WO1999061530A1

WO1999061530A1 - Concept for the production of pure carbon black through the combustion of natural gas without co2 and the production of electric power

Info

Publication number: WO1999061530A1
Application number: PCT/NO1999/000164
Authority: WO
Inventors: Olav Ellingsen
Original assignee: Industrikontakt, Ing. O. Ellingsen & Co.
Priority date: 1998-05-26
Filing date: 1999-05-25
Publication date: 1999-12-02
Also published as: AU4065099A; NO982374L; NO982374D0; NO308289B1

Abstract

A process for the combustion of hydrocarbons, such as natural gas, oil or the like, for producing energy, the combustion taking place in insufficient air so as to reduce the CO2 emissions and at the same time produce pure carbon in the form of filter cakes containing oil for later use, e.g., in existing coal-fired power stations, thereby reducing the sulphur emissions therefrom, and/or the use of the carbon in the metallurgical industry.

Description

CONCEPT FOR THE PRODUCTION OF PURE CARBON BLACK THROUGH THE COMBUSTION OF NATURAL GAS WITHOUT CO,AND THE PRODUCTION OF ELECTRIC

POWER

The present invention relates to a method for the production of pure carbon black mixed with oil through the combustion of hydrocarbons, such as natural gas or oil. without the production of CO₂, in conjunction with the production of electric power or other use of the thermal energy.

At present, there is a great deal of debate about the C0₂ emissions in Norway and the rest of the world, and in particular the C0₂ emissions that are expected from the planned gas-fired power stations in Norway with regard to the possible greenhouse effect these emissions may have on our planet.

For this reason, extensive research is currently underway to find ways of reducing the CO₂ emissions from the combustion of fossil fuels. One of the ideas that has been launched is to inject the CO₂ produced into the seabed and/or into oil reservoirs. This does nothing to eliminate the actual production of CO₂ during combustion, but presents a method for the disposal of the CO₂ thus produced.

Furthermore, the Norwegian company Norsk Hydro has recently launched a concept for virtually C0₂-free combustion by separating C0₂ from the natural gas.

One of the documents known from the patent literature is US Patent 5,316,750 wherein the object is to crack methane in a three-stage process according to the following formulae:

1. CH₄ + C0₂ → CO + 2H₂

2. CH₄ + CO₂ → 2C + 2H₂O

3. CO₂ + H₂ → CO + H₂O

The process operates at a pressure of between 10 and 40 bar.

Furthermore a process is known from the published patent application NO 175984 wherein, by means of a pyrolysis process in a plasma chamber, it is sought to crack methane into hydrogen and carbon black in order thereby to obtain a clean or partially clean combustion of hydrogen so that the CO₂ content of the waste gas is reduced. None of these inventions have any relevance to the present invention since the present invention differs clearly as regards use and the carrying out of the process, for instance in that the removal of the carbon takes place during the combustion.

It is known that all combustion of fossil fuels produces CO₂ as a result of the oxidation of carbon (C) and the oxygen (O) in the air. If carbon is burned, either alone or as a constituent of the fossil fuel, this is a law of nature and thus cannot be avoided.

The present invention will teach a method whereby the combustion can take place without the oxidation (burning) of the carbon in a process wherein the released thermal quantity can be used, wter alia, for the production of electric power.

All fossil fuels such as oil and gas have one or usually more carbon atoms in their molecules. In the case of methane, the chemical formula of which is CH₄, there is one carbon atom for every four hydrogen atoms. Taking methane as an example, it will be shown below how it is possible to burn only the hydrogen and not the carbon in one and the same operation.

It is well-known that if a so-called complete combustion of oil or gas does not take place, soot will be formed. The incomplete combustion is due to an insufficient supply of oxygen. Normally, this is a condition it is endeavoured to avoid since the soot causes substantial pollution and technical problems, and at the same time only a part of the energy in the fuel is harnessed.

However, the present invention seeks to do just this, namely to burn only the hydrogen and precipitate the carbon as pure carbon black which in turn can be sold as fuel to existing coal-fired power stations, and thus replace highly pollutant coals such as brown coal and black coal, and/or be used in the metallurgical industry as anode coal or anywhere else where there is a need for clean coal.

With reference to the enclosed flow diagram, the process is arranged in the follow ing manner:

In a combustion chamber a) gas and air are fed into the combustion chamber from two separate lines having regulating devices to ensure that the combustion in the chamber a) is incomplete, resulting in the formation of soot. To be able to harness the thermal value of the combustion and remove the soot in a way which does not interfere with the process, atomised oil having a high boiling point is injected from the top of the chamber a). This oil may be a decanted oil from the last stage of a refining process. When the oil encounters the carbon and the flame, it will absorb the carbon particles which are thus washed downwards in the chamber a). The oil and the carbon will be heated to a predetermined temperature. When this happens, the oil/carbon mixture encounters a heat exchanger consisting of tubes b) where a heat transfer to the water in the tubes will take place. The water, which is thus vaporised at a predetermined temperature, is conveyed in a conventional manner to a turbine c) which operates a conventional generator d) which produces power. After the oil/carbon mixture has passed the heat exchanger, it is pumped through a decanter centrifuge e) where the major part of the oil is separated from the carbon black. From the decanter centrifuge (or prior thereto), any remaining energy in the oil/carbon black mixture can be heat- exchanged with the heat exchanger feed water in a heat exchanger f). The feed water is pumped from the condenser g) after the turbine by means of a feed pump h). After the heat exchanger f), the oil is first pumped to a scrubber i) which receives waste gas from the chamber a). Here, the oil will cool down the waste gas which for the most part consists of water vapour and nitrogen, some carbon black and possible vaporised fractions of the oil. From the bottom of the scrubber, the oil is pumped into the chamber a) as described above.

The carbon black which exits the decanter centrifuge e) is passed down into a conventional filter chamber press j) wherein the carbon black is compressed into filter cakes. During this operation further oil will be pressed out of the carbon black/oil mixture so that ultimately it has a typical residual oil content of from 25 - 35%.

Since some oil always remains in the carbon black, there is provided a '"make-up^" tank k) containing oil which replenishes that held in the carbon.

The carbon black and oil mixture will have a potential thermal value that is equal to the sum of the thermal value of the oil and the carbon, and which can be sold as an ordinary commodity to existing coal-fired power stations and/or used as anode coal in the metallurgical industry and other industry.

It is obvious that the process can be used for all types of gases and oils which contain carbon and wherein an incomplete combustion will result in soot formation.

A preliminary estimate for a power station of 300,000 kW will give the following values:

Total power supplied P = 700,000 kW Total energy supplied E 2,520,000,000 kJ/h

Hydrogen consumption GH 15,000 kg/h

Gas consumption (methane) Gg = 84,000 kg/h

Operating temperature T 600° C

Overall efficiency η = about 44%

Carbon produced GC 63,000 kg/h

Claims

P a t e n t a i m s

1.

A method for the combustion of a fossil fuel, such as natural gas and oil. which combustion takes place as incomplete combustion, whereby carbon black is released, which is cooled/washed using a fluid, characterised in that a downwardly directed oil spray is used as the cooling/washing fluid, and that the thus formed oil/carbon mixture is reduced as regards the oil content in the mixture, and the reduced mixture is pressed to form carbon briquettes.

A method according to claim 1 , characterised in that the oil/carbon black mixture formed is cooled prior to the reduction, whereby energy is released for external use.

The method according to claim 2, characterised in that oil which is produced on the reduction of the oil/carbon black mixture is heat exchanged with a heat exchanger feed water for the said cooling of the oil/carbon black mixture formed.

4.

A method according to one of the preceding claims, characterised in that the said reduction includes a centrifugal separation of the oil/carbon black mixture.

5.

A method according to one of the preceding claims, characterised in that the said reduction of the oil/carbon black mixture includes a compression filtration.