Operating CV-Lines Responsibly

Extract byproduct effectively and responsibly throughout the cable-making process. Not only will your bottom line benefit but so will the environment.


Byproduct formation during the Continuous Vulcanizing process has been primarily a cable quality issue, but in this day and age, it has equally become an environmental one. Maillefer offers a modern Byproduct Separation (BPS) system that couples to extrusion lines seamlessly. Here is an optimal system for extracting byproducts in a responsible fashion.

 

Byproduct extraction improved

Medium voltage, high voltage, and extra high voltage cables are largely XLPE insulated and produced on CVlines. The cross-linking method employed on horizontal (HVC), vertical (VCV), or catenary (CCV) CV-lines is peroxide based. Unwanted byproducts result from this process. If insufficiently extracted, they will cause cable quality issues. It is best to handle byproduct removal carefully and in a systematic manner.

Typical quality issues on the outer cable surface due to byproducts

 

Improved byproduct separation and collection during the CV process has multiple benefits directly on the product and also on the neighboring environment:

 

Maintaining optimal production conditions

  • Stable cooling and heating capacity
  • Cleaner cooling water and cooling gas
  • Fewer quality issues with produced cables and scrapped cables

 

Reduced maintenance work

  • Less curing tube & heat exchanger cleaning needed
  • Vulcanizing equipment and instruments increased reliability in the operation
  • Decreased maintenance costs

 

Environment and Sustainability

  • Cleaner exhaust nitrogen gas from the CV-line to the atmosphere
  • Less wastewater
  • Better controlled by-product collection.

 

The entire BPS loop

Maillefer has continuously developed the byproduct removal process as an integral part of CV-line development. Nowadays, we offer several individual components for byproduct removal as a part of an overall approach. The goal is to secure and maximize the customer’s production potential and to minimize the scrap cable produced.

 

The schema of the BPS loop in a CV process

The BPS with the Gas ReHeater (GRH) component is the most effective and the most essential part of a byproduct extraction system. The BPS separates the decomposed crosslinking byproducts by condensing associated particles found in the nitrogen flow. The condensate is collected at the bottom of the unit. The BPS is equipped with a time-controlled valve, which purges the liquid waste collected towards holding tanks.

 

By-Product Separator (BPS)

The byproduct separator, wherein cold water is circulating in cooling pipes, inside star shaped profiles which cool down the gas temperature. The cross-linking byproducts are removed from the gas flow as condensate to the metallic surfaces (star shape profile). The outlet temperature is regulated by control valve.

Hot gas (180-220°C) drops in temperature (40-60°C) as it exits the BPS

 

The GRH continues by increasing the temperature of the gas returning from the BPS. It is located in the same gas circulation loop as the BPS. The heated gas is injected into the second to last curing tube, at the same temperature as the nitrogen within the curing tube.

 

Gas Re-heater (GRH)

Clean gas (60°C) is heated (200-350°C) by the GRH before returning to the cure tube

 

Both BPS and GRH are available as upgrades, ready to integrate into any existing CV-line, whether a Maillefer line or another. We provide three main upgrade types for existing CV-lines in order to improve byproduct extraction.

 

The complete byproduct removal system

If the CV-line is not equipped with a byproduct removal system, a complete BPS system with GRH is proposed. A holistic approach is used by studying the byproduct removal process for the CV in place, and a full system is engineered accordingly.

 

The partial byproduct removal system

If the line is already equipped with BPS but without a GRH, it is possible to improve the byproduct separation system by integrating the new component into the existing circulation loop and BPS.

 

Selective byproduct removal system replacement

If the existing CV-line is already equipped with a byproduct removal system that gives undesired results, selected elements are replaced accordingly, which may include Maillefer’s BPS and GRH.

A clean BPS unit before by-product extraction (left) and the same unit afterward showing successful residue collection (right)

 

High cable value to consider

CV cables are high-added-value products. Sacrificing cable quality due to insufficient byproduct removal directly affects the bottom line, not to mention the product image. Do not hesitate further to extract your crosslinking byproducts effectively and responsibly. We stand ready to offer a solution that is tailor-made for your specific conditions.

 

Roger Möller, VP Services
roger.moller@maillefer.net

 

Topics: Extrusion, Wire & cable manufacturing, Pipe & tube manufacturing, sustainability, Automation, quality, process control, environment, high voltage, byproduct

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