CO-COMBUSTION (COFIRING) OF WASTE WITH FUELS. Jan Nadziakiewicz

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1 CO-COMBUSTION (COFIRING) OF WASTE WITH FUELS Jan Nadziakiewicz

2 The need of co-combustion The increasing consumption of fuels creates the need to use some other substances as fuels. Especially interesting from technological point of view is cocombustion of fossil/renevable fuels with some amount of waste. The co-combustion process requires special systems of gas cleaning and monitoring of emission to the environment. Special emission standards must be observed. Most popular is using waste in cement industry and power systems. Various types of waste can be applied as fuel.

3 The purpose of using waste as fuel Energy recovery, Saving of fossil fuels and bio-renevable fuels, Reducing amount of waste to be landfilled, Reduction of environment pollution.

4 Waste types possible to use as fuels for co-combustion or production of rdf Waste codes Waste types for RDF production LCV MJ/kg Paper, cardboard Cloth 16, Textiles 16, Oils and edible fats Waste wood 15,8 Plastics Other elective collected fractions 14

5 THE TYPICAL PARAMETERS OF RDF PRODUCED FROM MUNICIPAL SOLID WASTE No. Parameter Unit Limits 1 Lower Heating Value kj/kg Ash content % < 20 3 Sulfur content % < 2 4 Chlorium content % < 0,7

6 Tanner diagram for mixture of municipal solid waste + 30% sludge FUEL Municipal Solid Waste Sludge 30% humidity MSW + Sludge 30% Sludge 80% huidity MSW + Sludge 80% Hard coal MARK

7 CO-COMBUSTION INSTALLATION it is the installation producing energy or other products in which the fuel is used with some additional amounts of waste or fuel from waste, with the aim of their energy recovery or incineration (utilization). This installation must fulfill the special requirements provided in a regulation dealing with the incineration systems.

8 Possible arrangements of co-combustion

9 MOST POPULAR WASTE USED AS ADDITIONAL FUELS Used tyres, Waste rubber, Waste from paper processing, Used oils, Waste wood, Municipal sewage sludge, Industrial sewage sludge, (paper pulp) Plastics, Used solvents.

10 Advantages and disadvantages of cofiring of waste with fuel Use of biomass in co-firing incorporate environmental, socioeconomic and strategy advantages regarding the use of biomass in dedicated biomass plants. In the case of waste residues the combustion may change the emission regulations to satisfy more strict standards For example, limits in emissions for large scale combustion facilities are more permissive than regulations for incineration plants. The bio-fraction of waste reduces emission of CO 2 to atmosphere determination of this fraction is a key issue.

11 Advantages and disadvantages of cofiring of waste with fuel Specific investment (per unit of installed power) is reduced in comparison with conventional biomass facilities since plant using fossil fuel already exists and only diverse modifications are required. Power generation with better efficiency: generally biomass power plants produce electricity with relative low efficiency (18 to 22%) compared with the huge coal units (32 to 38%) with optimised cycles given the economy of scale. Flexible operation: original plant can operate still at 100% load with fossil fuel. Co-firing facility is less sensitive to seasonality in biomass production and to biomass availability and price.

12 Advantages of co-combustion of waste Modernization of existing installation and infrastruccture is not necessary. No need for special training of staff operating the installation. Much easier approval of ecological and social organizations. Producing green energy with some extra income.

13 Disadvantages of co-firing of waste with fuel There are technical problems with the proper mixing of biomass/waste with coal. The addition of biomass lowers the softening temperature of ash causing the deposits on the boiler structure and worsening the heat transfer. Aplying the RDF instead of raw waste reduces this effect to some extent. European countries have proven the promotion of co-firing is a key for the development of biomass markets as well as for the creation of expertise on biomass handling and combustion.

14 Disadvantages of co-combustion of waste Needed higher efficiency of gas cleaning installations in existing boiler systems. More restricted emission standards for co-combustion than for combustion itself. Only cement kilns are fully prepared for o-comustion of waste, but they have special restrictions (LHV, Cl, metals). Only waste/rdf of defined properties can be added to coal in industrial installations.

15 Emission standards for SO 2 for fuels

16 Emission standards for NO 2 for fuels

17 Emission standards for dust for fuels

18 Emission standards for waste incineration

19 Emission standards of SO 2, NO 2, dust [mg/m 3 u] mg/m 3 u SO2 NOx Pył 0 Węgiel kamienny Biomasa Odpady 11% Odpady 6%

20 C, mg/m3u Emission standards for co-combustion of waste C SO ,2 0,4 0,6 0,8 1 Udział odpadu CSO2

21 Measured parameters for waste incineration installation: Hydrogen chloride (HCl) Hydrogem fluoride (HF) Nitrogen oxide (NO) Nitrogen dioxide (NO2) Sulphur dioxide (SO2) Carbon dioxide (CO2) Oxygen (O2) Ammonia (NH3) Water vapour (H2O) Mercury (Hg ) Temperature THC VOC Sb + AS + Pb + Cr + Co + Cu + Mn + Ni + V

22 WASTE INCINERATION SYSTEM 1.Bunkier na odpady komunalne 2 Podajnik odpadów 3.Palenisko z rusztem 4.Kocioł: - a - komora paleniskowa - b -pęczki konwekcyjne kotła - c- walczak 5. zasobnik żużla 6. Filtr spalin 7. Wylot spalin do instalacji oczyszczania

23 Co-combustion in power boilers Power boilers fired with coal or biomass have good potential in co-combustion of waste or fuel from waste with basic fuel. The main advantage is their technical equipment: fuel storage and preparation, milling systems, gas cleaning systems etc. Long time of residence of flue gas in the boiler (2s). The other positive point is the formal regulations which in most cases are fulfilled by power installations, althoug some additional equipment should be installaed.

24 The basic types of boilers in power system Grate type boilers. Pulverized fuel boilers. Fluidized bed type boilers. The type of boiler influences on the possibility and cost of cocombustion of waste with fuel.

25 Grate type boilers Grate type boilers are used mainly in a small water or steam boilers of a thermal power up to 50 MW th. In large power systems they are usually used as peak-load boilers. Grate type boilers usually have very simple gas cleaning systems (cyclones, electrostatic precipitators, no SO 2 or NO x removal systems this is the real obstacle for cocombustion of waste or fuel from waste. Problems with the bottom ash still may contaain carbon and hydrocarbons.

26 OR-35N GRATE TYPE STEAM BOILER Boiler type: drum boiler Combustion system: moving grate Max. capacity: 9,7 kg/s Steam temp. Out: 450 C Steam pressure 4,0 MPa Thermal efficiency: 87% Fuel: Hard coal LHV of fuel: 23 MJ/kg Cieszyn electropower station

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28 Pulverized fuel type boilers They are most popular type of boilers in Polish power system. The thermal power of one unit usually exceeds 500MW th. This units are equipped in relatively sophisticated gas cleaning installations: dust removal (electrostatic precipitators or bag filters), SO 2 removal systems (dry or wet), NO x removal systems (SCR or SNCR). They can be relatively easy adapted to the requirements for co-combustion of waste. The main problem is milling of waste to the size required by coal transport system. The easiest type of waste to be cocombusted in these types of boilers is sewage sludge (small organic and mineral particles).

29 MAIN CHARACTERISTICS OF COAL FIRED POWER PLANT

30 PULVERIZED TYPE BOILER FOSTER WHEELER CORPORATION Odpowiednia objętoćś komory paleniskowej w celu skutecznego spalania paliw stałych, ciekłych i gazowych Konstrukcja MONO-WALLTM TM ze ścian membranowych zapewniajacych szczelność komory paleniskowej Młyny misowo-rolkowe MBF i bębnowo-kulowe dla wielu rodzajów paliw. System niskiej emisji NOx bazujący na stopniowaniu powietrza. Technologia SCR zapewniająca najniższą emisję NOx

31 PULVERIZED TYPE BOILER FOSTER WHEELER CORPORATION WP-200 Water boiler OP-230 Steam boiler

32 Advantages of co-combostion of sludge in pulverized type boilers Pulverized type boilers fuelled with coal are very popular in power system Poland and they are run as basic load for many hours per year. High capacity of these boilers (large amounts of coal burned) makes possible the utilization of large amounts of sludge. The investment costs of modification of fuel system are not very high and are much lower than for special installation of sludge incineration.. The sluge from munisipa sewage is not corrosive and no toxic so the co-combustion process can be quite safe for environment.

33 Fluidal bed type boilers This type of boilers became more popular in Poland. There are low requirements regarding the size of fuel particles in the furnace. They have the possibility of SO 2 removal in the combustion process (lime addition to the fuel) and a low generation of NO x (low temperatures about C). The main problem is formal fulfilling the requirement of the gas temperature at least 850 o C and residence time of 2 s.

34 FLUIDAL BOILER OFZ-230 Natural circulation Fluidized bed circular boiler Max. capacity: 64 kg/s Steam temperature: 540 C Steam pressure: 13,8 MPa Temperature of water inlet: 158/205 C Boiler efficiency: 91,5% LHV of fuel: 17-20,1 MJ/kg

35 Polpharma Starogard Gdański 2 kotły OFz-75 ELETROCIEPŁOWNIA II BIELSKO-BIAŁA KOCIOŁ OFZ-230

36 GENERAL REMARKS The main restriction for applying co-combustion in power boilers are emission standards for such process. For relatively new boiler systems or by their modernization it is fairly easy to adapt the gas cleaning installations to emission standards for co-combustion. Przykładowe obliczenia standardów emisyjnych dokonane dla kotłów o różnej mocy cieplnej i jedynie dla trzech podstawowych rodzajów zanieczyszczeń prezentuje nastepująca tabela

37 Co-combustion in cement kilns

38 MAIN CHARACTERISTICS OF CEMENT PRODUCTION PROCESS

39 Co-combustion in cement kilns In many Polish cement production installations some types of waste is burned with coal. They are: grinded plastics, textiles, rubber, tyres, paper, wood, fuel from municipal solid waste etc. The method of applying the waste fuel to the kiln depends on the type of process: (dry or wet) and the type of kiln. The waste fuel can be fed to the main flame volume by a special burner or to the calcinator at the end of the kiln system. The important factor for this process is high temperature in the kiln ( C), high thermal inertia and alkaline atmosphere in the kiln.

40 Parameters of fuel accepted for cement kilns: Average NHV > 13 MJ/kg (min. 12 MJ/kg in bulk) humidity < 30 %, CL < 0,3 % S < 2,5 %, Heavy metals < 2500 ppm, PCB + PCT < 50 ppm, Hg < 10 ppm,

41 Scheme of heat processes in the kiln

42 Heavy metals in cement kiln Metals present in the fuel can be emitted in gas form or in a solid form., Solid metals are bound in the clinker with no negative effects neither on the procuct nor on environment. Solid-form metals are: Cr, Be, Ba, Ni, As i Ag. High volatile metals metals evaporate and are emitted as gas; they are: Hg and Tl. Medium volatile metals condensate on the dust particles and are recirculated to the process or are emitted to atmosphere; they are: Sb, Se, Pb, Cd. The use of alternative fuels of a defined parameters does not change the emission level of the system.

43 Advantages of co-combustion in cement kilns: Alkaline atmosphere neutralizing acidic gomponents of gas. Heavy metals immobilization in the clinker. High thermal efficiency of alternative fuel combustion in the process. Large thermal capacity providing steady parameters of the process. No solid products of combustion they are bounded with clinker. No special installations needed for combustion of alternative fuel, low costs of adaptation for additional fuel. High performance of dust removing systems and no increase of gas emission from the process.

44 Advantages of co-combustion in cement kilns: Co-combustion of alternative fuels in cement kilns helps in reducing the volume of waste. It reduces costs of production by recovery of energy from waste. It saves the natural energy sources (fuels). The rotary kiln can utilize various types of waste, which is difficult in other technologies.

45 Co-combustion of sewage sludge The sludge can be utilized in grate type of boilers or in pulverized types of boilers. The easiest method of fulfilling the requirmrnts of temperature and residence time are in pulverized type boilers because of large volume and high temperatures provided by main fuel. The experilence show that combustion of dried sludge with coals (up to about 10% mass) does not increase substantially the emission from the system. The other method is combustion of the sludge in cement kilns.

46 RÓWNOLEGŁE SPALANIE BIOMASY Z Równoczesne spalanie i współspalanie biomasy z węglem ze względu na dużą zawartość części lotnych, a małą zawartość azotu i siarki przebiega w odmienny sposób niż samego węgla. WĘGLEM W rezultacie udział biomasy przy wspólnym spalaniu z węglem oddziałuje na emisję tlenków azotu, dwutlenku siarki i metali ciężkich.

47 TECHNOLOGIE PRZETWARZANIA BIOMASY Bezpośrednie spalanie biomasy, Współspalanie biomasy z węglem, Termiczna utylizacja biomasy w spalarniach odpadów.

48 SPOSÓB PODAWANIA BIOMASY I PALIWA DO KOMORY PALENISKOWEJ KOTŁA ENERGETYCZNEGO Są dwie możliwości energetycznego wykorzystania biomasy w istniejących kotłach: współspalanie bezpośrednie: - mieszanie biomasy z węglem przed układem dozowania węgla do kotła (młynami), - niezależne przygotowanie biomasy rozdrobnienie i spalanie na ruszcie pod kotłem lub dozowanie do palników ewentualnie nad palnikami węglowymi niezależnym strumieniem w tym przypadku możliwe jest zużycie biomasy jako paliwa reburningowego; współspalanie pośrednie: - przedpalenisko do komory paleniskowej kotła wnoszone jest ciepło ze spalania biomasy - wstępne zgazowanie biomasy do komory paleniskowej wprowadzany jest wilgotny gaz palny.

49 METODY WSPÓŁSPALANIA W ENERGETYCE z zewnętrznym paleniskiem rusztowym dla biomasy, z wewnętrznym paleniskiem rusztowym dla biomasy poniżej przestrzeni paleniskowej, z mieleniem lub współmieleniem biomasy i węgla, z oddzielnym zgazowaniem biomasy i zasilaniem kotła gazem.

50 Z ZEWNĘTRZNYM PALENISKIEM RUSZTOWYM DLA BIOMASY spaliny max 1000 C biomasa Kocioł pyłowy

51 Z WEWNĘTRZNYM PALENISKIEM RUSZTOWYM DLA BIOMASY PONIŻEJ PRZESTRZENI PALENISKOWEJ Kocioł biomasa ruszt dla biomasy żużel

52 Z MIELENIEM LUB WSPÓŁMIELENIEM BIOMASY I WĘGLA młyn pył z biomasy i węgla Kocioł

53 INSTALACJE W AUSTRII I FINLANDII Elektrownie zagraniczne, jak na przykład w Lahtii w Finlandii oraz w austriackim Zeltweg wykorzystują system hybrydowy do produkcji energii elektrycznej. Po lewej - schemat elektrociepłowni w Zeltweg w Austrii o mocy 137 MW el i 334 MW c ze zgazowarką drewna o mocy 10 MW Po prawej - schemat procesowy elektrowni opalanej biomasą (poprzez jej zgazowanie) oraz węglem kamiennym i gazem ziemnym w Lahti (Finlandia) wg projektu firmy Foster-Wheeler 53

54 Ruszt mechaniczny jest wyposażony w kaskadowy układ podawania paliwa, dzięki czemu może być przystosowany do równoległego współspalania odpadów drewna poprzez prostą instalację drugiego układu zasilania

55 RUSZT PRZYSTOSOWANY DO WSPÓŁSPALANIA WĘGLA I BIOMASY

56 ZE PAK ELEKTROWNIA PĄTNÓW SA

57 ZE PAK ELEKTROWNIA ADAMÓW SA

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60 ZALETY SPALANIA BIOMASY Wykorzystywanie potencjału energetycznego biomasy, Obniżenie emisji CO 2 do atmosfery, Proces spalania jest stabilizowany przez spalanie węgla, Biomasa ma niski poziom zawartości siarki, Wysokie stężenie CaO w popiele pochodzącym z biomasy, Wyższa zawartość popiołu w węglu brunatnym daje możliwość obniżenia stężenia metali alkalicznych pochodzących z biomasy.

61 WADY WSPÓŁSPALANIA BIOMASY czas przebywania paliwa w komorze paleniskowej, szlakowanie paleniska, korozja wysokotemperaturowa, niszczenie katalizatorów, zmiana jakości popiołu, zmiana przebiegu procesu.

62 PODSUMOWANIE Współspalanie odpadów w instalacjach przemysłowych może stanowić realną alternatywę dla termicznych metod zagospodarowania różnych rodzajów odpadów. Najistotniejsza tutaj rolę mogą odegrać kotły energetyczne i piece cementowe służące do wypalania klinkieru, które stanowią najkorzystniejszą grupę instalacji przemysłowych do podjęcia procesu współspalania odpadów. Piece cementowe jako nieliczne instalacje przemysłowe mogą bez kosztownych modernizacji sprostać aktualnym przepisom w zakresie standardów emisyjnych. Z drugiej strony istnieje coraz większa grupa odpadów,których unieszkodliwienie powinno odbywać się metodami termicznymi. Dokonanie tego procesu poprzez profesjonalne spalarnie odpadów jest nadal kwestią przyszłości.