District heating
Aging infrastructure
Pressure sensor

From assumption to knowledge

Ry Heat Utility, Denmark

Along with the town’s rapid development – which included several new neighbourhoods – Ry Heat Utility was in need of detailed knowledge about the pressure in its distribution network. With Kamstrup’s pressure sensors, the utility now gets precise data to use when sizing and renovating its pipes.

Since 1962, Ry Heat Utility has supplied district heating for the town’s homes, shops and industry, and today, the distribution network consists of more than 80 kilometers of pipe. 

Because of the growth Ry has seen in recent years, the number of houses requiring heat has increased significantly. As this affects the differential pressure in the network, Operations Manager Flemming Skjødt needed precise data on what pressure the utility actually delivers to its customers.

In addition, the supply area covers considerable variations in topography, the age of the pipes, energy profiles of houses and differences in end-user behaviour – all factors that are difficult for the Operations Manager to predict in his calculations to design and get the most out of his network.

Using – for a start – two Kamstrup pressure sensors, he is, therefore, working his way through the supply area one zone at a time.

”We don’t know for sure if the pressure we guarantee is, in fact, the minimum pressure the consumer has if we were to measure it and check,” says the Operations Manager. With the new pressure sensors, the utility moves from assumption to knowledge: ”With the pressure sensors, we can see what pressure we actually deliver.” 

An operative tool

Ry Heat Utility has always had differential pressure measurement in its network but until now, it has used expensive fixed pressure transmitters connected to the SCADA system and placed where it assumed the differential pressure was representative. Verification performed in other places in the network was done using a manual manometer and that makes the measurement difficult to interpret.

”The measurement is only as reliable as the moment you choose and as accurate as the manometer allows. You don’t get a history – only a very brief measurement showing a precise snapshot”, Flemming Skjødt explains.

Performing pressure measurements over time allows the Operations Manager to size his distribution network more accurately:
”I place Kamstrup’s pressure sensors on the service taps in the valve pits and over a period of time, I read both the forward pressure and the return pressure using READy. I then know the actual differential pressure we have available and that enables me to calculate my pipes with much higher precision.” 

Data-based sizing

While a few of the zones in the supply area have not changed significantly, some of the pipes date back to the late 1960s and were designed based on very different criteria. ”We have a number of pipes in the centre of town where some old concrete ducts need to be replaced, but they are from a time when we used a higher set of temperatures so they have to be recalibrated. I will be using the pressure sensors for that,” says Flemming Skjødt.

In other parts of the network, he is not sure what pipes are hidden under ground because they are so old that it is not well documented.

”When I do pipe renovations, it is crucial that I choose the right size pipe. If the pipe is too big, it is too expensive in terms of both purchase price and heat loss, but if it is too small, it cannot deliver the necessary pressure to the customer. Here, the pressure sensors work as quick and accurate little helpers. We get closer to real-time data,” he explains.

The increased precision can reduce the overmeasure often used when sizing pipes. ”The overmeasure can mean the difference between going up a size or maybe even down, so there are potential savings there.”

Pipe sizing errors are expensive

The work involved in closing off town areas, digging up old pipes and laying down new ones is both time-consuming and costly – and the bigger the pipe, the more expensive it is. In addition, if the new pipes turn out to be the wrong size, the utility risks having to dig them up again. 

Replacing a service pipe is both costly and inconvenient because the consumer’s driveway or front garden will have to be dug up. However, if the pipes are located by the road, it will require breaking up the asphalt, which can result in a factor 10 increase in costs amounting to several thousand kroner per meter. 

”If I size my distribution network based on erroneous data or theory, I risk putting 100 meters of the wrong sized pipe into the ground. In the technical world we are in, believing isn’t enough – you need to know,” says Flemming Skjødt.

Supply optimisation

According to Flemming Skjødt, the utility’s ultimate goal will always be to deliver the right product at the right price at the right time so the consumers have a positive experience. This goes for everything from the actual supply of district heating to customer service and guidance as well as minimising costs in order to lower the price of heat. ”To reach our goal, we need to know what is actually going on in our network. We get that knowledge from the pressure sensors.”

Going forward, the Operations Manager will be placing more pressure sensors in the network but he will not know how many until the utility has worked its way through the zones in the supply area. The first step is to replace the last half of the meter park and expand the utility’s new wireless network, which will determine where it will gain the most from placing the new sensors.
From handheld terminal to network reading

So far, Ry Heat Utility has read its heat meters twice a year using a handheld terminal, but with network reading and more frequent meter data, the utility gets even more insight into the distribution network. This will enable it to further lower the return temperature and to prioritise its renovation efforts based on the actual state of the equipment in the network.  

In addition, once all data from the supply area is automatically delivered directly to the utility via the READy system, it will allow the Operations Manager to start using more of his time on optimisations: ”The need to get out into your area is really a thing of the past. Why run around town when we can get more insight by delving into the data we get?”

Project facts:

2,369 metering points
MULTICAL® 602 heat meters
READy network reading

Approx. 1,200 meters have been replaced and are read using the remote reading system, READy. The rest are read using a handheld terminal and PcBase

Kamstrup pressure sensors