DE2348477A1 - PROCESS FOR GASIFYING CARBON SUBSTANCES - Google Patents

Description

Palenlaimalt

Kar! A. Brose

Dipl.-Ing. D-8023 Munich - Pullach

1 / Bta- 9758 ⁱⁿ - ⁱ "* - ² ' ^I - ^Mdl8 - ^m0570 ' ⁷⁹³¹ Munich-Pullach, Sept. 26, 1973

OCCIDENTAL PETROLEUM CORPORATION, a company incorporated under the laws of the State of California, USA, 10889 Wilshire Boulevard, Los Angeles, « California 90 024, USA

Process for gasifying carbonaceous substances

The invention relates to a method for gasifying carbonaceous "materials by pyrolytic conversion of carbon- 'containing feed material to primarily gaseous products, it being an object of the invention to provide a method for pyrolytically converting such feed materials to primarily remote gas without causing
large amounts of hydrogen can be generated.

Long-distance gas is a fuel gas, which mainly consists of methane with a content of ethane and smaller contents of hydrocarbons of higher molecular weight. These hydrocarbons have a heat content per unit volume that is very high
is much higher than the heat content per unit volume of hydrogen.

The following table illustrates the differences in heat content based on a volume unit:

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calorific value

Calorific value of the hydrogen contained

Gas BTU / Ft ³ kcal / m ³ BTU / Ft ³ kcal / m ³

1013 9010 507 4510 1792 15950 597 5310 1614 14360 807 7190 H ₀ 325 2890 325 2890

Because the calorific value of hydrocarbons is based on a unit volume higher than that of hydrogen, fuel gases with a high content of hydrocarbons can pass through Pipelines, such as pipelines and gas pipelines, can be transported in a much more economical manner than hydrogen. In addition, hydrogen is only stored at considerable risk and can be used, and consequently the level of hydrogen in remote gas must be quite low in order to be sufficient Maintain safety factor. In summary, it can be said that hydrocarbon gases are used as fuels are considerably preferred over hydrogen.

The production of long-distance gas from carbonaceous material, such as coal, is becoming increasingly attractive, especially taking into account the fact that the ratio of natural gas reserves to production has decreased. the Conversion of carbonaceous materials into long-distance gas is also because of the enormous waste disposal problems that facing some areas, attractive.

The economics of converting carbonaceous materials such as coal in long-distance gas, however, has pronounced such a conversion using conventional methods rendered unattractive, and as a result, very little, if any, long-distance gas is carried through on an economic basis today Gasification of carbonaceous substances produced.

One of the problems with the economic transformation of

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Substances containing fuel in long-distance gas lies in the pronounced unstable nature of hydrocarbon generator gases at high temperatures. For example, 50 # of the decomposes during the Pyrolysis of coal as feed material in a first stage pyrolytic converter operating at 815 ° C, formed Ethans in 0.7 seconds. Higher molecular weight hydrocarbons decompose even faster.

The present invention provides a method for gasifying particulate carbonaceous materials in which such a particulate carbonaceous material is introduced into a first pyrolysis zone in a conveying gas stream and the material in this first pyrolysis zone is heated to a temperature and for a period of time, both of which be chosen so that gaseous pyrolysis products are obtained which contain at least 20 percent by volume of hydrocarbons containing from 1 to 4 carbon atoms, then discharged the gaseous pyrolysis products from the first pyrolysis zone and are cooled before any appreciable thermal decomposition of such products occurs, then the solids of these gaseous pyrolysis products are separated, then the separated solids in a second pyrolysis zone in a conveying gas stream entered and heated these solids in such a zone to a temperature and over a period of time are both chosen so that carbon monoxide and hydrogen are generated, the conveying gas at least partially is formed by recycled carbon monoxide and hydrogen, which is generated in the second pyrolysis zone became.

The present invention is thus characterized by the use of at least two pyrolysis zones in which carbonaceous Feed material is converted into gaseous products. In a first pyrolysis zone, a particulate carbonaceous feed material entrained in a conveying gas, a pyrolytic conversion subjected to temperature conditions which are appropriate

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are borrowed to at least a portion of the solids To convert feed material into gaseous products, and this is done with a residence time that depends on the temperature is related and is chosen such that the gaseous products experience minimal thermal decomposition, so that as Yield a high hydrocarbon gas is obtained. The residence time for the gaseous products in the first pyrolysis zone must be very short, and the emerging gaseous products are rapidly cooled to allow thermal decomposition Avoid gaseous hydrocarbons in hydrogen and other products. Those in the product of the first pyrolysis zone Solids contained are separated from the gaseous and liquid products and contained in a conveying gas in a second pyrolysis zone entered, where the solids in carbon monoxide, Nitrogen and animal or biochar (char) are converted by heating them to an appropriate temperature which is normally a temperature higher than the temperature of the first pyrolysis zone.

The second pyrolysis zone is preferably operated in such a way that the gaseous product is essentially a mixture of carbon monoxide and hydrogen and is therefore ideal to be recycled as a conveying gas for both stages of the pyrolysis will. The generator gas quantities of the second pyrolysis zone that exceed the quantities required for recirculation in the circuit can be brought together with the generator gases of the first pyrolysis zone, provided that the generator gases of the second Stage have been sufficiently cooled beforehand in order to avoid the cracking of the generator gases of the first stage. The solids of the second pyrolysis zone are separated from the liquid and gaseous products of the pyrolysis and are preferably used as Fuel used to generate heat for both pyrolysis zones. For this purpose, the solids are expediently made of the second pyrolysis zone in a furnace, in which some of these solids are burned in air to the temperature to increase the residue. The solids heated in this way are then fed into the pyrolysis zone.

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feeds to provide the heat required for the pyrolysis reactions.

In preferred embodiments of the invention, the liquid Products from both pyrolysis zones repeatedly circulated until the conversion of thermally convertible liquid Products in gaseous products is no longer possible. This means that the liquid products to exhaustion be circulated. Those liquids, such as benzene, which are extremely stable and not can easily be subjected to thermal decomposition in the pyrolysis zones are discharged from the system. To the Facilitating repeated recirculation of the liquid products for conversion into gaseous products becomes more expedient Way a phase separator is used to separate the liquid and gaseous products from each other.

Carbon monoxide and hydrogen generated in both pyrolysis zones are preferably converted to methane using conventional shift conversion and methanation techniques. Animal or biochar (char) and steam can be used to produce hydrogen, which is used in converting generator gases such as ethane, propane and ethylene into methane, thereby alleviating the problems associated with the high dew points of these heavier hydrocarbons avoid. The feed material is preferably pulverized to have a large surface area to volume ratio for its rapid heating in the first pyrolysis zone. If coal is used, the reaction temperature of the first stage of pyrolysis is preferably in the range of about 675 ° C to about 900 ⁰ C. Within this temperature range, and assuming a very small residence time of the particulate feed material, for example, a residence time in the range of about 0.01 seconds to about 3 seconds, a significant amount of hydrocarbon gases can be generated in the pyrolysis zone. If these hydrocarbon gases are cooled down quickly, it is not enough

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There is time for them to get into some greater degree To thermally decompose or split hydrogen and carbon.

For a mode of operation of the first pyrolysis zone with good efficiency consequently, the carbonaceous feedstock is exposed to conditions under which pyrolysis is extreme occurs rapidly, these conditions utilizing a small particle size, an extremely efficient heat transfer and a rapid removal of the gaseous hydrocarbon products from the pyrolysis zone. The initial one Cooling of all pyrolysis products of the first stage takes place immediately after their removal from the first pyrolysis zone to an extent sufficient to obtain, but should be, a high yield of hydrocarbon-free gases Cooling should not be such that tars condense from the generator gases on the solids produced and thereby the phase separator clog or shut down. In order to achieve heat transfer with an extremely high degree of efficiency, hot animal or vegetable charcoal, preferably in the manner described above, returned in the cycle, thereby in to have a direct heat transferring relationship with the feed material in the pyrolysis zones.

In the preferred embodiments, the present Invention a method for gasifying carbonaceous materials, in particular coal, created, which a pronounced has high efficiency. The gaseous products of the process have a high calorific value per unit volume on, and thus are the most known methods of producing gas which is not rich in hydrocarbons associated problems are avoided while at the same time lower capital costs and operating costs are achievable. The use of direct heat transfer from hot animal or biochar to other solids in the pyrolysis zones represents a simple process of high productivity, in which not only coking but at the same time non-coking

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Coal and carbonaceous waste can be processed.

The term "animal or biochar ¹¹ (char)" as used in the present specification refers to the solid products of the destructive distillation of a carbonaceous material in the absence of air or oxygen. If a carbonaceous material of any kind is heated sufficiently in the absence of air or oxygen, Some carbonaceous materials decompose completely into gaseous products (oxides of carbon, hydrogen and various hydrocarbons), while other carbonaceous materials decompose leaving a solid residue, which consists mainly of carbon and non-volatile residues of certain constituents of the starting material Solid residue is referred to in the present description as "animal or biochar ¹ * (char), unless it is a solid residue with a special carbon content iger materials that have special names. For example, "the" animal or vegetable ^{charcoal 11 obtained} as a result of the destructive distillation of coal is referred to as "coke * ¹ , while the solid residue from the destructive distillation of Wood and vegetable matter is called "charcoal" or "kiln coal".

In preferred embodiments of the present invention, the carbonaceous material used to feed the process is coal and the residue obtained as a solid referred to as coke.

In the following the invention is explained in more detail with reference to the single figure of the accompanying drawings, in which a Illustrates a schematic flow diagram of an exemplary embodiment of the method according to the present invention is.

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In general, it can be said that preferred embodiments of the process according to the invention two or more stages of the Use pyrolytic conversion of the carbonaceous feed. The first stage of pyrolytic conversion occurs in a temperature range of about 675 ° C to about 900 ° C and is carried out in a very short period of time, typically less than 3 seconds. The pyrolysis temperature and the residence time are adjusted to allow for the generation of hydrocarbons having from 1 to 4 carbon atoms to maximize. The feed material, which was previously pulverized is placed in a first stage pyrolysis reactor entered in a carrier gas, which mainly consists of hydrogen and carbon monoxide. Optionally, the feed material dried before pyrolysis. In the pyrolysis reactor of the first stage, condensation takes place at the same time. bare pyrolysis products, d. H. liquid products, cracked to produce even more producer gas. The one for pyrolysis in the reactor The heat required in the first stage is supplied in whole or in part by hot animal or vegetable charcoal, which occurs as a product of the overall process.

After pyrolysis, the solid and gaseous reaction products become initially cooled to approximately 540 ° G, which is a temperature which is sufficiently low to achieve the to minimize thermal decomposition of the desired gaseous hydrocarbons with 1 to 4 carbon atoms, which on the other hand is not so low that it leads to condensation of the condensable pyrolysis products. After this initial The solid products are cooled down from the gaseous ones Products are separated and introduced into a second stage pyrolysis reactor while the gaseous products are rapidly cooled to condense the liquid products and to avoid thermal decomposition. The pyrolysis reaction the second stage takes place at a higher temperature than the first stage, which is between about 760 ° and about 98O C or higher. Of course, higher temperatures lead to higher conversion speeds, but

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At this stage there are no concerns that any hydrocarbon containing products are cracked. The purpose of the second stage of pyrolysis is to make the remaining liquefiable To volatilize substances and convert them into hydrogen, carbon monoxide and gaseous hydrocarbons.

Part of that obtained from the products of the first stage condensed liquid ingredients will go along with the pesticides and hot animal or vegetable charcoal, which contains all or part of the thermal energy required for pyrolysis supplies, entered into the pyrolysis reactor of the second stage. The products of the reactor of the second stage turn into gaseous and solid components cracked. The gaseous components, mainly hydrogen and carbon monoxide with some condensable compounds, can act as a carrier gas in both Pyrolysis reactors are used. The gaseous products of the second stage pyrolysis that are not used as conveying gas are, and the condensable components contained therein are cooled and with the liquid and the gaseous Products of the pyrolysis of the first stage are brought together for further processing. Part of the solids from the The second stage pyrolysis reactor can be air burned in a furnace to produce the warm animal or vegetable charcoal that can be used to provide thermal energy for both To provide stages of pyrolytic conversion. Alternatively, the animal or vegetable charcoal can be heated by an electric furnace or a gas furnace can be heated via heat exchanger devices. The hot animal or vegetable charcoal can also be used to generate hydrogen, which in a methanation reaction is used to produce larger quantities of methane. The rest of the animal or vegetable charcoal from the pyrolysis reactor the second stage is discharged as a solid product.

The combined liquid and gaseous products from both stages of the pyrolytic conversion are separated in a JP phase separator separated into separate liquid and gaseous products.

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The liquid products are stored in both pyrolysis reactors until they are exhausted circulates, with thermally stable liquid products such as benzene, be discharged via a fractionator. The gaseous products of the phase separator can be further processed, to generate the desired remote gas. This further processing includes a hydrogenation of the unsaturated hydrocarbons, a shift conversion to generate hydrogen for reaction with carbon monoxide for methanation, a discharge of impurities and methanation. One method that has this general flow is in the drawing illustrated.

In the method illustrated in the drawing, powdered carbonaceous material, such as coal, is introduced into a coal container 12 as a stream 10. The coal can optionally be completely or partially dried to have a certain moisture content to generate steam, which can react with the coal during pyrolysis to generate carbon monoxide and hydrogen, which are converted and methanized at a later point in time. The coal is preferably partially dried in order to avoid unnecessary expenditure of thermal energy for heating and evaporation of water in the pyrolysis zone. The coal is pulverized to present a large surface area to volume ratio to thereby achieve rapid heating of the coal in the pyrolysis reaction. At least 80 4> of the ground coal has a particle size of 60 mesh (Tyler standard sieve), and preferably at least 80 4> of the coal has a particle size of 100 mesh with the remainder having a particle size of 60 mesh.

Particulate carbon is removed from the canister 12, peeled off in a stream 14, for example by means of gravity "The rate and amount of carbon flow in the stream. 14 is controlled via a valve 16. A rotary valve or a star valve meet the tightness requirements

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des Verrtiles 16. The working pressure of the pyrolysis is between approximately 1 - 7.8 atmospheres, so that the valve 16 acts as a pressure lock must act between its upstream and downstream sides * The coal in stream 14 is preferred free of oxygen · This can be achieved by leaving the charcoal in the container 12 with nitrogen, carbon dioxide or purged in the recirculated gas. A Stream 18 aligns a carrier gas, which is from in the circuit the second stage of the pyrolytic Ifa conversion described below, mainly carbon monoxide and hydrogen, to the coal stream. The circulating conveying or carrier gas and the particulate Coal feeds meet as a stream 20 to be introduced together into a first stage pyrolysis reactor 22 to become. At least within the reactor 22, the flow of carrier gas and coal feed is subject to high turbulence, to achieve good mixing and heat transfer. Thus the Reynolds number of the current is within of the reactor 22 at least over 2,000, preferably over 2,500, in order to have sufficient turbulence to those mentioned above Purposes. The speed of the carrier gas must in any case be comparatively high to the required to ensure rapid transport of the pyrolysis products through the pyrolysis reactor of the first stage, so that the necessary turbulent flow conditions are easily achievable. The feed to the pyrolysis reactor closes the recirculated liquid through a stream 23 and is hot in the circuit returned animal or vegetable charcoal from a stream 24, the latter also being entrained in the carrier gas. the Recirculated liquid is injected into the pyrolysis reactor, for example through mouthpieces or nozzles, and it is preferred to atomize the liquid into a mist for efficient heat transfer to the liquid and it to achieve subsequent cracking. The liquid is entrained in the reactor by the carrier gas stream. Hence the Residence time of the liquid in the reactor is also pronounced short, less than 3 seconds, and preferably between

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about 0.1 and about 1 second. The ones for pyrolysis in the The pyrolysis reactor of the first stage required heat is preferably provided by the hot animal or vegetable charcoal from the Stream 24 supplied as mentioned above. This hot animal or vegetable charcoal is also particulate and is subject also an extremely turbulent flow in the pyrolysis reactor 22, so that the heat transfer between the Animal or vegetable charcoal, the charcoal and the liquid returned in the cycle are carried out with an extremely high degree of efficiency.

Optionally, a stream 21 of steam can also be introduced into the first reactor 22 together with the coal feed, the carrier gas, the liquid recirculated and the animal or vegetable charcoal. Such steam injection appears to have little effect on the relative proportions of hydrocarbons to hydrogen and carbon dioxide produced in the first reactor 22. However, steam injection increases the amount of fuel gas produced and calculated in methane equivalents by up to $ 45 · The methane equivalent is based on the amount of methane that can be produced from a gas of a certain composition. For example, a gas containing carbon monoxide and hydrogen, as well as methane, can be converted into a methane-rich gas by methanation in the manner described below. The steam can be injected at any temperature above 10O ⁰ C. If steam is injected into the first reactor 22 at a temperature below the pyrolysis temperature, this consumes heat energy in the reactor and consequently the amount and / or the temperature of the animal or biochar must be increased to the pyrolysis temperature in the range between about 675 ° 0 to about 900 ° C. If steam is injected into the reactor 22 at temperatures above the pyrolysis temperature, this gives off thermal energy. However, since the reaction between the steam and the coal takes place endothermic, the amount and / or temperature of the animal or vegetable charcoal must nevertheless be increased to the pyrolysis temperature within the first

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To hold reactor 22. Steam can be in an amount up to approximately 50 percent by weight of the coal introduced into the reactor 22 can be injected, but the amount of steam injected is preferably below about 25 percent by weight of the coal charge.

The weight ratio of the solids charged to reactor 22 (in the exemplary embodiment coke and coal) to the carrier gas is between approximately 3 * 1 "to approximately 600: 1 and preferably between about 50: 1 to about 100: 1. The weight ratio of coke to coal is between approximately 1: to 18: 1 and depends on the heat capacities of the coke and the Coal, the temperature of the coke and the desired pyrolysis temperature.

As mentioned, the temperature in the pyrolysis reactor 22 becomes within the range of about 675 ° C to about 900 ° C held. This temperature range is chosen because the desired gaseous hydrocarbons, such as ethylene, methane and ethane, generated during pyrolysis become extremely fast at higher temperatures, even after brief exposure to such temperatures, decompose, the rate of decomposition being extremely temperature-dependent. At temperatures above the specified Even with an extremely short residence time, there is sufficient thermal decomposition in the area to be disadvantageous and considerable affect the final yield of gaseous hydrocarbons obtained.

The residence time of the material in the first stage reactor 22 will be less than 3 seconds, preferably between about 0.1 and about 1 second, held. The thermal decomposition of the pyrolysis products is also a strict and direct function of Time at pyrolysis temperatures, so that in order to obtain an acceptable yield of pyrolysis products, the shorter the residence time in the reactor, the shorter the yield of the desired hydrocarbons in these products.

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The product of the first stage leaving the pyrolysis factory 22 leaves this as a stream 25 which contains gaseous and solid pyrolysis products. The gaseous one Product is mainly a mixture of hydrogen, carbon monoxide, carbon dioxide and gaseous hydrocarbons with from 1 to 4 carbon atoms. At least 20 percent by volume and preferably at least about 30 percent by volume of the gaseous product consists of these gaseous hydrocarbons. This stream passes through a heat exchanger 26 to a separator 27 in order to separate the solid from the gaseous products separate. The separator 27 can be designed in the form of a cyclone separator.

The heat exchanger in the heat exchanger 27 can be achieved by water injection, Gas injection or by adding solids. It is important here to use the products of the first stage the pyrolysis to cool quickly, for example by quenching, before any appreciable amount of thermal decomposition takes place, cooling to a temperature of approximately 540 ° C is sufficient. The cooling of the pyrolysis products of the first Stage in stream 25 to a temperature which is well below 540 ° C, leads to the condensation of tars from the gaseous Components that clog the separator 27 or have been taken out of service.

From the separator 27 the gaseous product exits as a stream 28 and enters a heat exchanger 30 for cooling, where the gaseous product continues as quickly as possible to a temperature of about 175 ° 0 or less, preferably to a temperature that is not is above 40 ⁰ O, is cooled in order to avoid the thermal decomposition of the desired gaseous hydrocarbons. Condensable liquid products condense out of the gaseous products as a result of this cooling and are entrained in the gaseous stream to exit the heat exchanger 30 as a stream 32.

The solid st off he certificates leave the separator 27 through a

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Stream 34, together with a carrier gas as stream 36 in a Pyrolysis reactor 38 of the second stage with pneumatic conveyance to be introduced. The carrier gas, which in turn mainly consists of carbon monoxide and nitrogen, enters from a branch line 40 of a stream 42, which simultaneously promotes hot coke to the branch line. The carrier gas and the hot coke come from the downstream side of the second stage pyrolysis reactor 38 and a furnace 18 for hot coke, the stream 42 simultaneously the branch stream 24 of carrier gas and hot coke for the pyrolysis reactor of the first Level supplied.

The second stage pyrolysis reactor also has a recycled liquid feed which enters the reactor through stream 44. Stream 44 is a branch of stream 23. A turbulent stream of hot coke in the carrier gas also enters the second stage pyrolysis reactor directly through stream 46 which branches off from stream 42. Optionally, a stream 47 of steam can be injected into the second reactor. The steam can be injected at any temperature above 10O ⁰ G. As was also the case with the steam injection in the first reactor 22, the temperature and / or amount of coke must be adjusted to balance the steam supply in order to thereby maintain the required pyrolysis temperature in the second reactor 38. The steam is injected into the second reactor 38 in amounts up to about 50 percent by weight of the solids and coke feed to the second reactor.

In the second stage, the same intimate mixing as those subjected to pyrolysis are used to aid effective pyrolysis Materials and the atomization of the liquid as achieved in the first pyrolysis zone.

While the carrier gas in the embodiment described consists of pyrolysis products recycled in the cycle, "other

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on the other hand, the carrier gas can be any gas which is essentially free of free oxygen and which does not adversely affect the feed material or the pyrolysis products. Suitable carrier gases include hydrogen, carbon monoxide, carbon dioxide, nitrogen, helium and similar inert gases. Preferably, however, "the carrier gas consists of the recirculated gaseous product of the pyrolysis of the second stage and" consists mainly of hydrogen and carbon monoxide. A typical composition (in percent by volume) of the generator gas of the second pyrolysis is as follows: hydrogen 44 fo _f carbon monoxide 35 i ° i methane 20 $ and smaller amounts of higher order hydrocarbons, nitrogen, carbon dioxide and the like.

In the second pyrolysis, the weight ratio of the pesticides (solids produced and coke) to the carrier gas is between about 3 J 1 and about 600: 1, preferably between about 50: 1 and about 100: 1. The ratio of coke to solids produced is between about 1: 1 to about 18: 1. The ratio is determined by the heat capacities of the coke and solid products, the coke temperature and the desired Pyrolysis temperature determined.

The gaseous reaction products of the pyrolysis reactor of the second As mentioned above, stages consist mainly of carbon monoxide and nitrogen. The yields of these gases are increased, when steam is injected into the second reactor 38. Of the Steam apparently reacts with the carbon in the coke. The liquid returned in the circuit is converted into lighter thermally stable compounds and gaseous products. The temperature of the pyrolytic transformation in the second stage reactor is between about 760 ° C and about 980 ° C or higher, preferably between 790 ° G and 955 ° C. This temperature range was chosen to so that the pyrolysis takes place quickly. Excessive temperatures should, however, be avoided in order to reduce coke consumption and agglomeration and / or to minimize coke slagging and around

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also to minimize the consumption of thermal energy. The pyrolysis temperature and the residence time of the second pyrolysis stage are set in such a way that all pyrolyzable substances are pyrolyzed, and that a gaseous pyrolysis product is obtained which is at least 80 percent by volume, preferably 90 percent by volume, contains carbon monoxide and hydrogen.

The pyrolysis reactor of the second stage complements the pyrolysis reactor of the first stage in the production of components of the Long-distance gas, since considerable amounts of the hydrogen and carbon monoxide produced here are in a shift converter and methanator converted into methane.

The pressure at which both pyrolysis reactions take place is between about 1 to 7.8 atmospheres. The upper pressure limit was chosen to avoid expensive and complicated plant equipment to avoid, which would be necessary at pressures above 7.8 atmospheres.

The gaseous and solid products leave the second reactor 38 through a stream 48 and enter a solids separator 50 where the solids are discharged as a stream 52 and the gaseous products as a stream 54 will. The separator can be designed in the form of a cyclone separator. Some of the gaseous products of the Stream 54 pass into a heat exchanger 55, where they are cooled in order to condense out the condensable products and to allow the-gaseous and liquid products the second stage are brought together with those of the first pyrolysis stage at sufficiently low temperatures, to prevent thermal decomposition of the gaseous products of the first stage. Leave the cooled products the heat exchanger 55 as stream 56, which is combined with the stream 32 from the heat exchanger 30. A recycled one Gas stream 57, which consists primarily of hydrogen and carbon monoxide, but some condensable products contains, is used as a carrier gas in the above

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described way in the pyrolysis reactors 22 and 38 branched off as stream 54 in a controlled by valves 58 amount.

The recirculated gas stream 57 supplies the streams 42 and 18. As described above, the stream 18 promotes coal from stream I4 and stream 42 conveys hot coke into both Pyrolysis stages. The flow 42 ensures through its branch 40 the conveyance of the solid products from the separator 27. It should be emphasized that stream 57 is very hot; H. essentially at the pyrolysis temperature in the reactor of the second stage, and that the thermal energy is effectively in this recirculated gas stream preserved.

The solids exiting separator 50 through stream 52 are placed in producer coke and recycled coke divided as streams 60 and 62, respectively. Part of the heat contained in the producer coke can be transferred through conventional heat exchanger devices (not shown) can be recovered. There are many uses for the producer coke. For example The producer coke can be used as fuel for power plants, it can be used as raw material for synthetic coke for metallurgical Applications or used for the production of activated carbon and furthermore it can be used as raw material for synthetic Fuel gas production can be used in the manner described below. The ratio of recycled Coke to producer coke can be controlled by valves 64.

The recirculated coke from stream 62 and air through stream 66 are mixed together and enter coke oven 68 as a combined stream 70. A controlled combustion of part of the coke takes place in the coke oven in order to supply the heat for the rest of the coke. The controlled combustion is carried out by limiting the amount of air in the furnace to ensure a low-oxygen atmosphere below the stoichiometric ratio. Of the

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Heated coke and the products of combustion leave the coke oven as stream 71 and are separated from one another in a separator 72 separated, with the gases entering the separator as stream 74 and the high temperature coke entering the separator as stream 76 leaves to be introduced into the recirculated gas stream 57 to form the streams 42, 46, 40 and 24. In the high temperature coke contains sufficient thermal energy to generate the heat required for pyrolysis to be delivered in both reactors.

Again, it is of particular importance that the coke from the coke oven 68, which is used as a heat source in the pyrolysis reactors 22 and 38 is used, from which particulate coal supplied from the coal container 12 is obtained, and hence a has an extremely small particle size · The small particle size of the coke ensures effective direct heat transfer with high efficiency on the other solids introduced into the pyrolysis reactors.

A portion of the hot coke leaving the separator 72 as stream 76 is fed into a synthesis vessel 116 in a branch stream II4 Flow controlled by a valve II8 * Very hotter Steam is also introduced into synthesis vessel 116. In the synthesis vessel, the coke is brought to a temperature in the range from about 815 ° C to about 1370 ° G with optional Reaction with oxygen and heated with the steam at pressures in the range of about 21 atmospheres to about 42 atmospheres contacted to produce a synthesis gas stream 120. The synthesis gas stream mainly consists of carbon monoxide, carbon dioxide and hydrogen and is fed into a gas compressor 122 and then at a Pressure in a range between 4.4 to 11 atmospheres in the Heat exchanger 92 introduced. The synthesis gas stream is then mixed with a gas stream 82 in the manner described below treated.

The cooled gaseous and liquid products of the first

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Pyrolysis reactor 22 are in the manner described with a Part of the similarly cooled gaseous and liquid products of the second pyrolysis reactor 38 mixed to be used as Combined stream 32 to enter a phase separator 78, from which the liquid fractions as stream 80 and the gaseous Shares are discharged as stream 82. The liquid fractions enter a liquid fractionator 84 in which the thermally stable products, such as benzene, separated from the thermally unstable products and used as a generator liquid in the stream 86 are removed. The thermally unstable liquid products are removed from the fractionator 84 discharged as stream 88 for recirculation. Stream 88 supplies branch streams 23 and 44 to the pyrolysis reactor 22 of the first stage or the pyrolysis reactor 38 of the second stage with liquid components.

After the liquid has been separated from the gas, the gaseous products of the pyrolysis are treated further. For the most part, the pressure at which this further treatment is carried out is between about 4.4 atmospheres and about 11 atmospheres. It may thus be necessary to increase the pressure of the gases in stream 82 and a compressor 89 is used for this purpose. If such a pressure increase is required, the stream 82 is ^{cooled to a temperature of between about 27 °} C. to about 50 ^° C. prior to the pressure increase in order to avoid damaging the compressor. The compressor 89 stream exiting 82 is then brought to a temperature of about 315 ⁰ C to about 510 ° C in the heat exchanger 92 where it is mixed with the synthesis gas stream 120 from the compressor 122 and at the pressure of about 4.4 to 11 atmospheres are introduced into a hydrogenation reactor 94 at the outlets of the compressors 122, 89.

In the hydrogenation reactor, the gases are passed through a hydrogenation catalyst, such as a cobalt molybdate catalyst. Sator, passed to the unsaturated hydrocarbons, such as propylene, ethylene and butylene, to their corresponding

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corresponding saturated forms, namely propane, ethane and butane hydrogenate. The hydrogen generated during the pyrolysis and entering the hydrogenation reactor 94 in stream 82 is sufficient to to carry out this saturation.

The gases flow from the hydrogenation reactor 94 to a slide valve reactor. tor or rearrangement reactor 96, which is also within the temperature range between 315 C to 510 C and in the Pressure range between 4 »4 to 11 atmospheres works which were previously made. The rearrangement or sliding wall— development is well known and is represented in the following way:

catalyst
GO + H ₂ O ^ z ^: CO ₂ + H ₂

A common rearrangement catalyst, such as chromium- activated iron oxide, can be used in this process step will.

After the rearrangement reaction, the gases are ^{cooled to a temperature between 93 °} C. and 150 ^° C. in order to remove impurities. The pressure of the stream remains the same and the cooling is carried out in a heat exchanger 98. Sulfur sulfide and carbon dioxide are removed from the gas stream in conventional separators 100 and 102, respectively, and discharged from the system as streams 104 and 106, respectively.

After sulfur sulfide and carbon dioxide have been removed, the gas stream is further cooled ^{to a temperature between approximately 27 °} C. and approximately 50 ^{° C. in a heat exchanger 108.} The cooled gas is then introduced into a heavy hydrocarbon adsorber 110 to remove the hydrocarbon products having 5 or more carbon atoms. The adsorption is carried out by activated carbon or similar adsorbents.

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After removing the C _c and higher hydrocarbons from the gas stream, the latter is passed through a heat exchanger 112, where the stream is reheated to a temperature of between about 260 ° C. to about 480 ° G and then passed into a reaction vessel 128. The pressure of the stream during this final heat exchange is still between about 4.4 and about 11 atmospheres.

Takes place under these conditions in terms of pressure and temperature a methanation reaction in the reactor vessel 128 to convert hydrogen and carbon monoxide into methane and steam in the presence an appropriate nickel catalyst such as Raney nickel.

The reaction products in the reactor vessel 128, namely mainly Methane and other components pass through the vessel and exit as stream 134. Stream 134 is opened between about 27 ° 0 to about 50 ° C in a heat exchanger 136 cooled and then in a compressor 138 on Pipeline pressure compressed, which is between about 62 and 76 atmospheres. After this pressure increase, water becomes in one Dehydrator I40 removed from stream 134. That the dehydrator 140 leaving gas is a remote gas.

The long-distance gas generated by the method according to the invention is equivalent to and exchangeable with natural gas and can be used as a replacement or to supplement natural gas using the existing distribution systems for this. The gas can be pumped at pressures of 69 atmospheres or greater. It has a calorific value of about 8000 to 98OO kcal / Nm ^. The gas consists essentially of methane (70 percent by volume or more) and smaller amounts of Cp, G ^, G, G, - and Gg alkanes, alkenes and alkynes. The remote gas may contain between about 0 to about 25 volume percent hydrogen, contains but preferably less than 5 fo hydrogen. The gas contains no more than 0.1 percent by volume of carbon monoxide and no more than 0.1 percent by volume of sulfur compounds, such as sulfur water

409816/0351

substance and sulfur dioxide. The gas can contain up to 5 percent by volume of inert gases such as helium, nitrogen, argon and carbon dioxide, but not more than 3 percent by volume of carbon dioxide. The gas can be dried by conventional means to keep the moisture content within acceptable standards, for example 0.09 kg / Nm. The specific gravity of the gas is between about 0.5 and 0.7. The dew point of the hydrocarbon
10 ° C.

hydrogen at 69 atmospheres is between -7 ⁰ C and

A typical long-distance gas thus has a calorific value of about 8898 keal / NnH and a specific weight of about 0.58. The volume-based composition is 95 i ° methane, 3.7 <$> ethane, 1,3 i ° nitrogen with lesser amounts of higher hydrocarbons, water, carbon dioxide, carbon monoxide, hydrogen and other gases.

In the following the invention is explained in more detail by means of examples.

A bituminous coal is partially dried and turned into solid Particles pulverized. The particles are classified to have a particle size of 200 mesh (U.S. Bureau of Standards, standard sieve series 1919). The composition of coal is the following:

Ingredient weight percent

C 73.60

H 4.85

0 7.22

N 1.60

S 1.10

Ash 11.63

The partially dried and pulverized coal is then put into introduced a first pyrolysis reactor operating at one pressure

409818/0351

- · 24 -

of 2 atmospheres "is operated. Hotter returned in the circuit. lead coke is also introduced into the reactor. The temperature of the coke is 955 ° G, and the ratio of particulate Coke to particulate coal as fed into the reactor is adjusted so that the System temperature at the exit of the reactor is 790 ° C.

The solids are blown through the first pyrolysis reactor at high speed using recycled generator gas as the carrier at high speed so that the residence time in the reactor is about 0.1 seconds. The reaction products leaving the reactor pass through a cyclone separator to recover the solids. The gases are then quickly cooled to a temperature of about 38 ^{° C.} A quantity of liquid is also obtained in this process. The yields produced are as follows:

Product breakdown by weight

Gas 27.2

Liquids 10.3

Coke 62.0

Water 0.5

Gas composition by volume (HpS and NH -, - free)

2 21.4 GH ₄ 23.2 C ₂ H ₆ 5.1 ^C 2 ^H 4 14.3 GO 21.1 CO ₂ 6.4 C, and higher coals substances 8.5

The coke and the liquid are then treated with additional

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chem hot recirculated coke in a second pyrolysis reactor fed, where they are heated to a temperature of 870 ° G. In this second reactor, the Dwell time 1.0 seconds. The yields achieved are as follows:

Product breakdown by weight

Gas 13.1

Liquid 4.2

Coke '82.7

Gas composition by volume (H ₂ S and NHv-free)

H ₂ 73.5

CO 26.5

These results indicate that the present invention is the most pronounced efficient pyrolysis of carbonaceous feed material to produce gaseous pyrolysis products, which are rich in hydrocarbons and comparatively poor of hydrogen are made possible and extremely useful to convert this composition into remote gas. Because of the extremely simple reactions and the process of heat transfer used with an extremely high degree of efficiency, which can be used in the context of the present invention, the pyrolysis reactions are economical and conditional No complicated and expensive reactors or associated plant components The carbonaceous feed material itself can provide the energy for the pyrolytic conversion of the feed supply, which is expediently done by selectively burning part of the producer coke in a coke oven takes place to generate a mass of hot coke for recycle as a heat source for the pyrolysis reactors. That Coke product can also provide the amount of heat required in a synthesis vessel in which coke and steam react be brought to a bypass stream of synthesis gas

409816/0351

which contains carbon monoxide, carbon dioxide and hydrogen. It can thus be effectively removed from the sliding or rearrangement reaction between carbon monoxide and water use be made to produce carbon dioxide and hydrogen, this hydrogen being the hydrogen from the pyrolytic Conversion of the second stage and of a syngas sidestream can replace to produce with carbon monoxide of methane to react and to pyrolysis with components of higher molecular weight of the gaseous product react to convert these components into methane.

As an example of the economics of the present invention, it is possible to consider the production of G-as from a coal which has a calorific value of 1372 kcal / kg and contains 50% hydrogen. Assuming that the total hydrogen is extracted by pyrolysis as molecular hydrogen, the gas yield would be about 535 m ^ per ton of coal, with approximately 25.6 <? Were recovered o originally contained in the coal energy in the gas. This energy yield should be viewed in contrast to the case in which the hydrogen in the coal is extracted in the form of ethylene. The gas yield would then be only 268 m per ton of coal, but in this case the energy recovered in the gas is $ 63.5> the energy originally contained in the coal. The gas of the first pyrolysis stage of the process according to the invention normally has the following composition:

Volume percent

H ₂ 13-22

CO 30-33

CO ₂ 13-19

CH 16-18

C ₂ H ₆ 0.5-25

C ₂ H ₄ . 8-12

C ₂ H ₂ 0-1

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C Hg 0-0.5

C ₃ H ₆ 0.5-3.5

O ₃ H ₄ 0.2-0.4

C. Hydrocarbons 0.1-0.4

Benzene 0.7-0.8

Toluene 0.2-0.4

It should be noted that the accompanying drawing is only is schematic, parts such as pumps, blowers, fans and the like not being shown for the sake of clarity.

The carbonaceous feedstocks used in the present invention Methods that can be used include coal such as anthracite coal, bituminous coal, sub-bituminous Coal, lignite and peat, with preferred feed coals being the bituminous and sub-bituminous coals represent, and wherein the process works even with the difficult to gasify agglomerating bituminous coals, further Urban waste or waste and industrial waste, such as tree bark, rubber scrap, rubber tires, waste from sugar refiners, Sawdust, corn on the cob, rice hulls, animal substances from slaughterhouses and used petroleum products or at the Waste generated by the petroleum industry. The feed material should be in the form of relatively small particles, preferably about 200 mesh or smaller, in the manner explained above, to allow rapid heat transfer in the pyrolysis reactors with optimal pyrolytic conversion of the feed material into the desired products.

All of those mentioned in the description and in the drawings recognizable technical details are important for the invention.

409816/035

Claims (10)

Claims 1. Process for gasifying particulate carbonaceous Substances, characterized in that the particulate carbonaceous substances in a first pyrolysis zone entered in a conveying gas stream and in the first pyrolysis zone are heated to a temperature and over a period of time, both of which are chosen such that gaseous Pyrolysis products are obtained which contain at least 20 percent by volume of hydrocarbons with from 1 to 4 Carbon atoms contain that the gaseous pyrolysis products are withdrawn from the first pyrolysis zone before any noticeable thermal decomposition of these products takes place, as do the pesticides from the gaseous pyrolysis products be separated so that the separated solids are entered in a second pyrolysis zone in a conveying gas stream and heated in this zone to a temperature and for a period of time both chosen such that Carbon monoxide and hydrogen are generated, the conveying gas being at least partially recirculated Carbon monoxide and hydrogen gas is formed, which in the second pyrolysis zone was generated. 2. The method according to claim 1, characterized in that the temperature in the first pyrolysis zone is between about 675 ° and about 900 ° C and the residence time of the carbonaceous materials in the first pyrolysis zone is kept below 3 seconds will. 3. The method according to claim 1 or 2, characterized in that the heat for the reactions in the pyrolysis zones at least partly by introducing hot particulate animal or vegetable charcoal, coke or coke products into each of these zones is delivered. 4. The method according to claim 3, characterized in that the hot particulate animal or vegetable charcoal, coke or 409816/036 1 Coking products from the solids produced from the second Pyrolysis zone can be obtained. 5. Procedure according to. Claim. 4, characterized in that at least part of the solids produced in the second pyrolysis zone is fed into a furnace, where part of it is reduced to oxygen The atmosphere is burned in order to raise the temperature of the rest of the part, thus avoiding the hot animal or atmosphere To form biochar, coke or coking products. 6. The method according to one or more of the preceding claims, characterized in that parts of the carbon monoxide and hydrogen produced in the pyrolysis zones are combined in Methane can be converted. 7. The method according to one or more of the preceding claims, characterized in that a portion of the solids generated in one of the pyrolysis zones reacts with steam is brought to generate hydrogen, and that then the hydrogen with that in the second pyrolysis zone carbon monoxide produced is reacted to produce methane. 8. The method according to one or more of the preceding claims, characterized in that some of the gaseous products of the second pyrolysis are cooled to a temperature which is such that the subsequent merging with the gaseous products of the first pyrolysis does not leads to any noticeable thermal decomposition thereof, and that after cooling, this merging is carried out. 9 · The method according to one or more of the preceding claims, characterized in that the gaseous and the pyrolysis products of the first Py- ' rolysis zone initially cooled to a temperature high enough to condense condensation. 409816/0351 Avoidable pyrolysis products, which, however, is on the other hand sufficiently low to increase the rate of thermal Significantly reduce the decomposition of the gaseous products, so that the solids are then separated from the gaseous products and that finally the gaseous products are cooled to cause thermal decomposition of the same to end. 10. The method according to one or more of the preceding claims, characterized in that the condensable products of pyrolysis are condensed, then from the gaseous ones Products are separated and returned to one of the pyrolysis zones in the cycle. 40981 6/036 1