scholarly journals Effect of Bed Material on Bed Agglomeration for Palm Empty Fruit Bunch (EFB) Gasification in a Bubbling Fluidised Bed System

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4336 ◽  
Author(s):  
Tanakorn Kittivech ◽  
Suneerat Fukuda
Keyword(s):  
Silica Sand ◽  
Empty Fruit Bunch ◽  
Fluidised Bed ◽  
Suitable Alternative ◽  
Heating Value ◽  
Product Gas ◽  
Bed Materials ◽  
Bed Agglomeration ◽  
High Level ◽  
Bed Material

The high level of potassium compounds in Empty Fruit Bunch (EFB) induces ash-related problems, such as bed agglomeration, which is caused by the formation of a low-melting-point sticky compound: K2On·SiO2, especially in fluidised bed gasification using silica sand as bed material. Dolomite was found to be an effective alternative bed material for preventing bed agglomeration by the release of CaO via calcination processes during gasification. CaO acts as a catalyst to inhibit bed agglomeration by possibly enhancing the formation of K2CO3 instead of K2O·nSiO2. Alumina sand was also found to be a suitable alternative bed material to prevent bed agglomeration; however, due to the relatively high density of alumina sand, high gas velocity was needed to ensure good mixing and fluidisation. Using both dolomite and alumina sand as bed materials yielded a product gas having similar higher heating value (HHV) to that when using silica sand (i.e., 3.8–3.9 MJ/Nm3).

scholarly journals Experimental Investigation of Oxygen Carrier Aided Combustion (OCAC) with Methane and PSA Off-Gas

2020 ◽  
Vol 11 (1) ◽  
pp. 210
Author(s):  
Viktor Stenberg ◽  
Magnus Rydén ◽  
Tobias Mattisson ◽  
Anders Lyngfelt
Keyword(s):  
Oxygen Carrier ◽  
Silica Sand ◽  
Fuel Conversion ◽  
Fuel Gas ◽  
Bed Temperature ◽  
Bed Materials ◽  
Distribution Plate ◽  
Bed Material ◽  
Gas Conversion ◽  
No Emissions

Oxygen carrier aided combustion (OCAC) is utilized to promote the combustion of relatively stable fuels already in the dense bed of bubbling fluidized beds by adding a new mechanism of fuel conversion, i.e., direct gas–solid reaction between the metal oxide and the fuel. Methane and a fuel gas mixture (PSA off-gas) consisting of H2, CH4 and CO were used as fuel. Two oxygen carrier bed materials—ilmenite and synthetic particles of calcium manganate—were investigated and compared to silica sand, an in this context inert bed material. The results with methane show that the fuel conversion is significantly higher inside the bed when using oxygen carrier particles, where the calcium manganate material displayed the highest conversion. In total, 99.3–99.7% of the methane was converted at 900 °C with ilmenite and calcium manganate as a bed material at the measurement point 9 cm above the distribution plate, whereas the bed with sand resulted in a gas conversion of 86.7%. Operation with PSA off-gas as fuel showed an overall high gas conversion at moderate temperatures (600–750 °C) and only minor differences were observed for the different bed materials. NO emissions were generally low, apart from the cases where a significant part of the fuel conversion took place above the bed, essentially causing flame combustion. The NO concentration was low in the bed with both fuels and especially low with PSA off-gas as fuel. No more than 11 ppm was detected at any height in the reactor, with any of the bed materials, in the bed temperature range of 700–750 °C.

Rice Husk Combustion in a BFBC Using Porous Bed Material

2005 ◽  
Author(s):  
Tadaaki Shimizu ◽  
Takumi Nemoto ◽  
Hotaka Tsuboi ◽  
Toshio Shimoda ◽  
Syunji Ueno
Keyword(s):  
Rice Husk ◽  
Porous Alumina ◽  
Silica Sand ◽  
Stable Operation ◽  
N2o Emissions ◽  
Nox Emissions ◽  
Bed Materials ◽  
Average Size ◽  
Bed Material ◽  
Fluidized Bed Combustor

Rice husk was burned in a bench-scale fluidized bed combustor (53 mm I.D. and 1.3m height) at 1123 K. Silica sand (average size 0.27 mm) was employed as conventional bed material. As an alternative bed material, a kind of porous alumina (average size 0.69 mm) was employed. Unburned gas (CO) emissions were suppressed by employing porous alumina as bed material. NOx emissions from the alumina bed were also suppressed in comparison to the sand bed. N2O emissions were nearly negligible (less than 10 ppm) for both bed materials. During combustion in the sand bed, sudden temperature rise up to 1450 K and increase in pressure drop across the bed were observed. Agglomerates were found in the bed material after the experiments. For the porous alumina bed, such agglomeration trouble did not occur. As conclusion, the present porous alumina was effective for both reduction of pollutants emissions and stable operation.

scholarly journals Investigating Agglomeration Tendency of Co-Gasification between High Alkali Biomass and Woody Biomass in a Bubbling Fluidized Bed System

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 56 ◽  
Author(s):  
Tanakorn Kittivech ◽  
Suneerat Fukuda
Keyword(s):  
Chemical Properties ◽  
Silica Sand ◽  
Empty Fruit Bunches ◽  
Wood Sawdust ◽  
Inorganic Matter ◽  
Bubbling Fluidized Bed ◽  
Blended Fuel ◽  
Bed Agglomeration ◽  
High Alkali ◽  
Bed Material

Palm empty fruit bunches (EFB) is known as problematic biomass due to its high alkali content, i.e., more than half of inorganic matter is potassium (K). EFB when used as a fuel in fluidized beds with silica sand as bed material could form the sticky compound K2O·nSiO2 starting at around 750 °C and adhere bed particles together, resulting in bed agglomeration. Blending EFB with rubber wood sawdust (RWS) could improve the chemical properties and consequent ash composition of the blended fuel. In this study, RWS was blended with EFB at three ratios: RWS:EFB = 25:75, RWS:EFB = 50:50, and RWS:EFB = 75:25. Adding RWS to the fuel prolonged de-fluidization time. The high content of CaO in the RWS ash acted as an inhibitor to prevent the formation of K2O·nSiO2 and, instead, enhanced the formation of K2CO3, a higher melting point compound, which reduced bed agglomeration. During the experiment using RWS:EFB = 75:25, no bed agglomeration was found.

scholarly journals Analysis of bed agglomeration during gasification of wheat straw in a bubbling fluidised bed gasifier using mullite as bed material

2014 ◽  
Vol 254 ◽  
pp. 448-459 ◽  
Author(s):  
Seán T. Mac an Bhaird ◽  
Eilín Walsh ◽  
Phil Hemmingway ◽  
Amado L. Maglinao ◽  
Sergio C. Capareda ◽  
...  
Keyword(s):  
Wheat Straw ◽  
Fluidised Bed ◽  
Bed Agglomeration ◽  
Bed Material

Experimental Research on Impacts of Operation Parameters on Agglomeration Characteristics during CFB Biomass Gasification

2014 ◽  
Vol 556-562 ◽  
pp. 375-379
Author(s):  
Xiao Xu Fan ◽  
Li Guo Yang ◽  
Hui Liang Zhang ◽  
Hong Jian Chen
Keyword(s):  
Fluidized Bed ◽  
Biomass Gasification ◽  
High Alumina ◽  
Cotton Stalk ◽  
Air Velocity ◽  
Bed Materials ◽  
Operation Parameters ◽  
Bed Agglomeration ◽  
Bed Material ◽  
Return Valve

The impacts of operation parameters on agglomeration characteristics during biomass gasification in fluidized bed were studied experimentally in a 0.02MWt CFB gasifier using cotton stalk pellet as fuel. The experimental results indicated that among the temperature range (600 °C-800 °C), bed agglomeration would occur after a period running with sand, high alumina bauxite or periclase as the bed material, and potassium gathered on the surface of bed materials. In the process of the fluidized-bed gasification of biomass, air velocity affected the degree of bed agglomeration, and the agglomeration problem in return valve was more serious than that in main bed.

scholarly journals Mapping the Effects of Potassium on Fuel Conversion in Industrial-Scale Fluidized Bed Gasifiers and Combustors

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1380
Author(s):  
Teresa Berdugo Vilches ◽  
Jelena Maric ◽  
Henrik Thunman ◽  
Martin Seemann
Keyword(s):  
Fluidized Bed ◽  
Silica Sand ◽  
Fuel Conversion ◽  
Comprehensive Overview ◽  
Char Gasification ◽  
Gasification Rate ◽  
Catalytically Active ◽  
Dual Fluidized Bed ◽  
Bed Agglomeration ◽  
Bed Material

Potassium (K) is a notorious villain among the ash components found in the biomass, being the cause of bed agglomeration and contributing to fouling and corrosion. At the same time, K is known to have catalytic properties towards fuel conversion in combustion and gasification environments. Olivine (MgFe silicate) used as gasifier bed material has a higher propensity to form catalytically active K species than traditional silica sand beds, which tend to react with K to form stable and inactive silicates. In a dual fluidized bed (DFB) gasifier, many of those catalytic effects are expected to be relevant, given that the bed material becomes naturally enriched with ash elements from the fuel. However, a comprehensive overview of how enrichment of the bed with alkali affects fuel conversion in both parts of the DFB system is lacking. In this work, the effects of ash-enriched olivine on fuel conversion in the gasification and combustion parts of the process are mapped. The work is based on a dedicated experimental campaign in a Chalmers DFB gasifier, wherein enrichment of the bed material with K is promoted by the addition of a reaction partner, i.e., sulfur, which ensures K retention in the bed in forms other than inactive silicates. The choice of sulfur is based on its affinity for K under combustion conditions. The addition of sulfur proved to be an efficient strategy for capturing catalytic K in olivine particles. In the gasification part, K-loaded olivine enhanced the char gasification rate, decreased the tar concentration, and promoted the WGS equilibrium. In the combustion part, K prevented full oxidation of CO, which could be mitigated by the addition of sulfur to the cyclone outlet.

scholarly journals Influence of Gasification Operating Parameters on Performance of the Nong Bua Dual Fluidized Bed Gasification System in Thailand

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Vilailuck Siriwongrungson ◽  
Malinee Prasong ◽  
Janjira Hongrapipat ◽  
Reinhard Rauch ◽  
Shusheng Pang ◽  
...  
Keyword(s):  
System Performance ◽  
Operating Time ◽  
Gas Composition ◽  
Heating Value ◽  
Product Gas ◽  
Lower Heating Value ◽  
Dual Fluidized Bed ◽  
Bed Material ◽  
System Power ◽  
Lower Heating

Gasification system performance generally depends on feed moisture content, activity of bed material, gasifier and combustor temperatures, and scrubber media. The tar concentration and gas composition of product gas are two indicators of the gasification system performance. In this research, the effects of gasifier temperature and the activity of bed material on the tar concentration and gas composition of the product gas produced from a dual fluidized bed (DFB) gasification system power plant were investigated. The DFB gasification system power plant is located in Nong Bua district, Nakhon Sawan province, Thailand. Two periods of gasification operation were examined. These two periods were when the olivine was freshy activated and then after a period of operation. The gasifier temperature had several peaks during the operation, which caused the product gas composition to fluctuate. When the olivine had been used for a period, the percentage of hydrogen was approximately 3% higher than when the olivine had been freshly activated, and a lower heating value was observed, which was probably due to lower heating value of hydrogen. The tar concentration was substantially lower when compared with the freshly activated olivine. When the olivine was used for a period, the average tar concentration was 56±22 mg/Nm3 (this is after 95 h continuous operating time) while the average tar concentration of the freshly activate olivine was 872±125 mg/Nm3 (which was after 34.5 h continuous operating time). It was concluded that the average tar concentration and gas composition were influenced by the activity of the bed material and the gasification temperature.

A New Method to Inhibit Bed Agglomeration Problems in Fluidized Bed Boilers

2003 ◽  
Author(s):  
Jaani Silvennoinen
Keyword(s):  
Fluidized Bed ◽  
Industrial Scale ◽  
Fluidized Bed Combustion ◽  
Natural Sand ◽  
Worst Case ◽  
Free Quartz ◽  
Bed Materials ◽  
Bed Agglomeration ◽  
High Alkali ◽  
Bed Material

Fluidized bed combustion (FBC) technology was commercialized in the 70s. Both bubbling fluidized bed (BFB) and circulating fluidized bed (CFB) technology are capable of handling a wide variety of solid fuels. Natural sand is typically used as the fluidizing material. However, the properties and behavior of some solid fuel ash may limit the use of these fuels due to bed agglomeration problems. Natural sand contains several minerals, typically mainly consisting of 20–50 wt.-% of plagioclase (NaAlSi3O8 + CaAlSi3O8), 10–30 wt.-% of potash feldspar (KAlSi3O8), and 25–100 wt.-% of quartz (SiO2). Biomass based fuels contain high amounts of alkali. Ash high in alkali may react with the free quartz of the natural sand, producing an alkali silicate mixture with low melting point. This mixture may act as an adhesive between fluidized bed particles and may, in the worst-case, result in serious fluidization problems. This problem can be avoided by using AGGLOSTOP™ quartz-free bed material. Four different bed materials were tested in a 15 kW laboratory-scale FBC test rig with plywood residue, which is known to cause severe fluidization problems in FB boilers. Two of the tested bed materials were quartz-free. When quartz-free bed materials were used, no signs of bed agglomeration were observed. The other two bed materials containing free quartz caused total defluidization at a temperature of around 750°C after about half an hour of operation. The concept of using AGGLOSTOP™ quartz-free bed material with high alkali fuels has been successfully applied in two industrial scale BFB boilers (15 and 74 MWth). The use of AGGLOSTOP™ fluidized bed material enables energy production in FB boilers based on high alkali fuels, which were earlier impossible to utilize due severe bed agglomeration problems. This paper focuses on the bed agglomeration phenomenon by discussing the results from laboratory and industrial-scale boilers and presents a new solution to extend the use of high alkali fuels in FB boilers.

scholarly journals Catalytic gasification of oil palm empty fruit bunch by using Indonesian bentonite as the catalyst

2021 ◽  
pp. 1-10
Author(s):  
Nabila Aprianti ◽  
Muhammad Faizal ◽  
Muhammad Said ◽  
Subriyer Nasir
Keyword(s):  
Oil Palm ◽  
Empty Fruit Bunch ◽  
Gas Composition ◽  
Catalytic Gasification ◽  
Heating Value ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Product Gas ◽  
Effects Of Temperature ◽  
Gas Efficiency

Oil palm empty fruit bunch (OPEFB is one of the enormous waste expected to become a renewable energy source. This study aimed to convert OPEFB into syngas through a gasification process using bentonite as a catalyst. The effects of temperature and product gas catalysts were investigated, and the efficiency of the gasification process was summarized. The process has used an updraft gasifier at 350-550 °C and air as the gasification medium (ER 0.2). The results indicate that syngas can be produced by updraft gasifier. When the temperature increase, the H2 and CO rising. The highest H2 and CO content of 27.74% and 20.43% are obtained at 550°C when bentonite applied. HHV and LHV range of 3.38~12.79 MJ/Nm3 and 3.03~11.58 MJ/Nm3, respectively. The maximum carbon conversion efficiency (CCE) and cold gas efficiency (CGE) reach 85.49% and 82.34%. Bentonite has been able to increase the concentration of the gas composition especially H2 and CO and the heating value of syngas.

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