AB "Panevėžio energija"

Panevezys, Lithuania
2015

Installation of economizers for boiler

Customer:
AB „Panevėžio Energija“
Senamiesčio g. 113, Panevėžys

Where:
Janonio g.7, Panevėžys

The purpose of the project:
Reduced heat production costs of boiler. There was a boiler room, with two steam, gas boilers of 4 MW firepower each. Operation method: one boiler in operation, one boiler in reserve. Temperature of exhaust flue gases 260-280 C. The client wanted to reduce the temperature of the flue gas - increasing the efficiency of the boiler room.

What was done:
Initially “Gandras Energoefektas” offers a solution to one economizer:
Since 50% of the condensate is returned, water temperature before the economizer ~ 46 ° C (50% of the condensate at 90 ° C + 50% cold water at 4 ° C).
Water is heated in the economizer from c 46 ° C to 85 ° C followed by water transfer to dierator.
Water flow through the economizer - 2.33 m3 / h
Economizer produces 120 kW working with a single boiler.
Designed for operation of two boilers.

Advantages:

• Due to the fact that the boiler has been designed very tight, there was a problem with finding a place for the economizer and bypass was possible only if the economizer is mounted to one of two boiler. The bypass would allow economizer repair during the operation of the boilers.
• Economizer efficiency is higher if you use the water after dieratora.
• Less chance of accidents - the low temperature of the water eliminates the possibility of water boiling in the economizer.

Disadvantages:

• Economizer and tubes are made of stainless steel (water contaminated with oxygen)
• The high cost of the project to the contractor.
• Economizer must be equipped with the steam trap - the low temperature of the water does not exclude the possibility of condensation inside the economizer.
• Equip the dierator with electronic control system - The customer had 2 electrodes above and below the dieratora, which excluded the possibility of adjusting the level in dierator.

The customer insisted on a variant with two economizers:
Heated water after dierator from 105 ° C to 146 ° C water (at 4 bar saturation temperature 151 ° C) is on the verge of boiling.
Water flow through the economizer - 2.33 m3 / h
Flue gas temperature after the boiler 277 ° C, the temperature of exhaust gases from the economizer 160 ° C.
Economizer produces 105 kW of heat.
Should with the assistance of the the controller after the economizer to raise the pressure in the economizer to 6 bar.

Advantages:

• Conventional (classical) scheme
• Easy for contractor
• High temperature of water and flue gas prevents the formation of condensation.

Disadvantages:

• In case of failure of regulator - the accident with powerful hydraulic shocks in the economizer.
• Increased electricity consumption by feed pumps (6 bar)
• After the regulator - the steam-air mixture - an early failure of controller (cavitation)
• No bypass around the economizer - does not allowed due to dense boiler arrangement.

The data obtained after the installation of economizers: