Published:  30.6.2021

The technology company Digita Ltd, district heating valve manufacturer Vexve Oy and iProtoXi Oy, a provider of comprehensive IoT solutions, have together started the digitalisation of district heating and cooling networks.

“The new iSENSE product family consists of smart monitor solutions developed for measuring the variables of district heating and cooling networks. The variables are measured directly from the underground pipe network”, Vexve Product Manager Riina Lahti says.

The variables of the district heating network, such as pressure and water flow, have not previously been measured from the underground network. Measurements related to leak monitoring have been carried out manually on site. Since the data collection has required transitions and working hours, measurements have been taken relatively infrequently.

“Pressure, temperature and flow values are readily measurable at power plants and pumping stations. In contrast, very little data is available from underground district heating networks. In many cases, operations rely only on rough estimates and data collected by manual measurements”, says Business Development Director Jari Randell from Vexve.

The new district heating valve solution allows all variables to be monitored in real time, as the data collected using IoT technology is automatically transferred to a cloud service.

Diversity as a challenge and strength

Developing a new kind of technology has not been so simple. In the cooperation, Digita is offering a LoRa-based (Long Range) IoT network (Internet of Things) as the basis for the solution.

“Our IoT network is especially well-suited for sending and receiving small amounts of data over long distances in an energy-efficient way. Our network’s strength is good coverage even in challenging conditions. This is precisely why the IoT network is an ideal solution for monitoring the underground district heating network”, says Sales Director Mika Flinck from Digita’s IoT business.

“Digita has made it possible for information to travel. We are cooperating with our other partner, iProtoXi, on cloud service and device manufacturing”, Randell says.

The fact that all the companies have different areas of special expertise has been a challenge of its own. Vexve specialises in district heating valve solutions and iProtoXi in solutions applying IoT technology, while Digita is a company that specialises in wireless communications networks. However, flexibility has gone a long way.

“There are many aspects to the development of this kind of a product family. We need one another. Even though we do not always speak the same language, we want to learn from each other. I think we have succeeded well in that”, Randell says.

From platform to customised solution

iProtoXi, which focuses on industrial IoT solutions, brought its own Aistin platform to the project. It was developed to support faster and more sustainable implementation of customer solutions and comprehensive systems.

“We have a ready-made platform that includes a device platform and cloud service, electronics and software. We customise the platform into a solution that meets the customer’s needs”, iProtoXi Sales Director Juha Ryynänen says.

The solution developed by Vexve is called the iSENSE product family. The solution includes devices and a cloud service.

“The cloud service can be used to manage devices and change some parameters. The device software can also be updated remotely if needed”, Ryynänen says.

The secure platform utilises the latest technology. The flexible solution can be integrated with the customer’s other software and systems. As it gradually expands, the solution will further reduce surprises in the operation of the district heating network, making energy supply more efficient and predictable.

“For example, when one more pumping station is added to the district heating pipe network, it can affect the flow direction and thus the efficiency of the network. By measuring variables, such changes are detected immediately”, Lahti says.

The most important function of the automatic monitoring of the district heating system is predicting the condition of the piping and the operation of the system. The first pilot devices were installed in real network conditions in September 2017. The project was carried out with good results, after which the final device was productised. Monitoring provides stability for both district heating companies and their customers.

The basic principle of the network is a steel pipe in which the district heating water flows. The pipe also has an insulated protective cover. The iSENSE device, in turn, is located in a well with a valve and belonging to the district heating network. Sensors measure both pressure and water temperature from the valve and pipe. In addition, the device measures the conditions in the well and moisture in the pipe’s cover insulation.

“Moisture in the insulation indicates that either the pipe is leaking or moisture is entering the insulation from somewhere else. A pipe leak is of course the worst thing, but moisture in the isolation can also cause corrosion and rust the pipe”, Lahti says.

Ryynänen emphasises that several development rounds and the pilot phase have ensured that the iSENSE system operates independently underground.

“The device harvests energy from the piping through a separate harvester. The device also has battery backup in case the harvester is not enough. We have calculated that the device will operate independently without maintenance for at least two years”, iProtoXi CEO Janne Kallio says.

Finland is at the forefront of the digitalisation of district energy valves, and iSENSE solutions have already been delivered to several European countries.

“We have made changes to the cloud as software support, but otherwise the same device works there as well. We have not yet found any international competitors”, Kallio says.

Device prevented major damage

About one year ago in April, an iSENSE device reported a possible network leak. Since the network in that area had just been built, a leak was unlikely.

“However, a main pipe with a diameter of 600 millimetres that had almost rusted through was found 900 metres from the device. The cause was a leaking protective cover of the district heating pipe”, recalls Randell, who has worked with district heating valves for 30 years.

A leak in the protective cover of a district heating pipe does not yet mean that the pipe itself is leaking. However, moisture accumulated under the cover causes corrosion on the surface of the steel pipe. As this corrosion progresses, over time the pipe will also start leaking.

Since the cover leak was detected by pulse measurement, the exact location of the pipe requiring repair work was known. Accurately locating a leak is important as it saves both working hours and other total costs.

“There is a district heating network connection line more than five kilometres in length at the site where the leak was detected. The estimated cost of repairing the entire section was several million euros. The price of the iSENSE system, on the other hand, was less than 0.4% of the total cost”, Randell says.

Extensive repair work was avoided thanks to the iSENSE solution. The leak site was located and repaired by the contractor during the warranty period of the pipeline. Similar leaking pipe covers are found throughout the networks. The pipelines of the networks are made up of pipes measuring 6–18 metres in length. Connecting the pipes to each other creates joints in the pipelines that are potential leak sites. A five-kilometre pipeline with supply and return pipes will have several joints. With several joints, the risk of protective cover leaks increases.

“The leak would not have come to light without the system. Groundwater in the area is high, so the pipes are underwater in many places throughout the year. In addition, groundwater is challenging in Finland, as the streets are salted in winter. So the water is not fresh water, which further accelerates corrosion”, Randell says.

As the contractor carried out repair work, more leaks were found in the pipeline cover. Repairing one leak requires both machinery and labour. The work can take several days.

Investing EUR 15,000 in a monitoring system is a small sum compared to millions in repairs. In the case of this particular leak, many costs were also avoided because the pipeline had been built recently.

“It was fortunate that the fault was detected during the warranty period of the pipeline. Without iSENSE, the leak could have been discovered years later. By then there would have been a leak in the pipe too”, Randell says.

According to Randell, it is typical for leaks in the district heating network to occur at the worst possible time. Usually when the need for heating is greatest in the winter. The biggest leaks can even be detected by a random dog walker, as the entire street may be covered with water.

“On the other hand, leaks in the protective cover of the pipeline are not detected in time. This means that the leaks also result in costs. Customer billing is lost and more water has to be pumped into the pipeline”, Lahtinen says.

With a better understanding of how the network works, it is possible to optimise energy use and improve customer satisfaction. Network reliability is improved when downtime is minimised through timely and proactive maintenance. “This is exactly what the information provided by the iSENSE product family is needed for. The system adds value to district energy networks, making the entire energy system smarter”, Randell concludes.

Digita’s LoRaWAN network

• A national network that can be used for IoT (Internet of Things) solutions
• Designed for wireless and energy-efficient data transfer
• Based on LoRa (Long Range) technology, which is especially well suited for sending and receiving small amounts of data over long distances
• Key features of LoRaWAN (Long Range Wide Area Network) technology include two-way data communication, portability, tracking solutions and easy deployment
• The sensors used to collect data are lightweight and easy to install wirelessly
• A wide range of sensor solutions available

This article was originally published on the mtvuutiset.fi website as part of a commercial partnership.