Hydroprocessing for Clean Energy

Design, Operation, and Optimization

Frank (Xin X.) Zhu, Richard Hoehn, Vasant Thakkar, Edwin Yuh

• Publisher: Wiley-AIChE
• Year: 2016
• Print ISBN: 9781118921357
• eBook ISBN: 9781119328254
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Chemical & Biochemical Engineering
• Index: Technology & Engineering

Provides a holistic approach that looks at changing process conditions, possible process design changes, and process technology upgrades

• Includes process integration techniques for improving process designs and for applying optimization techniques for improving operations focusing on hydroprocessing units.
• Discusses in details all important aspects of hydroprocessing – including catalytic materials, reaction mechanism, as well as process design, operation and control, troubleshooting and optimization
• Methods and tools are introduced that have a successful application track record at UOP and many industrial plants in recent years
• Includes relevant calculations/software/technologies hosted online for purchasers of the book

Part 1
Fundamentals

Chapter 1
Overview of This Book

1.1 Energy Sustainability

There is a paradox in this world: people want to enjoy life fueled with sufficient and affordable energy supply. At the same time, people wish to live in a clean environment. This paradox defines the objective of clean energy: provide affordable energy with minimum climate impact. This is a huge challenge technically, economically, geographically, and politically. There is no silver bullet for solving this paradox and the practical path forward is to determine a good mix of different kinds of energy sources. The proportions of this mix depend on the availability of these energy sources and costs of converting them to useful forms in geographic regions.

Energy demand has been increasing significantly over recent years due to the fact that people in emerging regions wish to improve their living standard and enjoy the benefit that energy can bring. Therefore, in the short and middle term, there is more oil and natural gas production to satisfy increased energy demand. To reduce the climate impact, sulfur content for the fossil fuels must be reduced – in particular, ultra-low-sulfur diesel (ULSD) is the focus in the present time. As far as energy efficiency is concerned, cars and trucks have become more fuel efficient and will continue to improve mileage per gallon. Furthermore, electrical and hybrid vehicles will improve energy efficiency even further. On the renewable energy side, the percentage of renewable energy, such as ethanol for gasoline and biodiesel blended into diesel fuel, will gradually increase over time through governmental regulation. Further technology development will make renewable energy such as wind, solar, and biofuels more cost-effective and hence these energy sources will become a sustainable part of the energy mix. These trends will coexist to achieve a balance between increased energy demand and a cleaner environment, and at the same time, less dependence on foreign oil imports. In the long term, the goal is to increase the proportion of alternative energy in the energy mix to reduce gradually the demand for fossil fuels.

In summary, clean energy is the pathway for meeting the increased energy demand with a sustainable environment and the best future for clean energy is to capitalize on all the options: renewable energy, fossil fuels, increased efficiency, and reduced consumption. When these multiple trends and driving forces work together, the transformation becomes more economical and reliable. Technology developments in clean energy will join forces with regulations and market dynamics in the coming decades and beyond.

1.2 ULSD – Important Part of the Energy Mix

ULSD is an important part of clean energy mix. Diesel fuel is made from hydroprocessing of certain fractions of petroleum crude. It is used in cars, trucks, trains, boats, buses, heavy machinery, and off-road vehicles. The bad news is that most diesel engines emit nitrogen oxides that can form ground-level ozone and contribute to acid rain. Diesel engines are also a source of fine particle air pollution. The impact of sulfur on particulate emissions is widely understood and known to be significant. In the European Auto Oil program, detailed study of lower effect on particulate matter (PM) was studied. This study suggests significant benefit from sulfur reductions for heavy-duty trucks. Reductions in fuel sulfur will also provide particulate emission reductions in all engines.

Testing performed on heavy-duty vehicles using the Japanese diesel 13 mode cycle have shown significant PM emission reductions that can be achieved with both catalyst and noncatalyst equipped vehicles. The testing showed that PM emissions from a noncatalyst equipped truck running on 400 ppm sulfur fuel were about double the emissions when operating on 2 ppm fuel (Worldwide Fuel Charter, Sept. 2013).

When sulfur is oxidized during combustion, it forms SO₂, which is the primary sulfur compound emitted from the engine. Some of the SO₂ is further oxidized – in the engine, exhaust, catalyst, or atmosphere to sulfate (SO₄). The sulfate and nearby water molecules often coalesce to form aerosols or engulf nearby carbon to form heavier particulates that have a significant influence on both fine and total PM. Without oxidation catalyst systems, the conversion rate from sulfur to sulfate is very low, typically around 1%, so the historical sulfate contribution to engine-out PM has been negligible. However, oxidation catalysts dramatically increase the conversion rate to as much as 100%, depending on catalyst efficiency. Therefore, for modern vehicle systems, most of which include oxidation catalysts, a large proportion of the engine-out SO₂ will be oxidized to SO₄, increasing the amount of PM emitted from the vehicle. Thus, fuel sulfur will have a significant impact on fine particulate emissions in direct proportion to the amount of sulfur in the fuel.

In the past, diesel fuel contained higher quantities of sulfur. European emission standards and preferential taxation have forced oil refineries to dramatically reduce the level of sulfur in diesel fuels. Automotive diesel fuel is covered in the European Union by standard EN 590, and the sulfur content has dramatically reduced during the last 20 years. In the 1990s, specifications allowed a content of 2000 ppm maximum of sulfur. Germany introduced 10 ppm sulfur limit for diesel from January 2003. Other European Union countries and Japan introduced diesel fuel with 10 ppm to the market from the year 2008.

In the United States, the acceptable level of sulfur in the highway diesel was first reduced from 2000 to 500 ppm by the Clean Air Act (CAA) amendments in the 1990s, then to 350, 50, and 15 ppm in the years 2000, 2005, and 2006, respectively. The major changeover process began in June 2006, when the EPA enacted a mandate requiring 80% of the highway diesel fuel produced or imported in order to meet the 15 ppm standard. The new ULSD fuel went on sale at most stations nationwide in mid-October 2006 with the goal of a gradual phase out of 500 ppm diesel.

In 2004, the US EPA also issued the clean air-nonroad-Tier 4 final rule, which mandated that starting in 2007, fuel sulfur levels in nonroad diesel fuel should be reduced from 3000 to 500 ppm. This includes fuels used in locomotive and marine applications, with the exception of marine residual fuel used by very large engines on ocean-going vessels. In 2010, fuel sulfur levels in most nonroad diesel fuel were reduced to 15 ppm, although exemptions for small refiners allowed for some 500 ppm diesel to remain in the system until 2014. After 1 December 2014, all highway, nonroad, locomotive, and marine diesel fuel produced and imported has been ULSD.

The allowable sulfur content for ULSD (15 ppm) is much lower than the previous US on-highway standard for low-sulfur diesel (LSD, 500 ppm), which allows advanced emission control systems to be fitted that would otherwise be poisoned by these compounds. EPA, the California Air Resources Board, engine manufacturers, and others have completed tests and demonstration programs showing that using the advanced emissions control devices enabled by the use of ULSD fuel reduces emissions of hydrocarbons and...

Table of contents

• Cover
• Title Page
• Copyright
• Table of Contents
• Preface
• Part 1: Fundamentals
• Part 2: Hydroprocessing Design
• Part 3: Energy and Process Integration
• Part 4: Process Equipment Assessment
• Part 5: Process System Evaluation
• Part 6: Operational Guidelines and Troubleshooting
• Index
• End User License Agreement