Grudziadz, Poland

Grudziądz is a city of around 96,042 inhabitants (2010) on the Vistula River in northern Poland. It is situated in the Kuyavian-Pomeranian Voivodeship.

The Water Gate and the city walls of Grudziądz By Łukasz Dąbrowski – Own work, CC BY-SA 4.0,

The city of Grudziądz is supplied from the municipal heating system, operated by OPEC-SYSTEM Sp. z o.o. The subject of OPEC-SYSTEM Sp. z o.o. activity is the provision of heat supply services to municipal, residential and business units by means of heat transmission and distribution using a municipal heating network for heating, ventilation, technology and hot tap water preparation. The amount of heat purchased from the supplier in 2016 was 245.340 MWh. OPEC-SYSTEM municipal heating network, due to the city's longitudinal shape, has been divided into two networks: north and south. Both networks are supplied from a common source of Łąkowa CHP located in the central part of Grudziądz.

District Heating Technical parameters (heating season 2016/2017):

• Temperature: 114/60 °C (south network) and 108/60 °C (north network),  outside the heating season- 68°C,
• The maximum daily average mass flow:  during heating season: 1688 t / h,  outside the heating season: 292 t/h
• Maximum pipe diameter: DN600,
• The total length of the heating network is 98.9 km of which 44.9 km (45%) are pre-insulated pipes.
• At total 667 substations are connected to the network of which 498 are individual and 95 are group substations.

The heating system is regulated in a quantitative and qualitative manner. Depending on the outside temperature, the inlet temperatures of the heating system are adjusted. The basis for adjustment is the temperature table. OPEC-SYSTEM is not the owner of the production plant. Łąkowa CHP, production plant is owned by OPEC-INEKO Sp. z o.o. It is a source producing heat in the form of hot water, technological steam and electricity in a highly efficient cogeneration. The technological steam is produced for the needs of Schumacher Packaging Zakład Grudziądz Sp. z o.o. and OPEC-BIO Sp. z o.o. The electricity produced is used first of all for own needs, whereas the surplus of production is sold to Schumacher Packaging and trading companies.

The Łąkowa CHP has a total installed thermal power of 156.8 MW and 18 MW of electrical power. The installation includes:

• Water boiler type WR-10 (K7) – 11.6MW of thermal power, connected to a steel chimney with a height of 40 m 
• Three steam boilers type OR-32 (K1, K2, K3) and two water boilers type WR-25 (K4, K5) - 145.2 MW of thermal power, connected to a common concrete chimney with a height of 82 m
• Three turbines (TUP 6, TP 6, TUK 6) – 18 MW of electrical power in total.

Boilers K1 and K3 can burn either biomass or coal. At the same time, only one type of fuel is burned in a given boiler. K2, K4, K5 and K7 boilers are coal fired only boilers. All boilers are grate-fired boilers burning pulverized coal assortment.

In order to improve the network efficiency, network's temperature and pressure should be dynamically optimized. Currently approximately 50% of inhabitants uses heat from the DH network while the air quality is concerned as a main challenge. Therefore, the main improvement is identified to be the intensification of activities related to substitution of local boilers with a district heating network. Moreover, around 10% of connected consumers still produce domestic hot tap water with local gas boilers.

Due to the varying heat demand by the largest industrial customer, the use of a heat storage unit should be considered. The heat storage would allow avoiding the network overheat caused by intensified heat consumption by the industry.

Łąkowa CHP in Grudziądz by Mariusz Nasieniewski