3750 mm Drum Pulper Screening Zone Upgrade and Retrofit – Longyuan Paper Project

1. Project Background

Longyuan Paper's 3750 mm drum pulper was experiencing several operational issues, including insufficient open screening area, limited production capacity, frequent rope formation in the pulping zone, high energy consumption, and an unreasonable equipment load distribution.

To address these problems, our company carried out a targeted upgrade and retrofit of the screening zone by optimizing the screen perforation design. The improvements enhanced screening capacity and operational efficiency, optimized load distribution, and reduced energy consumption.

The retrofit successfully increased production capacity, reduced operating costs, improved efficiency, and significantly enhanced the overall operating performance of the equipment.

2. Operating Data Comparison Before and After the Retrofit

Operating Parameters	Before Retrofit	After Retrofit	Improvement
Daily Production Capacity	650 T/D	800 T/D	+150 T/D (+23.1%)
Water Addition in Pre-soaking Zone	70 m³/h	100 m³/h	+30 m³/h (+42.9%)
Water Addition in Screening Zone	550 m³/h	700 m³/h	+150 m³/h (+27.3%)
Drum Pulper Motor Current	36 A	40 A	+4 A
Electricity Consumption per Ton of Paper	Baseline	Reduced by ≥10 kWh/t	≥10 kWh/t saved

3. Economic Benefit Analysis

(1) Basic Calculation Parameters

1. Annual finished paper production: 200,000 tons
2. Electricity savings per ton of finished paper: ≥10 kWh
3. Industrial electricity price: RMB 0.6/kWh
4. Annual operating days: 330 days
5. Net profit per ton of paper: RMB 50 (reference value)

(2) Electricity Cost Savings

1. Annual electricity savings:200,000 tons/year × 10 kWh/ton = 2 million kWh/year
2. Annual electricity cost savings:2 million kWh × RMB 0.6/kWh = RMB 1.2 million/year
3. Payback period based on electricity savings alone: 9 months

(3) Additional Profit from Increased Production

1. Daily production increase:800 tons/day − 650 tons/day = 150 tons/day
2. Annual production increase:150 tons/day × 330 days = 49,500 tons/year
3. Annual additional profit:49,500 tons × RMB 50/ton = RMB 2.475 million/year

(4) Overall Investment Payback Period

2.6 months

(5) Additional Benefits from Reduced Operation and Maintenance Costs

The rope formation issue has been eliminated, reducing equipment downtime, maintenance requirements, and manual cleaning costs. Equipment-related losses caused by operational failures have also been reduced.

As a result, annual operation and maintenance costs have decreased significantly, further improving the overall economic benefits of the project.

4. Project Results

Following the retrofit, the daily production capacity increased to 800 T/D, representing a 23.1% increase compared with the original capacity.

The project is expected to generate RMB 2.475 million in additional annual profit, while saving at least RMB 1.2 million in annual electricity costs.

This upgrade demonstrates how targeted optimization of the drum pulper screening zone can improve production capacity, reduce energy consumption, lower maintenance costs, and deliver substantial economic benefits.