Skip to main content
European Commission logo print header
Content archived on 2022-12-27

UPGRADING OF RESIDUAL REFINERY TARS BY COMBUSTION

Objective

Deep conversion processes including solvent deasphalting and hydrotreatment lead to asphaltic residues like pitches or tars. The aim of the project is to use these residues instead of conventional fuels or coals for combustion in existing installations and demonstrate their potentialities.
The main results form this demonstration program are detailed, for each typical application of pitch combustion :
1 Substitute of conventional heavy fuel oil :
The pitch is diluted as to obtain a viscosity of 40 cSt at 100 deg. C. The purpose of this demonstration is to replace conventional heavy fuels by a mixture containing equal parts of pitches and cutter stock for combustion in existing boilers. The demonstration was run on a Babcock boiler of the type FM 9-52, subject to operating conditions prevailing at the Centre de Developpement of the IFP at Solaize. The efficiency of the installation and the thermal yield are maintained. The use of high performance burners is recommended so to limit the emission of pollutants.
2 High viscosity heavy fuel oil :
The purpose of this demonstration is to promote a cheap fuel for important units used in chemistry, oil refining and petrochemistry. The cutter stock content has been reduced by about 50 % compared to the previous formulation.
The demonstration was run on a 12 MW experimental furnace of the TOTAL Research Center at Gonfreville.
The transport, storage and implementation of this fuel requires a few modifications in order to supply the burner at high temperature. Emission of pollutants can be controlled by adjusting the rate of atomization steam. The efficiency and the thermal yield are maintained.
3 Pitch and coal aqueous slurry :
The purpose of this demonstration is to incorporate hard pitches into coal/water mixtures, so to increase the heating value and reduce the sulphur and ash content of the suspension.
The demonstration consisted in the preparation of a solid pitch, the crushing, the suspension and the combustion of the mixture. Production of the suspension (60-65 % of dry matter) by crushing a mixture of pitch and coal has been achieved in a prototype unit FLUOCARBELF. A Babcock boiler of the type FM-9-43 has been adapted by modifying the fuel supply circuit, the air preheating system and the burner. Combustion tests showed that it is necessary to improve the quality of the suspension so to facilitate its implementation and limit the production of pollutants.
4 Aqueous pitch slurry :
The purpose of this demonstration is to use directly hard pitches without fluxing agent in refineries, petrochemical and chemical plants.
Hard pitches were dry crushed in a vertical ball crusher, then put in suspension. The 64 % dry matter suspension was then stored for six months before it was burnt. Implementation of this suspension does not raise any operating problems but requires the simultaneous use of fuel-gas to stabilize the flame. The productivity of suspension preparation equipments could be improved.
5 Pulverized solid pitch :
The purpose of this demonstration is to use solid asphalts in pulverized coal units for chalk and cement industries.
European energy policies intended to decrease crude oil consumption have resulted in greater reductions in residual oil consumption than of other petroleum products. This means that more light components have to be produced from the same barrel of oil and the European refineries have already been upgraded, by building catalytic cracking and visbreaking conversion units. Since these trends are likely to continue in the future, refiners are increasingly considering the use of deep conversion units, to upgrade the residues into more valuable products.
The most promising techniques are solvent deasphalting and hydrotreatment which also produce a viscous pitch of high softening temperature. This pitch can be used as fuel but requires specially adapted or developed combustion technologies.
The main markets for this product are the following:
1) Plants using liquid fuels could handle the pitches, either diluted by cutter stocks or dispersed into aqueous suspensions or emulsions. The plant equipment would need some modification to safely handle the pollutants contained in the tars. Such plants are common in heavy steam-using industries such as refineries, petrochemical and chemical plants. They generally operate either as:
- cold wall equipments, such as fire tube boilers or water tube boilers, or
- hot wall equipment, such as refinery process ovens.
2) Plants using pulverised solids are mostly found in the chalk and cement industries, which have been using heavy fuels, pulverised coal and more recently petroleum coke.
Refinery pitches seem particularly suited for such applications without the need for substantial plant modification. The fact that the finished product absorbs the sulphur emitted is a plus from an environment standpoint.
3) Plants operating 'fluidized beds' are relatively recent and were designed to handle difficult fuels either with high ash or high sulphur content. These plants are used mostly for residential or industrial heating. The combustion of refinery tars in 'fluidized beds' offers the following advantages:
- high combustion efficiency
- very low level of pollutants emission.
The project consisted in testing the pitches from the ASVAHL deasphalting plant for demonstration in six applications.

Call for proposal

Data not available

Coordinator

GERTH
EU contribution
No data
Address
232 AV. NAPOLEON BONAPARTE
92500 Rueil Malmaison
France

See on map

Total cost
No data