A high-efficiency waste heat recovery steam condensing device for the papermaking industry

Abstract

This utility model relates to the field of energy-saving technology in the papermaking industry, specifically to a high-efficiency waste heat recovery steam condensation device for the papermaking industry. It includes a drying cylinder with a steam inlet for heating the paper sheets and a condensate outlet, and a drying cylinder cover; a steam-water separator for rapidly separating the steam-water mixture discharged from the drying cylinder, with its inlet connected to the drying cylinder outlet and its vapor phase outlet connected to the drying cylinder cover; a temperature control valve that controls its opening and closing by sensing the temperature of the condensate; and a heat exchanger whose inlet is connected to the temperature control valve outlet, and which is connected to the drying cylinder cover via a warm air channel. This device removes the heat pump unit and flash tank of the original condensate system, and adopts a dedicated leveled condensate optimization system, resulting in higher water removal efficiency and reduced installation costs.

Description

Technical Field

[0001] This utility model relates to the field of energy-saving technology in the papermaking industry, specifically to a high-efficiency waste heat recovery steam condensation device for the papermaking industry. Background Technology

[0002] In the manufacturing process of household paper, the paper after pressing must be sent to the drying cylinder for heating and drying. Currently, this process is mostly carried out by steam heating, which consumes a huge amount of steam. After the steam heats the paper in the drying cylinder, it will be discharged from the drying cylinder in the form of residual steam and condensate.

[0003] In existing technologies, crescent-shaped paper machines are mostly used to produce tissue paper. Traditional paper machine drying cylinder steam systems use heat pumps and flash tanks to recover waste heat from condensate. For example, the utility model patent with announcement number CN217026494U entitled "A Heating System for a Crescent-Shaped Paper Machine" improves the paper machine's gas hood heating method to increase steam utilization, but it has drawbacks such as system complexity, low utilization rate of flash secondary steam, and high energy consumption. Existing technologies are difficult to accurately control condensate temperature and discharge efficiency, and there is an urgent need for a more energy-efficient structural alternative. Utility Model Content

[0004] Therefore, the purpose of this utility model is to provide a high-efficiency waste heat recovery steam condensation device for the papermaking industry, which can effectively solve the problems mentioned in the background art.

[0005] The present invention adopts the following technical solution: a high-efficiency waste heat recovery steam condensation device for the papermaking industry, comprising a drying cylinder: the drying cylinder is provided with a steam inlet for introducing steam to heat the paper sheets and a water outlet for condensate to flow out, and the drying cylinder is provided with a drying cylinder cover; Steam-water separator: used to quickly separate the steam-water mixture discharged from the drying cylinder. The inlet of the steam-water separator is connected to the outlet of the drying cylinder, and the steam phase outlet is connected to the drying cylinder cover. Temperature control valve: controls its opening and closing degree by sensing the temperature of the condensate; Heat exchanger: The inlet of the heat exchanger is connected to the outlet of the temperature control valve, and the heat exchanger is connected to the drying cylinder cover through the warm air channel.

[0006] The temperature control valve is connected to a temperature sensor and forms a dynamic temperature control module. The normal opening of the temperature control valve is 65%±10%, and the opening decreases as the steam flow in the drying cylinder increases.

[0007] The heat exchanger is also connected to a warm water tank, which is connected to the outlet of a condensate drain valve via a pipe, for storing condensate after heat exchange.

[0008] A fan is installed at the entrance of the warm air duct.

[0009] The temperature control valve has a bypass pipe connected in parallel at both ends, and a manual maintenance valve is installed on the bypass pipe.

[0010] The heat exchanger is a plate heat exchanger.

[0011] Compared with the prior art, the advantages of this utility model are as follows: This device removes the heat pump device and flash tank of the original condensate system. The steam-water separator directly returns the separated secondary steam to the drying cylinder, reducing the amount of fresh steam replenishment. The heat exchanger recovers and reuses the heat, reducing energy consumption and operating costs. The temperature control valve regulates the condensate discharge temperature, maintaining the optimal condensate thickness in the drying cylinder. A dedicated condensate discharge valve replaces the original steam trap, ensuring continuous condensate discharge. After the technical modification, the steam consumption per ton of paper is reduced by more than 10%, the steam pressure of the drying cylinder is reduced by more than 150 kPa, and the condensate discharge temperature is reduced by at least 20°C. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the installation of the present invention; Figure 2 This is a flowchart illustrating Embodiment 1 of the present utility model; Figure 3 This is a flowchart illustrating Embodiment 2 of the present invention.

[0013] In the diagram: 1-Drying cylinder; 11-Drying cylinder cover; 2-Steam-water separator; 21-Gas passage; 3-Bypass pipe; 31-Manual maintenance valve; 4-Temperature control valve; 5-Heat exchanger; 51-Condensate drain valve; 52-Heat air passage; 6-Warm water tank; 7-Steam source. Detailed Implementation

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0015] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0016] Example 1: Please see Figure 1-2As shown, a high-efficiency waste heat recovery steam condensation device for the papermaking industry includes: a drying cylinder 1: the drying cylinder 1 is provided with a steam inlet for heating the paper sheets and a water outlet for condensate to flow out; a steam-water separator 2: used to quickly separate the steam-water mixture discharged from the drying cylinder 1, the inlet of the steam-water separator 2 is connected to the water outlet of the drying cylinder 1, and the vapor phase outlet end is connected to the steam inlet of the drying cylinder 1; a temperature control valve 4 is connected to the liquid phase outlet end of the steam-water separator 2, and the temperature control valve 4 is a control unit for the flow rate and temperature of condensate; a heat exchanger 5: the water inlet of the heat exchanger 5 is connected to the water outlet of the flow control valve 3; a condensate drain valve 51: placed at the water outlet of the heat exchanger 5; the warm air channel 52 of the heat exchanger 5 supplies air to the drying cylinder 1; and a warm water tank 6, connected to the water outlet of the condensate drain valve 51 through a pipe, used to store the low-temperature condensate after heat exchange.

[0017] This design eliminates the heat pump and flash tank of the original condensate system, and adopts a steam-water separator 2 with higher water removal efficiency and smaller size. The steam-water separator 2 utilizes the density difference of the medium to quickly separate the steam-water mixture discharged from the drying cylinder 1. A large amount of water-containing steam is passed into the steam-water separator 2, where it moves downwards in a centrifugal, inclined motion. The moisture entrained in the steam or compressed air is separated due to the reduced velocity, thus reducing the water content in the steam or compressed air. The separated liquid is discharged through a separately equipped steam trap, while dry, clean steam is discharged from the steam-water separator outlet. The steam-water separator ensures the dryness of the steam or air used by the steam-consuming equipment, improving the operating efficiency of the steam-consuming equipment and extending its service life. The heat exchanger 5 is a plate heat exchanger.

[0018] The vapor phase channel 21 of the steam-water separator 2 directly sends the separated uncondensed steam (secondary steam) back to the steam inlet of the drying cylinder 1 for recycling. This step avoids the complex secondary steam pressurization (heat pump) process of the traditional flash tank system, reducing energy loss and equipment complexity.

[0019] Temperature control valve 4 is connected to a temperature sensor and forms a dynamic temperature control module. Temperature control valve 4 senses and controls the temperature of the condensate discharged from steam-water separator 2 within the range of 85℃±5℃.

[0020] The normal opening degree of the temperature control valve 4 at the liquid phase outlet of the steam-water separator 2 is 65% ± 10%, and the opening degree decreases as the steam flow in the drying cylinder 1 increases.

[0021] The drying cylinder 1 is covered by a drying cylinder cover 11, and the air outlet of the warm air passage 52 of the heat exchanger 5 is connected to the warm air of the drying cylinder cover 11 through a pipe. A fan is installed at the inlet of the warm air passage 52.

[0022] The drain valve at the end of the heat exchanger 5 of the heating system was removed and replaced with a dedicated straight-through condensate drain valve 51 to ensure continuous condensate drainage.

[0023] A bypass pipe 3 is connected in parallel to both ends of the temperature control valve 4, and a manual maintenance valve 31 is installed on the bypass pipe 3 for emergency drainage and system maintenance in case of equipment failure.

[0024] The above-mentioned high-efficiency waste heat recovery steam condensation device for the papermaking industry includes the following steps: The steam inlet of the drying cylinder 1 is connected to a steam source 7 for generating fresh steam. After being introduced into the drying cylinder 1, the steam heats and dries the pressed wet paper sheets. The high-temperature steam-water mixture discharged after the high-temperature heat exchange in the drying cylinder 1 flows through the steam-water separator 2 to achieve rapid steam-water separation. The separated vapor phase is sent back to the drying cylinder 1 through the steam channel 21, and the liquid phase flows through the temperature control valve 4 and then through the heat exchanger 5. The condensate after heat exchange is discharged to the warm water tank 6 through the condensate discharge valve 51. The waste heat is fed into the warm air system of the drying cylinder cover 11 on the drying cylinder 1 through the warm air channel 52 for recovery and utilization.

[0025] Steam-water separation and direct internal steam circulation: At the outlet of the drying cylinder, the high-temperature condensate is first separated into steam and liquid by a steam-water separator. The separated secondary steam is directly fed back to the drying cylinder as a supplementary heat source. This process constitutes the first level of "leveling" balance in the system: it reduces the drying cylinder's demand for external fresh steam and, through the pressure difference and flow of steam, forms a dynamic, self-balancing thermodynamic cycle within the system.

[0026] Cascade recovery of condensate waste heat: After steam-water separation, the high-temperature liquid condensate flows into a heat exchanger for a second heat exchange. The heat exchanger recovers and reuses the residual sensible heat in the condensate (e.g., for heating process water or air), thereby further reducing the overall energy consumption and operating costs of the system. The condensate temperature decreases after flowing through the heat exchanger.

[0027] Precise control of liquid level and thickness: The temperature control valve indirectly and precisely maintains the optimal condensate thickness inside the drying cylinder by regulating the discharge temperature of the condensate. Maintaining this appropriate condensate thickness is crucial for ensuring the normal operation of the system: it ensures that the temperature control valve is at the appropriate opening, allowing for smooth and continuous discharge of condensate while preventing ineffective steam escape, thereby maintaining normal steam flow rate and stable heating efficiency within the drying cylinder. This method of stabilizing the liquid level thickness by controlling temperature constitutes the core "leveling" optimization of the system.

[0028] Example 2: Please see Figure 3The following describes the operation method of a high-efficiency waste heat recovery steam condensation device for the papermaking industry, comprising the following steps: The steam inlet of the drying cylinder 1 is connected to a steam source 7 for generating fresh steam. After being introduced into the drying cylinder 1, the steam heats and dries the pressed wet paper sheets. The high-temperature steam-water mixture discharged from the drying cylinder 1 after high-temperature heat exchange flows through the steam-water separator 2 to achieve rapid steam-water separation. The separated vapor phase is sent back to the drying cylinder 1 through the steam channel 21, and the liquid phase flows through the temperature control valve 4 and then through the heat exchanger 5. The condensate after heat exchange is sent to the steam source 7 for circulating heating through the condensate discharge valve 51. The waste heat is fed into the warm air system of the drying cylinder cover 11 on the drying cylinder 1 through the warm air channel 52 for recovery and utilization.

[0029] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A high efficiency waste heat recovery steam condensing device for the paper industry, characterized by: include, Drying cylinder (1): The drying cylinder (1) is provided with a steam inlet (12) for introducing steam to heat the paper and a water outlet for condensate to flow out. The drying cylinder (1) is provided with a drying cylinder cover (11). Steam-water separator (2): used to quickly separate the steam-water mixture discharged from the drying cylinder (1). The inlet of the steam-water separator (2) is connected to the outlet of the drying cylinder (1), and the steam phase outlet end is connected to the drying cylinder cover (11). Temperature control valve (4): controls its opening degree by sensing the temperature of the condensate; Heat exchanger (5): The inlet of the heat exchanger (5) is connected to the outlet of the temperature control valve (4), and the heat exchanger (5) is connected to the drying cylinder cover (11) through the warm air channel (52).

2. The high-efficiency waste heat recovery steam condensation device for the papermaking industry according to claim 1, characterized in that: The temperature control valve (4) is connected to a temperature sensor and forms a dynamic temperature control module. The normal opening degree of the temperature control valve (4) is 65%±10%, and the opening degree decreases as the steam flow in the drying cylinder (1) increases.

3. A high efficiency waste heat recovery steam condensing device for paper industry as claimed in claim 1 wherein: The heat exchanger (5) is also connected to a warm water tank (6), which is connected to the outlet of the condensate drain valve (51) via a pipe and is used to store the condensate after heat exchange.

4. A high efficiency waste heat recovery steam condensing device for paper industry as claimed in claim 1 wherein: A fan is installed at the entrance of the warm air duct (52).

5. A high-efficiency waste heat recovery steam condensation device for the papermaking industry according to claim 1, characterized in that: The temperature control valve (4) has a bypass pipe (3) connected in parallel at both ends, and a manual maintenance valve (31) is installed on the bypass pipe (3).

6. A high-efficiency waste heat recovery steam condensation device for the papermaking industry according to claim 1, characterized in that: The heat exchanger (5) is a plate heat exchanger.

Images