CA2747357A1 - Method and device for producing and purifying a synthesis gas - Google Patents

Abstract

The invention relates to a process for producing and purifying a synthesis gas by means of a carbonaceous fuel, comprising gasifying a first reactor (1A) at a temperature of between 780 and 1150 ° C and purification of the gas obtained in a second reactor (2A). According to the invention, said gasification is effected by means of a first fast fluidized bed reactor loop (1) comprising said first reactor (1A) supplied with oxidant, a first associated cyclone separator (1B) and a first returning solids (1C) to said first reactor (1A), said purification is effected by means of a single second fast fluidized bed reactor loop (2) comprising said second reactor (2A) fluidized by the gas obtained at the outlet of said first cyclone separator (1B), a second cyclone separator (2B) and a second solids return pipe (2C) to said second reactor (2A), said second reactor (2A) operating at a temperature of about 600 ° C in the lower part and at a temperature of about 400 ° C in the upper part.

Description

PROCESS AND DEVICE FOR PRODUCTION AND PURIFICATION
OF SYNTHESIS GAS

The invention relates to a method and a device for producing and of synthesis gas purification.
Gasification technology for carbonaceous fuels of fossil and non-fossil origin is an essential step in the progressive replacement of current hydrocarbons of the oil or natural gas for energy production, fuel production synthetics and finally the production of chemical intermediates of synthesis. In particular, the gasification of biomass has become strategic as it offers a valuable alternative to long-term, after depleting fossil fuel resources, while controlling the release of carbon dioxide into the atmosphere, who are deemed responsible for future climate change.
To achieve this gasification, various ways are possible in depending on the final quality sought for the gas: either a gasification with air, the gas produced has a low calorific value (PCI) resulting from the presence of nitrogen from the air and which is not used only for thermal applications, ie gasification at oxygen and with water vapor, the oxygen coming from a unit of separation of air from which the product gas, which has a medium average used, after extraction of the contained carbon dioxide, as the carbon monoxide and hydrogen synthesis or converted into hydrogen in the end.
Finally, it is possible to perform a gasification cycle thermochemical, without the need for an oxygen production unit, the The product gas has a mean ICP, which can be used as carbon monoxide and hydrogen synthesis or that can be converted to hydrogen after extraction of the contained carbon dioxide.

2 But these biomass conversion technologies that can use fixed beds or fluidized beds all have a problem common to solve which is that of the capture of alkaline and fatal tar present in the synthesis gas containing CO, CO2, H2, H2O, CH4, or even N2 If gasification in air, and incompatible with many uses due to corrosions and fouling provoked.
It is known that the vaporization of alkalines of Na20 and K20 type contained in the fuel and in particular its ashes are between 780 and 1150 C. Moreover, it is known that the condensation of alkali is carried out below 600 C gas temperature, while the condensation of tars is carried out below 400 C.
US Patent 3,804,606 discloses a system of production of gaseous fuel with low sulfur content in the purpose of powering a gas and steam turbine power plant.
This system includes a coal drying reactor and two stages of gasification by means of two reactors of gasification in series with respect to gas and interconnected in that coal, a first gasification reactor operating at a temperature of the order of 1040 to 1260 C and a second gasification reactor operating at a temperature of 930 C. The resulting gas is treated by two reactors of treatment whose first operates at a temperature of the order of 82 at 315 C and the second at a temperature of about 760 to 1090 C, also in series with regard to gas and interconnected solids, the resulting gas being introduced into a cyclone separator, where solids are reintroduced into the first gasification reactor and the purified synthesis gas is transmitted to a turbine power plant. Lime and calcium sulphide is

3 downstream of these two process reactors and the sulphide of calcium is extracted by gravity upstream from these two reactors of treatment.
These reactors are fluidized beds of dense type at low speed and fixed height, which, due to turbulence, cross-mixing gas / solids of high intensity and long residence time, require a cascade of fluidized beds with multiple interconnections of transfer of gases and solids, which are complex to build and to exploit industrially, because subject to obstructions.
In addition, the use of calcium sulphide is extremely environmental and health problems, knowing that is a classified waste hazardous waste whose disposal affects economically this process in a negative way.
The object of the invention is to produce a synthesis gas and ability 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 these compounds greater than 95 to 99% knowing that this deletion must be carried out on high temperature gas between 780 to 1150 C.
For this purpose, the invention proposes a method of producing and purification of a synthesis gas by means of a carbonaceous fuel, of gasifying in a first reactor at a temperature of temperature between 780 and 1150 C and to carry out a purification of the gas obtained in a second reactor, characterized in that than said gasification is effected by means of a first fast fluidized bed reactor loop including said first reactor oxidant, a first associated cyclone separator and a first return line of the solids to said first reactor,

4 said purification is carried out by means of a single second fast fluidized bed reactor loop having said second fluidized reactor by the gas obtained at the gas outlet of said first cyclone separator, a second associated cyclone separator and a second conduit for returning solids to said second reactor, said second reactor operating at a temperature about 600 C in the lower part and at a temperature of about 400 C
in the upper part.
According to one embodiment, said oxidant consists of solid particles carrying oxygen and in that said first reactor is fluidized by a mixture of carbon dioxide and water vapour.
Preferably, said solid particles carrying oxygen consist of a metal oxide based on pure oxides or mixed with iron, nickel, manganese and / or titanium.
Advantageously, said solid carrier particles of oxygen flow between said first fast fluidized bed loop and a third fast fluidized bed oxidation loop with a third reactor, a third associated cyclone separator and a third return line of the solids to said third reactor and interconnected with said first fast fluidized bed loop, to form a thermochemical cycle.
The invention also relates to a production facility and of purification of a synthesis gas, for the implementation of such a characterized in that said second reactor is disposed above said first cyclone separator, the gas outlet of said first cyclone separator constituting the bottom of said second reactor.
It is thus realized a compact stack of the two reactors which minimizes the gas connection sheaths between reactors.

The invention also relates to a production facility and of purification of a synthesis gas, for the implementation of such a characterized in that said second reactor comprises at least minus a heat exchanger of its temperature in part

5 high.
The invention also relates to a production facility and of purification of a synthesis gas, for the implementation of such a characterized in that interconnecting lines are disposed between the outlet of a first siphon arranged on the first return pipe 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 described below in more detail using FIG.
representing only preferred embodiments of the invention.
Figure 1 is a schematic sectional vertical sectional view of an installation for the implementation of a first mode of embodiment according to the invention.
FIG. 2 is a schematic sectional view in vertical section of an installation for the implementation of a second mode of 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 of carbonaceous fuel, consisting in gasification in a first fast fluidized bed reactor 1A in which circulate solid particles with a median diameter of about 120 microns at a temperature between 780 and 1150 C, in which is injected the solid or liquid or gaseous fuel to be converted and purification of the gas obtained in a second reactor 2A supplied with solid particles with a median diameter of about 10 to 40 microns.

6 This gasification is carried out by means of a first loop of a fast fluidized bed reactor 1 comprising this first reactor 1A of auto-thermal conversion, that is to say not requiring input external heat to perform the conversion reactions thermochemical endothermic nature, fed with oxidant, a first cyclone separator 1B associated and a first conduct of 1C return of the solids to the first reactor 1A.
Gasification of carbon fuels, fossil or non-fossil Biomass type fossils, in solid, liquid, pasty or gaseous can be carried out at atmospheric pressure or under pressure, if necessary, to power a gas turbine or a synthesis chemical.
In the example shown where the first reactor 1A furnished with insulating refractory is at atmospheric pressure, the solid fuel is introduced by a gravity well 6 at the outlet of a lateral siphon of 1D solids equipping the first return line 1C, down the first reactor 1A. Ashes of the fuel introduced and the used bed are partially extracted by the 1F pipe.
Synthetic raw gas produced at a temperature of 780 to 1150 C by auto-thermal conversion of fuel with oxidant in the first reactor 1A comes out through the skirt of the first separator cyclone 1B.
To reduce the tar contents, a pretreatment of the gas synthetic crude can be made by an oxidant injection into the upper part of the connecting sheath between the first reactor 1A and the first cyclone separator 1B, in the immediate vicinity of the entrance to the cyclone separator, to increase the temperature of the gas, before setting in turbulence and residence in the first cyclone separator 1B.
The purification is carried out by means of a single second fast fluidized bed reactor loop 2 having this second

7 reactor 2A fluidized by the gas obtained at the gas outlet of the first cyclone separator 1B, a second associated cyclone separator 2B and a second return pipe 2C solids to the second 2A reactor 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 exchangers in this second reactor, allowing cooling by cold solids the gas to be purified in order to cause the condensation of alkalis and tars.
A contribution of solid particles 10 is made at the outlet of this second 2D siphon and permanent extraction of these particles 11 recycled to the first reactor 1A is performed at the bottom of this siphon.
The particles of the second reactor 2A can therefore be a combination of externally introduced particles and particles from the leakage of the second efficiency cyclone separator 2B
higher than the first cyclone 1B, to recirculate to the reactor 2A these fines lost by the first cyclone 1B.
The solids at the outlet of the second cyclone 2B are at a temperature well below the temperature of the raw gas of fluidizing the second reactor 2A, which makes it possible to reach the temperature of 600 C in the lower part provided with material refractory of the second reactor 2A, to condense the alkalis on the bed support of fine particles in circulation. Synthesis gas cooled is transported vertically upward through to minus a submerged heat exchanger 4 arranged in the second reactor 2A, so as to cool again the synthesis gas to the temperature of 400 C. Such axial cooling of the flow in two stages also results from recirculated cold solids whose flow depends on the inventory in solids in the said second reactor adjusted by the intake and extraction of solid particles. This part

8 upper of the second reactor 2A is not lined with refractory insulation, 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 charged 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 2D siphon between these panels at intermediate heights of the second reactor 2A.
At the outlet of the gases of the second cyclone separator 2B, the gas of synthesis purified and cooled to 400 C is transferred by piping or a sheath 7 towards its use which can be of a thermal nature (combustion engine or turbine), either of a process nature for carry out liquid fuel type syntheses whose biofuels.
The second reactor 2A is disposed above the first cyclone separator 1B, the gas outlet of this first separator cyclone 1B constituting the bottom of the second reactor 2A.
According to the first embodiment illustrated in FIG.
the oxidant is air possibly enriched with oxygen or a mixture of oxygen and water vapor, fluidizing the first reactor 1A. The solid particles circulating in the first reactor (1A) are consisting of ash and inert fuel introduced granulometry has been prepared appropriately to make it possible its fluidization, in the case of a solid fuel, and by a material of this bed with a median diameter of about 120 microns. This WO 2010/07649

9 PCT / FR2009 / 052563 make-up material is preferably either sand or limestone or a dolomite, an aluminous clay.
According to the second embodiment illustrated in FIG.
the oxidant consists of solid particles carrying oxygen consisting of a metal oxide based on pure or mixed oxides of iron, nickel, manganese and / or titanium and the first reactor 1A is fluidized by a mixture of carbon dioxide and water vapor.
These solid particles carrying oxygen circulate between the first fast fluidized bed loop 1 and a third bed loop rapid fluidization of oxidation 3 comprising a third reactor 3A
fluidized with air, a third associated cyclone separator 3B and a third return line of 3C solids with a lateral siphon of solid 3D 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.
Air depleted in oxygen 9 comes out of the skirt of the third cyclone separator 3C, for cooling by energy recovery, filtration and discharge to the atmosphere.
Interconnection lines 5A, 5B are arranged between the exit of a first siphon 5C arranged on the first return pipe 1C and the third reactor 3A and between the exit of a third siphon 5D arranged on the third return line 3C and the first reactor 1A.
Alternatively, the third reactor 3A may be a dense bed or a moving bed.
FIG. 3 represents in detail a lateral siphon such as the 2D siphon equipping the second fast fluidized bed loop 2 or the 1D siphon equipping the first fast fluidized bed loop 1 according to the first embodiment (Figure 1).

Such a lateral siphon of solids 20 consists of a section 25 vertical sheath or pipe followed by a bend 23 inclined between 45 and 67.5, and preferably 45, then a lateral tee 21, having a vertical stroke which is followed by a change of direction of 5 292.5 to 315 by a second lateral tee 22 and a bend 24 having a vertical outlet 26, and preferably at 315, with a solids inlet ES and SS solid output. As a result, the amount of gas GF fluidization of such a siphon is minimized and the construction under pressure of such a siphon is simplified by the use of standard elements

10 piping type two tees 21, 22 lateral 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 side siphon of solids is equipped with a single fluidizing system GF, at the base from tee 21.
FIG. 4 shows in detail a double side siphon such as 3D siphons, 5D equipping the third fast fluidized bed loop 3 or the siphons 1D, 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 piping followed by a Y 31 inclined between 45 and 67.5, and preferably 45, then a lateral tee 32, 33 presenting a race which is followed by a change in direction from 292.5 to 315 by a second lateral tee 34, 35 and a bend 36, 37 having an exit vertical 37, 38, and preferably 315. The double siphon has a solid ES input and a double SS solid output and a system of fluidization GF at the base of the components 31, 32, 33.
fact, the amount of GF fluidization gas of such a siphon is minimized and the construction under pressure of such a siphon is simplified by the use of standard elements of piping type Y 31 and two tees 32, 33

11 lateral 45 degrees followed again by two lateral tees at 45 34, 35 and two elbows 36, 37 between 45 and 67.5, and preferably 45, with a straight section 37, 38. The lateral siphon of solids is provided with three fluidization systems 40, 41, 42 whose central 42 is compartmentalized by an inner wall.

Claims (16)

1. Process for producing and purifying a gas synthesis using a carbon fuel, consisting of gasification in a first reactor (1A) to a temperature between 780 and 1150 ° C and to carry out a purification of the gas obtained in a second reactor (2A), characterized in that said gasification is effected by means of a first loop fast fluidized bed reactor (1) comprising said first reactor (1A) fed with oxidant, a first cyclone separator associated (1B) and a first solid return line (1C) to said first reactor (1A), said purification is carried out 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 said first cyclone separator (1B), a second separator associated cyclone (2B) and a second return solids (2C) to said second reactor (2A), said second reactor (2A) operating at a temperature about 600 ° C in the lower part and at a temperature of about 400 ° C in the upper part. 2. Method according to claim 1, characterized in that that an auto-thermal conversion is carried out in said first reactor (1A). 3. Method according to one of the preceding claims, characterized in that solid particles of a median diameter about 120 microns circulate in said first reactor (1A). 4. Method according to one of the preceding claims, characterized in that said second reactor (2A) is powered 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 possibly air 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 auxiliary material circulate in said first reactor. 7. Method according to one of claims 1 to 4, characterized in that said oxidant consists of solid particles oxygen carriers and in that said first reactor (1A) is fluidized by a mixture of carbon dioxide and steam of water. 8. Method according to the preceding claim, characterized in that said solid particles carrying oxygen are consisting of a metal oxide based on pure oxides or mixed with iron, nickel, manganese and / or titanium. 9. Process according to claim 7 or 8, characterized in that that said solid particles carrying oxygen circulate between said first fast fluidized bed loop (1) and a third rapid fluidized bed oxidation loop (3) having a third reactor (3A), a third associated cyclone separator (3B) and a third return line of solids (3C) to said third reactor (3A) and interconnected with said first fast fluidized bed loop (1) to form a cycle thermochemical. 10. Installation for the production and purification of a gas synthesis, 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 separator cyclone (1B), the gas outlet of said first cyclone separator (1B) constituting the bottom of said second reactor (2A). 11. Installation for the production and purification of a gas synthesis, for the implementation of a method according to one of the 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 in part high. 12. Installation according to the preceding claim, characterized in that said second reactor (2A) comprises a lower part provided with refractory material and an upper part provided with cooling tubes. 13. Installation for the production and purification of a gas synthesis, for the implementation of a method according to claim 9, characterized in that interconnection (5A, 5B) are arranged between the output of a first siphon (5C) arranged on the first return pipe (1C) and said third reactor (3A) and between the output of a third siphon (5D) arranged on the third return pipe (3C) and said first reactor (1A). 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 an elbow (23) inclined between 45 ° and 67.5 °, then a tee side (21) having a vertical stroke which is followed by a change of direction from 292.5 to 315 ° by a second tee side (22) and an elbow (24) having a vertical outlet (26), and what said siphons have an input of solids (ES), a 15 solids output (SS) and a single fluidization system (GF).

15. Installation according to claim 13 or 14, characterized in that said first return line (1C) and said third return line (3C) are equipped with a double lateral siphon (30). 16. Installation according to the preceding claim, characterized in that said double side siphon (30) is consisting of a vertical pipe section followed by a Y (31) inclined between 45 ° and 67,5 °, then with a lateral tee (32,33) with a vertical stroke that is followed by a change of direction from 292.5 to 315 ° by a second lateral tee (34, 35) and an elbow (36, 37) having a vertical output (37, 38), and that said double siphon has a solids inlet (ES), a double solids outlet (SS) and a fluidizing system (GF).