Vacuum dewatering system for net part of paper machine

Abstract

The utility model discloses a vacuum dewatering system for a net part of a paper machine. The vacuum dewatering system comprises a vacuum device, three steam-water separators, three under-machine white water tanks and three out-machine white water tanks, an outlet pipeline of each steam-water separator is connected to an inlet pipe of the vacuum device; each steam-water separator is respectively provided with a water leg, the water leg of each steam-water separator is respectively connected to the corresponding under-machine white water tank, an inlet pipe of each steam-water separator is connected with at least one vacuum box, each vacuum box is respectively provided with a water leg, and the water leg of each vacuum box is respectively connected to the corresponding off-machine white water tank. According to the technical scheme provided by the utility model, the stable vacuum dehydration process can still be ensured under the conditions that the speed of the paper machine is accelerated and the mixing amount of pulp and water at a net part is greatly increased, so that the vacuum dehydration is uniform and stable, and the reliability and continuity of the operation of the paper machine are greatly improved.

Description

Technical Field

[0001] This utility model relates to the field of papermaking technology, and in particular to a vacuum dewatering system for the wire section of a paper machine. Background Technology

[0002] In the papermaking industry, with the continuous increase in paper machine speed, the pulp-water mixing volume in the wire section increases significantly, posing a severe challenge to vacuum dewatering in the low-vacuum zone of the wire section. Traditional vacuum dewatering systems often experience overfilling of the steam-water separator, leading to poor dewatering, water hammer formation in the vacuum tubes, and vacuum waves, resulting in inconsistent dewatering rates. This unstable vacuum dewatering not only seriously affects paper quality, such as causing poor paper uniformity and large fluctuations in moisture content, but also greatly reduces the operating efficiency of the paper machine, increases the risk of paper breaks, and raises production costs. Therefore, developing a vacuum dewatering system for the wire section of a paper machine can effectively improve the stability of vacuum dewatering in paper machines. Utility Model Content

[0003] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a paper machine wire section vacuum dewatering system, which aims to solve the technical problem that the steam-water separator often becomes full in the existing wire section vacuum dewatering system.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A vacuum dewatering system for the wire section of a paper machine includes a vacuum device, three steam-water separators, three under-machine white water tanks, and three external white water troughs. The outlet pipe of each steam-water separator is connected to the inlet pipe of the vacuum device. Each steam-water separator is equipped with a water leg, and the water legs of each steam-water separator are connected to the corresponding under-machine white water tank. The inlet pipe of each steam-water separator is connected to at least one vacuum box, and each vacuum box is equipped with a water leg, and the water legs of each vacuum box are connected to the corresponding external white water trough.

[0006] Furthermore, in the aforementioned vacuum dewatering system for the wire section of the paper machine, a first valve is installed on the inlet pipe of the vacuum device.

[0007] Furthermore, in the aforementioned vacuum dewatering system of the paper machine wire section, the outlet pipe of each vacuum box is connected to the inlet pipe of the corresponding steam-water separator, and a second valve is provided on the outlet pipe of each vacuum box.

[0008] Furthermore, in the aforementioned vacuum dewatering system for the paper machine wire section, all air-water separators have the same specifications.

[0009] Furthermore, in the vacuum dewatering system of the paper machine wire section, each steam-water separator includes a straight section and a conical section. The inlet pipe of each steam-water separator is connected to the side wall of the straight section; the outlet pipe of each steam-water separator is located at the top of the straight section; and the water leg of each steam-water separator is located at the bottom of the conical section.

[0010] Furthermore, in the vacuum dewatering system of the paper machine wire section, the inlet pipe diameter of each steam-water separator is 100~105mm; the outlet pipe diameter of each steam-water separator is 100~105mm; and the water leg diameter of each steam-water separator is 100~105mm.

[0011] Furthermore, in the aforementioned vacuum dewatering system of the paper machine wire section, the inlet pipe of each steam-water separator is connected to three vacuum chambers respectively.

[0012] Beneficial Effects: This utility model provides a vacuum dewatering system for the wire section of a paper machine. Compared with existing technologies, by combining a vacuum device, three steam-water separators, three under-machine white water tanks, and three external white water troughs, along with the rational connection and layout of each component, it effectively solves the problem of full steam-water separators in traditional vacuum dewatering systems. Even with increased paper machine speed and a significant increase in the amount of pulp mixed in the wire section, it still ensures a stable vacuum dewatering process, avoiding water hammer and vacuum waves formed in the vacuum tubes due to unstable dewatering. This results in a uniform and stable dewatering volume, greatly improving the reliability and continuity of paper machine operation. Furthermore, the rational design of the first valve on the vacuum device inlet pipe, the second valve on the vacuum box outlet pipe, and the third and fourth valves on the water leg enables precise control of the flow rate, pressure, and liquid water discharge of the steam-water mixture, making the entire dewatering process smoother and more efficient. Attached Figure Description

[0013] Figure 1 A schematic diagram illustrating the working principle of one embodiment of the vacuum dewatering system for the wire section of a paper machine provided by this utility model.

[0014] Figure 2 A schematic diagram illustrating the working principle of another embodiment of the vacuum dewatering system for the wire section of a paper machine provided by this utility model.

[0015] Figure 3 This is a front view of the steam-water separator provided in this utility model.

[0016] Numbering on the map:

[0017] 1. Vacuum device; 11. Inlet pipe of vacuum device;

[0018] 2. Steam-water separator; 21. Inlet pipe of steam-water separator; 22. Outlet pipe of steam-water separator; 23. Straight section of steam-water separator; 24. Conical section of steam-water separator; 25. Water leg of steam-water separator;

[0019] 3. Vacuum chamber; 32. Vacuum chamber outlet pipe; 35. Vacuum chamber water leg;

[0020] 4. External white water tank;

[0021] 5. White water pool below the machine;

[0022] 81. First valve; 82. Second valve; 83. Third valve; 84. Fourth valve. Detailed Implementation

[0023] This utility model provides a vacuum dewatering system for the wire section of a paper machine. To make the objectives, technical solutions, and effects of this utility model clearer and more explicit, the following provides a more detailed description. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model.

[0024] Please see Figure 1 and Figure 2 This utility model provides a vacuum dewatering system for the wire section of a paper machine. The accompanying drawings are for illustrative purposes only and are not proportional to the actual product. The drawings only depict structures relevant to the invention of this application; some conventional structures are not specifically shown. The terms "first," "second," etc., used herein are merely different names for similar structures for ease of explanation and are not intended to limit this application. Not all pipes are labeled in the drawings, as the inlet and outlet pipes of each device are easily identified based on the fluid flow direction. The arrows in the drawings indicate the airflow direction. Figure 1 and Figure 2 Three vacuum units are set up, each including a steam-water separator, a vacuum chamber, a white water tank below the machine, a white water tank outside the machine, and corresponding valves and pipes. Since the arrangement of each vacuum unit is the same, only one vacuum unit is labeled in detail, while the other two vacuum units are only labeled with their main components, so as to make the attached diagrams more concise and easier to observe.

[0025] The paper machine wire section vacuum dewatering system includes a vacuum device, three steam-water separators, three under-machine white water tanks, and three external white water troughs. The outlet pipe of each steam-water separator is connected to the inlet pipe of the vacuum device. Each steam-water separator is equipped with a water leg, and the water legs of each steam-water separator are connected to the corresponding under-machine white water tank. The inlet pipe of each steam-water separator is connected to at least one vacuum box, and each vacuum box is equipped with a water leg, and the water legs of each vacuum box are connected to the corresponding external white water trough.

[0026] Furthermore, a first valve is installed on the inlet pipe of the vacuum device. This device can precisely control the gas flow rate and pressure entering the vacuum device. When the operating conditions of the paper machine change, such as paper type switching or speed adjustment, the working state of the vacuum system can be quickly adjusted by adjusting the opening of this valve to maintain a stable vacuum level within the system, thereby ensuring the consistency of the dewatering effect.

[0027] Furthermore, the outlet pipe of each vacuum chamber is connected to the inlet pipe of the corresponding steam-water separator, and each vacuum chamber's outlet pipe is equipped with a second valve. This configuration allows for precise control of the inlet flow rate of the steam-water separator based on its operating status and the pressure within the vacuum chamber.

[0028] Furthermore, each vacuum chamber's water leg is equipped with a third valve; each steam-water separator's water leg is equipped with a fourth valve. This setup provides a reliable control method for liquid water discharge. During system operation, the drainage speed and flow rate of the water legs can be flexibly adjusted according to different production needs and operating conditions. This effectively prevents water accumulation or backflow within the water legs, avoiding water hammer and vacuum waves caused by poor drainage, and ensuring the system's vacuum stability.

[0029] To improve automation, in practical applications, each valve is connected to a controller (e.g., a PLC controller).

[0030] Furthermore, all steam-water separators are of the same specification. This arrangement ensures a high degree of versatility and interchangeability in the production, installation, and maintenance of the system. It also helps to guarantee the stable performance of each steam-water separator, ensuring balanced operation of the entire dehydration system and improving its overall reliability and stability.

[0031] Furthermore, each steam-water separator includes a straight section and a conical section. The inlet pipe of each steam-water separator is connected to the side wall of the straight section; the outlet pipe of each steam-water separator is located at the top of the straight section; and the water leg of each steam-water separator is located at the bottom of the conical section. The connection of the inlet pipe of the steam-water separator to the side wall of the straight section allows the incoming water-water mixture to form a stable airflow distribution within the straight section, which is beneficial for the initial separation of steam and water. The outlet pipe is located at the top of the straight section, facilitating the smooth discharge of the separated gas. The water leg is located at the bottom of the conical section, utilizing the shape advantage of the conical section to allow the separated water to flow quickly and smoothly into the white water pool below the machine under the action of gravity.

[0032] Preferably, the inlet pipe diameter of each steam-water separator is 100-105 mm; the outlet pipe diameter of each steam-water separator is 100-105 mm; and the water leg diameter of each steam-water separator is 100-105 mm. Preferably, the height of the straight section of the steam-water separator is 395-400 mm; and the height of the conical section of the steam-water separator is 195-200 mm. Appropriate pipe diameters ensure smooth flow of gas and water, avoiding problems such as blockage due to insufficient pipe diameter or slow flow rate and poor separation effect due to excessive pipe diameter. The specific heights of the straight and conical sections provide sufficient residence time and separation space for steam and water within the separator, ensuring efficient steam-water separation under various operating conditions.

[0033] Furthermore, the inlet pipe of each steam-water separator is connected to three vacuum chambers (e.g., Figure 2 (As shown). This setup can fully utilize the processing capacity of the steam-water separator to achieve centralized processing of water-vapor mixtures extracted from multiple vacuum chambers.

[0034] In practical applications, the three sets of vacuum units are used for vacuum dewatering of the wire surface layer, core layer, and bottom layer, respectively. Considering the characteristics of the surface layer, core layer, and bottom layer in terms of pulp content, fiber distribution, and paper forming requirements, the three sets of vacuum units are independently controlled, providing precisely matched vacuum dewatering conditions for each layer. This ensures uniform and stable moisture removal throughout the entire forming process, reducing paper quality defects caused by uneven dewatering and significantly improving product quality and production efficiency.

[0035] To facilitate understanding, the working principle is briefly described below: (1) The vacuum device works, creating a negative pressure environment in the entire system, which creates the necessary vacuum conditions for steam-water separation and vacuum dehydration. (2) During operation, the top, core, and bottom layers of the paper machine wire section will generate a mixture of steam and gas containing a large amount of water. This mixture is drawn into the system through each vacuum box for steam-water separation. A portion of the water in the vacuum box is discharged into the white water tank outside the machine through the water leg of the vacuum box; the remaining steam-water mixture is transported to the corresponding steam-water separator. In this process, the second valve set on the outlet pipe of the vacuum box plays an important role. It can reasonably adjust the flow rate and velocity of the gas according to the working state of the steam-water separator and the pressure in the vacuum box, ensuring that the water-vapor mixture can enter the steam-water separator in a suitable state. (3) The steam-water mixture is separated in the steam-water separator. The liquid water enters the white water tank below the machine through the water leg, and the gas is discharged through the outlet pipe of the steam-water separator. (4) During the entire operation of the paper machine, dynamic adjustments can be made according to different operating conditions (such as changes in paper machine speed, pulp type, and different pulp-water mixing amounts in the wire section). When the machine speed increases or the pulp-water mixing amount increases, the power of the vacuum device is adjusted, and the opening of the first valve is adjusted in conjunction with the adjustment to maintain a stable vacuum. In addition, the second, third, and fourth valves will also be adjusted according to parameters such as pressure and liquid level in the steam-water separator and vacuum chamber to ensure smooth steam-water separation and drainage processes throughout the system.

[0036] As can be seen from the above analysis, the technical solution proposed by this utility model enables the entire dewatering process to form an efficient circulation system, ensuring that vacuum dewatering operation can still be carried out stably even when the paper machine speed is continuously increasing and the pulp-water mixing volume is significantly increased. This effectively avoids dewatering failures caused by insufficient local processing capacity and greatly improves the overall reliability and adaptability of the system.

[0037] It is understood that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of this utility model, and all such substitutions or changes should fall within the protection scope of this utility model.

Claims

1. A paper machine wire section vacuum dewatering system comprising a vacuum device, characterized by: The three steam-water separators, the three under-machine white water pools and the three out-of-machine white water tanks are further included; the outlet pipes of each steam-water separator are respectively connected to the inlet pipes of the vacuum device; each steam-water separator is respectively provided with a water leg, and the water legs of the steam-water separators are respectively connected to the corresponding under-machine white water pools; at least one vacuum tank is connected to the inlet pipe of each steam-water separator, and each vacuum tank is respectively provided with a water leg, and the water legs of the vacuum tanks are respectively connected to the corresponding out-of-machine white water tanks.

2. The paper machine wire section vacuum dewatering system of claim 1 wherein: The inlet pipe of the vacuum device is provided with a first valve.

3. The paper machine wire section vacuum dewatering system of claim 1 wherein: The outlet pipe of each vacuum tank is respectively connected to the inlet pipe of the corresponding steam-water separator, and the outlet pipe of each vacuum tank is provided with a second valve.

4. The paper machine wire section vacuum dewatering system of claim 1 wherein: The specifications of the steam-water separators are the same.

5. The paper machine wire section vacuum dewatering system of claim 4 wherein: Each steam-water separator includes a straight section and a tapered section, and the inlet pipe of each steam-water separator is connected to the side wall of the straight section; the outlet pipe of each steam-water separator is arranged at the top of the straight section; and the water leg of each steam-water separator is arranged at the bottom of the tapered section.

6. The paper machine wire section vacuum dewatering system of claim 5 wherein: The diameter of the inlet pipe of each steam-water separator is 100-105 mm; the diameter of the outlet pipe of each steam-water separator is 100-105 mm; and the diameter of the water leg of each steam-water separator is 100-105 mm.

7. The paper machine wire section vacuum dewatering system according to claim 5, characterized by: The inlet pipe of each steam-water separator is respectively connected to three vacuum tanks.

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