Inner drying steam flash evaporating double-effect heat exchanging system

Abstract

The invention relates to an inner drying steam flash evaporating double-effect heat exchanging system. A flow distributing device is arranged in a liquid-phase space of a water bath type saturated steam generator; a gas-phase space is provided with a steam drying heat exchanger; overheated steam sequentially enters the steam drying heat exchanger and the flow distributing device through a pressure control valve; steam from the flow distributing device and water in the liquid-phase space are subjected to heat exchange and temperature reduction to form wet saturated steam which overflows out; then the wet saturated steam is heated by the steam drying heat exchanger to form dry saturated steam; the dry saturated steam enters a main steam heat exchanger to heat materials for the second time to form high-temperature condensed water; flash evaporation steam formed by carrying out flash evaporation on the high-temperature condensed water is used for carrying out first time of heating on the materials in a flash evaporation steam heat exchanger; condensed water obtained by condensing the flash evaporation steam enters a water collecting pot and then is pumped into the saturated steam generator through a water supplementing pump; and an PLC (Programmable Logic Controller) adjusts the opening degree of the pressure control valve according the temperature of a material outlet. The system disclosed by the invention realizes the step utilization of steam heat energy, ensures that the steam heat energy can be exhausted, and improves the energy efficiency.

Description

technical field [0001] The invention relates to a steam heat exchange system, in particular to an inner dry steam flashing double-effect heat exchange system. Background technique [0002] In indirect heat exchange, the heat exchange efficiency of saturated steam is higher than that of superheated steam, and the higher the degree of superheat, the lower the heat exchange efficiency. When there is only superheated steam source, it is necessary to reduce the temperature of the superheated steam to reduce the degree of superheat. Generally, steam desuperheaters such as spray desuperheater, surface desuperheater, etc. are used. The lower the superheat after desuperheating, the more serious the steam will be with water, and the worse the steam quality will be. If it is necessary to reduce the steam temperature to the saturation temperature corresponding to the required steam pressure, a water-bath saturated steam generator is usually used, also known as a water-bath steam desupe...

AI Technical Summary

Problems solved by technology

The shortcomings of the existing water-bath saturated steam generators are: the water content in the saturated steam is high, and the steam quality is poor

After the high-temperature condensed water enters the 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, which is very easy to form steam resistance; after the steam resistance, the back pressure of the trap increases , the pressure difference between the two ends of the trap decreases, and the drainage capacity decreases, resulting in the condensed water generated in the heat exchanger cannot be removed in time, the efficiency of the heat exchanger decreases, and the material temperature cannot meet the process requirements, thus affecting normal production

In order to ensure production, it is often necessary to open the shut-off valve in parallel with the steam trap for direct discharge. The steam pressure leaked from the shut-off valve offsets the steam resistance; although the production is guaranteed, the steam utilization rate is reduced and the steam consumption per unit product is increased.

Therefore, the heat exchange efficiency and energy efficiency of the existing heat exchange system are relatively low.

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