MCA preparation runs in parallel with cellulose preparation (cotton opening / pulp board crushing / pulverizing). Both streams feed into the etherification kneader.
The MCA Dissolving Vessel is a raw material preparation unit used to melt solid monochloroacetic acid (MCA) and convert it into a homogeneous liquid at controlled temperature, ready for metered dosing into the etherification kneader. MCA is the etherifying agent in CMC and PAC production — its precise preparation and dosing directly determines the degree of substitution (DS) and consistency of the final product.
The inner vessel is glass-lined (enamel-coated), providing full corrosion resistance against molten MCA and its vapours at elevated temperatures. The outer jacket uses carbon steel construction and accommodates steam or thermal fluid heating to melt and maintain the MCA at the required process temperature. This two-layer construction is the industry standard for MCA handling vessels in cellulose ether plants.
Monochloroacetic acid (MCA) is highly corrosive to carbon steel, stainless steel, and most common metals in its molten and aqueous states. Glass-lined (enamel) construction is mandatory for the inner vessel wetted surface. Any damage to the glass lining must be repaired before returning the vessel to service. Full personal protective equipment (PPE) is required when handling MCA. Refer to the MCA Safety Data Sheet (SDS) for storage, handling, and emergency response procedures.
- Glass-lined inner vessel for full MCA corrosion resistance: Molten MCA and its vapours are highly corrosive to metallic surfaces. The glass-lined (enamel) inner vessel provides a chemically inert barrier that withstands MCA across the full operating temperature range, extending vessel service life and preventing contamination of the MCA charge with corrosion products that would affect product purity and DS consistency.
- Jacketed heating for controlled MCA melting: Solid MCA (melting point ~63°C) must be uniformly melted and maintained at a controlled temperature before dosing. The carbon steel jacket circulates steam or thermal fluid around the inner vessel, providing even, controllable heating that prevents localised overheating and MCA decomposition.
- High design rating for process safety: With inner vessel design pressure of 0.4 MPa(G) and jacket design pressure of 0.6 MPa(G), both at 200°C design temperature, the vessel is rated well above normal MCA process conditions, providing a substantial safety margin for industrial continuous production.
- Integrated into EPC CMC/PAC production lines: ZHAOYUAN supplies the MCA dissolving vessel as a standalone unit or as part of a complete EPC CMC or PAC production line package, where it is integrated with the MCA dosing system, etherification kneader, and process control instrumentation.
| Parameter | Inner Vessel | Heating Jacket |
|---|---|---|
| Material / Construction | Glass-lined (enamel-coated) | Carbon steel |
| Design Temperature | 200°C | 200°C |
| Design Pressure | 0.4 MPa (G) | 0.6 MPa (G) |
| Process Medium | Molten monochloroacetic acid (MCA) | Steam or thermal heating fluid |
| Function | Melt, homogenise, and hold MCA at process temperature | Provide controlled indirect heating |
Vessel volume, nozzle configuration, agitator specification, and insulation details available on request. Custom sizing for different MCA batch volumes or continuous dosing requirements can be engineered as part of an EPC project.
In CMC and PAC production, the etherification reaction between alkalized cellulose and monochloroacetic acid (MCA) determines the degree of substitution (DS) of the final product — the most important parameter governing product viscosity, solubility, and application performance.
Uniform DS across a batch requires that MCA be dosed into the kneader as a homogeneous liquid at a controlled temperature and at a precise, metered rate. Solid MCA fed directly into the kneader causes uneven distribution, localised hot-spots, and DS variation — resulting in off-spec product and reduced yield. The MCA dissolving vessel eliminates this variability by ensuring a consistent, liquid-phase MCA feed to the etherification stage.
The vessel also serves as a buffer between MCA receipt (typically in solid bagged or bulk form) and the continuous or semi-continuous etherification process, allowing independent scheduling of MCA charging and kneader operation.