Method of suppressing metal contamination of synthesis gas production apparatus
A synthesis gas production apparatus (reformer) to be used for a synthesis gas production step in a GTL (gas-to-liquid) process is prevented from being contaminated by metal components. A method of suppressing metal contamination of a synthesis gas production apparatus operating for a GTL process that includes a synthesis gas production step of producing synthesis gas by causing natural gas and gas containing steam and/or carbon dioxide to react with each other for reforming in a synthesis gas production apparatus in which, at the time of separating and collecting a carbon dioxide contained in the synthesis gas produced in the synthesis gas production step and recycling the separated and collected carbon dioxide as source gas for the reforming reaction in the synthesis gas production step, a nickel concentration in the recycled carbon dioxide is not higher than 0.05 ppmv.
1. A method of suppressing metal contamination of a synthesis gas production apparatus operating for a GTL (gas-to-liquid) process, comprising:
a synthesis gas production step of producing synthesis gas by causing natural gas and gas containing steam and/or carbon dioxide to react with each other for reforming in a synthesis gas production apparatus;
a step of separating and collecting carbon dioxide contained as an unreacted source gas or an intermediary product in the synthesis gas produced in the synthesis gas production step by introducing the synthesis gas into a carbon dioxide absorption apparatus having therein a bed of a nickel-containing filling material and bringing the synthesis gas into contact with an aqueous solution of amines in the carbon dioxide absorption apparatus;
a Fischer-Tropsch oil manufacturing step of manufacturing Fischer-Tropsch oil by subjecting the synthesis gas from the step of separating and collecting carbon dioxide to a Fischer-Tropsch reaction and subsequently isolating a gaseous product from the Fischer-Tropsch oil; and
an upgrading step of manufacturing various hydrocarbon oils by subjecting the Fischer-Tropsch oil manufactured in the Fischer-Tropsch oil manufacturing step to hydrotreatment and distillation,
wherein the separated and collected carbon dioxide is recycled to the synthesis gas production step,
wherein the separated and collected carbon dioxide potentially contains nickel carbonyl which is generated by reaction of carbon monoxide contained in the produced synthesis gas and nickel eluted from the nickel-containing filling material into the aqueous solution of amines in the step of separating and collecting carbon dioxide, and
wherein the separated and collected carbon dioxide is introduced into a nickel carbonyl adsorption apparatus having an adsorbent containing active carbon as a main component at a temperature between 250° C. and 400° C. under a pressure between 0.02 MPaG and 3.0 MPaG and a gas hourly space velocity between 500 h −1 and 3,000 h −1 and subsequently introduced into the synthesis gas production apparatus, whereby a nickel concentration in the recycled carbon dioxide that has exited the adsorption apparatus is not higher than 0.05 ppmv.
2. The method according to claim 1 , wherein the aqueous solution of amines contains a tertiary amine.
3. The method according to claim 1 , wherein the gas supplied to the synthesis gas production apparatus shows a H 2 O/C mol ratio between 0.1 and 3.0 and/or a CO 2 /C mol ratio between 0.1 and 3.0.