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This paper proposes the design of a PI $^{\alpha }$ robust controller with which to regulate the steam pressure in the steam drum of a bagasse-fired boiler. The dynamic behavior of this process was identified by means of experimentation. This identification procedure yielded an equivalent third order plus time delay model, and showed wide process static gain variations. We, therefore, propose a new method with which to design fractional-order robust controllers for this kind of processes. This method is based on the exact attainment of certain nominal time specifications while using one of the parameters of the controller to maximize the gain margin. The controllers attained were shown to significantly outperform the robustness achieved by using PI or PID controllers, in the sense of reducing the Integral Absolute Error ( IAE ) and improving the steam pressure uniformity.

A control system with uncertainty or unpredictable disturbance needs more effort to be controlled. A conventional PID Controller is the most popular method used in industries. It was tuned and adjusted by the designer, and it has fixed parameters during operation. However, the disturbance effect causes the desired system performance unreachable. By using a self-tuning controller, the problem should be tackled. In this paper, the PID-Genetic Algorithm (PID-GA) controller was proposed and tested with the steam drum water level control system of a steam power plant. Variation in power load causes noisy water level characteristics and should be maintained at + 0.4 meters from the setpoint to prevent the power plant trip. From the simulation, PID-GA can reduce disturbance of the minimum, nominal, and maximum load with perturbation peaks 0.18 m, 0.22 m, and 0.26 m respectively.Keywords: genetic algorithm, NWL, PID-GA, steam drum, steam power plant.

Startup system, the design of startup sequences analysis is an important part of SCWR design. A thermal hydraulic system analysis code for supercritical water reactor named SCTRAN is used to model the entire startup system based on the circulation loop for startup and once-through direct cycle. The problem of the heat transfer coefficient (HTC) does not accurately capture deterioration phenomenon, the HTC is calculated as a discontinuity in the mode transfer region, its low prediction accuracy above the quasi-critical region have been solved by the new wall heat transfer model. Especially, the look-up table would not be used to obtain the HTC and achieves high prediction accuracy across the critical region, unless the pressure is higher than 19 MPa. After that, to get a smooth recirculation variable pressure startup process, the system model integrates the control system which can controls the temperature, the steam drum water level, the thermal power, and the coolant flow rate. Based on the CSR1000 core and entire once-through direct cycle and circulation loop for startup, four stages under control systems, from low pressure to full power condition in recirculation startup process, were analyzed with code SCTRAN and wall heat transfer model was modified. The calculation results show that the recirculation system can startup from subcritical state to full power state without issue of CHF. The control system can control the parameters quite well and maximum cladding temperature (MCST) can be limited under 650 °C in the startup process. The modified SCTRAN code in this paper can further expand the computational range and computational accuracy. The full-scale control system can meet the needs of parameters expected response.

The drum water level is a very important operating parameter of a drum boiler, and it is also a sign of whether the boiler steam system is balanced. Maintaining the water level of the steam drum within a certain allowable range is a necessary condition to ensure the safe operation of boilers and steam turbines. Excessive water levels will affect the normal operation of the steam separator, and the steam quality will deteriorate. When the superheater tube wall and the steam turbine blade become fouled seriously, it will cause the steam to carry water and cause the steam turbine water impact to damage the equipment. If the water level is too low, the water circulation will be destroyed, and in severe cases, the water wall pipe will be deformed and burst. Therefore, the water level control of the steam drum has always received great attention. For the control of the water level of the steam drum, the motivation is to adapt the boiler water supply to the boiler's evaporation capacity, maintain the steam drum water level within the specified range, and at the same time maintain a stable water supply flow.

In this study, a coal-fired industrial type boiler's performance and emission tests were performed using the energy balance method. During the experiments, the directives in the test standard (ASME PTC - 4) were followed. This tested boiler has a capacity of 75 t/h and is used in the mining industry. This boiler is a steam drum boiler equipped with an atmospheric circulating fluidized bed furnace. The furnace chamber with a rectangular cross-section has its width of 4250 mm and a depth of 4100 mm. In order to minimize the height of the furnace chamber and whole boiler, the middle wing walls are built-in the furnace chamber. As a result of the performance test, the boiler efficiency (indirect method) was found to be 93.07% (base on the lower heating value of fuel). According to the indirect method, the first three significant losses in total boiler losses were, respectively; the conversion of H2 in the fuel to water after combustion by 4.036%, the loss of dry flue gas by 3.231%, and the proportion of unburned carbon in residual products at the end of combustion with 1.653%. Due to the fluidized bed boiler's structural characteristics, it was also shown in the test results that emissions were suppressed in the combustion chamber, which was kept in the temperature range of 850-950 °C. © 2021 The Author(s).

The min/max state of charge (SoC) thresholds of battery storage (BS), which challenge the economics of frequency regulation (FR), have a certain degree of uncertainty and need to be artificially re-calibrated after a period of operation time. To tackle this challenge, a SoC threshold optimization method is proposed for joint FR by thermal power (TP) and battery storage (BS) by comprehensively considering the automatic generation control (AGC) fatigue loss cost of TP and the aging degradation cost of BS. The proposed method consists of three parts: 1) the AGC fatigue loss cost of TP is computed by considering motion loss cost (e.g., steam turbine rotor, oil servo-motor, steam gate valve stem) and static loss cost (e.g., steam drum, cylinder); 2) the aging degradation cost of BS is formulated by considering also the uncertainty of SoC; 3) the min/max SoC operation thresholds of BS are optimized through the surrogate Lagrangian relaxation (SLR) method by comprehensive considering of the AGC fatigue loss and aging degradation cost of FR. Results of extensive simulation tests have clarified and verified the economic effectiveness of proposed min/max SoC threshold optimization method for the joint frequency regulation by thermal power and battery storage.

Ethylene yield is significant in showing the performance of the steam cracker furnace in the olefin plant. This study was conducted in the actual large-scale olefin plant to see the impact of various variables towards the ethylene yield. The analysis was conducted utilizing Regression Analysis in Minitab Software Version 18 to develop a reliable ethylene yield model. The model concluded that ethylene yield in the studied plant was contributed by the factor of -0.000901, 0.02649, -0.282, 0.16, -0.0834, 0.1268, and 0.0057 of Hearth Burner Flow, Integral Burner Flow, Steam Drum Pressure, Super High-Pressure Steam (SHP) Boiler Feed Water Flow, SHP Flow, Naphtha Feed Flow, and Stack NOx Emission respectively. The Response Optimizer tool also showed that the ethylene yield from naphtha liquid feed utilizing pyrolysis cracking can be maximized at 32.55% with control setting at 9,476.41 kg/hr of Hearth Burner Flow, 608.56 kg/hr of Integral Burner Flow, 112.93 Barg of Steam Drum Pressure, 109.11 t/hr of SHP Boiler Feed Water Flow, 86.42 t/hr of SHP Flow, 63.49 t/hr of Naphtha Feed Flow and 126.23 mg/m3 of Stack NOx Emission.

Conversion of water into steam is the primary function of a utility boiler. The steam pressure is used to turn a steam turbine thus, generating electricity. Within the boiler drum there exists a steam/water interface. Boiler steam drum water level is one of the important parameters of power plant that must be measured and controlled. For safe and efficient boiler operation, a constant level of water in the boiler drum is required to be maintained. Too low water level may cause damage boiler tube by overheating. On the other hand too high drum water level leads to improper function of separators, difficulty in temperature controlling and damage in superheater tubes. Turbine may also be damaged by moisture or water treatment chemicals carryover. The amount of water entering the boiler drum must be balanced with the amounts of steam leaving to accomplish the constant water level in the drum. Therefore it is extremely important to have the knowledge of the operating principles, installation requirements, strength and weaknesses of drum water level control system. Ignoring these considerations can result in misapplication, frequent maintenance, unsafe operation and poor instrument as well as system performance. In this paper design aspects and installation requirements of boiler drum level control are discussed for safe and economic operation.

Based on water-cooled TCA of Mitsubishi gas turbine M701F, aiming at the control difficulty of the complex control system, this paper proposes a decoupling control strategy combined water-level control of waste heat boiler steam drum and outlet pressure control of high pressure feed water pump and TCA water side flow control. Finally the effectiveness and rationality of the complete set of optimized control scheme is verified by practical engineering application.

Operational optimisation for transient processes to exploit full potential of industrial plants has become indispensable today. To overcome this problem, accurate and fast determination and prediction of water-steam transients require precise algorithms with easy structure of the approximation, to allow algebraic transformation of equations and equation systems. This is beneficial especially for solving partial differential equations in the area of thermodynamics for water/steam systems. Our contribution focuses on the definition of new approximation algorithms for the determination of state functions of water/steam for dynamic simulation. Two main aspects of this work are to reduce computational time (by saving more than 50 % just for the calculation of a single property), using a direct method with a given accuracy to enable extensive dynamic process simulation calculations also for real-time applications like demand-side management and optimal control, and to keep the whole set of equations as linear equations which can be directly solved for the unknown parameter. Additionally, occurring errors by parameter variation of the respective approximation were analysed. The practicability is demonstrated by a simple highly dynamic application example of a steam drum in load cycling behavior comparing the developed new linear and quadratic approximation functions with the industry standard IAPWS-IF97.

The Advanced Heavy Water Reactor (AHWR) is a 300 MWe pressure tube type boiling light water cooled, heavy water moderated reactor. It has natural circulation based main heat transport system with integral steam drums. Recently, work has been initiated on a novel passive safety system named Passive Auto Depressurization System (PADS) for AHWR. This system is a part of shutdown cooling system and in case of occurrence of small break loss of coolant accident; PADS system mitigates chance of reactor core temperature rise. It actuates automatically at low steam drum level and rapidly depressurizes main heat transport system so that water injection from gravity driven water pool can be initiated to maintain coolant inventory for a sufficiently long time. The main component of PADS is Passive Pulse Generator (PPG), a passive device which is actuated at low steam drum level and generates high pressure signal within a short time span. The PPG generates a passive pressure pulse of around 11 bar amplitude with 8 min response time with threshold steam drum level fall of 100 mm. This pressure pulse is used for opening a passive valve which initiates decay heat removal through isolation condenser leading to depressurization of main heat transport system. An experimental facility has been designed towards the development and performance evaluation of PPG for PADS system of AHWR. This paper deals with the design of the experimental facility describing its piping layout, steam drum & heat exchanger vessel and associated instrumentation & control system. Test results along with RELAP5 analysis are discussed to validate PPG performance for PADS in AHWR.

In this paper, the method developed by the authors to separate the inorganic materials from the hydrocarbon of the sludge deposits, which is fast and can accurately identify very small quantities of inorganic materials, has been extended to characterize the 12 types of sludge samples collected from (a) a regeneration overhead acid gas condenser, (b) water draw-off pump’s suction strainer in a gas plant, and (c) condenser, inside vessels of inlet head, and head coiler tube equipment at gas plants. The results revealed that the major phases are (a) iron sulfide corrosion products with the hydrocarbon type of mixture of diesel and lube oil for a condenser and (b) carbonate scale in the form of calcium carbonate with the hydrocarbon type of lubricant oil for sludge deposits from a suction strainer for pumps, and drilling mud in the form of barium sulfate with no organic hydrocarbon or polymer for sludge samples from a water recycling pump. Moreover, the major phases for inorganic materials built up in a condenser, inside the vessel’s inlet head, and the head coiler tube revealed that iron oxide corrosion products are found in the steam drum, and iron sulfate corrosion products are built up in the condenser. The presence of dissolved oxygen in the boiler feed water is indicated by a high wt% of iron oxide corrosion product in the form of magnetite (Fe3O4), which appeared in the inorganic materials built up in the condenser steam drum. Knowing accurately which phases and their wt% were involved in the inorganic materials can guide the field engineers to facilitate efficient cleaning of the equipment by drawing up the right procedures and taking preventive action to stop the generation of those particular sludge deposits.

Advanced Heavy Water Reactor (AHWR) being developed in India is a vertical pressure tube type boiling water reactor. In case of AHWR the steam-water two-phase flow from the core is separated in horizontal steam drums purely due to gravity i.e. density difference between the steam and water. This simple principle eliminates the need for mechanical separators and associated system pressure drop. However, the separation efficiency is affected by the entrainment phenomenon, i.e. conveyance of water droplets by the separated steam out of the drum i.e. carryover. Carryover estimation for new equipment with existing empirical correlations may not be reliable and experimental investigations in relevant geometries are necessary. In the present work carryover process has been investigated in a test facility known as Air-Water Loop (AWL). The facility aims at simulation of gravity separation of two-phase flows relevant to AHWR steam drum, using air-water mixture. During the experiments, carryover at operating levels closer to exit has been measured. AWL also has a facility for optical measurements using high speed camera. Measurements on droplet size distribution have been carried out with shadowgraph technique at different operating levels. The present work also involves the analysis of carryover using 3-D Euler-Lagrangian simulations with OpenFOAM based solver.

We developed a plant model and model-based controller for a heat recovery system with a swirling flow incinerator located in South Korea. First, a plant model was designed to understand the dynamic characteristics of the system. The system was divided into three parts: incinerator, boiler, and steam drum. Then, each part was modeled with a multi-zone, zero-dimensional modeling scheme. Consequently, we found that the plant model followed the dynamic behavior of the target system, particularly for the seven important variables: boiler inlet temperature, superheater inlet temperature, boiler outlet temperature, oxygen mole fraction, steam production rate, steam pressure, and steam temperature. Then, we designed a multi-input multi-output controller for the system with a nonlinear control model. In the controller design, input variables were selected as air flow rate, fuel supply rate and steam valve opening area; while output variables were oxygen mole fraction of exhaust gas, steam production rate and steam pressure. A nonlinear control model was constructed by reducing the plant model. Then a linear quadratic regulator was applied while evaluating control gain at each time step. Finally, we validated the controller on the plant model, which adequately suppressed the disturbance on fuel composition and adjusted the steam production rate.

This study investigated the utilization of available excess steam by the Kamojang geothermal power plant, which, owing to the vapor-domination of the steam, utilizes a dry steam cycle. A model of the system was validated against actual Kamojang Unit-2 data and found to produce accurate results within a low discrepancy level (

Advanced Heavy Water Reactor (AHWR) is a vertical pressure tube type boiling water reactor that relies on two-phase natural circulation for heat removal from the nuclear core under normal operating as well as accidental conditions. In case of AHWR, the two-phase flow generated in the core is transported by vertical riser pipes to horizontal steam drums at the top. These horizontal steam drums provide sufficient surface area for the separation of steam water mixture purely based on gravity i.e. due to density difference between steam and water. To investigate this gravity separation phenomenon, an experimental facility known as Air-Water Loop has been designed. The facility has a scaled geometry of AHWR steam drum operating with Air-Water mixture as a working fluid. The required flow conditions for the experimental simulations are generated using air-water two-phase natural circulation in this facility. Steady state natural circulation experiments were performed where measurements on recirculation flow rates, two-phase and single phase pressure drop in various sections of the loop have been carried out. The present paper aims to describe the design aspects of the facility, pre-test calculations, steady state two-phase natural circulation experiments and assessment of measured experimental data. The experimental measurements have been predicted using a numerical model that considers various void fraction and pressure drop correlations from the literature for estimation of measured parameters.

At present, wet spraying is the main process for treatment of exhaust gas emitted by the concentrated sulfuric acid roasting method for decomposition of rare earth concentrates, which not only consumes a large amount of resources but also wastes the residual heat corresponding to temperatures of approximately 300 °C. In this paper, an exhaust gas dry processing technology that is completely different from the original wet spray process is proposed and successfully implemented in a rare earth roasting kiln. The dry process has successfully realized dust removal, cooling and acid condensation from exhaust gas through a cyclone separator and heat exchange-condensing acid system, and the waste heat can be converted into steam through a steam drum, which greatly simplifies the process for treatment of roasting exhaust gas. Compared with wet spraying, the dry process has the advantages of operational simplicity, small footprint, low energy consumption, low maintenance cost and no wastewater production, which makes it a promising process for the treatment of exhaust gas from rare earth roasting.

The formation of liquid droplets in the low pressure steam turbines has devastating impacts on the turbine adiabatic efficiency and also causes the mechanical damage of blades due to the occurrence of severe erosion phenomenon. Previous investigations have shown that the injection of steam can decrease liquid mass fraction as well as the size of the averaged radius of droplets. To exploit the maximum potentials of this method, the optimization of injection variables is necessary. In the present study, the numerical solution of wet steam flow by the injection of hot steam within convergent-divergent nozzles together with a multi-objective genetic algorithm method are used to evaluate the appropriate injection parameters. It is concluded that to reduce liquid droplet size by 66% and liquid mass fraction by 13%, an injection steam flow rate of 4% of the main stream flow rate with a temperature 1.8 times of inlet steam temperature is required. Such a reduction of liquid droplet size has an enormous effect on lowering the erosion damages of blades. Furthermore, the injection drives the liquid droplets away from the solid boundaries, which is also expected to reduce the possible mechanical damages to the blades and the casings of turbine.

The design of a module for a high-efficiency condenser of steam with a high content (up to 15%) of noncondensable gases (NCGs) with a nearly constant steam–gas mixture (SGM) velocity during the condensation of steam has been developed. This module provides the possibility to estimate the operational efficiency of six condenser zones during the motion of steam from the inlet to the SGM suction point. Some results of the experimental tests of the pilot high-efficiency condenser module are presented. The dependence of the average heat transfer coefficient k on the volumetric NCG concentration v has been derived. It is shown that the high-efficiency condenser module can provide a moderate decrease in k from 4400–4600 to 2600–2800 W/(m2 K) at v ≈ 0.5–9.0%. The heat transfer coefficient distribution over different module zones at a heat duty close to its nominal value has been obtained. From this distribution, it can be seen that the average heat transfer coefficient decreases to 2600 W/(m2 K) at an NCG concentration v = 7.5%, but the first condenser sections (1–3) retain high values of k at a level of no lower than 3200 W/(m2 K), and the last sections operate less well, having k at a level of 1700 W/(m2 K). The dependence of the average heat transfer coefficient on the water velocity in condenser tubes has been obtained at a nearly nominal duty such that the extrapolation of this dependence to the water velocity of 2 m/s may be expected to give k = 5000 W/(m2 K) for relatively pure steam, but an increase in k at v = 8% will be smaller. The effect of the gas removal device characteristic on the operation of the high-efficiency condenser module is described. The design developed for the steam condenser of a gas-turbine plant with a power of 25 MW, a steam flow rate of 40.2 t/h, and a CO2 concentration of up to 12% with consideration for the results of performed studies is presented.

Waste heat recovery combined with exhaust gas recirculation is a promising technology that can address both the issue of NO x (nitrogen oxides) reduction and fuel savings by including a pressurized boiler. In the present study, a theoretical optimization of the performance of two different configurations of steam Rankine cycles, with integrated exhaust gas recirculation for a marine diesel engine, is presented. The first configuration employs two pressure levels and the second is configured with three-pressure levels. The models are developed in MATLAB based on the typical data of a large two-stroke marine diesel engine. A turbocharger model together with a blower, a pre-scrubber and a cooler for the exhaust gas recirculation line, are included. The steam turbine, depending on the configuration, is modeled as either a dual or triple pressure level turbine. The condensation and pre-heating process is optimized to utilize the maximum waste heat recovery. The Genetic algorithm and fmincon active-set algorithm are used to optimize the design and operation parameters for the two steam cycles. The optimization aims to find the theoretically optimal combination of the pressure levels and pinch-point temperatures to maximize the power production. Results show that the two-pressure level steam cycle produces 1577 kW of net power; whereas the three-pressure level cycle produces 1641 kW at full load operation. The optimum pressure levels for the two-pressure level configuration are found to be 33.4/4.7 bar a . For the three-pressure level configuration, the optimum pressure levels are found to be 33.5/10.5/4.7 bar a . The amount of waste heat recovery from the pressurized boiler is significantly higher than from the main boiler for both cycles. It is, therefore, concluded that the three-pressure level steam cycle (configuration 2) is more efficient than the two pressure level cycle (configuration 1). At the same time, the engine equipped with waste heat recovery with a three-pressure level steam cycle is simpler to operate in Tier II operation. However, the two-pressure level steam cycle is a simpler configuration.

Most of the electricity being produced throughout the world today is from steam power plants. At the same time, many other competent means of gener-ating electricity have been developed viz. electricity from natural gas, MHD generators, biogas, solar cells, etc. But steam power plants will continue to be competent because of the use of water as the main working fluid which is abundantly available and is also reusable. The condenser remains among one of the key components of a steam power plant. The efficiency of a thermal power plant depends upon the efficiency of the condenser. In this paper, a the-oretical investigation about thermal analysis and design considerations of a steam condenser has been undertaken. A hybrid steam condenser using a higher surface area to diameter ratio of cooling a water tube has been analyzed. The use of a hybrid steam condenser enables higher efficiency of the steam power plant by lowering condenser steam pressure and increasing the vacuum inside the con-denser. The latent/sensible heat of steam is used to preheat the feed water supply to the boiler. A con-ceptual technological design aspect of a super vacu-um hybrid surface steam condenser has been theo-retically analyzed.

The operation of steam boilers with high efficiency requires control of thermo-hydraulic and strength parameters in the on-line mode. During operation under transient conditions, there are signific...

Horizontal well technology is widely used in the production of heavy oil. Steady-state model is used as main research method and assume constant wet steam parameters in wellbore, ignoring the impact of heat and mass transfers of steam from wellbore to the reservoir. Numerical calculation is used to analyze steam-water-oil three-phase on flow and heat transfer rule in reservoir and wellbore in startup phase. The influence rule on diffusion process of vapor and water hindered by oil stockpile in wellbore was analyzed, as well as vapor and water parameters change rule along the well. Result indicated that wet steam moving forward was hindered by oil stockpile in wellbore, which lead reservoir suction steam to be not uniform; dryness and temperature of steam gradually reduce, resulting in high temperature at the heel and low temperature at the toe of reservoir; reservoir suction steam effect was improved and reservoir heated range was expanded gradually with the increasing of steam injection volume an...

Direct use of a steam heat source for the organic Rankine cycle system is one of the key challenges in various plant industries where low-grade steam is available and is becoming difficult as the parent system has a strong variability. In addition, changing the type of the heat source fluid among steam, hot water, thermal oil and others from the parent plant could increase the operation time of the heat recovery system, which increases system economics and makes it more attractive. Although a variety of ORC systems have been developed mainly using single heat source as hot water heat source or a heat transfer loop. An ORC system with the direct use of a steam heat source has been rarely reported, and a system using two different heat sources have not been reported yet. Here we evaluate the performance characteristics of an ORC system using two different heat source fluids: steam and hot water. The target ORC system was originally developed for the hot water heat source and has a simple cycle configuration with R245fa as working fluid, and is composed of typical four components as: a two-stage radial turbine and a coupled generator, plate-type heat exchangers with a refrigerant tank, and a multi-stage centrifugal pump. The nominal net power output at the design point is 187.9 kW with the turbine expansion ratio of 9.5. The heat exchanger analysis showed that the steam heat source can be applied to this system. The isothermal heat exchange and high heat transfer coefficient at the two-phase region of the steam showed a large overdesign for the current application. We tested the ORC system using a steam generated from an incineration plant. The temperature and pressure of the steam were 143.5℃ and 302 kPa. We showed that the ORC system originally developed for the hot water heat source could be used for the steam heat source without any major system changes.

The sudden expansion of steam in the last stages of turbines causes a nucleation process to take place and liquid droplets to appear. Parts of these droplets, which grow collide with the blades and seriously damage them. This mechanical destruction also coincides with a thermodynamic shock which suddenly increases the pressure and reduces the performance of the steam turbine. In the present study, an attempt is made to control the size of droplets and liquid mass fraction by injecting hot steam to reduce the level of the damage. This process is similar to extracting steam from upper stages and injecting it into downstream stages. In order to prove the concept of this method, a one-dimensional in-house, two-phase flow code with steam injection is developed. The conservation equations are formulated for the vapor/liquid mixture and the liquid phase is modeled by two additional transport equations. Size and number of droplets together with liquid mass fraction are calculated in different convergent-divergent nozzles and the results are compared with experimental values. Then, the steam with higher pressure and temperature is injected into various locations in the nozzle. The results show that injecting hot steam in the divergent point of the nozzle downstream of the throat and following the Wilson point reduces the size of droplets but increases their number, which can ultimately, degrade the erosion of the blades. It is also concluded that in such a situation, the injection mass flow rate of nearly 5% of main stream flow with a temperature of about 30% higher than the main stream temperature is efficient in controlling wet steam parameters.

This paper addresses a thermodynamic analysis of steam injection in the combustion chamber of a large size gas turbine considering blades cooling and NOx emissions. Since heat transfer from the mixture of gas and steam is higher than the one from gas alone, the blades would be inefficiently cooled and their material might be affected. Thus, to preserve their temperature below the required limit, two solutions are proposed; the first keeps combustor discharge temperature at its initial value and increases the quantity of coolant and the second keeps the initial quantity of coolant and decreases the combustor discharge temperature. The results show that both solutions lead to the enhancement of performances but the first solution gives better results and allows producing a maximal steam/gas fraction of 14% while for the second solution this fraction is 11%. The power is increased from 270 MW to 388 MW and 302 MW respectively for the first and the second solution and the efficiency from 38% to 42.7% and 40.2%. The results have also shown that the amount of NOx produced is significantly decreased and may reach a value of 10 ppm for the first solution and 14 ppm for the second one.

We develop a method for the evaluation of the influence of hydrogen on the strength and durability of the drum of a high-pressure steam boiler subjected to thermal cycling and hydrogenation. We analyze the influence of hydrogen on the accumulation of damage to the metal and the duration of operation of the drum for different modes of damage. It is established that hydrogen accelerates the accumulation of damage and reduces the period of operation of metals by 25–30% for planned shutdowns of the boilers and by 40–50% for their emergency shutdowns.

In this study, thermal efficiency of power plant has been evaluated by integrating the KIER-developed dry-sorbent CO 2 capture process (KIERDRY) with a pulverized coal-fired power plant using a commercial simulator, gPROMS. A simple basic KIERDRY model has been developed and connected it to PCPP (Pulverized Coal Power Plant) example in gCCS, a system modelling tool for support of design and operating decisions across the CCS chain. The PCPP capacity of 500 MWe and the KIERDRY capacity of 150 MW (125 tonCO 2 /hr based on captured amount) have been set as a base case. We consider HP steam(307 o C, 31 bar) and IP steam(461 o C, 14∼14.6 bar) as the utility steam of a regenerator in KIERDRY since the steam condition of a regenerator has been set to approximately 14.6∼15 bar, saturated. Totally 5 cases have been evaluated: (1-1) Use HP steam, use condensate to make a process steam, and return to condensate(1 bar); (1-2) Use HP steam and return to 5th feed water heater(12 bar); (2-1) Use IP steam, use condensate to make a process steam, and return to condensate(1 bar); (2-2) Use IP steam and return to 5th feed water heater(12 bar); (2-3) Use IP steam, do additional heat integration by preheating dry sorbents at loop-seal, and return to 5th feed water heater(12 bar). As a result, the condensate generated at the regenerator should be returned to the power plant rather than used to make a process steam, which is supplied as a reactant for the carbonation reaction. Based on several case studies, the reduction of the power output of the PCPP with KIERDRY has been varied from 29.2 MWe(minimum penalty) to 71.7 MWe(maximum penalty). Thus, it can be concluded that the energy penalty of KIERDRY has been significantly reduced by how heat has been integrated with PCPP.

GE2M-PG test facility was constructed at the JSC “SSC RF-IPPE” for assessment of efficiency of VVER steam generator and investigation of effects of initial conditions of the accident on the processes of heat exchange in the steam generator (SG) tube bundle assembly. The facility was used in two series of experiments with and without removal of the steam–gas mixture (SGM) from steam generator cold collector. Functionality of the steam generator model in condensation mode with different concentrations of non-condensable gases in steam at the SG model inlet and different flow rates of steam–gas mixture removed from cold collector was investigated during the first phase of experiment. Effects of main factors of operational modes on the efficiency of heat exchange processes in the steam generator tube bundle assembly was investigated during the second phase of experiments conducted without removal of steam–gas mixture. The obtained results can be applied for verification of computer codes used in calculation simulation of emergency processes in VVER reactor facility.

The steam injection technology is widely used in heavy oil production. The higher the steam injection rate is, the more beneficial the exploitation of heavy oil is. In this paper, we choose the twodimensional rotation axis symmetry model, using VOF model of steam injection wells, wet steam phase change, transient analysis of influence of different injection pipe string structure in vertical well section during the process of steam injection on steam injection parameters and changes of single and dual steam injection steam injection well bore in steam parameters during the process of steam injection in horizontal wells. The analysis results show that the vertical well steam injection by high vacuum insulated tubing make minimize the dryness of the steam; Toe end dry degree is higher than that of single tube steam injection when horizontal pipe steam injection, which is conducive to the balanced development of heavy oil.

Many industrial processes require high amounts of steam. Design and operation of steam plants are particularly complex when the steam supply is required for short periods and with a varying time schedules. To fulfil the discontinuous needs of steam users, avoiding the steam boiler oversizing to the peak value of the steam request, a thermal energy storage (TES) system can be adopted. The proper sizing of TES systems, which, in this application, is constituted by a steam accumulator vessel installed between the steam generator and the consumer, cannot be based on the sole initial and final state conditions of the steam storage, since a performance prediction of the process time-evolution is also required. In this paper, a model of steam batch processes for industrial thermal treatments, able to describe unsteady operative conditions, is presented. More in detail, a three-stage steam plant, with a sequentially interconnected steam boiler, steam accumulator and processing tank, has been considered. The dynamic model of the charging and discharging processes of the steam accumulator has been applied to a real case study in the food industry: the batch debacterisation process of cocoa beans. Nevertheless, the obtained results can be profitably employed in the design and the performance assessments of a wide set of applications involving the steam processing fluid, such as desalination plants, solar thermal power plants, retorts, steam ovens and others.

In this paper, energy, exergy and economic (3E) analyses have been performed on a conceptual power plant cycle formed by integrating solar energy in steam cycle of a natural gas fired combined cycle power plant (CCPP). Solar integration has been done at medium temperature level using direct steam generation (DSG) technique with parabolic trough collectors. A portion of the feed water leaving the high pressure economiser-1, goes to the solar field for preheating and evaporation. As the feed water passes through the absorber tubes of the solar field, part of it is evaporated into steam. The water-steam mixture leaves the solar field and enters a separator placed at the end of the solar collector field. The separator separates the steam from the water-steam mixture. The water is sent back to the solar field using a recirculation pump whereas the separated dry steam leaving the separator is allowed to mix with the dry saturated steam leaving the high-pressure drum. Superheating of steam takes place in the heat recovery steam generator (HRSG). The results have shown that the energy and exergy efficiencies of solar field are 53.79% and 27.39% respectively. The results have shown that plant output has increased by 7.84% with solar field operating at design point for a 50 MW th nominal solar field capacity. The levelised cost of electricity generation has been observed to be lowered from 7.4 to 6.7 cents/kW h.

A thermal analysis of two combined cycle power plants is performed. The steam injection system in the combustion chamber constitutes the main difference between the two designs. For the first power plant (design 1) the injected steam is generated in the HRSG. While for second power plant (design 2) this steam is provided using a heat recovery system installed at the compressor outlet. The steam turbine cycle engenders two pressure extraction levels connected to open feed-water heaters. The steam injection in the combustion chamber improves the overall combined cycle efficiency if this steam is generated outside the HRSG. The increase of the ambient temperature affects the overall cycle efficiency. The optimum thermal efficiency, for any temperature value during the year, may be obtained for suitable margin of steam injection ratio. The second design presents better overall efficiency then the first one. In winter season (T am = 15 °C), the overall cycle efficiency is about 54.45% for a range of steam injection ratio within 11.8 and 14%. While in summer season (T am = 35 °C) and for the same cycle efficiency, the required range of steam injection ratio is between 18.5 and 18.8%.

Perubahan laju aliran uap menimbulkan gangguan pada sistem pengaturan level air steam drum. Level air dijaga pada titik tengah ketinggian drum atau disebut Normally Water Level (NWL), agar uap yang dihasilkan memenuhi spesifikasi serta tidak merusak peralatan pada pembangkit. Pada umumnya, sistem pengaturan level menggunakan kontroler PID konvensional. Namun, adanya gangguan dapat menyebabkan performa sistem dengan kontroler PID konvensional tidak mampu memenuhi spesifikasi. Kontroler PID-Genetic Algorithm (PID-GA) diterapkan untuk mengatur level air steam drum agar berada pada titik NWL ketika terdapat gangguan. Sistem pengaturan menggunakan kontroler PID-GA mampu meredam gangguan berupa beban minimal, nominal, dan maksimal, yaitu dengan perturbation peak masing-masing sebesar 0,18 m; 0,22 m; dan 0,26 m.

Boiler is an important utility system to support operations in the industry. The control of water level in the steam drum is a complicated task due to the non-minimum phase (NMP), which possibly will cause instability to the controlled water level in the steam drum. Process identification and controller design are difficult tasks for the steam drum because of non-minimum phase. Following the previous literature, this paper proposed process identification to 3rd order transfer function and optimization of Proportional-Integral-Derivative (PID) tunings of the water level by using Particle Swarm Optimization (PSO). A Graphical User Interface (GUI) has been developed to provide a direct platform to deal with these tasks. The result of PSO is compared with other tuning methods in terms of performance indicator and index. An analysis of the performance curve in 3-dimension graphs is also presented to visualize the output performance of various proportional and integral gain settings. The study has concluded that PSO provided better PI tunings for the best control of the Heat Exchanger function in the LOOP-PRO software.

Šiame tiriamąjame darbe atlikta garo katilo vandens lygio režimų analizė, realizuotas supaprastintas ir išplėstinis garo katilo vandens lygio režimų matematinis modeliai. Buvo parinkti modelio parametrai remiantis realiais duomenimis, sukurta vartoto sąsaja Matlab Simulink programiniame pakete įvairių valdymo režimų realizavimui. Imitacinis garo katilo vandens lygio režimų matematinis modelis verifikuotas taikant realius elektrinės duomenis. Atlikti tyrimai parodė, kad modelis adekvatus ir jį rekomenduojama taikyti procesų operatoriams tiriant įvairius valdymo režimus, efektyvumą ir derinant valdymo sistemą., In this research, steam boiler water level mode analysis was performed, simplified and extended mathematical models of steam boiler water level modes were implemented. Model parameters were selected based on real data, user interface created in Matlab Simulink software package for realization of various control modes. Simulation model of steam boiler water level modes has been verified using real power plant data. The research has shown that the model is adequate and recommended for process operators in the study of various control modes, efficiency and tuning.

During the inspection of a boiler containing cracks at the superheater header connection, cracking also was detected within the main steam drum. This was fabricated from a Mn-Mo-V low-alloy steel. It operated with water and saturated steam at approximately 335 deg C. Cracking was detected at the nozzles connecting the tubes for the entry of steam and hot water to the drum, at the downcomers, and at the connection to the safety valve. All cracks had a similar morphology, running in a longitudinal direction along the drum from the cutouts in the shell. All the cracks had developed under the influence of the hoop stress and were associated with the locally increased stress levels relating to the cutouts at nozzle and pipe connections. At their ends the cracks were filled with corrosion products, and their surfaces were seen to be very irregular. The process of crack growth was not due to fatigue only but can most probably be attributed to corrosion fatigue. The boiler steam drum design should be reviewed to reduce the local level of stress at the shell-nozzle connections.

The industrial tomographic 2-D gamma scan is an innovative non-destructive nuclear test designed to troubleshoot problems with process equipment, such as distillation columns and reactors. Due to physical restrictions, normally the gamma ray source and detector can only be positioned laterally to the equipment. The 2-D gamma scan is able to reconstruct the interior of the equipment even under this restriction, generating rectangular 2-D axial density profiles of equipment. To obtain clear reconstructions, it is necessary to collimate the detector, discarding the divergent incoming rays. It is not possible to use physical collimation in an industrial environment, as it is impossible to point the detector precisely in the direction of the gamma-ray emitter. In this article, we describe a technique we call “electronic collimation for gamma scan” that allows obtaining collimated data without physical collimation. We use 2-D gamma scan to evaluate a huge dilution steam drum in a large petrochemical plant to investigate possible problems with three demister pads. The low density of the demisters when compared to the vessel and surroundings makes it difficult to generate a reconstructed image where demisters are clearly visible. We describe how we overcome these difficulties using information known a priori about the equipment. We also ran simulations to show the superiority of 2-D gamma scan over conventional scan. These simulations also showed that, if there were defects in the demisters, we would observe them in the reconstructed images. We conclude that electronic collimation and prior information are essential for evaluating properly equipment with challenging layouts and low density parts.

Liquid entrainment or carryover is a phenomenon that liquid droplets are carried out from a boiler or steam drum during steam generation. The droplets may convey some dissolved solids and cause damage to steam equipment such as scaling deposits in valves and steam piping and erosion of turbine blades. The appearance of dissolved solids in boiler water mainly comes from the internal water treatment process by dosing some chemical substances into the boiler in order to prevent corrosion and scale formation. Trisodium phosphate (Na3PO4) is one of chemical substances commonly added during boiler operation to control the pH of boiler water. However, it can cause the occurrence of sodium hydroxide (NaOH) solution which results in the increase of total dissolved solid (TDS) concentration in boiler water. Therefore, this study is aimed to develop a test section in order to investigate the parameters affected by liquid entrainment in the boiler. The experiment is performed in ambient conditions under an air-water system. Three variable factors are taken into consideration, including the concentration of NaOH solution, the height of the water level in the test tank, and the gas superficial velocity which represents the flow velocity of steam during steam generation. The results show that the increase of the gas superficial velocity and the water level height in the tank resulted in the enhancement of the entrainment rate. The increase of the water level height played an important role on the liquid entrainment. The increase of NaOH concentration directly impacted the existing film bubbles and the longer stability of foam bubbles at the water surface which resulted in a higher entrainment rate. Therefore, TDS control was one of the most important factors which could be incorporated with the appropriate height of the water level and the consistency rate of steam generation in order to minimize the liquid entrainment.