WO2019052877A1

WO2019052877A1 - System and method for storing hydrogen extracted from coal

Info

Publication number: WO2019052877A1
Application number: PCT/EP2018/073902
Authority: WO
Inventors: Christian Blank
Original assignee: Christian Blank
Priority date: 2017-09-13
Filing date: 2018-09-05
Publication date: 2019-03-21
Also published as: EP3681982A1; DE102017008577A1

Abstract

The invention relates to a system (10) for storing hydrogen extracted from coal, comprising a coal gasification reactor (22) for the gasification of coal, a steam power plant (24) for power generation, which is thermally coupled to the coal gasification reactor (22), a water-gas shift reaction facility (26) which is connected to the coal gasification reactor (22) in order to obtain the reaction gases of the coal gasification reactor (22), and a gas accumulator (28), the gas accumulator (28) being connected to the water-gas shift reaction facility (26) in order to store at least one of the product gases of the water gas-shift reaction facility (26). The invention also relates to a method for storing hyrogen extracted from coal.

Description

System and method for storage of coal

hydrogen

The invention relates to a system for storing carbon derived from hydrogen. Furthermore, the invention relates to a method for storing coal-derived hydrogen.

In view of a future increased demand for hydrogen, especially in the area of mobility, and the goal of an energy transition from renewable raw materials with the progressive expansion of renewable electricity production, the storage of hydrogen for further use represents a major challenge in the coming years.

From US 201 1/0243802 A1 a method for storing hydrogen obtained from organic material is known, is gasified in the organic material, the waste heat is used to dry the organic material. Furthermore, a plasma gasification reactor is connected, which requires a great deal of energy, so that the energy obtained is used largely for the operation of the plasma gasification reactor and for the subsequent active cooling of the synthesis gas, which is several thousand degrees Celsius hot due to the plasma. Furthermore, pretreated, namely dried biomass or organic material, can be processed in plasma gasification reactors, which is difficult especially with organic material, since it first has to be dried with a high expenditure of energy.

In addition, plasma gasification reactors are very maintenance-prone, since the electrodes must be changed regularly.

The invention has for its object to store both regenerative and conventionally produced hydrogen in an efficient manner. According to the invention, the object is achieved by a system for storing coal-derived hydrogen, comprising a coal gasification reactor for gasification of coal, a steam power plant for power production, which is thermally coupled to the coal gasification reactor, a water gas shift reaction plant, which is connected to the coal gasification reactor to obtain the reaction gases of the coal gasification reactor, and a gas storage, wherein the gas storage is connected to the water gas shift reaction plant to store at least one of the product gases of the water gas shift reaction plant. Furthermore, the object is achieved according to the invention by a method for storing coal-derived hydrogen, comprising a system according to one of the preceding claims, comprising the following steps:

Gasifying the coal in the coal gasification reactor with water and (air-oxygen, - deriving the heat of reaction resulting from the gasification in order to heat a boiler of the steam power plant, whereby the reaction gases formed during the gasification are cooled,

Producing electricity in the steam power plant,

Passing the reaction gases formed during the gasification to the water gas shift reaction plant,

Carrying out a water gas shift reaction in the water gas shift reaction system by additionally supplying water to the water gas shift reaction system in addition to the reaction gases formed in the gasification, - forwarding the product gases formed in the water gas shift reaction, and

Storing at least one of the product gases in the gas storage.

The system and method according to the invention have the advantage over conventional steam power plants that the storage of hydrogen instead of the complete power generation in a future Hydrogen economy cost possible as a by-product of a steam power plant is possible. The main component of the system is a coal gasification reactor, a thermally coupled steam power plant, a water gas shift reaction plant and a gas storage, which interact accordingly.

In the coal gasification reactor, carbon monoxide and hydrogen, which are typically produced by rapid oxidation in the coal gasification reactor, are produced as reaction gases. The reaction gases of the gasification have a temperature of for example 1500 to 1800 ° C, which is much too high for a subsequent hydrogen shift reaction.

According to the reaction gases heat the feed water of the boiler of the steam power plant for the production of electric current, for example, steam is produced at a temperature of about 530 ° C, whereby the reaction gases are cooled, in particular to below 700 ° C, preferably to 200 ° C to 500 ° C.

As a result, it is even possible for the reaction gases in the water gas shift reaction system to be processed in order to spontaneously generate further hydrogen as product gases. The water gas shift reaction proceeds in particular with the addition of water in vapor form, ie by adding steam.

In other words, the thermally coupled steam power plant ensures that the reaction gases of the coal gasification reactor are sufficiently cooled so that the water gas shift reaction can proceed at all. However, there is no active cooling is made, is consumed in the energy for cooling, but the heat of the reaction gases is used to operate the steam power plant, at least partially, so to generate steam for the steam power plant.

By contrast, the coal gasification reactor is operated at very high temperatures, so that it provides almost exclusively hydrogen and carbon monoxide as reaction gases, for example 33% hydrogen and 60% carbon monoxide. In the prior art, a coal gasification reactor is usually operated at lower temperatures, for example at temperatures of maximum 1000 ° C to 1200 ° C, in order to then cool the reaction gases less active active, so that the overall efficiency is as high as possible.

However, at such temperatures, which are provided in the prior art, dioxides, which should be avoided according to the invention. Due to the high temperatures, according to the invention there is a rapid oxidation of the coal to be guided.

The resulting carbon monoxide as part of the cooled reaction gases of the coal gasification reactor is converted into hydrogen via the water gas shift reaction system. In this respect, more hydrogen is available, which can be used. The additional hydrogen represents a part of the product gases of the water gas shift reaction system.

The water gas shift reaction system may also include a high temperature and low temperature equipment part, whereby the carbon monoxide content in the production gases of the water gas shift reaction plant can be reduced.

Ultimately, the product gases of the water gas shift reaction system, ie mainly hydrogen, stored in a gas storage. The hydrogen can be used for hydrogen cars or other hydrogen applications. In principle, the hydrogen formed in the coal gasification reactor can be separated, for example via a downstream filter, so that only the cooled carbon monoxide is fed to the water gas shift reaction system as (cooled) reaction gas.

Subsequently, the hydrogen produced in the coal gasification reactor, ie the hydrogen as reaction gas, can be combined with the hydrogen from the water gas shift reaction plant, ie the hydrogen as product gas, and stored in the gas reservoir. The proportion of recovered hydrogen is thus maximum.

Alternatively, the hydrogen produced in the coal gasification reactor is also fed to the water gas shift reaction plant and, via this, to the gas reservoir. The system always produces an excess of electricity that can be fed into the grid, partly because of the connected steam power plant. In contrast, systems with plasma gasification reactors require at least a majority of the power to operate on their own. However, any surplus is needed at the latest for hydrogen production, ie it is directly consumed again.

One aspect provides a separation system for separating hydrogen, which is arranged between the water gas shift reaction system and the gas storage, so that the gas storage stores only hydrogen. In this respect, the hydrogen is separated from the remaining product gases of the water gas shift reaction system by means of a further subsystem, namely the separation system, and then stored in the gas storage, so that pure hydrogen is available. The separation plant may be a filter. The other product gases can also be separated or filtered so that they can also be stored separately.

According to a further aspect, a carbonization plant for continuous or discontinuous hydrothermal carbonization of biomass is provided, wherein the carbonation plant is fed as starting material any biomass, which is subjected to a continuous or batch process in a continuous process of hydrothermal carbonation, in particular wherein the the carbonization liberated heat of reaction is used to dry the resulting coal-water slurry. In this respect, a regenerative operation is possible in which any biomass in an upstream part of the plant is subjected to a hydrothermal carbonation in a continuous flow process or a batch batch process. Depending on the gasification reactor used, the resulting coal can be dried with the heat of reaction from the hydrothermal carbonization prior to gasification. The carbonization unit may comprise a carbonization part, a drying part adjoining the carbonization part, and a heat exchanger, the heat exchanger leading the heat of reaction liberated during the carbonization in the carbonization part to the drying part. This is a energy-efficient carbonisation plant, since the heat of reaction released during the carbonization of the biomass is used to dry the coal produced during the carbonation, so that dried coal can be fed to the coal gasification reactor. In principle, any biomass, even very humid, such as organic waste, can be used in the carbonization plant without pretreatment in order to produce the coal-water slurry by hydrothermal carbonation, which is also referred to as lignite-water slurry or HTC coal. The power consumption here is minimal. In general, the steam power plant can serve as a heat sink, so that the water gas shift reaction system receives the reaction gases of the coal gasification reactor cooled. The reaction gases are therefore cooled due to the heat dissipated to the temperature required for the water gas shift reaction. Since the cooling of the reaction gases or the dissipation of the heat generated is used to heat the existing water in the boiler of the steam power plant and to generate steam, there is a correspondingly energy-efficient system.

The coal gasification reactor may be a Koppers-Totzek reactor. Such a coal gasification reactor works with fine coal, which can work with different types of coal.

The coal can be shredded in advance to the required grain size. Depending on the gasification reactor used, for example in a Koppers-Totzek reactor, the coal in an upstream part of the plant must be crushed to a certain granularity. The HTC coal, ie the carbon-water slurry obtained from the carbonization plant, does not have to be comminuted before the subsequent gasification, since it is 8 to 20 nm in size, since a Kopper-Totzek reactor, for example, a grain size of less than 0.1 mm needed.

The reaction gases of the gasification may mainly comprise carbon monoxide, in particular wherein the reaction gases include, inter alia, hydrogen. Another aspect provides that the product gases produced in the water gas shift reaction are processed by means of an upstream separation unit for the separation of hydrogen, so that only hydrogen is supplied to the gas storage. For example, the coal is provided from fossil coal and / or from any biomass. The coal can therefore be made entirely from fossil coal, entirely from any biomass or even from a mixture. If a proportion of biomass is provided, it must first be carbonized accordingly. The comminuted coal, the lignite-water slurry produced from biomass, and / or the dried lignite-water slurry may generally be gasified in the coal gasification reactor with water and (air) oxygen.

Since the system comprises a steam power plant, the system is a stationary, immobile or stationary system.

In general, the gasification of the coal in the coal gasification reactor by adding water and oxygen at high speed, so that the coal is only briefly exposed to a flame in the coal gasification reactor, so not completely burned. In contrast to the system according to the invention, in which almost exclusively elemental hydrogen and carbon monoxide is produced in the gasification process, namely over 90%, for example 93%, atoms and, depending on the type of cooling, different, also poisonous, molecules, including heavy metals, are formed during plasma gasification. which need to be filtered separately, which makes the system accordingly more expensive.

In the plasma process, the biomass waste is first dried as a biomass with a high energy input and then broken down into atomic elements. These can form toxic compounds on cooling, which could then escape during the combustion of the product gas. In order to avoid such compounds, the hot gases are actively cooled very quickly in order to prevent the external conditions necessary for the formation of compounds such as furans and dioxins. Further advantages and features of the invention will become apparent from the following description and the drawings, to which reference is made. In the drawings show:

Figurl a schematic structure of the inventive system for the storage of coal-derived hydrogen, with which the inventive method can be performed.

FIG. 1 shows a system 10 that can generate hydrogen from a biomass.

For this purpose, the system 10 comprises a biomass feed 12, via which the carbonization plant 14 can be fed with the biomass to be carbonized. The carbonator 14, which is part of the system 10, serves for continuous or discontinuous hydrothermal carbonization of the biomass to produce coal.

For this purpose, the carbonization unit 14 comprises a carbonization part 16, a drying part 18 adjoining the carbonization part 16, and a heat exchanger 20 which couples the carbonization part 16 to the drying part 18.

Further, the system 10 includes a coal gasification reactor 22 coupled to the carbonator 14 to obtain the output of the carbonator 14.

The coal gasification reactor 22 gasifies the coal, thus among other things the starting products of the carbonization plant 14, wherein the coal is gasified with the addition of water and (air) oxygen inter alia to carbon monoxide and hydrogen. This creates thermal energy that can be used.

According to the invention, the thermal energy is utilized by a steam power plant 24 that is thermally coupled to the coal gasification reactor 22 so that feed water of a boiler of the steam power plant 24 is heated by the heat generated during gasification. Furthermore, the system 10 includes a water gas shift reaction unit 26 coupled to the coal gasification reactor 22 for the reaction gases the coal gasification reactor 22, which are cooled due to the thermal coupling with the steam power plant 24.

In the water gas shift reaction unit 26, the carbon monoxide obtained as the reaction gas from the coal gasification reactor 22 is converted to further hydrogen by adding water.

The gas-shift reaction system 26 is adjoined by a gas reservoir 28, in which at least one of the product gases of the water-gas shift reaction system 26 can be stored.

In particular, the one production gas may be hydrogen, which is why a separation plant 30 is provided for separating hydrogen, which is arranged between the water gas shift reaction plant 26 and the gas reservoir 28, so that the gas reservoir 28 stores only hydrogen.

In the embodiment according to FIG. 1, it is thus possible to obtain hydrogen from biomass and at the same time to produce electricity, the efficiency being correspondingly high.

As already explained, the carbonization system 14 is fed via the biomass feed 12 biomass, which is then carbonized in the Karbonisierungsteil 16, that is converted to coal. The biomass can be heated initially, to then be converted by means of an exothermic reaction in a coal-water slurry, in particular a lignite-water slurry.

The released heat is passed through the integrated heat exchanger 20 of the carbonization system 14 to the subsequent drying part 18, which serves to dry the coal-water slurry. In other words, the heat exchanger 20 serves as a heat coupling, so that the drying part 18 uses the heat released during the exothermic reaction of the carbonization to dry the coal-water slurry.

The dried coal-water slurry is then fed to the coal gasification reactor 22, where the coal is gasified together with water and (air) oxygen with release of energy inter alia to carbon monoxide and hydrogen. The Karbonisierungsanlage 14 is only optional, if hydrogen is to be obtained from biomass.

It is also fossil coal the coal gasification reactor 22 fed directly, which is then gasified with release of energy among other things to carbon monoxide and hydrogen.

Further, a mixture of biomass and fossil coal may be supplied to the coal gasification reactor 22.

In either case, the coal gasification reactor 22 is operated at temperatures as high as almost exclusively carbon monoxide and hydrogen. This is done by rapid oxidation at high temperatures, mainly resulting in carbon monoxide and hydrogen as reaction gases.

The coal gasification reactor 22 may be a Koppers-Totzek reactor which requires crushed coal for gasification, so that a comminution plant may be connected upstream, which comminutes the coal, in particular the fossil coal.

On the other hand, the carbon-water slurry produced in the carbonation plant 14 does not have to be further comminuted, since the coal has already been sufficiently comminuted.

Accordingly, in the coal gasification reactor 22, the coal can be gasified at temperatures of 1600 to 1800 ° C in a flame of the coal gasification reactor 22, producing hydrogen and carbon monoxide (generator gas).

The carbon monoxide (generator gas) is generated in accordance with incomplete combustion of coal with air, which is just not possible for example in a plasma combustion, especially since a working gas must still be used.

The heat energy of the reaction gases is fed to and / or removed from the steam power plant 24, which is thermally coupled to the coal gasification reactor 22, in particular the boiler of the steam power plant 24. The feed water therein is due to the heat of the reaction gases heated so that the feed water evaporates. The steam may then drive one or more turbines of the steam power plant 24 for power production.

The heating of the feed water with the reaction gases of the coal gasification reactor 22 cools the reaction gases accordingly, in particular the carbon monoxide as a reaction gas. For example, the reaction gases are cooled to temperatures below 700 ° C.

This ensures that the reaction gases, in particular the carbon monoxide, can be processed directly in the water gas shift reaction system 26, ie without intermediate active cooling, as is usual.

In other words, the steam power plant 24, which is thermally coupled to the coal gasification reactor 22, serves as a heat sink, so that the water gas shift reaction plant 26 receives the reaction gases of the coal gasification reactor 22 cooled. In the water-gas shift reaction system 26, the carbon monoxide, which is formed in addition to hydrogen in the gasification in the coal gasification reactor 22 as a reaction gas, converted to further hydrogen, so that more hydrogen can be provided.

The additional hydrogen is then separated via the separation unit 30 for separation, so that the gas reservoir 28 receives only hydrogen.

In particular, the hydrogen which has formed as the reaction gas in the coal gasification reactor 22 may also have previously been separated off, in particular before the reaction gases are passed on to the water gas shift reaction plant 26, the branched off hydrogen being combined with the additional hydrogen.

Subsequently, the branched hydrogen are stored in the gas storage 28 together with the additional hydrogen.

The gas storage 28 may be preceded by a compression system to compress the gas to be stored. Basically, the system 10 of the coal, which is provided in particular from biomass, can produce almost exclusively hydrogen and carbon monoxide, namely more than 90%. The resulting ash accumulates liquid in the reactor bottom and is granulated in a water bath. Simplified shown in the coal gasification reactor 22 following reaction C6H2O + 5 H2O = 6 CO + 6 h .The carbon monoxide thus obtained is then subjected to a water gas shift reaction in the water gas shift reaction system 26, which can be represented as follows 6 CO + 6 H2O = 6 CO2 + 6 H2. From this it becomes clear that from the carbon monoxide further hydrogen can be won.

This results in two molecules of hydrogen (H2) per carbon atom of the HTC coal.

It is precisely the combination of both processes (gasification and water gas shift reaction) that makes it possible to almost double the hydrogen produced compared to pure gasification or plasma gasification.

In addition, the entire process is very energy efficient, so that additional electricity can be produced, whereas in systems with plasma gasification no surplus energy is obtained, if the hydrogen is to be stored.

Claims

claims

1 . A system (10) for storing coal-derived hydrogen, comprising: a coal gasification reactor (22) for gasifying the coal, a steam power plant (24) for power production thermally coupled to the coal gasification reactor (22), a water gas shift reaction plant ( 26) connected to the coal gasification reactor (22) to obtain the reaction gases of the coal gasification reactor (22), and a gas storage (28), the gas storage (28) being connected to the water gas shift reaction plant (26), to store at least one of the product gases of the water gas shift reaction system (26).

2. System (10) according to claim 1, characterized in that a separation system (30) is provided for the separation of hydrogen, which is arranged between the water gas shift reaction system (26) and the gas reservoir (28), so that the gas storage ( 28) stores only hydrogen.

A system (10) according to claim 1 or 2, characterized in that the system (10) comprises a carbonization unit (14) for continuous or discontinuous hydrothermal carbonization of biomass to produce coal.

4. System (10) according to claim 3, characterized in that the Karbonisierungsanlage (14) comprises a Karbonisierungsteil (16), one of the Karbonisierungsteil (16) subsequent drying part (18) and a heat exchanger (20), wherein the heat exchanger (20 ) which conducts the heat of reaction released during carbonization in the carbonization part (16) to the drying part (18).

5. System (10) according to any one of the preceding claims, characterized in that the steam power plant (24) serves as a heat sink, so that the water gas shift reaction system (26) receives the reaction gases of the coal gasification reactor (22) cooled.

6. System (10) according to any one of the preceding claims, characterized in that the coal gasification reactor (22) is a Koppers Totzek reactor.

7. A method for storing coal-derived hydrogen, comprising a system (10) according to any one of the preceding claims, comprising the following

steps:

Gasification of the coal in the coal gasification reactor (22) with water and (air-oxygen,

Deriving the heat of reaction resulting from the gasification to heat a boiler of the steam power plant (24), wherein the at

Gasifying reaction gases are cooled,

Producing electricity in the steam power plant (24),

Passing the reaction gases formed in the gasification to the water gas shift reaction system (26), - carrying out a water gas shift reaction in the water gas shift

Reaction system (26) by additionally supplying water to the water gas shift reaction system (26) in addition to the reaction gases formed during the gasification,

Forwarding the resulting in the water gas shift reaction product gases, and

Storing at least one of the product gases in the gas storage (28).

8. The method according to claim 7, characterized in that the coal is comminuted in advance to the required grain size.

9. The method according to claim 7 or 8, characterized in that the reaction gases of the gasification mainly comprise carbon monoxide, in particular wherein the reaction gases include, inter alia, hydrogen.

10. The method according to any one of claims 7 to 9, characterized in that the product gases formed in the water gas shift reaction means an upstream separation plant (30) are processed for the separation of hydrogen, so that only hydrogen is supplied to the gas storage (28).

1 1. Method according to one of claims 7 to 10, characterized in that the coal is provided from fossil coal.

12. The method according to any one of claims 7 to 1 1, characterized in that the coal is provided from any biomass.

13. The method according to claim 12, characterized in that the system (10) comprises a Karbonisierungsanlage (14) for continuous or discontinuous hydrothermal carbonization of biomass, wherein the Karbonisierungsanlage (14) is fed as starting material any biomass, in a continuous process is subjected to a discontinuous hydrothermal carbonation in a continuous or in a batch process, in particular wherein the heat of reaction liberated in the carbonization is used for drying the resulting coal-water slurry.

14. The method according to claim 12 or 13, characterized in that the resulting coal-water slurry or the dried coal-water slurry is fed to the coal gasification reactor (22).