Projects

TEC-1, Technology

Our home page has already informed about the modernization project of Riga Steam Power Plant TEC-1 where we have taken part. The purpose of this account is to present a slightly more expanded concept of technology implemented in automation systems of heating boilers unit of the plant. A detailed description would certainly take many pages and unlikely appeal to a majority of readers, therefore only the basic principles have been presented hereinafter. Those of you who would need a more detailed account, please see a list of contacts in Contacts section of the page.

 

Boiler houses of Riga TEC-1 are highly automated and integrated systems that are operated without any manual intervention to maintain the required parameters of various systems and to start the facilities. As it was mentioned in the account of projects, there are two boiler houses on TEC-1.

1)      A central one, that consists of two water boilers – 116MW each, a pumping unit including three pumps and a supply line to ensure the minimum pump circulation, a boiler bypass.

2)      A supplementary one consisting of a boiler, 116MW, a pumping unit including two pumps and a supply line to ensure the minimum pump circulation, a boiler bypass and a connection line to the main boiler.

 

Each boiler is equipped with an air injection fan, exhauster, recirculation pump, a set of valves and adjusters, four bi-combustible burners (gas or diesel).

The automation system of the boiler houses is divided into parts – a control of a certain boiler and its operational equipment  (separately for each boiler); a control of all facilities of a corresponding boiler house (separately for the central and supplementary boiler house).

Automated control system of the boiler supports the required water parameters, such as:

1)      The minimum boiler circulation to ensure safety of its water pipes from overheating.

2)      Boiler’s output pressure - a protection from the inner steam generation.

3)      Temperature of the boiler’s inlet point (following ignition and reaching the desired temperature at the outlet point) – protection against condensation.

 

Besides, it provides automatic parameters required to set the desired boiler capacity on a particular moment and ensuring a safe and the most efficient fuel combustion:

1)      A pressure inside  the air supply panel of the burners (varies according to capacity settings), fine adjustment of the combustion stability as well as reduction of boiler emissions.

2)      Furnace exhaustion (including the maximum workout at the ignition during an inevitable upsurge).

3)      Combustible pressure in front of the burners (gas or diesel fuel).

 

The automation system of the boiler houses provides the required water parameters as well as supports, with the help of the pump unit, the necessary pressure at the boiler outlet depending on a current situation or the overall consumption of the boiler house; besides it can limit a boiler consumption by a cool bypass of the boiler house, securing a minimum consumption rate via the pump unit. The main task of the boiler house control panel is to maintain the desired temperature at the network output achieving that by adjustment of the boiler loading and water distribution.

As it has been previously described in the acount of this project, the supplementary boiler unit of TEC-1 is able to operate both ways – completely autonomous or combined with the central boiler house unit.

Switching from one mode to another with a corresponding change of control logic and methods of load and water distribution is automatic and only requires an operator to insert the closure command of end fittings.

In a shared mode the main controller of the central boiler house operates three boilers and five pumps as a single unit, deactivating a supply line ensuring the minimum consumption of the pump unit and a bypass of the supplementary boiler house. All operating boilers are aligned according to their loads and consumption despite the diferences in hydraulics.

If necessary, an operator can manually set a loading of a specific boiler, in that case any excess of the required total loading is distributed via boilers which are operated automatically.

In the case of autonomous mode of the supplementary boiler house, general controllers of the boiler houses operate independently, each maintaining its own temperature parameters and water settings – the pressure or consumption.

Power connection of boiler houses (regardless of the supplementary boiler house mode), ignition of the boiler, its halting and network disconnection takes place automatically on both boiler houses. Fully automatic power connection of the stopped boiler house takes less than 15 minutes, a startup of a boiler – further 15 minutes, respectively, an operator is able to operate the boiler within 30 minutes when required, and the boiler is completely ready  to be set the required loading parameters.

In case of extinction of one or more burners, a corresponding boiler keeps operating on the remaining burners, though without any option to increase its loading. After an operator has inserted a command of reducing the boiler’s loading and reaching parameters suitable for burner ignition, a boiler restarts  automatically and is available again for a full range operation. While on standby waiting for an operator’s command, this case may result in a possibility of restarting the supplementary boiler and minimizes the effect of temporary capacity loss.

Regardless of the operating mode, automated control system operates potentially dangerous parameters of boilers (pressure of water, air, combustibles; water flow rate, furnace exhaustion, water temperature, a critical failure of main sensors, flame lift-off from burners), as well as boiler houses (water pressure at various points, gas leakage, sensor failure, ventilation system breakdown) and in case of a hazardous situation operates correspondingly.