|Publication number||US20070011945 A1|
|Application number||US 11/428,478|
|Publication date||Jan 18, 2007|
|Filing date||Jul 3, 2006|
|Priority date||Jul 5, 2005|
|Also published as||CN101218170A, CN101218170B, EP1899265A1, EP1899265B1, WO2007003620A1|
|Publication number||11428478, 428478, US 2007/0011945 A1, US 2007/011945 A1, US 20070011945 A1, US 20070011945A1, US 2007011945 A1, US 2007011945A1, US-A1-20070011945, US-A1-2007011945, US2007/0011945A1, US2007/011945A1, US20070011945 A1, US20070011945A1, US2007011945 A1, US2007011945A1|
|Inventors||Gerard Grootveld, Pieter Zuideveld|
|Original Assignee||Gerard Grootveld, Zuideveld Pieter L|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (16), Classifications (29), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Priority is claimed of European patent application No. 05106072.1 filed Jul. 5, 2005.
The present invention relates to systems and methods for producing synthesis gas comprising CO and H2 from a carbonaceous stream using an oxygen containing stream.
Generally in such systems and methods, a carbonaceous stream such as coal, brown coal, peat, wood, coke, soot, or other gaseous, liquid or solid fuel or mixture thereof, is partially combusted in a gasification reactor using an oxygen containing gas such as substantially pure oxygen or (optionally oxygen enriched) air or the like, thereby obtaining synthesis gas (CO and H2), CO2 and optionally a slag. In case where slag is formed during the partial combustion, it drops down and is drained through an outlet located at or near the reactor bottom.
The hot product gas, which may be referred to as raw synthesis gas, is typically quenched in a quench section which is located downstream of the gasification reactor. In the quench section a suitable quench medium such as water, cold gas, recycled synthesis gas or the like is introduced into the raw synthesis gas in order to cool it.
After the quenching, the raw synthesis gas is further processed, e.g. to remove undesired components from it or to convert the CO into methanol and various other hydrocarbons. The H2 may be used a product gas or used for e.g. hydrocracking purposes.
WO-A-99/55618 describes a process to prepare a synthesis gas by means of two parallel-operated processes. One process is the partial oxidation, also referred to as gasification, of a biomass feed. In the parallel process, a natural gas is used as feed for a steam reforming process. Synthesis gas mixtures from both processes are combined.
WO-A-02/090250 describes a process to prepare a synthesis gas by means of two parallel-operated partial oxidation processes. In one process a solid or liquid feed is used as feed and in the parallel process a natural gas is used as feed. Synthesis gas mixtures from both processes are combined.
Known gasification reactors which operate on a liquid and especially on a solid feed, such as coal as in WO-A-02/090250, usually have a relative low availability. After a certain operating period, the reactor typically has to be shut down for a while, to check and repair the internals, if necessary. As a result no synthesis gas is produced for a while, or the syngas production is substantially halved as would be in the case of the process of WO-A-02/090250.
The above problem is even more pertinent in cases where the gasification reactor uses a particulate carbonaceous feed stream, such as coal and especially petroleum coke, that is intended to produce H2 as the main product. If the gasification process is applied in a refinery environment, using petroleum coke as the feed to the gasification process, a high H2 availability, usually greater than 98% of the year, and/or a high synthesis gas availability for generating power is desired. Hydrogen is used for the various refinery processes such as hydrotreating, hydrofinishing, hydrocracking and catalytic dewaxing. Disruptions in either the hydrogen or the power supply in a refinery is not desired. It is an object of the present invention to at least minimize the above problem.
It is a further object to provide a system ensuring a high availability of synthesis gas, while using as few components as possible.
It is an even further object to provide an alternative system for producing synthesis gas.
The present invention provides a system for producing synthesis gas comprising CO and H2, the system comprising first and second gasification reactors.
The first gasification reactor may comprise a first-reactor oxygen inlet for a first oxygen-containing stream, a first-reactor fuel inlet for a first, carbonaceous stream, and a first-reactor outlet for raw synthesis gas produced in the first gasification reactor.
The second gasification reactor may comprise a second-reactor oxygen inlet for a second oxygen-containing stream, a second-reactor fuel inlet for a second carbonaceous stream, and a second-reactor outlet for raw synthesis gas produced in the second gasification reactor.
The system further comprises an oxygen source of an oxygen containing stream and a distributor for fluidly connecting the oxygen source to the first-reactor oxygen inlet and to the second-reactor oxygen inlet, the distributor being arranged to selectively connect the oxygen source to the first or second gasification reactor.
In another aspect the present invention provides a method of producing synthesis gas comprising CO and H2, from a carbonaceous stream using an oxygen-containing stream, the method comprising at least the steps of:
The first and second gasification reactors may function at the same time, but it is especially preferred that the first and second gasification reactors are used alternately.
The method may further comprise optional steps of:
The first carbonaceous stream may comprise a particulate carbonaceous stream which may comprise a petroleum coke.
The second carbonaceous feed may be a gaseous stream which may comprise at least one of the vacuum residue feed of the coking process and natural gas, preferably natural gas.
The invention further provides a method using a spare gasification reactor in a process to generate power from a source of petroleum coke in one or more parallel operated gasification reactors, which spare reactor is capable of preparing a spare synthesis gas mixture comprising carbon monoxide and hydrogen by partial oxidation of at least one of a vacuum residue and natural gas, using up to a maximum first volume of oxygen per hour as obtained from an air separation unit.
Power generation based on petroleum coke may then optionally be obtained by
Carbon dioxide may advantageously be isolated prior to the power generation in, for example, a gas turbine. Carbon dioxide may be subjected to sequestration or suitably used for agricultural uses or enhanced oil recovery.
Hydrogen may optionally be obtained in said preferred embodiment from the petroleum coke by
The gas separation step may comprise or consist of a pressure swing absorbing process (PSA).
Irrespective of whether power is generated and/or hydrogen produced, the maximum capacity of the air separation unit is preferably less than the sum of the maximum first and second oxygen volumes per hour.
The invention will hereinafter be illustrated by way of example in more detail with reference to the accompanying non-limiting drawing.
In the accompanying drawing:
For the purpose of this description, a single reference number will be assigned to a line as well as a stream carried in that line. Same reference numbers refer to similar components.
Reference is made to
The system 1 comprises a first gasification reactor 2, a second gasification reactor 3, an oxygen source 4 and a shift converter 5. In the embodiment shown in
In the system 1 according to
Similarly, a gas containing stream 30 and an oxygen containing stream are 70 are fed into the gas gasification reactor 3 at inlets 9 and 11.
During normal use of the embodiment of
If the coal gasification reactor 2 is functioning, the oxygen source 4 feeds an oxygen containing stream 50 to the distributor 25 which selectively connects the source 4 to the coal gasification reactor 2 via lines 50 and 60. At this point no oxygen is fed to the gas gasification reactor 3.
The carbonaceous stream 10 is partially oxidised in the gasification reactor 2 thereby obtaining raw synthesis gas 20 (removed via outlet 8) and a slag (removed via stream 90). To this end usually several burners (not shown) are present in the gasification reactor 2.
The synthesis gas 20 produced in the coal gasification reactor 2 is usually fed to a quenching section (not shown); herein the raw synthesis gas is usually cooled.
As shown in the embodiment of
If desired, the synthesis gas stream 20 may be processed before entering the shift converter 5, e.g. in a dry solids removal unit (not shown) to at least partially remove dry ash in the raw synthesis gas 20. Also, the synthesis gas 20 may be fed to a wet gas scrubber (not shown).
If the coal gasification reactor 2 needs to be periodically checked, the gas gasification reactor 3 is started up (or is already on hot standby). The coal gasification reactor 2 is then shut down and the distributor 25 no longer feeds oxygen (via stream 60) to the coal gasification reactor 2, but connects the oxygen source 4 to the gas gasification reactor 3 via streams 50 and 70. The synthesis gas 40 removed from the gas gasification reactor 3 at outlet 12, may be processed similarly as the stream 20 and is also fed to the shift converter 5. In case a slag would be formed in the gasification reactor 3, a slag stream is removed via line 100.
According to an advantageous embodiment of the invention, the synthesis gas 40 is fed to the same shift converter 5 as stream 20 originating from the coal gasification reactor 2. Before stream 40 is fed to the same shift converter it is preferred to remove any solids from synthesis gas 20 in for example a separate dry solids removal step. Before stream 40 is fed to the same shift converter it is preferred to subject the synthesis gas to a separate wet gas scrubber. With “separate” is here meant, that when the spare second gasification reactor 3 is used the synthesis gas 40 does not pass the dry solids removal step and/or the wet gas scrubber used for stream 20.
As soon as the coal gasification reactor 2 is ready for use again, the coal gasification reactor 2 may be restarted. Then the distributor 25 may switch off the oxygen stream 70 to the gas gasification reactor 3, and oxygen is fed again through line 60 to coal gasification reactor 2. The gas gasification reactor 3 may then be shut down or for instance put on hot standby until later use. Thus, in the embodiment of
The person skilled in the art will readily understand that, if desired, the switching between the reactors 2 and 3 may proceed gradually. Thus, if the reactor 2 is to be shut down, the distributor 25 gradually decreases the oxygen stream 60 to reactor 2, at the same time increasing the oxygen stream 70 to reactor 3. As a result, the distributor 25 feeds oxygen to both reactors 2,3 at the same time for a certain period.
In the embodiment of
As the shift converter 5 is already known per se, it is not further discussed here in detail.
It has been contemplated that synthesis gas can be produced while ensuring a very high availability of the synthesis gas, even if the gasification reactor intended for the particulate carbonaceous stream is out of order.
Further it has been contemplated that the above may be achieved using a very simple system.
The combination of a gasification reactor intended for a particulate carbonaceous stream and a different type gasification reactor is contemplated more economic than if two gasification reactors intended for a particulate carbonaceous stream would be used which may be an important advantage.
The first and second gasification reactors may be any suitable reactor for partially oxidizing the respective carbonaceous stream. If desired more than one first and second gasification reactors may be used thereby obtaining a system comprising more than two gasification reactors being connected to the distributor.
The second gasification reactor may be used as a spare reactor, which may only be used if the first gasification does not operate, for example due to a failure to operate. In such an embodiment it is possible to limit the capacity of the air separation unit to a capacity, which is required to perform the gasification in the first gasification only. In case the first gasification fails, the second gasification can advantageously take over the preparation of synthesis gas, thereby making use of the oxygen manufacturing capacity, which is at that time not used by said first gasification reactor. As a result, the availability of synthesis gas may be ensured, even if the first gasification reactor or one of the first gasification reactors is out of order or on hot standby, while minimizing the required capacity of the oxygen manufacturing unit, suitably the air separation unit.
The first, particulate carbonaceous stream may be obtained from a high carbon containing feedstock such as naturally occurring coal, biomass or synthetic cokes. Synthetic coke is also referred to as petroleum coke. Petroleum coke is a by-product of a widely applied crude oil refining process. Petroleum coke may also be obtained as the by-product of a tar sands upgrading process as for example described in US-A-2002/0170846. In this publication a process is described wherein the heavy oil fraction of a bitumen or tar sands feed is converted into a gas oil product by means of a fluid coking process. Petroleum coke may for example be prepared by delayed coking, which is probably the most widely used coking process. Delayed coking uses a heavy residual oil as a feedstock. During delayed coking, heavy residual oil is introduced into a furnace, heated to about 480° C., and pumped into coking drums. The coking process initiates the formation of coke and causes it to solidify on the drum wall. Thermal decomposition drives off lower boiling products, which are removed continuously. When this reaction is complete, the drum is opened, and coke is removed. The first, particulate carbonaceous stream may be dry or wet. In the latter case the first stream is in the form of a slurry.
The first carbonaceous stream may also be a liquid stream. Suitable liquid streams are vacuum residues as obtained from crude mineral oils or tar sand oils or the asphalt fraction as obtained from a de-asphalting process using the vacuum residues as obtained from crude mineral oils or tar sand oil. Preferably the second carbonaceous stream is a gaseous stream as will be described below in case the first carbonaceous stream is such a liquid stream.
The second carbonaceous stream may be a substantially liquid or gaseous stream (or a combination of one or more thereof) suitable to be partially oxidized in the second gasification reactor, a gaseous stream being preferred. As a liquid stream e.g. oil, a condensate, a vacuum or atmospheric distillate or asphalt or other residue may be used.
The use of the vacuum residue feed of the coking process may be advantageous in situations wherein the coking operation itself fails to prepare the petroleum coke feed for the first gasification reactor. This will result in that the first gasification reactor fails to operate. The feed to the coking process may then be suitably used in the second gasification reactor.
As a gaseous stream for example natural gas, methane, ethane, propane, refinery gases, etc. may be used. Preferably the second carbonaceous stream is a gaseous stream, most preferably natural gas or mixtures of natural gas and refinery gasses, suitably refinery gasses comprising methane and ethane. A gaseous feed is preferred because the gasification reactor and the downstream gas processing steps may be of a more simple design. Furthermore the hydrogen to carbon monoxide molar ratio will be higher, resulting in less carbon dioxide by-product being made in the water shift reaction.
The source of an oxygen containing stream may be any suitable source. Preferably substantially pure oxygen or (optionally oxygen enriched) air or the like is used. Further, preferably a single source is used and is connected to both the first and the second gasification reactor(s). Preferably, the oxygen containing stream comprises >50 vol. % O2, preferably >90 vol. % O2, more preferably >95 vol. % O2, even more preferably >99 vol. % O2.
A preferred source of oxygen comprises a so-called air separation unit, wherein an oxygen containing stream can be prepared. Such air separation units and processes are well known and are also referred to as cryogenic air separation. In such a process compressed air is cooled and cleaned prior to cryogenic heat exchange and distillation into oxygen, nitrogen, and optionally, argon rich streams. Pressurizing these streams for delivery is accomplished by gas compression, liquid pumping or combinations of pumping followed by compression.
The maximum capacity of the air separation unit is preferably less than the sum of the oxygen requirements for gasification of the petroleum coke feed and the oxygen requirement for gasification of the natural gas feed as described above.
The capital investment for an air separation unit is very high. Thus processes, which require a lower oxygen capacity for the same synthesis gas production, are desired. In a preferred embodiment of the present invention the maximum capacity of the air separation unit is less than 80% of the sum of the oxygen requirements for the first and the second gasification reactor(s), especially if two first gasification reactors and one second gasification reactor are used. More preferably this percentage is less than 65%, especially when one first gasification reactors and one second gasification reactor are used. By definition the lower boundary for this percentage is 50%.
The person skilled in the art will readily understand that the distributor may have different embodiments as long as it is arranged to selectively connect the source of oxygen to the first or second gasification reactor.
With the term ‘raw synthesis gas’ is meant that this product stream may—and usually will—be further processed, e.g. in a dry solid remover, wet gas scrubber, a shift converter or the like.
The person skilled in the art will readily understand that the present invention may be modified in various ways without departing from the scope as defined in the claims.
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|U.S. Classification||48/197.00R, 48/61|
|Cooperative Classification||C01B13/0229, C01B2203/025, C10K3/04, C01B2210/0046, C10J2300/093, C10J3/723, C10K1/08, C01B3/48, C01B2203/065, C01B2203/1241, C01B2203/141, C01B2203/84, C10J3/00, C10J3/721, C01B2210/0082, C10J2300/0959, C01B3/36, C01B2203/86, C01B2203/0283|
|European Classification||C10J3/72C, C10K3/04, C10K1/08, C01B3/36, C01B3/48, C01B13/02D, C10J3/00|
|Sep 27, 2006||AS||Assignment|
Owner name: SHELL OIL COMPANY, TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:GROOTVELD, GERARD;ZUIDEVELD, PIETER LAMMERT;REEL/FRAME:018337/0121;SIGNING DATES FROM 20060810 TO 20060815