Method for the preparation of synthesis gas

Abstract

Method for the preparation of synthesis gas based on a combination of the ATR process or partial oxidation of hydrocarbon fee stock using oxygen from the electrolysis of water and an air separation unit to produce the synthesis gas.

Claims

1. Method for the preparation of gas for the synthesis of methanol, comprising the steps of: (a) separating atmospheric air into a separate oxygen containing stream and into a separate nitrogen containing stream; (b) preparing a separate hydrogen containing stream and a separate oxygen containing stream by electrolysis of water and/or steam; (c) partial oxidizing or autothermal reforming in an autothermal reformer at least a part of a hydrocarbon feed stock with at least a part of the oxygen containing stream obtained by the separation of atmospheric air in step (a) and at least a part of the oxygen containing stream obtained by the electrolysis of water and/or steam in step (b) to a process gas comprising hydrogen, carbon monoxide and carbon dioxide; (d) introducing at least part of the separate hydrogen containing stream from step (b) into the process gas from step (c), wherein the resulting mixture of hydrogen in the separate hydrogen containing stream with the process gas from step (c) form the gas for the synthesis of methanol, the gas having a module M, where M=(H.sub.2—CO.sub.2)/(CO+CO.sub.2), of between 1.9 and 2.2; and (e) adjusting the module M by tailoring the amount of hydrogen mixed with the process gas and/or by adding CO.sub.2 to the hydrocarbon feed stock upstream of partial oxidizing or autothermal reforming and/or downstream of step (c).

2. The method of claim 1, comprising the further step of steam reforming, in a heat exchange reformer, a part of the hydrocarbon feed stock not reformed in the autothermal reformer, by indirect heat transfer with part or all the process stream leaving the autothermal reforming step (c).

3. The method of claim 1, comprising the further step of steam reforming, in a heat exchange reformer, a part of the hydrocarbon feed stock not reformed in the autothermal reformer and/or a second hydrocarbon feed stock by indirect heat transfer with part or all the process gas leaving the autothermal reforming step (c), and mixing the heat exchange steam reformed process gas with autothermal reformed process gas.

4. The method of claim 1, comprising a further step of primary steam reforming the hydrocarbon feed stock upstream step (c).

5. The method of claim 1, wherein the hydrocarbon feed stock comprises natural gas, methane, LNG, naphtha or mixtures thereof either as such or pre-reformed and/or desulfurized.

6. The method of claim 1, wherein the separating of atmospheric air in step (a) and/or the electrolysis of water and/or steam in step (b) is powered at least in part by renewable energy.

7. The method of claim 1, wherein the separating of atmospheric air in step (a) is performed by cryogenic separation.

8. The method of claim 1, wherein the module M is between 2 to 2.1.

9. The method of claim 1, wherein the gas for the synthesis of methanol is, in a further step, converted to a methanol product.

Description

EXAMPLE

(1) Comparison Between Conventional ATR and ATR+Electrolysis According to the Invention

(2) TABLE-US-00001 Comparison Table ATR ATR + electrolysis ATR inlet T [° C.] 625 625 (feed) ATR inlet T (Oxidant) 240 240 ATR outlet T [° C.] 1050 1050 ATR inlet P [kg/cm.sup.2 g] 31 31 ATR outlet flow 93934 90667 [Nm.sup.3/h] Feed to ATR H2 [Nm.sup.3/h] 3345 3228 CO2 [Nm.sup.3/h] 698 673 CH4 [Nm.sup.3/h] 24103 23265 CO [Nm.sup.3/h] 16 15 H2O [Nm.sup.3/h] 18442 17801 Oxidant to ATR H2O [Nm.sup.3/h] 131 127 N2 [Nm.sup.3/h] 278 268 O2 [Nm.sup.3/h] 13601 13128 Electrolysis product H2 [Nm.sup.3/h]* 0 2434 O2 [Nm.sup.3/h]** 0 1217 Oxygen from ASU O2 [Nm.sup.3/h] 13601 11911 Product gas H2 [Nm.sup.3/h] 49874 50573 CO2 [Nm.sup.3/h] 4047 3907 CH4 [Nm.sup.3/h] 643 621 CO [Nm.sup.3/h] 20127 19427 H2O [Nm.sup.3/h] 18965 18306 N2 [Nm.sup.3/h] 278 268 Module 1.90 2.00 *Included in product gas **Included in oxidant to ATR

(3) As apparent from the Comparison Table above, the inlet and outlet flow from the ATR is less when applying electrolysis. That is that the ATR reactor is smaller in the method according to the invention. The same is true as regards the ASU.

(4) Another advantage of the method according to the invention is that the required feed amount to the ATR is less and the module of the synthesis gas is improved if the synthesis gas is used for methanol production in the method according to the invention.