Steam heater automation. The object of control is the air temperature in the grain dryers. To maintain the set temperature, steam heaters are used, in which water vapor from the heating unit heats cold air from the street, which is supplied to the heat exchangers by fans.
Steam is supplied to the heaters through valves with pneumatic actuators. The temperature of the steam that is supplied is controlled by the control system.
To protect the heaters from freezing, the system uses sensors for outdoor air temperature, condensate outlet temperature from each heater and antifreeze thermostats.
Control algorithms
After start-up, the System switches to the “Soft start” mode, in which the steam supply valve opens smoothly to warm up the pipelines, or to the “Operation” mode, in which the system maintains the set air temperature in the dryers.
When stopped, the System can maintain the set condensate temperature (the so-called “Standby” mode). The system will automatically enter this mode during normal operation if the dryer air temperature sensor fails.
The system operates continuously throughout the year, distinguishing between "Winter" and "Summer" seasons. In order to protect the air heater from freezing in winter, the algorithms of the system operation in winter and summer seasons are different. The transition between seasons occurs automatically according to the readings of the outdoor temperature sensor. But the System settings allow you to disable the automatic transition between seasons.
The difference between the summer and winter algorithms of the System operation is that in summer the system automatically switches to the “Standby” mode only if the air temperature sensor in the dryer fails. In winter, the transition is automatically carried out either in the event of a failure of the air temperature sensor in the dryer, or when the system detects a threat of freezing the heater (activation of the frost protection thermostat or a decrease in the condensate temperature at the outlet of the heater).
Additionally, when a threat of freezing of the air heater is detected, the System limits the lower position of the steam supply valve so that the pipelines remain heated.
System access
The system is accessed either locally or remotely. For local access, a touch panel is used, which is installed on the door of the control room. Screens have been developed for the panel, which display information about the operation of the System, as well as screens for its settings.
Remote access means that responsible persons have constant access to the System via the Internet. For this, a web server built into the controllers is used, for which web pages have been developed that contain information about the operation of the System.
Steam heater automation. Features of the System
The main features of the System are:
- well-developed and tested control algorithms, with the help of which the main tasks set for the development of the System are carried out - a clear
- maintaining the air temperature in the dryers and the inadmissibility of freezing heaters;
- a large number of system settings that allow you to make it flexible;
- keeping a log of events that occur in the System;
- maintaining an archive of values of technological parameters;
- remote access to the system from anywhere in the world (if you have the right to do so);
- friendly interface.