JPS5930701A - Method for thermally cracking heavy oil - Google Patents

Abstract

PURPOSE:To carry out the stable thermal cracking of heavy oil by dividedly feeding heavy oil to a thermal cracking pass and allowing steam to exist while keeping the ratio between the number of the molecules of steam and the number of the carbon atoms of heavy oil at a fixed value or above. CONSTITUTION:In a method for thermally cracking heavy oil contg. unvaporizable hydrocarbons with high mol.wt. in the presence of steam, the heavy oil is dividedly fed to a thermal cracking pass so as to keep the ratio between the number of the molecules of steam and the number of the carbon atoms of heavy oil (the ratio of S/C) at >= about 3.5-5.5. Heavy oil is fed from the 1st feeding section formed at the starting point of the pass, the thermal cracking of the oil in the presence of steam proceeds well in the pass, and heavy oil is fed from the 2nd feeding section formed at the downstream side of the pass. Feeding sections may be further formed at the downstream side to feed heavy oil. It is not always required to restrict the kind of the heavy oil to be supplied from the feeding sections to the same kind.

Description

[Detailed description of the invention] The present invention relates to a method of heavy oil pyrolysis.

According to the findings of the present inventors, the method of thermally decomposing heavy oil in the coexistence of steam in a thermal decomposition channel without a filler is carried out by external heating preferably at a rate of 10 to 100 m/sec. At this time, the ratio of the number of molecules of water vapor supplied to the number of carbon atoms in the heavy oil (S10 ratio) varies depending on the type of heavy oil, equipment conditions, etc., but is usually about 3.5 to 5.5. The present inventor has also found that it is necessary for the ratio to be at least a certain value (limit B/'0 ratio). If not, operation may become difficult due to turbulence or increase in pressure loss in the pyrolysis flow path. Cheap. death,
However, the water vapor consumed here usually has a SlC ratio of 0.2 to
This ratio is about 0.3, and even when the obtained product is directly subjected to catalytic steam reforming to finally produce a gas rich in hydrogen and carbon monoxide, this ratio is stoichiometrically high. 2 is fine. Therefore, as it is, the water vapor consumption rate is poor. In addition, since thermal decomposition is generally endothermic, the contents of the thermal decomposition channel require heating, which leads to the disadvantage that unnecessary energy is wasted and excessive equipment is required due to the excess steam.

In order to eliminate this drawback, the present inventor conducted studies and completed the present invention. That is, the present invention provides a method for thermally decomposing heavy oil containing high molecular weight hydrocarbons that cannot be evaporated in a heat-decomposition channel in the presence of steam. The supply is from a first supply section provided at the starting point of the flow path and at least one subsequent supply section provided downstream therefrom,
This is a method of pyrolysis of heavy oil, which is characterized in that it is carried out in parts. 0 Heavy oil as used in the present invention has fluidity at room temperature or under slight heating, but when heated, it becomes substantially vaporized. It is a substance that contains as a main component high molecular weight hydrocarbons that cannot be oxidized, and typically includes atmospheric distillation residue oil, vacuum distillation residue oil, tar, pitch, crude oil, especially heavy oil produced in Canada, Venezuela, China, etc. As mentioned above, conventional SZ
If the C ratio is not kept above the above-mentioned constant value, that is, the limit S/a ratio, pressure loss will be disturbed or increased in the pyrolysis flow path, and the reason why operation cannot be continued is unclear, but solid or highly viscous carbonaceous The inventor has confirmed that this is not due to precipitation/deposition. It is presumed that this problem probably occurs due to the loss of dynamic balance of the fluid state within the pyrolysis channel. In the method of the present invention, excessive supply is avoided due to operational requirements as described above. In order to increase the degree of utilization of steam that is not obtained, the thermal decomposition of the heavy oil supplied from the first supply section provided at the starting point of the thermal decomposition channel in the coexistence with steam has substantially progressed sufficiently. Heavy oil is supplied from a second supply section provided near a downstream location in the flow path in an amount (i.e., at a supply rate) that does not cause operational difficulties as described above.

Furthermore, if necessary, a fifth supply section and subsequent supply sections are similarly provided downstream to supply heavy oil.

The heavy oil type supplied from each supply section does not necessarily have to be the same, and in order to provide fluidity suitable for each supply, it is generally kept at a temperature of 200 to 300℃ or less, or at most 500℃ or less. Warming is performed.

The supply of heavy oil from each supply section to the pyrolysis flow path is such that the pyrolysis reaction occurs in the fluid containing water vapor flowing in the flow path until the next adjacent supply section or the exit of the flow path. In order to ensure that the thermal decomposition progresses to the desired degree, the thermal decomposition is carried out at an appropriate supply rate using a distributed feeder such as an atomizer that uses steam or other driving gas, or other feeders that do not inhibit the good progress of thermal decomposition. The more you do, the better.

In the process of the present invention, superheated steam, typically at a temperature of 700 DEG to 1000 DEG C., is introduced into the pyrolysis channel from the first feed section or from upstream thereof. This water vapor is hereinafter referred to as main water vapor. In the case of supplying heavy oil from the first supply section, the heavy oil supply device used in the first supply section can be an atomizer such as an atomizer, and main steam can be used as the driving gas. Heavy oil is fed into the pyrolysis channel from a non-dispersion type feeder, which is generally smaller than an atomizer, using the pressure of the heavy oil itself or the pressure of steam or other appropriate ejected gas. This is particularly practical for supply sections after the second supply section, which are often spatially restricted compared to the first supply section; In order to prevent this, the flow rate of the fluid in the flow path should be set to 10 m/sec or more, preferably 25 m/sec.
/second or more, more preferably 5 or 11/second or more, and the jetting speed of the heavy oil or the ejection gas from the non-dispersed type feeder is around or higher than the flow rate of the fluid described above. Good. Even when heavy oil is supplied from a distributed feeder, it is better to keep the flow rate of the fluid within the upper range.
This is preferable because it does not require precise adjustment of the dispersion state of heavy oil. Note that the practical upper limit of the flow rate is 1 oom/sec, preferably q
dm/sec or less is better.

The temperature and pressure inside the pyrolyzer is 800~ at the exit of the pyrolyzer.
If the operation is carried out at 1050°C and the pressure is about 1 to 40 atm, a stable and preferable reaction will occur. The length of the flow path outlet 1 is determined to achieve the desired final production.
However, if the residence time force in each section is ≦0.2 seconds or more and 4 seconds or less, preferably 0.4 seconds or more and 2 seconds or less, sufficient thermal decomposition power is usually obtained during that time; proceed. If it is less than 0.2 seconds, the dissociation reaction is insufficient.
The 4-method method is disadvantageous because the reaction rate is usually slow and no particularly significant effect can be obtained, and the equipment becomes too large.

The heavy oil thermally decomposed by the method of the present invention can be used for various purposes such as hydrogen, carbon oxide, carbon dioxide, and lower hydrocarbons. The most typical application is as a raw material for catalytic steam reforming to produce gases containing oxyhydrogen and carbon monoxide as main components, in which case the effluent from the pyrolysis channel outlet is generally required. Depending on the situation, it is directly led to a catalytic steam reformer via an appropriate conduit and subjected to reforming.

The reformer contains a normal catalyst used for this type of reforming.
The composition, shape, and dimensions are selected and used depending on the properties of the heavy γ field. In general, heavy oils contain impurities such as compounds containing nitrogen, sulfur, oxygen, etc., and inorganic compounds in addition to hydrocarbons. Therefore, depending on the type of heavy oil, select a catalyst that can withstand the insertion caused by these. For example, the front stage of the reformer is filled with a catalyst that is resistant to poisoning even if its reforming effect is somewhat inferior, and the latter stage is filled with a catalyst that focuses on the reforming effect. In the method of the present invention, it is possible to use the catalyst packed in multiple layers.Other effects of the divided supply of heavy oil are explained below. Ru.

In other words, in the conventional method of supplying the entire amount of heavy oil at the starting point of the pyrolysis channel, thermal decomposition, which is an endothermic reaction, occurs immediately near the starting point and the temperature drops significantly, resulting in a decrease in the reaction rate. Compensating for this temperature drop by increasing the external force solar temperature is not appropriate in terms of energy and heat resistance of the material of the pyrolysis channel, so it will eventually lead to a long residence time.
Narrowing efficiency is poor.

On the other hand, in the method of the present invention, the heavy oil is supplied separately, so the endothermic stress in the vicinity immediately after each supply section is reduced, the width of the temperature drop is small, and the temperature distribution throughout the flow path is also improved. As a result of homogenization, the overall efficiency of the reaction is improved.

Therefore, it is possible to shorten the reaction channel or increase the flow rate accordingly. In other words, reaction results comparable to conventional methods can be obtained with a shorter residence time.

The degree of distribution of heavy oil to each supply section directly affects the temperature distribution in the pyrolysis flow path and the residence time of the heavy oil, so it should be carefully determined in consideration of the following matters.

For simplicity, heavy oil of the same quality is supplied from every supply section,
In addition, assuming that the distance between each supply section and the adjacent supply section and the distance between the most downstream supply section and the outlet of the pyrolysis channel are all the same, from the point of view of making the temperature distribution in the flow channel uniform, 1. It is preferable that the distribution of heavy oil be equal between each supply section or gradually increase toward the downstream, but in order to shorten the residence time, it is better to have a higher distribution toward the upstream side. Therefore, in practice, the total amount of heavy oil to be supplied divided by the number of supply sections is 0.5 to 1.
5 times, preferably 0.6 to 1.4 times, more preferably 0
゛, 7 to 1.3 times the amount is distributed to the individual supply sections! Such a distribution is preferable in terms of the balance of various conditions.

In addition, increasing the number of supply sections is advantageous because it is possible to lower the S/C ratio overall, but the spacing between adjacent supply sections must be extremely large for the reaction to actually take place. Since it cannot be shortened, increasing the number of supply sections will increase the length of the decomposition flow path and thus the size of the pyrolyzer, as well as complicate the structure of the pyrolyzer and increase its operational efficiency. Since this increases the difficulty, 2 to 5 pieces, especially 3 to 4 pieces is suitable in practice.

The interval between two adjacent feed sections may be long enough or longer to allow the heavy oil supplied from the upstream feed section to be decomposed to a practically desired degree.

The present invention will be explained below with reference to examples, but the following examples merely show typical specific examples of the present invention, and the present invention is not limited thereto.〇Example 1 to 4 and Comparative Examples 1 to 4 An improved EP (AST
Using a flow path made of a material that further improves the heat resistance of HP specified in M-A297, there is a first supply section in the population, a first temperature measurement point 4.5 m downstream from the first supply section, and a first temperature measurement point 9.0 m downstream from the inlet. A second supply section at 15.5 m downstream from the inlet, a second temperature measurement point 18 m downstream from the inlet, a third supply section 22.5 m downstream from the inlet.
A device with a third temperature measurement point 5 m downstream was used. In the comparative example, a similar pyrolyzer as described above was used, except that it did not have the second and third supply sections.As for the supply mechanism, the first supply section on each side was In the atomizer nozzle that atomizes quality oil, in the second to S supply sections of each embodiment, water vapor passes through the horizontal pipe of the T-shaped pipe, and heavy steam flows toward this pipe from the vertical pipe. A nozzle was used in which quality oil was fed under pressure, and the outlet side of the steam was the jetting side of both, and the steam was saturated at a pressure of 25 to 1/an2. Also, the jetting speed of the mixture being jetted from the nozzle (
In practice, it is assumed that the jetting velocity of the steam is equal to the velocity of the steam stream to which the mixture is fed (but may contain heavy oil or its decomposed products fed from an upstream feed). The ejection direction was set so that the reaction pressure of the nuclear partner was 15 Kg/(32G).

The raw material oil used was an Arabian light type oil with a weight ratio of 48~. 5
0chi, Khafuji type 48-50%, Iranian snake 1-4
Atmospheric residue oil obtained from the same crude oil having a composition of 0.944 and a carbon/hydrogen weight ratio of 7. Re (0:85.Owt%tH:12,0wt%) Kinematic viscosity (
50°C) 67.3 cT Total calorific value 10440 K cal / 4 was used.

On the gold side, the product stream from the pyrolysis device is passed through a heat-resistant steel conduit with a heat-insulating layer and a steel exterior, and is then passed through a heat-resistant refractory brick conduit filled with catalyst to the outside. 400gg in diameter with a heat insulation layer and steel exterior,
It was flowed into a 3 m long reformer to perform catalytic steam reforming. As a catalyst, the weight ratio of OaO/MaOs is 52.
The former stage was filled with 1.5 m long balls (approximately 171 kg) of 10 diameter balls obtained by molding and firing a mixture of CaO/A, /, 20. A diameter of 10 obtained by molding and firing a mixture of NiO/NiO with a weight ji ratio of 32151/15
No. 11 balls were used by filling the rear stage with a length of 1.5 m (approximately 190 Kf). In addition, an additive gas inlet is provided at the above-mentioned inlet at the most upstream part of the reformer, and an appropriate amount of air is introduced to combust a part of the reactants to be contacted, and the generated combustion heat lowers the temperature associated with the endothermic reaction of the contact reaction. I tried to compensate for the decline.

Various conditions and results other than those described above are summarized in Table 1. In Comparative Examples 2 and 4, the pressure loss was greatly disturbed soon after the start of the experiment, and finally, after 2 hours and 1.5 hours, respectively, the pressure loss became too large and operation became impossible. Therefore, in these, gas analysis etc. were omitted and the description of the amount of added air was also omitted.

Furthermore, since the amounts of saturated steam used in the second and sixth supply sections were at most two to three times the amount of the main steam flow, they were included in the main steam flow and displayed.

The gas composition was analyzed by gas chromatography after drying the gas.

The pyrolyzer gas outlet gasification rate is the ratio of carbon atoms contained in the gas obtained from the pyrolyzer outlet to the amount of carbon atoms contained in the supplied heavy oil.

From the comparison of Comparative Examples 1 and 2 and Comparative Examples 5 and 4, in the combination of the above pyrolyzer and heavy oil, the limit S/O ratio is 5.
．． It appears to be around 5. As mentioned above, in Comparative Examples 2 and 4, even if the S10 ratio was set to around 5.0, operation became impossible in 1.5 to 2 hours due to excessive pressure loss, but in Examples 1 to 3, S/ Even though the total O was lowered to around 4.0, it was possible to operate for a sufficiently long time.

Furthermore, the total s7c in Example 4 is the same as S/○ in Comparative Example 1, but the gasification rate at the pyrolyzer outlet is 5% higher than in Comparative Example 1, which indicates the effectiveness of the method of the present invention. It shows.

Furthermore, in all of the comparative examples, the temperature at the first measurement point was significantly lower than in the examples, so it is thought that the efficiency as a whole was lowered.

The results of the present invention will be explained in detail by taking Example 1 as a representative example. Heavy oil is heated to 200 to 300°C in one preheating tank and given good fluidity, and is It is divided into two streams and sent to the first to third supply sections. Steam 400 KII/Hr s heavy oil 3 in the flow path immediately after the first supply section
Since it is supplied at a rate of 2Kf/Hr, S10 is approximately 9.
It is 75. 24.4~/H from the second supply section for the water vapor after subtracting the amount of water vapor consumed up to the second supply section
Since heavy oil is supplied at r, S/ immediately after the second supply section
C is approximately 12.5. Similarly, S immediately after the third supply section
/O is 14.7. As described above, in the method of the present invention, the B/O after each supply section in the reaction flow path must be sufficiently larger than the minimum magnification of the BZC ratio, and the number of H20 molecules in the amount of vapor and the total weight of the supplied Ratio of carbon atoms in oil (total S
/C) can be made sufficiently smaller than the limit S/C ratio, and the above-mentioned effects can be obtained.

Claims (1)

[Claims] In a method of thermally decomposing heavy oil containing high molecular weight hydrocarbons that cannot be evaporated in a pyrolysis channel in the presence of water vapor, supplying the heavy oil to the channel a first supply section provided at the starting point and at least one supply section also provided downstream;
A method of pyrolysis of heavy oil, characterized in that it is carried out in parts from two subsequent feed sections.