Cyclic separation

Advanced design tools for pressure swing adsorption

Cyclic separation processes such as pressure-swing adsorption are fundamental to high-purity gas production.

However because of the cyclic – and thus inherently dynamic – nature of the operations, they are very difficult to design, with the numerical challenges of solving such systems poorly catered for by current simulation software.

gPROMS ProcessBuilder provides advanced modelling capabilities that can solve cyclic separation systems rapidly and robustly, allowing engineers to answer design and operational questions based on accurate prediction.

Challenges

Engineers face many challenges when designing and operating adsorption systems:

  • How do you determine the cyclic steady-state (CSS) – an essential requirement in order to make informed design decisions about bed dimensions, operating conditions, cycle times, adsorbent, and so on?
  • How do you scale-up and scale-down designs, as systems typically need to be purpose-built taking into account feedstock, purity and flowrate requirements?
  • How do you choose between candidate adsorbents for a given separation requirement and process configuration?
  • How can you minimise pilot plant testing in order to be able to implement changes as rapidly and cost-effectively as possible?
  • What is the optimum number of beds in order to minimise capital costs while meeting requirements for a given separation?
  • Is single-bed or multiple-bed configuration better for the required separation? What depth of beds is requried in a multiple bed arrangement?

The complexity of the calculations required mean that there are very few tools that can help in these crucial decisions.

How gPROMS ProcessBuilder can help

Because gPROMS ProcessBuilder is built on PSE's gPROMS equation-oriented dynamic modelling platform, it can handle challenging numerical solution aspects such as fast transients, discontinuities and flow reversal with ease.

In addition, ProcessBuilder's state-of-the art adsorption libraries allow easy construction and specification of high-fidelity adsorption flowsheets. See the diagram below for a quick overview of some of the built-in capabilities.

ProcessBuilder for adsorption – features & advantages

There are many benefits from having a robust and accurate model of a pressure swing adsorption process. With a ProcessBuilder model you can:

Determine cyclic steady state

Modelling adsorption systems in ProcessBuilder enables you to easily calculate the cyclic steady state, in order to determine product purity, energy consumption, bed dimensions, cycle times and other key design parameters – enabling you to speed up design.

Minimise the number of beds

With the information from the cyclic steady state analysis, you can determine the minimum number of beds required to achieve your separation – minimising the capital and operating cost of your process.

Prove new adsorbents

With a rigorous model of your process you can rank and screen new adsorbent candidates for performance, validate vendors' claims, and choose the lowest cost adsorbent suitable for the task.

Scale up or down easily

A rigorous model will allow you to scale your process up or down, with the minimum of pilot plant testing.

Single or multiple beds?

With a rigorous bed model you can investigate different bed configurations and test different materials, to minimise CAPEX and OPEX or maximise performance.

Test emergency scenarios

What happens to performance when a valve doesn't close properly? Establish safety, integrity or control procedures on failure.

What does gPROMS ProcessBuilder provide?

gPROMS ProcessBuilder provides a unique set of capabilities. Some of the key aspects are shown in the diagram below.

Adsorption in gPROMS ProcessBuilder

The model solution is underpinned by gPROMS platform’s advanced dynamic simulation capabilities, which provide robust and relatively rapid solution of the complex problem.

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