Title of Invention

A PROCESS FOR AUTOTHERMAL REFORMATION OF A HYDROCARBON FEEDSTOCK

Abstract This invention relates to a process for autothermal reformation of a hydrocarbon feedstock comprises the steps of preparing a hot gas which is rich in hydrogen by contacting a methanol and steam containing feed gas with a methanation catalyst and introducing the hot gas into the autothermal reformer, thereby heating the reformer with heat contained in the hot gas to temperature which is sufficiently high to initiate and maintain subsequent reforming reactions to be carried out in the reformer.
Full Text The present invention relates to a process for autothermal reformation of a hydrocarbon feedstock.
Conventionally, autothermal reformers are stand alone reformers with no tubular reformers up-stream. Start-up of the autothermal reformers has been performed by preheating the entire reactor to high start-up temperatures i.e. between about 600°C and 1000°C. After the start-up temperature has been reached, a feedstock of e.g. gas steam mix-' tures and oxygen steam mixtures or in some cases oxygen air-mixtures is introduced into the heated reactor for further processing. The reactor is thereby subjected to detrimental pressurization and refractory lining material in top part of the reactor to excessive heat-up, during the first period of operation until a constant high pressure has been established.
During start-up, autothermal reformers produce a product gas mixture containing soot particles leading to a dark condensate, which cannot or only after further processing be reused. Other methods of starting similar reactors have been used in the industry.
In the ammonia industry, where a tubular reformer is supplying heat for preheating of a secondary reformer when appropriate conditions have been obtained, air is gradually added to the secondary' reformer so that the secondary reformer is not subjected to abrupt pressure changes and only to a modest increase in temperature.

The Japanese patent document JP 06305702 relates to start-up heating of a secondary steam reformer in a sequence of primary and secondary steam reforming. At start up of the process, a mixture of hydrogen and carbon monoxide or dioxide is methanised in the primary reforming reactor tube. Thereby, the temperature in the primary steam reforming tube is raised and size of a start-up heater is reduced.
This prior art concerns start-up heating of a primary reformer tube by means of methanisation of hydrogen and carbon oxides, whereas the present invention concerns start-up heating of an autothermal reactor and utilizes catalytic decomposition of a mixture of methanol and steam by means of a methanisation catalyst in order to provide hydrogen, carbon monoxide and methane for the start-up heating of the autothermal reactor.
Use of methanol and decomposition of the same to provide a hot gas for heating of an autothermal reformer is nowhere mentioned nor remotely touched in the prior art.
It has now been found that the start-up of an autothermal reformer may be performed by two different methods.
In one method of the invention, a gas is produced as feed to the autothermal reactor, which is similar to the gas supplied from a tubular reformer. This method can be used in a plant with a fired heater followed by an adiabatic pre-reformer and optionally a reheat step before the autothermal reformer.
In another method of the invention, a mixture of methanol and steam is preheated in a fired heater and then passed to a methanation reactor in which methanol is decomposed to form hydrogen and carbon oxides and minor amounts of methane.

By changing the ratio between steam and methanol, the outlet temperature from the methanator is adjusted to temperatures similar to the inlet temperature to the methanator in order to heat the autothermal reformer and at the same time activate the catalyst contained therein. These catalysts are commonly known and consist of Ni supported on an alumina carrier material. The mixture leaving the methanator is rich in hydrogen and optionally rich in steam, the gas mixture is then similar to the gas leaving a tubular reformer at temperatures about 650°C or higher, when the tubular reform is operated with a steam to carbon ratio of between 2.5 and 4.5. The hot mixture is then introduced into the autothermal reformer to warm up the reformer and to start the reforming reaction. One example of the invention is the following detailed description of the preferred embodiment of the invention.
Accordingly, the present invention provides a process for autothermal reformation of a hydrocarbon feedstock comprising the steps of: (a) catalytically decomposing a mixture of methanol and steam to a gas mixture containing hydrogen, carbon monoxide and a minor amounts of methane in presence of a methanation catalyst as herein described, capable of decomposing methanol to hydrogen, carbon oxides and methane and heating the gas mixture to a temperature of at least 650°C;
(b) introducing the decomposed hot gas mixture into a autothermal reformer to heat the autothermal reformer with heat contained in the hot gas mixture; and subsequently
(c) introducing a hydrocarbon feedstock into the heated autothermal reformer for autothermal reformation of the feedstock.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.

The Fig.I in drawing illustrates a schematic flow sheet of the start-up method according to the preferred embodiment of the present invention.
Referring to the drawing, an autothermal reformer 2 is designed for a natural gas flow of approximately 200.000 Nm /h. For the start-up of such a reformer, a methanator 4 with 2-4 m of catalyst 6 will be adequate and an hourly flow of methanol during the start-up phase of 15 to 20 ton/h is sufficient. In the example, a 50-50 mixture of methanol (MeOH) and steam is used and the mixture is preheated to 550-650°C, the methanator will then have an outlet temperature of about 675°C. Entry of oxygen steam, methylalcohol and natural gas is shown as A, B, C and D.
The total estimated methanol consumption for one start-up cycle is about 100 metric ton. The methanator is equipped with a pressure drop controlled by-pass valve. After ignition, natural gas is added gradually to the combined stream. As the pressure drop in the methanator increases, the by-pass valve 8 disposed as by-pass over the start-up reactor is opened and the plant gradually changes to normal running conditions.
A further advantage of the above described inventive method is that the conventionally used start-up valve systems are no longer needed resulting in considerable economic savings in the construction costs of autothermal reactors.
Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.




WE CLAIM:
1. A process for autothermal reformation of a hydrocarbon feedstock comprising
the steps of:
(a) catalytically decomposing a mixture of methanol and steam to a gas
mixture containing hydrogen, carbon monoxide and a minor amounts of
methane in presence of a methanation catalyst as herein described,
capable of decomposing methanol to hydrogen, carbon oxides and
methane and heating the gas mixture to a temperature of at least 650°C;
(b) introducing the decomposed hot gas mixture into a autothermal reformer to heat the autothermal reformer with heat contained in the hot gas mixture; and subsequently
(c) introducing a hydrocarbon feedstock into the heated autothermal reformer for autothermal reformation of the feedstock.
2. A process for autothermal reformation of a hydrocarbon feedstock substantially
as herein described with reference to the accompanying drawings.



Documents:

0181-mas-1999 abstarct-duplicate.pdf

0181-mas-1999 claims-duplicate.pdf

0181-mas-1999 description (complete)-duplicate.pdf

0181-mas-1999 drawings-duplicate.pdf

181-mas-1999-abstract.pdf

181-mas-1999-claims.pdf

181-mas-1999-correspondence others.pdf

181-mas-1999-correspondence po.pdf

181-mas-1999-description complete.pdf

181-mas-1999-drawings.pdf

181-mas-1999-form 1.pdf

181-mas-1999-form 26.pdf

181-mas-1999-form 3.pdf

181-mas-1999-form 4.pdf


Patent Number 229336
Indian Patent Application Number 181/MAS/1999
PG Journal Number 12/2009
Publication Date 20-Mar-2009
Grant Date 16-Feb-2009
Date of Filing 12-Feb-1999
Name of Patentee HALDOR TOPSOE A/S
Applicant Address NYMOLLEVEJ 55, DK-2800 LYNGBY,
Inventors:
# Inventor's Name Inventor's Address
1 IVAR IVARSEN PRIMDAHL DALMOSEVEJ 6-8 DK-2400 COPENHAGEN NV,
PCT International Classification Number C01B3/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/074,689 1998-02-13 Denmark