Position in the Production Line Stage 03–04

01
Raw Material Prep
02
Reaction
03–04
Stripping & Drying ← Here
05
Blending & Sieving
06
QC & Packaging

The Steam Stripping Dryer is installed after the etherification reaction and before the final washing and crushing stages. It performs two critical functions simultaneously: stripping residual solvent (typically isopropanol or ethanol) from the crude CMC or PAC, and drying the product to the target moisture content — in a single, continuous operation.

The stripped solvent vapor is recovered via the integrated vacuum system and condensed for reuse in the process, making this equipment central to both product quality and the economics of solvent recovery.

How It Works

The wet CMC or PAC material from the reaction stage is fed into the cylindrical vessel, where it is agitated by a rotating stirrer at controlled speed. Steam is supplied to the jacket surrounding the vessel — heating the material indirectly without direct contact, preserving product purity and preventing localized overheating.

A water ring vacuum pump maintains negative pressure inside the vessel, lowering the boiling point of the solvent and enabling effective stripping at temperatures well below the product's degradation threshold. The solvent-laden vapor is drawn off through the vacuum system, condensed, and recovered for reuse.

Key Design Features

  • Indirect steam heating via jacket — no direct contact between steam and product. Jacket designed for steam pressure up to 1.0 MPa at 180°C, ensuring stable, controllable heat input across all capacity ranges.
  • Duplex stainless steel inner vessel — product-contact surfaces (inner cylinder, agitator, inlet/outlet flanges) fabricated in duplex stainless steel or SUS316L for corrosion resistance and product purity compliance.
  • Vacuum system for low-temperature stripping — water ring vacuum pump maintains controlled negative pressure inside the vessel, enabling efficient solvent removal at reduced temperatures to protect heat-sensitive product grades.
  • Explosion-proof drive system — variable frequency explosion-proof motor with hard-face gearbox drives the agitator at controlled speed, ensuring uniform mixing of the product bed throughout the drying cycle.
  • Integrated solvent recovery — stripped solvent vapor is directed to the condensation system for recovery and reuse, significantly reducing raw material costs and environmental impact.
  • Designed to Chinese pressure vessel standards — vessel designed and manufactured in accordance with Chinese pressure vessel regulations (GB standards), with full documentation available for export projects.
  • Manual level control — material level inside the vessel is regulated via a manual control valve, giving operators direct control over batch fill level and residence time.

Technical Parameters

ParameterSpecification
Heating Method Indirect — steam jacket (no direct product contact)
Jacket Design Pressure 1.0 MPa (steam)
Jacket Design Temperature 180°C (steam)
Vessel Design Pressure Atmospheric (normal pressure)
Vessel Design Temperature 180°C
Inner Vessel Material Duplex stainless steel
Jacket Material Carbon steel
End Plates / Flanges Carbon steel composite SUS316L
Agitator Material Duplex stainless steel, polished finish
Drive Motor 110 kW, explosion-proof variable frequency motor, 380V, 3-phase, 50Hz
Gearbox Hardened-face gear reducer, China origin
Spindle Speed 100 rpm
Vacuum System Water ring vacuum pump, explosion-proof motor
Total Volume 6.0 m³
Material Level Control Manual regulating valve
HS Code 8419.40.1000

Specifications above reflect a completed reference project (6.0 m³ / 110 kW configuration). Vessel volume, motor power, and jacket area are engineered to your target production capacity.

Scope of Supply

✓ Included as Standard
Vessel with steam jacket, drive motor, speed reducer, agitator, manual level control valve
Not Included — Customer Scope
Electrical control cabinet, frequency converter, installation labor, feeding & discharging valves

Standard delivery time is approximately 120 days from down payment. ZHAOYUAN can also arrange these excluded items and full installation as part of an EPC project scope — contact us to discuss.

Applications

CMC Production Lines Solvent stripping and drying of crude CMC after etherification. Suitable for all CMC grades including food grade, industrial grade, and oilfield grade.
PAC Production Lines Stripping and drying of polyanionic cellulose after reaction. Compatible with both PAC-HV and PAC-LV production processes.
HPMC Production Lines Applicable in hydroxypropyl methylcellulose production where solvent stripping is required after the etherification stage.
Plant Revamping Replacement of existing dryers in capacity expansion or energy efficiency improvement projects for existing cellulose derivative plants.

Frequently Asked Questions

What does a steam stripping dryer do in CMC/PAC production?

After etherification and washing, the crude CMC or PAC still contains residual solvent (typically ethanol or isopropanol) and moisture. The steam stripping dryer performs both functions in a single vessel: indirect steam heating drives off residual solvent under vacuum, while continuous agitation and heat reduce moisture content to the target specification — all without direct steam contact with the product.

Why is the vessel rated for atmospheric pressure while the jacket is rated to 1.0 MPa?

The product side of the vessel operates at or below atmospheric pressure — in fact under vacuum during stripping — since no pressurized reaction takes place inside the vessel itself. The jacket, however, carries saturated steam used purely for indirect heating and is rated to 1.0 MPa / 180°C to safely contain the steam supply pressure. This is a standard design split for indirectly-heated stripping/drying vessels.

Why is duplex stainless steel used for the inner vessel instead of standard 304 or 316?

Duplex stainless steel combines the corrosion resistance of austenitic stainless steels with significantly higher strength, making it well suited to a vessel that must withstand both the chemical environment of residual reaction by-products and the mechanical stresses of continuous agitation at elevated temperature. It offers a durability advantage over standard 304/316 in this demanding, cyclic-duty application.

What is included in the standard equipment package, and what isn't?

The standard package includes the vessel with steam jacket, drive motor, speed reducer, and agitator. It does not include the electrical control cabinet, frequency converter, installation labor, or feeding/discharging valves — these are typically sourced locally or supplied by the customer to match site electrical standards and layout. ZHAOYUAN can also supply these items and full installation as part of a complete EPC project.

What is the typical delivery time for this equipment?

Standard delivery time is approximately 120 days from down payment for a single unit built to reference specifications. Lead time may vary depending on vessel size, material availability, and current production schedule — contact ZHAOYUAN for a confirmed delivery date against your specific requirements.

Can ZHAOYUAN size this dryer for a different production capacity?

Yes. The 6.0 m³ / 110 kW specification on this page reflects a completed reference project. Vessel volume, motor power, agitator speed, and jacket heating area are engineered to match your target production capacity and product characteristics. Contact ZHAOYUAN with your requirements for a tailored equipment specification.