A water-saving and consumption-reducing flue gas wastewater concentration system and method

Abstract

The present invention discloses a water-saving and energy-saving flue gas wastewater concentration system and method. A demister is arranged in the outlet flue. Among them, a washing water collection tank matched with the demister is arranged at the bottom of the outlet flue. The outlet of the washing water collection tank is divided into two paths. One path is communicated with the concentration tower through a third valve, and the other path is communicated with the clean water tank through a fourth valve and a filter. A water replenishing device is communicated with the clean water tank. The outlet of the clean water tank is divided into two paths after passing through a washing water pump. One path is communicated with the desulfurization tower through a first valve, and the other path is communicated with the washing water inlet of the demister. This system and method can effectively reduce the height of the flue gas wastewater concentration system and reduce the volume of the flue gas wastewater concentration system; by avoiding the direct inflow of washing water into the flue gas and water concentration system, the system energy consumption is reduced; the reuse of the demister washing water is realized, achieving the purpose of water conservation.

Description

Technical Field

[0001] The invention belongs to the technical field of desulfurized wastewater treatment in thermal power plants, and relates to a water-saving and energy-consuming-reducing flue gas wastewater concentration system and method. Background Art

[0002] The flue gas wastewater concentration system is a method for evaporating wastewater by using the waste heat of the flue gas at the tail of the boiler to achieve waste treatment with waste and desulfurized wastewater reduction. It is generally arranged between the dust collector and the desulfurization tower and will not affect the desulfurized wastewater system. The flue gas wastewater concentration system extracts part of the flue gas before entering the desulfurization tower. The flue gas enters the concentration tower from bottom to top, and the desulfurized wastewater is sprayed from top to bottom by a circulating pump. The flue gas uses its own temperature to evaporate the wastewater to achieve the purpose of concentrating the desulfurized wastewater, and the droplets carried in the flue gas are generally removed by a demister.

[0003] The flue gas wastewater concentration system well realizes the recovery of low-grade waste heat and improves the energy utilization efficiency. However, the existing demister of the flue gas wastewater concentration system is an in-built type, which has the disadvantage of large volume and increases the construction cost; the washing water of the demister cannot be reused, and the washing water directly flows into the flue gas wastewater concentration tower and re-enters the flue gas-water concentration circulation system, increasing the energy consumption and water consumption of the flue gas-water concentration system. Summary of the Invention

[0004] The purpose of the invention is to overcome the above-mentioned disadvantages of the prior art and provide a water-saving and energy-consuming-reducing flue gas wastewater concentration system and method, which can effectively reduce the height of the flue gas wastewater concentration system and reduce the volume of the flue gas wastewater concentration system; reduce the system energy consumption by avoiding the direct flow of washing water into the flue gas-water concentration system; realize the reuse of the washing water of the demister to achieve the purpose of water saving.

[0005] To achieve the above purpose, the water-saving and energy-consuming-reducing flue gas wastewater concentration system of the invention includes a concentration tower, a clean water tank, a water replenishing device, a washing water pump, a desulfurization tower, a first valve, a second valve, a flue gas demister, a washing water collection tank, a third valve, a fourth valve and a filter;

[0006] The top outlet of the concentration tower is connected to the inlet flue of the desulfurization tower through an outlet flue. A flue gas demister is arranged in the outlet flue. Wherein, a washing water collection tank matched with the flue gas demister is arranged at the bottom of the outlet flue. The outlet of the washing water collection tank is divided into two paths. One path is connected to the concentration tower through a third valve, and the other path is connected to the clean water tank through a fourth valve and a filter. The water replenishing device is connected to the clean water tank. The outlet of the clean water tank is divided into two paths after passing through the washing water pump. One path is connected to the desulfurization tower through a first valve, and the other path is connected to the washing water inlet of the flue gas demister through a second valve. The inlet flue of the desulfurization tower is connected to the desulfurization tower.

[0007] A pH meter 3 is arranged in the clean water tank.

[0008] The flue gas demister is an N-stage demister, where N is greater than or equal to 3.

[0009] The water-saving and energy-saving flue gas wastewater concentration method of the present invention includes the following steps:

[0010] During the operation of the concentration tower, when the droplets carried by the flue gas pass through the flue gas demister, the droplets flow into the flushing water collection tank due to inertial force during the contact with the flue gas demister. At this time, the fourth valve is in the closed state, and the third valve is in the open state. The demisting water is collected by the flushing water collection tank and then flows into the concentration tower by gravity.

[0011] When the flue gas demister reaches the state that needs to be flushed, the clean water tank transports the flushing water to the flue gas demister through the flushing water pump. The duration of a single flushing process of the flue gas demister is As. Among them, within Bs before a single flushing process, the flushing water collected by the flushing water collection tank flows into the concentration tower by gravity. During this process, the fourth valve remains in the closed state, and the third valve remains in the open state. During the remaining (A - B)s flushing process, the third valve remains in the closed state, and the fourth valve remains in the open state. The flushing water collected by the flushing water collection tank is filtered by the filter and then flows into the clean water tank. After a single flushing process is completed, the water replenishing device replenishes the clean water tank to the normal water level.

[0012] When the pH value of the water in the clean water tank is lower than 5, all the water in the clean water tank is discharged to the desulfurization tower through the flushing water pump. At this time, the second valve is in the closed state, and the first valve is in the open state. After the clean water tank is drained, the water replenishing device replenishes the clean water tank to the normal liquid level.

[0013] The duration of a single flushing process of the flue gas demister is 60s.

[0014] The number of flushing recycling times n of the water in the clean water tank = c(H + ) ÷ c 1 (H + ), where c(H + ) is the total accumulated concentration of H + during the flushing process, c(H + ) = 10 -m - 10 -7 , m is the pH set value for draining the clean water tank, and c 1 (H + ) is the concentration of H + increased during a single flushing process.

[0015] B = 5.

[0016] B = 8.

[0017] The present invention has the following beneficial effects:

[0018] When the water-saving and energy-consuming flue gas wastewater concentration system and method according to the present invention are specifically operated, the flue gas demister is arranged in the outlet flue to reduce the height of the flue gas wastewater concentration system and reduce the volume of the flue gas wastewater concentration system; at the same time, a washing water collection tank is arranged in cooperation with the flue gas demister, and most of the washing water in the washing water collection tank is discharged to the clear water tank by gravity flow, effectively realizing the separate collection of washing water and avoiding a large amount of washing water from directly flowing into the concentration tower to reduce the system energy consumption; during the washing process, the washing water with poor quality directly flows into the concentration tower, and the washing water with good quality enters the clear water tank after the suspended matter contained therein is filtered by a filter. At the same time, the clear water tank is provided with a water replenishing device, and the recycling of the high-quality washing water for the flue gas demister increases the recycling times of the flue gas demister washing water, effectively saving water resources while ensuring the quality of the washing water. Brief Description of the Drawings

[0019] Figure 1 It is a structural schematic diagram of the present invention.

[0020] Among them, 1 is the concentration tower, 2 is the clear water tank, 3 is the pH meter, 4 is the water replenishing device, 5 is the washing water pump, 6 is the desulfurization tower, 7 is the first valve, 8 is the second valve, 9 is the flue gas demister, 10 is the washing water collection tank, 11 is the third valve, 12 is the fourth valve, and 13 is the filter. Detailed Embodiments

[0021] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the present invention disclosure. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0022] The structural schematic diagram according to the disclosed embodiments of the present invention is shown in the drawings. These figures are not drawn to scale, and for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures and their relative sizes and positional relationships are only exemplary, and may actually deviate due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0023] Reference Figure 1, the water-saving and energy-saving flue gas wastewater concentration system of the present invention includes a concentration tower 1, a clear water tank 2, a pH meter 3, a water replenishing device 4, a flushing water pump 5, a desulfurization tower 6, a first valve 7, a second valve 8, a flue gas demister 9, a flushing water collection tank 10, a third valve 11, a fourth valve 12 and a filter 13;

[0024] The top outlet of the concentration tower 1 is connected to the inlet flue of the desulfurization tower 6 through an outlet flue, and a flue gas demister 9 is arranged in the outlet flue. Among them, a flushing water collection tank 10 matched with the flue gas demister 9 is arranged at the bottom of the outlet flue. Among them, the outlet of the flushing water collection tank 10 is divided into two paths, one path is connected to the concentration tower 1 through the third valve 11, and the other path is connected to the clear water tank 2 through the fourth valve 12 and the filter 13. The water replenishing device 4 is connected to the clear water tank 2, and a pH meter 3 is arranged in the clear water tank 2. The outlet of the clear water tank 2 is divided into two paths after passing through the flushing water pump 5. One path is connected to the desulfurization tower 6 through the first valve 7, and the other path is connected to the flushing water inlet of the flue gas demister 9 through the second valve 8. The inlet flue of the desulfurization tower 6 is connected to the desulfurization tower 6.

[0025] The flue gas demister 9 is an N-stage demister, N is greater than or equal to 3, and the flue gas demister 9 can ensure that the droplet carry-over amount of the outlet flue gas is not higher than 150 mg / m 3 .

[0026] The discharge mode of the clear water tank 2 is intermittent and will not affect the desulfurization system. The number of flushing and recycling times of the water in the clear water tank 2 is calculated according to the formula n = c(H + )÷c 1 (H + ), where n is the number of flushing and recycling times of the water in the clear water tank 2, c(H + ) is the total concentration of H + accumulated during the flushing process, c(H + ) = 10 -m -10 -7 , m is the pH set value of the drained water of the clear water tank 2, and c 1 (H + ) is the increased H + concentration during one flushing process.

[0027] The working process of the present invention is as follows:

[0028] During the operation of the concentration tower 1, when the droplets carried by the flue gas pass through the flue gas demister 9, the droplets flow into the flushing water collection tank 10 due to the action of inertial force during the contact with the flue gas demister 9. At this time, the fourth valve 12 is in the closed state and the third valve 11 is in the open state. The demisting water is collected by the flushing water collection tank 10 and flows into the concentration tower 1 by gravity.

[0029] When the flue gas demister 9 reaches the state that needs to be flushed, the clean water tank 2 transports the flushing water to the flue gas demister 9 through the flushing water pump 5. Generally, the duration of a single flushing process of the flue gas demister 9 is 60 s. Within the first 5 s of a single flushing process, the flushing water collected by the flushing water collection tank 10 flows into the concentration tower 1 by gravity. During this process, the fourth valve 12 is kept closed and the third valve 11 is kept open. During the remaining 55 s of the flushing process, the third valve 11 is kept closed and the fourth valve 12 is kept open. The flushing water collected by the flushing water collection tank 10 flows into the clean water tank 2 after being filtered by the filter 13. After a single flushing process is completed, the water replenishing device 4 replenishes water to the clean water tank 2 to the normal water level. During the cyclic flushing process, the pH value of the water in the clean water tank 2 will gradually decrease. When the pH value of the water in the clean water tank 2 is lower than 5, all the water in the clean water tank 2 is discharged into the desulfurization tower 6 through the flushing water pump 5. At this time, the second valve 8 is kept closed and the first valve 7 is kept open. After the clean water tank 2 is drained, the water replenishing device 4 replenishes water to the clean water tank 2 to the normal liquid level.

[0030] Embodiment 1

[0031] During the initial flushing, the water replenishing device 4 replenishes water to the clean water tank 2 to an appropriate liquid level, starts the flushing water pump 5, and flushes the flue gas demister 9 with the clean water in the clean water tank 2. Among them, within the first 5 s of the flushing process, the flushing water collected by the flushing water collection tank 10 flows into the concentration tower 1 by gravity. During this process, the fourth valve 12 is kept closed and the third valve 11 is kept open. During the remaining 55 s of the flushing process, the third valve 11 is kept closed and the fourth valve 12 is kept open. The flushing water collected by the flushing water collection tank 10 flows into the filter 13 and then into the clean water tank 22 after being filtered by the filter 13. The water replenishing device 4 replenishes water to the clean water tank 2 to the normal water level. Generally, after continuously flushing 20 times, when the pH value of the water in the clean water tank 2 is lower than 5, all the water in the clean water tank 2 is discharged into the desulfurization tower 6, and the water replenishing device 4 replenishes water to the clean water tank 2 to the normal water level.

[0032] Embodiment 2

[0033] During the initial flushing, the water replenishing device 4 replenishes water to the clear water tank 2 to an appropriate liquid level. The flushing water pump 5 is started, and the clear water output from the clear water tank 2 is used to flush the flue gas demister 9. Before the first 8 s of the flushing process, the flushing water collected by the flushing water collection tank 10 flows into the concentration tower 1. At this time, the fourth valve 12 is kept closed, and the third valve 11 is kept open. Then, during the remaining 52 s of the flushing process, the third valve 11 is kept closed, and the fourth valve 12 is kept open. The flushing water collected by the flushing water collection tank 10 is filtered by the filter 13 and then sent into the clear water tank 2. The water replenishing device 4 replenishes water to the clear water tank 2 to the normal water level. When the differential pressure of the flue gas demister 9 or the continuous operation time of the concentration tower 1 meets the flushing condition, the next flushing sequence starts. After continuous flushing twice, when the pH value of the water in the clear water tank 2 is lower than 6, the water in the clear water tank 2 is completely discharged to the desulfurization tower 6 at this time, and the water replenishing device 4 replenishes water to the clear water tank 2 to the normal water level.

Claims

1. A method for concentrating flue gas wastewater with water conservation and energy consumption reduction, characterized in that, based on a water-saving and energy-consuming flue gas wastewater concentration system, the water-saving and energy-consuming flue gas wastewater concentration system includes a concentration tower (1), a clear water tank (2), a water replenishing device (4), a flushing water pump (5), a desulfurization tower (6), a first valve (7), a second valve (8), a flue gas demister (9), a flushing water collection tank (10), a third valve (11), a fourth valve (12) and a filter (13); The top outlet of the concentration tower (1) is connected to the inlet flue of the desulfurization tower (6) through an outlet flue, and a flue gas demister (9) is arranged in the outlet flue. Among them, a flushing water collection tank (10) matched with the flue gas demister (9) is arranged at the bottom of the outlet flue. Among them, the outlet of the flushing water collection tank (10) is divided into two paths. One path is connected to the concentration tower (1) through the third valve (11), and the other path is connected to the clear water tank (2) through the fourth valve (12) and the filter (13). The water replenishing device (4) is connected to the clear water tank (2). The outlet of the clear water tank (2) is divided into two paths after passing through the flushing water pump (5). One path is connected to the desulfurization tower (6) through the first valve (7), and the other path is connected to the flushing water inlet of the flue gas demister (9) through the second valve (8). The inlet flue of the desulfurization tower (6) is connected to the desulfurization tower (6); A pH meter (3) is arranged in the clear water tank (2); including the following steps: During the operation of the concentration tower (1), when the fog droplets carried by the flue gas pass through the flue gas demister (9), the fog droplets flow into the flushing water collection tank (10) due to inertial force during the contact with the flue gas demister (9). At this time, the fourth valve (12) is in the closed state, and the third valve (11) is in the open state. The demisting water is collected by the flushing water collection tank (10) and flows into the concentration tower (1) by gravity; When the flue gas demister (9) reaches the state that needs to be flushed, the clear water tank (2) transports the flushing water to the flue gas demister (9) through the flushing water pump (5). The duration of a single flushing process of the flue gas demister (9) is As. Among them, within Bs before a single flushing process, the flushing water collected by the flushing water collection tank (10) flows into the concentration tower (1) by gravity. During this process, the fourth valve (12) is kept in the closed state, and the third valve (11) is in the open state. During the remaining (A - B)s flushing process, the third valve (11) is kept in the closed state, and the fourth valve (12) is in the open state. The flushing water collected by the flushing water collection tank (10) is filtered by the filter (13) and then flows into the clear water tank (2). After a single flushing process is completed, the water replenishing device (4) replenishes water to the clear water tank (2) to the normal water level; When the pH value of the water in the clear water tank (2) is lower than 5, all the water in the clear water tank (2) is discharged into the desulfurization tower (6) through the flushing water pump (5). At this time, the second valve (8) is in the closed state, and the first valve (7) is in the open state. After the clear water tank (2) is drained, the water replenishing device (4) replenishes water to the clear water tank (2) to the normal liquid level.

2. The water-saving and consumption-reducing flue gas wastewater concentration method according to claim 1, characterized in that, the duration of the first flushing process of the flue gas demister (9) is 60 s.

3. The water-saving and consumption-reducing flue gas wastewater concentration method according to claim 1, characterized in that, The number of times n of the flushing and recycling of water in the clean water tank (2) = c(H + ) ÷ c 1 (H + ), where c(H + ) is the total concentration of H + accumulated during the flushing process, c(H + ) = 10 -m -10 -7 , m is the pH set value for draining the clean water tank (2), and c 1 (H + ) is the concentration of H + increased during one flushing process.

4. The water-saving and consumption-reducing flue gas wastewater concentration method according to claim 1, characterized in that, B＝5。 5. The water-saving and consumption-reducing flue gas wastewater concentration method according to claim 1, characterized in that, B＝8。 6. The water-saving and consumption-reducing flue gas wastewater concentration method according to claim 1, characterized in that, the flue gas demister (9) is an N-stage demister, where N is greater than or equal to 3.

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