scholarly journals On line diagnostics and self-tuning method for the fluidized bed temperature controller

2016 ◽  
Vol 37 (1) ◽  
pp. 31-46
Author(s):  
Jan Porzuczek
Keyword(s):  
Fluidized Bed ◽  
Experimental Verification ◽  
Experimental Studies ◽  
Statistical Process ◽  
Temperature Controller ◽  
Tuning Method ◽  
Bed Temperature ◽  
Bubbling Fluidized Bed ◽  
Self Tuning ◽  
On Line

Abstract The paper presents the method of on-line diagnostics of the bed temperature controller for the fluidized bed boiler. Proposed solution is based on the methods of statistical process control. Detected decrease of the bed temperature control quality is used to activate the controller self-tuning procedure. The algorithm that provides optimal tuning of the bed temperature controller is also proposed. The results of experimental verification of the presented method is attached. Experimental studies were carried out using the 2 MW bubbling fluidized bed boiler.

Co-Firing of Steam Coal With High Sulfur Content Lignite in a Bubbling Fluidized Bed Combustor

2005 ◽  
Author(s):  
Nevin Selc¸uk ◽  
Yusuf Gogebakan ◽  
Hakan Altindag
Keyword(s):  
Fluidized Bed ◽  
Molar Ratio ◽  
So2 Emissions ◽  
Molar Ratios ◽  
High Sulfur Content ◽  
Bubbling Fluidized Bed ◽  
On Line ◽  
Emission Behavior ◽  
Nitrogen Contents ◽  
Fluidized Bed Combustor

Combustion and emission behavior of 100 % steam coal (SET 1) and a mixture of 80 % by weight steam coal and 20 % by weight local lignite, characterized by high sulfur and ash contents, (SET 2) were investigated in the 0.3 MWt Middle East Technical University (METU) Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) Test Rig. Experiments were performed with limestone addition at various Ca/S molar ratios with fines recycle. In both sets of experiments, parameters other than Ca/S molar ratio were held as nearly constant as possible. On-line measurements of O2, CO2, CO, SO2, NOx emissions were carried out. Comparisons between the emissions show that lower NOx and SO2 emissions are obtained from combustion of steam coal/lignite mixture compared to those from steam coal only despite higher sulfur and almost equal nitrogen contents of the mixture. Calculated combustion efficiencies were found to be around 98 and 96 % for SET 1 and SET 2, respectively. As for the sulfur retention efficiencies, up to three times higher efficiencies were achieved when steam coal is co-fired with high sulfur lignite.

An Experimental Study of the Gaseous Pollution Emissions in Petroleum-Coke-Fired Fluidized Beds

2003 ◽  
Author(s):  
Chun-Lin Zhang ◽  
Gui-Cheng Yuan ◽  
De-Chang Liu ◽  
Han-Ping Chen ◽  
Ding-Yu Liu ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Petroleum Coke ◽  
Calorific Value ◽  
Excess Oxygen ◽  
N2o Emissions ◽  
Bed Temperature ◽  
High Sulfur Content ◽  
Bubbling Fluidized Bed ◽  
Pollution Emissions ◽  
Gaseous Pollution

Petroleum cokes have high calorific value (about 37 MJkg−1), high sulfur content (2–7% wt.), and high nitrogen content (1∼3% wt.), introducing serious environmental problems when using as fuel. In this paper the effects of operating parameters (bed temperature, Ca/S mole ratio, and excess oxygen) on gaseous pollutant (SO2, NO, and N2O) emissions in a well-controlled bench scale fluidized bed reactor and an 1t/h bubbling fluidized bed for different type of petroleum cokes. Finally, the pollution emission differences between petroleum coke and coal were compared and the reasons were analyzed.

scholarly journals NOx EMISSIONS FROM BUBBLING FLUIDIZED BED COMBUSTION OF LIGNITE COAL

2015 ◽  
Vol 55 (4) ◽  
pp. 275 ◽  
Author(s):  
Pavel Skopec ◽  
Jan Hrdlička ◽  
Jan Opatřil ◽  
Jiří Štefanica
Keyword(s):  
Nitrogen Content ◽  
Fluidized Bed ◽  
Oxygen Concentration ◽  
Brown Coal ◽  
Conversion Factor ◽  
Nox Emissions ◽  
Fluidization Velocity ◽  
Bed Temperature ◽  
Bubbling Fluidized Bed ◽  
Air Staging

This paper presents experimental results of NO<sub>x</sub> emission measurements for combustion of two kinds of coal in a bubbling fluidized bed combustor. The tested fuels were Czech brown coal (CBC) and German young brown coal (GYC). These fuels have different nitrogen contents. The experiments were performed in the pilot scale BFB experimental unit with power output of 500 kW. The influence of several parameters on NO<sub>x</sub> formation are investigated in this paper. The parameters studied here include the effect of the nitrogen content in the fuel, the effect of the oxygen concentration in the bed, the effect of bed temperature, the effect of air staging, and the effect of fluidization velocity. Significantly different behaviour of the fuels was found. Although GYC has a lower nitrogen content than CBC, it is more reactive and produces higher NO<sub>x</sub> emissions. The biggest dependence of NO<sub>x</sub> production for CBC was found for the effects of air staging and fluidization velocity. As the fluidization velocity increases and the amount of secondary air decreases, there is an increase in NOx emissions. The oxygen concentration in the bed has the strongest effect on the NO<sub>x</sub> production of GYCs. With increasing oxygen concentration, the production of NO<sub>x</sub> also increases. On the basis of the NO<sub>x</sub> measurements, the N-NO conversion factor was calculated and the effect of the operating parameters on this conversion factor was investigated.

Effect of the Shape of the Baffles on the Hydrodynamics of a Fluidized Bed

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Srinivasa Rao Venkata Naga Kaza
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Gas Flow ◽  
Experimental Studies ◽  
Expansion Ratio ◽  
Blockage Ratio ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Bubbling Fluidized Bed

Gas flow in a gas–solid fluidized bed is characterized by the predominance of bubbles. When gas flow is more than the minimum fluidization velocity, the top of the fluidized bed may fluctuate vigorously leading to unstable operation. Bed fluctuation and fluidization quality are interrelated. The quality of fluidization can largely be improved by introducing baffles in bubbling and turbulent fluidized beds. In the present work three baffle geometries, i.e., circular, triangular and square are used to determine different hydrodynamic parameters such as minimum fluidization velocity, bed expansion, pressure drop across the bed, fluctuation ratio, expansion ratio, etc. in a bubbling fluidized bed. A new parameter blockage ratio is introduced to analyze the behaviour of baffled fluidized beds. It is found from the current experimental studies that the blockage ratio mainly influences the hydrodynamics of the bed rather than the shape of the baffle.

On-line relay test for automatic tuning of PI controllers for stable processes

2011 ◽  
Vol 34 (7) ◽  
pp. 903-913 ◽  
Author(s):  
Utkal Mehta ◽  
Somanath Majhi
Keyword(s):  
Design Method ◽  
Experimental Studies ◽  
Automatic Tuning ◽  
Time Model ◽  
Loop Control ◽  
First Order ◽  
Tuning Method ◽  
Process Dynamics ◽  
Pi Controllers ◽  
On Line

The applicability of the basic relay tuning method is extended by a robust on-line method to tune proportional–integral controllers without breaking the closed-loop control. A relay is connected in parallel to the controller to induce self-oscillation and then simple measurements are made only on the half period of limit cycle output to obtain a first-order plus dead time model of the process dynamics. A non-iterative optimum tuning formulae is developed in order to reduce the control signal variations. The simulation and experimental studies are presented to validate the design method.

High Temperature Fluidized Bed Reactor Kinetics With Sintering Inhibitors for Iron Oxidation

2011 ◽  
Author(s):  
F. Al-Raqom ◽  
J. F. Klausner ◽  
D. Hahn ◽  
J. Petrasch ◽  
S. A. Sherif
Keyword(s):  
Particle Size ◽  
Reaction Kinetics ◽  
Fluidized Bed ◽  
Iron Powder ◽  
Experimental Studies ◽  
Fluidized Bed Reactor ◽  
Hydrogen Yield ◽  
Silica Powder ◽  
Powder Bed ◽  
Bed Temperature

High purity hydrogen is produced through a thermochemical water splitting process that utilizes iron reduction-oxidation (redox) reactions. An iron powder bed is fluidized to improve heat and mass transfer thus improving the reaction kinetics. Inert additives which act as sintering inhibitors, such as silica (SiO2) and zirconia (ZrO2), are added to the iron powder, and their effectiveness in inhibiting sintering in the oxidation step is evaluated. The influence of particle size, composition, mass fraction and bed temperature on reaction kinetics is investigated. Incorporation of zirconia in the powder bed is done by mixing it with iron powder or by coating the iron particles with a mixture of 1–3 μm and 44 μm zirconia particles. Two different batches of silica are used for blending with iron powder. The silica powder batches include particle diameters ranging from 0–45 μm and 200–300 μm. The mixing ratios of silica to iron are 0.33, 0.5, 0.67 and 0.75 by apparent volume. Experimental studies are conducted in a bench scale experimental fluidized bed reactor at bed temperatures of 450, 550, 650, 750 and 850 °C. It is verified that increasing the bed temperature and the steam residence time increases the hydrogen yield. Increasing the iron particle size reduces the specific surface area and reduces the hydrogen yield. It has been found that sintering can be completely inhibited by mixing iron with 0–45 μm silica powder and maintaining the reaction temperature below 650 °C.

Fuzzy Self-Tuning PID Controller for Pressure Control in VCM

2014 ◽  
Vol 620 ◽  
pp. 598-604
Author(s):  
Yuan Yuan Liu ◽  
Fu Ping Wan ◽  
Hai Guang Zhang ◽  
Zhuang Ya Zhang ◽  
Qing Xi Hu
Keyword(s):  
Casting Process ◽  
Pressure Profile ◽  
Pressure Control ◽  
High Quality ◽  
Vacuum Casting ◽  
Tuning Method ◽  
Pressure Tuning ◽  
Pressure Control System ◽  
Self Tuning ◽  
On Line

Owing to nonlinearity, time-delay and complexity of pressure control system in vacuum casting (VC) process, the traditional pressure tuning method can’t guarantee the good performance and thus high quality product nowadays. In this paper, a novel pressure control strategy for vacuum casting process, combining fuzzy PID and neural network methods, is proposed to solve this problem. The proposed strategy can on-line regulate pressure difference between low and upper chambers of VCM to meet the pressure requirement in VC process, thus ensuring high quality part. With the aid of Matlab and configuration software – Forcecontrol, the proposed fuzzy self-tuning controller is implemented in a sample machine. The experiment result shows that the presented pressure controller can track the pressure profile accurately and thus can further improve the product quality.

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