Condensers that turn steam or process vapour back into liquid using air, with sloped tubes so the condensate drains. Designed and built in Stafford by Spiro-Gills Thermal Products, supplied and supported in the GCC by Petromarsh.
Tap a part to see what it does. The red line is the steam flowing down the sloped tubes as it condenses, the blue lines are the air blown up by the fan and out through the bundles.
Steam duct and distribution header. Large-bore duct from the turbine exhaust or process, feeding a header along the apex that spreads steam into every tube.
Sloped finned tube bundles. Two bundles leaning together form the A. Steam and condensate flow down the tubes in the same direction, and gravity drains the liquid.
Condensate headers. Collect the liquid at the bottom of each bundle and send it to the condensate tank or hotwell. Non-condensable gases are taken off and removed by ejectors or vacuum pumps.
Fan. A large axial fan in the deck under the A. It blows air into the space between the bundles and out through the fins.
Gearbox and motor. Large condenser fans are usually driven through a right-angle gearbox. Variable speed drives trim the fans to hold back pressure.
Fan deck and structure. A raised steel deck that carries the fans and bundles, high enough for air to reach the fans freely.
Vapour enters at the top and gives up its latent heat to air blowing across the fins. As it condenses, the liquid runs down sloped tubes to a condensate header. The design must drain liquid freely and remove gases that will not condense.
Condense the vapour from the top of a distillation column, such as a crude or stabiliser column. Usually horizontal bundles with tubes sloped toward the outlet header, typically about 10 mm per metre.
Condense turbine exhaust or process steam, often under vacuum. A-frame bundles at a steep angle drain condensate and fit a large surface on a small plot.
Under vacuum, air leaks in and any gas that will not condense blankets the tubes. A vent section and ejectors or vacuum pumps keep it moving out, so the surface stays active.
The right layout depends on whether you condense steam or process vapour, the pressure, and how much space you have. Tap a type to see when to use it.
Two bundles lean together under a steam distribution header, with fans in the deck below. Condensate drains down the steep tubes to headers at the bottom.
Used where water for a cooling tower is scarce or expensive.
A normal forced or induced-draft cooler with tubes sloped toward the outlet. Often one pass, or two passes with care, so condensate and vapour do not separate badly.
In steam condensers most bundles run steam and condensate downward together. A smaller vent section, often running counterflow, collects the gases that will not condense and sends them to the ejectors.
Extra rows or a separate pass cool the condensate below its boiling point, so it does not flash in the line or a pump.
Variable frequency drives on some or all fans trim the air flow. This holds back pressure as ambient changes and saves fan power at night and in winter.
Steam condensers are mostly carbon steel with aluminium fins. Process overhead condensers follow the fluid, including sour and chloride-bearing vapours.
| Part | Carbon steel | Stainless and duplex | Other options |
|---|---|---|---|
| Header boxes | Plate, forgings and pipeSA-516 Gr 70 · SA-105 · SA-106 Gr B | 304L, 316L, duplex 2205SA-240 · SA-182 · SA-312 | Low-temperature carbon steel, impact testedSA-516 with SA-20 · SA-333 · SA-350 LF2 |
| Tubes | Seamless or weldedSA-179 · SA-214 · SA-334 | 304L, 316L, duplexSA-213 · SA-249 · SA-789 | Admiralty brass, copper-nickelSB-111 |
| Fins | Aluminium, embedded or extruded, for long life1000-series aluminium | Stainless welded fins for corrosive airwelded spiral | Galvanised steel welded finshot-dip galvanised |
| Steam duct | Large-bore carbon steel duct and expansion joints, designed for vacuum and windwelded plate | ||
Process condensers follow API 661. Steam condensers for power use the same pressure codes and their own performance test code.
Requirements for air-cooled heat exchangers in petroleum, petrochemical and natural gas plants: headers, tubes, fins, fans, drives and structure.
Pressure design of the header boxes, plugs and nozzles, with the U stamp where it is required.
CE marking for Europe. UKCA under the Pressure Equipment (Safety) Regulations 2016 for the UK.
Rating software from Heat Transfer Research, Inc. Not a code, but the industry reference for air-cooler thermal design.
Performance test code for air-cooled steam condensers.
Performance test code for air-cooled heat exchangers in general.
Sound power found from sound pressure (3744) or sound intensity (9614) measurements. Used to check the noise guarantee.
Non-destructive testing methods, and certified mill certificates for every pressure part.
Material and hardness limits for headers and tubes exposed to hydrogen sulphide.
Your engineers red-line our drawings, you approve the design twice before production starts, and you can witness the tests. Tap a step to see what happens and which documents you receive.
Spiro-Gills Thermal Products has designed and built bespoke air-cooled heat exchangers and finned tube in Stafford since 1946, and has supplied them to more than 100 countries. Thermal design is done in HTRI, welding is to ASTM code, and the company holds ISO 9001:2015. Petromarsh is their exclusive representative in the GCC.
For a condenser, the vapour, pressure and non-condensable gases matter most. The items on the right are enough to start the design.
