Blowdown flash steam recovery system for waste heat boiler of heat recovery coke oven

Abstract

The utility model relates to a blow-off flash steam recovery system for a heat recovery coke oven waste heat boiler, which is characterized in that heat recovery boilers are provided with heat recovery boiler drums, the bottoms of the heat recovery boilers are provided with heat recovery boiler blow-off pipes, and sewage outlets of the heat recovery boiler drums are connected with sewage inlets II of corresponding blow-off flash tanks through pipelines II; a blow-off pipe of the heat recovery boiler is connected with a first sewage inlet of the corresponding blow-off flash tank through a first pipeline, the top end of each blow-off flash tank is connected with an inlet of the steam compressor unit through a third pipeline, and an outlet of the steam compressor unit is connected with the low-pressure steam pipe network through a fourth pipeline. The heat recovery system has the advantages that pollution discharge flash steam of all the heat recovery boilers is recovered through the header pipe, the number of devices is reduced, and investment optimization and operation maintenance of the devices are facilitated; the steam compressor unit sucks flash steam, the flash steam is compressed and boosted to low-pressure steam, the low-pressure steam is connected to a low-pressure steam pipe network through an outlet pipeline of the steam compressor, and white steam caused by blow-off steam diffusion is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat utilization of coke ovens, in particular to a sewage flash steam recovery system for a waste heat boiler of a heat recovery coke oven. Background Technique

[0002] The flue gas temperature of a heat recovery coke oven can reach 1200°C - 1300°C. It is sent to a heat recovery boiler through a high-temperature flue gas pipeline for heat exchange to heat the boiler feed water to make it undergo a phase change and rise in temperature to become superheated steam, which is sent to a steam turbine power station for power generation. The continuous blowdown and regular blowdown water in the heat recovery boiler are sent to a blowdown flash tank through a blowdown pipeline, and a certain amount of flash steam will be produced in the blowdown flash tank.

[0003] Due to the relatively low pressure of the blowdown flash steam, it is difficult to utilize the flash steam. If a medium-pressure deaerator is used in the feed water system of the heat recovery boiler, most of the flash steam from the heat recovery boiler cannot directly reach the deaerator; and if it is cooled through a condensation heat exchanger and the working medium is recovered, the heat of the flash steam is wasted as a cold source. Therefore, at present, most of the flash steam from heat recovery boilers is discharged to the atmosphere for treatment. Considering that generally, a heat recovery coke oven project has a relatively large number of heat recovery boilers, a large total evaporation capacity, and relatively large blowdown water volume and flash steam volume, the extensive discharge is a relatively large waste of working medium and energy. Therefore, it is necessary to find a feasible, efficient, and simple way to recover the blowdown flash steam of the boiler. Summary of the Invention

[0004] The purpose of the utility model is to provide a sewage flash steam recovery system for a waste heat boiler of a heat recovery coke oven, which realizes the recovery of the blowdown flash steam of the waste heat boiler of the heat recovery coke oven, is stable and reliable, improves the efficiency of blowdown flash steam recovery, and has a simple structure, safety and stability.

[0005] To achieve the above purpose, the utility model is realized through the following technical solutions:

[0006] A sewage flash steam recovery system for a waste heat boiler of a heat recovery coke oven includes at least one heat recovery boiler, at least one blowdown flash tank, and a steam compression unit. Each heat recovery boiler is provided with a steam drum of the heat recovery boiler. The bottom of each heat recovery boiler is provided with a blowdown pipe of the heat recovery boiler. The sewage outlet of the steam drum of the heat recovery boiler is connected to the sewage inlet two of the corresponding blowdown flash tank through pipeline two. The blowdown pipe of the heat recovery boiler is connected to the sewage inlet one of the corresponding blowdown flash tank through pipeline one. The top of each blowdown flash tank is connected to the inlet of the steam compression unit through pipeline three. The outlet of the steam compression unit is connected to the low-pressure steam pipe network through pipeline four.

[0007] The number of steam drums of the heat recovery boiler is the same as that of the blowdown flash tanks.

[0008] A safety valve of the low-pressure steam pipe network is arranged on the low-pressure steam pipe network.

[0009] Pipeline 1 is the regular blowdown main pipe of the heat recovery boiler, pipeline 2 is the continuous blowdown main pipe of the heat recovery boiler, pipeline 3 is the flash steam main pipe, and pipeline 4 is the outlet pipeline of the steam compression unit.

[0010] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0011] 1. The continuous blowdown water and regular blowdown water of the heat recovery boiler are respectively discharged into the continuous blowdown flash tank and regular blowdown flash tank through pipelines. The flash steam generated by the blowdown water in the blowdown flash tank of the heat recovery boiler is connected to the flash steam main pipe through a pipeline and introduced into the steam compression unit through the flash steam main pipe. The blowdown flash steam of each heat recovery boiler is recovered using the main pipe system, reducing the number of steam compressor equipment and facilitating the optimization of equipment investment and operation and maintenance.

[0012] 2. The blowdown flash steam recovery system of the heat recovery coke oven waste heat boiler not only recovers the working medium water but also avoids the waste of flash steam heat. With a relatively small power consumption, namely the power consumption of the steam compressor, the waste steam is converted into high-quality steam. The pressure of the compressed steam is higher than the original blowdown flash steam, enabling the utilization of the flash steam, which is then incorporated into the steam pipe network, achieving efficient recovery and utilization of the flash steam.

[0013] 4. A safety valve for the low-pressure steam pipe network is provided in the low-pressure steam pipe network to prevent the pressure from being too high when the steam compression unit pressurizes and sends the flash steam into the low-pressure steam pipe network, thus avoiding impact on the low-pressure steam pipe network and improving the safe operation of the steam pipe network.

[0014] 5. The steam compression unit sucks in the flash steam, compresses and boosts it to low-pressure steam, and is connected to the low-pressure steam pipe network through the outlet pipeline of the steam compressor, achieving the quality improvement (pressure boost) and recovery of the blowdown flash steam. At the same time, it avoids the "white steam" caused by the discharge of the blowdown steam. Brief Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of the blowdown flash steam recovery system of the heat recovery coke oven waste heat boiler.

[0016] In the figure: 1 - Regular blowdown water main pipe of the heat recovery boiler; 2 - Steam drum of the heat recovery boiler; 3 - Continuous blowdown pipeline of the heat recovery boiler; 4 - Blowdown flash tank; 5 - Flash steam main pipe; 6 - Steam compression unit; 7 - Outlet pipeline of the steam compression unit; 8 - Low-pressure steam pipe network; 9 - Safety valve for the low-pressure steam pipe network. Detailed Embodiment

[0017] The present utility model will be described in detail below with reference to the drawings in the specification. However, it should be noted that the implementation of the present utility model is not limited to the following embodiments.

[0018] The following embodiments are implemented on the premise of the technical solution of the present utility model, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present utility model is not limited to the following embodiments. The methods used in the following embodiments are all conventional methods unless otherwise specified.

[0019]

Embodiment 1

[0020] See Figure 1 , a waste heat boiler blowdown flash steam recovery system for a heat recovery coke oven, including 4 waste heat boilers, 4 blowdown flash tanks 4, and a steam compression unit 6. Each waste heat boiler is provided with a waste heat boiler steam drum 2. A waste heat boiler blowdown pipe 3 is provided at the bottom of each waste heat boiler. The sewage outlet of the waste heat boiler steam drum 2 is connected to the sewage inlet 2 of the corresponding blowdown flash tank 4 through a continuous blowdown main pipe 1 of the waste heat boiler. The waste heat boiler blowdown pipe 3 is connected to the sewage inlet 1 of the corresponding blowdown flash tank 4 through a regular blowdown main pipe 1 of the waste heat boiler. The top of each blowdown flash tank 4 is connected to the inlet of the steam compression unit 6 through a flash steam main pipe 5. The outlet of the steam compression unit 6 is connected to a low-pressure steam pipe network 8 through an outlet pipeline of the steam compression unit 6. A low-pressure steam pipe network safety valve 9 is provided on the low-pressure steam pipe network 8.

[0021] Working process:

[0022] Taking 4 waste heat boilers with an evaporation capacity of 80 t / h as an example, 4 corresponding blowdown flash tanks are provided for the 4 waste heat boilers; the continuous blowdown water of each waste heat boiler is discharged into the corresponding blowdown flash tank through a continuous blowdown pipeline of the waste heat boiler. The regular blowdown water of each waste heat boiler is discharged into the corresponding blowdown flash tank by a regular blowdown main pipe of the waste heat boiler. After the blowdown water enters the blowdown flash tank, flash steam of 0.2 MPa is generated. The total blowdown water volume is 4 * 80 * 0.02 = 6.4 t / h. The flash steam is taken as 2 t / h according to 30% of the blowdown water volume; the flash steam generated by the blowdown water in the blowdown flash tank is connected to the flash steam main pipe through a pipeline and introduced into the steam compression unit through the flash steam main pipe; the steam compression unit inhales the flash steam and compresses and boosts it to low-pressure steam of 0.6 MPa. The flash steam generated by the blowdown water in the blowdown flash tank is connected to the flash steam main pipe through a pipeline and introduced into the steam compression unit through the flash steam main pipe; the power consumption of the steam compression unit is about 160 kW. It is considered that with the application of 160 kW of electricity, 2 t / h of low-pressure steam is recovered; a low-pressure steam pipe network safety valve is provided on the low-pressure steam pipe network to prevent the low-pressure steam pipe network from being impacted by excessive pressure when the steam compressor pressurizes and sends the flash steam into the low-pressure steam pipe network, affecting the stable operation of the low-pressure steam pipe network.

[0023] For the continuous blowdown and regular blowdown of the heat recovery boiler of the present utility model, they are respectively discharged into the continuous blowdown flash tank and the regular blowdown flash tank through pipelines. The flash steam generated by the blowdown water in the blowdown flash tank of the heat recovery boiler is connected to the flash steam main pipe through a pipeline, and is introduced into the steam compression unit through the flash steam main pipe. The blowdown flash steam of each heat recovery boiler is recovered using the main pipe system, reducing the number of steam compressor equipment and facilitating the optimization of equipment investment and operation and maintenance; for the blowdown flash steam recovery system of the heat recovery coke oven waste heat boiler, it not only recovers the working medium water but also avoids the waste of the heat of the flash steam. With relatively low power consumption, namely the power consumption of the steam compressor, the waste steam is converted into high-quality steam. The pressure of the compressed steam is higher than that of the original blowdown flash steam, enabling the utilization of the flash steam, which is then incorporated into the steam pipe network, achieving efficient recovery and utilization of the flash steam; a safety valve for the low-pressure steam pipe network is provided in the low-pressure steam pipe network to prevent the steam compression unit from causing excessive pressure when sending the pressurized flash steam into the low-pressure steam pipe network, thus avoiding impact on the low-pressure steam pipe network and improving the stable operation safety of the steam pipe network; the steam compression unit inhales the flash steam, compresses and boosts it to low-pressure steam, and is connected to the low-pressure steam pipe network through the outlet pipeline of the steam compressor, achieving the quality improvement (pressure boost) recovery of the blowdown flash steam and simultaneously avoiding the "white steam" caused by the discharge of the blowdown steam.

Claims

1. A heat recovery coke oven waste heat boiler blowdown flash steam recovery system, characterized in that: It includes at least one heat recovery boiler, at least one blowdown expansion tank, and a steam compressor unit. Each heat recovery boiler is provided with a heat recovery boiler drum. A heat recovery boiler blowdown pipe is provided at the bottom of each heat recovery boiler. The sewage outlet of the heat recovery boiler drum is connected to the sewage inlet 2 of the corresponding blowdown expansion tank through pipeline 2. The heat recovery boiler blowdown pipe is connected to the sewage inlet 1 of the corresponding blowdown expansion tank through pipeline 1. The top of each blowdown expansion tank is connected to the inlet of the steam compressor unit through pipeline 3. The outlet of the steam compressor unit is connected to the low-pressure steam pipeline network through pipeline 4.

2. A heat recovery coke oven waste heat boiler blowdown flash steam recovery system according to claim 1, characterized in that: The number of heat recovery boiler drums and blowdown expansion vessels is the same.

3. A heat recovery coke oven waste heat boiler blowdown flash steam recovery system according to claim 1, characterized in that: The low-pressure steam pipe network is provided with a low-pressure steam pipe network safety valve.

4. A heat recovery coke oven waste heat boiler blowdown flash steam recovery system according to claim 1, characterized in that: The pipeline one is the heat recovery boiler periodic sewage main pipe, the pipeline two is the heat recovery boiler continuous sewage main pipe, the pipeline three is the flash steam main pipe, and the pipeline four is the steam compressor unit outlet pipeline.

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