Combiblock Energy and Utility Consumption — Air, Power and Water

1. Why utilities differ for a block

A blow-fill-cap combiblock does three jobs in one frame: it blows the bottle, fills it and caps it. That integration changes the utility picture compared with a separate blower plus rinser-filler-capper. The block removes the air conveyor between blowing and filling, which is the largest single air and floor saving, but it still needs high-pressure air for blowing, electrical power for the carousels and controls, and water for CIP and cooling.

The honest framing is that a block is not magic on power — the same blowing, filling and capping work is being done, just in one frame. The savings are in air (no conveyor) and floor and operators, not in a dramatically lower electrical load for equal output. Specifying utilities correctly means sizing each of the three for the rated output, not assuming the block is free to run.

2. High-pressure air for blowing

Blowing is the largest air load on a PET line. A rotary blow moulder consumes high-pressure air proportional to cavity count and bottle size, and air recovery at the blower returns exhausted air to the buffer rather than venting it, which cuts the net draw. The compressor is sized to the net demand after recovery, not to the raw blow volume.

Air quality matters at the machine, not just at the compressor. Moisture carried down a long main produces bottle defects, so the dryer and filtration are specified for the full blowing demand at rated output, and the dew point is checked at the machine rather than in the compressor room. A variable-speed compressor tracks the demand and avoids wasting energy holding pressure when the line is not at full rate.

Compressor sizing is the part most often wrong on a PET site. The figure to size is the net air demand after recovery at rated output, plus a margin for the start of blow and for the format with the largest bottle, not the catalogue blow volume. Undersize the compressor and the line drops below rated output on large bottles; oversize it and the unit runs off-load and wastes power. Confirm the demand and the recovery in writing before the air room is built, because correcting it later means a new machine and a new room.

3. Electrical power

Electrical load is set by the carousels, the blower, the air compressor and the ancillaries. Ask for both the installed power and the running load at your main format, because the supply must cover the running load plus the compressor, with margin for startup. The block's running load for a given output is close to a separate line's, because the work is the same.

Major motors on a variable-speed drive track the load and avoid the energy penalty of running flat out when the line is not at rate. This is cheaper to specify at build than to retrofit, and it shows up in the electricity bill across the line's life, not in the quotation.

Power quality is part of the supply question, not just the installed kilowatts. Voltage tolerance, phase balance and the harmonic load from the drives decide whether the line runs smoothly at the buyer's site, and a soft-start on the blower and compressor limits the inrush that trips a weak supply. Give the supplier the site voltage and the supply capacity in writing, because a line sized for one grid behaves differently on another, and that difference shows up as nuisance trips rather than a clean spec failure.

4. Water for CIP, cooling and treatment

Water demand is set mainly by CIP frequency and any product treatment, not by the block architecture. The block removes the air-conveyor rinse that a separate line has, but it adds no large new water use. Cooling water, where used, is often a closed loop rather than a drain, so the recurring cost is CIP and any treatment, not a large open draw.

Where water is scarce or expensive, rinse water recovery and reverse-osmosis concentrate reuse are worth evaluating at design stage rather than after installation. A block does not change that calculus; it only removes one rinse step. State the water quality and the constraints at quotation so the CIP and any treatment are specified for your site.

Drainage and discharge rules are a site constraint that the utility plan must respect. CIP effluent carries product and cleaning agent, so the drain size, any neutralisation and local limits on discharge are part of the layout, not an afterthought. Where the site has no treatment, a holding tank or a small neutralisation step is specified at design. Raise this early, because rework after the floor is poured and the drains are set is costly and slow.

5. Block vs separate line, by utility

On air and floor the block usually wins; on electrical power the two are close for equal output; on water they are similar once the conveyor rinse is accounted for. The block's advantage is concentrated in the air conveyor it eliminates and the operators it frees, not in a lower process energy.

The utility picture also shifts with bottle size. Larger bottles need more blow air per unit, so the air advantage of the block grows with bottle volume; small light bottles spend a smaller share on blowing and a larger share on the conveyor that the block removes. Read the table against your main format, because the block's edge is largest on the bottles you run most, not on the average bottle in a brochure, and a capacity plan built on the wrong bottle understates the saving.

6. Reducing recurring utility cost

The measures that cut recurring cost are mostly specifiable at build: variable-speed drives on the compressor and major motors, air recovery at the blower, demand control on compressed air, heat recovery where the process allows, and a calibrated CIP cycle that runs the minimum needed rather than a fixed long one. None is large per bottle; all are large per year at volume.

7. What to ask the supplier

Ask for the installed power, the running load at your main format, the net air demand after recovery, the water demand for CIP and treatment, and the floor dimensions. Confirm these in writing before the building is wired and plumbed, because under-sizing any one of them limits output and is costly to correct later.

The block architecture and capacity bands are in combiblock capacity selection, the block vs separate decision is in combiblock vs separate line, and the cost structure behind the utility load is in what drives combiblock price. The block family is in the combiblock range.

Frequently asked questions