EMS621U Process Safety and Loss Prevention, Final Assessment Coursework 2- Safety assessment report 1. Introduction The aim of this coursework is to test you against the learning objectives of the module: •Learn the lessons from historical safety incidents (done in CW1) • Identify and avoid common hazards (e.g. fire) • Quantify event likelihood and consequences • • Use engineering tools for identifying and analysing hazards (e.g. HAZOPS, LOPAS, bowties, fault trees...) Estimate & improve reliability of safety systems Assess and improve chemical plant designs for inherent safety ● Design and specify add-on safety measures We want you to show that you understand the theory and tools and can apply (and even critique) them over a real-world situation. Like most other 3rd year modules, this assessment is exploratory/open-ended: whilst we give you lots of data to start with, you will have to collect other data or make credible assumptions using sound engineering judgement. This coursework revolves around conducting a safety review of a steam methane reforming (SMR) process, to produce low carbon hydrogen for use as a fuel. I encourage you to look at the resources given here and beyond to understand the process so that you can produce a credible design and safety assessment. Each of you will be allocated a small section of this plant to produce a P&ID and conduct a safety review given a specific hazard: there are enough combinations of equipment and safety hazards such that you will all have a different item to study in detail. Allocations of the plant and the safety hazard will be posted alongside this brief. 2. Submission and feedback • Deadline is ● This is your final coursework which is an equivalent to an exam, so the results will be released at the same time as the exam results I will provide feedback with the results and I would be very happy to go through these results should you have any queries. Page 1 of 8 3. The process: Steam methane reforming The overall process to produce hydrogen from natural gas involves reacting methane with steam in a reforming reaction, and then a water-gas-shift reaction, that produces what is known as ‘syngas' (i.e. synthetic gas), a mixture of CO2 and hydrogen. The hydrogen and CO2 are then separated and purified and voila. CH4 + H2O ↔ CO + 3H₂ CO + H20 → H2+CO2 ΔΗ = 206 MJ/kmol AH = -41 MJ/kmol (1) (2) The reforming reaction occurs at ~850 C and 25 bar g and is endothermic, so must be heated via direct gas fired heating within the reformer. The reaction occurs with a Nickel catalyst and produces a mixture of carbon monoxide and hydrogen, alongside unreacted water and a small amount of unreacted methane. The reformate products are then cooled with cooling water prior to entering the water gas shift reactions. The water gas shift occurs via a fixed bed catalytic reaction over two stages (a high temperature shift at 350 C and a low temperature shift at 230 C), both of which are exothermic. Water reacts with the carbon monoxide that is produced in the reformation reaction to form more hydrogen and carbon dioxide. To separate the hydrogen from the CO2, the mixture goes through an amine absorption column at ~120 C and 22 bar g. The gas is feed to the bottom of the absorber and the liquid amine is fed to the top and absorbs the CO2 as the gas flows upwards. A purified hydrogen mixture exits the top of the column, with the bottom lean amine stream exiting the bottom. The lean amine with absorbed CO2 is then heated with steam and passes through a stripper column to remove the CO2, allowing the purified amine to recirculate back to the absorption column. The CO2 stream from the stripper passes through a condenser and then to a knock out drum which separates the remaining liquid amine fraction. The purified hydrogen and CO2 streams are then compressed to high pressures to be stored in intermediate storage prior to being sent as product to the customer. Page 2 of 8 4. Process Flow Diagram Steam Methane V1 Methane feed tank C1 Compressor 2 E1 Heater R1 Reformer E4 Cooler 8 V2 Absorption column 9 12 3 E2 Cooler 13 16 R2 HT water gas shift 5 E3 Cooler R3 LT water gas shit C2 Compressor E8 Cooler V5 H2 storage 15 C3 Compressor E9 Cooler V6 CO2 storage E7 Cooler V4 Knock out 10 drum E6 Cooler E5 Heater P2 Pump 11 P1 Pump V3 Stripper column 14 Page 3 of 8 To truck To truck Steam Methane V1 Methane feed tank E4 Cooler 8 V2 Absorption column 9 C1 Compressor 2 E1 Heater R1 Reformer 12 E2 Cooler 13 16 4 R2 HT water gas shift 6 E3 Cooler R3 LT water gas shit 15 DØ C2 Compressor E8 Cooler V5 H2 storage C3 Compressor E9 Cooler V6 CO2 storage E7 Cooler 10 V4 Knock out drum E6 Cooler E5 Heater P2 Pump 11 P1 Pump L V3 Stripper column 14 Page 4 of 8 To truck To truck Stream tables: Stream 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Steam Reformat Cooled WGS HT WGS LT Name input Methane e reformate WGS HT Vapour Fraction 1 1 1 1 1 cooled 1 WGS LT cooled Rich amine Stripper Stripper feed bottom Lean amine Stripper Knock out CO2 Hydrogen vent return product product 1 1 0 1 0 0 1 0 1 1 Temperature [C] 371 371 857 400 400 300 300 49 Pressure [bar g] 24 24 24 24 24 24 24 22 22 49 120 120 38 120 10 10 49 22 2 2 22 2 22 22 22 Mass flow [kg/hr] 27851 8267 26520 26520 26520 26520 26520 26520 2791714 2791714 2753705 2753705 83009 45000 3656 15277 Mole frac (Methane) 0% 100% 3% 3% 3% 3% 3% 3% 0% 0% 0% 0% 10% 18% 0% 0% Mole frac (H2O) 100% 0% 38% 38% 26% 26% 25% 25% 6% 6% 0% 0% 55% 25% 0% 0% Mole frac (CO) 0% 0% 15% 15% 2% 2% 1% 1% 0% 0% 0% 0% 0% 0% 0% 0% Mole frac (CO2) 0% 0% 0% 0% 12% 12% 14% 14% 6% 6% 1% 1% 4% 0% 100% 0% Mole frac (Hydrogen) 0% 0% 44% 44% 56% 56% 58% 58% 1% 1% 0% 0% 30% 56% 0% 100% Mole frac (H2S) 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% Mole frac (Amine) 0% 0% 0% 0% 0% 0% 0% 0% 87% 87% 99% 99% 0% 0% 0% 0% Page 5 of 8