Paper industry

The paper industry places high demands on productivity and plant availability. IPTech knows these requirements and provides the right sensors for level, switching and pressure: robust, long-term stable and easy to maintain.

Wood chip silo

Wood chip silo level measurement

Application

The wood chips are transferred via conveyor belts to storage silos up to 25 m high and stored there temporarily for further processing. The silos are filled and emptied in batches. During the process, large amounts of dust are generated, material cones and bridges form, which collapse during emptying. Reliable level measurement is needed here to ensure supplies for downstream processes and facilitate logistics planning.
 

Your benefit

Reliable
Reliable continuous measurement, even during filling
Cost effective
Optimal container volume utilization
User friendly
Volume display and sensor adjustment in a convenient location

 

Process data

Measuring task:
Level measurement
Measuring point:
Silo
Measuring range up to:
25 m
Medium:
Wood chips
Process temperature:
+5 … +50 °C
Process pressure:
0 … 0 bar
Special challenges:
Material cones, huge amounts of dust and bridging in the silo

Digester

Level detection and pressure measurement in the digester

Application

In the digester, the action of chemical dissolution removes the lignin binder, thereby exposing and freeing the cellulose fibres. During the cooking process according to the alkaline sulphate method, the fibres are fed into the digester by means of steam pressure. To enable fully automatic operation of the digester, a point level detection of the filling is required. The vessel pressure also needs to be carefully monitored throughout this process.
 

Your benefit

Reliable
Reliable operation despite extreme process conditions
Cost effective
Measuring system can be installed without invasive work on the vessel wall and insulation
User friendly
Simple retro installation

 

Process data

Measuring task:
Point level detection and pressure measurement
Measuring point:
Digester
Measuring range up to:
8 m
Medium:
Wood chips in cooking liquor
Process temperature:
+160 … +170 °C
Process pressure:
+6 … +8 bar
Special challenges:
Insulated vessel

Pipeline in the liquor recovery process

Density measurement in liquor recovery

Application

The black liquor resulting from pulp cooking is regenerated and fed back into the digester. Liquor regeneration comprises several process steps. The processes take place at high temperatures and pressures; the media are aggressive and sometimes abrasive. Density measurement of the liquor in the pipelines is required for eco-friendly and energy-efficient process control.
 

Your benefit

Reliable
Reliable operation despite extreme process conditions
Cost effective
Density measurement from the outside, without invasive changes to the pipe
User friendly
Optimized for the application, long-term maintenance-free measurement

 

Process data

Measuring task:
Density measurement
Measuring point:
Pipeline
Measuring range up to:
Density
Medium:
Cooking liquor
Process temperature:
+120 … +130 °C
Process pressure:
+2 … +3 bar
Special challenges:
The liquor contains organic residual substances

Bleaching tower

Level measurement and point level detection in the bleaching tower

Application

In order to achieve the desired degree of whiteness, the pulp must be bleached. For this it is filled into the 25 meter high bleaching tower. The bleaching process runs continuously at temperatures up to 95 °C, with using chemicals such as oxygen, ozone or peroxide. The bleached pulp is discharged via screw conveyors. Due to its size, the bleaching tower is never emptied. Continuous level measurement enables a smooth process flow.
 

Your benefit

Reliable
High operational reliability by reliable measurement, even with high pulp densities
Cost effective
Maximum utilization of bleaching tower volume
User friendly
Minimal servicing thanks to non-contact, maintenance-free measurement

 

Process data

Measuring task:
Level measurement and point level detection
Measuring point:
Bleaching tower
Measuring range up to:
25 m
Medium:
Pulp
Process temperature:
+85 … +95 °C
Process pressure:
0 … 0 bar
Special challenges:
Different pulp densities

Pulper

Level measurement and blockage detection in the pulper and conveyor belt monitoring

Application

Waste paper or pulp bales are transported on a conveyor belt to the pulper, where they are broken down by adding process water. A stirrer speeds up to separate fibers. Difficult process conditions exist in the pulper: falling bales cause severe pressure shocks, the stirrer creates vortexes. Besides that, foreign substances like wire, glass or sand enter the process along with the waste paper and have an extremely abrasive effect on the interior of the vessel. To ensure an automatic process flow, the level measuring system must establish the ratio of waste paper/pulp to process water. In addition, a possible jamming of the bales on the conveyor belt must be detected.
 

Your benefit

Reliable
Prevents jamming, thus ensuring a smooth automated process
Cost effective
Enables optimal ratio of pulp/waste paper to process water
User friendly
Wear and maintenance-free thanks to non-contact measurement

 

Process data

Measuring task:
Level measurement and blockage detection
Measuring point:
Pulper, conveyor belt
Measuring range up to:
4 m
Medium:
Waste paper/pulp
Process temperature:
+20 … +40 °C
Process pressure:
0 … 0 bar
Special challenges:
Pressure surges, abrasion, vortex formation

Pressure screen

Pressure measurement in the pressure screen

Application

Pressure screens are used to filter out impurities and separate fibres in stock preparation. A rotating screen basket inside the filter does the actual filtering. Pressure screens have an inlet for the suspension, an outlet for accepted stock and a discharge for rejected stock and contaminants. The process conditions are characterized by pressure surges as well as abrasion and contaminants in the stock. Efficient screening requires a controlled pressure difference between inlet and outlet, which therefore requires continuous, reliable measurement.
 

Your benefit

Reliable
Reliable measurement despite strong vibration
Cost effective
High abrasion resistance guarantees long operation
User friendly
Self-cleaning and maintenance-free thanks to front-flush mounting

 

Process data

Measuring task:
Pressure measurement
Measuring point:
Pressure screen
Measuring range up to:
2 bar
Medium:
Paper suspension
Process temperature:
+20 … +50 °C
Process pressure:
+1.5 … +2 bar
Special challenges:
Pressure surges, abrasion, contaminants in the suspension

Storage towers

Level measurement in storage towers

Application

Large quantities of prepared stock are needed to keep a paper mill running continuously. This material is stored in high storage towers. They are characterised by their large material throughput and agitators that ensure the homogeneity of the stock. Inside, the warm stock generates lots of steam and the pumping and stirring processes make the surface very turbulent. Reliable level measurement ensures a continuous supply of stock and prevents the agitator from running dry.
 

Your benefit

Reliable
Reliable measurement despite steam and changing stock temperatures and densities
Cost effective
Optimal utilization of the container volume
User friendly
Simple installation and setup

 

Process data

Measuring task:
Level measurement
Measuring point:
Storage tower
Measuring range up to:
30 m
Medium:
Paper suspension
Process temperature:
+20 … +50 °C
Process pressure:
0 … 0 bar
Special challenges:
Steam generation, agitated surface due to pump operation

Headbox

Pressure measurement in the headbox

Application

The paper suspension is pumped into the headbox of the paper machine. Via the hydraulically pressurized headbox it passes through a tapered cross-flow distributor and manifold, through the rectangular discharge opening, or slice, onto the screen. The outflow speed of the suspension is adjusted to match the speed of the screen by adjusting the pressure of the headbox feed pump. This means an accurate pressure measurement, with minimal turbulence created in the headbox is vital at this part of the process.
 

Your benefit

Reliable
Highly accurate measured values, precise control input for the headbox pump
Cost effective
No flushing pipes needed
User friendly
High protection class IP 68 for easy cleaning

 

Process data

Measuring task:
Pressure measurement
Measuring point:
Pipe
Measuring range up to:
10 bar
Medium:
Paper suspension
Process temperature:
+20 … +50 °C
Process pressure:
0 … +10 bar
Special challenges:
High humidity and warm measuring environment

Deaerator

Level measurement in the deaerator

Application

The approach flow system connects the stock preparation facility with the paper machine. Here, the pulp for the paper machine is diluted to the required consistency. Additionally, the approach flow system ensures a smooth flow of stock. A particularly important element is the stock deaerator upstream of the headbox. It removes any entrained air under vacuum to ensure a constant, smoothly running process. For effective performance, the stock deaerator always has to be filled to a predefined, millimetre-exact level.
 

Your benefit

Reliable
Dry run protection for the headbox pump
Cost effective
Low-cost solution through use of electronic differential pressure
User friendly
Easy mounting without mounting brackets and capillary tubes

 

Process data

Measuring task:
Level measurement
Measuring point:
Tank
Measuring range up to:
1.2 m
Medium:
Paper suspension
Process temperature:
+20 … +50 °C
Process pressure:
-0.8 … 0 bar
Special challenges:
Foaming, turbulent surface due to gas emissions, low level with vacuum

Water separator

Level measurement in the water separator and pressure measurement upstream of the vacuum pump

Application

The paper web is dewatered in the press and wire section of the paper machine. As the resulting water is removed via vacuum pipelines which are monitored by pressure transmitters to control the vacuum pump. It is also very important to prevent water from getting into the vacuum pump. To achieve this, water separators are built into the feed lines and the separated water is drawn off by a water pump. A continuous level measurement is used to control the level and the pump.
 

Your benefit

Reliable
The high reliability of measurement protects the vacuum pumps from water intake
Cost effective
High availability of the vacuum system
User friendly
Easy to install, setup without calibration

 

Process data

Measuring task:
Level and pressure measurement
Measuring point:
Separator
Measuring range up to:
1 m
Medium:
White water from the paper machine
Process temperature:
+20 … +50 °C
Process pressure:
-0.7 … 0 bar
Special challenges:
Permanent vacuum-resistant measurement required

Drying-cylinder

Differential pressure measurement in the drying cylinder

Application

The residual moisture content of the paper web is removed by steam-heated cylinders in the drying section of the paper machine. The drying process removes heat from the steam, which then forms a thin layer of condensate on the inner walls of the cylinder. This layer influences the transfer of heat to the paper and has to be skimmed off continuously by siphoning. The correct level of heat transfer from the drying cylinder to the paper is monitored by pressure measurements both at the inlet and at the outlet.
 

Your benefit

Reliable
Reliable measurement ensures continuous, trouble-free operation of the facility
Cost effective
Low-cost measurement system via electronic differential pressure
User friendly
Simple installation, as capillaries and impulse lines are not necessary

 

Process data

Measuring task:
Differential pressure measurement
Measuring point:
Drying cylinder
Measuring range up to:
0.5 bar
Medium:
Steam/condensate
Process temperature:
+95 … +150 °C
Process pressure:
+2 … +3 bar
Special challenges:
High temperatures and high humidity

Storage tanks for chemicals and auxiliary substances

Level, switching and pressure measurement in storage tanks

Application

The targeted addition of chemicals and auxiliary substances influences the properties and quality of the paper. Common additives are hydrogen peroxide as well as alkalis, acids and fillers. These chemicals and additives are sometimes aggressive, produce vapours and are at temperatures of up to 95 °C. This means they are often stored in stainless steel or glass fibre reinforced plastic containers. Level and pressure measurements are essential for the safe filling and emptying of the storage tanks and for dry run protection of pumps.
 

Your benefit

Reliable
Reliable, product-independent measurement
Cost effective
Optimal utilization of the container volume
User friendly
Simple installation and setup

 

Process data

Measuring task:
Level and pressure measurement, point level detection
Measuring point:
Tank
Measuring range up to:
4 m
Medium:
Chemicals and auxiliaries
Process temperature:
+10 … +95 °C
Process pressure:
0 … 0 bar
Special challenges:
Aggressive, gas producing media

Starch silo

Level measurement in starch silos and dry run protection for starch liquefaction vessels

Application

Starch is an important additive to increase the strength of the paper. The raw starch is stored in tall, narrow silos. Filling is carried out pneumatically, generating large amounts of dust. They are discharged into the starch slurry production system beneath the silo and the resulting slurry is pumped into the starch cookers by eccentric pumps. For optimal control of the silo filling process, a reliable level measurement is required. To prevent the eccentric pump from running dry, an in-line switch is needed upstream of the pump.
 

Your benefit

Reliable
Reliable function even during filling
Cost effective
Dry run protection prevents failures or damage to the eccentric pumps
User friendly
Easy alignment via optional adjustable sealing gaskets

 

Process data

Measuring task:
Level measurement and point level detection
Measuring point:
Silo
Measuring range up to:
15 m
Medium:
Starch
Process temperature:
+10 … +50 °C
Process pressure:
0 … 0 bar
Special challenges:
Strong dust generation during the filling process

Vacuum system

Level and pressure measurement in the vacuum system

Application

A vacuum system is used to perform dewatering on the high-speed paper machines. The required high vacuum is generated by a single or multi-stage centrifugal blower. The strength of the vacuum is regulated by the rotational speed of the electric drives. For this purpose, the vacuum must be continuously measured. It is also necessary to monitor the bearing lubrication system to ensure reliable operation of the vacuum blower itself. To achieve this, the pressure in the lubricating lines and the level in the lube oil supply tank need to be measured.
 

Your benefit

Reliable
Reliable pressure measurement in the lubrication system, even with strong vibration
Cost effective
Long-term stable vacuum measurement with oil-free ceramic measuring cell
User friendly
Temperature information on air and lubricating oil also available for the control system

 

Process data

Measuring task:
Level and pressure measurement
Measuring point:
Vacuum system
Measuring range up to:
-0.75 … 0 bar
Medium:
Lubricating oil, air
Process temperature:
+30 … +90 °C
Process pressure:
-0.75 … 0 bar
Special challenges:
Permanent high vacuum, vibrations

Hydraulic oil station

Level and flow measurement in the hydraulic oil station

Application

In the press section of a paper machine, very high pressures are needed for dewatering the stock. Hydraulic oil stations provide the supply to the various parts of the machine as well as filtering and cooling the recirculating lubrication system. Integrated pumps provide oil to the required locations and to enable fully automatic operation of the station, the flow rate and the level in the supply tanks must be measured.
 

Your benefit

Reliable
Reliable measurements ensure consistent operation of the paper machine
Cost effective
Differential pressure transmitters with pitot tube for low-cost oil flow measurement
User friendly
Convenient reading of the level directly at the measuring point

 

Process data

Measuring task:
Level and flow measurement
Measuring point:
Tank
Measuring range up to:
2 m
Medium:
Machine oil
Process temperature:
+20 … +80 °C
Process pressure:
+5 … +6 bar
Special challenges:
High pressures

Batching tank for coatings

Level measurement in the coating batching tank

Application

The press rolls are cleaned during product changes or shutdowns of the paper machine and then treated with a special coating agent. This protects them from adhesions and deposits that could cause the paper web to tear or split in the machine. The coating agent is mixed with hot water in a batching tank at a temperature of 50 °C, and pumped to various points in the machine. To maintain automatic operation, the level in the batching tank must be measured and the filter status monitored continuously.
 

Your benefit

Reliable
Reliable level measurement despite extreme temperature changes
Cost effective
Accurate measurement even in small tanks
User friendly
Sensor removal during tank cleaning not necessary

 

Process data

Measuring task:
Level measurement
Measuring point:
Batching tank
Measuring range up to:
0.5 m
Medium:
Hot water with coating agent
Process temperature:
+20 … +50 °C
Process pressure:
0 … 0 bar
Special challenges:
Temperature change from cold to hot, low liquid levels, rapid filling

Ash silo

Level measurement and point level detection in the ash silo

Application

Large quantities of fibre waste are produced during paper production. These are dried and burned and the energy released during combustion is used as process heat or to generate electricity. The ash is stored in high silos to be later used as an additive in the building materials industry. When the ash silo is filled, a great amount of noise and dust is generated and the material forms large angles of repose and overhangs. Filling, emptying and transportation logistics are controlled through the level measurement system.
 

Your benefit

Reliable
Reliable readings in spite of difficult measuring conditions
Cost effective
Maintenance costs removed by air cleaning of antenna
User friendly
One radar sensor for all silo sizes, simple to install

 

Process data

Measuring task:
Level measurement and point level detection
Measuring point:
Silo
Measuring range up to:
25 m
Medium:
Ash
Process temperature:
+80 … +120 °C
Process pressure:
0 … +1 bar
Special challenges:
Dust and noise, material cones and angles, poor reflective properties

Storage tank for wet strength agent

Level measurement and point level detection in the storage tank for wet strength agent

Application

Wet strength agents are polymeric additives that increase the water resistance particularly of hygienic and specialty papers. These are applied in the paper machine via a size press or spraying device. Because of their high pH value, these substances are stored in double-walled GRP (glass reinforced plastic) tanks. For safety and operational reasons, multiple level measurements are needed in these tanks.
 

Your benefit

Reliable
Reliable filling with overfill protection and leak sensors
Cost effective
Maximum utilization of the container volume thanks to continuous level measurement
User friendly
Direct reading of the measured value at the additive station

 

Process data

Measuring task:
Level measurement and point level detection
Measuring point:
Tank
Measuring range up to:
5 m
Medium:
Wet strength agent
Process temperature:
+20 … +40 °C
Process pressure:
0 … 0 bar
Special challenges:
Aggressive, water contaminating medium, high importance on the availability of the measurements

Pumps for wet strength agent

Pressure measurement and point level detection for eccentric pumps

Application

Wet strength agents are polymeric additives that enhance water resistance properties, especially in sanitary and specialty papers. They are applied in the paper machine via a size press or spraying device. Because of their high pH value, these substances are stored in double-walled GRP (glass reinforced plastic) tanks. The high viscosity of the medium requires the use of a pneumatic conveyor system and special eccentric pumps for filling and emptying. With these pump types, dry run protection and pressure monitoring is a necessity.
 

Your benefit

Reliable
Reliable dry run protection of these expensive, easily damaged pumps
Cost effective
High availability of the pumps 
User friendly
Product independent function, thus simple setup and commissioning

 

Process data

Measuring task:
Pressure measurement and point level detection
Measuring point:
Pump station
Measuring range up to:
3 bar
Medium:
Wet strength agent
Process temperature:
+20 … +40 °C
Process pressure:
0 … +3 bar
Special challenges:
Viscous medium, fast reaction required, small pipe diameters

Refiner

Pressure measurement on the refiner

Application

Refiners are used in paper production to grind up pulp. The main objective of the process is to impart certain properties to the pulp. Every refiner has a grinding set consisting of both fixed and rotating parts. The pressures at the input and output have to be measured for monitoring the loading and release of the grinding set as well as for display of performance.
 

Your benefit

Reliable
Reliable measured values for the load release
Cost effective
Reliable measurement protects against damage to the grinding set and avoids downtime
User friendly
Flush mounting transmitter for maintenance-free measurement

 

Process data

Measuring task:
Pressure measurement
Measuring point:
Pipeline
Measuring range up to:
5 bar
Medium:
Fibre suspension
Process temperature:
+20 … +90 °C
Process pressure:
+0.5 … +4 bar
Special challenges:
Pressure shocks when drive starts, vibrations

Dump chest

Level measurement in the dump chest

Application

The fibre suspension created in the pulper is first drawn off into a dump chest. There it is temporarily stored for the further stages of the stock preparation process. Typical process challenges in the dump chest are fast filling from above and high stock densities. A slow-running lateral agitator ensures a homogeneous, pumpable consistency of the fibres in suspension. Level measurement in the dump chest determines when it is filled to capacity and ready for emptying and the next process step. The measurement is carried out hydrostatically via a side-mounted pressure transmitter with a ball valve fitting. This allows removal for maintenance or cleaning purposes, even when the dump chest is full.
 

Your benefit

Reliable
High operational availability through reliable measurement, even with high pulp densities
Cost effective
Maximum utilization of the vat volume
User friendly
Service-friendly thanks to easy access to the measuring system

 

Process data

Measuring task:
Level measurement
Measuring point:
Vat
Measuring range up to:
10 m
Medium:
Pulp or waste paper suspension
Process temperature:
+20 … +40 °C
Process pressure:
0 … 0 bar
Special challenges:
Different stock consistencies, fast filling

Cleaner

Pressure measurement in the cleaner

Application

Cleaners remove contaminating materials that are specifically heavier than fibres. In waste paper processing, these contaminants are, for example, sand, glass, stones or staples. The feed through the inlet is tangential in order to set the flow of material in rotation. The heavier particles migrate outwards due to the centrifugal forces and are precipitated downwards, while the lighter fibres in the middle of the vortex rise upwards and are passed on as accepted material. Pressure measurements in the inlet, outlet and overflow are required to regulate the process and ensure that it stays at the optimal operating point.
 

Your benefit

Reliable
High operational reliability, even with abrasive contaminants in the process medium, due to ceramic measuring cell
Cost effective
Operating the cleaner at the optimal operating point
User friendly
Minimal servicing thanks to maintenance-free measurement

 

Process data

Measuring task:
Pressure measurement
Measuring point:
Cleaner pipe
Measuring range up to:
6 bar
Medium:
Paper suspension with contaminants
Process temperature:
+25 … +45 °C
Process pressure:
0 … 0 bar
Special challenges:
Abrasion

Quicklime silo

Level measurement in the quicklime silo

Application

Quicklime is an important substance for the recovery of lye in pulp production. It is produced in the lime kiln through the combustion of lime sludge from causticisation. The quicklime is conveyed via a bucket elevator into the quicklime silo, where it is temporarily stored, and then discharged via screw conveyors into the lime dosing feeder for the causticising process. Continuous level measurement in the quicklime silo is required to ensure a reliable supply is readily available.
 

Your benefit

Reliable
Reliable readings in spite of difficult measuring conditions
Cost effective
Maintenance costs are saved through air cleaning of antenna
User friendly
One radar sensor for all silo sizes

 

Process data

Measuring task:
Level measurement
Measuring point:
Silo
Measuring range up to:
25 m
Medium:
Pulp
Process temperature:
+40 … +80 °C
Process pressure:
0 … 0 bar
Special challenges:
Dust and noise, material cones and troughs, bad reflective properties

IBC containers for paper chemicals

Level measurement in IBC containers

Application

Various chemicals are used in paper manufacturing to achieve the desired properties in the end product. The media are supplied directly to the production areas in IBC containers and added to the paper suspension via metering pumps. Level measurement ensures the supply for the ongoing processes. The stocks are continuously monitored, which allows a dwindling level to automatically trigger an order for replenishment from the chemicals distributor.
 

Your benefit

Reliable
Accurate measurement, right down to the container bottom
Cost effective
Sensor can be installed quickly and easily
User friendly
Direct integration into the wireless network, visualisation of the measured values in IPTech Inventory System

 

Process data

Measuring task:
Level measurement
Measuring point:
Tank
Measuring range up to:
1 m
Medium:
Liquids
Process temperature:
-20 … +40 °C
Process pressure:
0 … 0 bar
Special challenges:
Different media, small measuring ranges

Steam pipeline

Flow measurement in the steam pipeline

Application

Steam is needed in the drying section of the paper machine. There it is used to heat the drying cylinders for drying the paper web. The steam is usually generated in the company’s own power plant and fed in via an insulated supply line. To ensure optimal consumption and demand planning, the flow rate is continuously measured via an orifice plate with a built-in differential pressure transmitter.
 

Your benefit

Reliable
Functions reliably under all operating conditions
Cost effective
Toptimal plant operation
User friendly
Simple installation and adjustment

 

Process data

Measuring task:
Flow rate measurement
Measuring point:
Pipeline
Measuring range up to:
16 bar
Medium:
Steam
Process temperature:
+100 … +210 °C
Process pressure:
+6 … +16 bar
Special challenges:
High pressures and high temperatures

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Beer tank

Application

During the brewing process, a thick layer of foam is always present in the beer tanks. Therefore usually two pressure transmitters are used for level measurement. One transmitter measures the head pressure, while the other at the bottom measures the total pressure. The level is precisely calculated from the differential between these two pressures. Hygienic process fittings are absolutely necessary for these sensors.

Your benefit

Reliable Certified materials according to FDA and EC 1935/2004 regulations Cost effective plics® concept: short delivery time and standardized operation User friendly One measuring system, three measured values: level, pressure, temperature