SYSTEM FOR THE PRODUCTION OF CARBON BLACK

Abstract: In a system for the production of carbon black and hydrogen by the decomposition of hydrocarbon gas, there is in connection with the thermal decomposition reactor (1) provided a reactor (2) with adjustable temperature zones in order to influence and control the properties of the carbon black as well as to modify the surface and structure of the carbon black. The reactor has means for supplying gases and materials in the various temperature zones. Downstream of the reactor (2) there is provided a cooler (3) for the reactions products, in which feed gas and plasma gas can be preheated (19) and which is followed by separation means which may preferably consist of a cyclone (4, 5) for separating coarse particles from the carbon component. The cyclone (4, 5) is connected to a filter device (7) wherein carbon black of the desired particle size and structure is filtered out to a silo (8) and further processing. The system is equipped with a pipe for transfer of hydrogen partly to the chemical process industry, as an energy carrier, as well as back to the reactor (2) via a return pipe.

Description: System for the production of carbon black The invention relates to a system for the production of carbon black and hydrogen by the decomposition of hydrocarbons. A number of different systems and processes for the production of carbon black from hydrocarbon gases are known in the prior art. One group of these processes utilizes thermal decomposi¬ tion of hydrocarbons into a carbon black and a hydrogen com¬ ponent by the use of a plasma torch. However, the methods used until now have usually only resulted in other gaseous hydrocar¬ bon products, e.g. acetylene. Until now no system has been developed which has enabled a continuous production of carbon black and hydrogen to take place, since the earlier systems have had to be stopped after short operational periods due to the formation of deposits, so that the torches and reactors have had to be cleaned before the system could be put into operation again. These disadvantages have resulted in the systems being very expensive to operate with correspondingly high costs for the final products. A further disadvantage with the known systems has been that they did not allow full control to be obtained of the final products, i.e. carbon black and hydrogen which were produced, since it has only been possible to produce a standard quality of carbon black with regard to physical properties, with the result that further processing of this product has had to be based on the carbon black obtained. The hydrogen has mainly been burned off. The object of the present invention is to provide a system for the production of carbon black and hydrogen by decomposition of hydrocarbon gas, which can be operated in a continuous process and where it is possible to preset the process conditions in such a way that a carbon black can be produced with predeter¬ mined physical properties. This object is achieved with a system which is characterized by the features in the patent claims presented. With the system according to the invention a rational and continuous production of carbon black for further processing is made possible, wherein the " carbon black is produced with a desired particle size and structure, in such a manner that the carbon black is accurately adapted to suit a subsequent ap¬ plication. Furthermore, a very rational and economical opera¬ tion is achieved, as portions of the produced hydrogen are returned to the plasma torch and used there as plasma gas. Moreover, hydrogen is used in the plasma torch together with the hydrocarbons in the feed gas, thus reducing the electrode consumption and thereby resulting in a further saving. In the system unwanted particle sizes and coarse fractions are fil¬ tered out, thus obtaining a uniform, defined final product. This is in addition to the fact that a reactor is used in which, by means of admixtures and adjustment of the heat zone, it is ensured that the carbon black produced has the desired structure. By means of the cycle used in the system and the return of hydrogen together with the use of natural gas or methane as the starting material, a highly pollution-free decomposition of the hydrocarbons is achieved, so that blockages and fouling in the reactor system are avoided and a continuous process thereby is achieved. The invention will now be described in more detail by means of an embodiment, which is illustrated purely schematically in the drawing, which shows a simplified process diagram for a system according to the invention. The system which is outlined in the attached drawing illustr¬ ates the principal features which are of importance for the present invention, all other pipelines and piping normally used and which would be present in a system of this kind having been omitted for reasons of clarity. Thus the drawing shows only those principles which are utilized in the invention. The main section of the system comprises a plasma torch 1 wit an attached reactor chamber 2. The plasma torch is supplied with plasma gas which may be hydrogen through a pipe 12 and hydrocarbon gas, e.g. methane, from a storage tank 16 or directly from a gas pipeline through a pipe 17. As safety equipment pipes from, e.g. an argon supply (15) and a nitroge supply (14) can be connected to the pipe 17, these branch pip are usually closed by means of valves. In the plasma torch 1 the hydrocarbon gas is decomposed, in the example methane is decomposed into carbon black and hydrogen, which are further processed in the reactor 2 in order to obtain the desired physical properties for the resulting carbon black. This is done by controlling the temperature of zones in the reactor and a controlled supply o methane resp. admixtures through branch pipes which lead into the reactor chamber and which are schematically indicated by 18. The reactor design is described in more detail in the applicant's copending patent application 92 1360. The produc carbon black is passed from the reactor together with the hydrogen, the carbon black now having predetermined physical properties, through a pipe cooler 3 and on to separation equipment which, e.g., may consist of a cyclone arrangement 4, 5, where coarse particles are separated if these are not want for the further processing. In the cooling system the tempera ture is reduced from an exit temperature from the reactor whi can be between, e.g. 800 and 1600° C, to a temperature of, e. 50-160° C. The heat which is removed from the product stream can be heat exchanged at 19 with the feed gas and plasma gas for energy optimization. The exit temperature from the plasma torch in the reactor is of the order of 3000-8000° C. After separation of coarse particles in the cooling cyclone 4 the coarse particles are collected in a slag silo 5 from which they can later be removed and used for less critical purposes than the specially produced carbon black. The hydrogen and carbon black are passed on through the pipe 6 to a main filter 7 which filters off additional components, so that in the filter silo 8 there is collected only carbon black with a particle size within a desired, defined range and with a special structure which is achieved in the reactor section. The special carbon black can then be removed from the filter silo 8 for further processing. Remaining hydrogen can be recovered from the filters and combined with the hydrogen from the pipe. The hydrogen can either be supplied directly to a chemical processing industry or stored for later use, it can be used as an energy carrier and employed, e.g., in power production, and a desired portion is returned through the pipe 11 to the plasma torch and used as plasma gas there. For reasons of safety the system is connected to a flame stack 10 where the gas can be burned off. Thus one of the final products of the process which is carried out in the system is used as an operating means for the actual process. This offers the benefit of reduced energy consumption, while at the same time a completely pure gas without pollution is used as plasma gas, thus resulting in minimum contamination of the torch. In the starting up period it may be necessary to supply extra hydrogen from a supply. In controlling the hydrogen gas feed to the torch it is possible to control the operation of the reactor and the torch in such a way that the system thereby achieves some degree of self-monitoring. During normal operation the system will be completely self-sufficient in plasma gas. In the above description of the system only the main components are described and it should be quite obvious that many modif¬ ications will be possible within the scope of the invention. With the system according to the invention the benefit is also obtained that the produced carbon black will not be polluted by other elements than those which are present in the feed gas or by materials which it may be desirable to add and which can be added in the reactor. In a favourable embodiment of the invention the hydrogen gas which is used as plasma gas can in addition be supplied with hydrocarbon gas, which can have a favourable effect in connection with the combustion or the consumption of the electrodes, which will thereby be less rapidly consumed. The control of the hydrogen supply to the plasma torch is provided by means of a control valve which is linked to the conditions in the plasma arc.

Claims: PATENT CLAIMS > 1. A system for the production of carbon black and hydrogen by the decomposition of hydrocarbon gas, characterized in that in connection with the thermal decomposi¬ tion reactor there is provided a reactor with adjustable temperature zones in order to influence and control the properties of the carbon black as well as to modify the surface and structure of the carbon black, which reactor has means for supplying gases and materials in the various temperature zones, that downstream of the reactor there is provided a cooler for the reaction products and in which feed gas and plasma gas can be preheated and which is followed by separation means which may preferably consist of a cyclone for separating coarse particles from the carbon component, that the cyclone is connected to a filter device wherein carbon black of the desired particle size and structure is filtered out to a silo and for further processing, and that the system is equipped with a pipe for transfer of hydrogen partly to the chemical process industry, as an energy carrier, as well as back to the reactor via a return pipe. 2. A system according to claim 1, characterized in that the reactor is equipped with a plasma torch which can use hydrogen, hydrocarbon gas and combinations of these as plasma gas. 3. A system according to claim 2, characterized in that the plasma gas for the process consists exclusively of feed gas or decomposition gas from the filtering device and that the quantity of hydrogen which is returned as plasma gas is controlled by the effect on the plasma torch, with a control valve linked to the plasma arc. 4. A system according to claim 1, characterized in that the system is operated without the supply of any materials other than feed gas. 5. A system according to claim 1, characterized in that the cooler is a pipe cooler for preheat¬ ing feed gas and plasma gas.

Inventors: HAUGSTEN KJELL E, HOX KETIL, LANGOY JOSTEIN, LYNUM STEINAR, HAUGSTEN, KJELL, E., HOX, KETIL, LANGOEY, JOSTEIN, LYNUM, STEINAR
Applicants: HAUGSTEN KJELL E, HOX KETIL, KVAERNER ENG, LANGOY JOSTEIN, LYNUM STEINAR, KVAERNER ENGINEERING A.S.
Application year: 1993
Main classification: C09C1
IPC codes: C01B3, C09C1