Introduction

The invention concerns a strategy for thermal peak-shaving in district heating systems. The by-pass valves – located at the users’ substation or in other parts of the network – are used to exclude the substation heat-exchanger and to pre-heat the district heating network in order to reduce the temperature difference at the plant level, and consequently the heating power.

Technical features

The strategy consists in the pre-heating of the distribution network. This allows to totally or partially get rid of the cold water within the return line of the network before the start-up of the users’ heat exchangers. This goal is reached by a smart management of the by-pass valves located in the system.

The control system involves the circulation of a pre-heating mass-flow rate through the by-pass pipe. This helps to decouple the primary circuit from the secondary circuit and, as a result, the production from the demand side.

Thus, by the time of the real start-up of the heating systems, the return temperature at the production plant level will be considerably higher. Despite the mass-flow rates are high, a relevant reduction of the heating power will be possible thanks to the reduction of the temperature difference.

Possible Applications

• Medium-sized or large district heating network with high peak demands that are due to night set-backs.

Advantages

• Higher efficiency of the global system;
• Lower emissions;
• Lower heating production costs;
• No installation costs;
• No space needs;
• Independence from users heat demand;
• Fast start-up of the customers heating systems.