Condensate Pump Research Articles

Development of a human reliability assessment technique for the maintenance procedures of marine and offshore operations

Continuous monitoring and maintenance of assets is important for safe and reliable marine and offshore operations. On-board maintenance activities carried out by seafarers/operators are often prone to error, leading to an accident. Marine environmental and operational conditions significantly affect human performance and influence seafarers/operators to make un-intentional errors. International Maritime Organization (IMO) guidance recommends implementing Human Error Assessment and Reduction Technique (HEART) for assessing the effect of human error probability considering quantitative risk analysis of shipping and offshore operations. The conventional HEART is not specifically developed to apply to marine and offshore operations and therefore it is necessary to develop an operational specific methodology capturing unique features of marine environment and operations. In this study, by revising and modifying the HEART to assess and quantify the potential human errors in different marine environmental and operational conditions, a new methodology is developed. As a part of the developed methodology, the Error Producing Condition (EPC) and Error Influencing Factor (EIF) tables are refined and developed to reflect the particular conditions of marine environments for Human Error Probability (HEP) estimation. The EIF tables for both engine and deck departments are developed separately considering the answers to a questionnaire survey among experienced seafarers from around the world. As the case studies the developed methodology is applied to the maintenance procedures of a marine engine exhaust turbocharger and also a condensate pump on an offshore oil and gas facilities. Application of the developed methodology confirms that extreme weather, extreme workplace temperature, high ship motion, high level of noise and vibration, and work overload and stress increase the likelihood of human error as well as potential accidents. It is intended that application of this developed methodology in human factor risk assessment will assist in improving the safety and reliability of the current maintenance practices in marine and offshore operations.

Application of heterogeneous blading systems is the way for improving efficiency of centrifugal energy pumps

The results of independent research implemented by the teams of authors representing the Brno University of technology (Czech Republic) and Moscow Power Engineering Institute National Research University (Russia) are presented and compared. The possibilities for improving the energy efficiency of slow-speed centrifugal pumps (with a specific speed coefficient n s < 80) widely used in power engineering—in thermal power stations, in heat electric-power stations, in nuclear power plants, and in boiler rooms—were investigated. These are supply pumps, condensate pumps, precharge pumps, etc. The pumps with such values of n s are widely used in some technological cycles of oil-and-gas and chemical industries too. The research was focused on achieving the shape of the pump efficiency characteristics providing a significant extension of its effective working zone and increasing its integrated efficiency. The results were obtained based on new approaches to the formation of a blading system of an impeller of a slow-speed centrifugal pump different from the traditional blading system. The analytical dependences illustrating the influence of individual geometry of a blading system on the efficiency were presented. The possibilities of purposeful changing of its structure were demonstrated. It was experimentally confirmed that use of the innovative blading system makes it possible to increase the pump efficiency by 1–4% (in the experiments for the pumps with n s = 33 and 55) and to extend its efficient working zone approximately by 15–20% (in the experiment for the pumps with n s = 33 and 66). The latter is especially important for the supply pumps of NPP power units. The experimental results for all investigated pumps are presented in comparison with the characteristics of the efficiency provided by the blading systems designed by traditional methods.

Heat transfer in an evaporation-condensation system in simulated weightlessness conditions

The process of heat transfer in an evaporation-condensation system (ECS) at circulation of dielectric liquid in a closed thermoelectrohydrodynamic (TEHD) loop consisting of an evaporator, a condenser and electrohydrodynamic (EHD) pump for pumping of heat carrier, is considered. Previously, the authors studied the dependence of heat transfer on the angle of rotation of TEHD loop in a vertical plane. The report contains the results of studies of heat transfer at electrohydrodynamic pumping of the heat carrier (8% solution of acetone in Freon 113) in the condenser area by means of EHD pump of “cone-cone” type. All elements of the ECS are arranged in a horizontal plane and the heat transfer from the heater to the condenser without EHD pumping is impossible. A pulsating heat carrier flow mode, depending on the heat input and the voltage applied to the pump, takes place at EHD pumping. As the input power is decreasing the frequency of the coolant pulsations as well as the departure diameter and number of vapour bubbles are also decreasing. At some critical heat input the pulsations disappear and the transition from turbulent mode to the laminar one takes place causing the decrease of the heat transfer coefficient. The increase of the pumping flow rate by raising the voltage applied to the EHD pump, results in a partial suppression of boiling. The maximum intensification of heat transfer is reached at pulsation frequency of 1.25 Hz. The maximum heat flow from the heater was 4.2·104 W/m2. Graphical representation and the physical interpretation of the results, which reflect the essence of the process, are given.

Numerical evaluation of thermal performances of diffusion–absorption refrigeration using 1,3-dimethylimidazolylium dimethylphosphate/methanol/helium as working fluid

The thermal performances of diffusion–absorption refrigeration using 1,3-dimethylimidazolylium dimethylphosphate/methanol/helium as working fluid were numerically analyzed. The operating characteristics of bubble pump, boiler, and evaporator were investigated. The variations in the coefficient of performance and exergy efficiencies with different heat inputs of the bubble pump and boiler were simulated and discussed. The thermal performances were compared with those of the butane/nonane/helium and lithium bromide/water/helium systems. The trend of variation in coefficient of performance is accordance to that of the experimental results for butane/nonane/helium system. The optimal coefficient of performance of the proposed system was lower than that of the lithium bromide/water/helium system. But the proposed system possessed the advantages of non-crystallization and non-corrosion, and it could operate at a higher boiler temperature. The exergy losses of each component were calculated and compared with one another. The largest four exergy losses occurred in the condenser, absorber, boiler, and bubble pump, which accounted for approximately two thirds of the total exergy input. The main reason for the exergy loss of the diffusion absorption refrigeration system was the heat transfer with temperature difference.

Optimization of freeze-drying using a Life Cycle Assessment approach: Strawberries’ case study

Drying of foods is a preservation method that aims to prolong the product shelf life and simplify its transport and storage. However, this process requires a large amount of energy, which results in high emissions of contaminants in the environment.In this work, Life Cycle Assessment (LCA) analysis was applied to the drying of strawberries. In particular, for the first time, traditional freeze drying and the combination of osmotic dehydration + freeze drying were analysed and compared to verify if the application of the pre-treatment was effective in reducing the environmental impact, obtaining a more sustainable process.The chosen functional unit was one 450 g dried strawberries’ package. Strawberries were gathered in 2016, from May to September. Primary data related to the drying process were used to perform mass and energy balances and compile the life cycle inventory. The LCA analysis was accomplished using SimaPro 8.0.5 software, in accordance with ISO 14040–14044. The calculations on the traditional freeze drying process were made considering actual operation factory data, whereas the calculations on the osmotic + freeze drying process were desk calculations. The comparison of freeze drying and osmotic dehydration + freeze drying on industrial scale revealed that the traditional process generated higher emissions in terms of all the studied environmental categories. A scenario analysis was, then, carried out to evaluate the potential emissions’ reduction due to the variation of some process times.An improved scenario based on the use of osmotic dehydration + freeze drying with optimised process times was, therefore, proposed; using the improved process, a reduction of the emissions equal to 25% with respect to the traditional freeze drying process could be obtained.Sensitivity analysis showed that variations in fertilisers’ amount and in condenser and vacuum pump power did not cause significant changes to the results. The results also showed moderate sensitivity to strawberries’ transport distance.

The influence of blade configuration on cavitation performance of a condensate pump

The cavitation performance of the centrifugal pump depends significantly on geometrical traits of the impeller blade. An investigation is performed on the centrifugal condensate pump which is featured by operating under cavitation condition. Both experimental and numerical techniques are utilized. Three impeller schemes are devised to improve the cavitation performance. Pump head, cavitation and flow parameter distribution are investigated systematically. Experimental results show that the impeller with five long and five short blades possesses the smallest critical value of net positive suction head at rated flow rate. It is further proved that this impeller maintains the most desirable cavitation performance over the entire flow rate range. Both hydraulic and cavitation performance of the impeller equipped with nine blades of three kinds of length are low relative to the other schemes. Cavities in the pump impeller are produced at the suction side of long blades and approaching the blade inlet, while cavities are absent near the inlet of the short blades. The correlation between pressure distribution and cavitation is manifested at impeller inlet. Long blades contribute to the enhancement of flow uniformity, but the low-pressure area immediately upstream of the blade inlet is enlarged due to narrowed inter-blade area, as is evident in the three pump impellers.

Performance Evaluation of Passive Solar Water Distillation System with Separate Surface Condenser and Vacuum Pump

Although, earth’s two-thirds surface is covered with water and residual is land; all over the world, access to potable water by the people is narrowing and declining. Now a day, pollution created by manmade activities, results in problem of water paucity. Solar energy with eco-friendly and cost effective benefits has become more popular for water purification. A solar still is commonly used device for water purification by distillation process does not require electricity. More investigation is going on to enhance the system performance and efficiency of the solar still and provide a sustainable water purification. There is a need to improve the single slope solar still performance and increase the production of water distillation. Many researchers, engineers and scientists experimentally studied solar water distillation either using condenser or vaccum tubes. So this work is focused on performance of solar water distillation system with combination of surface condenser and vaccum pump. Performance of solar stills having 20 mm water level in the aluminum basin is tested and compared analytically. The experimental study has been carried out to evaluate glass and basin temperature which increases by 2 to 4 0 C with respect to theoretical. Also investigation results show that, the daily distillate output increases up to 43% by coupling surface condenser and vaccum pump due to increase in rate of evaporation and condensation.

Modelling of Plate Heat Exchangers and Their Associated CO 2 Trancritical Power Generation System

Globally, there is no shortage of low-grade waste and renewable heat sources that can be converted into electricity and useful heat using applicable thermodynamic power cycles and appropriate working fluids. As a natural working fluid, CO2 is a promising candidate for application in low-grade power generation systems but require optimised design and evaluation. Since CO2 working fluid has a low critical temperature (31.1̊C) and high critical pressure (73.8 bar), a CO2 low-grade power generation system will most likely undergo supercritical Rankine (T-CO2) cycles. A T-CO2 system normally consists of a CO2 supercritical gas heater, expander, recuperator, condenser and liquid pump with the CO2 gas heater being a crucial component in determining system thermal and exergy efficiencies. In this paper, the models of a thermal oil-CO2 plate gas heater has been developed and validated with measurements of a 5 kWe T-CO2 system test rig. The model is then integrated with other system component models to establish the system model. The system model can be used to evaluate and compare system performances at different operating conditions, including variable CO2 gas heater pressures and heat sink parameters, thereby optimising system operations.

THE EFFECT OF DAMAGE RATE OF TECHNOLOGICAL SUBSYSTEMS EQUIPMENT ON FUNCTIONAL FAILURES OF STEAM TURBINES

The article presents the results of research on the eff ect of damage rate of steam turbine technological subsystems equipment on the operation of a power plant. It was revealed on the basis of analysis of reliability indicators of power units that malfunctions of steam turbine unit (STU) equipment accounted for 25 – 30 % of the total number of failures. The article presents the results of the malfunction analysis for the equipment of various STU technological subsystems operating in the power units and at cross-links power stations and leading to the turbine unit shutdown (failure). It is shown that critical equipment causing turbine unit shutdown in 70 or more percent of cases is represented by the equipment of three technological subsystems: condenser unit, oil supply subsystem and feed water subsystem. Based on the analysis results for operational documentation obtained at the Ural-Siberian region power plants for more than 300 power units with capacity of 200 to 800 MW, the article presents data on the eff ect of equipment failures at various technological subsystems on unplanned shutdowns of steam turbines. It also studies the basic malfunctions of the most critical equipment (that is of condenser, ejector, gland steam heaters, feedwater and condensate pumps, oil coolers, etc.) which can result both in its failure and in turbine unit functional shutdown. Statistical data is presented on the distribution of the causes of damage to condensers, ejectors, feedwater and condensate pumps and oil system equipment. Data presented in the article can be used to develop modules of technical condition monitoring and diagnostics as well as failure preventing measures for steam turbine technological subsystems equipment.

Dry сoolers and air-condensing units (Review)

The analysis of factors affecting the growth of shortage of freshwater is performed. The state and dynamics of the global market of dry coolers used at electric power plants are investigated. Substantial increase in number and maximum capacity of air-cooled condensers, which have been put into operation in the world in recent years, are noted. The key reasons facilitating the choice of developers of the dry coolers, in particular the independence of the location of thermal power plant from water sources, are enumerated. The main steam turbine heat removal schemes using air cooling are considered, their comparison of thermal efficiency is assessed, and the change of three important parameters, such as surface area of heat transfer, condensate pump flow, and pressure losses in the steam exhaust system, are estimated. It is shown that the most effective is the scheme of direct steam condensation in the heat-exchange tubes, but other schemes also have certain advantages. The air-cooling efficiency may be enhanced much more by using an air-cooling hybrid system: a combination of dry and wet cooling. The basic applied constructive solutions are shown: the arrangement of heat-exchange modules and the types of fans. The optimal mounting design of a fully shopassembled cooling system for heat-exchange modules is represented. Different types of heat-exchange tubes ribbing that take into account the operational features of cooling systems are shown. Heat transfer coefficients of the plants from different manufacturers are compared, and the main reasons for its decline are named. When using evaporative air cooling, it is possible to improve the efficiency of air-cooling units. The factors affecting the faultless performance of dry coolers (DC) and air-condensing units (ACU) and the ways of their elimination are described. A high velocity wind forcing reduces the efficiency of cooling systems and creates preconditions for the development of wind-driven devices. It is noted that global trends have a significant influence on the application of dry coolers in Russia, in view of the fact that some TPP have a surface condensers arrangement. The reasons that these systems are currently less efficient than the direct steam condensation in an air-cooled condenser are explained. It is shown that, in some cases, it is more reasonable to use mixing-type condensers in combination with a dry cooler. Measures for a full import substitution of steam exhaust heat removal systems are mentioned.

MATLAB/Simulink를 이용한 화력발전소 복수펌프 순환기동로직 시뮬레이션 구현

기존 국내 외 연구를 통해 개발된 펌프 운전 시뮬레이터는 대부분 동역학적 해석을 목적으로 하거나 운전자 교육용을 목적으로 개발되어 왔다. 그런데 기존 시뮬레이터는 운전자 위주로 구성되어 있어서 로직 설계자나 시운전 참여자들이 다양한 운전조건 또는 로직을 임의로 변경하기에는 적절하지 않다. 더욱이 최근 발전소에서 사용되는 두 개 이상의 복수펌프 운전에 대해 설계자나 운전자가 쉽게 활용할 수 있는 시뮬레이터는 개발되어 있지 않다. 그래서 본 논문에서는 MATLAB Simulink를 사용하여 일반적인 화력발전소에 주로 사용되는 복수펌프 3대에 대한 순환운전 로직에 대해 설계자나 운전원이 쉽게 사용할 수 있도록 시뮬레이션을 할 수 있는 방법을 제안 한다. 이 제안은 MATLAB을 사용할 수 있는 사용자가 발전소 DCS(Distributed Control System) 로직에 주로 사용되는 ANSI/ISA S5.2를 Simulink를 통해 구현할 수 있도록 도움을 준다. 또한 코드에 명시된 로직을 구현하기 위해 블록에 대한 Sub-System을 만들고 이를 시뮬레이터 내에서 적용이 가능한지를 검증한다. 제안된 방법을 이용한 실무 검증 단계에서는 로직 내에서 발생한 기동신호를 구현된 펌프 모델에 적용하여 3대 펌프 순환운전 시 발생할 수 있는 모든 오류 가능성을 제안된 시뮬레이터를 사용하여 설계 단계 및 운전 전에 검증할 수 있음을 실험을 통해 확인하였다. The simulators for pump operation developed by domestic or overseas research have been developed for dynamic analysis or operator training purposes. However, previous developed simulators focused on the operators so they are unsuitable for logic designers or commissioning engineers who need to change the operation conditions or logics arbitrarily. In addition, the simulator for two or more condensate pumps' operation, which can be used easily by plant designers or operators, has not been developed. Accordingly, this paper suggests a simulation method that can be used easily for plant designers or operators using MATLAB Simulink. This suggestion helps users who can use MATLAB to implement ANSI/ISA S5.2, which is applied mainly for DCS (Distributed Control System). In addition, to implement the logics specified in the CODE, Sub-Systems were created for the block and evaluated to determine if they can be used in the simulator. In the working level stage using the suggested method, all error possibilities that might occur during the three pumps' rotation operation could be verified with the suggested simulator during the design stage or before operation.

Economic Analysis of Wet Flue Gas Desulfurization System with the Application of Low Pressure Economizer for Waste Heat Recovery

The data of wet flue gas desulfurization (WFGD) power and water consumption, from two different coal-fired power plants (100 MW and 1000 MW) under full load operation, are studied for the WFGD economic analysis of waste-heat-recovery transformation with the installation of low pressure economizer (LPE). The results of 100MW unit show that, WFGD inlet flue gas temperature drops from 155°C to 110°C, the benefits generated include power consumption of fans declines by 23.85% and water consumption of the smoke desulfurization absorption tower declines by 34.88%. In another case, the temperature of inlet flue gas from WFGD of 1000 MW unit drops from 130°C to 84°C, power consumption of fans increases by 15.04% while water consumption of the smoke desulfurization absorption tower declines by 73.1%. Besides, the flow resistance is increased in LPE water side due to the installation of LPE. This makes power consumption of condensate pump enhanced, which slightly decreases the benefits from waste heat recovery.

An integrated method for human error probability assessment during the maintenance of offshore facilities

The paper presents a novel approach for Human Error Probability (HEP) assessment by integrating the Success Likelihood Index Method (SLIM) with the Technique of Human Error Rate Prediction (THERP). In this approach, the SLIM has been embedded within the THERP framework to generate the nominal HEP data when it is unavailable. The developed methodology is implemented to an offshore condensate pump maintenance task. In the first step of this study, the human error was estimated considering all the standard tools and procedures which are in place. In the second step, as an additional measures, radio frequency identification (RFID) based tools are utilized and HEP is recalculated. Without the application of RFID tools, the HEP value is found to be 5.7244×1022 or estimated as 5.72% with an uncertainty bound of 1.1448×10−2–1.1452×10−1. With RFID tools, it is reduced to 4.6342×10−2 or 4.63%, with an uncertainty bound of 2.145×10−2–2.089×10−1 which yields a net HEP reduction of 1.09%.

A modified mathematical model of heat pump's condenser for analytical optimization

The aim of this article is to present the reason and the process of creating new modified mathematical model of heat pump plate condenser. The fundamental mathematical model is modified according to analytical optimization procedure. The adaptation is carried out by applying the procedure of elimination. The modified mathematical model include 2 governing equations instead of 6. The two governing equations contain 2 unknown dependent variables and 6 known parameters. The modified mathematical model is validated using the comparative method. The compared data are obtained by numerical simulation using fundamental and modified mathematical models. Applying both models the obtained data fully coincided. By using the new modified mathematical model and implementing the optimization process may lead to the determination of the maximum energy efficiency of hot water subsystem. The subsystem comprises a condenser, a circulation pump, a connecting pipeline and the heating units. The objective function in the optimization process is the coefficient of performance, COP, as a function of the mass flow rate of the hot water or of the circulation pump power. The paper offers the implementation of modeling the circulation pump power to achieve the maximum value of the COP.

220 MW机组凝结水泵出力不足改造

凝结水泵是电厂中的重要辅助设备，保证其正常出力，对机组的稳定运行十分重要。针对某电厂220MW机组凝结水泵在调试阶段几次启动时出力数据进行了讨论，确定1号机组凝结水泵出力不足，在所采集实时运行数据的基础上，结合原设计参数及现场情况，对该电厂凝结水泵出力不足问题进行了改造，消除了凝结水泵出力不足的设备缺陷，提高了凝结水泵运行的安全性和经济性。 Condensate pump is an important auxiliary equipment of power plant; it is important to the stable running of the units. The paper discussed the condensate pumps running date during the integral startup of 220 MW unit; the running date showed the condensate pumps unit output was insuffi-cient of NO. 1. Based on the real-time data collected from power plants, design data and situation of the site, we retrofit the system for the condensation water pumps output insufficient, eliminate the shortage of equipments and improve the security and economy in condensate pump operation.

Improved Design of a 25 MW Gas Turbine Plant Using Combined Cycle Application

This paper presents the improved design of a 25 MW gas turbine power plant at Omoku in the Niger Delta area of Nigeria, using combined cycle application. It entails retrofitting a steam bottoming plant to the existing 25 MW gas turbine plant by incorporating a heat recovery steam generator. The focus is to improve performance as well as reduction in total emission to the environment. Direct data collection was performed from the HMI monitoring screen, log books and manufacturer’s manual. Employing the application of MATLAB, the thermodynamics equations were modeled and appropriate parameters of the various components of the steam turbine power plant were determined. The results show that the combined cycle system had a total power output of 37.9 MW, made up of 25.0 MW from the gas turbine power plant and 12.9 MW (an increase of about 51%) from the steam turbine plant, having an HRSG, condenser and feed pump capacities of 42.46 MW, 29.61 MW and 1.76 MW respectively. The condenser cooling water parameters include a mass flow of 1180.42 kg/s, inlet and outlet temperatures of 29.8°C and 35.8°C respectively. The cycle efficiency of the dry mode gas turbine was 26.6% whereas, after modification, the combined cycle power plant overall efficiency is 48.8% (about 84% increases). Hence, SIEMENS steam turbine product of MODEL: SST-150 was recommended as the steam bottoming plant. Also the work reveals that a heat flow of about 42.46 MW which was otherwise being wasted in the exhaust gas of the 25 MW gas turbine power plant could be converted to 12.9 MW of electric power, thus reducing the total emission to the environment.

Integration of cryopump instrumentation for SST-1 NBI

A positive ion neutral injector (PINI) capable in delivering 5MW (55kV, 90A) ion beam power is being operated for SST-1 neutral beam injection (NBI). The production and neutralization of the ion beams in the injector require a gas throughput of 20 torr I/s in the plasma box and 50–100 torr I/s in the neutralizer section. It is necessary to maintain operating pressure of vessel at 10−5 torr to reduce the re-ionization loss of beam within tolerable limits. Conventional Turbo molecular pumps cannot maintain this vacuum level at required gas feed rate so two cryo condensation pumps are being operated to achieve require vacuum in vessel. In order to monitor and optimize the performance of cryopumps, it is necessary to measure the temperature at various locations in LN2 and LHe path. It is also required to monitor the level of LHe and LN2 in cryopumps. Several temperature and level sensors are mounted at various places in cryopumps and integrated with PLC and SCADA based control system.

Problems and Diagnosis of Condensate Polishing System in Ultra-Supercritical Power Plant

Aiming at dealing with the problems of design, debug, and operation that occurred in the condensate polishing system, the paper put forward the problems of the high concentration of oxygen at the outlet of the condensate pump, pollution of the prefilter, the presence of remaining resin in the upper water cap of the high speed mixed bed, condenser leakage and abnormal shutdown of the turbine through the data analysis of condensate polishing system in Taishan Power Plant, diagnostic analysis of all these problems was performed and appropriate solutions were put forward.

Analysis on Fracture Causes of Condensate Water Pump Shaft

Failure causes on a condensate pump shaft were discussed by means of macroscopic observation, chemical composition analysis, metallurgical microstructure inspection, mechanical property tests and stress analysis. The experimental results showed that the improper material with disqualified chemical composition, improper microstructure and poor mechanical properties acted as inherent factor. In addition, structure design that led to stress concentration contributed to the failure as external factor. Finally, fatigue fracture happened at the reduce section of the pump shaft.

Failure Investigation of Condensate Pump Shaft

The premature failure of condensate pump shaft was investigated in this paper. The shaft was attached with feed water condensate pump system in thermal power plant boiler. The shaft was fabricated from martensitic stainless steel. A detailed study was carried out to determine the root cause of the shaft failures. Visual examination, macroanalysis, chemical analysis, microstructural characterization, and fractography examinations were also carried out to ascertain the probable cause of shaft failure. Finally, it was concluded that the failure of the shaft was due to the torsional fatigue initiated by the cracks at the thread roots.