GB2088893A - A Process for Producing Hydrocarbons - Google Patents

Abstract

Hydrogen, a carbon-containing material and crushed flux are injected into a carburized metal bath with induction coil heating elements in order to produce a required hydrocarbon compound, for example methane or acetylene. The bath is contained within a pressurized crucible-type furnace and impurities from the raw materials and by-product of the reaction are drawn off as slag or in the gaseous effluent. The carbon-containing raw material which may be any suitably prepared, dried and milled material such as solid fossil fuel or industrial waste, is far greater than in previous industrial hydrocarbon-producing processes.

Description

SPECIFICATION A Process for Producing Hydrocarbons The invention relates to a process for producing hydrocarbons The new process for producing hydrocarbons consists of injecting a technical or elemental hydrogen current and a current of another carboncontaining material into a carburized metal bath which is provided with heating means, in order to principally produce the particular hydrocarbon which is the object of the process. The components differing from the hydrocarbon producing material contained in the raw materials are eliminated as slag or in the gaseous phase.

The hydrocarbons are known chemical compounds which exist in nature, sometimes in large deposits, or are found as components of natural or artificial substances.

The industrial use of hydrocarbons in bulk quantities, gives rise to the rapid depletion of certain known natural sources of a great importance. For this reason, processes for synthesising hydrocarbons are nowadays of great industrial interest. The synthesising processes hitherto known are still very complex and the equipment used is often under extreme stress and some materials are almost at the maximum allowable stress level.

In 1862, Berthelot, using graphite electrodes, hydrogen and electrical energy to establish the voltaic arc, obtained acetylene (HC-C-H or C2H2), one of the first synthetic products of the industrial era.

Subsequently, a number of attempts were made to hydrogenate carbon and other carbonaceous substances and from them develop industrial processes to obtain solid, liquid, and gaseous hydrocarbons.

During the Second World War, Germany produced fuels in large quantities for their air force. This production was based on the studies of Professor F. Bergins and others. The cost of production was greater than the prices of the market for natural hydrocarbons, and therefore, at the end of the war, the producing plants were closed.

For strategic reasons and for reasons concerning availability of hydrocarbons, a new stage of interest in this technology was consolidated in the 1 970s.

The Fisher-Totschp process was adopted and improved by South Africa to meet an ambitious programme aimed at self-sufficiency in the production of liquid and gaseous hydrocarbons, based on South Africa's own carbonaceous resources. Hydrocarbons may be produced from carbonaceous matter, by two principal different methods, namely direct or indirect hydrogenation after previous carbon gasification.

The direct hydrogenation processes, which are about to become industrially effective, are firstly the so-called S.R.C. derived from Uhde Pfirmann and secondly a process which involves hydrogenation of coal, which is the bearer and donator of hydrogen to the system, to obtain a liquid product, the hydrogen contents of which is greater than the hydrogen contents of the coal used as raw material. In another hydrogenation process involving an electric discharge, the hydrogen is converted into the atomic or nascent state, that is, a plasma state, and is made to react with coal to produce acetylene which may subsequently be transformed into olefins by petrochemical processes.

The principles of the indirect process are gasification of the coal and later condensation under high pressure and high temperature conditions using standard types of equipment as developed by the chemical industry.

The new process which is proposed in the present application consists of injecting into an initial carburized metal bath, which is contained in a pressurized crucible-type furnace and provided with heating means, a current of carbonaceous material, a current of technical or elemental hydrogen, a current of flux and energy until the necessary and sufficient quantities of the settled components, as defined by the laws governing chemical reactions, are attained, in order to maintain the conditions in the carburized initial bath, including its temperature, in a steady state, in order to obtain as products an effluent composed principally of the particular hydrocarbon which is the subject of the process, and secondarily of other hydrocarbons, impurities contained in the raw materials and a slag comprising the remaining portion of the coal impurities and the flux employed.

The new process differs substantially from the previous processes in that total dissolution of the carbonaceous matter is accomplished in situ, that is, in the same milieau where the coal hydrogenation reactions occur, that is, in the carburized bath.

With respect to the existing processes the advantages inherent to the process of the present application will be explained in the following.

As mentioned during the brief description of the existing methods, it is possible to establish comparisons between the physico-chemical parameters employed in each process, as dynamic equilibriums of the respective reactions.

With respect to the conditions of pressure and temperature requirements of the Fisher-Totschp process, both these parameters are limited by the maximum stresses allowed for the materials composing the equipment. Fewer such compromises are required in the processes employing solvents.

The present invention provides a process for i producing hydrocarbons, characterized by the use of a crucible-type furnace which is insulated and provided with heating means, said furnace containing a carburized metal bath into the middle of which a current of carbonaceous milled matter and a current of technical or elemental hydrogen is injected.

In the proposed process, pressurization of the equipment is preferable, in order to isolate the product obtained from the atmosphere, that is in order to avoid its mixture with air. However the process may also be conducted under normal pressure. It should be added that pressurization also permits an increase in the quantitative efficiency of the equipment, but it should be emphasized that pressure is not a limitative factor, as in the previously mentioned processes.

In the proposed process the temperature attained may far exceed the temperatures attained in the majority of existing processes because the equipment used includes refractory coatings, which are traditionally adequate for this type of thermal stress.

The substantiai differences noted, with respect to pressures and temperatures, which are inherent to each individual process, will become evident from the embodiment described later.

From the embodiments, the following conclusions can be drawn.

1. The thermodynamic efficiency of the process as proposed exceeds that of existing processes.

2. The maximum allowable stresses for the materials composing the equipment in the proposed procedure are not limitative factors of the process parameters.

3. The proposed process depends on much simpler technology than the extraordinarily complicated conventional petrochemical procedures or electric plasma of existing processes. In this process technologies similar to those used in proven metallurgical procedures are employed.

4. The speed of the main reaction in the process always depends to some extent on the equipment efficiency and, in general, is bound to thermodynamic factors of pressure and temperature and to the catalyst efficiency.

One important and unique aspect of the proposed process is that no catalysts are used. It should however be emphasized that the physicochemical factor temperature is decisive in rendering the process reactions dynamic.

The carbonaceous material used as a raw material in the process may be one of a very large number of materials, for example all kinds of solid fossil fuels, vegetable fuel materials, industrial waste and urban waste materials conveniently prepared dried and of suitable particle size gradations.

Coke is of outstanding importance as a raw material, particularly coke obtained from the pyrolytic decomposition of coals, mainly bituminous coals.

In addition, the new process may enjoy all advances emerging from the coal preparation processes, prior to its use, which are presently the subject of profound studies which undoubtfully will mean better achievements over the many existing processes.

Of particular importance are those processes for preparation of coal which involve dissolution of the coal in a cast bath to fix the carbon contained in the coal under treatment. It is even more advantageous if the aforesaid bath is the same as the bath used in the present invention.

To carry out the proposed process a crucible furnace is required. This furnace is preferably a pressurized converter type furnace coated with a refractory material, mounted on trunnions and provided, at the bottom, with premixing charge nozzles. The nozzles are two-way nozzles and concentric. Hydrogen is injected into the equipment through the internal duct of each nozzle which acting as outlet end of a fluidized transport system for powdered solids.

In a similar manner, coal is pushed through the external duct of each nozzle by a fluid-state hydrocarbon.

Fluid pressures within the furnace are within the range between 2 and 1 2 atmospheres.

The quantity of heat required for the reaction energy is supplied to the bath preferably by means of induction coil systems which have an appropriate connection to an electrical supply line.

Also required are pressurized and continuous supply type hoppers, each with a workingpressure charging device.

A control element controls the supply of raw materials automatically, in doses, according to indications from sensor devices by which the process is controlled.

A tank of nitrogen is used as a safety means to cool the nozzle system while the furnace is at the horizontal position.

The following equipment is also required if hydrocarbons are to be produced on a large scale by means of the proposed process: Raw materials drying plant.

Raw materials milling plant.

Effluent purifying plant, for waste products from the process.

Storage tanks.

Bath ladle and slag reservoir.

The crucible furnace is placed in a horizontal position and preheated to the operating temperature. Nitrogen is blown through the nozzles, which charge the carburized bath. Upon completing this operation, the crucible is again placed in a vertical position and the flow of nitrogen is simultaneously switched to blow through corresponding charge nozzles. Hydrogen is injected through the internal nozzle, carbonaceous material and flux are injected through the external nozzle and the electric supply to the induction coils is switched on.

The particular hydrocarbon compound which the process is principally designed to produce is obtained through the furnace mouth or port, lesser quantities of other hydrocarbons, impurities and some carburized bath particles, which should subsequently be separated in the gaseous effluent cleaning device, from where it is transferred to the storage tank.

To complete the production cycle, the furnace is again placed in a horizontal position and the charge flow through the nozzles is again switched to a nitrogen flow. Finally, the carburized bath is discharged, the nitrogen flow being maintained so that the lining temperature of the bath does not affect the useful life of the nozzles.

Two embodiments of the process of the invention will be described in more detail: 1. Production of methane. CH4 A converter furnace of 200 tonne capacity is filled with cast iron containing 4% carbon at atmospheric pressure and 1 3000C.

Raw material. Residual petroleum coal.

Composition C 98%, volatile matter 2%, ash 0.5% 5 0.5% Technical or elemental hydrogen 99%.

Flow of raw materials.

Carbon 0.00481 tonne/sec H2 0.00167 tonne/sec Energy 6,150 kW Product Methane 9.33 m3/sec or 33,588 m3/hr The slag flows and sulfidric sulphur-containing flows are negligible due to the high quality of the coal used as raw material.

2. Acetylene production.

The furnace and the raw materials used in Case 1, at the pressure of 2 atmospheres. Raw materials charge flows Coal 0.147 tonne/sec Hydrogen 0.00123 tonne/sec Energy 200.604 MW Product 0.01593 tonne/sec or 13.72 (acetylene) Nm3/sec or 49,407 Nm3/sec

Claims (4)

Claims

1. A process for producing hydrocarbons, characterized by the use of a crucible-type furnace which is insulated and provided with heating means, said furnace containing a carburized metal bath into the middle of which a current of carbonaceous milled matter and a current of technical or elemental hydrogen is injected.

2. A process for producing hydrocarbons as claimed in claim 1 characterized in that the crucible-type furnace is pressurized.

3. A process for producing hydrocarbons as claimed in claim 1 or 2 characterized in that a current of crushed flux is also injected into the metal bath.

4. A process for producing hydrocarbons substantially as hereinbefore described.