Nonlinear controller design from Plant data

Ph.DDOCTOR OF PHILOSOPH

Control of particle circulation rate in circulating fluidized bed by a pulsed gas flow

As a coal-fired power generation technology for further improvement of power generation efficiency of coal-fired power generation, exergy regeneration type coal gasification power generation technology (1), a triple-bed circulating fluidized bed (2), has been proposed. The authors analyzed the flow characteristics of the triple-bed circulating fluidized bed, it has the flow characteristics of the riser and downer perform the proposed approach to representation by the equivalent circuit model. The equivalent circuit model of the riser and downer are shown in Figure 1. This equivalent circuit has the nature of the low-pass filter. A combination of the low-pass filter and the pulse voltage is used as a switching power supply. Then, we applied that the pulsed gas supply to the riser combined with a low-pass filter characteristics to control the particle circulation rate of the triple-bed circulating fluidized bed. Figure 2 shows the input output characteristics of the equivalent circuit of the riser/downer inputting a pulse voltage. We used an electric circuit simulator SPICE to calculation of circuit behavior. Circuit constant is to use the value of the reference 3, the input pulse height is set to 80V. When the input pulse width is changed, the output current is changed depending on the pulse width. Moreover, when changing the density of the pulse, the output current is changing depending on the pulse density. This result by giving a pulsed gas supply to the riser, it shows the possibility controlling the particle circulation rate of the triple-bed circulating fluidized bed. Please click Additional Files below to see the full abstract

Investigation of agglomerates growth mechanism for thermal seawater desalination

Desalination technology has been paid large attention because water demand has been increasing due to the industrial development and high growth rate of population. To develop a novel desalination process with high energy efficiency and with high recovery ratio, a self-heat recuperative seawater desalination process using a fluidized-bed evaporator has been proposed (1). The fluidized-bed evaporator was employed to prevent scale deposition on the heat transfer surface during seawater evaporation. The seawater evaporation experiment using a lab-scale fluidized bed showed that the proposed evaporator prevents scale deposition on the heat transfer surface (2). However, it was also found that the seawater feed into the bed causes agglomeration of fluidized particles, which has the possibility to cause defluidization. In this research, seawater evaporation experiments using the lab-scale fluidized-bed evaporator were conducted and the influence of operating conditions such as fluidizing gas velocity, seawater feed rate and bed temperature on the agglomeration behavior of fluidized particles was examined. Furthermore, the mechanism of agglomerates growth was investigated and the optimal operating conditions of the fluidized bed for thermal desalination were examined. REFERENCES H. Mizuno, Y. Kansha, M. Ishizuka and A. Tsutsumi. A Novel Thermal Desalination Process Using Fluidized Bed. Chem. Eng. Trans., 39: 181-186, 2014 H. Mizuno, Y. Kansha, M. Ishizuka and A. Tsutsumi. Agglomeration behavior in fluidized-bed evaporator for thermal seawater desalination. Appl. Therm. Eng., 89: 1096-1103, 2015

An overview of biomass thermochemical conversion technologies in Malaysia

The rising pressure on both cleaner production and sustainable development have been the main driving force that pushes mankind to seek for alternative greener and sustainable feedstocks for chemical and energy production. The biomass ‘waste-to-wealth’ concept which convert low value biomass into value-added products which contain high economic potential, have attracted the attentions from both academicians and industry players. With a tropical climate, Malaysia has a rich agricultural sector and dense tropical rainforest, giving rise to abundance of biomass which most of them are underutilized. Hence, the biomass ‘waste-to-wealth’ conversion through various thermochemical conversion technologies and the prospective challenges towards commercialization in Malaysia are reviewed in this paper. In this paper, a critical review about the maturity status of the four most promising thermochemical conversion routes in Malaysia (i.e. gasification, pyrolysis, liquefaction and hydroprocessing) is given. The current development of thermochemical conversion technologies for biomass conversion in Malaysia is also reviewed and benchmarked against global progress. Besides, the core technical challenges in commercializing these green technologies are highlighted as well. Lastly, the future outlook for successful commercialization of these technologies in Malaysia is included

Simulation of the Steam Gasification of Japanese Waste Wood in an Indirectly Heated Downdraft Reactor Using PRO/II™: Numerical Comparison of Stoichiometric and Kinetic Models

The conversion of biomass to olefin by employing gasification has recently gained the attention of the petrochemical sector, and syngas composition is a keystone during the evaluation of process design. Process simulation software is a preferred evaluation tool that employs stoichiometric and kinetic approaches. Despite the available literature, the estimation errors of these simulation methods have scarcely been contrasted. This study compares the errors of stoichiometric and kinetic models by simulating a downdraft steam gasifier in PRO/II. The quantitative examination identifies the model that best predicts the composition of products for the gasification of Japanese wood waste. The simulation adopts reaction mechanisms, flowsheet topology, reactions parameters, and component properties reported in the literature. The results of previous studies are used to validate the models in a comparison of the syngas composition and yield of products. The models are used to reproduce gasification at temperatures of 600∼900 °C and steam-to-biomass mass ratios of 0∼4. Both models reproduce experimental results more accurately for changes in the steam-to-biomass mass ratio than for temperature variations. The kinetic model is more accurate for predicting composition and yields, having global errors of 3.91%-mol/mol and 8.16%-g/gBM, respectively, whereas the simple stoichiometric model has an error of 7.96%-mol/mol and 16.21%-g/gBM

Koprodukcija bioetanola i električne energije

The concept of co-production of energy and products has recently been developed in order to consider the energy and production system from the point of view of improving energy conversion efficiency and saving energy. The authors have developed self-heat recuperation technology to optimize the energy of individual processes and realize co-production for energy saving. In this technology, process stream heat is recuperated and recirculated into the process using heat exchangers and compressors, leading to marked reductions in the process energy required. In this paper, the feasibility of co-production of bioethanol and power by integration of self-heat recuperative processes and biomass gasification for power generation is examined and the relationship between production energy and biomass components is discussed using the energy balance calculation.Nedavno je razvijen koncept koprodukcije energije i proizvoda u cilju unapređenja efikasnosti pretvorbe energije i ostvarivanja energetskih ušteda, uzimajući u obzir energiju i sustav proizvodnje. Autori su razvili tehnologiju povrata topline za optimizaciju pojedinih procesa i ostvarenje energetske uštede koprodukcijom. U ovoj tehnologiji, toplinski tok se vraća i reciklira u procesu putem izmjenjivača i kompresora, što vodi do značajnog smanjenja potrebne energije u procesu. U ovom radu ispituje se izvedivost koprodukcije bioetanola i električne energije integrirajući proces povrata topline i rasplinjavanja biomase za proizvodnju energije, a veza između proizvodnje energije i komponenata biomase objašnjena je koristeći proračun energetske bilance