Reducing Seal Water Consumption in Pulp & Paper Processes

Water conservation is crucial in the pulp and paper industry, with reducing seal water consumption being a key focus. Pumping systems, whether equipped with packing or mechanical seals, rely on seal water flush for optimal functioning. Seal water flush cools the seal and shaft, provides lubrication, and purges impurities. Factors such as product temperature, seal water temperature and pressure, rotation speed, and ambient system temperature influence the volume of water used. Without proper controls, systems often consume excessive seal water.

Different sealing solutions have specific flow and pressure requirements, and exceeding these offers no benefits. Purging impurities and lubricating seals typically require minimal water. Cooling may necessitate more, but often the quantity used far exceeds the requirement. Seals lacking flow controls can consume 20 to 30 gallons of water per minute, a figure that can be reduced through conservation practices.

Advantages of Reducing Seal Water Usage

Reducing seal water usage offers cost savings on water and wastewater treatment, enhanced seal reliability, improved equipment uptime, and compliance with environmental regulations. Implementing the following strategies can help:

Control Valves

Control valves, like household faucets, allow operators to flush the system with seal water when cooling is needed. However, keeping these valves wide open increases water consumption and wastewater production. Monitoring and opening valves only when necessary can save water.

Flow Meters

Flow meters reduce seal water consumption while enhancing seal reliability. These devices use two valves to regulate seal water flow and pressure through a metering tube, ensuring flush water meets sealing requirements. Flow meters provide pressure and flow readings, allowing adjustments for proper seal water pressure and flow. They can reduce water consumption by up to 90% compared to unmetered flow-controlled seals.

Smart Water Control Systems

Smart water control systems are the most advanced solution for seal water conservation, reducing water consumption by up to 97% beyond flow meter savings. These systems regulate water based on seal temperature, allowing water to flow as necessary for cooling. Unlike flow meters, smart systems can recycle seal water multiple times, replacing it with fresh water when necessary. High temperatures reduce water savings, as these systems frequently top off with cold water. Look for systems that operate automatically, do not require power, easily integrate with existing equipment, and have minimal maintenance.

Seal Water Pots

Closed-loop seal water systems, common in pulp and paper plants, employ a pressurized seal water pot connected to the seal via hoses. These systems continually circulate the same water, reducing usage and eliminating wastewater discharge. However, they can be expensive to install and require regular maintenance. If process fluids mix with seal water due to seal damage, cleaning the pots can be challenging.

Water Filtration

Filtration ensures efficient water use. Impurities in water can clog pumps, increase wear on seals, and lead to higher water consumption. Ensuring seal water meets industry standards for impurity size, silicate content, organic impurities, iron content, and water hardness is essential. Filtration options include inline filters for individual applications or multilayer filters for plant-wide systems.

Benefits of Water Conservation

Reducing seal water consumption lowers water and wastewater treatment costs while enhancing system reliability and reducing maintenance expenses. Seal water-related issues cause 59% of seal failures, primarily due to impurities accumulating and causing blockages. Without controls, seals typically last six to 18 months. With proper flush control technology, seals can last several years, improving equipment uptime, system performance, and lowering maintenance costs.

Minimizing seal water consumption helps meet environmental standards, as regulations on water pollution and usage tighten. Efficient seal water usage is achievable with current conservation technology. Investing in system controls and adhering to best practices offers significant financial, operational, and environmental benefits.

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