Authors: Heather Higgins, Will Russell and Uday Parekh, Blasch Precision Ceramics, USA
There has been a steady decrease in skilled labourers in the US in recent years, including bricklayers in the refractory ceramic industry. Skilled labour falls into one of two categories: highly skilled (such as scientists and engineers), or those with middle skills, requiring a high school diploma and less than a four-year degree. It is those with middle skills that are lacking in the construction industry, which is having a direct impact on the rate of project completion. Plant operators are often forced to either extend their outages to ensure that all of the planned work is accomplished or complete less of the maintenance than originally planned during turnarounds.
Several new technologies require skills that are not yet taught in schools. This gap in training requires companies to provide more on-the-job training that is specific to their process, and not necessarily transferable to another company.
As many schools discontinue vocational training and the current generation retires from skilled labour jobs, it is becoming more difficult to fill these positions.
In 2012, the US Department of Labor announced over US$175 million in funding for community colleges to grow and enhance their manufacturing education and training programmes.1 The skills gap is a very real phenomenon being experienced in American manufacturing today. The Manufacturing Institute reports that “over the next decade, nearly 3.5 million manufacturing jobs likely need to be filled and the skills gap is expected to result in 2 million of those jobs going unfilled.” MFG Day is now held every year in the US on the first Friday in October to celebrate modern manufacturing and inspire the next generation of manufacturers.
Figure 1. Typical Blasch HexWallTM installation.
Many organisations are using education to help bridge the skills gap. SkillsUSA works to put programmes in place with students beginning in middle school. These programmes utilise STEM (science, technology, engineering and mathematics) education and hands-on learning techniques to inspire students to move into fields relating to mathematics and science, encouraging some to consider skilled labour careers.
The refractory ceramic industry
A Certificate of Qualification in Brick and Stone Masonry, which is often required by employers or unions for refractory installations, can take 4300 hrs of apprenticeship and a written examination to earn.3 The US Department of Labor reports the number of apprentices in the US dropped from 488 000 in 2003 to 287 000 in 2013.4 The labour shortage is a real problem for construction companies, and market forecasts suggest that this will only get worse in the future. With all of these factors at play, along with more unpredictable, market-driven turnaround schedules, refractory installers must utilise technologies efficiently to shorten turnaround times and decrease the amount of skilled labour required to install structural refractory components.
Blasch Precision Ceramics works with installers to develop technologies that decrease the total number of skilled labour hours required to complete field refractory work. Instead of creating structures using traditional brick and mortar, precast ceramic shapes are designed and manufactured using proprietary material and unique technologies to create mortar-free, structurally stable, freestanding walls for a variety of applications across various industries. In these Self‑Supporting Structural Ceramic Systems (S3CSTM), each block has precast interlocking features to ensure interaction and to provide support to its neighbouring structures. This creates a self-supporting structure that is constructed by simply stacking blocks on top of one another, reducing the labour requirement without the use of mortar between structural parts. Overall benefits from these designs include faster installation and longer timespans between replacement compared to traditional systems, thus providing improvements in overall uptimes for critical units in the refining and chemical industries.
Figure 2. VectorWallTM installation with mortar free joints and vectoring hoods in place.
One field labour-saving solution is the Blasch HexWallTM. This mechanically stable system consists of a series of stackable six-sided blocks with alternating tabs and slots on each side (Figure 1), designed to lock together at installation. This system is used as a replacement for traditional refractory brick walls in reaction furnaces, such as those found in claus sulfur recovery units (SRUs), and is offered as a simple, mechanically robust and readily tailored solution.
The VectorWallTM is a mixing HexWall, altering the reactant flow path, which creates significant mixing within the chamber of a reaction furnace and maximises the use of the available volume (Figure 2). Its large hexagonal ceramic blocks are inherently stable and structurally supported.
Figure 3. Representative StaBloxTM tunnel.
These walls break the furnace into two zones, and both are used in SRUs and sulfuric acid plants. The latter system has allowed operators to increase the operating efficiency and throughput of thermal reactors, and is able to increase the temperature in zone one of the furnace, which enhances reaction kinetics and the destruction of contaminants that would otherwise cause fouling downstream, reduce run lengths, and thereby increase the frequency of labour intensive turnarounds.
The tube sheet in combustion processes between the furnace and waste heat (recovery) boiler can have a temperature difference of greater than 1000˚C between the hot furnace and cooler boiler side. The tube sheet is protected from failure and costly downtime by ferrules, which mitigate the impact of the large temperature gradient. Blasch’s boiler tube ferrules are pre-engineered for each boiler tube installation. They are properly sized, accurately molded, and completely wrapped with all required fibre insulation. Castable refractory is not necessary between the ceramic ferrule, and only a minimal amount is required around the periphery, resulting in large savings in the time required for installation and curing.
Furthermore, by separating the ferrule head and stem, the company’s two-piece ferrules remove stress from the concentration point where the two connect in a one-piece design, enabling enhanced thermal expansion tolerance.
The company’s flue gas reformer tunnel system (StaBloxTM) consists of a series of stackable, interlocking blocks (Figure 3). These blocks are rectangular and have notable engagement features keeping the blocks in place. Each block is roughly six times the size of a traditional refractory brick, and weighs under 50 lbs. With traditional refractory brick, a skilled installer has to construct expansion joints at a predetermined distance, typically every 6 ft of tunnel length, yet this system accommodates for thermal expansion with the design of each individual block and installation procedure.
The customisable blocks and mortar free expansion joints offer a higher level of reliability. They can be used to form tunnels in high heat or corrosive applications. Ease of installation and the improved run lengths of the steam methane reforming (SMR) process can result in substantial labour savings over the typical 15 – 20+ year life of the plant.
Case study
A custom design for the oil refining industry, installed by J.T. Thorpe & Son Inc., was created for use in a carbon monoxide (CO) boiler consisting of a rectangular furnace with six large burners protruding through the ceramic wall. These boilers are used to oxidise CO-rich waste gases that are generated in petroleum refineries. The customer’s wall was originally constructed of refractory brick that had suffered severe degradation over the years. Blasch worked with the customer to design a series of square bricks, as well as six sets of ring segments to surround the burners. The ring segments were to have holes for additional tubes coming off of the large burners, as well as pluggable holes to allow for a change in the amount of airflow when necessary. This change in airflow allows for a more tightly controlled temperature and an opportunity for additional mixing by causing additional turbulence. All of this was made possible with precast shapes that fit together using tongue and groove systems.
With the old brick and mortar refractory system, it would have taken three weeks to have a wall of this size built. However, this solution took just five days. Once constructed, the wall was a freestanding, fully supported structure within the furnace. The use of mechanical design to keep components positively engaged, while allowing them to thermal cycle without damage, is key to the success of these structures. Repeated thermal cycling cracks the typical mortar that is used to hold traditional bricks together, and failure (often in the form of a partial or complete collapse) soon follows. Structures of this kind should not be permanently cemented together. They need to be able to move and grow to relieve stress and increase refractory life.
Applications
The SRU plays a critical role in helping produce clean end-products (such as gasoline, diesel, jet fuel, heating oil, natural gas, etc.) from petroleum refineries and gas processing plants. It is critical that SRUs have very high uptime/availability since they often support multi-billion-dollar facilities. Thus, the components in the SRU reaction furnace must be robust, have long run times between turnarounds and be quick to install. The systems described in this article provide these benefits and help reduce the total field installation time required for these key components in SRUs.
Sulfuric acid is one of the most widely manufactured chemicals in the world, with production in the US and globally standing at over 35 million tpy and 250 million tpy, respectively. The largest use of sulfuric acid is for the manufacture of fertilizers. Another important use of Blasch’s products is in the regeneration of sulfuric acid, used as a catalyst in the alkylation process. Alkylate, the product from the alkylation process, has high octane and low Reid vapour pressure (RVP) and sulfur content. These qualities make alkylate a particularly prized blending component and key constituent for today’s clean burning gasoline. In sulfur burning and sulfuric acid regeneration, the reliability and uptime of the sulfuric acid reaction furnace is of great importance and is facilitated by the deployment of VectorWalls.
Hydrogen, ammonia and methanol are important chemicals/feedstocks in the petroleum refining, fertilizer and petrochemical industries that are manufactured via the steam methane reforming (SMR) process. Conventional flue gas reformer tunnel systems have relatively poor structural reliability. Damage to these tunnels can also result in changes in flow patterns in the SMR, reduced conversions, preliminary tube failures and time intensive and costly repairs. The StaBlox tunnel systems offer significant time savings and increased process uptimes through enhanced speed of tunnel construction and reduced downtime.
Conclusions
The skills gap in the US significantly impacts the ability of businesses to meet existing customer demand, let alone achieve future growth and profitability targets. With a shortfall of 2 million workers anticipated in the coming decade due to the shortage of workers with adequate STEM skills, industry growth and the acceleration of baby boomer retirement, manufacturers, schools and community colleges, communities, as well as local and federal government are all focusing on how to close this gap.
These efforts can be supplemented by the innovative design and engineering of products that improve ease and speed of installation, as well as provide maximum run-times between replacements, all geared towards significantly reducing the total skilled field labour requirement per unit of cumulative plant production in critical industries such as energy, chemicals and fertilizers, which touch everyday lives.
References
- ‘$175 Million in Funding Announced for Manufacturing Education Programs – September 20, 2012’, Manufacturing Institute, (20 September 2012) https://www.themanufacturinginstitute.org/ News-Articles/2012/09/20-DOL-TAACCCT-Announcement.aspx
- ‘The skills gap in U.S. manufacturing 2015 and beyond’, Deloitte, https://www.themanufacturinginstitute.org/~/media/827DBC7653394 2679A15EF7067A704CD.ashx
- ‘What Does a Refractory Mason Do?’, https://www.apprenticesearch. com/AboutTrades/GetTradeDetails?tradeId=280&TradeName=refractory-mason
- ‘Registered Apprenticeship National Results Fiscal Year 2013’, United States Department of Labor, https://doleta.gov/oa/data_ statistics2013.cfm
