Energy and water saving desulphuration integrated system for power plant

Abstract

The invention discloses an energy and water saving desulphuration integrated system for a power plant in the technical field of heat transmission. The system comprises an I-level phase change heat exchanger, a mixing chamber and a control system, wherein the I-level phase change heat exchanger is arranged on the back of an air preheater arranged on a gas duct at the tail end of a boiler and then is connected with the mixing chamber through a pipeline, the mixing chamber is connected with the air outlet of the air preheater of a boiler system through a pipeline, and the I-level phase change heat exchanger and the mixing chamber are all connected with the control system through connecting wires; or an II-level phase change heat exchanger is arranged between the desulfurization fan and desulfurizing tower of the boiler system. In the invention, the phase change heat exchanger absorbs the energy of raw gas to heat clean air, and the heated clean air is mixed with the low-temperature clean gas after being further heated to a higher temperature by the air preheater, the gas outlet temperature of a chimney is increased, thus the problems of low temperature corrosion of the existing clean gas heater and invalid integral device caused by low temperature corrosion are avoided radically, the low temperature exhaust heat of the raw gas is used fully, the thermal efficiency of the integral electric generating system is improved, and meanwhile, the water resource is saved greatly.

Description

technical field [0001] The invention relates to a device in the technical field of heat transfer, in particular to an energy-saving, water-saving and desulfurization comprehensive system for power plants used for net flue gas heating up and waste heat recovery after wet desulfurization. Background technique [0002] The use of limestone wet flue gas desulfurization is a desulfurization method commonly used in large power plants. However, the use of wet lime / limestone desulfurization process (FCD) generally has severe low-temperature corrosion of the flue gas heat exchange system, which cannot heat the clean flue gas to the required temperature, and often makes the heat exchange equipment completely ineffective, eventually causing extremely serious the problem of secondary pollution. In other words, using a flue gas heater to increase the net flue gas temperature has long been a technical problem that has not been well resolved in the world. For example, according to the "T...

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Problems solved by technology

This technical scheme once obtained people's general attention, but does not really obtain success so far

The reason is that there are obvious deficiencies: first, the heat exchanger consumes a large amount of steam, and the heat loss accounts for about 2% of the boiler efficiency, and the economy is poor; second, this method does not consider how to absorb and utilize the original flue gas before entering the desulfurization tower. Low-temperature waste heat, in order to improve the thermal efficiency of the boiler as much as possible, but also because a large amount of cooling water needs to be consumed to achieve the process requirements of reducing the temperature of the original flue gas entering the desulfurization tower, so that it will eventually cause a serious waste of water resources and increase the unnecessary pollution of the atmospheric environment. heat pollution

However, assuming that the original air preheater heat balance of the boiler leaves about 20% to 30% of the safety budget, if the device proposed here is not used, and the method provided by another patent is continued, that is, through the The above-mentioned stage III phase change heat exchanger uses the low-pressure steam extracted from the turbine exhaust port to indirectly heat the clean flue gas to achieve the same purpose of increasing the discharge temperature of the clean flue gas after desulfurization, which not only results in a relatively high initial investment in the equipment , and there are also problems of complex operation and relatively high operating costs of this part

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