6 Challenges in the Dewatering Process of Molded Pulp

Table of Contents

Reducing energy usage by 30% with high-efficiency pumps, optimizing vacuum pressure for consistent water removal, and implementing advanced wastewater treatments to decrease environmental impact by 95%.

Efficiency of Water Removal

In the process of molded pulp dewatering, the most significant challenge is to take out enough water to ensure maximum efficiency without affecting the structure of the product. Generally, the industries want to maximize the water removal at initial stages of production to diminish the costs associated with the energy demand for the drying stages that usually come next. According to an analysis from a pulp molding operation that produces egg trays, the total removal of about 75% of the water is feasible with the vacuum dewatering system. The prolonged drying time as the result of wasted moisture might increase the overall operational costs by up to 40%, making this aspect of the production an issue that requires attention.

Pressure and Duration Optimization

The optimization of both the vacuum pressure focusing on the volume of water extracted and the duration duet of its application is the vital factor that determines the financed tied to the operation. Measurements indicate that an increase in pressure from 0.3 to 0.5 bar can improve the process of the water removal by up to 15% . While leaving more moisture in the pulp form might not affect the structural integrity of the products at surface, it also makes it less energy-intensive to bring the mold to the drier temperature. In this way, the total energy consumption is cut by up to 20%, which directly correlates with the electricity bills.

Implications of Inefficiency

If the water removal process is inefficient, the energy use needed for the drying ramps up while the production slows due to longer conveyor time. In a poorly optimized process, the increased drying time has added 30 more minutes per batch, which makes for fewer batches produced in a day with increase unit costs.

Materials and Techniques

Water release can also be maximized with the use of modern materials . The hydrophobic mold surfaces property also improves the ability of the pulp to get the water off of it when it is released and transported to the conveyer belt at the end of the system. In this way, the removal of moisture before going to the drying oven can be increased by an additional 5%.

Quality and Speed Adjustments

Quality control is essential in dewatering as the speed of the conveyor belts that transport the pulp to the ovens has to be efficiently balanced. Even though a 10% increase in productivity can be seemingly achieved by increasing the conveyer speed, it also means that some parts of the mold will have water left in it due to the shorter exposure to vacuums. Precisely controlled operation ensures that the dewatering time is optimized to the maximum without a crooked distribution of drier and wetter products inside a batch.


Consistency and Quality Control

Achieving consistency in the dewatering process of molded pulp is a critical aspect of product quality. Egg cartons, fruit trays, and industrial packaging may all show poor product quality and structural weakness as a result of inconsistent dewatering. Uniform dewatering may be achieved through the implementation of mold design changes, advanced monitoring systems using sensors and the same moisture target to ensure uniformity, and standardized pulp mixtures and slurry preparation.

For instance, uniform airflow in the mold allows for a uniform drying temperature across the product. Typically, older or poorly designed molded pulp facilities will report a 10% increase in the rate of product rejection as a result of drying inconsistency and weakened areas in the product. Advanced systems, on the other hand, use sensors that monitor the moisture content of different areas of the pulp and an accepted 55% moisture reduction before the drying phase . If these sensors monitor the pulp moisture in real-time and make consistent process adjustments based on their measurements, the facility could expect a variability reduction of as much as 25%. However, sample stagnation due to rare measurements may result in lower quality.

In addition, the uniformity of both the pulp mixture and the prepared slurry should also be accomplished. For instance, pulp and the slurry must have uniform densities in order to prevent a concentration of weak spots. Typically, molded pulp facilities that measure and make necessary adjustments have a constant 1.03 specific gravity, thus, experience a product quality increase of about 20% . Finally, properly trained operators may also be a factor. Most molded pulp facilities that experience a drop in production efficiency and quality fail to provide operators with necessary training and equipment with the timely care it takes. Overall, the output quality of such companies is approximately 15% lower.

Energy Consumption

One of the major problems for manufacturers in the dewatering process of molded pulp is energy consumption. Both heating and vacuum systems require considerable power capacity; therefore, reducing energy consumption can decrease costs while also aligning with sustainable goals. There is a number of ways to reduce energy consumption, including implementing energy-efficient technologies, combining the process with heat recovery programs, incorporating automated control systems and scheduled maintenance.

Energy-Efficient Technologies

One way to reduce energy consumption is to employ energy-efficient technologies. Transitioning to a high-efficiency vacuum pump can decrease energy consumption by up to 30 percent . If a regular vacuum pump requires a certain amount of energy, let’s say, 50 kilowatts per hour, an energy-efficient model will only require 35 kilowatts per hour . Therefore, a target facility would save 15 kilowatts of energy, which could be used for other tasks while also generating cost savings. In addition, the implementation of energy-efficient drying systems can significantly decrease energy consumption levels.

Optimal Process Integration

The dewatering process could also be combined with heat recovery systems, which would enhance its efficiency. If the waste heat from the evaporative cooling system is utilized to heat incoming air, the energy consumption for drying decreases by 50 percent. This duplicitous use of the energy produced in the first step leads to cost savings as well as decreased environmental impact.

Automated Control Systems

Implementing automated control systems that determine the optimal times and power to engage in activities can result in significant energy savings. As noted by experts, employing a cost-effective smart control system that manages drying heat and vacuum pressure leads to 20 percent cost savings annually.

Scheduled Maintenance

One of the reasons for excess energy consumption in unwanted spikes is the inefficiency of equipment. Facilities, who engage with a maintenance service and replace their dewatering equipment on time, witness a 15 percent drop in unexpected spikes in energy across the year.


Equipment Maintenance

One of the most effective ways is to maintain the equipment used in the dewatering process of molded pulp to prevent breakdowns and ensure consistent production quality. Maintenance affects both the equipment’s lifetime and the overall efficiency of operation. A couple of the most common ways include regular inspection and servicing, the use of high-quality replacement parts, training for the maintenance team, and advanced monitoring systems.

  • Regular inspection and servicing. For instance, it is essential to keep regular checks of the vacuum pumps and dewatering screens. The surface of the later and the performance of both may be worn as they work consistently with wet pulp. Research shows that facilities that operate bi-weekly inspections and replace worn parts have downtime that is 25 percent lower than those practicing reactive maintenance.

  • Use of high-quality replacement parts. It has been observed that good replacement parts reduce the frequency of equipment maintenance and improve their efficiency. A good instance is a pump for dewatering that had low-quality seals and bearings that varied every 6 months. A replacement was sourced that cost slightly higher but lasted for a lifespan of one year, and thus the cost with the improved equipment was lower. Facilities that practice such proactive maintenance save a significant amount, 20 percent, in maintenance at the end of the machine’s lifespan.

  • Training for the maintenance team . The other most common way includes training the members of a maintenance team on how to flag and fix common issues without using specialist help. Research shows that facilities that implement regular training programs for their maintenance team reported a 30% reduction in the frequency of equipment failure . Skilled machine operators can be useful in preventing small problems that might initially seem insignificant from escalating into significant machine failures.

  • Advanced monitoring systems. Finally, sensors can be used in machines such as the dewatering screen to identify the imbalances in speed and motion that could lead to their mechanical failure . Facilities that implement such predictive maintenance technologies report a 40% reduction in unplanned downtime.

Environmental Impact

dewatering in molded pulp manufacturing has a substantial environmental impact. In particular, the pressure of the dewatering process and the flushing of the pulp cause water usage and waste management challenges, contributing directly to the environmental impact of the manufacturing process. Consequently, efficient dewatering minimizes the potential impacts not only in terms of environmental regulations but also sustainability.

Reducing Water Usage

Optimization of reuse in the cycle of pulp production is critical to the issue. A typical molded pulp plant can use up to 10,000 liters of water for producing one ton of product. A closed-loop water system can reduce this usage by up to 50% . Such systems can capture, treat, and reuse the water inside the plant, thus reducing the necessity of fresh water use and reducing the volume of wastewater. Thus, reusing water is beneficial for effective dewatering.

Wastewater Treatment

Improved wastewater treatment is impassable in the context of the reduction of environmental impacts. Advanced water treatment systems enable removing over 95% of contaminants from the wastewater before the discharge . Meanwhile, traditional ones can remove only around 80% of contaminants. The higher level of purification can help to meet stricter environmental standards and reduce pollution.

Use of Eco-Friendly Chemicals

Switching to chemicals, which are environmentally friendly and biodegradable, can assist with the reduction of the toxic load of wastewater. For example, some plants that have replaced traditional flocculants with organic ones succeeded in reducing the toxicity of their discharged water by 30% , thus fostering a healthier ecosystem around the plant.

Energy-Efficient Equipment

Adopting energy-efficient equipment can reduce the carbon impact stemming from dewatering. Thus, older style drying systems, which are less efficient, can be replaced by newer systems, which can slash the energy consumption by 40%. The greenhouse gas emissions from energy usage are also reduced as a result.

Scale-Up Issues

Scaling up the dewatering process in molded pulp production brings several challenges. Manufacturers hoping to increase capacity must consider several issues to ensure product quality and operational efficiency.

Ensuring Consistency

One of the most significant concerns in scaling up is the need to ensure the consistency of the dewatering results for batches of different sizes. For example, material with acceptable moisture content used by a facility producing 1,000 units per day may have substantially fluctuating water content if the plant scales up to 10,000 units. The higher moisture levels on such equipment results from the inherently imprecise distribution of pressure in larger equipment, necessitating more precise calibration. Automated process control eliminates this problem as it continuously adjusts to the current results, maintaining unparalleled consistency and reducing waste by up to 15%.

Optimizing Equipment and Layout

Another problem in the transition to larger facilities is the necessity to build the layout in a way that ensures a continuously high flow of materials through the plant. Inefficient dewatering layouts require high transportation and handling distances spent by units between the two subsequent stages, and such time expenditures may double if output is multiplied by 10. Because changing the output per unit of equipment to reduce route length is highly expensive and sometimes impossible, layout optimization frequently includes combining units. This approach can potentially increase the facility’s throughput by up to 10%. Furthermore, higher-volume machines are more efficient, reducing cycle time by up to 20%. Large, industrial-scale vacuum dewaterers keep the machine running for the shortest possible time, speeding the removal of water.

Training and Management

Larger production volumes demand more trained personnel. The dewatering process, in particular, requires multiple specialized operators for new equipment. Training new employees or transferring the required mechanical knowledge represents a significant challenge. Companies that provide comprehensive operator training report as much as 25% faster equipment operation by dewatering plant operators. It has also allowed running the facility with fewer, more qualified professionals and ensured continuous manufacturing.

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