NL1032001C2

Preparation by torrefaction of a solid fuel useful as fuel for a coal-fired power plant involves heating a starting composition comprising a secondary recovered fuel material indirectly at specific mass temperature

Abstract

Preparation by torrefaction of a solid fuel involves heating a starting composition indirectly, where the heating takes place at a mass temperature of 150 to 360[deg]C and a secondary recovered fuel (SRF) material is present in the starting composition. Independent claims are included for the following: (1) removal of at least one metal from a solid fuel involving: providing a solid fuel or the solid fuel obtained by using the method; reducing the thus obtained solid fuel to a particle size of less than 3 (preferably less than 2, especially less than 1) mm; and separating the at least one metal from the reduced solid fuel thus obtained; and (2) method (P1) for reduction of the 'total chlorine content' of a solid fuel obtained by the method, involving: washing the solid fuel with a solvent, in which solvent chlorine compounds present in the solid fuel dissolve.

NL1032001C2, drawing sheet 1 — Sheet 1 of 2

Term

Term ended

Expired 14 June 2026, 0.3 years ago.

31 claims: 22 independent, 9 dependent

1
CONCLUSIES CONCLUSIONS 1. A method of torrefying a solid fuel preparation in which an initial composition is indirectly heated with the 1. Werkwijze voor het door torreficeren bereiden van een vaste brandstof, waarbij een uitgangssamenstelling indirect wordt verwarmd, met het 5 characterized in that the heating takes place at a mass temperature of about 150 to about 360 ° C, wherein an SRF material is present in the starting composition. 5 kenmerk, dat het verwarmen plaatsvindt bij een massatemperatuur van ongeveer 150 tot ongeveer 360 °C, waarbij in de uitgangssamenstelling een SRF-materiaal aanwezig is.
5
Process according to one or more of claims 1-4, wherein in the starting composition a total of 10 to 20% by weight, preferably 12 to 17% by weight, of water 5. Werkwijze volgens een of meer van de conclusies 1-4, waarbij in de uitgangssamenstelling totaal 10 tot 20 gew.%, bij voorkeur 12 tot 17 gew.% water 20 is present, based on the total weight of the starting composition. 20 aanwezig is, op basis van het totale gewicht van de uitgangssamenstelling.
6
The method according to any of claims 1 to 5, wherein the starting composition contains at most 5 wt.%, Preferably at most 2 wt.% Of impurities, based on the dry weight of the starting composition. 6. Werkwijze volgens een of meer van de conclusies 1-5, waarbij in de uitgangssamenstelling ten hoogste 5 gew.%, bij voorkeur ten hoogste 2 gew.% verontreinigingen aanwezig zijn, op basis van het droge gewicht van de uitgangssamenstelling. 25 25
7
Method according to one or more of claims 1-6, wherein the heating is performed in a rotating drum. 7. Werkwijze volgens een of meer van de conclusies 1-6, waarbij het verwarmen wordt uitgevoerd in een roterende trommel.
8
Method according to one or more of claims 1-7, wherein the heating takes place gradually until a mass temperature of between 260 and 360 ° C is reached. 8. Werkwijze volgens een of meer van de conclusies 1-7, waarbij de verwarming geleidelijk plaatsvindt totdat een massatemperatuur wordt bereikt van tussen 260 en 360 °C. 30 30
9
Method according to one or more of claims 1-8, wherein the residence time of the starting composition at a temperature between 150 and 360 ° C is less than 100 minutes, in particular less than 45 minutes and in particular between 10 and 30 minutes. 9. Werkwijze volgens een of meer van de conclusies 1-8, waarbij de verblijftijd van de uitgangssamenstelling op een temperatuur tussen 150 en 360 °C minder is dan 100 minuten, met name minder dan 45 minuten en in het bijzonder tussen 10 en 30 minuten.
10
Solid fuel available by a method according to one or 10. Vaste brandstof verkrijgbaar door een werkwijze volgens een of 1 33 2 0 01 - more of claims 1-9. 1 33 2 0 01 „ meer van de conclusies 1-9.
14
Solid fuel according to one or more of claims 10-13, wherein the solid fuel contains from 40 to 90% by weight of torrefied biomass, based on the dry weight of the solid fuel. 14. Vaste brandstof volgens een of meer van de conclusies 10-13, waarbij in' de vaste brandstof 40 tot 90 gew.% getorreficeerde biomassa aanwezig is, op basis van het droge gewicht van de vaste brandstof.
15
Solid fuel according to one or more of claims 10-14, wherein 10 to 60% by weight of torrefied plastics are present in the solid fuel based on the dry weight of the solid fuel. 15. Vaste brandstof volgens een of meer van de conclusies 10-14, waarbij in de vaste brandstof 10 tot 60 gew.% getorreficeerde kunststoffen aanwezig zijn op basis van het droge gewicht van de vaste brandstof.
16
Solid fuel according to one or more of claims 14-15, wherein torrefied biomass and torrefied plastics are present in the solid fuel, wherein at least a part, preferably at least 40 wt.%, And in particular at least 60 wt. % of the torrefied biomass is embedded in the torrefied plastics. 16. Vaste brandstof volgens een of meer van de conclusies 14-15, waarbij in de vaste brandstof getorreficeerde biomassa en getorreficeerde kunststoffen aanwezig zijn, waarbij ten minste een gedeelte, bij voorkeur ten minste 40 gew.%, en in het bijzonder ten minste 60 gew.% van de getorreficeerde biomassa is ingebed in de getorreficeerde kunststoffen.
17
Solid fuel according to one or more of claims 10-16, wherein the solid fuel contains at most 5% by weight, in particular at most 3% by weight, of impurities, based on the dry weight of the solid fuel. 17. Vaste brandstof volgens een of meer van de conclusies 10-16, waarbij in de vaste brandstof ten hoogste 5 gew.%, in het bijzonder ten hoogste 3 gew.% verontreinigingen aanwezig zijn, op basis van het droge gewicht van de vaste brandstof.
18
Solid fuel according to one or more of claims 10-17, wherein the solid fuel contains less than 5 wt.%, Preferably less than 3 wt.% Water, based on the total weight of the solid fuel. 18. Vaste brandstof volgens een of meer van de conclusies 10-17, waarbij in de vaste brandstof minder dan 5 gew.%, bij voorkeur minder dan 3 gew.% water aanwezig is, op basis van het totale gewicht van de vaste brandstof.
19
A method for removing one or more metals from a solid fuel, the method comprising the steps of:19. Werkwijze voor het verwijderen van een of meer metalen uit een vaste brandstof, welke werkwijze de stappen omvat van: het verschaffen van een vaste brandstof ;providing a solid fuel;comminuting the solid fuel thus obtained to a particle size of less than 3 mm, preferably less than 2 mm, in particular less than 1 mm, separating the one or more metals from the comminuted solid fuel thus obtained. het verkleinen van de aldus verkregen vaste brandstof tot een deeltjesgrootte van kleiner dan 3 mm, bij voorkeur kleiner dan 2 mm, in het bijzonder kleiner dan 1 mm, het van de aldus verkregen verkleinde vaste brandstof afscheiden van de een of meer metalen.
21
A method according to any one of claims 19-20, wherein comminution is performed by breaking the solid fuel. 21. Werkwijze volgens een of meer van de conclusies 19-20, waarbij het verkleinen wordt uitgevoerd door middel van het breken van de vaste brandstof.
22
The method according to one or more of claims 19-21, wherein the separation is performed by means of sieving. 22. Werkwijze volgens een of meer van de conclusies 19-21, waarbij het afscheiden wordt uitgevoerd door middel van zeven.
23
Method according to one or more of claims 19-22, wherein as the one or more metals aluminum is separated. 23. Werkwijze volgens een of meer van de conclusies 19-22, waarbij als de een of meer metalen aluminium wordt afgescheiden.
25
Cleaned solid fuel obtainable by a method according to any of the claims 19-24. 25. Gereinigde vaste brandstof verkrijgbaar door een werkwijze volgens een of meer van de conclusies 19-24.
27
Clean solid fuel according to one or more of claims 25-26, wherein 40 to 90% by weight of torrefied biomass is present in the fuel. based on the dry weight of the cleaned solid fuel. 27. Gereinigde vaste brandstof volgens een of meer van de conclusies 25-26, waarbij in de brandstof 40 tot 90 gew.% getorreficeerde biomassa aanwezig is. op basis van het droge gewicht van de gereinigde vaste brandstof.
28
Cleaned solid fuel according to one or more of claims 25-27, wherein 10 to 60% by weight of plastics are present in the fuel based on the dry weight of the cleaned solid fuel. 28. Gereinigde vaste brandstof volgens een of meer van de conclusies 25-27, waarbij in de brandstof 10 tot 60 gew.% kunststoffen aanwezig zijn op basis van het droge gewicht van de gereinigde vaste brandstof.
29
Cleaned solid fuel according to one or more of claims 27-28, in which the cleaned solid fuel contains torrefied biomass and torrefied plastics, wherein at least a part, preferably at least 40% by weight, and in particular at least 60 wt% of the torrefied biomass is embedded in the torrefied plastics. 29. Gereinigde vaste brandstof volgens een of meer van de conclusies 27-28, waarbij in de gereinigde vaste brandstof getorreficeerde biomassa en getorreficeerde kunststoffen aanwezig zijn, waarbij ten minste een gedeelte, bij voorkeur ten minste 40 gew.%, en in het bijzonder ten minste 60 gew.% van de getorreficeerde biomassa is ingebed in de getorreficeerde kunststoffen.
30
Cleaned solid fuel according to one or more of claims 25-29, wherein the fuel contains at most 0.5 wt.%, And preferably at most 0.1 wt.% Of metals based on the dry weight of the cleaned solid fuel. 30. Gereinigde vaste brandstof volgens een of meer van de conclusies 25-29, waarbij in de brandstof ten hoogste 0,5 gew.%, en bij voorkeur ten hoogste 0,1 gew.% metalen aanwezig zijn op basis van het droge gewicht van de gereinigde vaste brandstof.
31
Use of a solid fuel according to one or more of claims 10-18 or a cleaned solid fuel according to one or more of claims 25-30 or a combination thereof as a fuel for a coal-fired power plant. 31. Toepassing van een vaste brandstof volgens een of meer van de conclusies 10-18 of een gereinigde vaste brandstof volgens een of meer van de conclusies 25-30 of een combinatie daarvan als een brandstof voor een steenkoolcentrale. 1 03 2 0 01 «! 1 03 2 0 01 «! O O CO CO I o IK) o o temperature, o temperatuur, Figure 1 Figuur 1 COOPERATION TREATY (PCT) SAMENWERKINGSVERDRAG (PCT) RAPPORT BETREFFENDE NIEUWHEIDSONDERZOEK VAN INTERNATIONAAL TYPE REPORT ON NEWNESS RESEARCH OF INTERNATIONAL TYPE REPORT OF THE NEWNESS RESEARCH OF VERSLAG VAN HET NIEUWHEIDSONDERZOEK VAN INTERNATIONAAL TYPE INTERNATIONAL TYPE Number of the request for a novelty search Nummer van het verzoek om een nieuwheidsonderzoek Form PCT / ISA / 201 (second page) (January 2004) page 1 of 2 Formulier PCT/ISA/201 (tweede blad) (Januari 2004) bladzijde 1 van 2 Form PCT / ISA / 201 (continuation second page) (January 2004) page 2 of 2 Formulier PCT/ISA/201 (vervolg tweede blad) (Januari 2004) bladzijde 2 van 2 Number of the request for a novelty search Nummer van het verzoek om een nieuwheidsonderzoek REPORT OF THE NEWNESS RESEARCH OF VERSLAG VAN HET NIEUWHEIDSONDERZOEK VAN INTERNATIONAAL TYPE INTERNATIONAL TYPE Informatie over leden van dezelfde octrooiiamilie Information about members of the same patent family Form PCT / lSA / 201 (continuation sheet patent patent) (January 2004) Formulier PCT/lSA/201 (vervolgblad octrooilamaie) (Januari 2004) GEBREK AAN EENHEID VAN UITVINDING LACK OF UNITY OF INVENTION Octrooiaanvrage Nr.:Patent Application No .: SN 47129 NL 1032001 SN 47129 NL 1032001 AANVULLINGSBLAD B SUPPLEMENTARY SHEET B De Instantie voor Nieuwheidsonderzoek heeft vastgesteld dat deze aanvrage meerdere uitvindingen bevat, te weten: The Novelty Searching Authority has determined that this application contains several inventions, namely: 1. conclusions: 1-18 1. conclusies: 1-18 Method for preparing a solid fuel by torrefying, wherein an SRF material is present in the starting material, as well as the fuel obtained thereby. Werkwijze voor het door torreficeren bereiden van een vaste brandstof, waarbij in het uitgangsmateriaal een SRF-materiaal aanwezig, alsmede de daarbij verkregen brandstof. 2. conclusions: 19-31 2. conclusies: 19-31 A method for removing metals from a solid fuel, wherein the solid fuel is comminuted and the metals are subsequently separated, as well as the purified fuel obtained thereby. Werkwijze voor het verwijderen van metalen uit een vaste brandstof, waarbij de vaste brandstof wordt verkleind en de metalen vervolgens worden afgescheiden, alsmede de daarbij verkregen gereinigde brandstof. Het vooronderzoek werd tot het eerste onderwerp beperkt. The preliminary investigation was limited to the first subject.

Independent claims22

181 paragraphs in 4 sections, as filed

(57) The present application relates to a process for torrefying a solid fuel in which an initial composition is indirectly heated. The present invention also relates to a solid fuel obtainable by such a method. Furthermore, the present application relates to a method for removing one or more metals from a solid fuel. In addition, the present invention relates to a cleaned solid fuel obtainable by performing such a method. Finally, the present invention relates to the use of such fuels.

NL C 1032001

The content of this patent differs from the original filed description with claim (s) and possible drawing (s). The documents originally filed can be viewed at the Netherlands Patent Office.

The Netherlands Patent Office is the Office for Industrial Property, an agency of the Ministry of

Economics

Brief designation: Method for preparing a solid fuel and the resulting solid fuel by torrefication, method for removing one or more metals from a solid fuel and the cleaned solid fuel obtained thereby, as well as use of these fuels.

DESCRIPTION

The present invention relates to a method of torrefying a solid fuel in which an initial composition is indirectly heated. The present invention also relates to a solid fuel obtainable by such a method. In addition, the present invention relates to a method of removing one or more metals from a solid fuel and to a cleaned solid fuel obtainable by such a method. Finally, the present invention relates to the use of the present solid fuels.

Methods for preparing a solid fuel by torrefying wood are described, for example, in WO 2005/056723 and US 2003/0221363. In such methods, woody products, such as, for example, wood chips, wood sawdust or, for example, nut shells, are torrefied, whereby a solid fuel is obtained.

James R. Arcate's 2002 Wood Energy magazine titled "Global Markets and Technologies for Torrefied Wood in 2002" states that torrefied wood can be used in conjunction with coal to generate electricity in coal combustion plants.

French patent application FR 2 624 876 and WO 86/06930 relate to the torrefaction of plant materials containing lignin and in particular wood.

The problem with such methods is that woody products are necessary as a starting material to obtain a solid fuel. This has a number of drawbacks.

First, wood and woody products are natural materials, the supply quantity of which cannot be easily controlled. In many countries, such as the Netherlands, because of the limited

03 2 0 0 1 ;

available ground area no large-scale timber production operated. This has made it impossible to produce a stable, continuous amount of wood. If there is (temporarily) a small supply of wood, for example a seasonally dependent supply, the energy requirement will remain the same, if the energy demand remains the same, in order to continue to meet the energy need. For example, wood can be purchased from countries with a large-scale and more continuous wood production, such as Finland, the Baltic States and Canada. Thus, fuel production using the above method is dependent on purchasing from other countries, which is undesirable.

A second drawback of using wood as a starting material is the cost of the starting material. Wood is a costly product as it can also be used for other purposes, such as the furniture and paper industry. In addition, the costs will increase further if wood has to be purchased. The associated costs do not only concern the purchase of the wood material, but also the costs of transporting it. Thus, a wood-based solid fuel would exhibit a substantial and possibly even fluctuating price, which is undesirable.

A third drawback is environmental in nature. If wood has to be transported, this leads to pollution, which is undesirable. In addition, it is undesirable to use a product that can also be used for other purposes as a fuel. Furthermore, a product formed by torrefaction of wood will have a certain degree of particulate matter, which can cause problems during storage and transport and possibly lead to air pollution.

By "torrefying" or "torrefaction" is meant a process in which a starting material undergoes a certain heating treatment. The term torrefaction is commonly used for processes to improve the properties of biomass, such as for example roasting coffee beans or wood. During the torrefaction process, the biomass is slowly heated in an inert atmosphere, i.e. an (almost) oxygen-free atmosphere. The torrefaction treatment results in a solid product with a lower moisture content and a higher energy density than the starting material. The torrefaction process could also be referred to as mild pyrolysis in which organic compounds are partially decomposed and flammable gases are formed. About 70% of the initial weight and about 90% of the initial energy are retained, increasing the caloric value per unit volume.

If biomass is torrefied, this produces so-called torrefied biomass, which has a number of special properties. The first property is hydrophobicity; the material loses its natural property of moisture absorption and is therefore more stable in storage than the non-torrefied biomass (such as wood and charcoal, for example). Also, less smoke is generated when torrefied biomass is burned compared to when non-torrefied biomass is burned.

According to European laws and regulations, “pure biomass” is formed by a stream in which the share of biomass exceeds 97%. Flows with a biomass share of less than 97% are referred to as “impure biomass”. By biomass in this description is meant dry, dead biomass, for instance in the form of dead plant material or dead wood.

Fuel biomass has received increasing attention in recent years. There are two reasons for this: firstly the fact that fossil fuels will be exhausted in the future and secondly because biomass fuel is more environmentally friendly than fossil fuel.

The big advantage of burning biomass is that it is almost CO2-neutral process. It is true that CO comes from burning biomass2 free, however this has recently (i.e. the past 1-25 years) been extracted from the atmosphere by the plants from which the biomass is formed. Thus, biomass combustion fits into the existing CO2cycle. This is a big difference with the burning of fossil fuels where CO2 that has been stored in the earth for so long that in practice this fuel was no longer part of the CO2cycle. In this way CO burns as it were by burning fossil fuel2 "Added" to the C02cycle. Therefore, there is a great demand for improved fuels in which biomass is used. However, as described above, there are drawbacks to using wood as a starting material for making a solid fuel.

The Dutch government has set a reduction target for CO2emission determined in the Netherlands. Special attention is also paid to the role that biomass can play in energy generation. Biomass is already used on a small scale in the Netherlands as a fuel for generating green electricity. A so-called coal covenant has been concluded with the operators of coal-fired power stations in the Netherlands. This covenant states that at least 10% of coal must be replaced by a sustainable alternative fuel, such as biomass.

However, the disadvantage of using untreated biomass, such as wood, as fuel is that it has a lower energy yield and cannot be used directly in existing combustion plants.

In principle, solid fuels based on biomass obtainable by torrefaction processes could be used for this, but these products have a number of drawbacks, as already explained above.

It is an object of the present invention to solve the above-mentioned problems.

Another object of the present invention is to provide a process for preparing a solid fuel in which there is a continuous, guaranteed supply of starting material.

The present invention also aims to provide a solid fuel suitable for use as a fuel for a multitude of combustion plants, preferably without further required pre-processing.

A further object is to provide a process which can provide a solid fuel with a good yield.

Yet another object is to provide a solid fuel which has a high energy density and / or which contains little particulate matter, which is advantageous during storage and transportation.

It is also an object of the present invention to provide a solid fuel which contributes to the reduction of CO2-emission.

One or more of the above objects are achieved by a method according to the preamble characterized in that the heating takes place at a mass temperature of about 150 to about 360 ° C, wherein an SRF material is present in the starting composition.

The present invention provides a solution to the above-mentioned problems in that SRF materials are used in the starting composition.

The present inventors have found that by subjecting SRF material to a torrefaction treatment, a solid fuel can be obtained with surprisingly good properties.

SRF is a term known in the art of secondary solid fuels and waste treatment. It is short for “Secondary Recovered Fuel”, which stands for “secondary recovered fuel”. Such secondary fuels are produced in so-called mechanical separation installations, based on industrial waste flows and / or household waste flows.

Household waste is a very heterogeneous mixture of, among other things, vegetable, fruit and garden waste, plastics, metals, such as ferrous and non-ferrous metals, inerts, such as sand, stone and glass. Household waste has a moisture content of more than 30% by weight. Household waste is usually incinerated in so-called WIPs (waste incineration plants) to destroy the waste and generate energy as a side effect. However, this processing method gives a low energy yield per ton of waste.

Another method of processing household waste, namely pyrolysis (heating at temperatures of about 500 ° C to 800 ° C), has proved to be technically and economically not feasible, as has been shown from various installations known in the area. The disadvantages associated with the use of household waste include: its high moisture content with associated high biological activity and odor nuisance.

WO 83/00046 discloses that household waste can be subjected to an indirect heating treatment method at a temperature of between 250 and 500 ° C, which corresponds to a torrefaction treatment. However, the product obtained by this treatment method cannot be referred to as a solid fuel. Furthermore, this method is not suitable for large-scale application. It has thus proved impossible to convert raw household waste to solid fuel by torrefaction.

SRF is formed using, for example, biological mechanical separation methods (BMS) or mechanical biological separation methods (MBS) from industrial waste streams and household waste streams. This achieves maximum recovery of raw material and production of a solid fuel. Such waste processing is increasingly being used as an alternative to waste incineration plants.

SRF is produced in the above separation plants in which the following process steps are carried out: the waste is brought to a defined particle size; the moisture content is reduced; ferrous metals, non-ferrous metals and inerts are removed. SRF contains a combination of plastics, biomass, water and contaminants.

The SRF obtained has defined properties in terms of: the dry matter content, the percentage of impurities, the calorific value, the particle size, the elemental composition and the percentage of biomass present therein. These properties may differ depending on the waste material used as starting material and the processing methods used.

Since SRF has undergone various treatments and also has defined properties, SRF is not seen as a partial stream of household or commercial waste, but as a product obtained from a waste stream (commercial and / or household waste), for which there are separate applications and markets. The use of SRF in torrefaction to obtain a solid fuel has not been previously described or proposed.

With the ever-increasing consumption and increasing production of waste, the amount of SRF material that can be produced will only increase. Waste production is continuous and therefore a continuous supply of starting material is available for the process of the present invention.

An example of a commercially available SRF useful in the method of the present invention is a mixture marketed under the registered trade name "Trockenstabilat". Trockenstabilat (brand) is a relatively dry SRF material with a dry matter content of approximately 85% by weight and a water content of approximately 15% by weight. Trockenstabilat (brand) contains approximately 65 wt% biomass, 9 wt% plastics, 25 wt% other fossil materials and approximately 1 wt% inert. This SRF material is produced from a partial stream of household waste. In the method according to the present invention it is also possible to use an SRF material which is made from industrial waste. A combination of several SRF materials is also applicable.

The direct use of such secondary fuels (SRF7 material) in combustion plants is possible, however this often leads to lower conversion efficiencies. The present inventors have found that these lower conversion efficiencies are largely due to: the lower heating value of these fuels compared to, for example, coal; the scale of the combustion installations used, as a result of which the technical optimization is not completely economically viable. The physical properties of any contaminants of SRF material are often also a limiting factor for use in existing incineration plants.

A further limiting factor in the direct use of SRF in incineration plants is the fact that SRF generally has a very low bulk density of approximately 150-250 grams per liter. Therefore, the amount of energy per m3 limited and economically viable transport can only take place with special means of transport and under special facilities, such as compaction in press containers or bales.

Another limiting factor in the direct use of SRF in incineration plants is the fact that the SRF particle size cannot be processed in existing coal-fired power stations. In addition, SRF does not show the optimal fire behavior. If SRF is to be fired in the existing coal-fired power stations, a thorough technical adjustment of the existing infrastructure is necessary. Especially if these plants are built according to the modern concept of pulverized coal-fired plants. Particle size and ignition behavior are of great importance in these plants and SRF does not comply with this. It is technically, economically and energetically impossible to reduce SRF to a particle size of less than about 3 mm, which is the minimum required for a pulverized coal fired power plant.

The present inventors have found that the present solid fuels are excellent for use in pulverized coal fired power plants.

Coal-fired power stations are used, among other things, to generate electricity for households and companies, among others. In coal-fired power stations, various types of coal with different compositions are mixed into a so-called “blend” which is then burned. The “blend” is chosen to obtain an optimal price-yield ratio.

The incineration products of coal-fired power stations, such as fly ash, are subject to requirements by the concrete and cement industry regarding the amount of heavy metals and trace elements that may be present therein. The reason for this is that these fly ash is frequently used in concrete and as cement replacements, for which legal requirements have been established for the amount of heavy metals and trace elements.

The present inventors have surprisingly found that the use of SRF material in a torrefaction process to obtain a solid fuel leads to excellent results in heavy metal and trace element contents.

The solid fuel obtained using the present process can be used in coal-fired power stations without fundamentally changing the logistics infrastructure of the plants.

The present solid fuel, obtained using SRF, contains a certain biomass equivalent. The amount of biomass originally present in the starting material is torrified to torrefied biomass or biomass equivalent.

By burning a solid fuel comprising a certain amount of biomass equivalent according to the present invention, a contribution is made to the aforementioned reduction target for CO2emission in the Netherlands. The percentage reduction of the CO2emission is calculated on the percentage of biomass present in the fuel and thus this percentage will vary with varying percentages of torrefied biomass in the present solid fuel. The present solid fuel can be used as one of the components of the above-described "blend" for coal-fired power stations or can replace this "blend" in its entirety.

Thus, the present invention provides a fuel that contributes to the reduction of CO2-emission without the use of the precious raw material wood.

The solid fuel of the present invention has a higher bulk density than the raw material, i.e.,> 350 grams per liter, which increases the solid fuel transportation capabilities. With such a bulk density, it is economically viable to transport the fuel unsealed and as bulk material by ship, train or truck, in contrast to the transport of untreated SRF material.

It would therefore be useful to also set up an installation in which the SRF can be converted into a solid fuel in the geographic vicinity of an installation where SRF is produced. This solid fuel not only has a higher bulk density and energy density, but also a higher economic value.

Torrefaction of SRF also leads to a reduction in the presence of certain heavy metals and trace elements such as cadmium, lead, mercury, sulfur and nitrogen.

In addition, the fly ash which is produced as a residual product at pulverized coal-fired coal-fired power plants using the present solid fuel has a composition that meets the requirements imposed on it by the customers.

Preferred embodiments of the present inventions are explained below.

Figure 1 shows an overview of a temperature profile of a torrefaction treatment according to the present invention.

In a preferred embodiment of the present invention, at least 50 wt%, preferably at least 75 wt%, and in particular at least 90 wt% SRF material is present in the starting composition based on the dry weight of the starting composition .

The phrase "based on the dry weight of the starting composition" means the percentage by weight that is present based on the weight of the dry ingredients of the starting composition, thus excluding water. The dry weight is determined in accordance with DIN NEN 12880 (February 2001).

The advantage of using at least 50 wt% SRF is that good results are obtained with regard to the reduced amount of particulate matter in the fuel obtained. In addition, an excellent bulk density is obtained and the cost of the solid fuel is reduced, since SRF is a cheap product, that is to say at the moment additional payments are made in the Netherlands when SRF is purchased. The amount of particulate matter in the solid fuel can be further reduced by using at least 75 wt% SRF material in the starting composition and even more by using at least 90 wt% SRF material in the starting composition. It is of course also possible to use up to 100 wt% SRF material as the starting composition. See also the results from Table 1, below.

If less than 100% by weight of SRF material is used, the starting composition may further comprise, for example, biomass, plastic fractions, paper fractions and cardboard fractions and the like.

By appropriately choosing the starting composition, the properties of the obtained solid fuel such as particle size, composition, amount of particulate matter and the like can be adjusted and selected depending on the desired application of the final fuel.

In a preferred embodiment of the present invention, there is provided a method in which from 30 to 80% by weight of biomass is present in the starting composition based on the dry weight of the starting composition. By 30 to 80% by weight of biomass is meant the total amount of biomass present in the total of the starting composition, i.e. in both the SRF material and in additional additives, such as biomass. The currently available SRF contains on average between 30 and 80% by weight of biomass, in particular about 60% by weight. If an SRF material is used in which the amount of biomass is judged to be insufficient, it is possible to add additional biomass to the starting material.

Biomass as used in the present invention can for instance consist of mixtures of (dried) waste residues of vegetables, fruit, food residues, grass waste, vegetable waste from the agricultural sector, woody constituents, paper, cardboard and the like.

By mixing SRF and biomass flows and possibly plastic fractions in a certain ratio, any desired starting composition and thus any desired solid fuel composition can be obtained. A fuel is thus obtained with a constant, reproducible and predetermined composition, which offers great advantages.

In another preferred embodiment of the present invention, it is preferable that 20 to 70% by weight of plastics are present in the starting composition based on the dry weight of the composition. By 20 to 70% by weight of plastics is meant the total amount of plastics, that is to say the plastics that can already be considered as a component of SRF and any additional added plastics.

As plastics can be mentioned, for example, laminates, packaging films, synthetic fabrics, rubber-like materials and the like. The plastics can be thermosetting or thermoplastic. However, in view of the desired properties of the obtained solid fuel, in which plastic softening plays a role, as will be further explained hereinafter, it is preferred that at least a portion, more preferably at least 50% by weight, be in the in particular at least 75 wt% and in particular at least 90 wt% or even 100 wt% of the plastics present are thermoplastic plastics.

Such thermoplastic plastics are partially or completely softened (plasticized) by the indirect heating used in the present process. The softening of SRF materials and other plastics leads to granulation of the final product. An advantage of granulate is that it is easy to transport, store and further process. A further advantage of the softening of the coastal materials, which advantage has surprisingly been found by the present inventors and which hitherto was completely unknown, is that any particulate matter and fine biomass particles present in the starting material or formed during the process are embedded in the softened plastics, whereby a virtually dust-free product is obtained, which is not possible using known methods of the prior art. The virtually dust-free product simplifies storage, transport and processing.

It is preferred that 10 to 20% by weight and preferably 12 to 17% by weight of water is present in the starting composition based on the total weight of the starting composition, i.e. the dry weight including water. Most SRF materials as available commercially are moisture retaining (at least 12% water). The final water content of the starting material is not only determined by the water content of the SRF material, but also by the water contents of any additional added biomass and / or plastics. If necessary, an additional drying step can be performed on the starting composition before the torrefaction treatment is performed to obtain a starting composition with a desired water content. Such a drying step can be carried out, for example, using (residual) heat that is released during the torrefaction process.

It is preferred that the present method be carried out continuously, with feedstock being continuously fed to the torrefaction device. During this process, (residual) heat will be obtained, which can be used, for example, for a possible drying step of the starting composition which is torrified at a later time.

The starting composition preferably contains at most 5% by weight and in particular at most 2% by weight of impurities, such as, for example, metals.

All components that are not biomass, plastics and water are regarded as impurities according to the present invention, even if these components themselves still have commercial value after separation.

Commercially available SRF material contains certain concentrations of chemical elements. The concentration of such chemical elements in fuels for combustion plants is limited by laws and regulations. This includes chemical elements such as chlorine, cadmium, lead and mercury. SRF material often contains metal particles, i.e. particles of both ferrous metals and non-ferrous metals, but in particular the non-ferrous metal aluminum. During the production of SRF material, ferrous metals are removed using magnets, among others, and non-ferrous metals are removed, for example, using eddy current. However, aluminum is usually still found in SRF material as part of the layer structure of plastic laminates and other packaging residues. Depending on the intensity and thoroughness of the separation that takes place in the production of SRF from commercial or household waste, the weight percentage of such contaminants will vary.

The present inventors have found that using the present method it is possible to separate such impurities from the solid fuel, as will be further explained below. Such contaminants can be torrefied, as a result of which they end up in the present solid fuel in modified or unaltered form.

The heating according to the present method is preferably carried out in a rotating drum, also called a rotating drum. Turning drums are already used in waste incineration, pyrolysis, calcination and other heat treatments of bulk goods. The present inventors have shown that rotary drums are also particularly suitable for performing the present method. Fluidised bed techniques can also be used, for example, or other techniques. The present process can be carried out using commercially available equipment.

Preferably, the mass temperature during torrefaction is gradually increased to a mass temperature of between 260 and 360 ° C. By mass temperature is meant the temperature from the starting composition during the torrefaction process to the final product obtained, namely the solid fuel. During heating at a temperature of about 90-100 ° C, the softening of thermoplastic plastics will start, which leads to gas development from about 150 ° C. By softening thermoplastic plastics, part of the biomass will, as it were, stick to the softened coastal substances. The torrefaction gases formed are captured and can be burned, whereby the released heat can be used to further heat the product. In addition, formed flue gases can be passed through a heat exchanger to recover heat that can be used again in the torrefaction process. By carefully choosing the starting composition, the temperature range and the residence time, an accurate process management can be obtained, which means that after starting the process no extra energy from outside is needed because the process can meet its own energy needs.

The present inventors have found that by appropriately selecting the mass temperature and the percentage of plastics in the output composition, the amount of torrefaction gas released can be determined. Such torrefaction gas can be burned in order to obtain energy, which makes it possible to carry out an automatic process.

The mass temperature is then increased and at a temperature of about 160 to 180 ° C, decomposition of thermoplastic plastics, among others, occurs. A temporary stabilization in the temperature can also occur, after which the temperature increases further to the final temperature, which is chosen between, for example, 260 and 360 ° C, depending on, inter alia, the starting composition and the desired product.

The residence time of the material to be torrefied at the temperature used may vary depending inter alia on the choice of starting material, the temperature and the desired properties of the final solid fuel. Preferably, the residence time is less than 100 minutes, in particular less than 45 minutes, and in particular the residence time is between 15 and 30 minutes. Residence time is the time during which the starting composition is kept at a temperature of between 150 and 360 ° C during the torrefaction process.

The present method also relates to a solid fuel obtainable by a method of the present invention.

It is preferred that the solid fuel be granular. The granulate size is preferably less than 40 mm and in particular less than 10 mm. The size of the granulate will partly determine its application and any further processing thereof. The present inventors do not wish to be limited by any particular theory, however, assume that the granulate size is largely determined by the size of the starting material. During the torrefaction process, these plastic chips or plastic particles present in the SRF material will soften and biomass will be embedded in these softened plastic particles to form a granulate of the solid fuel. Thus, an SRF material with a larger particle size will lead to a solid fuel with a larger granulate size. The granulate formation is further influenced by the temperature settings during the process and the method of processing.

The granulates formed can be brittle and the brittleness is determined, inter alia, by the formulation, the choice of raw materials, the temperature settings and the residence time and can therefore be controlled. The brittleness can be important, for example, when processing the solid fuel, for example if it is to be reduced.

The granulates formed can also have a certain and sometimes even a high degree of porosity. This porosity can be influenced by the choice of raw materials and process conditions.

SRF can exhibit a certain degree of dustiness, that is, it contains a certain proportion of small particles. This dust share can be reduced or even completely eliminated by the torrefaction process of the present invention where the dust particles are embedded in the softened plastics.

In a preferred embodiment of the solid fuel of the present invention, 40 to 90 wt% torrefied biomass is present in the solid fuel based on the dry weight of the fuel. Torrefied biomass is understood to mean biomass that has been subjected to torrefaction treatment. Compared to the starting material, a slightly higher percentage of biomass may be present in the solid fuel since some of the other components, such as plastics, for example, will disappear in gaseous form during the decomposition process. It is particularly preferred that between 10 and 60% by weight of torrefied plastics be present in the solid fuel based on the dry weight of the solid fuel. The amount of torrefied plastics in the torrefied solid fuel is lower than the plastics content in the starting composition since some of the plastics are decomposed and gasified during the torrefaction process.

In a preferred embodiment of the present invention both torrefied biomass and torrefied plastics are present in the solid fuel with at least a portion, preferably at least 40% and in particular at least 60% of the torrefied biomass being embedded in the torrefied plastics.

As already mentioned above, softening of the thermoplastic plastics occurs during the torrefaction process. In such a softened state, dust particles and the currently torrefied or not yet fully torrefied biomass particles will be partially incorporated and embedded in the torrefied plastics to obtain composite granulate.

It will be understood, however, that another portion of the torrefied biomass, especially the slightly larger particles, will not be embedded in the torrefied plastics and will be separately contained in the solid fuel.

A further advantage of the fact that portions of the torrefied biomass are embedded in the torrefied plastics is that the solid fuel of the present invention contains little to no dust since some or all of this dust is embedded in and retained in the torrefied plastics .

In a preferred solid fuel according to the present invention, at most 5% by weight and in particular at most 5% by weight of metals is present based on the dry weight of the solid fuel.

These metals can, for example, consist of ferrous and non-ferrous metals.

Preferably, in the solid fuel is less than 5 wt%, in particular less than 3 wt. % and in particular less than 1% by weight of water is present based on the total weight of the solid fuel. The content of water in the starting composition is lowered by the torrefaction process whereby this water is converted into steam.

The lower calorific value is preferably greater than 18 MJ / kg, in particular greater than 20 MJ / kg, which is determined by DIN 51900-1 (April 2000 + February 2004).

The present invention also relates to a method of removing one or more metals from a solid fuel, the method comprising the steps of:

providing a solid fuel, reducing the solid fuel thus obtained to a particle size of less than 3 mm, preferably less than 2 mm, in particular less than 1 mm, separating from the reduced solid fuel thus obtained a or more metals.

The present method of removing one or more metals from a solid fuel can be used, inter alia, to further purify the solid fuel obtained by one or more of the aforementioned methods or applied to any of the aforementioned solid fuels.

It is preferable that the reduction of the obtained solid fuel is performed by breaking the solid fuel. Reducing the solid fuel by breaking is preferable to, for example, grinding the solid fuel. By breaking only the granulate is reduced, while the size of metal particles, such as aluminum particles, is not affected. Such metal particles thus retain their original size (length x width), which simplifies the separation of granulate and metal particles.

The breaking can be performed, for example, using a roller construction, such as a crushing roller chair with adjustable slit opening, or with a jaw crusher or comminuting device with similar effect. The particles thus obtained can have an angular or shard-like shape.

The separation is preferably carried out by means of sieving. Sieving is a simple technique whereby the comminuted particles with a particle size of less than, for example, 3 mm can be separated from metal particles present in the solid fuel which have a larger diameter. Other separation techniques such as cyclonage, upflow techniques or eddy current can also be used to separate the metals. With the present invention it is possible to separate substantially quantitatively metals from the solid fuel.

It is preferable to separate aluminum as the one or more metals present. Aluminum is a metal that can be recycled well and aluminum scrap has a high energy content and also a high economic value. Therefore, it is an advantage of the present invention that aluminum (aluminum scrap) can be extensively recovered from the solid torrefied fuel so that it can be sold as a separate by-pass.

A further advantage of separating aluminum is that aluminum, if present in the solid fuel, can lead to problems in combustion plants. If aluminum is burned, it is possible that so-called pyrophoric aluminum is formed, which is highly flammable and can lead to fires that cannot or hardly be extinguished in combustion plants. Thus, the present method of aluminum separation provides a much safer fuel, moreover, the precious aluminum is reused and not burned.

In addition, it is an advantage that the fly ash obtained in pulverized coal fired power plants by burning the aluminum-cleaned solid fuel has lower levels of alumina, which may be beneficial. The amount of fly ash is reduced in its entirety by removing one or more metals from the solid fuel.

Aluminum is often present in waste in the form of laminates, i.e. embedded in very thin layers between, for example, layers of plastic. This aluminum present in laminate cannot be easily separated due to the strong bond with the adjacent plastic layers. The present torrefaction process separates aluminum from the plastics when the plastic layers soften and / or carbonize. Aluminum will be present in the solid fuel as "unbound" particles.

The present invention also relates to a cleaned solid fuel obtained by the above method.

The particle size of the resulting cleaned solid fuel is preferably less than 3 mm, in particular less than 2 mm, and in particular less than 1 mm. Reducing the fuel to such a size simplifies the removal of one or more metals, which retain the original size.

Solid fuels with a particle size of <1 mm can be used directly in the incinerator of a coal-fired coal-fired power plant. Solid fuels with a particle size between 1 and 3 mm can be fed into a coal-fired mill, where they are reduced to a particle size of <; 1 mm.

The cleaned solid fuel of the present invention preferably contains 40 to 90 wt.% Torrefied biomass and 10 to 60 wt. % plastics as also described above for the solid fuel. Also, in the cleaned solid fuel, preferably torrefied biomass and torrefied plastics are present, wherein at least a part, preferably at least 40 wt.% And in particular at least 60 wt.% Of the torrefied biomass is embedded in the torrefied plastics as also described above.

The amount of metals in the cleaned solid fuel is preferably at most 0.5 wt%, in particular at most 0.1 wt%, and is therefore significantly reduced from the metal content in the solid fuel before cleaning according to the present method.

The present invention also relates to the use of a solid fuel or a cleaned solid fuel of the present invention or a combination thereof as a fuel that can be fired in a coal power plant. The advantage of this is that the aforementioned reduction in CO2emission can be achieved.

The present invention will now be further illustrated by the following non-limiting examples.

Examples

A starting composition was prepared by mixing a certain amount of SRF consisting of 60% by weight of biomass and 38% by weight of plastics and 2% by weight of impurities, and a certain amount of biomass, of the type B wood. The starting material was treated in a rotating drum with a temperature profile, the starting material being heated to 330 ° C for a total of 45 minutes. The product obtained is assessed on a number of properties: granulate formation, amount of particulate matter, fire behavior, CO2-reduction, suitability as bulk material, dust formation during breaking and percentage of volatile compounds in the solid fuel. These properties are assessed on the basis of the following criteria: - - very poor, - poor, o moderate, + good, ++ very good.

Granulate formation is judged more positively as a larger proportion of the solid fuel is granulate.

The amount of particulate matter is judged more positively the smaller the amount of particulate matter in the solid fuel.

Burning behavior is judged more positively the smaller the size of the granulate particles formed.

CO2-reduction is assessed more positively the more biomass is present in the solid fuel.

Suitability as a bulk good is judged more positively the better compromise is obtained between a high bulk density, a small amount of particulate matter and a high porosity. Such a compromise makes it possible for the solid fuel to be transported well as bukeware without having to be compacted with, for example, a ship, train or truck.

Dust formation during breaking is rated more positively the less dust formation occurs during breaking. This property is particularly important because of the safety during the breaking process, which will decrease with a larger amount of dust.

Percent volatile compounds in the solid fuel will be judged more positively as the wt% volatile compounds present in the solid fuel increases. Such volatile compounds are highly flammable and improve the combustion behavior of the solid fuel.

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Table 1

<td>In front of- statue</td><td>SRF wt. % on base from dry clot</td><td>extra biomass wt% op basis of dry dust</td><td>wt% biomass in output composition</td><td>wt% plastics output composition</td><td>granulate formation</td><td>quantity fine dust</td><td>fire- behaviour</td><td>co,- reduction</td><td>suitability as bulk goods</td><td>dust formation while break</td><td>percentage volatile connections solid fuel</td>

In Table 1, Examples 1-8 and Comparative Example 1 *

As will be apparent from Table 1, the solid fuels of the present invention exhibit better granulate formation and particulate matter results than the solid fuel of Comparative Example 1. Furthermore, it will be clear from the Table that solid fuels with an increasing proportion of SRF in the starting composition give better results with regard to granulate formation, amount of particulate matter, fire behavior, suitability as bulk material and dust formation during breaking, without the properties regarding CO2-reduction and percentage of volatile compound are deteriorated excessively.

Table 2 shows the weight loss for a starting composition according to Example 8 during the torrefaction process, depending on the mass temperature. As can be seen from the table, weight loss increases with increasing mass temperature.

Table 2

<td>Mass temperature</td><td>Example 8 -% weight loss</td>

Table 3 shows the correlation between the percent weight loss of the starting composition during the torefaction process and the residence time at a temperature of 300 ° C. This table shows that with increasing residence time, the percentage of weight loss increases.

It should be noted that weight loss is beneficial once the weight lost comes from water and low calorie compounds. This increases the percentage of high-caloric compounds in the solid fuel and thus also the energy density. However, as soon as high-caloric compounds are also lost, no increase in energy density will be noticeable and in fact combustion of solid fuel occurs, which is undesirable. Therefore, the amount of weight loss should be appropriately selected depending, inter alia, on the composition of the starting composition.

Table 3

<td>Residence time</td><td>Weight example 8</td>

The percentage of weight loss is partly determined by the size of the granulate (better heat conduction with smaller size) and process conditions (influence the heat transfer).

An example of a temperature profile of the mass temperature during the present torrefaction treatment is shown in Table 4 and Figure 1.

Table 4

<td>Time (min)</td><td>mass temperature ° C</td>

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