Fluid bed cooler, a fluid bed combustion reactor and a method fo

Details Fluid bed cooler, a fluid bed combustion reactor and a method fo Fluid bed cooler, a fluid bed combustion reactor and a method fo

1990-01-03

1991-05-14

Favors, Edward G.

Liquid heaters and vaporizers

Miscellaneous

16510416, 122483, B09B 300, F22B 100

Patent

active

050146521

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention concerns fluid-bed combustion reactors and a method for the operation of a fluid-bed combustion reactor. The invention further concerns a fluid-bed cooler for particulate material.
Fluid-bed systems are used in a number of processes, wherein a good contact between solid particulate material and gas is desired. Examples are heat exchange, reactions with heterogeneous catalysts and reactions directly between solid matter and gases. The fluid-bed principle may briefly be explained in that the solid particulates are affected by a fluidization gas introduced from below, it being within certain constraints possible hereby to suspend the particles within a body of particulate materials and keep them suspended, even though the gas flow velocity does not need to rise to a level where single particles except for the very smallest ones would be entrained and carried away by the gas flow. Under such conditions the individual particles are freely movable, but the body of the particulate material will exhibit an upper surface, i.e. it behaves like a liquid from which the name fluid-bed. Hereby, obviously a very large area of contact between the solid particulates and the applied gas is achieved.
Recently fluid-bed systems have acquired a special interest in connection with applications related to combustion systems for solid fuels. Important advantages are that fluid bed systems may operate on various types of fuel and that an extremely good heat transfer from the combustion may be obtained. The body of particles within such systems may comprise inert particles such as sand, into which a minor proportion of fuel is added. The inert particles are heated by the combustion and circulate within the fluid-bed contacting suitable heat exchanger surfaces to transfer heat hereto. Heat transfer by radiation or by gas convection to fixed heat exchanger surfaces which is usual with other combustion systems will thus to some extent be replaced by heat transfer through physical transport of particles, whereby extended contact areas and heat exchange by direct contact between solid matter is obtained, whereby the heat exchange coefficient (number of watts exchanged related to m.sup.2 's of surface area and related to degrees of temperature difference) is higher than that achieved by the contact between gas and fixed surface.
Fluid-bed combustion systems allow a closer control of combustion parameters and make it possible to clean the exhaust gas for certain undesirable materials as reactants may simply be intermixed into the bed material, making it possible to achieve a combustion which in several respects is more environmentally acceptable than it is possible with other combustion systems. However, besides these advantages there are also certain difficulties connected to fluid-bed reactors, among which may be noted that they are substantially more complicated than other combustion systems by requiring the controlled introduction of fluidization gas, and by requiring extended start-up periods, e.g. of the magnitude of 3 to 10 hours, due to the substantial amount of solid material to be heated. Furthermore, it is difficult to operate them completely satisfactory by partial load, and adjustments of the load can only be carried out slowly.
Fluid-bed combustion systems are traditionally classified by the mean velocity of fluidization gas upwards through the fluid-bed, several variants occurring operating at various gas velocities within a range that may be generally described by the limits designated slow beds and fast beds, respectively.
Slow beds are characterized by a fluidization velocity typically within the range 1 through 3 m/second, this velocity having lower limits defined by the requirement for oxygen to the combustion and by the requirement for a minimum gas velocity in order to fluidize the particles. The density within the body of particles will be relatively high and the bed must be relatively shallow in order to keep the gas pressure necessary for fluidization within reasonable l

REFERENCES:
patent: 4184455 (1980-01-01), Talmud et al.
patent: 4312301 (1982-01-01), Anson
patent: 4321233 (1982-03-01), Tsudi et al.
patent: 4469050 (1984-09-01), Kurenberg
patent: 4473032 (1984-09-01), Maintok
patent: 4716856 (1988-01-01), Beisswenger et al.
patent: 4753177 (1988-06-01), Engstrom et al.
patent: 4813479 (1989-03-01), Wahlgren
VGB Kraftwerkstechnik, vol. 67, No. 6, Jun. 1987, Essen de, pp. 555-556; G. Daradimos and I. Dreher: "Inbetriebsetzung und Betriebsverhalten der Wirbelschichtfeuerung".
VGB Kraftwerkstechnik, vol. 67, No. 5, May 87, Essen de, pp. 446-449; H. Langner et al., "Auslegung und Konstruktion des Damperzeugers der ZAWSF. STadtwerke Dufsburg".

Affiliated with

Also associated with

Rating

Fluid bed cooler, a fluid bed combustion reactor and a method fo does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Fluid bed cooler, a fluid bed combustion reactor and a method fo, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluid bed cooler, a fluid bed combustion reactor and a method fo will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1640389