Recovery of CO 2 from units of Steam Methane Reforming at Sines Refinery Alexandre, André 1,2 , Alves, Sebastião 1, Campos, Cristina 2

1Department of Chemical Engineering, Instituto Superior Técnico, Lisbon, Portugal 2 Technical Refining Staff, Galp Energia, Lisbon, Portugal

Abstract This master degree thesis results from an internship done at Technical Refining Staff of

Galp Energia between March and September of 2011and had as main objective to select the CO 2 recovery process to be applied in hydrogen units located in Sines Refinery. Initially, was elaborated a general study on the market for in Europe and particularly in Iberia, being also analyzed the different processes of recovery it with matching industrial existence. Subsequently, were examined the existing two Hydrogen units, as they constitute the source of carbon dioxide.

The comparison of the recovery processes of CO 2, within this academic analysis, made possible to select the process FlashCO 2, as the one with highest probability of being used in

Sines. Then, based up on this process, were estimated the capacities of CO 2 units for extreme conditions, taking into account the utilization rates of hydrogen units concerned. Therefore, it was also completed an analysis of the possible technical and logistical implementation of a CO 2 unit at Sines Refinery.

Finally, an economic analysis allowed to conclude that the CO 2 unit, downstream of the hydrogen production plant HR, is feasible, being the minimum rate of operation below the average of the units in the European Union.

Keywords: CO 2 capture, H2 production, tail , flashCO 2 process, Sines Refinery

1. Introduction charcoal. Afterwards, Hoffmann discovered Carbon dioxide is normally present at that this gas is an acid gas and, Black gaseous state (atmospheric conditions) and showed is lethal effect on animal life. its presence has been known since the XVI Although, Lavoisier was the first to century [1]. Van Helmont was the first to demonstrate the existence of this gas, when recognize it when he prepared and isolated he proved its composition and named it the gas by various routes: fermentation, carbonic acid. action of acids on carbonates, burning of The commercial exploitation of carbon dioxide began with attempts to produce artificial mineral waters and its Nowadays, current uses for CO 2 are in development was carried on by Faraday and the beverage and alimentary industry Thilorier, who realized experiments on the (higher relevance in Europe), water of . Thilorier succeeded treatment, enhanced recovery (EOR, in experiments on the expansion, vapor particularly in the U.S.A.), agriculture, fire pressure, density, and enthalpy changes of extensor and inert agent, metals fabrication the liquid CO 2 during evaporation, and he industry and chemical application in was the 1 st to produce solid carbon dioxide. production of urea and methanol. The majority of the carbon dioxide generated in the world is a by product of 2. Market Analysis and hydrogen production. As so, The liquid CO 2 merchant market was there aren’t processes for production of CO 2 analysed in Portugal, Iberia and Europe. and the corresponding raw materials, but In Portugal, the liquid CO 2 production there are recovery processes and the sources is only made by in Estarreja. where the gas can be recovered [1]. Recently, in 2009, this company made an Other sources are the flue gases of upgrade of its capacity to 29 kton/year. power plants ( or based), There were two other units in Lavradio cement units and limekilns and in sugar connected to ammonia production, which fermentation units like bio-ethanol begun lay-off in 2007 and closed definitely factories. The last sources of CO2 can be in 2009. Currently, the Portuguese considered as the natural occurrence of the production is around 3,5 kton/year and the gas in caverns (due to precedent volcanic consumption about 25-35 kton/year. activity) or the presence in natural gas wells In Spain, the liquid CO 2 production is with very high concentrations. made by Praxair, Air Liquide, Linde, Air Products and Neoelectra (decreasing order

Table 1 - Comparison of CO 2 purity and of capacity), with total production and recovery cost by source Purity Recovery consumption close to 420 kton/year, being Source (% mol) Cost the installed capacity near 693 kton/year. 15 - 20 % ++ Therefore, in Iberia the installed Hydrogen unit 40 - 50 % +++ capacity is 722 kton/year, from the Ammonia unit ≈ 97 % + following sources: hydrogen (57%), ammonia (22%), bio-ethanol (11%) and Flue Gas from 10-20 % ++++ power plants (10%). The equivalent total Power plant consumption is, approximately, 450 Bioethanol unit > 80 % ++ kton/year. Natural source > 90 % +

Limekilns ≈ 40 % +++ 3. H2 production in Sines Refinery The hydrogen production in Sines Refinery is carried out by two units: HI of 2003, with a maximum capacity of 30 3 kNm H2/h, and HR from 2011, with 90 3 kNm H2/h [2].

Figure 1 - Geographic location of Refineries and CO 2 units in Iberia

In Europe, the merchant of liquid carbon dioxide is around 3600 kton/year, to a corresponding capacity of 5600 kton/year. Here, there is also a production of 1700 Figure 3 - HI unit kton/year that is stored, in CCS activities.

The sources of CO 2 in Europe have a Both of these units produce H 2 by different distribution than in Iberia, being Steam Methane Reforming process, with the the units of ammonia the main origin main difference in the presence of Pre- (52%), followed by the units of hydrogen Reforming in the case of HR unit [3]. (30%) and bio-ethanol (6%). The others The main advantage of the introduction sources include CO from caverns (Italia, 2 of Pre-Reforming in the most recent unit is Hungary), from ethylene oxide units supplied by the savings in the combustion (Germany, Belgium) and power plants of to fired heater of the SMR , as also (Spain, Germany). The European market its the lower production of vapour for export controlled mainly by three companies as and the higher feedstock flexibility [4]. shown in Figure 2.

4. CO 2 capture processes

18,3% The capture of CO 2 can be divided in 41,3% 22,5% three main categories: pre-combustion, 17,7% post-combustion and oxyfuelling [5]. In this

case, the capture of CO 2 from a hydrogen Air Liquide Linde Yara Outros unit is of the first category and is realized in the stream (inlet of PSA) or in the Figure 2 - Market shares by total capacity tail gas stream (outlet purge gas form PSA).

The major processes available can be 4.2. Physical absorption grouped as follows: The physical absorption can be utilized

• Absorption Processes when the CO 2 concentration is between 15 • Adsorption Processes and 40% of the stream (molar fraction) and • Membrane Separation the partial pressure of the gas in the stream • Cryogenic separation is high. The process bases are quite similar to

To remove the CO 2 from the streams the chemical absorption with the significant mentioned above, all of the process options divergence of using a physical agent are viable. However, the capture of CO 2 in instead, and that the physical absorption is Syngas should be done with absorption favoured at low temperatures. As so, the processes, preferably chemical type (amine main processes to remove CO 2 are: Selexol MDEA), and in tail gas must be utilized a (DMPEG), Purisol (NMP), Fluor Solvent Cryogenic separation. (propylene carbonate) and Rectisol process (methanol). The last two processes are the 4.1. Chemical absorption and MDEA most important and used because their There are a variety of amines that can solvents prove to have higher absorption be utilized in the treatment of acid gases. capacities relative to CO 2. Furthermore, the To remove of CO at low concentrations, 2 Rectisol has the lowest solvent circulation i.e. until 15% of the stream (molar rate and requires less energy [6]. fraction), the most widely used amines is the MEA, DEA and MDEA [5]. 4.3. Membrane separation The comparison between this amines Membrane systems have been reveals that MDEA is the most indicated particular utilized in the treatment of amine to remove CO 2, because it doesn’t natural gas with high concentration of acid react with this gas (so it doesn’t stimulate gases like CO 2. As main advantages, it has the corrosion problems), has higher uptake higher capacity to adapt to variations of of absorption of CO 2 and requires less CO 2 in the feed and the spatial requirements energy in regeneration step. As drawback of the installation are low [8]. it’s quite more expensive then the others and it can’t react directly with CO 2, so it is 4.4. Cryogenic separation necessary a primary dissolution of the gas Cryogenic separation has special in water (slow reaction). However, this last utilization in streams where the CO 2 disadvantage can be overwhelmed with the concentration is above 40% (%mol), being addiction of an activator – aMDEA[6],[7]. ideally to remove CO 2 from tail gas stream. The MDEA process can even achieve This separation path includes the CO removal rates higher than 95% [7]. 2 following operations to obtain CO 2: compression, cooling, expansion and increases the CO 2 removal rate and distillation (to higher purity requirements). produces a stream of off-gas (mainly

The main disadvantages of these processes composed by H 2, CO, CH 4 and residual are related to the conditions of operation: CO 2) that can be send to a PSA or high pressure and low (negative) membrane unit for H 2 recovery. temperatures. These conditions are supported by the necessity of working near 5. Process Selection the triple point of CO 2: -56ºC and 5,2 bar. The option of capturing the stream of The three main processes are: Syngas is technically more difficult to FlashCO 2 process of Union Engineering implement for units that did not consider CO 2-CPU of Air Liquide and CO 2LDSep of this option at the time of its construction, Fluor. since there is space or utilities constraints The advantages of FlashCO 2 over the that turn the plant unfeasible. For instance, other cryogenic process are the lower one of the biggest limitations is reflected in energy consumption presented, near 350 changing the configuration of the unit, kWh/ton of CO 2 compared with at least 420 given that the stream of Syngas (PSA inlet) kWh/ton of CO 2, the lower pressure would then have a quite different conditions (with total pressure bellow 30 composition (with higher H 2 purity) and bar) and the higher capacity of CO 2 lead to critical modifications in quantities removal - 90-95% compared to 60-85% of PSA adsorbents. (CO 2LDSep ) and 80% ( CO 2-CPU ) [6] [9]. As so, the capture must take place after Therefore, the FlashCO 2 process the PSA, since that’s the option that will represents a viable method of removing least disturb the normal operation of either CO 2 with lower operation costs and one of the hydrogen units in Sines Refinery. possible increase of H production. 2 The option for FlashCO 2 process was The referred process begin with made taking into consideration the source compression and liquefaction of the tail gas of capture and the best available techniques to produce a first stream rich in CO 2 (that in the industrial sector. Therefore, the main includes 50-70% of all the CO 2 present in advantages considered were the lower the tail gas) which is send to a distillation energy consumption and the higher capacity column to purification (inlet of 95% purity for CO 2 removal. and outlet with food and beverage grade The choice of the hydrogen unit where CO – purity above 99,5%). The gas stream 2 to implement a CO 2 recovery plant was (originated on the liquefaction section) has based mainly in a technical and logistical the remaining CO 2 and is send to a selective analysis, that revealed the presence of absorption unit where methanol is used as spatial restrictions (area available is physical agent. The methanol absorption insufficient) and lack of direct access to utilities (not enough power at the nearest As result, was discovered that changes substation) in the HI. in raw material of the HR won’t affect Therefore the recovery should take dramatically the composition of the tail gas, place downstream the HR unit, since this unchanging the operation of the CO 2 unit. unit isn’t affected by the same of Furthermore, it was recognized that the constraints of HI unit and since this unit burning of the off-gas (H 2 rich stream) can’t allow possible expansion of the CO 2 unit in be a recommendable action as the design of the future. the burners in the Top-Fired Steam Reforming doesn’t account for the higher

6. Plant implementation percentage of H 2 verified and, The standard operation parameters and consequently, this stream must have conditions can be observed in the Figure 4, another destiny: refinery stream or being the feed at low pressure (from 0,2 to H2 recover by membranes system + PSA, 2 bar) [10]. for instance [11]. Next, were investigated the possible In the other hand, it was calculated a consequences of the integration of this unit possible maximum CO 2 emission reduction in the regular functioning of HR unit and around 50 to 70 ktons per year (between 2,8 the Sines Refinery itself. and 4% of total CO 2 emissions by Sines Refinery).

Figure 4 – Generic block diagram of a CO 2 unit with FlashCO 2 process 7. Economical Analysis The total direct and indirect costs To complete this macro analysis about (utilities and solvents plus maintenance, a possible installation of a CO 2 capture unit raw material, patent, etc) were estimated in Sines Refinery, it was imperative to from 41,1 to 39,7 €/ton of CO 2 recovered make an estimation of the investment (increasing the plant capacity). In the other required, taking into consideration side, the fixed costs are between 7,1 and 6,4 investments in similar units. In addition, it € per ton of CO 2 recovered. would be important to analyze the costs of Relatively to distribution sector, it was

CO 2 capture both in terms of utilities and verified that, although the cost would be solvents (variable costs), as well as lower for ships and rail system, due to the maintenance, land use and workforce lower investment required and the (direct and fixed costs) and product characteristics of the customers (minor distribution (transport). individual consumption), the road The investment required to build this transportation becomes the preferable

CO 2 capture plant will be around 11,5 to option. Therefore, the transportation cost

14,5 M€ (for a range of capacity between calculated was around 20,8 €/ton of CO 2 50 and 70 kton/year) and was calculated by until a maximum radius distance of 200 km comparison with other similar investments (exponential increase from that point on). in units with the exact same process and To determine the margin for the CO 2 constraints [12]. price outside the HR unit (tail gas stream), it was necessary to calculate, historically,

the selling price of the product (CO 2 pure liquefied), knowing that it’s inside a volatile market where the transport and raw material cost have huge influence

The economic viability of CO 2 recovery unit was analysed with the calculation of the break-even point and other economic indicators, such as the TIR, the VLA and the RP.

Figure 5 - FlashCO 2 recovery unit in Chile Table 2 – Economic indicators of CO 2 units

Economic HR HR The CO 2 capture cost (only utilities and indicators (X kton) (Ykton) Break-even point solvents considered) was determined by the 74% 65% (% of unit capacity) average of the examples available, as being V. A. L. (M€) 11.749 23.264 around 22,9 € per ton of CO 2 recovered. T. I. R. (%) 13,1% 17,5% R. P. (years) 8 6 8. Conclusions [3]. Ke Liu et all, Hydrogen and Syngas The market analysis revealed the Production and Purification potential for the installation of a new CO 2 Technologies , AIChE and John Wiley recovery unit in Iberia. & Sons, Inc, 2010

The specifications of CO 2 recovery and [4]. Ratan, Sanjiv; Hydrogen technology – transportation made the introduction of a an overview , Technology unit in Sines Refinery possible, being Quarterly, Autumn 2003 abruptly promoted if any of the Ammoniac [5]. Metz, B. et all.; IPCC Special Report factories shutdown. on Carbon Dioxide Capture and On the other hand, the sensitivity Storage, Cambridge University Press, analysis revealed the importance of the cost Cambridge, 2005 of the product distribution and the raw [6]. Processing, Gas Processes material price, within total cost. Deviations Handbook, Gulf Professional of these parameters exposed that the Publishing, 2004 distance distribution of the product is vital [7]. Chaubey, Trapti et all; Clean Hydrogen to the profitability of the unit, overriding Production from SMR, CO2 Summit: the effect of increasing raw material price. Technology and Opportunity, 2010 In summary, with this work, it can be [8]. Fleming, Greg; Membrane Technology conclude that the integration of a carbon for Hydrogen Recover, Air Liquide - dioxide recovery unit should be performed MEDAL, 2006 downstream of the hydrogen production [9]. Reddy, Satish, Vyas, Sunil; Recovery unit HR (Refinery Plant III), if the market of Carbon Dioxide and Hydrogen from allows the unit to operate above the break- PSA Tail Gas, Energy Procedia, even point and preferably if there’s a Volume 1, Issue 1, Pages 149-154, guarantee that the sales of product are made February 2009 continuously on a contractually trade [10]. Union Engineering; CO2 Capture arrangement. from Fossil Fuel-Based Hydrogen Production; CryoGas International, 9. References May 2011

[1]. Topham, Susan; Ullmann’s [11]. Find, Rasmus; Method for recovery Encyclopedia of Industrial Chemistry , carbon dioxide from a Gas, Patente WO 5th Edition., Volume A5, Wiley-VCH 2006/037323 A1, 2006

Verlag GmbH & Co. KGaA, [12]. Clean Development Mechanism, Weinheim, 1986 Recovery and Utilization of CO2 from [2]. Galp Energia, Refinaria de Sines - Refinery Tail Gas, Project Design Relatório Operacional , December 2010 Document (CDM-PDD) NM0230, Chile, 2009