ITMO20150098A1 - REACTOR FOR GASIFICATION PLANTS - Google Patents

Description

Description of Patent for Industrial Invention entitled:

? REACTOR FOR GASIFICATION PLANTS ?.

DESCRIPTION

The present invention refers to a reactor for gasification plants.

As you know, gasification? a set of thermochemical processes suitable for transforming biomass, of various kinds and origins, into a combustible gas, commonly called? syngas ?, and usable for various purposes, for example as a fuel in internal combustion engines.

The whole of the thermochemical processes takes place in special gasification reactors.

In the fixed bed, co-current and counter-current reactors, used for small and medium-sized plants (up to about 1MW), the set of thermochemical processes can? generally be divided into four main phases: drying, pyrolysis, oxidation and reduction.

The biomass usually used for this type of process? consisting of wood chips or other organic matter, for example deriving from waste treatment.

The thermochemical processes take place at high temperatures (higher than 700? -800?) And in the presence of a gasifying agent, usually air, in an understoichiometric percentage.

In particular, in the oxidation phase it is possible to reach temperatures of about 1100 ° C or higher.

The biomass, in these conditions,? subjected to a thermal degradation for which the long-chain chemical bonds are split into molecules pi? simple and the biomass itself is transformed into resulting products of various types, gaseous, liquid and solid.

The gaseous products obtainable depend on the type of gasifying agent and constitute the combustible gaseous mixture called syngas.

In the case of air there is carbon dioxide, methane, carbon monoxide, nitrogen, hydrogen and other gaseous molecules.

Solid products, commonly called? Char ?, are material that has not reacted during the thermochemical processes and is found at the end of the processes in the form of ash and other solid particles.

The ash and solid particles having dimensions greater than about 10 pm precipitate and are easily removable, while the particles with smaller dimensions, commonly called? Dust? or? dust ?, are carried away by the syngas and find themselves in it.

The above thermochemical processes are normally carried out in a special reactor, that is? in a container suitable to be filled at least partially with the biomass to be transformed into syngas.

By providing a sufficient quantity? of heat, a temperature gradient is established inside the reactor which allows the development of the thermochemical reactions necessary for the chemical degradation of the biomass and therefore the favorable conditions are created for the various phases of the gasification process.

The temperature gradient is self-sustaining over time and the reactions continue as long as biomass and oxidizer are supplied.

The biomass present in the reactor progressively undergoes thermochemical degradation as, due to the loading and unloading operations, it passes from the upper portion of the reactor to the lower one.

Ideally, the four stages in which it can? be divided the gasification process can be identified in four different areas all? inside the reactor.

The drying phase takes place in the upper portion of the reactor, at temperatures up to about 250 ° C.

The pyrolysis phase takes place in the portion immediately below with temperatures reaching an interval of approximately 250 ° C and 600 ° C.

The oxidation phase takes place in the underlying portion, where the reactor usually shrinks forming a bottleneck, with temperatures reaching even over 1100 ° C.

The last phase of reduction, on the other hand, takes place in the larger portion? below, it begins at temperatures in the range of about 800 ° C to 1100 ° C and, being endothermic, reaches temperatures of about 600 ° C or lower.

In known reactors, for example of the? Co-current? Type, in the portion where the oxidation step takes place there are nozzles for the discharge of the gasifying agent (air).

Furthermore, the co-current reactors are open at the bottom, so as to allow the passage of the syngas from the portion where the reduction takes place.

Other known types of reactors, such as the? Countercurrent? Type reactors, are completely similar to the? biomass is fed into the reactor.

In counter-current reactors, in fact, the gas crosses the biomass bed in the opposite direction with respect to the direction of advance of the biomass itself in the reactor.

In any case, ? note the need to cope with the drawbacks linked to the high temperatures that are reached at the? inside the reactor, especially in the portion where oxidation takes place.

In particular, it is necessary to face the effect that the high temperatures have on the walls defining the reactor itself.

In fact, at such temperatures, the mechanical and oxidation resistance of some materials with which the reactors are made, such as commercial steels, is significantly reduced, making this type of material unusable for the construction of the casing.

As an alternative to commercial steels? it is known to use ceramic refractory materials, resistant to high temperatures.

Also in this case, however, there are some drawbacks linked both to the high costs of this type of materials, and to their poor resistance to temperature variations, with these making the material more effective. fragile. This last drawback? particularly evident when the reactor requires frequent on-off cycles of the reactor or simple maintenance operations.

The main task of the present invention? that of devising a reactor for gasification plants that allows the temperature of the reactor walls to be lowered.

A purpose of the present invention? that of devising a reactor for gasification plants which, at par? of thermal insulation, allows to reduce the thermal dispersion towards the outside.

A further purpose of the present invention? that of devising a reactor for gasification plants that allows to increase the thermal efficiency.

Another purpose of the present invention? that of devising a gasification plant which allows to overcome the aforementioned drawbacks of the prior art within the ambit of a simple, rational, easy and effective use and low cost solution.

The above objects are achieved by the present gasification plant having the characteristics of claim 1.

Other characteristics and advantages of the present invention will become more evident from the description of a preferred, but not exclusive, embodiment of a gasification plant, illustrated by way of indication, but not of limitation, in the accompanying drawings in which: Figure 1? an axonometric view of the reactor according to the invention;

figure 2? a partially exploded view of the reactor according to the invention;

figure 3? a sectional view of the reactor according to the invention.

With particular reference to these figures, yes? 1 generally indicates a reactor for gasification plants.

The reactor 1 comprises a first container body 2 able to be filled at least partially with biomass to be gasified to obtain synthesis gas (syngas).

The first container body 2? provided with an upper portion 3 suitable for receiving the incoming biomass.

In the present discussion, with the terms? Superior ?,? Inferior ?,? Superiorly ?,? Inferiorly? and the like, reference is made to the commonly adopted solution of positioning the reactor so that its main axis is in a vertical position.

The upper portion 3? the portion in which temperatures and conditions are reached such as to allow the development of the drying phase and part of the pyrolysis phase.

Helpfully, the upper portion 3? provided with an inlet 4 intended to be connected to transfer systems such as, for example, hoppers, augers, pistons, etc., suitable for inserting the biomass into the reactor itself.

In the present embodiment, the input 4? surrounded by attachment means 5 intended to make the connection between the reactor 1 and the transfer systems mentioned above.

The first container body 2 also comprises a central portion 6. The central portion 6? the portion of the first container body 2 suitable for hosting a biomass oxidation step.

In the central portion 6, in fact, conditions are created that allow the pyrolysis phase to continue, but, above all, such as to guarantee the development of the actual combustion of the biomass, with the achievement of average temperatures of about 800 ° C.

AND? in this portion that the gasifying agent 7 is introduced, usually air, but the use of other agents such as pure oxygen or steam is not excluded, in substoichiometric proportions to give rise to the oxidation phase which completes the transformation of biomass into gas summary 8.

For this purpose, holes 9 are made in correspondence with the central portion 6 for the introduction of the gasifying agent 7.

In the embodiment illustrated in the figures, the holes 9 are made at the same height and equidistant from each other to ensure an injection of gasifying agent 7 as much as possible. possible homogeneous.

In this way, all? inside of the central portion 6 zones with different temperature and oxygenation conditions such as to decrease the efficiency of the gasification process.

Advantageously, the central portion 6 comprises an upper portion 6a of substantially cylindrical conformation, having one end? upper portion connected to the upper portion 3, and a lower portion 6b substantially shaped like an inverted truncated cone and associated with the upper portion 6a.

In the present discussion, by truncated cone? Inverted? we mean the configuration in which the section of the truncated cone having larger dimensions? arranged above the section having smaller dimensions.

As illustrated in the figures, the outer surface of the central portion 6? smooth, but alternative solutions are not excluded in which, for example, exchange fins or other devices are made on this surface to increase the heat exchange surface of the central portion itself.

Finally, the first container body 2 comprises a lower portion 10 suitable for allowing the gasified biomass (ashes and other inert material) and the synthesis gas 8 to escape.

In particular, in correspondence with the lower portion 10 the main reduction reactions take place which contribute to the formation of the combustible part of the syngas (hydrogen, carbon monoxide, etc.). The lower portion 10? associated with the central portion 6 and, in the present embodiment, it also has a truncated conical shape, in this case not overturned, but having the section with larger dimensions arranged below the section with smaller dimensions.

In particular, the lower section 6b has an? Extremity? lower 11 connected to the lower portion 10.

In the present embodiment, therefore, the end? lower portion 11 coincides with the connecting section between the central portion 6 and the lower portion 10.

The first container body 2 illustrated in the figures, therefore, has a narrowing precisely in correspondence with the extremity. lower 11.

The end lower 11, due to its positioning,? subjected to very high temperatures and has less surface to use to dispose of excess heat.

For this reason it is the part of the first container body 2 which is most susceptible to wear and thermal stress.

The reactor 1, moreover, provides a second container body 12 entirely comprising the first container body 2.

In particular, the second container body 12? associated with the first container body 2 in correspondence with the upper portion 3 and? provided with at least one port 13 suitable for allowing the entry of the gasifying agent into the second container body itself.

In the present embodiment? a port 13 is present, but alternative solutions are not excluded in which the second container body 12 comprises a different number of ports 13.

Also, as illustrated in the figures,? there is also an auxiliary port 13a suitable for allowing the gasifying agent to enter the reactor 1 as well.

Are not different solutions excluded in which, for example, light 13? closed and the entry of the gasifying agent takes place only through the light 13a.

The second container body 12 has a substantially cylindrical shape and, at the upper base,? provided with a lid 12a shaped like a circular crown with an open center that can be superimposed on inlet 4.

In correspondence with the lower base, on the other hand, the second container body 12 has means 14 for hooking it to a support structure 15 capable of supporting the container body at a height.

Still in correspondence with the lower base, the second container body 12 comprises a discharge area 16.

The latter? arranged below the first container body 2 and? suitable to accumulate the gasified biomass, that is? ashes and other material deriving from the thermochemical processes of gasification, coming out of the first container body itself.

According to the invention, the reactor 1 comprises an auxiliary casing 17 which at least partially surrounds the central portion 6.

In particular, the auxiliary casing 17? fixed to the central portion above the holes 9 and? provided with an opening 18 obtained below the holes 9 so as to convey the gasifying agent 7 around the central portion 6.

In the present embodiment, the auxiliary casing 17 allows the gasifying agent 7 to pass from the second container body 12 to the holes 9 so that the central portion 6 can be lapped by the gasifying agent itself.

The auxiliary casing 17, in fact, defines a space between the central portion 6 and the casing itself, closed at the top by a substantially horizontal wall 17a and accessible through the opening 18.

The gasifying agent 7 can? then pass from the second container body 12 to the holes 9 through the opening 18 and skirting the central portion 6.

In the present embodiment, the auxiliary casing 17 entirely surrounds the central portion 6 so as to completely envelop it. In particular, the auxiliary casing 17 comprises an upper section 17a of substantially cylindrical shape which surrounds the upper section 6a.

The auxiliary casing 17 also comprises a lower section 17b substantially shaped like an inverted truncated cone that surrounds the lower portion 6b of the central portion 6.

The opening 18? defined at the base of the lower section 17b cos? to convey the passage of the gasifying agent 7 in the vicinity? of the extremity lower 1 1.

In this way, the gasifying agent 7 can? lick the entire central portion 6, effectively operating a heat exchange that allows the cooling of the central portion itself and above all of the extremity? lower 11 which, as mentioned,? the one most susceptible to wear and thermal stress.

In order to optimize the exchange d? heat between the gasifying agent 7 and the first container body 2, at least one of the ports 13? arranged at a higher level than opening 18.

In this way, the gasifying agent 7 enters the second container body 12 from above, passes around the auxiliary casing 17 and then, slipping into the opening 18, goes up towards the holes 9.

Are not different solutions excluded in which, for example, light 13? arranged at a different altitude and the air? in any case conveyed to the auxiliary casing 17 thanks to the arrangement of the elements inside the reactor itself.

Again with reference to the embodiment illustrated in the figures, in the second container body 12? housed a dividing partition 21 associated externally with the first container body 2 at the end? lower 11.

The dividing baffle 21 actually prevents the gasifying agent 7 from licking the lower portion 10, favoring the conveyance of the agent itself towards the opening 18.

Advantageously, in the second container body 12 there are two dividing baffles 21 spaced apart to form a thermal insulation gap.

As illustrated in the figures, the two dividing baffles 21 are arranged parallel and so as to create an interspace such as to thermally insulate the portions of the reactor 1 separated by the dividing elements themselves.

The interspace above? preferably filled with air, but the use of insulating materials such as, for example, rock wool or the like is not excluded. In addition to the container bodies described above, the reactor 1 comprises a conveying chamber 19 housed in the second container body 12 and associated with the lower portion 10 of the first container body 2.

Such a room? able to collect the synthesis gas 8 coming out of the first container body 2 to convey it outside the reactor 1, for example towards unit? filtering suitable to purify the gas from impurities? and / or towards user elements such as internal combustion engines or other users.

The conveying chamber 19 has at least one conveying duct 20 exiting from one of the ports 13 or from another point and adapted to remove the synthesis gas 8 from the reactor 1 at the outlet.

In particular the conveying duct 20? outgoing from the second container body 12 through the aforementioned opening 13.

As illustrated in the figures, the conveying duct 20? a tubular element with a diameter smaller than the port 13 and such as to pass through the port 13 without preventing the entry of the gasifying agent 7 into the reactor. Conveniently, the conveying chamber 19 comprises as many conveying ducts 20 as there are ports 13 present in the second container body 12.

In the present embodiment, the conveying chamber 19 has the shape of a cylinder with a circular crown section and? arranged in the reactor 1 interposed between the first container body 2 and the second container body 12.

The base of the conveying chamber 19? fixed to the lower portion 10 of the first container body 2 preventing the synthesis gas 8 from expanding thereafter. inside the second container body 12 and conveying it towards? external.

The base of the conveying chamber 19? connected to the lower portion 10 so as to define a volume 22 around the first container body 2 which, in the present embodiment,? closed at the top by the partition 21.

Usefully, this volume 22 can? be filled with material, for example sand or other siliceous material, designed to increase the thermal inertia of the lower portion 10.

So ? possible to increase the thermal inertia while maintaining more? constant the temperature of the surface of the lower portion 10 and thus avoid temperature peaks which can compromise the correct carrying out of the gasification reactions.

How does the present invention work? the following.

The gasifying agent 7 enters through the ports 13 and is conveyed towards the holes 9.

In particular, in the second container body 12 it proceeds through the opening 18, licking the extremity. lower 11 and the central portion 6. What? by doing so, the gasifying agent 7 removes heat from these elements and therefore operates a cooling which is useful for preserving them from thermal stress. Entering through the holes 9, the gasifying agent helps to carry out the gasification of the biomass present in the first container body 2. Here the synthesis gas 8 is formed which, sucked or pushed, proceeds through the lower portion 10 and, therefore, enters the conveying chamber 19. Here? conveyed out of the reactor 1 through the conveying ducts 20.

Yup ? in practice, it has been observed that the described invention achieves the proposed aims and in particular it is emphasized that the reactor for gasification plants devised allows the temperature of the walls to be lowered to a greater extent. hot parts of the reactor.

In particular, the conformation and arrangement of the auxiliary casing makes s? that the incoming air removes heat from the parts of the reactor most exposed to high temperatures.

So ? Is it possible to build the reactor with cheaper and more expensive materials? easily available on the market such as, for example, commercial steels.

The reactor devised, moreover, thanks to the shielding effect of the auxiliary casing and of the second container body, allows to reduce the thermal dispersion towards the outside.

Finally, this solution allows to increase the efficiency of the reactor.

In fact, before entering the first container, the gasifying agent undergoes a preheating.

This allows you to reduce the quantity? of heat to be supplied to the reactor itself to maintain the conditions useful for the thermochemical processes for the transformation of biomass into synthesis gas.

Claims (2)

CLAIMS 1) Reactor (1) for gasification plants comprising: a first container body (2) able to be filled at least partially with biomass to be gasified to obtain synthesis gas (8), provided with at least an upper portion (3) suitable for receiving biomass at the inlet, at least a central portion (6) suitable for to host an oxidation step of said biomass, said central portion (6) comprising holes (9) for the addition of a gasifying agent (7), and at least a lower portion (10) suitable for allowing the filoriestamento of said gasified biomass and said synthesis gas (8); characterized in that it comprises an auxiliary casing (17) which at least partially surrounds said central portion (6),? associated with said central portion (6) above said holes (9),? provided with at least one opening (18) obtained below said holes (9), and adapted to convey said gasifying agent (7) around said central portion (6). 2) Reactor (1) according to claim 1, characterized in that it comprises at least a second container body (12) entirely comprising said first container body (2) and associated with it in correspondence with said upper portion (3), provided with at least a port (13) adapted to allow the entry of said gasifying agent (7) into said second container body (12); 3) Reactor (1) according to one or more? of the preceding claims, characterized in that said central portion (6) comprises: an upper portion (6a) of substantially cylindrical conformation having an end? upper connected to said upper portion (3); And a lower portion (6b) substantially shaped like an inverted truncated cone, associated with said upper portion (6a) and having one end? lower (11) connected to said lower portion (10). 4) Reactor (1) according to claim 1, characterized in that said auxiliary casing (10) comprises: an upper section having a substantially cylindrical conformation which at least partially surrounds said upper section (6a); And a lower section substantially shaped like an inverted truncated cone that at least partially surrounds said lower section (6b), said opening (18) being defined at the base of said lower section to convey the passage of said gasifying agent (7) in proximity ? of said extremity? lower (11). 5) Reactor (1) according to one or more? of the preceding claims, characterized in that said second container body (12) comprises a discharge area (16) arranged below said first container body (2) and adapted to accumulate said gasified biomass coming out of said first container body (2). 6) Reactor (1) according to one or more? of the preceding claims, characterized in that it comprises a conveying chamber (19) at least partially housed in said second container body (12), associated with said lower portion (10) of said first container body (2) and adapted to collect said gas synthesis (8) coming out of said first container body (2). 7) Reactor (1) according to one or more? of the preceding claims, characterized in that said conveying chamber (19) comprises at least one conveying duct (20) exiting said port (13) and able to remove said synthesis gas (8) at the outlet from said reactor (1) . 8) Reactor (1) according to one or more? of the preceding claims, characterized in that said conveying duct (20)? outgoing from said second container body (12) through said port (13). 9) Reactor (1) according to one or more? of the preceding claims, characterized in that in said second container body (12)? housed a dividing septum (21) associated externally to said first container body (2) in proximity to of said extremity? lower (11), 10) Reactor (1) according to claim 9, characterized by the fact that in said second container body (12) there are housed two of said dividers (21) spaced apart to form a thermal insulation gap.