Multi-effect flash evaporation system for utilizing condensed water waste heat in air-heating coil group

Abstract

The invention relates to a multi-effect flash evaporation system for utilizing condensed water waste heat in an air-heating coil group. A plurality of groups of coil heat exchangers capable of making steam pressure be increased gradually in sequence along an air flowing direction are arranged in the air-heating coil group, and a drain valve is arranged at an outlet of each coil heat exchanger; the coil heat exchanger close to a hot air outlet is connected with a main steam pipe through a main steam valve, condensed water is introduced to a first-stage flash-evaporation tank for flash evaporation and the steam obtained after the flash evaporation is introduced into the coil heat exchanger with the steam pressure inferior to main steam pressure by one stage for heat emission, the condensed water is introduced into a second-stage flash-evaporation tank for flash evaporation and the steam obtained after the flash evaporation is introduced into the coil heat exchanger with the steam pressure inferior to the main steam pressure by two stages for heat emission, the condensed water is introduced into a third-stage flash-evaporation tank for flash evaporation, and so on; and the final-stage flash-evaporation steam is introduced into the coil heat exchanger close to a cold air inlet, the discharged condensed water is introduced into a condensed water pump, and an outlet of the condensedwater pump is connected into a condensed water recovering system. The multi-effect flash evaporation system disclosed by the invention can be used for not only guaranteeing the temperature of hot airto reach a process requirement, but also increasing the utilization efficiency of the steam and reducing the energy consumption of a unit product.

Description

technical field [0001] The invention relates to a thermal system, in particular to a multi-effect flash utilization system for waste heat of condensed water of an air heating coil group. Background technique [0002] The air heating coil group usually includes multiple parallel coil heat exchangers. The inlets of each coil heat exchanger are connected to the main steam pipe through the main steam valve, and the outlets of each coil heat exchanger are respectively equipped with drain valves. The outlets of each steam trap are respectively connected to the main condensate pipe. When the steam flows through the heat exchangers of each coil, it exchanges heat with the air and releases latent heat, and then condenses into high-temperature condensed water under the same pressure. The high-temperature condensed water is discharged into the main condensed water pipe through each steam trap; One end of the heating coil group enters, flows through the outer surface of each coil heat ...

AI Technical Summary

Problems solved by technology

[0003] After the high-temperature condensed water enters the total condensed water pipe, the pressure drops continuously along the way, part of the high-temperature condensed water flashes into steam, the volume expands by more than 1000 times, and the flow rate increases by about 10 times, so that the main condensed water pipe is not dominated by condensed water but by It is flash steam, which is easy to form steam resistance; after steam resistance, the back pressure of the trap increases, the pressure difference between the two ends of the trap decreases, and the discharge capacity of the trap decreases, resulting in the condensed water generated in the coil heat exchanger cannot be removed in time, The efficiency of the heat exchanger decreases, and the temperature of the hot air cannot meet the process requirements, thus affecting normal production

In order to ensure production, it is often necessary to open the bypass shut-off valve in parallel with the steam trap for direct discharge. As a result, the steam leaks through the bypass shut-off valve while the condensed water is discharged, and the steam flows against the condensed water in the main condensed water pipe to overcome the steam leakage. resistance; although the production is guaranteed, the steam utilization rate is reduced and the steam consumption per unit product is increased

Therefore, the existing system either cannot produce normally, or the waste of steam is serious, and the sensible heat of condensed water is not fully utilized

Images