scholarly journals The Integration of Process Heat Applications to High Temperature Gas Reactors

2011 ◽  
Author(s):  
Michael G. McKellar
Keyword(s):  
High Temperature ◽  
Greenhouse Gases ◽  
Industrial Process ◽  
Inlet Temperature ◽  
Condensation Temperature ◽  
Outlet Temperature ◽  
Reactor Outlet ◽  
Reactor Inlet ◽  
Process Heat ◽  
High Temperature Gas

A high temperature gas reactor, HTGR, can produce industrial process steam, high-temperature heat-transfer gases, and/or electricity. In conventional industrial processes, these products are generated by the combustion of fossil fuels such as coal and natural gas, resulting in significant emissions of greenhouse gases such as carbon dioxide. Heat or electricity produced in an HTGR could be used to supply process heat or electricity to conventional processes without generating any greenhouse gases. Process heat from a reactor needs to be transported by a gas to the industrial process. Two such gases were considered in this study: helium and steam. For this analysis, it was assumed that steam was delivered at 17 MPa and 540°C and helium was delivered at 7 MPa and at a variety of temperatures. The temperature of the gas returning from the industrial process and going to the HTGR must be within certain temperature ranges to maintain the correct reactor inlet temperature for a particular reactor outlet temperature. The returning gas may be below the reactor inlet temperature, ROT, but not above. The optimal return temperature produces the maximum process heat gas flow rate. For steam, the delivered pressure sets an optimal reactor outlet temperature based on the condensation temperature of the steam. ROTs greater than 769.7°C produce no additional advantage for the production of steam.

Modeling and Analyzing of Simple Combined Cycle of Modular High Temperature Gas Cooled Reactor

2016 ◽  
Author(s):  
Xinhe Qu ◽  
Xiaoyong Yang ◽  
Jie Wang
Keyword(s):  
High Temperature ◽  
High Efficiency ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Brayton Cycle ◽  
Reactor Outlet ◽  
Cycle Efficiency ◽  
High Temperature Gas

High temperature gas cooled reactor (HTGR) which is one of generation IV reactor has been widely given attention in many countries since the sixties of the last century because of its inherent safety and high efficiency. Currently, the HTGR commonly uses regenerative Brayton cycle. However, as reactor outlet temperature (ROT) rising, regenerative Brayton cycle has a higher reactor inlet temperature (RIT) than 500°C and is limited by reactor materials. Combined cycle of HTGR not only can solve the problem of high RIT, but also can get a higher cycle efficiency than 50%. In this paper an accurate model of combined cycle consisting of topping Brayton cycle, bottoming Rankine cycle and heat recovery steam generator (HRSG) was established. In terms of new model of combined cycle, this paper analyzed the main properties of simple combined cycle. And put forward two optimization schemes improving the cycle efficiency of combined cycle.

Transient Response Simulation of High Temperature Gas-Cooled Reactor With Helium Turbine for Secondary Inlet Temperature Change of Precooler and Intercooler

2010 ◽  
Author(s):  
Wenlong Li ◽  
Zuoyi Zhang ◽  
Heng Xie ◽  
Yujie Dong
Keyword(s):  
High Temperature ◽  
Temperature Increase ◽  
Power Loss ◽  
Cooling Water ◽  
Reactor Power ◽  
Physical Parameters ◽  
Inlet Temperature ◽  
Reactor Outlet ◽  
Reactor Inlet ◽  
High Temperature Gas

A simulation program has been developed to study the transient characteristics of high temperature gas-cooled reactor with indirect helium turbine cycle. It is assumed that cooling water inlet temperature of precooler or intercooler has a step increase from 20°C to 25°C. Simulation result shows that generator power decreases accompanied with inlet temperature increase of cooling water of precooler or intercooler and precooler accident causes much bigger power loss for generator than intercooler accident. Both of surge margins of LPC and HPC have step decreases due to these two accidents. For this precooler accident, physical parameters of primary loop keep basically unchanged. For this intercooler accident, it causes reactor power loss, temperature increase of reactor inlet and temperature decrease of reactor outlet.

The Features of Closed Brayton Cycle and Sub-Critical Combined Cycles Coupled With (Very) High Temperature Gas-Cooled Reactor

2018 ◽  
Author(s):  
Xinhe Qu ◽  
Xiaoyong Yang ◽  
Gang Zhao ◽  
Jie Wang
Keyword(s):  
High Temperature ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Fourth Generation ◽  
Outlet Temperature ◽  
Brayton Cycle ◽  
Reactor Outlet ◽  
Combined Cycles ◽  
Very High ◽  
High Temperature Gas

High Temperature Gas-cooled Reactor (HTR) and Very High Temperature Gas-cooled Reactor (VHTR), are the most promising and achievable fourth-generation nuclear reactor for its inherent safety. In this paper, the performance of Closed Brayton Cycle (CBC) and two sub-critical combined cycles were investigated and compared. The CBC is a recuperated and inter-cooling closed Brayton cycle. Two combined cycles include the sub-critical Rankine cycle without steam reheating (Simple Combined Cycle, SCC) and a sub-critical reheated Rankine cycle (Reheated Combined Cycle, RCC). The topping cycles of SCC and RCC are both a simple Brayton cycle, and connect with the bottoming cycles by a sub-critical heat recovery steam generator (HRSG). Physical and mathematical models of three different thermodynamic cycles were established. Within the temperature range of the HTR and VHTR, the effects and mechanism of key parameters, such as reactor outlet temperature, steam temperature and pressure, on features of three different cycles were investigated. The results showed the elevated reactor outlet temperature could obviously enhance efficiency of three cycles. The results showed that RCC had the highest efficiency while SCC had the lowest efficiency, and the efficiency of CBC is slightly lower than that of RCC. The results could be helpful to understand and develop the power conversion system coupled with (V)HTR in the future.

An Evaluation of Creep-Fatigue Damage for the Prototype Process Heat Exchanger of the NHDD Plant

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Kee-Nam Song ◽  
Yong-Wan Kim ◽  
Sung-Deok Hong ◽  
Hong-Yune Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Temperature ◽  
Fatigue Damage ◽  
Inlet Temperature ◽  
Alloy 617 ◽  
Element Analysis ◽  
Creep Fatigue ◽  
Process Heat ◽  
Very High

A process heat exchanger (PHE) transfers the heat generated from a nuclear reactor to a sulfur-iodine hydrogen production system in the Nuclear Hydrogen Development and Demonstration, and was subjected to very high temperature up to 950°C. An evaluation of creep-fatigue damage, for a prototype PHE, has been carried out from finite element analysis with the full three dimensional model of the PHE. The inlet temperature in the primary side of the PHE was 950°C with an internal pressure of 7 MPa, while the inlet temperature in the secondary side of the PHE is 500°C with internal pressure of 4 MPa. The candidate materials of the PHE were Alloy 617 and Hastelloy X. In this study, only the Alloy 617 was considered because the high temperature design code is available only for Alloy 617. Using the full 3D finite element analysis on the PHE model, creep-fatigue damage evaluation at very high temperature was carried out, according to the ASME Draft Code Case for Alloy 617, and technical issues in the Draft Code Case were raised.

Thermodynamic Analysis of Power Generation Cycles With High-Temperature Gas-Cooled Nuclear Reactor and Additional Coolant Heating Up to 1600 °C

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Michał Dudek ◽  
Zygmunt Kolenda ◽  
Marek Jaszczur ◽  
Wojciech Stanek
Keyword(s):  
Energy Efficiency ◽  
High Temperature ◽  
Thermodynamic Analysis ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Electric Energy ◽  
High Energy ◽  
Medium Size ◽  
Outlet Temperature ◽  
High Temperature Gas

Nuclear energy is one of the possibilities ensuring energy security, environmental protection, and high energy efficiency. Among many newest solutions, special attention is paid to the medium size high-temperature gas-cooled reactors (HTGR) with wide possible applications in electric energy production and district heating systems. Actual progress can be observed in the literature and especially in new projects. The maximum outlet temperature of helium as the reactor cooling gas is about 1000 °C which results in the relatively low energy efficiency of the cycle not greater than 40–45% in comparison to 55–60% of modern conventional power plants fueled by natural gas or coal. A significant increase of energy efficiency of HTGR cycles can be achieved with the increase of helium temperature from the nuclear reactor using additional coolant heating even up to 1600 °C in heat exchanger/gas burner located before gas turbine. In this paper, new solution with additional coolant heating is presented. Thermodynamic analysis of the proposed solution with a comparison to the classical HTGR cycle will be presented showing a significant increase of energy efficiency up to about 66%.

scholarly journals (Solar) Mixed Reforming of Methane: Potential and Limits in Utilizing CO2 as Feedstock for Syngas Production—A Thermodynamic Analysis

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2537 ◽  
Author(s):  
Henrik von Storch ◽  
Sonja Becker-Hardt ◽  
Christian Sattler
Keyword(s):  
Outlet Temperature ◽  
Operating Pressure ◽  
Carbon Formation ◽  
Synthetic Fuels ◽  
Reactor Outlet ◽  
Reactor Inlet ◽  
Syngas Production ◽  
A Value ◽  
Methane Potential ◽  
Reforming Reactions

The reforming of natural gas with steam and CO2 is commonly referred to as mixed reforming and considered a promising route to utilize CO2 in the production of synthetic fuels and base chemicals such as methanol. In the present study, the mixed reforming reaction is assessed regarding its potential to effectively utilize CO2 in such processes based on simple thermodynamic models. Requirements for the mixed reforming reactions based on process considerations are defined. These are the avoidance of carbon formation in the reactor, high conversion of the valuable inlet streams CH4 and CO2 as well as a suitable syngas composition for subsequent synthesis. The syngas composition is evaluated based on the module M = ( z H 2 − z CO 2 ) / ( z CO 2 + z CO ) ,   which should assume a value close to 2. A large number of different configurations regarding CO2/H2O/CH4 at the reactor inlet, operating pressure and outlet temperature are simulated and evaluated according to the defined requirements. The results show that the actual potential of the mixed reforming reaction to utilize CO2 as feedstock for fuels and methanol is limited to approximately 0.35 CO2/CH4, which is significantly lower than suggested in literature. At 900 °C and 7 bar at the reactor outlet, which is seen suitable for solar reforming, a ratio of H2O/CH4 of 1.4 can be set and the resulting value of M is 1.92 (CO2/CO/H2 = 0.07/0.4/1).

Analytical Dynamic Modeling of Line-Focus Solar Collectors

1981 ◽  
Vol 103 (3) ◽  
pp. 244-250 ◽  
Author(s):  
J. D. Wright
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
Industrial Process ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Fluid Flow Rate ◽  
Digital Controllers ◽  
Dynamics Models ◽  
Line Focus

Solar thermal electric power and industrial process heat systems may require a constant outlet temperature from the collector field. This constant temperature is most efficiently maintained by adjusting the circulating fluid flow rate. Successful tuning of analog or digital controllers requires a knowledge of system dynamics. Models relating deviations in outlet temperature to changes in inlet temperature, insolation, and fluid flow rate illustrate the basic responses and the distributed-parameter nature of line-focus collectors. When plotted in dimensionless form, the frequency response of a given collector is essentially independent of the operating conditions, suggesting that feedback controller settings are directly related to such easily determined quantities as collector gain and fluid residence time.

Sign in / Sign up

Export Citation Format

Share Document