CN110877918A - System and method for treating high-salinity wastewater by using high-temperature ash - Google Patents

Abstract

The present invention provides a system for treating high-salt wastewater by using high-temperature ash and slag, comprising a drum slag cooler, a slag inlet pipe, a slag discharge pipe, a high-salt wastewater storage tank, a first flow regulating door, a second flow regulating door, and a cooling water inlet , cooling water outlet, slag inlet temperature measurement point, slag outlet temperature measurement point and cooling water return water temperature measurement point, the invention makes full use of the waste heat of the high-temperature bottom slag, and treats part of the high salt without affecting the boiler efficiency and boiler operation. Wastewater (the amount of treatment is related to the amount of slag discharge) is a beneficial supplement to the traditional zero-discharge process, and has the advantages of good evaporation effect, high equipment utilization rate, and low investment and operation and maintenance costs.

Description

A system and method for treating high-salt wastewater with high-temperature ash and slag

technical field

The invention relates to the field of thermal power plant water treatment, in particular to a system and method for treating high-salt wastewater by utilizing high-temperature ash and slag.

Background technique

In recent years, the Chinese government has become more and more strict in the supervision of wastewater discharge from industrial enterprises. The "Ten Water Regulations" promulgated in 2015 clearly pointed out that "comprehensive control of pollutant discharge" should be implemented, and water environmental protection has been raised to the national strategic level. Provinces and cities have successively promulgated relevant regulations on up-to-standard and zero-discharge wastewater, and some thermal power plants have begun to carry out zero-discharge transformation of plant-wide wastewater.

The wastewater produced by thermal power plants mainly includes reverse osmosis concentrated water, circulating water sewage, coal-containing wastewater, oil-containing wastewater, domestic wastewater, desulfurization wastewater, etc. Among them, reverse osmosis concentrated water, circulating water sewage and desulfurization wastewater belong to high-salt wastewater, which is characterized by very high salt content, COD and other indicators. Especially desulfurization wastewater, the soluble salt content exceeds 35,000 mg/L. Therefore, high-salt wastewater is the biggest obstacle for thermal power plants to achieve zero discharge of wastewater in the whole plant.

At present, there are mainly two processes for zero-discharge treatment of high-salt wastewater: (1) concentration + evaporative crystallization. Concentration generally adopts reverse osmosis membrane (or DTRO membrane) or high-temperature concentration process of flue gas to concentrate high-salt wastewater into a small amount of High-concentration wastewater, and then use evaporation equipment to evaporate the concentrated water to dryness. Commonly used evaporation equipment is multi-effect evaporation crystallization (MED), steam mechanical compression crystallization (MVR) and natural evaporation crystallization (NED). (2) Concentration + flue evaporation, the concentration process is the same as the first method, and the flue evaporation process is divided into flue direct evaporation and flue bypass evaporation. Flue direct evaporation is to inject concentrated water directly into the high-temperature flue. The injection point is generally at the horizontal flue at the furnace outlet, and the high-temperature flue gas is used to quickly evaporate the waste water; the flue bypass evaporation is to take the flue gas before the air preheater ( about 300°C), and the waste water is evaporated to dryness by passing into the evaporation tower. The above two processes have engineering applications in China. The evaporation crystallization process has no effect on the operation of the boiler, but the investment and operation and maintenance costs are high; the flue evaporation process will slightly reduce the efficiency of the boiler and may also affect the operation of the boiler. The advantage is that the investment and lower operating costs.

The roller slag cooler is an important auxiliary machine of the circulating fluidized bed (CFB) boiler. The drum slag cooler can be used to treat high-salt wastewater, mainly based on: (1) the slag inlet temperature in the drum slag cooler is about 900 ℃, which can quickly evaporate the high-salt wastewater; (2) the high-salt wastewater is evaporated to dryness The crystalline salt precipitated later is discharged together with the bottom slag, without the risk of pollution; (3) The waste heat of the bottom slag is fully utilized to evaporate the waste water, and it has no effect on the boiler efficiency and boiler operation.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a system and method for treating high-salt wastewater by using high-temperature ash and slag, which solves the defects of high cost and low efficiency in the existing high-salt wastewater treatment.

In order to achieve the above object, the technical scheme adopted in the present invention is:

The present invention provides a system for treating high-salt wastewater by using high-temperature ash and slag, including a drum slag cooler, a slag inlet pipe, a slag discharge pipe, a high-salt wastewater storage tank, a first flow regulating door, a second flow regulating door, and a cooling water inlet , cooling water outlet, slag inlet temperature measurement point, slag outlet temperature measurement point and cooling water return water temperature measurement point, wherein the cooling water inlet and cooling water outlet set on the drum slag cooler are respectively the same as the ones on the high-salt wastewater storage tank. The waste water outlet is connected with the waste water inlet to form a circulation loop of cooling water; the feed port provided on the drum slag cooler is connected with a slag feed pipe; the slag discharge port provided on the drum slag cooler is connected with a slag outlet pipe; The slag inlet pipe, the slag outlet pipe and the cooling water return pipe are respectively provided with a slag inlet temperature measurement point, a slag outlet temperature measurement point and a cooling water return temperature measurement point; the cooling water outlet on the high-salt waste water storage tank It is also communicated with the slag inlet pipe; the cooling water outlet on the high-salt waste water storage tank and the connecting pipe between the slag inlet pipe and the roller slag cooler are respectively provided with a first flow regulating door and a second flow regulating door.

Preferably, a booster pump is provided at the cooling water outlet of the high-salt wastewater storage tank.

Preferably, the drum slag cooler is further provided with a front dust extraction pipe and a rear dust extraction pipe, the front dust extraction pipe is arranged on one side of the slag inlet; the rear dust extraction pipe is arranged on the slag discharge port mouth side.

Preferably, the top of the drum slag cooler is also provided with a safety valve.

Preferably, the roller slag cooler is fixed and limited by equipment support.

A method for utilizing high-temperature ash and slag to treat high-salt wastewater, based on the described system for utilizing high-temperature ash and slag to treat high-salt wastewater, comprising the following steps:

Under the condition of normal operation of the drum slag cooler, adjust the first flow control gate and the second flow control gate to an appropriate opening, so that after the system runs stably, the slag discharge temperature measurement point is kept at (110-120) °C, and the cooling water returns to The water temperature measuring point is kept at 95°C, where:

When the temperature at the slagging pipe is lower than 110℃, reduce the opening of the first flow control valve until the slag temperature returns to the normal range;

When the temperature at the slag discharge pipe is higher than 120℃, slowly increase the opening of the first flow control door until the slag discharge temperature returns to the normal range;

When the temperature on the cooling water return pipe is higher than 95°C, reduce the opening of the second flow control valve and increase the original cooling water volume until the cooling water return temperature returns to normal.

Compared with the prior art, the beneficial effects of the present invention are:

The invention provides a system and method for treating high-salt wastewater by using high-temperature ash and slag. For a circulating fluidized bed (CFB) boiler, the existing drum slag cooler is used as heat exchange equipment, and the high-temperature bottom slag is used as a high-temperature heat source. The concentrated high-salt wastewater is sprayed into the slag cooler, and directly exchanges heat with the high-temperature bottom slag, so as to achieve the purpose of rapidly drying the high-salt wastewater; the invention makes full use of the waste heat of the high-temperature bottom slag, without affecting the boiler efficiency and boiler operation. It is a beneficial supplement to the traditional zero-discharge process, and has the advantages of good evaporation effect, high equipment utilization rate, low investment and operation and maintenance costs;

Further, the high-salt wastewater can be used as the circulating cooling water of the drum slag cooler, which is preheated before being sprayed into the slag cooler, and the temperature of the high-salt wastewater can be controlled by adjusting the cooling water flow. The advantages of this design are: (1) High-salt wastewater is preheated to about 95°C, and it can evaporate more quickly after spraying; (2) Saving cooling water consumption.

Description of drawings

1 is a schematic diagram of a system structure involved in the present invention;

Among them, 1. drum slag cooler 2, equipment support 3, slag inlet pipe 4, slag discharge pipe 5, high-salt waste water storage tank 6, booster pump 7, first flow regulating door 8, second flow regulating door 9, cooling water Inlet 10, cooling water outlet 11, safety valve 12, front dust extraction pipe 13, rear dust extraction pipe 14, slag inlet temperature measurement point 15, slag discharge temperature measurement point 16, cooling water return water temperature measurement point.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings.

As shown in FIG. 1 , the present invention provides a method and system for treating high-salt wastewater by using high-temperature ash and slag, including a drum slag cooler 1, an equipment support 2, a slag inlet pipe 3, a slag discharge pipe 4, and a high-salt wastewater storage tank 5. Booster pump 6, first flow control gate 7, second flow control gate 8, cooling water inlet 9, cooling water outlet 10, safety valve 11, front dust extraction pipe 12, rear dust extraction pipe 13, slag inlet temperature Measuring point 14, slag discharge temperature measuring point 15 and cooling water return temperature measuring point 16, the cooling water inlet 9 and cooling water outlet 10 set on the drum slag cooler 1 and the waste water outlet on the high-salt waste water storage tank 5 and the cooling water outlet 10 are respectively. The waste water inlet is connected to form a circulation loop for cooling water.

A slag feed pipe 3 is connected to the feed port provided on the drum slag cooler 1 .

The slag discharge port provided on the drum slag cooler 1 is connected with a slag discharge pipe 4 .

The slag feed pipe 3 , the slag discharge pipe 4 and the cooling water return pipe are respectively provided with a slag feed temperature measurement point 14 , a slag discharge temperature measurement point 15 and a cooling water return water temperature measurement point 16 .

The cooling water outlet on the high-salt waste water storage tank 5 is also communicated with the slag feed pipe 3 for preliminarily cooling the ash in the slag feed pipe 3 .

A first flow regulating door 7 and a second flow regulating door 8 are respectively provided on the cooling water outlet on the high-salt waste water storage tank 5 and the connecting pipeline between the slag inlet pipe 3 and the drum slag cooler 1 .

A booster pump 6 is provided at the cooling water outlet of the high-salt wastewater storage tank 5 .

The drum slag cooler 1 is also provided with a safety valve 11 , a front dust extraction pipe 12 and a rear dust extraction pipe 13 .

The front dust extraction pipe 12 is arranged on the side of the slag inlet; the rear dust extraction pipe 13 is arranged on the side of the slag outlet; the safety valve 11 is arranged on the top of the drum slag cooler 1 .

The roller slag cooler 1 is fixed and limited by the equipment support 2 .

The working principle of the present invention is:

The invention provides a system for treating high-salt wastewater by utilizing high-temperature ash and slag, and sprays the concentrated high-salt wastewater into a drum slag cooler 1, and utilizes the heat of the high-temperature ash to quickly evaporate the high-salt wastewater;

The core point of the present invention is:

(1) The best evaporation effect is achieved by controlling the amount of waste water sprayed into the slag cooler, and the waste heat of ash and slag is fully utilized;

(2) The high-salt wastewater is used as the cooling water of the slag cooler, and the preheated wastewater is easier to evaporate, and at the same time, it has the effect of saving water.

The workflow of the present invention is:

Under the normal operation of the drum slag cooler 1, turn on the booster pump 6, and adjust the first flow control door 7 and the second flow control door 8 to a suitable opening degree, so that the slag discharge temperature measuring point 15 remains at 110 after the system runs stably. In the range of -120°C, the temperature measurement point 16 of the cooling water return water is kept at 95°C.

The function of the slag discharge temperature measuring point 15 is to monitor the slag discharge temperature. If the slag discharge temperature is lower than 100°C, it means that the waste water in the slag cooler has not been completely evaporated to dryness.

The function of the cooling water return temperature measuring point 16 is to monitor the temperature of the preheated waste water. If the temperature is too high, the waste water may be vaporized in the pipeline, causing danger.

When the slag discharge temperature is lower than 110°C, the opening degree of the first flow regulating door 7 is reduced, and the amount of injected waste water is reduced until the slag discharge temperature returns to the normal range.

When the slagging temperature is higher than 120°C, slowly increase the opening of the first flow regulating door 7 until the slagging temperature returns to the normal range.

When the cooling water return temperature is higher than 95°C, the high-salt wastewater has been fully preheated. At this time, the opening of the second flow control valve 8 should be reduced, and the original cooling water volume should be increased at the same time until the cooling water return temperature returns to normal. .

The function of the safety valve 11 is to automatically exhaust when the pressure in the slag cooler is too high to avoid accidents in the slag cooler.

Compared with the existing evaporative crystallization technology, the present invention has the following advantages:

1. Make full use of the drum slag cooler, and use the waste heat of the high-temperature bottom slag to evaporate the high-salt wastewater, with high evaporation efficiency and low investment.

2. The inorganic salt crystals precipitated after the wastewater is evaporated are discharged together with the bottom slag and do not need to be treated separately.

It has no effect on the operating efficiency and operating status of the boiler.

Claims (6)

1. A system for treating high-salinity wastewater by using high-temperature ash is characterized by comprising a roller slag cooler (1), a slag inlet pipe (3), a slag outlet pipe (4), a high-salinity wastewater storage tank (5), a first flow regulating valve (7), a second flow regulating valve (8), a cooling water inlet (9), a cooling water outlet (10), a slag inlet temperature measuring point (14), a slag outlet temperature measuring point (15) and a cooling water return temperature measuring point (16), wherein the cooling water inlet (9) and the cooling water outlet (10) arranged on the roller slag cooler (1) are respectively connected with a wastewater outlet and a wastewater inlet on the high-salinity wastewater storage tank (5) to form a cooling water circulation loop; a feed inlet arranged on the roller slag cooler (1) is connected with a slag inlet pipe (3); a slag discharging hole arranged on the roller slag cooler (1) is connected with a slag discharging pipe (4); a slag inlet temperature measuring point (14), a slag outlet temperature measuring point (15) and a cooling water return temperature measuring point (16) are respectively arranged on the slag inlet pipe (3), the slag outlet pipe (4) and the cooling water return pipeline; a cooling water outlet on the high-salinity wastewater storage tank (5) is also communicated with the slag inlet pipe (3); and a first flow regulating valve (7) and a second flow regulating valve (8) are respectively arranged on a cooling water outlet on the high-salinity wastewater storage tank (5) and a connecting pipeline between the slag inlet pipe (3) and the roller slag cooler (1).

2. The system for treating high-salinity wastewater by using high-temperature ash according to claim 1, characterized in that a booster pump (6) is arranged at a cooling water outlet of the high-salinity wastewater storage tank (5).

3. The system for treating high-salinity wastewater with high-temperature ash according to claim 1, characterized in that the roller slag cooler (1) is further provided with a front dust extraction pipe (12) and a rear dust extraction pipe (13), the front dust extraction pipe (12) is arranged at one side of the slag inlet; the rear dust extraction pipe (13) is arranged on one side of the slag outlet.

4. The system for treating high salinity wastewater with high-temperature ash according to claim 1, characterized in that the top of the roller slag cooler (1) is further provided with a safety valve (11).

5. The system for treating high salinity wastewater with high temperature ash according to claim 1, characterized in that, the roller slag cooler (1) is fixed and limited by the equipment support (2).

6. A method for treating high salinity wastewater with high temperature ash, which is characterized in that the system for treating high salinity wastewater with high temperature ash according to any one of claims 1 to 5 comprises the following steps:

under the condition that the roller slag cooler (1) normally operates, the first flow regulating valve (7) and the second flow regulating valve (8) are regulated to proper opening degrees, so that after the system stably operates, a slag discharging temperature measuring point (15) is kept at (110) and 120 ℃, and a cooling water return temperature measuring point (16) is kept at 95 ℃, wherein:

when the temperature at the slag discharging pipe (4) is lower than 110 ℃, reducing the opening degree of the first flow regulating valve (7) until the slag discharging temperature is restored to the normal range;

when the temperature at the slag discharging pipe (4) is higher than 120 ℃, slowly increasing the opening degree of the first flow regulating valve (7) until the slag discharging temperature returns to the normal range;

when the temperature on the cooling water return pipeline is higher than 95 ℃, the opening degree of the second flow regulating valve (8) is reduced, and meanwhile, the original cooling water quantity is increased until the cooling water return temperature returns to be normal.

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