Description Of The Plant

The Wood Treatment technology that we are offering is a Fully Automated one that uses High pressure Treatment of Wood in a cylinder herein referred to as an Autoclave with Creosote as a preservative.

The creosote plant is designed for the protection of building elements with particular heavy demands, and where special requirements to durability of wood in open area in earth (or water) contact are to be met.

This modern creosote oil process taking place in the plant is tailored for the new types of creosote, which are to be processed at the temperature of 130°C.

Due to the special construction with placing of the autoclave in the storage tank, the filling and emptying timings are extremely short and the loss of heat is very small. This guarantees an optimal penetration and impregnation. An optimal heat transfer is also ensured via a heat exchanger that constantly keeps the impregnating material warm.

The computer-controlled plant is safe for operation and eco-friendly, using a closed cooling system and integrated heating system.


Complete WTT Cr20 Plant For Impregnation Of Wood With Creosote Oil

The plant can as a standard operate with following impregnation processes.

BETHELL PROCESS (full cell impregnation)


FULL CELL PROCESS OR BETHELL PROCESS is adopted when it is desired to have high levels of absorption of the preservative; it involves filling the cells and saturating the cell walls with the preservative. The timber to be treated is placed in the pressure chamber. – charge. The door of the chamber is tightly closed and a vacuum of at least 56 cm of mercury is created and maintained for about 30 minutes. The aim is to force out as much air from the cells as is possible.

Thereafter, the preservative is introduced into the cylinder with the vacuum working.The vacuum pump is stopped when the preservative has completely filled the cylinder. The   charge is subjected to an antiseptic pressure whose intensity depends on

Ø Species

Ø Size of the material being treated

Ø Refractoriness of the material Due to this pressure, the preservative is introduced into the timber. It is maintained till absorption of the desired extent is obtained after which the preservative is withdrawn from the cylinder. The dripping preservative is removed from the timber by applying a vacuum of 38 to 56 cm of mercury for a period of about 15 minutes. This process is fairly effective if the correct technique has been adopted and the right preservative used in the treatment.




The Lowry process is used for some reasonably permeable species or to limit the liquid absorption and omits the initial vacuum of the Full Cell Process. The cylinder is flooded with preservative, the pressure raised and held until refusal is reached. After releasing the pressure, the preservative is returned to the holding tanks and a final vacuum is drawn on the timber to remove excess preservative.

Below is a simplified production cycle of the plant



Nominal and actual capacities:


With a normal exploitation the annual capacity with 330 working days is 17,820 m3 based on 9 m3 wood per charge and six charges per day (two shifts) = 100,000 poles per year


Stack dimensions:


Width: 1,200 mm

Height: 1,400 mm

Max. length: 13,500 mm

50 pieces of Poles Ø 120-180 per charge

Energy consumption:

Electricity connection:

75 kW as 3 x 380 volt, 50 Hz, + 0 + earth + separate earth of min. 10 ohm

Average electricity consumption: 15 kW/h

The plant is supplied in 3 finish-mounted units, and is operational after being placed on a concrete foundation and connected to electricity and an external heat supply.




Cylindrical autoclave

Diameter: 2,000 mm (external)

Length: 13,000 mm (internal); 13,500 mm wood length

Volume: 42,400 litres of liquid

Door: 1 WTT hydraulic fully automatic quick locking door, complete with 1 hydraulic pump and hydraulic equipment. The door is powered by a 1.5 kW electrical motor.

Material: 14 mm HII plate according to DIN 17155

Working pressure: 0 to 15 bar (abs)

Insulation: 150 mm mineral wool insulation covered with galvanized steel plates Internal rails and anti-float holder for the impregnation trolleys.




Dimensions of the storage tank section:

Diameter: 2,200 mm

Length: 14,000 mm

Total storage volume: 52,000 litres of creosote

Material: 8 mm steel plate

Insulation: 150 mm mineral wood covered with galvanized steel plates.

The storage tank is equipped with a manhole, diameter 600 mm and a level indicator.


Heating of the storage tank section and the autoclave:


1 Heat exchanger, for heating of the creosote oil to 120º C in the storage tank section. Heating of the heat exchanger (Boiler) with thermo oil.

1 Circulation pump for the circulation of the creosote oil in the storage tank section through the heat exchanger. Capacity 60 m3/h with 3 bar (abs). It is powered by a 5.5 kW electrical motor.




2 oil-sealed vacuum pumps to establish and maintain a vacuum of up to 0.30-0.15 bar (70 – 85% vacuum). It is powered by a 11 kW electrical motor. Complete with tank with a volume of 1000 litres for storage of the seal oil for the vacuum pumps.

1 transport pump for emptying of the autoclave when the pressure phase has been completed. It is powered by an 11 kW electrical motor.

It has a capacity of 150 m3 1 hour.

1 pressure pump to obtain and maintain a working pressure of up to

13 bar (abs.). It is powered by an 11 kW electrical motor. Capacity 20 m3 with 10 bar (abs).

1 final emptying pump with a motor capacity of 5.5 kW and a capacity of 20 m3/h with 3 bar (abs).

1 Transport pump for filling of the combined pre-heater and storage tank with creosote oil from the external storage tank after each process. Automatic interruption when the desired quantity of creosote oil has been filled up in the pre-heater/storage tank.

Powered by an 5.5 kW electrical motor with a capacity of 60 m3/h with 3 bar (abs)

Filter equipment:

1 filter in the autoclave

1 filter in the pressure circuit


Pipes and valves:

1 complete pipe work containing the following:

– a filling and emptying circuit, diameter 150 mm

– a circulation circuit, diameter 100 mm

– a pressure circuit, diameter 65 mm

– a vacuum circuit, diameter 100 mm

1 mechanical pressure regulation valves

1 electrical safety valve

1 Vacuum tank with a float switch for switching over from the filling to the pressure phase.


Computer Control unit:

The Plant has a fully automatic operation of the plant in accordance with the British and a number of foreign standards.

Hardware equipment consisting of 1 IMB PC as well as 1 A4 printer for printing out the treatment protocols when each process has been completed.

Main process parameters:

  1. a) initial vacuum value as condition for the initial vacuum time with the Bethell impregnation
  2. b) initial pressure value as condition for the pressure time with the

Rüping processes

  1. c) pressure value as condition for the pressure time
  2. d) final vacuum value as condition for the final vacuum time
  3. e) times for:

– initial vacuum

– initial air pressure

– pressure

– pressure phase

– holding phase between filling and emptying

– emptying

– final vacuum

– final emptying

  1. f) temperatures as condition for the pressure phase

Screen pictures with indication of:

1) process parameters, among other things:

– vacuum

– pressure

– nominal and actual time for each process phase

– temperature in the autoclave and the storage tank

– time and date indication

2) fault indication

3) 10 fixed programs defined by the plant operator

4) technical data

5) customer’s data with indication of among other things:

– customer’s name

– process number

– wood volume (entered value)

– wood humidity (entered value)

6) Wood volume calculation based on entered values for thickness, width and length.

Printing out of the process protocol with a selection of the above mentioned registrations and entered values.

Manual control box for operation of the pumps and the valves in case of error on the computer control.

The plant is delivered with a factory-certificate.