Two-section type spraying flue gas water lifting and waste heat utilization system

Abstract

The utility model discloses a two-section type spraying flue gas water lifting and waste heat utilization system, and relates to the technical field of wet desulphurization. The system comprises a spraying cooling tower, a plate heat exchanger, a condensation water lifting storage tank and a heat pump unit, a water pool, a first-stage spraying cooling area, a second-stage spraying cooling area and a third-stage ridge efficient demister are sequentially arranged in the spraying cooling tower from bottom to top, and a spraying cooling tower inlet is formed between the water pool and the first-stage spraying cooling area; and a liquid collecting tray is arranged between the first-stage spraying cooling area and the second-stage spraying cooling area. According to the utility model, desulfurized low-temperature flue gas and low-temperature circulating spray liquid drops are in reverse contact for heat exchange, so that the temperature of the flue gas is further reduced, moisture carried in the flue gas is condensed and separated out, the white smoke phenomenon caused by direct discharge of the flue gas is reduced, meanwhile, condensed water is recycled, and the additional water supplementing amount of a desulfurization system is effectively reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of wet desulphurization, more particularly to a two-stage type spray flue gas water extraction and waste heat utilization system. BACKGROUND

[0002] The wet desulphurization technology is widely used in flue gas treatment due to its high desulphurization efficiency, but the wet desulphurization technology also leads to an increase in the water content of flue gas, if the flue gas after desulphurization is directly discharged into the atmosphere through a chimney, a large amount of saturated water vapor carried in the flue gas will be discharged into the atmosphere with the flue gas, and chimney rain phenomenon is likely to occur; at the same time, the heat carried by the flue gas after desulphurization is also wasted.

[0003] The water consumption of the wet desulphurization system accounts for more than 50% of the water consumption of the coal-fired power plant system, and the water loss of the flue gas directly discharged after desulphurization accounts for more than 80% of the water consumption of the desulphurization system, in line with the principle of "water saving and reduction of water consumption index", especially for water-deficient areas, it is of great significance to develop flue gas water extraction technology to realize less water supplement or even zero water supplement of the desulphurization system.

[0004] At present, the condensation method is adopted, whether it is indirect condensation of a heat exchanger or direct condensation by spraying, the temperature of the flue gas is reduced below the water dew point, the water vapor in the flue gas is condensed and recovered, which is a mainstream flue gas water extraction technology; however, for flue gas with high dust content, how to realize the graded utilization of condensed water and improve the water quantity of high-quality condensed water is the focus of attention of power plants; in addition, for cogeneration power plants in cogeneration areas, how to further utilize the waste heat of the flue gas after desulphurization to increase the heating capacity of the heat network under the premise of reducing the water consumption index of the desulphurization system is also a problem to be solved.

[0005] Therefore, it is necessary to develop a two-stage type spray flue gas water extraction and waste heat utilization system which can realize the graded utilization of flue gas condensed water and improve the heating capacity of the heat network. UTILITY MODEL CONTENT

[0006] The utility model aims at overcoming the defects in the background art, and provides a two-stage type spray flue gas water extraction and waste heat utilization system.

[0007] In order to achieve the above-mentioned purpose, the technical scheme of the utility model is as follows: a two-stage type spray flue gas water extraction and waste heat utilization system, characterized by comprising a spray cooling tower, a plate heat exchanger, a condensation water extraction tank and a heat pump unit, the inside of the spray cooling tower is sequentially provided with a water pool, a first-stage spray cooling zone, a second-stage spray cooling zone and a third-stage ridge high-efficiency demister from bottom to top, there is a spray cooling tower inlet between the water pool and the first-stage spray cooling zone, and a liquid collecting pan is arranged between the first-stage spray cooling zone and the second-stage spray cooling zone;

[0008] The bottom of the water pool is connected with the first-stage spray cooling zone through a first-stage cooling circulating pump and the plate heat exchanger in sequence.

[0009] The collecting tray is connected with the secondary spray cooling area through a condensate water storage tank, a secondary cooling circulating pump and a heat pump unit in sequence.

[0010] The first spray layer of the primary cooling area and the first spray layer of the secondary cooling area are both provided with a filler layer below.

[0011] The condensate water storage tank is connected with the tertiary ridge high-efficiency demister and a process water tank through a demister flushing water pump.

[0012] The plate heat exchanger is connected with the heat pump unit through a plate heat exchanger cold source water supply pump, and the heat pump unit is connected with a heat network.

[0013] In the above technical solution, the primary spray cooling area comprises a first spray layer and a second spray layer from bottom to top; and the primary cooling circulating pump comprises a first primary cooling circulating pump and a second primary cooling circulating pump.

[0014] The bottom of the pool is connected with the first spray layer through the first primary cooling circulating pump, and is connected with the second spray layer of the primary cooling area through the second primary cooling circulating pump and the plate heat exchanger in sequence.

[0015] In the above technical solution, the heat pump unit comprises a first heat pump unit and a second heat pump unit; the plate heat exchanger is connected with the first heat pump unit, and the first heat pump unit is connected with the heat network.

[0016] In the above technical solution, the secondary spray cooling area comprises a first spray layer and a second spray layer from bottom to top; the first spray layer and the second spray layer of the secondary cooling area are both connected with the second heat pump unit; and the second heat pump unit is connected with the heat network.

[0017] In the above technical solution, the bottom of the pool is connected with the water using point through a blowdown pump.

[0018] In the above technical solution, an alkali tank is further included; the alkali tank is connected with the connecting pipeline between the pool and the second primary cooling circulating pump through a first alkali metering pump, and is connected with the connecting pipeline between the condensate water storage tank and the secondary cooling circulating pump through a second alkali metering pump.

[0019] In the above technical solution, two of each of the secondary cooling circulating pump, the demister flushing water pump, the plate heat exchanger cold source water supply pump and the blowdown pump are provided, one for use and one for standby.

[0020] In the above technical solution, the first spray layer of the primary cooling area and the first spray layer of the secondary cooling area are both provided with a filler layer below.

[0021] Compared with the prior art, the utility model has the advantages that:

[0022] 1) The low-temperature flue gas after desulfurization is reversely contacted and heat-exchanged with low-temperature circulating spray liquid drops in the utility model, so that the flue gas temperature is further reduced, the water carried in the flue gas is condensed and separated out, the white smoke phenomenon generated by direct flue gas discharge is reduced, meanwhile, the condensed water is recycled and utilized, and the additional water supplement of the desulfurization system is effectively reduced.

[0023] 2) The utility model adopts staged spray cooling, the primary spray cooling area washes off most of the dust while cooling the flue gas, the temperature drop of the flue gas in the area is small, the condensed water quantity is small, the solid content of the corresponding condensed water is relatively large, the water quality is poor, and the water is discharged through the blowdown pump for use in the water point; the secondary spray cooling area mainly cools the flue gas, the temperature drop of the flue gas in the area is large, the condensed water quantity is large, and the solid content is extremely low, so that a large amount of high-quality condensed water can be recycled, the application range of the recycled water is increased, and the water supplement of the desulfurization system is reduced; the utility model effectively realizes the staged control of the condensed water quality.

[0024] 3) In the primary spray cooling area, the circulating spray water is heat-exchanged with the flue gas and the temperature is increased, but the water quality is poor, in order to maintain the stable water temperature of the circulating spray water and fully recycle the heat of the condensed water in the area, the utility model adopts indirect heat exchange, and a plate heat exchanger is configured to cool the circulating spray water; the cold source water of the plate heat exchanger is heated in the plate heat exchanger, is pumped into the primary heat pump unit for further cooling after being pumped into the plate heat exchanger through the plate heat exchanger cold source water pump, and is continuously sent into the plate heat exchanger cold source inlet, so that the cold source water is closed and constant-temperature circulated, and the heat of the cold source water is absorbed by the primary heat pump unit and is added to the heat network return water; flue gas waste heat utilization is realized.

[0025] 4) In the secondary spray cooling area, the circulating spray water is heat-exchanged with the flue gas and the temperature is increased, and the water quality is good, so that the utility model directly adopts the secondary heat pump unit to absorb the low-quality heat source of the condensed water, heats the heat network return water, and realizes flue gas waste heat utilization.

[0026] 5) The utility model is provided with a lye tank, the lye is respectively sent into the inlet pipeline of the primary and secondary cooling circulating pumps through the lye metering pump, is fully mixed with the condensed water through the impeller stirring action of the condensed water circulating pump, and the pH value of the water quality in the system is maintained between 6 and 7. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a structural schematic view of the utility model.

[0028] Wherein, 100 - spray cooling tower, 110 - water pool, 120 - first spray cooling zone, 121 - first spray layer of first cooling zone, 122 - second spray layer of first cooling zone, 130 - second spray cooling zone, 131 - first spray layer of second cooling zone, 132 - second spray layer of second cooling zone, 140 - three-stage ridge high-efficiency demister, 150 - liquid collecting pan, 160 - filler layer, 200 - plate heat exchanger, 300 - condensate water storage tank, 400 - heat pump unit, 410 - first heat pump unit, 420 - second heat pump unit, 510 - first cooling circulating pump, 511 - first cooling first circulating pump, 512 - first cooling second circulating pump, 520 - second cooling circulating pump, 530 - demister flushing water pump, 540 - plate exchanger cold source water supply pump, 550 - blowdown pump, 561 - first lye metering pump, 562 - second lye metering pump, 600 - lye tank. DETAILED DESCRIPTION

[0029] The implementation of the present application will be described in detail below with reference to the accompanying drawings, which do not constitute limitations to the present application, but are only examples. Meanwhile, the advantages of the present application will become more apparent and easier to understand through the description.

[0030] To solve the problem of water loss caused by direct discharge of saturated low-temperature flue gas after desulfurization, large water consumption of the desulfurization system, increased system operation cost in water-deficient areas, poor water quality of the recovered water for high-dust flue gas, small applicable range of the recovered water, and difficult capture and utilization of flue gas waste heat after further cooling of the low-temperature flue gas, the present application proposes a two-stage spray flue gas water recovery and waste heat utilization system and a use method thereof, which realizes further cooling and condensation of flue gas after desulfurization and recovery of water carried in the flue gas, and reduces the white smoke phenomenon caused by direct discharge of flue gas after desulfurization. The present application realizes high-quality condensate water recovery rate, increases the applicable range of the recovered water, and reduces the water supplement of the desulfurization system by using hierarchical spray cooling. Meanwhile, the present application realizes flue gas waste heat utilization by using a heat pump to absorb the low-quality heat source of the condensate water and heat the return water of the heat network.

[0031] As shown in the drawings, the two-stage spray flue gas water recovery and waste heat utilization system comprises a spray cooling tower 100, a plate heat exchanger 200, a condensate water storage tank 300, and a heat pump unit 400. The inside of the spray cooling tower 100 is sequentially provided with a water pool 110, a first spray cooling zone 120, a second spray cooling zone 130, and a three-stage ridge high-efficiency demister 140 from bottom to top. The water pool 110 is provided with a spray cooling tower 100 inlet between the water pool 110 and the first spray cooling zone 120. The first spray cooling zone 120 and the second spray cooling zone 130 are provided with a liquid collecting pan 150.

[0032] The bottom of the water pool 110 is sequentially connected with the first spray cooling zone 120 through a first cooling circulating pump 510 and the plate heat exchanger 200.

[0033] The collecting pan 150 is connected with the secondary spray cooling area 130 through the condensate water storage tank 300, the secondary cooling circulating pump 520 and the heat pump unit 400 in sequence.

[0034] The first spray layer 121 of the primary cooling area and the first spray layer 131 of the secondary cooling area are both provided with the filler layer 160.

[0035] The condensate water storage tank 300 is connected with the tertiary ridge high-efficiency demister 140 and the process water tank through the demister flushing water pump 530.

[0036] The plate heat exchanger 200 is connected with the heat pump unit 400 through the plate heat exchanger cold source water supply pump 540, and the heat pump unit 400 is connected with the heat network.

[0037] The primary spray cooling area 120 comprises the first spray layer 121 and the second spray layer 122 of the primary cooling area from bottom to top in sequence, and the primary cooling circulating pump 510 comprises the first primary cooling circulating pump 511 and the second primary cooling circulating pump 512.

[0038] The bottom of the pool 110 is connected with the first spray layer 121 through the first primary cooling circulating pump 511, and the bottom is connected with the second spray layer 122 of the primary cooling area through the second primary cooling circulating pump 512 and the plate heat exchanger 200 in sequence.

[0039] The heat pump unit 400 comprises the first heat pump unit 410 and the second heat pump unit 420, the plate heat exchanger 200 is connected with the first heat pump unit 410, and the first heat pump unit 410 is connected with the heat network.

[0040] The secondary spray cooling area 130 comprises the first spray layer 131 and the second spray layer 132 of the secondary cooling area from bottom to top in sequence, the first spray layer 131 and the second spray layer 132 of the secondary cooling area are both connected with the second heat pump unit 420, and the second heat pump unit 420 is connected with the heat network.

[0041] The bottom of the pool 110 is connected with the water using point through the blowdown pump 550, the condensate water of the pool 110 is sent to the water using point of the plant area, and the liquid level balance of the pool 110 is maintained.

[0042] The alkali tank 600 is connected with the connecting pipeline between the pool 110 and the second primary cooling circulating pump 512 through the first alkali metering pump 561, and connected with the connecting pipeline between the condensate water storage tank 300 and the secondary cooling circulating pump 520 through the second alkali metering pump 562.

[0043] The secondary cooling circulating pump 520, the demister flushing water pump 530, the plate heat exchanger cold source water pump 540, and the blowdown pump 550 are each provided with two, one for use and one for backup.

[0044] The first spray layer 121 of the primary cooling zone and the first spray layer 131 of the secondary cooling zone are each provided below with a filler layer 160.

[0045] A method for using a two-stage spray flue gas water extraction and waste heat utilization system, characterized in that it comprises the following steps:

[0046] Step 1: flue gas from the outlet flue of the absorption tower enters the primary spray cooling zone 120 through the flue gas inlet of the spray cooling tower 100; the filler layer 160 below the first spray layer 121 of the primary cooling zone uniformly distributes the flue gas while transferring heat and removing dust from the flue gas; after the spray liquid of the first spray layer 121 and the second spray layer 122 of the primary cooling zone transfers heat and removes dust from the flue gas, the flue gas enters the secondary spray cooling zone 130 through the flue gas cap of the liquid collector 150; the generated condensed water falls into the water pool 110; the temperature of the flue gas is reduced by 2-3℃ in the primary spray cooling zone 120;

[0047] Step 2: the primary cooling first circulating pump 511 extracts circulating spray water from the water pool 110 and sends it to the first spray layer 121 for circulating cooling of the flue gas;

[0048] The primary cooling second circulating pump 512 extracts circulating spray water from the water pool 110 and sends it to the plate heat exchanger 200; after the plate heat exchanger 200 cools the circulating spray water, it is sent to the second spray layer 122 of the primary cooling zone for circulating cooling of the flue gas;

[0049] Step 3: the heat exchange medium in the plate heat exchanger 200 is sent to the primary heat pump unit 410 from the cold source outlet through the plate heat exchanger cold source water pump 540; after being cooled by the evaporator of the primary heat pump unit 410, it is sent to the cold source inlet of the plate heat exchanger 200; the cold source inlet of the primary heat pump unit 410 is connected with the heat network return water, and the cold source outlet is connected with the heat network supply water, to heat the heat network return water; flue gas waste heat utilization is achieved;

[0050] Step 4: the blowdown pump 550 sends the circulating spray water in the water pool 110 to the water points in the plant area;

[0051] Step 5: after the flue gas enters the secondary spray cooling zone 130, the filler layer 160 below the first spray layer 131 of the secondary cooling zone uniformly distributes the flue gas while transferring heat from the flue gas; the spray liquid of the first spray layer 131 of the secondary cooling zone and the second spray layer 132 of the secondary cooling zone transfers heat from the flue gas; the low-temperature clean flue gas is discharged from the top of the spray cooling tower 100 and is discharged into the atmosphere through the chimney; the generated condensed water is collected by the liquid collector 150 and flows into the condensed water extraction storage tank 300; the recovery and utilization of condensed water are achieved.

[0052] Step 6: The mist eliminator flushing water pump 530 extracts the circulating spray water from the bottom of the condensate water storage tank 300 to send to the three-stage roof high-efficiency mist eliminator 140 for flushing; at the same time, the mist eliminator flushing water pump 530 also sends the circulating spray water to the process water tank.

[0053] Step 7: Since the condensate water produced by the secondary spray cooling area 130 is of high quality, the circulating spray water is extracted from the bottom of the condensate water storage tank 300 by the secondary cooling circulating pump 520 and directly sent to the secondary heat pump unit 420. The circulating spray water is cooled by the evaporator of the secondary heat pump unit 420 and then sent to the first spray layer 131 and the second spray layer 132 of the secondary cooling area for circulating cooling of the flue gas. The cold source inlet of the secondary heat pump unit 420 is connected with the heat network return water, and the cold source outlet is connected with the heat network supply water, so as to heat the heat network return water. Flue gas waste heat utilization is realized.

[0054] In actual use, since the condensate water produced by the primary spray cooling area 120 contains a large amount of solids, it is difficult to meet the low-temperature heat source water quality requirements of the primary heat pump unit 410. In order to maintain the stability of the circulating water temperature of the primary spray cooling area 120, a set of plate heat exchanger 200 is arranged in the pipeline of the second spray layer 122 of the primary cooling area to cool the circulating spray water. The cold source water in the plate heat exchanger 200 is heated, and then sent to the evaporator of the primary heat pump unit 410 for further heat exchange and cooling, and then continuously sent to the cold source inlet of the plate heat exchanger 200. The cold source water in the plate heat exchanger 200 is closed and constantly circulated at a constant temperature.

[0055] The mist eliminator flushing water pump 530 also has the function of a flue gas condensate water extraction pump, which sends the flue gas condensate water from the secondary spray cooling area 130 to the process water tank through the mist eliminator flushing water pump 530.

[0056] The circulating spray water absorbs part of the acid gas in the flue gas while reducing the temperature of the flue gas, and therefore the circulating spray water is acidic; therefore, the utility model configures the lye tank 600, the lye is sent into the inlet pipeline of the first-stage cooling second circulating pump 512 through the first lye metering pump 561, is sent into the second-stage cooling circulating pump 520 through the second lye metering pump 562, is fully mixed with the condensed water through the impeller stirring action of the first-stage cooling second circulating pump 512 and the second-stage cooling circulating pump 520, and the pH value of the water quality of the system is ensured to be maintained between 6-7; although the content of SO2 in the flue gas after desulfurization is very low, part of the SO2 can still be absorbed in the spray cooling tower 100, and the accumulated operation can cause the condensed water in the tower to be acidic; the acidic liquid can cause corrosion to the pipeline and the flow equipment (pump, heat exchanger, heat pump, etc.), and if acid-resistant metal materials are selected, the cost of the pipeline and the equipment will increase; therefore, the utility model configures the lye tank 600, and the acidic liquid is neutralized by adding alkali, and is maintained in the neutral range of the pH value 6-7.

[0057] The first spray layer 121 of the first-stage cooling zone, the second spray layer 122 of the first-stage cooling zone, the first spray layer 131 of the second-stage cooling zone and the second spray layer 132 of the second-stage cooling zone all adopt bidirectional nozzles, which can not only improve the atomization effect of a single nozzle, but also can obviously obtain dense secondary atomization effect, uniform distribution of flue gas and optimal flue gas cooling and condensation effect under the condition of optimizing and combining the arrangement of different function nozzles, so that the cooling and condensation effect is improved, the circulating amount of condensed water is saved, the number of spray layers is reduced, and the purpose of energy saving and consumption reduction is achieved.

[0058] The utility model adopts two-stage water lifting ideas, wherein the first-stage spray cooling zone 120 removes the dust in the flue gas while reducing the temperature of the flue gas, and the second-stage spray cooling zone 130 condenses the water in the flue gas while reducing the temperature of the flue gas, so that the water quality of the condensed water can be effectively controlled.

[0059] By reducing the temperature drop of the flue gas in the first-stage spray cooling zone 120 (controlling the temperature drop to be 2-3 DEG C), the water amount of the condensed water in the zone will be less, and the heat loss discharged by the blowdown pump 550 will be less; the heat released by the temperature drop of the flue gas in the zone is transferred to the first-stage circulating spray water of the first-stage spray cooling zone 120, the first-stage circulating spray water absorbs and transfers the heat to the heat network return water through the plate heat exchanger 200 and the first-stage heat pump unit 410, and most of the heat released by the temperature drop of the flue gas in the first-stage spray cooling zone 120 is recovered by the first-stage heat pump unit 410 to heat the heat network return water.

[0060] Under the condition that the overall temperature drop of the flue gas is the same, the temperature drop of the flue gas in the first-stage spray cooling zone 120 is reduced in the utility model, and the temperature drop of the flue gas in the second-stage spray cooling zone 130 is increased.

[0061] Since the primary spray cooling zone 120 has removed most of the dust in the flue gas, the secondary spray cooling zone 130 has a large amount of condensate water and the water quality is clean, the heat released by the temperature drop of the flue gas in the secondary spray cooling zone 130 is transferred to the secondary circulating spray water in the secondary spray cooling zone 130, and the low-quality heat of the circulating spray water is recovered and heated by the secondary heat pump unit 420 to heat the network return water.

[0062] Compared with the prior art, the utility model under the premise of meeting the cooling circulating water quality requirement of the heat pump unit 400, effectively reduces the intermediate heat exchange link, also reduces the heat exchange equipment configuration, maximum limit releases the heat of flue gas cooling through heat pump unit 400 recycling.

[0063] Example 1

[0064] The utility model will be further illustrated below in combination with actual parameters, but will not limit the utility model in the range of the described embodiments.

[0065] A two-stage spray flue gas water extraction and waste heat utilization system and a use method thereof, comprising the following steps:

[0066] Step 1: the clean flue gas (about 1290000Nm 3 / h, 51℃, dust content about 30mg / Nm 3 ) from the outlet flue of the absorption tower enters the primary spray cooling zone 120 of the spray cooling tower 100, the filler layer 160 below the first spray layer 121 of the primary cooling zone uniformly distributes the flue gas while transferring heat and removing dust from the flue gas, after the spray liquid of the first spray layer 121 of the primary cooling zone and the second spray layer 122 of the primary cooling zone transfers heat and removes dust from the flue gas, the flue gas enters the secondary spray cooling zone 130 from the flue cap of the liquid collector 150;

[0067] In the primary spray cooling zone 120, the flue gas is reduced from 51℃ to 49℃, producing 10.7t / h of condensate water, which falls into the water pool 110; the dust removal efficiency of the primary spray cooling zone 120 is about 70%, and the dust content of the flue gas is reduced from 30mg / Nm 3 to 9mg / Nm 3 .

[0068] Step 2: the primary cooling first circulating pump 511 and the primary cooling second circulating pump 512 are unitized; the primary cooling first circulating pump 511 extracts 1500m 3 / h of circulating spray water from the water pool 110 to the first spray layer 121 for circulating cooling of the flue gas;

[0069] In order to maintain the stability of the circulating water temperature of the primary spray cooling zone 120, the primary cooling second circulating pump 512 extracts 1400m 3 / h circulating spray water is sent to the plate heat exchanger 200, and the plate heat exchanger 200 cools the 1400m 3 / h circulating spray water from 52℃ to 47℃, and the temperature of the cold source water (800m 3 / h) of the plate heat exchanger 200 is increased from 22℃ to 30.6℃; the cooled circulating spray water is sent to the second spray layer 122 of the primary cooling area to cool the flue gas circulatingly;

[0070] Step 3: The 800m 3 / h, 30.6℃ water from the cold source outlet of the plate heat exchanger 200 is sent to the primary heat pump unit 410 through the plate heat exchanger cold source water pump 540, and is cooled to 22℃ after heat exchange through the evaporator of the primary heat pump unit 410, and is then sent to the cold source inlet of the plate heat exchanger 200; the cold source inlet of the primary heat pump unit 410 is connected with the heat network return water, and the cold source outlet is connected with the heat network supply water, so as to heat the heat network return water; flue gas waste heat utilization is realized;

[0071] Step 4: The circulating spray water in the pool 110 is sent to the water points in the factory area by the blowdown pump 550; the condensate water in the pool 110 is sent to the water points in the factory area to maintain the liquid level balance of the pool 110.

[0072] Step 5: The flue gas (about 1290000Nm 3 / h, 49℃, containing about 9mg / Nm 3 ) enters the secondary spray cooling area 130, the filler layer 160 below the secondary spray cooling area first spray layer 131 uniformly distributes the flue gas while transferring heat to the flue gas, the spray liquid of the secondary spray cooling area first spray layer 131 and the secondary spray cooling area second spray layer 132 transfers heat to the flue gas, the flue gas with a mist content of less than 20mg / Nm 3 of the third ridge high-efficiency mist eliminator 140 is removed, and the low-temperature clean flue gas is discharged from the top of the spray cooling tower 100, connected with the inlet flue of the wet electric mist eliminator of the absorption tower, and finally discharged into the atmosphere through the chimney; in the secondary spray cooling area 130, the flue gas is cooled from 49℃ to 34℃, and the condensate water of 69.3t / h is collected by the liquid collecting tray 150 and flows into the condensate water storage tank 300; the recovery and utilization of the condensate water are realized.

[0073] By increasing the contact area and liquid discharge capacity, reasonably selecting the blade type and spacing, optimizing the flushing system, strictly following the clearance design to ensure the uniformity of the flow field before and after the mist eliminator, etc., the liquid droplet at the outlet of the third ridge high-efficiency mist eliminator 140 is stably controlled to be less than 20mg / Nm 3 .

[0074] Step 6: Two mist eliminator flushing water pumps 530 are provided, one for use and one for standby; the mist eliminator flushing water pump 530 extracts 150m 3 / The circulating spray water is sent to the three-stage ridge high-efficiency demister 140 to flush the three-stage ridge high-efficiency demister 140; at the same time, the demister flushing water pump 530 has the function of a flue gas condensate water lifting pump, and the flue gas condensate water in the secondary spray cooling area 130 is sent to the process water tank through the demister flushing water pump 530.

[0075] Step 7: The secondary cooling circulating pump 520 is provided with two pumps in a mother pipe mode, one for use and one for standby; the condensate water generated in the secondary spray cooling area 130 has high quality, and is extracted from the bottom of the condensate water lifting storage tank 300 through the secondary cooling circulating pump 520 at a flow rate of 3000 m 3 The circulating spray water is directly sent to the secondary heat pump unit 420, and the circulating spray water is cooled to 32 DEG C through the evaporator of the secondary heat pump unit 420 and then is sent to the first spray layer 131 of the secondary cooling area and the second spray layer 132 of the secondary cooling area to cool the flue gas; the cold source inlet of the secondary heat pump unit 420 is connected with the heat network return water, and the cold source outlet is connected with the heat network supply water, so that the heat network return water is heated; and the flue gas waste heat utilization is realized.

[0076] The specific data are shown in the following table:

[0077]

[0078]

[0079] Example 2

[0080] The difference between the embodiment and the embodiment 1 lies in that in step 1, in the primary spray cooling area 120, the flue gas is reduced from 51 DEG C to 46 DEG C.

[0081] The specific data are shown in the following table:

[0082] No. Comparative item Unit Example 2 Flue gas amount at the inlet of the spray cooling tower 100 Nm3 / h ～12900 Flue gas temperature at the inlet of the spray cooling tower 100 ℃ ～51 Outlet flue gas temperature of the primary spray cooling zone 120 ℃ ～46 Outlet flue gas temperature of the secondary spray cooling zone 130 ℃ ～34 Total released heat of flue gas condensation MW 61 Condensed water amount generated by the primary spray cooling zone 120 m 3 / h]]> 29.5 Cooling water amount of the primary circulating spray water m 3 / h]]> 2400 Water temperature of the primary circulating spray water ℃ ～44 Water temperature of the pool 110 ℃ ～52 Condensed water amount generated by the secondary spray cooling zone 130 m 3 / h]]> 50.5 Cooling water amount of the secondary circulating spray water m 3 / h]]> 3200 Water temperature of the condensed water extraction storage tank 300 ℃ ～43 Heat carried by the drainage from the primary spray cooling zone 120 kJ / h ～6443 Heat carried by the drainage from the secondary spray cooling zone 130 kJ / h ～9120 Total heat carried by the drainage kJ / h 15563 Input low-temperature heat source of the heat pump (ignoring heat loss in the transportation process) kJ / h 204037 Coefficient of performance of the heat pump COP 1.7 Heat of the return water of the heating network kJ / h 495518

[0083] Example 3

[0084] The difference between the embodiment and the embodiment 1 lies in that in step 1, in the primary spray cooling area 120, the flue gas is reduced from 51 DEG C to 43 DEG C.

[0085] The specific data are shown in the following table:

[0086] No. Comparative item Unit Example 3 Flue gas amount at the inlet of the spray cooling tower 100 Nm3 / h ～12900 Flue gas temperature at the inlet of the spray cooling tower 100 ℃ ～51 Outlet flue gas temperature of the primary spray cooling zone 120 ℃ ～43 Outlet flue gas temperature of the secondary spray cooling zone 130 ℃ ～34 Total released heat of flue gas condensation MW 61 Condensed water amount generated by the primary spray cooling zone 120 m3 / h 45.3 Cooling water amount of the primary circulating spray water m3 / h 2700 Water temperature of the primary circulating spray water ℃ ～41 Water temperature of the pool 110 ℃ ～52 Condensed water amount generated by the secondary spray cooling zone 130 m3 / h 34.7 Cooling water amount of the secondary circulating spray water m3 / h 2000 Water temperature of the condensed water extraction storage tank 300 ℃ ～43 Heat carried by the drainage from the primary spray cooling zone 120 kJ / h ～9894 Heat carried by the drainage from the secondary spray cooling zone 130 kJ / h ～6267 Total heat carried by the drainage kJ / h 16161 Input low-temperature heat source of the heat pump (ignoring heat loss in the transportation process) kJ / h 203439 Coefficient of performance of the heat pump COP 1.7 Heat of the return water of the heating network kJ / h 494066

[0087] According to the embodiments 1-3, it can be known that in the utility model, when the temperature of the flue gas is reduced by 2 DEG C in the primary spray cooling area 120, the total heat carried by the discharged water is the least, and the heat of the heat network return water is the highest; the embodiment 1 is the preferred embodiment.

[0088] In summary, the utility model discloses hierarchical spray cooling, primary spray cooling area 120 is washed away most dust while cooling flue gas, this area controls the temperature drop of flue gas to be 2-3 DEG C, and the amount of condensate water is small, and the solid content of corresponding condensate water is relatively large, and the water quality is poor, is discharged to the water point for use by blowdown pump 550;Secondary spray cooling area 130 mainly cools flue gas, the temperature drop of flue gas in this area is large, and the amount of condensate water is large, and the solid content is extremely low, can realize the recovery rate of a large amount of high-quality condensate water, increase the application range of recovered water, and reduce the water supply of desulfurization system;The utility model effectively realizes the hierarchical control of condensate water quality.

[0089] In primary spray cooling area 120, the utility model discloses indirect heat exchange, and the heat released by the temperature drop of flue gas in this area is transferred to primary circulating spray water in primary spray cooling area 120, and the heat is absorbed by plate heat exchanger 200 and primary heat pump unit 410 and is transferred to heat network return water, so that most of the heat released by the temperature drop of flue gas in primary spray cooling area 120 is recovered and heated by primary heat pump unit 410 to heat network return water;In secondary spray cooling area, the amount of condensate water in secondary spray cooling area 130 is large, and the water quality is clean, and the heat released by the temperature drop of flue gas in secondary spray cooling area 130 is transferred to secondary circulating spray water in secondary spray cooling area 130, and the low-quality heat of circulating spray water is recovered and heated to heat network return water by secondary heat pump unit 420;Under the premise of meeting the quality requirement of heat pump unit 400 for cooling circulating water, the utility model effectively reduces the intermediate heat exchange link, also reduces the heat exchange equipment configuration, and maximizes the heat released by flue gas cooling to be recycled by heat pump unit 400.

[0090] Other unexplained parts belong to the prior art.

Claims

1. A two-stage spray flue gas water extraction and waste heat utilization system, characterized in that: The application relates to a cooling system, which comprises a spray cooling tower (100), a plate heat exchanger (200), a condensing water storage tank (300) and a heat pump unit (400), wherein the spray cooling tower (100) is internally provided with, from bottom to top, a pool (110), a first-stage spray cooling area (120), a second-stage spray cooling area (130) and a third-stage ridge high-efficiency demister (140); the pool (110) is provided with a spray cooling tower (100) inlet between the pool (110) and the first-stage spray cooling area (120); a collecting tray (150) is arranged between the first-stage spray cooling area (120) and the second-stage spray cooling area (130). The pool (110) is sequentially connected with the first-stage spray cooling area (120) through a first-stage cooling circulating pump (510) and the plate heat exchanger (200) at the bottom of the pool (110). The collecting tray (150) is sequentially connected with the second-stage spray cooling area (130) through the condensing water storage tank (300), a second-stage cooling circulating pump (520) and the heat pump unit (400). The first-stage spray cooling area (120) sequentially comprises a first-stage cooling area first spray layer (121) and a first-stage cooling area second spray layer (122) from bottom to top. The second-stage spray cooling area (130) sequentially comprises a second-stage cooling area first spray layer (131) and a second-stage cooling area second spray layer (132) from bottom to top. The first-stage cooling area first spray layer (121) and the second-stage cooling area first spray layer (131) are both provided with a filler layer (160) below. The condensing water storage tank (300) is connected with the third-stage ridge high-efficiency demister (140) and a process water tank through a demister flushing water pump (530). The plate heat exchanger (200) is connected with the heat pump unit (400) through a plate exchanger cold source water supply pump (540), and the heat pump unit (400) is connected with a heat network.

2. The two-stage spray flue gas water extraction and waste heat utilization system according to claim 1, characterized in that: The first-stage cooling circulating pump (510) comprises a first-stage cooling first circulating pump (511) and a first-stage cooling second circulating pump (512). The pool (110) is connected with the first-stage cooling area first spray layer (121) through the first-stage cooling first circulating pump (511) at the bottom of the pool (110) and is sequentially connected with the first-stage cooling area second spray layer (122) through the first-stage cooling second circulating pump (512) and the plate heat exchanger (200) at the bottom of the pool (110).

3. The two-stage spray flue gas water extraction and waste heat utilization system according to claim 2, characterized in that: The heat pump unit (400) comprises a first-stage heat pump unit (410) and a second-stage heat pump unit (420); the plate heat exchanger (200) is connected with the first-stage heat pump unit (410), and the first-stage heat pump unit (410) is connected with the heat network.

4. The two-stage spray flue gas water extraction and waste heat utilization system according to claim 3, characterized in that: The second-stage cooling area first spray layer (131) and the second-stage cooling area second spray layer (132) are both connected with the second-stage heat pump unit (420); and the second-stage heat pump unit (420) is connected with the heat network.

5. The two-stage spray flue gas water extraction and waste heat utilization system according to claim 4, characterized in that: The pool (110) is connected with a water using point through a blowdown pump (550) at the bottom of the pool (110).

6. The two-stage spray flue gas water extraction and waste heat utilization system according to claim 5, characterized in that: Also include lye tank (600); the lye tank (600) is connected through the first lye metering pump (561) with the connection pipeline between the pool (110) and the first cooling second circulating pump (512), is connected through the second lye metering pump (562) with the connection pipeline between the condensate water storage tank (300) and the secondary cooling circulating pump (520).

7. The two-stage spray flue gas water extraction and waste heat utilization system according to claim 6, characterized in that: The secondary cooling circulating pump (520), the demister flushing water pump (530), the plate exchange cold source water pump (540), the blowdown pump (550) are all provided with two, one is a spare.

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