Fuel and related compositions – Coal treating process or product thereof
Reexamination Certificate
2001-02-27
2003-02-18
Toomer, Cephia D. (Department: 1714)
Fuel and related compositions
Coal treating process or product thereof
C048S210000, C204S164000
Reexamination Certificate
active
06521003
ABSTRACT:
This invention relates to the treatment of solid carbonaceous material. It relates in particular to a process and installation for treating solid carbonaceous material.
SUMMARY OF INVENTION
According to a first aspect of the invention, there is provided a process for treating solid carbonaceous material, which process comprises heating the material to a temperature of about 1800° C. or higher, by means of a non-transfer arc generated plasma flame, thereby causing components of, or present in, the carbonaceous material to be gasified and thus to be separated or removed from any residual solid material as a hot gas phase, with said any residual solid material being obtained as a product.
The non-transfer arc plasma flame is thus that produced by a non-transfer arc plasma generator or torch comprising an anode and a cathode between which an arc is generated while a gaseous medium passes between the anode and the cathode. The gaseous medium is heated by the arc, typically to a temperature in excess of 3000° C., so that molecules of the gas split into atoms which become ionized and electrically conducting. The non-transfer arc generated plasma flame thus comprises the hot ionized gaseous medium, i.e. a plasma, and an elongate electric arc inside the plasma. The heating may be effected in a high temperature reaction zone in which the plasma generator or torch is located.
The solid carbonaceous material may be in particulate form, and may be present in the reaction zone in the form of a bed, such as a fixed or moving bed. The process may be a batch process. However, it is envisaged that the process will normally be a continuous process in which the bed of solid particulate material passes continuously through the reaction zone. More particularly, the bed of solid carbonaceous material may pass continuously through the reaction zone in a vertically downward direction, with fresh solid particulate carbonaceous material being added continuously to the top of the bed, and solid particulate product, when present, being withdrawn continuously from the bottom of the bed.
The process may include adding fresh solid particulate carbonaceous material to a preheating zone located above the reaction zone, and heating the carbonaceous material in the preheating zone by contacting it with the hot gas phase from the reaction zone. Thus, in the preheating zone, the feedstock may be heated from ambient or room temperature to a temperature of about 1800° C., or higher.
The addition of the fresh solid particulate carbonaceous material to the top of the bed may be at such a rate that the bed moves through the reaction zone at a rate of from 10 mm/min to 90 mm/min, preferably from 40 mm/min to 70 mm/min.
The process may include cooling any residual solid material or solid product in a cooling zone below the reaction zone. The cooling may be effected by contacting the hot solid product with a treatment gas. The treatment gas may thus enter the cooling zone, cool down the hot solid product while it is heated, pass upwardly from the cooling zone into and through the reaction zone, and thereafter into and through the preheating zone. The hot gas phase then comprises spent or used treatment gas, gasified components from the solid carbonaceous material, and any gaseous products formed in the reaction zone.
The treatment gas may be reactive or non-reactive, depending on the solid carbonaceous material used.
The entire flow of treatment gas may thus be introduced through the cooling zone. However, in one embodiment of the invention, a portion of the treatment gas may be introduced directly into the reaction zone, eg directly with the plasma flame, as part of the plasma generating gas. In other words, at least a portion or component of the gaseous medium of the non-transfer arc generated plasma flame may be treatment gas. In this embodiment of the invention, about a third of the total treatment gas required in the reactor, may then enter as part of the plasma generating gas.
The treatment gas may be selected from: an inert gas such as argon, helium and neon; a relatively inert gas such as nitrogen; a more reactive gas such as oxygen; a gas which is liquid at ambient conditions, such as superheated steam, which can then typically be at a temperature in the range of 1000° C. to 1800° C.; a synthesis gas such as a hydrogen-carbon monoxide mixture; a halogen such as chlorine or fluorine; and a mixture of two or more of these gases.
It will be appreciated that, in the event that no solid produce is produced, treatment gas can still be used in the process, with the make-up and addition rate of the treatment gas thus constituting one of the process variables. The make-up and addition rate of the gaseous medium or plasma generating gas can also constitute one of the process variables.
The process is characterized thereby that differing feedstocks can be treated in the process, and the process variables or parameters can be selected to obtain different products. Thus, in one embodiment of the invention, only the solid carbonaceous material may be used as a feedstock to the preheating zone, ie the feedstock consists only of the solid carbonaceous material. The solid carbonaceous material may be selected from coke such as synthetic grade coke, pitch grade coke or petroleum grade coke; waste carbonaceous material such as waste anode material; anthracite; and coal. The process can then be operated to obtain purified carbonaceous material as the solid product, with the components which are gasified in the reaction zone being impurities or undesirable components present in the feedstock material. Instead, the process can be operated to obtain one or more desired gasified or gaseous components are present in the hot gas phase, with any residual solid material being of little or no value. The components present in the gas phase may then be recovered as products.
In another embodiment of the invention, a mixture of the solid carbonaceous material and a solid non-carbon material selected from a metal or metal-containing mineral, eg chromite; a non-metal compound such as an oxide, eg silica oxide, particularly an oxide capable of being converted to a carbide; and a ceramic, may be used as a feedstock to the preheating zone. The process can then be operated to obtain a valuable solid product other than coke.
In yet other embodiments of the invention, the make-up and/or addition rate of the treatment gas and/or the plasma generating gas can be varied or altered to obtain both valuable gaseous components and valuable solid products, in some cases. The treatment gas make-up will be dependent on the particular feedstock that is used, as well as the recovery system used to recover valuable components from the gas phase.
The feedstock may have a purity between 70% and 99.9% (by mass), and more typically between 80% and 99.9% (by mass), so that it then contains between 0.1% and 20% (by mass) impurities. When coke is used as feedstock, or as a component thereof, the impurities are typically present in the form of 1.0% to 1.6% bonded nitrogen, and at least 0.2% sulphur (by mass).
The particle size distribution of the feedstock is typically from 1 mm to 30 mm in diameter or cross-section, preferably from 3 mm to 15 mm.
As stated hereinbefore, the feedstock is heated to a temperature of about 1800° C. or higher, ie the reaction temperature in the reaction zone is not less than about 1800° C. At temperatures below about 1800° C., the removal of impurities such as nitrogen and sulphur from carbonaceous material such as coke is excessively time consuming. The upper limit of the temperature to which the material is heated, is set by the formation of undesirable species in the gas phase. Typically, however, the maximum reaction temperature may be between 1800° C. and 2600° C., when the feedstock consists only of carbonaceous material such as coke. Preferably, the reaction temperature is then at least 2000° C., eg between 2100° C. and 2300° C. Typically, the maximum reaction temperature may be up to 4000° C., when the feedstock comprises a carbonaceo
Lombaard Ruan
Mast-Ingle Julian Charles
Swanepoel Jacobus
Ladas & Parry
Sasol Technology (Pty) Limited
LandOfFree
Treatment of solid carbonaceous material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Treatment of solid carbonaceous material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Treatment of solid carbonaceous material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3156210