scholarly journals Heat Transfer Characteristics of Heat Exchangers for Waste Heat Recovery from a Billet Casting Process

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2695
Author(s):  
Ju O Kang ◽  
Sung Chul Kim
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Waste Heat ◽  
Casting Process ◽  
Effective Area ◽  
Total Heat ◽  
Process Conditions ◽  
Heat Absorption ◽  
Industrial Facilities ◽  
The Difference

The application of the thermoelectric generator (TEG) system to various industrial facilities has been explored to reduce greenhouse gas emissions and improve the efficiency of such industrial facilities. In this study, numerical analysis was conducted according to the types and geometry of heat exchangers and manufacture process conditions to recover waste heat from a billet casting process using the TEG system. The total heat absorption increased by up to 10.0% depending on the geometry of the heat exchanger. Under natural convection conditions, the total heat absorption increased by up to 45.5%. As the minimum temperature increased, the effective area increased by five times. When a copper heat exchanger of direct conduction type was used, the difference between the maximum and minimum temperatures was significantly reduced compared to when a stainless steel heat exchanger was used. This confirmed that the copper heat exchanger is more favorable for securing a uniform heat exchanger temperature. A prototype TEG system, including a thermosyphon heat exchanger, was installed and a maximum power of 8.0 W and power density of 740 W/m2 was achieved at a hot side temperature of 130 °C. The results suggest the possibility of recovering waste heat from billet casting processes.

Development of Heat Exchanger Fouling Model and Preventive Maintenance Diagnostic Tool

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
H. Zabiri ◽  
V. R. Radhakrishnan ◽  
M. Ramasamy ◽  
N. M. Ramli ◽  
V. Do Thanh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Predictive Model ◽  
Diagnostic Tool ◽  
Preventive Maintenance ◽  
Heat Exchangers ◽  
Waste Heat ◽  
A Priori ◽  
Transfer Efficiency ◽  
Heat Transfer Efficiency

The Crude Preheat Train (CPT) is a set of large heat exchangers which recover the waste heat from product streams back to preheat the crude oil. The overall heat transfer coefficient in these heat exchangers may be significantly reduced due to fouling. One of the major impacts of fouling in CPT operation is the reduced heat transfer efficiency. The objective of this paper is to develop a predictive model using statistical methods which can a priori predict the rate of the fouling and the decrease in heat transfer efficiency in a heat exchanger in a crude preheat train. This predictive model will then be integrated into a preventive maintenance diagnostic tool to plan the cleaning of the heat exchanger to remove the fouling and bring back the heat exchanger efficiency to their peak values. The fouling model was developed using historical plant operating data and is based on Neural Network. Results show that the predictive model is able to predict the shell and tube outlet temperatures with excellent accuracy, where the Root Mean Square Error (RMSE) obtained is less than 1%, correlation coefficient R2 of approximately 0.98 and Correct Directional Change (CDC) values of more than 90%. A preliminary case study shows promising indication that the predictive model may be integrated into a preventive maintenance scheduling for the heat exchanger cleaning.

Addressing Fouling by Qualifying Chemical Additives Using Novel Technologies

2021 ◽  
Author(s):  
Andrew Robert Farrell ◽  
Dario Marcello Frigo ◽  
Gordon Michael Graham ◽  
Robert Stalker ◽  
Ernesto Ivan Diestre Redondo ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Emulsion Stability ◽  
Ambient Pressure ◽  
Screening Tests ◽  
Process Conditions ◽  
Screening Methods ◽  
Chemical Additives ◽  
Laboratory Techniques ◽  
Prediction And Prevention

Abstract Fouling of heat exchangers and production of stable emulsions in desalting units can present significant challenges in refinery operations. Often these difficulties occur due to the concurrent processing of two or more crude oils that are incompatible under process conditions. This paper describes a significant development in laboratory techniques for studying these issues and evaluating mitigation strategies. Asphaltenes compatibility was evaluated for oil mixtures that may be co-processed in the refinery using a deposition flow rig, and the results were compared with those obtained with more conventional tests: blending stability analysis by light scattering and various screening methods. The flow rig mimics the process conditions (elevated pressure, high temperature, flow-induced shear) and identifies whether deposition or precipitation will occur. The former can cause fouling of heat exchangers whereas the latter produces solids that can stabilize emulsions in the desalter. By varying the proportions of oils that were co-injected into the deposition flow rig, the range within which mixtures were unstable was found. By flowing through a capillary (to mimic a heat exchanger) and in-line filter, it was possible to identify whether precipitation of suspended flocs or fouling of the heat exchanger itself was the likely issue for each mixture. Emulsion-stability tests were conducted using a pressurized rig with an ersatz separator to mimic the desalting unit; results were compared with those obtained in conventional, ambient-pressure bottle tests. Oil(s) and refinery wash water were injected, mixed under representative shear, and allowed to separate within the typical residence time of the desalter. Chemical additives were tested to identify those that were effective at controlling any observed problems. Results obtained in either flow rig (using representative pressure, temperature, and shear) did not always match those obtained using conventional methods. Asphaltenes fouling occurred under conditions where it was not predicted by screening tests that were conducted at conditions not representative of the process and did not occur under conditions where it was predicted. Differences were also observed between the emulsion stability observed in bottle versus rig tests, though these should be viewed as complementary techniques. This paper presents new laboratory techniques for the prediction and prevention of refinery fouling and emulsion stability. They mimic conditions in the facilities much better than those typically used to date.

The Potential Danger of Fire in Gas Turbine Heat Exchangers

1969 ◽  
Author(s):  
C. F. McDonald
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Engine Operation ◽  
Exhaust Heat ◽  
The Subject ◽  
Gas Turbine Cycle

Increased emphasis is being placed on the regenerative gas turbine cycle, and the utilization of waste heat recovery systems, for improved thermal efficiency. For such systems there are modes of engine operation, where it is possible for a metal fire to occur in the exhaust heat exchanger. This paper is intended as an introduction to the subject, more from an engineering, than metallurgical standpoint, and includes a description of a series of simple tests to acquire an understanding of the problem for a particular application. Some engine operational procedures, and design features, aimed at minimizing the costly and dangerous occurrence of gas turbine heat exchanger fires, are briefly mentioned.

Analysis and Design of the “Solar One” Thermal Storage Subsystem Heat Exchangers

1984 ◽  
Vol 106 (3) ◽  
pp. 279-285
Author(s):  
F. R. Weiner
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Thermal Storage ◽  
Design Solution ◽  
Process Conditions ◽  
Analysis And Design ◽  
Heat Exchanger Design ◽  
Central Receiver ◽  
Final Design ◽  
Design Requirements

This paper describes the analysis and design of the five kinds of heat exchangers used in the thermal storage subsystem of the 10 MWe Solar Central Receiver Pilot Plant, now becoming more known as “Solar One.” The paper discusses the practices and standards used in the designs of the heat exchangers, lists the heat exchanger design requirements, and discusses the process conditions. The design assumptions and constraints, the geometrical considerations, and the tradeoff studies that were conducted to optimize the designs are also discussed. A description of each heat exchanger reveals the final design solution. Novel and unique features of a power plant that must operate on a daily sun-cycle are identified.

scholarly journals Estimation of Shutdown Schedule to Remove Fouling Layers of Heat Exchangers Using Risk-Based Inspection (RBI)

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2177
Author(s):  
Abdelnaser Elwerfalli ◽  
Salih Alsadaie ◽  
Iqbal M. Mujtaba
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Oil And Gas ◽  
Waste Heat ◽  
Complex Phenomenon ◽  
Cleaning Process ◽  
Chemical Substances ◽  
Operation Period ◽  
The Heat Transfer Coefficient ◽  
Gas Plants

Oil and Gas plants consist of a set of heat exchangers, which are used in recovering the waste heat from product streams to preheat the oil. The heat transfer coefficient of exchangers declines considerably during the operation period due to fouling. Fouling in heat exchangers is a complex phenomenon due to the acceleration of many layers of chemical substances across tubes of heat exchangers resulting from chemical reactions and surface roughness. In this paper, the fouling process was determined as a critical failure in the heat exchanger. Failure is an accelerated fouling layer across the heat exchanger tubes, which can be the reason for the clogging of tubes. Hence, a risk assessment was conducted using the Risk-Based Inspection (RBI) approach to estimate the probability of fouling in heat exchangers. The results showed that the RBI approach can be used successfully to predict the suitable time to shut down the plant and conduct the fouling cleaning process.

Thermomechanical Treatment of Aluminum Alloy Fin Stock for Heat Exchanger Produced by Twin Roll Strip Casting Process

2010 ◽  
Vol 638-642 ◽  
pp. 241-246 ◽  
Author(s):  
Suk Bong Kang ◽  
Dong Bae Kim ◽  
Sang Su Jung ◽  
Kwang Jun Euh
Keyword(s):  
Thermal Conductivity ◽  
Aluminum Alloy ◽  
Heat Exchanger ◽  
Cold Rolling ◽  
Heat Exchangers ◽  
Casting Process ◽  
Strip Casting ◽  
Manufacturing Cost ◽  
Intermediate Annealing ◽  
Twin Roll

Aluminum alloys are commonly used as a material for heat exchangers due to their higher thermal conductivity and specific strength among various metallic materials. The lightweightening heat exchangers for automobile application are requisite for reducing the evolution of CO2 and improving the efficiency of fuel. The twin roll strip casting process is considered to produce the high quality and low manufacturing cost aluminum alloy fin stock for automobile heat exchangers. Thermomechamical treatment has carried out to obtain optimum processes for initial cold rolling, intermediate annealing and final cold rolling, which can meet the requirements for high strength and high thermal conductivity after brazing heat treatment. Mechanical properties and thermal condutivity have been evaluated before and after simulated brazing process. The nuclei of recrystallization might be formed along shear deformation bands during initial cold rolling and should be grown during intermediate annealing to enhance the permeation of molten brazings for the following brazing process. Final cold rolling has allowed strain hardening and controlling of sagging amount as fin stock materials of heat exchanger. In the present study the suitable thermomechnical treatment was suggested to balance the properties of strength, thermal conductivity, brazing behavior and sagging in Al-Fe-Mn-Si-Zn based alloys produced by twin roll strip casting process.

Successful Sealing of Heat Exchangers Due to the Implementation of New Technology in a Gasket System

2005 ◽  
Author(s):  
Julie L. Simonton ◽  
David W. Reeves
Keyword(s):  
Thermal Expansion ◽  
Heat Exchanger ◽  
Test Data ◽  
Heat Exchangers ◽  
New Technology ◽  
Process Conditions ◽  
Successful Implementation ◽  
Differential Thermal Expansion ◽  
Effective Seal ◽  
Subsequent Failure

Research into the historical use and subsequent failure of double-jacketed type gaskets in heat exchangers has yielded the characteristics necessary for leak elimination and the realization that maintaining a seal cannot be achieved by gasket specification alone. An evaluation of the heat exchanger, stud load, tightening method, gasket specification, proper installation procedures, process conditions, as well as stud selection must each be carefully considered to consistently create an effective seal. This paper highlights field test data from a refinery on the differential thermal expansion of flanges and how the gasketed connection is affected. Laboratory test data, specifically Radial Shear Tightness Test, or Ra.S.T., data, which mimics the radial shearing effects on a gasket in a heat exchanger, as well as verifying the effects on the gaskets in the field, is also presented. The details of the new technology in a gasket system for heat exchangers, perfected in conjunction with Chevron and Lamons Gasket Company, will be presented along with its successful implementation at a major petrochemical refinery.

Performance Evaluation of Multi-Stage Shell and Tube Transport Membrane Condenser Heat Exchangers for Low Grade Waste Heat and Water Recovery

2017 ◽  
Author(s):  
Soheil Soleimanikutanaei ◽  
Cheng-Xian Lin ◽  
Dexin Wang
Keyword(s):  
Water Vapor ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Power Plants ◽  
Ceramic Membrane ◽  
Waste Heat ◽  
Low Grade ◽  
Water Recovery ◽  
Multi Stage ◽  
Shell And Tube

In this work for the first time the performance of multi-stage shell and tube Transport Membrane Condenser (TMC) based heat exchangers are evaluated numerically. The present heat exchanger is design to work under high pressure and temperature condition for both heat and water recovery in Oxy-Combustion processes. TMC heat exchangers use the nano-porous and ceramic membrane technology to extract the water vapor and latent heat of condensation from the flue-gas. The most important application of TMC heat exchangers is in the power plants which the water vapor in the presence of other non-condensable gases (i.e. CO2, O2 and N2) exist. Effect of the different arrangement of the multi-stage shell and tube TMC heat exchangers, number of branches and number of heat exchangers in each branch on the heat transfer and water recovery have been studied numerically. A single phase multi-component model is used to assess the capability of single stage TMC heat exchangers in terms of waste heat and water recovery at various inlet conditions. Numerical simulation has been performed using ANSYS-FLUENT software and the condensation rate model has been implemented applying User Define Function. Finally, an optimum configuration for the TMC heat exchanger unit has been proposed and the results of numerical simulations are depicted in terms of temperature and water vapor mass fraction contours.

scholarly journals Investigation of effect of heat exchanger size on power output in low-temperature difference Stirling engines

2021 ◽  
Vol 313 ◽  
pp. 03002
Author(s):  
Linda Hasanovich ◽  
David Nobes
Keyword(s):  
Heat Exchanger ◽  
Low Temperature ◽  
Power Output ◽  
Heat Exchangers ◽  
Waste Heat ◽  
Significant Loss ◽  
Stirling Engine ◽  
Dead Volume ◽  
Optimal Geometry ◽  
Stirling Engines

The Stirling engine is capable of converting any source of thermal energy into kinetic energy, which makes it an attractive option for utilizing low-temperature sources such as geothermal or waste heat below 100 °C. However, at these low temperatures, the effects of losses are proportionally higher due to the lower thermal potential available. One such significant loss is excess dead volume, wherein a significant contributor is the heat exchangers. The heat exchangers must be selected to optimize power output by minimizing the dead volume loss while maximizing the heat transfer to and from the engine. To better understand what the optimal geometry of the heat exchanger components is, a Stirling engine is modelled using a third-order commercial modelling software (Sage) and trends of engine properties of power, temperature, and pressure for different heat exchanger geometries are observed. The results indicate that there is an optimum heat exchanger volume and geometry for low temperature Stirling engines. This optimum is also affected by other engine properties, such as regenerator size and engine speed. These results provide insight into the optimal geometry of these components for low-temperature Stirling engines, as well as providing design guidance for future engines to be built.

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