REPORT. What does the boiler as big as a block look like, which left thousands of blocks in Bucharest without heat. And who are the “Dores”

A crack appeared in a steam boiler, “which is the size of an 8-10-story apartment block”, explains the engineer who maintains it, reduced the capacity of CET Bucharest Sud. The breakdown left thousands of blocks without heat and hot water for days. On Friday, HotNews was inside the plant to see what such a breakdown looks like and what the specialists who are repairing the old and fragile system are saying.

• The citizens of Bucharest in the blocks left without heat thought, angrily, that “they work like Dorei and do nothing”. As journalists, it is our duty to discuss with those subject to public criticism.
• Marius Bucur, chief engineer at CET Sud explains why breakdowns at such installations are not managed in hours, but in days. The engineer believes that “Mere administrative reorganization does not solve anything. Technical problems are solved with investments.”

When you say cauldron, you think of something small, the size of a barrel, at most. Here is something else. You look up and it doesn't end. “In terms of height, each boiler is comparable to a block of 8-10 floors”, explains Marius Bucur, chief engineer of the CET Bucharest Sud plant. “That size also gives them a very large thermal inertia.”

VIDEO – What it looks like inside CET Sud:

The steam towers on the road to the Sea

The CET Sud plant is located in the south of the city, beyond Dâmbovița in front of the Văcărești Natural Park. Almost opposite the Vitan fair, a landmark known to the people of Bucharest. Its smoke towers can be seen from afar on the highway leading to the Black Sea.

At the entrance to CET Sud, access is done with a protective helmet. The tour takes place on an elevated metal walkway among multi-level boilers, thick pipes and working fans.

The sound of things going

As a sensation, you feel on the floor of an old hall, like the old one at the Obor square, but you don't see the stalls, but the installations.

Their noise is constant and loud enough to make conversations difficult. The size of the equipment and the continuous rhythm of the installations immediately give the feeling of a system that works without a break. Until something snaps.

Engineer Coman: Inertia is part of how a plant like this works

The steam boilers of CET Bucharest Sud are large industrial installations, identical in type and function. This inertia is essential for the operation of the plant, explains Dumitru Coman, the second engineer we talk to.

Boilers heat up and cool down slowly, and they cannot be turned on or off quickly. For this reason, any intervention, even a punctual one, involves a complete shutdown of the installation and an inevitable waiting time, adds the specialist.

A small crack, a big effect

The fault that reduced production capacity was a crack in one of the pipes inside a steam boiler. While explaining the intervention, the engineers show on the phone pictures of the inside of the installation, where the pipe bundles and the replaced portion can be seen.

“Look, a pipe broke in this and you have to turn off the boiler immediately,” he says. “In order to intervene, you have to isolate it, cool it completely, and then you go in. You change the pipe and then you let it go again.”

The boiler operates at high temperatures and pressures and is a completely enclosed assembly. For this reason, shutdown is not immediately followed by repair.

It takes tens of hours to cool down the facility, until safe conditions can be ensured for the teams working inside. “You can't go in there while the facility is warm. It has to be safe for people,” Coman and Bucur explain in turn.

The chain effect: the boiler stops, the turbine stops

Shutting down the boiler automatically also shut down the related turbine, because the production chain is a continuous one. “When steam boiler number 4 stopped, the related turbine also stopped automatically, because we had no more steam”, explains Marius Bucur. “If you run out of steam, you can no longer produce electricity or heat on that circuit.”

CET Sud did not stop completely. Other boilers and turbines remained in operation, but the loss of one boiler significantly reduced total capacity. “One boiler off doesn't mean the plant stops, but it limits you a lot,” says the engineer.

The actual intervention was possible only after the complete cooling of the installation. “We expected an intervention period of three days. We managed to do it in two”, says chief engineer Bucur. They worked continuously.

Is there a plan B?

At CET Bucharest Sud there is no backup in the classical sense – an identical boiler, ready to be started immediately if one breaks down. The breakdown solution consists in the operation with the other aggregates available, within the technical limits of the installation and the network.

Some boilers have been permanently taken out of operation and can no longer be used even temporarily. “Boilers 5 and 6 are withdrawn from operation. Once withdrawn, they are no longer declared as capacities, they no longer appear at the national energy dispatcher. Practically, they no longer exist as a backup option,” explains Dumitru Coman, engineer at the plant.

Chief Engineer Bucur claims that the equipment is old and beyond its lifespan

The absence of reserves is directly related to the age of the equipment. “Any energy equipment has a lifespan calculated at 20-25 years, maximum 30”, says Marius Bucur. “After that, you either do a major overhaul or you take it out of service.”

A major repair involves investments of about 40–50% of the cost of new equipment and can extend the operation by another life cycle. “The boilers that are taken out of service are no longer working at all. They are no longer authorized to operate,” explains the engineer.

How CET Sud works

CET București Sud operates in cogeneration mode, i.e. it produces electricity and thermal energy simultaneously. “With the same steam you make two products”, explain those who lead us through the bowels of the steam fortress.

The steam drives a turbine that produces electricity and is then used to heat the water in the district heating system.

Starts and stops are slow processes. “Starting a boiler takes about six hours. Starting a turbine from cold, also about six hours. A complete start-up takes 12-14 hours,” says the engineer.

How a fault is detected

Defects are permanently monitored, both automatically and by operating personnel. Parameters such as pressure, temperature and flow are monitored in the control room. “When a problem occurs, you see parameter fluctuations. Visual and audible alarms appear.”

In parallel, the staff makes periodic rounds in the facility. “Each one has a circled area. If they see something wrong, they signal. Then they decide if they can continue or if they can stop. In this case, the decision was to stop.”

Why does heating agent arrive, but the radiators remain cold

After fixing the crack, ELCEN announced the delivery of thermal agent at temperatures up to 96-97 degrees Celsius. However, in many areas the radiators remained cold.

The engineers explain that the temperature is not enough. “The amount of heat is flow multiplied by the temperature difference between flow and return.” “If you give a heater 100 degrees, but it doesn't have circulation, it doesn't heat up.”

In the areas close to the plant, the heat agent arrives at a high temperature, which is why the flow rate is reduced. Further, as the temperature drops, the flow rate should increase. However, the very old network no longer allows these adjustments without risk.

Why can't I increase the pressure

Increasing pressure would force circulation but could cause damage. “The network is very old. If you raise the pressure, you break it,” the engineers explain. Because of this, the system today operates at lower pressures than it was originally designed for.

“The problems are chronic”

Engineers say the recent breakdown is not the root cause of the problems, but an episode in a system that has been at its limit for years. “The problems are chronic. The system is very old,” says Marius Bucur. “Simply administrative reorganization does not solve anything. Technical problems are solved with investment.”

According to them, there is good faith in crisis management, but also clear limits. “It's not that someone doesn't want it. At some point, there's nothing you can do to an old system without forcing it.”

On an old map in the back of a room, he shows the ramifications, the networks, but also the historical CETs. One no longer works: CET Titan. It is the other one in the eastern and southeastern area of ​​the Capital, which serves the blocks in Sectors 2 and 3, two of the most populated in Bucharest.

About repairs, investments and the “circle” of breakdowns

When asked about the pace of interventions, engineers say that the replacement of some sections of the network is done constantly, but the effects cannot be felt quickly in such an old and extensive system. “Kilometers of the network are being changed, but the system is so big that, often, while you are replacing a portion, a breakdown occurs elsewhere,” explains Marius Bucur.

The district heating network works as a continuous system, where demands move from one section to another. Fixing one area does not automatically make the rest of the network go away.

The chief engineer emphasizes that the main problem is not the lack of punctual interventions, but the insufficient pace of investments compared to the degree of wear and tear. “CET Bucharest Sud has been operating for almost 60 years, and most of the infrastructure dates back to the first stages of operation. When you finish changing the last pipe, you have to start over. It's not something that can be solved once and for all,” says Bucur.

“You can't force an old system without breaking it somewhere else”

In this context, each new failure is not an isolated incident, but a natural consequence of system aging. “Iron is iron. At some point it wears out and needs to be replaced. You can maneuver, you can compensate, but you can't force an old system without breaking it somewhere else,” he explains.

Engineers say that, from their point of view, there is good faith and constant efforts, but the limits are technical. “These problems are not solved by administrative reorganization. They are solved by investments”, says Marius Bucur, emphasizing that, without them, the system remains vulnerable, no matter how many kilometers of network are replaced annually.