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1

Usefulness assessment of automatic air flow control system with oxygen sensor in a 20 kW boiler with periodic wood pellet supply

Juszczak M., Cichy W., Pałaszyńska K.

Drewno : prace naukowe, doniesienia, komunikaty

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2016

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vol. 59, nr 198

111--130

EN

The benefits of applying automatic air flow control system with oxygen sensor in a 20 kW heating boiler with a retort furnace supplied periodically with wood pellets were examined. Boiler combustion chamber was not lined with ceramic blanket and therefore the fuel supply cycle duration (operation and stand-by) was set by the producer to just 20 seconds. Variation in time of carbon monoxide, nitric oxide, nitrogen oxides and oxygen concentrations in the flue gas, as well as correlations between: pollutant concentrations and temperature in the combustion chamber or oxygen concentration, temperature in the combustion chamber and oxygen concentration, nitric oxide and carbon monoxide concentrations were compared for different scenarios: with automatic air flow control and with constant air flow. It was concluded that applying automatic air flow control system with oxygen sensor did not significantly reduce carbon monoxide concentration (only by 10-15%). Most probably it is because the stand-by in fuel feeding is too short for the air supply fan to react. In order to reduce carbon monoxide concentration, instead of applying automatic air flow control it is preferable to obtain higher heat outputs (above 60% of its maximum value) and use higher capacity water heat storages.

2

Correlation between air flow rate and pollutant concentrations during two-stage oak log combustion in a 25 KW residential boiler

Juszczak M.

Chemical and Process Engineering

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2016

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Vol. 37, nr 3

419--428

EN

It can be expected that there is a considerable correlation between combustion air flow rate and the concentrations of carbon monoxide, hydrocarbons and nitrogen oxide in the flue gas. The influence of temperature and oxygen concentration in the combustion zone on the concentrations of carbon monoxide, hydrocarbons and nitrogen oxide in the flue gas, for high and low combustion air flow, was analysed. Oxygen concentration for which the concentration of carbon monoxide is the lowest was determined, as well as the mutual relation between carbon monoxide and nitrogen oxide concentration.

3

Concentrations of carbon monoxide and nitrogen oxides from a 25 kW boiler supplied periodically and continuously with wood pellets

Juszczak M.

Chemical and Process Engineering

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2014

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Vol. 35, nr 2

163--172

EN

The impact of the fuel feeding mode (continuous or periodic with different stand-by/operation time ratios) on carbon monoxide (CO) and nitrogen oxides (NO, NOx) concentration values in the flue gas was analysed for coniferous wood pellet firing. Experiments were performed in a 25 kW water boiler equipped with an over-fed wood pellet furnace located in a full scale heat station simulating real-life conditions. Influence of oxygen concentration and temperature in the combustion chamber on carbon monoxide and nitrogen oxide concentrations was presented in diagrams. Dust and hydrocarbon concentrations were also monitored. It was concluded that the commonly used periodic fuel supply does not necessarily cause a significant increase of carbon monoxide concentration, as compared to the continuous fuel feeding mode. Continuous fuel supply can even induce higher carbon monoxide concentrations when fuel mass stream is not chosen properly. Each time new fuel type is used in a specific furnace, one should perform experiments to determine the adequate settings (stand-by/operation time ratio, fuel mass streams, air stream) to obtain the optimal, lowest possible emission for a certain boiler heat output.

4

Alternatywne systemy grzewcze

Nantka Marian B.

Builder

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2014

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R.18, nr 9

80--84

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Stężenia tlenku węgla i tlenków azotu (NO, NOX) z kotła o mocy 25 kW zasilanego peletami drzewnymi w sposób periodyczny i ciągły

Juszczak M.

Archiwum Gospodarki Odpadami i Ochrony Środowiska

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2013

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Vol. 15, nr 3

17--24

EN

The impact of periodic and continuous feeding mode on the carbon monoxide (CO) and nitrogen oxides (NO, NOx) concentration values in the flue gas downstream the boiler was analyzed during firing 4,6 and 8 kg/h of wood pellets in an overfeed- channel furnace. Significant increase of CO concentration during periodic feeding mode in comparison to continuous feeding mode, was observed only in the case of very long stand-by period. In periodic fuel supply with constant air stream, during stand-by period in fuel feeding, the temperature in combustion chamber decreased, however oxygen concentration increased. These factors, that usually influence nitrogen oxide concentration compensated mutually to a big extent. Therefore, the concentration of nitric oxide (NO) and nitrogen oxides (NOx) mainly depended on the stream of nitrogen in the fuel supplied to the furnace, as temperature in the combustion chamber was relatively low (below 700°C). Investigations were performed in the full-scale heat station in conditions similar to these which appeared in reality.

PL

Stężenia tlenku węgla i tlenków azotu (NO, NOX) z kotła o mocy 25 kW zasilanego peletami drzewnymi w sposób periodyczny i ciągły. Badano wpływ periodycznego i ciągłego zasilania peletami drzewnymi kotła z paleniskiem nasuwowym-korytkowym, na stężenia tlenku węgla i tlenków azotu (NO i NOx) w spalinach. Stwierdzono, że stężenie tlenku węgla dla zasilania periodycznego rośnie znacząco w stosunku do zasilania ciągłego dopiero dla bardzo długich przerw w dozowaniu peletów. W czasie dozowania periodycznego paliwa (przy stałym strumieniu powietrza), temperatura w komorze spalania obniżała się a stężenie tlenu rosło. Te czynniki, które wpływały na zmniejszenie i wzrost stężenia tlenków azotu, wzajemnie się kompensowały w dużym stopniu. Stężenia tlenków azotu zależały więc głównie od strumienia azotu dostarczanego do paleniska w paliwie, dlatego że temperatura w komorze spalania była względnie niska (poniżej 700°C). Badania były prowadzone w kotłowni w pełnej skali technicznej, w warunkach zbliżonych do rzeczywistej eksploatacji.

6

Ocena efektywności energetycznej podgrzewaczy regeneracyjnych wysokoprężnych bloku ciepłowniczego elektrociepłowni

Pojawa B, Strumski P

Rynek Energii

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2012

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Nr 6

27--33

PL

Do głównych urządzeń wchodzących w skład typowego bloku ciepłowniczego BC–50 elektrociepłowni należą między innymi podgrzewacze regeneracyjne wysokoprężne. Przeznaczone są do podgrzewania wody zasilającej kocioł parowy w części wysokoprężnej bloku ciepłowniczego. Czynnikiem grzewczym jest para przegrzana pochodząca z nieregulowanych upustów pary w części wysokoprężnej turbiny parowej. Podczas wymiany ciepła zachodzącej w podgrzewaczach bardzo istotną rolę stanowi ciepło skraplania pary. Przedstawione w artykule badania dotyczą oceny efektywności energetycznej pracy przedmiotowych podgrzewaczy. Badania przeprowadzono w aspekcie wykorzystania ciepła skraplania pary podczas wymiany ciepła zachodzącej w podgrzewaczach oraz możliwości zoptymalizowania ich pracy. Do badań wykorzystano wyniki pomiarów zarejestrowanych przez system pomiarowo–rejestrujący, wybranego bloku ciepłowniczego elektrociepłowni. LITERATURA

EN

The main devices in the heating block of a typical heat and power station are among other high-pressure regenerative heaters. They are designed to heat the steam boiler feed water in the high-pressure part of heating block. Heating medium is superheated steam coming from non-regulated vents of high-pressure part of steam turbine. Heat of condensation is a very important during the heat exchange occurring in heater. Studies presented in this article concerns the evaluation of the energy efficiency of the work in research heaters. The study was conducted in the context of the use of heat of condensation during heat transfer occurs in heater and the ability to optimize their work. The study uses the results of the measurements recorded by measuring and recording system, the selected heating block of heat and power station.

7

Pollutant emission from a heat station supplied with agriculture biomass and wood pellet mixture

Juszczak M., Lossy K.

Chemical and Process Engineering

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2012

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Vol. 33, nr 2

231-242

EN

Tests for combustion of hay and sunflower husk pellets mixed with wood pellets were performed in a horizontal-feed as well as under-feed (retort) wood pellet furnace installed in boilers with a nominal heat output of 15 and 20 kW, located in a heat station. During the combustion a slagging phenomenon was observed in the furnaces. In order to lower the temperature in the furnace, fuel feeding rate was reduced with unaltered air stream rate. The higher the proportion of wood pellets in the mixture the lower carbon monoxide concentration. The following results of carbon monoxide concentration (in mg/m3 presented for 10% 02 content in flue gas) for different furnaces and fuel mixtures (proportion in wt%) were obtained: horizontal-feed furnace supplied with hay/wood: 0/100 - 326; 30/70 - 157; 50/50 - 301; 100/0 - 3300; horizontal-feed furnace supplied with sunflower husk/wood: 50/50 - 1062; 67/33 - 1721; 100/0 - 3775; under-feed (retort) furnace supplied with hay/wood: 0/100 - 90; 15/85 - 157; 30/70 - 135; 50/50 - 5179; under-feed furnace supplied with sunflower husk/wood: 67/33 - 2498; 100/0 - 3128. Boiler heat output and heat efficiency was low: 7 to 13 kW and about 55%, respectively, for the boiler with horizontal-feed furnace and 9 to 14 kW and 64%, respectively, for the boiler with under-feed furnace.

8

Pollutant concentrations from deciduous wood fuelled heat station

Juszczak M.

Chemical and Process Engineering

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2011

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Vol. 32, nr 1

41-55

EN

CO, NO, NO2 and dust concentrations from combustion of deciduous wood (birch, beech, lime-tree) logs and pellets in two heating boilers (15 and 25 KW), situated in a heat station were investigated. Time dependences of pollutant concentrations as well as the impact of temperature in the combustion chamber and oxygen concentration on pollutant concentrations were presented. Pollutant emission indices have been estimated.

9

Pollutant concentrations from a heat station fuelled with a wood pellet and coffee husk pellet mixture

Juszczak M.

Archiwum Gospodarki Odpadami i Ochrony Środowiska

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2011

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Vol. 13, nr 4

51-58

EN

CO, CxHy, NO, NOx and dust concentrations from a heat station with a boiler of 15 kW nominal heat output supplied with a wood pellet and coffee husk pellet mixture were researched . In the entrained flow furnace designed for firing wood pellet burning, melting and sintering ash phenomenon was not be successfully avoided. In comparison to wood pellet combustion, the observed boiler heat efficiency was lower. CO concentration was relatively high but did not exceed the permitted value. The impact of temperature in the combustion chamber and oxygen concentration on pollutant concentrations was determined. Pollutant emission indicators were estimated.

PL

W kotłowni grzewczej badano stężenia CO, CxHy, NO, NOx i pyłu z kotła o mocy nominalnej 15 kW, zasilanego mieszaniną peletów drzewnych i peletów z łusek kawy. W palenisku typu narzutowego dostosowanego do peletów drzewnych, mimo obniżenia temperatury, nie udało się uniknąć całkowicie zjawiska mięknienia i zlepiania się popiołu. Uzyskano niższą niż dla peletów drzewnych sprawność cieplną kotła oraz wyższe stężenie tlenku węgla, lecz poniżej dopuszczalnej wartości. Określono wpływ temperatury w komorze spalania i stężenia tlenu na stężenia zanieczyszczeń. Oszacowano wskaźniki emisji.