THE NEW GASIFICATION PROJECT AT ENI SANNAZZARO REFINERY AND ITS INTEGRATION WITH A 1050 MWe POWER PLANT

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1 THE NEW GASIFICATION PROJECT AT ENI SANNAZZARO REFINERY AND ITS INTEGRATION WITH A 1050 MWe POWER PLANT Gasification Technologies 2004 Washington, DC October 3-6, 2004 Guido Collodi, Dario Camozzi - Snamprogetti Italy Agostino Cavanna Eni Refining & Marketing - Italy INTRODUCTION Following the new regulation introduced in Europe in the last years, defining more stringent limits for the emissions to the atmosphere, the necessity to find an alternative use for the fuel oil has created a new challenge for the refineries. At the same time the need to improve the Italian power production has pushed Eni, the Italian energy company, to enter the electricity market. In this frame Eni decided to built in the industrial area of Sannazzaro, in northern Italy, a new combined-cycle power plant of 1050 MWe fed by both syngas and natural gas. A new gasification plant, based on Shell Gasification Process (SGP) is under construction by Snamprogetti at the Eni R&M refinery (formerly Agip Petroli), for the production of syngas and hydrogen for internal use. The gasification plant is integrated with the nearby 1050 MWe power plant of EniPower, feeding the syngas to one 250 MWe combined-cycle. Additional 800 MWe are produced by two high efficiency NGCC. The complex will become the 4 th Italian IGCC from refinery residues. CONTEXT OF THE PROJECT Eni Refining & Marketing Division owns a refining system formed by 5 refineries in Italy (Livorno, Sannazzaro, Taranto, Venezia, Gela), shares in Italy (Priolo, Milazzo) and capacity in Europe (Germany, Czech Republic). Progressive reduction of heavy residue market obliged refineries to reduce this production or to find new utilization. This reduction is mainly due to Italian power production that is going to use more gas than fuel oil for environmental and economic reasons. To cope with the above scenario, Sannazzaro refinery has studied the following alternatives: A new Coking Unit; Transportation of fuel oil to the sea for bunker market;

2 Gasification of residue to produce syngas for gas turbine and valuable hydrogen for the refinery. This last option was evaluated in a context of integration with a new 1050 MWe power plant utilizing mainly natural gas. A cost/benefit analysis of the different options led to identify as best solution the realization of a Gasification plant to produce hydrogen for the refinery and syngas to be fed to a dedicated gas turbine, completely integrated with the power plant. Main reasons that conducted to this solution are: 1. A definitive and profitable solution to convert the bottom of the barrel The refinery will arrive to cancellation of fuel oil production (about 5% of total present refinery production) toward syngas production; 2. A consolidated technological solution The well-proven Shell technology (with the important reference of Pernis refinery) was considered; 3. Lower environmental impact compared with other possibilities Gasification minimizes SO 2 emission via a good syngas H2S removal system. With regard to the NOx emissions at the power station stacks, these are minimized utilizing the modern technologies for NOx emission reduction from gas turbine. As far as the Gasification plant configuration concerns, these features have been chosen: Syngas heat recovery with steam production vs. quench technology, to increase the efficiency; Waste Heat Exchanger with internal superheater to avoid the installation of a new furnace to superheat the high pressure steam; Soot Ash Removal Unit to minimize the solid waste production creating a vanadium concentrate easier to handle; Hydrogen recovery unit to obtain a valuable utility for refinery that requires more hydrogen for the desulphurization process; Chemical H 2 S removal, vs. physical, sufficient to guarantee the degree of purity of the syngas in terms of sulphur; Carbon dioxide recovery available for selling; Installation of a Metal-Carbonyls Removal Unit to avoid formation of metal deposit in the gas turbine burners. More detailed description is included in the next paragraphs. The Gasification plant is being constructed by Snamprogetti under an EPC contract up to the mechanical completion including part of pre-commissioning activities. Snamprogetti is also providing engineering, procurement and start-up services for the new Power plant on lump-sum basis. INTEGRATION BETWEEN REFINERY AND POWER PLANT

3 A new 1050 MWe Power plant, owned by EniPower, has been built near the refinery (see the complex block diagram). Eni Gas & Power Natural gas (12.5 km new pipeline) EniPower Ansaldo-Siemens V94-3A.2 (400 MW) EniRefining & Marketing Ansaldo-Siemens V94-3A.2 (400 MW) H2 Gasification plant 50 t/h Tar Syngas Ansaldo-Siemens V94-2K (250 MW) Schematic Complex Block Diagram It consists of three multi-shaft Combined Cycle Units, two of which fed by natural gas (Ansaldo- Siemens V94-3A.2 of about 400 MWe each), and the third (Ansaldo-Siemens V94-2K of about 250 MWe) fed by syngas produced from the gasification of refinery residues, but with the possibility of co-firing with natural gas in order to adjust the heating value when the H2/CO ratio of the syngas is low. The same gas turbine is also able to run with 100% natural gas. Each power module consists of one Gas Turbine of high efficiency and low pollutant emissions, one HRSG, without post-combustion, at three pressure levels (about 100, 30 and 5 barg) with reheat and one condensing type steam turbine (with air condenser). The natural gas supply for the new GTs is ensured by a new pipeline of 12.5 km connected to the national gas distribution grid. This new installation uses refinery services for most part of the utilities and sends to the refinery some Medium Pressure Steam. Main supply to the Power Plant is high quality demineralized water produced from the existing Refinery Demineralization Plant to be used for the High Pressure Boilers of Power Plant and Gasification. Main product coming from the Power Plant is Medium Pressure Steam that allows a decrease of the Refinery Power Plant fuel oil consumption. There are some services and utilities shared with the refinery: fire water and industrial water supply, wastewater treatment and blow down.

4 The above interconnections are already in operation with the exception of the syngas that will be available after Gasification start-up. The integration between Refinery and Power plant requires a continuous sharing of operating information in order to optimize the unit operating management. For this reason a redundant optical fiber connection is in operation to allow signal exchange among the different control systems. GASIFICATION PLANT DESCRIPTION Please refer to the attached Process Block Diagram. AIR NITROGEN BFW HP STEAM AIR SEPARATION UNIT (o.b.l.) OXYGEN SHELL GASIFICATION PROCESS (SGP) GAS COOLING AND COS HYDROLYSIS SULPHUR RECOVERY (Refinery) HYDROGEN SULPHIDE SULPHUR REMOVAL SULPHUR CARBON DIOXIDE EXPORT HYDROGEN RECOVERY STEAM EXPORT HYDROGEN FEEDSTOCK (VISBREAKER TAR) WATER DISCHARGE METAL ASH FLUE GAS TO REFINERY SOOT WATER SOOT WATER FILTRATION AND SWS FILTER CAKE SOOT ASH REMOVAL UNIT (SARU) (SPENT CARBON) CARBONYL REMOVAL SYNGAS (NAT.GAS) POWER COMBINED CYCLE UNIT (EniPower) Process Block Diagram Feedstock The design gasification feedstock is vacuum flashed visbroken residue with the following main characteristics Data on dry basis Design Feed Carbon %wt Hydrogen %wt 9.05 Sulphur %wt 3.54

5 HHV (* = calculated) MJ/kg LHV (* = calculated) MJ/kg Oxygen at 99.5%v purity will be supplied from an air separation unit located outside the battery limit and will be preheated prior to being introduced into the gasifiers. Gasification The non-catalytic partial oxidation of hydrocarbons by the Shell Gasification Process (SGP) takes place in a refractory-lined gasifier equipped with a specially designed, co-annular burner. This design provides efficient gas/liquid mixing and a good flame temperature control. The oxygen, at 99.5 %v purity, is preheated with saturated steam from the syngas cooler and mixed with superheated steam as moderator prior to feeding to the burner. The burner and reactor are designed and tuned such that this mixture is intimately mixed with the feedstock within the reactor. Two gasification strings are provided, each having a capacity of 600 t/d of visbreaker tar. The residue from the visbreaker is run down into a common feed vessel. The feedstock is supplied to the gasifier using a reciprocating feed pump, one for each string. A feed preheater is provided to heat up the feedstock in case it is supplied from tankage instead of being supplied directly from the visbreaker unit. Gasification takes place at a pressure of 62 barg; the temperature of the syngas entering the syngas cooler is approx C.

6 Superheated HP steam Raw syngas to treating section Superheated HP steam from string 2 syngas cooler C Raw syngas from string 2 Scrubber cooler C Feed Pump J steam superheater C /4 Soot Scrubber E Feed Vessel F Feed preheater C Oxygen Heater C Gasifier D HPC trim cooler C Econo miser F Soot Quench E Quench Nozzle Filter F A/B Scrubber Slurry Pump J A/B Soot Separator F Residue from BL To second string, B Oxygen from BL HP BFW from BL To flash vessel from filter Quench water cooler C from filter Simplified Process Flow Diagram of SGP Syngas Cooling Primary heat recovery takes place in a Waste Heat Exchanger with superheater section generating high pressure saturated as well as superheated steam. The saturated steam generated is used inside the plant for oxygen preheating and, if needed, for feed preheating. The remainder is superheated; part is used as process steam for gasification while the surplus is exported. Secondary heat recovery takes place in a boiler feed water economizer. Soot Removal In the partial oxidation of hydrocarbons the product gas contains a certain amount of free unconverted carbon (soot). The soot particles and the ash are removed in two stages from the gas by means of a quench pipe arranged with a soot separator followed by a packed scrubbing tower, the soot scrubber. Most of the soot is removed in the quench pipe by a direct water spray.

7 In the scrubber the gas is washed by water in counter current flow. After leaving the scrubber at a temperature of about 120 C the gas is suitable for further treating in the HCN/COS catalytic hydrolysis unit / acid gas removal unit. The soot formed in the partial oxidation reaction is removed from the system as a soot slurry via the bottom outlet of the soot separators and is routed to a common soot slurry system for further processing. Soot slurry processing The soot slurry ex scrubbers is let down to low pressure in a common slurry flash vessel to flash off dissolved syngas components like H2, CO and acid gas (NH3, H2S). This gas is routed to the refinery sulphur recovery unit (SRU). The flashed soot slurry is routed to the filter feed vessel. Carbon slurry filtration takes place in two membrane filter presses operating in batch mode. The produced filter cake will have a soot ash content between 15 and 25 %wt and is fed to the Multiple Hearth Furnace. The Ash has a commercial value as feedstock for the metals producing industry, in particular as vanadium source. The product ash is collected and packed in big bags for shipment to a metal reclaimer. The other product from MHF is the flue gas containing CO and other trace impurities which originate from the cake. Dust removal is applied to clean the flue gas before it is sent to a refinery furnace. Sour water stripping The sour water stripper receives filtrate water from filter presses and flash gas from soot slurry flash vessel as well as process condensate from the acid gas treating unit. The sour gas is sent to the existing sulphur recovery facilities (outside battery limits). The stripped water is sent to battery limits for further treatment in a biotreater

8 sour gas to SRU Flash Vessel F Slurry Cooler C Reflux Cooler C Filter feed Vessel F Filter Press F /202 Filtrate Vessel F Reflux Pump J A/B LPS Slurry Pump J A/B LPS Waste water Stripper E Filter Feed Pump J /201 Filtrate Pump J A/B Slurry Tank Pump J A/B Slurry tank G Stripper Effluent Pump J A/B Stripper Effluent Cooler C Cake Trough F /203 From soot separators Effluent water to Bio-treater Cake to Conveyor To SGP scrubbers Simplified Process Flow Diagram of Slurry Processing. COS hydrolysis and Acid Gas Removal The raw syngas requires further treatment to a specified purity in order to make it suitable for H2 production and for electric power generation in a gas turbine. COS/HCN Hydrolysis and Syngas Cooling Unit convert most of the COS and HCN in the syngas feed to H2S and NH3 via catalytic hydrolysis reactions, and cool the syngas to suitable temperatures for the Acid Gas Removal Unit. The Acid Gas Removal Unit removes most of the sulfur containing compounds from the syngas to meet environmental emission regulations (i.e. maximum 10 ppmv of H2S in the treated syngas). The selected solvent is not removing COS, therefore a COS hydrolysis takes place upfront to convert COS into H2S. Sulfur containing acid gas removed from the syngas is sent to the existing Sulfur Recovery facilities in the refinery. The HCN is also converted to NH3, which is removed along with the condensate produced from the cooled syngas. The hydrolysis process is licensed by Shell while the amine process utilizes Dow Gas-Spec solvent.

9 Metal Carbonyls Removal The purpose of the Metal Carbonyl Removal Unit is to remove the iron and nickel carbonyls in the syngas downstream the Acid Gas Removal Unit. They are removed by physical adsorption with activated carbon. Although they are present in trace quantities, they could cause operational problem to the downstream gas turbine. Prior to being sent to the downstream membrane unit to recover hydrogen, the treated syngas is filtered through a sintered metal filter. The spent carbon contains adsorbed metal carbonyls. When the carbon is saturated (after an estimated time of 6-12 months, depending on carbonyls content), it is burned in the MHF of SARU, and metal carbonyl thermally decomposed and converted to metal ash (oxides). Hydrogen Recovery The unit has been designed to produce Nm 3 /h of hydrogen with a purity of minimum 99.9%v. This is achieved by means of UOP licenced membrane system followed by a Pressure Swing Adsorbtion (PSA). The hydrogen selectively permeates into the bore of the membrane fibres pushed by the differential pressure across them. The hydrogen depleted non-permeate gas is available essentially at the feed pressure, and sent to the gas turbine. Syngas Quality The treated syngas is made available to the Power plant at about 90 C and 39.5 barg, and with a molar ratio H2/CO between about 0.4 and 1 depending on the hydrogen extraction. The low heating value of the syngas (dry) ranges between 2800 and 3700 kcal/kg, and in the lower case it is adjusted in the power plant by a small (about 10%) addition of natural gas. REFINERY IMPACT The new Gasification plant will be completely integrated into the refinery for all the utilities. Some of the systems are revamped to cope with the new requirements. Visbroken Vacuum Tar is taken both directly from the Visbreaker Unit and from dedicated storage Tank. The line from storage is kept always in service to cope with the case of Visbreaker trip. Sour gas coming from wastewater Stripper and acid gas from Amine Washing Unit will be treated in the refinery Sulphur Recovery Units that are going to be revamped to increase their capacity. Hydrogen recovered from syngas is added to the same quality hydrogen from a SteamReforming Unit to feed the high purity refinery network, used mainly for Hydrocracker and Total Isomerization Units. Tail gas from the new PSA will be used as a fuel in an existing refinery furnace. All the HP steam produced will be used in the Gasification complex itself, or outside the refinery.

10 A new system to recover the steam condensate from Gasification complex and transform it into boiler feed water is integrated into the new complex. The stripped water coming from Waste Water Stripper and all the rain and drain water recovered from new complex will be treated in the Biological Waste Treatment Plant of refinery. Because of the increased consumption of instrument air, and the necessity of start up air to heat the gasifier with natural gas, the air refinery system is going to be revamped, increasing the capacity and the reliability. In the Gasification complex there is a wide use of nitrogen both in normal operation (blanketing, purging, etc.) and during start up/shut down, so the distribution has been deeply studied, mainly because for some use a very high quality nitrogen is required (especially for purging of oxygen connected lines). Moreover, because high-pressure nitrogen is necessary as a backup of reactor cooling medium, and it is not available from refinery, a dedicated storage was studied to fulfill the requirements of pressure and quality. Despite the fact that cooling water consumption is not so big, some refinery cooling towers are going to be revamped to assure cooling for old and new units. Fuel gas from refinery network is used mainly in the MHF furnace. Additionally, natural gas is used for blanketing and, during start up, as a fuel for reactor preheating. All the safety discharge from the new complex use the refinery blow down and acid blow down systems that have been checked and modified accordingly. The sealing/flushing oil system can be fed by LCO or desulphurised gasoil from refinery network. STATUS OF THE PROJECT All the CCU groups of the EniPower power station have been started-up and tested with natural gas between July 2003 and July They are presently producing at 100% load. The construction activity progress of the gasification plant is about 35% (end of August 2004) with all major equipment already in place. The syngas production for the third GT is foreseen during the 2 nd half of From then on, this will be the fourth Italian IGCC from refinery residues, for a total installed capacity of about 1600 MWe net power output. REFERENCES 1. G.Collodi, D.Brkic The Experience of Snamprogetti s Four Gasification Projects for over 3000 MWth Gasification Technologies 2003 San Francisco USA. 2. J.D.deGraaf, A.Magri The Shell Gasification Process at the Agip Refinery in Sannazzaro Gasification-The Clean Choice for Carbon Management-2002 Noordwijk The Netherlands.