Publications on polyethylene terephthalate (PET) continue to increase including the number of publications on recycling. PET is a versatile material with the ability to be remade from its polymer state through mechanical recycling and even back to its original monomer through advanced recycling. The scale of PET's use affords continued research and applications in improved recycling. Publications on new uses of discarded PET and the ability to clean and convert it into many forms including alternative materials are expanding with an attempt to complete circular use or improve the end of life. As indicated in life cycle assessment studies, increases in recycling lower the energy required to manufacture products. The future for PET will reduce energy demands further with the largest breakthroughs in recycling technologies and bio‐sourced resins trending toward zero energy and carbon negative solutions. Opportunities remain for improvement in the use of PET with light weighting. The testing of new resins, development of bio‐feedstocks, improvements in engineering, processing, recycling, and design continue to provide benefits. This review provides context for these developments.
Traditional energy production plants are increasingly forced to cycle their load and operate under low-load conditions in response to growth in intermittent renewable generation. A plant-wide dynamic model of a supercritical pulverized coal (SCPC) power plant has been developed in the Aspen Plus Dynamics® (APD) software environment and the impact of advanced control strategies on the transient responses of the key variables to load-following operation and disturbances can be studied. Models of various key unit operations, such as the steam turbine, are developed in Aspen Custom Modeler® (ACM) and integrated in the APD environment. A coordinated control system (CCS) is developed above the regulatory control layer. Three control configurations are evaluated for the control of the main steam; the reheat steam temperature is also controlled. For studying servo control performance of the CCS, the load is decreased from 100% to 40% at a ramp rate of 3% load per min. The impact of a disturbance due to a change in the coal feed composition is also studied. The CCS is found to yield satisfactory performance for both servo control and disturbance rejection.
Thermal power plants that have been designed to operate at their rated capacity are being forced to cycle their load and operate under low-load condition to meet changing load demands due to the increased penetration of renewables into the electric grid. The rapid load-following operation is leading to challenging control problems. The goal of this research is to develop dynamic model and control system for efficient load-following operation. The focus of this work is on supercritical pulverized coal (SCPC) power plants. The steady-state model is developed using Aspen Plus and Aspen Custom Modeler and then converted to a pressure-driven Aspen Plus Dynamics model, where the regulatory control layer and coordinated control system (CCS) are developed for efficient servo control and disturbance rejection characteristics. A detailed threeregion dynamic model of the feed water heater is also developed. The model can estimate the changing size of desuperheating, condensing and subcooling zones during load-following. As key components of CCS, control strategies for the coal flow, air flow, boiler feedwater flowrate and reheat steam temperature are developed. The control strategy for the main steam temperature control is developed with due consideration of the time delay of the SCPC system.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.