Conical Tank Research Articles

Seismic analysis of elevated pure conical tanks under vertical excitation

Truncated conical vessels are commonly used as liquid containers in elevated tanks. Despite the widespread use of this type of structure worldwide, no direct code provisions are currently available covering its seismic analysis and design. The purpose of the current study is to assess the importance of considering the vertical component of ground accelerations when analyzing and designing this type of water-storage structure. The study is conducted using an equivalent mechanical model that estimates the normal forces that develop in the tank walls when subjected to vertical excitation. In addition, a three-dimensional finite element model has been developed by modeling the walls of the tank using shell elements. The finite element model has been employed to predict maximum membrane and overall meridional stresses due to both hydrodynamic and hydrostatic pressure distributions. Comparisons have been conducted to assess the significance of considering vertical excitation and to identify the magnification in meridional stresses due to bending effects associated with support conditions and large deformations.

English

PID controller plays very important role in many process control industries. In this paper Ziegler- Nichols controller, Tyreus and Luyben controller, Cohen Coon controller are used to control the level of the conical tank. The controller is designed based on the mathematical model of the system. Non-linear variation is exigent in conical tank because of some of the awkwardness compared to linear system based on analysis, non-linear system is preferred by number of industries. For disposal of solid material non-linear is the system will be best supporter for controller used for conical tank. In this work, a non linear tank process is identified as first order plus dead time model and identified model is used for controller implementation. The closed loop response of process system is obtained using MATLAB simulink. Based upon obtained results and time domain specifications best tuning PID controller parameter is highlighted.

English

In process industries, the level of the liquid must be controlled and it is a mandatory process. But controlling a non-linear process is a highly complicated and complex process. Many process industries employs conical tank because of its non-linear shape, because of its constantly changing cross section, with respect to height controlling. For each operating region, the linear portion of the nonlinear process is determined as first order plus dead time model (FOPD). Different controller scheme such as conventional PID controllers based on Ziegler-Nicholas (ZN-PID) method, Chien, Hrones and Reswich (CHR-PID) method, Tyres-Luyben (T-L-PID) method, Internal Model Control (IMC-PID) and Model Predictive Controller (MPC) method were proposed and their responses was compared. The main objective of the controller is to provide a minimum settling time, peak overshoot and rise time and to provide a minimum performance error. Among the various controllers, Model Predictive Control (MPC) satisfies the above criteria. The controller will be simulated using MATLAB SIMULINK

Design of Neural Estimator for Non-Linear Interacting Process

Real processes often exhibit non-linear behavior; time variance and delay between input and output, having a vast amount of highly correlated data and this correlation need to be utilized in the design of estimator. In this work, an interacting non-linear (conical tank) is taken for study and a neural estimator is designed using Data driven approach. The neural network is developed in hardware on a customized Linux kernel and implemented using python language. The second order training algorithm is modified using a batch update strategy and this approach along with the hardware implementation reduces the estimator training period and makes it highly suited to online.

Structure of geometrical nonlinearities in problems of liquid sloshing in tanks of non-cylindrical shape

Structure of geometrical nonlinearities in mathematical model of liquid sloshing in tanks of non-cylindrical shape is under consideration. In contrast to the case of cylindrical reservoir, some new types of nonlinearities occur in mathematical statement of the problem. They are connected with four main reasons. First, they are determined by new normal modes, which correspond to non-cylindrical shape of the tank and take into account some nonlinear properties of the problem (for example, they follow tank walls above level of a free surface). Second, determination of the potential energy of the liquid includes tanks geometry in close vicinity of cross-section of undisturbed free surface of the liquid and tank walls. Third type of manifestation of geometrical nonlinearities is connected with compensation of elevation of liquid level due to non-cylindrical type of tank shape for providing law of mass conservation. The fourth type of nonlinearities is connected with simultaneous manifestation of physical and geometrical nonlinearities. Investigation showed that mostly manifestation of nonlinear properties of liquid sloshing, connected with geometrical nature, is predetermined by inclination and curvature of tank walls in close vicinity of contact of undisturbed liquid with tank walls. We illustrated some general properties of geometrical nonlinearities by the example of three cases of tanks, namely, cylindrical, conic, and paraboloidal tank, which is selected such that its walls have the same inclination near free surface of the liquid as conic tank, but in this case curvature is manifested supplementary.

Design and Implementation of Two-Degree-of-Freedom Nonlinear PID Controller for a Nonlinear Process

A Two-Degree-of-Freedom (2-DOF) Nonlinear PID (NPID) controller is designed for a conical tank level process. The process is modeled using black box identification method as a First Order Process with Dead Time (FOPDT) model. Two nonlinear first order tracking differentiators are designed for the nonlinear PID controller. The closed loop control is implemented for a wide operating range of the process with the designed controller. The implementation and simulation is carried out using Mat-lab Simulink software. The online implementation of proposed controller shows that 2-DOF NPID is better than 1-DOF NPID. Index Terms: Two-Degree-of-Freedom, First order process with dead time, Nonlinear PID, Nonlinear tracking differentiator I. Introduction A conical tank level process is a nonlinear process due to the conical shape of the tank. The change in area of the conical tank for equal rise in level is nonlinear. The nonlinear process is modeled as piecewise linear models at some operating points. This inherent nonlinear behavior of the processes makes control of such processes more complex. Presence of the nonlinearity in the plant often causes degraded performance of the overall process. A nonlinear PID controller is developed by defining a nonlinear function which gives the controller settings depending upon the calculated error and some tuning parameters (1)(2). A nonlinear function may contain number of parameters and values of those should be decided by the designer and it varies from plant to plant. When the process and the controller both exhibit nonlinear characters, a 2-DOF control scheme is considered to improve servo and regulatory problems (3). In the 2-DOF control scheme the closed loop transfer functions for servo and regulatory can be adjusted independently (4)(5)(6). In this work, the tuning of 2-DOF nonlinear PID controller is demonstrated to achieve stability and desired performance measures. This paper is organized such that first the design of the 2-DOF nonlinear PID control structure using the nonlinear tracking differentiators and secondly conical tank level process is described. Then the simulation study and online implementation of designed controller with actual process are shown. e when e e when e e sign e f p p p p p          

An Improved MRAC Scheme for Non-linear Design of Adaption Gain γ using Heuristic Algorithms

This paper presents an approach to Optimal Model Reference Adaptive Control (OMRAC) and comparative performance evaluation are analyzed for a conical tank process which exhibits behavior of a class of nonlinear dynamical system. The conventional Model Reference Adaptive Control (MRAC) method based on the MIT rule reported in the works (P. Swarnkar et al., 2010), has its difficulty in choosing the reference model and adaption gain γ. Inspired by the above work, the selection of reference models in MRAC scheme are based on the multiple models (MM) depending on the operating regime of the process. In this proposed work, the reference model considered is a second order system having fixed roots in denominator polynomial representing the most dominant poles in the process determined using Dominant Pole Algorithm (DPA). The numerator polynomial of the reference model is designated as static sensitivity from each linearized region of the process. The optimal adaption gain γ of MRAC is obtained by Bacterial Foraging based Particle Swarm Optimization (BFPSO) algorithm and the system performance is compared with traditional algorithms such as Bacterial Foraging Optimization (BFO) and Particle Swarm Optimization (PSO). The simulated result gives consistently better setpoint tracking mechanism and error minimization.

Assessment of current design procedures for conical tanks under seismic loading

This study is motivated by the fact that no design provisions currently exist specifically for conical tanks under seismic excitations. The design of liquid storage structures is governed by the American Water Works Association (AWWA), American Petroleum Institute (API), or Eurocode 8. An approximate method based on replacing the conical tank with an equivalent cylinder is given in these design codes. The state of stresses in conical tanks is different than that of cylindrical tanks. A previously established equivalent mechanical model is used to determine the response of a number of conical tanks under horizontal excitations. The models incorporate the different components of the hydrodynamic pressure and account for flexibility of the tank walls. Using an assortment of seismic hazard areas, the maximum base shear force and overturning moment are evaluated for a number of conical tanks. Those are compared to the corresponding values predicted by the design codes using the equivalent cylinder approach. The results reveal that this approximate approach is not adequate for designing conical tanks to resist seismic excitations.

A problem of propellant oscillations in cylindrical and conical tanks

A problem of propellant oscillations in cylindrical and conical tanks

Weakly nonlinear sloshing in a truncated circular conical tank

Sloshing of an ideal incompressible liquid in a rigid truncated (tapered) conical tank is considered when the tank performs small-magnitude oscillatory motions with the forcing frequency close to the lowest natural sloshing frequency. The multimodal method, the non-conformal mapping technique and the Moiseev type asymptotics are employed to derive a finite-dimensional system of weakly nonlinear ordinary differential (modal) equations. This modal system is a generalization of that by Gavrilyuk et al 2005 Fluid Dyn. Res. 37 399–429. Using the derived modal equations, we classify the resonant steady-state wave regimes occurring due to horizontal harmonic tank excitations. The frequency ranges are detected where the ‘planar’ and/or ‘swirling’ steady-state sloshing are stable as well as a range in which all steady-state wave regimes are not stable and irregular (chaotic) liquid motions occur is established. The results on the frequency ranges are qualitatively supported by experiments by Matta E 2002 PhD Thesis Politecnico di Torino, Torino.

Digestibilidad aparente de ingredientes de origen vegetal y animal en la cachama

El objetivo de esta investigación fue evaluar los coeficientes de digestibilidad aparente de materia seca (MS), proteína y energía de alimentos de origen animal y vegetal, utilizados en raciones para cachama (Piaractus brachypomus). Fueron formuladas 15 dietas experimentales, compuestas por 69,5% de una dieta referencia semipurificada, 0,5% de óxido de cromo y 30% del ingrediente a evaluar. En cada experimento, fueron utilizados 90 peces que se alimentaron durante cinco días con la correspondiente dieta; al quinto día, los animales fueron trasladados a tanques cónicos para recolección de heces. Los coeficientes de digestibilidad aparente (CDA) de proteína variaron de 92,1 a 84,7% entre los ingredientes proteicos de origen vegetal, de 85,0 a 68,5% en los proteicos de origen animal, y de 83,7 a 57,6% entre los de origen vegetal con baja proteína. Los CDA de energía de torta de soya, gluten de maíz, harina de yuca integral y de todos los ingredientes de origen animal arrojaron valores superiores a 76%. Los máximos CDA de MS variaron entre 71 y 78% y fueron observados en gluten, harina de yuca y en los ingredientes de origen animal. La cachama tiene alta capacidad para aprovechar eficientemente ingredientes de origen animal y vegetal.

Adaptive Control of a Non-Cylindrical Tank

A conical tank in which the diameter changes with the tank height, allows the use of feedback control used in complex nonlinear systems, such as adaptive control. This project modified an existing system of two interacting tanks by inserting a removable solid cone into one of the tanks. This modification created two new nonlinear configurations, one of which had a discontinuity. Optimal controller settings at different depths of liquid were found by minimizing the integral of the absolute error (IAE). These settings were used by an adaptive PID controller at a different settings, comparing the results to a conventional PID tuned to that setting.

Simulation based Modeling and Implementation of Adaptive Control Technique for Non Linear Process Tank

of nonlinear process is a complicated task in industrial environment. In this work, adaptive control technique is discussed in control of single conical tank level control system is a nonlinear system is identified mathematically. Analytical modeling were implemented and simulated in MATLAB SIMULINK and transfer function isobtain from the simulated response and PI controller parameter were derived for implementing gain scheduling adaptive controller and synthesis based method is used to obtain PI parameters for multiple linear models. The simulation studies were carried out for two controller parameters. From the results based on Performance indices like Integral Squared Error (ISE), it is proved the controller implemented using gain scheduling adaptive control technique out performs well over synthesis method based tuned multi PI controller.

Fuzzy scheduled RTDA controller design

In this paper, the design and development of fuzzy scheduled robustness, tracking, disturbance rejection and overall aggressiveness (RTDA) controller design for non-linear processes are discussed. pH process is highly non-linear and the design of good controller for this process is always a challenging one due to large gain variation. Fuzzy scheduled RTDA controller design based on normalized integral square error (N_ISE) performance criteria for pH neutralization process is developed. The applicability of the proposed controller is tested for other different non-linear processes like type I diabetic process and conical tank process. The servo and regulatory performance of fuzzy scheduled RTDA controller design is compared with well-tuned internal model control (IMC) and dynamic matrix control (DMC)-based control schemes.

Maintenance and Culture of Paralarval Longfin Squid (Doryteuthis(Loligo)Pealeii) in a Laboratory

A system and management protocol was developed that maintained large numbers of paralarval longfin squid in a laboratory for 18–44 days. The system included a 200-L conical tank, an inflow pipe with a 1-µm filter, an aeration ring, and a centered outflow standpipe with a 150-µm mesh outflow filter. Cleaning and maintenance protocols involved siphoning tanks, periodic partial draining, and transfer of squid from a used tank to a clean tank. Paralarval squid were fed brine shrimp and commercial rations, which they ingested. Squid survived and grew in the system until catastrophic disruptions terminated the experiments prematurely. With suitable backups and refinement, the system design, management protocol, and feeding regime used provide a starting point to increase squid utility for research and commercial production.

Development of genetic algorithm-based fuzzy logic controller for conical tank process

The proportional integral derivative controllers are widely used in industries for controlling the different process variables due to its simplicity, flexibility and efficiency. Recently, the control of non-linear processes in the industries have turned the attention towards the intelligent controllers such as neural networks, fuzzy logic controller (FLC), genetic algorithm-(GA) tuned controllers, adaptive controller, predictive controller, robust controller, etc. This work focuses on developing a GA-based FLC for conical tank. A conical tank is a highly non-linear process due to the variation in the area of cross section of the level system with change in shape. Conventionally, a parameter adaptive proportional integral (PI) controller has been designed for non-linear process. Alternatively, in this work, an intelligent controller (GA-based FLC) is designed for the control of non-linear process to ensure the exact level control. The experimental results are obtained for servo and regulatory response of the process. The GA-based FLC is compared with adaptive PI controller.

Estimation of evaporative losses during storage of crude oil and petroleum products

Storage of crude oil and petroleum products inevitably leads to evaporative losses. Those losses are important for the industrial plants mass balances, as well as for the environmental protection. In this paper, estimation of evaporative losses was performed using software program TANKS 409d which was developed by the Agency for Environmental Protection of the United States - US EPA. Emissions were estimated for the following types of storage tanks: fixed conical roof tank, fixed dome roof tank, external floating roof tank, internal floating roof tank and domed external floating roof tank. Obtained results show quantities of evaporated losses per tone of stored liquid. Crude oil fixed roof storage tank losses are cca 0.5 kg per tone of crude oil. For floating roof, crude oil losses are 0.001 kg/t. Fuel oil (diesel fuel and heating oil) have the smallest evaporation losses, which are in order of magnitude 10-3 kg/tone. Liquids with higher Reid Vapour Pressure have very high evaporative losses for tanks with fixed roof, up to 2.07 kg/tone. In case of external floating roof tank, losses are 0.32 kg/tone. The smallest losses are for internal floating roof tank and domed external floating roof tank: 0.072 and 0.044, respectively. Finally, it can be concluded that the liquid with low volatility of low BTEX amount can be stored in tanks with fixed roof. In this case, the prevailing economic aspect, because the total amount of evaporative loss does not significantly affect the environment. On the other hand, storage of volatile derivatives with high levels of BTEX is not justified from the economic point of view or from the standpoint of the environment protection.

Azaspiracid accumulation, detoxification and biotransformation in blue mussels (Mytilus edulis) experimentally fed Azadinium spinosum

Azadinium spinosum (Elbrächter and Tillmann), a small marine dinoflagellate, has been recently described as a de novo producer of azaspiracid-1 and -2 (AZA1 and -2) diarrhoeic toxins. A culture of A. spinosum was established in our laboratory and optimised for pilot-scale production of this organism, to evaluate and understand AZA1 and -2 accumulation and biotransformation in blue mussels (Mytilus edulis) fed with A. spinosum.Adult mussels were continuously exposed to A. spinosum over 1 week in 160 L cylindrical conical tanks. Three different diets were tested for contamination: 5000, 10 000 cells mL−1 of A. spinosum and a mixture of 5000 cells mL−1 of A. spinosum with 5000 cells mL−1 of Isochrysis aff. galbana (T-Iso, CCAP 927/14). During the subsequent period of detoxification (2 weeks), contaminated mussels were continuously fed with 5000 cells mL−1 of T-Iso. Kinetics of accumulation, detoxification and biotransformation were evaluated, as well as the toxin distribution and the effect of A. spinosum on mussel digestive gland tubules.M. edulis fed on A. spinosum in the three tested conditions; this finding confirmed our recent experiments feeding A. spinosum to mussels. The original algal toxins AZA1 and -2, as well as mussel metabolites AZA3 to 12, -17, -19, -21 and -23 were found during these trials. After as little as 6 h, azaspiracid contents in mussels reached the EU regulatory limit, and metabolites were observed in all conditions at approximately 25% of the total AZA content. This fraction exceeded 50% after 24 h, and continued to increase until the end of the study. AZA17 and -19 were found to be the main metabolites, with AZA17 concentrations estimated in the same order of magnitude as that of the main algal toxin, AZA1.

Multimodal method for linear liquid sloshing in a rigid tapered conical tank

PurposeThe purpose of this paper is to derive linear modal equations describing the forced liquid sloshing in a rigid truncated (tapered) conical tank, as well as to show how to couple these modal equations with “global” dynamic equations of a complex mechanical system carrying this tank.Design/methodology/approachDerivation of the modal equations can be based on the Trefftz variational method developed by the authors in a previous paper. Describing the coupled dynamics utilizes Lukovsky' formulas for the resulting hydrodynamic force and moment due to liquid sloshing.FindingsThe so‐called Stokes‐Joukowski potentials can be found by using the Trefftz method from the authors' previous paper with the same polynomial‐type functional basis. Coupling the modal equations with the global dynamic equations becomes a relatively simple task facilitated by Lukovsky's formulas. Using the linear multimodal method can be an efficient alternative to traditional numerical and analytical tools employed for studying the coupled vibrations of a tower with a conical rigid tank on the tower top.Practical implicationsThe derived modal equations are equipped by tables with the computed non‐dimensional hydrodynamic coefficients. Interested readers (engineers) can incorporate the modal equations into the global dynamic equations of a whole mechanical system without new computations of these coefficients.Originality/valueThe multimodal method can be an alternative to traditional numerical tools. Using the derived modal equations simplifies analytical studies and provides efficient calculations of the coupled dynamics of a mechanical system carrying a rigid tapered conical tank with a liquid.

Design of Neural Based PID Controller For Nonlinear Process

In this paper, a neural network (NN) based internal model control (IMC) -PID controller is proposed for a non–linear process. The controller structure has been outlined and its performance is demonstrated on a conical tank process. The control of liquid level in a conical tank is nonlinear due to the variation in the area of cross section of the tank system with its change in shape. The model of the process is identified using standard step response based system identification technique and it is approximated to be first order plus dead time (FOPDT) model. From the results it is observed that fuzzy controller shows much better integral absolute error (IAE) and integral squared error (ISE) performance criteria than the conventional controller.