NOx gases comprise highly reactive compounds, mainly nitrogen dioxide (NO2) and nitric oxide (NO). They are byproducts of various industrial processes, in this case, stemming from an arsenic acid reactor used in the production of wood treatment chemicals. These gases contribute to air pollution, leading to smog formation, acid rain and pose a significant threat to respiratory health.

In 2021, Koppers initiated a project to upgrade their Wiri production facility. Pressure Worx had previously provided a heat exchanger for their existing plant and collaborated with Koppers and their engineering consultants at AECOM to design a larger uprated heat exchanger for the project. The project also required a new updated NOx scrubbing system. Leveraging Pressure Worx’s extensive experience in biogas scrubbing worldwide, we were initially contracted to support and review the Koppers/AECOM process, providing mechanical design services for the system. This collaboration ultimately led to the award for the manufacture and supply of five large stainless steel scrubber vessels, in addition to the uprated heat exchanger, in late 2022.

In the emission reduction process, NOx gases generated from the arsenic reactor enter Pressure Worx’s 3-meter-long stainless-steel shell & tube heat exchanger cooling the gas before it enters the multistage scrubbing tower solution. This consists of five scrubbing towers, each with a 1.2-meter diameter and heights of approximately 11 meters, connected in series. Inside the scrubbers, a series of chemical reactions occur, neutralizing and removing the harmful NOx gases from the exhaust stream.x

Pressure Worx provided the scrubbing towers, complete with stainless steel internals (liquid and gas distributors, packing supports, and hold downs), ceramic random packings, quick-release inspection/service manways, and handholes. Additionally, Pressure Worx designed and supplied the level transmitter chambers and manufactured the in-ground foundation steelwork and stud bolting to ensure a seamless installation on-site.

Pressure Worx successfully delivered all the equipment to Koppers’ Wiri site on schedule in August 2023. They now proudly stand as part of Koppers’ newly upgraded Wiri process facility, another milestone in New Zealand’s environmental efforts.

NOx scrubbing system

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The ISO9001:2015 recertification underlines our continuing commitment to delivering quality products and services to our customers.

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Biogas cleanup

The first part of the process involves the cleanup of the biogas produced from the water treatment facility to remove contaminants such as Hydrogen Sulphide (H₂S) and various Siloxanes.  Pressure Worx designed and supplied two sets of gas scrubbers, one set for the H₂S removal and the other for the siloxanes. 

Pressure Worx provided lead-lag siloxane scrubbers using specifically formulated carbon adsorption media in our 3.7m high GRP/polypropylene lined vessels.  Our H₂S scrubbers use a granular iron oxide scavenging material, also in a lead-lag configuration of 3.5m high vessels. The four white scrubber vessels can be seen in the above photo at the left most edge of the site.

The main benefits of the lead-lag configuration are twofold.  Maintenance teams can change the media on the lead scrubber while the lag scrubber remains on-line, meaning no down time.  Furthermore, operators can ensure that the lead scrubber media is fully spent (utilised) before change out, with the lag bed providing a safety net against break through.

Screw compressor packages

After the scrubbers and as part of the front end of the process, Pressure Worx supplied three gas compressor packages on various biogas and hydrogen rich duties.  We selected oil flooded screw compressors in self-contained units from Adicomp as the ideal solution for Hazer’s CDP.  Adicomp is a leading global supplier of biogas screw compressors and Pressure Worx is proud to represent them across Australasia.  The partnership enables us to specify packages for local conditions and standards but manufactured with Adicomp’s extensive experience at their comprehensive facilities in Italy.

The target commissioning date for the Hazer Commercial Demonstration Project is Q1 2022.  A green hydrogen future awaits!

Three compactly designed and enclosed screw compressor packages were supplied to site with control systems complete with variable speed drives to optimise control and energy efficiency.

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Following a call with the team and a briefing to describe what was required, our engineering team got together to design a solution. Time was critical and we quickly realised the solution had to use readily available piping components to build the elevator autoclave.

The AC75 elevators connect to the bottom of the rudder at the back of the boat.  They control the boat pitch and need to be really strong, so they’re made from a fast curing pre-impregnated carbon fibre laminate. The autoclave increases both the temperature and pressure during the carbon fibre curing process.  The result is that the consolidated laminates ensure the highest quality and strongest uniform elevator blades.

Our specialty autoclave design called for a cylinder with flanged, removable covers for ease of operator access during lamination. Within a week, we built and tested the autoclave at our Auckland factory before we delivered it down to Emirates Team New Zealand’s workshop facility.

Team NZ appreciated the fast turnaround, design skill and quality product.  Just a few weeks after delivering the elevator autoclave they contracted us again, this time to test and certify the hydraulic tank used on board Te Rehuai.  These system critical components are crucial to the efficient working of the boat.  The systems worked without a glitch and we were all greatly relieved when the Americas Cup was locked back in its case at the Yacht Squadron in Westhaven for another few years!

We’re pleased to have had the opportunity to work with Emirates Team New Zealand and be involved, in even a small way, to making their defence a success.

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Our thermal design team analysed the rocket exhaust process data and then designed a specialty heat exchanger to meet the Rocket Lab design brief.  As result, Pressure Worx specially developed a number of notable features for the exhaust condenser.  We included a condensate impingement separator and collection sump within the exhaust outlet bonnet.  “We had to analyse over 29 different and complex rocket operating cases to come up with a heat exchange solution that would meet all of them”, said Rowntree.

Exhaust gas from the rocket enters the stainless flange at the right of the exhaust condenser

Following the successful design and delivery of the Rocket Exhaust Condenser, Rocket Lab asked us to design and supply a Spray Chamber Vessel, also fitted to the exhaust.  This vessel saturates the exhaust and cools the stream prior to the rocket exhaust condenser.  Furthermore, it works under vacuum and was fabricated entirely from stainless steel.

“We loved working with the engineers from Rocket Lab and its awesome to be involved in just a small way with helping develop their test facility to enhance their rocket performance for future missions into space. They are an innovative and exciting company, proud of their New Zealand origin”.

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We manufacture replacement upgrades of older units including legacy Flotech and Greenlane Technology units for which we have historic project information and direct replacement units available. The direct replacements are dimensionally equivalent and can slide straight in with no changes to the existing piping. Our specialist thermodynamics designers can also replace existing fixed tubesheet designs to floating tubesheet, bellows or U-tube designs, to better accommodate the thermal expansion often seen in hot water and CIP heat exchanger applications.  Construction materials are typically stainless steel 316 or Duplex (SAF2205) and we can provide hygenic design for food grade applications. Stainless steel heat exchangers are finished with electro-polishing.

For difficult site layouts, we customise our standard designs, tailoring the layout, orientations and connection sizes to suit the particular site installation requirements. We stock key components and can offer rapid delivery when required.

Pressure Worx provides the most energy efficient, robust and cost effective heat transfer solutions for our clients. Please contact our sales team on sales@pressureworx.co.nz  to discuss your hot water and CIP heat exchangers requirements.

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Options include power generation with gas engines or microturbines and both are widely used to generate electricity either to support local electricity needs or to feed into the local grid.  Microturbines offer minimal moving parts, low maintenance, low noise and vibration and where there’s a nearby application for the heat generated by the microturbine, this meaningfully supports microturbine project economics.  However both microturbines and gas engines require LFG to be cleaned up before use.  Gas engine manufacturers typically require the high H2S content in LFG to be removed or reduced and siloxanes in newer landfills damage gas engine components and lead to excessive maintenance costs.  Microturbines often require complete removal of siloxanes prior to combustion to avoid early failure of expensive turbine components.

Pressure Worx have developed a variety of gas conditioning and biogas clean up solutions. We find no two sites are the same and biogas constituents will vary depending on many factors including the type and mix of organic waste. We can help you with designing and supplying a gas conditioning or clean up solution to match your raw biogas and meet the specifications for your end use requirements.

Another option for LFG is to use it in gas fired boilers.  While this comes with some challenges, the gas cleanup requirement prior to combustion is reduced.  Landfill gas emerges with variable pressures, volumes and methane content during a day and over time and boilers on LFG need to include gas trains designed and sized to accommodate this variability.  Combustion controls can provide for in operation adjustments for fluctuations in the LFG composition.  A well-designed LFG fired gas boiler installation provides stable heat for many applications, especially when combined with a LNG fuel train.  In some critical applications, dual gas trains with LFG and LNG options can allow uninterrupted operation.  Pressure Worx can offer custom designed dual gas trains for your requirements.

Contact us at sales@pressureworx.co.nz if you want to talk about your waste to energy project to better utilise biogas on your landfill.

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Different products and processes require different types of CIP systems. Single use and dump systems are often installed where there is a large amount of fouling due to product deposits and high chemical oxygen demand (COD) levels make them unsuitable for re-use systems. Reuse CIP systems typically have a dilute chemical supply tank and a post rinse recovery tank used for the next pre-rinse. Both types of systems require critical temperature control to prevent product spoilage and to increase its dirt removal efficiency.

At Pressure Worx, we understand both the process of CIP systems and the requirements of the heating systems for CIP temperature control for water and cleaning agents. We custom design heat exchangers and heating systems with either an in-line heater for each cleaning circuit or a re-circulated kidney type heater for each chemical supply tank or water recovery tank. In both cases, the cleaning agents will be heated to the proper temperature.

Capacity and pressure requirements in CIP systems vary dramatically, so we custom design heat exchangers for your specific CIP system requirements. Whether a single pass heat exchanger with a fixed tubesheet, a multi-pass design with a floating tubeplate, or u-bundle design, we can provide the most economical and reliable heat exchanger design to meet your CIP systems requirements.

For more information on how we can help with your CIP systems, please don’t hesitate to contact us at sales@pressureworx.co.nz

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Hydrogen Sulphide (H₂S), more commonly known as ‘rotten egg gas’ is an essential gas used in the production of Nickel. The gas is produced by reacting molten liquid sulphur with hydrogen in a reactor. The refinery produces 225 tonnes per day of H₂S for its Nickel production.

“Pressure Worx won a contract to design and supply the H₂S Cooler in Madagascar, having considerable experience and reputation in the design and supply of similar heat exchangers for Nickel plants around the world”, said Steve Rowntree, director at Pressure Worx.

The H₂S cooler, cools the gas down in the shell of the unit. Residual sulphur within the gas solidifies on the outside of the water cooled U-tubes during the cooling process. Over time this results in a restriction of the gas flow and a reduction in cooling performance. “The Pressure Worx design incorporates a special shell jacket, that periodically allows the operators to inject low pressure steam around the outside of the shell, melting the sulphur build up which then drains to a separate blow down vessel, allowing the performance of the cooler to return to new” reported Rowntree.

The H₂S cooler was designed by Pressure Worx in Auckland. High temperature stainless steel grade SS310s was used for the tube bundle design, providing excellent resistance to corrosion and oxidation at elevated temperatures. Non-destructive testing (NDT) including both X-rays and dye pen testing was carried out on all welds in direct contact with the H₂S gas due to ensure their integrity with the highly toxic gas. Fabrication, testing and certification of the unit was carried out in Auckland.

“It’s great to see that NZ companies can still compete globally on the world stage with clever design, IP and competitive specialist fabrication” said Rowntree. “We are currently developing other specialised heat exchange equipment designs as well as a range of biogas and landfill gas conditioning systems to improve the efficiency and reliability of renewable gas power gensets around the world.”

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