Main Condenser Research Articles

The influence of supercooling of the main condensate at the outlet of the condenser on the operation of a cogeneration steam turbine plant

The article considers the issue of the influence of supercooling of the main condensate on the performance of a steam power plant. We describe the calculation method for a steam turbine condenser. Based on the mathematical model of a condenser, we propose a method for calculating supercooling degree of the condensate on its bottom with different air inflows in a turbo unit vacuum system. The degree of the condensate supercooling on the condenser bottom during the operation of the turbine unit in the heat and electricity production mode is determined in the example of the T-110/120-130 UTZ turbine unit. It is shown that an increase of air inflow into the vacuum system by four times leads to an increase in supercooling of the condensate from 3.5 to 11°C. It has been established that an increase in the condensate supercooling leads to additional heat losses of up to 1.100 kW in the turbine unit per a cycle in the power production operating mode and up to 500 kW per a cycle in the heat production mode.

Multi-parameter Joint Optimization Based on Steam Turbine Thermal System Characteristic Reconstruction Model

Steam turbine thermal system characteristic reconstruction model for multi-parameter joint optimization is proposed in this paper. This paper has two main improvements. First, a steam turbine thermal system characteristic reconstruction model is conducted, which includes turbine, condenser and heater. There are three iterative nested algorithms in this model. In the innermost layer, avariable condition calculation model of condenser is nested, and the exhaust flow and exhaust steam pressure can be calculated. In the outermost layer, the power equation is applied as the iteration ends. In this model, simulation of thermal system of steam turbine three kinds of disturbing factors demand can be realized well and the joint optimization of thermal system of steam turbine flow section and the cold end can be realized. Through calculation and comparison, the model constructed in this paper is proved to have high accuracy, and the calculation process is stable and convergent. At the same time, the joint optimization method involving turbine main steam pressure and exhaust pressure is proposed here. In this method, heat consumption rate is the optimization objective, with steam turbine thermal system characteristic reconstruction model, the optimal main steam condenser and vacuum pressure were obtained. The result of A 600MW condensing unit showed that the method could be synchronized to determine the optimal combination of circulating pump, the best vacuum and sliding pressure curve of main steam under different load and different ambient temperature. Comparison results also showed that the joint optimization solution of main steam pressure and exhaust pressure is superior to optimized solution main steam pressure individually.

Optimal design for cryogenic structured packing column using particle swarm optimization algorithm

Large scale cryogenic air separation is the most efficient and cost-effective approach to produce high-purity air products by present. Structured packing columns (SPC) are widely focused and applied due to their characteristics of high efficiency and energy saving in the cryogenic distillation process. The optimal design of the SPC is to reduce the energy consumption and initial investment, while it is a highly nonlinear and multivariable problem. The coexistence of real variables and integer variables, such as the flow rates and the positions of materials at the inlets/outlets, makes the optimization become a typical mixed integer nonlinear programming (MINLP) problem. The purpose of this paper is to study the optimal design method for the cryogenic SPC using the particle swarm optimization (PSO) algorithm. A modified PSO for handling the MINLP problem (MI-PSO) is proposed. A multi-objective optimal design for the SPC in cryogenic air separation plant with the capacity of 17,000 Nm3/h is investigated as a instance. By MI-PSO algorithm, the total exergy loss theoretically reduces 36.3% and the main condenser heat load decreases 5.4% after optimization, which can provide test prediction for the cryogenic distillation experiment.

Simulation of 25 MWe Steam Power Plants Using Gate Cycle

Power plants using steam are a very popular system today. To develop a construction of power plant system requires an accurate analysis in determining operating parameters as expected. Designing with manual calculations certainly requires a very long time. One of faster method use a thermodynamic simulation system such as a Gate Cycle. The goal of this research was to simulate a steam power plant to produce 25 MW net electric power and to investigate the effect of an increasing of main steam temperature, main steam pressure and condenser pressure on electrical power and thermal efficiency. The simulation was done using the main input data of simulation were tempe rature of 535 0C, pressure of 89 bar, condenser pressure of 0.084 bar and heating value of low rank coal of 3800 kcal/kg. The main steam temperature was varied of 515; 535; 555 and 575 0C. The main steam pressure was varied of 79; 89; 99 and 120 bar, The condenser pressure was varied at 0.064; 0.074; 0.084 and 0.094 bar. The simulation results showed the net electric power produced of 25.8 MW on the main input data. An increasing of the main steam temperature and the main steam pressure would increase the net electrical power and the thermal efficiency but an increasing of condenser pressure would decrease the net electrical power and the thermal efficiency

Application and limits of a constant effectiveness model for predicting the pressure of steam condensers at off-design loads and cooling fluid temperatures

The main steam condenser is an essential part of every steam power plant. It governs the exhaust pressure of the low pressure turbines and defines the minimum cycle temperature. The heat that is extracted from the cycle steam by the condenser is transferred to a cold stream such as air or water and discarded to atmosphere using a cooling device. The effectiveness of the condenser is key in determining steam temperature, and hence the turbine back pressure response at various operating conditions. Several methods have been proposed in literature to predict the change in backpressure due to load changes. This work examines the validity of a constant condenser effectiveness assumption method, for predicting the back pressure response at various loads, and/or for different cooling inlet temperature conditions. It also shows how the effectiveness of a condenser can be evaluated without detailed knowledge of the condenser internal design. The results of the model were validated against data from 2 Air Cooled Condensers and 1 Wet Cooled Condenser. The results indicate that the constant effectiveness assumption is valid for all heat load conditions, and for cooling inlet temperatures within a close range to the design cooling fluid inlet temperature. To further improve on the accuracy, a simple linear adjustment can be added if one extra low load condition is known, resulting in pressure prediction errors below 4% for the full operating range.

Power regeneration upgrading of vapour compression refrigeration plants

Power Regeneration Technique in Vapour Compression Refrigeration Plants is presented for the purpose of upgrading already existing plants, each characterized by Main Compressor, Evaporator, Condenser and Main Expansion Valve.The Power Regeneration Concept is illustrated and theoretical results deeply discussed in relation to the upgrading of Refrigeration Plants whose Cooling Power being given or whose Main Compressor remain unchanged. Changes in performance and internal variables are deeply analysed for various arrangement options. Experimental results are also given providing the performance improvement of the Refrigeration Plants equipped with Power Regeneration Systems. Cooling Power and COP improvements up to 100% and 80% respectively are expected for a given Main Screw Compressor; while COP increasing up to 70% and Main Compressor Delivery reduced to 50% are evidenced for constant Cooling Power Plants.

Make-up Water Heating Capability, Conditions, and Efficiency in Built in Bundles when Cooling Water Is Concurrently Piped through the Main Condenser Bundles

The paper considers the make-up water heating capability and conditions in the built-in tube bundles when cooling water is concurrently piped through the main turbine condenser bundles. Based on the analysis of experimental and calculated data, a technique is proposed for estimating heat fluxes entering the condenser when the turbine plant operates in the heat production mode. It is shown that, for efficient operation of the built-in bundle as part of the condensing system, all heat fluxes coming in addition to the wheelspace should be directed into the regenerative heating zone under the built-in condenser bundles through special water distribution devices, and the inlet zone itself should be separated from the condenser chamber by enclosing shields. The calculation studies were carried out using a mathematical condenser model of a cogeneration steam turbine plant with built-in condenser bundles. The studies were performed on the model of a turbine plant T-50-12.8 for three seal levels of the low-pressure sliding grid and different make-up water flows and temperatures. The conducted researches made it possible to determine the heat distribution in the condenser between the condenser bundles in different turbine operating modes and to reveal the absence of pressure constraints in the condenser and make-up water temperature constraints at the outlet of the built-in bundle. Based on the turbine plant T-50-12.8 mathematical model, thermal efficiency calculations were performed using the built-in make-up water condenser bundles when the main bundles operate in the cooling mode. It is shown that the heat economy of the turbine plant operating in the considered regimes in the heat production mode with the make-up water flows close to the nominal make up 70% and more of the condenser heat load.

Experimental study on the condensation characteristics of nitrogen with non-condensable gas

The non-condensable gas at the top of the main condenser of the distillation section, such as helium or neon, would lower the heat transfer efficiency and the productivity of the air separation plant. Current research mainly focuses on the study of the water vapor condensation mechanism with non-condensable gases, while those on cryogenic fluids are rare. In this work, an experimental setup was designed to study the condensation mechanism of pure nitrogen vapor and nitrogen vapor mixed with helium on the vertical plate. The experimental data of pure nitrogen vapor is in good agreement with the results calculated by the classical Nusselt model, which demonstrates that the experimental system has high reliability. The influences of the mass fraction of helium and system pressure on the condensation heat transfer coefficient are analyzed. Results show that even a very low mass fraction of helium can cause the condensation heat transfer coefficient of nitrogen vapor to decrease obviously. The deviation between the heat transfer coefficient of the nitrogen-helium mixture and pure nitrogen increases with the increases of the helium mass fraction and the decrease of system pressure. A new condensation heat transfer correlation for nitrogen with helium is developed that the deviations of most of its predictions are within 20% compared to the experimental data.

Study on Dynamics of Steam Dump System in Scram Condition of Nuclear Power Plant

Abstract During the scram or load rejection of nuclear power plant, the excess steam of steam generator needs to be dumped to the main condenser through the steam conditioning device to reduce the temperature rising of the primary loop and prevent the steam generator from over-pressure. For study of the dynamics and control strategy of the steam dump system, this paper established a simulation model of nuclear power plant using Gsuite simulation platform, and then studied the dynamical-varying of some important-variables in nuclear power plants during scram. The results indicated that the model built can approximately predict the dynamic changes of important parameters such as the average temperature of the primary loop and the main steam pressure. Therefrom it is concluded that the joint operation of the steam dump system and atmospheric steam dump system can effectively prevent the rising of the temperature of the primary loop and the overpressure of the secondary circuit, and thus it can avoid the opening of the main-steam safety valve.

On the feasibility and possibility of heating water for district heating systems through the use of heat of the main condensate after cogeneration turbines

The possibilities of increasing the efficiency of cogeneration turbines of CHP plants through the use of low-potential heat carriers for water heating in district heat supply systems and increasing the generation of CHP electricity are considered. The existing technologies of heating the makeup water of the district heating system upstream water treatment apparatuses do not always provide the required heating temperature and do not have the sufficient energy efficiency. The technologies of using the main condensate of the exhaust steam in the turbine to heat the feed water in additional heaters included in the system of regeneration of cogeneration turbines are developed. The use of these technologies contributes to increasing the flow rate and reducing the enthalpy of the steam of regenerative outlets of the turbine used to heat this condensate, and, therefore, increases the combined heat and power generation. In order to determine the industrial applicability of the proposed solutions, experimental studies of the regeneration systems of turbo-units under the conditions of Ulyanovsk СHPPs-1 have been carried out. Multiparameter data arrays on operation of turbine condensate-feed path have been collected, and regression equations have been obtained to calculate the main condensate flow temperatures depending on various factors. On the basis of experimental data there have been calculated the minimum and maximum flow rates of feed water that can be heated to the desired temperature in the surface heaters included in the regeneration system of the turbines, the flow graphs of the heated feed water are constructed depending on the temperature of the main condensate after the turbines. The fields of application of the proposed technological solutions in operating heat supply systems are defined. The evaluation of energy efficiency is carried out using the method of specific generation of CHP electricity and conventional fuel economy at the implementation of the proposed solutions is calculated.

Experimental investigation of steam condensation in water tank at sub-atmospheric pressure

Abstract The International Thermonuclear Experimental Reactor (ITER) Vacuum Vessel Pressure Suppression System (VVPSS) limits the Vacuum Vessel (VV) internal pressure, in case of loss of coolant (LOCA) or other pressurizing accidents from the in-vessel components, to 150 kPa (abs). This is key safety function because a large internal pressure could lead to a breach of the primary confinement barrier. Safety is ensured by discharging the steam evolved during the accident event to the VVPSS suppression tanks where it is condensed. Steam condensation occurs at sub-atmospheric pressure condition. Moreover, being this latter not standard for traditional nuclear systems, this investigation is quite new (not studied in detail before) and deals with an experimental investigation of the direct contact condensation at VVPSS prototypical thermal-hydraulic conditions. To the purpose, a small-scale experimental rig was properly designed and built at Lab. B. Guerrini of DICI-University of Pisa as well as different temperature, pressure and steam mass (flow rate per hole) conditions and sparger patterns have been investigated. The experimental test matrix is also presented in this study. The obtained results show high efficiency of condensation for all examined conditions. The main condensation regimes at sub-atmospheric pressure conditions were identified. In addition, a comparison was done between the condensation regimes experimentally determined and those available in the literature, which were obtained at atmospheric pressure. Finally, results demonstrated to be representative of the real configuration at ITER reactor.

Experimental Study on a Low-Temperature Heat Pump Sludge Drying System

The low-temperature sludge drying has become a kind of emerging hot drying technology. A small low-temperature heat pump sludge drying system is constructed in this paper. System operation characteristics are experimental studied. The results demonstrate that the set of an auxiliary fan is helpful to the system stable operation, but also leads temperature fluctuation of the main and auxiliary condenser. The inlet temperature and humidity of moist air in the drying closet and evaporator presents the opposite vibrate trend. The moisture contents in the above two devices both show a trend of increasing first and then decreasing, but the fluctuation range in drying closet is bigger. The wind resistances of the drying box and evaporator, which account for more than 90% of the whole system, both shows a certain extent fluctuation. The average specific power consumption of the system is 0.97 kWh/kg.

Conjugate heat and mass transfer study of a new open-cycle absorption heat pump applied to total heat recovery of flue gas

Industrial exhaust flue gas contains massive heat and water. Effective recovery will make positive sense for energy saving and conservation. Traditional condensing heat exchanger is restricted by coolant water temperature and corrosion problem. This paper proposes a new open absorption heat pump (OAHP). The system works on the basis of directly contacting spray heat and mass transfer occurring in three main parts, including generator, condenser and absorber. Driven by high-temperature flue gas directly from a burner, the system generates strongly concentrated LiBr solution prepared for the absorption of moisture and heat from the objective flue gas. A detailed theoretical model is established in Eulerian-Lagrangian formulation to simulate the particle dynamics and the heat and mass transfer characteristics. Extraordinary temperature profiles different from those in common heat transfer are found in the generator and are explained by the conjugate heat and mass transfer. The effects of the driving flue gas temperature and the return water temperature on system performances are studied. The OAHP system achieves excellent heat recovery capacity even at high return water temperature, indicating superiority to the condensing heat exchanger.

Analysis of the pyrolysis products from spent bleaching clay

Malaysia annually generated about 177,000 tonnes of spent bleaching clay (SBC) at 1% clay dosage added which nearly 50,000 tonnes of adsorbed oil was recovered at 28% oil retention. This oil-laden SBC is currently under-utilized as it is dumped in landfills without any attempt to recover the oil. A total of 26.57 wt% of residual palm oil in spent bleaching clay was pyrolyzed using tubular furnace. The pyrolytic oil products analyzed by GC-MS showed aliphatic hydrocarbon ranging from C9-C18 in the main condenser and C16-C44 in the NaCl saturated solution extract. Carboxylic acids and alkanes were the major classes of compounds found in the main condenser and NaCl extract. Significant amounts of monoaromatic compounds, alkenes, alcohols, ketones, aldehydes, esters, nitrogenated compounds, and polycyclic aromatic hydrocarbons (PAHs) were found in this study. The bio-oil resulting from the pyrolysis process gives n-hexadecanoic acid as the major compound

Simulation and energy integration of distillation tower of a naphtha treatment unit

Energy optimization is of vital importance especially in oil, gas and petrochemical industries. Distillation column with high energy consumption is one of the most common equipment in the aforementioned industries. Thus, it is important to revise the projection of initial process, reduce energy consumption and recover some of used energy. In this work, we studied energy optimization of a naphtha treating unit in a petrochemical company using Aspen HYSYS software. For energy optimization, feed temperature was changed to a satisfactory temperature (47 °C) for condensation of overhead steam distillation. Feed was used as a cooling fluid in the heat exchanger before the main condenser. According to outcome, 644.11 MW of energy was recovered and approximately 53% less energy was used in the air conditioner. Feed was injected in tower with higher temperature (212 °C) because of preheating. This reduces consumed energy up to approximately 63% by reducing the entering flow rate of reboiler.

Evaluation of impacts of cooling tower design properties on the near-field environment

In a nuclear power plant, ultimate heat sink (UHS) and circulating water system (CWS) cooling towers both ultimately remove heat from the essential service water system, main condenser, and non-essential service water system during all operation modes including accident conditions. Since the visible plume from the cooling tower has an adverse effect on the environment, however, an environmental impact assessment of the cooling tower is required for the construction of a new nuclear power plant. In this study, the environmental impact of UHS and CWS cooling towers of an APR1400 standard design plant was assessed for the purpose of testing and demonstrating the recently-updated SACTI2 model. Because the site for the APR1400 standard design plant had not been decided, one-year meteorological data from the Spokane International Airport weather station, WA, USA, were used as hypothetical input data for the environmental impact assessment. The quantitative effect of cooling tower design changes on the environment was analyzed in terms of index-value dispersion area (AD) and dispersion ratio (δ) for nine environmental assessment indexes. Scenario test conditions were varied by changing cooling tower arrangement, distance between cooling towers, length of cooling tower, exit port height, exit port diameter, the number of exit ports, heat load per tower, and air flow rate per tower.

Generalized pinch point design method of subcritical-supercritical organic Rankine cycle for maximum heat recovery

Novel methodology for pinch point design and optimization of subcritical and supercritical organic Rankine cycles is proposed for maximum heat recovery. The proposed method is able to predict pinch point locations in both evaporator and condenser simultaneously. As a main advantage, both evaporator and condenser pressures can be optimized simultaneously by optimizing only working fluid mass flow rate to get maximum net work output or heat recovery efficiency for given heating fluid and cooling fluid inlet conditions using selected working fluids. Working fluids have been selected based on thermodynamic and environmental criteria and compared based on various performance parameters (net work output, thermal efficiency, heat recovery efficiency, irreversibility, exergetic efficiency, turbine size parameter and heat transfer requirement). The present method seems to be better than previous pinch point design methods as it optimize the cycle by considering both source and sink. At optimum operation, ammonia is best in terms of lower mass flow rate requirement, higher exergetic efficiency, lower turbine staging and turbine size, whereas, isopentane is best in terms of higher power output and heat recovery efficiency. Novel contour plots are presented as well to select optimum ORC design parameters for available heat source and sink.

Chemistry of impact events on Mercury

Based on the equilibrium thermochemical approach and quenching theory, formation of molecules and dust grains in impact-produced clouds formed after collisions between meteoroids and Mercury is considered. Based on observations of Al, Fe, and Mn atoms in the exosphere of Mercury and new results of studies of the elemental composition of the surface of Mercury, quenching temperatures and pressures of main chemical reactions and condensation of dust particles were estimated. The behavior of the main Na-, K-, Ca-, Fe-, Al-, Mn-, Mg-, Si-, Ti, Ni-, Cr-, Co, Zn-, O-, H-, S-, C-, Cl-, N-, and P-containing species delivered to the Hermean exosphere during meteoroid impacts was studied. The importance of meteoroid bombardment as a source of Na, K, Ca, Fe, Al, Mn, Mg, and O atoms in the exosphere of Mercury is discussed.

Optimization of operating temperatures in the gas operated single to triple effect vapour absorption refrigeration cycles

Thermodynamic analysis of LiBr–H2O single, double and triple effect vapour absorption cycles has been carried out using LPG and CNG as sources of energy. Optimization of operating temperatures in single to triple effect cycles has been carried out for maximum COP of the system and minimum gas requirement in it at desired temperatures in evaporator, absorber and main condenser using iterative technique. In single effect cycle, optimum temperatures in main generator have been obtained, while in double effect cycle, low pressure generator, high pressure condenser and main generator temperatures have been optimized. In triple effect cycle having three condensers and three generators, condenser temperatures (Tc3 and Tc4) and generator temperatures (Tg2, Tg3 and Tg) have been optimized. The maximum COP of triple effect cycle goes up to 1.955 which is around 132% higher than single effect cycle with its gas requirement reduced to around 122% at the same conditions.

Mechanisms of pressure oscillation in steam jet condensation in water flow in a vertical pipe

Pressure oscillation associated with direct contact condensation of steam jet in water pipe flow is of high significance for industrial processes. In this paper, experimental study is conducted to reveal the mechanisms of the pressure oscillation in steam jet condensation in water flow in a vertical pipe. The interfacial characteristics of the jet plume are acquired by high speed camera, and the pressure oscillation due to condensing jet are captured by using high frequency pressure transducers. Four main types, including Chugging, Oscil-I, Oscil-II and Stable condensation regimes, are identified visually based on the interfacial behavior of the jet plume, and their distribution is described in a three-dimensional condensation regime diagram based on steam mass flux, water temperature, and Reynolds number of water flow. In the Chugging regime, the high-amplitude pressure oscillation appears at low frequency, and the unimodal PDF demonstrates that the pressure oscillation is only dominated by steam mass flux. In the Oscil-I regime, the pressure oscillation is approximately sinusoidal and its intensity is the highest among the four condensation regimes, whereas the intensity of the pressure oscillation remains at a low level and varies little in the Stable regime. In both the Oscil-I and Stable regimes, with increase of water temperature and Reynolds number of water, the unimodal PDF spreads out over a wider range, and finally the bimodal and symmetrical PDF appears for the Oscil-I regime. The statistical analysis shows that both the deviation and maximum of pressure signals could identify the four condensation regimes well, while both the skewness and kurtosis of pressure signals could easily distinguish the Chugging and Oscil-II regimes.