Jayesh Barve

Boiler model and simulation for control design and validation

Abstract A plant validated boiler simulator is a very useful tool for controls design, analysis and performing experiments because of the cost involved in doing experiments on a real boiler or even lab-boiler. This paper presents the dynamic model simulator of a typical power-plant boiler derived based on the first principles and a hybrid approach of suitably combining lumped and distributed modeling approach for the relevant subsystems. The developed model simulator is validated using an actual plant-data covering the dynamic plant startup scenario. The plant-data of steam flow-rate, feed-water flow-rate, feed water temperature, and heat input defines the boundary condition of the plant startup, and the model-simulated response of the drum-level and pressure are compared with the actual plant-data of boiler drum-level and pressure. The validation results are very encouraging considering the challenges posed by complex behavior and uncertainties in the actual power-plant boiler-drum, and the measurement inaccuracies in the industrial plant conditions.

Cold-Tip Temperature Control of Space-borne Satellite Stirling Cryocooler: Mathematical Modeling and Control Investigation

IR (Infra-Red) detectors are widely used in Space-borne remote sensing satellites. In order to achieve a high signal to noise ratio, the IR detectors need to be operated at cryogenic temperatures. Traditionally, the cryogenic cooling of these detectors is achieved using passive cooling techniques. However recent trend is to employ Stirling-cycle based miniaturized active cryocoolers. An accurate and stringent control of active cryocooler cold-tip temperature is essential to accomplish high signal & image quality from the IR detectors. This paper presents work on investigations and comparison of performance of proposed 2-DOF (2-Degrees-of-Freedom) versus traditional 1-DOF feedback-control structures for the control of cryocooler cold-tip temperature used in IR (Infra-Red) detectors of Space Satellites. Towards this, first-principle based control oriented mathematical model simulated in Matlab/Simulink is proposed to support such investigation and controller tuning. Open-loop (system) and closed-loop (controls) simulation results are tuned & validated with the experimental data obtained from the Lab-scale test-setup of a commercial Stirlingcryocooler. The performance of 2-DOF feedback control structures are analyzed with the help of experiment results offering a better cold-tip temperature control performance.

Temperature profile modelling, simulation and validation for a counter flow water tube in tube heat exchanger

The present work gives an insight and visualization of temperature gradient behavior along the length of a cross flow water tube in tube heat exchanger with mathematical modelling. Various process operational disturbance is given to understand the steady state and dynamic behavior. Discrete modelling is done by considering number of zones along the length of heat exchanger for the study of temperature profile. Simulation is carried out in MATLAB/SIMULINK and validation is done using CFD (Computational Fluid Dynamics) with Gambit/Fluent for steady state and dynamic analysis of temperature gradient under same condition. Control strategy is also developed with PID in MATLAB/SIMULINK to maintain the Cold fluid outlet temperature which is validated with practical results with marginal difference.

Modeling and identification of experimental drum type steam boiler

Developing mathematical model for a process is an important and integral step in control system design process. Mathematical models can be developed from fundamental physical laws (white-box approach), by performing experiments (black-box approach) or a combination of both (gray-box approach). This paper presents a black-box system identification of a laboratory boiler. A mathematical MIMO model matrix which describes the dynamic behavior of the drum level and drum pressure of lab-boiler setup with respect to steam and feed water as manipulated variables is presented. A complete system identification of lab-boiler setup, designed by these researchers, has been carried out based on the design-of-experiments (DoE) and validated model with the field measurements. In this paper, the identified boiler-model is characterized in the form of 2×2 process transfer function model matrix structure. This 2×2 model matrix defines the dynamics describing the effect of changes in the feed-water flow rate and steam-flow rate, on the boiler drum-level and drum-pressure. This model can be used to study various classical and advanced control-design and analysis through this lab boiler setup.