Flue gas deep carbon capture device for recovering waste heat
Technical Field
The utility model belongs to the environment field, concretely relates to flue gas degree of depth carbon entrapment device of recovery waste heat.
Background
Climate warming has attracted close global attention, CO 2 Is one of the most prominent greenhouse gases in the atmosphere. As a key industry for carbon dioxide emission, the flue gas tail gas of each thermal power plant in the power industry contains a large amount of carbon dioxide, and the carbon dioxide is directly discharged to the atmosphere in the current process flow. With the establishment of the carbon emission right trade market in China, the carbon emission is comprehensiveCapture of CO, directly related to the economic interest of the enterprise 2 The demand of (2) is gradually coming up.
The MEA (monoethanolamine) method is a common method for capturing CO2, a regeneration cycle is realized through the absorption and desorption of MEA, but a high-temperature heat source is required in the regeneration process, and a steam extraction of a steam turbine of a power plant is generally adopted, so that the overall energy consumption of the technology is high. Meanwhile, the flue gas temperature at the outlet of the wet desulphurization tower of the coal-fired power plant is higher than the requirement of the MEA (membrane electrode assembly) process on the flue gas temperature, and the CO2 absorption rate is low.
For a cogeneration unit, recovering the waste heat in the system is one of the best ways to increase the heating capacity without upsizing the unit. At present, the flue gas is generally discharged after being cooled to 50-60 ℃ by adopting a water spraying method in a power plant, and the heat in the flue gas is not recovered, so that the energy waste is caused. Meanwhile, a large amount of carbon dioxide also exists in the desulfurization slurry generated after spraying, so that the difficulty is increased for further capturing the carbon dioxide.
CN 109454620A discloses a carbon capture and waste heat recovery coupling device, which utilizes an absorption tower and a desorption tower to realize CO in high-temperature flue gas discharged by industry 2 The collection and storage of the waste heat and the recovery of a certain waste heat are carried out. However, in the scheme, the utilization of the waste heat of the flue gas is rough, the temperature of the flue gas of the absorption tower is high, and CO is generated 2 Low absorption rate and CO content in desulfurized slurry 2 Nor was trapping carried out.
Disclosure of Invention
An object of the utility model is to provide a flue gas degree of depth carbon entrapment device of recovery waste heat has solved prior art and has reached the purpose of certain recovery waste heat, but the lower problem of heat recovery rate, and simultaneously, among the prior art absorption tower entry flue gas temperature is high, and CO 2 Low absorption rate and no carbon capture of the desulfurization slurry.
In order to achieve the above purpose, the utility model discloses a technical scheme is:
the utility model provides a flue gas deep carbon capture device for recovering waste heat, which comprises a desulfurizing tower, a primary separator, a flash tank, an absorption tower and a desorption tower, wherein the desulfurizing tower is provided with a flue gas inlet and a flue gas outlet, and the flue gas outlet is connected with a flue gas inlet arranged on the absorption tower; a slurry outlet arranged on the desulfurizing tower is connected with a slurry inlet arranged on the flash tank through a primary separator; a slurry outlet arranged on the flash tank is connected with a slurry inlet arranged on the desulfurizing tower;
a gas outlet arranged on the primary separator is connected with a gas inlet arranged on the absorption tower;
a rich liquid outlet arranged on the absorption tower is connected with a rich liquid inlet arranged on the desorption tower;
a barren liquor outlet arranged on the desorption tower is connected with a barren liquor inlet arranged on the absorption tower;
and a flue gas outlet is formed in the absorption tower.
Preferably, a heat exchange unit is arranged between a rich liquid outlet arranged on the absorption tower and a rich liquid inlet arranged on the desorption tower.
Preferably, a steam inlet arranged on the heat exchange unit is connected with a steam outlet arranged on the flash tank.
Preferably, the heat exchange unit comprises a lean-rich liquid heat exchanger and an absorption heat pump, wherein a rich liquid outlet arranged on the absorption tower is connected with a rich liquid inlet arranged on the desorption tower through the lean-rich liquid heat exchanger and the absorption heat pump in sequence;
and a barren liquor outlet arranged on the desorption tower is connected with a barren liquor inlet arranged on the absorption tower through a barren-rich liquor heat exchanger.
Preferably, a steam outlet arranged on the flash tank is connected with a steam inlet arranged on the absorption heat pump.
Preferably, the absorption heat pump is provided with a driving steam inlet and a first condensed water outlet, and the first condensed water outlet is connected with the clean water tank.
Preferably, the absorption heat pump is provided with a second condensate outlet.
Preferably, a carbon dioxide outlet arranged on the desorption tower is connected with a gas outlet on the condenser; the condenser is provided with a gas outlet and a liquid outlet, and the liquid outlet is connected with a liquid inlet on the desorption tower.
Compared with the prior art, the beneficial effects of the utility model are that:
the utility model provides a pair of flue gas degree of depth carbon entrapment device of recovery waste heat through desulfurization thick liquid flash distillation, reduces desulfurization thick liquid temperature to reduce desulfurizing tower exhaust gas temperature to about 40 ℃, reach MEA and absorb CO 2 The optimum temperature of the water-soluble polymer improves the absorption rate; by means of desulfurization slurry flash evaporation, the heat of the flue gas is actually recovered, and the part of heat is upgraded by an absorption heat pump and then is used for heating MEA rich solution, so that the consumption of power plant steam in the MEA regeneration process can be effectively reduced, and the regeneration energy consumption is reduced; by flashing the desulphurised slurry in two stages, the predominant CO is separated in the first stage primary gas-liquid separation stage 2 And releasing the carbon, realizing the capture of carbon in the desulfurization slurry and improving the overall carbon capture rate of the flue gas.
Drawings
Fig. 1 is a schematic structural diagram of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The utility model provides a flue gas degree of depth carbon entrapment device of recovery waste heat, including desulfurizing tower 1, primary separator 4, flash tank 5, absorption tower 2 and desorber 3, wherein, be provided with flue gas entry and flue gas outlet on desulfurizing tower 1, the flue gas outlet is connected the flue gas entry of seting up on absorption tower 2; a slurry outlet arranged on the desulfurizing tower 1 is connected with a slurry inlet arranged on the flash tank 5 through a primary separator 4; a slurry outlet arranged on the flash tank 5 is connected with a slurry inlet arranged on the desulfurizing tower 1;
a gas outlet arranged on the primary separator 4 is connected with a gas inlet arranged on the absorption tower 2;
a rich liquid outlet arranged on the absorption tower 2 is connected with a rich liquid inlet arranged on the desorption tower 3;
a barren liquor outlet arranged on the desorption tower 3 is connected with a barren liquor inlet arranged on the absorption tower 2;
and a flue gas outlet is formed in the absorption tower 2.
As shown in fig. 1, the utility model provides a pair of retrieve flue gas degree of depth carbon entrapment device of waste heat, including desulfurizing tower 1, absorption tower 2, desorber 3, elementary vapour and liquid separator 4, flash tank 5, absorption heat pump 6, poor-rich liquid heat exchanger 7 and condenser 8, wherein, flue gas entry and exhanst gas outlet have been seted up on desulfurizing tower 1, the flue gas entry that sets up on the exhanst gas outlet connection absorption tower 2.
And a slurry outlet formed in the desulfurizing tower 1 is connected with a slurry inlet formed in the primary gas-liquid separator 4.
And a gas outlet formed in the primary gas-liquid separator 4 is connected with a gas inlet formed in the absorption tower 2.
And a slurry outlet arranged on the primary gas-liquid separator 4 is connected with a slurry inlet on the flash tank 5.
And a steam outlet formed in the flash tank 5 is connected with a steam inlet formed in the absorption heat pump 6.
The absorption heat pump 6 is provided with a driving steam inlet and a first condensate outlet, and the first condensate outlet is connected with a water purifying tank.
And a second condensate water outlet is arranged on the absorption heat pump 6.
The rich liquid outlet arranged on the absorption tower 2 is connected with the rich liquid inlet arranged on the desorption tower 3 through a lean-rich liquid heat exchanger 7 and an absorption heat pump 6 in sequence.
A barren liquor outlet arranged on the desorption tower 3 is connected with a barren liquor inlet arranged on the absorption tower 2 through a barren-rich liquor heat exchanger 7.
The gas outlet arranged on the desorption tower 3 is connected with the gas inlet arranged on the condenser 8.
The condenser 8 is provided with a gas outlet and a liquid outlet, and the liquid outlet is connected with a liquid inlet arranged on the desorption tower 3.
And a flue gas outlet is formed in the absorption tower 2.
The utility model discloses a theory of operation:
the flue gas 9 enters the desulfurizing tower 1 to exchange heat with the low-temperature desulfurizing slurry 12 sprayed from the top of the tower and is purified, and the temperature of the flue gas is reduced and the flue gas is humidified.
High-temperature desulfurization slurry at bottom of desulfurization tower10 into the primary gas-liquid separator 4, desulphurizing the CO in the slurry under vacuum of about 20kPa absolute 2 Released and carries a small amount of water into the absorption tower 2.
CO removal 2 Enters the flash tank 5 and is flashed in a vacuum environment at a lower pressure to produce flash steam 13 and low temperature desulphurised slurry 12, heat being transferred from the desulphurised slurry to the flash steam.
The flash steam 13 enters an absorption heat pump 5, and is upgraded by using driving steam 15, and the MEA rich solution is heated. Driving the steam to condense in the heat pump to form condensed water 16 which returns to the water purifying tank; the flash steam 13 is condensed into condensed water 14 which is used as the water for desulfurization.
The purified saturated wet flue gas 11 enters an absorption tower 2 to be in countercurrent contact with MEA barren solution sprayed from the top of the tower, and CO in the flue gas 2 Is absorbed, CO 2 The absorbed flue gas 18 is discharged from the top of the absorption tower.
The MEA rich solution 17 is discharged from the bottom of the absorption tower, is heated by the lean-rich solution heat exchanger 7, enters the absorption heat pump 6, is further heated to high-temperature rich solution 19, and enters the desorption tower 3 for desorption.
The desorbed MEA lean solution 20 enters the absorption tower 2 for circulation after being cooled by the lean-rich solution heat exchanger 7.
Desorbed CO-rich 2 The gas 21 is discharged from the top of the tower, enters a condenser 8 for gas-liquid separation and is further compressed to obtain high-purity CO 2 22。
The utility model discloses a desulfurization thick liquid flash distillation reduces desulfurization thick liquid temperature to reduce desulfurizing tower exhaust gas temperature to about 40 ℃, reach MEA and absorb CO 2 The optimum temperature of the water-absorbing agent is improved.
By means of desulfurization slurry flash evaporation, the heat of the flue gas is actually recovered, and the part of heat is upgraded by an absorption heat pump and then is used for heating the MEA rich solution, so that the consumption of the power plant steam in the MEA regeneration process can be effectively reduced, and the regeneration energy consumption is reduced. By flashing the desulphurised slurry in two stages, the predominant CO is separated in the first stage primary gas-liquid separation stage 2 And releasing the carbon, realizing the capture of carbon in the desulfurization slurry and improving the overall carbon capture rate of the flue gas.