DE102011009903A1 - Producing brown coal coke useful for power generation, comprises drying raw brown coal, carbonizing dried brown coal, and storing the energy-rich gas produced during the carbonization, in a gas reservoir - Google Patents

Abstract

Producing brown coal coke (1), comprises drying (3) raw brown coal (2), carbonizing (5) the dried brown coal, and storing the energy-rich gas (7) produced during the carbonization, in a gas reservoir. An independent claim is also included for a system for producing brown coal coke, comprising a device for drying the raw brown coal to a water content of 10-20 wt.%, a device for carbonization the dried brown coal, and a reservoir for the energy-rich gas obtained during the carbonization.

Description

The invention relates to a method and a system for producing lignite coke.

Lignite is a fossil fuel that is preferably used for power generation, with brown coal about one third of the energy density of hard coal. For the industrial use of lignite a further processing of the raw lignite coal processing plants is necessary, for example by crushing, drying and molding to various solid fuels, such as briquettes, lignite dust or fluidized lignite.

The drying of lignite is an energy consuming process due to the large amounts of water to be removed. In order to be able to process lignite into gaseous and liquid products as well as high-grade solid fuels, the water content must be reduced to 10 to 20% by weight, depending on the production target. An energetically efficient process for drying lignite is fluidized bed drying (WTA technology) with internal waste heat recovery in accordance with WO 2010/057509 , The WTA technology works on the principle of stationary, low-expansion fluidized bed. The energy required for drying is coupled via steam-heated heat exchangers, which are installed in the fluidized bed dryer. The drying takes place in quasi 100% pure steam, which is slightly overheated. Depending on the temperature of the steam, equilibrium is established at constant pressure between the temperature of the steam and the residual moisture of the dry coal. By controlling the fluidized bed temperature, the water content can be adjusted and kept constant at the desired value.

Another way of upgrading the coal to produce a more carbon-rich and cleaner fuel of uniform quality is by coking the lignite, with the lignite being heated to exclusion of air. The volatiles in the lignite are pyrolyzed by heating to a temperature of 900 ° C to 1400 ° C, released and sucked off. Degassing of the brown coal forms a porous lignite coal coke, which essentially contains carbon. The crude gas is decomposed by fractional condensation in the so-called. "Carbon values" tar, sulfuric acid, ammonia, naphthalene, benzene and Kokereigas.

The Kokereigas served for a long time as city gas for the supply of households, before it was replaced by natural gas. Nowadays the coke oven gas is used in the industry. For this purpose, the coking gas is buffered for example in a disc gas container and then transported away for further use via a gas network. The known disc gas containers serve because of their volume as a buffer for pressure regulation within the gas network. A long-term storage of the coke oven gas over several hours is not possible.

The invention has for its object to optimize the process of brown coal beneficiation energetically, to reduce emissions and in particular to allow a more flexible use of the resulting coke oven gas.

The object is achieved by a method for producing lignite coke, comprising the steps of drying the brown coal, coking the dried lignite and storing the high-energy gas produced during the coking in a gas storage.

Saving the high-energy gas in a gas storage in the sense of the invention means that the high-energy gas can be stored for at least 12 hours in the gas storage, preferably for at least 24 hours.

The drying of the raw lignite coal and subsequent coking of the dry lignite coal produces a lignite coke which achieves a high energy density and, in contrast to the lignite coal, has good transportability. The energy density of the lignite coal coke produced corresponds approximately to the energy density of hard coal. The good transportability of the lignite coke produced allows, for example, a transport of the lignite coal coke produced by water. The storage of the high-energy gas generated in the coking in a gas storage has the advantage that the high-energy gas can be fed during peak load times in the utility grid and can be stored during low load periods in the gas storage.

According to one variant of the invention, the brown coal is dried to 10 to 20 wt .-% water content. The dried lignite can be coked more efficiently in the following, since less water must be expelled from the lignite.

In a preferred variant of the invention, the stored energy-rich gas is supplied to a gas power plant, preferably during an increased load of a power network to be supplied. The gas power plant may be designed for example as a gas engine or gas turbine and serves to generate electricity. The stored high-energy gas can thus be used to compensate for heavily loaded times in a power grid. Furthermore, the stored high-energy gas be used to restart the gas power plant after a total shutdown, the high-energy gas thus allows a so-called. Schwarzstart capability of the gas power plant.

According to a particularly expedient variant, the heat produced in the gas-fired power plant is supplied to lignite drying for further use. The heat generated in the gas power plant is thus used to reduce the energy consumption for drying the lignite coal.

According to one variant of the invention, the coked brown coal is subjected to a coke quenching, in particular a Kokstrockenkühlung. As soon as the coking lignite comes into contact with oxygen, the coking lignite begins to burn at the prevailing temperatures. To prevent this, the coked brown coal is extinguished and cooled. In the case of coke quenching, a distinction is made between quenching with coke wet water and coking dry cooling, for example with nitrogen as an inert gas. According to the invention, a Kokstrockenkühlung preferred because it allows energy recovery, no water consumed, has a low dust formation and ensures a higher coke quality due to the lower water content.

In a particularly preferred variant of the invention, the heat produced in the coke cooling is supplied to the lignite drying and / or the gas power plant for further use. The waste heat of the coke cooling is thus used to reduce the energy consumption of lignite drying and to increase the energy generated in the gas power plant.

According to a further variant of the invention, the heat produced during the coking of the brown coal is supplied to the brown coal drying or the gas power plant for further use. The use of the waste heat produced by the coking of the dry lignite leads to an energetic optimization of the method according to the invention and helps to reduce emissions.

The object is further achieved by a system for producing lignite coke according to the method of any one of claims 1 to 7, comprising: a device for drying lignite, preferably to a water content of 10 to 20 wt .-%; a device for coking the dried lignite, and a storage for the high-energy gas produced during the coking. After drying the raw lignite in the apparatus for drying lignite to a water content of 10 to 20 wt .-%, the dried lignite is fed to a device for coking the dried lignite. In the apparatus for coking the dried lignite, the dried lignite is heated to a temperature of 900 ° C to 1400 ° C with exclusion of air, the volatile constituents in the lignite are pyrolyzed, released and sucked off. The lignite coke produced by the coking has approximately the same energy density as hard coal with a residual water content of 3 to 4% by weight and a volume which corresponds to one quarter of the volume of the lignite coal. The lignite coke produced is pourable and easy to transport, especially by water.

The high-energy gas produced during coking is stored in a memory and can be fed into a gas network if required, especially during periods of heavy load.

According to a variant of the invention, the system further comprises a device for cooling the lignite coke and / or a gas power plant, in particular a gas turbine or a gas engine. The device for cooling the lignite coke is preferably a coke dry cooling. The gas-fired power plant can be supplied with the stored high-energy gas and thus compensate for the higher energy demand in a power grid by the energy generated at peak load times. Furthermore, the stored high-energy gas can be used to restart the gas power plant after a total shutdown (black start capability).

In a variant of the invention, the system further comprises heat transfer lines, which are designed such that the heat generated in the gas power plant is supplied to the apparatus for drying the brown coal and / or in the apparatus for cooling the lignite coke and / or in the apparatus for Coking the brown coal resulting heat the gas power plant and / or the device for drying the lignite is supplied. The heat transfer lines may be formed, for example, as pipes through which hot steam can be passed. Such a design of the heat transfer line allows an energetic optimization of the method for producing lignite coke.

In the following, the invention will be explained in more detail with reference to exemplary embodiments illustrated in the figures. Show it:

1 a schematic flowchart of the method and

2 a schematic view of a device according to the invention.

1 shows a schematic flow chart of a method according to the invention for the production of lignite coke 1 , According to the method of the invention, crude lignite becomes 2 dried in a first process step 3 , preferably to a water content of 10 to 20 wt .-%. The dry lignite 4 is coked in a next step 5 , When coking 5 the dry lignite is heated to a temperature of 900 ° C to 1400 ° C with exclusion of air, wherein the volatile constituents in the dry lignite are pyrolyzed by the heating, released and sucked off. The brown coal coke resulting from coking 1 contains essentially carbon and has an energy density which corresponds approximately to the energy density of hard coal, the volume of lignite coke 1 corresponds to about one quarter of the volume of the raw lignite coal.

The lignite coke 1 starts at the prevailing temperatures right after the coking 5 to burn on contact with air / oxygen. To prevent this, the lignite coke is 1 a coke quenching and cooling 6 subjected.

The lignite coke produced by the process according to the invention 1 has a high energy density, approximately in the range of hard coal, a low water content of about 3 to 4 wt .-%, a low volume, compared to raw lignite, and is easy to transport, especially by water.

When coking 5 the dry brown coal 4 creates a high-energy gas 7 , This high-energy gas 7 will be saved 8th and at peak load times to a gas power plant 9 passed, which generates electricity.

The in the gas power plant 9 The resulting waste heat can be dried by the lignite 2 be fed in what 1 schematically by the dashed line 10 is shown. By using the waste heat of the gas power plant 9 can the energy consumption of drying 3 the raw lignite 2 be reduced.

The coking 5 the dry brown coal 4 The resulting waste heat can be used for drying 3 the raw lignite 2 and / or the gas power plant 9 be fed in what 1 through the dashed line 11 is clarified. Likewise, the case of coke quenching 6 resulting waste heat of drying 3 the raw lignite 2 and / or the gas power plant 9 be fed in what 1 through the dashed line 12 is clarified. By using the waste heat of coking 5 the dry brown coal 4 and / or coke quenching 6 during drying 3 the raw lignite 2 and / or in the gas power plant 9 the energy consumption of the whole process is reduced.

In 2 is a schematic view of a system according to the invention for the production of lignite coke 1 represented according to the inventive method. The system according to the invention 1 includes a fluidized bed drying plant with internal waste heat recovery, WTA plant 13 , In the WTA facility 13 becomes the raw lignite 2 dried, preferably to a water content of 10 to 20 wt .-%. The WTA facility 13 works on the principle of stationary, low-expansion fluidized bed. The energy required for drying is coupled via steam-heated heat exchangers, which are installed in the fluidized bed dryer. The drying takes place in quasi 100% pure steam, which is slightly overheated. Depending on the temperature of the steam, equilibrium is established at constant pressure between the temperature of the steam and the residual moisture of the dry lignite 4 one.

The dry lignite 4 will be in a subsequent coking plant 14 heated to temperatures of 900 ° C to 1,400 ° C under air sealing, reducing the volatiles in the dry lignite 4 pyrolyzed, released and aspirated.

The resulting brown coal coke 1 would start to burn shortly after coking on contact with air / oxygen, resulting in the subsequent coke dry cooling system 15 is prevented. In the Kokstrockenkühlanlage 15 becomes the lignite coke 1 cleared and cooled. The Kokstrockenkühlanlage 15 uses nitrogen as an inert gas and allows energy recovery, has no water consumption, and is characterized in particular by the higher coke quality due to the lower water content.

That in the coking plant 14 resulting high-energy gas 7 becomes a gas aftertreatment 16 subjected, for example, by fractional condensation, wherein the high-energy gas is decomposed into the so-called coal tar, sulfuric acid, ammonia, naphthalene, benzene and Kokereigas. The thus purified high-energy gas 7 becomes a compressor 17 fed and then in a gas storage 18 saved.

At high load times in a power grid, the high-energy gas 7 from the gas storage 18 to a gas turbine or a gas engine 19 be directed, the gas turbine or the gas engine 19 by burning the high-energy gas 7 Electricity generated to meet the demand within the power grid during peak load time.

Those in the gas turbine or in the gas engine 19 Waste heat generated by means of a heat recovery steam generator 20 and suitable heat pipes, such as piping 21 , in the WTA facility 13 be used. Likewise, in the coking plant 14 and the Kokstrockenkühlanlage 15 Waste heat generated by the WTA plant 13 and / or the heat recovery steam generator 20 the gas turbine / gas engine 19 be supplied. Also, in the gas aftertreatment 16 Waste heat generated by the WTA plant 13 and / or the heat recovery steam generator 20 be supplied.

LIST OF REFERENCE NUMBERS

1

lignite

2

raw lignite

3

desiccation

4

Dry lignite

5

Coke

6

Kokslöschung

7

high-energy gas

8th

storage

9

Gas power plant

10

waste heat recovery

11

waste heat recovery

12

waste heat recovery

13

WTA plant

14

coking

15

Kokstrockenkühlanlage

16

gas treatment

17

compressor

18

gas storage

19

Gas turbine / gas engine

20

heat recovery steam generator

21

pipeline

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2010/057509 [0003]

Claims (10)

Process for producing lignite coke ( 1 ), comprising the steps of drying ( 3 ) of raw lignite ( 2 ) Coking ( 5 ) of the dried lignite ( 4 ), and Save ( 8th ) of the coking ( 5 ) resulting high-energy gas ( 7 ) in a gas storage ( 18 ). Process according to claim 1, wherein the raw lignite coal ( 2 ) dried to 10 to 20 wt .-% water content ( 3 ) becomes. Method according to claim 1 or 2, wherein the stored high-energy gas ( 7 ) a gas power plant ( 9 ), preferably during an increased load of a power network to be supplied. A method according to claim 3, wherein in the gas power plant ( 9 ) resulting lignite drying ( 3 ) is supplied for further use. Method according to one of claims 1 to 4, wherein the coked brown coal ( 1 ) of a coke quenching ( 6 ), in particular a Kokstrockenkühlung. A method according to claim 5, wherein the coke quenching ( 6 ) resulting lignite drying ( 3 ) or the gas power plant ( 9 ) is supplied for further use. Method according to one of claims 1 to 6, wherein in the coking ( 5 ) resulting lignite drying ( 3 ) or the gas power plant ( 9 ) is supplied for further use. System for producing lignite coke ( 1 ) according to the method of any one of claims 1 to 7, comprising: a drying device ( 13 ) of raw lignite ( 2 ), preferably to a water content of 10 to 20% by weight, a device for coking ( 14 ) of the dried lignite ( 4 ), and a memory ( 18 ) for the coking ( 5 ) high-energy gas ( 7 ). A system according to claim 8, further comprising a cooling device ( 15 ) of lignite coke ( 1 ) and / or a gas power plant ( 9 ), in particular a gas turbine or a gas engine ( 19 ). System according to claim 8 or 9, further comprising heat transfer lines ( 21 ), which are designed such that in the gas power plant ( 9 ) generated heat of the device for drying ( 13 ) of the raw lignite ( 2 ) and / or in the cooling device ( 15 ) of lignite coke ( 1 ) and / or in the device for coking ( 14 ) of the dry brown coal ( 4 ) resulting heat the gas power plant ( 9 ) and / or the device for drying ( 13 ) of the raw lignite ( 2 ) is supplied.

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