How ABB is helping optimize combustion at Twences waste-to-energy plant

How ABB is helping optimize combustion at Twence’s waste-to-energy plant

Maintaining the right level of oxygen is crucial for combustion optimization. Too much excess oxygen equals decreased efficiency. Read more about how ABB is helping Twence optimize combustion in their waste-to-energy plant in the Netherlands.

Operating in the eastern Dutch province of Overijssel, Twence has been a leader in the business of harnessing raw materials and energy from waste for more than two decades. The company operates separation plants, biomass power plants and waste-to-energy plants. Each waste stream has its own specific process. Committed to innovation and new technologies, Twence recently built a carbon capture plant to capture CO2 from the flue gas associated with the generation of energy from waste incineration, reusing it in liquid form as a new raw material.

Twence’s goal is to bring as much raw material and energy as possible back into society. However, for the team, sustainability is not something they can do alone. Instead, they work with municipalities, businesses and partners to make the entire region greener and make a significant contribution to sustainability goals.

Accurate and reliable oxygen measurement in harsh environments

Energy recovery from waste is the conversion of non-recyclable waste materials into usable heat, electricity, or raw materials through a variety of processes, including gasification and combustion, the latter being the method used at Twence.

To run the combustion process efficiently and safely, the plant operators must control oxygen concentrations at all times. Maintaining the right level of oxygen through accurate and rapid measurement is crucial for combustion optimization. Too much excess oxygen equals decreased efficiency.

At Twence, oxygen is measured at various points in the process with the help of combustion gas oxygen analyzers. The analyzers rely on in-situ zirconium sensors that measure oxygen concentrations through inserting the sensors in the flue gas generated during waste incineration.

In addition to providing reliable oxygen readings, the analyzers must withstand the harsh conditions of the combustion process, resisting thermal and mechanical vibrations, shockwaves, corrosion, as well as high sulfur atmospheres.

The shock pulse generators used by Twence to clean the boiler system from fly ash make the environment even more challenging as the generators induce small explosions in the cleaning process.

View of a shock pulse generator at Twence

Need for superior combustion gas oxygen analyzers for Twence

The team at Twence had experienced analyzer breakdowns in the past. They knew that sending the oxygen analyzers back to the manufacturer for repair or fixing the faulty analyzers in the field was challenging, costly and time-consuming.

In one case, a zirconium sensor had just been replaced and it had to be replaced again the next day once the shock pulse generators had been used.

Twence were on the lookout for superior analyzers that would be able to withstand extreme conditions, as well as provide accurate and reliable oxygen measurement.

Endura AZ20: The accurate and reliable analyzer for harsh environments

In 2018, Twence started a trial with ABB's Endura AZ20 combustion gas oxygen analyzers.

The first Endura AZ20 was positioned at the boiler system outlet, the point that had proven the most challenging because the sensor was located in the uncleaned stack gas.

ABB’s Endura AZ20 uses a thick piece of zirconium coated with porous platinum. The robust design guarantees resistance to both thermal and mechanical stresses as well as to sulfur and other gases.

From the moment Twence turned to the Endura AZ20, they noticed improvements in the hardware, the readings, and in the entire waste-to-energy system’s performance.

The Endura AZ20 also did not need regular calibration because the analyzers showed minimal drift.

Today, Twence report that their Endura AZ20s are performing as needed without any malfunctions. In seven years, they have not had any defective Endura AZ20s, not even in the harshest measuring position.

The AZ20 in operation at Twence

Innovative engineering and dependable analyzers

Engineered to improve combustion efficiency while providing accurate oxygen measurement, the Endura AZ20 was a perfect fit for Twence.

“Behind the Endura AZ20 are decades of field experience and prudent research,” said Arjan Meerveld, ABB Measurement & Analytics. “The Endura AZ20 was created for accurate and reliable oxygen measurement in harsh conditions exactly like those at Twence.”