DE2724833A1 - COAL GASIFICATION WITH NUCLEAR ENERGY - Google Patents

Description

- 3 - 24.377.6

Go / Fe 05/31/1977

GHT

Society for high temperature reactor technology mbH 5060 Bergisch Gladbach 1

Gasification of coal with nuclear energy

The present invention relates to a plant for generating methane or synthesis gas from carbonaceous substances with a nuclear-heated helium circuit. A first part of the carbon is converted into methane with hydrogen in a hydrogenating gasifier and a second part of the carbon is converted into synthesis gas with steam in a steam gasifier; At least part of the methane is converted into water vapor with steam in a cracking furnace. These plants deliver either methane (CH.) Or synthesis gas as a mixture of H_ and CO with small proportions of CO ₂ and CH ₄ .

In the journal: "Chemie-Ingenieur-Technik" 1974 , on page 938, in particular in Figure 1, and on page 941, in particular in Figure 2, a process scheme is described for the production of methane via the steam gasification of coal. On page 937 new processes of hydrogenating gasification of coal to methane are mentioned. However, both methods have a significant disadvantage. In the hydrogenative gasification is because of the long residence times of the coal and in consideration of the limited dimensions of the

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Vergasers cannot achieve a perfect conversion of the coal. In addition to the ash, the residual coke that falls from the hydrogenation gasification also contains approx. 30 - 45% of the carbon used. In the case of steam gasification, on the other hand, the carbon used can be gasified almost completely. Since this process only takes place at high temperatures (hard coal 790 ^° C., lignite 630-660 ° C.), only the upper temperature range of the heat released in the reactor can be used for gasification. In a pure steam gasifier process, the remaining heat can essentially only be used to generate steam and thus to generate electricity, because only a small part of this steam can be used in the process.

In the report ORNL / TM-5242 (Oak Ridge National Laboratory, November 19 76) on page 82 a system is shown in which carbon is converted into methane by means of nuclear heat will. The coal is first dried, then gasified with hydrogenation and the residual coke in a steam gasifier converted to synthesis gas. Part of the methane produced is stored in a methane cracking furnace (there referred to as reformer) converted into synthesis gas with the addition of hot steam. But this circuit has the following disadvantages: The process heat exchangers arranged in a primary but also in a secondary helium circuit are particularly complex. On the one hand, pipelines and apparatus carrying helium place increased demands to the tightness and on the other hand it must also be prevented that undesired substances on this Way into the primary circuit and either form unwanted deposits there or activated in this way that they interfere elsewhere. Also have

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all process heat exchangers heated with pure helium have the disadvantage that helium is not a single-atom gas Gives off radiant heat, which is a disadvantage especially at the high temperatures provided here. Man would have to increase the helium velocity in order to increase the heat transfer by convection.

The object of the present invention is a plant for generating methane or synthesis gas from carbonaceous Substances with a nuclear-heated helium cycle, which largely avoids the disadvantages described.

To solve this problem, a system according to claim 1 is proposed. Since the product gases at both Spill places with a very high temperature and it is uneconomical to only use this high temperature Regenerative preheating of the incoming product gas or Using this circuit to even use it to generate steam is a considerable improvement in overall efficiency expected of the plant. The requirements for the tightness of such a methane cracking furnace, especially in Area of the exchangeable catalytic converter are considerably smaller if only process gases are carried on both sides will.

The plant proposed in the second claim has particular advantages when mainly synthesis gas is produced should, because everything generated in the two gasifiers methane is split and the amount of heat required for it the two product streams that have to be cooled anyway. In addition, the arrangement results of two methane cracking furnaces in different places have particular advantages in terms of regulation and adaptation

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to different types of coal or different end products, for example methane or synthesis gas.

Figures 1 to 3 show possible embodiments of the invention in a highly schematic form.

FIG. 1 shows a system in which the methane cracking furnace differs from the one emerging from the steam gasifier Product gas is heated.

Figure 2 shows a plant in which a methane cracking furnace is heated by the product stream emerging from the hydrogenating gasifier.

FIG. 3 shows a system in which a methane cracking furnace is separated from the one emerging from the steam gasifier Product stream and a further methane cracking furnace from the product stream emerging from the hydrogenating gasifier is heated.

In all three figures, the gas-cooled high-temperature reactor 1 with a primary helium circuit 2 is via a heat exchanger 3 its heat to a secondary helium circuit 4, in which a steam gasifier 5, one after the other Process steam superheater 8, a steam generator 9 and a Fan 10 is arranged, which conveys the helium back into the heat exchanger 3. The raw coal is initially under Addition of hydrogen in the steam gasifier 11 to a large part is gasified and is then in the steam gasifier 5 with the addition of superheated steam almost completely transformed into a mixture of methane, hydrogen, carbon monoxide and carbon dioxide. That Product gas emerging from the hydrogenating gasifier 11 is in all three figures in the regenerative preheater

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used to preheat the hydrogen. It is then cooled in a further heat exchanger 13, at 14 dedusted and cleaned, at 15 freed from carbon dioxide and hydrogen sulfide and a low-temperature gas decomposition 16 supplied. The product gas emerging from the steam gasifier 5 is cooled at 17, at 18 the existing carbon monoxide is converted with water to carbon dioxide and hydrogen, at 19 becomes cooled further, at 20 carbon dioxide and hydrogen sulfide are washed out and then with the compressor 21 the hydrogen is fed back to the hydrogenating gasifier 11 via the regenerative preheater 12. The one in the steam generator 9 produced water vapor of approx. 180 bar and 540 C is first expanded in a turbine 24 and used to generate electricity. Part of the steam is taken from the turbine and passed through the process steam superheater 8 fed to the steam gasifier 5.

In Figure 1, the product gas emerging from the steam gasifier 5 is used to heat a cracking furnace 6, which is charged with a mixture of methane and water vapor and its product in the manner already described is fed into the hydrogenating gasifier via 18, 19, 20, 21 and 12. According to previous calculations is this circuit is particularly suitable for methane production, if up to 57% in the hydrogenating gasifier 11 the raw coal is gasified. Since in the cracking furnace there are approximately the same pressures on both sides and the both media are of similar composition, so that small leaks in the cracking furnace are of no importance, With this circuit, the cracking furnace 6 can be built with the least possible effort.

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Figure 2 shows a circuit similar to the rest of Figure 1, a cracking furnace 7, which from the hydrogenating Carburetor 11 exiting product gas is heated. This cracking furnace 7 is also made from a mixture of methane and water vapor charges and feeds its product into the product stream exiting the water vapor gasifier a. The calculations so far show that this circuit is particularly suitable for methane production, if in the hydrogenating gasifier 11 60% and more of the raw coal used are gasified. Also here is aut Both sides have the same pressure and two media that do not have to be absolutely sealed against each other,

In FIG. 3 there is both a cracking furnace 6, which is heated by the medium emerging from the steam gasifier 5, and a cracking furnace 7, which is heated by the product emerging from the hydrogenating gasifier 11. As in FIGS. 1 and 2, both cracking furnaces 6 and 7 are fed by a mixture of methane and water vapor. The product emerging from both cracking furnaces is also fed to the product stream emerging from the steam gasifier 5. According to the calculations made so far, this circuit is particularly suitable for the production of synthesis gas, which essentially consists of hydrogen and carbon monoxide. With this circuit, all methane generated in the two carburetors should be completely split. Therefore, a larger amount of heat is necessary for the cracking, which is expediently distributed over both cracking furnaces 6 and 7. In contrast to FIGS. 1 and 2, in FIG. 3 the carbon monoxide separated in the low-temperature gas separation 16 is not returned to the circuit but is released to the outside as a product together with part of the hydrogen.

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If you only want to produce hydrogen with this plant, you can of course use low-temperature gas separation 16 operate so that the carbon monoxide separated there again, as in Figures 1 and 2 in the Cycle is returned.

The following table gives a numerical example for each of the three figures, which refers to German hard coal (gas flame coal) with 6% water, 10% ash and
34% volatile matter.

figure 1 2 3 Reactor power in MW 30OO 3000 3OOO Carbon gasification rate
in the hydrogenating carburetor
in % 55 60 55 Amount of coal in t / h 860 984 360 Methane production in Nm / h 6180OO 7OOOOO - Synthesis gas production - - 7650OO

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Claims (2)

24.377.6 Go / Fe 05/31/1977 GHT Society for high temperature reactor technology mbH 5060 Bergisch Gladbach 1 Gasification of coal with nuclear energy Expectations ι \ J Plant for the production of methane or synthesis gas from carbonaceous substances with a nuclear-heated helium cycle; a first part of the carbon is converted into methane with hydrogen in a hydrogenating gasifier and a second part of the carbon is converted into synthesis gas with steam in a steam gasifier; At least part of the methane is converted into hydrogen with steam in a cracking furnace. This system has the following features: a) A methane cracking furnace is made from the Steam gasifier or product gas emerging from the hydrogenating gasifier heated. 2. Plant according to claim 1, in particular for generating synthesis gas, with the following features: a) A methane cracking furnace is used by the steam gasifier exiting product gas is heated, 909809/0010 b) another methane cracking furnace is released from the hydrogenating gasifier Produktyas heated. 909809/0010