Steam Balance™ describes Pöyry's unique set of high-tech solutions covering everything that is needed to optimise combined heat and power (CHP) plant steam balancing.
Almost all industrial power plants encounter problems when process disturbances occur. Process interruptions such as paper machine web breaks or turbine and boiler trips do not only cause unnecessary down-time for manufacturing processes, but inefficient steam balancing between process and CHP plant also results in notable economical losses by increasing operating costs.
Pöyry has developed a method to integrate power plant control systems together so that the operation is optimised both economically and technically. During the design work all imaginable process disturbances are tested with dynamic simulation utilising Pöyry's own Modysim™ software.
Dynamic simulation in power-plant engineering
Pöyry's control experts assist in all power-plant engineering stages from the first feasibility studies to commissioning ensuring that the power-plant will be started smoothly, operation is stable and process steam availability is high.
Power-plant design methods that are in use today too often presuppose that the steam consumption of an industrial host is completely steady throughout one day´s or one hour´s operation. The reality at many industrial processes such as pulp and paper mills couldn't be more different: steam load typically shifts all the time up and down when breaks on big paper machines and cyclical operation of batch digesters take place. Turbine and boiler trips can add their share in the operational challenges.
It is typical that steam-net controls are even today developed only during commissioning by trial and error. It often takes months to get the power plant running reliably and efficiently after the initial start-up.
In Pöyry's CHP plant engineering these disturbances are tested already in the early stages of the power-plant concept development with Modysim™, Pöyry's own steam-network simulator. With the simulation it can be ensured that
- process component dimensioning is correct
- possible steam accumulator is correctly dimensioned
- steam-pressure control configuration is correct, also in the turbine and boiler controls
- highest possible steam availability can be achieved
- CHP plant can be commissioned quickly without control related teething problems
Steam-net optimisation projects
Pöyry has the know-how to stabilise any fluctuating steam-network. The solution requires controller reconfiguration in the plant DCS and in some cases an installation of a steam accumulator. Pöyry has carried out more than 40 steam-net optimisation projects all over the world offering the clients significant value.
Surprisingly many industrial power plants have serious problems with unstable steam pressures. They are not only an operational challenge: economic losses due to inefficient steam balancing are typically between EUR 0.2 million and EUR 2.0 million annually at almost all paper mills.
Pöyry has a unique track record in optimising power plant steam balancing. Over the years the work process has become straightforward, and there are already over 40 successful references all around the world.
A typical project starts with a control audit including feasibility estimation of the implementation.
In the second phase the feasibility is calculated accurately with the help of a steam-network dynamic simulation with the Modysim™ programme.
In the implementation phase a specification for the control modifications is prepared. Pöyry's specialists supervise the reconfiguration of the turbine and automation systems and after that finetune all the controllers. Steam pressure stability in the low-pressure header typically achieved in our projects is ± 0.05 bar during stable conditions and ±0.1 bar during disturbance situations.
A steam-net optimisation project often has a short pay-back time, typically less than a year.
Steam Balance™ EPC Package
A turn-key delivery of a steam accumulator and advanced controls
Pöyry has carried out over 40 steam network optimisation projects having gained solid experience on both steam-network controls and steam accumulator installations.
A steam accumulator is a powerful tool in steam-network stabilisation and economic optimisation of the operation. However, as a steam accumulator itself is only a pressure vessel, it needs to be equipped with an advanced control system in order to get the most of the equipment.
Pöyry is the only company in the world able to deliver a total solution for steam balancing as turn-key supply. The delivery can include steam accumulator vessel, an advanced steam-net control system and functional guarantees.