WO2010076499A2

WO2010076499A2 - Method and device for producing and purifying a synthesis gas

Info

Publication number: WO2010076499A2
Application number: PCT/FR2009/052563
Authority: WO
Inventors: Jean-Xavier Morin
Original assignee: Jean-Xavier Morin
Priority date: 2008-12-16
Filing date: 2009-12-16
Publication date: 2010-07-08
Also published as: WO2010076499A3; CA2747357A1

Abstract

The invention relates to a method for producing and purifying a synthesis gas using a carbon fuel, consisting of carrying out gasification in a first reactor (1A) at a temperature of between 780 and 1150°C and carrying out a purification of the resulting gas in a second reactor (2A). According to the invention: said gasification is carried out using a first reactor loop with a fast fluidised bed (1) including said first reactor (1A) supplied with an oxidiser, a first associated cyclone separator (1B) and a first duct (1C) for returning the solids towards the first reactor (1A); and the purification is carried out using a second reactor loop with a fast fluidised bed (2) including said second reactor (2A) fluidised by the gas resulting at the output of the first cyclone separator (1B), a second associated cyclone separator (2B) and a second duct (2C) for returning the solids towards said second reactor (2A), the second reactor (2A) operating at a temperature of about 600°C in the lower portion and of about 400°C in the upper portion.

Description

PROCESS AND DEVICE FOR PRODUCTION AND PURIFICATION

OF SYNTHESIS GAS

The invention relates to a method and a device for producing and purifying synthesis gas.

Gasification technology for carbonaceous fuels of fossil and non-fossil origin is an unavoidable step in the progressive replacement of current hydrocarbons of the oil or natural gas type for the production of energy, the production of synthetic fuels and finally the production of intermediate products. synthetic chemicals. In particular, the gasification of biomass has become strategic because it offers a viable alternative in the long term, after the depletion of fossil fuel resources, while controlling the release of carbon dioxide into the atmosphere, which is considered responsible. future climate change.

To carry out this gasification, various routes are possible depending on the desired final quality of the gas: either an air gasification of which the gas produced has a low heating value (LPV) resulting from the presence of the nitrogen of the gas. air and which is only used for thermal applications, ie gasification with oxygen and with water vapor, oxygen coming from an air separation unit whose gas produced, which has a Average ICP, is used, after extraction of the contained carbon dioxide, as synthesis gas with carbon monoxide and hydrogen or converted into hydrogen in the ultimate way.

Finally, it is possible to carry out a gasification in the thermochemical cycle, without the need for an oxygen production unit, whose produced gas has an average ICP, which can be used as synthesis gas with carbon monoxide and hydrogen or which can be converted to hydrogen after extraction of the contained carbon dioxide. But these biomass conversion technologies that can use fixed beds or fluidized beds all have a common problem to solve which is that of the capture of alkaline and fatal tar present in the synthesis gas containing CO, CO ₂ , H ₂ , H ₂ O, CH ₄ , or even N ₂ if gasification in air, and incompatible with many uses following corrosions and fouling provoked.

It is known that the vaporization of the alkalines of the Na ₂ O and K ₂ O type contained in the fuel and in particular its ashes is carried out between 780 and 115O ⁰ C. Moreover, it is known that the condensation of the alkalis is carried out below 600 ⁰ C gas temperature, while the condensation of tars is carried out below 400 ⁰ C.

US Patent 3,804,606 discloses a system for producing a low sulfur gas fuel for the purpose of supplying a gas and steam turbine plant.

This system comprises a coal drying reactor and two gasification stages by means of two gas gasification reactors in series with respect to the gas and interconnected with respect to the coal, a first gasification reactor operating at a temperature of order 1040 to 126O ⁰ C and a second gasification reactor operating at a temperature of the order of 93O ⁰ C. The resulting gas is treated with two treatment reactors, the first operating at a temperature of the order of 82 to 315 ⁰ C and the second at a temperature of the order of 760 to 1090 ⁰ C, also in series with respect to the gas and interconnected with respect to solids, the resulting gas being introduced into a cyclone separator, where the solids are reintroduced into the first gasification reactor and the purified synthesis gas is passed to a turbine plant. Lime and calcium sulphide is introduced downstream of these two treatment reactors and the calcium sulphide is extracted by gravity upstream of these two treatment reactors.

These reactors are fixed-rate, low-velocity, dense-type fluidized beds, which, due to turbulence, high-intensity gas / solid cross-over mixing and long residence time, require a cascade of fluidized beds with multiple interconnections. transfer of gases and solids, which are complex to build and operate industrially, because they are subject to clogging. In addition, the use of calcium sulphide is extremely problematic from the environmental and health standpoints, knowing that it is a classified waste hazardous waste whose disposal economically affects this process in a negative way.

The object of the invention is to produce a synthesis gas and to be able to remove at minimum cost the content of alkalis and tars in this synthesis gas, so as not to exceed a content of 5 ppm, which amounts to achieving a reduction of of these compounds greater than 95 to 99% knowing that this removal must be carried out on high temperature gases between 780 and 1150 ^° C. To do this, the invention proposes a process for producing and purifying a gas of synthesis using a carbonaceous fuel, consisting of gasification in a first reactor at a temperature between 780 and 115O ⁰ C and purification of the gas obtained in a second reactor, characterized in that said gasification is carried out at means of a first fast fluidized bed reactor loop having said first oxidant fed reactor, a first associated cyclone separator and a first returning solids to said first reactor, said purification is effected by means of a single second fast fluidized bed reactor loop comprising said second fluidized reactor by the gas obtained at the gas outlet of said first cyclone separator, a second cyclone separator associated and a second return line of the solids to said second reactor, said second reactor operating at a temperature of about 600 ^° C. at the bottom and at a temperature of about 400 ^° C. at the top.

According to one embodiment, said oxidant consists of solid particles carrying oxygen and in that said first reactor is fluidized with a mixture of carbon dioxide and water vapor.

Preferably, said solid particles carrying oxygen consist of a metal oxide based on pure or mixed oxides of iron, nickel, manganese and / or titanium.

Advantageously, said solid particles carrying oxygen circulate between said first fast fluidized bed loop and a third fast fluidized bed oxidation loop comprising a third reactor, a third associated cyclone separator and a third return line of solids towards said third reactor and interconnected to said first fast fluidized bed loop to form a thermochemical cycle.

The invention also relates to an installation for the production and purification of a synthesis gas, for the implementation of such a method, characterized in that said second reactor is disposed above said first cyclone separator, the outlet of gas of said first cyclone separator constituting the bottom of said second reactor.

It is thus achieved a compact stack of the two reactors which minimizes the gas connecting sheaths between reactors. The invention also relates to an installation for the production and purification of a synthesis gas, for the implementation of such a method characterized in that said second reactor comprises at least one exchanger for cooling its temperature at the top.

The invention also relates to an installation for the production and purification of a synthesis gas, for the implementation of such a method, characterized in that interconnection pipes are arranged between the outlet of a first siphon arranged on the first return line and said third reactor and between the outlet of a third siphon arranged on the third return line and said third reactor.

The invention is hereinafter described in more detail by means of a figure showing only preferred embodiments of the invention. Figure 1 is a schematic sectional vertical sectional view of an installation for the implementation of a first embodiment according to the invention.

Figure 2 is a schematic sectional vertical sectional view of an installation for implementing a second embodiment according to the invention.

Figures 3 and 4 are vertical sectional views of detail.

As illustrated in FIGS. 1 and 2, the invention proposes a process for producing and purifying a synthesis gas by means of a carbonaceous fuel, comprising performing a gasification in a first fast fluidized bed IA reactor in which circulates solid particles with a median diameter of about 120 microns at a temperature of between 780 and 115O ⁰ C, into which the solid or liquid or gaseous fuel is injected to be converted and to carry out a purification of the gas obtained in a second reactor 2A fed solid particles with a median diameter of about 10 to 40 microns. This gasification is carried out by means of a first fast fluidized bed reactor loop 1 comprising this first reactor IA of auto-thermal conversion, that is to say not requiring external heat input to perform the reactions of thermochemical conversion of endothermic nature, fed with oxidant, a first cyclone separator IB associated and a first return line IC solids to the first reactor IA.

The gasification of carbonaceous fuels, fossil or non-fossil biomass type, in solid, liquid, pasty or gaseous form can be carried out at atmospheric pressure or under pressure, if necessary, to feed a gas turbine or a chemical synthesis.

In the example shown where the first reactor IA filled with insulating refractory is at atmospheric pressure, the solid fuel is introduced by a gravity well 6 at the outlet of a side siphon solids ID equipping the first return line IC, downwards. of the first reactor IA. The ash of the fuel introduced and the used bed are partially extracted by the IF pipe.

The synthesis crude gas produced at a temperature of 780 to 115O ⁰ C by auto-thermal conversion of the fuel with the oxidant in the first reactor IA exits through the skirt of the first cyclone separator IB.

To reduce the tar contents, pretreatment of the synthesis crude gas can be carried out by an injection of oxidant into the upper part of the connecting sheath between the first reactor IA and the first cyclone separator IB, in the immediate vicinity of the reactor. cyclone separator inlet, to increase the temperature of the gas, before turbulence and residence in the first cyclone separator IB.

The purification is carried out by means of a single second fast fluidized bed reactor loop 2 comprising this second 2A reactor fluidized by the gas obtained at the gas outlet of the first cyclone separator IB, a second associated cyclone separator 2B and a second return line 2C solids to the second reactor 2A equipped with a 2D side siphon. The second reactor 2A operates at a temperature of about 600 ^° C. in the lower part and at a temperature of about 400 ^° C. in the upper part by the use of exchangers in this second reactor, making it possible to cool with cold solids the gas to be purified to cause condensation of alkalis and tars. A supply of solid particles 10 is made at the outlet of this second 2D siphon and a permanent extraction of these recycled particles 11 to the first reactor IA is carried out at the bottom of this siphon. The particles of the second reactor 2A can therefore be a combination of particles introduced externally and particles from the leak of the second cyclone separator 2B of higher yield than the first cyclone IB, in order to recirculate to the reactor 2A these fines lost by the first cyclone IB.

The solids at the outlet of the second cyclone 2B are at a temperature well below the temperature of the crude synthesis gas fluidizing the second reactor 2A, which makes it possible to reach the temperature of 600 ^° C. in the lower part provided with refractory material of the second reactor 2A, for condensing the alkali on the bed support of circulating fine particles. The cooled synthesis gas is transported vertically upwardly through at least one immersed exchanger 4 for cooling arranged in the second reactor 2A, so as to cool the synthesis gas again to a temperature of 400 ^° C. Such axial cooling two-stage flow also results from the recirculated cold solids, the flow rate of which depends on the solids inventory in said second reactor adjusted by the addition and extraction of solid particles. This part upper of the second reactor 2A is not lined with insulating refractory, which contributes to the cooling of the gas by its cooled walls consisting of cooling tubes joined by welded fins. The exchanger 4 may consist of panels of contiguous tubes arranged transversely in the second reactor 2A to the flow loaded with synthesis gas, knowing that the great fineness of the particles in circulation will not cause erosion of the metal parts. These exchanger panels 4 may consist of several panels on the height of the second reactor 2A with solid returns of the second siphon 2D between these panels at intermediate heights of the second reactor 2A.

At the outlet of the gases of the second cyclone separator 2B, the purified and cooled synthesis gas at 400 ^° C. is transferred via a pipe or sheath 7 towards its use, which may be of a thermal nature (combustion in a motor or turbine), or nature process to perform liquid fuel type syntheses including biofuels.

The second reactor 2A is disposed above the first cyclone separator IB, the gas outlet of this first cyclone separator IB constituting the bottom of the second reactor 2A.

According to the first embodiment illustrated in FIG. 1, the oxidant is air possibly enriched with oxygen or a mixture of oxygen and water vapor, fluidizing the first reactor IA. The solid particles circulating in the first reactor (IA) consist of ashes and inerts of the introduced fuel whose particle size has been prepared appropriately to make it possible to fluidize it, in the case of a solid fuel, and by a material of supplement of this bed with a median diameter of about 120 microns. This make-up material is preferably either sand, limestone, dolomite, or aluminous clay.

According to the second embodiment illustrated in FIG. 2, the oxidant consists of solid particles carrying oxygen constituted by a metal oxide based on pure or mixed oxides of iron, nickel, manganese and / or titanium and the first reactor IA is fluidized with a mixture of carbon dioxide and water vapor.

These solid particles carrying oxygen flow between the first fast fluidized bed loop 1 and a third fast fluidized oxidation bed loop 3 comprising a third air-fluidized reactor 3A, a third associated cyclone separator 3B and a third conduit returning solids 3C with a 3D solid side siphon to the third reactor 3A and interconnected to the first fast fluidized bed loop 1 to form a thermochemical cycle. The third oxidation reactor 3A is associated with exchangers 8 to absorb the possible exo-thermicity of the oxidation.

Oxygen-depleted air 9 leaves the skirt of the third cyclone separator 3C, for cooling by energy recovery, filtration and discharge to the atmosphere. The interconnection pipes 5A, 5B are arranged between the outlet of a first siphon 5C arranged on the first return line IC and the third reactor 3A and between the outlet of a third siphon 5D arranged on the third return line 3C and the first IA reactor. Alternatively, the third reactor 3A may be a dense bed or a moving bed.

FIG. 3 shows in detail a lateral siphon such as the 2D siphon equipping the second fast fluidized bed loop 2 or the siphon ID equipping the first fast fluidized bed loop 1 according to the first embodiment (FIG. 1). Such a lateral siphon of solids 20 consists of a vertical section of sheath or pipe followed by a bend 23 inclined between 45 ° and 67.5 °, and preferably 45 °, then a side tee 21 having a vertical stroke which is followed by a change of direction from 292.5 to 315 ° by a second lateral tee 22 and a bend 24 having a vertical outlet 26, and preferably 315 °, with an inlet of the ES solids. and an output of SS solids. As a result, the amount of GF fluidizing gas of such a siphon is minimized and the pressurized construction of such a siphon is simplified by the use of standard elements of two-side type pipe 21, 22 between 45 and 67.5 °, and preferably at 45 °, and two elbows 23, 24 between 45 and 67.5 °, and preferably at 45 °, with a straight section 25, 26. The lateral siphon solids is provided with a single fluidization system GF, at the base of the tee 21. Figure 4 shows in detail a double side siphon such as 3D siphons, 5D equipping the third loop fast fluidized bed 3 or siphons ID, 5C equipping the first fast fluidized bed loop 1 according to the second embodiment (Figure 2).

Such a double side siphon 30 equipping said first and third siphons 5C, 5D is constituted by a vertical section of sheath or pipe followed by a Y 31 inclined between 45 ° and 67.5 °, and preferably at 45 °, then a lateral tee 32, 33 having a vertical stroke followed by a change of direction from 292.5 to 315 ° by a second lateral tee 34, 35 and a bend 36, 37 having a vertical outlet 37, 38, and preferably at 315 °. The double siphon has an inlet of the solids ES and a double outlet of the solids SS and a system of fluidization GF at the base of the components 31, 32, 33. As a result, the amount of fluidizing gas GF of such a siphon is minimized and the pressurized construction of such a siphon is simplified by the use of standard elements of type Y 31 and two tee 32, 33 45 degrees laterally followed by two lateral tees at 45 ° 34, 35 and two elbows 36, 37 between 45 and 67.5 °, and preferably at 45 °, with a straight section 37, 38. The side siphon solids is provided with three fluidization systems 40, 41, 42, the central 42 is compartmentalized by an inner wall.

Claims

REVEN DICATIONS

1. A method for producing and purifying a synthesis gas using a carbonaceous fuel, comprising gasifying in a first reactor (IA) at a temperature of between 780 and 115O ⁰ C and performing a purification of gas obtained in a second reactor (2A), characterized in that said gasification is carried out by means of a first fast fluidized bed reactor loop (1) comprising said first reactor (IA) supplied with oxidant, a first associated cyclone separator (IB) and a first solid return line (IC) to said first reactor (IA), said purification is effected by means of a single second fast fluidized bed reactor loop (2) having said second reactor (2A) fluidized by the gas obtained at the gas outlet of said first cyclone separator (IB), a second associated cyclone separator (2B) and a second solids return pipe (2C) towards said second e reactor (2A), said second reactor (2A) operating at a temperature of about 600 ⁰ C in the lower part and at a temperature of about 400 ⁰ C in the upper part.

2. Method according to claim 1, characterized in that an auto-thermal conversion is performed in said first reactor (IA).

3. Method according to one of the preceding claims, characterized in that solid particles with a median diameter of about 120 microns circulate in said first reactor (IA).

4. Method according to one of the preceding claims, characterized in that said second reactor (2A) is fed solid particles with a median diameter of about 10 to 40 microns.

5. Method according to one of the preceding claims, characterized in that said oxidant is air optionally enriched with oxygen or a mixture of oxygen and water vapor, fluidizing said first reactor.

6. Method according to the preceding claim, characterized in that solid particles of a makeup material circulate in said first reactor.

7. Method according to one of claims 1 to 4, characterized in that said oxidant is composed of solid particles carrying oxygen and in that said first reactor (IA) is fluidized with a mixture of carbon dioxide and steam of water.

8. Process according to the preceding claim, characterized in that said solid particles carrying oxygen consist of a metal oxide based on pure or mixed oxides of iron, nickel, manganese and / or titanium.

9. The method of claim 7 or 8, characterized in that said solid particles carrying oxygen flow between said first fast fluidized bed loop (1) and a third fast fluidized bed oxidation loop (3) having a third reactor (3A), a third associated cyclone separator (3B) and a third solid return line (3C) to said third reactor (3A) and interconnected to said first fast fluidized bed loop (1), to form a thermochemical cycle .

10. Installation for the production and purification of a synthesis gas, for the implementation of a method according to one of the preceding claims, characterized in that said second reactor (2A) is disposed above said first cyclone separator (IB), the gas outlet of said first cyclone separator (IB) constituting the bottom of said second reactor (2A).

11. Installation for the production and purification of a synthesis gas, for the implementation of a process according to one of claims 1 to 9 or according to claim 10, characterized in that said second reactor (2A) comprises at least one exchanger (4) for cooling its temperature at the top.

12. Installation according to the preceding claim, characterized in that said second reactor (2A) comprises a lower portion provided with refractory material and an upper portion provided with cooling tubes.

13. Installation for the production and purification of a synthesis gas, for the implementation of a method according to claim 9, characterized in that interconnection pipes (5A, 5B) are arranged between the outlet of a first siphon (5C) arranged on the first return line (IC) and said third reactor (3A) and between the outlet of a third siphon (5D) arranged on the third return line

(3C) and said first reactor (IA).

14. Installation according to the preceding claim, characterized in that said first and third siphons (5C, 5D) are constituted by a vertical section (25) of piping followed by a bend (23) inclined between 45 ° and 67.5 ° , then a side tee (21) having a vertical stroke which is followed by a change of direction from 292.5 to 315 ° by a second lateral tee (22) and a bend (24) having a vertical exit (26). ), and in that said siphons have a solid inlet (ES), a solids output (SS) and a single fluidization system (GF).

15. Installation according to claim 13 or 14, characterized in that said first return line (IC) and said third return line (3C) are equipped with a double side siphon (30).

16. Installation according to the preceding claim, characterized in that said double side siphon (30) is constituted by a vertical pipe section followed by a Y (31) inclined between 45 ° and 67.5 °, then a side tee (32, 33) having a vertical stroke which is followed by a change of direction from 292.5 to 315 ° by a second lateral tee (34, 35) and a bend (36, 37) having a vertical exit (37, 38), and in that said double siphon has a solids inlet (ES), a double solids outlet (SS) and a fluidization system (GF).