JPH0132275B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a novel method for directly producing liquefied oil and gas by thermally treating coal in the presence of hydrogen;
More specifically, it relates to a new method for rapid pyrolysis of coal in the presence of hydrogen. Recently, coal, which is the most abundant fossil fuel resource and is widely distributed around the world, has been reevaluated as an energy source that should replace oil as one of the means to deal with the future depletion of oil resources. It's starting to feel like this. However, coal is an extremely complex polymer compound, and its main constituents are carbon,
In addition to hydrogen, it contains considerable amounts of heteroatoms such as oxygen, nitrogen, and sulfur, as well as ash, so if it is burned as is, it will generate a large amount of air pollutants, and its calorific value is lower than that of petroleum. Many issues remain to be resolved, including problems with transportation and storage. Therefore, various methods have been proposed to liquefy coal and remove heteroatoms and ash with the aim of obtaining clean fuel oil, fuel gas, and value-added chemical raw materials. Typical of these methods include, for example, the method of extracting coal with a solvent (for example, U.S. Patent No.
4022680), a method for liquefying coal in the presence of hydrogen or a hydrogen donor (e.g. U.S. Pat.
4191629), a method of liquefying and gasifying coal in the presence of hydrogen (for example, Japanese Patent Application Laid-open No. 51-502), a method of liquefying and gasifying coal in an inert gas (for example, US Pat. No. 3,736,233) books), etc. In addition, as a method to directly obtain light oil and gas by heating coal, by jetting finely pulverized coal into a high-temperature, high-pressure hydrogen stream, it is possible to directly obtain light oil and gas in a short period of several tens of milliseconds to several minutes. Method for high-speed hydrogenation and thermal decomposition of coal (for example, Japanese Patent Application Laid-open No. 142703/1983)
is also known. This method uses, for example, pulverized coal at a pressure of 50 to 250 kg/cm ² (gauge pressure) and a temperature of 600 kg/cm 2 (gauge pressure).
This is carried out by rapidly heating coal at a rate of 10 ² - ^{10 3} °C/sec by ejecting it into a hydrogen stream at ~1200 °C, resulting in hydrogen pyrolysis, which produces methane,
Ethane, carbon dioxide, carbon monoxide, water vapor, hydrogen sulfide, ammonia, etc., as well as liquid products such as gasoline fraction, aromatic compounds with carbon atoms of 10 or more, high-boiling point tars, etc., and a solid product called char. are obtained respectively. However, in this method, lower reaction temperatures reduce the total conversion rate of coal to liquid or gas, i.e. the number of carbon atoms in the total product divided by the number of carbon atoms in the feed coal, multiplied by 100. If the reaction temperature is lower, aromatic compounds with carbon numbers of 10 or more and heavy oils such as tar become the main products, and if the reaction temperature is increased, the total conversion rate increases, but methane becomes the main product. However, there remained a problem in that the conversion rate to light oil was low. Traditionally, coal has been used as a way to solve this problem.
By pulverizing the coal to less than 100 mesh and ejecting it into a high-speed air stream, the heating rate of coal can be increased to 1000 mesh or less.
A reaction method that increases the conversion rate to light oil such as gasoline fraction while suppressing the production of methane by raising the temperature to 10,000℃/sec, the reaction temperature is 700 to 800℃, and the reaction time is 2 to 10 seconds. For example RBGrowcock and
DR Mackenzie, Fuel, Vol. 55, p. 394 (1976)], but the yield of gasoline fraction was still not sufficient. In addition, the coal is rapidly hydrogenated and pyrolyzed at a heating rate of 10 ⁴ °C/second or more, a reaction temperature of 800 to 1100 °C, a reaction time of 20 milliseconds to 2 seconds, and a pressure of 35 to 100 Kg/cm ² (gauge pressure). A method (for example, Japanese Patent Application Laid-Open No. 140505/1983) was also attempted. However, even with this method, 20 to 800
With a very short reaction time of milliseconds, the conversion rate to total liquid is as high as 30-45%, but the conversion rate to gasoline fraction is as low as 3-8%. Even if the length is increased, the conversion rate to gas only increases, while the conversion rate to gasoline fraction tends to decrease. The present inventors have conducted intensive research to improve the conversion rate to gasoline fraction in such known methods, and have found that gasoline fraction can be produced not only directly from coal but also as an intermediate liquid liquid. The product is further hydrogenolyzed and lightened to produce it,
and found that the latter is predominant overall, and that it is therefore necessary to increase the absolute amount of liquid product to improve the conversion to gasoline fraction. Based on this knowledge, the present invention has been made. That is, the present invention generates a gasoline fraction from coal at a high yield, and also significantly saves the amount of hydrogen for hydrogenation by suppressing the generation of methane gas due to the higher-order decomposition of ethane that is produced as a by-product. The present invention provides a method for hydrogenating and pyrolyzing hydrothermal coal. According to the method of the present invention, when coal is heat treated in the presence of hydrogen to liquefy and gasify it, (a) in a hydrogen stream at a temperature of 800 to 1100°C and a pressure of 35 to 250 kg/cm ² (gauge pressure); A step of ejecting fine coal powder to rapidly heat it and cause an instantaneous reaction, and (b) a step of reacting for 1.0 to 60 seconds at a temperature lower than the temperature of the previous step and in the range of 570 to 850 ° C. By doing so, the conversion rate to gasoline fraction can be dramatically increased while suppressing the conversion rate to methane. By the way, the reaction of converting coal to gasoline fraction in the present invention can be thought of mainly through two processes. One is that covalent bonds with low bond dissociation energy are cleaved by simple thermal decomposition of coal, and free radicals are generated. This is the first stage reaction process in which reactions such as hydrogen abstraction, dehydrogenation, recombination, and cyclization progress and are stabilized into liquid decomposition products.
The other is a second stage reaction process in which the pyrolysis liquid product produced in the first stage reaction process is hydrogenolyzed to further reduce the molecular weight. The first stage reaction process is considered to be completed in a relatively short time, and the higher the reaction temperature, the more
The cleavage of covalent supplies with low bond dissociation energy occurs violently. On the other hand, the second stage reaction process is a reaction in which a gasoline fraction is produced by the hydrogenolysis reaction of the liquid product produced in the first stage reaction process. It is necessary to carry out the process at a relatively low temperature in order to suppress the higher-order hydrogenolysis reaction of the produced ethane to methane. Therefore, in order to increase the conversion rate from coal to gasoline fraction, first, the reaction conditions that produce a large amount of liquid product that can become gasoline fraction in the first stage reaction process, and the second stage reaction process. An ideal reaction process can be achieved by selecting reaction conditions that make the rate of hydrogenolysis of the liquid product faster than the rate of hydrogenolysis of the gasoline fraction. To describe the reaction operation conditions of the present invention in more detail, the heating rate of coal is preferably faster in order to increase the amount of liquid product, preferably 10,000°C/second or more, and more preferably 50,000°C/second. In addition, in step (a), if the reaction temperature is high, the amount of methane produced will be large and the liquid product will be small, and if the reaction temperature is low, the thermal decomposition rate of coal will be slow.
The reaction temperature must be 800°C or higher and 1100°C or lower, preferably 850°C or higher and 1050°C or lower. (a) In the process, it is necessary to maintain the reaction temperature instantaneously within the above reaction temperature, but if the reaction time is short, the heating rate of the coal cannot keep up and the appropriate reaction temperature cannot be reached, and if the reaction time is long, methane Usually, because more is produced and less liquid product is produced.
It is preferably 20 milliseconds or more and 800 milliseconds or less, and more preferably 50 milliseconds or more and 500 milliseconds or less. (b) In the process, if the reaction temperature is high, the decomposition rate of the gasoline fraction will be high and the selectivity to the gasoline fraction will be reduced, and if the reaction temperature is low, the decomposition rate of the liquid product other than the gasoline fraction will be low. The reaction temperature is lower due to the lower conversion rate to gasoline fraction.
Must be above 570℃ and below 850℃, 600℃
Desirably above ℃ and below 800℃. On the other hand, if the reaction time is short, it is difficult to expect much improvement in the conversion rate to gasoline fraction, and if the reaction time is long, the decomposition of the gasoline fraction will proceed too much. 3.
It is preferable that the time is between 30 seconds and 30 seconds. The reaction temperature in each reaction zone does not necessarily need to be constant and may be changed over time. The pressure in step (a), in which the main reaction is the pyrolysis reaction of coal, is not significantly affected by the conversion rate from coal to liquid products. On the other hand, if the pressure in step (b), where the main reaction is the hydrogenolysis reaction of the liquid product produced in step (a), is increased,
The conversion rate to gasoline fraction increases, but if the pressure is increased beyond a certain level, the effect becomes smaller, and
If the pressure is high, the equipment will become huge and it will be economically disadvantageous. In this way, it is desirable to increase the reaction pressure in step (b), but providing a compression process between both reactions requires cooling, which is disadvantageous both in terms of reaction and thermal energy. b) Focusing on process pressure
The pressure in the (a) process is determined, and the pressure in the (i) process is the pressure in the (b) process plus the pressure loss in the reaction tube (which can usually be ignored).
It is desirable that the pressure be applied. The reaction pressure in both steps is preferably 35 Kg/cm ² G or more and 250 Kg/cm ² G or less, and more preferably 50 Kg/cm ² G or more and 200 Kg/cm ² G or less. The weight ratio of hydrogen for reaction to supplied coal (anhydrous, ash-free basis) varies depending on the type of coal and the composition of the required reaction product, and generally the weight ratio of hydrogen to supplied coal (anhydrous, ash-free basis) is 0.03. ~0.08 is sufficient, but in order to improve the diffusion of liquid products from coal and the diffusion of hydrogen into coal pores, increase the conversion rate from coal to gasoline fraction, and prevent coking.
It is desirable to supply excess hydrogen. but,
Excess hydrogen is separated from the products from the coal, returned to the reactor, and recycled, so if the amount of excess hydrogen increases, the energy and equipment required for separation, circulation, and heating will also increase, which is economically disadvantageous. Become. Therefore, the weight ratio of supplied hydrogen to supplied coal is preferably 0.1 or more and 1.5 or less, more preferably 0.2 or more.
1.0 or less. Note that the hydrogen gas flow as used in the present invention also includes a hydrogen-rich gas flow that satisfies the above conditions. When transitioning from step (a) to step (b), it is necessary to rapidly lower the reaction temperature. Heat recovery is achieved when lowering the reaction temperature by indirectly heat-exchanging the reaction hydrogen, rapidly cooling the reaction product of step (a) to the temperature of step (b), and preheating the reaction hydrogen. be able to. Another method is to supply hydrogen at a temperature lower than the (b) process reaction temperature at the end of the (b) process to rapidly cool the reaction product in the (b) process and achieve the temperature of the (b) process. I can do it. This method can increase the hydrogen partial pressure in step (b), increase the conversion rate to gasoline fraction and ethane, and also has a great effect on preventing coking. Furthermore, in part or all of the (b) process, indirect heat exchange is performed between the reaction product of the (b) process and hydrogen for reaction, and hydrogen at a temperature lower than the reaction temperature of the (b) process is transferred immediately after the (b) process. (a) By supplying
By rapidly cooling the process reaction product, the temperature of the process (b) can also be achieved. This method is expected to have the effects of both of the above cooling methods, and is the most effective method. Coal here refers to anthracite coal, bituminous coal, subbituminous coal, charcoal, lignite, dirty coal, grass coal, etc. The coal used in the present invention is preferably bituminous coal, subbituminous coal, or charcoal. EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples. Example 1 Illinois No. 6 coal was sequentially crushed using a geocrusher, a brown coal mill, and a ball mill, coarse particles were removed using a 200-mesh sieve, and then crushed in a vacuum dryer at -720 mmHg and 100°C for 10 minutes. It was dried for hours and the moisture content was adjusted to 3 parts by weight or less based on 100 parts by weight of coal. The elemental analysis values of the coal were as shown in Table 1 based on anhydrous coal.

[Table] Pressure 100Kg/cm ² G, room temperature hydrogen 1.0Kg/H, inner diameter 5
mmφ externally heated Hastelloy X hydrogen preheating tube
Preheat to 900°C, and further heat to 1150°C using an externally heated ceramic hydrogen heating tube with an inner diameter of 5 mm connected to the hydrogen preheating tube. On the other hand, the finely pulverized dry coal at room temperature of 2.5Kg/H is continuously fed using a table-type coal feeder under a pressure of 100Kg/cm ² G, and hydrogen at room temperature of 0.1Kg/H and a pressure of 100Kg/cm ² G is used. The coal is conveyed using a hydrogen gas stream, and the coal is jetted and mixed into the superheated hydrogen stream to rapidly raise the temperature of the coal from room temperature to 930°C. The heating rate of the coal at this time is approximately 2×10 ⁵ °C/
Estimated to be seconds. Further, the mixture of coal and hydrogen was passed through an externally heated ceramic reaction tube having an inner diameter of 6 mmφ, and a first stage reaction was carried out at a reaction temperature of 930° C. and a reaction time of 120 milliseconds. After that, pressure 110
Kg/cm ² G of room temperature hydrogen, 0.47 Kg/H, is mixed with the first stage reaction product to rapidly cool the reaction product to 700°C, and an external tube with an inner diameter of 50 mmφ connected to a ceramic reaction tube is heated. The mixture was passed through a heated stainless steel reaction tube to carry out the second stage reaction at a reaction temperature of 700°C and a reaction time of 13 seconds. Room temperature hydrogen is mixed with the reaction product from the second stage reaction tube to control the reaction product temperature.
After rapidly cooling to 430°C and separating the char with a chaat trap, the liquid product was condensed and separated from gas using an indirect water cooler and an indirect cooler using a -65°C refrigerant, and then analyzed. In order to keep the reaction temperature constant in each reaction zone, an electric heater was installed around the reaction tube, and the hydrogen heating tube, first and second reaction tubes, and the electric heater were placed in a stainless steel pressure-resistant container with an inner diameter of 500 mmφ. By accommodating the tube, the pressure resistance of the reaction tube was no longer required. In addition, the reaction pressure was 100 Kg/cm ² G, the amount of hydrogen supplied to the coal supplied in the first stage reaction was 0.5 weight ratio based on anhydrous ash-free coal, and the amount of hydrogen supplied to the coal supplied in the second stage reaction was 0.5% by weight. The weight ratio was 0.71. As a result of analysis of the reaction product, the conversion rate of the reaction product from coal based on carbon was as shown in Table 2.

【table】

[Table] Examples 2 to 9 Dry pulverized coal used in Example 1 (Illinois No. 6)
A reaction experiment was conducted on the same sample using the apparatus described in Example 1. Table 3 shows the results of various examples in which the temperature, time, pressure in the first and second stage reaction zones, and the amount of hydrogen supplied for reaction relative to the coal supplied were varied as reaction conditions. In order to change the reaction time in the first and second stage reaction zones, the lengths of the reaction tubes were appropriately changed.

[Table] Comparative Examples 1 to 6 The apparatus described in Example 1 was modified so that room temperature nitrogen gas could be introduced into the end of the first stage reaction zone, and the reaction product was rapidly cooled with nitrogen gas to stop the reaction. I did it like that. Using the same sample of pulverized coal as in Example 1, a reaction experiment similar to that in Example 1 was carried out at a coal supply rate of 2.5 kg/h. The experimental results are shown in Table 4. In addition, in each comparative example, the reaction time is based on experimental data in the vicinity where the gasoline fraction reaches its maximum.

[Table] Comparative Examples 7 to 10 A reaction experiment was conducted using the same sample of dry pulverized coal used in Example 1 and using the apparatus used in Example 1. As for the operating conditions for the reaction, the pressure was maintained at 100 Kg/cm ² G, and the temperature shown in Table 5 outside the specified range of the present invention was used as the reaction temperature for either the first stage reaction or the second stage reaction. , and other conditions were as shown in Table 5. The experimental results are shown in Table 5.

Table A summary of the advantages of the present invention compared to the prior art is listed below. (1) The conversion rate from coal to gasoline fraction increases by approximately 60%. (2) The conversion rate from coal to ethane increases by approximately 57%. (3) The total conversion rate from coal is approximately 60%, which is equivalent to conventional technology.
%, the conversion rate to methane is about 20% lower, so the amount of hydrogen consumed for reaction is lower, and hydrogen production costs can be reduced. (4) When lowering the reaction product temperature from the first reaction zone to the second reaction zone, coking in the second reaction zone can be reduced by supplying hydrogen for cooling.

Claims (1)

[Claims] 1. When coal is heat treated in the presence of hydrogen to liquefy and gasify it, (a) in a hydrogen stream at a temperature of 800 to 1100°C and a pressure of 35 to 250 Kg/cm ² (gauge pressure); A step of ejecting fine coal powder to rapidly heat it and cause an instantaneous reaction, and (b) a step of reacting for 1.0 to 60 seconds at a temperature lower than the temperature of the previous step and in the range of 570 to 850 ° C. A coal hydrogenation pyrolysis method characterized by: 2 (a) The heating rate of coal in the process is 10000
The method according to claim 1, wherein the temperature is at least ℃/sec. 3. The ratio of the amount of coal supplied (anhydrous, ashless standard) to the amount of hydrogen supplied for reaction in the (a) process is 10:
1. A method according to claim 1, wherein the ratio is 1 to 2:3. 4 (b) In a part or the whole of the step, heat is exchanged indirectly between the reaction product of the step (a) and the hydrogen gas for the reaction of the step (b), thereby cooling the reaction product and preheating the hydrogen gas. 2. The method according to claim 1, wherein the above steps are carried out at the same time. 5. A patent claim in which hydrogen gas at a temperature lower than the reaction temperature of step (b) is supplied at the end of step (a), and the reaction product of step (b) is directly quenched to reach the reaction temperature of step (b). The method described in item 1. 6. A patent for cooling a process reaction product by a combination of (a) indirect heat exchange with hydrogen gas for reaction in the process and (b) supplying hydrogen gas at a temperature lower than the reaction temperature in the process. The method according to claim 1.