EP2655552A1

EP2655552A1 - Process for the pyrolysis of organic feedstock

Info

Publication number: EP2655552A1
Application number: EP10805202.8A
Authority: EP
Inventors: Prerak Goel; Christopher THANNHÄUSER
Original assignee: Thannhaueser Goel IP AG
Current assignee: Thannhaueser Goel IP AG
Priority date: 2010-12-20
Filing date: 2010-12-20
Publication date: 2013-10-30
Also published as: WO2012083979A1

Abstract

Process for the pyrolysis of hydrous organic feedstock, more particularly of organic wastes and biomass, featuring the following process steps: - a circulated inert heat-transfer medium (8) in piece form is heated in a preheater (1), - the heated heat-transfer medium (8) is introduced simultaneously with the hydrous feedstock into a pyrolysis reactor (2), - in the pyrolysis reactor (2) the feedstock is pyrolyzed, optionally with further addition of steam, - the mixture of pyrolysis gas and steam that is formed in the pyrolysis reactor (2) is reformed in a reforming reactor (3) to give a product gas having a high hydrogen content (first end product), - the pyrolysis coke (2) produced in the pyrolysis reactor is discharged from the pyrolysis reactor (2) together with the heat-transfer medium (8) and is separated off from the heat-transfer medium, and - the heat-transfer medium (8) separated off is recycled into the preheater (1). In order, in this process, to reduce the height of the plant construction and to avoid disruptively high temperatures in the region of the heat-transfer medium circuit, the invention proposes that the reforming reactor (3) is arranged separately from the heat-transfer medium circuit and is heated separately from said circuit.

Description

Process for pyrolysis of organic feedstock

The invention relates to a process for pyrolysis of hydrous organic feedstock, in particular of organic waste and biomass, with the following process steps: a) a lumped inert heat transfer medium circulated in the circuit is heated in a preheater, b) the heated heat transfer medium is mixed with the hydrous feedstock c) in the pyrolysis reactor, the feedstock is optionally pyrolyzed with further addition of steam, d) the mixture of pyrolysis gas and water vapor formed in the pyrolysis reactor is reformed in a reforming reactor into a product gas having a high hydrogen content (first end product), e) the pyrolysis coke formed in the pyrolysis reactor (second end product) is discharged out of the pyrolysis reactor together with the heat carrier and separated from the heat carrier, and f) the separated heat carrier is returned to the preheater.

Such a method is known, for example, from EP 1 337 607 and embodied in the appendix "Blauer Turm" (see www.blue-tower.de). knew method is the heat carrier, the z. B. may consist of heat-resistant ceramic balls, heated in the preheater with the aid of flue gas from a furnace to about 1100 ° C and entered in this state via a solids lock in the reforming reactor located below the preheater to there the heat required for the reforming in the enter required temperature range. As it passes through the reforming reactor, the heat transfer medium cools down to the temperature level required for heating the pyrolysis reactor (about 750 ° C.) and is in turn introduced via a metering device into the pyrolysis reactor underneath, to which the feed material is simultaneously supplied. The heat transfer medium then passes through the pyrolysis reactor together with the feedstock and, together with the pyrolysis coke produced during the pyrolysis, is discharged from the bottom of the pyrolysis reactor at a temperature of about 600.degree. After separation of the pyrolysis coke from the heat carrier, the heat carrier is then conveyed by means of an elevator up and entered via a lock again from above into the preheater. If the amount of water added to the hydrous feed is insufficient to reform, steam is also added to the pyrolysis reactor.

In the trial operation of the above-mentioned system, a number of problems has been found. On the one hand, the system inevitably has a relatively large overall height due to the guidance of the heat transfer circuit, so that the heat transfer medium for the return to the preheater must be lifted over a relatively long conveying path, which is unfavorable both energetically and wear. On the other hand, the heat transfer medium must be heated in the preheater up to 1100 ° C, ie up to the range of bright yellow heat, whereby the life of the one part of the heat carrier and the other part of the heat carrier leading plant parts, especially the solids sluices, can be greatly affected. Finally, in the known method of reforming process as a result of constantly present in the reforming reactor large heat transfer medium only poorly controllable and thus difficult to control. It is therefore an object of the invention to develop the method of the type mentioned in that the height of the system can be reduced and disturbing high temperatures in the heat transfer circuit can be avoided. Finally, it should be better possible to optimize the reforming process by a more accurate temperature control with a view to a better product yield and to a high hydrogen content in the product gas.

To solve this problem, the invention proposes starting from the method of the type mentioned above, g) that the reforming reactor is arranged separately from the heat transfer circuit and is heated separately from this.

In the method according to the invention, the heat transfer circuit comprises only the preheater and the pyrolysis reactor. As a result, the necessary height of the plant is reduced by about the height of the reforming reactor. Because of the reduced height, the delivery path for the return of the heat carrier is shortened accordingly. Furthermore, in the method according to the invention, the heat transfer medium only to the inlet temperature in the pyrolysis reactor, d. H. heated to about 800 ° C. As a result, the wear on the heat transfer medium and on the guide and transport means for the heat transfer medium decreases accordingly.

Because the reforming reactor is heated separately from the heat transfer medium circuit and pyrolysis coke in the process according to the invention, the reforming process can be controlled much more precisely with regard to optimized product discharge (product gas or pyrolysis coke) and optimized for the highest possible hydrogen content in the product gas.

A first, expedient embodiment of the invention provides that a subset of the product gas is diverted and is burned in a gas burner whose flue gas first heats the reforming reactor and then the heat carrier in the preheater. As a result, the process remains energy self-sufficient and enables optimized application to pyrolysis coke. This is particularly important in locations where the pyrolysis in agriculture z. B. is needed for soil improvement.

A second expedient embodiment of the invention provides that the entire pyrolysis coke or a separated subset of the pyrolysis coke is incinerated in a coke furnace whose flue gas first heats the reforming reactor and then the heat carrier in the preheater. Again, the process remains energy self-sufficient and allows optimized application of hydrogen-containing pyrolysis gas. This is especially important in locations where z. B. wants to generate electricity with a gas turbine or a gas engine, z. B. to fill the power generation gaps of electricity generating solar systems.

Optionally, it is also possible to combine the two last-discussed embodiments of the heating of the reforming reactor with one another in order to be able to produce more product gas or more pyrolysis coke as required and / or season.

Finally, one can also influence the amount of pyrolysis coke formed by adding air, oxygen or a mixture of air and oxygen into the pyrolysis reactor. This results in the pyrolysis additionally a precisely controllable substoichiometric combustion, which gasifies a portion of the carbon and additionally enters heat in the pyrolysis reactor.

The reforming process can in both cases - regardless of the particular energy source - take place in an externally heated reaction chamber of the reforming reactor. This has the advantage that the reforming process can be accomplished alone in the gas phase without interference by passing solids, if necessary in the presence of a catalyst which is located in the reaction space of the reforming reactor. Due to the presence of a suitable catalyst, it is known that the reforming process can be considerably intensified. Instead of an externally heated reaction chamber but the reforming process can also be carried out in a moving bed reactor, the circulating high-temperature heat transfer medium first by the flue gas of the gas burner and / or the coke firing heated preheating and then one of them through a solids sluice separated reaction chamber, the from flows through to be reformed pyrolysis gas. In this embodiment as well, it is possible to add to the circulating heat transfer medium a catalyst which is not polluted by the feedstock and can optionally be thermally, chemically or mechanically reactivated outside the reforming reactor or can be completely or partially replaced.

In order to use the sensible heat from the product gas, it may further be provided that the preheater upstream of the pyrolysis reactor is subdivided into two preheating chambers, which are successively passed through by the heat transfer medium and of which the one from the pyrolysis gas passed through and the other from the passed flue gas from the Reforming reactor is heated.

For the same purpose, alternatively or in addition thereto, the preheating chamber of the moving bed reactor may also be subdivided into two preheating chambers, which are successively passed through by the high-temperature heat carrier and one of which heats the product gas passing through it and the other from the flue gas of the gas burner and / or coke firing becomes.

Finally, to remove the sensible heat from the exhaust gas, it is finally provided that steam is generated for the reforming with the exhaust gas from the preheater.

Three embodiments of the invention will be explained in more detail below with reference to the drawing. Show it:

Fig. 1: Schematically the method according to the

Invention in a first embodiment; 2 shows schematically the method according to the

Invention in a second embodiment;

3 shows schematically the method according to the

Invention in a third embodiment;

4 shows schematically the method according to the

Invention in a fourth embodiment;

5 shows schematically the method according to the

Invention in a fifth embodiment.

In FIG. 1 of the drawing, a preheater with the reference numeral 1, a pyrolysis reactor with the reference numeral 2 and a reforming reactor with the reference numeral 3 are designated. Furthermore, the plant comprises a gas burner 4, a sieve 5, a product gas purification 6 and a steam generator 7.

The heat carrier 8 is formed by refractory ceramic balls, which are located for the most part in bulk in the preheater 1 and the pyrolysis reactor 2. The heat transfer medium 8 is circulated continuously and moves slowly from top to bottom first through the preheater 1 and then through the pyrolysis reactor 2, then as Siebrückhalt on the screen 5 and an elevator 9 back up into the preheater. 1

Between the preheater 1 and the pyrolysis reactor 2 between the screening plant 5 and the elevator 9 and between the elevator 9 and the preheater 1 are each not shown in detail, gas-tight solids sluices 10 are provided for the passage of the heat carrier 8.

The heat transfer medium 8 is heated in the preheater 1 to about 800 ° C and entered at this temperature from above into the pyrolysis reactor 2. At the same time with the heat transfer medium 8 is in the pyrolysis reactor 2 via an adding device 11 to be pyrolyzed water-containing organic feedstock in the form of organic waste or biomass input. In addition, in order to influence the resulting amount of pyrolysis coke, air or oxygen or a mixture of air and oxygen may be introduced into the pyrolysis reactor by means of an adding device 12.

On its way through the pyrolysis reactor 2, this feedstock is pyrolyzed with the addition of water vapor. The energy required for the pyrolysis provides the heat transfer medium 8, which accordingly cools in the pyrolysis reactor 2 from 800 ° C to 600 ° C. If air and / or oxygen are added, a stoichiometric combustion of carbon also takes place in the pyrolysis reactor 2, whereby optionally additional heat is introduced into the pyrolysis reactor.

The pyrolysis gas-steam mixture formed in the pyrolysis reactor 2, as indicated by the arrow 13, leaves the pyrolysis reactor 2 at about 630 ° C. in the direction of the reforming reactor 3 and is further treated there, as will be explained below.

The pyrolysis coke formed during the pyrolysis is discharged together with the heat transfer medium 8 via a discharge device 14 arranged downstream of the pyrolysis reactor 2 together with the heat transfer medium 8 and applied to the screening plant 5. There, the heat carrier 8 is retained as Siebrückhalt and fed to the elevator 9, which promotes the heat carrier 8 upwards and enters from above through the solids lock 10 in the preheater 1. In contrast, the pyrolysis coke separated off as a screen pass is conveyed to a product dispenser 15 where it is dispensed as the first product of the process.

The above emerging from the pyrolysis reactor 2 pyrolysis gas-steam mixture is entered into a heated from the outside, separate reaction chamber 16 of the reforming reactor 3 and there subjected to the reforming process. The heating of the reaction chamber 16 of the reforming reactor 3 via a reaction chamber 16 surrounding the heating jacket 17 which is flowed through by the hot flue gas of about 1100 ° C of the gas burner 4 and the reaction chamber 14 is heated accordingly. The product gas produced in the reaction chamber 16 by reforming is purified in the product gas purification unit 6 and sent to a product gas outlet 8 as a second process product.

The fuel required for the operation of the gas burner is a partial flow of the product gas which is supplied to the gas burner 4 via a gas line 19. The gas burner 4 is further associated with an air supply 20, via which the gas burner is supplied with air. By precise control of the air and gas supply of the gas burner 4, the amount of flue gas and flue gas temperature generated in the gas burner 4 can be controlled very accurately, whereby it is possible to precisely control the heat supplied to the reaction chamber 16 of the reforming reactor 3. For the same purpose, a part of the exhaust gas stream can also be recycled into the furnace. In this way, one can advantageously return a portion of the sensible heat from the exhaust gas to the process.

The exhaust gas from the heating jacket 17 is supplied via an exhaust pipe 21 to the preheater 1 to its heating. This exhaust still has a temperature of about 860 ° C, which is sufficient to heat the heat carrier located in the preheater 1 8 to the required about 750 ° C.

Because the amount of water supplied to the pyrolysis reactor 2 together with the feed material is sometimes insufficient to provide a sufficient amount of steam for reforming, steam is additionally introduced into the pyrolysis reactor 2. This additional steam is generated in a steam generator 7, which is expediently heated with the exhaust gas 22 from the preheater 1. The additional steam generated in the steam generator 7 is input via a steam line 23 from below into the pyrolysis reactor 2. The amount of steam can be controlled by the fact that the steam generator 7 via a water supply valve 24, a targeted amount of water is supplied.

In the embodiment of Figure 2 occurs in the place of the gas burner 4, a coke firing 34, which can be heated via a Koksleitung 37 with the pyrolysis or a subset of the pyrolysis coke produced. If necessary, the heating with product gas shown in FIG. 1 and the heating with pyrolysis coke shown in FIG. 2 can also be combined with one another so that the system can be combined with product gas, pyrolysis coke or combined heating with both heating means. If necessary, it is also possible to use heating means that are not from the plant. The latter is only useful if such heating means are available at low cost.

In the embodiment according to Figure 3, the reforming reactor 3 is designed as a moving bed reactor, which operates with a circulating high-temperature heat carrier 40, which consists of particularly temperature-stable ceramic balls, first in one of the flue gas of a gas burner (cf., the gas burner 4 shown in Figure 1) / or a coke-firing (cf the coke-fired furnace 34 of Figure 2) are heated and thereafter pass through a reaction chamber 42 through which the pyrolysis-gas-vapor mixture flows in order to release the heat absorbed in the preheating chamber 41, and then into the furnace via an elevator 43 Vorwärmkammer 41 to be returned. Because the high-temperature heat carrier 40 comes into contact exclusively with gases here, there are hardly any disturbing solids in the moving bed reactor or at its high-temperature heat carrier 40, so that the reforming process can be controlled very precisely.

Again, the flue gas used for the heating of the reforming reactor is then fed to the preheater 1 of the pyrolysis reactor 2.

The embodiment according to FIG. 4 additionally deals with the problem of using the sensible heat from the product gas. For this purpose, the preheater 1 resulting from FIG. 1 has been subdivided into two preheating chambers 1a and 1b. Both preheat chambers 1a and 1b are passed through by the heat carrier 8 and are connected to each other by a solids sluice. The preheating chamber 1a is - as in the embodiment of Figure 1 - heated by the flue gas from the heating jacket 17 of the reforming reactor 3. In contrast, the preheating chamber 1b is heated by the product gas flowing through it, which senses its sensible heat the heat carrier 8 delivers and only then the product gas cleaning 6 is supplied.

An alternative to the use of sensible heat from the product gas is shown in FIG 5. There, the resulting from Figure 3 preheating 41 of the moving bed reactor has been divided into two Vorwärmkammern 41 a and 41 b, which are separated from each other by a solids sluice and are traversed by the high-temperature heat transfer 40 , The preheating chamber 41a is heated by the flue gas of the coke firing 34 as in the exemplary embodiment according to FIG. 3, while the preheating chamber 41b is heated by the product gas which is supplied via a connecting line 44 between the reaction chamber 42 and the preheating chamber 41b and then via a connecting line 45 the product cleaning 6 is supplied.

Claims

claims

1. A process for pyrolysis of hydrous organic feedstock, in particular of organic waste and biomass, comprising the following process steps: a) a cycled lumped inert heat transfer medium is heated in a preheater (1), b) the heated heat transfer medium (8) is simultaneously c) in the pyrolysis reactor (2), the feed material is optionally pyrolyzed further with the addition of steam, d) the mixture of pyrolysis gas and water vapor formed in the pyrolysis reactor (2) is mixed in a pyrolysis reactor (2) Reforming reactor (3) to a product gas with a high hydrogen content (first end product) reformed, e) in the pyrolysis reactor (2) resulting pyrolysis (second end product) is discharged together with the heat carrier (8) from the pyrolysis reactor (2) and from the heat carrier (8) separated, and f) the separated heat transfer medium (8) is returned to the preheater (1),

characterized, g) that the reforming reactor (3) is arranged separately from the heat transfer circuit and is heated separately from this.

2. The method according to claim 1, characterized in that a partial amount of the product gas is diverted and is burned in a gas burner (4), the flue gas first the reforming reactor (3) and then the heat carrier (8) in the preheater (1) heated.

3. The method according to claim 1, characterized in that the pyrolysis or a separated portion of the pyrolysis coke is burned in a coke furnace (34), the flue gas first the reforming reactor (3) and then the heat carrier (8) in the preheater (1) heated.

4. The method according to one or more of claims 1 to 3, characterized in that in the pyrolysis reactor (2) additionally air, oxygen or a mixture of air and oxygen are entered.

5. Process according to claims 1 or 2, characterized in that the reforming process takes place in an externally heated reaction chamber (14) of the reforming reactor (3).

6. The method according to claim 5, characterized in that the reforming process in the reaction chamber (16) of the reforming reactor (3) takes place in the presence of a catalyst.

7. The method according to claim 2 and / or 3, characterized in that the reforming process takes place in a moving bed reactor, the circulating high-temperature heat transfer medium (40) first one of the flue gas of the gas burner (34) and / or the coke firing (4) heated preheating chamber ( 41) and thereafter one of them through a solids sluice separated reaction chamber (42) passes through which is traversed by the pyrolysis gas to be reformed.

8. The method according to claims 2 and / or 3, characterized in that the pyrolysis reactor (2) upstream preheater (1) is divided into two preheating chambers (1a and 1b), which are sequentially passed through by the heat carrier (8) and of which one is heated by the product gas passed through and the other by the passed flue gas from the reforming reactor.

9. The method according to claim 7, characterized in that the preheating chamber (41) of the moving bed reactor is subdivided into two preheating chambers (41a and 41b), which are successively passed through by the high-temperature heat carrier (40) and of which one of the continuous product gas and the other of the flue gas of the gas burner (34) and / or the coke (4) is heated.

10. The method according to one or more of claims 1 to 9, characterized in that with the exhaust gas from the preheater () steam is generated for the reforming.