BKT-Service in cooperation with Kadant Johnson Systems has completed a full steam and condensate system rebuild of Selenginsk PPM (Republic of Buryatiya, Russia). The main objectives of the rebuild were to improve runability of the machine, reduce steam consumption and modernize the control system.
A dryer section survey was performed during March 2011 in order to evaluate the project potential and define the goals and objectives of the rebuild. One of the main factors noted during the study, was the need for high levels of flexibility, due to the wide range of grades produced on the paper machine. At the opposite ends of the drying spectrum were double layer linerboard at 250g/m2, which was dryer limited and 70 g/m2 sack paper, which was speed limited! This huge drying capacity variation required high levels of flexibility and turndown on the machine steam system.
In order to achieve the required flexibility, a new three stage cascade system has been installed. Using state of the art technology, the system can also operate as single stage cascade, depending on the paper grade being produced and the pressure/drying curve requirements.
The rebuild included the complete modernization of the drying cylinder hardware with Kadant Johnson, 9800 PTX Rotary joints and cantilever stationary siphons combined with Turbulator TubeTM bars, being installed in all dryers. The control of the system has been developed on a PLC platform which is supervised by the Kadant Johnson Dryer Management System (DMS) controls package. DMS is an expert dryer management software package developed by Kadant Johnson Systems and able to fully support the operators in dryer section operation and management. The DMS package allows a complex steam and condensate system to become quite “user friendly” by automating much of the control system. At Selenginsk mill, the DMS system has been compared to a very skilled operator, who is able to optimize in real-time all the drying parameters needed for the specific grade being produced. Once the optimum conditions are established, they are repeatable whenever this grade is produced and conditions are not influenced by either shift changes or operator ability.The main features of the DMS system are:
- Automatic pressure curve adjustment
- Dynamic pressure set-point limit calculations
- Valve condition monitoring
- Ex-press dryness calculation
- Sheet break management
- Fully automated system start-up and shut-down
- Dedicated remote telephone connection which guarantees full technical support, directly from Kadant Johnson technician’s off-site. This is a key element for this remotely located mill
Following the rebuild, a test run was performed during which all of the guarantees for performance and technical issues were fully satisfied.
Drying capacity has been increased by 20%, specific steam consumption reduced by 5% and machine runability greatly improved with benefits in overall machine efficiency. Sheet break recovery time has been improved and energy losses to the condenser have been reduced to values lower than 2% of the total steam consumption.
Selenginsk management were very pleased to certify the success of the rebuild, signing the test run protocol only 30 days from the machine start-up.