Cryst-O-Dry® infrared rotary crystallizer and dryer for PET
Crystallizes and dries PET bottle flake and preform grinding in one continuous pass: 15–25 minutes instead of the 5–6 hours a conventional crystallizer and dryer need.
Also written crystalliser, the UK spelling.
Key features
One machine, one step
Crystallization and drying in a single continuous pass. Flake and preform grinding go in as they are and come out crystalline and dry, with no desiccant to buy or replace.
Inside-out infrared heating
Shortwave infrared needs no transfer medium. The granule and its internal moisture are heated together while the surrounding air stays at ambient.
Patented rotary drum
An internal helix and tumbler fins keep every particle moving through the heat for its whole residence time.
Three heating zones
The temperature profile along the drum is set to the material: its moisture and its crystallization requirement.
No desiccant
No desiccant bed to buy, regenerate or replace, and none for the volatiles from post-consumer flake to poison.
Quick to clean
The heater column and cooling system pull out on a slide. A continuous air shield keeps PET fines off the lamps while running.
Cryst-O-Dry® vs conventional systems
- Crystallizer, about 1 h
- Dryer at 150–180 °C, 4–5 h
- Energy intensive
- Space intensive
- Non-uniform heating
- Desiccant contamination
- Seasonal variability
- Difficult to clean
- Cryst-O-Dry drum, 15–25 min
| Parameter | Conventional system | Cryst-O-Dry |
|---|---|---|
| Steps required | 2 (crystallizer + dryer) | 1 |
| Total processing time | 5–6 hours | 15–25 minutes |
| Moisture reduction | 5,000–6,000 ppm → ~300 ppm | 5,000–6,000 ppm → 300–400 ppm |
| Heating principle | Outside-in (air medium) | Inside-out (no medium) |
| Desiccant required | Yes | No |
| Footprint | Large (2 machines) | Compact (1 machine) |
| Energy efficiency | Lower | Higher |
The process is continuous. Material is fed and discharged without stopping, and throughput is set by drum speed and residence time — the figures are in the specification below. Conventional processing times are established industry practice, consistent with A.B. Plastech's own process comparison data.
Limitations of conventional crystallizer–dryer systems: full explanation
The standard industry method uses 2 separate machines and 2 separate steps. A crystallizer — a hopper with an agitator — heats amorphous PET through its glass transition to achieve crystallization, taking approximately 1 hour. The crystallized material is then transferred to a dryer — hot air, desiccant wheel, compressed air, membrane, or vacuum — and dried at 150–180 °C, taking a further 4–5 hours.
Total processing time before the extruder can run: 5–6 hours.
Energy intensive
The dryer heats air first. The air then heats the material from the outside in — an inefficient transfer of energy with losses at every step.
Space intensive
2 machines, 2 hoppers, transfer equipment — a large footprint.
Non-uniform heating
Hot air does not penetrate the material evenly; surface and core temperatures differ.
Desiccant contamination
Post-consumer PET flakes release volatiles during drying that contaminate and degrade desiccant beds, requiring additional treatment and replacement.
Seasonal variability
Hot air dryer performance is directly affected by ambient humidity. Results vary between summer and winter, even on the same line.
Difficult to clean
Multiple vessels, transfer points and air circuits make changeover and maintenance time-consuming.
How it works
- Heater warms a large volume of air
- Hot air heats the granule surface
- Heat creeps slowly to the core
- Shortwave infrared goes straight into the granule
- Core and internal moisture heat together
- Air stays at ambient; moisture is driven out
How it works: full explanation
Cryst-O-Dry combines crystallization and drying into a single step, using shortwave infrared radiation in a continuously moving patented rotary drum.
In a conventional dryer, air is the transfer medium: energy must first heat the air, which then heats the surface of the material, which then slowly conducts heat toward the core. This outside-in process is inherently slow. Infrared radiation requires no medium. Shortwave IR penetrates directly into the material and acts at the molecular level, heating from the inside out. The bulk of the granule and any internal moisture are heated simultaneously. The surrounding air stays at ambient temperature, and the temperature gradient between the heated granule interior and the cooler surface drives moisture outward and away.
What takes 5–6 hours conventionally takes 15–25 minutes in Cryst-O-Dry.
The rotary drum
Material moves continuously through the patented rotating drum, fitted with an internal helix. Tumbler fins ensure every particle is exposed to uniform infrared heating throughout its residence time. No agglomeration, no hot spots, no stagnant zones.
Multiple heating zones
Precise control of the temperature profile across the drum length, matching the process to the material's specific moisture content and crystallization requirement.
“The delivered energy is applied directly to the material with no other transfer medium … this is the driving force that drives moisture to come out faster than in convection drying.” — Discover Polymers, 2025, 2:1, Springer.
Achievable moisture levels
Moisture levels and moisture after discharge: full explanation
15–25 minutes brings 5,000–6,000 ppm down to 300–400 ppm. For most PET processing that is the job done.
Hold the discharged material in an insulated buffer hopper for 30–45 minutes and it falls further, on the material's own exothermic heat, with no additional energy at all.
Where the specification calls for under 50 ppm, a dehumidifier placed in conjunction with the machine will reach it. Tell us the number you have to hit and we will tell you what the line needs.
There is no separate crystallizing step to arrange first. Flake and preform grinding go in as they are, and come out crystalline and dry.
Moisture reduction after discharge
The material finishes the job
PET crystallization is an exothermic process — the material generates its own heat as it crystallizes. This is a property of the chemistry of PET. When Cryst-O-Dry completes its cycle and crystallized material is held in open containers, the exothermic reaction continues, driving residual moisture further downward without any additional energy input. Moisture levels reduce naturally from approximately 300 ppm toward 150 ppm through the material's own thermal behaviour.
Hot granules after transport
Freshly crystallized PET granules retain heat and continue their exothermic reaction during transit. If your material arrives warm after a long journey, that is confirmation the crystallization succeeded. The heat comes from inside the material itself.
Operating cost
Crystallizing and drying PET bottle flake takes 0.22 kWh per kilogram, and preform grinding 0.12 kWh per kilogram, both within ±5%. Put those figures against your own tariff to get the cost per kilogram at the rate you actually pay.
Against a conventional agitator crystallizer followed by a dehumidifying dryer, that is 20–30% less energy for the same material. And there is no desiccant to buy, regenerate or replace — which also means the volatiles that post-consumer flake gives off during drying have no desiccant bed to poison.
The infrared lamps are the only consumable. They last 5,000 hours and cost ₹1,500 to ₹2,500 each; the machine carries 3 zones with 3–6 lamps in each, configured for the duty. A full set replaced at the end of its life, spread across the material it processed in those 5,000 hours, works out at roughly 1–5 paise per kilogram. The lamps are the only scheduled replacement on the machine.
They are standard lamps, widely available from any supplier.
Technical specifications: IRD1500
| Model | IRD1500 |
| Process | Continuous |
| Drum speed | Variable, VF drive |
| Volumetric capacity | 133–333 litres/h, according to residence time |
| Throughput | litres/h × bulk density, capped by heating load ÷ energy per kg — see the table below |
| Drying temperature | Up to 180 °C |
| Energy, PET bottle flake | 0.22 kWh/kg ±5% |
| Energy, preform grinding | 0.12 kWh/kg ±5% |
| Heaters | Shortwave infrared, 2,000 W, 3 zones, 3–6 per zone to requirement |
| Heating connected load | 18–36 kW |
| Lamp life | 5,000 hours |
| Drum | SS-304, insulated. Contact parts SS-304 |
| Drum dimensions | 1500 mm long, 750 mm inside diameter |
| Drum drive | 0.75 kW (1 hp), assisted power cooling |
| Cooling and exhaust blowers | ebm-papst |
| Control | PLC, HMI, switchgear and VF drive — Siemens / Schneider |
| Power supply | 400 V AC, 50 Hz |
| Overall dimensions | 3000 × 1250 × 1900 mm (L × W × H) |
| Bought-out components | Bearings SKF, NTN, Nachi, NBC · gearbox Premium, Bonfiglioli, PBL · motors Roto-motive, Siemens, ABB — or equivalent |
| Intellectual property | Indian Patent 297057 — grant and current standing below |
Throughput by residence time
Residence time is the operator's choice, set on the drive. Run faster for more output; run slower for a drier result. What your material needs depends on its moisture and its form, and we set it for your material when the machine is commissioned.
| Residence time | Volumetric | At 0.4 kg/litre | At 0.6 kg/litre |
|---|---|---|---|
| 10 minutes | 333 litres/h | 133 kg/h | 200 kg/h |
| 15 minutes | 222 litres/h | 89 kg/h | 133 kg/h |
| 20 minutes | 167 litres/h | 67 kg/h | 100 kg/h |
| 25 minutes | 133 litres/h | 53 kg/h | 80 kg/h |
Every figure in that table is inside the heating load. Where your bulk density is not 0.4 or 0.6, multiply the volumetric rate by it — then check the answer against heating load ÷ energy per kilogram, because a dense material can ask for more heat than the lamps can give. The output is the lower of the two.
Throughput and energy figures are for PET. Bulk density and the moisture you have to reach decide which line of the table applies — tell us the material and the target and we will quote the rate. All specifications are subject to change without notice to improve reliability, function or design.
Technical background: crystallizing and drying PET
Recycled and scrap PET flake is amorphous and has picked up moisture in storage and transport. There are three ways to take it to the extruder:
Cryst-O-Dry crystallizes and dries together, in one pass of 15–25 minutes.
Technical background: full explanation
PET is a highly hygroscopic resin — it absorbs moisture from the atmosphere during transportation and storage. When moisture-laden PET is processed at melt temperatures of 260 °C and above, the water hydrolyses the polymer chains, causing loss of intrinsic viscosity, an increase in carboxyl groups, colour change, and irreversible deterioration of the final product.
Post-process and recycled PET present an additional challenge. Unlike virgin PET, which is semi-crystalline, post-consumer and scrap PET is amorphous. Amorphous PET cannot simply be dried: heated through its glass transition temperature of approximately 80 °C, amorphous particles soften and agglomerate, forming clumps that choke conventional drying hoppers and disrupt the process.
The correct sequence is therefore crystallize first, then dry. Only crystalline PET can be safely heated to the drying temperature of 160 °C and above without agglomeration.
References: Ind. Eng. Chem. Proc. Des. Dev., 1977, 16(3), 341–346 · “Beyond processing methods: the impact of the drying technique on PET performance,” Discover Polymers, 2025, 2:1, Springer.
Cleaning and maintenance
The heater column and the cooling system pull out on a slide. That opens the drum for cleaning by hand in a short stop, and it restarts immediately afterwards, so cleaning at a material change is practical.
How often depends on the input material and the room it runs in. Washed flake from a good line asks for very little; dusty reground material asks for more.
Dust on the lamps themselves is dealt with differently. A continuous air supply through the heater bank holds a shield in front of the lamps, so PET fines do not settle on them while the machine is running.
Installations
Cryst-O-Dry is commissioned, operational and producing results, in India and in export markets. A machine supplied to Nepal in 2020 is still in production. Details of installed references are available on request.
Launch at IndiaPlast 2019
At IndiaPlast 2019, the Cryst-O-Dry exhibit was visited by leading drying systems experts from the United States, desiccant drying industry leaders from India, and PET recycling specialists from Europe.
Patent
| Patent | Indian Patent 297057 |
| Title | Modular Drum and Method of Manufacturing Thereof |
| Filed | 21.01.2017 |
| Granted | 24.05.2018 |
Where this page calls the drum patented, that is the grant above. Searchable on the Indian Patent Office public database.
How the process is validated
Infrared crystallization and drying is an established process: calibrated, variable infrared heat applied to continuously agitated material produces a repeatable, controlled result.
We will take you through the process, the settings for your material and the published references before you order, and stay with you after commissioning.
Scientific references
- McKinney, D.E. et al. Ind. Eng. Chem. Proc. Des. Dev., 1977, 16(3), 341–346. doi.org/10.1021/i260063a017
- “Beyond processing methods: the impact of the drying technique on PET performance.” Discover Polymers, 2025, 2:1. Springer. link.springer.com/article/10.1007/s44347-025-00013-9
- Linseis Messgeräte GmbH. DSC application data — PET thermal analysis. linseis.com/en/applications/polymers/chip-dsc-10-polymers-pet/
Tested with your material before dispatch
We do not keep a demonstration machine. Every machine is built against an order. When yours is complete and before it leaves our works, we run your material through it, to your parameters. What you assess is the machine you are buying.
Questions buyers ask
What does Cryst-O-Dry do?
It crystallizes and dries PET bottle flake and preform grinding in one continuous pass: 15–25 minutes instead of the 5–6 hours a conventional crystallizer and dryer need.
How dry is the flake after one pass?
Flake or regrind that arrives at 5,000–6,000 ppm moisture leaves at 300–400 ppm after 15–25 minutes. Figures are for PET. Your result depends on the material and its starting moisture.
How much energy does it use?
0.22 kWh/kg on PET bottle flake, which is 20–30% less energy than the two-step route.
Does it need a desiccant?
No. There is no desiccant bed to buy, regenerate or replace.
How is infrared different from a hot-air dryer?
Shortwave infrared needs no transfer medium. The granule and its internal moisture are heated together while the surrounding air stays at ambient. A conventional dryer heats air first, and the air then heats the material from the outside in.
How is it cleaned?
The heater column and cooling system pull out on a slide, and a continuous air shield keeps PET fines off the lamps while it runs.
Is Cryst-O-Dry patented?
The rotary drum is covered by Indian Patent 297057, granted in 2018.
Where is it installed?
In India and in export markets. A unit supplied to Nepal in 2020 is still in production.
How do I get a quote?
Call or WhatsApp +91 94160 55854, or send the quote request on the Contact page. Tell us the material, how much per hour and when you need it. We read every complete enquiry ourselves.
Enquire about Cryst-O-Dry®
Send us your material, its starting moisture, the moisture you need and the throughput. We will recommend the configuration and quote.
A.B. Plastech · Modern Industrial Estate, Bahadurgarh, Haryana
pawar@abplastech.co.in
abautomech@hotmail.com