Both effects are detrimental to plant performance, but air gasification still has the advantage over oxygen systems. Environmentally, air blown schemes are not inherently "clean" than oxygen blown systems, due to the use of cold gas purge in oxygen blown GC C devices.
Large Scale Gasification Tests
Gasifier: SVZ-Grate Gasifier Operating Pressure: 24bar
- INTRODUCTION
- COMMERCIAL HISTORY
- REFINERY APPLICATIONS
- ECONOMICS
- REFINERY BENEFITS
- GASIFICATION PROCESS DESCRIPTION
- CONCLUSION
The hot synthesis gas and solids (unconverted carbon and ash) leaving the combustion chamber are quenched by contact with water in the lower quenching section of the gasifier. Most of the solids in the synthesis gas are washed out of the synthesis gas.
TEXACO GASIFICATION MILESTONES
LICENSED GASIFICATION CAPACITY
TEXACO IGCC PLANT
TEXACO QUENCH GASIFIER
TEXACO GASIFICATION
IGCC PROJECTS FOR THE 1990'S
TEXACO FEEDSTOCK DIVERSIFICATION
1956 HEAVY FUEL OIL 1957 WHOLE CRUDE
1961 NAPHTHA 1962 VACUUM RESID
1972 WASTE OILS
1983 ASPHALT 1983 COAL
INTRODUCTION
SCGP technology has recently been applied to the 250 MWe integrated coal gasification combined cycle at Demkolec, Buggenum. In the Netherlands, a 250 MWe combined cycle coal gasification plant based on Shell technology has been built by Demkolec, a development partnership of the Netherlands Electricity Generating Board (N.V. Sep).
THE SHELL GASIFICATION PROCESS (SGP)
The excess water from the SARU (ie the total net water produced in the gasification stage) is directed to a sour water stripper to remove traces of ammonia, NH3, hydrogen cyanide, HCN and hydrogen sulphide. The processing of soot and ash has been improved with the development of the soda ash removal unit.
THE SHELL COAL GASIFICATION PROCESS (SCGP)
The other outlet allows the hot raw gas and fly slag to exit the top of the gasifier. Of the energy in the coal fed to the gasifier, approximately 80-83% is converted to raw syngas.
RECENT MAJOR PROJECTS BASED ON SHELL GASIFIERS
Modification of the GT13E2 standard for medium Btu (MBtu) operation resulted in a unit where the main GT13E2/MBtu performance parameters are improved to exceed 185 MW and 37% (simple cycle) at ISO conditions with turbine inlet temperature. 1080 °C (TITIS0). Due to the high speed of gas injection, the flame stabilizes behind the burner (Figure 5).
Gasification Process
Vortex Breakdown
Gas Injection Holes
Combustion Air
Flame Front MBTU - Fuel
Eight of these plants are in commercial operation or early stage, providing some indication of the technology's potential. This amount of air is typically less than 20% of the gas turbine airflow, but must be exhausted without affecting the cooling air for the turbine components. Again, the fuel and nitrogen delivery system and its valves provided many of the lessons learned.
An important issue for the performance of an IGCC power plant and for the gas turbine compressor design is the degree of air-side integration of the compressor and the air separation unit (cf. Figure 4). In this concept, all the air for the air separation unit is extracted from the GT compressor. Table 1 provides an overview of the syngas composition and mass flow rates for both of the two V94.2 syngas applications - the Buggenum IGCC and the ISAB project.
The fuel system of the Buggenum gas turbine (see figure 6) therefore consists of a pipe work with extremely large diameters (DN600) including the use of flaps (flying valves) as control and stop valves.
SIEMENS
Puertollano IGCC 1.94.3 Block
Featuring Oxygen-Blown PRENFLO Coal Gasification
Natural Gas Operation
Syngas Operation
Syngas Operation
Gas turbine is recognized as the best motive power for modern power plants based on Simple Cycle as well as in Combined Cycle configuration according to the features of the specific project. Sodium and potassium, combined with vanadium, form eutectic salts whose melting point is lower than 566 °C; when combined with sulphur, they form sulphates which start their corrosive action at a temperature within the operating range of the gas turbine. Another key point is a constant control and monitoring of fuel quality to tune the treatment system to the actual fuel composition.
At the bottom of the vessel is water containing almost all the sodium plus potassium previously dispersed in the fuel; The system consists of a tank, a circulation pump and a metering pump that inject the additive into the high-pressure line downstream of the gas turbine fuel injection pump. When one of the two certification tanks is full, the treated oil is certified by chemical analysis.
For the successful implementation of the IGCC concept, the process of gasification of oil residues must be efficient and reliable.
This paper describes the positive experience that has been gained over the past fifteen years in the construction and operation of plants based on the gasification of residual oil using Texaco quench reactors. The construction of IGCC complexes based on this technology can benefit from the experience of the last fifteen years to provide a gas generation process of the reliability required for the energy industry.
DETAILS OF THE SELECTED TECHNOLOGY AND ITS PERFORMANCE
- RELIABILITY AND AVAILABILITY OF OXYGEN SUPPLY
- GASIFICATION CAPACITIES AND ROUTINE INSPECTION
- GASIFIER CONTROL, START-UP AND SHUT-DOWN
- BURNER PLATFORM LAYOUT
- CONSTRUCTION MATERIALS
The successful implementation of this important safety aspect requires the correct detailed design of the piping system. The duration and rate of the purge are also important questions to ensure a satisfactory shutdown procedure. The flow of cooling water to a cooling coil on the burner tip must be maintained during removal and installation of the burner in the carburetor.
In close proximity to the burner on top of the gasification reactor are the following critical piping systems. Stead/CVG 21 Jan 97 services, tools and instruments required to inspect the gasifier reactor burner and refractory during the shutdown period. The implementation of these procedures must be fully considered when developing the burner platform layout.
Correct construction materials and corrosion protection measures are important for the lifespan of the installation.
IGCC
The three gasification complexes in Table 4 generate synthesis gas for products in the chemical and fertilizer industries. An IGCC complex can also be designed to produce synthesis gas for chemical byproducts. Optimized processing schedules can be applied to each of these products, for which proprietary technology is available within the company.
Gasification in practice: the ISAB Energy 512 MW IGCC Complex
Financial Overview
All tasks associated with the successful completion of project financing development were completed in July 1996 (Financial Close). This is the result of intensive activities aimed, on the one hand, at completing the most important contracts with ENEL, the oxygen supplier (Air Liquide), the raw material supplier (Erg Petroli) and other smaller parties, and at the other side to demonstrate to the technical advisor (Stone & Webster) the robustness and proven experience of the technologies involved. The total project capital cost is Lit 1,900 billion. The project will be constructed under a lump sum turnkey construction contract (LSTK), incorporating the terms already agreed between ISAB Energy and the contractor under a Memorandum of Understanding signed in March 1995.
After a six-month open-book phase (June-December 1995) and the definition and signing of the LSTK contract, including the engineering, construction and takeover of the plant, detailed engineering was developed from February 1996. On July 17, 1996, the notice was given to proceed and the official start of construction activities. As of the current date (early December 1996), engineering development is 30% of planned, while material orders are 5%.
Completion of engineering is anticipated by October 1997, while commencement of commercial operation is scheduled for the end of.
Operating Experience with Air Blown 200 ton/day Entrained Flow Coal Gasifier
Particulars of dry feed air blown two stage entrained bed coal gasifier The air blown entrained bed gasification combined cycle is able to attain high net thermal
The maintenance of the generator can be carried out during the above schedule provided for the corresponding gas turbine. The maintenance of critical components can take place during the maintenance of the gas turbine. The evaluation of unplanned outages in the IGCC complex can be carried out through an availability assessment.
The following summarizes the typical availability values for the main units of the IGCC Complex. Saving equipment as described for the maintenance program contributes greatly to increasing the availability figure. Wet nitrogen is discharged to the atmosphere or recycled after condensation of the vapors (see above).
COMMISSIONING OF FIRST COMMERCIAL SOOT ASH REMOVAL UNIT (SARU) HGMC Tils, Shell International Oil Products B.V., The Netherlands. The preparation itself represents a considerable part of the total investment in the gasification plant. Most of the filtrate is returned to the SGP process as rinse water.
O.Box 9035, 6800 ET Arnhem, the Netherlands
A possible advantage of the present system is that it can be used without the risk of any tar formation. This use of the excess nitrogen from the air separation unit also applies to the OGCC case described above. Since the recuperator is quite simple in that the metal temperatures do not exceed 500 °C (930 °F) anywhere, the capital costs of the coal-fired TOPHAT cycle are expected to be much lower than for the gasification-based schemes and the operation is much simpler.
The fact that the TOPHAT coal burner pressure is only 4 - 8 bar psia) makes pressurizing the coal relatively easy and can make expensive lockout systems redundant. With modern gas turbines combined with two-stage TOPHAT air compressors, coal gasification power plants can be built with an efficiency of 52% based on LHV of the fuel. Due to the absence of a steam cycle, the capital cost of such power plants is lower than for conventional combined cycle stations based on coal gasification, while the operation of the power plant becomes simpler.
A Destec two-stage gasifier using a dry coal feed is required to obtain the 52% yield.
In the course of the detailed engineering execution of the ISAB Energy project, a Dynamic Simulation Study of the Integrated Combined Cycle Gasification Plant is in progress. It consists in building a dynamic simulation model that describes the sections of the plant which are dynamically important. This causes a change in the syndrome gas demand and thus the clean gas head pressure.
Consequently, the raw syngas pressure fluctuates in the Heat Recovery Section and a variation of the syngas production from the Gasifiers is mentioned. Once the planned and unplanned planting events are selected, the model will be exercised for each of the transitions. The final product will be a dynamic model of the ISAB Energy IGCC combined cycle plant with plant response predictions for the identified planned and unplanned (upset) events.
The simulator consists of a detailed dynamic modeling of the various systems of the plant, including the control.
