Modeliranje in vodenje sistema za pripravo zraka v procesu zmanjševanja emisij NOx

ŠINK, ALEŠ (author), Mušič, Gašper (mentor)

Magistrsko delo predstavi rešitve za zmanjševanje škodljivih emisij v industriji in prometu. Prikazan je sistem, ki zmanjšuje emisije dušikovih oksidov (NOx) v odpadnem zraku iz peči in sušilnikov v tovarni avtomobilskih katalitičnih pretvornikov. Odpadni zrak iz sušilnikov in peči vsebuje emisije NOx, ki jih je potrebno zmanjšati pred izpustom v ozračje. Za to skrbi čistilna naprava, ki efektivno deluje v naprej določenem temperaturnem območju in z vnaprej določenim pretokom odpadnega zraka. Zaradi naštetih pogojev je potrebno odpadni zrak iz peči in sušilnikov predhodno pripraviti z ustreznim vodenjem loput za dovod svežega in odpadnega zraka ter z vodenjem hitrosti vrtenja motorja ventilatorja. Hkrati je potrebno paziti, da so obratovalni pogoji v sušilnikih in pečeh še vedno v zahtevanih mejah, saj delovanje izven zahtevanih meja pomeni slabšo kvaliteto izdelka ali v skrajnem primeru tudi zaustavitev proizvodnje. Podana je analiza delovanja sistema samodejnega vodenja procesa, ki jo je predlagal naročnik. Ker menimo, da predlagani način, ni optimalen, je v drugem delu magistrskega dela podan predlog izboljšanja sistema samodejnega vodenja sistema priprave odpadnega zraka. Za namen načrtovanja izboljšanega sistema samodejnega vodenja je sistem priprave odpadnega zraka iz peči in sušilnikov podan v obliki matematičnih modelov. Le-te smo določili z uporabo identifikacijske metode, ki za modelno strukturo uporablja mehko logiko tipa Takagi-Sugeno. Podana je tudi razlaga osnovnih pojmov mehke logike. V zadnjem delu je prikazana uporabnost pridobljenih mehkih modelov na primeru vodenja z proporcionalno integrirnimi regulatorji (PI), ki so jim dodane mrtve cone na pogrešku in regulirni veličini. Dodano je tudi filtriranje procesnih signalov in nadzorna logika sistema vodenja, tako da je sistem vodenja pripravljen za implementacijo na realnem sistemu. Sistem vodenja in nadzorna logika sta načrtovana konceptualno in preizkušena s simulacijo. Namen je prikazati, da obstajajo poleg naročnikovega predloga tudi druge in boljše rešitve. Pri izvedbi predlagane rešitve na realnem sistemu bi bilo potrebno prilagajanje parametrov regulatorjev in nastavitev nadzorne logike.

• Language: Slovenian
• Keywords: katalitični pretvornik, zmanjševanje emisij, NOx, selektivna katalitična redukcija, mehka logika, identifikacija, mehki model Takagi-Sugeno, regulacija, regulatorji PI, nadzorna logika
• Work type: Master's thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2016
• PID: 20.500.12556/RUL-80634
• Publication date in RUL: 25.02.2016

Secondary language

• Language: English
• Title: Modelling and control of air preparation system in the process of NOx emission reduction

Abstract

The thesis introduces possible solutions for reducing harmful emissions produced in the industry and transport sectors. The thesis describes the system for reducing nitrogen oxides (NOx) emissions in exhaust air, which comes from the dryers and ovens in a factory of automotive catalytic converters. The exhaust air from the dryers and ovens contains NOx emissions, which must be reduced before the air can be released in to the atmosphere. The system for NOx emissions reduction efficiently operates only in predetermined temperature and air flow ranges of the exhaust air. Due to those conditions, exhaust air from the dryers and ovens must be prepared in advance by controlling the fan speed and fresh and exhaust air dampers positions. At the same time must be ensured that operating conditions in the dryers and ovens are within defined ranges. Operation outside of the defined ranges can result in lower product quality or even in the production shutdown. In the second part of the thesis, a control system analysis of the exhaust air preparation proposed by the costumer is given. We think the proposed control system is not optimal and could be improved. An example of improved control system of the exhaust air preparation is given. To design the improved control system, mathematical models must have been obtained. The exhaust air preparation process was identified using identification method, with help of Takagi-Sugeno type fuzzy logic. Brief description of the fuzzy logic is also presented. In the last part of the thesis, obtained fuzzy models are used to demonstrate the improved control system for the exhaust air preparation. The control system uses proportional-integral (PI) controllers with added dead zones on error signals and manipulated values. Process value signals filtering and the supervisory logic of the control system are also added to ensure the correct operation of the control system. The control system and the supervisory logic are designed as the concept and are tested with simulation. The purpose of the thesis is to show that better and more optimal control systems can be used for the exhaust air preparation control in comparison with the solution proposed by the costumer. With minor changes of the controller parameters and supervisory logic settings, presented control system can be ready for the implementation on the real process.

• Keywords: catalytic converter, emission reduction, NOx, selective catalytic reduction, fuzzy logic, identification, Takagi-Sugeno fuzzy model, control, PI controllers, supervisory logic