MOVING MOUNTAINS FOR GREEN ENERGY

Transcription

1 SAMCHEOK GREEN POWER PROJECT MOVING MOUNTAINS FOR GREEN ENERGY WITH FOSTER WHEELER AND KOSPO T he Samcheok Green Power Project is one of the world s most ambitious energy complexes. Currently being constructed in the Gang Won Do province in northeast of South Korea, the plant site will occupy 2.5 million square meters of reclaimed coastal land. The plant belongs to state owned utility, Korean Southern Power (KOSPO). The company s aim is to provide Korea s stable grid with a constant supply of 50 JANUARY/FEBRUARY 2013 POWER INSIDER electricity, and are doing so by staying on the cutting edge of energy production. Despite being coal fired, KOSPO s Samcheok project will be one of the greenest and most efficient power plants ever built. For its first phase, the plant will feature 4 of the world s first 550MW ultra-supercritical Foster Wheeler CFB boilers producing a total of 2000MW - firing imported coals and biomass. When fully complete, in addition to the CFB boilers, the Samcheok site will generate 1000MW from renewable sources, comprising of wind turbines mounted on the plant s seawall; solar panels on rooftops and slopes; wave power generation at the seawall, small hydropower at the plant drainage canal, and fuel cells from nearby Korea Gas Corporation. The plant infrastructure will include bilateral mooring for coal barges and an indoor coal yard

2 to keep coal dry and secure, reducing the spread of coal dust. The coal will come in on sealed barges and get vacuumed into an underground system of large pipes into the coal store, and an underground conveyer system will then take it up to the boiler islands, meaning that the coal will never be exposed to the outside. KOSPO have taken this environmentally conscious storage solution to a new level, roofing the coal store with solar panels. The solar panels, along with the other renewable installations, will power the auxiliary needs like conveying, stacking, and reclaiming, and any excess will get transferred to the grid. KOSPO also has plans to reuse the ash waste from the plant, aiming to remarket it to the building industry. Ash from the plant s electrostatic precipitators will be recycled and used as lightweight aggregate for construction and land reclamation. The ash will be used to rehabilitate land around old mines by neutralizing the acidic soil. Even the landscape of South Korea is being cleverly utilized in this exciting project. South Korea in general is a narrow, peninsular landmass that is mountainous with little flatland, and Samcheok in particular is full of fishing villages, national parks and environmentally protected zones. This leaves little space to build a groundbreaking power plant. KOSPO worked around these restrictions and made the most out of Samcheok s coast, by reconfiguring the landscape in careful consideration of the developments environmental impact. The mountain was already deemed industrial land because of its proximity to an LNG refinery and terminal. To make the most of the limited space, a tiered landscape was chosen for the site. This innovative method meant less workload, less soil and landmass to remove and therefore saved KOSPO a significant amount of money on the civil works. The key words surrounding the Samcheok complex are efficient, renewable and recycle. This makes Samcheok a model power plant, with incredible integration of thermal, renewable and environmentally friendly technologies. KOSPO sees Samcheok as a template for future coal fired power plants around the world. As such, KOSPO has strategically promoted and publicized this impressive facility, setting the stage for the next generation of plants that will use these cleaner technologies. KOSPO s president, Mr. Lee, has played an instrumental part by inviting press and industry insiders to the plant during the construction phase, and will continue to do so during operation, in order to demonstrate the ambitious undertaking for others seeking to do the same. The site will also contain a world leading CO2 research center employing technical experts from around the globe to continue development and reduce emissions. So what made a state owned utility like KOSPO want to develop such an ambitious and revolutionary project, utilizing such an array of different energy solutions? Primarily, a project of this scale and cost could not have been completed by anything other than a state managed and funded utility. The project, which is expected to cost in excess of $3 billion, is unlikely to produce the sort of returns that an IPP or bank would need to make it a worthwhile investment. Instead, it is a strategic project financed by the government to secure their energy security long term. South Korea and KOSPO need to think about energy security. KOSPO is a fast growing company with South Korea s energy demands increasing yearly. This is a challenge compounded by South Korea s dearth of natural resources; Korea is a major importer of fuels. Without the resources that nations such as China and India can exploit, South Korea is forever at the mercy of rising import costs and an unpredictable market. This rise in costs is simply driven by demand; most existing conventional thermal plants can only burn high-grade fuels, and the supply of good quality coal is declining, becoming more expensive. KOSPO could see that there were advantages in finding a way to exploit cheaper, low-grade fuels. Poor quality coal comes at a substantial discount, but that POWER INSIDER JANUARY/FEBRUARY

3 SAMCHEOK GREEN POWER PROJECT comes with the price of major challenges for efficient combustion. KOSPO undertook a three and a half year study in order to identify the right technology to have flexibility in fuel procurement and ability to burn low grades efficiently. It was Foster Wheeler that presented KOSPO with the idea of Circulating Fluidized-Bed (CFB) technology. CFB technology has several established benefits such as improved efficiency, reduced emissions, high fuel flexibility, high reliability and lower maintenance costs that combine to make this boiler technology a highly competitive option for large scale utility applications. CFB boilers burn fuels and waste materials like no other technology, with no flame or high temperatures. With CFB technology, combustion occurs at about 850C - far lower than the 1500C required for a pulverized coal (PC) boiler. An additional disadvantage of the PC boiler is that melting ash has a high propensity for slagging in the furnace and soot blowing is required. CFB technology takes these common operational difficulties out of the equation. Another significant feature of CFB technology is its ability to tightly control nitrogen oxides (NOx) and sulphur dioxide (SO2) emissions in the boiler, which can avoid the EPC capital costs associated with the installation of selective catalytic reduction (SCR) and FGD equipment. For a 600MW plant for example, CAPEX savings can exceed $100 million. In addition, the operating costs for ammonia and catalyst management for a SCR are also importantly avoided. Finally, and most important for KOSPO, CFB steam generators afford the maximum flexibility in fuel selection and can handle all coal types including low rank coals, petroleum coke, coal slurries and anthracite culm, as well as biomass and peat. This fuel procurement flexibility for CFB steam generators provides long-term fuel security and the potential to save millions of dollars by providing full access to discounted low quality fuels in the global fuel market. CFB technology originated from a number of small companies wishing to utilize the waste produced by their industries, such as the waste from paper and sugar mills, biomass and agriculture. Innovative companies, like Foster Wheeler, realized these wastes could be burned to provide energy for these facilities. Over the past 35 years, CFB technology has evolved from robust small-scale industrial boilers for burning such difficult fuels to large-scale utility power applications like Samcheok. Foster Wheeler has been a pioneer of that development, particularly in the scaling up of the technology. Foster Wheeler is responsible for making CFB larger, more efficient, and commercially viable for large power projects. Thus, for the first time in its history CFB technology can challenge PC technology in electricity generation applications, with more than 80 CFB units rated above 200 MW operating worldwide today. Foster Wheeler is also responsible for taking the technology supercritical. Supercritical boilers pressurize the steam to a far higher level, so that it can absorb more heat and translate into high efficiency. There is only one power plant operating a supercritical CFB boiler in the world, which demonstrates the cutting edge nature of Foster Wheeler s technology. That plant is the Lagisza power plant in Poland, which uses a 460MW supercritical CFB boiler and has been in successful commercial operation since It was to this plant that Foster Wheeler took KOSPO to demonstrate the potential and viability of supercritical CFB technology. KOSPO was very impressed and began technical discussions with Foster Wheeler about the feasibility of taking the technology to Samcheok, and scaling it up. Foster Wheeler confidently asserted that not only could they make the technology bigger, taking the boiler from 460MW to 550MW, but could also take the technology to ultra-supercritical steam conditions (over 600C steam temperatures), improving the CFB s efficiency even more. Whilst this posed some risks, KOSPO considered them manageable, and an agreement was reached to bring the world s first and largest ultra-supercritical CFB boilers to Samcheok. This makes Samcheok not only an important milestone for Foster Wheeler, but for the power industry globally. The Lagisza plant s design provided a solid base for scaling up the technology to the 550MW Samcheok units. The fundamental design was created in Foster Wheeler s Finnish engineering center, with the detailed design coming from Foster Wheeler s Shanghai base. Hyundai is the lead EPC for the project and will be responsible for the erection and installation of the CFB boilers. In the CFB combustion process, the fuel can be gravity fed into the fuel chutes only coarsely crushed. Because of the forgiving nature of the CFB process, the fuel doesn t need to undergo the complex processes required for pulverised coal combustion technology, such as fine grinding and drying. The fuel chutes feed the fuel to ports in the lower section of the CFB furnace, where it is fluidized by primary combustion air flowing through hundreds of specially designed nozzles in the floor of the furnace. Additional air, called secondary combustion air, is fed through ports located higher up in the furnace walls. Both the primary and secondary combustion air supports the burning, fluidization and vigorous 52 JANUARY/FEBRUARY 2013 POWER INSIDER

4 mixing of the solid fuel, limestone and ash particles, allowing the CFB to cleanly burn almost any combustible material. The particles eventually reach the top of the furnace and then pass through compact solid separators that capture and return most of them back to the furnace. The compact separators are an advanced design feature of Foster Wheeler s CFB technology, which is made up of steam-cooled panels that are fully integrated with the furnace. After being separated from the hot furnace gas, the captured particles flow from the bottom of the solid separators, pass through return passages and then into loop seals. The loop seals maintain the pressure balance between the furnace and the exit of the separators, allowing the solids to flow back into the furnace even though the solids are travelling into a higher-pressure zone. Foster Wheeler s differential loop seal design is proven in the industry for being highly reliable. The steam side of the CFB is based on the low mass flux BENSON once through technology from Siemens, because of the multitude of advantages it brings. Traditional supercritical boilers use spiral wound tubing to even out the uneven heat absorption in conventional PC boilers. However, this complicates the boiler and structure steel design since the walls of the boiler are now a spiral group of tubes. To prevent them from deformation, the furnace must be supported both horizontally and vertically. This intricate support system is more costly since it requires more steel and is complicated to build but it also makes repairing the boiler more difficult since the bracing must be moved out of the way and the boiler temporarily supported during the repair. Foster Wheeler s supercritical boilers utilize vertical tubes, allowing the boiler to be top supported, avoiding the complicated structure of the spiral wound boilers. The vertical tube design is easier to build and work on, and is more efficient since the distance the steam travels (which equates to pressure loss) is far shorter. Unlike PC units with uneven heat input in burner zones, the CFB combustion temperatures are uniform over the entire furnace resulting in uniform heat absorption for all boiler tubes, unlike conventional designs. For extra protection, small boiler tubes are used, reducing the weight of the water in the tube so buoyancy effects cause an increase in the water/steam flow for any tube receiving more heat. This low mass flux design is a passive self-cooling mechanism that FOSTER WHEELER S SUPERCRITICAL BOILERS UTILISE VERTICAL TUBES, ALLOWING THE BOILER TO BE TOP SUPPORTED, AVOIDING THE COMPLICATED STRUCTURE OF THE SPIRAL WOUND BOILERS. THE VERTICAL TUBE DESIGN IS EASIER TO BUILD AND WORK ON, AND IS MORE EFFICIENT SINCE THE DISTANCE THE STEAM TRAVELS (WHICH EQUATES TO PRESSURE LOSS) IS FAR SHORTER. doesn t exist in high mass flux spiral wound designs. Another advanced design feature of Foster Wheeler s CFBs is a high performance particle-tosteam heat exchanger called an IntrexTM, which is located between the loop seals and the furnace. The IntrexTM efficiently extracts high temperature heat from the hot particles in the CFB to produce high temperature superheat/reheat steam. The IntrexTM also solves the difficult problem of corrosion in the boiler s final superheaters. In a conventional PC boiler, the final super-heater coils are located at the top of the furnace exposed to all the corrosive elements in the boiler fuel gas. These coils are the most susceptible to corrosion since they operate at the highest metal temperature which increases as the temperature of the steam increases like in an ultra-supercritical boiler. To overcome this, PC boilers are forced to use expensive alloys for these coils and still require frequent maintenance and replacement depending on the fuel quality. To avoid this, Foster Wheeler CFB s locate these final superheating/reheater coils in their IntrexTM, submerging them in a hot bed of solids fluidized with clean air. The coils are protected from the corrosive boiler flue gases allowing the use of lower cost alloys and steels while also increasing the ability of the CFB to fire less costly lower quality fuels or achieve higher steam temperatures for the same fuel. Further, since the hot solids are in direct contact with the coils, the heat transfer is very efficient resulting in a very compact design saving cost and space. High performance tubing is being sourced from reputable players like Vallourec & Mannesmann and Sumitomo. These companies are playing a major role in the production of common and POWER INSIDER JANUARY/FEBRUARY

5 SAMCHEOK GREEN POWER PROJECT high-end seamless tubing. Hyundai is sourcing structural steel locally. As previously stated, the Foster Wheeler technology will allow KOSPO to use a wide range of fuels. In general, the fuel quality in Asia is declining, and the fuel supply chain can rapidly change. By using CFB technology and having wide fuel specifications KOSPO can avoid getting stuck with a limited or expensive supply chain. KOSPO will be able to buy different fuels over the life of the project, and Foster Wheeler has given KOSPO a wide range of coal possibilities and specifications. Initially, the project will utilize a lot of low grade Indonesian sub bituminous coal, and some petroleum coke as well. Potentially, the CFB boilers could be able to fire up to 20% biomass, totaling a possible 400 MW. The Korean Renewable Energy portfolio from the government provides great support for biomass, as it is an abundant domestic resource. Pellets, which make good feedstock, can also be imported. Construction schedule of the plant is on time. At the time of writing, site excavation is proceeding and the space for the boiler has been cleared, with the foundations of the boilers being poured. Foster Wheeler is well ahead in full detailed design, and will start supplying steel and boiler components this year. The main erection of the boiler is due to take place over The four units will be erected simultaneously, though stages of construction will be staggered between components in order to maximize the productivity of the workforce through space limitation and also minimize costs. The Samcheok Green Energy Project is a fantastically engineered combination of traditional electricity generation techniques with groundbreaking green technology. Despite being coal fired, this project demonstrates technology that can not only use low-grade coal, but has the potential to utilize biomass as well. This is made possible by the development of ultra-supercritical CFB boilers, which is surely the future of thermal technology. Most importantly, the Samcheok Green Power Project demonstrates the most logical approach to the global energy crisis. By using such a wide range of green and thermal technologies to produce it s 5000 MW capacity, KOSPO is not reliant on a specific fuel source, allowing them maximum flexibility whilst still be environmentally conscious. By breaking these boundaries, KOSPO and Foster Wheeler have offered the energy industry a glimpse into the future of power generation. This article was co-written by Bob Giglio Vice President of Strategic Business Planning and Development at Foster Wheeler Global Power Group and Rachael Gardner-Stephens, Assistant Editor for Power Insider Asia. 54 JANUARY/FEBRUARY 2013 POWER INSIDER