A tubular heat exchanger (HE) is designed for regenerative or recuperative heat exchange. Its main function is to return heat from the exhaust air to the supply air.
Technical characteristics of HE:
- Air-to-air tubular heat exchanger
- Heat transfer medium in tubes is steam-air mixture (SAM)
- SAM inlet temperature 70…80 С
- SAM outlet temperature 45…55 С
- SAM flow volume 60000 m3/h
- Air heat exchanger working medium
- Air inlet temperature 20…25 С
- Dry air outlet temperature 45…55 С
- Dry air flow volume 62350 m3/h
- Number of nozzles in the scrubber 20 pcs (Nozzle 490.888 30 CG “Lechler”)
- Water flow at a pressure of 3 bar 380 l/min
Overall dimensions:
- Height – 4600…5100 mm
- Width – 4010 mm
- Length – 4486 mm
- Weight – 6600 kg
Design description
The principle of operation of the tubular heat exchanger (HE) is to transfer heat from warm exhaust air to cold fresh air coming from outside, without mixing the flows. This allows to reduce heat losses during ventilation of premises and save energy on heating dry air to the screen blowing chambers of the hood of the drying part of the paper machine.
HE consists of:
- heat exchanger;
- recuperator frame;
- adapter;
- flexible insert.
The HE is made in the form of a welded structure made of carbon steel and aluminum. The HE is insulated with mineral wool on the outside and sheathed with aluminum-zinc profile sheet. The inner surface of the HE is sheathed with a stainless steel sheet 1.5 mm thick.
Inside the HE there are four sections of the heat exchanger fastened together by a bolted connection. The sections of the heat exchanger are a welded frame made of aluminum profile, aluminum tubes ∅38×1.5 and aluminum sheet 4 mm thick.
The upper part of the heat exchanger is a welded frame made of carbon steel. It is insulated with mineral wool on the outside and sheathed with aluminum-zinc profile sheet. The inner surface is sheathed with 1.5 mm thick stainless steel sheet. In the upper part of the heat exchanger there is a spray with four nozzles (490.888 30 CG “Lechler”) with a fully conical jet for washing the tubes of the sections with warm water (30-40°C). The water supply to the spray is through a pipe that comes out of one of the walls of the upper part of the heat exchanger.
The frame is a welded frame made of carbon steel.
The adapter is a welded frame made of carbon steel, like the upper part. It is insulated with mineral wool on the outside and sheathed with aluminum sheet. The inner surface is sheathed with 1.5 mm thick stainless steel sheet.
The flexible insert is made of carbon steel, stainless steel and fabric (impregnated linen canvas).
A rubber plate with a thickness of 10mm and 5mm, as well as silicone sealant, is used to seal the gaps between the parts of the HE.
The inlet and outlet of dry air of the HE is carried out through the side flanges measuring 4188mm x 730mm (using a pressure fan).
The inlet of the steam-air mixture (SAM) from the ventilation duct of the mine to the HE is carried out through: a heat exchanger, passes through aluminum tubes ∅38×1.5, giving off heat to the air, reaches the upper part of the recuperator, passes through the adapter and is sucked out using an axial fan into the atmosphere.