Improvement of operation of steam cushion system for sensible thermal energy storage

Ryszard Zwierzchowski,M.A Sayegh,H Jouhara,B Kaźmierczak,M Kutyłowska,K Piekarska,J Danielewicz

doi:10.1051/e3sconf/201911600107

Ryszard Zwierzchowski, M.A Sayegh + Show 5 more

Open Access

https://doi.org/10.1051/e3sconf/201911600107

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Abstract

The paper contains a method for improvement of operation of steam cushion system including its energy savings analyses, for a Thermal Energy Storage (TES) tank. Energy savings analyses were performed using operational data from selected Combined Heat and Power plants, which supply heat to large cities in Poland and are furnished with the TES. The role of the steam cushion system in the TES tank is to prevent the stored water against absorbing oxygen from atmospheric air. In the TES tank, which is a non-pressure tank, oxygen from atmospheric air could penetrate to the network water through the surge chamber and safety valves. The steam pressure under the roof is generated from technological steam injected under the roof. Energy savings in the steam cushion system are generated by using an appropriate technical solution for the upper orifice and suction pipe for circulation water, i.e., to make it movable through the use of pontoons. An isolating buffer layer is created at the top of the tank with very small convective and turbulent heat transport, which causes limited heat transfer from steam bed to the stored water in the tank. This results in heat flux of approximately 10% of the heat flux that occurs in the typical technical solution of the upper orifice and suction pipe for circulation water in the TES tank. This technology offers great opportunities to improve the operating conditions of District Heating System, cutting energy production costs and emissions of pollutants to the atmosphere.

Highlights

District Heating Systems (DHS) in Poland, which are supplied with heat from District Heating plants (DHp) or Combined Heat and Power plants (CHPp), have been undergoing intensive modernization over the last twenty years
The temperature of the circulation water in the suction pipe could not drop below 99.5°C or 93.3°C as is presented in equations (4) and (7)
Where an upper orifice is used, an isolating buffer layer is created at the top of the tank with very restrained convective and turbulent heat transport, thereby causing limited heat transfer from the steam bed area to the water in the tank

Summary

Introduction

District Heating Systems (DHS) in Poland, which are supplied with heat from District Heating plants (DHp) or Combined Heat and Power plants (CHPp), have been undergoing intensive modernization over the last twenty years. These modernization processes usually concern energy generation in DHp or CHPp and heat distribution through the District Heating Network (DHN). TES technology offers big, new opportunities to improve the operating conditions of DHS, i.e., to cut heat and electricity production costs and emissions of pollutants to the atmosphere, and to boost energy security for consumers [5]

System description

Characteristics of the steam cushion system

Energy savings for operation of the steam cushion system

Findings

Summary and conclusions