Fuel and related compositions – Coal treating process or product thereof
Patent
1994-11-15
1996-11-26
Medley, Margaret
Fuel and related compositions
Coal treating process or product thereof
44622, 44629, 48197R, 48210, 48212, 48213, C10L 500
Patent
active
055780920
DESCRIPTION:
BRIEF SUMMARY
In thermo-electric power generation processes the old, established steam turbine cycle is increasingly substituted with a combined cycle comprising gas as well as steam turbine. In this way power generation can be performed with higher efficiency and 45-47% can be reached compared with 39-41% in the steam turbine cycle. Said high efficiency of the combined cycle is, however, obtained only when using natural gas as fuel, and for solid natural fuels, such as coal and bio (biological) fuels the efficiency is restricted to 42-44% because of the complications caused by transforming the fuel to a form which is acceptable for the gas turbine.
A number of processes, such as pressure (super-atmospheric) combustion, complete and partial gasification, etc. have been developed for making possible the use of solid natural fuels in connection with a combined cycle. All said processes are characterized by a high level of complexity and are therefore subjected to operation disturbances in a more than normal degree. This fact and the moderate efficiency of 42-44% have resulted in said processes having not been commonly accepted.
The present invention is directed to an uncomplicated method for transforming solid natural fuels, such as coal, preferably with 5-45% of volatile constituents, lignites, peat and bio fuels, to a form which is suited for a combined cycle, wherein the end product of said method is pressurized clean hot combustable gas with a high heat value, "reformed gas", suited for the gas turbine, and finely-divided hot char with a high heat value, which is suitable as a fuel for all types of steam generators. Char is here intended to be interpreted as the coke-like residue comprising low levels of H, O, N and S, which remains after pyrolysis of solid carbonaceous fuels.
The method according to this invention is characterized by transforming the solid natural fuel to a form suited for the combined cycle by pyrolysis in combination with reformation of the pyro gas in the presence of water vapour, wherein the flow of finely-divided fuel at super-atmospheric pressure, suitably 5-20 bars, and >700.degree. C. in a first reactor in a cascade of reactors, suitably .gtoreq.3, in the presence of finely-divided burnt lime and/or dolomite (when "lime" is used in the following in the specification said expression comprises also dolomite) for desulphurization, is brought into fluidizing contact with char recirculated from the last reactor in said cascade with a flow >5 times larger than the flow of fuel, whereafter fluidizing contact between formed pyro gas and char is continued in the subsequent reactors and the temperature in said reactors is suitably maintained at a higher level than in said first reactor, whereas the temperature in the last reactor in said cascade is suitably maintained at a lower level than in said first reactor, whereafter produced pyro gas and net char are separated, and recirculated char discharged from said last reactor, after adapted temperature increase by partial combustion with oxygen containing gas, is recirculated to said first reactor, the pyrolysis reactor, in said cascade .
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic diagram of an embodiment of a device according to present invention.
According to the invention the fluidizing contact between the gas and the char in all the reactors in said cascade is suitably performed in a fluidized bed of classical type, i.e. with the relative void volume .epsilon. in the fluidized bed maintained within the range 0.4 <.epsilon.<0.8. For achieving a good contact and rapid pyrolysis the dried natural fuel is finely-divided prior to the pyrolysis so that suitably 50% thereof has a particle size <150 .mu.m and 90% <250 .mu.m.
The contact of the finely-divided natural fuel and the recirculating char with adapted temperature is performed by blowing the fuel with the aid of inert gas, suitably N.sub.2 (when N.sub.2 is stated to be the fluidizing gas in the following, said gas can also be substituted with another inert gas) against
REFERENCES:
patent: 3970434 (1976-07-01), Gasior et al.
patent: 4188191 (1980-02-01), Longanbach et al.
patent: 4315758 (1982-02-01), Patel et al.
patent: 4321233 (1982-03-01), Tsuji et al.
patent: 4338283 (1982-07-01), Sakamoto et al.
patent: 4407206 (1983-10-01), Bartok et al.
patent: 4509957 (1985-04-01), Fiery
patent: 4627367 (1986-12-01), Butt
patent: 4796568 (1989-01-01), Pillai
patent: 4823712 (1989-04-01), Wormer
patent: 4828486 (1989-05-01), Sakamoto et al.
patent: 4872886 (1989-10-01), Henley et al.
patent: 4993332 (1991-02-01), Boross et al.
patent: 5033413 (1991-07-01), Zenz et al.
patent: 5069685 (1991-12-01), Bissett et al.
patent: 5243922 (1993-09-01), Rehmat et al.
patent: 5306481 (1994-04-01), Mansour
LandOfFree
Method and a device for producing fuels does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and a device for producing fuels, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and a device for producing fuels will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1969853