Cost Saving VSA Oxygen Generator / VSA Oxygen Plant For Pulp Paper Bleaching

Why a VSA oxygen generator is needed:

1. The transformation of modern pulp bleaching process: from "chlorine" to "oxygen"
Traditional pulp bleaching uses a large amount of chlorine gas (Cl ₂) and hypochlorite. Although this method is effective, it can produce a large amount of highly toxic and difficult to biodegrade pollutants such as adsorbable organic halides (AOX) and dioxins, causing serious harm to the environment.

With increasingly strict environmental regulations, the paper industry has widely adopted bleaching processes such as Elemental Chlorine Free (ECF) and Total Chlorine Free (TCF). One of the core technologies of these two processes is:

Oxygen Delignification: In the early stage of the bleaching process, treating pulp with oxygen (O ₂) under alkaline conditions can remove most of the residual lignin in the pulp. This step can significantly reduce the amount of chemicals used in the subsequent bleaching process.

Chlorine dioxide (ClO ₂) bleaching: As the main bleaching agent in the ECF process, chlorine dioxide has high bleaching efficiency and produces almost no dioxins, with extremely low AOX generation.

The VSA oxygen generator is the key equipment that provides stable and economical oxygen for these new processes.

2.How does VSA oxygen generator work?
VSA stands for Vacuum Swing Adsorption. The working principle is briefly described as follows:

Adsorption: The blower sends ambient air into an adsorption tower containing porous adsorbents (such as zeolite molecular sieves). The adsorbent preferentially adsorbs nitrogen (N ₂) from the air under high pressure, while allowing oxygen (O ₂) to pass through.

Output: In this way, oxygen rich gas with a purity of about 90% -95% can be obtained at the outlet of the tower.

Regeneration: Then, by vacuuming, the adsorbed nitrogen and other impurities are desorbed and discharged back into the atmosphere to regenerate the adsorbent and prepare for the next cycle.
Usually, two or more adsorption towers alternate between adsorption and regeneration steps to achieve continuous production of oxygen.

3.Why does the bleaching process specifically require a VSA oxygen generator?
a. Provide oxygen for the oxygen delignification section
This is the most direct and primary requirement. The oxygen delignification unit requires a large amount of oxygen consumption (usually 20-30 kilograms of oxygen per ton of pulp). VSA oxygen concentrators can:

On site Generation: Directly producing oxygen within the factory area avoids the transportation and storage costs of liquid oxygen.

Reduce production costs: Although equipment investment is required, in the long run, the cost of producing oxygen in-house is much lower than purchasing liquid oxygen externally. Electricity is the main cost, while VSA technology has relatively low energy consumption.

Stable and reliable supply: It can continuously and stably provide oxygen of the required purity and pressure according to the needs of the production line.

b. Used for manufacturing chlorine dioxide (ClO ₂)
Chlorine dioxide (ClO ₂) is the most important bleaching agent in modern ECF bleaching. It is extremely unstable and cannot be transported over long distances. It must be prepared on-site in the paper mill. The current mainstream efficient preparation methods (such as R8, SVP) ®/ LITE and other processes require a chemical reaction between sodium chlorate (NaClO3), methanol (or hydrogen peroxide), and sulfuric acid (H ₂ SO ₄) in the reactor. In this reaction process, high-purity oxygen is required as the raw material gas or carrier gas.

The oxygen purity produced by VSA oxygen concentrator (93% ±) fully meets the requirements of chlorine dioxide preparation system, and is also the lowest cost and most reliable oxygen supply solution.

Summary
The need for VSA oxygen generators for pulp and paper bleaching is fundamentally a result of the industry's transition towards environmentally friendly bleaching technology

Environmental Protection Requirements: Eliminate the severe pollution caused by chlorine bleaching and adopt clean technologies such as oxygen delignification and chlorine dioxide bleaching.

Economic demand: These new technologies require a large amount of oxygen, and VSA oxygen concentrators can reliably and continuously produce oxygen on site at the lowest operating cost.

Process requirements: Both oxygen delignification reactors and chlorine dioxide preparation systems rely on stable oxygen sources to operate efficiently.

Therefore, VSA oxygen generator have become an indispensable core supporting equipment for modern and environmentally friendly pulp mills. They not only help paper mills meet environmental requirements, but also enhance market competitiveness by reducing production costs.