CHEMICAL ENGINEERING TRANSACTIONS VOL. 76, 2019 A publication of The Italian Association of Chemical Engineering Online at www.aidic.it/cet Guest Editors: Petar S. Varbanov, Timothy G. Walmsley, Jiří J. Klemeš, Panos Seferlis Copyright © 2019, AIDIC Servizi S.r.l. ISBN 978-88-95608-73-0; ISSN 2283-9216 CO2 Total Site Planning with Centralised Multiple Headers Jeffelee Sanghuanga, Sharifah Rafidah Wan Alwia,*, Wan Norlinda Roshana Mohd Nawib, Zainuddin Abdul Manana, Jiří Jaromír Klemešc aProcess System Engineering (PROSPECT), Research Institute for Sustainable Environment (RISE), School of Chemical and Energy Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia bFaculty of Chemical Engineering & Natural Resources, Universiti Malaysia Pahang (UMP), 26300 Kuantan, Pahang Malaysia cSustainable Process Integration Laboratory (SPIL), NETME Centre, FME, Brno University of Technology – VUT Brno 616 00, Brno, Czech Republic syarifah@utm.my CO2 Capture, Utilisation and Storage (CCUS) has been gearing towards the technology viable for CO2 removal from the atmosphere. The successful implementation of an integrated CCUS system would open up the opportunity to develop high CO2 gas field as well ensures the sustainability of gas production while minimising the impact on the environment. A methodology of CO2 integration management by maximising the recovery of CO2 for future utilisation and minimising CO2 to be sent for sequestration through centralised CO2 headers or known as CO2 Total Site has been developed. It consists of one high-purity header that is attached to CO2 storage or reservoir and low-purity headers that accept CO2 sources at different purity to satisfy CO2 demands. The multiple headers with consideration of different purity range of headers and a different number of headers are studied in this work. The application of the CO2 Total Site-Problem Table Analysis (CTS-PTA) has potentially resulted in an optimal CO2 target with the reduction of carbon storage of 32 % with a lower risk of CO2 leakage and low CO2 emission. 1. Introduction The carbon emission is increasing with the continuous increase in world energy consumption. In a combination of CO2 capture and storage and utilisation (CCUS), the CO2 emissions can be reduced by capturing CO2 and injecting it into geological storage or through utilisation. The CO2 capture and storage (CCS) technology involves the capturing of CO2 from the exhaust gases from large industrial facilities and appropriately storing it in geological storage sites such as depleted oil and/or gas reservoirs. However, integrated CO2 capture and utilisation have been reported as a promising route toward economically viable chains of values (Stuardi et al., 2019). Pinch Analysis based methodology has been widely used in planning CO2 capture and storage such as storage planning and CO2 sources and sinks matches (Diamante et al., 2014). This methodology has emerged as an important branch of Process Integration (PI) for problems involving the management of CO2 emissions (Tapia et al., 2018). An approach using CO2 Pinch Total Site methodology was developed to manage CO2 capture and CO2 demands from various plants into centralised header before send to storage or sequestration (Mohd Nawi et al., 2015). The algebraic method for targeting the optimum CO2 utilisation and storage based on the Pinch Analysis approach was introduced (Mohd Nawi et al., 2016). An extended methodology with consideration of different purity range of headers and a different number of headers is proposed in this paper to enhance the systematic planning and management of CO2 emission for a sustainable potential alternative which can directly be related to the industrial symbiosis. 2. Methodology A methodology development of the Total Site CO2 Integration (TSCI) targeting technique for optimal carbon target of CO2 utilisation and storage is described. Generally, the methodology comprises of four main steps which are setting the header, data extraction, constructing problem table algorithm and analysing the result. DOI: 10.3303/CET1976024 Paper Received: 05/04/2019; Revised: 27/04/2019; Accepted: 09/05/2019 Please cite this article as: Sanghuang J., Wan Alwi S.R., Nawi W.N.R.M., Manan Z.A., Klemes J.J., 2019, CO2 Total Site Planning with Centralised Multiple Headers, Chemical Engineering Transactions, 76, 139-144 DOI:10.3303/CET1976024 139 2.1 Step 1: Setting CCUS header A potential area is selected for the implementation of TSCI planning. The area has to consist of a number of CO2 sources and demands. The decision on the number of TSCI centralised headers is within the flue gas purity of CO2 sources and demands. The highest flue gas purity of CO2 from demand is about 99 %, so the acceptability of one of the headers must be within the range so that the demand can extract the required CO2 supply from the centralised header. The rest of the centralised headers are set at lower acceptable purity range to satisfy demands which have lower purity requirement. Since this is an end-of-pipe solution, the header with high purity range is designed for reservoir storage as the final destination. For the flue gas within the centralised headers with lower acceptable purity range has to be fully consumed by the last demand at the end of its pipeline. 2.2 Step 2: Data extraction The limiting data for the CO2 sources and CO2 demand in the selected potential area are identified and extracted based on their location along the headers from the beginning of the pipeline until the identified end. A flue gas consists of CO2 gas and other various gases such as nitrogen (N2), oxygen (O2), carbon monoxide (CO), nitrogen oxide (NOx), and sulphur oxide (SOx). The extracted data includes the flue gas flow (FT) and the gas CO2 purity (PCO2). The amount of CO2 (FCO2) and other gases flow rates (FOG) can be calculated using equations adapted from Mohd Nawi et al. (2016). 2.3 Step 3: Problem Table Algorithm construction An algorithmic method is developed for the planning and managing the CO2 sources and demands using centralised headers. The problem table algorithm, namely CO2 Total Site Problem Table Algorithm (CTS-PTA), is extended to target the maximum amount of CO2 that will be utilised with the minimum amount of sequestrated CO2 for multiple headers. CTS-PTA is based on the TS concept, provides the insight-based solution which can be used as a tool for CCUS planners and mechanisms to maximise the CO2 utilised and minimise the CO2 stored based on the location of sources and demands along the centralised header instead of their purities. By taking Header 1 (H1) as an example, the step-wise description of performing CTS-PTA is detailed in this section. Starting from the beginning of the centralised header, the sources and demands are matched by performing FT (Cum FT) and FCO2 (Cum FCO2) cascade, the accumulation of FT and FCO2 cascade using equations adapted from Mohd Nawi et al. (2016). Meanwhile, the header CO2 purity (PH1) after going through each source also can be calculated using equations adapted from Mohd Nawi et al. (2016). At demands’ locations, FT and FCO2 are accumulated from the top to the bottom row with the flow values of gases from header to specific location (FT,H1-D, FT,H1-H2, FT,H1-H3, FCO2,H1-D, FCO2,H1-H2, and FCO2,H1-H3) needs to be considered, as given in Eq(1) and Eq(2). There are two TSCI utilisation rules 1 or 2 need to satisfy for CO2 demands as adapted in Mohd Nawi et al. (2016). TSCI utilisation rule 1 is for the demand requires a higher CO2 purity (PCO2,D,i) (example 99%) than that accumulation of header CO2 purity (PHi,i-1) in the header (example 86%). A mixture of pure CO2 from the CO2 generator is required to satisfy the requirement of high purity demands. TSCI utilisation rule 2 is for the demand requires equal or lower CO2 purity (PCO2,D,i) than the accumulated CO2 purity in the header. Any FT from the header can directly be supplied to the demand by assuming that the demand can accept equal or higher purity sources. The minimum target of FT and FCO2 that is to be sent to the dedicated geological storage can refer to the last row of Column 7 (Cum FT) and Column 8 (Cum FCO2) respectively. The total fresh CO2 required from the centralised pure CO2 generator is the summation of Column 12 (FCO2,FC). For the subsequent headers, the same procedures are applied except the fresh CO2 supply from the centralised CO2 generator. The cleaner flue gas from the header with higher acceptable purity range has the potential to be utilised instead of using pure CO2 to satisfy higher CO2 purity demands for TSCI utilisation rule 1. The amount of FT taken from H2 (FT,H2-D) and H1 (FT,H1-D) to satisfy demand at H2 can be calculated using Eq(3) and Eq(4). Cum FT,H2,i = Cum FT,H2,i-1 + FT,H2-D,i + FT,H2-H3,i (1) Cum FCO2,H2,i = Cum FCO2,H2,i-1 + FCO2,H2-D,i + FCO2,H2-H3,i (2) FT,H2-D,i = (FT,D,i· PH1,i-1 - FT,D,i · PD,i) / (PH1,i-1 - PH2,i-1) (3) FT,H1-D,i = FT,D,i – FT,H2-D,i (4) For the situation where CO2 in the header with a lower purity range is a deficit to supply to a demand in the header. Instead of using fresh, pure CO2, the surplus of CO2 from another header with higher purity range can direct referring the amount of needed CO2 with neglecting the purity demand in the header since it tends to be ideally below than the other headers. For example, in header 3 (H3), the surplus of CO2 from H1 can supply to H3 to solve the deficit problem in H3 to satisfy the requirement of demand in H3. Eq(5) and Eq(6) described the gases transportation between other headers to H3, listed in Column 29 and Column 31 (Table 2c). FT,H1-H3,i = Cum FT,H3,i-1 + FT,D,i (5) FT,H2-H3,i = Cum FT,H3,i-1 + FT,D,i - FT,H1-H3,i (6) 140 As only H1 is designed to be sent to geological storage, the last row of Cum FT,H2 (Column 16) and Cum FT,H3 (Column 24) should not give any access where the surplus value of FT should be reduced by part of the sources, preferably the source with lower purity. When the last row of Cum FT gives a zero value, that is the Pinch Point of the TSCI system. 3. Results and discussion The CTS-PTA method was demonstrated with a combined case study data from Texas by Hasan et al. (2014) and another case study from an industrial site by Munir et al. (2012). The arrangement of the sources and demands across the headers is assumed as shown in Table 1. As the mentioned sign of flow rate, the positive values indicate CO2 input flow rate into the header whereas the negative values are output flow rate from the header. A CTS-PTA is performed to optimise the carbon target of CCUS with a few scenarios. The effect of different acceptable purity range and number of headers are analysed through the application of CTS-PTA on five different scenarios. Table 1: Arrangement of CO2 sources and demands across the header S/D Description PCO2 (%) FT(t/h) FCO2(t/h) FOG(t/h) S1 Cement 90 138.8 124.9 13.9 S2 Refineries/Chemical 70 608.5 425.9 182.5 S3 Power (coal based) 85 1,174.3 998.2 176.1 D1 Beverage plant 99 -50.0 -49.5 -0.5 S4 Power (NG based) 88 101.5 89.3 12.2 S5 Agricultural 65 69.9 45.4 24.4 D2 Enhance oil recovery 80 -208.3 -166.6 -41.7 S6 Petrochemical 80 615.4 492.3 123.1 S7 Gas processing 90 36.5 32.8 3.6 S8 Iron & Steel (corex) 95 27.9 26.5 1.4 D3 Methanol Production 50 -83.3 -41.7 -41.7 D4 Micro Algae Production 10 -220.0 -22.0 -198.0 3.1 Example scenario 1 In this scenario, TSCI is studied by using one header approach. All the CO2 sources and demands are integrated into one header. The minimum amount of remaining CO2 in Column 8 after cascading is 1,821.2 t/h which is needed to be sent to geological reservoirs for CO2 storage. There is 47.4 t/h amount of fresh CO2 from the CO2 generator is needed to blend with the header gas in order to reach the requirement of the demand. The CO2 purity in the stream header at the end is accumulated to 81 % which is still under the acceptable range as the assumption of only 80 % and above purity can enter geological storage. 3.2 Example scenario 2,3,4 In this scenario, TSCI is studied by using two header approaches. Each of the headers is set to a certain purity range. Each of the headers is set to a certain purity range. For Scenario 2, H1 is set to 80 - 99.99 % while H2 is set to 50 - 79.99 %. For Scenario 3, H1 is set to 90 - 99.99 % while H2 is set to 50 - 89.99 %. For Scenario 4, H1 is set to 85 - 99.99 % while H2 is set to 50 - 84.99 %. However, H2 for all scenarios (2,3,4) does not have access to storage. For this reason, any of an excess CO2 in the last row (Cum FTi,H2) needs to be deducted with the sources from H2. This is the Pinch Point of the system where the CO2 from the H2 which cannot be stored, might still be emitted to the environment. After performing the CTS-PTA, the minimum of amount of remaining of CO2 in Column 8 (H1) after cascading is 1,582.6 t/h, 179.8 t/h, and 917.2 t/h for Scenario 2, 3, and 4. 3.3 Example scenario 5 For further scenario, three headers were set with a purity range between 90 – 99.99 % for H1, 70 – 89.99 % for H2 and 50 – 69.99 % for H3. The results are shown in Table 2a, 2b and 2c. 141 Table 2a: CTS-PTA Scenario 5 for H1 1 2 3 4 5 6 7 8 9 10 11 12 i S/ D Hea der PCO2,S/D (%) FTH1,S/D (t/h) FCO2H1,S/D (t/h) FOGH1,S/D (t/h) Cum FT,H1 (t/h) Cum FCO2,H1 (t/h) PCO2,H1 FCO2,H1-D (t/h) FT,H1-D (t/h) FCO2,FC-D (t/h) 1 S1 H1 90.0 138.8 124.9 13.9 138.8 124.9 0.90 2 S2 H2 70.0 138.8 124.9 0.90 3 S3 H2 85.0 138.8 124.9 0.90 4 D1 H1 99.0 -50.0 -49.5 -0.5 -4.5 -5.0 45.0 133.8 120.4 0.90 5 S4 H2 88.0 133.8 120.4 0.90 6 S5 H3 65.0 133.8 120.4 0.90 7 D2 H2 80.0 133.8 120.4 0.90 8 S6 H2 80.0 133.8 120.4 0.90 9 S7 H1 90.0 36.5 32.9 3.7 170.3 153.3 0.90 10 S8 H1 95.0 27.9 26.5 1.4 198.2 179.8 0.91 11 D3 H3 50.0 184.8 167.6 0.91 12 D4 H3 10.0 0.0 0.0 0.00 Table 2b: CTS-PTA Scenario 5 for H2 1 2 3 13 14 15 16 17 18 19 20 i S/ D Header PCO2,S/D (%) FTH2,S/D (t/h) FCO2H2,S/D (t/h) FOGH2,S/D (t/h) Cum FT,H2 (t/h) Cum FCO2,H2 (t/h) PCO2,H2 FCO2,H2-D (t/h) FT,H2-D (t/h) 1 S1 H1 90.0 2 S2 H2 70.0 608.5 426.0 182.6 608.5 426.0 0.70 3 S3 H2 85.0 1,174.3 998.2 176.1 1,782.8 1,424.1 0.80 4 D1 H1 99.0 1,782.8 1,424.1 0.80 5 S4 H2 88.0 101.5 89.3 12.2 1,884.3 1,513.4 0.80 6 S5 H3 65.0 1,884.3 1,513.4 0.80 7 D2 H2 80.0 -208.3 -166.6 -41.7 -167.3 -208.3 1,676.0 1,346.1 0.80 8 S6 H2 80.0 615.4 492.3 123.1 2,291.4 1,838.4 0.80 9 S7 H1 90.0 2,291.4 1,838.4 0.80 10 S8 H1 95.0 2,291.4 1,838.4 0.80 11 D3 H3 50.0 2,291.4 1,838.4 0.80 12 D4 H3 10.0 2,256.2 1,810.2 0.80 142 Table 2c: CTS-PTA Scenario 5 for H3 1 3 21 22 23 24 25 26 27 28 29 30 31 32 i S/D PCO2,S/D (%) FTH3,S/D (t/h) FCO2H3,S/D (t/h) FOGH3,S/D (t/h) Cum FT,H3 (t/h) Cum FCO2,H3 (t/h) PCO2,H3 FCO2,H3- D (t/h) FT,H3-D (t/h) FT,H1- H3 (t/h) FCO2,H1- H3 (t/h) FT,H2-H3 (t/h) FCO2,H2- H3 (t/h) 1 S1 90.0 2 S2 70.0 3 S3 85.0 4 D1 99.0 5 S4 88.0 6 S5 65.0 69.9 45.4 24.5 69.9 45.4 0.65 7 D2 80.0 69.9 45.4 0.65 8 S6 80.0 69.9 45.4 0.65 9 S7 90.0 69.9 45.4 0.65 10 S8 95.0 69.9 45.4 0.65 11 D3 50.0 -83.3 -41.7 -41.7 -54.1 -83.3 -13.4 -12.2 0.0 0.0 12 D4 10.0 -220.0 -22.0 -198.0 -220.0 -184.8 -167.6 -35.2 -28.2 220.0 195.9 0.89 0.0 In Scenario 5, there is no excess amount of CO2 in H1 after cascading, a zero value at the last row of Cum FCO2 (Column 8 in Table 2a). This is due to the deficit in CO2 supply at H3. There is about 13.4 t/h of flue gas supplied to H3 at the location of D3 in order to cover the CO2 supply deficit to satisfy the demand. Besides, an amount of 184.8 t/h flue gas from H1 and an amount of 35.2 t/h flue gas from H2 are supplied into H3 to fulfil the requirement of demand 4. Refer to Table 2a, it can be seen there is excess flue gas in H2, there is about 2,256.2 t/h Cum FT,H2 at the last row of Column 16. The same procedure is carried out to deduct the amount of CO2 supply from the sources that supply into H2, which are S2, S3 and S8. All the amount of sources are eliminated from supplying to H2 except for the S3. The supply amount of flue gas from S3 is changed to 142 t/h from 1,174.3 t/h. There is no excess accumulation of CO2 at the end of H2. As mentioned previously, there is about 35.2 t/h of flue gas is needed to inject into H3 to satisfy the D4 which is one of the demands that extract flue gas from the header. However, there is also a large amount of captured CO2 might still emit into the environment which up to 1,795.8 t/h. The result obtained from all the scenarios is analysed and compared as shown in Table 3. Table 3 includes the base case study as the reference to the CCS without CCUS concept applied. The adjustment of purity range and number on the headers gave impact in the amount and purity of CO2 which is sent to geological storage. The amount of fresh CO2 and the carbon emission are also affected by the mentioned factors. With the consideration of TSCI, Scenario 3 and 5 are giving a negative result as there is a large potential CO2 emission as the captured carbon from the sources might still be emitted into the environment although they have high percentage reduction of carbon storage with a low amount of CO2 sent to geological storage. The amount of CO2 sent to geological storage in Scenario 2 and 4 are lower than in Scenario 1. However, there is an amount of captured CO2 from sources that cannot be stored and might still be emitted to the atmosphere as the Pinch Point of H2 is achieved. In Scenario 1, there is no Pinch Point should be considered and no captured CO2 released into the atmosphere and all the excess CO is sent to storage. The result of purity in sequestered CO2 for Scenario 1 is barely lower than 80 % which prove that one header approach would create uncertain storage condition and lead to difficulty in controlling the CO2 purity from various emission sources. In short, Scenario 1 might still be a questionable selection of CCUS planning depending on the condition of sources and demands. For Scenario 2 and 4, the lower flow rate required in fresh CO2 results in a reduction of overall 143 capital cost when compared to the base case without utilisation consideration. Scenario 2 gives a lower carbon emission, but higher in the amount of CO2 sent to geological storage. In contrast, Scenario 4 gives a better result in minimising the amount of CO2 sequestered but higher amount of CO2 emission. The carbon emissions storage life capacity is estimated for both Scenarios; there is a potential of extending storage life about 10.3 % and 34.6 % for Scenario 2 and 4. As the objective of this study is the optimal carbon target of CCUS, Scenario 2 has higher potential in the low carbon emission planning with the optimal CCUS condition compared to Scenario 4. Table 3: Summary of results between CCS (base case) and all the scenarios (1,2,3,4,5) Base Case: CCS (without utilisation header) Scenario 1 Scenario 2 Scenario 3 Scenario 4 Scenario 5 CO2 sequestered in storage (t/h) 1,764 (sources with ≥ 80 % purity) 1,821.2 1,582.5 179.8 1,153.1 0 Purity of CO2 sequestered 84 % 81 % 84 % 91 % 86 % - Fresh/outsource of CO2 needed (t/h) 279.8 47.4 46.5 45.0 46.5 45.0 4. Conclusions An extended methodology of TSCI has been developed by the numerical technique which is known as CTS- PTA to analyse the impact of purification range and number of headers. This newly developed method has contributed significantly to addressing the maximum utilisation of CO2 and minimum CO2 to be stored in geological storage. With all the scenarios given, the most optimal CO2 target can reduce a 32 % of CO2 storage with a lower risk of CO2 leakage and low potential of CO2 emitted into the environment. The technique is now available for CCUS planners to design their future headers according to CCUS mechanisms for significant CO2 reduction planning and management. Acknowledgements The authors would like to thank Universiti Teknologi Malaysia (UTM) under Vote Number Q.J130000.3509.05G96, Q.J130000.2509.19H34, Malaysia Ministry of Education under Fundamental Research Grant Scheme R.J130000.7809.4F918 and EC project for Sustainable Process Integration Laboratory-SPIL (Project No. CZ.02.1.01/0.0/0.0/15_003/0000456) funded by Czech Republic Operational Program Research and Development, Education, Priority 1: Strengthening capacity for quality research in collaboration agreement with Universiti Teknologi Malaysia (UTM), for providing research funds for this project. References Diamante, J. A. R., Tan, R. R., Foo, D. C. Y., Ng, D. K. S., Aviso, K. B., Bandyopadhyay, S., 2014. Unified Pinch Approach for Targeting of Carbon Capture and Storage (CCS) Systems with Multiple Time Periods and Regions. Journal of Cleaner Production, 71, 67-74. Hasan, M. M. F., Boukouvala, F., First, E. L., Floudas, C. A., 2014. 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