Abstract

In district heating stations, the heat carrier is circulated between the energy source and consumers by a pumping system. Fluid handling systems, such as pumping systems, are responsible for a significant portion of the total electrical energy use. Significant opportunities exist to reduce pumping energy through smart design, retrofitting, and operating practices. Most existing systems requiring flow control make use of bypass lines, throttling valves or pump speed adjustments. The most efficient of these options is pump speed control. One of the issues in using variable-speed pumping systems, however, is the total efficiency of the electric motor/pump arrangement under a given operating condition. This paper provides a comprehensive discussion about pump control in heating stations and analyzes the energy efficiency of flow control methods. Specific attention is also given to the selection of motor types, sizing and pump duty cycle. A comparative energy analysis is performed on the hot water discharge adjustment using throttling control valves and variable-speed drives in a district heating station constructed in Romania. To correlate the pumped flow rate with the heat demand and to ensure the necessary pressure using minimum energy, an automatic system has been designed. The performances of these control methods are evaluated in two practical applications. The results show that approximately 20%–50% of total pumping energy could be saved by using the optimal control method with variable-speed pumps. Additionally, some modernization solutions to reduce the environmental impact of heating stations are described.

Highlights

  • Interest in efficient and eco-friendly management has been growing in recent years, especially in systems characterized by large consumption of non-renewable energy

  • The results show that the control strategy is robust and capable of improving the energy efficiency of the system for most of the scenarios considered

  • This paper provides a comprehensive discussion about pump control in heating stations and analyzes the energy efficiency of flow control methods

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Summary

Introduction

Interest in efficient and eco-friendly management has been growing in recent years, especially in systems characterized by large consumption of non-renewable energy Fluid handling systems, such as pump and fan systems are responsible for a significant part of total electrical energy use [1]. An increased issue in using VSP systems is the control and optimization of their operation and the total efficiency of the electric motor/pump arrangement under a given operating condition. A comparative energy analysis is performed on the hot water discharge adjustment using throttling control valves and variable-speed drives in a district heating station constructed in Romania. To correlate the pumped flow rate with the heat demand and to ensure the necessary pressure using minimum energy, an automatic system has been designed The performances of these control methods are evaluated in two practical applications. Some modernization solutions to reduce the environmental impact of heating stations are described

Thermal Load of the Heating Station
Solutions for Reducing the Pumping Energy
Pump Operation at Fixed Speeds
Pump Operation at Variable Speeds
Motor Options
Variable Frequency Drives
Energy Efficiency of the Adjustment Methods
Assessment of Energy Savings with Variable-Speed Drives
Economical Efficiency
Findings
Conclusions
Full Text
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