Evaporation effect tank system with high thermal efficiency

Abstract

The utility model provides an evaporation effect tank system with high heat efficiency, which comprises a low-pressure fresh steam tank group, a multi-effect secondary steam tank group and a surface cooling module which are connected in sequence, and a non-condensable gas outlet of the low-pressure fresh steam tank group is communicated with a steam inlet of the multi-effect secondary steam tank group. According to the utility model, the evaporation route of the evaporation tank is improved, a first evaporation process is set to be composed of a plurality of first-effect steam tanks and forced-effect steam tanks which are connected in parallel, and secondary steam, non-condensable gas and low-pressure steam which is not subjected to heat exchange generated in the first evaporation process are all led to a multi-effect secondary steam tank group to serve as heating sources. Due to the fact that the second-effect evaporation tank can be filled with sufficient heat, the heat of fresh steam can be fully utilized, the amount of fresh steam needed by the first evaporation procedure is further reduced, and the effect of saving energy is achieved. And meanwhile, a large amount of fresh steam which is not subjected to complete heat exchange is prevented from flowing to the surface cooling module through the non-condensable gas main pipe, so that the adverse effect on the cooling capacity of the surface cooling module is avoided.

Description

Technical Field

[0001] This utility model relates to a pulping wastewater treatment device, specifically an evaporator system with high thermal efficiency. Background Technology

[0002] Evaporation tanks are an important environmentally friendly process for treating pulping wastewater. The principle behind this process is to lower the boiling point of the wastewater using a vacuum environment, and then concentrate and increase the concentration of the black liquor using a low-temperature heat source. Evaporation equipment typically employs multi-effect evaporators connected in series, with the secondary steam from the previous effect serving as the heat source for the next effect. However, the evaporation process is affected by vacuum differences caused by surface cooling, leading to reduced evaporation efficiency, especially in the first effect where higher pressure results in increased steam consumption.

[0003] During the heating process within the steam tank, some non-condensable gases are generated. These non-condensable gases are piped into a common non-condensable gas header and then sent to a surface cooler for cooling. If too much non-condensable gas enters, it reduces the cooling capacity of the surface cooler, leading to a decrease in vacuum. In existing technologies, the first and second effects of the evaporation system use fresh, low-pressure steam for heating. This steam contains almost no non-condensable gases, but it also enters the surface cooler. This steam not only increases the load on the cooler but also leads to energy waste and reduced efficiency. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides an evaporator system with high thermal efficiency, including a low-pressure fresh steam tank group, a multi-effect secondary steam tank group, and a surface cooling module connected in sequence. The low-pressure fresh steam tank group is connected to a fresh low-pressure steam source through a first steam pipe. The steam outlet and non-condensable gas outlet of the low-pressure fresh steam tank group are respectively connected to the steam inlet of the multi-effect secondary steam tank group. The steam outlet and non-condensable gas outlet of the multi-effect secondary steam tank group are respectively connected to the surface cooling module through a second steam pipe and a non-condensable gas main pipe.

[0005] Furthermore, an odor removal furnace is connected to the rear side of the surface cooling module.

[0006] Furthermore, the low-pressure fresh steam tank group is composed of at least two sets of first-effect steam tanks or forced-effect steam tanks connected in parallel.

[0007] Furthermore, the multi-effect secondary steam tank group includes at least three groups of steam tanks, which are connected in series from the second-effect steam tank to the last-effect steam tank; the steam outlet of the steam tank located at the front of the multi-effect secondary steam tank group is connected to the steam outlet of the steam tank located at the rear through a third steam pipe, and the non-condensable gas outlet of each group of steam tanks in the multi-effect secondary steam tank group is connected to the non-condensable gas main pipe through a non-condensable gas branch pipe.

[0008] Furthermore, the number of steam tanks in the multi-effect secondary steam tank group is 3-8 groups.

[0009] Furthermore, each evaporator in the low-pressure fresh steam tank group is equipped with a perforated plate at its non-condensable gas outlet, and the perforation diameter of the perforated plate is 4-6 mm.

[0010] This invention provides a high-efficiency evaporator system, comprising a low-pressure fresh steam tank group, a multi-effect secondary steam tank group, and a surface cooling module connected in sequence. The non-condensable gas outlet of the low-pressure fresh steam tank group is connected to the steam inlet of the multi-effect secondary steam tank group. This invention improves the evaporation path of the evaporator by setting the first evaporation process as consisting of multiple parallel first-effect steam tanks and forced-effect steam tanks. The secondary steam, non-condensable gas, and low-pressure steam that has not undergone complete heat exchange generated in the first evaporation process are all directed to the multi-effect secondary steam tank group as a heating source. Since the second-effect evaporator can be filled with sufficient heat, the heat of the fresh steam can be fully utilized, thereby reducing the amount of fresh steam required for the first evaporation process and saving energy. It also avoids a large amount of incompletely heat-exchanged fresh steam flowing through the non-condensable gas main pipe to the surface cooling module, which would adversely affect the cooling capacity of the surface cooling module. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the planar structure of an evaporator system with high thermal efficiency according to this utility model.

[0012] Figure reference numerals: 1. First-effect evaporator; 2. Second-effect evaporator; 3. Surface cooler; 4. Odor removal furnace; 5. First steam pipe; 6. Second steam pipe; 7. Third steam pipe; 8. Non-condensable gas branch pipe; 9. Non-condensable gas main pipe; 10. Isolation valve; 11. Forced-effect evaporator. Detailed Implementation

[0013] like Figure 1 The illustrated high-efficiency evaporator system includes a low-pressure fresh steam tank group, a multi-effect secondary steam tank group, and a surface cooling module connected in sequence. The low-pressure fresh steam tank group is connected to a fresh low-pressure steam source via a first steam pipe 5, where it is heated by the steam provided by the fresh low-pressure steam source. The multi-effect secondary steam tank group is connected to the surface cooling module via a non-condensable gas main pipe 9 and a second steam pipe 6, respectively. An odor removal furnace 4 is connected to the rear of the surface cooling module. Specifically, the surface cooling module consists of two sets of parallel surface coolers 3, which cool the gas discharged from the multi-effect secondary steam tank group. The steam from the multi-effect secondary steam tank group after heating the black liquor is discharged through the second steam pipe 6 and cooled into condensate by the surface cooling module. The non-condensable gas generated during the heating process is transmitted through the non-condensable gas main pipe 9, cooled by the surface cooling module, and then transmitted to the odor removal furnace 4 for combustion.

[0014] The low-pressure fresh steam tank group is also equipped with a steam outlet and a non-condensable gas outlet for discharging steam and non-condensable gas. The steam outlet and non-condensable gas outlet of the low-pressure fresh steam tank group are respectively connected to the heating chamber of the multi-effect secondary steam tank group to transfer heating gas into the multi-effect secondary steam tank group.

[0015] Specifically, the low-pressure fresh steam tank group includes three sets of first-effect evaporators 1 and two sets of forced-effect evaporators 11, with the five sets of evaporators connected in parallel. Each set is connected to a fresh low-pressure steam source via a first steam pipe 5, using low-pressure steam to perform the first stage of heating on the black liquor in the new steam tank group. The fresh low-pressure steam source contains almost no non-condensable gases. The secondary steam generated by the low-pressure new steam tank heating the black liquor flows through the steam outlet to the heating chamber of the multi-effect secondary steam tank group, serving as the main heat source for heating the black liquor. The low-pressure steam that has not been fully heat-exchanged and the non-condensable gases generated during the heating process flow through the non-condensable gas outlet to the heating chamber of the multi-effect secondary steam tank group to supplement the heat input in the heating chamber.

[0016] The multi-effect secondary steam tank group comprises seven evaporators, numbered from the second-effect evaporator (2) to the eighth-effect evaporator. These seven evaporators are connected in series. The steam outlet of the preceding evaporator is connected to the steam inlet of the following evaporator via a third steam pipe (7). The preceding evaporator provides the heat needed to heat the black liquor. The steam outlet of the final-effect evaporator, the eighth-effect evaporator, is connected to the surface cooling module via a second steam pipe (6). The non-condensable gas outlets of the seven evaporators are connected to the main non-condensable gas pipe (8) via non-condensable gas branch pipes (8). The non-condensable gas collected in the entire multi-effect secondary steam tank group is then uniformly transmitted to the surface cooling module for cooling.

[0017] Furthermore, the non-condensable gas outlets of each evaporator in the low-pressure fresh steam tank group are equipped with perforated plates to change the flow rate and velocity of the non-condensable gas towards the second-effect evaporator 2. In conventional technology, the perforation diameter of the non-condensable gas perforated plate in the first-effect evaporator 1 is 25-27 mm, and the perforation diameter of the non-condensable gas perforated plate in the forced-effect evaporator 11 is 10-14 mm. However, in this embodiment, the perforation diameter of the non-condensable gas perforated plates in both the first-effect evaporator 1 and the forced-effect evaporator 11 is adjusted to 4-6 mm to reduce the flow rate of gas entering the second-effect evaporator 2. Gas that has not been fully heat-exchanged in the first-effect evaporator 1 can be fully heat-exchanged in the first-effect evaporator 1 and the second-effect evaporator 2, thereby improving the heating efficiency of the second-effect evaporator 2.

[0018] In this embodiment, the connection between the non-condensable gas outlet of the low-pressure new steam tank group and the steam inlet of the second-effect evaporator 2 can be achieved by setting up a separate connecting pipe, or by modifying the existing pipeline. In the prior art, the non-condensable gas outlet of the first-effect evaporator 1 is directly connected to the non-condensable gas main pipe. By installing an isolation valve 10 at this connection point and leading a new pipe from the isolation point to the steam inlet of the second-effect evaporator 2, the introduction of gas into the second-effect evaporator 2 can be realized.

[0019] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An evaporator system with high thermal efficiency, characterized in that: The system includes a low-pressure fresh steam tank group, a multi-effect secondary steam tank group, and a surface cooling module connected in sequence. The low-pressure fresh steam tank group is connected to a fresh low-pressure steam source through a first steam pipeline. The steam outlet and non-condensable gas outlet of the low-pressure fresh steam tank group are respectively connected to the steam inlet of the multi-effect secondary steam tank group. The steam outlet and non-condensable gas outlet of the multi-effect secondary steam tank group are respectively connected to the surface cooling module through a second steam pipeline and a non-condensable gas main pipe.

2. The evaporator system with high thermal efficiency as described in claim 1, characterized in that: The rear side of the surface cooling module is connected to an odor removal furnace.

3. The evaporator system with high thermal efficiency as described in claim 1, characterized in that: The low-pressure fresh steam tank group consists of at least two sets of first-effect steam tanks or forced-effect steam tanks connected in parallel.

4. The evaporator system with high thermal efficiency as described in claim 1, characterized in that: The multi-effect secondary steam tank group includes at least three steam tanks, which are connected in series from the second-effect steam tank to the last-effect steam tank. The steam outlet of the steam tank located at the front of the multi-effect secondary steam tank group is connected to the steam outlet of the steam tank located at the rear through a third steam pipe, and the non-condensable gas outlet of each steam tank in the multi-effect secondary steam tank group is connected to the non-condensable gas main pipe through a non-condensable gas branch pipe.

5. The evaporator system with high thermal efficiency as described in claim 4, characterized in that: The number of steam tanks in the multi-effect secondary steam tank group is 3-8 groups.

6. The evaporator system with high thermal efficiency as described in claim 3, characterized in that: The non-condensable gas outlet of each evaporator in the low-pressure fresh steam tank group is equipped with an orifice plate, and the orifice plate has a diameter of 4-6 mm.

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