A high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production, replacing wet decomposition towers.

Abstract

This invention discloses a high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production, replacing a wet decomposition tower. The system includes a buffer tank for receiving saline wastewater from a raw material tank; a preheater for receiving the saline wastewater from the buffer tank and initially raising its temperature; a heating chamber for receiving the preheated saline wastewater from the preheater; an evaporation chamber for flash evaporation of the heated brine to obtain a concentrated solution; a carbonization tower for receiving the concentrated solution from the evaporation chamber and CO2 gas supplied from another inlet for a carbonization reaction; an online monitoring module for real-time monitoring of scaling trends in the evaporation chamber; and a high-frequency electromagnetic pulse device for periodically flushing the evaporation chamber with high-frequency pulse waves, thereby periodically disturbing the solution to inhibit crystal growth. This high-efficiency decomposition and evaporation system offers advantages such as low energy consumption, environmental friendliness, small footprint, and high safety and reliability. It provides an alternative to the wet decomposition tower necessary in sodium bicarbonate production, reduces evaporation water volume, and offers a new technological approach.

Description

Technical Field

[0001] This utility model relates to the field of chemical wastewater treatment technology, and in particular to a high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production that can replace a wet decomposition tower. Background Technology

[0002] Sodium bicarbonate is an important inorganic chemical product widely used in the food industry, pharmaceutical field, metallurgy, metal heat treatment, glass, feed, rubber, dyes, detergents, personal care products, and dry powder fire extinguishing agents. Traditionally, sodium bicarbonate is produced primarily using the wet decomposition method, with the core equipment relying on the wet decomposition tower. Currently, the decomposition system of the wet decomposition tower mostly uses multi-effect evaporators or thermal vapor recompression (TVR). However, current wet decomposition tower systems often suffer from the following drawbacks:

[0003] 1. High steam energy consumption: The steam consumption of multi-effect evaporation reaches 0.4-0.6 t / t water, and the energy cost accounts for more than 40%.

[0004] 2. Severe scaling: The mother liquor of silicon-containing wastewater contains NaHCO3, Na2CO3, and impurity ions (Ca²⁺, Al⁻). 3+ Mg²⁺ tends to form scale on heat exchange surfaces and pipes, leading to a decrease in heat transfer coefficient and requiring frequent shutdowns for cleaning.

[0005] 3. Low decomposition efficiency of sodium bicarbonate: The additional condensate produced by the wet decomposition tower leads to a low concentration of sodium bicarbonate, which increases the evaporation energy consumption and the difficulty of sodium bicarbonate decomposition. For example, patent CN118718890A mentions that the total decomposition rate of sodium bicarbonate by traditional multi-effect evaporation is only 85.4%. Although the patent improves the total decomposition rate of sodium bicarbonate by adding a catalyst as feed to the wet decomposition tower, it also significantly increases the cost of the chemicals.

[0006] 4. Low secondary steam utilization rate: The ejector ratio of the TVR system is limited (≤1:1), making it impossible to efficiently recover low-grade heat energy.

[0007] Therefore, in order to ensure the effectiveness and economy of recovering sodium bicarbonate from wastewater, there is an urgent need for an MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production that can replace wet decomposition towers. Utility Model Content

[0008] The purpose of this invention is to provide a high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production that replaces the wet decomposition tower. The system further decomposes and evaporates sodium bicarbonate using a combined MVR decomposition and evaporation system for saline wastewater, concentrating the resulting brine to a certain concentration with a specific ratio of sodium carbonate to sodium bicarbonate before it enters a carbonation tower to produce sodium bicarbonate. This decomposition and evaporation system enables efficient utilization of secondary steam, overcoming problems such as high energy consumption, high cost, and energy waste in existing technologies. Furthermore, this high-efficiency decomposition and evaporation system has advantages such as low energy consumption, environmental friendliness, small footprint, and safety and reliability, providing a new technical path for the efficient decomposition and evaporation of sodium bicarbonate, thus solving the problems mentioned in the background art.

[0009] To achieve the above objectives, this utility model provides the following technical solution:

[0010] A high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production, replacing a wet decomposition tower, includes:

[0011] Buffer tanks are used to receive saline wastewater (a mixture of sodium carbonate and sodium bicarbonate, with sodium salt concentrations of 70–120 g / L) from raw material tanks.

[0012] The preheater is used to preheat the saline wastewater in the receiving buffer tank.

[0013] The heating chamber receives preheated saline wastewater from the preheater at 70-75°C, reducing the evaporation load. It uses steam to heat the wastewater (indirectly) and raise its temperature, and performs wet decomposition of sodium bicarbonate. The condensate from the heating and decomposition is transported to a condensate tank for gas-liquid separation, while the liquid enters the preheater to heat the remaining brine. Additionally, the steam in the heating chamber releases heat and becomes condensate, which, along with non-condensable gases, is discharged to the condensate tank. The non-condensable gases undergo simple treatment to recover CO2.

[0014] The steam compressor uses a slight negative pressure to compress and heat the secondary steam generated in the evaporation chamber to the set temperature. The heated steam is then introduced into the heater; if the steam supply is insufficient, it is supplemented with fresh steam.

[0015] The evaporation chamber receives the heated brine and some liquid water, which are then flash-evaporated into steam, concentrating the brine. The secondary steam flash-evaporated in the evaporation chamber is compressed and heated by a steam compressor and then returned to the heating chamber. After being concentrated to a certain concentration with a specific ratio of sodium carbonate to sodium bicarbonate in the evaporation chamber, the brine is pumped into the carbonation tower. The evaporation chamber uses a titanium threaded tube with a spiral flow channel structure on the inner wall, achieving a heat transfer coefficient K≥2000 W / (m²·K).

[0016] The steam compressor is a mechanical steam recompressor with an isentropic efficiency of ≥80%. It compresses secondary steam from 80-85℃ to 105-110℃ for reuse.

[0017] The carbonization tower is used to receive the concentrated solution and CO2 gas from the evaporation chamber for a carbonization reaction. The liquid after the carbonization reaction enters the next production process.

[0018] The various devices are connected by corrosion-resistant pipes.

[0019] The online monitoring module is used to monitor the real-time scaling trend in the evaporation chamber and send signals to the high-frequency electromagnetic pulse device.

[0020] A high-frequency electromagnetic pulse device periodically flushes the evaporation chamber with high-frequency pulse waves, thereby periodically disturbing the solution to inhibit crystal nucleus growth.

[0021] A further embodiment of this invention is that a water pump A is connected between the raw material tank and the buffer tank, a feed pump is connected between the buffer tank and the preheater, and a discharge pump is connected between the evaporation chamber and the carbonization tower.

[0022] A further embodiment of this invention is that the condensate after steam exchange in the heating chamber enters a condensate tank, and a water pump B is connected between the condensate tank and the preheater.

[0023] A further aspect of this invention is that the preheater is a plate heat exchanger, and the condensate in the preheater is discharged through a drain pipe.

[0024] A further aspect of this invention is that the saline wastewater in the evaporation chamber is first preheated by the condensate transported by water pump B before entering the heating chamber for heating.

[0025] A further aspect of this invention is that the steam in the evaporation chamber is transported to the heating chamber as a heating source carrier for the heating chamber.

[0026] A further aspect of this invention is that the pulse frequency of the high-frequency electromagnetic pulse device is 20–50 kHz, and the power density is 5–10 W / cm². The discharge head of the high-frequency electromagnetic pulse device is connected to the outlet of the evaporation chamber. The high-frequency electromagnetic pulse device uses a high-voltage transformer and a high-voltage rectifier silicon stack to generate a high-voltage DC charging current. The high-frequency electromagnetic pulse device generates an ignition pulse, causing the upper and lower electrodes of the ignition switch to break down and discharge. The discharge head of the cable discharges on the scaled pipe wall in the water, converting electrodynamic force into hydraulic force, so that the scale is broken and detached under the action of the shock wave, thereby achieving the purpose of scale removal.

[0027] A further aspect of this invention is that the online monitoring module includes a conductivity sensor and a differential pressure transmitter connected to the evaporation chamber. The conductivity sensor and differential pressure transmitter monitor the scaling trend in real time and are electrically connected to a PLC controller. The PLC controller is electrically connected to a high-frequency electromagnetic pulse device and can trigger the cleaning program of the high-frequency electromagnetic pulse device.

[0028] The specific process flow of this utility model is as follows: saline wastewater → buffer tank → preheater → heating chamber → evaporation chamber → saline concentrate → carbonization tower → sodium bicarbonate crystals.

[0029] The beneficial effects of this utility model are:

[0030] This utility model presents an MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production that replaces wet decomposition towers. It only requires a small amount of steam during the initial start-up and does not require other energy sources after normal operation. It only needs to provide sufficient electrical energy to ensure normal evaporation.

[0031] This invention relates to an MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production that replaces wet decomposition towers. It includes a heater and a secondary steam condenser, so no additional condenser is required, and no cooling cycle is needed.

[0032] This invention provides a high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production that replaces wet decomposition towers. It has low dependence on manual labor and requires fewer supporting public works projects.

[0033] This invention relates to an MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production that replaces wet decomposition towers. The addition of scale inhibitors and high-frequency pulse cleaning can effectively suppress the formation of hard scale and reduce the frequency of downtime for cleaning.

[0034] This invention provides a high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production that replaces wet decomposition towers. It is safe and reliable, and the entire system can be configured for control. It can be automated and has process compatibility. It can adapt to fluctuations in mother liquor composition and can be extended to other salt (such as sodium chloride and sodium sulfate) evaporation and concentration scenarios. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of this utility model.

[0036] In the diagram: 1-Buffer tank, 2-Preheater, 3-Heating chamber, 4-Evaporator, 5-Carbonization tower, 6-Online monitoring module, 7-High frequency electromagnetic pulse device, 8-Water pump A, 9-Feed pump, 10-Discharge pump, 11-Water pump B, 12-Mechanical steam recompressor, 13-Condensate tank. Detailed Implementation

[0037] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0038] Example 1: To test the energy-saving effect of a high-efficiency baking soda decomposition and evaporation system integrating MVR technology, such as... Figure 1 As shown,

[0039] ① Raw material source: High-salinity wastewater (sodium salt 70-120g / L, pH 9.2, Ca²⁺, Mg²⁺) + 200ppm).

[0040] ② The MVR evaporation and concentration process is as follows: High-salt wastewater is fed into preheater 2 by feed pump 9. After heat exchange and recovery of latent heat in the condensate by preheater 2, the preheated saline wastewater enters heating chamber 3. After being heated in heating chamber 3, the saline wastewater enters evaporation chamber 4 and evaporates at 85℃. The secondary steam generated in evaporation chamber 4 is compressed by steam compressor 12 at a speed of 4800 rpm and then enters heating chamber 3 for recycling. When the evaporation chamber 4 concentrates to a certain concentration and the sodium carbonate and sodium bicarbonate reach a certain ratio of brine, it is introduced into carbonization tower 5 by discharge pump 12 to carry out carbonization reaction with carbon dioxide. The steam in heating chamber 3 releases heat and becomes condensate, which flows out from the bottom of heating chamber 3 and is discharged to condensate tank 13 along with non-condensable gases. Then, it is sent to preheater 2 by water pump B11 to preheat the saline wastewater. The non-condensable gases are treated simply to recover CO2. 2。

[0041] ③ Test results show that the evaporation intensity of the MVR evaporation wastewater mother liquor is 38 kg / (m³). 2. h); Specific energy consumption: 0.09t standard coal / t water (energy consumption is about 30% of the energy consumption of multi-effect steam generator); Continuous operating time: 600h (scale layer thickness ≤0.08mm).

[0042] ④ According to relevant literature, for a triple-effect evaporator with the same processing capacity, with an electricity price of 0.5 yuan / kWh and without considering the benefits of condensate, the cost per ton of water treated is 64.45 yuan. Assuming an annual operating time of 7200 hours, the operating cost of this novel MVR high-efficiency decomposition and evaporation system with a processing capacity of 1 t / h is approximately 198,000 yuan less than that of a triple-effect evaporator.

[0043] Example 2: Verification of the scale prevention performance of a high-efficiency sodium bicarbonate decomposition and evaporation system integrating MVR technology.

[0044] ① Raw material source: High-salinity wastewater (sodium salt 70-120g / L, pH 9.2, Ca²⁺, Mg²⁺) + 200ppm).

[0045] ② The MVR evaporation concentration and scaling verification process is as follows: High-salt wastewater is fed into preheater 2 by feed pump 9. After heat exchange and recovery of latent heat in the condensate in preheater 2, the preheated saline wastewater enters heating chamber 3. After being heated in heating chamber 3, the saline wastewater enters evaporation chamber 4 and evaporates at 85℃. The secondary steam generated in evaporation chamber 4 is compressed by steam compressor 12 at a speed of 4800 rpm and then enters heating chamber 3 for recycling. When the evaporation chamber 4 concentrates the brine to a certain concentration and the sodium carbonate and sodium bicarbonate reach a certain ratio, it is introduced into carbonization tower 5 by discharge pump 12 to carry out carbonization reaction with carbon dioxide. The scaling trend of the MVR evaporator is monitored in real time by online monitoring module 6. Based on the prediction results, an automatic cleaning program is triggered to flush the MVR evaporator with pulse waves with a running cycle of 24 hours and a frequency of 20-50kHz.

[0046] ③ Test results show that the heat transfer coefficient of the MVR evaporation system only decreased by 7% after running for 600 hours.

[0047] Comparative Example 2: The high-frequency electromagnetic pulse device 7 of the MVR was turned off, and the same high-efficiency decomposition and evaporation experiment as in Example 2 was carried out on the high-salt wastewater.

[0048] ① Raw material source: High-salinity wastewater (sodium salt 70-120g / L, pH 9.2, Ca²⁺, Mg²⁺) + 200ppm).

[0049] ② The MVR high-efficiency decomposition, evaporation, and scaling verification process is as follows: High-salt wastewater is fed into preheater 2 by feed pump 9. After heat exchange and recovery of latent heat in the condensate by preheater 2, the preheated saline wastewater enters heating chamber 3. After being heated in heating chamber 3, the saline wastewater enters evaporation chamber 4 and evaporates at a temperature of 85℃. The secondary steam generated in evaporation chamber 4 is compressed by steam compressor 12 at a speed of 4800 rpm and then enters heating chamber 3 for recycling. When the evaporation chamber 4 is concentrated to a certain concentration and the sodium carbonate and sodium bicarbonate reach a certain ratio of brine, it is introduced into carbonization tower 5 by discharge pump 12 to carry out carbonization reaction with carbon dioxide. After releasing heat, the steam in heating chamber 3 becomes condensate and flows out from the bottom of heating chamber 3. It is discharged to condensate tank 13 along with non-condensable gas and then sent to preheater 2 by water pump B11 to preheat the saline wastewater. The non-condensable gas is treated simply to recover CO2 gas.

[0050] ③ Test results show that the heat transfer coefficient of the MVR high-efficiency decomposition and evaporation system that did not use high-frequency pulse cleaning decreased by 45% after 200 hours of operation.

[0051] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent transformations or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. A high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production that replaces wet decomposition towers, characterized in that, include: Buffer tank (1) is used to receive saline wastewater from the raw material tank. The saline wastewater is a mixed salt solution of sodium carbonate and sodium bicarbonate. The preheater (2) is used to receive the saline wastewater in the buffer tank (1) and initially raise its temperature; The heating chamber (3) is used to receive the preheated saline wastewater from the preheater (2), and to indirectly heat and raise the temperature of the saline wastewater using steam, and to wet decompose sodium bicarbonate. The condensate after heating and decomposition is transported to the condensate tank (13) for gas-liquid separation. The liquid enters the preheater (2) to heat the brine. In addition, the steam in the heating chamber (3) becomes condensate after releasing heat, and is discharged to the condensate tank (13) together with the non-condensable gas. The steam compressor (12) compresses and heats the secondary steam generated in the evaporation chamber (4) with a slight negative pressure to reach the set temperature; the heated steam is introduced into the heating chamber (3), and if the amount of steam is insufficient, it is supplemented with fresh steam; Evaporation chamber (4) is used to receive the heated brine and some liquid water, which are flashed into steam to concentrate the brine. The secondary steam flashed out in evaporation chamber (4) is compressed and heated by steam compressor (12) and then sent back to heating chamber (3). The brine is concentrated to a certain concentration and sodium carbonate and sodium bicarbonate reach a certain ratio in evaporation chamber, and then introduced into carbonation tower (5) by discharge pump (10). Carbonization tower (5) is used to receive concentrated solution and CO2 gas in evaporation chamber (4) for carbonization reaction; The online monitoring module (6) is connected to the evaporation chamber (4) to monitor the real-time scaling trend in the evaporation chamber (4) and send a signal to the high-frequency electromagnetic pulse device (7); A high-frequency electromagnetic pulse device (7) is connected to the outlet of the evaporation chamber (4) to periodically rinse the evaporation chamber (4) with high-frequency pulse waves, thereby periodically disturbing the solution to inhibit crystal nucleus growth.

2. The MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production as described in claim 1, which replaces the wet decomposition tower, is characterized in that: A water pump A (8) is connected between the buffer tank (1) and the raw material tank containing saline wastewater, a feed pump (9) is connected between the buffer tank (1) and the preheater (2), and a discharge pump (10) is connected between the evaporation chamber (4) and the carbonization tower (5).

3. The MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production as described in claim 1, wherein the condensate after steam exchange in the heating chamber (3) enters the condensate tank (13), and a water pump B (11) is connected between the condensate tank (13) and the preheater (2).

4. The MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production as described in claim 1, which replaces the wet decomposition tower, is characterized in that: The preheater (2) is a plate heat exchanger, and the condensate in the preheater (2) is discharged through the drain pipe.

5. The MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production as described in claim 1, which replaces the wet decomposition tower, is characterized in that: The saline wastewater in the evaporation chamber (4) is first preheated by the condensate transported by the water pump B (11) before entering the heating chamber (3) for heating.

6. A high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production, as described in claim 1 or 5, characterized in that: The steam in the evaporation chamber (4) is transported to the heating chamber (3) as the heating source carrier of the heating chamber (3).

7. The MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production as described in claim 1, which replaces the wet decomposition tower, is characterized in that: The steam compressor (12) is a mechanical steam re-compressor, and the isentropic efficiency of the steam compressor (12) is ≥80%.

8. The MVR high-efficiency decomposition and evaporation system for sodium bicarbonate production as described in claim 1, which replaces the wet decomposition tower, is characterized in that: The high-frequency electromagnetic pulse device (7) has a pulse frequency of 20-50kHz and a power density of 5-10W / cm². The discharge head of the high-frequency electromagnetic pulse device (7) is connected to the outlet of the evaporation chamber (4).

9. A high-efficiency MVR decomposition and evaporation system for sodium bicarbonate production, as described in claim 1 or 8, characterized in that: The online monitoring module (6) includes a conductivity sensor and a differential pressure transmitter connected to the evaporation chamber (4). The conductivity sensor and differential pressure transmitter monitor the scaling trend in real time and are electrically connected to the PLC controller. The PLC controller is electrically connected to the high-frequency electromagnetic pulse device (7) and can trigger the cleaning program of the high-frequency electromagnetic pulse device (7).

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