Process and Plant for Refining Raw Materials Containing Organic

Constituents

This invention relates to a process and a plant for refining raw materials containing organic constituents, such as raw materials containing oil and/or bitumen, in particular oil or tar sand or oil shale.

In view of an increasing shortage of petroleum deposits, the economic exploita- tion of raw materials containing organic constituents, such as oil or tar sands or oil shale, has become of greater interest. Oil or tar sands are mixtures of clay, sand, water and hydrocarbons. The latter can have different compositions and range from bitumen to normal crude oil. The hydrocarbon content in the sands is between about 1 and 18%. The economic efficiency of an exploitation increases with the hydrocarbon content. Oil or tar sands can be recovered by surface mining. When extracting them from deeper soil layers, an initial processing of the oil or tar sand already is effected in situ. Steam is introduced into the deposit, in order to liquefy the hydrocarbons. Therefore, this kind of oil recovery requires very much water, which in addition cannot be discharged quite free from oil.

Oil shales are rocks which contain bitumen or low-volatility oils. The content of organic matter (kerogen) lies between about 10 and 30%. Oil shales are no shales in a petrographic sense, but layered, not schistous, sedimentary rocks. The recovery of hydrocarbons, such as oil from oil shale, traditionally is effected by mining and subsequent pyrolysis (carbonization at 500 ⁰ C). Alternatively, there is also used the subsurface recovery (in situ) by pressing a steam-air mixture into the rock previously loosened by blasting and ignition of a flame front, which expels the hydrocarbons such as oil.

The previous recovery of hydrocarbons, such as crude oil from oil or tar sands or oil shale thus is relatively cost-intensive. With rising oil prices, the recovery of hydrocarbons, such as crude oil, from oil or tar sands and oil shale becomes increasingly interesting in economic terms. An essential problem in the present recovery of hydrocarbons, such as crude oil, from oil or tar sands and oil shales is the necessary high consumption of water and the emission of waste waters containing residual oil.

From U.S. patent 4,507,195 a process for coking contaminated oil shale or tar sand oil on solids distilled in retorts is known. Here, the hydrocarbonaceous solids are mixed with a hot heat transfer material, in order to raise the temperature of the solids to a temperature suitable for the pyrolysis of the hydrocarbons. The mixture is maintained in a pyrolysis zone, until a sufficient amount of hydrocarbon vapors is released. In the pyrolysis zone, a stripping gas is passed through the mixture, in order to lower the dew point of the resulting hydrocarbon vapors and entrain the fine particles. Accordingly, a mixture of contaminated hydrocarbon vapors, stripping gas and entrained fine particles is obtained from the pyrolysis zone. From the contaminated hydrocarbon vapors, a heavy fraction is separated and thermally cracked in a fluidized bed consisting of fine particles, whereby the impurities together with coke are deposited on the fine particles in the fluidized bed. The product oil vapors are withdrawn from the coking container. As heat transfer material, recirculated pyrolyzed oil shale or tar sand is used, which was guided through a combustion zone, in order to burn carbon residues and provide the heat for the pyrolysis of the raw material. Since there is no pressure seal between the combustion zone and the pyrolysis furnace, the oxidizing atmosphere of the combustion zone can enter the pyrolysis furnace and impair the quality of the oil vapor. Thermal cracking in the coking container also consumes much energy and therefore is expensive.

From EP 1 015 527 B1 , there is also known a process for the thermal treatment of feedstock containing volatile, combustible constituents, wherein the feedstock is mixed with hot granular solids from a collecting bin in a pyrolysis reactor, in which relatively high temperatures exist. This should lead to cracking reactions in the gases and vapors in the reactor.

Beside the thermal cracking used in the above-mentioned processes, catalytic cracking processes are known. In Fluid Catalytic Cracking (FCC), the heavy distillate of a refinery is decomposed to gases, liquefied gases and gasolines, preferably to long-chain n-alkanes and i-alkanes. Cracking generally is effected at temperatures between 450 and 550 ⁰ C and a reactor pressure of 1.4 bar by means of an alumosilicate-based zeolite catalyst. FCC crackers are described for instance in US 7,135,151 B1 , US 2005/0118076 A1 or US 2006/0231459 A1. An exemplary catalyst is disclosed in WO 2006/131506 A1. As further possibili- ties for the further treatment of hydrocarbon fractions hydrotreatment and hydro- cracking are mentioned by way of example.

In a refining plant for raw materials containing organic constituents, such as oil- containing raw materials, the latter, e.g. oil sand, can first be supplied to drying, then to preheating, then to an expulsion stage, and finally the residual solids can be supplied to a combustion. Drying is effected at e.g. about 80 to 120 ⁰ C ₁ preheating at e.g. about 150 to 300 ⁰ C. The expulsion stage operates at e.g. about 300 to 1000 ⁰ C. In all three stages, hydrocarbonaceous vapors (oil vapors) are released, which are supplied to a processing stage (e.g. by hydrocracking, coking and/or hydrotreating) and are further processed there. The residual solids of the expulsion stage can be introduced into a combustion stage and be burnt at e.g. about 1000 to 1200 ⁰ C. The solid combustion products can be utilized, for instance, to heat up the expulsion stage. In most cases, the individual stages (drying, preheating, expulsion and combustion) can be operated as fluidized beds. As fluidizing gas, light hydrocarbons, inert gas (such as nitro-

gen), oxygen-containing gases, CO2-containing gases or also waste gases of the combustion stage can be used. For the processing stage, hydrogen is also required beside the oil vapors (e.g. for hydrocracking).

The qualities of oil-containing raw materials often are very different and fluctuating, so that in some cases only very little oil vapors are released in the expulsion stage or in a preceding stage and that bitumen of the oil-containing raw materials tends to liquefying or coking instead of evaporating. The yield of desired oil vapors thereby is reduced and often more energy is produced in the combustion stage, which is not desired. The coking tendency of the oil increases with increasing temperature. In the case of higher-quality oil-containing raw materials, such as oil sands, which contain very much oil and simply release their oil content, the relation between the generation of heat in the combustion stage and the generation of oil vapor in the expulsion stage can be accomplished by con- trolling the temperature in the expulsion stage and/or supplying supporting fuels in the combustion stage. In the case of oil-containing raw materials of low quality, such control is not possible, however, because of the risk of coking.

Therefore, it is the object of the present invention to provide an improved proc- ess and a corresponding plant for raw materials containing organic constituents, such as raw materials containing oil and/or bitumen, in particular oil or tar sand or oil shale, in particular of low quality, which process and plant can also meet the demand of hydrogen for the further processing of the hydrocarbonaceous vapors (oil vapors) recovered or can generate excess hydrogen for other pur- poses.

This object substantially is solved with the invention by a process as mentioned above with the following steps:

supplying the raw materials to an expulsion stage and expelling a hydro- carbonaceous, in particular oil-containing vapor at a temperature of e.g. about 300 to 1000 ⁰ C, supplying the hydrocarbonaceous vapor expelled in the expulsion stage and/or in a gasification stage downstream of the expulsion stage to a processing stage, in which the same is further processed e.g. by cracking, coking and/or hydrotreating, separating the products obtained in the processing stage and withdrawing the same, - introducing the solids left in the expulsion stage and/or in the gasification stage including the non-evaporated fractions of heavy hydrocarbons into a combustion stage, burning the heavy hydrocarbons left in the solids in the combustion stage at a temperature of e.g. about 600 to 1500 ⁰ C, preferably e.g. about 1050 to 1200°C, recirculating hot solids from the combustion stage into the expulsion stage and/or the gasification stage, wherein the oxidizing atmosphere of the combustion stage is separated from the atmosphere of the expulsion stage and/or the gasification stage by means of a blocking device, and - supplying water into the expulsion stage and/or the gasification stage.

At about 500 to 600 ⁰ C, water already reacts with the coking products of the hydrocarbonaceous (oil-containing) solids, e.g. in the reaction

C + H ₂ O → CO + H ₂ .

At the same time, the water can react with the low-volatility constituents of the oil-containing raw materials, so that the same are decomposed and more volatile components are obtained, which are expelled.

The resulting hydrogen advantageously can be used in the processing stage. By means of cracking, lighter hydrocarbons are obtained, which can be processed even further. With the addition of the amount of water and with the temperature in the expulsion stage, the amounts of hydrogen and hydrocarbons produced can be controlled and regulated. In the case that e.g. the generation of hydrogen should be increased or the separation of hydrogen should be simplified, it is expedient to operate a gasification stage parallel to or downstream of the expulsion stage.

In the possibly present gasification stage after the expulsion stage, the residual solids of the expulsion stage can be introduced either completely or in part. The residual solids of the gasification stage, just as the residual solids of the expulsion stage, then can be delivered to the combustion stage. With the amount of water added, in conjunction with the retention time and the temperature, the conversion of the solids can be controlled and the production of a desired amount of hydrogen can be determined. Preferably, the water is converted almost completely (at least for 70%, preferably for at least 90%).

Alternatively, the gasification stage can be charged with oil-containing raw mate- rials, which do not originate from the expulsion stage, e.g. from a preheating.

For the expulsion stage and/or the gasification stage, the water can wholly or partly replace the normally used fluidizing gas.

By using a separate gasification stage, e.g. the gas composition, retention time and temperature can be adjusted and controlled independent of the expulsion stage. Thus, optimum conditions for expelling the oil vapor in the expulsion stage and optimum conditions for gasification with water, possibly together with CO ₂ , in the gasification stage can be adjusted. In particular, the amount of water supplied can be increased in the separate gasification stage.

To provide the heat required for the gasification reaction, the water can be supplied to the expulsion stage and/or the gasification stage as steam or superheated steam of e.g. about 600 ⁰ C. This steam can at least partly be generated with the waste heat from the combustion or from other parts of the plant. The steam can be added with slightly elevated pressure, but also as low-pressure steam with a pressure of 2 to 10 bar.

To improve or control the yield in the reactor, e.g. electromagnetic waves (e.g. microwaves), ultrasound or the like can be used. It is likewise possible to use catalytically active substances in the expulsion stage, but in particular in a separate gasification stage, which can improve and control the expulsion or gasification of the organic constituents or control and change their composition.

The residual hydrocarbon content left in the solids is burnt in the combustion stage configured as heat generator, in order to provide the heat required in the expulsion stage and/or the gasification stage, which by means of the solids withdrawn from the combustion stage is transferred into the expulsion stage and/or the gasification stage. Between the combustion stage and the expulsion stage and/or the gasification stage, a seal is provided, in order to separate the oxidizing atmosphere of the combustion stage from the expulsion stage and/or the gasification stage and avoid an oxidation, combustion or even explosion of the gases generated in the expulsion stage and/or gasification stage.

The drying stage and/or the preheating stage and/or the expulsion stage and/or the gasification stage and/or the combustion stage preferably are operated as fluidized bed.

Recycle gas from the expulsion or gasification stage, inert gas such as nitrogen, oxygen-containing gases such as air, CO ₂ -containing gases, CO-containing

gases, oxygen, hydrogen and/or waste gases from the combustion stage and/or gases obtained from the drying stage and/or the preheating stage and/or the processing stage, which contain light hydrocarbons, or mixtures of said gases can be supplied to the expulsion stage and/or the gasification stage as fluidizing and/or reaction gas. Water or steam can be added to these gases, which in part contain light hydrocarbons beside steam. The hydrocarbonaceous waste gases, in particular from the drying stage, which still contain water, thus can optimally be utilized, and a cooling in the combustion stage can be prevented. It is likewise possible to advantageously use in particular waste water contaminated with hydrocarbons from other plants or parts of the plant in the expulsion and/or gasification stage. It may also be advantageous to use a reactor for the gasification stage, in which the residual solids also are delivered into the combustion stage. Thus, in particular a flash reactor, a stationary fluidized bed or an annular fluidized bed can be used as well.

To improve the energy balance, the preheated fluidizing and/or reaction gases can be supplied to the drying stage and/or the preheating stage and/or the expulsion stage and/or the gasification stage and/or the combustion stage, wherein heating the respective gases, in particular the steam and the water used for generating the steam, preferably can be effected by means of the waste heat obtained during heat recovery from the waste gas and/or from the calcination residue of the combustion stage.

In accordance with the invention, the hydrocarbonaceous vapor is expelled from the solids in the expulsion stage and/or in the gasification stage e.g. by distillation, and it can be expedient to operate the expulsion stage and/or the gasification stage under a reduced pressure in the range from e.g. about 0.001 to 1 bar. With a separate gasification stage, however, an excess pressure of preferably 1 to 20 bar can also be adjusted.

To further increase the production of hydrogen, a CO shift reactor is provided in accordance with a development of the invention after the expulsion stage and/or the gasification stage, in which the reaction

CO + H ₂ O → CO ₂ + H ₂

takes place. In many cases, the reaction can be accelerated by catalysts. With a great increase in temperature in the expulsion stage and/or the gasification stage to for instance from about 850 to 900 ⁰ C, it is also possible that the CO ₂ reacts as follows:

C + CO ₂ → 2 CO.

With the CO shift reactor, the CO obtained likewise can be converted to H ₂ . Such increase in temperature, however, is not always desirable, as it might preclude a more favorable construction of the plant and the amounts recircu- lated from the combustion stage should be minimized. For the gasification stage, the temperature range from 450 to 800 ⁰ C, in particular from 500 to 700 ⁰ C therefore is preferred. If the temperature must be raised to above 800 ⁰ C, pref- erably 900 to 1000 ⁰ C, this preferaby is effected only in the gasification stage.

The gases supplied to the CO shift reactor and/or the processing stage preferably must be subjected to a gas cleaning, such as a dedusting and/or removal of disturbing gases, e.g. of H ₂ S.

The hydrogen obtained in the expulsion stage and/or the gasification stage and/or the CO shift reactor, can be supplied to the processing stage, possibly together with other reaction gases, for cracking and/or a further utilization, such as liquefaction or synthesis, or be used as process gas in a metallurgical plant.

From the gases containing hydrogen and/or CO ₂ , e.g. the hydrogen can be separated, for instance by membrane processes, and/or CO ₂ can be removed, for instance by absorption on exchange media.

To provide the heat required for the gasification reaction, an indirect heating of the expulsion stage and/or of the gasification stage can be effected beside the recirculation of the residual solids from the combustion stage. Alternatively, a partial internal combustion of the solids can take place in the expulsion stage and/or the gasification stage. The CO obtained likewise can be processed to hydrogen in the CO shift reactor. Due to the possibility of an internal combustion, preferably in a separate gasification stage, the process also can be performed much more flexibly. If the heat required is provided by supplying additional residual solids from the combustion stage, a gas barrier between combustion stage and expulsion stage or gasification stage also is expedient here. Even in the case of a partial internal combustion, such gas barrier is expedient to provide for a selective and metered introduction of oxygen, mixtures with oxygen or air into the combustion stage.

In the processing stage, catalytic cracking expediently is effected at a tempera- ture of e.g. about 400 to 600 ⁰ C and a pressure of e.g. about 1 to 2 bar, possibly by means of a zeolite catalyst. The separation of the products obtained in the processing stage can be effected in a distillation column.

The combustion in the combustion stage advantageously is performed in an atmosphere rich in oxygen, wherein a staged combustion can be effected. Additional fuel in the form of untreated hydrocarbonaceous solids, coal, coke, bio- mass or the like then can be supplied to the combustion stage. The heat generated in the combustion stage can be recovered from the waste gas and/or the calcination residue. Especially at low temperatures, heat quantities thus can

partly be utilized, which hardly can be used expediently in some other way, e.g. in the case of cooling water from the cooling of residues.

In accordance with a development of the invention, it is also possible to wholly or partly supply the waste gas from a substoichiometric stage of a staged combustion to the CO shift reactor. This can be effected after a possible cleaning or reprocessing of the waste gas. Furthermore, this waste gas from a substoichiometric stage or from the superstoichiometric combustion can be used as fluidizing, heating or reaction gas for drying, preheating, expulsion, gasification or even combustion.

The process of the invention is not restricted to being used with low-quality hydrocarbonaceous raw materials. Since reprocessing the products from the hydrocarbonaceous raw materials requires a large amount of hydrogen (e.g. for hydrocracking), however, the hydrogen supply represents a limiting factor. With the process of the invention it is at best possible to at least partly provide the hydrogen required for the further processing of the hydrocarbonaceous vapors (oil vapors).

This invention also extends to a plant for refining raw materials containing organic constituents, such as solids containing oil and/or bitumen, in particular oil or tar sand or oil shale, but also oil-containing fluidizable materials or wastes, with an expulsion stage and possibly with a gasification stage downstream of the expulsion stage, to which the hydrocarbonaceous raw materials are sup- plied, with a combustion stage to which solids and fuels coming from the expulsion stage and/or the gasification stage are supplied, with a return conduit, via which hot solids generated in the combustion stage are supplied to the expulsion stage and/or the gasification stage, with a blocking device for separating the gas atmospheres of the combustion stage and of the expulsion stage or the gasification stage, with a processing stage to which hydrocarbonaceous vapor

expelled from the solids in the expulsion stage and/or the gasification stage and/or hydrocarbonaceous gases obtained from the CO shift reactor provided downstream of the same are supplied, and in which the heavy hydrocarbon components are decomposed by means of the hydrogen obtained in the expul- sion stage and/or the gasification stage by adding water and/or in the CO shift reactor, and a separating means for separating the products obtained in the processing stage.

In accordance with a development of the invention, the plant can include a means for separating the hydrogen, which then can be used separately, from the hydrocarbonaceous gases originating from the expulsion stage and/or the gasification stage and/or the CO shift reactor.

The plant also can include a drying stage and/or a preheating stage before the expulsion stage and/or the gasification stage.

Furthermore, a gas cleaning can be provided before the processing stage and the CO shift reactor, respectively.

With the invention, it furthermore is proposed to provide a heat recovery system for the waste gas and/or the calcination residue downstream of the combustion stage.

Further objectives, features, advantages and possible applications of the inven- tion can be taken from the following description of embodiments and the drawings. All features described and/or illustrated form the subject-matter of the invention per se or in any combination, also independent of their inclusion in individual claims or their back-reference.

In the drawings:

Fig. 1 schematically shows an exemplary plant for performing a process in accordance with the invention, and

Fig. 2 schematically shows a possible alternative to the plant as shown in

Fig. 1.

A plant for refining raw materials containing organic constituents, which is schematically shown in Fig. 1 , includes a drying stage 2, to which hydrocarbo- naceous raw materials, such as oil or tar sand or oil shale, are supplied via a supply conduit 1. Via a conduit 3, the solids thus dried are delivered to a preheating stage 4 and from there, preheated, with a temperature of e.g. about 200 ⁰ C via a conduit 5 to an expulsion stage 6 suitable for distillation, in which the same are heated to e.g. 500 to 800 ⁰ C, and the organic constituents thereby are expelled as hydrocarbonaceous vapors. In the illustrated case, the drying stage 2, the preheating stage 4 and the expulsion stage 6 constitute fluidized- bed reactors, to which the fluidizing and/or reaction gases are supplied via fluidizing conduits 25a to 25c. Via a conduit 28, water n the form of steam fur- thermore is supplied to the expulsion stage 6 as fluidizing and/or reaction gas.

The hydrocarbonaceous vapors (oil vapors) dried and preheated in the drying stage 2 and in the preheating stage 4 are supplied to a gas cleaning 8 via conduits 26, 27. Together with the hydrogen obtained by the reaction C + H ₂ O → CO + H ₂ , the hydrocarbonaceous vapors (oil vapors) obtained in the expulsion stage 6 likewise are delivered via conduit 7 to the gas cleaning 8 and from there together with the remaining gases via a processing stage 9 including a cracker into a separating means 10, from which the individual product components are discharged to the outside. In the processing stage 9, the hydrogen originating

from the expulsion stage 6 is used for cracking the heavy hydrocarbon components present.

Alternatively, conduit 26 can lead not into the gas cleaning 8, but into the expul- sion stage 6.

The residual solids left in the expulsion stage 6 after expelling the hydrocarbon gases, which contain amounts of heavy hydrocarbons, are supplied via a conduit 11 to a combustion stage 12 configured e.g. as a fluidized-bed furnace, to which e.g. air, oxygen-containing or oxygen-enriched gas and part of the hydrocarbon gas originating from the expulsion stage 6 can also be supplied via conduits 13, 14 for starting, regulating or controlling the combustion stage 12.

From the combustion stage 12, a return conduit 15 leads to a non-illustrated blocking device 16, which serves to separate the atmospheres of the combustion stage 12 and the expulsion stage 6 and is connected with the expulsion stage 6 via a conduit 17.

The waste gas from the combustion stage 12 is supplied via a conduit 18 to a heat recovery 19 and then via a conduit 20 to a gas cleaning 21. The calcination residue of the combustion zone 12 also can be supplied to a heat recovery 23 via a conduit 22. The hot air obtained in the heat recoveries 19, 23 can be introduced as combustion air into the combustion stage 6 via a conduit 24. The heat recoveries 19, 23 can, however, also be used for preheating the fluidizing and/or reaction gases to be supplied to the various fluidized beds, in particular the steam to be supplied to the expulsion stage 6 or the water provided for this purpose.

The plant shown in Fig. 2 is an alternative to the plant of Fig. 1 , wherein identi- cal parts of the plant are provided with the same reference numerals, in order to

illustrate that they perform the same or corresponding functions as the parts of the plant shown in Fig. 1.

The plant as shown in Fig. 2 substantially differs in that the residual solids of the expulsion stage 6 are supplied via a conduit 33 to a gasification stage 30, which can be supplied with steam or fluidizing gas via conduits 34, 35. Via a conduit

36, the residual solids of the gasification stage 30 likewise are supplied to the combustion stage 12, which in this case is connected with the expulsion stage 6 and the gasification stage 30 via the return conduit 15 and the blocking devices 16a, 16b as well as the solid conduits 17a, 17b.

Furthermore, the plant as shown in Fig. 2 differs from the one shown in Fig. 1 in that between the gas cleaning 8 and the processing stage 9 a CO shift reactor 29 is provided for the (additional) generation of hydrogen from the gases origi- nating from the expulsion stage 6 and the gasification stage 30. Via a gas cleaning 37, which can be identical with the gas cleaning 8, the gasification stage 30 is connected with the CO shift reactor 29.

List of Reference Numerals:

I supply conduit for raw materials 2 drying stage

3 conduit for dried solids

4 preheating stage

5 conduit for preheated solids

6 expulsion stage 7 conduit for oil vapors and hydrogen

8 gas cleaning

9 processing stage (e.g., cracker)

10 separating means

I 1 conduit for residua! solids 12 combustion stage (furnace)

13 conduit for combustion gas

14 conduit for fuel gas

15 return conduit for solids

16 blocking device 16a blocking device

16b blocking device

17 conduit for solids 17a conduit for solids 17b conduit for solids 18 conduit for waste gas

19 heat recovery for waste gas

20 conduit for waste gas

21 gas cleaning

22 conduit for calcination residue 23 heat recovery for calcination residue

24 conduit for heated air 25a-c fluidizing conduits

26 conduit for oil vapors

27 conduit for oil vapors 28 conduit for steam

29 CO shift reactor

30 gasification stage

31 conduit for oil vapors with CO and H ₂

32 conduit for oil vapors with CO and H ₂ 33 conduit for solids

34 conduit for water

35 fluidizing conduit

36 conduit for residual solids

37 gas cleaning