THE AIM OF THE PROJECT IS TO DEVELOP A SYSTEM OF SEPERATION BY TANGENTIAL FILTRATION WITH MINERAL MEMBRANE AS A PART OF A NEW UPGRADING PROCESS FOR THE CONVERSION OF HEAVY RESIDUES IN LIGHTER FRACTIONS. THE PROCESS IN DEVELOPMENT IS A THERMOCATALYTIC HYDROTREATMENT WITH A CATALYST INJECTION UNDER LIQUID OR SLURRY PHASE. THIS PROCESS IS ABLE TO CONDUCT A HIGH CONVERSION LEVEL ON RESIDUES UNDER HIGH HYDROGEN PRESSURE. TO ACHIEVE THIS HIGH CONVERSION LEVEL OF RESIDUES INTO VALUABLE PRODUCTS., THE CATALYST IN SLURRY PHASE HAS TO BE IN SUCH QUANTITY AS ITS RECYCLING IS AN ECONOMIC NECESSITY. THE TANGENTIAL FILTRATION ON MINERAL MEMBRANE MIGHT BE A SOLUTION TO SEPERATE LARGE CONVERTED HYDROCARBONS WITHOUT CATALYST AND A SMALL ONE WHERE CATALYST IS CONCENTRATED.THIS CATALYST CONCENTRATE WOULD BE RECYCLED TO INCREASE CATALYST CONCENTRATION IN REACTOR. TWO ASPECTS ARE IMPORTANT IN THIS PROJECT:
- THE CATALYST CHARACTERIZATION
- THE MEMBRANE PERFORMANCES
THE ORIGINALITY BUT ALSO THE DIFFICULTY OF THE PROJECT IS THE APPLICATION OF THIS MEMBRANE TECHNOLOGY TO THE OIL RESIDUES WHERE ARE CONCENTRATED ALL THE MAIN CONTAMINANTS AND THE HEAVIEST COMPOUNDS OF THE CRUDES.
Studies were performed on the separation of dispersed catalysts by ultrafiltering. Preliminary studies involved the preparation of representative samples from catalytic hydroconversion, thorough analysis of the fluid, definition and choice of the membranes for the ultrafiltering loop. The ultrafiltering step involved the adaptation of pilot units to heavy petroleum residue processing, selection and adaptation of an ultrafiltering module and determination of performance levels. Integration of the hydroconversion step and the filtering step were performed to study the effect of catalyst recycling.
A series of tubular metal ceramic composite mineral ultrafilters were developed which can be directly welded to the installation. They consisted of a metallic macroporous support covered with a ceramic mesoporous ultrafiltering layer.
Several types of supports were analysed (alumina, nickel, stainless steel, carbon) and various types of layers have been studied with pore radii from 130 to more than 1000 angstroms. Membrane geometry was also researched with respect to smooth or twisted tubes.
The various membranes selected were tested under highly varied operating conditions. First of all, with light cycle oil (LCO) to understand the phenomena implemented and to enable membrane selection than on real feedstocks under conditions close to those used industrially.
An optimum pore radius has to be defined and which probably is between 250 and 500 angstroms.
With regards to the membrane twist effect, a comparison was made on 3 sets of membranes characterized by very similar pore radii. Only 1 case was recorded with a flow rate on a twisted membrane much higher than on a smooth membrane.
Real load tests showed good selectivity with regards to molybdenum separation, but found a low dependance of performance with regards to operating conditions and low production rates during tests with catalytic hydroconversion residue.
These experiences, as well as those related to the study of the pore radius, show that the catalytic hydroconversion residue must not be fluxed but must be at a much higher temperature to reduce its viscosity.
Tests were performed with a lubrication oil base, less viscous than the catalytic hydrovisbreaking residue, nonfluxed with LCO. To reach the same viscosity as that of the oil base, it is necessary to heat the catalytic hydrovisbreaking residue to a 280 to 300 C which was not possible in the test installations.
THIS PROJECT COVERS SEVERAL ASPECTS - SO.E OF THESE ASPECTS ARE KNOWN, OTHERS ARE TO BE CONFIRMED. FOR THESE REASONS SEVERAL PHASES ARE DEFINED.
PHASE 1 - PRELIMINARY STUDIES
THESE STUDIES COVER THREE ASPECTS:
1.1. - STUDIES ON CATALYTIC PRECURSORS
SEVERAL TYPES OF CATALYTIC PRECURSORS WILL BE STUDIED IN BATCH OPERATION IN REACTORS. OPERATING CONDITIONS WILL BE CHECKED. THE LIQUID EFFLUENT WILL BE FILTERED. THE SEDIMENTS WILL BE WEIGHTED AND ANALYSED TO UNDERSTAND THE REACTION MECHANISMS.
1.2. - SAMPLE PREPARATION
A LARGE SAMPLE OF HYDROTREATED EFFLUENT WILL BE PREPARED WITHOUT CATALYST RECYCLING IN ADJUSTED OPERATING CONDITIONS. THE COMPLETE ANALYSIS OF THIS LIQUID WILL BE DONE:
- MOLECULAR WEIGHT REPARTITION
- ASPHALTENE AND METAL CONTENT
- STANDARD PETROLEUM TESTS
- CONCENTRATIONS, SIZE, CHEMICAL COMPOSITION OF PARTICULES
1.3. - MEMBRANE SELECTION
AFTER COMPLETE REALISATION OF THE ULTRAFILTRATION LOOP, SEVERAL TYPES OF MINERAL MEMBRANES WILL BE TESTED AND SEVERAL PARAMETERS WILL BE STUDIED:
- PORES DIAMETER
- PRESSURE GRADIENT
- TANGENTIAL VELOCITY
- TEMPERATURE
THE BEST SOLUTIONS WILL BE SELECTED FROM THESE RESULTS.
PHASE 2 - ULTRAFILTRATION STUDY
THE SELECTED MEMBRANES WILL BE USED IN A SET OF OPERATING CONDITIONS REPRESENTATIVE OF INDUSTRIAL ONES.
2.1. - ULTRAFILTRATION MODULE
AN ULTRAFILTRATION PILOT PLANT WILL BE CONSTRUCTED IN SOLAIZE IFP CEDI CENTRE FOR WORKING IN OPERATING CONDITIONS SET AT TEMPERATURE OF 200 CELSIUS DEGREES TO 240 CELSIUS DEGREES AND A PRESSURE OF 50 BARS.
2.2. - HYDROTREATED EFFLUENT ULTRAFILTRATION
TWO OR THREE HYDROTREATED FEEDSTOCKS WILL BE STUDIED AT THE CEDI PLANT ON THE SELECTED MEMBRANE.
THE EVOLUTION OF REJECT RATIO FOR SOLID PARTICLES, FILTRATE FLOWRATE WILL BE STUDIED ACCORDING TO OPERATING PARAMETERS: MEMBRANE, PRESSURE DIFFERENTIAL, TANGENTIAL VELOCITY, TEMPERATURE, PARTICLES CONCENTRATION, DECOLMATING PERIODS.
THE FEEDSTOCK, THE FILTRATE AND "RETENTATE" WILL BE ANALYZED FOR PARTICLES ASPECTS AND CHEMICAL COMPOSITION.
2.3. - EVALUATION OF USED MEMBRANE
THE MEMBRANES AFTER USE WILL BE STUDIED AS IN PHASE 1.
PHASE 3 - TEST WITH RECYCLED CATALYST
THE AIM OF THIS TEST IS TO TEST AT THE SAME TIME:
- THE ACTIVITY OF RECYCLED CATALYST
- THE FILTERABILITY OF SEDIMENTS
FOR THIS PURPOSE TWO PILOT PLANTS WILL BE CONNECTED; THE HYDROTREATING PILOT PLANT THAT WILL PRODUCE A SAMPLE OF HYDROTREATED EFFLUENT CONTAINING THE CATALYST IN SUSPENSION AND THE ULTRAFILTRATION PLANT THAT WILL PRODUCE "RETENTATE" FRACTIONS CONTAINING THE CATALYST WHICH WILL BE RECYCLED TO THE HYDROTREATING PLANT.
THIS TEST WILL PROVIDE ALL THE DATA TO EVALUATE THE OPERABILITY AND THE PERFORMANCES OF THE SCHEME BY COMPLETE MATERIAL BALANCE AND PRODUCTS ANALYSIS.
PHASE 4 - RESULTS AND CONCLUSIONS
THE OVERALL RESULTS WILL ALLOW TO ESTABLISH A COMPLETE PROCESS SCHEME AND A TYPICAL MATERIAL BALANCE. AN ECONOMICAL STUDY WILL EVALUATE THE INTEREST OF THIS INTEGRATED SCHEME. COMPLEMENTARY INFORMATION WILL BE PROPOSED TO ACHIEVE A PROCESS WITH A COMMERCIAL INTEREST.
