HOT VAPOUR FILTER DESIGN AND OPERATION IN PDU-SCALE

Objectives
The objectives of the task include:
- To install a hot vapor filter to an existing Process Development Unit (PDU)
- To verify operation of the filter in continuous operation
- To produce hot vapour filtered product oil

Tasks
The tasks included are:
- To install a hot vapor filter to an existing Process Development Unit (PDU)
- To verify PDU operation after modifications
- Initial test with the HVF
- HVF pyrolysis oil production for tests and analysis
- Reporting of the HVF operation

The PDU has been operating since 1996 with a total liquid production of more than 31 tonnes in more than 2000 h of operation.


Data concerning the PDU operation is presented in the Figures below. Availability and operation hours for experimental runs during 1998 - 2004 are presented. Availability has been defined for each test run as total hours in production divided by total hours planned operation before the test. On average the availability has been during the past years slightly below 90 %. Amount of pyrolysis oil produced during 1996-2004 is also shown below.

 

The PDU has been modified. First experimental run without the filter was carried out in March 2004 to verify new equipment, measurements and controls.
The test period was between May 2004 and February 2006. The objective for the HVF runs was to operate hot vapour filter continuously with pyrolysis vapours.
Auxiliary material is fed to the line before the filter to improve filter dust removal. The primary criteria employed assessing the HVF performance operation is the pressure drop across the filter.

The first test with a HVF was unsuccessful. During a 5-hour operation, the pressure drop across the filter increased continuously. Back-pulsing of the filter did not yield the desired reduction in pressure drop.

After some tests with several modifications to the system and different operating parameters, a more successful 10 hour test was carried out recently.

 

Although the filter pressure-drop increase was substantially improved and operation was smooth, nevertheless pressure-drop increase was continuous.

The conclusion is that with the present experimental arrangement HVF of pyrolysis vapours does not appear feasible.