Process and reactor for producing synthesis gas

Abstract

For producing synthesis gas by autothermal reformation of gaseous, liquid and/or solid fuels, the fuel is reacted with an oxidizing agent in a reaction space at a pressure of 10 to 120 bar and a reaction space temperature of 800 to 2,000 C. to obtain synthesis gas, wherein the oxidizing agent is introduced centrally in the upper region of the reaction space and wherein a flame is formed in the reaction space. The oxidizing agent is introduced into the reaction space separate from the fuel.

Claims

1. A process for producing synthesis gas by autothermal reformation of gaseous, liquid and/or solid fuels, in which the fuel is reacted with an oxidizing agent in a reaction space at a pressure of 10 to 120 bar and a reaction space temperature of 800 to 2,000 C. to obtain synthesis gas, wherein the oxidizing agent is introduced centrally in the upper region of the reaction space and wherein a flame is formed in the reaction space, wherein the oxidizing agent is introduced into the reaction space separate from the fuel, wherein the fuel is introduced at one or more points into a recirculation zone of the flame, wherein the recirculation zone is defined as the zone wherein the materials present in the flame flow back to the top, and wherein the fuel is introduced into the recirculation zone along with a moderator such that a spray cone is formed within the recirculation zone.

2. The process according to claim 1, wherein the fuel is introduced into the recirculation zone of the flame at more than one point.

3. The process according to claim 1, wherein the oxidizing agent is introduced into the reaction space with a swirl.

4. The process according to claim 1, wherein the oxidizing agent is introduced into the reaction space along with a moderator.

5. The process according to claim 1, wherein the fuel is introduced into the reactor in atomized form.

6. The process according to claim 5, wherein a moderator is used as atomizing medium.

7. The process according to claim 1, wherein fuel is introduced into the reaction space via several inlets and that different fuels are supplied through the individual fuel inlets.

8. A reactor for producing synthesis gas in a reaction space with an inlet for fuel and an inlet for oxidizing agent, wherein the supply conduit for the oxidizing agent is provided centrally in the upper region of the reaction space, and with an outlet for the synthesis gas, wherein separate supply nozzles are provided for the oxidizing agent and the fuel into the reaction space such that the fuel is introduced at one or more points into a recirculation zone of the flame, wherein the recirculation zone is defined as the zone wherein the materials present in the flame flow back to the top, wherein the fuel is introduced into the recirculation zone along with a moderator via the fuel supply nozzles, such that a spray cone is formed within the recirculation zone.

9. The reactor according to claim 8, wherein around the inlet for the oxidizing agent an annular gap is provided for supplying a moderator into the reaction space.

10. The reactor according to claim 8, wherein a plurality of supply nozzles for the fuel are arranged uniformly distributed around the circumference of the reaction space.

11. The reactor according to claim 10, wherein the axes (B.sub.i) of the supply nozzles for the fuel intersect on the reaction space axis (R).

12. The reactor according to claim 10, wherein the axes (B.sub.i) of the supply nozzles for the fuel intersect in a plane which is vertical to the reaction space axis (R).

13. The reactor according to claim 10, wherein the axes (B.sub.i) of the supply nozzles for the fuel are inclined at an angle of 1 to 180 to the reaction space axis (R).

14. The reactor according to claim 8, wherein the supply nozzles for the fuel include a spray angle of 10 to 120.

15. The reactor according to claim 8, wherein at least in the lower region of the reaction space a catalyst bed is provided.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further developments, advantages and possible applications of the invention can also be taken from the following description of exemplary embodiments and the drawing. All features described and/or illustrated form the subject-matter of the invention per se or in any combination, independent of their inclusion in the claims or their back-reference.

(2) In the drawing:

(3) FIG. 1a schematically shows a section through a reactor of the invention according to a first embodiment with the representation of the oxidant and fuel injection as well as the recirculation zone of the flame,

(4) FIG. 1b shows a top view of the reactor according to FIG. 1a,

(5) FIG. 2 shows a section through a second embodiment of the invention with lateral gas outlet,

(6) FIG. 3a shows a section through a reactor according to a third embodiment with fuel supply nozzles arranged in the lower region of the reactor,

(7) FIG. 3b shows a top view of the reactor according to FIG. 3a,

(8) FIG. 4 shows a section through a reactor according to a fourth embodiment, wherein the fuel supply nozzles are oriented differently, and

(9) FIG. 5 shows a reactor according to the invention with another diameter/length ratio.

DETAILED DESCRIPTION

(10) By way of example, the succeeding detailed description of the present invention refers to the use of a liquid fuel such as oil or a vapor/oil mixture. The invention is, however, not limited thereto and can equally be applied for other suitable fuels.

(11) The reactor 1 according to the invention for producing synthesis gas by partial oxidation and autothermal reformation includes a reaction space 3 surrounded by a reactor wall 2, in whose upper region (reactor head) a supply nozzle 4 for oxidizing agent is centrally provided in vertical direction. In the illustrated embodiment, a two-fluid nozzle is shown by way of example, in which the oxidizing agent, in particular technically pure, compressed and preheated oxygen, is supplied through an inner duct 5. A moderator, in particular steam, carbon dioxide or a mixture thereof, can be added to the oxidizing agent. Around the inner duct 5 an annular duct 6 is provided, through which a further part of the moderator is introduced into the reaction space 3. If necessary, the supply nozzle 4 for the oxidizing agent and the moderator can be cooled.

(12) At an angle of 10 to 30, in particular about 20, relative to the reactor space axis R three supply nozzles 7 for fuel are provided uniformly distributed around the circumference of the reactor 1. The axes B.sub.i of the supply nozzles 7 intersect on the reactor space axis R (cf. FIG. 1b). In the embodiment shown in FIG. 1, the supply nozzles 7 likewise are provided in the region of the reactor head, so that the fuel is introduced into the reaction space 3 from above. As liquid fuel, for example oils, suspensions of water or oil or of finely ground solids with a liquid (slurries) can be used. To the fuel to be reformed a part of the above-mentioned moderator can be added before the inlet to the reactor 1, in the inlet to the reactor 1, or via a separate concentric nozzle around the inlet. The exit velocity and direction of the fuel and possibly of the moderator can be chosen such that the fuel is added to the recirculation zone of the flame 9 as uniformly and widely as possible, in order to achieve a residence time in the reactor 1 as long as possible.

(13) The liquid fuels are atomized by means of a spray nozzle which has a rather large spray angle of 10 to 120. The atomization can be effected by pressure atomization or by means of a two-fluid nozzle, wherein the moderator can be used as atomizing medium. Such atomizer is disclosed for example in EP 1 016 705 B1 for use in a burner. Beside liquid fuels, the use of gaseous or solid fuels also is conceivable, in which the atomization then can be omitted. To avoid overheating, the supply nozzles 7 can be cooled actively.

(14) In the bottom region of the reactor 1, an outlet 8 for withdrawing the synthesis gas (reformate) is centrally provided. Such configuration of the gas outlet is typical when the gas is supplied to a succeeding quenching nozzle (not shown) and in addition liquid slag possibly must also be discharged from the reactor.

(15) In dependence on the feedstock, the reaction space 3 can be designed differently. In essence, it is a cylindrical hollow space which includes a refractory lining or in particular in use of strongly ash-containing fuels is defined by a cooling screen, along which the liquid slag can flow off.

(16) In particular in the case of gaseous feedstock, a non-illustrated catalyst bed can be provided in the lower region of the reactor 1, in order to achieve a better degree of conversion at low gasification temperatures.

(17) When introducing the oxidizing agent through the supply nozzle 4, the same reacts with the reformate generated in the reactor 1 by forming a flame 9. Through the inlet of the oxidizing agent and due to the reaction with the reformate, a flow with the recirculation zones 11 is formed in the reaction space 3. Along with a moderator, in particular steam or carbon dioxide, the fuel is introduced into the reactor 1 via the supply nozzle 7 such that the spray cone with the main evaporation zone 10 lies in the recirculation zone 11. In this way, the residence time of the fuel (reducing agent) in the reaction space 3 can be influenced positively. With the same hydrodynamic residence time, a higher conversion is achieved.

(18) The height of the inlet for the fuel and the angle to the reactor axis R substantially can be chosen freely. It must be ensured, however, that the oxidation zone (flame) and the main evaporation zone are accommodated in different spatial regions in the reactor 1.

(19) In dependence on the configuration of the reaction space, commissioning or starting the reactor 1 is effected differently. A refractory lined reactor usually is heated with a heat-up burner to such an extent that the masonry can provide a sufficient ignition energy. Before the oxygen is added to the reaction space 3, a sufficient amount of combustible gas must already be present in the reaction space 3. This can be achieved in that synthesis gas or hydrogen are supplied. Moreover, the energy of the hot walls initially can be utilized for the reformation of the fuel, so as to provide a reformate which reacts with the oxidizing agent. If the walls of the reaction space 3 are cooled, however, the ignition energy must be provided in some other way, for example by means of a heat-up burner which frequently remains in the reactor 1 after the start of the main reforming reactions.

(20) FIG. 2 shows a second embodiment of the invention, in which the outlet 8 for the synthesis gas is arranged laterally at the reactor 1. Such configuration is common practice in use of a non-illustrated waste heat boiler. Moreover, this embodiment corresponds to the reactor 1 according to the first embodiment.

(21) FIG. 3 shows a further embodiment of the invention, in which in contrast to the embodiment of FIG. 1 the supply nozzles 7 for the fuel are arranged in the lower region of the reactor 1, and therefore the angle is >90, in particular about 135. In this embodiment, the fuel is introduced into the recirculation zone 11 such that it substantially enters into the upward flow.

(22) FIG. 3b shows the projection of the supply nozzles 7 for the fuel on one plane. Like in the first embodiment, the fuel nozzle axes B.sub.i intersect in a point which lies on the reactor space axis R.

(23) It is, however, not necessary that the axes B.sub.i intersect in one point. In the embodiment of FIG. 4 a projection of a case is shown, in which the fuel inlets 7 all lie on a common plane vertical to the reactor space axis R. The angles each have the same value. However, the axes B.sub.i do not intersect in a common point. The points of intersection of the axes B.sub.i however, lie in one plane which is oriented vertical to the reactor space axis R. With this arrangement of the fuel inlets, a slight swirl can be generated in the reactor 1, which positively influences the residence time of the fuel in the reactor 1.

(24) In the embodiment of FIG. 5 a large diameter/length ratio of the reaction space 3 is shown as compared to the embodiments of FIGS. 1 to 4. The oxidant inlet here has a large swirl number, so that the flame 9 becomes very short. The fuel is supplied via supply nozzles 7, which lie in a plane vertical to the reactor space axis R.

(25) With the invention, an optimum residence time of the fuel in the reaction space 3 is achieved by the separate addition of oxidizing agent and reducing agent. With the same hydrodynamic residence time, a higher conversion is obtained. The supply nozzles 4, 7 for the oxidizing agent and the fuel, respectively, are designed and optimized independent of each other, so that no compromises must be made. Due to the achieved great spatial utilization of the reaction space, a very high conversion can be achieved. The efficiency of the process can be optimized and the generation of by-products such as soot can be reduced.

LIST OF REFERENCE NUMERALS

(26) 1 reactor 2 reactor wall 3 reaction space 4 supply nozzle for oxidizing agent 5 inner duct 6 annular duct 7 supply nozzle for fuel 8 outlet 9 flame 10 spray cone with main evaporation zone 11 recirculation zone B.sub.i fuel nozzle axes R reactor space axis