Maintaining the correct level of oxygen is vital for combustion optimization. Too much excess oxygen will decrease efficiency. This article discusses how ABB is helping Twence optimize combustion in their waste-to-energy plant in the Netherlands.
Image Credit: ABB Measurement and Analytics
For more than two decades, Twence has been a market leader in harnessing raw materials and energy from waste. The company, operating in the eastern Dutch province of Overijssel, manages biomass power plants, separation plants, and waste-to-energy plants.
Each waste stream follows its own particular process. Twence is committed to innovative technologies and has recently constructed a carbon capture plant to capture carbon dioxide (CO2) from the flue gas produced during energy generation from waste incineration, reusing it in liquid form as a new raw material.
Returning as much raw material and energy as possible back into society is Twence’s goal. However, sustainability is not something the team can achieve alone.
Twence works with municipalities, businesses, and partners to make the entire region greener and contribute to sustainability goals as much as possible.
Oxygen Measurement in Harsh Environments
Energy recovery from waste involves converting non-recyclable waste materials into usable heat, electricity, or raw materials via various processes, including gasification and combustion. Twence employs the combustion method.
Plant operators must continuously monitor oxygen concentrations to operate the combustion process efficiently and safely. Maintaining the appropriate oxygen levels through precise and rapid measurement is essential for optimizing combustion, as excessive oxygen can lead to decreased efficiency.
At Twence, oxygen levels are measured at multiple points in the process using combustion gas oxygen analyzers. These analyzers utilize in-situ zirconium sensors that gauge oxygen concentrations by being inserted into the flue gas generated during waste incineration.
In addition to delivering reliable oxygen readings, the analyzers must endure the harsh conditions of the combustion process, resisting thermal and mechanical vibrations, shockwaves, corrosion, and high sulfur environments.
The shock pulse generators employed by Twence to clean the boiler system of fly ash further complicate the environment, as these generators create small explosions during the cleaning process.
View of a shock pulse generator at Twence. Image Credit: ABB Measurement & Analytics
Superior Combustion Gas Oxygen Analyzers at Twence
The team at Twence has previously encountered analyzer breakdowns. They recognized that returning the oxygen analyzers to the manufacturer for repairs or fixing the faulty units in the field was challenging and costly.
In one instance, a zirconium sensor was replaced only to require replacement again the following day after the shock pulse generators were used.
Twence is actively seeking superior analyzers that can withstand extreme conditions while providing accurate and reliable oxygen measurements.
Endura AZ20
In 2018, Twence began a trial with ABB's Endura AZ20 combustion gas oxygen analyzers.
The first Endura AZ20 was placed at the boiler system outlet. This position was the most challenging due to uncleaned stack gas.
ABB’s Endura AZ20 employs a thick piece of zirconium coated with porous platinum. The robust design ensures resistance to thermal and mechanical stresses as well as gases such as sulfur.
Twence immediately noticed improvements in the hardware, readings, and entire waste-to-energy system’s performance.
The Endura AZ20 did not require regular calibration as the analyzers indicated minimal drift.
Twence now reports that its Endura AZ20s perform as needed without malfunctions. Over the past seven years, no defective Endura AZ20s have been reported, even in the harshest measuring position.
The AZ20 in operation at Twence. Image Credit: ABB Measurement & Analytics
Innovative and Dependable Analyzers
Engineered to improve combustion efficiency while providing accurate oxygen measurement, the Endura AZ20 proved a perfect fit at Twence.
Arjan Meerveld, ABB Measurement & Analytics said: “Behind the Endura AZ20 are decades of field experience and prudent research. The Endura AZ20 was created for accurate and reliable oxygen measurement in harsh conditions exactly like those at Twence.”
The AZ20 in normal operation displaying the value (5.9 Vol.% O2). Tag number and health status of the Zirconium sensor (displays optimal three digits - see area in red. Image Credit: ABB Measurement & Analytics
The AZ20 displaying the “as found value” on 12 June 2024: 0.28 mV. Showing the difference in reading at the previous calibration: +0,04 Vol%, 64 days and 1 minute earlier. Image Credit: ABB Measurement & Analytics
Removal of the Zirconium sensor from the probe. Image Credit: ABB Measurement & Analytics
This information has been sourced, reviewed and adapted from materials provided by ABB Measurement & Analytics.
For more information on this source, please visit ABB Measurement & Analytics.