Development of Technologies on Innovative Simplified Nuclear Power Plant Using High-Efficiency Steam Injectors: Part 10—Application to a Small District-Heating Reactor

2006 ◽  
Author(s):  
Tadashi Narabayashi ◽  
Yoichiro Shimazu ◽  
Toshihiko Murase ◽  
Masatoshi Nagai ◽  
Michitsugu Mori ◽  
...  
Keyword(s):  
Power Plant ◽  
Direct Contact ◽  
Cooling System ◽  
High Reliability ◽  
District Heating ◽  
Water Jet ◽  
Hot Water ◽  
Feed Water ◽  
District Heating System ◽  
Core Cooling

A steam injector (SI) is a simple, compact and passive pump and also acts as a high-performance direct-contact compact heater. This provides SI with capability to use as a passive ECCS pump and also as a direct-contact feedwater heater that heats up feedwater by using extracted steam from the turbine. In order to develop a high reliability passive ECCS pump and a compact feedwater heater, it is necessary to quantify the characteristics between physical properties of the flow field. We carried out experiments to observe the internal behavior of the water jet as well as measure the velocity of steam jet using a laser Doppler velocimetry. Its performance depends on the phenomena of steam condensation onto the water jet surface and heat transfer in the water jet due to turbulence on to the phase-interface. The analysis was also conducted by using a CFD code with the separate two-phase flow models. With regard to the simplified feed-water system, size of four-stage SI system is almost the same as the model SI that had done the steam and water test that pressures were same as that of current ABWR. The authors also conducted the hot water supply system test in the snow for a district heating. With regard to the SI core cooling system, the performance tests results showed that the low-pressure SI core cooling system will decrease the PCT to almost the same as the saturation temperature of the steam pressure in a pressure vessel. As it is compact equipment, SI is expected to bring about great simplification and materials-saving effects, while its simple structure ensures high reliability of its operation, thereby greatly contributing to the simplification of the power plant for not only an ABWR power plant but also a small PWR/ BWR for district heating system.

scholarly journals Overview of Solutions for the Low-Temperature Operation of Domestic Hot-Water Systems with a Circulation Loop

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3350
Author(s):  
Theofanis Benakopoulos ◽  
William Vergo ◽  
Michele Tunzi ◽  
Robbe Salenbien ◽  
Svend Svendsen
Keyword(s):  
Low Temperature ◽  
Heat Loss ◽  
District Heating ◽  
Heating System ◽  
Hot Water ◽  
Heating Power ◽  
Circulation Loop ◽  
Space Heating ◽  
District Heating System ◽  
Domestic Hot Water

The operation of typical domestic hot water (DHW) systems with a storage tank and circulation loop, according to the regulations for hygiene and comfort, results in a significant heat demand at high operating temperatures that leads to high return temperatures to the district heating system. This article presents the potential for the low-temperature operation of new DHW solutions based on energy balance calculations and some tests in real buildings. The main results are three recommended solutions depending on combinations of the following three criteria: district heating supply temperature, relative circulation heat loss due to the use of hot water, and the existence of a low-temperature space heating system. The first solution, based on a heating power limitation in DHW tanks, with a safety functionality, may secure the required DHW temperature at all times, resulting in the limited heating power of the tank, extended reheating periods, and a DH return temperature of below 30 °C. The second solution, based on the redirection of the return flow from the DHW system to the low-temperature space heating system, can cool the return temperature to the level of the space heating system return temperature below 35 °C. The third solution, based on the use of a micro-booster heat pump system, can deliver circulation heat loss and result in a low return temperature below 35 °C. These solutions can help in the transition to low-temperature district heating.

scholarly journals Thermal Hydraulic Analysis of a Nuclear Reactor due to Loss of Coolant Accident with and without Emergency Core Cooling System

2020 ◽  
Vol 01 (02) ◽  
pp. 53-60
Author(s):  
Pronob Deb Nath ◽  
Kazi Mostafijur Rahman ◽  
Md. Abdullah Al Bari
Keyword(s):  
Nuclear Reactor ◽  
Cooling System ◽  
Computational Study ◽  
Reactor Core ◽  
Primary Circuit ◽  
Feed Water ◽  
Pressurized Water ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Core Cooling

This paper evaluates the thermal hydraulic behavior of a pressurized water reactor (PWR) when subjected to the event of Loss of Coolant Accident (LOCA) in any channel surrounding the core. The accidental break in a nuclear reactor may occur to circulation pipe in the main coolant system in a form of small fracture or equivalent double-ended rupture of largest pipe connected to primary circuit line resulting potential threat to other systems, causing pressure difference between internal parts, unwanted core shut down, explosion and radioactivity release into environment. In this computational study, LOCA for generation III+ VVER-1200 reactor has been carried out for arbitrary break at cold leg section with and without Emergency Core Cooling System (ECCS). PCTRAN, a thermal hydraulic model-based software developed using real data and computational approach incorporating reactor physics and control system was employed in this study. The software enables to test the consequences related to reactor core operations by monitoring different operating variables in the system control bar. Two types of analysis were performed -500% area break at cold leg pipe due to small break LOCA caused by malfunction of the system with and without availability of ECCS. Thermal hydraulic parameters like, coolant dynamics, heat transfer, reactor pressure, critical heat flux, temperature distribution in different sections of reactor core have also been investigated in the simulation. The flow in the reactor cooling system, steam generators steam with feed-water flow, coolant steam flow through leak level of water in different section, power distribution in core and turbine were plotted to analyze their behavior during the operations. The simulation showed that, LOCA with unavailability of Emergency Core Cooling System (ECCS) resulted in core meltdown and release of radioactivity after a specific time.

scholarly journals Advanced Control of a District Heating System with High Residential Domestic Hot Water Demand

2020 ◽  
Vol 160 ◽  
pp. 01004 ◽  
Author(s):  
Stanislav Chicherin ◽  
Lyazzat Junussova ◽  
Timur Junussov
Keyword(s):  
Energy Demand ◽  
Energy Use ◽  
District Heating ◽  
Heating System ◽  
Primary Energy ◽  
Hot Water ◽  
District Heating System ◽  
Domestic Hot Water ◽  
Extreme Load ◽  
Flow Controller

Proper adjustment of domestic hot water (DHW) load structure can balance energy demand with the supply. Inefficiency in primary energy use prompted Omsk DH company to be a strong proponent of a flow controller at each substation. Here the return temperature is fixed to the lowest possible value and the supply temperature is solved. Thirty-five design scenarios are defined for each load deviation index with equally distributed outdoor temperature ranging from +8 for the start of a heating season towards extreme load at temperature of -26°C. All the calculation results are listed. If a flow controller is installed, the customers might find it suitable to switch to this type of DHW supply. Considering an option with direct hot water extraction as usual and a flow controller installed, the result indicates that the annual heat consumption will be lower once network temperatures during the fall or spring months are higher. The heat load profiles obtained here may be used as input for a simulation of a DH substation, including a heat pump and a tank for thermal energy storage. This design approach offers a quantitative way of sizing temperature levels in each DH system according to the listed methodology and the designer's preference.

Sizing of a Gas Turbine for Repowering of Cogeneration Power Plant Ljubljana by Mathematical Optimisation

1996 ◽  
Author(s):  
Mihael Gabriel Tomšič ◽  
Olgica Perović
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Optimal Operation ◽  
Hot Water ◽  
Mixed Integer ◽  
Heat Recovery Boiler ◽  
Continuous Variables ◽  
District Heating System ◽  
Operational Strategy ◽  
Steam Extraction

The paper deals with optimal sizing of a gas turbine for repowering of cogeneration power plant Ljubljana considering possible plant operational strategy with respect to variations of electric and heat loads and energy costs. CHP plant is a main source for the Ljubljana town district heating system. Existing plant consists of two condensing steam turbines with steam extraction, back pressure turbine with steam extraction, auxiliary steam and hot water boilers for peak heat load production. This system delivers up to 111 MW into the power grid and up to 348 MW of heat. Repowering with gas turbine generator set with additionally fired heat recovery boiler is considered. For uncoupling heat and power generation a heat storage tank is assumed. For sizing of new equipment and plant operational strategy a model based on mixed-integer linear programming was developed. Zero - one integer variables are adopted to indicate the on/off status of operation, continuous variables to indicate the operational level of each constituent equipment and an optimal solution is derived by branch and bound method. Two prospective sizes of TG sets were tested for range of assumptions regarding power purchase tariff schedules. Different optimal operation policies resulted. The study provides background for contract negotiation and for investment decisions.

Hybrid heat pipe based passive in-core cooling system for advanced nuclear power plant

2015 ◽  
Vol 90 ◽  
pp. 609-618 ◽  
Author(s):  
Yeong Shin Jeong ◽  
Kyung Mo Kim ◽  
In Guk Kim ◽  
In Cheol Bang
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Heat Pipe ◽  
Nuclear Power ◽  
Cooling System ◽  
Core Cooling

Incorporating a District Heating/Cooling System Into an Existing Geothermal Power Plant

1998 ◽  
Vol 120 (2) ◽  
pp. 179-184 ◽  
Author(s):  
M. Kanog˘lu ◽  
Y. A. C¸engel ◽  
R. H. Turner
Keyword(s):  
Power Plant ◽  
Cooling System ◽  
Peak Load ◽  
District Heating ◽  
Industrial Park ◽  
Exergy Destruction ◽  
Geothermal Fluid ◽  
Geothermal Power Plant ◽  
Floor Space ◽  
Geothermal Power

Geothermal energy has been used for power generation, space and process heating, and to a lesser extent, space cooling. However, it is rarely used for cogeneration. This paper shows how a district heating/cooling system can be incorporated into an existing geothermal power plant to make the best use of extracted hot brine. In the power plant analysis, exergy destruction throughout the plant is quantified and illustrated using an exergy cascade. The primary source of exergy destruction in the plant is determined to be the reinjection of used brine into the ground, which accounts for 48.1 percent of the total exergy destruction. The overall first and the second law efficiencies of the plant are calculated to be 5.6 and 28.3 percent, respectively, based on the exergy of the geothermal fluid at downwell, and 5.7 and 28.6 percent, respectively, based on the exergy of the geothermal fluid at wellhead. A binary system is considered for the heating/cooling district to avoid corrosion and scaling problems. The heating system, as designed, has the capability to meet the entire needs of the Reno Industrial Park under peak load conditions, and has 30 percent reserve for future expansion. An absorption system will be used for the cooling of the intended 40 percent floor space of the industrial park. An economic analysis shows that the incorporation of the district heating/cooling system with 2,785,000 m2 of floor space connected to the geothermal grid appears to be feasible, and financially very attractive. Further, using the returning freshwater from the district heating/cooling system for partial cooling of the binary fluid of the power plant can save up to 15 percent of the fan work.

scholarly journals District heating system simulation considering consumer and pump operation features

Vestnik MGSU ◽  
2019 ◽  
pp. 748-755 ◽  
Author(s):  
Saule K. Abildinova ◽  
Stanislav V. Chicherin
Keyword(s):  
Mathematical Model ◽  
Energy Consumption ◽  
District Heating ◽  
Heating System ◽  
Hot Water ◽  
Water Supply Systems ◽  
Problem Solution ◽  
District Heating System ◽  
Pump Station ◽  
Pump Equipment

Introduction. The purpose of this investigation is to show what changes introduced in the mathematical model of a district heating system are capable of considerable improving the convergence of simulation results and actual data. The study evaluates the work of heating supply establishments with their customers as well as analysis of the ways of enhancing pump equipment efficiency that allows saving electric energy or increasing output at the same energy consumption. Materials and methods. Engineering acceptance of newly introduced and reconstructed facilities is conducted, heat loads are corrected, disconnections and recurrent connections of indebted consumers are carried out. Studying data submitted by a local heat supply establishment shows that pump seals made from iron and steel are subject accelerated wear in the course of operation. Results. Three variants of the problem solution are suggested: making seals from bronze or stainless steel, prevention of unjustified increase of seal clearances as well as using labyrinth pump seals. This will allow increasing pump equipment efficiency by 5 to 7 % and save about 2 × 105 kW∙h of electrical energy for every pump or increase of output at the same energy consumption. Taking into account that a pump station is a part of the district heating system and unmachined inner surfaces of the pumps have a significant roughness, grinding of these surfaces can improve their hydraulic characteristics of the pumps. In the scope of the suggested method, the entire district heating system is considered not in the situation when actual load is equal to the sum of all the design loads and the pump equipment has manufacturer’s parameters, but accounting actual loads and characteristics. Conclusions. Mathematical model of district heating system heating and hydraulic mode that takes issues mentioned above into consideration would allow simulating joint operation of the heating and hot water supply systems at transient operation modes with higher accuracy.

Analysis of Automatic Depressurization System Stage 4 Valves Inadvertent Actuation Scenario for a Certain Passive Power Plant

2013 ◽  
Author(s):  
Lu Lu ◽  
Jianhui Yu
Keyword(s):  
Risk Assessment ◽  
Power Plant ◽  
Cooling System ◽  
Statistical Treatment ◽  
Local Maximum ◽  
Stage 4 ◽  
Passive Power ◽  
Core Cooling ◽  
Uncertainty Method ◽  
Made In

The automatic depressurization system (ADS) stage 4 valves inadvertent actuation scenario is one of the risk-significant cases in probabilistic risk assessment (PRA) analysis of passive power plant. Based on mini-ASTRUM (automated statistical treatment of uncertainty method) and CQD (code qualification document) method together, the calculation which utilizing WCOBRA/TRAC and HOTSPOT codes has been made in this paper. And the results indicate that, the calculated peak cladding temperature (PCT), local maximum oxidation (LMO), and core-wide oxidation (CWO) are all low enough, which meet the three design acceptance criteria defined in 10 CFR 50.46 emergency core cooling system (ECCS).

scholarly journals Biomass consumption in residential sector of Ukraine in 2007–2016

2019 ◽  
Vol 112 ◽  
pp. 02006
Author(s):  
Viacheslav Antonenko ◽  
Sofiia Levinska
Keyword(s):  
District Heating ◽  
Decisive Role ◽  
Heating System ◽  
Regional Level ◽  
Hot Water ◽  
District Heating System ◽  
Residential Sector ◽  
Statistical Monitoring ◽  
Direct Emission ◽  
Self Production

Residential sector plays a decisive role in the bioenergy sector growth in Ukraine. Larger half of biomass used by households comes from so-called self-production, which is problematic for the statistical monitoring. State Statistics do not publish detailed fuel mix reports on regional level. In this article we are providing a detailed data on fuel mix used by the households at regional level during 2007– 2016 and determine the biofuel self-production amount. The facilities that are direct emission sources and are the final fuel consumers, including individual heating/hot water boilers/stoves out of district heating system and individual cookers are considered in detail.

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