WO2009093107A1

WO2009093107A1 - Agitating pyrolysis and gasification reactor

Info

Publication number: WO2009093107A1
Application number: PCT/IB2008/055575
Authority: WO
Inventors: Haci Mehmet Arslan
Original assignee: Haci Mehmet Arslan
Priority date: 2008-01-21
Filing date: 2008-12-30
Publication date: 2009-07-30
Also published as: TR200800384A2

Abstract

The present invention relates to an internal agitating counter flow pyrolysis gasifier reactor (1) which will enable regular distribution of the fuel in the oxidation and reduction zones (9) during production of various combustible gases from all kinds of fossil sources and other wastes by pyrolysis and gasification methods. In the pyrolysis zone (4) of the reactor, homogeneous heat distribution is provided by regularly moving the distribution of the fuel by an agitating system and oxidation is perpetuated by preventing bridging at the oxidation zone whereby oxidation speed in the oxidation zone can be increased by means of the agitator (5) and it is also ensured that the agitator (5) is cooled.

Description

AGITATING PYROLYSIS AND GASIFICATION REACTOR

Field of the Invention

The present invention relates to a reactor used in pyrolysis and gasification of biomasses, all kinds of fossil wastes, intense carbon containing combustible and inflammable industrial wastes.

Background of the Invention

Pyrolysis gasifier biomasses use all kinds of fossil sources and other wastes or mixtures with similar features with the purpose of producing various combustible gases by the method of pyrolysis and gasification. The produced pyrolysis gases are utilized to produce electrical energy and/or heat energy via internal combustion engines, gas turbines, and conventional boiler steam turbines.

Mixtures of biomasses and wastes are not homogeneous; they exhibit a rather wide range. According to the types of sources, the major waste materials are domestic and industrial wastes, hospital wastes, cardboard and paper wastes, materials containing wood and cellulose, sawdust, furniture industry wastes, coal, shells of fruits and nuts, sewage sludge, leather industry wastes, animal slaughterhouse wastes, dried dung of small and big animals, rubber and plastic wastes, sugar beet wastes, waste oils and waste liquid fuels, pulp, petroleum sludge, bones, agricultural wastes, all kinds of biomass waste material mixtures.

Increasing interest in the widespread use of pyrolysis and gasifiers based on chemical treatment of especially domestic solid wastes and industrial wastes as a result of the latest developments in the fossil based raw material market, is the result of the fact that the conventional methods such as burning and burying in the ground which are employed in the existing technology in order to use these waste materials but pose environmental concerns have environmental impacts yielding irrepairable results and that the said methods are not economical any more.

The general processing form of the mostly known pyrolysis and gasifiers at the present time is the method of intermittent operation. The fact that the slag and molten slag form a bridge in the gasifier reactor hindering the material flow within the reactor, causes discontinuous flow of fuel, and on the other hand leads to the product gas obtained to contain a high amount of tar. Furthermore, the molten slag resulting from the high zonal temperatures which arise in the oxidation zone during gasification process and which are not equally distributed can not be discharged from the reactor completely and may cause obstruction of the system.

In the prior art, during pyrolysis and gasification of wastes with high ash ratios, ashes with high carbon content can be yielded from the reactor. Elimination of these high carbon content ashes afterwards may cause problems. As a result of these known difficulties, conventional gasifiers operate until the gasification process is complete. Subsequently, the process of cleaning the slag and molten slag accumulated in the high temperature zone of the gasifiers together with the high carbon content ashes by means of mechanic methods is adopted.

Undesirable operation conditions occurring during the startup of the gasifier and the fact that the tar content of the gas produced increases in the case that the gasifier is operated in low temperatures (<700°C) during its normal use are of other problems caused by the intermittent operation of gasifiers. The tar contained in the obtained gas may reach levels that hinder use of the product gas.

The European patent document No. EP0297425, an application known in the art, relates to a pyrolysis reactor. It discloses processing waste materials containing hydrocarbons by way of measuring the temperature difference in the fluidized bed reactor. The Canadian patent document No. CAl 194275, one of the applications known in the art, discloses a pyrolysis reactor which aims to realize production of certain fine sized particles of silicon.

The European patent document EP0687692, another application known in the art, relates to a process employed for obtaining a product with the waste polymer thermally cracking in a reactor. It is disclosed that the products cracked in the process pass through a bed reactor and that there are calcium oxides in the medium in reaction conditions at 400 - 600°C.

Summary of the Invention

The objective of the present invention is to provide a counter flow pyrolysis gasifier reactor with internal agitator which will ensure regular distribution of fuel in the oxidation and gasification zones during production of various combustible gases by means of the method of pyrolysis and gasification of all kinds of fossil based sources and other wastes.

Another objective of the invention is to perpetuate oxidation by preventing bridging in the oxidation zone and to ensure that air reaches into the fuel at the oxidation zone by means of an agitator, oxidation speed is increased and the agitator is allowed to be cooled.

Detailed Description of the Invention

The "Counter Flow Agitating Pyrolysis Gasifier Reactor" realized to fulfill the objective of the invention is illustrated in the accompanying figure, in which;

Figure 1 is the view of the Counter Flow Agitating Pyrolysis Gasifier Reactor. The components given in the figure are individually numbered where the numbers refer to the following:

I . Counter flow agitating pyrolysis gasifier reactor 2. Fuel feeder

3. Drying zone

4. Pyrolysis zone

5. Agitator

6. Agitator air tube and air diffuser 7. Agitation system

8. Upper passage zone

9. Reduction zone

10. Air inlet holes

I 1. Upper oxidation zone agitator air diffusion holes 12. Upper passage

13. Upper passage air gap

14. Upper passage air inlet valve

15. Agitator air inlet tube

16. Lower passage zone 17. Gas outlet tubes

18. Agitator air inlet valve

19. Lower passage

20. Lower passage air gap

21. Lower passage air inlet valve 22. Ash discharge helix

23. Ash discharge air insulation valve

The inventive counter flow agitating reactor (1) comprises a fuel feeder (2) for feeding fuel by means of a valve helix, a drying zone (3), an agitator (5) disposed right below the drying zone which ensures regular dispersion of the fuel within the reactor and a pyrolysis zone (4) provided alongside the agitator (5), tubes (6) within the agitator (5) system which enable passage of air and diffusion thereof within the agitator (5), and an agitation system (7) which enables agitation thereof, a fuel feeder (2) on the reactor, a passage zone (8) right below the pyrolysis zone (4) where the oxidation occurs, an air diffusion passage which is provided below the passage zone and which forms the upper section of the reduction zone (9) and air inlet holes (10) which provide certain amount of air to the lower passage forming the lower section of the reduction zone (9), upper oxidation zone agitating air diffusion holes (11) which inject certain amount of air by means of the air tubes (6) within the agitator (5).

The upper passage zone (8) located above the reduction zone (9) narrows down and twines like a cone in order to facilitate fuel flow towards the bottom of the gasifier. The upper passage (12) which is twines like a cone is produced by special welding methods from a high temperature resistant (>1250°C) specially alloyed, corrosion and high heat resistant material to be arranged onto the inner surface of the counter flow agitating pyrolysis gasifier reactor.

The agitator air tube and holes (6) help the air diffusion in the oxidation zone (8). The air supplied to the air inlet holes (10) is received into the reactor via the upper passage air gap (13) located between the inner part and the outer wall of the reactor. Air is accepted to the said gap (13) via the upper main air inlet valve (14). Intake of air into the agitator air inlet tube (15) is enabled by means of the agitator air inlet valve (18) via the same air inlet tube.

All of the air inlet holes (10) entering into the gasifier except the agitator air tubes (6) are arranged on the surface of the narrowing passage zone (12) and 25 cm to 30 cm distant from the uppermost and lowermost parts of the narrowest passage (9).

The upper passage (12) reaches the reduction zone (9) by extending downwards towards the inside of the conical lower passage zone (16). There are provided gas outlet tubes (17) on the outer wall surrounding the reduction zone (9) and the product gas is collected therefrom.

The second passage (19) forming the lower part of the reduction zone (9) enables the ashes resulting after gasification to flow and accumulate. The ash flow zone is also conical in order to facilitate accumulation of the ashes. The second lower passage (19) of the reactor is incorporated to the inner surface of the reactor (1) on the same axis with the air diffusion passage (12).

The air provided by the air inlet holes (10) is taken in upon passing from the outer surface of the lower passage (19) to the upper passage air gap (13). Intake of air into the lower passage air gap (20) is carried out via the air inlet valve (21). The ash-slag mixture remaining at the end of the gasification process is discharged by means of the ash discharge helix (22) which is air insulated from the lowermost point of the reactor and the air insulation valve (23). The gas produced in the reactor is taken out of the reactor by means of the gas outlet tubes (17) which generate negative pressure. High temperature occurring in the oxidation zone (8) causes temperature to reach 500°C - 600°C in the pyrolysis zone (4) and to 100⁰C - 200°C in the drying zone by way of the heat rising upwards. This medium that is created enables the pyrolysis reactions required for the gas formation to take place.

The counter flow agitating pyrolysis gasifier reactor (1) is operated continuously upon starting gas production within 15 minutes following the first ignition depending on the fuel mixture.

As a result of the researches conducted with the purpose of eliminating the difficulties arising in the other pyrolysis systems known and used in the industry, it is found that an internal agitating reactor was required which will enable regular distribution of the fuel in the pyrolysis, oxidation and gasification zones. In the pyrolysis zone (4) of the said reactor (1), homogeneous heat distribution is provided by regularly moving the distribution of the fuel by an agitating system and oxidation is perpetuated by preventing bridging at the oxidation zone (8) and by enabling air to reach into the fuel at the oxidation zone (8) by means of the agitator (5) oxidation speed can be increased and the agitator (5) can be cooled. While the gas flow within the oxidation zone (8) of the reactor (1) is enabled to be downwards in the same direction with the fuel flow, in the lower zone (16), gas flow is enabled to be upwards in the opposite direction of fuel flow.

In the reactor (1) system, in the first oxidation zone (8) the biomass is partially oxidized. Tar and oil of the pyrolysis gases are partially oxidized in the reactor upper zones by the heat radiation coming from the lower oxidation zone. The biomass and wastes that carbonize due to oxidation are reduced whereby ashes are generated. The process comprises gasification of also the ungasified carbon within the ashes during oxidation and passing the produced combustible gas through the passages before exiting the reactor (1), and following the treatment of the tars within the gas at a temperature of 1000⁰C or more that results in the said zone, outputting the gas from the reactor (1) by means of the outlet tubes (17).

Operation temperature of the pyrolysis zone (4) at the upper zone of the reactor (1) is 350⁰C - 650⁰C. Temperature of the first oxidation zone (8) is above 1000°C. Temperature of the reduction zone (9) is 700⁰C - 800⁰C. Operation temperature of the lower passage zone (16) is 550⁰C - 750⁰C. Thanks to this feature of the gasifϊer, by using the gas generated in the second oxidation zone (16), the tar of the raw and hot gas generated during the gasification process is ensured to be effectively cleaned.

The produced gas is output from the reactor (1) upon being sucked by the vacuum pump located outside of the reactor (1). Thus by enabling operation of the reactor (1) in negative pressure, leakage of the gas produced in the reactor (1) is absolutely prevented. Furthermore, in the case that the vacuum pump is not operational or is out of order, since the air received within the reactor is only provided by the vacuum pump via the holes inside the reactor (1), air intake stops and since the oxygen which is received into the reactor with the air is hindered, generation of combustible gases within the reactor (1) is prevented and gas accumulation therein is hindered. Thus it is ensured that the reactor (1) remains safe.

In order to enhance the efficiency of the reactor (1) and to return a part of the heat energy carried by the produced combustible gas back to the reactor (1) when leaving the reactor (1), the output gas is passed through the heat exchanger; and it is injected to the oxidation zones (8) of the reactor (1) and before it is taken into the oxidation zones (8) from the agitator via the vacuum pump, it is also circulated through the zones of the reactor (1) which are exposed to high temperatures whereby it is enabled to be heated more and it is ensured that the inner surfaces of the reactor (2) are cooled.

In another preferred embodiment of the invention, in order to attain pyrolysis gas in the upper pyrolysis zone (4) where pyrolysis gas generation is realized and oxidation in the upper passage zone (8) in the reactor (1) within a wider fuel mass, a plurality of agitators (5) is used depending on the volume of the reactor (1). By increasing the number of agitators (5), a balanced heat transfer is provided in the pyrolysis zone and the air is allowed to reach into the fuel in the upper passage zone (8) and regular pyrolysis gas generation and oxidation occur, whereby gasification can be performed with larger volumes due to regular pyrolysis gas generation and oxidation.

Claims

1. A counter flow agitating pyrolysis gasifier reactor (1) comprising a fuel feeder (2) and a valve helix that enables input thereto, a drying zone (3), an agitation system (7), a fuel feeder (2) on the reactor (1), a passage zone

(8) where the oxidation occurs, an upper passage (12) that narrows down and twines like a cone in order to facilitate fuel flow, an upper passage air gap (13) located between the inner part and the outer wall of the reactor enabling receipt of the air supplied to the air inlet holes (10) into the reactor, an upper main air inlet valve (14) which enables air to be accepted to the said gap (13), an agitator air inlet tube (15), an agitator air inlet valve (18) by means of which air intake is provided, a conical lower passage zone (16) which reaches the reduction zone (9) by extending inwards and downwards, gas outlet tubes (17) on the outer wall which enable collection of the product gas surrounding the reduction zone (9), a second passage (19) forming the lower part of the reduction zone (9) enabling the ashes resulting after gasification to flow and accumulate, a lower passage air gap (20) at which intake of air is realized by means of the air inlet valve (21), an ash discharge helix (22) air insulated from the lowermost point of the reactor (1) and an air insulation valve (23) by means of which the ash-slag mixture remaining at the end of the gasification process is discharged; and characterized by an agitator (5) which is disposed right below the drying zone and ensures regular dispersion of the fuel within the reactor, a pyrolysis zone (4) provided alongside the agitator (5), tubes (6) within the agitator (5) system enabling passage of air and diffusion thereof within the agitator (5), upper oxidation zone agitating air diffusion holes (11) which inject a certain amount of air by means of the said tubes (6), an air diffusion passage which is provided below the passage zone (8) and which forms the upper section of the reduction zone (9), and air inlet holes (10) providing certain amount of air to the lower passage forming the lower section of the reduction zone (9).

2. A counter flow agitating pyrolysis gasifier reactor (1) according to Claim 1, characterized by an agitator (5) comprising tubes (6) through which air passes.

3. A counter flow agitating pyrolysis gasifier reactor (1) according to Claim 1 and 2, characterized by a plurality of agitators (5) depending on the volume of the reactor (1) which allow enlarging the volume of the reactor

(1) and enables carrying out pyrolysis gas production of larger fuel masses in the upper pyrolysis zone (4) and regular oxidation thereof in the upper passage zone (8) and consequently provide production of product gas in larger volumes and enables operation of the reactor (1) to be carried out continuously.