Flue gas waste heat recovery system

Abstract

The invention discloses a flue gas waste heat recovery system. The system comprises a first heat exchanger, a second heat exchanger, a heat pump and a heat supply network pipeline; a first liquid distribution device and a second liquid distribution device are arranged in the first heat exchanger; the bottom of the first heat exchanger communicates with the input end of the heat release side of thesecond heat exchanger; the output end of the heat release side of the second heat exchanger communicates with the first liquid distribution device to form a first fluid circulation loop; the output end of the heat release side of the second heat exchanger further sequentially communicates with the heat pump and the second liquid distribution device to form a second fluid circulation loop; the heat supply network pipeline comprises a heat supply network water return pipeline and a heat supply network water supply pipeline; the heat supply network pipeline communicates with the heat absorptionside of the second heat exchanger to form a heat supply network circulation loop; and / or the heat supply network pipeline sequentially communicates with the heat absorption side of the second heat exchanger and the heat pump to form a heat supply network water circulation loop. Through the arrangement, the flue gas waste heat recovery efficiency can be improved, and the investment of heat pump equipment is reduced.

Description

technical field [0001] The invention relates to the technical field of waste heat recovery, in particular to a flue gas waste heat recovery system. Background technique [0002] Natural gas flue gas contains a large amount of water vapor, and the condensation heat carried by this part of water vapor accounts for about 10% of the low calorific value of natural gas, which is an important factor affecting the utilization efficiency of natural gas. Therefore, recovering this part of condensation heat can significantly improve Thermal efficiency of natural gas. [0003] The prior art discloses a central heating system (CN102242946B) that utilizes an absorption heat pump to recover waste heat from flue gas, and uses a flue gas-water direct contact heat exchanger and an absorption heat pump to recover flue gas heat. This system can significantly It can reduce the exhaust gas temperature, and at the same time reduce the concentration of nitrogen oxides in the exhaust gas to a certa...

AI Technical Summary

Problems solved by technology

This setting results in a large temperature difference at the heat exchange end on the high-temperature side of the flue gas. A part of the high-temperature flue gas heat first enters the low-temperature medium and then enters the circulation, and then is driven by the heat pump to drive the heat source to extract water for the heating network, resulting in waste of energy. At the same time lead to a larger investment in heat pump equipment

In addition, during the cooling process of the flue gas, as the water vapor condenses, the specific heat capacity changes greatly, while the specific heat capacity of the spray water remains almost unchanged. If the flow rate of the spray water does not change, the heat exchange temperature difference between the two fluids Difficult to match effectively, also caused relatively large irreversible heat transfer loss

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