Product Overview
Rajshree Group is one of India's leading turnkey suppliers of Pulp Washing Systems for kraft and chemical pulp mills. The washing stage — also known as Brown Stock Washing — is one of the most critical steps in the pulp manufacturing process. It separates the spent cooking liquor (black liquor) from the cellulose fibres after the digester, recovering valuable chemicals for reuse and preparing clean pulp for the bleaching stage.
Efficient washing directly impacts chemical recovery efficiency, bleaching chemical consumption, and overall mill profitability. Rajshree's washing systems are engineered for maximum black liquor extraction, minimum dilution factor, and consistent pulp quality — using proven drum washer, diffusion washer, and press washer technologies suited to every mill size and pulp grade.
Key Features
- ✓Multi-stage drum washer configuration for maximum black liquor extraction
- ✓Diffusion washer option for energy-efficient continuous washing
- ✓Twin-roll press washers for high-consistency outlet (30–35% DS)
- ✓Counter-current washing for minimum fresh water consumption
- ✓Sealed hood design to capture non-condensable gases (NCG)
- ✓Stainless steel 316L construction for high corrosion resistance
- ✓Automatic shower system with controlled water distribution
- ✓DCS/PLC-based automated consistency and flow control
- ✓Integrated black liquor storage tank and transfer pump system
- ✓Low soda loss — less than 8 kg Na₂SO₄ equivalent per tonne of pulp
Types of Washing Systems We Supply
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Drum Washer
Rotary vacuum drum washer with multi-stage counter-current configuration. Ideal for medium to large capacity mills. Proven technology with consistent performance.
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Diffusion Washer
Atmospheric or pressurized diffusion washer for continuous, energy-efficient washing. Suitable for all pulp types with minimum fibre damage and low energy consumption.
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Press Washer (Twin Roll)
High-pressure twin-roll press washers delivering 30–35% outlet consistency. Excellent black liquor extraction with compact footprint. Ideal for retrofit and space-constrained mills.
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Belt Washer
Horizontal belt washers for agro-based pulps (bagasse, straw). Gentle handling of short fibres with excellent washing efficiency and low maintenance requirements.
How the Washing Process Works
1
Blow Tank Feed
Hot pulp slurry from the digester blow tank enters the first washing stage at 10–15% consistency, carrying black liquor with dissolved lignin and spent chemicals.
2
Counter-Current Washing
Clean wash water enters at the last stage and flows counter to the pulp direction through 3–4 stages. Each stage displaces progressively more black liquor from the fibre mat.
3
Black Liquor Extraction
Strong black liquor (15–18% dry solids) is extracted from the first stage and sent to the evaporation plant for concentration before being fired in the recovery boiler.
4
Clean Pulp Output
Washed pulp exits the final stage at 10–35% consistency (depending on washer type) with soda loss below 8 kg/tonne — ready for oxygen delignification or bleaching.
Applications
- Kraft pulp mills — softwood and hardwood
- Agro-based pulp mills — bagasse, rice straw, wheat straw
- Bleached and unbleached kraft pulp production
- Dissolving pulp and specialty pulp mills
- Waste paper recycled fibre washing and cleaning
- Upgrade and retrofit of existing washing lines
Our Turnkey Project Process
1
Consultation & Feasibility
We evaluate your pulp grade, capacity, and existing layout to recommend the best washing technology for your mill.
2
Engineering & Design
Complete process design, P&IDs, civil foundation drawings, electrical layouts and equipment datasheets prepared by our experienced team.
3
Manufacturing & Supply
Equipment manufactured in our shop or sourced from trusted vendors, quality-inspected, and dispatched with installation drawings.
4
Installation & Commissioning
Our field engineers supervise erection, pipework, instrumentation, and commission the washing system to guaranteed performance parameters.
5
Training & After-Sales Support
Full operator and maintenance training, performance guarantee trial run, and ongoing technical support and spare parts supply.