Hydroprocessing Plant Hydrogen Integration Reduces Natural Gas Use

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Solution Overview

Problem

The high hydrogen consumption in hydrotreating processes for producing diesel, jet fuel, and naphtha from renewable feedstocks leads to increased natural gas usage and carbon dioxide emissions, as existing methods require significant hydrocarbon feedstocks for hydrogen production.

Innovation Solution

An integrated process that utilizes two recycle streams from a hydroprocessing and separation stage to minimize natural gas consumption, where a hydrogen-rich stream is recycled back to the hydroprocessing unit and an off-gas stream is processed to produce additional hydrogen, reducing energy consumption and carbon footprint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high amount of hydrogen gas is consumed in hydrotreating renewable feedstock, then the hydrocarbon product can be produced effectively, but natural gas consumption and CO2 footprint increase significantly

Engineering Contradiction:

Improvehydrocarbon product productionVSAvoidnatural gas consumption

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent combines the hydrotreating process with a hydrogen production unit into an integrated system. The hydrogen production unit is directly coupled with the hydrotreating unit, allowing hydrogen to be produced on-site from the off-gas stream and fed back to the hydrotreating process, thereby reducing external natural gas consumption while maintaining productivity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent converts the off-gas stream containing CO and CO2, which would normally be waste or harmful emissions, into a valuable hydrogen source. Through water-gas shift reaction and methanation, the off-gas is transformed into hydrogen-rich gas that feeds the hydrotreating process, turning a liability into a benefit and reducing natural gas dependency.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Quantity of substance

If hydrogen production unit uses more hydrocarbon feedstock, then hydrogen supply for hydroprocessing is sufficient, but CO2 emissions increase

Engineering Contradiction:

Improvehydrogen supplyVSAvoidCO2 emissions

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent utilizes the off-gas stream from the hydrotreating process, which contains CO and CO2, as feedstock for the hydrogen production unit. Through water-gas shift reaction (CO + H2O → CO2 + H2) and subsequent processing, the harmful CO and CO2 are converted into useful hydrogen, eliminating waste emissions while providing sufficient hydrogen supply.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

Instead of discarding the off-gas stream as waste, the patent recovers valuable hydrogen from it through a series of processing steps including water-gas shift reaction, CO2 removal, and PSA purification. This recovery process converts what would be harmful emissions into a useful resource, reducing both waste and CO2 footprint.

Inventive Principle:

Principle #34Discarding and recovering

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach achieves a significant reduction in natural gas consumption by 40-90% and decreases carbon dioxide emissions, while enabling a smaller hydrogen production unit and lower operational costs.

Implementation Method 1

The hydrogen generation step includes the use of steam methane reformer

Methodology Applied

Scientific EffectSteam reforming:

Implementation Method 2

Gas-water shift reaction: CO2+H2↔CO+H2O

Methodology Applied

Scientific EffectWater gas shift reaction:

Implementation Method 3

a PSA unit for hydrogen purification

Methodology Applied

Scientific EffectPressure swing adsorption: Pressure Swing Adsorption

Implementation Method 4

During the hydrotreating of renewable feedstock, the oxygen is mainly removed as H2O, which gives a paraffinic fuel

Methodology Applied

Scientific EffectHydrodeoxygenation:

Implementation Method 5

Oxygen can also be removed by dicarboxylic pathway, which generates CO2 instead of H2O

Methodology Applied

Scientific EffectDecarboxylation:

Implementation Method 6

Methanation: CO+3H2↔CH4+H2O

Methodology Applied

Scientific EffectMethanation:

Data Source

PatentUS11802247B2Process and plant for producing hydrocarbons with reduced CO<sub>2</sub>-footprint and improved hydrogen integration

Publication Date: 2023.10.31 HALDOR TOPSOE AS

AI summary

Process and plant for producing hydrocarbon products from a feedstock originating from a renewable source, where a hydrogen-rich stream and on off-gas stream comprising hydrocarbons is formed. A portion of the hydrogen-rich stream is used as a recycle gas stream in a hydroprocessing stage for the production of said hydrocarbon products, and another portion may be used for hydrogen production, while the off-gas stream is treated to remove its H2S content and used as a recycle gas stream in the hydrogen producing unit, from which the hydrogen produced i.e. make-up hydrogen, is used in the hydroprocessing stage. The invention enables minimizing natural gas consumption in the hydrogen producing unit as well as steam reformer size.