Process for methanol production from low quality synthesis gas

• US 10,550,055 B2
• Filed: 07/15/2016
• Issued: 02/04/2020
• Est. Priority Date: 08/12/2015
• Status: Active Grant

• Current Assignee: Topsoe
• Original Assignee: Haldor Topsã¸E A/S (Haldor Topsã¸E Holding A/S)
• Inventors: Modarresi, Hassan
• Primary Examiner(s): Bahta, Medhanit W
• Application Number:
  US15/749,607
• Publication Number:
  US 20180237366A1
• Time in Patent Office: 1,299 Days
• CPC Class Codes: B01J 19/0013 Controlling the temperature of the process
• CPC Class Codes: B01J 19/0053 Details of the reactor
• CPC Class Codes: B01J 2208/00061 of the reactants
• CPC Class Codes: B01J 2208/00176 outside the reactor
• CPC Class Codes: B01J 2208/00274 involving reactant vapours
• CPC Class Codes: B01J 2208/0053 Controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling
• CPC Class Codes: B01J 2208/00716 Means for reactor start-up
• CPC Class Codes: B01J 2219/00105 part or all of the reactants being heated or cooled outside the reactor while recycling
• CPC Class Codes: B01J 2219/00202 at the reactor outlet
• CPC Class Codes: B01J 2219/00213 Fixed parameter value
• CPC Class Codes: B01J 2219/00231 at the reactor inlet
• CPC Class Codes: B01J 2219/00389 Feeding through valves
• CPC Class Codes: B01J 8/001 Controlling catalytic processes B01J8/1809 takes precedence
• CPC Class Codes: B01J 8/0453 the beds being superimposed one above the other
• CPC Class Codes: B01J 8/0457 the beds being placed in separate reactors
• CPC Class Codes: B01J 8/0492 Feeding reactive fluids for solid material, see B01J8/0015
• CPC Class Codes: B01J 8/0496 Heating or cooling the reactor
• CPC Class Codes: C07C 2521/04 Alumina
• CPC Class Codes: C07C 2523/80 with zinc, cadmium or mercury
• CPC Class Codes: C07C 29/15 by reduction of oxides of carbon exclusively
• CPC Class Codes: C07C 29/1512 : characterised by reaction conditions
• CPC Class Codes: C07C 29/1518 : one step being the formation of initial mixture of carbon oxides and hydrogen for synthesis
• CPC Class Codes: C07C 31/04 : Methanol

Abstract

In a novel process for methanol production from low quality synthesis gas, in which relatively smaller adiabatic reactors can be operated more efficiently, some of the inherent disadvantages of adiabatic reactors for methanol production are avoided. This is done by controlling the outlet temperature in the pre-converter by rapid adjustment of the recycle gas, i.e. by manipulating the gas hourly space velocity in the pre-converter.

Claims

1. A process for methanol production from synthesis gas comprising the following steps:

providing a fresh, pressurized methanol synthesis gas containing hydrogen, carbon monoxide and carbon dioxide,

preheating and passing the fresh synthesis gas through an adiabatic methanol pre-converter/guard reactor to generate a process gas stream, wherein, in the adiabatic methanol pre-converter/guard reactor, the synthesis gas is partially converted to methanol over a heterogeneous methanol catalyst and poisonous impurities are removed from the synthesis gas,

providing a recycle gas stream from a conventional methanol synthesis loop, said recycle gas stream containing partly converted methanol synthesis gas and, optionally, mixing a part of the recycle gas stream with the fresh synthesis gas prior to the preheating and passing of the synthesis gas through the adiabatic methanol pre-converter/guard reactor,

cooling the process gas stream from the pre-converter/guard reactor to a temperature which is suitable for the main converter, and passing the cooled process gas stream to the conventional methanol synthesis loop, and

separating raw methanol from the methanol synthesis loop,

wherein the outlet adiabatic temperature in the pre-converter/guard reactor is controlled by rapid adjustment of the recycle gas stream injected to the adiabatic methanol pre-converter/guard reactor to manipulate the GHSV (gas hourly space velocity) in the pre-converter.

2. Process according to claim 1, wherein the adiabatic methanol pre-converter/guard reactor is sized and designed for the plant full load condition, treating and converting the synthesis gas without risk of catalyst overheating.

3. Process according to claim 1, wherein a safe gas space velocity is established across the reactor in the methanol synthesis loop to avoid overheating of the catalyst.

4. Process according to claim 1, wherein the heterogeneous methanol catalyst is a copper-zinc oxide catalyst on an alumina support.