THE SARLUX IGCC PROJECT AN OUTLINE OF THE CONSTRUCTION AND COMMISSIONING ACTIVITIES

Transcription

1 THE SARLUX IGCC PROJECT AN OUTLINE OF THE CONSTRUCTION AND COMMISSIONING ACTIVITIES 1999 Gasification Technologies Conference San Francisco, California October 17-20,1999 Guido Collodi - Snamprogetti - Italy Robert M. Jones - General Electric Co. - USA ABSTRACT In the early 90 s, owing to the new environmental specifications, the Italian refineries had to evaluate new routes to reduce the production of heavy products and/or to introduce technologies to allow them to stay competitive on the market. TAR gasification and energy production (IGCC) has been selected by SARLUX, a joint venture of SARAS and ENRON, in order to develop a new 551 MW IGCC Plant in the SARAS refinery located in Sarroch, Sardinia, Italy. Co-production of 40,000 Nm 3 /h of pure hydrogen and export of 180 t/h of medium and low pressure steam to the refinery are also achieved. The plant has been built by a Consortium formed between Snamprogetti,General Electric, and Nuovo Pignone under a lump-sum turn-key construction contract (LSTK), with an overall schedule of 38 months to achieve Minimum Performance Standards. The project, started on January 97, is in the final stage of erection with some utility units already commissioned. Start-up of the gasification section is expected in November 99. This paper will provide information, referred to the July-August 99 time peroid, on the status of the IGCC construction, and initial commissioning experience for the Utilities and Combined Cycle Unit. This data will be updated during the Conference. THE IGCC IN ITALY The modification of the fuel oil market consequent to the new environmental specifications will have strong effects on the oil industry, making available a large amount of petroleum residues which need to be converted. At present, high sulphur fuel oil can be prepared by blending oil residue with light distillate to bring the fuel oil characteristics in the range of commercial specification. In Europe (EU), such a specification will become more and more restrictive in a very short time period. According to the European Committee proposal, 1 wt% sulphur fuel only will be allowed from year 2000 for

2 industrial users, and 0.1 wt% sulphur gasoil for civil users. Strong limitations will be set to the heavy metals content. The aforesaid considerations have been the driving force for Italian refineries to search for new routes to reduce the production of heavy products and/or technologies to allow them to stay competitive on the market. The Italian refineries selection has been toward IGCC despite high investment costs, due to several aspects peculiar to the Italian situation: - strong dependence on crude as raw material - absence of nuclear power production - increasing of power demand and environmental constraint to realize new power station - national incentive (ordinance CIP 6) to sponsor power production from renewable feedstock - possibility to set up partnership with independent power producers - opportunity to finance the project by a non recourse approach The interest toward IGCC in a polygeneration mode is still high in Italy not only in refinery context, and more than one initiative is open despite the fact that the national incentive does not apply to new projects. During this 1999 year all three Italian IGCC projects are in the commissioning phase and expected to deliver electricity to the national grid, for a total installed capacity of more than 1300 MW. THE SARLUX IGCC At the 1997 Gasification Technologies Conference, the paper "The SARLUX IGCC Project", presented a few months after contract award, featured process descriptions and performances of the complex,. The main characteristics are reported here again for reference. Process Description. The Integrated Gasification Combined Cycle (IGCC) Project is designed to produce in an environmentally acceptable manner 551 MW of electric power, 100 tons/hour of MP steam, 85 tons/hour of LP steam, and 40,000 Nm 3 /hour of hydrogen. Electric power, steam and hydrogen will be exported respectively to ENEL and the SARAS refinery; sulphur and sludge metals cake, produced as by-products from the process plant, will be recovered and delivered to IGCC battery limits. The IGCC configuration is shown below in the overall Process Block Diagram. The oxygen necessary for partial oxidation in the gasification process, is supplied by an Air Separation Unit,

3 ASU, located outside the IGCC battery limits. Three different feedstocks can be fed at battery limits between the refinery and the IGCC: vacuum visbroken residue (TAR), vacuum residue, and asphalt. Sarlux IGCC Project Process Block Diagram Raggruppamento Temporaneo di Imprese Snamprogetti-General Electric- Turbotecnica AIR SOLIDS TO DISPOSAL AIR SEPARATION UNIT OXYGEN WASTE WATER PRETREATMENT WASTE WATER TO SULPHUR BIOTREATMENT RECOVERY SULPHUR NITROGEN FEEDSTOCK FEEDSTOCK PREPARATION SYNGAS GENERATION AND SOOT EXTRACTION GAS COOLING AND COS HYDROLYSIS TAIL GAS HYDROGEN SULPHIDE SULPHUR REMOVAL STEAM TO EXPORT STEAM BOILER FEED WATER ELECTRIC POWER STEAM TO EXPORT COMBINED CYCLE UNIT SYNGAS SATURATION HYDROGEN PRODUCTION HYDROGEN DEMIWATER SYNGAS TO POST FIRING DESALTED WATER DEMIWATER PRODUCTION The Complex uses the Texaco low pressure quench gasification process technology to produce syngas required by the Combined Cycle Units (CCU). The refinery residual oil, plus oxygen from ASU and HP steam from CCU, feed the Texaco Gasification (Unit 300) which converts heavy oil feedstock into syngas, at the conditions of about 1400 C and 38 barg. The syngas is immediately quenched with water. This syngas primarily consists of hydrogen, carbon monoxide and carbon dioxide, with small amounts of methane, hydrogen sulphide, carbonyl sulphide, and trace amounts of ammonia and hydrogen cyanide. The syngas is scrubbed to remove particulate using a circulating grey water system. The water used for scrubbing becomes rich in soot and is sent to the Soot Extraction (Unit 310), for soot removal by absorption with naphtha and recycle. In this way the carbon recovery efficiency is maximized. A portion of the grey water decanted off the naphtha is recycled to the syngas scrubber in the Gasification Unit, whereas the remaining portion is sent to the Waste Water Pretreatment (Unit 320). In this unit metals (vanadium and nickel), cyanides, sulphides, and ammonia contained in the grey water are removed for further water treatment in the downstream aerobic system. Metal and sulphide compounds are concentrated in a filter cake. The water-saturated syngas leaving the syngas scrubber, goes to the Heat Recovery (Unit 400) and then onto the COS Hydrolysis (Unit 400), where the carbonyl sulphide is hydrolyzed to hydrogen sulphide and carbon dioxide in a fixed bed catalytic reactor. The hydrolyzed syngas is cooled and fed to a Selexol absorber column in the Sulphur Removal (Unit 500). Selexol a

4 physical solvent process (licensed by UOP), is designed to absorb hydrogen sulphide and carbonyl compounds from syngas, while minimizing the co-absorption of carbon dioxide. On top of the regeneration column, acid gas mainly containing hydrogen sulphide and carbon dioxide, is sent to the Sulphur Recovery and Tail Gas Treatment (Units 510 and 520), where hydrogen sulphide is converted into elemental sulphur in an oxygen Claus plant licensed by Lurgi. Clean syngas, now containing only 30 ppm of sulphur, is sent to the Hydrogen Removal and Recovery (Units 600 and 610). These units, supplied by UOP, include a membrane section and a pressure swing absorption section (PSA), to produce pure hydrogen (more than 99% vol.) available at the refinery battery limits. Overall sulphur recovery is more than 99.5% of the sulphur content present in the feedstock. The syngas and waste gas coming from Hydrogen Recovery Unit, and the non-permeate gas coming from the Hydrogen Removal Unit, are fed to the Syngas Saturation (Unit 410) for syngas moisturization. The addition of water vapour to the syngas reduces NOx in the gas turbine exhaust and improves turbine output by increasing syngas mass flow. Moisturized syngas having a low heating value ranging from 1700 to 1850 kcal/kg, is sent to the gas turbine of the Combined Cycle Unit (Unit 700), at about 20 barg and 200 C where it is convertied into electric power. The Combined Cycle Unit mainly consists of three single-shaft STAG 109E combined cycle units by General Electric, each including one gas turbine, one generator, one steam turbine, and one Heat Recovery Steam Generator (HRSG). The heat of fluegas generated inside gas turbines is recovered to produce HP and MP steam. The HP steam is employed in the gasification unit and to produce electric power by the above mentioned steam turbines. PPU and CCU operation is supported by the necessary amount of utilities produced inside the IGCC (cooling water, instr. air, desal. water, etc.) or taken from the Refinery (demi water). Plant Performances The attached table shows the overall IGCC plant expected performance when using TAR with the guaranteed production of power, steam and hydrogen. Sarlux IGCC Project Overall Plant Performances OVERALL BALANCE: LHV IGCC Feed: Kg/hr Kcal/Kg MW Gasification Feed: A IGCC Outputs: Hydrogen to refinery: B MP Steam to refinery: C LP Steam to refinery: D Gas to Turbine (WET) : Gas to Post-firing (Dry): 0-0 POWER BALANCE: Consumption: MW Production: MW PPU: 22.6 Gas Turbine: 136.3

5 CCU: 10.2 Steam Turbine: 50.8 Utilities: 22.5 Gross Power: (ASU: 60) Total 55.3 Total of 3: F (115.3) E EFFICIENCY CALCULATION: 100*(B+C+D+F-E)/A Overall IGCC: 48.4% excluding ASU 44.6% including ASU The above table compares overall IGCC efficiency with and without the contribution of the Air Separation Unit. Environmental Impacts The SARLUX IGCC plant is designed to meet the most stringent environmental regulations. Air emissions The SARLUX IGCC has only one continuous emission to atmosphere, i.e. the CCU single stack meeting the following values (@ 15% O 2, dry basis): NOx 60 mg/nm 3 SOx 60 CO 25 Particulate 10 Liquid effluents The process water from the IGCC aerobic system is sent to the Refinery biological treatment and will have the following main characteristics: COD 250 mg/l BOD Solid products Heavy metals present with ash in the feedstock, mainly Nickel and Vanadium, and unreacted carbon are concentrated in a filter cake produced in the Waste Water Pre-Treatment Unit. This cake is a salable product and SARLUX is actively investigating on the market. With TAR as feedstock, Ni and V are concentrated in the filter cake at about 35% (dry basis). Noise The new IGCC complex is located in and surrounded by the existing SARAS Refinery. The equipment are selected to achieve a maximum sound level of 1 m.

6 CONSTRUCTION OVERVIEW The first construction activities started on August '97, i.e. seven months after the commencement date. The complexity of the plant, which consists of multiple trains for some process units (e.g. 3 gasification trains, 2 heat recovery, clean up and saturation trains, 3 CCU etc.), has the added consequence that commissioning activities in some utility units start when most of the PPU is still under construction. The overall estimated hours required by RTI for the scope of works amounts to : about 75% are for construction and the rest is equally splitted between home office (engineering, procurement, management) and precommissioning/commissioning activities. More than tons of material is installed (13000 for the CCU) and more that m 3 of concrete used (10000 for CCU) for buildings, foundations, stack. More than 25 major firms (civil, mechanical, electrical etc.) were involved in the erection of the complex and, after a period of assessment and field organization, the activity reached a progress of 7-9% per month in The overall construction and precommissioning progress status of the Project is at 87% (July '99). UTILITIES COMMISSIONING Most of the utility units part of the IGCC complex have been commissioned or are close to start-up. The commissioning team is completed, consisting of more than 50 Contractor's personnel and 40 Owner's personnel who are participating and have been trained over several months of actively at the site works. In particular commissioning has occurred on the following units: Desalination Units - They consist of six modules of 120 m 3 /h production each, based on thermocompression technology supplied by I.D.E. The first module was commissioned on June 99 and all six successfully tested. At present two modules are in operation for demi-water production.

7 Cooling Tower and CW Circuit - The sea cooling tower, a single cell of 65 m of diameter of wetdry (hybrid) type, is supplied by Balcke-Dürr and provides a cooling duty of 465 Gcal/h. Its erection took about 22 months and has been commissioned on August 99. The main cooling water circuits bring sea water to the CCU condensers (90" pipe) and fresh water in closed circuit to the other users through plate and frame exchangers. Diesel Oil System - Diesel oil is the start-up fuel for the CCU. The system mainly consists of one 380 m 3 tank receiving the oil from the refinery, and three pumping skids each one providing diesel oil to its dedicated CCU train during start-up, planned shut-down and syngas shortage. The unit has been commissioned and ready to provide fuel to CCU. Waste Water Treatment - It is the aerobic unit treating the water coming from the grey water pretreatment (metal recovery). It is provided by USF-Smogless and will reduce the formates, cyanides and other organic substances to the level permitted by the law after the subsequent refinery water treatment. The unit is mechanically completed. Electrical Substations There are seven electrical substations in the Complex. Five of them have been commissioned from the beginning of this year. COMBINED CYCLE UNITS COMMISSIONING The CCU consists of three identical trains plus some common parts (stack, GIS HV substation, firefighting etc.). The #1 train is ~90% mechanically completed as of July 99. Mechanical installation of the main single-shaft combined cycle power train equipment has been completed and precommissioning activities including L.O. flush, control loop checks and flushing of major piping systems for the first unit are complete or in their final stages. Installation and flush of the steam turbine lube oil and hydraulic oils systems is also in the finals stages. Initial fire of the first gas turbine unit on distillate oil is projected to occur in September Trains #2 and #3 follow the same programme being a few percent points behind the train #1, and the common parts are completed.. FUTURE ACTIVITIES As noted above, at the time of this presentation the CCU trains are in, or close to, the commissioning phase, as well as the process units. Following initial fire and synchronization of the gas turbine, commissioning activities for the Heat Recovery Steam Generators (HRSG s) will commence to support blowdown of the steam piping to the steam turbine, paving the way for start-up and commissioning of the steam cycle equipment. At the same time the firing of the first gas turbine and subsequent synchronization with ENEL will have taken place. As soon as the first CCU's HRSG produce high pressure steam in stable quality and quantity, the first gasification train will be ready to be started-up with TAR. This event is expected during November'99, followed by the second and third train after about one and a half month. The line-up of the downstream units (LTGC, AGRU, Saturation) would take approximately two or three weeks,

8 based on the experience gained from the other Italian IGCC project (ISAB Energy), where Snamprogetti is in Consortium with Foster Wheeler Italiana. The switch of the first Gas Turbine from distillate to syngas is therefore expected before the end of this year.