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Operational determinants of gaseous air pollutants emissions from coal-fired district heating sources

Zwierzchowski Ryszard, Różycka-Wrońska Ewelina

Archives of Environmental Protection

2021

Vol. 47, no. 3

108--119

This study describes the correlation between emission of gaseous pollutants to the atmosphere and the combustion parameters of a coal-fired 25 MW heating capacity water boiler with mechanical grate (boiler type WR-25) in unstable working conditions: start-up, shutdown and loads below the technical minimum. Whereas measurements were made for a specific type and size of coal-fired water boiler with mechanical grate, the measurements and calculations are applicable to WR boilers with a different heating power as well as OR type steam boilers, which have a practically identical design. In sum, there are more than 1,000 coal-fired water and steam boilers of these types in Poland. In addition, the analysis reported in this paper highlights the important role played by boilers operating in unstable conditions in terms of emission of gaseous pollutants to the atmosphere. The conclusions are relevant for other boilers fi red with gas, oil or biomass operating under conditions such as start-up, shutdown and loads below the technical minimum. This article fi lls a gap in air protection engineering practice and the literature with regard to indicators and emission standards, drawing on measurements of pollutant concentrations in the exhaust gases from unstable WR boiler working conditions. The measurements can be used to assess the emission of pollutants to the atmosphere in such boiler working conditions and their impact on air quality. The analyses presented were based on the authors’ own measurements in WR-25 boiler technical installations using portable gas analyser GASMET DX-4000, which uses the FT-IR measurement method for compounds such as SO2, NOx, HCl, HF, NH3, CH4, and CO. Concentrations of CO, NOx and SO2 in exhaust gases were determined with multiple regression with the STATISTICA statistical software and with linear regression complemented by the “smart” package in the MATLAB environment. The study provides computational models to identify pollutant concentrations in the exhaust gases in any working conditions of WR-25 boilers.

Prezentowana praca badawcza opisuje korelację między emisją gazowych zanieczyszczeń powietrza do atmosfery, a parametrami spalania dla wodnego kotła rusztowego opalanego węglem typu WR-25, o mocy cieplnej 25 MW w niestabilnych warunkach pracy, takich jak: rozruch, odstawianie z ruchu i praca przy obciążenia poniżej minimum technicznego. Przedstawione analizy opierały się na własnych pomiarach autorów wykonanych dla kotłów rusztowych typu WR zasilających w ciepło miejskie systemy ciepłownicze oraz na wynikach z symulacji komputerowych wykorzystujących uzyskane dane pomiarowe. Autorzy prezentują, wskaźniki emisji zanieczyszczeń gazowych do atmosfery, w oparciu o pomiary tych emisji w niestabilnych warunkach pracy kotła typu WR, a których to wskaźników aktualnie brakuje zarówno w literaturze jak i praktyce inżynierii ochrony atmosfery. Wskaźniki te pozwolą na rzeczywiste oszacowanie wielkości emisji gazowych zanieczyszczeń do atmosfery w takich niestabilnych warunkach pracy kotła, jak również ich wpływ na jakość powietrza w otoczeniu. Prezentowana praca dostarcza modele obliczeniowe do identyfikacji obciążenia emisyjnego zanieczyszczeniami gazowymi do atmosfery w jakichkolwiek, a przede wszystkim w niestabilnych warunkach pracy kotłów typu WR-25.

Topology of calculating pressure and friction coefficients for time-dependent human hip joint lubrication

Wierzcholski K.

Acta of Bioengineering and Biomechanics

2011

Vol. 13, no. 1

41-56

The paper deals with the calculations of the unsteady, impulsive pressure distributions, carrying capacities and friction forces under unsteady conditions in a super-thin layer of biological synovial fluid inside the slide biobearing gap limited by a spherical bone head. Unsteady and random flow conditions for the biobearing lubrication are given. Moreover, the numerical topology of pressure calculation for a difference method is applied. From a mathematical viewpoint the present method for the solution of the modified Reynolds equation allows this problem to be resolved by the partial recurrence nonhomogeneous equation of the second order with variable coefficients. To the best of the author knowledge, an adaptation of the known numerical difference method to the spherical boundary conditions applied during the pressure calculations for a human hip bonehead seems to be decisive.