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This paper develops a control system for a drum-boiler unit, which employs a three element cascade control (water level, steam flow, feed-water) versus a single element control for the water level loop, in order to attenuate the non-minimum phase shrink-and-swell effect. The overall control structure includes a heat flux control loop for throttle p...
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... heat flux are presented. The swell effect is shown. Using 1 element control the command decreases, due to the swell effect and after a period of time increases. By using 3 element control, the feed-forward steam loop adds predictability to the control structure and deals better and faster with disturbances acting on the inner loop. In Fig. 8 and Fig. 9, the same scenario is presented but at 90% ...
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... high loads, it is observed that three elements control presents significant improvement over single element control. A GUI was developed ( Fig. 9) to facilitate the human- machine interaction. Operators start the simulation in one of the four operating points. They have the possibility to make manual or automatic maneuvers by switching one of the control buttons. By modifying the setting points, they can observe transient and stationary process ...
Citations
... The boiling point and density of water and steam will both change as the pressure changes. The amount in the steam drum will quickly increase or decrease as a result of these simultaneous reactions [14,15]. The swell and shrink reactions are the rise and fall of water level caused by pressure changes.The swell and shrink reactions are in the opposite direction of the boiler's natural activity. ...
Rapid rise in the steam mass flow rate causes the increase in dynamic effects. The pressure disturbance in the boiler's upper drum cause mechanical effects. Drum level fluctuations cause interactions with the controls of boiler combustion. Interactions with the controls, resulting inefficient and dangerous operations. The dynamic effects in the "upper" drum of the boiler (mechanical's effects) are very complex problems and critical due to the pressure disturbance in the upper drum of the boiler. This work deals with an experimental investigation of the dynamic behavior of the boiler drum level system is reported from plant data (Al-Quds power plant) in Baghdad / Iraq under a particular condition of operating, and the mathematical equations of the boiler model variables explained and defined. The dynamic effects are investigated with increasing steam mass flow rate (10% and 20%) at the outlet of the boiler. The results showed that the rapid rise in the rate of steam mass flow causes the dynamic effects to increase (shrink and swell) by 15%, rates of evaporation and thus causes an increase in the volume of water inside the upper drum boiler that causes overheating in the tubes.
... When the pressure of the steam decreases, the level of the water in the drum increases causing the steam bubbles to expand, which is known as the swelling phenomenon. And if the pressure of the steam in the boiler drum increases, the level of the water decreases causing the steam bubbles to compress, which is termed as the shrinking phenomenon [5,6]. ...
... Mathematical models based on conservation laws have been developed and proposed to understand the dynamic behavior of the boiler system over the years. Most of these studies have focused on water-tube boilers [5][6][7][8][9] and relatively less work discuss the modeling of fire tube boilers [10][11][12][13]. A dynamic model of the fire-tube boiler comprising of numerous sub-models, each of which characterizes a different zone in the boiler, was proposed by Sorensen, K. in 2004 [14,15]. ...
... .9. CS 3000 provides a default Control Group builder CG0001. ...
A steam boiler is a sealed vessel designed for the purpose of generating steam pressure at a higher level than atmospheric pressure. “Harnessing” the steam raises the pressure and consequently the boiling temperature. This also increases the energy content of the resulting steam. Different boiler types can be differentiated either according to their design, method of combustion or type of fuel. Steam boilers are defined by their design, steam output and permissible operating pressure. Essentially, two designs are offered to generate high pressure steam with a higher output range: The water tube boiler and the flame tube/smoke tube boiler (also referred to as boiler with large water chamber). This designs conventionally used as a quick steam boiler up to approx 30 bar or as a water tube boiler up to approx 300 bar. The boiler control which is the most important part of any power plant, and its automation is the precise effort. In order to automate a power plant and minimize human intervention, there is a need to develop a DCS. This system controls and monitors the plant and helps to reduce human errors. © 2015, International Journal of Pharmacy and Technology. All rihgts reserved.
... Seu desempenho dinâmico determina a capacidade de regulação durante variações de demanda e, consequentemente, o desempenho dinâmico da caldeira (Åström, K. J. e Bell, R.(2000), Shinskey, F. G. (1988;1994), Khaisongkram, W. (2004).). Apesar de sua importância, não é raro encontrá-lo com problemas de estabilidade e oscilações persistentes (Shinskey, F. G. (1988), Iacob, M.;Andreescu, G.(2011)). Uma das razões é o fenômeno shrink-and-swell (têmpera/inchamento), responsável por uma resposta dinâmica com fase não-mínima, o que dificulta o controle. ...
... Seu desempenho dinâmico determina a capacidade de regulação durante variações de demanda e, consequentemente, o desempenho dinâmico da caldeira (Åström, K. J. e Bell, R.(2000), Shinskey, F. G. (1988;1994), Khaisongkram, W. (2004).). Apesar de sua importância, não é raro encontrá-lo com problemas de estabilidade e oscilações persistentes (Shinskey, F. G. (1988), Iacob, M.;Andreescu, G.(2011)). Uma das razões é o fenômeno shrink-and-swell (têmpera/inchamento), responsável por uma resposta dinâmica com fase não-mínima, o que dificulta o controle. ...
Control loop auditing of a boiler is illustrated with a detailed case study of performance and disturbances present in boiler control loops of a thermoelectric power plant. Non-minimum phase characteristic of boiler level control is explained and illustrated with experimental results. The auditing procedure is exemplified with the usage of principal component analysis to identify loop interactions, process relevant frequencies, and experimental tests used to estimate reduced order models for PI(D) controller tuning parameters and the impact of nonlinearities such as valve hysteresis. Experimental results illustrate the dynamical behaviour of the boiler, the procedures carried out in the plant auditing, proposed and implemented actions along with improvements obtained in performance and stability of the plant operation with the auditing scan of the boiler system.
The research paper provides details of the sultry dihydrogen monoxide heating system for power consumption such as aliment pump, victual pump motor, control valves etc; withal, details cognate to the test of the subsisting system power utilizing the 3-element mode method to control the drum level. Includes details about the sundry energy test equipment used during the potency test to quantify the sundry parameters such as flow, head, power haste, temperature and vibration. This study was conducted with the avail of 2 boiler and turbine engineers and 3 operators where there is an inch switch. During the study of the parameter sundry parameters were accumulated and designations were accumulated and the calculation was predicated on brake vigor and pressure disunion. In order to calculate it is consequential that one situation is sometimes engendered under the circumstances of each task. In cases of full volume, the drum pressure is customarily kg/cm2 above the maximum pressure. This denotes that when the total smoke load maximum pressure is ninety kg/cm2, then the corresponding drum pressure will be 100 kg/cm2. Ergo, while competitive calculations always engender the assurance that the pressure to aliment the victual in an economic rest area or aliment supply center is much more preponderant than the high pressure of the boiler drum suppleness for harmless operation.
The thermal power station uses some amount of their generated power to be consumed by its auxiliary power requirements. The auxiliary power consumption in the country is around 8-9%. The auxiliary power consumption can be minimize by increasing the load factor, by operational optimization, applying advanced control techniques and energy efficient measures. By decreasing the auxiliary power extra power will be available at grid. Thus, the aim of the audit is to determine the potential areas for minimizing auxiliary power consumption by operational optimization and energy management policy to improve energy efficiency of auxiliaries. This study will give the basic understanding of energy management approach, energy efficiency and energy saving areas so as to achieve maximum plant efficiency resulting fuel saving. Boiler feed pump is one of the equipment in a power plant with the highest auxiliary consumption. The research is specifically targeted at the feed water system and its potential for obtaining considerable energy and cost savings.
The Brazilian electrical energy matrix is based on renewable energies mainly on hydroelectric energy. As the country has experienced some energy crisis, it is necessary to find alternative sources of electric energy production that can help to keep the offer of the main energy source, especially during the dry season.
Biomass is a viable alternative fuel for the production of electricity, through generation power plants and cogeneration power plants. Among electricity production alternatives, we have the sugar and alcohol plants, which have a great energy production potential that which can be optimized through the best use of bagasse burning. This dissertation will study all the elements of energy cogeneration in sugarcane plants, by emphasizing bagasse and boiler, proposing an alternative to improve bagasse burning efficiency. This proposition will be proven through the use of flow meters and bagasse moisture, together with a logic controller that acts on the inputs of the energy cogeneration, which increase the efficiency of the mesh and reduce the wastage of the input variables.
All propositions will be simulated with data from a sugar and alcohol mill, so that it is possible to validate the model, and to prove the gains from using the controller.
Through this controller, it was verified that the plant burns more bagasse than necessary, reducing the efficiency of the boiler and disturbing the rest of the process.
In order to meet out the steam requirement, to safeguard the boiler water tubes and to safe guard the turbine blades the boiler drum water level control plays an important role in thermal power station. The main objective of the boiler–turbine system control is to meet the load demand of electric power while maintaining the pressure and water level in the drum within tolerances This paper demonstrates the increase in efficiency and energy savings by using the three element mode method of drum level control and compares it to the the traditional DP mode .Traditionally in most power stations , the DP mode of operation is used because it is believed it provides more robust control of the throttle valve , however throttling losses do occur .This is primarily because it is a linear system of control. The linear system of control causes more losses and hence greater power consumption. Three element mode reduces these throttling losses by measuring the steam level , steam rate flow as well as the water level simultaneously , thereby resulting in a lesser loss of pressure and hence lesser demand. Pressure drop across the throttle valve can be optimized more efficiently using this method of control and the observations and results regarding this have been discussed .The results found were very encouraging and the method can be applied widely to all sub critical boiler systems across the power industry .
This paper introduces an extension of the Internal Model Control algorithm for efficient disturbance rejection. The approach is based on ideas from model based predictive control and diophantine equation derivation. As an illustration of the power of the extension, an example from the process industry is borrowed, namely a drum boiler. The process is challenging for control since it has an integrator and non-minimum phase dynamics. The performance of the proposed extension is compared against nominal IMC design and PID. The simulation results suggest that the proposed algorithm outperforms the other implementations in terms of effective disturbance rejections.
