lower power operation, a series of problems could be caused by low residual heat and excessive removal capability of heat sinks. Taking a real accident as example, this paper discussed how to deal with loss of normal feedwater in AP1000 NPP during lower power operation. The level of Steam Generators (SG) will be rapidly reduced in case of Main Feedwater loss, and Startup Feedwater pump will start. If the reactor is not shut down immediately, the Startup Feedwater will not be enough to prevent SG level from falling, and automatic reactor trip will be inevitable. Therefore, in event of loss of Main Feedwater which cannot be recovered instantly, the reactor should be shut down manually to maintain SG level as high as possible. Appropriate measures should be taken to avoid excessive cooling after trip. Attention should be paid to SG level and feedwater flow to avoid Passive Residual Heat Removal Heat Exchanger (PRHR HX) actuation during regulating Startup Feedwater. Otherwise, PRHR HX may be actuated unexpectedly. With Reactor Coolant Pumps operating, PRHR HX heat removal capacity is strong. The Cold Leg temperature will drop rapidly because of PRHR HX and other heat sinks. In this case, the most effective measure to stabilize temperature of Cold legs is to isolate Streamline. Otherwise, structure integrity of the Reactor Pressure Vessel (RPV) will be challenged under Pressurized Thermal Shock (PTS) due to rapid drop of Cold leg temperature. In order to alleviate PTS, depressurization shall be performed and further cooling shall be suspended. Since PRHR HX is only connected to Loop 1, coolant in Hot Leg of Loop 2 is still kept at high temperature. Therefore, necessary measures shall be taken to prevent coolant flash in Loop 2 during the process of depressurization, which may fill the Pressurizer up with water. The RPV Head Vent valves perform safety-related function by preventing Pressurizer overfill in certain design basis events in AP1000 NPP. However, emergency letdown by opening the valves cannot effectively reduce Pressurizer level when coolant flashed in Loop 2. Because of mitigating PTS, opening RPV Head Vent valves, and steam condensation in Loop 2, the subcooling of the coolant at the core outlet is likely to drop below 6 °C or even 0 °C.

EN Analysis of modern approaches to improve the efficiency of blackout accident management at nuclear power plants

The paper analyzes the approaches to improve the efficiency of blackout accident management taking into account the lessons of the great accident at Fukushima Daiichi NPP in 2011. It is found that the afterheat removal passive systems by natural circulation through steam generators cannot provide conditions for adequate safety functions to remove heat from the reactor and maintain the required feedwater level in the steam generator during blackout accidents and multiple failures of safety-related systems. The application of alternative approaches using auxiliary feedwater steam generator driven pumps requires additional experiment-calculated operability / reliability qualification for a blackout accident and multiple failures of NPP safety-related systems. However, implementation of alternative SDEFP system requires in-depth qualification for the conditions of blackout accidents. Safety systems of passive heat removal from the steam generator (adequately to active safety electrical systems) cannot ensure safety functions on control of required feedwater level in the steam generator and heat removal from the reactor core during blackout accidents (at least 72 hours) and multifailure accidents. The system of the steam generator driven emergency feedwater pump can be the alternative solution to ensure safety functions on heat removal through the steam generator during blackout accidents. Additional study of efficiency of steam driven pumps at the experimental facilities that meet real-life criteria of hydrodynamic similarity is a necessary condition for implementation of system of the steam driven emergency feedwater pump. Application of an integrated approach to manage blackout accidents is reasonable. At the initial stage of accident with relatively high steam pressure in the steam generator it is required supply of feedwater by the steam driven emergency pump

Low Power Steam Turbine Energy Efficiency and Losses During the Developed Power Variation

This paper investigates low power marine steam turbine during the variation in its developed power. The turbine is used for the Main Feedwater Pump (MFP) drive. Energy analysis of the Main Feedwater Pump Turbine (MFPT) is based on the measurements performed in nine different operating regimes. The measured operating parameters were steam pressure and temperature at the turbine inlet, steam pressure at the turbine outlet, and a water volume flow through MFP. Turbine energy power losses are most influenced by steam mass flow through the turbine and by steam specific enthalpy at the turbine outlet. An increase in turbine developed power causes a continuous increase in turbine energy efficiency. Analyzed turbine is balanced as most of the other steam system components – maximum energy efficiency will be obtained at the highest load, on which the majority of turbine and system operation can be expected during exploitation.

PRELIMINARY DESIGN OF RDE FEEDWATER PUMP IMPELLER

Nowadays, pumps are being widely used in the thermal power generation including nuclear power plants. Reaktor Daya Eksperimental (RDE) is a proposed nuclear reactor concept for the type of nuclear power plant in Indonesia. This RDE has thermal power 10 MWth, and uses a feedwater pump within its steam cycle. The performance of feedwater pump depends on size and geometry of impeller model, such as the number of blades and the blade angle. The purpose of this study is to perform a preliminary design on an impeller of feedwater pump for RDE and to simulate its performance characteristics. The Fortran code is used as an aid in data calculation in order to rapidly compute the blade shape of feedwater pump impeller, particularly for a RDE case. The calculations analyses is solved by utilizing empirical correlations, which are related to size and geometry of a pump impeller model, while performance characteristics analysis is done based on velocity triangle diagram. The effect of leakage, pass through the impeller due to the required clearances between the feedwater pump impeller and the volute channel, is also considered. Comparison between the feedwater pump of HTR-10 and of RDE shows similarity in the trend line of curve shape. These characteristics curves will be very useful for the values prediction of performance of a RDE feedwater pump. Preliminary design of feedwater pump provides the size and geometry of impeller blade model with 5-blades, inlet angle 14.5 degrees, exit angle 25 degrees, inside diameter 81.3 mm, exit diameter 275.2 mm, thickness 4.7 mm, and height 14.1 mm. In addition, the optimal values of performance characteristics were obtained when flow capacity was 4.8 kg/s, fluid head was 29.1 m, shaft mechanical power was 2.64 kW, and efficiency was 52 % at rotational speed 1750 rpm.Keywords: Blade, impeller, pump, RDEDESAIN AWAL IMPELER POMPA AIR UMPAN RDE. Saat ini, pompa digunakan secara luas dalam pembangkit tenaga termal termasuk pembangkit listrik tenaga nuklir. Reaktor Daya Eksperimental (RDE) merupakan konsep reaktor nuklir yang diusulkan untuk tipe PLTN di Indonesia. RDE ini memiliki daya termal 10 MWth, dan menggunakan pompa air umpan dalam siklus uapnya. Kinerja pompa air umpan bergantung pada ukuran dan geometri model impeller, seperti jumlah sudu dan sudut sudu. Tujuan dari penelitian ini adalah untuk membuat rancangan awal impeller pompa air umpan untuk RDE dan untuk mensimulasikan karakteristik kinerjanya. Kode Fortran digunakan sebagai bantuan dalam penghitungan data untuk untuk mengkalkulasi secara cepat bentuk sudu impeller pompa air umpan, terutama pada kasus RDE. Analisis perhitungan dipecahkan menggunakan korelasi empiris yang terkait dengan ukuran dan geometri model impeller pompa, sedangkan analisis karakteristik kinerja dilakukan berdasarkan diagram segitiga kecepatan. Pengaruh bocoran, melalui impeler akibat celah yang diperlukan antara impeller pompa air umpan dan saluran volute, juga dipertimbangkan. Perbandingan antara pompa air umpan HTR-10 dan RDE menunjukkan kemiripan dalam garis tren bentuk kurva. Kurva karakteristik ini akan sangat berguna untuk perkiraan nilai kinerja pompa air umpan RDE. Desain awal pompa air umpan memberikan ukuran dan geometri model sudu impeller dengan 5-sudu, sudut masuk 14,5 derajat, sudut keluar 25 derajat, diameter dalam 81,3 mm, diameter luar 275,2 mm, ketebalan 4,7 mm, dan tinggi 14,1 mm. Selain itu, nilai optimal karakteristik kinerja diperoleh ketika kapasitas aliran 4,8 kg/s, head fluida 29,1 m, tenaga mekanik poros 2,64 kW, dan efisiensi 52 % pada kecepatan putaran 1750 rpm.Kata kunci: Sudu, impeler, pompa, RDE