Solid-Liquid Filtration

A User's Guide to Minimizing Cost and Environmental Impact, Maximizing Quality and Productivity

Trevor Sparks

• Publisher: Butterworth-Heinemann
• Year: 2011
• Print ISBN: 9780080971148
• eBook ISBN: 9780080971155
• Topic: Technology & Engineering
• Subtopic: Fluid Mechanics
• Index: Technology & Engineering

Exploring the success factors that combine to deliver this performance. Finding ways to get more from your processes, with examples, case studies and scenarios. Solid-Liquid Filtration is a crucial step in the production of virtually everything in our daily lives, from metals, plastics and pigments through to foods (and crockery) and medicines. Using a practical and applied approach, Trevor Sparks has created a guide that chemical and process engineers can use to help them: - Understand how filtration processes affect production processes, production costs, product quality, environmental impact and productivity - Optimise process development and project execution, with real examples and supporting software forms and tools - Develop reporting tools to monitor processes, and find ways to get more from processes This book's focus is helping process engineers understand their filtration processes better. Its accessible approach and style make it a valuable resource for anyone working in this sector, regardless of prior knowledge or experience. - Several examples and scenarios are provided throughout the book in order to help engineers understand the importance of filtration and the effect that it has on the bottom-line. - Covers methods for optimizing processes, include process variable, plus laboratory testing, modeling and process troubleshooting - Accompanied by optimization software that enables readers to model and plan optimal filtration processes and set ups for their particular circumstance.

Chapter 1. Introduction

Chapter Outline

1.1 Scope2

1.2 Summary9

Filtration processes on a production plant can often be made more successful and give the overall production process a competitive advantage. The central ideas in this book are that: (1) the competitiveness of a production process is determined by how it performs in terms of production cost, product quality, productivity, and safety, health and the environment; (2) the outcomes of filtration steps within that process have a great impact on this competitiveness; (3) several success factors combine to determine filtration performance; and (4) a greater depth of knowledge about these success factors can optimize choices in process development, equipment selection/plant design and process optimization, leading to a competitive advantage. This book covers the filtration of solid particles in a slurry (e.g. removing solid matter from a liquor or liquid from a slurry), slurry filtration equipment (e.g. vacuum and pressure filters and centrifuges) and industrial applications (e.g. pharmaceuticals, food, minerals and metal production).

Creativity is just connecting things.

Steve Jobs, Wired Magazine, Feb 1996

There is a very good chance that the filtration processes on your production plant (or on paper, or even in your mind’s eye, as a part of a plant design) can be made more successful and that this, in turn, will give your overall production process a competitive advantage. That is why this book exists. The central ideas in this book are:

1. That the competitiveness of a production process, relativey to your competitors, is determined by how it performs in terms of:

• production cost

• product quality

• productivity

• safety, health and the environment (SHE).

2. That the outcomes of filtration steps within that process can have a great impact on this competitiveness. (And that, whenever possible, it is a good idea to quantify this impact in currency terms – some of the numbers can be very significant and still surprise me.)

3. That a number of discrete success factors combine to determine the performance of a filtration process.

4. That by having a greater depth of knowledge about these success factors you can optimize your choices in:

• process development

• equipment selection/plant design

• process optimization

and, thereby, create and sustain a competitive advantage.

The structure of the book follows this sequence of ideas.

The aim was not to produce a reference work on the subject of filtration; instead, I have tried to give some context to the subject as well as offer up some practical and applicable ideas that will lead directly to an improvement in your filtration processes. It can serve as an introduction for the uninitiated (giving suggestions for further reading for those wanting to deepen their knowledge), as a refresher for those who remember something about the subject from their process engineering education or, for someone with a deep theoretical knowledge of the subject, it can act to link their knowledge with more day-to-day challenges.

1.1. Scope

The field of filtration is large and wide, so we must be clear, from the beginning, about the scope of this book. ¹ The book covers:

¹As a young salesman, attempting to sell large-scale slurry filtration equipment to chemical and mining companies – some of these machines could individually weigh up to 100tonnes – I would still get calls from people: "Hello, I got your name from Yellow Pages, can you get me an oil filter for a 1971 Ford Capri?"

• Filtration of solid particles with typical particle sizes from 1μm to 100 μm in a slurry with >1% solids (weight by weight), for reasons that include:

– removal of a small amount of solid matter from a liquor (i.e. polishing)

– removal of liquid from a slurry (e.g. before transportation or evaporation)

– removal of product in the liquid phase from a slurry (in this case, the solid can either be a waste or a by-product)

– removal of a contaminant in the liquid phase from a solid product (the liquid may be recycled back into the process).

• Using slurry filtration equipment, including:

– vacuum filters: disc, drum, belt and pan continuous filters and vacuum nutsch batch filters

– pressure filters: chamber filters (filter press, tube press, automatic pressure filters), pressure vessel filters (candle, leaf and pressure nutsche)

– centrifugal filters: peeler, inverting basket, pusher.

• Industrial applications, including:

– pharmaceuticals: biotechnology, active pharmaceutical ingredients, fermentation broths, plant extracts, etc.

– food/beverage starch: sugar, yeast, brewing, etc.

– industrial minerals: kaolin, calcium carbonate, titanium dioxide, etc.

– metals production: mining, metal refining, alumina, etc.

– general process industry: bulk chemicals, waste treatment, polymers, etc.

Equations are used sparingly (where a picture can be used instead then it will be). This is because the emphasis is on improving process performance, rather than necessarily predicting it to a certain degree of accuracy. However, process engineers use spreadsheets for a great deal of their work and so calculations and models are described in more detail in the appendices and spreadsheets are made available for download from the website that accompanies this book. ²

²http://www.solid-liquid-filtration.com/

Throughout, I will refer to case examples to reinforce ideas. Where possible, these ideas and themes illustrated in these examples will be applicable to other cases or industries.

The book is written so that each of the central ideas is treated in turn. It is intended to be read as a whole, but can also be dipped into for a particular idea or piece of information. It is divided into four parts.

Part I serves to give some background to the field of solid–liquid filtration. Following a brief pseudohistorical review there is a background to the physical processes at play in an industrial filtration process. It will be noted, and explored, how the performance of full-scale filtration equipment (sometimes comprising more than 100tonnes of machinery and hundreds of square meters of filtration area) is determined by how countless billions of microscopic particles interact with each other, and how a certain numbe...

Table of contents

• Cover image
• Table of Contents
• Front Matter
• Copyright
• Preface
• List of Figures
• Chapter 1. Introduction
• 1.1. Scope
• 1.2. Summary
• Chapter 2. History of Filtration
• 2.1. Origins
• 2.2. Industrial Revolution and Onwards
• 2.3. Recent History
• 2.4. Current Trends
• 2.5. Summary
• Chapter 3. Physical Phenomena
• 3.1. Basic Narrative of a Filtration Process
• 3.2. Step-by-step Narrative
• 3.3. Other Notable Phenomena and Things to Look out for
• 3.4. Summary
• Chapter 4. Competitiveness in Processing
• 4.1. Production Cost
• 4.2. Product Quality
• 4.3. Productivity
• 4.4. Safety, Health and the Environment
• 4.5. Summary
• Chapter 5. The Outcomes of Filtration Processes
• 5.1. Filter Cake Outcomes
• 5.2. Filtrate Outcomes
• 5.3. Slurry Outcomes
• 5.4. Filtration Costs
• 5.5. Examples of Filtration as a Part of a Process
• 5.6. Summary
• Introduction
• Chapter 6. Slurry Filterability
• 6.1. The Nature of the Slurry to be Filtered
• 6.2. Pretreatment of the Slurry
• 6.3. Slurry Handling
• 6.4. Summary
• Chapter 7. Filter Design
• 7.1. Vacuum Filtration: Continuous
• 7.2. Pressure Filtration: Continuous
• 7.3. Pressure Filtration: Discontinuous
• 7.4. Centrifugal Filtration
• 7.5. Summary
• Chapter 8. Filter Installation
• 8.1. Human Considerations
• 8.2. Process Considerations
• 8.3. Slurry Systems
• 8.4. Cake Handling
• 8.5. Summary
• Chapter 9. Filter Cloth
• 9.1. Desired Outcomes
• 9.2. Cloth Design and Manufacture
• 9.3. Cloth Support Grid
• 9.4. Cloth in Operation
• 9.5. Summary
• Chapter 10. Filter Maintenance
• 10.1. Particular Issues with Filtration Equipment
• 10.2. Speed Versus Machine Sympathy
• 10.3. Component Plant Trials
• 10.4. Summary
• Chapter 11. Filter Operation
• 11.1. Operational Choices
• 11.2. Summary
• Chapter 12. Process Testing
• 12.1. Test Equipment
• 12.2. Testing Program
• 12.3. Design of Experiments
• 12.4. Sampling
• 12.5. Example Method
• 12.6. Data Acquisition
• 12.7. Archiving Data
• 12.8. Cake Washing
• 12.9. Analysis
• 12.10. Summary
• Chapter 13. Getting the Most from Filtration Processes
• 13.1. Product Development and Process Design
• 13.3. Process Optimization
• 13.4. Summary
• Bibliography
• Appendix A. Useful Expressions
• Appendix B. Flow Through a Growing Porous Filter Cake
• Appendix C. Forms and Templates
• Appendix D. Sample Test Method
• Index