氨裂解產氫與二氧化碳直接氫化費托反應之整合製程 設計分析

Abstract

本研究利用氨裂解反應製綠氫與碳捕捉二氧化碳，通過費托(FT)反應將二氧化碳轉化為碳氫化合物(烷類、烃類)後進入分離程序，序列式的分離出各種燃料（如輕烴、汽油、航空燃料、柴油），在未來的去碳化經濟中是一個有前景的選擇。 整個製程一共分成三個部分，第一部分為ammonia decomposition 產氫，本研究探討了不同的反應器架構(恆溫反應器、絕熱反應器、非恆溫反應器)以及不同的換熱物質(氨氣燃燒、熱熔鹽)去做比較 ，盡可能使實際反應器狀況貼近恆溫反應器。。經過初步之設計，得知使用非絕熱式反應器(換熱物質為熱熔鹽)之轉化效能較貼近恆溫反應器。在氨分解製程之後我們提出了一個使用物理吸附的PSA使氫氣與氮氣分離的建議，而此PSA使用了zeolite 5A 的吸附劑並且使用了4個床8個步驟使氫氣純化高達99.99%而回收率達80%。接著第二部分我們利用經PSA產出的氫氣與二氧化碳進行 One-step RWGS及FT反應，開發了四種由Anderson-Schultz-Flory（ASF）分布描述的不同鏈傳播概率（ɑ）特徵的情景，分別對應於生產輕烴（ɑ=0.3）、汽油（ɑ=0.65）、航空燃料（ɑ=0.75）和柴油（ɑ=0.85）。針對每種情景，通過詳細的數學建模研究了利用不同反應器數量、採用各種熱傳遞方法和填充不同催化劑的替代配置。為了確定最佳設計和操作條件，進行了多目標優化，旨在最大化轉化率和最小化生產成本。最後第三部分，提出了一種統一的系統，適用於從不同的產品分布中分離汽油、航空燃料和柴油。該分離系統旨在提高效率並降低成本，為行業提供更加經濟和實用的解決方案。

This study utilizes ammonia decomposition to produce green hydrogen and captures carbon dioxide, converting it into hydrocarbons (alkanes and hydrocarbons) through the Fischer-Tropsch (FT) reaction. These hydrocarbons then undergo separation processes to sequentially extract various fuels (such as light hydrocarbons, gasoline, jet fuel, and diesel). This approach is a promising option in a future decarbonized economy. The entire process is divided into three parts. The first part involves hydrogen production through ammonia decomposition. This study explores different reactor configurations (isothermal, adiabatic, and non-isothermal reactors) and different heat exchange substances (ammonia combustion, molten salt) to compare and closely match the actual reactor conditions to those of an isothermal reactor. Preliminary design indicates that using a non-adiabatic reactor (with molten salt as the heat exchange substance) achieves conversion efficiency close to that of an isothermal reactor. Following the ammonia decomposition process, we propose using PSA (Pressure Swing Adsorption) for separating hydrogen and nitrogen. This PSA system uses zeolite 5A adsorbent and employs four beds with eight steps to achieve hydrogen purification up to 99.99% with an 80% recovery rate. In the second part, we utilize the hydrogen produced by the PSA system and carbon dioxide for one-step RWGS and FT reactions. Four scenarios characterized by different chain propagation probabilities (ɑ) described by the Anderson-Schultz-Flory (ASF) distribution were developed, corresponding to the production of light hydrocarbons (ɑ=0.3), gasoline (ɑ=0.65), jet fuel (ɑ=0.75), and diesel (ɑ=0.85). For each scenario, alternative configurations utilizing different reactor numbers, employing various heat transfer methods, and packing different catalysts were investigated through detailed mathematical modeling. Multi-objective optimization, aiming to maximize conversion and minimize production costs, was conducted to determine the optimal design and operating conditions. The third part proposes a unified system applicable for the separation of gasoline, jet fuel, and diesel from different product distributions. This separation system aims to enhance efficiency and reduce costs, providing a more economical and practical solution for the industry.