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It is assumed that pipeline depressurisation would be done preferentially by displacing the CO 2 into the wells with an airdriven pig, with subsequent depressurisation of the air (as described in Ref S6). However, facilities for manual depressurisation of the entire pipeline via the Kingsnorth CCS plant vent system are considered in this document. It is assumed that the CO2vented during depressurisation is routed to the onshore CCS plant vent system, from which it will be safely released to atmosphere
KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 1 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. Transient Analysis – Depressuring and Venting (Pipeline) Table of Contents 1 Executive Summary 6 1.1 Scope of Work 6 1.2 Depressurisation Times and Peak Flow Rates 6 1.2.1 Onshore Pipeline Only 6 1.2.2 Onshore and Offshore Pipelines 7 1.3 Depressurisation of Offshore Kingsnorth Platform Topsides Piping 7 1.4 Pressure Surges 7 1.5 Minimum Temperatures 8 1.5.1 Fluid and Wall Temperatures within Pipeline 8 1.5.2 Fluid Temperatures within Vent System 9 2 Scope of Work 10 2.1 Pipeline Operating Scenarios 10 2.2 Scope of Study 10 3 Basis of Design and Assumptions 11 3.1 Depressurisation Philosophy 11 3.2 Depressurisation Orifices 11 3.3 Vent Backpressure 11 3.4 Final Pressure 12 3.5 Olga Model 12 4 Depressurisation of Onshore Piping 14 4.1 Introduction 14 4.2 Depressurisation of Onshore Section - Vapour Phase Operation 14 4.3 Depressurisation of Onshore Section - Dense Phase Operation 17 5 Depressurisation of Offshore Kingsnorth Platform Topsides Piping 25 5.1 Introduction 25 5.2 Results 25 6 Depressurisation of Offshore Pipeline 26 6.1 Introduction 26 6.2 Depressurisation of Offshore Pipeline - Vapour Phase Operation 26 6.3 Depressurisation of Offshore Pipeline - Dense Phase Operation 30 7 Depressurisation of Offshore Pipeline by Pigging 39 8 Pressure Surges 39 8.1 Introduction 39 8.2 ESD Closure 39 8.3 “Steam type” Condensation 39 9 Supporting References 40 10 Appendix A Onshore Pipeline Depressurisation Results 41 10.1 Vapour Phase Operation 41 10.2 Dense Phase Operation 44 11 Appendix B Offshore Pipeline Depressurisation Results 47 11.1 Vapour Phase Operation 47 11.2 Dense Phase Operation 51 KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 2 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. Table of Tables Table 1-1 Pipeline Operating Scenarios 6 Table 1-2 Summary of Minimum Fluid Temperatures during Blowdown 8 Table 1-3 Summary of Minimum Wall Temperatures during Blowdown 8 Table 2-1 Pipeline Operating Scenarios 10 Table 2-2 Transient Analysis Cases 10 Table 4-1 Onshore Pipeline Depressurisation Times – Vapour Phase Operation 15 Table 4-2 Minimum Temperatures during Onshore Pipeline Depressurisation– Vapour Phase Operation 16 Table 4-3 Onshore Pipeline Depressurisation Times – Dense Phase Operation 17 Table 4-4 Minimum Temperatures during Onshore Pipeline Depressurisation– Dense Phase Operation 19 Table 6-1 Offshore Pipeline Depressurisation Times – Vapour Phase Operation 26 Table 6-2 Minimum Temperatures during Vapour Phase Depressurisation of Offshore Pipeline 28 Table 6-3 Offshore Pipeline Depressurisation Times – Dense Phase Operation 30 Table 6-4 Minimum Operating Temperatures during vapour phase depressurisation of offshore pipeline 33 Table of Figures Figure 3-1 Schematic of OLGA Model for Depressurisation 13 Figure 4-1 Pressure Upstream of Depressurisation Orifice – Vapour Phase Operation, Onshore Section 15 Figure 4-2 Temperature Downstream of Depressurisation Orifice – Vapour Phase Operation, Onshore Section 16 Figure 4-3 Figure 4-4 Mass Flow Rate during Onshore Pipeline Depressurisation, Dense Phase Operation 18 Figure 4-5 Liquid Content during Onshore Pipeline Depressurisation, Dense Phase Operation 18 Figure 4-6 Pressure Upstream of leak during Onshore Pipeline Depressurisation, Dense Phase Operation 19 Figure 4-7 Downstream Temperature during Onshore Pipeline Depressurisation, Dense Phase Operation 20 Figure 4-8 Temperature Trends in Onshore Pipeline during Onshore Blowdown, Dense Phase Operation 21 Figure 4-9 Pressure Trends in Onshore Pipeline during Onshore Blowdown, Dense Phase Operation 21 Figure 4-10 Minimum Fluid Temperature in Pipeline during Depressurisation of Onshore Section – Dense Phase Operation 22 Figure 4-11 P-T Pathway at landfall valve, During Depressurisation of Onshore Pipeline (4“ Orifice), Dense Phase Operation. 23 Figure 4-12 P-T pathway upstream of depressurisation orifice, During Depressurisation of Onshore Pipeline (4“ Orifice), Dense Phase Operation 24 Figure 6-1 Depressurisation times and peak mass flow – offshore pipeline, vapour phase 27 Figure 6-2 Mass Flowrate during Depressurisation of the Offshore Pipeline, Vapour Phase Operation 27 Figure 6-3 Upstream Pressure during Depressurisation of the Offshore Pipeline, 28 Figure 6-4 Comparison of T, P in Onshore and Offshore Piping during Blowdown, Vapour Phase Operation 29 KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 3 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. Figure 6-5 Depressurisation times and peak mass flow – offshore pipeline, dense phase 30 Figure 6-6 Mass Flow during Offshore Pipeline Depressurisation, Dense Phase Operation 31 Figure 6-7 Pressure Upstream of Blowdown Valve During Depressurisation of the Offshore Pipeline, Dense Phase Operation 31 Figure 6-8 Comparison of T, P in Onshore and Offshore Piping during Blowdown, Dense Phase Operation 33 Figure 6-9 Comparison of Holdup in Onshore and Offshore Piping during Blowdown, Dense Phase Operation 34 Figure 6-10 Minimum Fluid Temperature in the Pipe during Depressurisation of the Offshore Pipeline, Dense Phase Operation 35 Figure 6-11 Operating Conditions at 273km during Blowdown of Dense Phase Offshore Pipeline 36 Figure 6-12 Operating Conditions at Riser Base, Dense Phase Offshore Pipeline Blowdown through 6” Orifice 36 Figure 6-13 Downstream Temperature during Offshore Depressurisation, Dense Phase Operation 37 Figure 10-1 Downstream Temperature during Onshore Pipeline Depressurisation, Vapour Phase Operation 41 Figure 10-2 Upstream Pressure during Onshore Pipeline Depressurisation, Vapour Phase Operation 42 Figure 10-3 Mass Flowrate during Onshore Pipeline Depressurisation, Vapour Phase Operation 42 Figure 10-4 Pipeline Liquid Content during Onshore Pipeline Depressurisation, Vapour Phase Operation 43 Figure 10-5 Downstream Temperature during Onshore Pipeline Depressurisation, Dense Phase Operation 44 Figure 10-6 Upstream Pressure during Onshore Pipeline Depressurisation, Dense Phase Operation 44 Figure 10-7 Mass Flow Rate during Onshore Pipeline Depressurisation, Dense Phase Operation 45 Figure 10-8 Minimum Pipe Wall Temperature during Onshore Pipeline Depressurisation, Dense Phase Operation 45 Figure 10-9 Minimum Fluid Temperature during Onshore Pipeline Depressurisation, Dense Phase Operation 46 Figure 10-10 Liquid Content during Onshore Pipeline Depressurisation, Dense Phase Operation 46 Figure 11-1 Downstream Temperature during Offshore Pipeline Depressurisation, . 47 Figure 11-2 Upstream Pressure during Offshore Pipeline Depressurisation, 48 Figure 11-3 Mass Flowrate during Offshore Pipeline Depressurisation, 48 Figure 11-4 Minimum Wall Temperature during Offshore Pipeline Depressurisation, 49 Figure 11-5 Liquid Content during Offshore Pipeline Depressurisation, 50 Figure 11-6 Downstream Temperature during Offshore Pipeline Depressurisation, . 51 Figure 11-7 Upstream Pressure during Offshore Pipeline Depressurisation, 51 Figure 11-8 Mass Flowrate during Offshore Pipeline Depressurisation, 52 Figure 11-9 Minimum Wall Temperature during Offshore Pipeline Depressurisation, 52 Figure 11-10 Minimum Fluid Temperature during Offshore Pipeline Depressurisation, 53 Figure 11-11 Liquid Content during Offshore Pipeline Depressurisation, 53 KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 4 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 5 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. Table of Holds HOLD Description 1 Hewett topsides blowdown orifice sizes considered 2 Offshore Blowdown Pending Data from Plant Layout Review 3 Data from Pigging Simulations List of Abbreviations API RP American Petroleum Industry Recommended Practice CCS Carbon Capture and Storage CFD Computational Fluid Dynamics ESD Emergency Shutdown FEED Front End Engineering Design HP High Pressure LP Low Pressure OD Outside Diameter OLGA Transient flow assurance software P-T Pressure-Temperature SDV Shut Down Valve SSIV Subsea Isolation Valve KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 6 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. 1 Executive Summary 1.1 Scope of Work The pipeline depressurisation analysis takes into account two operating scenarios agreed previously: Table 1-1 Pipeline Operating Scenarios Property Base Case Full Flow Vapour Density LP Vapour HP Dense Power Plant Capacity (without Capture) 400 MW 1600 MW CO 2 Flowrate 6600 t/d 26,400 t/d This study examines the following depressurisation scenarios for the cases described in Table 1-1 above: Depressurisation of onshore pipeline Depressurisation of offshore Kingsnorth platform topsides pipework (HOLD 2) Depressurisation of offshore pipeline It is assumed that pipeline depressurisation would be done preferentially by displacing the CO 2 into the wells with an air-driven pig, with subsequent depressurisation of the air (as described in Ref S6). However, facilities for manual depressurisation of the entire pipeline via the Kingsnorth CCS plant vent system are considered in this document. It is assumed that the CO 2 vented during depressurisation is routed to the onshore CCS plant vent system, from which it will be safely released to atmosphere 1 . 1.2 Depressurisation Times and Peak Flow Rates 1.2.1 Onshore Pipeline Only The 29.5 barg (443 psia) reservoir pressure case was considered for vapour phase operation as this has the highest pipeline settle-out pressure of all the vapour phase cases (33.2 barg) and is thus the most conservative. The quantity of CO 2 held in the vapour filled onshore section before depressurisation is approximately 400 tonnes. The depressurisation times required for a range of orifice sizes from 1 to 6 inches ranged from 77 to 2 hours with peak mass flows from 6 to 200 kg/s respectively. The 157.5 barg (2,299 psia) reservoir pressure case was considered for dense phase operation as it is representative of typical dense phase pipeline operation. The quantity of CO 2 held in the liquid filled onshore section before depressurisation is approximately 4,200 tonnes. The depressurisation times required for a range of orifice sizes from 1 to 5 inches ranged from greater than 800 hours to 15 hours with peak mass flows from 50 to 1,085 kg/s respectively. The simulation for a 6 inch orifice did not run to the end of the depressurisation (i.e. OLGA model would not converge). 1 The location of the vent stack is not known; for the case of venting of the onshore pipeline (vapour phase) the stack could be located next to the CCS plant to give the highest initial temperature. KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 7 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. 1.2.2 Onshore and Offshore Pipelines Depressurisation of the offshore pipeline is currently assumed to be performed preferentially by pigging, thus displacing the CO 2 into the reservoir 2 . This is considered separately in Ref S6. If this is not possible, it is assumed that any blowdown would be via the onshore Kingsnorth CCS plant vent system. Depressurisation of the pipeline via the offshore Kingsnorth platform may also be considered; if so this document will be updated following dispersion analysis to confirm this methodology is acceptable with respect to relevant safety standards. Blowdown orifice sizes of 4”, 5” and 6” were considered, as the likely size of the Kingsnorth CCS vent plant was not known at this stage of the project (smaller sizes were presumed to result in excessive blowdown times). As for the onshore case the 29.5 barg (443 psia) reservoir pressure case was considered for vapour phase operation. The quantity of CO 2 held in the vapour filled onshore and offshore pipeline before depressurisation is approximately 14,800 tonnes. The depressurisation times required for orifice sizes from 4 to 8 inches ranged from 190 to 74 hours with peak mass flows from 91 to 307 kg/s respectively. Similarly the 157.5 barg (2,299 psia) reservoir pressure case was considered for dense phase operation. The quantity of CO 2 held in the liquid filled onshore and offshore pipeline before depressurisation is approximately 152,000 tonnes. The depressurisation times required for a range of orifice sizes from 4 to 8 inches ranged from 558 hours to 199 hours with peak mass flows from 61 to 2,007 kg/s respectively. The peak rates described above, particularly for dense phase depressurisation, are likely to require large vent systems. It may be desirable to limit the instantaneous depressurisation rate upon ESD initiation (e.g slow opening valve or parallel offline locked closed valve system) in order to reduce the required size of the Kingsnorth CCS plant vent system. 1.3 Depressurisation of Offshore Kingsnorth Platform Topsides Piping This analysis is on hold until platform layout drawings have been produced; these are required to allow an estimate of the topsides inventory to be made. 1.4 Pressure Surges No significant issues were found for the Kingsnorth system associated with pressure surges due to fluid hammer or vapour condensation. 2 This would be followed by depressurisation of the air in the pipeline via the Kignsnorth CCS plant vent system KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 8 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. 1.5 Minimum Temperatures 1.5.1 Fluid and Wall Temperatures within Pipeline The minimum temperatures during blowdown are summarised below. The design temperature will be driven by the requirements for dense phase blowdown rather than vapour phase blowdown. The blowdown of the onshore pipeline is the more onerous of the dense phase blowdown scenarios and will require a significantly lower design temperature than blowdown of the onshore and offshore pipelines together. The minimum fluid and wall temperatures during blowdown are summarised in Table 1-2 and Table 1-3 respectively. Table 1-2 Summary of Minimum Fluid Temperatures during Blowdown Orifice Size (in) Min Fluid Temperature within Pipeline °C Onshore pipeline only Onshore and offshore pipelines Vapour phase Dense phase Vapour phase Dense phase 1 -3 N/A N/A N/A 2 -4 -55 N/A N/A 3 -6 -78 N/A N/A 4 -7 -78 -2 -7 5 -9 -78 -2 -7 6 -10 -78 -2 -18 Table 1-3 Summary of Minimum Wall Temperatures during Blowdown Orifice Size (in) Min Fluid Temperature within Pipeline °C Onshore pipeline only Onshore and offshore pipelines Vapour phase Dense phase Vapour phase Dense phase 1 -3 N/A* N/A N/A 2 -3 -41 N/A N/A 3 -3 -63 N/A N/A 4 -4 -68 -3 -7 5 -4 -64 -3 -7 6 -5 -74 -3 -13 N/A corresponds to cases where the orifice size is unsuitable (i.e. too small). The following points should be noted: The minimum fluid temperature of -18°C for the dense phase onshore and offshore blowdown through a 6” orifice corresponds to a worst case value due to the formation of a pool of liquid CO 2 . The temperature in the pipeline during blowdown is more typically -12°C. The minimum fluid temperatures of -78°C in Table 1-2 and Table 1-3 occur when the onshore pipeline is blown down with the offshore pipeline isolated and left pressurised. This is the most onerous design condition for the onshore pipeline but does not apply for the offshore pipeline. Pressure and temperature trends for various positions in the pipeline are provided in section 4.3 for the onshore pipeline and section 6.3 for the offshore pipeline. Where the fluid and wall temperatures are <-50°C, this occurs with a simultaneous decrease in pressure i.e. the design pressure does not need to allow for -78°C at maximum allowable operating pressure. KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 9 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. Pressure and temperature trends for the riser are shown in section 6.3 (Figure 6-12). 1.5.2 Fluid Temperatures within Vent System During vapour phase operation, solids may potentially be formed immediately downstream of the depressurisation orifice as the minimum downstream temperature 3 is c. -56 °C. However it is likely that any solids formed will sublime quickly as the temperature required to maintain solid CO 2 at 1 atm is c. -79 °C. Note that that the velocity in the pipework downstream of the blowdown orifice will likely sweep any solids towards the onshore CCS plant vent system. For dense phase blowdown, there is the potential to form solid CO 2 downstream of the depressurisation orifice. During blowdown of the offshore pipeline, the fluid temperature downstream of the orifice is maintained at -79°C for a significant length of time and thus if there is limited heat ingress from atmosphere into the vent system there is the potential for solid CO 2 to accumulate downstream of the depressurisation orifice. It is recommended that this be examined in more detail during the design of the vent system. 3 This assumes that the pressure within the vent system could be as high as the triple point. KCP-GNS-FAS-DRP-0004 Revision: 02 Project Title: Kingsnorth Carbon Capture & Storage Project Page 10 of 54 Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party. 2 Scope of Work 2.1 Pipeline Operating Scenarios This transient analysis will take into account two operating scenarios described in the project basis of design, as shown in Table 2-1. Table 2-1 Pipeline Operating Scenarios Property Base Case Full Flow Vapour Density LP Vapour HP Dense Power Plant Capacity (without Capture) 400 MW 1,600 MW CO 2 Flowrate 6,600 t/d 26,400 t/d These scenarios have been described in the flow assurance basis of design and previous steady state simulations; details of base data are provided in Refs S1 and S2 respectively). The two cases considered further in this transient analysis are summarised in Table 2-2. Table 2-2 Transient Analysis Cases Reservoir pressure psia Reservoir pressure barg Scenario Pipeline operating phase 443 29.5 Base case Vapour 2,299 157.5 Full flow Dense 2.2 Scope of Study This study examines the following depressurisation scenarios for the cases described in Table 2-2 above: Depressurisation of onshore pipeline (i.e. up to the landfall isolation valve) Depressurisation of offshore Kingsnorth platform topsides pipework Depressurisation of offshore pipeline (i.e. inlet up to isolation valve at offshore Kingsnorth platform) Removal of CO 2 from the entire pipeline by pigging (and subsequently depressurising the air-filled pipeline through the Kingsnorth CCS plant vent system) is presumed to be the preferred method of depressurising the entire pipeline; this is considered separately in Ref S6. The shutdown and cooldown OLGA models produced in the previous start-up analysis (Ref S3) will be used as the basis for this study. [...]... 54 Transient Analysis – Depressuring and Venting (Pipeline) Figure 3-1 Schematic of OLGA Model for Depressurisation KCP-GNS-FAS-DRP-0004_02-ktKKDoc1 Transient Analysis - Depressurising and Venting (Pipeline) Printed on: 20-May-10 KCP-GNS-FAS-DRP0004 Rev.: 01 Project Title: Docume nt Title: 4 Kingsnorth Carbon Capture & Storage Project Page 14 of 54 Transient Analysis – Depressuring and Venting (Pipeline). .. Carbon Capture & Storage Project Document Title: Transient Analysis – Depressuring and Venting (Pipeline) 3 Page 11 of 54 Basis of Design and Assumptions Unless indicated otherwise, the basis of design and assumptions for this study are the same as those presented in Reference S1 3.1 Depressurisation Philosophy It is assumed that only the onshore pipeline and offshore platform topsides would be required... Project Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Depressurisation time and peak mass flow Offshore pipeline - vapour phase 200 400 180 350 160 300 140 250 120 200 100 150 80 100 60 50 40 0 2 4 6 depressurisation time 8 Peak mass flow (kg/s) depressurisation time (hr) Page 27 of 54 10 peak mass flow Figure 6-1 Depressurisation times and peak mass flow – offshore pipeline,... Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Page 29 of 54 distance of 240km from the pipeline, also in a low point, and represents the offshore section Trends for the 4” blowdown orifice are presented in Figure 6-4: Figure 6-4 Comparison of T, P in Onshore and Offshore Piping during Blowdown, Vapour Phase Operation Although the pressures are similar for the onshore and offshore... Kingsnorth Carbon Capture & Storage Project Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Page 30 of 54 6.3 Depressurisation of Offshore Pipeline - Dense Phase Operation The depressurisation times and peak mass flow rates are tabulated in Table 6-3 and illustrated in Figure 6-5 Table 6-3 Offshore Pipeline Depressurisation Times – Dense Phase Operation Depressurisation Peak Mass Peak... Title: Transient Analysis – Depressuring and Venting (Pipeline) Page 15 of 54 Table 4-1 Onshore Pipeline Depressurisation Times – Vapour Phase Operation Orifice Depressurisation Peak Mass Peak Std Vol Initial Settle-out size time Flow Flow pressure (barg) (in) (hrs) (kg/s) MSm³/d) 1 77 6 0.3 2 19 22 1 3 9 50 2 33.2 4 5 89 4 5 3 139 6 6 2 200 9 Figure 4-1 Pressure Upstream of Depressurisation Orifice – Vapour... Title: Kingsnorth Carbon Capture & Storage Project Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Page 19 of 54 Figure 4-6 Pressure Upstream of leak during Onshore Pipeline Depressurisation, Dense Phase Operation The minimum fluid temperatures downstream of the depressurisation orifice and in the pipeline and the minimum wall temperature in the pipeline are presented in Table... Carbon Capture & Storage Project Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Page 23 of 54 Figure 4-11 P-T Pathway at landfall valve, During Depressurisation of Onshore Pipeline (4“ Orifice), Dense Phase Operation Conversely for the position immediately upstream of the depressurisation orifice, the temperature increases a lot faster and so the P-T pathway does not follow the... Carbon Capture & Storage Project Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Page 32 of 54 Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation... Project Document Title: Transient Analysis – Depressuring and Venting (Pipeline) Page 22 of 54 The minimum fluid temperature in the pipeline is around -79°C for all orifice sizes As the vapourisation of CO2 is an endothermic process, heat must be absorbed to vapourise the liquid CO2 in the pipeline As the system behaviour tends towards adiabatic, this heat must come from the fluid itself and hence the temperature . (°C) Min wall temperature in pipeline (°C) 33.2 1 - 56 -3 -3 2 - 56 -4 -3 3 - 56 -6 -3 4 - 56 -7 -4 5 - 56 -9 -4 6 - 56 -10 -5 KCP-GNS-FAS-DRP-0004 Revision: 02 Project. Introduction 25 5.2 Results 25 6 Depressurisation of Offshore Pipeline 26 6. 1 Introduction 26 6. 2 Depressurisation of Offshore Pipeline - Vapour Phase Operation 26 6. 3 Depressurisation of Offshore. of Dense Phase Offshore Pipeline 36 Figure 6- 12 Operating Conditions at Riser Base, Dense Phase Offshore Pipeline Blowdown through 6 Orifice 36 Figure 6- 13 Downstream Temperature during