The modern papermaking process primarily consists of pulping and papermaking. Pulping involves the separation of plant fiber raw materials through chemical and mechanical methods to produce unbleached pulp or bleached pulp. Papermaking, on the other hand, involves combining pulp fibers suspended in water through various processing techniques to form paper that meets diverse requirements.
Modern papermaking is highly automated, featuring extensive control systems that include alkali recovery, slurry flow box, slurry storage tower, pulping vessels, bleaching towers, additive tanks, drying drums, steam pipelines, vacuum pumps, and more. Each system demands high productivity and equipment reliability. LEEG Instruments thoroughly understands industry needs and provides suitable pressure, level, flow, and temperature measurement instruments. These devices are robust, long-lasting, stable, and easy to maintain, meeting the stringent requirements of the industry.
Industry Challenges
In the papermaking production process, the main measured media include pulp slurry, steam, water, wastewater, and black liquor. Throughout the process, the pressure of these media in pipelines and vessels can reach up to 1.6 MPa, with temperatures as high as 180°C. Whether it's coarse pulp slurry in the refining section, black liquor chemical pulp in the cooking section, high-concentration pulp in the deinking section, mixed pulp in the blending system, sludge in waste treatment, or bleached chemi-mechanical pulp in the bleaching section, these media are characterized by abrasiveness, corrosion, large particles, and high temperatures. Improper product selection can easily lead to measurement failure, affecting production.
Solution
Papermaking industry pressure transmitters use ceramic capacitive diaphragms, with additives such as talc, silicon carbide, and kaolin in the process. Papermaking industry pressure transmitters employ flush-mounted diaphragms for easy cleaning, reducing contamination from adhering impurities. The process connection adopts a papermaking-specific M44x1.25 interface. For special sections, electromagnetic flowmeters can use high-temperature-resistant, negative-pressure-resistant PFA (with steel wire mesh lining) and a pulp-optimized electromagnetic flow converter designed specifically for the papermaking industry.
Case Application
A domestic paper company uses corn starch as raw material to produce cultural paper. The process involves multiple stages, such as pulp preparation, mixing, forming, pressing, and drying. Each stage requires precise control of pressure and flow to ensure production stability and product quality. Pressure transmitters provide accurate and stable measurement of pressure changes during production, ensuring all process parameters remain within the desired range. Key applications include:
Pulp Preparation Stage: During pulp mixing, pressure transmitters monitor slurry pressure variations to ensure thorough mixing and stable pulp concentration. The pressure is maintained between 1-3 bar to achieve optimal pulp ratio.
Pressing Stage: In the paper forming and pressing process, pressure transmitters monitor the working pressure of the press, typically within 4-7 bar, preventing excessive or insufficient pressure that could lead to uneven paper thickness.
Drying Stage: During drying, pressure transmitters mainly monitor steam pressure, usually within 6-12 bar, ensuring uniform paper drying and avoiding localized over-drying or moisture retention.
LEEG SMP858-TST Pressure Transmitter (Papermaking Specialized) adopts advanced mono-silicon sensing technology, providing 0.5% F.S. full-scale accuracy. With a ceramic diaphragm, it operates reliably in high-temperature, high-humidity, and corrosive environments. It supports multiple output signals, such as 4-20mA, HART, RS485, and PA protocols, enabling seamless integration with industrial automation control systems. The SMP858-TST pressure transmitter drives high-quality, sustainable development in green papermaking.
