Closed heat exchange circulating water and saline water concentration coupling device and process thereof

Abstract

The invention relates to a closed heat exchange circulating water and saline water concentration coupling device and a process thereof, the device comprises a closed circulating water system and a high-salinity water concentration system, and is characterized in that the high-salinity water concentration system is a closed circulating water cooling tower, the closed circulating water cooling tower is of a three-section structure, namely an upper section, a middle section and a lower section, a fan and a sprayer are mounted in the upper section, a straight-section air duct, a second heat exchanger and an air inlet grille are mounted in the middle section, a salt storage water tank is mounted in the lower section, and a closed circulating water system is formed among the second heat exchanger, an external first heat exchanger, a buffer and a circulating water pump. According to the invention, the chlorine salt water needing to be concentrated is evaporated by fully utilizing the characteristics of the circulating water cooling tower and the heat transfer requirement, so that the concentration of 5% chlorine salt water reaches 30% or above, and the concentrated salt water is sold as a byproduct, or is evaporated and crystallized in a multi-effect evaporation device to produce byproduct salt (calcium chloride / sodium chloride industrial salt).

Description

Technical Field

[0001] The present invention relates to the field of industrial technology, and in particular to a coupling device for concentrating closed heat exchange circulating water and brine and a process thereof. Background Art

[0002] In existing technologies, for the treatment of saline wastewater (calcium chloride, sodium chloride, etc.), industrial enterprises generally dilute it with water and use it as greening water or discharge it directly. This treatment method easily leads to a large amount of water resource waste, environmental pollution and damage to the ecological balance of water bodies.

[0003] Enterprises with a large amount of by-product salty wastewater generally use thermal desalination methods such as evaporation, concentration, and crystallization. However, in actual applications, thermal desalination consumes a lot of energy. Evaporation treatment requires 0.4-0.5 tons of steam per ton of water, which makes the production cost of enterprises high. Therefore, most enterprises are developing various energy-saving evaporators, such as multi-effect evaporators, thermal cycle steam recompressors, mechanical steam recompressors, etc. The existing by-product salty water treatment processes are as follows: Figure 1 and Figure 2 .

[0004] At present, the industries that produce saline wastewater as by-products (such as chlorosilane, polysilicon, silane, nano-silicon-carbon negative electrode material manufacturers, etc.) all use multi-effect evaporation and crystallization concentration. The heat required for multi-effect evaporation and crystallization is a large source of energy consumption. Although the current mainstream method of using MVR to improve steam utilization and energy saving has certain effects, its energy saving and emission reduction effects are also very limited. In the industries that produce saline wastewater as by-products (such as chlorosilane, polysilicon, silane, nano-silicon-carbon negative electrode material manufacturers, etc.), take a silane unit with an annual output of 5,000 tons as an example: the chlorine consumption of the silane unit is 0.1~0.3kg / kg.SiH4, producing 5~15m³ / h of 5% chlorine brine, and the steam consumption of brine evaporation and crystallization is 2.3~7.1t / h; the circulating water cooling tower is a conventional heat exchange device in chemical production equipment. The circulating water cooling tower of a silane unit with an annual output of 5,000 tons requires about 4,000m³ / h, and the heat required to be released is 1.344*10 8 kj / h (equivalent to steam volume of approximately 59.5t / h).

[0005] According to the above balance calculation, a large amount of heat in the circulating water cooling tower of the silane device is consumed by heat transfer using spray cooling water and air coolers in conventional cooling; Therefore, a closed heat exchange coupling device for circulating water and brine concentration and its process are designed to overcome the above problems. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of the prior art by providing a simple, closed-loop heat exchange coupled device and process for circulating water and brine concentration that saves energy, reduces emissions, and reduces consumption. The present invention fully utilizes the characteristics of a circulating water cooling tower and its heat transfer requirements to evaporate the chloride-containing brine to be concentrated, achieving a concentration of 5% chloride-containing brine to over 30%. The concentrated brine is then sold as a byproduct or further evaporated and crystallized in a multiple-effect evaporator to produce byproduct salt (calcium chloride / sodium chloride industrial salt) for sale.

[0007] The present invention is achieved through the following technical solution: a closed heat exchange circulating water and brine concentration coupling device, which includes a closed circulating water system and a high-salt water concentration system. The high-salt water concentration system is a closed circulating water cooling tower. The closed circulating water cooling tower has a three-section structure, namely an upper section, a middle section, and a lower section, all of which are detachably installed by bolts. A fan and a sprinkler are installed inside the upper section, a straight section air duct and a second heat exchanger and an air inlet grille are installed in the middle section, and a brine storage tank is installed in the lower section. A closed circulating water system is formed between the second heat exchanger and the external first heat exchanger, a buffer, and a circulating water pump.

[0008] Preferably, the sprayer is connected to an external high-salt water system through a spray pipe, a fan is installed above the sprayer, and the lower part faces the second heat exchanger, a straight air duct is installed on the tower wall below the second heat exchanger, an air inlet grille is provided outside the straight air duct, and a brine storage pool is provided at the bottom of the tower facing the sprayer. After the high-salt water is sprayed toward the heat exchanger through the sprayer, the concentrated brine falls into the brine storage pool, and the water vapor is blown to the outside through the fan.

[0009] Preferably, a pipe is provided outside the salt water storage tank, and the pipe flows water to the outside in one direction through a spray salt water pump, and returns water to the spray pipe in the other direction for further concentration.

[0010] Preferably, one end of the second heat exchanger is connected to the first heat exchanger, and the other end is connected to the buffer. The buffer is connected to the first heat exchanger through a circulating water pump to form a closed loop. A water adding pipe and a drug adding pipe are also provided in the buffer, and a sewage treatment outlet is also opened at the bottom.

[0011] Preferably, the first heat exchanger is an equal-wall heat exchanger, and the second heat exchanger is a shell-and-tube heat exchanger.

[0012] A process for coupling closed heat exchange circulating water and brine concentration, wherein the process comprises adding a closed heat exchange circulating water system to a closed circulating water cooling tower, and concentrating the sprayed brine by coupling the closed circulating water system with the water cooling tower. The process specifically comprises a high brine concentration method and a closed heat exchange circulating water method.

[0013] Preferably, the high-salt water concentration method comprises the following steps: 1) 5% of the brine in the external brine system enters the sprinkler in the cooling tower through the pipeline and is sprayed onto the second heat exchanger through the sprinkler; 2) The brine sprayed onto the second heat exchanger exchanges heat with the circulating water inside the heat exchanger, and the heated high-salt water drips from top to bottom into the high-salt water pool; 3) Dry cold air from the fan enters from the straight section of the air duct and enters the closed-circulation water cooling tower from bottom to top. It contacts the brine dripping from top to bottom in the tower space in countercurrent, undergoing multiple heat and mass exchanges. After the heat exchange, the water in the brine evaporates under the action of the dry cold air, forming saturated water vapor in the upper section of the cooling tower. The fan then sends the saturated water vapor into the external ambient air. The high brine after the volatilization enters the brine storage tank under the action of gravity for collection. 4) The brine storage tank at the bottom is divided into two pipelines through the spray brine pump to send out concentrated brine: one pipeline is merged with the pipeline from the external brine system and then sprayed with concentrated salt under the action of the sprinkler; the other pipeline is measured to have a chloride content of 30% and is sent to the buffer pool for takeout processing.

[0014] Preferably, the closed heat exchange circulating water method comprises the following steps: 1) The first heat exchanger performs the first heat exchange at the user end. The hot water flows into the second heat exchanger to exchange heat with the brine. The water after heat exchange flows into the buffer. The buffer uses a circulation pump to circulate the water back to the first heat exchanger for reuse. 2) Observe the water volume in the circulating water in the buffer through a liquid level meter or scale level. When the water volume is too low, start the water supply pipe to replenish water; 3) A water quality detector is also installed in the buffer to observe the water quality. When the water quality is low, the dosing pipe is opened for dosing treatment, and the sewage is discharged through the sewage outlet to achieve the goal of cleaning the water quality.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1) The present invention reduces the land required for the construction of a multi-effect evaporation device; 2) The simplification of the present invention reduces the construction of multi-effect evaporation and greatly reduces capital investment; 3) The present invention simplifies the operation to room temperature, effectively reducing process and safety risks; 4) The present invention changes the conventional multi-effect evaporation process from internal brine concentration to external brine concentration, which greatly reduces the process continuity problems caused by process scaling and blockage; 5) The present invention combines the characteristics of chemical process technology and optimizes the process flow, achieving simplification, short process flow, less equipment, etc., greatly improving production efficiency; 6) The present invention fully utilizes the characteristics of the circulating water cooling tower and the heat transfer requirements, uses chloride-containing brine to evaporate water, and concentrates 5% chloride-containing brine to a concentration of more than 30%, saving 5.25t / h of steam and generating huge economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the existing brine concentration process diagram; Figure 2 This is a diagram of an existing brine concentration plant; Figure 3 It is the overall flow chart of the present invention; Figure 4 It is a structural schematic diagram of the closed-cycle water cooling tower in the present invention. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to more clearly understand the objectives, technical solutions and advantages of the present invention, the present invention is further described below with reference to the accompanying drawings and embodiments.

[0018] In the description of the present invention, it should be understood that the orientations or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “inside”, “outside”, “horizontal” and “vertical” are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or component referred to must have a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0019] The present invention will be described in detail below with reference to the accompanying drawings: Figure 3-4 As shown, a closed heat exchange circulating water and brine concentration coupling device includes a closed circulating water system 17 and a high-salt water concentration system 18. The high-salt water concentration system is a closed circulating water cooling tower. The closed circulating water cooling tower has a three-section structure, namely an upper section 5, a middle section 4, and a lower section, all of which are detachably installed by bolts. A fan 6 and a sprinkler 7 are installed inside the upper section 5, a straight section air duct and a second heat exchanger 3 and an air inlet grille are installed in the middle section 4, and a brine storage tank 1 is installed in the lower section. A closed circulating water system is formed between the second heat exchanger 3 and the external first heat exchanger 12, the buffer 13, and the circulating water pump 11.

[0020] The sprayer 7 is connected to the external high-salt water system through a spray pipe. A fan 6 is installed above the sprayer 7 and faces the second heat exchanger 3 below. A straight air duct is installed on the tower wall below the second heat exchanger 3. Air inlet grilles are provided outside the straight air duct. The air inlet grilles are the left air inlet grille 2 and the right air inlet grille 9. A brine storage pool 1 is provided at the bottom of the tower facing the sprayer 7. After the high-salt water is sprayed toward the heat exchanger through the sprayer 7, the concentrated brine falls into the brine storage pool 1, and the water vapor is blown to the outside through the fan 6.

[0021] A pipe is further provided outside the salt water storage tank 1 , through which the water flows to the outside in one direction through a spray salt water pump 10 and returns to the spray pipe in the other direction for further concentration.

[0022] One end of the second heat exchanger 3 is connected to the first heat exchanger 12, and the other end is connected to the buffer 13. The buffer 13 is connected to the first heat exchanger 12 through a circulating water pump 11 to form a closed loop. A water supply pipe 14 and a drug supply pipe 15 are also provided in the buffer 13, and a sewage treatment outlet 16 is also provided at the bottom. The water supply pipe in the buffer of the present invention is used to replenish water in the process flow, and its liquid level can be observed in real time using a liquid level meter. The drug supply pipe is used to close all pipes after the entire device is used, and then add cleaning drugs to clean the pipes in the device, thereby removing harmful substances and ensuring the normal use of the device. The drug supply pipe can be monitored in real time by an environmental detector to ensure the cleanliness of the device pipes.

[0023] The first heat exchanger 12 is a partition heat exchange type heat exchanger, and the second heat exchanger 3 is a shell and tube heat exchanger.

[0024] A process for coupling closed heat exchange circulating water and brine concentration, wherein the closed heat exchange circulating water system is added to a closed heat exchange circulating water cooling tower, and the brine is concentrated by coupling the heat exchange circulating water system with the water cooling tower. The process specifically includes a high-salt water concentration method and a closed heat exchange circulating water method.

[0025] The high-salt water concentration method comprises the steps: 1) 5% of the brine in the external brine system enters the sprinkler in the cooling tower through the pipeline and is sprayed onto the second heat exchanger through the sprinkler; 2) The brine sprayed onto the second heat exchanger exchanges heat with the circulating water inside the heat exchanger, and the heated high-salt water drips from top to bottom into the high-salt water pool; 3) Dry cold air from the fan enters the straight section of the air duct through the air inlet grille, and then enters the closed-circulation water cooling tower from bottom to top. It contacts the brine dripping from top to bottom in the tower space in countercurrent, undergoing multiple heat and mass exchanges. After the heat exchange, the water in the brine evaporates under the action of the dry cold air, forming saturated water vapor in the upper section of the cooling tower. The fan then sends the saturated water vapor into the external ambient air. The high brine after the volatilization enters the brine storage tank under the action of gravity for collection. 4) The brine storage tank at the bottom is divided into two pipelines through the spray brine pump to send out concentrated brine: one pipeline is merged with the pipeline from the external brine system and then sprayed with concentrated salt under the action of the sprinkler; the other pipeline is measured to have a chloride content of 30% and is sent to the buffer pool for takeout processing.

[0026] The closed heat exchange circulating water method comprises the following steps: 1) The first heat exchanger performs the first heat exchange at the user end. The hot water flows into the second heat exchanger to exchange heat with the brine. The water after heat exchange flows into the buffer. The buffer uses a circulation pump to circulate the water back to the first heat exchanger for reuse. 2) Observe the water volume in the circulating water in the buffer through a liquid level meter or scale level. When the water volume is too low, start the water supply pipe to replenish water; 3) A water quality detector is also installed in the buffer to observe the water quality. When the water quality is low, the dosing pipe is opened for dosing treatment, and the sewage is discharged through the sewage outlet to achieve the goal of cleaning the water quality.

[0027] The overall process of the present invention is specifically as follows: The 5% process high brine from the high brine system is transported by pipeline to the closed-circulation water cooling tower as the refrigerant of the closed-circulation water system, and undergoes wall heat exchange with the hot closed-circulation water heated by the first heat exchanger in the closed-circulation water cooling tower. After the heat exchange, the heated process high brine is in countercurrent contact with the dry cold air in the closed-circulation water cooling tower for multiple heat and mass exchanges. The water in the hot high brine is volatilized under the action of the dry cold air to form saturated water vapor and is sent into the external ambient air; the high brine after volatilization is collected at the bottom of the closed-circulation water cooling tower under the action of gravity, and the high brine at the bottom of the closed-circulation water cooling tower is divided into two pipelines by a spray brine pump to send out concentrated brine: one pipeline is merged with the pipeline from the high brine system and then goes to the sprayer to spray concentrated salt; the other pipeline is sent to the buffer pool after measurement to meet the standard (chloride content reaches 30%), and is waiting for takeaway processing.

[0028] The design features of the present invention are as follows: 1. The brine is concentrated by coupling with closed heat exchange circulating water, which is a new innovation. Secondly, the role of the cooling tower is not only to cool the liquid but also to concentrate the brine.

[0029] 2. The closed heat exchange circulating water adopts secondary heat exchange to maximize the heat exchange efficiency, and concentrates the brine to make the temperature of the closed circulation water reach the temperature required by the industrial device.

[0030] 3. Perform heat exchange twice in the water cooling tower to concentrate the brine in the atmospheric environment (similar to the ancient salt drying process), without polluting the environment, and is more economical and environmentally friendly.

[0031] The specific embodiments described herein are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A closed heat exchange circulating water and brine concentration coupling device, comprising a closed circulating water system and a high brine concentration system, characterized in that: The high-salt water concentration system is a closed-loop water cooling tower. The closed-loop water cooling tower has a three-section structure, namely the upper section, the middle section, and the lower section, all of which are detachably installed by bolts. A fan and a sprinkler are installed inside the upper section, a straight-section air duct and a second heat exchanger and an air inlet grille are installed in the middle section, and a salt water storage tank is installed in the lower section. A closed circulating water system is formed between the second heat exchanger and the external first heat exchanger, the buffer, and the circulating water pump.

2. The closed heat exchange coupling device for circulating water and concentrating brine according to claim 1 is characterized in that: The sprayer is connected to the external high-salt water system through a spray pipe. A fan is installed above the sprayer and faces the second heat exchanger below. A straight air duct is installed on the tower wall below the second heat exchanger, and an air inlet grille is provided outside the straight air duct. A brine storage pool is provided at the bottom of the tower facing the sprayer. After the high-salt water is sprayed toward the heat exchanger through the sprayer, the concentrated brine falls into the brine storage pool, and the water vapor is blown to the outside through the fan.

3. The closed heat exchange circulating water and brine concentration coupling device according to claim 2 is characterized in that: A pipe is also provided outside the salt water storage tank, through which the water flows to the outside in one direction through a spray salt water pump, and returns to the spray pipe in the other direction for further concentration.

4. The closed heat exchange coupling device for circulating water and concentrating brine according to claim 1 is characterized in that: One end of the second heat exchanger is connected to the first heat exchanger, and the other end is connected to the buffer. The buffer is connected to the first heat exchanger through a circulating water pump to form a closed loop. The buffer is also provided with a water adding pipe and a drug adding pipe, and a sewage treatment outlet is also opened at the bottom.

5. The closed heat exchange coupling device for circulating water and concentrating brine according to claim 1 is characterized in that: The first heat exchanger is a partition heat exchange type heat exchanger, and the second heat exchanger is a shell and tube heat exchanger.

6. A process for coupling closed heat exchange circulating water with brine concentration, characterized by: The process is to add a closed heat exchange circulating water system to a closed circulating water cooling tower, and concentrate the spray brine by coupling the closed circulating water system with the water cooling tower. The process specifically includes a high brine concentration method and a closed heat exchange circulating water method.

7. The process of coupling closed heat exchange circulating water and brine concentration according to claim 6, characterized in that: The high-salt water concentration method comprises the steps: 1) 5% of the brine in the external brine system enters the sprinkler in the water cooling tower through the pipeline and is sprayed onto the second heat exchanger through the sprinkler; 2) The brine sprayed onto the second heat exchanger exchanges heat with the circulating water inside the heat exchanger, and the heated high-salt water drips from top to bottom into the high-salt water pool; 3) Dry cold air from the fan enters from the straight section of the air duct and enters the closed-circulation water cooling tower from bottom to top. It contacts the brine dripping from top to bottom in the tower space in countercurrent flow, undergoing multiple heat and mass exchanges. After the heat exchange, the water in the brine evaporates under the action of the dry cold air, forming saturated water vapor in the upper section of the cooling tower, which is then sent into the external ambient air by the fan. After the water evaporates, the high-salt water enters the brine storage tank for collection under the action of gravity; 4) The brine storage tank at the bottom is divided into two pipelines through the spray brine pump to send out concentrated brine: one pipeline is merged with the pipeline from the external brine system and then sprayed with concentrated salt under the action of the sprinkler; the other pipeline is measured to have a chloride content of 30% and is sent to the buffer pool for takeout processing.

8. The process of coupling closed heat exchange circulating water and brine concentration according to claim 6, characterized in that: The closed heat exchange circulating water method comprises the following steps: 1) The first heat exchanger performs the first heat exchange at the user end. The hot water flows into the second heat exchanger to exchange heat with the brine. The water after heat exchange flows into the buffer. The buffer uses a circulation pump to circulate the water back to the first heat exchanger for reuse. 2) Observe the water volume in the circulating water in the buffer through a liquid level meter or scale level. When the water volume is too low, start the water supply pipe to replenish water; 3) A water quality detector is also installed in the buffer to observe the water quality. When the water quality is low, the dosing pipe is opened for dosing treatment, and the sewage is discharged through the sewage outlet to achieve the goal of cleaning the water quality.

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