Dry quenching boiler blowdown staged recovery system

Abstract

The utility model provides a dry quenching boiler blowdown grading recovery system belongs to the technical field of boiler water discharge, include: boiler, boiler is equipped with the mouth of connecting and discharging, and the mouth of connecting and discharging is connected with the water tank of connecting and discharging through the pipeline of connecting and discharging, and the outlet of water tank of connecting and discharging is connected with the import of water pump of connecting and discharging, and the outlet of water pump of connecting and discharging is connected with closed cooling tower, fog gun dust removal water tank and open circulating water pool through pipeline respectively, and boiler still is equipped with fixed mouth of discharging, and fixed mouth of discharging is connected with open circulating water pool through fixed pipeline of discharging, still is connected with sewage pool through the pipeline of discharging ground ditch. The system prolongs fixed discharge interval time through phosphorus-free water treatment reagent, reduces boiler blowdown quantity and heat loss, improves steam quality and evaporation capacity, through real -time analysis boiler blowdown water quality, divides blowdown water quality into several grades, and realizes the automatic switching of different grade blowdown water recovery through controller, recovers it to different downstream water treatment system, improves blowdown water recovery rate, reduces sewage treatment cost, reduces the waste of water resources.

Description

Technical Field

[0001] This utility model relates to the field of boiler water discharge technology, and in particular to a graded recycling system for wastewater discharge from a dry quenching coke boiler. Background Technology

[0002] Currently, traditional steam boiler in-furnace water treatment involves adding trisodium phosphate to combine with calcium and magnesium ions to form soft sludge, which is then discharged through periodic blowdown. However, there is a significant difference between pure steam-supply boilers and boilers in power plants that participate in the Rankine cycle. Since pure steam-supply boilers do not participate in the Rankine cycle, they cannot replenish pure steam condensate and must continuously add new demineralized water. Therefore, trisodium phosphate must be continuously added for in-furnace water treatment, leading to a large accumulation of phosphate and sludge within the boiler, necessitating increased frequency and duration of periodic blowdown. Simultaneously, to remove suspended solids, continuous blowdown must maintain a certain opening, resulting in a large amount of high-temperature boiler water being discharged from the boiler via scheduled and continuous blowdown. However, boiler blowdown not only removes the working fluid but also carries away a significant amount of heat, reducing the boiler's evaporation rate and causing disadvantages such as decreased evaporation and thermal efficiency. Secondly, according to the current process design, the boiler continuously discharges relatively clean water compared to the water used by the coking plant. All of this boiler wastewater is discharged into the sewage pond along the plant's drainage ditches, which not only increases the burden on the sewage treatment system and raises the company's sewage treatment costs, but also wastes a great deal of water resources.

[0003] Dry quenching waste heat boilers are crucial equipment for recovering the sensible heat of red-hot coke in the dry quenching process. The dry quenching waste heat boilers used in the dry quenching workshop are all pure steam-supply boilers. To ensure the quality of the supplied steam and the safety of the boiler, a large amount of ammonia and trisodium phosphate must be added. The large amount of chemical addition necessitates a large amount of wastewater discharge to promptly remove the slag formed inside the boiler. The large amount of wastewater discharge also causes a decrease in the pH and phosphate content of the boiler water, requiring the addition of chemicals again. Consequently, the boiler discharges a large amount of wastewater into the wastewater treatment system. This vicious cycle leads to problems such as increased chemical costs, higher wastewater treatment costs, water waste, and reduced boiler evaporation and thermal efficiency. Utility Model Content

[0004] This utility model addresses the problems of increased reagent costs, higher wastewater treatment costs, water waste, and reduced boiler evaporation and thermal efficiency in existing boiler blowdown systems. It provides a graded recovery system for dry quenching coke boiler blowdown by technically modifying the original boiler blowdown system.

[0005] This utility model provides a graded recycling system for wastewater discharge from a dry quenching coke boiler, comprising: a boiler; the boiler is provided with a continuous discharge port, which is connected to a continuous drainage tank via a continuous discharge pipe; the outlet of the continuous drainage tank is connected to the inlet of a continuous drainage pump, and the outlet of the continuous drainage pump is connected to a closed cooling tower, a mist cannon dust removal water tank, and an open circulating water pool via pipes respectively; the boiler is also provided with a fixed discharge port, which is connected to the open circulating water pool via a fixed discharge pipe, and the fixed discharge port is also connected to a sewage pool via a drainage ditch pipe.

[0006] As a preferred embodiment of this technical solution, a first regulating valve is provided on the pipeline between the continuous drainage pump and the closed cooling tower, a second regulating valve is provided on the pipeline between the continuous drainage pump and the dust removal water tank of the mist cannon, and a third regulating valve is provided on the pipeline between the continuous drainage pump and the open circulating water pool.

[0007] As a preferred embodiment of this technical solution, a sampling pipe is connected to the connecting pipeline, and a sampling device is connected to the other end of the sampling pipe. The sampling device is connected to an online steam and water analysis instrument.

[0008] As a preferred embodiment of this technical solution, the online steam and water analyzer is electrically connected to the controller, and the controller is also electrically connected to the first regulating valve, the second regulating valve, and the third regulating valve respectively.

[0009] As a preferred embodiment of this technical solution, the boiler is also equipped with a chemical dosing device, which includes a chemical tank and a chemical dosing pump. The chemical tank is connected to the boiler's feedwater pipeline through the chemical dosing pump. The chemical tank stores alkaline, phosphorus-free organic chemicals.

[0010] As a preferred embodiment of this technical solution, a liquid level detector is installed in the drainage tank, and the liquid level detector is electrically connected to the controller.

[0011] As a preferred embodiment of this technical solution, at least three boilers are provided, which are connected in parallel, and each boiler is equipped with a corresponding drainage tank and a corresponding drainage pump.

[0012] The dry quenching coke boiler blowdown graded recovery system provided by this utility model extends the fixed blowdown interval by using phosphorus-free water treatment agents, reducing boiler blowdown volume and heat loss, and improving steam quality and evaporation rate. By analyzing the water quality of boiler blowdown in real time, the system classifies the blowdown water quality into several levels, and automatically switches the recovery of different levels of blowdown water through a controller, recycling it to different downstream water treatment systems. It can also automatically switch valves and downstream water treatment systems in a timely manner to achieve the purpose of precise recovery and reuse of blowdown water, improve the blowdown water recovery rate, reduce wastewater treatment costs, and reduce water waste.

[0013] This system relies on the boiler's existing blowdown and control systems. Based on the detected conductivity of the blowdown wastewater, it adjusts the wastewater's destination in a timely manner, sending it to different downstream water treatment systems. The system is designed for an annual operating time of 8400 hours and achieves the following advantages and technical indicators: Reduced boiler water loss: Boiler water loss rate reduced to 5-7%; Increased boiler steam production: Overall boiler steam production increased by 4-6%; Improved wastewater recovery rate: Boiler blowdown wastewater recovery rate ≥98%; Excellent equipment operating stability: Recovery system operating rate ≥95%; High equipment safety rate: Accident rate 0%. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A schematic diagram of the structure of a dry quenching coke boiler blowdown graded recovery system provided in one embodiment of this utility model; Figure 2 A schematic diagram of the structure of a dry quenching coke boiler wastewater graded recovery system provided for another embodiment of this utility model; Figure 3 A schematic diagram of the structure of a dry quenching coke boiler wastewater graded recovery system provided in another embodiment of this utility model.

[0016] Explanation of reference numerals in the attached figures: 1. Boiler; 2. Drainage tank; 3. Drainage pump; 4. Closed-loop cooling tower; 5. Dust suppression water tank for mist cannons; 6. Open-loop circulating water tank; 7. Sewage tank; 8. Online steam and water analysis instrument; 9. Controller; 11. Chemical tank; 12. Dosing pump; 13. Liquid level detector; 21. Sampling device; 41. First regulating valve; 51. Second regulating valve; 61. Third regulating valve. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments of this utility model are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are also within the protection scope of this utility model.

[0018] like Figure 1This utility model discloses a graded recycling system for wastewater discharge from a dry quenching coke boiler, comprising: a boiler 1; the boiler 1 is provided with a continuous discharge port, which is connected to a continuous drainage tank 2 via a continuous discharge pipe; the outlet of the continuous drainage tank 2 is connected to the inlet of a continuous drainage pump 3, and the outlet of the continuous drainage pump 3 is connected to a closed cooling tower 4, a mist cannon dust removal water tank 5, and an open circulating water pool 6 via pipes respectively; the boiler 1 is also provided with a fixed discharge port, which is connected to the open circulating water pool 6 via a fixed discharge pipe, and the fixed discharge port is also connected to a sewage pool 7 via a drainage ditch pipe.

[0019] This system is a technical modification of the existing sewage discharge system of boiler 1. Other structures in boiler 1 are identical to those in existing technologies and are not further limited here. Boiler 1's scheduled sewage discharge is set to once a week. The water quality of the scheduled discharge is poor and can be sent to the open circulating water tank 6 for purification and use as general circulating water within the plant, or directly to the wastewater tank 7 for treatment and discharge. The continuously discharged wastewater can be divided into several grades and sent to the closed cooling tower 4 for applications requiring high water quality, to the mist cannon dust suppression tank 5 for dust removal in the plant area or other work sections, or to the open circulating water tank 6 for general industrial circulating water. This system recycles and reuses the wastewater from boiler 1, achieving the recycling of different grades of wastewater and sending it to different downstream water treatment systems. This improves water resource utilization, reduces wastewater treatment costs, and avoids waste caused by direct discharge of wastewater into the surrounding environment, thus achieving the goals of energy conservation, emission reduction, and water resource reuse.

[0020] like Figure 1 In a specific implementation scheme, a first regulating valve 41 is provided on the pipeline between the drain pump 3 and the closed cooling tower 4, a second regulating valve 51 is provided on the pipeline between the drain pump 3 and the mist cannon dust removal water tank 5, and a third regulating valve 61 is provided on the pipeline between the drain pump 3 and the open circulating water tank 6. The aforementioned first regulating valve 41, second regulating valve 51, and third regulating valve 61 are commonly used pneumatic or electric valves in the art, and are not limited here.

[0021] In the specific implementation plan, a sampling pipe is connected to the continuous discharge pipeline, and a sampling device 21 is connected to the other end of the sampling pipe. The sampling device 21 is connected to an online steam-water analyzer 8. The sampling device 21 is a commonly used sampling device in the plant and is not limited here. The online steam-water analyzer 8 can analyze the water quality of the discharged wastewater in real time. The main analytical parameter is conductivity, so that the wastewater can be disposed of in a timely manner by comparing the detected conductivity with the water quality of each level of water use in the plant.

[0022] In the specific implementation plan, the online steam-water analyzer 8 is electrically connected to the controller 9, which is also electrically connected to the first regulating valve 41, the second regulating valve 51, and the third regulating valve 61. The controller 9 and its DCS control system are commonly used technologies in this field. They are based on the original control system of the boiler 1. The online steam-water analyzer 8 analyzes the wastewater quality in real time, and then, based on the detected conductivity, the controller 9 controls the opening and closing of the first regulating valve 41, the second regulating valve 51, and the third regulating valve 61 to send the wastewater to different downstream water treatment systems. When the wastewater quality changes, the valves and downstream water treatment systems can be automatically switched in a timely manner to achieve the purpose of accurate recycling and reuse of wastewater.

[0023] Specifically, when the conductivity of the wastewater is <10 μS·cm, the wastewater is sent to the closed cooling tower 4 and enters the closed-loop cooling water system; when the conductivity is in the range of 10-30 μS·cm, the wastewater is sent to the mist cannon dust removal water tank 5; when the conductivity is >30 μS·cm, the wastewater is sent to the open-loop circulating water tank 6 and enters the open-loop cooling water system. When the water quality index is within a certain range, the corresponding valve of the DCS interlock opens, and the other valves close. To prevent the wastewater quality from affecting the downstream water treatment system, the switching valve is controlled 10-30 minutes after the detected conductivity changes, so as to empty the wastewater in the connecting wastewater tank 2 before the water quality change, especially after the conductivity changes from high to low, to prevent the high conductivity wastewater from affecting the low conductivity water treatment system.

[0024] like Figure 2 In a specific implementation plan, the boiler 1 is also equipped with a dosing device, which includes a chemical tank 11 and a dosing pump 12. The chemical tank 11 is connected to the feedwater pipe of the boiler 1 through the dosing pump 12. The chemical tank 11 stores alkaline phosphorus-free organic chemicals.

[0025] The water treatment agent added to boiler 1 by the dosing device is a commonly used agent in the field. The outlet of the dosing pump 12 is connected to the feedwater pipeline before the economizer, consistent with the existing system. The alkaline, phosphorus-free organic agent can prevent scaling and salt accumulation. The agent combines with calcium and magnesium ions in the boiler water to form light suspended solids that are suspended in the boiler water and can be discharged through continuous blowdown. Since continuous blowdown is always open during normal operation of boiler 1, it will not significantly increase the amount of boiler blowdown and heat loss. However, without the addition of trisodium phosphate, no water slag will be generated, which can significantly reduce the frequency of periodic blowdown and greatly extend the interval between blowdowns, which is beneficial to reducing the amount of boiler blowdown and heat loss, and improving steam quality and evaporation.

[0026] In a specific implementation plan, a level detector 13 is installed in the drain tank 2, and the level detector 13 is electrically connected to the controller 9. When the sewage discharge volume of the drain changes, it will affect the liquid level in the drain tank 2. In order to ensure the continuous and stable operation of the system, the level detector 13 is used to monitor the liquid level in the drain tank 2 in real time, and the opening degree of each regulating valve and the start and stop of the drain pump 3 are adjusted in a timely manner according to the liquid level to avoid equipment failure.

[0027] like Figure 3 In the specific implementation plan, at least three boilers 1 are set up, and the three boilers 1 are connected in parallel, with three connected drainage tanks 2 and three connected drainage pumps 3 respectively. The dry quenching workshop in the plant has three boilers 1. In this field, multiple boilers 1 are often connected in parallel. Therefore, the wastewater graded recovery system of this utility model is also correspondingly set up, with the online steam-water analysis instrument 8, controller 9 and control system, and downstream water treatment system being shared. This wastewater graded recovery system can realize the automated graded recovery of wastewater, with high system operating efficiency and stability, simple structure, convenient operation, and multiple sets connected in parallel do not affect each other's operation, and can also reduce water waste.

[0028] It should be noted that arrows without reference numerals indicate the flow direction of gas-liquid mixtures, gas phases, or liquid phases.

[0029] In this utility model's dry quenching coke boiler wastewater graded recovery system, during operation, the alkaline, phosphorus-free organic reagent in the reagent tank 11 is pumped to the boiler 1's feedwater pipeline via the dosing pump 12, entering the boiler 1 along with the boiler's makeup water. The reagent combines with calcium and magnesium ions in the boiler water to form light suspended solids, which remain suspended in the boiler water. These suspended solids then enter the continuous discharge pipeline through the continuous discharge port and are stored in the continuous discharge tank 2. During the continuous discharge process, a small portion of the wastewater passes through the continuous discharge pipeline into the sampling device 21 via the sampling pipe, and then enters the online steam-water analyzer 8 for conductivity analysis and detection. When the conductivity of the discharged wastewater is <10 μS·cm, the controller 9 controls the first regulating valve 41 to open, sending the discharged wastewater from the drain tank 2 into the closed cooling tower 4, which then enters the closed-loop cooling water system for use in applications requiring high water quality. When the conductivity is in the range of 10-30 μS·cm, the controller 9 controls the second regulating valve 51 to open, sending the discharged wastewater to the mist cannon dust removal water tank 5 for dust removal and suppression in the plant area or other work sections. When the conductivity is >30 μS·cm, the controller 9 controls the third regulating valve 61 to open, sending the discharged wastewater to the open circulating water tank 6, which then enters the open circulating cooling water system for use as ordinary industrial circulating water. Additionally, the boiler 1's scheduled discharge frequency is once a week. The water quality of the scheduled discharge is relatively poor; it can be sent to the open circulating water tank 6 for purification and then used as ordinary circulating water within the plant, or it can be directly sent to the wastewater tank 7 for treatment and discharge.

[0030] It is important to note that when water quality indicators fall within a certain range, the corresponding valve in the DCS interlock will open, while other valves will close. Additionally, 10-30 minutes after a change in the detected conductivity, the valves will be switched to ensure that the wastewater in the drain tank 2 before the change in water quality is emptied as much as possible. Changes in the discharge volume of the drain system will affect the liquid level in the drain tank 2. To ensure continuous and stable system operation, a level detector 13 is used to monitor the liquid level in the drain tank 2 in real time, and the opening of each regulating valve and the start / stop of the drain pump 3 are adjusted accordingly to prevent equipment failure.

[0031] like Figure 3 Based on the above embodiments, the three boilers 1 connected in parallel in the dry quenching workshop of the plant are also equipped with the above-mentioned dry quenching boiler wastewater classification and recycling system. The wastewater treatment method of each boiler 1 is the same, and the multiple sets connected in parallel do not affect each other's operation.

[0032] It should be noted that the detailed structure of some devices in this utility model is not described in detail, but belongs to the prior art known to those skilled in the art, and therefore will not be described again here. In addition, the parts of this device not described are the same as or can be implemented using existing technology.

[0033] It should be noted that pressure sensors, flow meters, or temperature sensors are installed on the conveying pipelines inside the system between different units, devices, or equipment. Various valves, such as pressure relief valves, pressure regulating valves, and safety valves, are also installed to regulate and stabilize the pressure of the entire system.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A graded recovery system for wastewater from a dry quenching coke boiler, characterized in that, include: boiler; The boiler is equipped with a continuous discharge port, which is connected to a continuous drainage tank via a continuous discharge pipe. The outlet of the continuous drainage tank is connected to the inlet of a continuous drainage pump, and the outlet of the continuous drainage pump is connected to a closed cooling tower, a mist cannon dust removal water tank, and an open circulating water pool via pipes. The boiler is also equipped with a fixed discharge port, which is connected to the open circulating water pool via a fixed discharge pipe. The fixed discharge port is also connected to a sewage pool via a drainage ditch pipe.

2. The dry quenching coke boiler blowdown graded recovery system according to claim 1, characterized in that, A first regulating valve is provided on the pipeline between the continuous drainage pump and the closed cooling tower, a second regulating valve is provided on the pipeline between the continuous drainage pump and the dust removal water tank of the mist cannon, and a third regulating valve is provided on the pipeline between the continuous drainage pump and the open circulating water pool.

3. The dry quenching coke boiler blowdown graded recovery system according to claim 2, characterized in that, A sampling pipe is connected to the connecting pipeline, and a sampling device is connected to the other end of the sampling pipe. The sampling device is connected to an online steam and water analysis instrument.

4. The graded recovery system for wastewater from a dry quenching coke boiler according to claim 3, characterized in that, The online steam and water analyzer is electrically connected to the controller, and the controller is also electrically connected to the first regulating valve, the second regulating valve, and the third regulating valve, respectively.

5. The graded recovery system for wastewater from a dry quenching coke boiler according to claim 1, characterized in that, The boiler is also equipped with a chemical dosing device, which includes a chemical tank and a dosing pump. The chemical tank is connected to the boiler's water supply pipe through the dosing pump. The chemical tank stores alkaline, phosphorus-free organic chemicals.

6. The dry quenching coke boiler blowdown graded recovery system according to claim 4, characterized in that, The drain tank is equipped with a liquid level detector, which is electrically connected to the controller.

7. The dry quenching coke boiler blowdown graded recovery system according to any one of claims 1-6, characterized in that, The boiler is provided in at least three configurations, which are connected in parallel and are equipped with three drainage tanks and three drainage pumps respectively.

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