(84aq) Maximizing Cost Savings and Reducing CO2 Emission in NCC Process with Heat Exchanger Networks: An Integrated Analysis

Olefins are considered an essential raw material in the chemical industry to manufacture various products for daily life, including plastic, synthetic fiber, etc. Several techniques have been developed to produce olefins, such as ethane cracking center (ECC), coal to olefin (CTO), and naphtha cracking center (NCC) [1], and NCC is mainly applied in Asia and Europe. In the NCC process, naphtha is thermally cracked at temperature above 800 â—¦C and rapidly cooled to temperature below 400 â—¦C through a series of step [2]. Since it requires a significant amount of heat and cooling energy simultaneously, the NCC process is energy-intensive and waste energy exists inside of the process. Recycling waste heat and cooling energy is necessary to improve energy independence and economic benefits.

Motivated by these considerations, the heat exchanger network (HEN) using pinch analysis is presented [3]. This methodology involves the use of a heat exchanger to transfer heating and cooling energy between two streams in a process, ensuring that they reach the required condition. Since the installation cost of the heat exchanger depends on the area of the heat exchanger, an economic evaluation based on the area of the heat exchanger should be conducted. Also, as external energy input decrease, not only economic benefits but also environmental factors is affected. Many studies using HEN have proposed an economic evaluation, but environmental impact assessment has not been considered about HEN by calculating the reduced utility amount. Therefore, an integrated evaluation considering the economy and environment should be conducted.

We focus on the development of multiple heat exchange networks using data extracted from an actual NCC processes and optimal heat exchange networks are derived. In addition, an integrated assessment combining economic and environmental impact assessment is conducted based on the amount of carbon dioxide generated from the varied types of energy generation fuel (e.g., coal, natural gas, biogas, waste plastic, etc.) and energy production methods (e.g., solar power generation). Based on this integrated assessment, the optimal HEN configuration will be determined by minimizing the payback period considering installation cost, utility reduction, and CO₂ emission.

Literature cited:

1. Kim, S. and S. Oh, Impact of US Shale Gas on the Vertical and Horizontal Dynamics of Ethylene Price. Energies, 2020. 13(17): p. 4479.
2. Han, S.Y., et al. Selective formation of light olefins by the cracking of heavy naphtha. in Carbon Dioxide Utilization for Global Sustainability: Proceedings of the 7th International Conference on Carbon Dioxide Utilization, Seoul, Korea. 2004.
3. Linnhoff, B. and E. Hindmarsh, The pinch design method for heat exchanger networks. chemical engineering science, 1983. 38(5): p. 745-763.