Process for the production of synthesis gas

Details Process for the production of synthesis gas Process for the production of synthesis gas

1999-09-24

2001-03-27

Richter, Johann (Department: 1621)

Compositions

Gaseous compositions

Carbon-oxide and hydrogen containing

C518S703000, C518S704000, C423S359000

Reexamination Certificate

active

06207078

ABSTRACT:

DESCRIPTION
1. Field of Application
The present invention relates to a process for the production of synthesis gas for obtaining compounds such as ammonia and methanol.
More specifically, the invention relates to a process for the production of synthesis gas comprising the steps of:
feeding a first flow comprising hydrocarbons and a first gas flow comprising steam to a primary reforming section;
feeding a first gas flow comprising oxygen and possibly nitrogen to a secondary reforming section;
reacting the hydrocarbons and steam first in the primary reforming section and then—together with oxygen—in the secondary reforming section, obtaining a first gas phase comprising CO, CO
2
, H
2
and possibly N
2
;
feeding the first gas phase comprising CO, CO
2
, H
2
and possibly N
2
to a carbon monoxide conversion section.
Throughout this specification and the appended claims, the term: “hydrocarbons” is used to indicate generically a raw material source of hydrogen and carbon, such as for example methane, natural gas, naphtha, GPL, (liquefied petroleum gas) or refinery gas and mixtures thereof.
The invention relates also to a plant for the production of synthesis gas for implementing the aforesaid process, as well as to a method of retrofitting an existing plant for the production of synthesis gas.
As known, in the field of synthesis gas production, more and more the need is felt of realizing processes which are easy to implement and allow to reach higher and higher production capacities with low operating and investment costs and low energy consumption.
2. Prior Art
In order to satisfy such requirements, synthesis gas production processes, in which a flow comprising hydrocarbons and a gas flow comprising steam are sent first to a primary reforming section and then—together with a gas flow comprising oxygen and possibly nitrogen—to a secondary reforming section, have found broad application. A gas phase rich in CO, CO
2
, H
2
and possibly N
2
is thereby obtained, which is in turn sent to treatment sections such as for example the carbon monoxide conversion sections at high and low temperature. The treatment sections can vary depending on the type of synthesis gas to be produced.
In order to improve the conversion yield of hydrocarbons, as well as to reduce the energy consumption, processes for the production of synthesis gas are used in the field wherein the conversion reaction in the secondary reforming section is carried out in the presence of a catalyst.
The secondary reformers intended for carrying out such processes are generally called autothermal, since they do not require external heat supply for their operation.
Although advantageous in some aspects, the above described processes exhibit a series of drawbacks. First of all the fact of being little flexible and not able to adapt themselves effectively to variations in the operating conditions, in particular when significant increases in the amount of synthesis gas to be produced are required.
In fact, the primary and secondary reforming sections, responsible for the conversion of hydrocarbons, are not able to operate conveniently apart from the design capacity.
Therefore, in order to adapt the synthesis gas producing plants which operate according to the above described processes to the capacity increases required more and more in this field, dramatic interventions of retrofitting and, last but not least, the replacement of the reforming sections themselves with sections having increased capacity are necessary, with very high investment costs.
Further on, it is important to notice that the presence of a primary reforming section requires a supply from outside of high amounts of heat that affects negatively the overall energy consumption necessary for implementing such processes.
Because of these drawbacks, the implementation of synthesis gas producing processes according to the prior art requires today high investments and energy consumption, such to penalize remarkably the costs of base chemicals such as hydrogen and carbon monoxide, despite the ever increasing demand for these products.
SUMMARY OF THE INVENTION
The problem underlying the present invention is to provide a process for the production of synthesis gas which is easy to implement and allows to obtain high production capacities with low operating and investment costs as well as with low energy consumption.
The above problem is solved, according to the invention, by a process for the production of synthesis gas of the aforesaid type, which is characterized in that it comprises the steps of:
feeding a second flow comprising hydrocarbons, a second gas flow comprising steam and a second gas flow comprising oxygen and possibly nitrogen to an autothermal reforming section provided in parallel with respect to the primary and secondary reforming sections;
reacting the hydrocarbons, steam and oxygen in the autothermal reforming section, obtaining a second gas phase comprising CO, CO
2
, H
2
and possibly N
2
;
feeding the second gas phase comprising CO, CO
2
, H
2
and possibly N
2
to the carbon monoxide conversion section.
Throughout this specification and the appended claims, the term: “autothermal reforming section” is used to indicate a reforming section wherein hydrocarbons, steam and oxygen are reacted, preferably in the presence of catalyst, without heat being supplied from outside. In the production of synthesis gas for ammonia or methanol, sections of this kind are generally called secondary reforming sections.
Advantageously, thanks to the step wherein a second flow of hydrocarbons is reacted in an autothermal reforming section, it is possible to face easily and effectively even substantial capacity variations of the plant implementing the process according to the invention.
In fact, according to the present invention, the reforming reaction of hydrocarbons is carried out in two stages, provided in parallel, the former comprising a primary reforming section and a secondary reforming section, the latter comprising an autothermal reforming section.
In this way, it is possible to apportion the desired total production of synthesis gas in the two reforming stages, whose capacity may be therefore varied from time to time and independently according to the specific demand, without negatively affecting the remaining process.
In particular, the load partition in the reforming sections arranged in parallel, allows—inter alia—to optimize the energy consumption, maximizing the production of synthesis gas in the autothermal reforming section and at the same time minimizing the feed to the primary reformer.
In other words, the production capacity of synthesis gas being equal, the present process permits to suitably apportion in two reforming stages arranged in parallel the hydrocarbons and the steam. Therefore the overall energy consumption is lower than that needed by the prior art.
Advantageously, the gas flows comprising CO, CO
2
, H
2
and possibly N
2
obtained respectively in the secondary reforming section and in the autothermal reforming section, are sent to a same carbon monoxide conversion section, exploiting in this way only one equipment line in order to carry out the subsequent steps of preparation for the synthesis gas.
A further advantage, resulting from the process according to the invention, is given by the fact that, having the possibility of feeding separate flows of hydrocarbons to reforming stages independent from each other, it is advantageously possible to use for the production of synthesis gas hydrocarbons of different nature in the different reforming stages, thus adapting the process to the existing natural resources and to whichever requirement may arise.
In order to obtain a synthesis gas for the production of ammonia with a high CO
2
/H
2
molar ratio, the second gas flow comprising oxygen fed to the autothermal reforming section comprises advantageously oxygen enriched air.
Throughout this specification and the appended claims, the term: “oxygen enriched air” is used to indicate air with a molar oxygen content above 21%, for example comprise

Affiliated with

Also associated with

Rating

Process for the production of synthesis gas does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for the production of synthesis gas, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the production of synthesis gas will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2458842