GB2108524A

GB2108524A - Method and apparatus for hydrogenating coal

Info

Publication number: GB2108524A
Application number: GB08230751A
Authority: GB
Inventors: Wolfgang Bulang
Original assignee: MAN Maschinenfabrik Augsburg Nuernberg AG
Current assignee: MAN AG
Priority date: 1981-10-29
Filing date: 1982-10-28
Publication date: 1983-05-18
Also published as: DD208602A5; FR2515637B1; JPS5930891A; DE3142888A1; FR2515637A1

Abstract

A gasification reactor (12) and the associated gas generation circuit are combined with a power plant (11) so that the combustion chamber (28) of the power plant is energized with the residual coke from the reactor (12) and so that the high-temperature heat from the combustion chamber (28) is utilized for the production of hydrogen for gasification. <IMAGE>

Description

SPECIFICATION Method and apparatus for hydrogenating coal This invention relates to a method and apparatus for the hydrogenation of coal, peat or biomass using a gasification reactor.

The purpose of a gasification reactor is to generate methane (CH4) from raw coal. For this purpose the raw coal is partially gasified using hydrogen at 100 bar. The hydrogen required is continuously generated in a gasgenerating circuit using a portion of the CH4 produced and absorbing high-temperature heat of reaction. To this end, use is normally made of special-purpose combustion chambers fed with the normally available primary energy, especially coal.

An object of the present invention is to provide an energy-saving method for hydrogenation.

The invention provides a method of hydrogenating coal, peat or biomass using a gasification reactor, wherein the heat required for gasification is generated by burning residual coke from the gasification reactor.

In this manner, the separate primary energy is replaced with the residual coke from the reactor, which normally constitutes a waste product, and this not only considerably economizes energy but also substantially alleviates environmental effects. Additionally the removal of residual coke waste is facilitated.

In the degasification process, the formation of methane is accompanied by desulpherization of the coal and bonding of the nitrogen, so that the flue gas produced in the combustion of the residual coke is free from sulphur and nitrogen oxides.

Preferably, use is made of the combustion chamber of a power station for burning the residual coke. In this manner the power station is simultaneously made enviromentally tolerable, and its flue gas is low in injurious matter.

In order to exploit the heat produced at a maximally high temperature, a cracking reactor with a catalyst is preferably arranged in the hot zone of the combustion chamber of a power station.

At the catalyst, cracking of part of the methane produced as required for the gasification process is achieved. The high-temperature thermal energy required for this purpose is picked up in the hot zone of the flue gas.

This affords the advantage that the power station utilizes the valuable high-temperature heat, which is normally wasted, for the gas generator circuit. Combination of hydrogenation with a power station thus contributes substantially to the energy economy effort and notably improves the efficiency not only of a gasification reactor, but simultaneously also of a power station.

Especially effective heat transfer from the power station combustion chamber to the gas generator circuit is achieved using a tubular cracking reactor having a suitable catalyst.

Preferably, the steam required for the gas generator circuit is taken from the steam plant of the power station.

This eliminates the need for separate steam generators to reduce the overall size and economize material as well as labour. This measure additionally also achieves a compact gasifier-power station unit.

An embodiment of the invention will now be described with reference to the accompanying drawing which shows schematically a gasification power-station plant.

In the drawing, a combined gasificationpower station plant comprises a gasification system 10 shown in broken line and power station 11 enclosed by dash-dotted line.

CH4 is produced in a reactor 1 2 in which dehydrated raw coal 1 3 is partially gasified using hydrogen at a pressure of about 100 bar. Carbon, sulphur, nitrogen and oxygen contained in the coal, combine with the hydrogen to form hydrogenous compounds, which are fed through duct 1 4 into a gascleaning device 1 5. In the gas-cleaning device 1 5 the compounds are separated and fed away. The residual gases remaining after removal of NH3 and H3S are fed into a lowtemperature separation unit 16, in which residual hydrogen and possibly CO2 are separated. The CH4 separated in this manner is then fed through an expansion turbine 1 7 to a reservoir or consumer (not shown).

A portion of the synthesized CH4 expanded to about 50 bar is diverted through a duct 1 8 for the production of the hydrogen needed to sustain the gasification process. The diverted CH4 is decomposed using steam and is then heated in a high-temperature heat exchanger 20. The heated steam-methane mixture is carried through a tubular cracking reactor 21 in which the mixture is broken down into carbon monoxide and hydrogen using a nickel catalyst. This process takes place at elevated temperatures of around 900,C. The hightemperature heat of the reaction mixture CO and H2 is yeilded in the heat exchanger 20 to heat the methane-steam mixture. In a succeeding reformer 22 the CO is converted to CO2 and H2 by the addition of steam and is fed into the separation unit 16.Having been freed from residual foreign gas the hydrogen is finally compressed in a compressor 25 to aout 100 bar and ducted to the reactor 1 2.

In order to generate the requisite amount of thermal energy for the production of hydro gen, the combustion chamber 28 of the power station 11 is used utilizing the residual coke from the reactor 1 2. For this purpose, the residual coke is conveyed directly via a duct 30 from the coke extractor 32 to the combustion chamber 28, being finely ground in a grinder 31 on the way. Putting the residual coke to further use economizes primary energy and affords another important advantage in that the flue gas produced in this manner contains no injurious sulphur or nitrogen.

The power station 11 essentially consists of the combustion chamber 28, evaporator 30, high-pressure, intermediate-pressure and lowpressure turbines 35, 36 and 37, respectively, and a generator 38.

For generating steam, the heat of the flue gas, originally over 1000"C, must be reduced to 800"-900"C. The high-temperature heat yielded in the process, which is wasted in normal power plants, is utilized to best effect for the gas generator circuit described. For this purpose, a tubular cracking reactor 21 is arranged in the hot zone 40 of the combustion chamber 28 below the evaporator 30, so that the tubular cracking reactor 21 serves the concomitant function of cooling the flue gas for the evaporators 30. The evaporator 30 is arranged in a low temperature zone 52 of the combustion chamber.

The steam needed for the gas-generator circuit is advantageously taken from the steam plant of the power plant 11, if necessary with an expansion turbine 42 en route.

To assist economical continuous service of the plant 10, 11, a further power station 45 can be provided to utilize excess CH4. When the Ch4 demand is low, the excess methane is expanded in a turbine 46 and burned in a combustion chamber 47. The flue gases are used to drive a compressor 48 and a gas turbine 49 to operate a generator 50.

Claims

CLAIMS:

1. A method of hydrogenating coal, peat or biomass using a gasification reactor, wherein the heat required for gasification is generated by burning residual coke from the gasification reactor.

2. A method as claimed in Claim 1, wherein the residual coke is burned in the combustion chamber of a power station.

3. A method as claimed in Claim 2, wherein the combustion chamber is divided into a high-temperature zone for generating the heat and into a low temperature zone.

4. A method as claimed in Claim 3, wherein the required heat is picked up in a cracking reactor arranged in the hot zone of the combustion chamber of the power station.

5. A method as claimed in Claim 4, wherein the cracking reactor is a tubular cleavage reactor is provided with a catalyst.

6. A method as claimed in any one of the preceding Claims, wherein the steam required to sustain the gasification reaction is taken from a power station steam plant.

7. A method of hydrogenating coal, peat or biomass substantially as herein described with reference to the enclosed drawing.

8. Apparatus for carrying out the method as claimed in any one of the preceding claims, comprising a combustion chamber communicating with the residual coke exit of a gasification reactor and containing a cracking reactor from which high temperature reaction heat is extracted.

9. Apparatus as claimed in Claim 8, wherein the combustion chamber is the combustion chamber of a power station.

10. Apparatus as claimed in Claim 9, wherein the gasification reactor, the associated gas generating circuit and the power station constitute a structural unit.

11. Apparatus as claimed in Claim 8 or 9, wherein a steam circuit for gasification is integrated into the steam circuit of the power station.

1 2. Apparatus substantially as herein described with reference to the accompanying drawing.