Device and method for capturing CO2 in coal-fired flue gas by grades based on membrane method

Abstract

The invention discloses a device and method for capturing CO2 in coal-fired flue gas by grades based on a membrane method. The device is composed of a booster fan, a separation membrane assembly, a draught fan, a permeation side draught fan, a permeation side depth CO2 capturing device and the like; after desulfurization, clean flue gas is boosted by the booster fan to enter the separation membrane assembly; by adjusting a matching relation between the booster fan and the draught fan, permeation residual sides of the separation membrane assembly are guaranteed to be in a positive-pressure state; meanwhile, the permeation side draught fan is adjusted to guarantee that a permeation side of the separation membrane assembly keeps a needed negative-pressure state, so as to form pressure difference between the two sides of a membrane; the pressure difference drives the CO2 in permeation residual side flue gas to permeate towards the permeation side, so that the effect of separating the CO2 in the flue gas is realized; the permeation residual side gas is discharged out from a chimney under the effect of the draught fan. According to the device and the method, the CO2 is enriched and captured by grades so that the problem of CO2 capturing of a current large-size coal-fired power station that the operation cost is high, caused by the fact that the amount of the flue gas is great and the CO2 concentration is low, can be effectively solved.

Description

technical field [0001] The invention relates to a membrane-based staged capture of CO in coal-fired flue gas 2 The device and method are suitable for capturing CO in the desulfurized flue gas of coal-fired power stations. 2 , belonging to the field of coal-fired air pollutant control. Background technique [0002] In the past century, the global climate has undergone changes characterized by warming. Human activities, especially the industrialization of developed countries, have emitted a large amount of greenhouse gases, which is the main factor of current global climate change. CO 2 is the most typical representative of them. [0003] Facing the status quo of global warming, as the largest anthropogenic CO 2 Coal-fired boilers that are emission sources will inevitably require the installation of CO 2 capture device to achieve CO 2 Control of emissions. However, "low carbon" does not mean "zero carbon", and "emission control" does not require "zero emission". 2 As a ...

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Problems solved by technology

[0006] Purpose of the invention: the present invention aims at the large amount of coal-burning flue gas and the CO in the flue gas existing in the prior art 2 low concentrations of CO 2 Due to the high cost of capture operation, the two-step idea of ​​"enrichment first, then capture" is proposed, and a membrane-based staged capture of CO in coal-fired flue gas is provided. 2 The device and method, the device is arranged after the desulfurization equipment, using the CO 2 The characteristics of selective separation and low operating cost are different from conventional high-efficiency and high-cost CO 2 Capture technologies complement each other, both to achieve CO 2 The controlled emissions can also significantly reduce the conventional high-efficiency, high-cost CO 2 The scale of the capture device effectively reduces operating costs

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