A power plant boiler chemical cleaning dispensing system and method

Abstract

The application discloses a chemical cleaning dispensing system and method for a boiler of a thermal power plant, and belongs to the technical field of chemical cleaning. The system comprises a cleaning tank, a cleaning pump, a dispensing pump, a Venturi dosing device and a self-circulation bypass. The outlet of the cleaning tank is divided into two branches, the first branch is connected with the inlet of the cleaning pump, and the second branch is connected with the inlet of the dispensing pump. The outlet of the cleaning pump is divided into three branches, the first branch is connected with the inlet of the Venturi dosing device, the outlet of the Venturi dosing device is connected with the cleaning tank, and the Venturi dosing device is used for sucking solid and liquid chemical cleaning agents into the cleaning tank, the second branch is connected with the inlet of the self-circulation bypass, and the outlet of the self-circulation bypass is connected with the cleaning tank. The third branch is connected with the boiler of the thermal power plant. The outlet of the boiler of the thermal power plant is divided into three branches, the first branch is connected with the cleaning tank, the second branch is connected with the inlet of the cleaning pump, and the third branch is connected with a wastewater pool. The chemical cleaning system is simplified, the installation cost and installation period of the chemical cleaning system are reduced, and the wastewater amount generated by the chemical cleaning is reduced.

Description

Technical Field

[0001] This invention belongs to the field of chemical cleaning technology in the power industry, specifically relating to a chemical cleaning dosing system and method for boilers in thermal power plants. Background Technology

[0002] Currently, the main coal-fired power generating units under construction and in operation have an installed capacity ranging from 300MW to 1000MW. Their economizers and water-cooled wall heating surfaces have large water volumes, with some units exceeding 300m³. 3 Due to their long operating time, these thermal power units are currently facing problems such as large scale buildup on economizers and water-cooled wall heat exchange tubes, resulting in low heat exchange efficiency and frequent tube ruptures. Chemical cleaning is a common method used for these units. Since chemical cleaning generates wastewater, which falls under the category of waste acid from the chemical cleaning of boiler HW34 (listed as hazardous waste), reducing the amount of wastewater generated by chemical cleaning is imperative, considering environmental protection and hazardous waste disposal risks. Therefore, more and more cleaning companies are beginning to use citric acid or EDTA as the main cleaning medium in their cleaning processes.

[0003] When using citric acid or EDTA for chemical cleaning, the pH of the cleaning solution at the pump outlet must be maintained between 3.5 and 5.5. The current method involves switching the cleaning system to a self-circulating operation mode between the pump and the cleaning tank once the system is ready for chemical dosing. Solid citric acid or EDTA is first added to the cleaning tank, followed by ammonia to adjust the pH. After pH adjustment, the cleaning solution is then pumped into the system to begin chemical cleaning. Because thermal power units currently have large water volumes, the amount of citric acid or EDTA used in chemical cleaning is substantial, ranging from 15 to 20 tons. However, standard cleaning tanks used by chemical cleaning units are typically only 10 to 15 cubic meters. 3 This method is insufficient to meet the requirements for drug preparation. If the cleaning tank is used directly for batch drug preparation, the cleaning solution entering the cleaning system, due to its static state, can easily cause sedimentation of the cleaning agents. The usual practice is to fabricate a large temporary drug preparation tank on-site, with a water volume of 80-100 m³. 3 Temporary drug preparation tanks occupy a large area, take a long time to manufacture, and are costly. On-site manufacturing is prone to leakage problems due to construction period and process issues, which can easily lead to environmental accidents. Because temporary drug preparation tanks have a large water volume, the water rinsing step after chemical cleaning requires a large amount of demineralized water to clean them. The chemical cleaning system also requires the use of a standard cleaning tank, which makes the cleaning system complex, the installation period long, and the operation complicated. Summary of the Invention

[0004] The purpose of this invention is to provide a chemical cleaning dosing system and method for boilers in thermal power plants. This system changes the dosing method of citric acid or EDTA, enabling the dosing process to be carried out simultaneously with boiler cleaning, thus avoiding the need to build large temporary dosing tanks on-site.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The first aspect of the present invention provides a chemical cleaning and dosing system for boilers in thermal power plants, including a cleaning tank, a cleaning pump, a dosing pump, a Venturi dosing device, and a self-circulating bypass;

[0007] The outlet of the cleaning tank is divided into two paths: the first path is connected to the inlet of the cleaning pump; the second path is connected to the inlet of the dispensing pump.

[0008] The cleaning pump outlet is divided into three paths. The first path is connected to the inlet of the Venturi dosing device, and the outlet of the Venturi dosing device is connected to the cleaning tank. The Venturi dosing device is used to draw solid and liquid chemical cleaning agents into the cleaning tank. The second path is connected to the inlet of the self-circulation bypass, and the outlet of the self-circulation bypass is connected to the cleaning tank. The third path is connected to the boiler of the thermal power plant.

[0009] The boiler outlet of the thermal power plant is divided into three routes: the first route is connected to the cleaning tank, the second route is connected to the inlet of the cleaning pump, and the third route is connected to the wastewater pool.

[0010] The dosing pump outlet is divided into three paths: the first path is connected to the inlet of the Venturi dosing device; the second path is connected to the inlet of the self-circulation bypass; and the third path is connected to the inlet of the cleaning pump.

[0011] As a further improvement of the present invention, the cleaning tank is a chemical cleaning system device.

[0012] As a further improvement of the present invention, the Venturi dosing device is a negative pressure injector.

[0013] As a further improvement of the present invention, a first valve is provided on the pipe connecting the first path of the cleaning tank to the inlet of the cleaning pump; a second valve is provided on the pipe connecting the second path of the cleaning tank to the inlet of the dispensing pump.

[0014] As a further improvement of the present invention, a third valve is provided on the pipeline connecting the first path of the cleaning pump to the inlet of the Venturi dosing device; a fourth valve is provided on the pipeline connecting the second path of the cleaning pump to the inlet of the self-circulation bypass; a fifth valve is provided on the pipeline connecting the third path of the cleaning pump to the boiler of the thermal power plant; a sixth valve is provided on the pipeline connecting the first path of the cleaning pump to the cleaning tank; a seventh valve is provided on the pipeline connecting the second path of the cleaning pump to the inlet of the cleaning pump; and an eighth valve is provided on the pipeline connecting the third path of the cleaning pump to the wastewater tank.

[0015] As a further improvement of the present invention, a ninth valve is provided on the pipeline connecting the first path of the dosing pump to the inlet of the Venturi dosing device; a tenth valve is provided on the pipeline connecting the second path of the dosing pump to the inlet of the self-circulation bypass; and an eleventh valve is provided on the pipeline connecting the third path of the dosing pump to the inlet of the cleaning pump.

[0016] As a further improvement of the present invention, the cleaning box is transported by a semi-trailer.

[0017] As a further improvement of the present invention, the flow rate of the cleaning pump is 1100t / h, and the flow rate of the dispensing pump is 160t / h.

[0018] A second aspect of the present invention provides a method for preparing chemicals for a chemical cleaning system in a thermal power plant boiler, comprising:

[0019] Once the chemical cleaning system is ready for dosing, maintain the circulation of the dosing pump and the cleaning tank, open the inlet valve of the Venturi dosing device, and add solid and liquid chemical cleaning agents to the cleaning tank in batches according to the proportion, controlling the pH of the cleaning solution at the outlet of the dosing pump to be in the acidic range.

[0020] Once the first batch of cleaning solution is prepared, it will be injected into the boiler chemical cleaning system.

[0021] Once the liquid level in the cleaning tank drops to the minimum required level, continue preparing the second batch of cleaning solution, and so on, until the cleaning solution is fully prepared.

[0022] Once the liquid level in the boiler chemical cleaning system reaches the maximum required level, a portion of the cleaning solution will be discharged into the wastewater tank.

[0023] The solid and liquid chemical cleaning agents include solid citric acid and solid EDTA.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The present invention relates to a chemical cleaning dosing system for thermal power plant boilers, comprising a cleaning tank, a cleaning pump, a dosing pump, a Venturi dosing device, and a self-circulating bypass. Based on the new dosing method employed by the Venturi dosing device, the dosing process is carried out simultaneously with boiler cleaning, solving the drawback of requiring the on-site fabrication of large dosing tanks when cleaning large-capacity boilers in thermal power plants using citric acid or EDTA. This addresses the problems of long fabrication time, high cost, significant leakage risk, and potential environmental accidents associated with large dosing tanks. The system simplifies the chemical cleaning system, reduces installation costs and construction time, and minimizes wastewater generation during chemical cleaning. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a chemical cleaning and dosing system for a thermal power plant boiler provided in an embodiment of the present invention. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0029] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0030] In response to the problems raised in the background technology, there is an urgent need to improve the chemical cleaning system and methods for citric acid or EDTA cleaning of large-capacity boilers in thermal power plants, simplify the chemical cleaning system, and reduce the installation cost and construction period of the chemical cleaning system.

[0031] Therefore, the first objective of this invention is to provide a chemical cleaning and dosing system for boilers in thermal power plants, comprising a cleaning tank 1, a cleaning pump 2, a dosing pump 3, a Venturi dosing device 4, and a self-circulating bypass 5.

[0032] The outlet of the cleaning tank 1 is divided into two paths: the first path is connected to the inlet of the cleaning pump 2; the second path is connected to the inlet of the dispensing pump 3.

[0033] The outlet of the cleaning pump 2 is divided into three paths. The first path is connected to the inlet of the Venturi dosing device 4, and the outlet of the Venturi dosing device 4 is connected to the cleaning tank 1. The Venturi dosing device 4 is used to draw solid and liquid chemical cleaning agents into the cleaning tank 1. The second path is connected to the inlet of the self-circulation bypass 5, and the outlet of the self-circulation bypass 5 is connected to the cleaning tank 1. The third path is connected to the boiler 6 of the thermal power plant.

[0034] The outlet of the thermal power plant boiler 6 is divided into three paths: the first path is connected to the cleaning tank 1, the second path is connected to the inlet of the cleaning pump 2, and the third path is connected to the wastewater pool 7.

[0035] The outlet of the dosing pump 3 is divided into three paths: the first path is connected to the inlet of the Venturi dosing device 4; the second path is connected to the inlet of the self-circulation bypass 5; and the third path is connected to the inlet of the cleaning pump 2.

[0036] The chemical cleaning dosing system for thermal power plant boilers of the present invention changes the dosing method. When the chemical cleaning system is ready for dosing, the cleaning pump is switched off to establish a closed loop between the cleaning pump and the thermal power plant boiler, maintaining the operation of the cleaning system. The cleaning solution is injected into the cleaning system in batches through the dosing pump and the cleaning tank. Since the cleaning system is in operation, the batch addition of the cleaning solution will not cause the cleaning agent to settle. The dosing process is carried out simultaneously with the boiler cleaning.

[0037] This invention utilizes the Venturi effect, also known as the Venturi effect, of the Venturi dosing device 4. This effect manifests as an increase in fluid velocity when confined flow passes through a narrowed cross-section; the velocity is inversely proportional to the cross-sectional area. According to Bernoulli's law, the increase in velocity is accompanied by a decrease in fluid pressure, which is the common Venturi phenomenon. This effect refers to the generation of low pressure near a high-speed flowing fluid, thereby producing an adsorption effect.

[0038] Based on the negative pressure injection principle of the Venturi dosing device 4, solid and liquid dosing agents can be injected into the cleaning tank 1, and the dosing process is carried out simultaneously with the boiler cleaning.

[0039] The system of the present invention will be described in detail below with reference to specific embodiments.

[0040] Example 1

[0041] This invention provides a chemical cleaning and dosing system for boilers in thermal power plants. (See attached document.) Figure 1The system includes a cleaning tank 1, a cleaning pump 2, a dosing pump 3, a Venturi dosing device 4, and a self-circulating bypass 5. The outlet of the cleaning tank 1 is divided into two paths: the first path is connected to the inlet of the cleaning pump 2, with a first valve on the pipeline; the second path is connected to the inlet of the dosing pump 3, with a second valve on the pipeline. The outlet of the cleaning pump 2 is divided into three paths: the first path is connected to the inlet of the Venturi dosing device 4, with a third valve on the pipeline, and the outlet of the Venturi dosing device 4 is connected to the cleaning tank 1; the second path is connected to the inlet of the self-circulating bypass 5, with a fourth valve on the pipeline, and the outlet of the self-circulating bypass 5 is connected to the cleaning tank 1; the third path is connected to the boiler 6 of the thermal power plant, with a fifth valve on the pipeline. The outlet of the boiler 6 is divided into three paths: the first path is connected to the cleaning tank 1, with a sixth valve on the pipeline; the second path is connected to the inlet of the cleaning pump 2, with a seventh valve on the pipeline; and the third path is connected to the wastewater tank 7, with an eighth valve on the pipeline. The outlet of the dosing pump 3 is divided into three paths. The first path is connected to the inlet of the Venturi dosing device 4, and a ninth valve is installed on the pipeline. The outlet of the Venturi dosing device 4 is connected to the cleaning tank 1. The second path is connected to the inlet of the self-circulation bypass 5, and a tenth valve is installed on the pipeline. The outlet of the self-circulation bypass 5 is connected to the cleaning tank 1. The third path is connected to the inlet of the cleaning pump 2, and an eleventh valve is installed on the pipeline.

[0042] This invention employs a novel dosing method, which solves the drawback of requiring the on-site fabrication of large dosing tanks when using citric acid to clean large-capacity boilers in thermal power plants.

[0043] As an optional embodiment of the present invention, the cleaning tank 1 is a chemical cleaning system with a water volume of 15m³. 3 No on-site manufacturing or assembly is required, and the specifications can be transported by 13-meter semi-trailers.

[0044] As an optional embodiment of the present invention, the cleaning pump 2 has a flow rate of 1100 t / h, a voltage of 6 kV, and a power of 500 kW, which meets the flow rate requirements for chemical cleaning of large-capacity boilers. The dosing pump 3 has a flow rate of 160 t / h, a voltage of 380 V, and a power of 90 kW, which meets the dosing requirements.

[0045] As an optional embodiment of the present invention, the Venturi dosing device 4 is a negative pressure injector used for dosing solid and liquid drugs.

[0046] The second objective of this invention is to provide a dosing method for a chemical cleaning dosing system for boilers in thermal power plants, comprising the following steps:

[0047] Once the chemical cleaning system is ready for dosing, maintain the circulation of the dosing pump 3 and the cleaning tank 1, open the inlet valve of the Venturi dosing device 4, and add solid and liquid chemical cleaning agents to the cleaning tank 1 in batches according to the proportion, and control the pH of the cleaning solution at the outlet of the dosing pump 3 to be in the acidic range.

[0048] Once the first batch of cleaning solution is prepared, it will be injected into the boiler chemical cleaning system.

[0049] Once the liquid level in cleaning tank 1 drops to the minimum required level, continue preparing the second batch of cleaning solution, and so on, until the cleaning solution is fully prepared.

[0050] Once the liquid level in the boiler chemical cleaning system reaches the maximum required level, part of the cleaning solution will be discharged into the wastewater tank 7.

[0051] The method of the present invention will be described in detail below with reference to specific embodiments.

[0052] Example 2

[0053] like Figure 1 As shown, the dosing method of a chemical cleaning dosing system for a thermal power plant boiler according to the present invention is as follows: When the chemical cleaning system is ready for dosing, close the first, third, fourth, sixth, and eighth valves, and open the fifth and seventh valves to maintain the circulation of the cleaning pump 2 and the thermal power plant boiler 6. Open the second, ninth, and tenth valves to maintain the circulation of the dosing pump 3 and the cleaning tank 1. Open the inlet valve of the Venturi dosing device 4 and add solid and liquid chemical cleaning agents to the cleaning tank 1 in batches according to the proportion, controlling the pH of the cleaning solution at the outlet of the dosing pump 3 to be in the acidic range. After the first batch of cleaning solution is prepared, open the eleventh valve to pump the cleaning solution into the boiler chemical cleaning system. When the liquid level in the cleaning tank 1 drops to the minimum required level, close the eleventh valve and continue to prepare the second batch of cleaning solution, and so on until the cleaning solution is prepared. When the liquid level in the boiler chemical cleaning system reaches the maximum required level, open the eighth valve to discharge part of the cleaning solution to the wastewater tank 7.

[0054] When applied, this invention addresses the problems of long manufacturing time and high cost of large-scale drug mixing tanks, the significant risk of leakage, and the potential for environmental accidents. It simplifies the chemical cleaning system and reduces the installation cost and construction period.

[0055] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention. This includes combining various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not further describe the various possible combinations. However, these simple modifications and combinations should also be considered as part of the content disclosed in this invention and are all within the protection scope of this invention.

Claims

1. A chemical cleaning dosing system for a boiler of a thermal power plant, characterized in that: It includes a cleaning tank (1), a cleaning pump (2), a dosing pump (3), a Venturi dosing device (4), and a self-circulating bypass (5); The outlet of the cleaning tank (1) is divided into two paths: the first path is connected to the inlet of the cleaning pump (2); the second path is connected to the inlet of the dispensing pump (3). The outlet of the cleaning pump (2) is divided into three paths. The first path is connected to the inlet of the Venturi dosing device (4), and the outlet of the Venturi dosing device (4) is connected to the cleaning tank (1). The Venturi dosing device (4) is used to draw solid and liquid chemical cleaning agents into the cleaning tank (1). The second path is connected to the inlet of the self-circulating bypass (5), and the outlet of the self-circulating bypass (5) is connected to the cleaning tank (1). The third path is connected to the boiler (6) of the thermal power plant. The outlet of the thermal power plant boiler (6) is divided into three paths: the first path is connected to the cleaning tank (1), the second path is connected to the inlet of the cleaning pump (2), and the third path is connected to the wastewater pool (7). The outlet of the dosing pump (3) is divided into three paths: the first path is connected to the inlet of the Venturi dosing device (4); the second path is connected to the inlet of the self-circulation bypass (5); and the third path is connected to the inlet of the cleaning pump (2).

2. The chemical cleaning dosing system for a boiler of a thermal power plant according to claim 1, characterized in that: The cleaning tank (1) is a chemical cleaning system.

3. The chemical cleaning dosing system for a boiler of a thermal power plant according to claim 1, characterized in that: The Venturi dosing device (4) is a negative pressure injector.

4. The chemical cleaning dosing system for a boiler of a thermal power plant according to claim 1, characterized in that: A first valve is installed on the pipe connecting the first path of the cleaning tank (1) to the inlet of the cleaning pump (2); a second valve is installed on the pipe connecting the second path of the cleaning tank (1) to the inlet of the dispensing pump (3).

5. The chemical cleaning dosing system for a boiler of a thermal power plant according to claim 1, characterized in that: A third valve is installed on the pipeline connecting the first path of the cleaning pump (2) to the inlet of the Venturi dosing device (4); a fourth valve is installed on the pipeline connecting the second path of the cleaning pump (2) to the inlet of the self-circulation bypass (5); and a fifth valve is installed on the pipeline connecting the third path of the cleaning pump (2) to the boiler (6) of the thermal power plant.

6. The chemical cleaning dosing system for a boiler of a thermal power plant according to claim 1, characterized in that: A ninth valve is installed on the pipeline connecting the first path of the dosing pump (3) to the inlet of the Venturi dosing device (4); a tenth valve is installed on the pipeline connecting the second path of the dosing pump (3) to the inlet of the self-circulation bypass (5); and an eleventh valve is installed on the pipeline connecting the third path of the dosing pump (3) to the inlet of the cleaning pump (2).

7. The chemical cleaning dosing system for a boiler of a thermal power plant according to claim 1, characterized in that: The cleaning pump (2) has a flow rate of 1100t / h, and the dispensing pump (3) has a flow rate of 160t / h.

8. The method of dosing a chemical cleaning of a boiler of a thermal power plant according to any one of claims 1 to 7, characterized in that, include: Once the chemical cleaning system is ready for dosing, maintain the circulation of the dosing pump (3) and the cleaning tank (1), open the inlet valve of the Venturi dosing device (4), and add solid and liquid chemical cleaning agents to the cleaning tank (1) in batches according to the proportion, and control the pH of the cleaning solution at the outlet of the dosing pump (3) to be in the acidic range. Once the first batch of cleaning solution is prepared, it will be injected into the boiler chemical cleaning system. When the liquid level in the cleaning tank (1) drops to the minimum required level, continue to prepare the second batch of cleaning solution, and so on until the cleaning solution is prepared. When the liquid level in the boiler chemical cleaning system reaches the maximum required level, part of the cleaning liquid will be discharged into the wastewater pool (7).

9. The method of claim 8, wherein the method further comprises: determining the amount of the chemical to be used in the cleaning process; and determining the amount of the chemical to be used in the cleaning process based on the amount of the chemical to be used in the cleaning process and the concentration of the chemical to be used in the cleaning process. The solid and liquid chemical cleaning agents include solid citric acid and solid EDTA.

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