Table of Contents
How does 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 fluidized bed process?
A fluidized bed is a physical phenomenon that occurs when a solid particulate substance (usually present in a holding vessel) is under the right conditions so that it behaves like a fluid. The usual way to achieve a fluidize bed is to pump pressurized fluid into the particles.
What is fluidized bed combustion boiler?
Fluidized-bed boilers are the most common type of boiler recommended for biomass fuel, which is burned within a hot bed of inert particles, typically sand. The fuel-particle mix is suspended by an upward flow of combustion air within the bed.
What are 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.
How does fluidized bed combustion reduce pollution?
The low combustion temperature reduces corrosion and fouling of heat-transfer surfaces, allows a lower emission of nitrogen oxides and alkalis, and also permits control of sulphur dioxide emission by direct addition of limestone or dolomite to the fluidized bed.
What is fluidized bed gasifier?
Fluidized-bed gasifiers suspend feedstock particles in an oxygen-rich gas so the resulting bed within the gasifier acts as a fluid. These gasifiers employ back-mixing, and efficiently mix feed coal particles with coal particles already undergoing gasification.
What is a fluidized bed heat exchanger?
A fluidized bed heat exchanger is provided in which air is passed through a bed of particulate material containing fuel. A steam-water natural circulation system is provided for heat exchange and the housing of the heat exchanger has a water-wall type construction.
Where are fluidized beds used?
Fluidized beds have been used in technological processes such as: cracking and reforming of hydrocarbons (oil), carbonization and gasification of coal, ore roasting, Fischer-Tropsch synthesis, polyethylene manufacturing, limestone calcining, aluminum anhydride production, granulation, vinil-chloride production, Sep 7, 2010.
What is FBC boiler type?
6.3 Types of Fluidised Bed Combustion Boilers 1. Atmospheric classic Fluidised Bed Combustion System (AFBC) 2. Atmospheric circulating (fast) Fluidised Bed Combustion system(CFBC) 3. Pressurised Fluidised Bed Combustion System (PFBC).
Where are FBC boilers used?
Bubbling FBC is used for Fuels with lower heating values such as Rice Husk. Under such sort, the main factors leading to fluidization are as follows: Solid Fuel Particle Size. Air Fuel Mixture.
What are the advantages of the fluidized bed combustion system over the fixed bed and the suspension firing systems?
The advantages of PFBC include improved cycle efficiency, reduced emissions, reduced boiler size, improved combustion, and reduced tube erosion [23].
What are the advantages of FBC boiler?
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.
Which among the following is not a fluidized bed combustion system?
Which one of the following is not a functioning model of fluidised bed? Explanation: The operation given as “Packed with fluid sliding on top” is not possible as a setup for fluidised bed because in this case the particles would get compressed and not in random free movement.
What is done to increase the rate of heat transfer in the Velox boiler?
What is done to increase the rate of heat transfer in the Velox boiler? Explanation: This boiler uses oil or gaseous fuel inside furnace for its combustion. The combustion gases are circulated through the tubes with supersonic speed velocity to increase the heat transfer rate between the hot gases and feed water. 4.
Which of the following are consequences of burning coal for energy?
Air pollution from coal-fired power plants is linked with asthma, cancer, heart and lung ailments, neurological problems, acid rain, global warming, and other severe environmental and public health impacts.
What is the percentage of SOx reduction which can be gained by adding an excess amount of limestone to the bed of an Afbc unit?
What percentage of SOx reduction that can be gained by adding an excess amount of limestone to the bed of an AFBC unit? e. 90 – 95%.
What are the three types of fluidized gasifiers used?
Explanation: Circulating fluidized bed, dual fluidized bed and bubbling fluidized bed are the three main types of fluidized gasifiers used. They are mainly used to achieve a uniform temperature distribution.
Why was fluidized bed not used commercially for production of gasoline?
Why was fluidized bed not used commercially for production of gasoline from natural gas? Explanation: Fluidized bed was not possible because of less conversion, scale up problem. Explanation: To maintain very high temperatures through passing high density current through electrically conductive material.
How does a gasifier work?
Gasification occurs in a gasifier, generally a high temperature/pressure vessel where oxygen (or air) and steam are directly contacted with the coal or other feed material causing a series of chemical reactions to occur that convert the feed to syngas and ash/slag (mineral residues).
What is packed and fluidized bed?
In a packed bed, upward liquid velocities can be applied up to the minimum fluidization velocity. In a liquid-fluidized bed, the upward liquid velocity is in between the minimum fluidization velocity and the terminal settling velocity of a single particle.
