A system for treating mother liquor in a sodium-process bleaching powder concentrate plant
By designing a mother liquor treatment system for a sodium-based bleaching powder production unit, a closed-loop system was formed using a preheater, evaporator, thickener, and centrifuge. This solved the problem of mother liquor accumulation, enabled the recovery of wet salt and the thermal energy recovery of water, and improved production economy and long-cycle operation capability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SINOPEC NANJING ENG & CONSTR
- Filing Date
- 2025-04-15
- Publication Date
- 2026-05-29
AI Technical Summary
The accumulation of mother liquor in the sodium bleaching powder refining process increases the load on the production unit, and the discharge and treatment consume water resources and generate additional costs, affecting the economic efficiency of production and long-term operation.
A system for treating mother liquor in a sodium-based bleaching powder production apparatus was designed, comprising a preheater, an evaporator, a thickener, and a centrifuge, which are connected by pipelines to form a closed-loop system to achieve internal treatment and resource recovery of the mother liquor, including the recovery of wet salt and the recovery of thermal energy from water.
The system achieves effective treatment of mother liquor within the unit, recovers wet salt as a product, and utilizes steam to recover water as a heat source, thereby improving the economics of production and the long-term operation capability of the unit.
Smart Images
Figure CN224299043U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of engineering design and production operation of sodium bleaching powder production equipment, and relates to a system for treating mother liquor in a sodium bleaching powder production equipment. Background Technology
[0002] The sodium process for bleaching powder production has gradually replaced the calcium process as the mainstream process due to its advantages such as high equipment flexibility, fewer equipment units, smaller footprint, and less by-products. In the sodium process, chlorine gas is passed into a basic salt slurry prepared from alkaline solution and hydrated lime to induce a chlorination reaction, yielding calcium hypochlorite. The reaction formula is as follows:
[0003] Ca(OH)2+2NaOH→Ca(ClO)2+2NaCl+2H2O
[0004] This process generates a large amount of salt-containing mother liquor during production. The mother liquor contains reaction byproducts NaCl and small amounts of Ca(OH)₂ and Ca(ClO)₂. The accumulation of large amounts of mother liquor increases the load on the production unit and affects the reaction process. Currently, the main method is to collect and discharge the mother liquor. Discharging the mother liquor not only consumes a large amount of production water, but also incurs additional costs for wastewater treatment.
[0005] Effective treatment of mother liquor is crucial for the economic efficiency and long-term operation of bleaching powder production equipment. Utility Model Content
[0006] The purpose of this invention is to provide a system for treating mother liquor in a sodium-based bleaching powder production apparatus, addressing the aforementioned technical limitations.
[0007] The objective of this utility model can be achieved through the following technical solutions:
[0008] A system for treating mother liquor in a sodium-based bleaching powder production apparatus includes a preheater, an evaporator, a thickener, and a centrifuge. The output pipe of the mother liquor from a single centrifugation is connected to the preheater, which is connected to the bottom of the evaporator. The output end of the evaporator in the middle is connected to the centrifuge via the thickener.
[0009] In the above system, the output ends of the preheater and evaporator are secondary steam pipes.
[0010] In the above system, the output end at the top of the thickener and the liquid output end at the bottom of the centrifuge are both connected to the filtrate circulation pipeline.
[0011] In the above system, the filtrate circulation pipeline is connected to the secondary reaction system of the sodium bleaching powder process.
[0012] In the above system, the solid output end at the bottom of the centrifuge is loose salt.
[0013] A method for treating mother liquor in a sodium-based bleaching powder production apparatus, wherein the primary mother liquor pipeline is connected to a preheater. The preheater output is connected to the evaporator input via a preheated mother liquor pipeline, and the other output is connected to a secondary condensate pipeline. The lower output of the evaporator is connected to a thickener via a saturated salt solution pipeline, the upper output is connected to the preheater via a secondary steam pipeline, and the bottom is connected to a steam pipeline and a condensate pipeline. The lower output of the thickener is connected to a centrifuge via a thickening salt solution pipeline, and the upper output is connected to a filtrate recycling pipeline via a supernatant pipeline. One output of the centrifuge is connected to a wet salt short-tube slurry product delivery device, and the other output is connected to a filtrate recycling pipeline to return the filtrate to the production unit.
[0014] The beneficial effects of this utility model are:
[0015] (1) The system can process the mother liquor once in the bleaching powder unit without sending it out for processing. (2) The system can recover the wet salt in the mother liquor for sale as a product or further process it into refined salt for sale. (3) The system recovers water in the mother liquor in the form of steam, which can be used as a heat source to provide heat for the drying process of bleaching powder products, and its condensate is recycled as production water. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the traditional sodium bleaching powder process.
[0017] Figure 2 This is a flowchart illustrating the present invention.
[0018] Figure 3 This is a schematic diagram of the structure of this utility model.
[0019] In the diagram, 1. Primary mother liquor inlet pipe, 2. Heated mother liquor pipe, 3. Supersaturated salt solution pipe, 4. Thickening salt solution pipe, 5. Supernatant pipe, 6. Moisture-dissipating salt pipe section, 7. Filtrate circulation pipe, 8. Secondary steam pipe, 9. Secondary condensate pipe, 10. Preheater, 11. Evaporator, 12. Thickener, 13. Centrifuge, 14. Steam pipe, 15. Condensate pipe. Detailed Implementation
[0020] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto:
[0021] like Figures 2-3A system for treating mother liquor in a sodium bleaching powder production apparatus includes a preheater 10, an evaporator 11, a thickener 12, and a centrifuge 13. The output pipe of the mother liquor from the first centrifugation is connected to the preheater 10. The preheater 10 is connected to the bottom of the evaporator 11. The output end of the evaporator 11 in the middle is connected to the centrifuge 13 via the thickener 12. The output ends of the preheater 10 and evaporator 11 are secondary steam pipes 8. The output end at the top of the thickener 12 and the liquid output end at the bottom of the centrifuge 13 are both connected to a filtrate circulation pipe 7. The filtrate circulation pipe 7 is connected to the secondary reaction system of the sodium bleaching powder process. The solid output end at the bottom of the centrifuge 13 is loose wet salt.
[0022] The more specific process is as follows:
[0023] The primary mother liquor pipeline 1 is connected to the preheater 10. The output end of the preheater 10 is connected to the input end of the evaporator 11 via the preheated mother liquor pipeline 2, and the other output end is connected to the secondary condensate pipeline. The lower output end of the evaporator 11 is connected to the thickener 12 via the saturated salt solution pipeline 3, the upper output end is connected to the preheater 10 via the secondary steam pipeline 8, and the bottom is connected to the steam pipeline 14 and the condensate pipeline 15. The lower output end of the thickener 12 is connected to the centrifuge 13 via the thickening salt solution pipeline 4, and the upper output end is connected to the filtrate reuse pipeline 7 via the supernatant pipeline 5. One output end of the centrifuge 13 is connected to the wet salt short tube slurry product delivery device, and the other output end is connected to the filtrate reuse pipeline 7 to return the filtrate to the production unit.
[0024] Instructions for running the example:
[0025] The primary mother liquor from the reaction unit is at a temperature of 25°C and a pressure of atmospheric pressure, containing 21.5 wt% NaCl, 1.8 wt% Ca(OH)₂, and 3.4 wt% Ca(ClO)₂ (data for secondary mother liquor; the primary mother liquor contains more). The mother liquor enters the preheater 10 through the primary mother liquor pipeline 1 and is heated to 60°C. The preheated mother liquor is then sent to the forced circulation evaporator 11, where it is evaporated and concentrated into a supersaturated salt solution. It then enters the thickener 12 through the supersaturated salt solution pipeline 3 and is cooled to below 5°C. The supernatant from the thickener overflows into the filtrate circulation pipeline 7. The remaining thickened salt solution contains a large amount of crystals and is sent to a centrifuge for centrifugal separation to obtain a wet salt product with a water content of 15%. The filtrate is sent to the secondary reactor through the filtrate circulation pipeline 7, where the uncrystallized Ca(OH)₂ and Ca(ClO)₂ are returned to the production unit.
Claims
1. A system for treating mother liquor in a sodium-based bleaching powder production apparatus, characterized in that, The system includes a preheater (10), an evaporator (11), a thickener (12), and a centrifuge (13); the output pipe of the mother liquor from the first centrifugation is connected to the preheater (10), the preheater (10) is connected to the bottom of the evaporator (11), and the output end of the middle part of the evaporator (11) is connected to the centrifuge (13) through the thickener (12).
2. The system for treating mother liquor in the sodium bleaching powder production apparatus according to claim 1, characterized in that, The output ends of the preheater (10) and evaporator (11) are secondary steam pipes (8).
3. The system for treating mother liquor in the sodium bleaching powder production apparatus according to claim 1, characterized in that, The output end at the top of the thickener (12) and the liquid output end at the bottom of the centrifuge (13) are both connected to the filtrate circulation pipe (7).
4. The system for treating mother liquor in the sodium bleaching powder production apparatus according to claim 1, characterized in that, The filtrate circulation pipeline (7) is connected to the secondary reaction system of the sodium bleaching powder process.
5. The system for treating mother liquor in the sodium bleaching powder production apparatus according to claim 1, characterized in that, The solid output end at the bottom of the centrifuge (13) is a moisture-absorbing salt.