Manufacturers of Timber Drying Kilns for over 40 years 01621 785

Firewood Logs & Woodchip Drying Kilns

Kiln Services manufacture a wide range of firewood log drying kilns, along with some dual purpose options for both logs and woodchip. Batch sizes of between 12m³ and 200m³ are available.

There are three options for loading:

  1. In crates or IBC units
  2. Hook bins - up to 3 per kiln
  3. By bucket loader onto the drying floor within the kiln.

Our modular design for crates provides for low-cost expansion. This is done by using the original door set with surrounding insulated panels, plus the original control system. Heat exchangers in each module are connected within the kiln, therefore providing the boiler or heat source is large enough, no external modifications need to be made to the original boiler plant.  

There are three sizes of modular kilns to choose from. 12m³ per module, 20m³ per module and 30m³ per module. All can be increased by adding intermediate modules, so for example, a one-module 20m³ kiln can be extended to a five module 100m³, as demand increases.

Adding modules does not alter drying time, as each module has the same air velocity, heat output and venting capacity. All of our kilns have many features designed to maximise efficiency and provide fast drying times. Firstly, with the exception of our direct hot air design, all kilns are of multiple air pass design. This means that kilns do not vent continuously - the hot air is forced through the log stack at high velocity. We reverse the air flow every two hours to ensure the batch is dried evenly. This also speeds up drying, as the air will find a different path through the log stack. The same hot air is passed through the log stack hundreds of times, absorbing moisture from the stack. It is only when this hot wet air achieves the set humidity condition as set in the drying program, that the ventilators open, exhausting the hot wet air and introducing fresh dry air. Once the humidity of the air in the kiln has fallen, the ventilators close until the humidity has again achieved the set condition.

To appreciate the efficiency of this type of control, 1 cubic metre of air at 20° centigrade at 100% RH only holds 14 grams of water, but at 70° centigrade the same m³ of air can carry over 200 grams of water.

On single air pass systems, where the hot air only has a single pass over the log stack, very little moisture is in each cubic metre of hot air vented.

Converted shipping containers can require 5 or 6 times as much hot air to be vented to remove the same volume of water vapour.

Boilers used to provide heat can be either automatic wood chip systems, hand fired biomass, or fossil fuels such as kerosene or natural gas.

All of our multiple air pass kilns have the option of heat recovery. This system replaces the standard venting equipment and uses the hot wet exhaust air to pre-heat the fresh dry inlet air. Inlet air temperatures can be increased by 40° centigrade through this system, reducing heat consumption and running costs by up to 20%.

When logs are freshly cut, depending upon the species, they will have a moisture content of between 50 & 80%. At these levels of moisture content each kilogram of wood can contain between 500 and 800 grams of water. Therefore, a log weighing 1500 grams with a moisture content of 50% contains half a litre of water. This means that most of the energy in the freshly cut log is used to evaporate the moisture and very little for the primary purpose of producing heat.

Another factor for consideration is the amount of air required to burn wood at high moisture content; remember each cubic metre of air flowing up the chimney is an extra cubic metre of fresh cold air coming into a room which has to be heated.

Other advantages of using kiln dried logs is that the kilning temperature of 70 degrees centigrade sterilizes the logs and removes all traces of wood boring insects etc.

When dry, and burnt efficiently wood is a renewable carbon neutral source of energy.

A log drying kiln holding 80 cubic metres of logs per batch load. This kiln dries two batch loads per week.

A log drying kiln being loaded with crates that the customer has made from reclaimed scaffold sections.

Our smallest modular kiln, 1 module 12m³ capacity, supplied with integral boiler room. This kiln can be supplied as a hot water multiple air pass, or for a 60kW hot air biomass blower.

A dual purpose 56 cubic metre log and wood chip drying kiln that is ideal for those companies who want to dry woodchip & logs in the same kiln load. The kiln can be supplied to hold batch loads from 28 to 112 cubic metres.

A forklift truck loaded with a log cage with reinforced sides allowing rotation of the cage. Each cage is 1200mm wide x 1200mm high x 1000mm deep and holds 1.4 cubic metres of logs.

Our top quality wood log crates are designed for kiln drying with large gaps for good air circulation and are 1.2 cubic metres.

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