Dual PID process controller for control system of a steam generator

• 1850 Dual loop PID process controller as part of the control system of a steam generator 300Kg /h
• 1850 controller takes care of controlling steam pressure, tank level and also performs math and interlocks functions required by the control algorithm. In addition, it generates alarms, executes plant interlocks and offers diagnostics
• Field bus connectivity and web server functionality of 1850 helps remote access and over view of the plant in secured manner.

The clean steam generator is used to produce pure and clean steam, without harmful substances and impurities.
In this process, a tank full of osmosed water heated by several heat exchangers through which industrial steam passes. The heated water generates the clean steam.
The steam is one of the most used elements to transport energy as it is a safe and efficient energy carrier and it can hold a lot of potential energy (five or six times more than an
equivalent mass of water).
Applications for pure and clean steam can be found in the food, cosmetic and pharmaceutical industries, as well as for sterilization and any direct steam heating process, where steam quality requirements are very high.

The process calls for Dual loop PID process controller with ability to handle complex control algorithm.

Following parameters to be managed

• Pressure of the industrial steam to the heat exchangers
• Level of the osmosed water in the tank
• Process and set point deviation alarms to be interactive with the plant interlocks and plant shut down
• A temperature soft start is requested to avoid any thermal stress of the piping and equipment, as the temperature reaches high values (100 to 400 °C) at the start-up
• To meet the daily or weekly scheduled change of steam demand
• Remote access for product configuration, alarm management and diagnostic

• Precise dual PID loop controller: accuracy 0.1%
• Control features: ratio, cascade, variable set point program
• Configurable analogue Input signals: TC, V, mA, RTD
• Configurable output signal: V, m A, valve control
• Logic input/outputs: 8/16
• Logic and math function blocks, real time clock, totalizer, timer
• Wide and bright LCD display for prominent visibility of operators
• Web server to enable remote service
• Modbus TCP communication protocol for third party equipment connectivity

The dual loop PID controller 1850 provides the accurate control required for the steam generator PID control and configurable Input /Output

• Two PID loops (pressure and level) in one device with 0.1% accuracy: this simplifies installation and use
• Provide digital inputs /outputs (8/16) to perform plant interlocks
• Four configurable process alarms – alerts the operators when the process variables value goes outside allowable range

Temperature Soft start and multiple real time clock

• This function defines the time within which the PID power output goes from 0 to 100% (Figure 2). Needed for the pressure control to obtain a gradual heating at the start-up. This prevents thermal stress on the material and thus avoids any mechanical damage/leak etc.
• Four independent weekly real time clocks to support an early production start or the variation of demand during the working days, nights, weekends etc.

Connectivity and local visualization

• Remote management from a centralized supervision system with the serial/ethernet communication
• Web server connectivity (Figure 3) allows remote diagnostic and management of all the process parameters – can use any device able to access browser (PC, mobile phone, tablet etc)
• The visualization of scrolling messages on local display comes handy to field operators (Figure 4)