Cold black liquor tank suitable for displacement cooking
By designing a cold black liquid tank with a simple structure, using an inner and outer groove structure with an inner and outer jacket and a special liquid tube design, the complexity of cold black liquid treatment and impurity deposition problems in the replacement cooking process are solved, and efficient black liquid isolation and energy-saving effects are achieved.
Patent Information
- Application Number
- CN202421796435.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-29
- Publication Date
- 2025-04-25
- Estimated Expiration
- 2034-07-29
AI Technical Summary
In the replacement cooking process, there are two major problems in the treatment of cold black liquid: one is that a complex structure of cold black liquid tank is required to prevent impurities from deposition, and the other is that direct pumping of cold black liquid to the washing filtrate tank may lead to impurities mixing and concentration reduction, increasing steam consumption.
A cold black liquid tank with a simple structure and a small area is designed, and an inner and outer groove structure with an inner and outer jacket is designed. The inner groove is used to store high-temperature black liquid, and the outer groove is used to store low-temperature black liquid. It also avoids impurities deposition through a special liquid tube design, eliminating the setting of the stirrer.
It realizes effective isolation of black liquids with different temperatures and alkali concentrations, improves process efficiency, saves energy, reduces insulation costs, and reduces the frequency of cleaning of the outer tank, simplifies the equipment structure.
Smart Images
Figure CN222798703U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of displacement cooking equipment, in particular to a cold black liquor tank suitable for displacement cooking process. Background Art
[0002] The core difference between the displacement cooking process and the traditional method is the introduction of a temperature-zoned tank system, which is specially used to store the black liquor replaced at different stages of the cooking process. This system, especially the warm black liquor tank and hot black liquor tank, is the iconic configuration of the displacement cooking process. They are responsible for storing high-temperature black liquor with a temperature of more than 100°C, ensuring the efficient operation of the process.
[0003] In current commercial practice, there are two main strategies for treating cold black liquor with a temperature below 100°C. The first is to store it in a cold black liquor tank with a relatively complex structure and equipped with a stirring device to prevent impurities from depositing; the second is to transport the cold black liquor to the alkali recovery section through a cold black liquor pump directly connected to the washing filtrate tank, but this method may cause mixing problems between cold black liquor and washing filtrate, which not only pollutes the washing filtrate, but also reduces the concentration of black liquor sent to subsequent treatment processes, thereby increasing steam consumption during evaporation.
[0004] In the delicate operation of the three-displacement cooking process, the warm charging (i.e. low-temperature cooking) stage is particularly important. The black liquor displaced in the initial stage has a temperature below 100°C, is rich in impurities such as fines and saponification, and has a low residual alkali content. This part of the black liquor is directly discharged into the cold black liquor tank. In the later stage, the displaced black liquor shows a higher residual alkali concentration and a temperature exceeding 100°C, so it needs to be safely stored in a pressurized warm black liquor tank. This part of the warm black liquor is not only partially reused in the warm charging process, but the remaining part will also be transferred to the cold black liquor tank for storage after cooling to below 100°C. At this time, part of the cooled black liquor is used for the cold charging process, and the remaining part is combined with the black liquor displaced in the initial stage of warm charging, and is uniformly sent to the alkali recovery evaporation section through a pumping and filtration system for further processing.
[0005] It can be seen that the cold black liquor tank plays a dual role in the process: it is both a temporary storage station for black liquor leading to the evaporation process and a supply source of black liquor required for the cold charging process. In view of the differences in temperature and alkali concentration of the black liquor replaced in the two stages before and after the warm charging, the strategy of storing them separately is particularly critical, which helps to optimize resource utilization and improve overall process efficiency. Utility Model Content
[0006] The utility model aims to provide a cold black liquor tank suitable for displacement cooking process, which has the characteristics of simple structure, easy manufacture and small footprint. The two parts of black liquor with different temperatures and alkali concentrations displaced before and after warm charging are stored separately to achieve better utilization effect. The high-temperature liquid is stored in the inner tank, which saves energy and reduces the insulation cost. The special liquid distribution pipe design of the outer tank effectively avoids the cleaning frequency of the outer tank and saves the setting of the agitator.
[0007] In order to achieve the above-mentioned invention object, the technical solution of the utility model is as follows:
[0008] A cold black liquor tank suitable for displacement cooking comprises an inner tank and an outer tank which are arranged inside and outside, the inner tank and the outer tank are both cylindrical structures with sealed bottoms, the top of the inner tank is lower than the top of the outer tank, the inner tank and the outer tank are both provided with a liquid inlet pipe and a liquid outlet pipe, the inner tank is connected to a black liquor cooler through the liquid inlet pipe, the inner tank is connected to a cooking pot through the liquid outlet pipe, the outer tank is connected to the cooking pot through the liquid inlet pipe, the outer tank is connected to a black liquor recovery system through the liquid outlet pipe, the liquid inlet pipe of the inner tank is connected to a liquid distribution port in the inner tank, and the liquid inlet pipe of the outer tank is connected to a liquid distribution pipe in the outer tank.
[0009] The liquid inlet pipe of the inner tank passes through the side wall of the outer tank and is horizontally inserted into the inner tank. The liquid inlet pipe of the inner tank is horizontally inserted to facilitate connection with a pump outside the cold black liquor tank.
[0010] The liquid distribution port is located in the middle of the inner tank or close to the inner wall of the inner tank; different positions are selected according to different pulp types.
[0011] The liquid dispensing port is a bell mouth, a 30-90° elbow or an oblique short connection.
[0012] The center height of the liquid distribution port is between 10% and 50% of the inner tank height.
[0013] The liquid distribution pipe is arranged around the inner groove in an annular or semi-annular structure. The distance between the liquid distribution pipe and the side wall of the inner groove and the side wall of the outer groove is equal. The height of the liquid distribution pipe is 0.6~1.5 meters from the bottom of the outer groove. Such a height can ensure a better flushing effect after connecting the nozzle.
[0014] The liquid distribution pipe is evenly distributed with an equal number of nozzles, which are arranged vertically downward. The nozzles are cut with an oblique cut of 15 to 75 degrees toward the outer tank liquid outlet pipe, which helps the black liquor discharged from the nozzles to flow in one direction, thereby preventing impurities in the black liquor from being deposited.
[0015] Beneficial effects of the utility model:
[0016] 1. The utility model has an inner tank liquid inlet pipe connected to a black liquor cooler, an inner tank liquid outlet pipe connected to a cooking pot, a cold black liquor tank outer tank liquid inlet pipe connected to a cooking pot, and an outer tank liquid outlet pipe connected to a recovery system. The inner tank is used to store the cooled black liquor from the warm black liquor tank. This part of the black liquor has a higher temperature and is used in the cooking cold charging process. The cold black liquor outer tank is used to store the warm charging reflux liquid from the cooking pot with a temperature less than 100°C. This part of the black liquor has a lower concentration and contains more impurities. It is sent to the alkali recovery section for subsequent recovery treatment after being filtered by the black liquor filter through the black liquor filter feed pump.
[0017] 2. The utility model has a simple structure, is easy to manufacture, and occupies a small area. At the same time, it realizes the effective isolation of two liquids with significant differences in temperature and residual alkali, ensuring the high efficiency and accuracy of the process. By storing the black liquor that needs to be cold-charged in the inner tank and keeping the black liquor in the inner tank warm through the black liquor in the outer tank, it saves energy and reduces the insulation cost.
[0018] 3. In the utility model, the design of the liquid distribution pipe with an oblique nozzle ensures that the discharged black liquor can flow uniformly and smoothly toward the liquid outlet, effectively preventing the deposition of impurities such as fine dust, thereby significantly reducing the frequency of cleaning the outer tank, reducing the maintenance burden, eliminating the need for the agitator, further simplifying the equipment structure, and reducing manufacturing costs and operating energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a schematic diagram of the cold black liquor tank structure of Example 1 of the utility model.
[0020] Figure 2 This is a schematic diagram of the cold black liquor tank structure of Example 2 of the utility model.
[0021] Among them, 1. inner tank; 2. outer tank; 3. liquid inlet pipe; 4. liquid outlet pipe; 5. liquid distribution pipe; 6. liquid distribution port. DETAILED DESCRIPTION
[0022] The present invention is further described in detail below in conjunction with the embodiments, but the implementation manner of the present invention is not limited thereto.
[0023] Example 1
[0024] like Figure 1As shown, the present embodiment provides a cold black liquor tank suitable for displacement cooking, comprising an inner tank 1 and an outer tank 2 which are arranged inside and outside, the inner tank 1 and the outer tank 2 are both cylindrical structures with sealed bottoms, the top of the inner tank 1 is lower than the top of the outer tank 2, the inner tank 1 and the outer tank 2 are both provided with a liquid inlet pipe 3 and a liquid outlet pipe 4, the inner tank 1 is connected to the black liquor cooler through the liquid inlet pipe 3, the inner tank 1 is connected to the cooking pot through the liquid outlet pipe 4, the outer tank 2 is connected to the cooking pot through the liquid inlet pipe 3, the outer tank 2 is connected to the black liquor recovery system through the liquid outlet pipe 4, the liquid inlet pipe 3 of the inner tank 1 is connected to a liquid distribution port 6 in the inner tank 1, and the liquid inlet pipe 3 of the outer tank 2 is connected to a liquid distribution pipe 5 in the outer tank 1.
[0025] The liquid inlet pipe 3 of the inner tank 1 passes through the side wall of the outer tank 2 and is horizontally inserted into the inner tank 1;
[0026] The liquid dispensing port 6 is disposed in the middle of the inner tank 1; the liquid dispensing port 6 is a bell mouth; the center height of the liquid dispensing port 6 is 20% of the height of the inner tank 1;
[0027] The liquid distribution pipe 5 is arranged around the inner tank 1 in an annular or semi-annular structure, and the distance between the liquid distribution pipe 5 and the side wall of the inner tank 1 and the side wall of the outer tank 2 is equal. The height of the liquid distribution pipe 5 is 1.2 meters from the bottom of the outer tank 2;
[0028] The liquid distribution pipe 5 is evenly distributed with an equal number of nozzles, which are arranged vertically downward and have a 60° oblique cut facing the liquid outlet pipe 3 of the outer tank 2 .
[0029] The cold black liquor tank in this embodiment is used to produce pine pulp;
[0030] In this embodiment, the liquid inlet pipe 3 of the inner tank 1 is connected to the black liquid pipeline at the black liquid side outlet of the black liquid cooler, the liquid outlet pipe 4 of the inner tank 1 is connected to the cold charging pump on the liquid inlet pipeline of the cooking pot, the liquid inlet pipe 3 of the cold black liquid outer tank 2 is connected to the warm charging reflux main pipe of the cooking pot, and the liquid outlet pipe 4 of the outer tank 2 is connected to the inlet of the black liquid filter feed pump of the recovery system. The inner tank 1 is used to store the black liquor after cooling from the black liquor cooler. This part of the black liquor has a higher temperature and is returned to the cooking cold charging process. The cold black liquor outer tank 2 is used to store the warm charging reflux liquid with a temperature of less than 100°C from the cooking pot. This part of the black liquor has a lower concentration and contains more impurities. It is sent to the alkali recovery section for subsequent recovery and treatment after being filtered by the black liquor filter through the black liquor filter feed pump.
[0031] Example 2
[0032] like Figure 2 As shown, this embodiment provides a cold black liquor tank suitable for displacement cooking. Compared with Example 1, the difference is that, in this embodiment, the liquid distribution port 6 is arranged near the inner wall of the inner tank 1; the liquid distribution port 6 is an elbow with a 45° cut downward; the liquid distribution pipe 5 is 1 meter high from the bottom of the tank; the nozzle has a 45° oblique cut facing the liquid outlet pipe; and the remaining structure is the same as that of Example 1.
[0033] This embodiment is used for pulping with bamboo or hardwood as raw materials on a smaller scale.
[0034] It is understood that the present invention is described by some embodiments, and those skilled in the art are aware that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.
Claims
1. A cold black liquor tank suitable for displacement cooking, characterized in that: The invention comprises an inner tank (1) and an outer tank (2) which are arranged inside and outside. The inner tank (1) and the outer tank (2) are both cylindrical structures and sealed at the bottom. The top of the inner tank (1) is lower than the top of the outer tank (2). The inner tank (1) and the outer tank (2) are both provided with a liquid inlet pipe (3) and a liquid outlet pipe (4). The inner tank (1) is connected to a black liquor cooler via the liquid inlet pipe (3). The inner tank (1) is connected to a cooking pot via the liquid outlet pipe (4). The outer tank (2) is connected to a black liquor recovery system via the liquid inlet pipe (3). The liquid inlet pipe (3) of the inner tank (1) is connected to a liquid distribution port in the inner tank (1). The liquid inlet pipe (3) of the outer tank (2) is connected to a liquid distribution pipe in the outer tank (2).
2. The cold black liquor tank suitable for displacement cooking according to claim 1, characterized in that: The liquid inlet pipe (3) of the inner tank (1) passes through the side wall of the outer tank (2) and is inserted into the inner tank (1).
3. The cold black liquor tank suitable for displacement cooking according to claim 2, characterized in that: The liquid dispensing port (6) is located in the middle of the inner tank (1) or close to the inner wall of the inner tank (1).
4. The cold black liquor tank suitable for displacement cooking according to claim 1, characterized in that: The liquid dispensing port (6) is a bell mouth, a 30-90° elbow, or an oblique short connection.
5. The cold black liquor tank suitable for displacement cooking according to claim 1, characterized in that: The center height of the liquid distribution port (6) is between 10% and 50% of the height of the inner tank (1).
6. The cold black liquor tank suitable for displacement cooking according to claim 1, characterized in that: The liquid distribution pipe (5) is arranged in an annular or semi-annular structure around the inner tank (1), the liquid distribution pipe (5) is equidistant from the side wall of the inner tank (1) and the side wall of the outer tank (2), and the height of the liquid distribution pipe (5) is 0.6 to 1.5 meters from the bottom of the tank.
7. The cold black liquor tank suitable for displacement cooking according to claim 1, characterized in that: The liquid distribution pipe (5) is evenly distributed with an equal number of nozzles, the nozzles are arranged vertically downward, and the nozzles are cut with an oblique cut of 15 to 75 degrees toward the liquid outlet pipe of the outer tank (2).