2. European CO2 Test Centre Mongstad - Testing, Verification and Demonstration of Post- Combustion Technologies (2009)
Gelein de Koeijer*b, Yngvil Oftebro Engeb, Cyril Thebault c, Svein Bergb, Julia Lindlanda, Sverre Johannesen Overåb
aGassnova SF, N -3920 Porsgrunn, Norway bStatoilHydro ASA, N-4035, Stavanger, Norway cVattenfall AB, SE-162 87 Stockholm, Sweden
The European CO 2 Test Centre Mongstad project will construct two post-combustion CO2 capture test plants (amine and chilled ammonia) with total annual CO2 capacity of 100,000 tones. The ambitions are:
- Develop technologies for CO2 capture capable of wide national and international deployment
- Reduce cost and technical, envi ronmental and financial risks related to large scale CO2 capture
- Test, verify and demonstrate CO2 capture technology owned and marketed by vendors
- Encourage the development of a market for such technology
Both plants will be able to capture CO2 from two d ifferent flue gases with 3.5 and 12.9 mol% CO2.
On 12 th October 2006 Statoil (now StatoilHydro) and the Norwegian State agreed on implementation of CO2 Capture and Storage (CCS) at the Mongstad refinery . The Mongstad refinery is located north of the city Bergen in Norway. T he refinery is operated by StatoilHydro. In 2010 major improvements of the refinery will be ready including connections to several of its neighboring industrial sites and offshore platforms. This improvement includes the construction of a Combined Heat and P ower plant (CHP) which will add ~1.3 million tonnes CO2 per year to the emissions to the already existing emissions from the refinery, of which t he Residue Catalytic Cracker (RCC) is the largest contributor with ~0.8 million to nes CO2 per year. The agreement requires a two-stage implementation of CCS. The first stage is the European CO2 Test Centre Mongstad (TCM) with a design capacity of 100 000 tonnes of CO2 /year. The second stage is full scale implementation. The aim of this paper is to describe the tech nical choices and aims of the first stage – TCM.
The purpose of the test centre is to identify, test, develop and qualify CO2 capture technologies, and to reduce cost and financial, technical and environmental risk connected to the construction and operati on of a full scale CO2 capture plant. The ambitions of the TCM project are:
- Develop technologies for CO2 capture capable of wide national and international deployment
- Reduce cost and technical, environmental and financial risks related to large scale CO2 capture
- Test, verify and demonstrate CO2 capture te chnology owned and marketed by vendors
- Encourage the development of a market for such technology
The TCM partners are Gassnova SF (representing the Norwegian State), DONG Energy, Shell, StatoilHydro, and Vattenfall. The partners are operators from both oil&gas and power industry, and participate actively in the developmentof CO2 Capture and Storage.
Many technologies for CO2 capture are documented , and groups of these technologies have previously been assessed on various bases , see e.g . Steeneveldt et al  and CO2 Capture Project (CCP) [ 5]. At the start of the TCM project these technologies needed to be assessed with TCM specific demands enabling a technology choice. T he following criteri a were used together with the knowledge from the partners:
- Extent of modification and disturbances to the CHP and refinery. The operation of TCM (and the later full scale capture plant ) should not require any modifications to the CHP plant and refinery, nor disturb their operations
- Usefulness and improvement potential for the large-scale Mongstad CO2 capture plant
- General improvement potential relative to MEA based post -combustion (as documented by e.g. IEA [ 4] and CCP [ 5])
- Availability of established and emerging suppliers for the TCM project
- Technology demonstration and qualification aims of TCM in relat ion to its maturity. TCM should preferably demonstrate and qualify new and most probably immature technology.
- CO2 capture plant at Mongstad will have no harmful emissions in accordance to the zero harmful emission target of the Norwegian authorities and the Mongstad emission permit
- The possibility to capture CO2 fromthe high CO2 content flue gas from the RCC addition to CHP
The result was to recommend improved amine and c hilled ammonia technology. Amine technology is w ell known, simple and flexible, but still has improvement potential on steam demand, cost, emissions, discharges, solvent formulations, materials/ corrosion, and scale-up. An important reference was the Esbjerg pilot unit , which is the largest amine based post -combustion pilot unit in the world with a 1 to n CO2 per capacity and 1 m diameter absorber. The chilled ammonia technology uses the general absorption/desorption based on a carbonate/bicarbonat e cycle :
CO2(g) + CO32-(aq/s) + H2O (l) Û 2HCO3– (aq/s)
The reaction needs a cation for which the supplier Alstom has chosen ammonium. Alstom is developing this technology and calls it the ‘Chilled Ammonia Process’ (CAP) . Its possible advantages are reduced energy demand, fewer CO2 compressor stages, well known low cost chemicals, and reduced amount of waste . However this technology is unproven, has few available experimental data, need s extensive cooling, and requires handling of slurries and ammoni a. The chilled ammonia technology h as been tested less and therefore represents a higher risk.
Figure 1 shows the TCM overall concept and design capa cities based on the main functional requirements agreed in the early phase of the project. Each of t he two CO2 capture technologies (Amine / C hilled Ammo ni a) shall be able to capture CO2 from two different flue gas sources (CHP/RCC) and shall operate independent of each other . The CHP flue gas represents a gas fired power plant with 3.5 mol% and the RCC flue gas represents coal fired power plant with 12.9 mol% with particulates, SOx and NOx.
The design capacity will be 100 000 t ones CO2/yr if both technologies operate simultaneously with > 85% CO2 capture efficiency and 92% regularity. It will be possibl e to simulate the effects on CO2 capture of gas turbine Exhaust Gas Recycling (EGR ) by CO2 recycle from either plant back to the CHP flue gas . EGR is a technology for increasing the CO2 concentration to ~4-8 mol% and reduce the flue gas volume from gas fired turbines, see e.g. CCP . The technologies need to have high flue gas flexibility in each CO2 capture unit for handling both CHP and RCC flue gas. The plants will be designed such that scale-up to full-scale plant can be done based on the results from TCM. The amine technology has different gas flows through the absorber for RCC and CHP exhaust, while carbonate has the same. The reason was that the carbonate absorber performance was estimated to be less sensitive for CO2 concentration than amine. The maximum flue gas flows from the sources are 20-34% too large relative to what is estimated needed in the capture process. This will give flexibility and the ability to test the limits. Their sizes ar e chosen by a compromise between this flexibility and duct/tie-in cost.
Further, since the ambition for TCM is to create a centre for testing of post -combustion CO2 capture technologies and associated facilities, the TCM project includes access to flue gas es, utilities and captured CO2, as well as additional space reserved for testing of new (future) equipment and technologies in smaller or similar scale as the initial two technologies. CO2 compression and storage is not included at this stage but may be added in a later phase. The sizes of these plants will be significantly larger than the existing pilot plants. The absorber diameters will be expected to be around 2.5 -4.0m, while their heights may be 40-60m. Relative to the Esbjerg unit a scale-up factor of 5-10 will reached. It is expected that this size increase will be an important contribution in the scale -up of post-combustion CO2 capture.
The overall test objectives are:
- Demonstrate/quali fy and scale-up of high risk technologies (Chilled ammonia)
- Achieve incremental technology improvem ents in a generic and flexible a mine test unit
- Build and share knowledge and competence of CO2 capture technology among th e partners for full -scale realization
- Construct a test plant for CO2 capture tech nology applicable for both gas- and coal-fired power stations, balancing and taking into account the needs (application, geography) of the individual partners
- Measure and compare test results against reference cases to achieve the strategic ambitions
- Obtain good relations to vendors of CO2 capture technology and understand their offerings and capabilities
This chapter describes the main specific test objectives and functionality requirements for the amine plant.
HSE: Main HSE issues identified are the emissions and discharges of the solvents used , i.e. main amines, degradation products, activators, inhibitors, anti -foams, metals/metaloxides, SO x, and NOx. Technology and equipment that avoid these emissio ns will be included as far as reasonably possible for a test plant. Sampling, measurement and analysis methods and tools will be documented and tested for use before the start-up. U se and production of environmentally harmful chemicals need to be minimized during design.
Equipment: The pl ant will consist of one flexible absorber and two strippers for enabling CO2 capture from both RCC and CHP gas. One stripper will be designed for CHP exhaust and one for the RCC exhaust. Moreover, it will be used for testing of different solvents, requiring a high flexibility of operating parameters and filling/emptying capabilities. Verification of reduced h eat and electricity demand is of high priority. In order to have flexibility in future improvements, s pace will be allocated for:
- Inter-stage abso rber cooling
- Split flow from both strippers
- Additional reclaimer
- Additional reboilers in both strippers
- First stage of CO2 compression train
Nozzles and space have been allocated to allow testing of new or alternative equipment components within the initial plant.
The plant will allow for accurate measurement of temperatures, pressures, flows and composition. Mat erials testing test facilities for other steel qualities, concrete, coated mater ials and plastic will be installed . Multiple temperature and pressure measurement devices in absorber and stripper will be installed. Measurement of the amine and other chemicals in the entrained washing water will be possible. It shall be possible to measure the impact of SO2, NOx, particles, iron oxides and chlorides on the amine plant performance (e.g. amine degradation rate, filtration rate, corrosion rate, etc.)
Absorber : The absorber will have at least three sections of packing for CO2 removal complete with liquid distributors and liquid draw trays:
- The height of t he lowest bed is determined by the performance of a fast amine with RCC flue gas
- The second height is determined by the performance of a fast amine with CHP flue gas and of a slow amine with RCC flue gas. In case these heights significantly differ a fourth section can be included
- The third height is determined by the performance of a slow amine with CHP flue gas.
It will be possible to replace the packing/packing material with other packing type and other packing materials,
i.e. structured, random and plast ic. Below a demister, two water wash sections will be installed in the top of the absorber with minimum water consumption as design criterion. Space for a second demister will be allowed for.
Strippers : The two strippers will have at least two sections o f packings with nozzles and brackets to enable installation of liquid distributors and liquid draw trays for split flow operation. It will be possible to take out packing. The energy contained in the pressurized hot lean amine leaving the RCC -stripper will be utilized for reducing overall energy demand of the plant when capturing CO2 from the RCC gas. It will be possible to run the RCC-stripper without this technology.
Testing ranges: It will be possible to operate with CO2 concentrations in flue gas from 3.5 -12.9 mol% with minimum steam conditions at 100% load and 50% turndown for qualification for large-scale operation by utilizing the flexibility provided by multiple absorber sections and two strippers. Testing of RCC flue gas will be possible at varying of SO2 conc entrations. It is aimed to have a long term test at stable high SO2 concentrations. It will be possible to test different solvents.
An extensive test and development program will be prep ared utilizing the available functionalities before start-up.
The Chilled Ammonia Process (CAP) is currently being developed and commercialized by Alstom. The technology is ne w and the first pilot plant with continuou s operation of integrated absorber and regenerator was started 2008 at WE Energies coal fired power plant in Wisconsin , USA [8 ]. Figure 2 shows a 3D sketch of the CAP at TCM as envisaged by Alstom.
Chemistry and heat integration in the CAP are more complex compared to other commercially available CO2 capture technologies. There will be precipitation of ammonium bicarbonate, e.g. a mixture of solid particles of bicarbonate and the liquid solvent will form a slurry. Solids have thus to be handled during process operation. However, amm onium bicarbonate will dissolve during heating of the solvent in the lean/rich heat exchanger and in the regenerator, which operates at high pressure. Ammonia in water is volatile, and special measures h ave to be taken to avoid excessive emissions of ammonia to the environment. Emissions to air and to discharges to sea need to be l imited and the ammonia loss need to be kept at a minimum.
With respect to HSE, design data and testing ranges, the Chilled Am monia plant will be subject to many of the same design and functionality items as mentioned for the amine plant. Multiple temperature and pressure measurements in absorber and stripper will be provided to enable establishment of complete mass and energy balances. The design will also allow for liquid, gas and solid sampling and pH measurement at feed, exit and intermediate points in the absorber and stripper. The design shall allow for the simulation of the non optimal conditions (off set conditions).
The test program for Chilled Ammonia will focus on the following:
- Determination of the ammonia losses from test plant.
- Evaluation of the stripper operating pressure.
- Evaluation of process temperatures on thermal duty and CO2 capture efficiency
- Assessment of process kinetics for selected operating conditions
- Evaluation of performance of equipment
- Long duration tests of stable operation at industrial conditions.
- Evaluation of sensitivities to flue gas composition (sulphur, oxygen, particles, etc.) .
- Determinatio n of material and corrosion issues.
- Confirmation of operational stability and robustness.
- Evaluation of c hallenges around slurry operation and influence of solids content. In particular, turn down o peration, process control and operation, fouling and transportability, solid separation.
- Assessment of foaming issues for process.
- Determination of NH3/CO2 in rich and lean solvent all ove r the process and evaluate its impact on CO2 capture efficiency and steam consumption.
The activities on the chilled ammonia will progress in parallel with those of the amine plant . Determi nation o f design philosophy, in p articular with respect to scale -up is an important activity before start -up, and will be verified in the test program.
The investment decision and project approval is planned for end of 2008. It is aimed to have the start -up in 2011. The first test campaigns will start after about some months of comissioning. TCM will be operated for a period o f at least 5 years enabling an extensive validation and development o f the chosen technologi es. More information on future developments can be found on the TCM homepage on the website of Gassnova SF [ 9].
The European CO2 Test Centre Mongstad will be a n important d riving force in the qualification of large -scale capture technology and development of improved technology. It will establish an international test site for emerging technologies, equipment and solvents, as well as a location suitable for a wide range of research related to CO2 capture technology. It will contribute in the search for ways to reduce the CO2 emissions and to limit the environmental consequences of human activities. This project is unique in the world due to its ambitions, its flexibility of CO2 so urces and technologies, its cooperation of international companies from both oil and power industry and its agreement that initiated the project. We will be “catching our future”!
The authors thank the TCM steering committee and the partners Gassnova SF (representing Norwegian State), DONG Energy, Shell, StatoilHydro, and Vattenfall for granting permission to publish this paper. The authors would like to express their gratitude to all current and previous TCM team members.
- Website of Norwegian Government (Norwegian only) , http://www.regjeringen.no/upload/kilde/oed/prm/2006/0143/d dd/pdfv/293147- avtale_mellom_staten_og_statoil_mongstad _12_okt_06.pdf, October 2006
- Intergovernmental Panel on Climate Change (IPCC), Carbon Dioxide Capture and Storage, IPCC Special Reports, http://www.ipcc.ch/ipccreports/srccs.htm , ISBN-13 978-0 -521 -86643-9, Cambridge University Press, New York, USA , 2005
- R. Steeneveldt, B. Berger and T.A. Torp, Chemical Engineering Research and Design , 84-9 (2006) 739
- IEA Greenhouse Gas R&D Program, Improvement in Powe rG eneration with Post -Combustion Capture of CO2, Report Number PH4/33 , 2004
- D. C. Thomas (Ed.), Carbon Dioxide Capture for Storage in Deep geological Formations – Results from the CO2 Capture Project, ISBN 0 -08 -044570-5 (2 volume set), Elsevier, Oxford, UK , 2 005
- J.N. Knudsen, J. N. Jense n, P. Vilhelmsen and O. Biede, First year operation experience with a 1 t/h CO 2 absorption pilot plant at Esbjerg coal -fired power plant , Proceedings of European Congress of Chemical Engineering (ECCE-6 ), Copenhagen, 16 -20 September 2007.
- N. Solie, Chilled Ammonia Process for Post-Combustion CO2 Capture, Tekna kursdagene , NTNU, Trondheim, 3 -4 January 2008
- Press release by Reuters, http://www.reuters.com/articl e/pressRelease/idUS225 300+27 -Feb- 2008+BW20080227, Feb. 27, 2008
- Gassnova TCM homepage , http://www.gassnova.no/, 2008