iX challenge: Kiln waste heat recovery for use in brick and tile dryers

Hinton Perry and Davenhill Ltd manufactures Dreadnought clay roof tiles and Ketley engineering bricks in the West Midlands. The company has operated from the same site since 1805. They are an SME manufacturer, employing 65 people. They are looking for ways to capture waste heat from their kilns for use within the brick & tile drying chambers at their Dudley site in the West Midlands.

Currently, bricks and tiles are dried within drying chambers using natural gas as the primary source of heat. Hinton Perry and Davenhill would like to explore the possibility of capturing waste heat from the exhaust flue gas from the kilns to replace the natural gas used to heat the drying chambers.

Waste heat is currently used only from the cooling part of the cycle and direct air can only be used in the later stages of the drying cycle. If the high-temperature waste heat was directly added into a dryer at the start of the drying cycle it would destroy the humidity conditions and as a result, the bricks and tiles would crack. Hinton Perry and Davenhill would like a solution that will allow the waste heat from the kiln firing cycles to be used for the whole drying cycle without affecting the quality of the bricks and tiles.

The waste heat is currently transferred from the kilns via a centrifugal fan and hot air ducting system.

Hinton Perry & Davenhill have data for the energy available from the shuttle kilns using 2018 as the reference year, mapped over the energy requirements for drying bricks and tiles for every hour, 24/7 over 52 weeks. Emission data is also available for the firing of bricks and tiles.

The site currently relies on natural gas and electricity to meet the demands of their operations. They are supplied to the site via the grid.

• Gas consumption, Kilns – 39018 MWh
• Gas consumption, Drying chambers – 4335 MWh

The kiln exhaust flue gas temperatures are given below:

• 1 Tunnel kiln = 71°C (continuous operation, 24 hours/day, 7 days/week)
• 5 large shuttle kilns = 106-476°C (operating 24 hours a day, 7 days/week intermittent firing and cooling)
• 3 smaller kilns = 50-400°C (operating 24 hours a day, 7 days/week intermittent firing and cooling)

The amount of waste heat produced from all the kilns = 513kW per hour.

Brick drying chambers require 115°C temperature for 66 hours. They are in the same building and approximately 50m from the kiln exhaust. The Brick drying chambers have a volume of 150m³ each.

Tile Drying Chambers require 90°C for 180 hours. They are in a separate building and approximately 100m from the kiln exhaust. The tile drying chambers have a volume of 216m³

There are obstacles in between kilns and drying chambers, namely mechanical handling equipment for bricks and large diameter ductwork.

There is no room available for heat exchangers to be sited directly next to each kiln, it has been envisaged that a centralised unit 10-35m from the kilns is the only suitable area.

Hinton Perry and Davenhill Ltd would look more favourably on solutions that are able to be implemented while high levels of production are maintained, help deliver on their net zero carbon strategy and have achieved a TRL of 8 (demonstrated at scale in an operational environment).

Entrants to this competition must be:

• Established businesses, startups, SMEs or individual entrepreneurs
• UK based or have the intention to set up a UK base