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
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 →
Are your chain conveyor sprockets wearing out quickly? The chains might be running in the wrong direction and contributing to excessive sprocket tooth wear.
Often, I have come across plants that are experiencing high-wear on their chain conveyor sprocket teeth, where the drive sprockets have become so worn and `hooked’ that they won’t release the chain cleanly. Following is a description of what is happening.
H-style conveyor chain links have an offset side-bar design with a narrow-end where the barrel attaches to the side-bars, and a wide-end where the side-bars fit outside and are pinned to the narrow-end of the adjacent link. See the following graphic.
Basic H-style chain can be run either narrow-end forward or wide-end forward, but the direction the chain runs makes a difference where wear occurs.
In North America, most woody biomass is transported by truck, whether it is logs, lumber, pulp chips, shavings, sawdust, wood pellets or wastewood / hog fuel. Trucks are versatile, plentiful, easily scheduled and economical over short distances. However, woody biomass is light and bulky and when transporting large volumes over long land distances, truck transport becomes costly; rail transport can be significantly less costly to use.
Transporting biomass by railcar has its challenges. Woody biomass takes many forms, shapes and sizes and can be a difficult-to-handle material, particularly getting it out of containers such as railcars.
Wood chip transport by railcar became popular in North America in the 60’s and 70’s with the determination that properly prepared sawmill residuals could be used for pulp chips. Several hundred specially designed wood chip railcars were constructed and most of these railcars are still in use today.
Pulp chips make up the bulk of woody biomass being transported by rail in North America. Pulp chips tend to be fairly uniform in size, but knit together after transport in box cars. And, the chip moisture content can vary significantly, which can be a problem in very cold climates. Wood chips will self-heat from biological action and oxidation if left to sit for awhile, and snow that might be sitting on top, melts and freezes at the bottom of the railcar.
Wood pellets are also transported by rail, more so as the world demand for pellets increases.
In BC, pulp chips and wood pellets are routinely transported hundreds of kilometers by rail from the BC interior to the ports in Vancouver and Prince Rupert for trans-loading onto ships. Continue reading →
Woody biomass has been used for hundreds of years as a fuel source, primarily as solid wood being burned in a fireplace or stove. For much of the 20th century, excessive waste residuals from forest industry facilities such as sawmills, were disposed of by burning in piles or `tee-pee’ burners. Even today, most logging residuals are unused and are disposed of by burning in slash piles. In the mid part of the 20th century, industry started to use their woodwaste as a fuel source for process heat and electricity (cogeneration / combined heat and power). Also, wood pellets started to be used as a domestic fuel in homes, primarily in Europe.
Climate change and global warming have become big topics in the last 20 years, and most scientists believe that mankind is a significant contributor to global warming, particularly through the use of fossil fuels. Recently, progressive governments committed to reducing their green-house gases (GhG’s) and are promoting and funding considerable research into finding sustainable, low-carbon energy sources. Governments have mandated the closure of coal-fired power plants and are looking for alternative fuels. Consequently in the last decade, the world `discovered’ woody biomass and is focusing on its use as a sustainable, low-carbon fuel or feedstock for bio-chemicals. Continue reading →
Recently, I have had several inquiries regarding the requirements for conveyor safety and guarding. There are many organizations that dictate safety requirements and provide guidelines for guarding, and it can be confusing as to which organization has authority. The end-user must know which apply in his area.
This article provides general instructions as to where information can be found regarding WorkSafe and OHSA requirements with regards to conveyors in BC, AB and ON. Also included are comments regarding general conveyor safety and guarding experience that the author has gained over the years. Continue reading →
Too often a client will want to jump straight from a preliminary project concept into construction, giving little thought or effort to project planning and engineering. Unfortunately, many of these ill-conceived projects are unsuccessful in their execution due to faulty or non-existent planning. To ensure a successful project, it is best to follow established front-end engineering and design (FEED) project development procedures that will give the client and his financiers confidence that the technical process is sound and the financial outcome has a good chance of being realized.
For a description of the steps that all projects go through from feasibility study, raw resource planning, securing a market, engineering, procurement, construction, commissioning and start-up, refer to the article titled “So You Want to Build a Biomass Plant, A Beginner’s Guide to the Project Development Process”, included elsewhere on this website.
Generally, it is recommended that all projects are set up to go through the following formalized development phases:
Pre-feasibility phase where a market opportunity is identified and rough costs and possible profits established.
Feasibility study phase, which considers various alternatives with Class 40 order of magnitude budget(s).
Definition phase, which includes development of a selected concept and Class 25 budget.
Detail engineering phase with AFE grade Class 10 budget.
Vendor documentation is required for equipment purchased as part of a project. It is very important information to have, if the equipment is to be designed, installed, operated and maintained safely and correctly.
Unfortunately, equipment vendors often don’t understand the contractor’s or end-user’s requirements and `scrimp’ on the quality and quantity of documentation provided with their equipment. Also, it is helpful if vendor documentation is provided in a format consistent with the end-user’s requirements. So, it is imperative when issuing requests for quotations (RFQ’s) to include the documentation requirements that the successful vendor will be expected to provide with their equipment.
Following are general instructions that should be included in RFQ documents, regarding:
Pulpmills are among the largest users of woody biomass and typically store and process huge volumes of wood chips prior to the pulping process. Storage volumes of 120,000 BDt (750,000 m³) are not uncommon. The value of these chips is in the tens of millions of dollars, so mills have very specific requirements for storing wood chips to minimize fibre losses and maximize fibre recovery.
Things to consider when designing chip storage piles include: the material being handled, total required storage volume, practical live-storage volume, fibre aging, pile turn-over, dry fibre loss, chip degradation and breakage, dust and fire control, inventory management, the methods of pile-building and reclaiming, etc. Continue reading →
This article has been the most popular and has received the most attention since I wrote it in 2011. I’ve done a couple of rock removal studies since then and decided the article needed updating with new information.
The upsurge of interest in biomass-fired power plants in the past few years is accompanied by a corresponding increase of interest in methods for removing non-combustible, non-organics such as rocks, stones, sand and grit from woody biomass. Rock contaminated woody biomass has long been a problem, and many ways have been attempted in trying to deal with it. The methods are varied, usually depending upon the end-use to which the biomass is being put. There are some specific methods that are very successful; others more a measure of how best to accommodate the problem.
Following is a brief description of the problems, solutions and accommodations that various biomass processing industries utilize when dealing with rocks and other non-organic contaminants in their woody biomass. Continue reading →
“Metrication in Canada began in 1970 and while Canada has converted to the metric system for many purposes, there is still significant use of non-metric units and standards in many sectors of the Canadian economy. This is mainly due to historical ties with the United Kingdom (before metrication), the traditional use of the imperial system of measurement in Canada, close proximity to the United States, and to public opposition to metrication during the transition period.”
This is a direct quote from an article titled “Metrication in Canada” on Wikepedia, but the emphasis in italics is mine.
46 years later in 2016, the measurement system is still a mixed bag, partly metric and partly imperial. And, everyone, including clients, engineers, other consultants, regulatory bodies, vendors, manufacturers and contractors all interpret the measurement designation requirements differently, and if not controlled can wreak havoc with a complex project. Continue reading →
It has been well documented that a Kraft wood pulp digester fed with a uniform chip size and a controlled volume of pins and fines provides a measurable improvement to the pulping process and pulp quality. Chips less than 7 mm thick pulp more completely than thicker chips, giving a uniform raw material for easily controlled pulping and bleaching. Additionally, removing the `pins’ and `fines’ from the digester feed improves operating performance.
Chip thickness screening (CTS) is a wood chip segregation and conditioning process that removes the overthick chips from the chip furnish and processes them either by slicing or crushing so that they can be uniformly cooked along with the screen accepts.
Most mills recognized the benefits of CTS in the early 1990’s and installed CTS systems; however, there were significant technological advances in the late 1990’s that many mills missed and still have not upgraded their equipment to the latest, most efficient technologies.
Although the actual pulping process improvements resulting from the application of CTS may vary from mill to mill, generally improvements can be found in the following areas:
Improved wood utilization.
Increased digester maximum production.
Decreased digester alkali application.
Recovery boiler solids reduction.
Increased chip screens system availability.
Less mechanical damage due to foreign materials such as rocks.
This article provides a brief description of the CTS process and summarizes the potential benefits. For excellent reference papers on chip thickness screening and the benefits, see the references included at the end of this article. Continue reading →