$[$Chemical Engineering$]$

Please explain the process mechanisms:

All auger tubes of the pyrolyzer were under negative pressure, which caused volatiles and gases $(890$ kg h$1)$ to be transported to a temporary storage drum $($a vapor$$liquid separator$).$ The assumed heat losses lowered the temperature of the pyrolysis products from $600\backslash$deg C to $520\backslash$deg C during transportation. Approximately $12\mathrm{.}5$ t h$1$ of air was compressed and heated to $390\backslash$deg C in an air preheater. A combustion mixture of hot air and pyrolysis products was then

utilized for three major sinks of high$-$temperature heat: the pyrolyzer, activation reactor, and Rankine cycle boiler. Eventually, all combustion products were utilized in the Rankine cycle as they vaporized and superheated the steam. Approximately $4$ t h$1$ of water was utilized in the Rankine cycle for electricity generation. After the last turbine expansion, the hot water$/$steam mixture at $209\backslash$deg C and $2$ bar first transferred heat in the ORC boiler and then emitted heat to meet the unit operation requirements of preheating, drying, and desorption. The steam was completely reliquefied in a cooling water condenser, after which it was compressed to a maximum pressure of $170$ bar to restart the cycle. The flue gases exited the Rankine cycle boiler at $400\backslash$deg C and were used to preheat the combustion air, which cooled the gases down to $135\backslash$deg C$.$ This temperature was too high for CO$2$ capture using the pressure swing adsorption $($PSA$)$ system and would require a large amount of cooling water to reduce the temperature

below $50\backslash$deg C $($owing to the sheer flow rate of the flue gas$).$ Therefore, an ORC was introduced to utilize this large amount of waste heat. The ORC working fluid $(5$ t h$1$ of isobutane$)$ was compressed to $18$ bar and entered the first reboiler at $18\backslash$deg C$,$ where it absorbed the flue gas heat and cooled the gas to $40\backslash$deg C$.$ As it exited the reboiler, the isobutane had a vapor fraction of only $36\%$; therefore, the heat needed to achieve total vapor was provided by the Rankine cycle hot water in the second reboiler. The ORC turbine expanded the isobutane to $3$ bar and generated $95$ kW of work, after which it was condensed to liquid at $15\mathrm{.}2\backslash$deg C and was recompressed. In all the cases, the total gross power generated from the combined power cycles was approximately $1\mathrm{.}36$ MW or $0\mathrm{.}710\mathrm{.}73$ MW net when all unit operations were considered. The cooled flue gas was first separated from the condensed water in a flash drum, after which the CO$2$ was separated using a series of PSA beds that utilized the three WPDPCs$.$ The amount of PSA adsorbent bed material $($calculated from the flue gas composition, flow rate, and experimental isotherms$)$ necessary for complete CO$2$ separation varied from $46$ to $76$ tons based on the activation route. The CO$2-$rich gas was compressed to a pipeline pressure of $50$ bar and was removed from the process either as a secondary product or for storage.