建立工業級焦爐氣淨化製程之操作指引系統

Abstract

近年來，虛實整合系統(Cyber Physical System, CPS)及智慧製造的概念被廣泛應用於各類工業製程改善，透過建立製程模型(虛擬系統)，並對製程模型進行操作變數之分析，可提供改善操作效率之可能策略，為實際製程(實際系統)創造價值。本研究以煉鋼業中之焦爐氣淨化製程為例，展示虛實整合系統及智慧製造如何具體應用於煉鋼業。焦爐氣作為煉焦廠之副產品，含有豐富之氫氣及甲烷，可做為廠內燃料以增加能源使用效率，其分離製程主要包含除Tar、除硫氨及除芳香烴三個子製程，本研究以商用軟體Aspen Plus建立後兩個子製程之製程模型，並以此為基礎建立操作指引系統，該系統可根據入口焦爐氣之條件，提供操作變數之建議。相較於傳統操作策略，使用操作指引系統可在不違反環保法規之前提下，減少洗滌液流率和蒸汽用量，增進製程之能源使用效率。根據模型分析，使用該系統可降低除硫氨製程中氨蒸餾塔之26%低壓蒸汽用量，以及除芳香烴製程中預熱器之26%中壓蒸汽用量。此外，本研究亦根據模型分析提出操作改善建議，其中一個建議可在不違反廢水品質之前提下，將出口焦爐氣硫化氫濃度降低至現有水準之30%，另一個建議則可在不影響出口焦爐氣芳香烴濃度前提下，將除芳香烴製程中預熱器之中壓蒸汽用量下降10%。

Recently, the concepts of cyber-physical systems (CPS) and smart manufacturing have been applied in various industrial scenarios to improve process efficiency. By establishing a process model (cyber system), operating variables can be analyzed to identify potential process improvements, enhancing the design and op eration of the physical system. This work focuses on a commerical-scale coke oven gas (COG) purification process to demonstrate the implementation of CPS and smart manufacturing in the steel industry. COG, a byproduct of coke oven plants, contains abundant hydrogen and methane and is typically used as fuel in the plant to reduce coal consumption and increase energy efficiency. To minimize SOx, NOx, and soot formation during combustion, impurities in COG, such as tar, H2S/NH3, and aromatic compounds, must be removed beforehand. Using Aspen Plus, commercial-scale H2S/NH3 removal and aromatic removal processes were modeled, and an operation guidance system was developed. This system provides operational suggestions based on the inlet COG condition, reducing scrubbing liquid and steam usage while complying with environmental regulations. Scenario analysis showed that the system could reduce LP steam consumption in the ammonia stripper by 26% and MP steam consumption in the preheater by 26%. Additionally, two process improvement strategies were proposed. One strategy reduces outlet COG H2S concentration by 70% without violating wastewater composition regulations. The other reduces MP steam consumption in the aromatic removal process by 10% without affecting outlet COG aromatic composition.