The paper industry is the basic raw material industry of the national economy and an important industry closely related to social civilization and economic development.
The paper-making process is a complex industrial process of mass and heat transfer, which is mainly divided into two parts: pulping and paper-making. The pulping process mainly includes cooking, washing, screening, and bleaching. The paper-making process mainly includes paper material preparation, pulp flow, paper surface forming, wet paper press dehydration, drying, paper sheet calendering, and coiling. The recovery process is an environmental protection-supporting process focusing on evaporation, combustion, and causticization.
A large number of containers such as towers, pools, tanks, and barrels are used in the production process of pulp and paper making. All kinds of pulp in the production process need to be stored, transported, and processed in these containers. In order to ensure the accuracy and efficiency of the entire process, enterprises have implemented computer control systems, and the demand for intelligent pressure transmitters has also increased.
The intelligent pressure transmitter can be used in conjunction with the computer control system to measure the pressure, differential pressure, flow, liquid level, and other information in the pulp and paper production process, which greatly improves the production capacity of the equipment and reduces the product consumption and operating costs.
Distributed Control System is one of the automation technologies of the pulp and paper production process, which can truly realize the optimal control of the industrial production process. The structure of DCS is mainly divided into four layers: field instrument layer, control unit layer, factory layer, and management layer. Field equipment is used to measure various process parameters such as pressure and temperature for display, recording, or control. Obtaining accurate and reliable process parameters is the basis of control. Therefore, monitoring in the DCS system is very important.
1、MDM6000 Series Intelligent Pressure Transmitter
MDM6000 series intelligent pressure transmitter adopts advanced monocrystalline silicon piezoresistance technology and can output 4~20mA+HART, Modbus-RTU/RS485, and other standard signals. The product has a communication function, which can carry out two-way communication in the control room, transmitter site, and other places connected with the control loop to complete the setting, monitoring, and testing of parameters.
Range: 60mbar ~400bar
Accuracy: ±0.075%, ±0.1%, ±0.2%
Long-term stability: ±0.2% SPAN/5years
Working temperature: - 40 ° C~85 ° C
Medium temperature: - 45 ℃~105 ℃
Output signal: 4mA~20mA DC+HART, Modbus-RTU/RS485
Power supply: 10.5V/16.5V~55V DC
Certification: Intrinsically Safe (NEPSI), Explosion Proof (NEPSI), CSA, CE (TUV), RoHS, IP67, HART
2、MTM4831 Temperature Transmitter
MTM4831 temperature transmitter is available for measuring temperature from -200 ℃～500 ℃ of various liquid, gas or solid surface directly. It uses a special temperature module to make linearity corrections on temperature sensing elements, outputting a standard analog/ digital signal. With various outputs, it is easy to apply temperature measurement in many different fields.
Power Supply：10V～30V DC（Typical：24V DC）15V～30V DC（Display）
Output: 4mA～20mA DC；4mA～20mA DC+HART；4mA～20mA DC + RS485； RS485；Thermal Resistance
Accuracy：±1.0%FS (-200℃…0℃～500℃ )
±0.5%FS (-40℃…0℃～150℃ )
±0.25%FS (-20℃…0℃～105℃ )
Display: 4-digit LCD/LED
Stability: ±0.5%FS/year (general)
Ambient Temperature: -25℃～70℃
Relative Humidity: ＜95%
Flameproof Sign: Ex d IIB T6 Gb
The common measurement of pulp and paper making is liquid level measurement and pressure measurement, and the medium is usually pulp, steam, clean water, white water, chemicals, paint, etc. Different measuring objects choose different transmitter types, otherwise, the measurement purpose will not be achieved and the difficulty of later maintenance will be increased.
In pulping and papermaking, the pulp is the water suspension of papermaking fiber, which is easy to form flocculation, causing blocking and hardening, so the flange-type intelligent pressure transmitter is suitable for the liquid level and pressure measurement of pulp. According to the installation location and equipment conditions, choose to use a single flange intelligent pressure transmitter or a flange intelligent remote pressure transmitter.
When measuring the pressure of medium with high viscosity and easy to scale, such as pulp, white water, black liquor, etc., it is necessary to increase the diameter of the impulse pipe and install a valve outside the pressure tap to facilitate the dredging and cleaning of the impulse pipe without shutdown. For the flat flange pressure transmitter, when measuring the liquid level of easily precipitated substances such as white mud and pulp, a valve for flushing shall be installed on the short pipe to flush regularly to ensure that the pressure tap is unblocked and accurately measured. If the zero position and range of the transmitter are found to be different from the actual measured value after a period of use, the transmitter shall be removed and the diaphragm shall be cleaned regularly.
In pulp and paper making, chemical pulping, deinking chemical preparation, and coating preparation and storage also need to be measured for liquid level and pressure. Most of these media are corrosive or viscous liquids. A flat flange pressure transmitter should be selected for measurement, and the diaphragm material should be corrosion-resistant material, such as stainless steel.
In the 300000-ton corrugated paper project of a paper mill, MicroSensor has successfully helped the enterprise improve the equipment operation efficiency and improve the paper quality.
①Greatly saves the time and cost of manual inspection
②Effectively improves the operation efficiency and product quality
③Provides an important basis for later data analysis