Superheated Steam Temperature Research Articles

Innovative Sensor Design Method of Industrial Ceramic Product Modeling Based on Immune Optimization Algorithm

A new method based on immune optimization algorithm was proposed for modeling and design of industrial ceramic products. Based on the joint coding of fuzzy rules and membership function parameters, an improved immune optimization algorithm was used to realize the synchronous optimization of industrial ceramic product modeling. A superheated steam temperature control system is taken as an example to carry out simulation tests. The results show that the ratio of the unit volume to the side length is between 0 and 1, which is called the mass of the grid element. Zero is the worst quality and one is the best. Element aspect ratio and distortion degree are also basic inspection indexes. The average mass of vacuum glass is 0.86, the aspect ratio is 1.71, and the element distortion degree is 0.13, indicating that the grid quality is well divided. It is proved that using the improved immune genetic algorithm to optimize fuzzy control can overcome the defects of the traditional genetic algorithm and ensure the faster and more stable search for the optimal rule base and membership function.

Development and validation of a dynamic flowsheet model for a 350 MWe supercritical circulating fluidized bed boiler

The circulating fluidized bed (CFB) boiler is highly recommended in peak shaving for its wide load regulating range compared with the pulverized coal (PC) boiler. However, the research on dynamic flowsheet model of the CFB boiler is quite limited due to its complex flow regime. In this paper, both steady state and dynamic flowsheet model of a supercritical 350 MWe CFB boiler was developed based on Aspen Plus and Aspen Dynamics software coupled with comprehensively user defined combustion kinetics and heat transfer coefficient with FORTRAN subroutines. This model was then validated by the operating data of the 350 MWe supercritical CFB boiler. Based on this model, the dynamic characteristics of three typical step signal disturbances, coal flow rate, primary flow rate and secondary air flow rate, were further analyzed to provide theoretical references to dynamic operation. Also, the quantitative relation between the stabilization time and step signal amplitude was calculated. The calculated dynamic characteristics demonstrates that the heat distribution does not vary much after adding step signal disturbances of coal flow rate, primary air flow rate and secondary air flow rate. The step signal disturbance of secondary air flow rate has less influence to the CFB boiler system compared with that of primary air flow rate. The superheated steam temperature is more sensitive to step signal disturbances compared with reheated steam temperature. The higher step signal amplitude results in longer stabilization time. Above all, this dynamic flowsheet model can not only be used to conduct dynamic behavior prediction and analysis but also provide transfer functions to the further development of CFB automatic control system.

Influence of Superheated Steam Temperature and Moisture Exchange on the Inactivation of Geobacillus stearothermophilus Spores in Wheat Flour-Coated Surfaces

Influence of Superheated Steam Temperature and Moisture Exchange on the Inactivation of Geobacillus stearothermophilus Spores in Wheat Flour-Coated Surfaces

Multi-model adaptive predictive control of superheated steam temperature of DSG solar parabolic-trough collector based on heat-steam ratio and its reference trajectory

The direct steam generation (DSG) solar thermal power generation system has obvious inertia and nonlinearity in the response of superheated steam temperature. Due to the intermittent and random fluctuations of solar irradiation, the DSG system frequently undergoes large changes in operating conditions, which results in a very complicated problem of controlling the superheated steam temperature at the collector outlet. This paper proposed a multi-model adaptive control scheme based on the heat-steam ratio and its reference trajectory for the control problem of the outlet steam temperature of the DSG solar parabolic-trough collector. Firstly, through analyzing the dynamic characteristics of the superheated steam temperature, the main factors and the main nonlinear characteristics that lead to the nonlinearity of the steam temperature response are revealed. Secondly, taking the ratio of solar irradiation to the outlet steam flow (heat-steam ratio) as the characteristic parameter based on the nonlinear characteristics of the system, the DSG collector system is divided into several linearized subspaces, and then the corresponding steam temperature predictive sub-model set and steam temperature adaptive predictive control scheme are established. Finally, a smooth switching strategy based on the reference trajectory of the nonlinear characteristic parameter (heat-steam ratio) is established in response to the frequent or large switching of the controller caused by the large changes in the operating conditions, which effectively improved the stability of the temperature control process of the superheated steam at the DSG collector outlet. In this paper, the effectiveness of the above-mentioned control scheme has been preliminarily verified through simulation experiments.

Prediction of superheated steam temperature for thermal power plants using a novel integrated method based on the hybrid model and attention mechanism

The stability of superheated steam temperature (SST) is severely challenged by the adjustment of thermal power plants under a wide-load range. Accurate and efficient prediction of SST plays an important role in the control of superheat system. To this end, an SST prediction model based on a multi-mode integrated method is proposed in this paper. Firstly, conservation of energy, as an equality constraint, is introduced into the loss function of the data-driven model based on Long Short-Term Memory (LSTM) architecture. Subsequently, the physical relationship between SST and the spray water flow, as an inequality constraint, is introduced into the above loss function. Finally, an individual hybrid model for each operating mode is developed and integrated with multi-mode switching strategies based on attention mechanism. Operating data with a wide-load range is sampled from a supervisory information system (SIS) to validate the superiority of the proposed method. The comparison results demonstrated that the predictive effect of the hybrid model with physics-based loss function is not only generalizable but also scientifically consistent with the dynamic characteristics of the step response. Furthermore, the results of the multi-mode integrated model prove the effectiveness of the mode switching strategy based on the attention mechanism.

Control of steam bottoming cycles using nonlinear input and output transformations for feedforward disturbance rejection

In this paper we analyze the control problem for a steam cycle that produces power by recovering waste-heat from gas turbines on an offshore installation. The waste-heat recovery unit is based on once-through steam generator technology. The main disturbances are large variations of the gas turbine exhaust gas flowrate and temperature. We analyze the effect of these disturbances on the operation of the steam cycle, specifically for the superheated steam pressure and temperature. We compare the performance of different decentralized control strategies based on standard PID-controllers and nonlinear feedforward. We consider floating pressure and constant pressure operation strategies. For steam temperature control we implement feedback, and feedback in combination with nonlinear input and output transformations for feedforward disturbance rejection. These transformations are based on the steady-state energy balance on the waste heat recovery unit, while for simulation purposes we use a high-fidelity dynamic model of the bottoming cycle designed to minimize the weight and volume. The outcome from this work can be used to propose control strategies for coordinating a combined cycle (gas turbine with a steam bottoming cycle) that can operate with large and rapid changes in power demand.

Application of anti integral saturation cascade PID control algorithm in superheated steam temperature control

At present, most units adopt the superheated steam temperature control system with cascade PID control structure. However, because most cascade PID control algorithms have no anti-integral saturation function, the automatic control of boiler superheated steam temperature cannot be put into operation normally. On the existing cascade PID superheated steam temperature regulation system, we judge the deviation value of the main regulator and the output value of the auxiliary regulator, and cancel the integration function at an appropriate time. When the input deviation signal turns over, the regulating system can immediately enter the normal regulating state, so that the cascade PID superheated steam temperature regulating system can timely and accurately regulate the superheated steam temperature. The fuel cost is saved by about 155,600 yuan per year.

Developing an analytical model to predict the energy and exergy based performances of a coal-fired thermal power plant

In the present study, an analytical model has been developed to predict the effectiveness of the closed feedwater heaters based on the measured data available from a coal-fired thermal power plant. Invoking this model, a ‘Predictive Model’ has been developed to anticipate the energy and exergy-based behavior of the coal-fired power plants. In this model, all the components have been assumed to be installed, and hence they could not be changed. Based on this model, a numerical code has been developed to analyze an existing coal-fired power plant using Engineering Equation Solver software. Invoking this code, the impact of the operational conditions on the performance of the power plant is examined. The effects of superheater outlet pressure, superheater outlet temperature, and reheater inlet pressure upon energy and exergy-based parameters of the cycle have been examined. It has been observed that by increasing the superheater pressure by 100%, the net power delivered by the cycle increases more than 8%. While increasing the superheated steam temperature from 539.8 to 580 °C, the net power delivered by the cycle increases more than 6%. Further, by increasing the reheater pressure from 30 to 34 bar, the net power delivered by the cycle reduces 1.57%.

Parametric Assessment of The Thermal Performance of Coal-Fired Power Plant

Exergy analysis has been found to be a useful method for improving the conversion efficiency of energy resources, since it helps to identify locations, types and true magnitudes of wastes and losses. It has also been applied for other purposes, such as distinguishing high- from low-quality energy sources or defining the engineering technological limits in designing more energy-efficient systems. To identify locations, types, and actual magnitudes of energy losses; exergy analysis has been found to be a valuable way for enhancing the conversion efficiency of the different energy systems. The aim of this research is to analyze the effect of the operation conditions on the performance of coal-fired power plants. As well, this study focuses on the effect of different feedwater heaters' numbers that lead to the highest exergy destruction of the coal-fired power plants. For different values of the superheated steam temperature and the pressure, a parametric study was conducted to determine the efficiency of the coal-fired power plant. The results show that, when the pressures and temperature of the superheated steam increases the evaporator temperature will increases too. Increasing the temperature of evaporator rises the average maximum temperature of the cycle, which improves the thermal efficiency of the cycle as well as the powerplant efficiency. The results show that, at higher boiler pressures and temperatures, the temperature difference between the water/steam and hot gases of the boiler is reduced which means the irreversibility associated with the heat transfer process decreases. Therefore, by increasing the pressure and temperature of the superheater, the exergy efficiency of the thermal cycle is improved. It was observed that operating the coal-fired power plant at high superheated pressure and temperatures produce lead to reduce the exergy losses.

Control of high-order processes: near-optimal robust tuning of PID regulators for repeated-pole plus dead-time models

This paper aims to present an analysis of the performance and robustness characteristics of repeated-pole plus dead-time (RPPDT) model PID (Proportional Integral Derivative) regulatory control system. Their performances are evaluated with the integrated absolute error index (IAE) and their robustnesses with the maximum sensitivity ( M S ). Normalised controlled process models and controllers are used for control system design. Optimal – robustness free – and optimal robust PID regulators parameters are found. A Near-Optimal Robust tuning rule (NORpid) for PID controllers based on high-order RPPDT models is obtained and applied to the control system of an eighth-order process. Examples include the control of the superheated steam temperature system (SHSTS) of a 500-MW boiler.

Deep-learning modeling and control optimization framework for intelligent thermal power plants: A practice on superheated steam temperature

Deep-learning modeling and control optimization framework for intelligent thermal power plants: A practice on superheated steam temperature

Configuration Design of Superheated Steam Temperature Control for No.2 Unit of Diaobingshan Power Plant

Configuration Design of Superheated Steam Temperature Control for No.2 Unit of Diaobingshan Power Plant

Advancement of steam generation process in water tube boiler using Taguchi design of experiments

Steam generation and utilization are needed in many industries and home appliances with, specific requirements. Though there are numerous categories of boilers available for steam generation, this analysis concentrated on the water tube boiler since it produces more steam and offers better safety measures. Taguchi techniques are considered in this entire research work completed through design of experiments (DOE). Orthogonal array L16 is selected to examine the steam generation with four process parameters and four levels. Selected process parameters are namely temperature of feed water (°C), the pressure of feed water (bar), cold water supply (liters), and boiler drum pressure (bar). The response of this study is the as steam generation to since increasing the steam is a target of this investigation. The experimental value of the steam generation is compared with the desired range; most of the response values are within the predicted value. Further, the superheated steam temperature and pressure analysis were also carried out. The maximum steam generation is achieved as 84.31 L; registered in the 15th run of the experiment.

Application of Iterative Feedback Tuning Method in Superheated Steam Temperature Control System

Taking a 600 MW supercritical once-through boiler as the study object, this paper designed an IFT-based two-degree-of-freedom (DOF) PID superheated steam temperature control system. Besides, the IFT-PID controller was formed and compared with the conventional tuning method. The simulation results show that this method can be successfully applied to great-inertia and large-lag controlled objects, with evident superiority.

PID Controllers with a Constant Speed Actuator: Implementation Versions and Self-Tuning of Pulse Duration

The article considers three implementation versions of controllers operating with constant speed actuators that are used in automation systems of a technological process: with a relay-pulse control unit (RPCU) with a lagging feedback and topping differentiator (a real differentiating element, RD), with calculating the output according to a PID algorithm and using the actuator model for its implementation, and with calculating the control output speed and using a pulse-width modulator. Formulas for calculating the parameters of the RPCU and RD primary components from the condition of approaching the equivalent PID algorithm are given. The system version with a PID controller with the actuator control proceeding from its model is considered in two options: with individual integrators for the controller’s integral component and the actuator model, and with a common integrator for the controller’s integral component and the actuator model. In the latter option, the signal from the actuator model is subtracted from the controller’s integral component, due to which the possibility of the integrator’s output to reach the integral component’s limit values is ruled out. The versions are compared by analyzing the automatic control system performance in the pulsed actuator’s operation mode based on simulation for the superheated steam temperature control section of a steam boiler equipped with a surface steam desuperheater. The analysis was carried out taking into account both the usual dynamic accuracy indicators and the number of actuators switched into operation during the transient. It is shown that the advantage of the version with the PID algorithm and common integrator for the integral component and the actuator model is that there is no need in this case to calculate the controlled variable second derivative; in addition, this version is free from the problem connected with accumulation of the difference between the signals from the actuator and its model. This version can be considered to be more preferred in implementing a PID algorithm in the software of programmed controllers. Recommendations for self-tuning of pulse duration and the control unit relay element parameters during the control process depending on the algorithm’s individual components are given. By using the proposed recommendations, it becomes possible to achieve an essentially lower actuator switching frequency during the control process.

Quality Characteristics of Semi-Dried Restructured Jerky Processed Using Super-Heated Steam.

Moisture content and water activity play important roles in extending the shelf life of dried meat products, such as jerky. However, the commonly used hot air drying process is time-consuming, costly, and adversely affects the quality of dried meat products, warranting the development of an advanced and economical drying method. This study investigated the effect of super-heated steam (SHS) drying on the quality characteristics of semi-dried restructured jerky as a measure to prevent the excessive quality deterioration of meat products during drying. The control sample was dried using hot air, and the treatment samples were dried using SHS at different temperatures (200, 250, and 300 °C) and for different durations (90, 105, and 120 min). With increasing SHS temperature and duration, the moisture content, water activity, and residual nitrite content of the jerky were reduced. The shear force values for treatments at 200 and 250 °C were lower than those for the control. With a non-significant difference in lipid oxidation compared with the control, the overall acceptability score was the highest for the treatment at 250 °C for 120 min. In conclusion, SHS (250 °C for 120 min) drying has a potential industrial value to replace the hot air drying method.

Energy Requisite and Drying Capacity of a Superheated Steam Dryer

This research was carried out to determine the energy requisite in terms of the specific thermal energy consumption, the specific electrical energy consumption and the drying capacity of a superheated steam dryer. The superheated stream dryer consists of a boiler housing, steam transfer pipes made of galvanized steel, super-heater made up of two (2) heater bands of 4000W (used to convert saturated steam to superheated steam), superheated chamber made of galvanized steel, the drying chamber made using stainless steel, a PID temperature controller (for regulating the temperature of superheated steam) as well as a water heater of 1500W to raise the temperature of water to saturation temperature. The result observed revealed that, drying capacity ranged from 0.1 to 0.36 kg/h, specific thermal energy consumption ranged from 9.22 to 19.99 kJ/kg and specific electrical energy consumption ranged from 15.41 to 57.17kWh/kg as influenced by temperatures of 160-180 °C, bed depths of 1 to 5 cm and tempering time of 20 and 40 minutes. Results obtained proves that drying paddy rice in a superheated steam dryer in comparison with hot air dryer has lesser energy consumption and saves operational cost.

The effect of water activity and temperature on the inactivation of Enterococcus faecium in peanut butter during superheated steam sanitation treatment

The objective of this study was to investigate the inactivation kinetics of Enterococcus faecium in peanut butter under different water activities (aw) and superheated steam temperatures. Peanut butters were prepared at 4 different initial water activities (0.19, 0.40, 0.60, and 0.80) and E. faecium was inoculated into the peanut butter (7.4–8.7 log CFU/g). The inoculated peanut butter samples were exposed at 4 different superheated steam temperatures (125 °C, 175 °C, 225 °C, and 250 °C). Survivor data were modelled using Weibull and log-linear models to describe the inactivation kinetics of E. faecium. The decimal reduction times (D-value), temperature sensitivity (zT) and aw sensitivity (zaw) of the D-value were determined from a log-linear model, and inactivation parameters from the Weibull model were also evaluated. An increase in aw of peanut butter and superheated steam temperature decreased the D-value of E. faecium. The zaw-value and zT-value were determined to be 0.60 ± 0.09 and 194.66 ± 40.69 °C, respectively (R2 > 0.89). The inactivation kinetics of E. faecium on surfaces contaminated with peanut butter can provide comprehensive information to superheated steam sanitation treatment which may be applied to environmental surfaces for effective microbial inactivation without the introduction of water.

State variable-fuzzy prediction control strategy for superheated steam temperature of thermal power units

With the large-scale grid connection of new energy power, the random fluctuation existing in the power system is intensified, which leads to frequent fluctuation of load instructions of thermal power units. It is of great significance to improve the variable load performance of the coal-fired units. It is more difficult to control the superheated steam temperature (SST). In order to improve the control performance of SST, a state variable fuzzy predictive control method is proposed in this paper. Firstly, Takagi-Sugeno fuzzy state observer is used to approximate the non-linear plant of the SST. At the same time, based on the state observer, a fuzzy state feedback controller is designed to improve its dynamic characteristics. Thirdly, based on the extended predictive model of the state feedback controller, a model predictive controller is designed to realize the SST tracking control. Dynamic simulation shows the effectiveness of the strategy.

Research on Carbon Emission Index Data of Turbine Unit Based On Variable Parameter Operation

At present, the problem of climate warming caused by greenhouse gases dominated by CO2 has become the focus of global environmental governance, and China is facing severe pressure of carbon emission reduction internationally. In this paper, from the perspective of the operation of coal-fired units, based on the CO2 generation coefficient of unit standard coal consumption, combined with the consumption difference analysis, the influence degree of the main controllable operating parameters such as the pressure, temperature of superheated steam and reheated steam of the units, as well as the boiler exhaust temperature, on Qco2 , that is, the sensitivity of Qco2 to the changes of each parameter is studied. On-site operating personnel of the unit can focus on monitoring and real-time adjustment of controllable operating parameters that have a great impact on Qco2 , so as to ensure that the unit is at a low carbon emission intensity level, thus reducing the total carbon emissions of coal-fired power plants. Finally, through experiments, it is proved that the steam turbine parameter optimization method studied in this paper can provide higher unit efficiency and reduce carbon emission level.