How does a fluidized bed combustion work?
Fluidized-bed combustion (FBC) uses a mixture of particles suspended in an upward flowing airstream, which combine to exhibit fluid-like properties. Combustion takes place in the bed with very intense mixing of gases and solids, high heat transfer to the furnace, and a low combustion temperature.
What is a BFB boiler?
Boilers. A bubbling fluidized bed (BFB) boiler is a boiler that can also handle fuels that are difficult to pulverize or less combustible. The fuel is introduced into a mixture of sand flowing at high temperatures, allowing the fuel to be efficiently combusted.
How does Afbc boiler work?
The AFBC Boiler achieves this by carrying out combustion in a bed of crushed refractory / sand which is suspended by an upward stream of air, fluidising it and facilitating a significant higher degree of combustion completeness.
What are fluidised beds used for?
Fluidized beds are used for several purposes, such as fluidized bed reactors (types of chemical reactors), solids separation, fluid catalytic cracking, fluidized bed combustion, heat or mass transfer or interface modification, such as applying a coating onto solid items.
What is FBC explain with neat sketch?
“Fluidized bed combustion (FBC) is a combustion technology used to burn solid fuels.” A bed of solid particles is said to be fluidized when the pressurized fluid (liquid or gas) is passed through the medium and causes the solid particles to behave like a fluid under certain conditions.
What is an advantage of the FBC?
FBC boilers can burn fuel with a combustion efficiency of over 95% irrespective of ash content. FBC boilers can operate with overall efficiency of 84% (plus or minus 2%). High heat transfer rate over a small heat transfer area immersed in the bed result in overall size reduction of the boiler.
What is the temperature range in a bubbling fluidized bed?
750–850°C
The fluidized bed gasifier usually works in the 750–850°C temperature range. The steam-to-fuel ratio or air-to-fuel ratio also affects this temperature. The CFB gasifier has higher carbon conversion efficiency and excellent heat transfer capacity than the conventional bubble fluidized bed gasifier [28,29].
Which mattress is used in fluidized bed combustion boiler?
Atmospheric fluidized beds use limestone or dolomite to capture sulfur released by the combustion of coal. Jets of air suspend the mixture of sorbent and burning coal during combustion, converting the mixture into a suspension of red-hot particles that flow like a fluid. These boilers operate at atmospheric pressure.
Why bed material is used in boiler?
The purpose of Bed Material is to support Fluidization of the Bed. It is little heavier (higher gravity) and rounded spherical shaped sand allowing uniform primary air distribution for good fluidization and at the same time ensuring excellent turbulence for combustion with minimum excess air.
What are the types of FBC boiler?
1. Atmospheric classic Fluidised Bed Combustion System (AFBC) 2. Atmospheric circulating (fast) Fluidised Bed Combustion system(CFBC) 3. Pressurised Fluidised Bed Combustion System (PFBC).
Why is fluidization important?
These chemical reactions are highly exothermic and fluidization ensures a uniform temperature, minimizing unwanted side reactions, and efficient heat transfer to cooling tubes, ensuring high productivity.
What is the advantage of fluidization?
The chief advantage of fluidization are that the solid is vigorously agitated by the fluid passing through the bed, and the mixing of the solid ensures that there are practically no temperature gradients in the bed even with quite exothermic or endothermic reactions.
What are the different types of FBC?
What are the types of fluidized bed?
There are two main types of fluidized bed gasification systems—bubbling fluidized bed and CFB. Depending on the scale of operation, the cyclone separators for capture and recycling of solid particles could be placed either internally or externally.
What are the types of fluidization?
… of the type of material being fluidized, six distinct fluidization types can occur. These are, homogeneous, bubbling, slugging, turbulent, jetting and spouting as described by Kunii and Levenspiel 1991[13].
What is fluidization process?
Fluidization (or fluidisation) is a process similar to liquefaction whereby a granular material is converted from a static solid-like state to a dynamic fluid-like state. This process occurs when a fluid (liquid or gas) is passed up through the granular material.
What is FBC explain its stages with neat sketch?
“Fluidized bed combustion (FBC) is a combustion technology used to burn solid fuels.” A bed of solid particles is said to be fluidized when the pressurized fluid (liquid or gas) is passed through the medium and causes the solid particles to behave like a fluid under certain conditions. Check Our Steam Boilers Catalog.
What is boiler efficiency formula?
η=(Energy output)/(Energy input) X 100
In order to calculate boiler efficiency, we divide the total energy output by total energy input, multiplied by hundred.
What are the advantages of fluidized bed combustion?
Advantages and Dis-advantages of Fluidized Bed Combustion
High thermal efficiency. Easy ash removal system, to be transferred for made cement. Short commissioning and erection period. Fully automated and thus ensures safe operation, even at extreme temperatures.
What are types of fluidization?
What are the disadvantages of fluidization?
The main disadvantage of gas-solid fluidization is the uneven contacting of gas and solid. Erosion of vessel internals. Attrition of solids. Because of attrition, the size of the solid particles is getting reduced and possibility for entrapment of solid particles with the fluid are more.
What is the principle of fluidization?
1 The principle of fluidization. Fluidization is the process of stationary solid particles brought into a dynamic “fluid-like” state by an upward stream of fluid (gas or liquid) (Fan & Zhu, 2005).
What are the disadvantages of fluidized bed reactor?
Disadvantages. As in any design, the fluidized bed reactor does have its draw-backs, which any reactor designer must take into consideration. Increased reactor vessel size: Because of the expansion of the bed materials in the reactor, a larger vessel is often required than that for a packed bed reactor.
What are the advantages of fluidized-bed combustion?