JPH0323481B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for pyrolyzing heavy oil. In particular, the present invention relates to improvements in a heavy oil supply device that is supplied to a pyrolysis channel. The present inventors have conducted various studies on methods for thermally decomposing heavy oil in the presence of steam, and as a result of conducting various studies on methods for thermally decomposing heavy oil in the presence of steam, the inventors have found that a temperature of 800° C. ~1100℃, pressure 0~50Kg/ ^cm2G ,
It was found that it is best to carry out the process with a residence time of 0.2 seconds or more. At this time, heavy oil is supplied to the main steam flow supplied from the starting point of the pyrolysis channel or upstream from it, but for the purpose of effective use of heat, multiple pyrolysis channels are provided in parallel. The product streams can also be combined and then subjected to subsequent, eg, catalytic steam reforming. Furthermore, for the purpose of effectively utilizing steam, the heavy oil can be divided and supplied from the starting point of the pyrolysis channel and at least one point downstream from the starting point. According to conventional knowledge, heavy oil is normally supplied to such a pyrolysis channel by an atomizer using steam or other ejecting gas. This type of supply device uses the main steam flow itself or a jet of gas (or steam) for heavy oil supply to disperse heavy oil into the main steam flow, and is effective. It is intended for distributed supply. A very typical example of such an atomizer is the
The inner space 1 in the concentric double tube is shown in the figure.
1, heavy oil passes through the outer space 22, and ejection gas such as steam passes through the outer space 22. However, the structure near the ejection part 55 allows the ejection gas to be concentrated in, for example, the inner pipe 99 and the outer pipe 88. It is complicated and difficult to manufacture, as it requires an inner piece 77 of the outer tube for the purpose of operation, and furthermore, in order to operate properly, it is necessary to precisely adjust the relative positions of the heavy oil outlet 33 and the ejection gas outlet 44. It is complicated to handle. In addition, the target thermal decomposition reaction generally takes place at temperatures above 700°C and is also endothermic, so the water vapor used for ejection is heated to temperatures above 700°C.
On the other hand, depending on the type of oil, heavy oil generally begins to decompose at a temperature not exceeding 500°C, so the inner space 11 through which the heavy oil passes is set to 700°C or more. It is necessary to sufficiently insulate the outer space 22 through which water vapor or the like having a temperature of .degree. If this insulation is not sufficient, there is a risk that the inner space 11 will be clogged with precipitation and deposits (mainly carbon) due to decomposition of heavy oil. Due to this complicated structure, this mechanism is expensive, and the large size of this mechanism also increases the restrictions on where it can be installed. If you want to make it squirt, it will be quite difficult. The present invention was completed as a result of research to find a method that does not have the disadvantages of using conventional feeders. That is, the present invention provides a method in which heavy oil containing high molecular weight hydrocarbons that cannot be evaporated is pyrolyzed in the presence of water vapor in a pyrolysis channel. At least one of the oil supply devices consists of only one flow path for discharging heavy oil and is a single tubular flow path without a mechanism for atomization, and the flow rate of the fluid in the pyrolysis flow path is is 10 m/sec or more, and the heavy oil is supplied from the single tubular flow path in a substantially upstream direction with respect to the fluid. Conventionally, the supply of heavy oil in this type of heavy oil pyrolysis method has required a supply device that involves active atomization, which has a complicated structure as explained above with reference to Fig. 1. It has been believed that it must be On the other hand, the method of the present invention is capable of carrying out the desired thermal decomposition reaction using a feeding device with an extremely simple structure. It has not been previously known that this process can proceed smoothly, and this was discovered and confirmed for the first time through research by the present inventors. The reason why the reaction proceeds sufficiently even when using the supply device consisting of a single tubular flow path used in the present invention is because the mixing state necessary for the reaction is achieved in the method of the present invention, or because the method of the present invention It is conceivable that the flow state of the steam and heavy oil, or even the gas for supplying the heavy oil in the method, provides particularly suitable conditions for promoting this reaction, but the details are not clear. The heavy oil used in the present invention is a substance containing as a main component high molecular weight hydrocarbons that have fluidity at room temperature or with slight heating, but cannot be substantially vaporized by heating. These include atmospheric distillation residue oil, vacuum distillation residue oil, tar, pitch, crude oil, especially heavy crude oil produced in Canada, Venezuela, China, etc., and heavy crude oil obtained from tar sands and oil shale in various places. be. In the method of the present invention, the flow rate of the fluid in the pyrolysis channel is 10 m/sec or more, and the heavy oil is supplied from a simple tubular path in a substantially upstream direction with respect to the fluid. This is an essential requirement. If any of these conditions is lacking, it will be difficult to continue operation due to disturbances or rapid increases in pressure loss within the pyrolysis flow path. In addition, it is preferable for stable operation that the jetting speed during supply is the same as or higher than that of the fluid, especially depending on the respective jetting and flow directions of the two and the extent to which their central axes coincide. Note that as long as these substantially match, the present invention can generally be carried out satisfactorily regardless of the magnitude of the ejection velocity. The flow velocity is preferably about 25 m/sec or more, more preferably about 50 m/sec or more. Here, the flow rate of the fluid in the pyrolysis channel refers to the reaction temperature/pressure, the cross-sectional area of the pyrolysis channel, and the supply amount (velocity) of the main steam flow supplied from the starting point of the pyrolysis channel or upstream thereof ) means the flow velocity of the main steam flow calculated from In addition to this main steam flow, if there is a gas supplied from outside the flow path, such as heavy oil ejection gas, the amount of that supply is also taken into consideration. Heavy oil is normally supplied after being preheated to a temperature of about 200 to 300°C, which is at most below the thermal decomposition temperature, in order to adjust fluidity. In the present invention, a single tubular flow path is defined as any flow path that can supply a desired amount of heavy oil into the pyrolysis flow path in substantially the same direction as the fluid in the flow path and, if necessary, at approximately the same speed. road is available. The simplest single-tubular flow path is one in which heavy oil is forced into one opening and ejected from the other opening, and of course it can be used, but in general, heavy oil whose fluidity is not very high is used as described above. Since discharging at a high speed may be inconvenient, such as requiring a special pressurizing mechanism, three openings for the heavy oil ejection gas flow path, heavy oil supply flow path, and heavy oil jet flow path are required. It is practical to use a trifurcated flow path and ejection gas. Such trifurcated channels can have any cross shape such as a T-shape, an inset shape, a Y-shape, a Y-shape, etc., and the axes of the three channels do not necessarily have to be on the same plane, and Any of the three intersecting legs may correspond to any opening. The most practical one is a T-shaped three-pronged flow path, where one side of the upper side of the T-shape corresponds to the gas flow path for discharging heavy oil, and the other side corresponds to the heavy oil jetting flow path. The vertical side corresponds to the heavy oil supply channel. When such a three-pronged flow path is used, the heavy oil quantitatively sent to the heavy oil supply path is combined with the ejection gas supplied to the ejection gas flow path at the communication intersection of the three-pronged The oil is ejected together with the gas from the opening of the oil ejection channel. In this case, the jetting speed of the heavy oil may be considered to be approximately equal to the jetting speed of the gas. Hereinafter, a typical example of a supply device used in the present invention will be explained with reference to the drawings. In Figures 2 to 4, the flow path 1 for the gas for discharging heavy oil is generally a cylindrical space having a circular or oval cross section, and the heavy oil discharge gas flow path 1 is generally a cylindrical space having a circular or oval cross section. The heavy oil flow path 2 communicates with the oil supply flow path 2 at a communication intersection 3 in a substantially T-shape, and the heavy oil flow path 2 is a cylindrical space corresponding to the leg side of the T-shape. The downstream end of the flow path 1 is located downstream of the communication intersection 3 when looking at the airflow of the heavy oil ejecting gas flowing through the flow path 1, and forms a spout 4. At the communication intersection 3 of the flow path 1 and the downstream part thereof, when carrying out the method of the present invention, the heavy oil expulsion gas flows together with the heavy oil, and downstream of the spout 4, both of them are further thermally decomposed. If there is another preceding supply mechanism further upstream of the steam or pyrolysis channel in the channel, the heavy oil will flow together with the previously supplied material and/or its decomposed products, and the heavy oil will be cracked. Smooth operation and good reaction results are achieved if the jetting velocity of the material ejected from the supply mechanism into the pyrolysis channel is approximately equal to or higher than the flow velocity of the material flowing in the pyrolysis channel in advance. It is necessary for. FIG. 2 shows the most typical example, where channels 1 and 2 communicate at a communication intersection 3 with their axes orthogonal to each other. In Figure 3, channels 1 and 2 are connected in a T-shape, and channel 2
The heavy oil supplied from the flow path 1 includes a component in the opposite direction to the flow of the ejection gas flowing through the flow path 1 and joins the gas. Conversely, in FIG. 4, the flow paths 1 and 2 communicate in a Y-shape, and the heavy oil containing the forward component of the ejection gas merges. The gas for ejecting the heavy oil that has merged at the communication intersection 3 is ejected from the jet port 4 into the pyrolysis flow path, and further merges with the main steam or the main steam and the pyrolysis products upstream. The shapes, sizes, etc. of the two channels and the upstream and downstream sides of the communication intersection 3 of the channel 1 do not have to be the same, and can be changed as necessary to the extent that they do not impede the achievement of the object of the present invention. are selected. For example, inserting an orifice or a restriction near the outlet of the flow path 2 at the communication intersection 3 to the flow path 1, or providing one or more restrictions or bulges between the communication intersection 3 of the flow path 1 and the spout 4. , a conical shape between the two, and a flow path 1 between the communication intersection 3 and the jet port 4 from the flow path 1 upstream from the communication intersection 3 (referred to as flow path 1A).
The mixing state etc. can also be changed by, for example, causing the ejection gas to flow into the flow path 1B (referred to as the flow path 1B) in the tangential direction of the flow path 1B. 5 to 8 show other examples of the single tubular passage of the present invention, in which both flow passages are depicted by a single solid line for simplicity. Figure 5 shows two heavy oil flow paths 2 and the same communication intersection 3.
This is an example in which the pipe 1 is connected to the flow path 1 of the gas for discharging heavy oil. The two heavy oil flow paths may be used for feeding the same or different heavy oils at the same time, or one may be used as a spare and used when the other fails. Moreover, both axes do not necessarily have to be on the same straight line, and may form an angle of 60° or the like on a plane perpendicular to the flow path 1, for example. In the example of FIG. 6, the axes of the two channels 2 are 1 in FIG.
The flow path 2 on the right in FIG. are doing. Therefore, if there is an accident in the flow path 2, the closed flow path 2' can be opened and used. In addition, when cleaning the flow path 2, etc., it is possible to open the closed flow path 2' and clean it from that side. It is also convenient. In this sense, the same convenience can be enjoyed if a passage that can be closed and opened is provided in place of the closed flow path 2'. FIG. 7 shows an example in which a plurality of channels 2 are distributed from upstream to downstream of the channel 1, and of course the shape, dimensions, approach angle, and mounting position of each channel 2 as seen from the axial direction of the channel 1 are shown. etc. may be different, the heavy oils fed by husband and wife may not be of the same type, and they may not all be used at the same time. FIG. 8 shows an example in which the flow path 1 is bent at the communication intersection point 3. Although it is not very common, it can be used when physical space is limited or for other needs. FIG. 9 shows an example in which the supply device used in the present invention is installed at the most upstream part of the decomposition channel. It is formed by three tubes that fit together. The flow path 1 is constricted near the jet nozzle 4, thereby increasing the jet flow velocity. The main steam flow for the reaction flows from the main steam inflow path 5 formed by a branch pipe concentrically screwed to the block 7 outside the pipe forming the flow path 1 on the side of the spout 4 to the decomposition flow path. The heavy oil and the ejecting gas are supplied to the most upstream part of the fuel tank 6, and the heavy oil and the ejecting gas are jetted out from the jet port 4 in the same direction as the steam flow into the center of the pipe and subjected to a thermal decomposition reaction. The example in Figure 10 shows that when heavy oil is supplied midway from upstream to downstream of the pyrolysis flow path or main steam flow path for various reasons, for example, heavy oil may be supplied even midway through the pyrolysis flow path. This is an example suitable for the case where oil is supplied, etc., and the supply mechanism without the steam inflow channel 5 is used as shown in FIG. In the vicinity of the part where the curve changes to a straight line touching it, heavy oil and supply gas are pumped from the flow path 1 on the side of the jet nozzle 4 with the straight line axis as the axis, by aligning the jet direction with the flow direction of the pyrolysis flow path. is supplied to the pyrolysis channel 6. 10th
In the figure, blocks etc. shown in FIG. 9 are omitted for simplicity. Particularly in cases such as this example, the feeding mechanism of the present invention is advantageous because it requires less space than conventional ones. However, in the case of Fig. 10, the jetting direction during the supply of heavy oil and the flowing direction of the fluid in the pyrolysis channel do not substantially match, so the jetting velocity during the supplying is different from that of the fluid. It is necessary that the speed is the same as or higher than. In addition, when carrying out the method of the present invention, generally the ejection flow velocity from the ejection port 4 is approximately the same as or higher than the flow velocity in the pyrolysis channel 6, and in approximately the same direction as the fluid in the pyrolysis channel. is desirable for good thermal decomposition of heavy oil. However, there are 7 exceptional conditions.
As stated in lines 3 to 5 on page 3. If the ejection flow velocity is too small, the pressure loss in the pyrolysis flow path will be greatly disturbed and increased, making it difficult to operate the cracker. On the other hand, if the ejection flow velocity is too small, it will be difficult to operate the cracker. This is not always easy with pressurized jetting, and even when ejecting gas is used, as described below, the amount of ejecting gas at a temperature lower than the pyrolysis reaction temperature increases, which is undesirable as it causes a decrease in the temperature of the reaction system. . The flow velocity in the pyrolysis channel is preferably less than 100 m/sec, more preferably less than 90 m/sec, to avoid excessive pressure loss and is practical. The heavy oil ejection gas used in the method of the present invention is typically at least one of water vapor, hydrogen, carbon monoxide, carbon dioxide, nitrogen, etc., but when two or more supply devices of the present invention are used, There may be one that does not use ejection gas, and the gases used in the husband and wife supply mechanisms or their compositions may not be the same as occasion demands. In addition, the flow rate of gas may be adjusted, for example, to adjust the speed of ejection from the ejection port.
The most appropriate value can be set for each individual supply mechanism. The temperature of the ejecting gas should be lower than the decomposition start temperature of heavy oil, which is generally about 300 to 500 degrees Celsius, preferably 20 to 50 degrees Celsius, to prevent premature decomposition in the feeder. In addition to preventing troubles due to heavy oil supply or non-supply, the supply device, especially the flow path 1
It is possible to suppress the temperature rise due to heat in the heating furnace or decomposition channel through which the flow channel 1 normally passes and projects, and is also convenient for purging heavy oil. The range that can be used for general purposes even if the type of heavy oil changes is 25.0.
A temperature below ℃ is suitable. On the other hand, if it is too low, it will reduce the fluidity of heavy oil, which is inconvenient.
The temperature is preferably 200°C or higher. The pyrolysis gas obtained by the method of the present invention may be used as it is as a raw fuel after removing moisture and the like as appropriate, but it is generally better to use it after further catalytic steam reforming. In the method of the present invention, it is possible to enjoy various advantages of the present invention as described above by using at least one supply device consisting of the single tubular flow path described above, but it is difficult to supply heavy oil due to diversion of existing equipment or other reasons. There is no problem in using a conventional atomizer or the like as part of the device. As mentioned above, the product obtained by the method of the present invention can be used as a variety of raw materials and fuels, but this product can be directly subjected to catalytic steam reforming to convert it into a gas whose main components are hydrogen and carbon monoxide. The most typical usage is to do so. In this case, the product stream from the outlet of the pyrolysis channel is supplied to the reformer via an appropriate conduit or collecting pipe as required. As the catalyst to be filled in the reformer, any catalyst normally used for steam reforming of hydrocarbons can be used with an appropriate composition, shape, size, etc.; Since it often contains impurities such as organic compounds and inorganic substances containing sulfur and the like, in such cases, it is best to select a composition and shape that can withstand poisoning by these substances. In addition, multi-layer packing of different types of catalysts is carried out, for example, by filling the front stage of the reformer with a catalyst that emphasizes durability against poisoning rather than the reforming effect, and the latter stage with a catalyst that has a large reforming effect. Good too. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto. The gas composition was analyzed by gas chromatography on the gas after dehumidification. Example 1 Improved HP (HP specified in ASTM-A297
A pyrolyzer with a supply device similar to that shown in Fig. 9 is used at the most upstream part of a pyrolysis channel made of a material with improved durability and has an inner diameter of 70 mm and a length of 30 m. An externally insulated reformer with an inner diameter of 400 mm and a length of 3.0 m (made of heat-resistant firebrick with an external heat-insulating layer and steel exterior) was connected via an externally insulated conduit. CaO/Al ₂ O ₃ weight ratio in the 1.5 m section before the reformer
52/48 calcined spheres (diameter 10 mm) were filled, and the latter 1.5 mm was filled with calcined spheres (diameter 10 mm) of CaO/Al ₂ O ₃ /NiO in a weight ratio of 32/51/15. In addition, in order to compensate for the reaction heat by partial combustion of the mixture after pyrolysis, the reformer is equipped with an additive gas inlet near the pyrolysis inlet at the most upstream part of the reformer, and a small amount of air is supplied. and reformed it. Other conditions, results, etc. are shown in Table 1. Note that piping, equipment, etc. between the supply channels for heavy oil, steam, and supply gas to the reformer outlet are sufficiently externally insulated as necessary. Example 2 A supply device having the structure illustrated in Fig. 10 was installed at the most upstream part of a pyrolysis channel with an inner diameter of 30 mm and a length of 20 m that meandered back and forth approximately twice in a radiant heating furnace at approximately 1100°C. A pyrolyzer having a structure in which the steam flow flows from the upper left side to the lower side of the decomposition channel 6 in FIG. 10 was used, and the following reformer and its connections were the same as in Example 1. Other conditions, results, etc. are shown in Table 1. Comparative Examples 1 to 2 In place of the supply device of the present invention in Examples 1 and 2, an atomizer having a structure as shown in Fig. 1 that utilizes main steam to atomize heavy oil was used, but each of the Examples was the same as in Examples 1 and 2. 1
Using the same pyrolyzer and reformer as in 2 and 2, experiments were conducted under the conditions shown in Table 1, and the results shown in Table 1 were obtained.
However, in these comparative examples, compared to the examples, it was necessary to adjust the atomization state of the heavy oil in advance, and since the supply mechanism was large, handling such as installation was complicated. Example 3 and Comparative Example 3 Experiments were carried out in the same manner as in Examples 1 and 2, respectively, except that the conditions related to the heavy oil jetting speed were changed as shown in Table 1. The results are shown in Table 1. Comparative Example 3 used the apparatus shown in FIG. 10, in which the supply device was provided at the curved part of the flow path and the jetting direction and the flow direction did not substantially match, as in Example 2, but the jetting speed at the time of supplying was The operating results were poor because the velocity was lower than the velocity of the fluid in the decomposition channel. Example 4 Instead of the atomizer in Comparative Example 1, the first
Comparative Example 1 was carried out using the atomizer shown in the figure without the inner piece 77 of the outer tube, which has a simple structure and is not intended for atomization, and therefore does not require any special adjustment. Similar good results were obtained. In addition, the heavy oil used in each of the above examples has a specific gravity of
0.944, carbon/hydrogen weight ratio 7.08 (C: 85.0wt%,
H: 12.0wt%), a kinematic viscosity of 67.30cST at 50°C, and a total calorific value of 10440Kcal/Kg, and was supplied after being preheated to the temperature shown in Table 1. Gas composition was analyzed by gas chromatography after drying the gas.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an example of a supply device using an atomizer, FIGS. 2 to 4 are schematic diagrams showing representative examples of the supply device used in the present invention, and FIGS. A diagram showing a flow path of another example of the single tubular passage of the invention, FIG. FIG. 3 is a schematic cross-sectional view showing an example of a method for attaching the feeding device shown in the figure. DESCRIPTION OF SYMBOLS 1... Heavy oil ejection gas flow path, 2... Heavy oil supply flow path, 3... Communication intersection, 4... Spout port, 5...
...Main steam inflow path, 6...Pyrolysis flow path.

Claims (1)

[Claims] 1. In a method in which heavy oil containing high molecular weight hydrocarbons that cannot be evaporated is pyrolyzed in the presence of water vapor in a pyrolysis channel, At least one of the heavy oil supply devices consists of only one flow path for discharging heavy oil and is a single tubular flow path without a mechanism for atomization, and the fluid in the pyrolysis flow path is The flow rate of the heavy oil is 10 m/sec or more, the heavy oil is supplied from the single tubular flow path in a substantially upstream direction with respect to the fluid, and the jetting direction during the supply and the flow direction of the fluid are different from each other. A heavy oil pyrolysis method characterized in that, if they do not substantially match, the ejection velocity during the supply is the same as or higher than the velocity of the fluid. 2. Claims in which the single tubular flow path is a trifurcated heavy oil spouting flow path having three openings: a heavy oil ejection gas flow path, a heavy oil supply path, and a heavy oil jetting flow path. The method described in paragraph 1.