4 Mistakes to Avoid in Your Hydrogen Liquefaction Process Design

Hydrogen is going to be part of energy transition. Hydrogen liquefaction is going to be part of hydrogen value chain.

Are you ready to liquefy hydrogen? Before you start, you might want to avoid four (4) mistakes in your process design.

How to estimate your ASU power consumption with your calculator, not your computer

Guofu just published a paper on "Chemical Engineering Progress" magazine, that featured how to estimate your cryogenic air separation units power consumption with your calculator, not your computer.

Separation, Compression and Liquefaction Power Consumption Calculator of Cryogenic Air Separation Units

Many of my blog readers asked me to generate an Excel spreadsheet to quickly calculate the energy consumption of cryogenic air separation units, regarding the separation, compression and liquefaction power. Based on one of my blogs http://showcase.guofuchen.com/2014/01/blog-post.html, an excel worksheet was developed to answer this challenge. Simply input the flow and pressure of gaseous oxygen and nitrogen, and the liquid oxygen and nitrogen flow, this worksheet will magically tell you the approximate power consumption instantly.

LNG Liquefaction Power Calculation

This blog shows you how you can calculate the LNG (Liquefied Natural Gas) liquefaction power. To liquefy the natural gas at 50 bara and 15 C, approximately the liquefaction power is 0.25 kWh/kg or 10 kW/(ton/d). That's to say, to liquefy 1 kg LNG, about 0.25 kWh energy is to be consumed. For a 5 million metric ton per annum (mmtpa) LNG liquefaction plant, the power consumption is about 137 MW. At the end of this blog, you can download the calculation file for details provided by +Guofu Chen.

Exergy Analysis of an Cryogenic Air Separation Unit (ASU)

This blog analyzes the exergy loss and distribution in an Cryogenic Air Separation Unit (ASU). This example was extracted from Perry's Chemical Engineers' Handbook (7th edition, Chapter 4 Thermodynamics, Page 4-36). At the end of the blog, you can download a step-by-step excel calculation example by +Guofu Chen.

Air Separation Unit (ASU) Energy Impact of Main Vaporizer DT

Answers to some common Air Separation Unit, Oxygen and Nitrogen Liquefaction Questions

Question 1: If I change the delta T of the main vaporizer from 2.5 °C to 1.5 °C, how much energy consumption can I save?

Answer 1: Your energy saving is:

           

Energy saved (kW) = 0.0478 * Q * (2.5 – 1.5) = 0.0478 * Q

           

Where Q is the main vaporizer duty in kW

主冷凝蒸发器温差和液体膨胀机对空分功耗的影响 Oxygen Separation Liquefaction

主冷凝蒸发器温差和液体膨胀机对空分能耗的影响

摘要: 本文对空分流程工程师非常关心的主冷温差和液体膨胀机对能耗的影响进行了火用分析，并且明确指出：1）主冷凝蒸发器温差每减少1 K，空分将会节省0.0478 X Q的能耗，这里Q是主冷凝蒸发器的换热量。2）液体膨胀机的使用将会节省4.7倍于自身轴功率的能耗。

关键词:火用；有效能；火用损；空分流程；功耗；主冷；主冷凝蒸发器；温差；液体膨胀机；氧气；氮气；液氧；液氮

空分流程中几个基本热力过程的Yong再分析 Oxygen Separation Liquefaction

空分流程中几个基本热力过程的Yong再分析

摘要: 本文基于毛绍融老师在深冷技术2002年第一期第一页上发表的文章，对空分流程中几个基本热力过程进行了简易而又深刻的数值再分析，从而为流程工程师在流程的改进和优化方面提供了清晰的方向；并且在文末给出一个计算功耗的示例。本文不同于毛老师的地方在于，毛老师使用了软件来计算物性参数，而笔者只是简单地使用了几个基本热力学方程便达到了同样的目的，并且得出了明确的结论。

关键词:Yong；有效能；Yong损；空分流程；功耗；分离功；压缩功；液化功；氧气；氮气；液氧；液氮

Exergy Reanalysis of Several Basic

Thermodynamic Cycles in Air Separation Processes

空分系统的氧气和氮气压缩功、分离功和液化功

摘要: 本文对空气分离系统中最重要的能耗进行了深入的分析。空分能耗可以分成三类：压缩功、分离功和液化功。作者分别使用了经典计算方法和火用计算方法来计算上述三类功，并且得出完全相同的结果。在文末，作者指出：火用计算方法就像一把万能钥匙，不管中间发生的过程如何，比如说压缩、换热和精馏，也不管是压缩功、分离功和液化功，只要知道起始和终了状态，通过 E = h - T0 x S 分别算出起始和终了状态的火用，两者之差即为要使该过程发生的最小功。

关键词: 火用；有效能；火用损；空分流程；功耗；分离功；压缩功；液化功；氧气；氮气；液氧；液氮

Abstract: The most important energy consumption of Air Separation Unit is analyzed comprehensively. Energy consumption of ASU can be divided into three categories: compression, separation and liquefaction. The classical and EXERGY calculation methods are used to calculate them and achieve the same results. In the end, the author concludes that: EXERGY calculation method is just like an almighty key to solve all the problems, whatever the intermediate processes are, such as compression, heat exchanger and distillation; whatever needs to be calculated, such as compression, separation and liquefaction energy; once the beginning and ending conditions are known, through E = h - T0 x S the EXERGY of beginning and ending conditions can be calculated and the EXERGY difference is the minimum energy to drive the process.

Keywords: Exergy; Available energy; Exergy loss; Air separation process; Power consumption; Energy of separation, compression and liquefaction；oxygen; nitrogen; liquid oxygen; liquid nitrogen