News. Pulp & Paper. Turbidity Measurement Improves Efficiency of Green Liquor Filtration. Perspectives in Liquid Process Analytics

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1 Pulp & Paper Perspectives in Liquid Process Analytics 9 News INGOLD Leading Process Analytics Turbidity Measurement Improves Efficiency of Green Liquor Filtration The turbidity sensor InPro 8400 provided a large Japanese paper manufacturer with a reliable means of controlling the return of high-turbidity permeate from the green liquor filtration process during backflushing of the filter. Paper market in Japan Japan is the second largest paper manufacturer and sixth largest pulp producer in the world. Our customer belongs to the largest single P&P producer in Japan, with approx. 4,800 employees and over 12 billion US dollars sales. Recently, Japanese pulp and paper companies have tended to shift to the production of highgrade paper. The reason is that the high labor costs in Japan do not favor the production of high-volume (commodity) paper. Green liquor clarification During processes for recovery of chemicals from the pulping stage, so-called green liquor is produced, which has to be clarified/ filtered before further utilization/ treatment. The purpose of green liquor clarification is to remove solids from the green liquor. The solids are primarily unburned carbon particles from the recovery furnace. These solid particles are typically referred to as dregs. Along with carbon the dregs contain other impurities such as silica, iron, chromium, aluminum and magnesium. These impurities are not part of the causticizing process. If these particles are not removed from the system in the green liquor clarifier, they can cause many operational problems downstream. Therefore, the clarification step takes on a critical aspect. The filtration process To maintain filtration efficiency, the customer backflushes the filter at certain intervals. Immediately after backflushing, filter material often migrates/ breaks

2 through to the permeate side and therefore the turbidity in the permeate liquid immediately tends to rise. Process control with turbidity measuring system On the basis of the measurement provided by the turbidity sensor, it is possible to control the return of high turbidity permeate liquid to the filter inlet side. If the turbidity drops, then the permeate can be fed to the next step, causticization (see Fig. 1). With this measuring principle, it can be guaranteed that the degree of turbidity never exceeds a level which might negatively impact the causticizer. application. METTLER TOLEDO installed a measuring system consisting of the turbidity sensor InPro 8400 and the transmitter Trb 8300F/S. The sensor was directly mounted into the permeate pipe. Functionality of the system The decision to furnish the InPro 8400 with Kalretz seals was exactly the right choice for this application. Fig. 2 shows the turbidity values measured during the process. During the one-year test run, the sensor needed no maintenance whatsoever, and even afterwards during the real Fig. 1: Extract of schematic flow chart of the paper production. production run, the only work required was for replacement of the lamp. Customer satisfaction and benefits After the many problems experienced prior to installation of the InPro 8400 sensor, the customer was really satisfied with this solution. To run an application without maintenance problems and to consistently obtain reliable results has been met with great appreciation. METTLER TOLEDO solution As the green liquor is usually strongly alkaline (40%), and the process temperature also high (70 C/158 F), the turbidity measuring system should be able to tolerate these challenging conditions. Before METTLER TOLEDO offered its solution the customer had difficulties in finding the right turbidity sensor for this salt cake recovery furnace dissolving tank strong black liquor green liquor green liquor clarifier turbidity measurement causticizer white liquor and sludge Publisher / Production dregs washer dregs pebble lime Mettler-Toledo AG Process Analytics Im Hackacker 15 CH-8902 Urdorf Switzerland Illustrations turbidity control line Archive MarCom CH-8902 Urdorf Switzerland Archive Giesse Srl, Italy Archive Tappi association Subject to technical changes. Mettler-Toledo AG 06/07 Printed in Switzerland. Fig. 2: Turbidity measuring curve as obtained with the sensor InPro time 2 METTLER TOLEDO Pulp &Paper News

3 ph-measurements at Headbox The Design of InPro 4501 ph-sensors Increases Sensor Life and Operating Efficiency A leading US manufacturer of paper products switching to METTLER TOLDEDO s InPro 4501 ph-electrode at their headbox. Fouling, cleaning requirement and excessive calibration could be significantly reduced. Therefore, maintenance becomes optimized and the operation efficiency increased. The role of ph in the headbox Headbox ph measurement is critical to the consistency of strength and quality of paper products. Headboxes serve as the link between the approach flow system and the forming section of paper processing. Its main tasks are to distribute the stock uniformly in cross direction and to create a homogeneous jet for achieving an optimum sheet structure in terms of physical properties. 1 High levels of ph will degrade paper quality and significantly weaken its overall strength. Incoming stock or pulp typically has a higher than desired ph value. Injection of neutralization agent, such aluminum sulfate, is required in order to reduce the ph to acceptable levels. The ability to accurately monitor the ph level and control neutralization agent injection is critical to the overall efficiency and quality of the headbox processing. High process requirements The inherent difficulty of ph measurement of headbox processing relates to the composition of the feed (paper pulp) into the processor. Paper pulp is extremely fibrous and has a tendency to quickly coat surfaces. Standard ph probes require relatively significant tip exposure in order to complete the connection between the reference and measurement electrolyte. The extended sensor tip exposure provides a large surface for the fibrous media to quickly coat and clog. Accurate measurements quickly degrade and excessive cleaning and calibration is required in order to maintain acceptable performance. The secret of InPro 4501 The InPro 4501 Sensor is integrally housed in chemically resistant PVDF with a unique flat glass membrane and integral solution ground. The engineered, selfcleaning design of the flat glass membrane resists coating and limits clogging from fibrous media. The solid polymer reference electrolyte is in direct contact with the media and eliminates the potential of junction fouling. The integral solution ground is an added benefit preventing ground loop problems and allows for advanced signal diagnostics. The METTLER TOLEDO solution The paper product manufacturer decided to install eight InPro 4501 sensors with ph 2100e transmitters. The installation of the sensors was easily facilitated by the 1 MNPT process connections integral to the sensor bodies. The sensors simply threaded into existing access points without requiring extensive changes to the present piping system. The customer s benefit The final result for the customer has been a 2-fold increase in sensor life up to 8 months! The exceptional performance of the InPro 4501 sensors have led to an evaluation of other difficult points of measure. INGOLD ph sensors are now being considered for an additional eight loops with HotTap installations. METTLER TOLEDO Pulp &Paper News 3

4 Transmitter for Wastewater M300 the new Transmitter Series for Reliable Wastewater Measurements The M300 transmitter series for ph/ ORP, oxygen, and conductivity measurements combine robustness and ease of use. High versatility and reliable basic measurements make this instrument the ideal choice for wastewater applications. M300 a multiparameter transmitter The new M300 transmitter line has been designed to measure ph, conductivity and dissolved oxygen. Besides a single channel unit there is also a dual channel version available with multi-parameter capability. A large, 4 line backlit display with menus in 5 languages simplifies the installation and configuration of these instruments. The transmitters feature a USB port for ease of configuration, data logging and downloading software upgrades. M300 transmitter. M300 the right choice for wastewater The M300 transmitter represents a unique solution for wastewater applications where reliability and robustness are key. In the multi-parameter version, the user can set the two channels to any combination of the parameters ph, oxygen, and conductivity. This flexibility plus a universal power supply enable diverse installation requirements to be covered with the same physical transmitter. Ease-of-use and state-of-the-art measurement The hallmark of a modern measurement system should be the useability of its hardware combined with an intuitive, self-explanatory user interface, enabling the complete system to be set-up and operated without any prolonged study of operating manuals or costly personnel training. The information shown on the display should be well readable and easy to understand. In addition, permanent monitoring of ph electrodes via integrated diagnostic functions must provide a continuous flow of information on the actual operational status of the electrode, so that in the event of failure, the situation can be rectified within the shortest time possible. Likewise, the time needed for maintenance and calibration should be reduced to an absolute minimum through clear user prompting by the transmitter. These important points were all implemented in the development of the M300 Transmitter Line. Some highlights are described in more detail in the following. M300 Transmitter Line Hardware All transmitters 1 2or 1 4 DIN are equipped with a variable power adapter to allow operation at 20 to 30 VDC and at 100 to 240 VAC. Two different measurement values shown on the backlit display are well readable from a distance of 3-5 m. The attractively priced, multichannel version is freely configurable for parallel operation with ph and/or conductivity sensors. User-friendly operation A specially developed Quick Setup routine for startup guarantees error-free, ba- METTLER TOLEDO Pulp &Paper News 4

5 sic configuration. The software menu, both for ph and conductivity units, is selfexplanatory and available in five languages. The transmitter is fitted with a USB interface so that it can also be easily, safely and quickly configured via a PC or Notebook. Data Logger Via a USB connection the data logger is able to transfer data to the Notebook important for being necessarily to solve any problems that may arise. Data retrieval is straightforward and of help in achieving cost savings for maintenance work. Large backlit display (4 text lines) 5 languages Quick Setup Mode Password protection IP 65/NEMA 4X protection (1/4 DIN: front) PID controller 4-wire installation PID Controller The Transmitter M300 is equipped with a PID controller for rapid control of extreme values as well as for exact control of values near to the set points. In practice, this allows saving in dosing amounts, increase in yield, and a lowering of overall costs. Maintenance and calibration The continuously operating diagnostics function constantly provides information about the sensor status and, where necessary, displays which maintenance work is to be carried out. When calibrating the electrode, the automatic buffer recognition considerably shortens servicing time. What is important to know Outstanding features Technical advantages Your benefits of the M300 Dual-channel option, One transmitter for Saves costs user-configurable two measuring points High versatility Universal power supply Country-independent Ease of use voltages and frequencies Large backlit, Easily readable display under Excellent reading comfort high-contrast display unfavorable light conditions reduces handling errors Two-value display More information available Easy-to-understand plus two text lines at a glance instructions Quick setup menu Easy commissioning Saves time and installation Removable terminal plugs Easy component exchange Simplifies maintenance USB interface On-site firmware upgrade Asset protection and commissioning Basic diagnostics Enhanced sensor monitoring Optimizes sensor maintenance and reduces downtimes Two-level password Safety level adapted Protection against unauthorized protection to specific task handling enhances overall operational safety Five menu languages Easy operation Less handling errors result for wide user group in improved operational safety PID controller Accurate process control More efficient dosing of reagents improves yield Data logging USB port Allows on-site process Easy data access provides troubleshooting transparency Two or four current outputs For easy integration Higher yield into the process Cost savings Hold control input For master-slave operation Enhanced application with EC 100 /150 /200 coverage 5 METTLER TOLEDO Pulp &Paper News

6 Open Fieldbus Protocols support Asset Management and Plant Maintenance Open fieldbus technology like HART, FOUNDATION Fieldbus and PROFIBUS enables the full use of METTLER TOLEDO functional advantages on digital communication: improved resolution of measured values, intelligent sensor diagnostics and instrument parameter settings comfortable instrument configuration out of a central station, higher level of process data to improve the plant conditions, availability of additional process values to be easily integrated into the control system Our intelligent analytical instruments are equipped with electronic device descriptions (DD) for various process instrument configuration software tools. METTLER TOLEDO recommends Transmitters for ph / ORP, dissolved oxygen and conductivity Two transmitter lines for integration in HART, FOUNDATION Fieldbus and PROFIBUS PA networks. EasyClean 400 The cleaning and calibration system EC 400 for an easy integration in FOUNDATION Fieldbus and PROFIBUS PA networks. ISM technology Integration of sensor diagnostic information into the process control environment sensor wear monitor and adaptive calibration timer for optimal maintenance planning. Mettler-Toledo AG Process Analytics Im Hackacker 15 CH-8902 Urdorf, Switzerland Visit for more information Your METTLER TOLEDO contact: