Design and Test Plan of the Supercritical CO2 Compressor Test Loop

2008 ◽  
Author(s):  
Takao Ishizuka ◽  
Yasushi Muto ◽  
Masanori Aritomi
Keyword(s):  
High Pressure ◽  
Critical Point ◽  
Thermal Efficiency ◽  
Supercritical Co2 ◽  
Thermal Power ◽  
Low Pressure ◽  
Fiscal Year ◽  
Pressure Side ◽  
Test Loop ◽  
Pressure Compressor

Supercritical carbon dioxide (CO2) gas turbine systems can generate power at a high cycle thermal efficiency, even at modest temperatures of 500–550°C. That high thermal efficiency is attributed to a markedly reduced compressor work in the vicinity of critical point. In addition, the reaction between sodium (Na) and CO2 is milder than that between H2O and Na. Consequently, a more reliable and economically advantageous power generation system can be created by coupling with a Na-cooled fast breeder reactor. In a supercritical CO2 turbine system, a partial cooling cycle is employed to compensate a difference in heat capacity for the high-temperature — low-pressure side and low-temperature — high-pressure side of the recuperators to achieve high cycle thermal efficiency. In our previous work, a conceptual design of the system was produced for conditions of reactor thermal power of 600 MW, turbine inlet condition of 20 MPa/527°C, recuperators 1 and 2 effectiveness of 98%/95%, Intermediate Heat Exchanger (IHX) pressure loss of 8.65%, a turbine adiabatic efficiency of 93%, and a compressor adiabatic efficiency of 88%. Results revealed that high cycle thermal efficiency of 43% can be achieved. In this cycle, three different compressors, i.e., a low-pressure compressor, a high-pressure compressor, and a bypass compressor are included. In the compressor regime, the values of properties such as specific heat and density vary sharply and nonlinearly, dependent upon the pressure and temperature. Therefore, the influences of such property changes on compressor design should be clarified. To obtain experimental data for the compressor performance in the field near the critical point, a supercritical CO2 compressor test project was started at the Tokyo Institute of Technology on June 2007 with funding from MEXT, Japan. In this project, a small centrifugal CO2 compressor will be fabricated and tested. During fiscal year (FY) 2007, test loop components will be fabricated. During FY 2008, the test compressor will be fabricated and installed into the test loop. In FY 2009, tests will be conducted. This paper introduces the concept of a test loop and component designs for the cooler, heater, and control valves. A computer simulation program of static operation was developed based on detailed designs of components and a preliminary design of the compressor. The test operation regime is drawn for the test parameters.

scholarly journals Parametric diagnostics of the condition of a dual-flow turbojet engine using neural network simulation of the operating process

2018 ◽  
Vol 224 ◽  
pp. 02057
Author(s):  
Anas S. Gishvarov ◽  
Julien Celestin Raherinjatovo
Keyword(s):  
Neural Network ◽  
High Pressure ◽  
Combustion Chamber ◽  
Early Stage ◽  
Low Pressure ◽  
Similarity Criteria ◽  
Ann Model ◽  
Turbojet Engine ◽  
Operating Process ◽  
Pressure Compressor

The article presents a method of parametric diagnostics of the condition of a dual-flow turbojet engine (DFTE). The method is based on the identification (determination) of the condition of the DFTE components (the compressor, combustion chamber, turbine) with application of a mathematical model of the operating process which is presented as an artificial neural network (ANN) model. This model describes the relation between the monitored parameters of the DFTE (the air temperatures (Tlpc*, Thpc*) beyond the low pressure compressor (LPC) and the high pressure compressor (HPC), the pressure beyond the LPC (Plpc), the fuel consumption rate (Gf), the gas temperatures (Thpt*, Tlpt*) beyond the high pressure turbine (HPT) and the low pressure turbine (LPT)) and the parameters of the condition of its components (the efficiencies of the LPC and the HPC (ηlpc*, ηhpc*), the stagnation pressure recovery factor in the combustion chamber (σcc), the efficiencies of the HPT and the LPT (ηhpt*, ηlpt*)). The parameters of the condition of the engine components (ηlpc*, ηhpc*, σcc, ηhpt*, ηlpt*) are the similarity criteria (integral criteria) which enable to identify the condition of the DFTE components to a high degree of reliability. Such analysis enables to detect defects at an early stage, even if the values of the monitored parameters (Тlpc*, Тhpc*, Plpc, Gf, Тhpt*, Тlpt*) are within the permissible limits. We provide the sequence for development of the ANN model and the results of its performance study during the parametric diagnostics of the condition of the DFTE.

Numerical Simulation of Non-Equilibrium Condensation in Supercritical CO2 Compressors

2019 ◽  
Author(s):  
Kevin W. Brinckman ◽  
Ashvin Hosangadi ◽  
Zisen Liu ◽  
Timothy Weathers
Keyword(s):  
Critical Point ◽  
Residence Time ◽  
Supercritical Co2 ◽  
Equilibrium Phase ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Working Fluid ◽  
Modeling Framework ◽  
Test Loop ◽  
Non Equilibrium

Abstract There is increasing interest in supercritical CO2 processes, such as Carbon Capture and Storage, and electric power production, which require compressors to pressurize CO2 above the critical point. For supercritical compressor operation close to the critical point there is a concern that the working fluid could cross into the subcritical regime which could lead to issues with compressor performance if condensation was to occur in regions where the fluid dropped below the saturation point. Presently, the question of whether there is sufficient residence time at subcritical conditions for condensation onset in supercritical CO2 compressors is an unresolved issue. A methodology is presented towards providing a validated simulation capability for predicting condensation in supercritical CO2 compressors. The modeling framework involves the solution of a discrete droplet phase coupled to the continuum gas phase to track droplet nucleation and growth. The model is implemented in the CRUNCH CFD® Computational Fluid Dynamics code that has been extensively validated for simulation at near critical conditions with a real fluid framework for accurate predictions of trans-critical CO2 processes. Results of predictions using classical nucleation theory to model homogeneous nucleation of condensation sites in supersaturated vapor regions are presented. A non-equilibrium phase-change model is applied to predict condensation on the nuclei which grow in a dispersed-phase droplet framework. Model validation is provided against experimental data for condensation of supercritical CO2 in a De Laval nozzle including the Wilson line location. The model is then applied for prediction of condensation in the compressor of the Sandia test loop at mildly supercritical inlet conditions. The results suggest that there is sufficient residence time at the conditions analyzed to form localized nucleation sites, however, droplets are expected to be short lived as the model predicts they will rapidly vaporize.

Numerical Investigation of the Flow Behavior Inside a Supercritical CO2 Centrifugal Compressor

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Alireza Ameli ◽  
Teemu Turunen-Saaresti ◽  
Jari Backman
Keyword(s):  
Critical Point ◽  
Centrifugal Compressor ◽  
Supercritical Co2 ◽  
Flow Behavior ◽  
Liquid Density ◽  
Flow Solver ◽  
Real Gas ◽  
Fluid Behavior ◽  
Test Loop ◽  
Fluid Properties

Centrifugal compressors are one of the best choices among compressors in supercritical Brayton cycles. A supercritical CO2 centrifugal compressor increases the pressure of the fluid which state is initially very close to the critical point. When the supercritical fluid is compressed near the critical point, wide variations of fluid properties occur. The density of carbon dioxide at its critical point is close to the liquid density which leads to reduction in the compression work. This paper explains a method to overcome the simulation instabilities and challenges near the critical point in which the thermophysical properties change sharply. The investigated compressor is a centrifugal compressor tested in the Sandia supercritical CO2 test loop. In order to get results with the high accuracy and take into account the nonlinear variation of the properties near the critical point, the computational fluid dynamics (CFD) flow solver is coupled with a look-up table of properties of fluid. Behavior of real gas close to its critical point and the effect of the accuracy of the real gas model on the compressor performance are studied in this paper, and the results are compared with the experimental data from the Sandia compression facility.

Soft Computing Application for Gas Path Fault Isolation

2004 ◽  
Author(s):  
Ranjan Ganguli ◽  
Rajeev Verma ◽  
Niranjan Roy
Keyword(s):  
High Pressure ◽  
Fuzzy Sets ◽  
Fuzzy System ◽  
Low Pressure ◽  
Fault Isolation ◽  
Rule Base ◽  
Rotor Speed ◽  
Genetic Fuzzy System ◽  
Radial Basis ◽  
Pressure Compressor

A fuzzy system that automatically develops its rule base from a linearized performance model of the engine by selecting the membership functions and number of fuzzy sets is developed in this study to perform gas turbine fault isolation. The faults modeled are module faults in five modules: fan, low pressure compressor, high pressure compressor, high pressure turbine and low pressure turbine. The measurements used are deviations in exhaust gas temperature, low rotor speed, high rotor speed and fuel flow from a base line ‘good engine’. A genetic algorithm is used to tune the fuzzy sets to maximize fault isolation success rate. A novel scheme is developed which optimizes the fuzzy system using very few design variables and therefore is computationally efficient. Results with simulated data show that genetic fuzzy system isolates faults with accuracy greater than that of a manually developed fuzzy system developed by the authors. Furthermore, the genetic fuzzy system allows rapid development of the rule base if the fault signatures and measurement uncertainties change. In addition, the genetic fuzzy system reduces the human effort needed in the trial and error process used to design the fuzzy system and makes the development of such a system easier and faster. A radial basis neural network is also used to preprocess the measurements before fault isolation. The radial basis network shows significant noise reduction and when combined with the genetic fuzzy system leads to a diagnostic system that is highly robust to the presence of noise in data.

Practical Considerations When Conducting a Transient Analysis of a Heat Exchanger Tube Rupture

2012 ◽  
Author(s):  
David R. Thornton ◽  
Robert A. Sadowski ◽  
Philip A. Henry
Keyword(s):  
High Pressure ◽  
Heat Exchanger ◽  
Transient Analysis ◽  
Low Pressure ◽  
Lower Pressure ◽  
Pressure Side ◽  
Analysis Methodology ◽  
Large Pressure ◽  
Process Plants ◽  
Shell And Tube

As part of operations, petrochemical and process plants sometimes require the exchange of heat between a high pressure fluid and a lower pressure fluid in shell-and-tube heat exchangers. In most cases, the high pressure fluid exists on the tubeside and the lower pressure is on the shellside. While rare, it is possible for a tube inside the exchanger shell to rupture suddenly, releasing the high pressure fluid into the shellside. If the pressure of the high pressure fluid exceeds the design pressure of the low pressure shell or its attached piping, it might be possible for the resulting pressure in the low pressure side to exceed permitted values. In such cases, API 521 provides guidance on assuring that sufficient pressure relief is available to limit the pressures on the heat exchanger(s)’ low pressure side. An overpressure analysis per API 521 can include both steady-state and transient analysis methods for determining that the pressures remain within acceptable levels. In situations where a large pressure differential exists between the high and low pressure sides of the exchanger, the transient, hydraulic analysis of the tube rupture event can be used as a tool to help mitigate over pressure. After briefly discussing the analysis methodology, this paper discusses some of the practical considerations and decisions that normally go into conducting the analysis.

Reducing Energy Consumption for Seawater Desalination through the Application of Reflux-Recycle Concepts from Oil Refining

2013 ◽  
Vol 295-298 ◽  
pp. 1456-1462 ◽  
Author(s):  
K. E. Ting ◽  
H.T. Ng ◽  
H.C. Li
Keyword(s):  
High Pressure ◽  
Energy Consumption ◽  
Specific Energy Consumption ◽  
Low Pressure ◽  
Hybrid Membrane ◽  
Oil Refining ◽  
Pressure Side ◽  
Seawater Desalination ◽  
Feed Concentration ◽  
Membrane Processes

The application of the concepts in oil and gas distillation to membrane desalination process to lower the energy cost for seawater desalination was studied in this paper. Drawing on the close analogy between multistage RO and conventional distillation separation processes, a hybrid membrane processes employing reflux and recycle concepts was developed. Reflux in membrane processes involves taking a portion of the effluent stream on the high pressure side and sending it to the low pressure side of the membrane, while recycle involves taking a portion of the permeate stream on the low pressure side and sending it to the high pressure side of the membrane. A predictive model was developed to study the effect of reflux and recycle on the specific energy consumption (SEC) and permeate quality when compared to conventional systems. In this study, the water permeability coefficients of membranes and brine recycle ratios were investigated. The results show that the SEC for a hybrid membrane processes comprising of RO and NF membrane was lower than conventional methods with the same recovery and feed concentration, suggesting that it is feasible to apply reflux and recycle concepts of distillation on desalination. Through the careful selection of RO membranes and NF membranes, benefits of reflux and recycle can be enjoyed for seawater desalination.

Corrosion Studies of High and Low Pressure Compressor Blades of a Gas Turbine

2005 ◽  
Author(s):  
A. Boschetti ◽  
E. Y. Kawachi ◽  
M. A. S. Oliveira
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Low Pressure ◽  
Compressor Blade ◽  
Compressor Blades ◽  
X Ray ◽  
Corrosion Studies ◽  
High Pressure Compressor ◽  
Pressure Compressor ◽  
Base Superalloy

This work presents preliminary results of corrosion studies for three blades, one of the low pressure compressor and two of two different stages of the high pressure compressor of a gas turbine, which has been operating for 5,000 hours. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray diffraction (XRD), Electrochemical Impedance Spectroscopy (EIS) in aqueous solution containing chloride, and Atomic Absorption Spectrometry (AAS) were used to characterize the blades surfaces. The SEM and EDS results showed that the homogeneity and amount of contaminants, such as sodium, potassium, calcium, magnesium, chloride and sulphur are bigger in the high pressure compressor blade surfaces than in the low pressure compressor blade surface. The EIS results showed that the degradation process in turbine compressor blades increases with the temperature and pressure increase inside the compressors and depends of the blade composition. The low pressure compressor blade, which was made of a Ti base superalloy exhibited smaller corrosion resistance (smallest charge transfer resistance value (Rct)) than the two high pressure compressor blades, which were made of a Fe base superalloy. However, despite of its lower resistance to corrosion, after 5,000 hours of service, the low pressure compressor blade did not present pitting corrosion while the high pressure compressor blades did.

Practical Experience With a Mobile Methanol Synthesis Device

2014 ◽  
Author(s):  
Eric R. Morgan ◽  
Tom Acker
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Methanol Synthesis ◽  
Low Pressure ◽  
Practical Experience ◽  
Gaseous Hydrogen ◽  
Water Mixture ◽  
Pressure Side ◽  
Northern Arizona ◽  
Northern Arizona University

Northern Arizona University has developed a methanol synthesis unit that directly converts carbon dioxide and hydrogen into methanol and water. The methanol synthesis unit consists of: a high pressure side that includes a compressor, a reactor, and a throttling valve; and a low pressure side that includes a knockout drum, and a mixer where fresh gas enters the system. Methanol and water are produced at high pressure in the reactor and then exit the system under low pressure and temperature in the knockout drum. The remaining, unreacted recycle gas that leaves the knockout drum is mixed with fresh synthesis gas before being sent back through the synthesis loop. The unit operates entirely on electricity and includes a high-pressure electrolyzer to obtain gaseous hydrogen and oxygen directly from purified water. Thus, the sole inputs to the trailer are water, carbon dioxide and electricity, while the sole outputs are methanol, oxygen, and water. A distillation unit separates the methanol and water mixture on site so that the synthesized water can be reused in the electrolyzer. Here, we describe and characterize the operation of the methanol synthesis unit and offer some possible design improvements for future iterations of the device, based on experience.

Pressure Variation in Low Pressure Side of Shell and Tube Heat Exchanger After Tube Rupture

2014 ◽  
Author(s):  
Ganesh S. Katke ◽  
M. Venkatesh ◽  
N. P. Gulhane
Keyword(s):  
High Pressure ◽  
Heat Exchanger ◽  
Low Pressure ◽  
Pressure Variation ◽  
Operating Pressure ◽  
Pressure Side ◽  
Tube Heat Exchanger ◽  
Analytical Algorithm ◽  
Shell And Tube ◽  
Design Pressure

This paper presents an analytical algorithm to determine the pressure variation on the Low Pressure side of a Shell and Tube Heat Exchanger (STHE) after a tube rupture and its validation using CFD simulation. STHEs are often used for exchanging heat between high-pressure (HP) and low-pressure (LP) fluids in the chemical process industry. In case tube rupture occurs in a STHE having a large pressure difference between HP and LP side, there is a risk of release of significant quantity of fluid from the HP side to the LP side. The consequent pressure build-up can lead to the failure of LP side pressure envelope. Generally, design pressure of the LP side is about 10–20% higher than the operating pressure of the LP side fluid, but well below the operating pressure on the HP side. There is no well-established methodology to design the LP side to withstand sudden release of high pressure fluid following a tube rupture. Three dimensional analyses were carried out using Computational Fluid Dynamics to study the pressure variation in LP side (shell side) of a Gas Cooler and to validate the results obtained from the analytical algorithm. It has been observed that the pressure on the LP side exceeds the design pressure instantaneously due to generation of a pressure pulse after tube rupture. This may lead to damage of LP envelope (shell) and internal structure of STHE.

Asymmetric Solution for Compressor Station Spare Capacity

2006 ◽  
Author(s):  
Rainer Kurz ◽  
Matt Lubomirsky
Keyword(s):  
High Pressure ◽  
Compression Ratio ◽  
Low Pressure ◽  
Compressor Station ◽  
Spare Capacity ◽  
High Pressure Compressor ◽  
Power Turbine ◽  
In Series ◽  
Asymmetric Solution ◽  
Pressure Compressor

Arranging compressor units in series rather than in parallel can offer a number of advantages in many applications. However, especially if the compression ratio is rather high, it is desirable to use different impellers for the low-pressure and the high-pressure compressor. Otherwise, one or both operate off their best efficiency points. This leaves however the problem of the staging of a spare unit. In the paper, a solution to this dilemma is described. To understand the underlying constraints, the relationships between the system resistance, the compressor characteristic, and the power turbine characteristic are analytically derived.

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