Pharmaceutical Glass Expansion Projects Land, All-Electric Melting Electrode Demand Follows

Pharmaceutical glass expansion projects have recently been commissioned in succession, and all-electric melting furnaces are the dominant form for borosilicate glass tubing and container lines. Compared with container glass, pharmaceutical glass is held to tighter limits on bubbles, stones and striae, so electrode configuration and operating stability directly affect the yield of conforming product.

How Borosilicate Glass Melts

Borosilicate glass has a high melting temperature and high viscosity, making refining and homogenization harder than with ordinary soda-lime glass. In all-electric melting, heat is generated inside the glass melt and the temperature distribution is relatively uniform, but the demands on electrode layout and power distribution are higher. Excessive local power intensifies convection and actually raises the risk of striae.

Points to Watch in Electrode Configuration

The number, diameter and immersion depth of the electrodes must be set against the furnace tank dimensions and the pull rate. A common problem in expansion projects is copying the parameters of an old line while ignoring the heat-loss conditions and flow-field differences of the new tank. We recommend a thermal calculation at the design stage and retaining adjustment margin during commissioning.

The Procurement Rhythm of a Project

Pharmaceutical glass projects have long construction cycles, and electrodes are usually bought in two batches: the first for ignition and commissioning, the second to top up according to operating results. The first batch should cover the main holes plus spare pieces, so that a single damaged electrode does not hold up the schedule during commissioning.

Records During Qualification

After ignition, record power, current, glass melt temperature and output quality to establish a commissioning baseline. If bubbles increase or local devitrification appears, analyze it against electrode load and the refining agent dosage rather than simply adjusting temperature. Complete records also make it easier to replicate the result in a later expansion.

Coordination with Refractories and Refining

Electrode layout and refractory selection in an all-electric furnace affect each other. The brick around the electrodes carries a high heat flux, and a mismatched grade erodes faster. At the design stage, the electrode scheme and the refractory scheme should be reviewed together so that separately optimized solutions do not clash on site. During commissioning, sampling frequency can be raised to judge whether power distribution is sound from changes in bubbles and striae, and the parameters can then be stabilized step by step.

For product parameters, see the selection notes for this duty; you can also return to the manufacturer information home page.