RU2703515C1 - Device for plasma-chemical hydrocracking of heavy hydrocarbons - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to hydrocracking hydrocarbon fractions. Described is a device for plasma-chemical hydrocracking of heavy hydrocarbon fractions, comprising an indirect-action plasmatron with a tubular cathode, a swirler of plasma-forming gas and a stepped nozzle and a reactor made of a thick-wall tube with an upper and lower flanges, branch pipes for removal of reaction products and residues of raw material, nozzle for supply of raw material into reactor, as well as nozzle for water injection, characterized by that on the upper end of the raw material supply branch pipe there is installed an annular nozzle, imparting rotary movement to the hydrocarbon raw material leaving it, and a plate, and internal volume of reactor is separated by cylinder, fixed on lower flange of reactor and forming stripping chamber.

EFFECT: high efficiency of the hydrocracking process by creating microzones with large temperature drops outside the zone of action of plasma ions on hydrocarbon material, longer service life of the nozzle and anode by preventing ingress of water droplets on their surface and longer life of the cathode due to more intense heat removal.

5 cl, 2 dwg

Description

The invention relates to hydrocracking of hydrocarbon fractions, in particular, heavy oil or fuel oil raw materials, for their purification from harmful impurities and increase the octane number. It can be used in the oil refining industry in the field of deep oil refining, to obtain light fractions (fractions of diesel fuel, kerosene, gasoline, alcohols and gas), purification of oil products from harmful impurities, as well as during the operation of heat-generating plants where it is rational to replace liquid fuel with gas .

The closest analogue of the claimed invention is a device for hydrocracking heavy hydrocarbon fractions, consisting of a reactor, on the top cover of which a plasmatron is mounted. A sleeve with a plasma torch anode is installed on the bottom cover of the reactor, into which hydrocarbon raw materials and water are fed through the nozzle and the channel system in the bottom cover of the reactor (RU 2574732, 01/14/2016)

The device has several disadvantages that significantly reduce its performance.

1. The water supply to the reaction zone for the formation of microzones with a temperature difference on the surface of the hydrocarbon feed takes about half the area from which the evaporation of hydrocarbons could take place, and, in addition, the energy of the plasma ions entering the microzones with a low temperature is spent on heating and water evaporation and does not participate in the cracking of hydrocarbons.

2. Water vapor formed in the reaction zone impedes the passage of plasma ions to the surface of the hydrocarbon feedstock to effect the cracking process.

3. A certain number of tiny droplets of water inevitably fall on the surface of the anode and nozzle. When water transitions to a vapor state, the metal breaks out from the surface of these parts, i.e. leads to their quick failure.

4. There is no direct contact of the cathode with the liquid to remove heat and heat is removed from the cathode through its contact with the cathode tube, this is not enough. Therefore, the cathode also quickly fails.

The objective of the invention is to provide such a device for plasmachemical hydrocracking of heavy hydrocarbons, which would eliminate the above disadvantages.

The technical result achieved by the implementation of this invention is to increase the productivity of the hydrocracking process by creating microzones with large temperature differences outside the zone of plasma ion exposure to hydrocarbon feeds, increasing the life of the nozzle and anode by preventing water droplets from getting on their surface, and increasing the life of the cathode due to more intense heat removal.

The specified technical result is achieved in a device for plasmachemical hydrocracking of heavy hydrocarbons, consisting of a plasma torch and a reactor.

Indirect plasma torch with a tubular cathode. The plasma jet is compressed by a stream of air supplied through a swirler, which is also a cathode holder. The cathode is inserted into the swirl, with a conical fit along the end of the cathode, and when the swirl is screwed onto the cathode tube, it is tightly pressed through a special sleeve and a rubber o-ring in the seat. The cooling fluid passes through a tube inserted into the cathode pipe until it stops in the cathode, the gap between the swirler wall and the cathode and returns through the cathode pipe to the external cooling circuit of the plasma torch. Thus, the cathode, from the outside, is completely washed by the cooling fluid, which can significantly improve the heat removal from the plasma torch, and, consequently, increase its service life. The inner end of the tubular cathode is insulated with a heat-resistant ceramic sealant. The sealant, being an insulator, prevents the cathode spot from converging into the center of the tubular cathode.

The plasma torch is screwed into the upper flange of the reactor, and when voltage is applied between the nozzle and the cathode, an electric arc arises, which then jumps through the formed plasma to the anode screwed in the center of the annular reactor nozzle. In the initial position, the end of the anode is below the nozzle head by 15-20 mm. At the end of the anode, the plasma flow changes direction by 90 degrees. The central part of the anode is also filled with a heat-resistant ceramic sealant, which prevents the anode spot from moving to the center and the anode spot, with a stream of air, rotates around the periphery of the end of the anode. Heat is removed from the anode by a stream of hydrocarbon feed. As the anode burns out, it is moved up with the help of a pin passing through the pipe for supplying hydrocarbon raw materials.

Towards the plasma flow, a hydrocarbon feed is supplied to the annular nozzle equipped with a swirler. Moving, under the action of centrifugal forces along the wall of the annular nozzle, the hydrocarbon feed is exposed to plasma ions, resulting in the cracking of long hydrocarbon molecules. Broken hydrocarbon molecules, remaining in the liquid state, will not be able to get out of the liquid phase, since the temperature in the nozzle chamber is much higher than the temperature of the liquid, and molecules fragmented to the state of gas fractions are squeezed out of the liquid. An important condition for ensuring effective cracking is the turbulent mode of fluid flow.

A plate is installed on the head of the annular nozzle with an inner diameter smaller than the diameter of the nozzle chamber, which separates the stream exiting the nozzle chamber into liquid and gaseous phases.

The liquid phase, which is a fragmented and whole hydrocarbon molecules comes out under the plate and spreads over the inner surface of the stripping chamber. Water is sprayed over the hydrocarbon surface in the stripping chamber through the nozzle, forming microzones with a large temperature difference. Water, when heated, passes into steam, which continuously pushes the heated layers from the surface of the raw material and fills the stripping chamber, therefore, immediately above the surface of the hydrocarbons, the temperature will be equal to the boiling point of water, i.e. 100 degrees Celsius Intensive separation of hydrocarbon molecules begins in the stripping chamber both in the contact zone of the microzones with a large temperature difference, and over the entire surface of the hydrocarbons in the stripping chamber. Since fragmented hydrocarbon molecules exposed to plasma ions have more energy, they will primarily be released from the liquid phase. Hydrocarbon molecules that are not exposed to plasma ions, having lost part of their energy on heating and the transition of water into steam, are removed from the stripping chamber through the drain windows.

Gaseous products exit through the gap between the upper flange of the reactor and the plate: gas fractions of hydrocarbons, partially air, carbon dioxide, which are mixed in the upper part of the reactor with the effluent from the stripping chamber.

In the mixed volume, the reaction of water vapor with the gas fraction of hydrocarbons will additionally occur with the formation of carbon monoxide and hydrogen, which will fill the free bonds of the fragmented hydrocarbon molecules.

The essence of the claimed invention is illustrated by drawings, where na fig. 1 shows a plasmatron for plasma production, and FIG. 2 shows a reactor for plasmachemical hydrocracking of heavy hydrocarbons.

Indirect plasma torch, with a tubular cathode, gas-vortex movement of the cathode spot and a step nozzle. Air is used as a plasma-forming gas. In FIG. 1 details of the plasma torch are indicated under No. 1-17 Cathode tube 1 with a swirl 11 screwed onto it and a cathode 13 with a special sleeve 17 inserted into it, is screwed inside the dielectric insulator 3. The cathode pipe is fixed in the right position with the lock nut 2. On the dielectric insulator there are grooves for rubber o-rings 15 and a groove 12 between them with a through hole for supplying air to the swirler 11 A steel bond 16 with a fitting 14 welded to it is put on the dielectric insulator.

Using the nut 5 and the fixing half rings 10 above, the assembly described above is attached to the case of the plasma torch 6. A nozzle is installed in the case 8. Two fittings 7 and 9 are screwed into the case 6 to supply and discharge cooling liquid. At the end of the body there is a thread for installing a plasma torch in a plasma-chemical reactor.

The reactor is depicted in FIG. 2 in detail under No. 18-31. The reactor vessel 19 is made of a thick-walled pipe, to the lower part of which a flange 21 is threaded under the pipe 22 for supplying hydrocarbon raw materials. Inside, concentrically to the plasma torch body, a cylinder 25 is attached to the flange 21 by spot welding, with drain windows, the internal volume of which forms a stripping chamber. An annular nozzle consisting of a swirl 28 and a housing 27 is screwed onto the upper end of the nozzle 22. An anode 31 is screwed into the swirl, which can be moved as it is worked out by a pin 23. A plate 30 with a skirt 29 is mounted on the head of the ring nozzle. The skirt has several longitudinal slots .

A nozzle 24 is screwed into the reactor vessel to supply water to the stripping chamber and temperature sensors 26 to monitor the hydrocracking process. In the lower and upper parts of the reactor vessel, nozzles 20 are welded for the exit of liquid hydrocarbons and reaction products, respectively. On top of the reactor is closed by a flange 18 with a thread under the plasma torch body.

The device operates as follows.

The device is not an independent unit capable of carrying out the entire cycle of operations for the processing of heavy hydrocarbons into light petroleum products and is capable of only cracking hydrocarbon molecules, so it can be used as a separate module in an oil refinery.

Since in plasma-chemical hydrocracking only a small part of the hydrocarbons turns into steam, the separation of light hydrocarbon fractions from the feed (fuel oil) at the first stage must be carried out using a cyclone in order to exclude contact of the reaction products with the feed.

Given that the reactor should provide a turbulent flow regime, i.e. pressure losses in the circulation piping will be significant, the feed to the reactor is carried out by a separate pump.

Based on the foregoing, the raw material heated to operating temperature is supplied to the reactor of the plasma chemical hydrocracking device by a pump from the still bottom tank of the first column. The reaction products and unreacted raw materials enter the cyclone, and the reaction products through the upper nozzle are sent tangentially to the upper part of the cyclone, and the unreacted raw materials merge directly into the lower part of the cyclone, without rotation. The separated reaction products are sent to the column to separate the light fractions, and the feed from the bottom of the cyclone is returned to recirculation, to warm up to operating temperature.

Start up work.

1. Apply voltage to the power source of the plasma torch, turn on the cooling of the plasma torch. An inert gas (argon) is supplied as a plasma-forming gas at the time of the start of the plasma torch by air piping

2. Check the circulation of raw materials through the bypass line, bypassing the reactor, turning on the pump. The volume of pumped raw materials through the reactor should be 1.5 times the volume subjected to hydrocracking. The temperature of the raw materials is within 250 degrees Celsius. Then the pump is stopped and the piping is reconfigured for circulation of raw materials through the reactor:

3. Turn on the plasmatron. An electromagnetic contactor is pre-mounted on the mass cable of the power source, which at the time of starting the plasma torch leaves the main power circuit open, and after the appearance of the plasma, the electromagnetic contactor automatically closes the circuit and immediately feeds the reactor material. After starting the plasma torch, using the time relay, the air supply to the plasma torch automatically opens and argon is shut off;

4. Check the parameters of the operating mode (current of the plasma torch power source, circulation pressure, temperature of the raw material entering the reactor) of the device and, when they deviate from the calculated ones, make adjustments;

5. Turn on the water supply to the stripping chamber. After water supply, a well-audible crack appears in the reactor, indicating the transition of water to a vapor state:

6. Choose the optimal mode of operation of the device, achieving maximum output. This is achieved by changing the water supply to the stripping chamber, following the temperature readings in the upper and lower parts of the reactor. According to the practice of using the existing design of the plasma chemical hydrocracking device, with the optimum volume of water supplied to the stripping column, the temperature in the upper part of the reactor is within plus or minus 15 degrees Celsius of the temperature of the raw material at the reactor inlet. At the bottom of the reactor, the temperature of the unreacted feed should not be lower than 160 degrees Celsius (in order to avoid the ingress of water into the feed to be recycled). Excessive pressure in the reactor has a negative effect on the plasma chemical hydrocracking process; therefore, the pressure in the reactor should not exceed 0.05 MPa.

Claims (5)

1. Device for plasma-chemical hydrocracking of heavy hydrocarbon fractions, containing an indirect-action plasma torch with a tubular cathode, a plasma gas swirl and a stepped nozzle, and a reactor made of a thick-walled pipe with upper and lower flanges, pipes for removing reaction products and residues of raw materials, a pipe for supplying raw materials in the reactor, as well as a nozzle for injecting water, characterized in that an annular nozzle is attached to the upper end of the pipe for supplying raw materials, imparting rotationally e motion withdrawing therefrom a hydrocarbon feedstock, and a plate and an inner cylinder volume of the reactor is separated, secured to the bottom flange of the reactor and forming the stripping chamber. 2. The device according to p. 1, characterized in that the hollow cathode is installed inside the swirl plasma torch. 3. The device according to claim 1, characterized in that the inner end of the tubular cathode is coated with a heat-resistant dielectric sealant. 4. The device according to p. 1, characterized in that the annular nozzle together with the plate form a chamber in which the cracking of the raw material leaving it is carried out. 5. The device according to claim 1, characterized in that water is injected through the nozzle to supply water to the surface of the rotating layer of hydrocarbon feedstock in a stripping chamber.

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