Application of BFB Technology for Biomass Fuels: Technical Discussion and Experiences From Recent Projects

Bubbling fluidized bed combustion (BFB) is well applicable to biomass and other alternate fuels. Typical features for these fuels are high volatile content, varying moisture content and, in some cases, a somewhat high alkali and chlorine content. Fortum Engineering has supplied several boiler and power plants based on its in-house BFB boiler technology. The boilers show good performance with high availability and long operating time.

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Petroleum Coke and Coal Start-Up Testing in Bubbling Fluidized Bed Combustors

Journal of Energy Resources Technology ◽

10.1115/1.2794982 ◽

1997 ◽

Vol 119 (2) ◽

pp. 96-102 ◽

Cited By ~ 2

Author(s):

E. J. Anthony ◽

K. Anderson ◽

R. Carson ◽

I. T. Lau

Keyword(s):

Fluidized Bed ◽

Petroleum Coke ◽

Bituminous Coal ◽

Volatile Content ◽

Fluidized Bed Combustion ◽

Bench Scale ◽

Start Up ◽

Bubbling Fluidized Bed ◽

Tennessee Valley ◽

Start Ups

Bench-scale and 160 MWe demonstration tests were conducted for petroleum coke and high volatile bituminous coal blends. The bench-scale apparatus was a 100-mm-dia reactor located at the Canada Centre for Mineral and Energy Technology (CANMET), Energy Research Laboratories. The demonstration tests were conducted on the Tennessee Valley Authority’s (TVA) 160 MWe Shawnee Atmospheric Fluidized Bed Combustion (AFBC) Unit located at Paducah, Kentucky. Five and ten percent nominal volatile petroleum cokes were tested in the bench-scale unit. In addition, for the five-percent petroleum coke blends of 25, 50, and 75-percent petroleum coke, with the balance coal, were also examined at the bench scale. Eight start-up tests have been conducted with 50 percent blend of green delayed petroleum coke at the Shawnee AFBC unit. The bench-scale tests revealed that the volatile content in the petroleum coke was the primary factor affecting start-up. The tests showed that the volatile content from the coke and coal ignited at similar times; the char required longer to ignite. Bench-scale tests showed adequate start-up performance with blends up to 75 percent petroleum coke. Cold start-ups were conducted at the Shawnee AFBC Unit with 7 to 10 percent volatile green delayed petroleum coke. In all the start-ups, the operating temperature of 816°C was reached within 15 min of introducing the petroleum coke blend; this is similar to when high volatile bituminous coal was used. One start-up required a longer time because limestone had to be used to generate the bed. Local hot spots (982°C) were noticed in several start-ups for short periods, but subsided when additional air was supplied. Although more difficult to control, TVA routinely starts the Shawnee AFBC Unit with 50 percent shot petroleum coke and 50 percent high volatile bituminous coal.

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Wood Chip Drying through the Using of a Mobile Rotary Dryer

Energies ◽

10.3390/en12091590 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1590 ◽

Cited By ~ 9

Author(s):

Angelo Del Giudice ◽

Andrea Acampora ◽

Enrico Santangelo ◽

Luigi Pari ◽

Simone Bergonzoli ◽

...

Keyword(s):

Moisture Content ◽

Power Plants ◽

Black Locust ◽

Thermal Power ◽

Initial Moisture Content ◽

Wood Chip ◽

Wood Chips ◽

Cocurrent Flow ◽

Drying Process ◽

Rotary Dryer

Drying is a critical point for the exploitation of biomass for energy production. High moisture content negatively affects the efficiency of power generation in combustion and gasification systems. Different types of dryers are available however; it is known that rotary dryers have low cost of maintenance and consume 15% and 30% less in terms of specific energy. The study analyzed the drying process of woody residues using a new prototype of mobile rotary dryer cocurrent flow. Woodchip of poplar (Populus spp.), black locust (Robinia pseudoacacia L.), and grapevine (Vitis vinifera L.) pruning were dried in a rotary drier. The drying cycle lasted 8 h for poplar, 6 h for black locust, and 6 h for pruning of grapevine. The initial biomass had a moisture content of around 50% for the poplar and around 30% for grapevine and black locust. The study showed that some characteristics of the biomass (e.g., initial moisture content, particle size distribution, bulk density) influence the technical parameters (i.e., airflow temperature, rate, and speed) of the drying process and, hence, the energy demand. At the end of the drying process, 17% of water was removed for poplar wood chips and 31% for grapevine and black locust wood chips. To achieve this, result the three-biomass required 1.61 (poplar), 0.86 (grapevine), and 1.12 MJ kgdry solids−1 (black locust), with an efficiency of thermal drying (η) respectively of 37%, 12%, and 27%. In the future, the results obtained suggest an increase in the efficiency of the thermal insulation of the mobile dryer, and the application of the mobile dryer in a small farm, for the recovery of exhaust gases from thermal power plants.

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Biomass Ash – Bed Material Interactions Leading to Agglomeration in FBC

17th International Conference on Fluidized Bed Combustion ◽

10.1115/fbc2003-150 ◽

2003 ◽

Cited By ~ 5

Author(s):

H. J. M. Visser ◽

S. C. van Lith ◽

J. H. A. Kiel

Keyword(s):

Coating Thickness ◽

Problem Area ◽

Critical Conditions ◽

Fluidized Bed Combustion ◽

Biomass Ash ◽

Fundamental Study ◽

Fluidization Velocity ◽

Bubbling Fluidized Bed ◽

Bed Agglomeration ◽

Bed Material

In (bubbling) fluidized-bed combustion and gasification of biomass, several potential problems are associated with the inorganic components of the fuel. A major problem area is de-fluidization due to bed agglomeration. The most common found process leading to de-fluidization in commercial-scale installations is “coating-induced” agglomeration. During reactor operation, a coating is formed on the surface of bed material grains and at certain critical conditions (e.g., coating thickness or temperature) sintering of the coatings initiates the agglomeration. In an experimental approach, this work describes a fundamental study on the mechanisms of de-fluidization. For the studied process of bed de-fluidization due to sintering of grain-coating layers, it was found that the onset of the process depends on: a) a critical coating thickness, b) on the fluidization velocity when it is below approx. four times the minimum fluidization velocity and c) on the viscosity (stickiness) of the outside of the grains (coating).

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Ruhrchemie/Ruhrkohle’s Technical Version of the Texaco Coal Gasifier as Part of a Combined Cycle Plant

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/82-gt-167 ◽

1982 ◽

Cited By ~ 3

Author(s):

B. Cornils ◽

J. Hibbel ◽

P. Ruprecht ◽

R. Dürrfeld ◽

J. Langhoff

Keyword(s):

High Pressure ◽

Power Plants ◽

Coal Gasification ◽

Operating Time ◽

Combined Cycle ◽

Gas Generation ◽

Load Following ◽

Gasification Process ◽

Steady State Operation ◽

Combined Cycle Plant

The Ruhrchemie/Ruhrkohle variant of the Texaco Coal Gasification Process (TCGP) has been on stream since 1978. As the first demonstration plant of the “second generation” it has confirmed the advantages of the simultaneous gasification of coal: at higher temperatures; under elevated pressures; using finely divided coal; feeding the coal as a slurry in water. The operating time so far totals 9000 hrs. More than 50,000 tons of coal have been converted to syn gas with a typical composition of 55 percent CO, 33 percent H2, 11 percent CO2 and 0.01 percent of methane. The advantages of the process — low environmental impact, additional high pressure steam production, gas generation at high pressure levels, steady state operation, relatively low investment costs, rapid and reliable turn-down and load-following characteristics — make such entrained-bed coal gasification processes highly suitable for power generation, especially as the first step of combined cycle power plants.

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Bubbling fluidized bed combustion of Syncrude coke

10.4095/304362 ◽

1987 ◽

Cited By ~ 2

Author(s):

E J Anthony ◽

H A Becker ◽

R K Code ◽

R W McCleave ◽

J R Stephenson

Keyword(s):

Fluidized Bed ◽

Fluidized Bed Combustion ◽

Bubbling Fluidized Bed

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Operating parameters affecting the thermal performance of biomass boilers

TAPPI Journal ◽

10.32964/tj16.8.453 ◽

2017 ◽

Vol 16 (08) ◽

pp. 453-461

Author(s):

Naz Orang ◽

Honghi Tran ◽

Andy Jones ◽

F. Donald Jones

Keyword(s):

Moisture Content ◽

Thermal Performance ◽

Excess Oxygen ◽

Operating Parameters ◽

Pulp Mills ◽

Furnace Temperature ◽

Bubbling Fluidized Bed ◽

Oil Flow ◽

Induced Draft Fan ◽

Content Range

Operating data of a bubbling fluidized bed (BFB) boiler and three stoker grate (SG) biomass boilers from different pulp mills were analyzed over a 2-year period. The results show that in all cases, the thermal performance decreases markedly from 5.5 to 4 lb steam/lb dry biomass as the feedstock moisture content increases from 40% to 60%. The BFB boiler had better thermal performance, although it operated in a higher moisture content range compared with the SG boilers. Multivariate analysis was also performed on one of the SG boilers to determine operating parameters that affect thermal performance. The results show that furnace temperature, oil flow rate, and induced draft fan current positively correlate with thermal performance, while the feedstock moisture content, total air flow, and excess oxygen (O2) negatively correlate with thermal performance. This implies that when making modifications to improve thermal performance, it is important to take into account correlations among various parameters. In some cases, one positively correlated parameter might cause an increase in a negatively correlated parameter. The net effect might be a decrease in thermal performance.

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Thermo-economic analysis of an efficient lignite-fired power system integrated with flue gas fan mill pre-drying

Proceedings of 21th International Drying Symposium ◽

10.4995/ids2018.2018.7393 ◽

2018 ◽

Author(s):

Junjie Yan ◽

Xiaoqu Han ◽

Jiahuan Wang ◽

Ming Liu ◽

Sotirios Karellas

Keyword(s):

Moisture Content ◽

Economic Analysis ◽

Power System ◽

Energy Saving ◽

Flue Gas ◽

Power Plants ◽

Waste Heat ◽

Low Rank ◽

Analysis Model ◽

Energy Saving Potential

Lignite is a domestic strategic reserve of low rank coals in many countries for its abundant resource and competitive price. Combustion for power generation is still an important approach to its utilization. However, the high moisture content always results in low efficiencies of lignite-direct-fired power plants. Lignite pre-drying is thus proposed as an effective method to improve the energy efficiency. The present work focuses on the flue gas pre-dried lignite-fired power system (FPLPS), which is integrated with fan mill pulverizing system and waste heat recovery. The thermo-economic analysis model was developed to predict its energy saving potential at design conditions. The pre-drying upgrade factor was defined to express the coupling of pre-drying system with boiler system and the efficiency improvement effect. The energy saving potential of the FPLPS, when applied in a 600 MW supercritical power unit, was determined to be 1.48 %-pts. It was concluded that the improvement of boiler efficiency mainly resulted from the lowered boiler exhaust temperature after firing pre-dried low moisture content lignite and the lowered dryer exhaust gas temperature after pre-heating the boiler air supply. Keywords: lignite; pre-drying; thermodynamic analysis; thermo-economics

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