US2971829A

US2971829A - Hydrocarbon gasification

Info

Publication number: US2971829A
Application number: US782471A
Authority: US
Inventors: Jacobus J Van Rossum; Marinus J Hofstede
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1958-12-23
Filing date: 1958-12-23
Publication date: 1961-02-14
Anticipated expiration: 1978-02-14

Description

1961 .1. J. VAN ROSSUM ETAL 2,971,829

HYDROCARBON GASIFICATION 2 Sheets-Sheet 1 Filed Dec. 23, 1958 FIG.

INVENTORS:

JACOBUS J. VAN ROSSUM MARINUS J. HOFSTEDE THEIR ATTORNEY Feb. 14, 1961 Filed Dec. 23, 1958 2 Sheets-Sheet 2 FIG. 4

INVENTORS:

JACOBUS J. VAN ROSSUM MARINUS J. HOFSTEDE BYJ THEIR ATTORNEY United States Patent 1 2,971,829 HYDROCARBON GASIFICATION Jacobus J. Van Rossum and Marinus J. Hofstede, Delft, Netherlands, assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Dec. 23, 1958, Ser. No. 782,471 3 Claims. (Cl. 48-196) This invention relates to improvements in a process for the preparation of gas mixtures containing hydrogen and carbon monoxide by partial combustion of liquid or gaseous hydrocarbon materials with an oxygen-containing gas. The expression oxygen-containing gas is used herein to include air, oxygen-enriched air and substantially pure oxygen.

In a known process for the manufacture of synthesis gas through patrial combustion of a first and second fluid with usually the addition of steam, one of the fluids (which may be either a carbonaceous fuel or an oxygencontaining gas) is fed tangentially into a first zone (sometimes described as a whirl chamber) which has a boundary of a surface of revolution with a velocity suflicient to form an annular, rotating column which advances forwardly toward an open throat in one end of the whirl zone. There is a gradual reduction in the cross section of the whirl zone and accordingly a like reduction in the cross section of the annular rotating column to the dimen-' sion of the throat. The other fluid (which may be either a carbonaceous fuel or an oxygen-containing gas but differing from the first fluid) is injected outwardly in a hollow cone from a conduit disposed axially within the whirl chamber into the encompassing rotating, annular column of the first fluid. This injection occurs adjacent the restricted throat. There occurs a rapid expansion of the outwardly moving, rotating column from the restricted throat into a sharply enlarged combustion or reaction zone which also has a boundary wall of substantially a surface of revolution. Normally steam is supplied to the combustion chamber through the tbroat-inthe rotating annular column, having been admitted with the first fluid in the formation of the rotating column. If the hydrocarbon used is liquid the annular rotating column will generally be the oxygen-containing gas, with the liquid hydrocarbon being injected outwardly into that column. However, if the hydrocarbon is gaseous, it may be employed to form the outer, rotating annular column and the oxygen-containing gas (here oxygen or a very rich oxygen stream) will be centrally introduced.

The process of the foregoing description is designed to provide an intimate mixing of fuel and combustion air supplied to the combustion zone. The formation of double gas vortices as described in U.S. Patent No. 2,806,517, Te Nuyl, leads to the desired combustion without the requirement of excess air. It has developed that for the optimum operation of the process, there should be rela- I 2,971,829 Patented Feb. 14, 1961 i Fig. 1;

tively uniform distribution of the gas'supplied to the flected in the combustion zone, leading to irregularities of distribution which interfere with the reaction.

It is an object of this invention to provide an improved process wherein there is a more uniform distribution of the gases supplied to the reaction zone. This and other objects will become more apparent with a reading of the following disclosure, taken in conjunction with the drawings wherein:

Fig. 1 is a longitudinal cross-section of an apparatus suitable for the performance of theprocessof the in- V vention;

Fig. 3 is a graph of the circumferential pressure profile of an apparatus of the general design of that of Figs. 1 and 2, taken at the throat of the apparatus, showing the variations of pressure around the full 360 circumference of the throat; and

Fig. 4 is a circumferential pressure profile of an apparatus having a design generally like that of Patent No. 2,806,517, again with the profile being taken at the throat of the apparatus, showing the variations of pressure around the full 360 circumference of the throat.

It has now been discovered that the annular rotating column of gas supplied to the combustion zone of the aforementioned described process may be provided with a more uniform pressure distribution when the first fluid is introduced into the first zone (Whirl zone) through the several openings at an angle defined by a tangential line to an imaginary cylinder having a diameter not greater than two-thirds of the diameter of the first zone and not less than the diameter of the axially disposed conduit (obstruction) of that zone, the latter referred to conduit being the conduit through which the second fluid is furnished. Furthermore, each of the several openings into the first zone is a slot of a restricted area designed to provide a pressure drop thereover in excess of the maximum pressure diiferential existing between any two points in the encircling plenum. In the preferred embodiment the first fluid is admitted to the plenum at an angle designed to impart to the entering first fluid the same directional rotation within the plenum as exhibited by the first fluid flowing through the first zone (whirl zone). The pressure drop across the individual slots is preferably in excess of two and one-half times the largest pressure variant in the plenum.

With reference to the drawings, the apparatus illustrated in Figs. 1 and 2 includes a combustion chamber 11 enclosed in a refractory wall 12 which is connected axially through a throat 13 in one end thereof to an axially aligned whirl chamber 15. Both chambers have circular cross-sections and in the instance of the whirl chamber there is a gradual tapering (a cone formation) to the dimension of the restricted throat connecting the two chambers. This gradual reduction in the cross-section of the whirl chamber or zone results in a corresponding reduction in the cross-section of the annular rotating column of gas formed therein. It will be seen that the first fluid, normally oxygen or oxygen enriched air, is admitted through a line 14 and a tangential opening 16 to the interior of a plenum 17 which encircles the whirl chamber, being separated by a cylindrical bushing 18. Steam may be and is customarily introduced with the air to the plenum and from there through the whirl chamber to the combustion zone.

The wall of the cylindrical bushing 13 separating the plenum and whirl chamber is relatively thick and is provided with eight elongated slots of limited cross-section, especially designed to obtain a large drop in pressure. In the instance where the gasification process is carried on at a relatively high pressure, say in excess of 10 atm., it is advantageous to take one-half of an atmosphere pressure drop across the slots. Generally speaking, it is preferred that the pressure drop across the individual slots be in excess of two and one-half times the largest pressure variant existing in the surrounding plenum. It is also desirable to round oflt'the walls of the several slots on the inlet (upstream) side, thus permitting the gas stream to pass through the, slots with less disturbance, and thereby promoting a more uniform inflow. The gas supplied to the plenum rotates in the same direction as the stream passing through the whirl chamber. 1

far end a nozzle'22 which terminates adjacent the throat The hydrocarbon fluid is injected outwardly in a hollow cone into the rotating annular column of air.

, The several elongated slots of the whirl chamber wall open at an angle defined by a tangential line to the cylindrical feed tube support. By directing the slots in this fashion a larger degree of homogenizing may be obtainedthan in the instance of the arrangement of the slots in a tangential direction to the inner diameter of the whirl chamber. The angle of introduction of the air through the several slots of the whirl chamber wall is preferably defined by a tangential line to an imaginary cylinder having a diameter not greater than two-thirds the diameter of the whirl chamber nor less than the diameter of the axially disposed conduit lying within the whirl zone. In this connection the term axially disposed conduit (obstruction) includes the cylindrical support 23.

The lower section of the wall of the whirl chamber, that is the portion adjoining the combustion chamber, is provided with an internal annular channel 25 which is supplied with cooling water through an internal inlet conduit -27. The outlet line for the'water passing through the annular channel is a second internal conduit 28. The wall of the combustion zone is likewise supplied with a cooling jacket 36 which completely encompasses'thc wall of that zone. Here the cooling water is introduced through a line 32 to the down-stream side of the combustion zone. The water circulates throughout the jack et 30, leaving via an exit line 33.

It has been found that the process of the invention may be successfully practiced with an apparatus of the following dimensions:

Cross-sectional area of supply line 1 4 sq. mm 7050 Largest inside diarnetcr of the plenum 17 mm 2 80 Outside diameter of thewhirl chamber wall mm 190' Inside diameter of the whirl chamber wall -mm..- 150 Number of slots in the whirl chamber wall 8 Width of the slots mm.. 3 Effective length of the slots mm- 15 Height of the slots mtn 183 -Diameter of the imaginary cylinder in relation to-which the slots are arranged tangentially mm 78 Effective length of the slots referred to in the data 20 table above is the actual lengthof a slot of like effectiveness not utilizing the rounding ed on the inlet (upstream) side of the slots. The height of the slots is the dimension of the slot parallel to the axis of the whirl chamber. The width of the slot is the smallest dimension of the slots, best illustrated in Fig. 2'. It was found that witlrthe use of the apparatus having the above-mentioned dimensions the pressure drop over the several slots was approximately two and one-half times as large as the largest prmsure variant in the plenum.

The advantages to be had in the use of the processof the invention are strikingly demonstrated in the graphs of Figs. 3 and 4. The graphs respectively depict the circumferential pressure profiles obtained. in the operation of an apparatus of the design of Figs. 1 and.2 and ofa more conventional apparatus of the general design of Patent No. 2,806,517. Both apparatus had a rated capacity of 3.00 kilograms per hour of hydrocarbon. Structurally, the two apparatus were essentially alike except for the design of the slots and the angle of introduction of the air to the whirl chamber. Theair inlet slots of the whirl chamber Wall of the apparatus of Fig. 4 are designed for a minimum pressure drop. And in this particular, instance the walls ofthe several ports (12in number) have the, cross-section of .an air foil, rounded and of greater thickness at the inlet side and tapering to the outlet side. Such a design is recognized to give a minimum pressure drop. In contrast the several ports of the apparatus of Figs. 1 and 2, the operation of which is reported in Fig. 3 were purposely designed to provide a significant pressure drop of approximately one-half an atmosphere with theapparatus operating at a pressure somewhat in excess of atmospheres In Figs. 3

. and .4,-P .;stands for reference pressure .and R is a pressure taken around the throat of the respective ap paratus. The reference pressurein theinstance of Fig. 3 is approximately 80 mm. mercury gaugeand in the other graph approximately 90 mm. mercury gauge. The slots of the apparatus of Fig. 3 had a width of 3 mm. and a height of approximately 100 mm." The air foil ports of the other apparatus presented a minimum width of approximately. 3.7 mm. and a height of approximately- 85 The latter apparatusincorporated 12 air foils. Theg'raph of each of the two figures presents a circumferential pressure profile taken at the throat of the respective apparatus, that is at the restricted passageway connecting the whirl chamber and the combustion zone. The data of the ordinates of both graphs is the percentage variation. obtained ,in the operation of the respectiveprocesses. It will be seen that there is a significant improvement in the pressure distributions to be had in the use .of the improved process, there the maximumpressure variation is 2.3% whereas in the other case the pressure variation was approximately 10%.

We claim as our invention:

1. In a method of preparing gas mixtures contain ing predominently hydrogen and carbon monoxide by partial combustion of a first and second fluid, one of the fluids. being a carbonaceous fuel and the otheran oxygene containing gas,;wherein the first fluid is introduced from an outer encircling plenum at an angle through a plurality of openings into a first zone having aboundry of a surface of. revolution with a velocitysufiicient to form an annular rotating column of said first fluid advancing forwardly toward an open throat in one end of said zone and wherein there is a gradual reduction in the cross section of said zone and accordingly of the annular rotating column to the dimension of said throat and wherein there is an injection of thesecond fluid outwardly from aconduit disposed axially. within said first zone into the rotating annular column of the first fluid and wherein there occurs a rapid expansion of the outwardly moving, rotating column from the restricted throat into a sharply enlarged combustion zonehaving a boundary wall of substantially a surface of revolution, the improvement comprising introducing the first fluid into the first zone through the several openings at an angle defined bya tangential line-to an imaginary cylinder having adiameter not greater than two-thirds of the diameter of the first zone andv not less than the diameter of the axially disposedconduit of said zone, and providing a pressure drop over each. of saidiplurality of openings between the plenumfandthe. first zone in excess of the maximum pressurev differential existing between any two points in the plenum.

2. ,A process in accordance with claim l'wherein the first fluid is admitted to the plenum at an angle adequate to impart to the entering first fluid the same direction of rotation within the plenum as exhibited by that portion References Cited in the file of this patent UNITED STATES PATENTS ,517 Te Nuyl Sept. 17, 1957 FOREIGN PATENTS 720,120 7 Great Britain Jul 31. 1951

Claims

1. IN A METHOD OF PREPARING GAS MIXTURES CONTAINING PREDOMINENTLY HYDROGEN AND CARBON MONOXIDE BY PARTIAL COMBUSTION OF A FIRST AND SECOND FLUID, ONE OF THE FLUIDS BEING A CARBONACEOUS FUEL AND THE OTHER AN OXYGENCONTAINING GAS, WHEREIN THE FIRST FLUID IS INTRODUCED FROM AN OUTER ENCIRCLING PLENUM AT AN ANGLE THROUGH A PLURALITY OF OPENINGS INTO A FIRST ZONE HAVING A BOUNDRY OF A SURFACE OF REVOLUTION WITH A VELOCITY SUFFICIENT TO FORM AN ANNULAR ROTATING COLUMN OF SAID FIRST FLUID ADVANCING FORWARDLY TOWARD AN OPEN THROAT IN ONE END OF SAID ZONE AND WHEREIN THERE IS A GRADUAL REDUCTION IN THE CROSS SECTION OF SAID ZONE AND ACCORDINGLY OF THE ANNULAR ROTATING COLUMN TO THE DIMENSION OF SAID THROAT AND WHEREIN THERE IS AN INJECTION OF THE SECOND FLUID OUTWARDLY FROM A CONDUIT DISPOSED AXIALLY WITHIN SAID FIRST ZONE INTO THE ROTATING ANNULAR COLUMN OF THE FIRST FLUID AND WHEREIN THERE OCCURS A RAPID EXPANSION OF THE OUTWARDLY MOVING, ROTATING COLUMN FROM THE RESTRICTED THROAT INTO A SHARPLY ENLARGED COMBUSTION ZONE HAVING A BOUNDARY WALL OF SUBSTANTIALLY A SURFACE OF REVOLUTION, THE IMPROVEMENT COMPRISING INTRODUCING THE FIRST FLUID INTO THE FIRST ZONE THROUGH THE SEVERAL OPENINGS AT AN ANGLE DEFINED BY A TANGENTIAL LINE TO AN IMAGINARY CYLINDER HAVING A DIAMETER NOT GREATER THAN TWO-THIRDS OF THE DIAMETER OF THE FIRST ZONE AND NOT LESS THAN THE DIAMETER OF THE AXIALLY DISPOSED CONDUIT OF SAID ZONE, AND PROVIDING A PRESSURE DROP OVER EACH OF SAID PLURALITY OF OPENINGS BETWEEN THE PLENUM AND THE FIRST ZONE IN EXCESS OF THE MAXIMUM PRESSURE DIFFERENTIAL EXISTING BETWEEN ANY TWO POINTS IN THE PLENUM.