Gas 2024 Issue

Summary of gas separation technologies

Features H₂ purity

Adsorption

Cryogenics

Legacy membranes

Divi-H

99.9%+ 75-92%

90-96% 90-98%

90-98% 85-95%

90-99.95%

H₂ recovery

90-95%

Feed pressure

10-40 barg

>5-75 barg

20-160 barg

Feed temperature Feed H₂ content H₂ product pressure

50-80C

<0C

20-80C

20-150C >25-80%

>40%

>10%

>25-50%

Feed pressure 1-225 K Nm³/hr

Feed/low pressure 10-75+ K Nm³/hr

<< Feed pressure

< Feed pressure

H₂ capacity

Modular

Pretreatment requirements

Depends on adsorbent

CO₂, H₂O removal Liquid HCs

CO₂, H₂S, acid gas removal

Minimal (liquid separation only)

Multiple products

Capital cost

Medium Moderate

High Good

Low

Scale economics

Modular

Table 1

continuously without the need for intermittent cycles or regeneration steps, providing a steady supply of separated gases. The Divi-H membrane modules allow for ‘hot swap - ping’, where a fibre cartridge is replaced within a single module while the system continues operating. y Simplicity and ease of operation: Membrane systems are simple to operate and require minimal supervision. They do not involve complex processes like cryogenic cooling or adsorption-desorption cycles. z Fast start-up and shutdown: Membrane systems can quickly reach operational conditions, reducing downtime during start-up and shutdown. { Versatility: ROG streams can change compositions, flow rates, and pressures quickly. Membrane separation can handle a wide range of gas streams with varying com - positions and flow rates. Membrane separation requires significantly lower energy consumption compared to cryo or pressure swing adsorption separation | Minimal maintenance requirements: Membrane sys - tems have no moving parts, resulting in lower maintenance and operational costs. } Reduced environmental impact: Membrane separation avoids the need for cryogenic fluids or chemical adsor - bents, minimising the release of harmful substances into the environment. ~ Cost-effectiveness: Membrane separation offers a cost-effective solution for gas separation due to lower cap - ital and operational expenses, shorter project lead times, and reduced utility requirements. ROG sources The hydrogen balance throughout a refinery can be com - plex, with multiple source locations, uses, and points of

It can operate in environments rich in H₂S and acidic gases that would cause legacy membranes to fail and operate at temperatures up to 150°C, whereas prior tech- nology was limited to 50-80°C. These improvements in the performance of polymeric hydrogen separation membranes allow for significant use-case expansion within refinery operations. Table 1 gives a summary of the different gas separation technologies available to refiners. Part 1 of this article will preview sample ROG streams produced from several types of units for their potential sep - aration and purification via Divi-H. The membrane demon - strates separation costs as low at $0.015/kg hydrogen separated, with returns on investment (ROIs) exceeding 2,400% over the life of the product when compared to grey hydrogen production. Part 2 in PTQ Q3 2024 will analyse its effectiveness in hydrotreaters and hydrocrackers. Membrane technology advantages There are several qualitative benefits to leveraging mem - brane technology for gas separation, of which not all will be considered in the following analysis: u Energy efficiency : Membrane separation requires sig - nificantly lower energy consumption compared to cryo or pressure swing adsorption (PSA) separation. The driving force for separation is provided purely by the feed gas pressure. v Compact and modular design: Membrane systems have a smaller footprint and are easily scalable, making them suitable for applications where space is limited or modular expansion may be required. This scalability allows for great flexibility for ROG stream applications, as the flow rates and composition of the ROG can change quickly and vary greatly. w Selectivity and design versatility: While cryogenic and PSA separation are limited in their hydrogen purity options, membrane systems can be designed for a massive range of desired purities, pressure drops, and recoveries. If the purity of the hydrogen product stream does not need to be at 99.95%+, the economics of membrane separation are difficult to beat. x Continuous operation: Membrane separation operates

Gas 2024