DE102009035408A1 - Gasification of carbonaceous fuels with increased conversion rate - Google Patents

Abstract

In a gasification device, carbonaceous raw fuel milled to give dust is gasified to a raw gas rich in H and CO. From the raw gas filtered particles, in particular unconverted fuel dust are added to the raw fuel again. As a result, a non-optimal implementation of the fuel, which may be based on shortcomings of the gasification device or its operating parameters, be improved, the system efficiency can be increased and the disposal costs are minimized.

Description

The The invention relates to a method for fuel feed for an entrained flow gasification plant, in the dust at a pressure between 0.1 and 1 MPa to a rich in H and CO containing crude gas is gassed.

In order to be able to gasify coal by means of entrained flow gasification with dry coal feed, it is necessary to dry and grind the coal and to raise the coal, including conveying gas, to the gasification pressure. This is done according to the current state of the art in the following, essential process steps, see 1 , The raw coal is conveyed via suitable conveyor technology ( 1 ) a raw coal silo ( 2 ) and passes from there into the grinding drying plant ( 3 ). Depending on the water content of the coal, the drying and grinding steps can be combined in the mill or carried out separately using the coal dryer and coal mill. The generated coal dust is filtered through a filter ( 4 ) in a coal dust silo ( 5 ) stored. From there, the coal is conveyed via a pneumatic conveying system ( 6 ) into an intermediate bunker ( 7 ). From there, the coal passes through a lock system ( 8th ), in which the coal is pressurized, into a feed tank ( 9 ), from where the coal in turn pneumatically the air flow gasifier ( 10 ) is supplied.

The process steps ( 1 ) to ( 7 ) run at atmospheric pressure or only slight overpressure to overcome transport pressure losses. The process steps ( 9 ) and ( 10 ) run at high pressures, typically between 1 and 10 MPa (10 and 100 bar). The lock system ( 8th ) works with periodically changing pressures between gasification process pressure and atmospheric pressure of the intermediate bunker ( 7 ).

The entire process chain of coal processing from raw coal to to Flugstromvergaser represents a significant proportion of the effort for a coal gasification plant. For coal with high coalification such as hard coal, anthracite, petroleum coke competes this method also with the slurry gasification, wherein the slurry gasification regarding the investment costs is usually in the advantage.

From the US 4,465,496 An air flow gasifier is known in which ground petroleum coke is supplied as fuel purified to water slurry and in which unconverted coal particles collect in a water bath concentrated in a spreader to be mixed with the fuel.

Of the Invention is based on the object in an entrainment gasification plant with pneumatic fuel dust feed the requirements for a if possible, complete implementation of the supplied To reduce fuel dust.

The The object is achieved by a method having the features of the claim 1 solved.

According to the invention the resulting in the raw gas purification filter cake fed to the raw fuel. In the course of the partial oxidation in the entrained flow gasifier unconverted Fuel dust is filtered out of the raw gas and fed to the input side Mixed with dust. This can increase the plant efficiency (repeated gasification of unreacted carbon) and the disposal costs are minimized.

advantageous Further developments of the invention are in the subclaims specified.

The Invention will be described below as an exemplary embodiment to an extent necessary for understanding on the basis of Figures explained in more detail. Showing:

1 Essential process steps of coal preparation and production for entrainment gasification with dry feed according to the state of the art,

2 Substantial process steps of the coal preparation and conveying for the entrainment gasification with dry feed according to the present invention,

3 the treatment of flash gas and excess gas quantities and

4 the inventive recycling of the filter cake from the raw gas purification plant in the raw fuel mill drying.

In the same designations denote the same elements.

The main difference between the pneumatic conveying system ( 6 . 1 ) and the combination ( 6 * . 2 ) of lock and pneumatic conveying is the pressure. While the pneumatic delivery requires only low pressures - usually 1.5 to 3 bar, the pressure is increased and combined with the gasification process pressure 1 to 10 MPa (10-100 bar) including the pressure loss of the pneumatic conveying with the combination of lock and delivery this pressure into the feed tank ( 9 ) realized. In addition to the execution of ( 6 * ) as a combination of lock with pneumatic conveying the use of a dust pump is also possible.

A further education is through the in 3 ge dashed illustrated treatment of expansion and / or excess gas levels given.

Both in the lock release and due to the pneumatic transport of ( 6 * ) to ( 9 ) must be removed in some cases large amounts of gas. These could conventionally be dedusted in separate filter systems. When integrating coal mill drying and coal gasification, however, it makes sense to measure the amount of gas produced in the already existing filter ( 4 ) to dedust and thus save additional effort. For this purpose, the gases, such as nitrogen or carbon dioxide, must be throttled from the process pressure to atmospheric pressure and, depending on the type of gas, temperature conditions and the risk of dew point undershoots, a gas preheating of the gas quantities.

According to the in 4 The invention relates to the filter cake (wholly or partly), which in the raw gas purification ( 11 ) of the gasification process is obtained (dash-dot line) in the raw coal silo 2 recycled.

in the Partial oxidation in the entrained flow gasifier unconverted Fuel dust is filtered out of the raw gas and the input side added to supplied fuel dust. The non-conversion of the fuel dust can be due to inhomogeneities of the fuel, such as B. regarding Aufmahlungsgrad or mixture of different Fuel types, especially types of coal, but also on the optimum attributable to deviating operating parameters of the entrained-flow gasifier be.

The crude gas purification ( 11 ) can by filtering devices of different types, such. B. the type Venturi scrubber, centrifugal, membrane or candle filter be given.

The Return of the filtered particles from the Crude gas and the admixture to the fuel to be gasified continuously or cyclically.

LIST OF REFERENCE NUMBERS

1

Rohkohlefördertechnik

2

Rohkohlesilo

3

desiccation and grinding the coal (combined or separately)

4

dust filter

5

Kohlestaubsilo

6

pneumatic conveyor system

7

intermediate bunker

8th

lock system

9

feed tank

10

coal gasification

6 *

lock system with integrated pneumatic conveying or dust pump

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 4465496 [0005]

Claims (8)

Method for fuel feed for an entrainment gasification plant ( 10 ), in which a combustible dust is gasified at a pressure of between 0.1 and 1 MPa to a crude gas containing high amounts of H and CO - one in a raw fuel silo ( 2 ) stored raw fuel of a facility ( 3 ) is fed to the dust for grinding and drying of the raw fuel to fuel dust, - the fuel dust then in a fuel silo ( 5 ), then the combustible dust is introduced into a feed tank (at the pressure of the entrained flow gasification plant) ( 9 ), - then the fuel dust from the feed tank into the entrained flow gasification plant ( 10 ) is metered for gasification, - the raw gas of a crude gas purification produced in the entrained-flow gasification plant by gasification of the combustible dust ( 11 ) is supplied and - the resulting in the crude gas purification filter cake is fed to the raw fuel silo. A method according to claim 1, characterized in that the ground pulverized dust before Zwischenbunkerung a dust filter ( 4 ) goes through. Method according to one of the preceding claims characterized in that the raw gas purification in a Venturi scrubber he follows. Method according to one of the preceding claims characterized in that the raw gas purification in a membrane filter he follows. Method according to one of the preceding claims characterized in that the raw gas purification in a candle filter he follows. Method according to one of the preceding claims characterized in that the crude gas purification in a centrifugal separator he follows. Method according to one of the preceding claims characterized in that the return of the filtered particles from the raw gas and the admixture to the To be gasified fuel continuously or cyclically. Method according to one of the preceding claims 1 to 7, characterized in that the return the filtered particles from the raw gas and the admixture to cycled to be atomized fuel dust.

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