Steam Chest Research Articles

Expanded beads of polyethylene moldable at low steam pressure

In this study, we explored an innovative approach to extrude expanded polyethylene (ePE) bead foam by utilizing a blend of two types of polyethylene, specifically low-density and linear low-density polyethylene. The intention behind this mixture was to enhance the molding process’s flexibility during steam chest molding. The outcomes of our investigation reveal the adaptability of the devised method and formulation, enabling the production of a broad spectrum of foam densities ranging from 20 to 100 kg/m³. Additionally, we achieved successful molding at remarkably low steam pressures, below 0.6 bar. Our research focuses on the strategic adjustment of processing parameters, including temperature and pressure, along with optimized die geometry for the extrusion foam process. To comprehensively evaluate the foamed molded components, we conducted a comprehensive mechanical and optical analysis. The findings underscore the flexibility and cost-effectiveness of ePE produced through foam extrusion. This method emerges as a promising alternative to expandable polystyrene, especially in applications requiring flexible materials and convenient recyclability without contributing to microplastic pollution in the environment.

A review on semi-crystalline polymer bead foams from stirring autoclave: Processing and properties

Abstract Bead foams have been widely used for more than 70 years, with expandable polystyrene and expanded polypropylene (EPP) being the main materials. There are different processes for producing bead foams, depending heavily on the material used (e.g., their thermal behavior). EPP is usually produced by a discontinuous stirring autoclave process, which is the main subject of this study. In this process, thermal treatment during the saturation phase leads to the formation of a second melt peak, which is considered an important prerequisite for the subsequent welding process, in which the individual foamed beads are welded into complex shaped parts by applying saturated steam to the beads in a cavity (so-called steam chest molding). To date, EPP is one of the main bead foams used industrially, but other materials such as polylactide and thermoplastic polyurethane can also be processed using the same technique. This review focuses on the important thermal and physical mechanisms during saturation and expansion and the parameters (material and process) that affect them. The process itself provides multiple possibilities to influence thermal behavior (i.e., crystallization) and expansion. Typical properties of resulting bead foams, which are found in many applications, are also considered.

Nutritional value, productive performance, and economic efficiency response to the degree of steam-flaked yellow corn in growing rabbits.

The performance of a corn steam flaker was evaluated to improve steam-flaked corn (SFC) quality and investigate its feeding effects on nutritional value, productive performance, digestibility coefficients,and economic efficiency of growing rabbits. The flaker performance was studied as a function of change in steaming time, steam chest temperatureand roll gap. Performance evaluation of the flaker was carried out in terms of flake thickness (FT), flake density (FD) and processing index (PI) as well as rabbit feeding trials. Experimental results clarified that values of FT, FDand PI are in the optimal limits under conditions of 118°C steam chest temperature, 40 min steaming time and 0.80 mm roll gap. Steam flaking is an acceptable process for rabbit feeds as SFC with optimal FD of between 0.36 and 0.39 kg/L corresponding to a PI of between 50.14% and 54.32% significantly improve the nutritional value of SFCcompared with whole corn grain by 1.31%, 1.26% and 160.75%respectively. Also, SFC severely decreased the total count of harmful bacteria, fungi countand mortality rate compared to whole corn grain. Rabbits fed SFC processed to the density of 0.36 kg/L of the diet had better body weight gain, feed conversion ratio, organic matter digestibility, net revenueand economic efficiency of 9.29%, 8.89%, 4.65%, 15.62%and 15.43% compared with rabbit fed whole yellow corn grainrespectively. In conclusion, it is convenient to entirely substitute whole corn grain with SFC to be utilised in rabbits' diets where achieved the best feeding effects results.

Influence of Molecular Weight on the Bead Foaming and Bead Fusion Behavior of Poly(butylene terephthalate) (PBT)

A current trend in the progress of bead foams is the use of engineering polymers (i.e., poly(butylene terephthalate) (PBT)), which are more temperature resistant than commodity polymers and thus offer new areas of application. Currently, foaming and molding of PBT bead foams seem to be possible only with an epoxy-based chain extender. This modification leads not only to an increase in molecular weight but also to a changed PBT chain architecture (i.e., branching or even cross-linking). Thereby, the crystallization behavior is considerably slowed down so that the time for chain interdiffusion across neighboring bead surfaces is prolonged. This study investigates the molecular weight influence separately. The crystallization behavior is controlled by varying the length of linear PBTs in such a way that different bead fusion phenomena result. With increasing molecular weight, a lower open cell content (OCC), and therefore a higher expansion behavior during thermomechanical analysis, was observed, which increases the contact area between the beads in the cavity during the steam chest molding process. Adding to the literature shown so far, this study shows that linear chemically unmodified PBT can also be processed into bead foam components using PBTs having a higher molecular weight.

Evaluation of the Fusion Quality of Bead Foams Made from Polybutylene Terephthalate (E‐PBT) Depending on the Processing Temperature

AbstractIncreasing requirements are leading to new developments in bead foam materials. Engineering thermoplastics such as polybutylene terephthalate (PBT) outperform standard bead foams in thermal stability. In order to obtain molded parts, beads are fused together using steam chest molding. Classical theories for the fusion mechanism, explaining the molding of amorphous EPS (expandable polystyrene) or semi‐crystalline EPP (expanded polypropylene), cannot be applied to E‐PBT (expanded polybutylene terephthalate). In previous studies, sufficient time for polymer interdiffusion during molding is identified as crucial and requires adjusted crystallization kinetics. This study consequently examines to which extent the crystalline properties and the bead fusion behavior of E‐PBT can be influenced by the bead foaming process. By varying the underwater granulation (UWG) water temperature, different cooling rates of the expanding melt are generated. The foamed beads show different cell morphologies, thermal and dynamic mechanical properties depending on the UWG water temperature. Those beads that show a pronounced shrinkage behavior in the thermomechanical analysis, caused by an increased open cell content and a pronounced cold‐crystallization, exhibit a reduced bead fusion quality. The bead fusion quality is examined by the fracture surface. The shrinkage phenomenon causes a reduced bead to bead contact and partially separation between the beads.

KNOWLEDGE AND PRACTICE OF STAFF NURSES REGARDING PREVENTION OF POSTOPERATIVE SURGICAL COMPLICATIONS OF PATIENT UNDERGOING ABDOMINAL SURGERY AT SELECTED HOSPITALS, SIKKIM.

The term abdominal surgery broadly covers surgical procedures that involve opening the abdomen. After abdominal surgeries, patients are at the risk of developing complications. The common postoperative complications after the abdominal surgery include pneumonia, deep vein thrombosis and surgical site infections. The aim of the present study was to assess knowledge and practice of staff nurses regarding prevention of postoperative surgical complications of patient undergone abdominal surgery. Adescriptive survey study was conducted in hospitals, of Gangtok, Sikkim. Data were collected using structured knowledge questionnaires and observational checklist from 60 staff nurses working in Surgical ICU and surgery ward selected by non-probability purposive sampling technique. The ndings revealed that majority of the staff nurses i.e out 60 staff nurses, 49(82%) had average knowledge and 11(18%) had good knowledge. Majority of staff nurses 44(73%) had good practice and 16(27%) had poor practice regarding prevention of postoperative surgical complications and also showed that there was a moderately positive correlation between knowledge and practice of staff nurses regarding prevention of postoperative surgical complications (r=0.2). Based on the ndings of the study, it can be concluded that in spite of having good practice level regarding prevention of postoperative surgical complications, staff nurses had average knowledge level. Knowledge and practice of the staff nurses in some certain area of prevention of postoperative surgical complications such as providing steam inhalation and chest physiotherapy, preventive measures for surgical site infection, assessment of pain in calf muscle, providing education to patient and family members need to be improved.

Simulative study of polymeric core–shell foam particles for the enlargement of the material portfolio in 3‐D high‐frequency welding

AbstractThe steam chest molding process is currently state of the art concerning the generation of three‐dimensional polymeric foam components made from particle foams. An adaption of the high‐frequency welding process shows advantages regarding the required energy and the used water. Due to the low dielectric loss factors of the most common foam materials (PE, PP, and PS), they cannot be heated sufficiently by an electric field. To enable heating of these foams, the particles may be coated with a second material that shows a high dielectric loss. The possible heat development of the modified particles was simulatively investigated. To ensure a realistic simulation, the properties of the used materials are analyzed beforehand. The heating simulation shows clear dependence regarding the particle size and the shell thickness. By a suitable combination, sufficient heating is achievable. For single particles, an irregular temperature distribution is calculated, mainly caused by the difference of permittivity resulting in a local variation of electrical flux density. Bigger particles and thicker shells will result in faster heating ramps and higher overall temperatures. The additional calculation regarding a particle–particle interaction shows a homogenization of the temperature distribution across the particle surface.

Broadband microwave absorption performance and theoretical dielectric properties model of hollow porous carbon spheres/expanded polypropylene composite foams

Hollow porous carbon spheres (HPCS)/Expanded polypropylene (EPP) composite foams were prepared by rapid expansion of supercritical solution and steam chest molding. Due to the uniform and continuous foam structure, HPCS/EPP foams can maintain better loss ability at lower permittivity. Excellent impedance matching enables them to achieve ultra-broad absorption bandwidth of over 17 GHz. Furthermore, the high frequency dielectric properties of HPCS/EPP foams with unique dual percolation microstructure were described by the Two Exponent Phenomenological Percolation Equation (TEPPE) in a two-step framework. It was revealed that the fitting values of the complex permittivity of the foams with different expansion ratios are in good agreement with the experimental values in the frequency band from 0.5 to 18 GHz. This work introduces a new approach for predicting and optimizing the electromagnetic properties of ternary foamed composites.

Compression Molding of Thermoplastic Polyurethane Foam Sheets with Beads Expanded by Supercritical CO2 Foaming.

Expanded thermoplastic polyurethane (ETPU) beads were prepared by a supercritical CO2 foaming process and compression molded to manufacture foam sheets. The effect of the cell structure of the foamed beads on the properties of the foam sheets was studied. Higher foaming pressure resulted in a greater number of cells and thus, smaller cell size, while increasing the foaming temperature at a fixed pressure lowered the viscosity to result in fewer cells and a larger cell size, increasing the expansion ratio of the ETPU. Although the processing window in which the cell structure of the ETPU beads can be maintained was very limited compared to that of steam chest molding, compression molding of ETPU beads to produce foam sheets was possible by controlling the compression pressure and temperature to obtain sintering of the bead surfaces. Properties of the foam sheets are influenced by the expansion ratio of the beads and the increase in the expansion ratio increased the foam resilience, decreased the hardness, and increased the tensile strength and elongation at break.

Combination of Cyclic Steam Stimulation and Steam Flooding to Improve Oil Recovery in Unconsolidated Sand Heavy Oil Reservoir

Steam injection can be success in increasing oil recovery by determining the steam chamber growth. It will impact on the steam distribution and steam performance in covering hot areas in the reservoir. An injection plan and a proper cyclic steam stimulation (CSS) schedule are critical in predicting how steam chamber can grow and cover the heat area. A reservoir simulation model will be used to understand how CSS really impact in steam chamber generation and affect the oil recovery. This paper generates numerous scenarios to see how steam working in heavy oil system particularly in unconsolidated sand reservoir. Combine the CSS method and steam injection continue investigate in this research. We will validate the scenarios based on the how fast steam chest can grow and get maximum oil recovery. Reservoir simulation resulted how steam chest behavior in unconsolidated sand to improve oil recovery; It concluded that by combining CSS and Steam Injection, we may get a faster steam chest growth and higher oil recovery by 61.5% of heavy oil system.

Simulation of Turbine-Generator

This study involved mathematical modeling of turbine generator simulator (TGS) and speed governing system for Fast Breeder Reactor (FBR). All steam turbine system utilize governor controlled valves at the inlet to the turbine to control the steam flow. The previously developed FBR and Pressurized water reactors (PWR) mathematical models (by author) [1] were connected to the same Turbine-generator model and controlled by the same method of control. Then a comparison between the dynamic performance transient response of FBR and PWR controlled plants were considered in two cases, load demand perturbation and reactivity perturbations. The steam chest and inlet piping to the turbine cylinder introduce delays between valve movement and change in the steam flow. The results show that the model is capable of simulating the dynamic transient response for FBR in two cases, load demand perturbation and reactivity perturbations.

Parameters calculation of thermal power plant dynamic model using steam cycle data

Standard models are created to carry out power system dynamic studies. One of the major problems in this regard is the parameter identification of these models. These parameters are not constant and may change due to extensive use and the large number of repairs, modifications and overhaul of the units, and, consequently, they cannot provide a reliable basis for further use. Thus, actual parameters need to be determined. This paper determines the actual parameters of a real 150 MW tandem compound, single reheat steam turbine located in the Egyptian network since 1986 using the available unit steam cycle data. The time constants of Steam Chest, reheater and cross over are calculated. The power fractions of high pressure (HP), intermediate pressure (IP) and low pressure (LP) turbine stages are also estimated. The calculated parameters are compatible with IEEEG1 general steam turbine model. Finally, parameters validation is investigated by comparing the actual and simulated turbine power response. Also governor and turbine speed responses are provided. The simulation is carried out by DIgSILENT power factory software.

New method for monitoring steam injection for Enhanced Oil Recovery (EOR) and for finding sources of geothermal heat

A database of over 10,000 wells with open hole logs, of which over 600 wells are dedicated surveillance wells with whole core, time lapse Carbon/Oxygen, Neutron, and Temperature data being used for evaluating Adrok’s deep penetrating radar system.Kern River (California) is on its way to recovering 90% of its OOIP and surveillance is playing a significant role in achieving such a world class milestone. Future growth for development of the field and surveillance technologies still exist as well. To that end, we are looking at the possibly of surface only acquisition for Chevron’s surveillance needs.Significant time and effort was spent on dielectric logging in the 1970’s - 80’s by operators and service companies. Adrok’s Atomic Dielectric Resonance (ADR) scanning technology claims to interact with the subsurface in the same region of the electro-magnetic spectrum as di-electric logging, but from surface measurement. First Principles predicts a rise in dielectric constant as temperature rises. Fieldwork was conducted during 2014 to 2016. The surveys were divided up into two groups, one for training (full access to database) and one for blind testing (no access to database). Surprisingly, the blind tests could detect the presence or absence of a single zone steam chest by a rise in dielectric constant at the correct space-time.Atomic Dielectric Resonance (ADR) is a patented investigative technique (Stove, 2005) which involves the measurement and interpretation of resonant energy responses of natural or synthetic materials to the interaction of pulsed electromagnetic radio-waves from materials which permit the applied energy to pass through the material. Radiowaves (typically in the frequency range of 1MHz to 100MHz) are continuously pulsed into the ground from an ADR transmitter antenna and the responses from the ground are gathered at the ground surface by an ADR receiver antenna. The resonant energy response can be measured in terms of energy, frequency and phase relationships. The precision with which the process can be measured helps define the unique interactive atomic or molecular response behaviour of any specific material, according to the energy bandwidth used. ADR is measurable on a very wide range of hierarchical scales both in time and space. Time scales may range from seconds to femtoseconds, and spatial scales from metres to nanometres. The technology has been applied to help mining and petroleum companies in their search for subsurface natural resources, some of which are described in this contribution.The body of the oral presentation describes in greater detail the technology, field experiments and results to date for Chevron. Results from onshore geothermal heat exploration at a number of sites in New Zealand are also presented.

Real‐time parameter estimation based intelligent controllers for AGC operation under varying power system dynamic conditions

In this paper, real-time parameter estimation based intelligent controller has been proposed for the optimum automatic generation control (AGC) operation of multi-area interconnected power system. In earlier AGC studies, supplementary controllers were designed for presumed power system dynamic conditions, such as constant system loadings, fixed values of power system dynamic model parameters. However in practical AGC system, these power system model parameters, namely frequency bias parameter B, steam chest and reheater time constants & , power system time and gain constants & , load sensitivity factor D, etc., continuously varies depending upon the consumer's load demand and number of power generating units participating in AGC. The controller's operation no longer remains optimum as these system parameters changes from their initial values. In view of the above, parameter estimation based real-time intelligent controller has been designed which automatically adjusts its controller gain settings to its optimum conditions in real-time after sensing changes in power system model parameters. At first, different methodologies are presented to estimate dominant power system model parameters. Then, presented methodologies are utilised in the design of intelligent controller for AGC system. The proposed controller is successfully tested upon IEEE 39 bus system with various case studies.

AGC of Two Area Power System Based on Different Power Output Control Strategies of Thermal Power Generation

In this paper, dynamic performance of automatic generation control (AGC) of two area thermal–thermal power system is determined through the steam chest and reheater constant trajectories. In earlier AGC studies, steam chest and reheater time constants denoted as ${T_{\text{SC}}}$ and ${T_{\text{RH}}}$ are considered to be constant, irrespective of plant generation schedules. However, it is discovered that ${T_{\text{SC}}}$ and ${T_{\text{RH}}}$ follow the specific trajectories with the plant generation schedules. These time constant trajectories are determined by the power output control strategies being employed to change the plant generation schedules. These control strategies are the different combinations of steam pressure versus flow rate curves used to operate the plant at different generation schedules. In this paper, time constant versus generation schedule trajectories of ${T_{\text{SC}}}$ and ${T_{\text{RH}}}$ have been derived for different power output control strategies. Furthermore, these time constant trajectories have been utilized to investigate the dynamic performance of two area reheat thermal power system.

Influence of Spin Projection Noise on the Sensitivity of Cs Atom Magnetometer

This article introduces the influence of laser's spin projection noise on the sensitivity of Cs atom magnetometer and concludes that the theoretical value of the spin projection noise is about1.23fT·Hz -1/2 under the optimization condi- tions of the atom steam chest, namely temperature as 105°C, volume as 0.0785cm 3 and molecular density as 1.7×10 13 cm -3 . Such research has provided us with the necessary basis for the experimental study on Cs atom magnetometer.

Continuous Seismic Reservoir Monitoring of Thermal Enhanced Oil Recovery

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 165428, ’Continuous Land Seismic Reservoir Monitoring of Thermal EOR in the Netherlands,’ by Julien Cotton, Laurene Michou, and Eric Forgues, CGG, and Kees Hornman, Shell Global Solutions International, prepared for the 2013 SPE Heavy Oil Conference Canada, Calgary, 11-13 June. The paper has not been peer reviewed. A reservoir-monitoring system has been installed on a medium-heavy-oil onshore field in the context of redevelopment by gravity-assisted steamflood. The challenge was to monitor the lateral and vertical expansion of the steam chest continuously with seismic reflection. The high sensitivity of the buried acquisition system allows the tracking and monitoring of very small variations of the reservoir’s physical properties in both the spatial and calendar domains. A daily 4D “movie” of the changes allows proposing a scenario that explains the unexpected behavior of the production. Introduction The Schoonebeek field is in the northeast of the Netherlands with 1 billion bbl of stock-tank oil initially in place. Between 1948 and 1996, the oil was produced with several small-scale thermal enhanced-oil-recovery pilots with vertical wells. Today, the oil is produced by gravity-assisted steamdrive. A permanent seismic system including 2D and 3D phases was installed in 2010 to monitor the reservoir’s evolution during steam injection. The monitoring lasted 2 years. During this time, the propagation of the steam plume injected into a horizontal well located between two horizontal producer wells was tracked in order to understand the 4D behavior of the steam and possibly update the dynamic production model.

Continuous Land Seismic Reservoir Monitoring of Thermal EOR in the Netherlands

A permanent reservoir monitoring system has been installed for Shell, on a medium heavy-oil onshore field situated in the NE of The Netherlands, in the context of re-development of oil production by Gravity Assisted Steam Flood. The challenge was to continuously monitor with seismic reflection the lateral and vertical expansion of the steam chest injected in the reservoir during production over more than a year. The main problems for onshore time-lapse are caused by near-surface variations between base and monitor surveys which affect the seismic signal coming from the reservoir. Here, a set of permanent shallow buried sources and sensors have been installed bellow the weathering layer to both mitigate the near surface variation and minimize the environmental footprint. The very high sensitivity of our buried acquisition system allows for the detection and mapping of tiny changes within the reservoir on a daily basis and permits to follow very small variations of the reservoir physical properties in both spatial and calendar domains. The 4D reservoir attributes obtained from seismic monitoring fit the measurements made at observation, production and injector wells (pressure, temperature and oil/water production). '4D movie' if the reservoir properties allows proposing a scenario which explains the unexpected behavior of the production and confirms that the steam does not follow the expected path to the producer wells but rather takes a more complicated 3D path within the reservoir.

Optimized load-frequency simulation in restructured power system with Redox Flow Batteries and Interline Power Flow Controller

This paper proposes the Load Frequency Control (LFC) of an interconnected two-area multiple-unit thermal reheat power system in a restructured environment. In the restructured scenario, various kinds of apparatus with large capacity and fast power consumption may cause a series problem of frequency oscillations. The oscillation of system frequency may sustain and grow to cause a series frequency stability problem if no adequate damping is available. Moreover, the larger amount of the steam stored in steam chest and reheater of thermal power plant delays the control valve motion to increase the mechanical power output after the load perturbation. So in order to stabilize the system, impacts of Interline Power Flow Controller (IPFC) in series with tie-line and Redox Flow Batteries (RFB) at the terminal of area 1 have been investigated. The Bacterial Foraging Optimization (BFO) algorithm is used to optimize the integral gains of the Load-frequency Controller under different transactions in the competitive electricity market. Compliance with North American Electric Reliability Council (NERC) standards for Load Frequency Control has also been established in this work. Simulation studies reveal that the RFB coordinated with IPFC units for LFC loop has greater potential for improving the system’s dynamic performance.

The Influence of Overlap Degree Research on Nozzle Governing Characteristic

To solve the problems existing in the flow characteristics of steam turbine unit, the influence of valve overlap degree on nozzle governing steam turbine had been studied. The combined flow characteristics of given valve overlap degree were obtained for a 600MW steam turbine unit by the method of theoretical calculation combined with simulation test, and the influence of valve overlap degree on governing stage efficiency and steam chest pressure had been also analyzed. This paper discussed the selection of rational overlap degree and introduced a new method of building model for governing stage efficiency of steam turbine in constant pressure operation condition, which provided theoretical guidance for optimization research on nozzle governing steam turbine operation.