Desalted water system for self-contained power plant of steel mill

Abstract

The invention relates to the field of chemical water treatment of power plants, and discloses a steel mill self-contained power plant demineralized water system which comprises five chemical water stations, the first chemical water station comprises a first-stage demineralized water tank and a second-stage demineralized water tank, the second chemical water station comprises two thermoelectric demineralized water tanks, and the third chemical water station comprises a dry quenching demineralized water tank. The fourth chemical water station comprises a fourth machine desalting water tank; the fifth chemical water station comprises a middle water tank and a fifty thousand desalting water tank; the first-stage desalted water tank, the middle water tank, the second thermoelectric desalted water tank and the dry quenching desalted water tank are communicated with one another, and the second-stage desalted water tank, the fourth machine desalted water tank and the fifty thousand desalted water tank are communicated with one another. The first chemical water station is newly built and is communicated with the original factory desalting pipe network, so that the purposes of reducing staff, improving efficiency and reducing the system are achieved, the system is improved and upgraded, the labor intensity of staff can be reduced, the enterprise happiness of the staff can be improved, the whole system is free of wastewater discharge, and the environmental protection benefit is obvious.

Description

Technical Field

[0001] The present invention relates to the field of chemical water treatment in power plants, and in particular to a desalted water system for a self-provided power plant of a steel plant. Background Art

[0002] A steel mill's self-owned power plant is a supporting power generation facility built by steel enterprises to meet their own electricity and heat needs for production. It usually uses secondary energy (such as coal gas, waste heat, waste pressure, etc.) generated during the steel production process to generate electricity. It is a key facility for steel enterprises to achieve energy self-sufficiency, reduce costs and increase efficiency. Its core value lies in converting "waste" in the production process into high-quality energy.

[0003] The desalted water stations configured in the power plant desalted water system are distributed between the gas power generation and waste heat units. However, some power plant desalted water systems have the following process drawbacks: (1) The system layout is decentralized, the water stations are scattered and far apart, and the staffing requirements are large; (2) Unbalanced water supply and low utilization of equipment and personnel; (3) The process configuration is backward and cannot meet the requirements of environmental protection and energy conservation. The existing water station mainly uses the "ion exchange bed" process, which has process disadvantages such as large acid and alkali consumption, high manual operation intensity, and low degree of automation. It can no longer meet the current process requirements of environmental protection and energy conservation. (4) The equipment process configuration is different, and the equipment selection is different, which makes customized management inconvenient and increases the amount of equipment maintenance.

[0004] Therefore, it is urgent to propose an optimization method for the desalted water system structure to overcome the above-mentioned process drawbacks. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a desalted water system for a steel plant's self-contained power plant, which connects the desalted water pipeline of the first chemical water station with the original desalted water pipeline network in the plant area. Through the integration of the pipeline network and the optimization of the personnel structure, it is convenient for unified management of equipment, improves economic benefits, reduces system energy consumption and the workload of staff.

[0006] To achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: a desalted water system for a self-owned power plant of a steel plant, comprising five chemical water stations, wherein the first chemical water station comprises a primary desalted water tank and a secondary desalted water tank, the second chemical water station comprises a secondary thermoelectric desalted water tank, the third chemical water station comprises a dry quenching desalted water tank, the fourth chemical water station comprises a No. 4 unit desalted water tank, and the fifth chemical water station comprises an interconnected intermediate water tank and a 50,000 desalted water tank; The first-level desalted water tank, the intermediate water tank, the second thermoelectric desalted water tank and the dry quenching desalted water tank are interconnected, the second-level desalted water tank, the fourth unit desalted water tank and the 50,000 desalted water tank are interconnected, and the second-level desalted water tank, the dry quenching desalted water tank, the 50,000 desalted water tank and the fourth unit desalted water tank are respectively connected to the corresponding boilers.

[0007] Optionally, the primary desalted water tank and the secondary desalted water tank are connected to each other, and a connecting valve is installed on the connecting pipeline between the two.

[0008] Optionally, a return pipeline is provided between the output end and the input end of the first-stage desalted water tank, the second-stage desalted water tank and the second thermoelectric desalted water tank, and a return valve is installed on the return pipeline.

[0009] Optionally, a decarbonizer is provided inside the intermediate water tank, and the intermediate water tank is connected to the 50,000 ton desalted water tank via a process water pump and an ion exchanger.

[0010] Optionally, an additional desalted water tank for supplying water to corresponding boilers is connected to the communication pipeline between the second thermoelectric desalted water tank and the CDQ desalted water tank.

[0011] Optionally, the first water treatment station adopts a full membrane process, and the second to fifth water treatment stations adopt an ion exchange bed process.

[0012] Optionally, the DCS system screens of the second to fifth chemical water stations are centrally located in the control room of the first chemical water station.

[0013] Optionally, the water production process steps of the first water treatment station include: S1. The domestic water in the raw water tank passes through the multi-media filter into the filter water tank to obtain preliminary filtered water; S2, the preliminary filtered water passes through the ultrafiltration device into the ultrafiltration water production tank to obtain ultrafiltered water; S3, the ultrafiltered water is desalted by two-stage RO devices in sequence and then enters the first-stage desalted water tank to obtain first-stage desalted water; S4. The primary desalted water is desalted by the EDI device and then enters the secondary desalted water tank to obtain secondary desalted water.

[0014] The beneficial effects of the present invention are as follows: In the present invention, a new first chemical water station is built and connected to the original factory desalination pipeline network, thereby achieving the purpose of reducing staff and increasing efficiency as well as reducing system costs. By improving and upgrading the system, the labor intensity of personnel can be reduced, the happiness of employees and the company can be improved, and the overall system can be free of wastewater discharge, with obvious environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 2. It is a schematic diagram of the interconnected structure of the desalted water system according to an embodiment of the present invention; Figure 2 This is a water production process flow chart of the first water treatment station in an embodiment of the present invention; DETAILED DESCRIPTION

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0017] like Figure 1 and Figure 2 The figure shows a desalinated water system for a steel plant's self-owned power plant, consisting of five chemical water treatment stations: the first, second, third, fourth, and fifth chemical water treatment stations. The desalted water pipeline of the first chemical water station is connected to the existing desalted water network within the plant and is equipped with automatic valves and return pipes. The first chemical water station uses a full membrane process, while the second through fifth chemical water stations use ion exchange bed processes.

[0018] The existing power plant was originally equipped with four chemical water stations, namely the No. 2 thermal power chemical water station (the second chemical water station), the CDQ chemical water station (the third chemical water station), the No. 4 unit chemical water station (the fourth chemical water station), and the No. 50,000 chemical water station (the fifth chemical water station). All of them mainly used the "ion exchange bed" process, which had process drawbacks such as high acid and alkali consumption, high manual operation intensity, and low degree of automation. They can no longer meet the current process requirements for environmental protection and energy conservation.

[0019] To reduce staff and increase efficiency, improve system operation economics, and enhance automation, the proposed solution includes the construction of a new Unit 6 chemical water station (the first chemical water station) for centralized water supply. Unit 6 utilizes a full membrane process, resulting in minimal overall system acid and alkali consumption, a high degree of automation, high operational economics, and minimal maintenance. By constructing a demineralized water interconnecting pipeline, adding automated valves, and implementing logic programming, centralized monitoring of demineralized water throughout the plant is achieved, eliminating outdated processes, and optimizing demineralized water utilization and system staffing.

[0020] Specifically, first draw the desalted water system diagram of the whole plant, compile the system operation process logic manual, build two new plant desalted water pipelines in the area of ​​the new unit No. 6, connect them with the original plant desalted water pipeline network, and simultaneously configure automatic valves and return pipes; then, according to the system process requirements and combined with the existing system DCS software foundation, complete the remote debugging of the automatic valves, and according to the process operation logic manual, complete the logic configuration and DCS system screen drawing; centralize the DCS screens of each water station to the control room of the No. 6 unit water station; finally, concentrate the personnel of each water station to the newly built No. 6 unit water station, and ensure two-way supply with other water stations, and the second thermal power water station will be abandoned.

[0021] After adopting the technical solution proposed by the present invention, the benefits achieved are directly reflected in the following aspects: (1) Economic benefits: Economic benefits of RMB 2.5377 million per year were achieved by reducing staff, increasing efficiency and reducing system energy consumption.

[0022] ① Reducing staff and increasing efficiency: Through the integration of pipeline networks and the optimization of personnel structure, the goal of reducing staff and increasing efficiency was achieved, with direct benefits of 2.25 million yuan per year.

[0023] Calculation formula: Benefit = Number of employees reduced × Average annual income per capita = 9 × 250,000 = 2.25 million; Among them, 9 people actually retired from their positions in the past year and the number of employees did not increase. 250,000 yuan / person / year is the per capita income calculated based on human resource cost in our factory.

[0024] ② System energy consumption: Through centralized water supply, the shutdown of the second thermal power water system, dry quenching of coke, unmanned operation of Unit 4 and the 50,000-ton water station at night were achieved, the system stopped operating, the acid and alkali loss was reduced, and the operating power consumption (negligible) was reduced, resulting in a cumulative reduction of production costs by 287,700 yuan / year.

[0025] The calculation formula is as follows: Benefit = reduced acid and alkali consumption × acid and alkali price = 184 × 0.04 + 230 × 0.0935 = 287,700 yuan / year; Acid and alkali consumption = resin amount × 100kg / m 3 × number of regenerations; Cationic bed acid consumption = 5m 3 ×100kg / m 3 / 1000×365=184t; Alkali consumption of anion bed = 6.3×100kg / m 3 / 1000×365=230t.

[0026] Among them, the resin amount is the filling amount of the system bed, 100 (kg / m 3 The quota of resin is the actual value selected by combining the design requirement with the actual on-site usage. The number of 365 regenerations is the actual value occurred during system operation. The acid and alkali prices are the latest winning bid prices of the system (200 yuan / ton lower than last year).

[0027] (2) Social benefits: Through system automation upgrades, the labor intensity of employees is reduced and the sense of happiness of employees and the company is improved. The overall system has no wastewater discharge, and the environmental benefits are obvious.

[0028] Example 1

[0029] like Figure 1As shown, the first chemical water station includes a first-level desalted water tank and a second-level desalted water tank, the second chemical water station includes a second thermoelectric desalted water tank, the third chemical water station includes a dry coke quenching desalted water tank, the fourth chemical water station includes a No. 4 unit desalted water tank, and the fifth chemical water station includes an intermediate water tank and a 50,000 ton desalted water tank that are interconnected; the first-level desalted water tank, the intermediate water tank, the second thermoelectric desalted water tank and the dry coke quenching desalted water tank are interconnected, the second-level desalted water tank, the No. 4 unit desalted water tank and the 50,000 ton desalted water tank are interconnected, and the second-level desalted water tank, the dry coke quenching desalted water tank, the 50,000 ton desalted water tank and the No. 4 unit desalted water tank are respectively connected to the corresponding boilers.

[0030] As mentioned above, the power plant has multiple boilers and desalted water pumps. The boilers include the CDQ waste heat boilers, boilers 1-6, and the blast furnace. The CDQ desalted water tank is connected to the CDQ waste heat boilers, the 50,000 desalted water tank is connected to boilers 1-3, the unit 4 desalted water tank is connected to boilers 4-5, and the secondary desalted water tank is connected to boiler 6. Desalted water pumps are installed between the desalted water tanks and the boilers to ensure the supply of desalted water to the boilers.

[0031] Specifically, the second thermoelectric desalted water tank is connected to the dry coke quenching desalted water tank, and the dry coke quenching desalted water tank is connected to the dry coke quenching waste heat boiler; the first-level desalted water tank is connected to the intermediate water tank, the intermediate water tank is connected to the 50,000 desalted water tank, and the 50,000 desalted water tank is connected to boilers 1 to 3; the desalted water tank of unit 4 is connected to boilers 4 to 5, the second-level desalted water tank is connected to boiler 6, and the second-level desalted water tank is connected to the desalted water tank of unit 4.

[0032] The connecting pipeline between the second thermoelectric desalted water tank and the dry quenching desalted water tank is connected to the connecting pipeline between the first-level desalted water tank and the intermediate water tank, and the connecting pipeline between the first-level desalted water tank and the intermediate water tank is connected to the connecting pipeline between the second-level desalted water tank and the No. 4 unit desalted water tank.

[0033] The primary and secondary demineralized water tanks are interconnected, with a connecting valve installed in the connecting pipe between them. In emergency situations (such as equipment failure at an older water station or insufficient water production capacity), the primary and secondary demineralized water tanks can also be connected.

[0034] In addition, the CDQ desalted water is also connected to the external desalted water tank for the blast furnace, and the external desalted water tank for the blast furnace is connected to the blast furnace through a desalted water pump to supply water; and on the connecting pipeline between the second thermoelectric desalted water tank and the CDQ desalted water tank, additional desalted water tanks are also connected, such as No. 1 180 desalted water tank, No. 2 180 desalted water tank and 360 desalted water tank, and No. 1 180 desalted water tank and No. 2 180 desalted water tank are connected in series. The above-mentioned additional desalted water tanks are used to supply water to the 180 boiler and the 360 ​​boiler respectively.

[0035] Furthermore, return pipes are respectively provided between the output and input ends of the first-stage desalted water tank, the second-stage desalted water tank and the second thermoelectric desalted water tank. Return valves are installed on the return pipes. The return valves can control the on-off of the return pipes. That is, when the water supply stops, the return valve is turned on, and the water in the pipes can flow back to the corresponding water tanks, avoiding water being trapped in the pipes and affecting the safety and service life of the pipe equipment.

[0036] The intermediate water tank is equipped with a decarbonizer, which is connected to the 50,000 ton desalted water tank via a process water pump and an ion exchanger. Decarbonizers are a state-of-the-art technology used in water treatment systems to remove carbon dioxide (CO2). They are used in desalinated water systems that utilize ion exchange processes. Their core function is to reduce the CO2 content in the water through physical or chemical methods, preventing it from adversely affecting the subsequent desalination process. Ion exchangers utilize ion exchange resins to reversibly exchange ions with water to remove salt, hardness, and other impurities.

[0037] In order to achieve cost reduction and efficiency improvement, the DCS system screens of the second to fifth chemical water stations are centralized in the control room of the first chemical water station, so that the personnel of each water station can be concentrated in the newly built No. 6 chemical water station.

[0038] Example 2

[0039] like Figure 2 As shown, based on Example 1, the present invention also proposes process steps for preparing desalted water using a full membrane process in the first water treatment station, including preliminary filtration, ultrafiltration, two-stage RO device desalination, EDI device desalination and other steps.

[0040] The domestic water in the factory enters the raw water tank for storage, and is pumped to the multi-media filter through the filter lift pump. After filtering through the multi-media filter, preliminary filtered water is obtained, and then the preliminary filtered water enters the filter water production tank for temporary storage, thereby achieving preliminary filtration of domestic water.

[0041] The preliminary filtered water is first pumped into the heater through the ultrafiltration lift pump for heating, and then enters the self-cleaning filter for further filtration, and then ultrafiltered through the ultrafiltration device to obtain ultrafiltered water, and finally enters the ultrafiltration water tank for temporary storage to complete the ultrafiltration step.

[0042] The ultrafiltration water first passes through the first-level RO lifting pump, safety filter, first-level RO high-pressure pump, and first-level RO device in sequence and enters the first-level RO water production tank to complete the first-level RO device desalination; then passes through the second-level RO lifting pump, safety filter, second-level RO high-pressure pump, and second-level RO device in sequence and enters the first-level desalted water tank to obtain first-level desalted water.

[0043] Under the action of the EDI lifting pump, the first-level desalted water passes through the safety filter and the EDI device in turn and enters the second-level desalted water tank to obtain second-level desalted water. The second-level desalted water can be pumped into the thermal system, that is, the corresponding boiler, through the desalted water pump.

[0044] Among them, the RO device (Reverse Osmosis Device) is a core water treatment device that utilizes the selective permeation principle of a reverse osmosis membrane to separate water from dissolved salts and impurities under pressure. The EDI device (Electrodeionization Device) is a deep desalination device that combines ion exchange resins with electrodialysis technology. It can produce ultrapure water without the need for chemical regeneration. This technology overcomes the limitations of traditional ion exchange processes that require frequent use of acids and alkalis.

[0045] The comparison between the ion exchange bed process and the full membrane process in various dimensions is shown in the following table:

[0046] It can be seen that the new chemical water station adopts the full membrane process and is connected to the desalted water network of the original plant area, which can make the overall acid and alkali consumption of the system extremely small, the degree of automation high, the operation economy high, and the manual maintenance required small.

[0047] Compared with improving and upgrading the original four water treatment plants, which would result in increased investment costs and a longer time, the desalted water system proposed in the present invention is based on the original equipment and combined with the newly built water treatment plant, so that the pipelines of the latter are connected to the pipeline network of the former, thereby completing the upgrade and improvement of the water treatment process at a relatively low cost and in a shorter time.

[0048] In summary, the present invention proposes a desalted water system that can be applied to the situation where chemical water treatment stations of self-owned power plants of large steel mills are dispersed, so as to realize the mutual sharing of desalted water throughout the plant, deep treatment of large industrial water reuse, system fine desalination, water balance of the whole plant, and good economic use and application prospects in the field of energy conservation.

[0049] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0050] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0051] The above description is based on the ideal embodiment of the present invention. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the content of the specification and must be determined according to the scope of the claims.

Claims

1. A desalted water system for a steel plant's self-owned power plant, characterized by: It includes five chemical water stations. The first chemical water station includes a primary desalted water tank and a secondary desalted water tank. The second chemical water station includes a secondary thermal power desalted water tank. The third chemical water station includes a CDQ desalted water tank. The fourth chemical water station includes a No. 4 unit desalted water tank. The fifth chemical water station includes an interconnected intermediate water tank and a 50,000 ton desalted water tank. The first-level desalted water tank, the intermediate water tank, the second thermoelectric desalted water tank and the dry quenching desalted water tank are interconnected, the second-level desalted water tank, the fourth unit desalted water tank and the 50,000 desalted water tank are interconnected, and the second-level desalted water tank, the dry quenching desalted water tank, the 50,000 desalted water tank and the fourth unit desalted water tank are respectively connected to the corresponding boilers.

2. The desalted water system of the steel plant's self-provided power plant according to claim 1, characterized in that: The primary desalted water tank and the secondary desalted water tank are connected to each other, and a connecting valve is installed on the connecting pipeline between the two.

3. The desalted water system of the steel plant's self-provided power plant according to claim 1, characterized in that: A return pipeline is provided between the output end and the input end of the first-level desalted water tank, the second-level desalted water tank and the second thermoelectric desalted water tank, and a return valve is installed on the return pipeline.

4. The desalted water system of the steel plant's self-provided power plant according to claim 1, characterized in that: A decarbonizer is provided inside the intermediate water tank, and the intermediate water tank is connected to the 50,000 ton desalted water tank through a process water pump and an ion exchanger.

5. The desalted water system of the steel plant's self-provided power plant according to claim 1, characterized in that: The connecting pipeline between the second thermoelectric desalted water tank and the CDQ desalted water tank is connected with an additional desalted water tank for supplying water to the corresponding boiler.

6. The desalted water system of a steel plant's self-provided power plant according to claim 1, characterized in that: The first water treatment station adopts the full membrane process, and the second to fifth water treatment stations adopt the ion exchange bed process.

7. The desalted water system of the steel plant's self-provided power plant according to claim 6, characterized in that: The DCS system screens of the second to fifth chemical water stations are centrally located in the control room of the first chemical water station.

8. The desalted water system for a steel plant's self-provided power plant according to any one of claims 1 to 7, characterized in that: The water production process steps of the first chemical water station include: S1. The domestic water in the raw water tank passes through the multi-media filter into the filter water tank to obtain preliminary filtered water; S2, the preliminary filtered water passes through the ultrafiltration device into the ultrafiltration water production tank to obtain ultrafiltered water; S3, the ultrafiltered water is desalted by two-stage RO devices in sequence and then enters the first-stage desalted water tank to obtain the first-stage desalted water; S4. The primary desalted water is desalted by the EDI device and then enters the secondary desalted water tank to obtain secondary desalted water.

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