DD237120A1

DD237120A1 - DEVICE FOR INFLUENCING LIQUID SUBSTRATES IN PLASMACHEMICAL ARC REACTORS

Info

Publication number: DD237120A1
Application number: DD25644783A
Authority: DD
Inventors: Helmut Drost; Hans Behlke
Original assignee: Adw Ddr
Priority date: 1983-11-08
Filing date: 1983-11-08
Publication date: 1986-07-02

Abstract

Die Erfindung betrifft eine Vorrichtung zum Einspeisen fluessiger, insbesondere kohlenwasserstoffhaltiger bzw. oelhaltiger Substrate zwecks pyrolytischer Umsetzung in einem plasmachemischen Lichtbogenreaktor. Die Vorrichtung ist gegenueber den bisherigen Loesungen technisch einfacher und garantiert eine guenstigere Energieausnutzung sowie als Folge der Unterdrueckung des Anfalls fester koksartiger Pyrolyseprodukte laengere Reaktorstandzeiten. Erfindungsgemaess wird dies dadurch erreicht, dass das einspeisende Substrat mittels Wasserstoff als Treibgas als Aerosol oder Schaum so in den Reaktor geleitet wird, dass die Kathodenwaerme zur Substratverdampfung genutzt wird, wodurch sich eine Voraufheizung des Substrats eruebrigt. Gleichzeitig wird mittels der Substratmenge und des Treibgasdruckes die Einspeisung so reguliert, dass der nicht verbrauchte Teil des Substrats als wasserstoffhaltiges Aerosol laengs der Anodeninnenflaeche gefuehrt wird, wodurch sich das Abscheiden fester Produkte weitgehend verhindern laesst. Durch Ausfuehrung der Kathode als massiver stumpfer Stab lassen sich erhoehte Verdampfungsraten und damit ein hoeherer Stoffdurchsatz erzielen. FigurThe invention relates to a device for feeding liquid, in particular hydrocarbon-containing or oelhaltiger substrates for the purpose of pyrolytic reaction in a plasma-chemical arc reactor. The device is compared to the previous solutions technically simpler and guarantees a more favorable energy utilization and as a result of the suppression of the attack of solid coke-like pyrolysis longer reactor life. According to the invention this is achieved in that the feeding substrate is passed by means of hydrogen as a propellant gas as aerosol or foam in the reactor so that the cathode heat is used for substrate evaporation, whereby a preheating of the substrate is eliminated. At the same time, the supply is regulated by means of the amount of substrate and the propellant gas pressure so that the unused portion of the substrate is guided as hydrogen-containing aerosol along the Anodeninnenflaeche, which can prevent the deposition of solid products largely. By carrying out the cathode as a solid blunt bar, increased evaporation rates and thus a higher material throughput can be achieved. figure

Description

— Wegfall des600°C — Vorheizkessels samt der notwendigen Sicherheits-und Dosierungsvorrichtung und dadurch Vereinfachung der Reaktorkonstruktion.- Removal of the 600 ° C preheating boiler together with the necessary safety and dosing device, thereby simplifying the reactor design.

— Einsparung des zusätzlichen Energieaufwandes für die Verdampfung der Flüssigkeit im Heizkessel.- Saving the additional energy expenditure for the evaporation of the liquid in the boiler.

— Anwendbarkeit der Vorrichtung auch im Niederdruckbereich bis zu 50 Torr und darunter, der besonders wichtig ist für die Acetylen-Synthese aus flüssigen Kohlenwasserstoffen.- Applicability of the device in the low pressure range up to 50 Torr and below, which is particularly important for the acetylene synthesis from liquid hydrocarbons.

— Ein niedrigerer Energieaufwand für die Synthese der Zielprodukte bei der Plasma-Pyrolyse von flüssigen Kohlenwasserstoffen.- A lower energy consumption for the synthesis of the target products in the plasma pyrolysis of liquid hydrocarbons.

— Hohe Standfestigkeit des Reaktors bei der Pyrolyse von flüssigen Kohlenwasserstoffen infolge der Verhinderung des Anfalls und des Absetzens von festen koksartigen Produkten an der Anodenwand und an der Kathode.- High stability of the reactor in the pyrolysis of liquid hydrocarbons due to the prevention of seizure and settling solid coke-like products on the anode wall and at the cathode.

— Ein höherer Stoffdurchsatz durch bessere Nutzung der Plasma-Enthalpie für die chemische Stoffwandlung.- Higher throughput through better use of plasma enthalpy for chemical conversion.

— Höhere Konzentration des Zielproduktes infolge eines geringen Bedarfs an Wasserstoff als Treibgas.Higher concentration of the target product due to low hydrogen demand as propellant.

embodiment Example 1:

Als Reaktor dient ein zwischen einer stumpfen stabförmigen Wolframkathode 3 (6 mm 0) und einer kupfernen zylinderförmigen Hohlanode 4 (20 mm 0) brennender und durch ein axiales Magnetfeld 2 zur Rotation gebrachter Lichtbogen 1 (sogen, rotierender Bogen).As a reactor between a blunt rod-shaped tungsten cathode 3 (6 mm 0) and a copper cylindrical hollow anode 4 (20 mm 0) burning and brought by an axial magnetic field 2 for rotation arc (so-called, rotating arc) is used.

Die Substrateinspeisung erfolgt über einen mit Wasserstoff betriebenen Aerosolzerstäuber 6. Im Ausgang des Zerstäubers ist die Kathode 3 der rotierenden Bogenentladung 1 in einem Haltering 8 befestigt, in dem eine Anzahl von Bohrungen (2 mm 0) konzentrisch um den Schaft der Kathode 5 angebracht sind. Die Kathode 3 ist mit Ausnahme eines Teiles von etwa 7 mm mit einem dünnen Metallrohr 5 umgeben (8,0 mm 0), das einerseits im Anodenbereich 4 von einem Quarzrohr 7 bedeckt ist, wobei lediglich eine Kathodenspitze 3 von etwa 1,5mm freiliegt.The substrate is fed in via a hydrogen-powered aerosol atomizer 6. In the outlet of the atomizer, the cathode 3 of the rotating arc discharge 1 is fixed in a retaining ring 8, in which a number of bores (2 mm 0) are mounted concentrically around the shaft of the cathode 5. The cathode 3 is surrounded (8.0 mm 0) except for a part of about 7 mm with a thin metal tube 5, which is covered on the one hand in the anode region 4 of a quartz tube 7, with only a cathode tip 3 of about 1.5 mm exposed.

Die Funktion der erfindungsgemäßen Anordnung besteht darin, 'das aus dem Zerstäuber 6 strömende Substrat-Gas-Gemisch längs der Kathode 3 in unmittelbarem Kontakt mit ihr bis zu deren unterem heißem Ende 9 zu leiten, wo es aufgeheizt und in ein Gas-Dampf-Gemisch umgewandelt wird. Das Quarzrohr 7 verhindert ein Ansetzen des Bogens 1 an das Substratleitrohr 5.The function of the arrangement according to the invention is to direct the substrate-gas mixture flowing from the atomizer 6 along the cathode 3 in direct contact with it to its lower hot end 9, where it is heated and into a gas-vapor mixture is converted. The quartz tube 7 prevents the sheet 1 from being applied to the substrate guide pipe 5.

Example 2:

Die Testung derEinspeisungsvorrichtung erfolgte mit Paraffinöl als Modellsubstrat. Der Öl-Massenfluß betrug etwa 1,35 kg/h. Als Zerstäubergas wurde Wasserstoff benutzt mit einer Durchflußrate von 475 l/h. Die Potentialdifferenz zwischen Kathode 3 und Anode 4 betrug 175 V, Der Bogenstrom 30 A, das Magnetfeld 2 etwa 1 000 Gauß, die Rotationsgeschwindigkeit des Bogens 1 etwa 4000 U/s und der Druck im Reaktor 100 Torr. Es ergab sich für das gebildete Azetylen ein spezifischer Energieaufwand von 8,6 kWh/kg.Testing of the feeder was with paraffin oil as a model substrate. The oil mass flow was about 1.35 kg / h. Hydrogen was used as a nebulizer gas with a flow rate of 475 l / h. The potential difference between cathode 3 and anode 4 was 175 V, the arc current 30 A, the magnetic field 2 about 1,000 Gauss, the rotational speed of the arc 1 about 4000 U / s and the pressure in the reactor 100 Torr. It resulted for the formed acetylene a specific energy consumption of 8.6 kWh / kg.

Claims

Invention claim:

1. Device for feeding liquid hydrocarbon substrates for the purpose of implementation in a hot arc, characterized in that using the cathode heat, the liquid to be reacted previously mixed in a mixing device by means of a propellant gas or aerated or foamed and then with the help of a to the cathode (3) enclosing guide tube (5) passed to the hot cathode end and is evaporated before entering the reactor space.

2. Device according to item 1, characterized in that to prevent coke-like precipitates on the anode (4) a part of the reacted substrate-gas mixture wets the anode wall (4).

3. A device according to item 1, characterized in that to prevent coke-like precipitates on the cathode (3) the liquid substrate, a sufficiently high proportion of hydrogen is mixed before the substrate-gas mixture enters the hot zone of the cathode (3) ,

4. Device according to item 1, characterized in that to increase the substrate evaporation rate, the cathode (3) is designed as a blunt rod.

For this 1 page drawing

Field of application of the invention

The application is in the field of plasma pyrolysis of liquid substrates in the arc, in particular in the reaction of saturated hydrocarbons (higher alkanes, gasolines, oils and lignite ingredients) to simple unsaturated compounds (C ₂ H ₂ ; C ₂ H ₄ ).

Characteristic of the known technical solutions

In the reaction of liquid hydrocarbons in plasma chemical reactors to acetylene, the substrates are generally fed as an aerosol or as a vapor in the plasma. The substrate feed as an aerosol has the advantage that no preheating of the substrate is required. However, it has the disadvantage that valuable plasma energy is expended for substrate heating. In addition, especially in the vacuum range for atomization, a high throughput of propellant gas is required, on the one hand reduces the concentration of the target product in the pyrolysis, on the other hand by blowing the sheet process operation discontinuous designed (DE-OS 2,731,042, DE-OS -2 634616). In the case of substrate injection in vapor form, the disadvantages of the aerosol feed are avoided, but the provision of an evaporation part makes the reaction process more complicated and, moreover, the total energy expenditure for the process higher.

In the case of the rotating arc evaporation feed is characterized in that the substrate is evaporated in a separate vessel outside the reactor, mixed with water vapor, to the required temperature up to 600 ⁰ C is heated and then introduced under pressure into the reactor (US-3 168592 US-3,320,146).

Object of the invention

The aim of the invention is to improve the plasma-chemical material conversion process of liquid substrates in the electric arc energetically by means of a special feed device, to simplify technically and to increase the service life of the reactor by reducing the seizure of solid reaction products.

Object of the invention

The invention has for its object to make the feed so that the cathode heat is used for Substrataufheizung or evaporation, so that the liquid substrate is fed as a mixture of substrate aerosol and substrate vapor.

Features of the invention

According to the invention this is achieved in that the liquid substrate to be fed passes from a reservoir by positive pressure into a mixing device located at the upper end of the cathode, where it is mixed with a propellant gas. The mixture of substrate and propellant is subsequently directed along the cathode to the lower end of the hot cathode where it is vaporized by the cathode heat. The use of hydrogen as a propellant gas largely prevents the formation of solid coke-like pyrolysis products. At the same time a portion of the liquid is guided along the anode wall and thus used as a rinsing agent, which can be prevented deposition of solid products formed on the anode wall largely. The particular advantages of the invention are: