BIOMASS TRUCKS AND DUMPERS

Introduction

Most raw materials for plants that process woody biomass are delivered in bulk trucks and some are delivered by railcar. This article concerns biomass delivery by truck and the systems available for unloading the trucks.

Chip Truck Dumper
Chip Truck Dumper

Residual chips, shavings, and sawdust from sawmills are delivered primarily by truck to pulpmills, pellet plants, and panelboard plants. Woodwaste (hog fuel) from sawmills and other raw log processors is delivered by truck to biomass-fired energy systems and cogeneration plants. Wood pellets are delivered by truck and by railcar and are loaded onto ships or delivered direct to biomass-fired power plants.

Delivery by Truck

There are many different types and sizes of trucks used depending upon the material being handled, the weather conditions, the unloading facilities available, distances traveled, the types of truck available, road conditions, the most economical transport method, road weight allowances, required throughput capacity, etc. There are generally two types of trucks used: self unloading and non-self unloading trucks. Continue reading →

PLASTIC CONTAMINATION IN PULP

Introduction

“Plastic is Drastic” is the theme of an environmentalist group that is concerned about plastic contamination in the oceans.  It has also been a constant refrain heard for decades in pulp and paper mills throughout the world.

Miniscule tramp particles of plastic are present in most pulp and paper, and can cause numerous and costly operating problems not only for the pulp producer but also for the end-user. Plastic particles become embedded in the pulp and can cause the sheet to tear during processing or will become coated on equipment and cause streaks in the pulp.  Additionally, plastic particles embedded in paper will not accept printing ink.

Indeed, plastic contamination in pulp is a small but significant and costly problem in pulp manufacture; the amount of plastic in one small plastic pen can ruin 1,000 tonnes of pulp.  Generally, the industry has done a great job of controlling the amount of plastic used in a pulp mill, but plastic contamination is still a significant problem that mill operators keep a `keen’ eye on.

Unfortunately, there is no `magic bullet’, when it comes to eliminating plastic contamination.  Removing plastic from pulp is almost impossible, so the best solution is to prevent plastic from getting into the wood chips and pulp in the first place. Continue reading →

DETERMINING THE NATURAL COMPACTION OF A BIOMASS PILE

Paul Janzé – Advanced Biomass Consulting Inc.

For many reasons, people need to know how much material is present in a biomass storage pile. Hog Fuel Storage, 2Accurate volume measurement is relatively easy, but to determine the amount of dry fibre actually present, the compacted density and moisture content are required. In fact, the greatest number of queries I receive at this website are with regard to biomass pile density and compaction. This is because compaction is the most difficult pile parameter to determine with any consistent accuracy.

Biomass is highly compressible both through artificial and natural means. Every material is different and every pile is different.  The amount of compaction depends upon the species, the form of the material, the relative amounts of bark, wood and foliage present, the grind size, particle size distribution, moisture content, weather conditions, the shape of the pile, how the pile is constructed, how long it has been sitting, the amount of decomposition, the amount of contamination with dirt, grit or stones, etc. So, it is just an educated guess as to how much compaction there will be in any one pile. Continue reading →

Helical Chute for Wood Pellets

Paul Janzé – Advanced Biomass Consulting Inc.

Introduction

Some materials such as wood pellets are quite fragile and tend to break up when handled. ABC - Helical Chute,2Wood pellets are manufactured from small wood particles, generally <3.0mm (<1/8″), which are compressed in pelletizers into small cylinders 6-8mm in dia. x up to 50mm long. Pellets are held together by the binding action of the lignin that is naturally present in the wood fibre, acting under pressure. From the moment they exit the pelletizer and fall into the receiving conveyor, the pellets start to break up. At every conveyor transfer point, in bucket elevators, screw and chain conveyors, falling into bins, loading into trucks, railcars or ships, they degrade some more. Every time they are handled by crane or mobile equipment, they break up a bit more into their constituent parts. The best way to reduce product damage and small particle generation is to handle the pellets as gently as possible. Falling >30m (100′) into a silo results in high velocity impact forces, breakage and dusting. Consequently when faced with the problem on a recent project, we developed a spiral / helical chute which allows pellets to slide rather than freefall to the bottom of a silo.

Continue reading →

DISC SCREEN FUNDAMENTALS

Author: Paul Janzé, Advanced Biomass Consulting Inc.

Sliver Screen2The disc screen is a simple piece of equipment that is ideal for, and commonly used for screening woody biomass. It consists of a series of driven shaft assemblies mounted in a frame.  Each rotor shaft assembly has profiled discs mounted at regular spacings. The discs from one shaft interleaf with those on the adjacent shafts, creating open areas between the discs and the shafts.

Incoming material is fed onto one end of the screen.  The shaft assemblies rotate, and the discs agitate the material. Pieces of material that are smaller than the spacing between the discs and shaft assemblies fall through the screen.  The pieces that are larger than the openings are conveyed along the top of the discs and pass over the end of the screen.

Disc screens are particularly useful for screening biomass for the following reasons: Continue reading →

SCREENS FOR WOODY BIOMASS

Author: Paul Janzé, Advanced Biomass Consulting Inc.

Harmac Scalping Screen, 1
Disc Screen

Because of the wide variation in material characteristics, selecting the appropriate screen for woody biomass is not as straight forward as it is for other materials.  This article is intended to provide general screen selection information based on the author’s experience as to what types of screens work best with different forms of woody biomass.

I’ve said this many times before and I will repeat it once again.  “Biomass is not an easy material to handle. It appears in a myriad of species, forms and sizes; it knits together, doesn’t flow well, consolidates and packs easily. It can have a wide range of moisture contents, basic and bulk densities and calorific values. It will freeze; is very dusty, catches fire easily and is self-combustible. It can contain all manner of contaminants.  On the other hand, wood pellets are uniform in size and moisture content, are very free flowing, but are quite fragile and easily degrade and require special handling.” Continue reading →

BIOMASS DUST FIRE AND EXPLOSION CONTROL

Introduction

mill-1Fires have always been a problem in wood processing plants, particularly in those that handle dry material, including wood finishing plants, panelboard plants and wood pellet facilities; less so in sawmills. Historically, most sawmills in BC were accustomed to processing `green’ wood with moisture contents of 40 – 55%, wet basis.  While not unknown, fires were not a common experience with such wet wood, and explosions were unheard of. So, the fires and explosions in northern BC in 2011 and 2012, which resulted in the total destruction of two large sawmills, multiple deaths and injuries, is great cause for concern.  Everyone is asking, “What happened?” The relevant safety authorities are currently investigating both incidents and at this point in time, firm causes have yet to be identified. Continue reading →

BIOMASS STORAGE PILE BASICS

INTRODUCTION                                                                                    

With the current emphasis on biomass usage as a `green’ fuel for energy plants, it has become apparent that there is a need for understanding the requirements for storing biomass.  Woody biomass, called `hog fuel’, has long been utilized as a fuel in cogeneration plants at pulp and paper mills, where it was traditionally a waste product from the processing of clean white wood chips used to make pulp.  While many practical lessons have been learned about what is appropriate for hog fuel storage, generally little documented study has been directed at storage practices, primarily due to its abundance and historical status as a waste product with next to zero value.

However, hog fuel is the basic feedstock for biomass-fired power plants and is becoming a hot commodity and it is the single biggest on-going cost item for energy plants.  How it is handled has an effect on quality, so a greater understanding of hog fuel storage requirements is required. Continue reading →

CHIP / BIOMASS PILE INVENTORY MANAGEMENT

Where any bulk, raw resource is used in an industrial process, there is a requirement to track both usage and inventory.  And with the increased movement to utilizing biomass as a fuel source, more companies are discovering the difficulty in accurately measuring biomass inventory.

The traditional method of determining inventory has been to measure the volume of a pile and from that back-calculate the tonnage.  However, accurately determining the amount of fibre in biomass piles has long been problematic and even today with accurate measuring devices, fibre measurement doesn’t have an easy solution.

Pulp and paper mills everywhere have struggled with this problem for years.  One year they will have to write-off wood chip inventory that appears to have disappeared; the next year they will have too much inventory.  Other facilities that utilize biomass have similar inventory assessment problems.

Volume Measurement

Pile size and volume is measured by surveying and years ago the lack of accuracy was accepted and used to explain inventory variances.  With current measuring technology, the volume measurement accuracy has greatly improved and yet the estimate of actual fibre remaining in the pile is still not very accurate.  Generally, the problem lies with not knowing the amount of compaction and the consequent density inside the pile.  Without this knowledge, back-calculating tonnage from a volume measurement is quite `hit and miss’. Continue reading →

So you want to build a biomass plant

A Beginner’s Guide to the Project Development Process

Author: Paul Janzé

An editted version of this article appeared in the November / December 2011 issue of Bioenergy Insight magazine, under the title “Building a Biomass Plant”. http://bioenergy-news.com/

You have a good idea for a new way to manufacture a product.  Or, your friend has spotted a market opportunity.  All you have to do is build a plant and start producing.  “Build it and they will come.”  Sounds simple. How can you miss?

Easily, I must say.  The days are long gone when developing a project was as simple as pitching an idea to a bank, getting some cash, building a plant and selling your product.

With the current emphasis on producing `green energy’ from biomass and the subsequent government grants and subsidies available to promote the idea, a lot of well-meaning but inexperienced entrepreneurs are promoting the construction of plants that will process biomass into one form or another.

There are some basic steps that all projects go through, from concept to start-up, whether the `builder’ is new to the process or whether it is a company with a well formulated plan for development.  Following is a brief description of the project development process. Continue reading →