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(Solved): An airstream coming from a new UK industrial coal plant producing 350MWt of energy, flowing with a ...
An airstream coming from a new UK industrial coal plant producing of energy, flowing with a mass rate (kilograms per hour), contains the following composition of pollutants: Particle density is constant and equal to . The process operates at and . The properties of the gas stream can be approximated to those of dry air. Answer the following questions. (a) Design a purification plant that is able to fulfil the environmental legislations. Clearly explain your calculations and clearly state all the assumptions made. Use one unit operation type for particle collection and one type for gas purification. You can also use more pieces of equipment of the same type in series or parallel if appropriate. [25 marks] (b) Evaluate the environmental impact of the process and report the results in a table according to the IChemE requirements. [5 marks] (c) Draw a complete PFD of the process designed. Include the details for all the pieces of equipment designed as well as for the streams. [5 marks] (d) Briefly describe alternative changes to your design configuration which would contribute to fulfil the legislation requirements or even to improve the overall efficiency of the plant. Detailed calculations are not required, but quantitative considerations need to be made to justify the choice. [15 marks]
Expert Answer
(a) Designing a Purification Plant:To fulfill the environmental legislation requirements, we need to remove the pollutants, SO2 and particles, from the airstream. We will design a purification plant using two unit operations: particle collection and gas purification.Particle Collection: We will use an electrostatic precipitator (ESP) for particle collection. An ESP uses electrostatic forces to capture and remove particles from the gas stream. The particles will be charged, and then electrostatic plates will attract and collect them. The ESP can handle a wide range of particle sizes and has a high collection efficiency.Calculation for Particle Collection: Given:Particle diameter: 5 micronsParticle density: ? = 1,600 kg/m³Gas flow rate: mtot = 10,000 kg/hrGas density (dry air): ?_gas = 1.184 kg/m³ (at 25°C and 1 atm)Assumptions:The gas composition is approximated to that of dry air.The gas temperature and pressure remain constant during the process.We need to convert the gas flow rate from kg/hr to m³/s: mtot = 10,000 kg/hr = 10,000/3,600 kg/s = 2.778 kg/sThe volumetric flow rate of the gas: Vdot = mtot / ?_gas = 2.778 kg/s / 1.184 kg/m³ = 2.348 m³/sThe total mass of particles in the gas stream: m_particle = (1 g/m³) * Vdot = 1 g/m³ * 2.348 m³/s = 2.348 g/s = 0.002348 kg/sThe total number of particles: N_particle = m_particle / (? * (4/3) * ? * (diameter/2)³) = 0.002348 kg/s / (1,600 kg/m³ * (4/3) * ? * (2.5e-6/2)³) = 37.29 particles/s