DK175601B1 - Preparing a gasification gas for bio-fuel - comprises contacting flow of fuel with counter flow of gas generated by burning coal or hydrocarbon fuel in e.g. power station or boiler - Google Patents

Abstract

A flow of bio-fuel is contacted with a counter-flow of gas generated by burning coal or hydrocarbon fuel in e.g. power station or boiler. - A gasification method for bio-fuel comprises contacting counter-flows of bio-fuel and gasification medium in a reactor, the gasification medium comprising a gas generated by burning coal or other hydrocarbon fuels. The resulting gasification gas contains a combustible gas obtained by converting the tar content in the gasification medium. Water vapour is also recovered from the gasification medium for use in the gasification gas.

Description

DK 175601 B1 l

Method and Plant for gasification of biomass.

BACKGROUND OF THE INVENTION

The invention relates to a method and a plant for gasification of biomass according to the preamble of claims 1 and 5, where the tar content of the gas is fully utilized for gas production.

The gasification method and the plant are of the type consisting of an atmospheric countercurrent gasifier for gasification of biomass, where the fuel and gasification medium have opposite flow through the carburetor.

10 In the known gasification concepts of this kind, atmospheric air has been used as the gasification medium and the tar content of the gas produced has either been tried washed out with a gas washer and subsequently thermally cracked over an external coke bed, or tried cracked with a catalyst and subsequently filtered for being able to use the gas to operate a gas engine or it has been burnt directly in a gas boiler. In the plants where the tar is washed out, there are problems with getting rid of the tar water that is washed out of the gas. In the known gasification concepts, there are problems in maintaining the desired gasification temperature in the gasification zone, since the oxidation of the carbon in the gasification zone is difficult to control with the known temperature measurement methods.

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An example of a known plant is disclosed in GB-A 2158841, from which it is known to supply diesel exhaust gas to a carburetor together with water vapor and atmospheric air. The supply of the atmospheric air is necessary to initiate oxygenation of the fuel in the carburetor, thereby supplying energy to increase the temperature of the carburetor. However, oxygenation often causes some form of short-circuit in the carburetor, which results in the gasification being stopped and the fuel catching fire.

Invention 30 The invention provides a gasification method and plant of the kind mentioned above, but in which the tar content of the gas is converted into combustible gas. Simultaneously

DK 175601 B1 I

the present invention provides a gasification method and plant of the present invention

mentioned initially, where the gasification temperature is easy to control. IN

This is achieved according to the invention by a gasification method and the installation thereof

5 initially mentioned and characterized in that as gasification medium I is used

the combustion products from combustion of coal or hydrocarbon compounds. Hereby I

will the combustion products, from the combustion of the hydrocarbon compounds, add -

most of the energy (more than 50% of the energy) needed for I

gasification process. At the same time, for the gasification process, it will be needed

10 water vapor is supplied as water vapor is formed in the burning of hydrocarbons (using the combustion products from the combustion of coal it can, for

gasification process, necessary water vapor is supplied by injecting water into I

forgasningsmediet. The water will evaporate and become superheated before reaching it

the gasification zone). IN

With this gasification method and plant it is easy to control the gasification temperature

the energy and the temperature required for the gasification being supplied by means of I

forgasningsmediet. Today there are many systems for combustion of coal and I

hydrocarbon compounds capable of delivering the desired gasification medium

20 the desired temperature. IN

In a particular embodiment of the gasification method according to the invention, as in

gasification medium is used the combustion products from tar burning I

condensed / separated from the gasification gas produced with I

The gasification method. Hereby the combustion products, from the burning of the tar I, will

which is condensed / separated from the gasification gas, supply most of the energy I

necessary for the gasification process. IN

In another embodiment of the gasification method and plant according to the invention I

30, the combustion products from the combustion of I can be used as gasification medium

gasification gas produced by the gasification method and the plant. IN

In another embodiment of the gasification plant according to the invention, the gas from the gasification process is first filtered in a filter where the filter material consists of hay.

As a result, a large part of the tar in the gas is filtered out as hay possesses the ability to withhold heavy hydrocarbon compounds. When replacing filter material, the hay 5 with filtered tar can be fed into the carburetor and gasified together with the biomass.

The remainder of the tar in the gas is condensed / separated by the gas and used for the production of gasification media for the gasification process.

ΙΟ In another embodiment of the gasification plant according to the invention, straw can be used as a filter material instead of hay.

In another embodiment of the gasifier according to the invention, the bed of the carburetor can be used as a filter by compressing the bed mechanically thus by compressing the bed with a force 1/4 equal to the force of the mass of the bed material or greater.

In another embodiment of the gasification method of the invention, excess tar condensed / excreted by the gas can be fed to the gasification medium before being directed to the gasification zone. Hereby a thermal cracking of the tar is obtained by mixing with the hot gasification medium and a thermal cracking of the tar when passing through the hot gasification zone.

In another embodiment of the gasification method according to the invention, the gasification medium can be supplied to the gasification zone of the gasifier at a temperature lower than the temperature required for the gasification process. By burning the tar so that the combustion products (gasification medium) have an appropriate oxygen percentage, the temperature of the gasification zone can be adjusted to meet the conditions of the gasification process.

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I DK 175601 B1 I

I 4 I

In another embodiment of the gasification plant according to the invention, as in

In fuel, waste is used (such as chemical waste, household waste, construction waste,

Waste from demolition of buildings etc. as well as various other waste). IN

In a particular embodiment of the gasification plant according to the invention, as in

In gasification media, the combustion products of an existing I are used

In boiler / CHP plants fired with coal and / or hydrocarbon compounds. IN

This solves the problem of co-firing at the power plants as the chlorine compounds I

You will be left in the ashes from the gasification process. IN

I 10 I

In Figures I

In order to give a better understanding of the invention, there are attached 4 drawings which I

You will now explain in greater detail the following with reference to the drawings, in which:

In Figure 1, the principle of an atmospheric countercurrent gasifier for gasification of I is shown

In biomass, I

Figure 2 shows the principle of an atmospheric countercurrent gasifier for gasification of I

In biomass, with filtration of the gas, I

I 20 I

Figure 3 shows the principle of an atmospheric countercurrent gasifier for gasification of I

In biomass, with the addition of condensed tar to the gasification medium,

I and I

In Figure 4, the principle of an atmospheric countercurrent gasifier for gasification of I is shown

In biomass, with mechanical pressure setting of the bed. IN

In the Detail Description I

Figure 1 shows the principle of an atmospheric countercurrent gasifier for gasification of I

In 30 biomass. The principle is characterized in that the fuel and the gasification medium are fed into I

At each end of the carburetor and therefore has the opposite directed flow. The gas produced in

In the carburetor can be taken out several places on the carburetor. An example I is shown here

5 DK 175601 B1 where the gas is taken out at the same level as the fuel is supplied. It should be noted that it is not crucial whether the fuel is supplied at the top or bottom relative to the gasification medium.

Figure 2 shows the principle of an atmospheric countercurrent gasifier for gasification of biomass according to Figure 1, with filtration of the gas after the carburetor.

Figure 3 shows the principle of an atmospheric countercurrent gasifier for biomass gasification according to Figure 1, with the addition of condensed tar to the gasification medium.

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Figure 4 shows the principle of an atmospheric countercurrent gasifier for biomass gasification according to Figure 1, with mechanical pressurization of the bed.

I DK 175601 B1 I

I I

List of reference figures to Figures I

I l. Fuel I

I 2. Gasification gas I

I 3. Dry zone I

I 5 4. Pyrolysis zone I

I 5. Gasification zone I

I 6. Gasification medium I

I 7. Ashes I

I 8. Filter I

I 10 9. Condensed tar I

I 10. Mechanical pressure setting of the bed I

Claims (9)

1. A method for gasification of biomass in an atmospheric countercurrent gasifier, wherein fuel in the form of biomass and gasification medium has opposite flow through the carburetor, characterized in that as the gasification medium, the combustion products from combustion of coal 10 or hydrocarbon compounds are used, possibly with the addition of water vapor, supplies 50% or more of the energy needed for the gasification process. Method according to Claim 1, characterized in that the combustion products of combustion of tar separated from the gasification gas produced by this method and associated plants are used as the gasification medium. Method according to any one of claims 1 to 2, characterized in that the gasification medium is supplied to the gasification zone of the carburetor at a temperature 20 lower than the temperature required for the gasification process. Method according to any one of claims 1 to 3, characterized in that excess tar condensed or separated by the gas is fed to the gasification medium before it is led to the gasification zone. 25 5. Biomass gasification plant consisting of: an atmospheric countercurrent gasifier in which fuel (1) and gasification medium (6) have opposite flow through the carburetor, 30 a unit for combustion of coal or hydrocarbon compounds, DK 175601 B1 In a unit for supplying water or water vapor characterized by H 5 having the atmospheric countercurrent carburetor having a connection to the unit for combustion H of coal or hydrocarbon compounds and a connection to the unit for supplying water H or water vapor, and wherein the plant is dimensioned such that H combustion products supply 50% or more of the energy needed for the H gasification process. IN System according to claim 5, characterized in that the carburetor bed I is used as a filter (8) by compressing the bed mechanically (10) so that the bed I is compressed by a force 1/4 as large as the force of the mass of the bed material. or greater. IN Installation according to claim 5 or 6, characterized in that the gas from the gasification process is first filtered into a filter where the filter material consists of straw or hay. IN 7 DK 175601 B1 Plant according to one of claims 5 to 7, characterized in that H is used as fuel "(1) waste such as chemical waste, household waste, H construction waste, waste from demolition of buildings etc. and various other waste. H An installation according to any one of claims 5 to 8, characterized in that the unit for burning coal or hydrocarbon compounds is an existing boiler or. H CHP plants that are fired with coal and / or hydrocarbon compounds. H