A kind of purification equipment for 1000MW thermal power unit indirect air cooling system circulating water

Abstract

The utility model relates to a kind of purification equipment for 1000MW thermal power generating unit indirect air cooling system circulating water, pass through the large flow filter of series connection, cation exchanger and anion exchanger, effectively remove the impurity, suspended matter and ionic pollutant in circulating water, ensure that circulating water quality meets standard.The equipment is equipped with water quality monitoring system, differential pressure monitoring system and resin catcher, ensure that water quality, and reduce system water consumption and maintenance cost.At the same time, equipment uses modular design, it is convenient to install and maintain, and is equipped with bypass to facilitate repair.The utility model is especially suitable for north coal-rich water-scarce area, help to prevent indirect cooling system corrosion, improve unit operation efficiency and safety.

Description

Technical Field

[0001] This utility model is used for the purification of circulating water in indirect air-cooled units of thermal power plants. It is a purification device for circulating water in indirect air-cooled systems of thermal power units. Background Technology

[0002] In coal-rich but water-scarce regions of northern my country, the application of SCAL-type indirect air-cooling technology as a condensation method for turbine exhaust steam has become widespread. However, this type of air-cooling system lacks specific anti-corrosion measures. Long-term substandard conductivity, pH, suspended solids, Al ions, and Fe ions in the system's circulating water will cause severe corrosion of the indirect cooling system. Investigations have revealed multiple corrosion leaks that have occurred in indirect-cooled units during actual operation.

[0003] When the pH value exceeds the standard, the Al2O3 protective film on the inner surface of the aluminum tube bundle will gradually dissolve in the water, causing corrosion of the cooling triangular aluminum tube bundle. The higher the pH value, the faster the corrosion rate of the cooling triangular aluminum tube bundle.

[0004] Excessive conductivity can cause electrochemical corrosion in the intercooling system, leading to Fe and Al corrosion of the equipment. Increased corrosion can cause increased turbidity in the circulating water. When the turbidity exceeds the standard, it will affect the heat transfer of the intercooling system and the unit's load-bearing capacity.

[0005] After system corrosion, the 1mm thick aluminum heat exchange tube bundle is highly susceptible to corrosion and leakage. On the other hand, the ring tubes are made of carbon steel, and when the pH or conductivity of the water exceeds the standard, a large amount of corrosion products will be generated. When the corrosion products accumulate in the water, the turbidity of the water will increase. After being deposited on the heat exchange tube bundle, it will cause a decrease in the heat transfer of the aluminum heat exchange tube bundle, affecting the normal load of the unit and posing a safety hazard to the unit operation.

[0006] The "DL / T 2295-2021 Guidelines for Corrosion Control of Circulating Cooling Water Systems for Surface-Type Indirect Air-Cooled Units" specifies the following water quality standards for circulating water in surface-type indirect air-cooled systems: conductivity (25℃) ≤ 2μS / cm, pH value (25℃) 7.0~8.3, suspended solids ≤ 10NTU, Al ions ≤ 50ug / L, Fe ions ≤ 100ug / L, chloride ions ≤ 100ug / L, and sulfate ions ≤ 50ug / L.

[0007] In addition, mechanical impurities (sand, soil, iron oxide, aluminum oxide, etc.) in the circulating water can scratch stainless steel, carbon steel, and pure aluminum equipment and pipes, so the fewer mechanical impurities, the better. However, in the SCAL type indirect air-cooled units currently in operation, because there is no purification system for treatment, the conductivity of the circulating water exceeds the standard, and there are also a lot of mechanical impurities in the circulating water. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, the purpose of this utility model is to provide a purification device for circulating water in the indirect air-cooling system of thermal power units. To achieve the above objective, the technical solution provided by this utility model is as follows: A purification device for circulating water in the indirect air-cooling system of a 1000MW thermal power unit includes a high-flow filter, a cation exchanger, and an anion exchanger connected in series and equipped with a maintenance bypass.

[0009] The outlet points of the cation exchanger and anion exchanger are equipped with sampling points or online pH meters and conductivity meters for monitoring the quality of the effluent.

[0010] The high-flow-rate filter is equipped with a differential pressure monitoring system at both the inlet and outlet sections.

[0011] A resin trap is installed on the outlet header of the equipment, and differential pressure monitoring is installed at the inlet and outlet of the resin trap.

[0012] The equipment's inlet or outlet water pipe is connected to the maintenance manhole of the return water pipe (cold pipe section) of different sectors of the indirect cooling system.

[0013] The high-flow filter inlet is also connected to a booster pump, and the booster pump inlet is connected to a pipe leading out from the maintenance manhole of the indirect air-cooling system circulating water; the booster pump is equipped with a frequency converter.

[0014] The filters, cation exchangers, and anion exchangers of the purification equipment are respectively arranged inside a standard container, with pre-installed connection pipe heads on the side.

[0015] The cation exchangers and anion exchangers are connected to the pipelines using flexible connections.

[0016] The cation exchanger and anion exchanger are portable, making it easy to move them to the unit's regeneration room when the resin becomes unusable.

[0017] Add a tee and corresponding valve after the acid-base injector or acid-base metering pump in the original regeneration system of the unit's regeneration room; one tee is for normal regeneration of the unit, and the other is for the purification equipment.

[0018] The beneficial effects of this utility model are: This invention takes into account the types of impurities in the circulating water of indirect air-cooled systems and removes these impurities in a targeted manner, thereby ensuring that the circulating water quality of the indirect air-cooled system meets the standard requirements, preventing various types of corrosion caused by substandard water quality, reducing the water consumption of the indirect air-cooled system, and extending the maintenance cycle of the indirect air-cooled system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the specific structure of the purification equipment described in this utility model.

[0020] In the diagram, (1) is a filter, (2) is a cation exchanger, and (3) is an anion exchanger. Detailed Implementation

[0021] This invention provides a purification device for circulating water in the indirect air-cooling system of a 1000MW thermal power unit, as shown in the attached diagram. The main components of this purification device are a booster filter and anion / cation exchangers. The equipment is integrated into three containers for easy on-site installation. The connection between the purification device and the indirect cooling system is achieved by replacing the existing manholes; the existing manholes on the indirect cooling system piping are removed. Two manholes of the same specifications, equipped with pipes and valves, are then used to replace the previous manholes.

[0022] A purification device for circulating water in the indirect air-cooling system of a 1000MW thermal power unit, comprising: The booster pump, high-flow filter, cation exchanger, and anion exchanger are connected in series. Each of the above devices is connected to a bypass pipeline. Valves are installed on the inlet and outlet pipelines and bypass pipelines of each device. The main equipment dimensions are: filter DN550mm and cation and anion exchanger DN2200mm.

[0023] The purification equipment is installed inside the cooling tower, in the open space between two adjacent sectors. This facilitates connection between the purification equipment and the cooling system. The equipment's inlet or outlet water pipe connects to the maintenance manhole of the return water pipe (cold pipe section) of different sectors of the cooling system.

[0024] The inlet and outlet of the purification equipment are connected to two sectors of the intercooling system, respectively. This allows the circulating water in the intercooling system to be purified via a bypass before returning to the intercooling system. The filters, cation exchangers (cation bed), and anion exchangers (anion bed) in the purification equipment operate in series; each treatment unit is also equipped with a bypass for maintenance and repair.

[0025] The purification equipment is arranged in three containers, with a processing capacity of approximately 100 tons per hour.

[0026] The specific description of the purification equipment for circulating water in the indirect air-cooling system of thermal power units according to this utility model is as follows: 1) Handling method The new equipment and the indirect cooling system adopt a bypass treatment method. A portion of the circulating water from a certain sector of the indirect cooling system is selected as the equipment's inlet water, and the equipment's outlet water is returned to an adjacent sector of the same system. The connection method does not require cutting or welding. Considering the large circulation flow rate and large system water volume of the indirect cooling system, the bypass treatment mode is considered for treating the circulating water.

[0027] 2) Purification process Water purification involves simultaneous filtration and desalination. The desalination section employs an ion exchange bed configuration. Most commonly used water treatment processes combine filtration and desalination in various ways; the best approach will be researched and selected based on site conditions. Preliminary considerations include the influent and effluent conditions of the proposed solution, as well as the installation, operation, and maintenance of the equipment.

[0028] 3) Recycling process The desalination section in the purification equipment is a recyclable and reusable component.

[0029] 4) Post-treatment water quality testing The proposed new unit will be equipped with online instruments for real-time monitoring of effluent pH and conductivity. Testing of the circulating water in the intercooling system is a routine water quality test conducted by the power plant laboratory; pH ​​and conductivity are already measured online, while turbidity, Al, and Fe ions were previously tested periodically. After the unit is commissioned, the operating mode can be adjusted based on the effluent and circulating water quality indicators.

[0030] Based on the water quality analysis of the indirect air-cooled system's circulating water, the sources of water pollution and the causes of water quality exceeding standards are determined, and the most suitable treatment process is selected. The process technology must be mature, safe, and scientifically sound. After commissioning, the circulating water quality of the indirect air-cooled unit should meet the requirements of "DL / T 2295-2021 Guidelines for Corrosion Control of Circulating Cooling Water Systems for Surface-Type Indirect Air-Cooled Units".

[0031] Using the bypass treatment device described in this utility model, the water quality of the circulating water in the intercooling system can fully meet the standards after bypass purification, for example, the following scheme: Example 1 A power plant's 1000MW supercritical generator unit is a SCAL-type indirect air-cooled unit with a total circulating water volume of 10,000 m³. The unit has been in commercial operation for approximately two years, with the circulating water temperature in the low-temperature section ranging from 30℃ to 50℃. The circulating water contains silt and rust, is light yellow and slightly turbid, and has a maximum conductivity of 22 μS / cm. 2 The pH level consistently exceeded the standard. The pH remained between 7.1 and 7.9.

[0032] Water is drawn from the low-temperature branch pipes of sectors 7 and 8 in several indirect cooling systems and connected to the circulating water system of the SCAL type indirect air-cooled unit. A booster pump is put into operation to increase pressure, a high-flow-rate cartridge filter is put into operation, a cation exchanger + anion exchanger is put into operation, and a mixed bed is put into operation, ultimately returning the water to the low-temperature section of the circulating water system. The bypass flow rate of the circulating water is 100 t / h, and it is operated for five weeks. During this period, the filter cartridges are replaced in a timely manner according to the pressure difference; based on the conductivity of each desalination module, the cation exchanger, anion exchanger, and mixed bed module are replaced once each. The conductivity of the circulating water is ≤2 μs / cm. 2 The pH is 7.3~8.1, the water is clear and the turbidity is ≤10UNT, and the water quality fully meets the standards.

[0033] Example 2 A power plant's 1000MW ultra-supercritical generator unit is a SCAL-type indirect air-cooled unit with a total circulating water volume of 8000m³. The unit has been in commercial operation for approximately one year, with the circulating water temperature in the high-temperature section ranging from 55℃ to 65℃. The circulating water contains silt and rust, with a turbidity of 176~202 NTU and a conductivity reaching a maximum of 30~50 μS / cm. 2 The pH level consistently exceeded the standard. The pH remained between 7.5 and 8.2.

[0034] Water is drawn from the return water pipes of sectors 10 and 11 in several indirect air-cooled systems, connected to the circulating water purification device of the SCAL type indirect air-cooled unit, and then returned to the high-temperature section of the circulating water after treatment. The bypass flow rate of the circulating water is 100t / h. In the initial stage of treatment, a booster pump is put into operation to increase the pressure, and a high-flow-rate cartridge filter, bypass cation exchanger, anion exchanger, and mixed bed are put into operation. After three weeks of operation in the above mode, the turbidity of the indirect air-cooled circulating water decreases to 3~10 NUT. In the fourth week, the cation exchanger and anion exchanger are put into operation and continue to operate for four weeks. During this period, the filter cartridges are replaced in a timely manner according to the pressure difference. Based on the conductivity of each desalination module, the conductivity of the circulating water is ≤2μs / cm. 2 The pH is 7.3~8.2, the turbidity is ≤10UNT, the water is clear, and the water quality fully meets the standards.

[0035] This method completely avoids the pressure on power plant water production caused by large-scale demineralized water replacement; because each part involved specifically removes various impurities from the circulating water, addressing different water qualities. A single set of equipment solves the problem of excessive circulating water quality in the intercooling system.

Claims

1. A purification device for circulating water in the indirect air-cooling system of a 1000MW thermal power unit, characterized in that: The purification equipment is installed inside the indirect cooling tower, including a high-flow-rate filter (1), a cation exchanger (2), and an anion exchanger (3) connected in series with a maintenance bypass; the inlet of the high-flow-rate filter (1) is also connected to a booster pump, and the inlet of the booster pump is connected to a pipe leading out from the maintenance manhole of the indirect air-cooling system circulating water; the booster pump is equipped with a frequency converter; the filter, cation exchanger, and anion exchanger of the purification equipment are respectively arranged in a standard container, with reserved connection pipe heads on the side; the cation exchanger and anion exchanger are connected to the pipeline by a flexible connection; the inlet and outlet sections of the high-flow-rate filter are equipped with differential pressure monitoring systems; a resin trap is installed on the outlet header of the equipment, and differential pressure monitoring is installed at the inlet and outlet of the resin trap.

2. The purification equipment for circulating water in the indirect air-cooling system of a 1000MW thermal power unit according to claim 1, characterized in that: The outlet points of the cation exchanger and anion exchanger are equipped with sampling points or online pH meters and conductivity meters for monitoring the quality of the effluent.

3. A purification device for circulating water in an indirect air-cooled system of a 1000MW thermal power unit according to claim 2, characterized in that: The equipment's inlet or outlet water pipe is connected to the maintenance manhole of the return water pipe in different sectors of the intercooling system.

4. A purification device for circulating water in an indirect air-cooled system of a 1000MW thermal power unit according to claim 3, characterized in that: The cation exchanger and anion exchanger are portable, making it convenient to move them to the unit's regeneration room when the resin becomes unusable.

5. A purification device for circulating water in an indirect air-cooled system of a 1000MW thermal power unit according to claim 4, characterized in that: Add a tee and corresponding valve after the acid-base injector or acid-base metering pump in the original regeneration system of the unit's regeneration room; one tee is for normal regeneration of the unit, and the other is for the purification equipment.

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