March 16, 1954 w_ J, MATTOX 2,672,410 GASIFICATION OF CARBONACEOUS SOLIDS Filed D60. 1, 1949 EXCHANGER 24 O2 INL£T /4/ STEAM INLE7"_ 2 f ' f Patented Mar. 16, 1954 2,672,410 UNITED STATES PATENT OFFICE 2,672,410 .GASIFIGATION OF CARBONACEOUS SOLIDS William J. Mattox, Baton Rouge, La.,assignor to Standard Oil Development Company, a corpo ration of Delaware Application December 1, 1949, Serial No. 130,493 15 Claims. (01. 48-206) 2 The present invention relates to the production the gas generator in a so-called single-vessel sys of gases fromynon-gaseous carbonaceous ma tem or a continuous circulation of suspended terial, and speci?cally to the production of gas solid carbonaceous material to a separate heater mixtures containing carbon monoxide and hy in which heat is generated by combustion of the drogen, such as water gas, from such carbona carbonaceous constituents of the residue, and re ceous materials as coke and coals, wherein the circulation of the highly heated ?uidizable com formation of carbon dioxide is repressed by the bustion residue to the gas generation zone to sup~ addition of an alkali metal halide. ply the heat required therein in a so-called two It has long been known that solid fuel ma vessel system. terials, such as coke, coal, and the like, may be 10 The single-vessel system would as such; be converted into more valuable gases which can more desirable than the two-vessel system be more easily be handled and more efficiently uti cause the latter requires the circulation of tre lized for a greater variety of purposes. One of mendous quantities of solids between the two the most widely practiced gas-generating con vessels, a factor which presents serious problems versions is the so-called water-gas process in 15 of design and equipment maintenance. However, which solid fuels, such as coal or coke of any single-vessel operation involves the disadvan origin, are reacted with steam at temperatures tage of product gas dilution with nitrogen and of about 1400" to 2000° F. to produce water gas carbon dioxide when air is used as the combus mixtures of carbon monoxide and hydrogen in tion-supporting gas. Since technically pure oxy varying proportions, depending mainly on the 20 gen has become available at relatively low cost, time of contact, conversion temperatures, and nitrogen dilution may be eliminated by the use steam feed rate. The overall water gas reaction of oxygen in a commercially feasible operation. being endothermic, heat must be supplied; this However, carbon dioxide formation remains a is usually accomplished by the combustion of a problem seriously affecting the practicability of portion of the carbonaceous feed with an oxidiz the otherwise preferable single-vessel system. ing gas, such as oxygen, at about 1600°-2400° F. Recent investigations have shown, for example, The combustion reaction may be carried out that in a gasi?cation ‘operation employing 2300 either simultaneously with the water gas reac lbs. of powdered coal, 1700 cu. ft. of oxygen and tion or alternately in a make-and-blow fashion. 2000 lbs. of steam per hour to produce 70,000 cu. The water gas process permits the production 30 ft. of water gas, the product gas contains about of gas mixtures of varying composition and 16% of CO2. This carbon dioxide represents a B. t. u. content. The process as such, therefore, total loss as far‘as the output of hydrogen or is suited not only for the production of fuel gases synthesis gas is concerned. The significance of but also for the production of gases for hydro this loss will be appreciated when it is borne in genation processes and particularly for the cata 35 mind that the present methods of synthesis gas lytic synthesis of hydrocabons and oxygenated production account for about 60% of the cost of organic compounds from C0 and H2, which proc synthetic fuel production. Although CO2 forma ess requires H2:CO ratios, depending on the tion may be reduced to a certain extent by ad products desired and reaction conditions to be justing operating conditions, this can be done maintained, varying within limits of about 0.5 to 40 only at the expense of generator capacity. 2.5 or more volumes of H2 per Volume of CO‘. The present invention substantially alleviates The technical utilization of the water gas proc these difficulties and a?ords various additional ess, particularly for hydrogenation and for pro advantages as will appear from the description duction of synthesis gas, has been impeded by given below wherein reference will be made to difficulties encountered particularly in heat sup 45 the accompanying drawing. ply, continuity of operation, and limitations in In accordance with the present invention, car temperature imposed by low ash fusion or soften bon dioxide formation is considerably reduced ing points. The problem of continuity of opera and even substantially eliminated in water gas tion has been satisfactorily solved heretofore by generators wherein carbonaceous solids are gasi the application of the ?uid solids technique 50 ?ed with steam and oxygen, by the addition to wherein the carbonaceous charge is reacted in the generator of small proportions of a halide the form of a dense turbulent mass of ?nely di which at the reaction conditions’ yields halogen vided solids ?uidized by ‘the ‘gaseous reactants and/or a volatile halogen compound.” and products. Heat is generated either by par , 'Alkali metal halides, such as the chlorides, bro tial combustion of carbonaceous materials within 65 mides, and ?uorides of sodium, potassium, vlith 2,672,410 3 4 ium, rubidium, and cesium, or mixtures of such ~ control the Hz/CO consumption ratio of the syn halides are particularly suitable for the purposes thesis reaction. of the invention, but alkaline earth metal halides, The process of the invention may be carried such as those of barium, calcium, and magnesium, out in any system wherein carbonaceous solids may also be used. Sodium chloride, because of are reacted with steam and oxygen to produce its ready availability and low cost, is the preferred gas mixtures of the type of water gas. Any con~ addition agent. Proportions of about 0.01—5%, ventional gas generator working on this principle preferably about 0.05-l%, ‘by weight of alkali may be adapted for the purposes of the invention, metal halide based on carbon supplied to the independent of the special technique involved, i. e. generator, are suitable to depress C02 forma 10 the essential advantages of the invention may be tion from about 15-20% to less than about 5% realized in ?xed bed, moving bed, ?uid bed or of the product gas. true suspension operation. However, ?uid opera While it is not intended to limit the present tion is preferred, because of its superior charac invention by any theory of the reaction mecha teristics of gas-solids and solids-solids contact nism involved, it is believed that the effect of 15 and its improved heat transfer characteristics, the addition of halides may be explained as fol which greatly enhance the inhibiting and cata lows. Alkali metal halides, such as NaCl, react lytic effects of the addition agents of the inven with steam in the presence of oxygen at the gas tion. A system of this preferred type is illus generation temperatures of about 1800°-2000° F., trated in the drawing, the single ?gure of which to yield free halogen and/or hydrogen halide and 20 depicts schematically an expanded flow plan of alkali metal oxide and carbonate. Small amounts the process. _ of halogen or volatile halogen compounds are Referring now to the drawing, the system shown known to suppress the formation of CO2 in favor consists essentially of a conventional ?uid-type of an exclusive formation of CO in the combus water gas generator [0 and metal halide recover tion of carbonaceous materials. Since CO2 for- - ing equipment 30 and 40, the functions and coop mation in the water gas generator is largely due eration of which will be forthwith described using to a complete combustion of carbon to CO2, the the gasi?cation of a low temperature coke in the halogen or halogen halide supplied by the alkali presence of NaCl as an example. It should be metal halide will act to suppress CO2 formation understood, however, that the system may be op in the water gas reaction. 30 erated in a similar manner for the gasi?cation of It will be appreciated from the foregoing that other carbonaceous solids, such as various coals, the addition of halides in accordance with the in the presence of other suitable halides. invention has nothing in common, regarding its In operation, fresh coke ground to a particle purpose and effect, with the known addition of size passing 4 mesh with a major proportion such agents catalyzing the water gas reaction as passing 60 mesh is fed from a feed hopper, pref alkali metal carbonates, nickel, heavy metal erably a lock hopper I, into a standpipe or other oxides or sul?des, etc., or mixtures thereof which conveying means 3 into generator Ill. The coke have no inhibiting effect on the formation of 00:. may be preheated to temperatures of about 400° It is, however, a particular advantage of the 800° F. in hopper I by means of product gases present invention that such catalytic agents as passed therethrough via lines 6 and 8, or in any alkali metal oxides or carbonates are formed as other conventional means. Sea water is intro the solid residue of the liberation of halogen or duced through line 5 into standpipe 3 in amounts hydrogen halide.