A catalytic wet oxidation reaction system

Abstract

The utility model discloses a catalytic wet oxidation reaction system, including oxidation tower, steam generator, vapor liquid separation tank, falling film circulating pump, preoxidation tower, booster pump and steam water mixer, the oxidation water export of oxidation tower is connected with the oxidation water import of steam generator, and the heat exchange is carried out to oxidation water and pure water in steam generator, and pure water is heated and pressurized to generate high temperature steam, and oxidation water is cooled, high temperature steam and raw water are mixed to preheat raw water through vapor liquid separation tank and steam water mixer, preheat raw water is preoxidized through preoxidation tower, then is passed through booster pump and is passed in oxidation tower import, and falling film circulating pump is used for circulating the separated liquid pure water and pumps into steam generator, the utility model discloses raw water and high temperature steam are mixed for the first time, preheat raw water, do not need traditional column tube heat exchanger and additional heater, avoid the problem of frequent blockage of heat exchanger and heater, can greatly prolong the device continuous operation cycle, and generate high temperature steam byproduct.

Description

Technical Field

[0001] This utility model belongs to the field of wastewater treatment, specifically relating to a catalytic wet oxidation reaction system. Background Technology

[0002] Catalytic wet oxidation (CWAO) is a treatment process that effectively degrades organic pollutants in wastewater using a highly efficient catalyst under specific temperature and pressure conditions. It offers unique advantages in treating medium- to high-concentration, recalcitrant organic wastewater. Compared to traditional methods, CWAO technology exhibits numerous advantages, including high treatment efficiency, small footprint, wide applicability, and low secondary pollution. Currently, catalytic wet oxidation technology is relatively mature for treating conventional medium- to high-concentration, recalcitrant organic wastewater.

[0003] During the operation of a CWAO system, the reaction temperature is typically controlled within the range of 200-300℃. The oxidation reaction of organic pollutants in the wastewater releases heat, resulting in a high temperature for the effluent from the oxidation liquid. To utilize this heat, current technologies typically involve exchanging heat between the effluent from the top of the tower and the cold raw wastewater entering the system. This method can raise the raw water temperature to some extent. However, in most cases, this heat exchange method alone is insufficient to raise the raw water temperature to the required reaction temperature. Especially for raw water with low COD values, further preheating is often necessary. Therefore, a heater is usually connected in series after the last stage heat exchanger to achieve this. In practical applications, shell-and-tube heaters are a commonly used type of heater.

[0004] However, during actual system operation, when the raw wastewater is heated within the operating temperature range of the heat exchanger and heater, the organic matter in the wastewater undergoes oxidation and decomposition during heating. Since the pipes of the heat exchanger and heater are relatively narrow, coking or scaling easily occurs inside the heat exchanger or heater. This coking or scaling can cause blockage of the heat exchanger or heater, significantly reducing heat exchange and heating efficiency and preventing the achievement of the expected reaction temperature. This not only drastically reduces reaction efficiency but, in severe cases, can even cause the system to cease normal operation, necessitating a shutdown for cleaning. This situation seriously affects the normal production operation of the plant.

[0005] It is necessary to develop a catalytic wet oxidation reaction system that can utilize the heat from the effluent of the oxidation liquid to heat the raw wastewater without clogging the heat exchanger or heater, thereby extending the continuous operation cycle of the system and improving production efficiency. Utility Model Content

[0006] The purpose of this invention is to provide a catalytic wet oxidation reaction system that can maximize the continuous operation cycle of the system and avoid the clogging problems of heat exchangers and heaters.

[0007] The technical solution adopted in this utility model is: A catalytic wet oxidation reaction system includes an oxidation tower, a steam generator, a vapor-liquid separator, a falling film circulating pump, a pre-oxidation tower, a booster pump, and a vapor-water mixer; The oxidation tower is equipped with an oxidation water outlet and a wastewater inlet. The steam generator is equipped with an oxidation water inlet, a first pure water inlet, a second pure water inlet, a cooling oxidation water outlet, a first high-temperature steam outlet, and a first liquid pure water outlet. The oxidation water and pure water in the steam generator exchange heat. The pure water is heated and pressurized to generate high-temperature steam, and the oxidation water is cooled. The first pure water inlet is connected to external cold pure water. The oxidation water outlet is connected to the oxidation water inlet of the steam generator; The vapor-liquid separator is provided with a first high-temperature steam inlet, a second liquid pure water outlet, and a second high-temperature steam outlet. The vapor-liquid separator is used to control the high-temperature steam pressure and further separate high-temperature steam and liquid pure water. The first high-temperature steam inlet is connected to the first high-temperature steam outlet of the steam generator. The falling film circulation pump is equipped with a liquid pure water inlet. The first liquid pure water outlet of the steam generator and the second liquid pure water outlet of the vapor-liquid separator are both connected to the liquid pure water inlet. The outlet of the falling film circulation pump is connected to the second pure water inlet of the steam generator, which is used to pump the liquid pure water into the steam generator to generate high-temperature steam again. The liquid pure water in the falling film circulation pump is all high-temperature pure water, which is obtained by condensing high-temperature saturated steam and has a high temperature.

[0008] The steam-water mixer is equipped with a second high-temperature steam inlet and a raw water inlet, which are used to mix high-temperature steam and raw water and exchange heat, and to preheat the raw water. The second high-temperature steam inlet is connected to the second high-temperature steam outlet; The raw water inlet is connected to the raw water pipeline; The steam-water mixer is equipped with a mixed raw water outlet, and the pre-oxidation tower is equipped with a mixed raw water inlet and a pre-oxidized water outlet. The mixed raw water outlet is connected to the mixed raw water inlet. The pre-oxidized water outlet is connected to the wastewater inlet of the oxidation tower via a booster pump.

[0009] The system may further include a gas-liquid separator, which is used to separate the cooled oxidation water into liquid water and waste gas. The gas-liquid separator is provided with a cooling oxidation water inlet, a tail gas outlet, and a treated water discharge outlet. The cooling oxidation water inlet is connected to the cooling oxidation water outlet of the steam generator, and the tail gas outlet is connected to the absorption tower. The treated water discharge outlet can be connected to a post-treatment system or discharged according to the wastewater treatment status.

[0010] The waste gas enters the absorption tower through the tail gas outlet for treatment, and then discharges non-toxic and pollution-free tail gas.

[0011] Furthermore, the second high-temperature steam outlet is divided into two paths: one path is connected to the second high-temperature steam inlet, and the other path is connected to an external steam pipeline to supply excess steam to the external steam network.

[0012] A valve is installed before the second high-temperature steam inlet. The flow rate of high-temperature steam entering the steam-water mixer is controlled by the valve, which in turn controls the temperature of the preheated raw water.

[0013] Furthermore, the oxidation tower is equipped with an oxygen inlet, which is connected to an oxygen tank for introducing oxygen.

[0014] Furthermore, the oxidation tower is equipped with a temperature sensor and an electric heating device to control the reaction temperature inside the oxidation tower.

[0015] Furthermore, the oxidation tower is equipped with automatic temperature and pressure detection elements. Through the controller and computer programming, it provides feedback on the electrical energy required for replenishment, and the heat is supplemented by an external power source.

[0016] The oxidation tower is also equipped with a catalyst inlet, and the catalyst storage tank is connected to the catalyst inlet through a catalyst metering pump to control the amount of catalyst used in the tower.

[0017] The pre-oxidation tower is not equipped with a heating device, and a catalyst may or may not be added to the pre-oxidation tower, depending on the actual wastewater conditions.

[0018] The steam generator includes a heat exchange section and a water-vapor separation section located below the heat exchange section. The heat exchange section is equipped with a pure water pipeline and an oxidation water pipeline. A first pure water inlet and a second pure water inlet are located at the top of the heat exchange section of the steam generator and are connected to the pure water pipeline inlet. The pure water pipeline outlet is located at the bottom of the heat exchange section and is connected to the water-vapor separation section. The oxidation water inlet is located at the upper part of the heat exchange section of the steam generator and is connected to the oxidation water pipeline inlet. The oxidation water pipeline outlet is the cooling oxidation water outlet, located at the lower part of the heat exchange section of the steam generator. The pure water pipeline and the oxidation water pipeline are in the same direction and exchange heat in the heat exchange section of the steam generator. The oxidation water is cooled to obtain cooled oxidation water, while the pure water is heated and pressurized to generate high-temperature steam, which enters the water-steam separation section from the outlet of the pure water pipeline.

[0019] The first high-temperature steam outlet is located in the upper part of the water-vapor separation section, and the first liquid pure water outlet is located at the bottom of the water-vapor separation section. In the water-vapor separation section, saturated high-temperature steam is separated to obtain liquid pure water and high-temperature steam. The liquid pure water flows out from the first liquid pure water outlet and enters the falling film circulation pump, while the high-temperature steam is introduced into the vapor-liquid separator from the high-temperature steam outlet.

[0020] Furthermore, the system also includes a raw water feed pump, and the raw water pipeline is connected to the raw water inlet of the steam-water mixer through the raw water feed pump.

[0021] Furthermore, the vapor-liquid separator is equipped with a pressure gauge and valves to regulate and control the steam pressure inside the vapor-liquid separator, thereby controlling the temperature of the high-temperature saturated steam.

[0022] In this invention, the high-temperature steam is actually high-temperature and high-pressure steam. Generally speaking, the pressure of the high-temperature steam at the second high-temperature steam outlet of the vapor-liquid separator is 0.3~1MPa, and the corresponding temperature is about 130~180℃.

[0023] The method of using the catalytic wet oxidation reaction system of this utility model includes the following steps: (1) Raw water is fed into a steam-water mixer and mixed with high-temperature steam to obtain preheated mixed raw water, which is then fed into a pre-oxidation tower. The organic matter is partially oxidized and decomposed, and the partially oxidized pre-oxidized water is transported to the oxidation tower by a booster pump. Under the action of a catalyst, oxygen is introduced to carry out a catalytic wet oxidation reaction to obtain high-temperature oxidized water effluent. (2) The oxidized water outlet is fed into the steam generator to exchange heat with the pure water. The pure water is heated to obtain high-temperature steam. The high-temperature oxidized water is cooled to obtain cooled oxidized water. The high-temperature steam passes through the vapor-liquid separator, and the steam pressure is controlled to further separate the steam and liquid pure water. The high-temperature steam at the outlet of the vapor-liquid separator is fed into the steam-water mixer to mix with the raw water. (3) Cooling oxidation water is introduced into a gas-liquid separator to separate liquid treatment water and waste gas. The waste gas is introduced into an absorption tower for treatment, and the liquid treatment water is post-treated or discharged according to the treatment status of the wastewater.

[0024] In step (1), the flow rate of high-temperature steam is controlled, thereby controlling the temperature of the preheated mixed raw water to 130~180℃. The preheating temperature of the raw water does not need to be too high, as excessively high temperatures will lead to excessive oxidation and decomposition of organic matter.

[0025] The temperature of high-temperature steam is generally 130~180℃.

[0026] The reaction temperature inside the oxidation tower is generally 200~300℃, preferably 220~280℃.

[0027] Furthermore, in step (1), since high-temperature steam has not yet been generated when the machine is started, the start-up procedure is generally as follows: Pure water is introduced into the pre-oxidation tower and pumped into the oxidation tower. The oxidation tower is heated by electric heating. At this time, no catalyst or oxygen is added to the oxidation tower. After the electric heating reaches 220~240℃, it is switched to raw water. The raw water is sent into the oxidation tower through the pre-oxidation tower and the pump. The oxidation tower is introduced with catalyst and oxygen to carry out catalytic wet oxidation reaction and obtain high-temperature oxidized water effluent. The high-temperature oxidized water effluent is introduced into the steam generator to exchange heat with the cold pure water. The pure water is heated and pressurized to obtain high-temperature steam. The high-temperature oxidized water is cooled to obtain cooled oxidized water. The high-temperature steam is further separated from the liquid pure water by the gas-liquid separator. The high-temperature steam at the outlet of the gas-liquid separator is introduced into the steam-water mixer to mix with the raw water to obtain preheated mixed raw water. Then, the operation is carried out according to step (1).

[0028] The catalytic wet oxidation reaction system provided by this invention is suitable for various types of raw water containing organic matter, with no restrictions on COD or TOC, but it is particularly effective for high-concentration organic wastewater. High-concentration organic wastewater generates more heat in the oxidation tower, resulting in a higher steam production rate. The required preheating temperature for the raw water is also lower, and it is less prone to clogging, thus significantly improving treatment efficiency.

[0029] The catalytic wet oxidation reaction system provided by this invention can treat wastewater with COD greater than 20,000 mg / L and / or TOC greater than 5,000 mg / L.

[0030] It can further treat wastewater with COD greater than 50,000 mg / L.

[0031] The catalytic wet oxidation reaction system provided by this utility model can also treat wastewater with TOC greater than 5000 mg / L, especially wastewater with TOC greater than 10000 mg / L, or even greater than 20000 mg / L.

[0032] In step (2), the liquid pure water obtained from the high-temperature steam passing through the vapor-liquid separator and the liquid pure water condensed in the steam generator are recycled back into the steam generator through a falling film circulation pump.

[0033] Furthermore, the high-temperature steam at the outlet of the gas-liquid separator is divided into two paths: one path goes into the steam-water mixer, and the other path connects to an external steam pipeline.

[0034] In step (1), the temperature inside the oxidation tower is controlled by a temperature sensor and an electric heating device.

[0035] In this invention, the high-temperature, high-pressure oxidizing liquid at the top of the tower indirectly exchanges heat with low-pressure saturated steam produced as a byproduct through a steam drum. All or part of this byproduct steam is directly mixed with the raw water using a steam-water mixer to preheat the raw water. The preheated raw water undergoes a pre-oxidation reaction in the pre-oxidation tower, with the temperature typically controlled below 180°C. Intermediate products resulting from incomplete oxidation remain suspended in the raw water. After passing through the pre-oxidation tower, the pre-oxidized water is pumped into the oxidation tower, where it undergoes a complete oxidation reaction with oxygen under the action of a catalyst.

[0036] Before entering the oxidation tower, wastewater is not preheated by a traditional shell-and-tube heat exchanger, nor does it require an additional heater. Heating occurs directly within the oxidation tower, thus avoiding frequent clogging issues caused by heat exchangers and heaters, reducing the number of equipment shutdowns due to blockages, and significantly extending the continuous operation cycle of the unit. Furthermore, the raw water is mixed with high-temperature steam. The high-temperature steam both heats and dilutes the raw water. Since no additional heating occurs in the pre-oxidation tower, some organic matter in the preheated mixed raw water undergoes oxidation and decomposition at a certain temperature. Incomplete oxidation may produce substances that easily clog the heat exchange tubes. Because the raw water is diluted, these substances do not easily settle but remain suspended in the pre-oxidized water. Moreover, the pre-oxidation tower and booster pump have larger pipes compared to shell-and-tube heat exchangers. Therefore, after passing through the pre-oxidation tower, the pre-oxidized water is in a diluted solid-liquid dispersion state, which is less likely to clog the pipes. Additionally, the wastewater, oxidant air, or oxygen in the oxidation tower can undergo a complete oxidation reaction with the participation of a catalyst, reducing or eliminating the formation of intermediate products. Therefore, coking or scaling does not form within the oxidation tower.

[0037] This invention can treat high-concentration organic wastewater. High-concentration organic wastewater is more prone to scaling and pipe blockage under conventional heat exchange processes. However, this invention utilizes the heat generated by the oxidation of high-concentration organic matter more fully and avoids pipe blockage. When the organic matter content of the raw water is high and the heat release in the oxidation tower is large, the required preheating temperature of the raw water is lower. When the steam-water mixer mixes with high-temperature steam, only a smaller amount of high-temperature steam is needed to preheat the raw water, improving thermal efficiency and generating more high-temperature steam byproducts.

[0038] This invention places the heater inside the oxidation tower, eliminating the need for traditional heaters. Saturated steam recovered from the high-temperature, high-pressure oxidation liquid is directly mixed with the raw water to heat it. This invention reduces heater investment, requires a smaller project footprint, avoids clogging issues in heat exchangers and heaters, and significantly extends the project's operating cycle. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a catalytic wet oxidation reaction system.

[0040] In the diagram, 1-Oxidation tower; 11-Oxidation water outlet; 12-Wastewater inlet; 13-Oxygen inlet; 14-Temperature sensor and electric heating device; 15-Catalyst inlet; 2-Steam generator; 21-Oxidation water inlet; 22-First pure water inlet; 23-Second pure water inlet; 24-Cooling oxidation water outlet; 25-First high-temperature steam outlet; 26-First liquid pure water outlet; 27-Heat exchange section; 28-Water-vapor separation section; 271-Pure water pipeline; 272-Oxidation water pipeline; 3-Vapor-liquid separator; 31-First high-temperature steam inlet; 32-Second liquid pure water outlet; 33-Second high-temperature steam... Outlet; 34-Pressure gauge; 4-Falling film circulation pump; 41-Liquid pure water inlet; 5-Gas-liquid separator; 51-Cooling oxidation water inlet; 52-Tail gas outlet; 53-Treatment water discharge outlet; 6-Pre-oxidation tower; 61-Mixed raw water inlet; 62-Pre-oxidation water outlet; 7-Booster pump; 8-Raw water feed pump; 9-Steam-water mixer; 91-Second high-temperature steam inlet; 92-Raw water inlet; 93-Mixed raw water outlet; 100-Steam pipeline; 101-Oxygen tank; 102-Catalyst metering pump; 103-Absorption tower; 104-Wastewater effluent; 105-Pure water tank; 106-Raw water pipeline. Detailed Implementation

[0041] The specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of this utility model. Based on the description of this utility model, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this utility model.

[0042] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "set up," "equipped with," "located in," "installed," and "connected," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0043] The terms “end,” “side,” “outer side,” “top,” and “bottom,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this utility model is usually placed during use. They are only for the convenience of description and simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0044] In the description of this utility model, unless otherwise expressly specified and limited, the terms "first", "second", etc. are used only to distinguish elements with similar properties, and not to indicate or imply relative importance or a specific order.

[0045] The term “include” or any other variation thereof is intended to cover non-exclusive inclusion, which includes not only those elements listed, but also other elements not expressly listed. Example 1

[0046] A schematic diagram of a catalytic wet oxidation reaction system is shown below. Figure 1 As shown, it includes an oxidation tower 1, a steam generator 2, a vapor-liquid separator 3, a falling film circulating pump 4, a vapor-liquid separator 5, a pre-oxidation tower 6, a booster pump 7, and a vapor-water mixer 9. The oxidation tower 1 is provided with an oxidation water outlet 11 and a wastewater inlet 12. The steam generator 2 is provided with an oxidation water inlet 21, a first pure water inlet 22, a second pure water inlet 23, a cooling oxidation water outlet 24, a first high-temperature steam outlet 25, and a first liquid pure water outlet 26. The oxidation water and pure water in the steam generator 2 exchange heat. The pure water is heated and pressurized to generate high-temperature steam, and the oxidation water is cooled. The first pure water inlet 22 is connected to an external pure water tank 105, and cold pure water is introduced into the steam generator 2. Oxidation water outlet 11 is connected to oxidation water inlet 21 of steam generator; The vapor-liquid separator 3 is provided with a first high-temperature steam inlet 31, a second liquid pure water outlet 32, and a second high-temperature steam outlet 33. The vapor-liquid separator 3 is used to control the high-temperature steam pressure and further separate high-temperature steam and liquid pure water. The first high-temperature steam inlet 31 is connected to the first high-temperature steam outlet 25 of the steam generator 2. Furthermore, the vapor-liquid separator 3 is equipped with a pressure gauge 34 and a valve to control the steam pressure inside the vapor-liquid separator 3, thereby controlling the temperature of the high-temperature saturated steam.

[0047] In this invention, the high-temperature steam is actually high-temperature and high-pressure steam. Generally speaking, the pressure of the high-temperature steam at the second high-temperature steam outlet of the vapor-liquid separator is 0.3~1MPa, and the corresponding temperature is about 130~180℃.

[0048] The falling film circulation pump 4 is equipped with a liquid pure water inlet 41. The first liquid pure water outlet 26 of the steam generator 2 and the second liquid pure water outlet 32 ​​of the vapor-liquid separator 3 are both connected to the liquid pure water inlet 41. The outlet of the falling film circulation pump 4 is connected to the second pure water inlet 23 of the steam generator 2, which is used to pump the liquid pure water into the steam generator 2 to generate high-temperature steam again. The liquid pure water in the falling film circulation pump 4 is all high-temperature pure water, which is obtained by condensation of high-temperature saturated steam and has a high temperature.

[0049] The steam-water mixer 9 is equipped with a second high-temperature steam inlet 91 and a raw water inlet 92, which are used to mix high-temperature steam and raw water and exchange heat, and to preheat the raw water. The second high-temperature steam inlet 91 is connected to the second high-temperature steam outlet 33; The raw water pipeline 106 is connected to the raw water inlet 92; furthermore, the system may also include a raw water feed pump 8, and the raw water pipeline 106 is connected to the raw water inlet 92 of the steam-water mixer 9 through the raw water feed pump 8.

[0050] The steam-water mixer 9 is provided with a mixed raw water outlet 93, and the pre-oxidation tower 6 is provided with a mixed raw water inlet 61 and a pre-oxidized water outlet 62. The mixed raw water outlet 93 is connected to the mixed raw water inlet 61. The pre-oxidized water outlet 62 is connected to the wastewater inlet 12 via a booster pump 7; In a preferred embodiment, a buffer tank is provided before the raw water inlet 61, the raw water outlet 93 is connected to the buffer tank inlet, and the buffer tank outlet is connected to the raw water inlet 61.

[0051] Furthermore, the inlet of the buffer tank is also connected to a pure water pipeline, allowing pure water to be introduced.

[0052] The gas-liquid separator 5 is equipped with a cooling oxidation water inlet 51, a tail gas outlet 52, and a treated water discharge outlet 53. The cooling oxidation water inlet 51 is connected to the cooling oxidation water outlet 24 of the steam generator 2, and the tail gas outlet 52 is connected to the absorption tower 103. The treated water discharge outlet 53 can be connected to a post-treatment system or discharged according to the wastewater treatment status. Pressure reducing valves can be installed at the cooling oxidation water outlet 24, the tail gas outlet 52, and the treated water discharge outlet 53 to reduce the pressure of the cooling oxidation water, tail gas, and treated water.

[0053] The gas-liquid separator 5 is used to separate the cooled oxidized water into liquid water and waste gas. The waste gas enters the absorption tower for treatment through the tail gas outlet 52 and discharges non-toxic and non-polluting tail gas.

[0054] Furthermore, the second high-temperature steam outlet 33 is divided into two paths: one path is connected to the second high-temperature steam inlet 91, and the other path is connected to the external steam pipeline 100 to supply excess steam to the external steam network.

[0055] Furthermore, a valve is provided before the second high-temperature steam inlet 91 to control the flow rate of high-temperature steam entering the steam-water mixer 9, thereby controlling the temperature of the raw water after preheating.

[0056] Furthermore, the oxidation tower 1 is provided with an oxygen inlet 13, which is connected to the oxygen tank 101 for introducing oxygen.

[0057] Furthermore, the oxidation tower 1 is equipped with a temperature sensor and an electric heating device 14 for controlling the reaction temperature inside the oxidation tower 1.

[0058] Traditional processes typically employ tubular heaters, but this invention is the first to use electric heating within the oxidation tower 1, thus avoiding the problem of pipe blockage in tubular heaters.

[0059] The catalytic wet oxidation reaction in oxidation tower 1 is exothermic. In the initial startup phase, the tower temperature is low, requiring the electric heating device to provide the necessary heat to ensure a smooth start-up. As the reaction progresses, the released heat gradually raises the tower temperature. At this point, the frequency of use and power requirements of the electric heating device will decrease accordingly.

[0060] The oxidation tower 1 of this utility model is equipped with an automatic temperature and pressure detection element. Through the controller and computer programming, the electric heating device is automatically adjusted. The automatic temperature and pressure detection element can monitor the temperature and pressure changes in the tower in real time and continuously. The controller automatically adjusts the start and stop of the electric heating device and the power level according to the real-time temperature, the preset temperature range and reaction requirements.

[0061] The oxidation tower 1 is also provided with a catalyst inlet 15. The catalyst storage tank is connected to the catalyst inlet 15 through a catalyst metering pump 102 to control the amount of catalyst used in the tower.

[0062] The pre-oxidation tower 6 is not equipped with a heating device. A catalyst may or may not be added to the pre-oxidation tower 6, depending on the actual wastewater conditions.

[0063] The steam generator 2 includes a heat exchange section 27 and a water-vapor separation section 28 located below the heat exchange section 27. The heat exchange section 27 is provided with a pure water pipeline 271 and an oxidation water pipeline 272. A first pure water inlet 22 and a second pure water inlet 23 are located at the top of the heat exchange section 27 of the steam generator 2 and communicate with the inlet of the pure water pipeline 271. The outlet of the pure water pipeline 271 is located at the bottom of the heat exchange section 27 and communicates with the water-vapor separation section 28. The oxidation water inlet 21 is located at the upper part of the heat exchange section 27 of the steam generator 2 and is connected to the inlet of the oxidation water pipeline 272. The outlet of the oxidation water pipeline 272 is the cooling oxidation water outlet 24, which is located at the lower part of the heat exchange section 27 of the steam generator 2. The pure water pipeline 271 and the oxidation water pipeline 272 are in the same direction and exchange heat in the heat exchange section 27. The oxidation water is cooled to obtain cooled oxidation water, and the pure water is heated and pressurized to generate high-temperature steam, which enters the water vapor separation section 28 from the outlet of the pure water pipeline 271.

[0064] The first high-temperature steam outlet 25 is located in the upper part of the water-vapor separation section 28, and the first liquid pure water outlet 26 is located at the bottom of the water-vapor separation section 28. In the water-vapor separation section 28, saturated high-temperature steam is separated to obtain liquid pure water and high-temperature steam. The liquid pure water flows out from the first liquid pure water outlet 26 and enters the falling film circulation pump 4, while the high-temperature steam is introduced into the vapor-liquid separator 3 from the high-temperature steam outlet.

[0065] Example 2: A company's pesticide wastewater has a flow rate of 120 t / d and a COD of 40,000~50,000 mg / L. Two different process flows were used to treat the wastewater: The wastewater is treated using a traditional process, as follows: (1) The raw water is fed into the heat exchanger after being boosted by the pump, and exchanges heat with the high temperature oxidation water effluent. The preheated raw water enters the heater and is heated to 220~250℃. Then it is fed into the oxidation tower. Under the action of the catalyst, oxygen is introduced to carry out the catalytic wet oxidation reaction to obtain the high temperature oxidation water effluent. The high temperature oxidation water effluent is fed into the heat exchanger and exchanges heat with the raw water to obtain the cooled oxidation water. (2) Cooling oxidation water is introduced into a gas-liquid separator to separate liquid treatment water and waste gas. The waste gas is introduced into an absorption tower for treatment, and the liquid treatment water is post-treated or discharged according to the treatment status of the wastewater.

[0066] Under traditional processes, the heaters and heat exchangers must be shut down for cleaning after no more than 7 days of continuous operation. The process flow steps of the catalytic wet oxidation reaction system of this invention are as follows: (1-1) Start-up stage: Pure water is introduced into the pre-oxidation tower and pumped into the oxidation tower. The oxidation tower is heated by electric heating. At this time, no catalyst or oxygen is added to the oxidation tower. After the electric heating reaches 220~240℃, it is switched to raw water. The raw water is sent into the oxidation tower through the pre-oxidation tower and the pump. The oxidation tower is introduced with catalyst and oxygen to carry out catalytic wet oxidation reaction and obtain high-temperature oxidized water effluent. The high-temperature oxidized water effluent is introduced into the steam generator to exchange heat with the cold pure water. The pure water is heated and pressurized to obtain high-temperature steam. The high-temperature oxidized water is cooled to obtain cooled oxidized water. The high-temperature steam is further separated into steam and liquid pure water by the gas-liquid separator. The high-temperature steam is introduced into the gas-water mixer. (1-2) Operation stage: Raw water is fed into the steam-water mixer and mixed with high-temperature steam to obtain preheated mixed raw water. The flow rate of high-temperature steam is controlled, thereby controlling the temperature of the preheated mixed raw water to 150~160℃. The preheated mixed raw water is fed into the pre-oxidation tower, where organic matter is partially oxidized and decomposed. The partially oxidized pre-oxidized water is transported to the oxidation tower by a booster pump. At this time, no electric heating is required. The temperature inside the oxidation tower is controlled at 270~280℃. Under the action of a catalyst, oxygen is introduced to carry out a catalytic wet oxidation reaction to obtain high-temperature oxidized water effluent. (2) The oxidized water outlet is fed into the steam generator and indirectly exchanges heat with the pure water. The pure water is heated and pressurized to obtain high-temperature steam. The high-temperature oxidized water is cooled to obtain cooled oxidized water. The high-temperature steam passes through the vapor-liquid separator, and the pressure is controlled to further separate the steam and liquid pure water. The pressure of the high-temperature steam is controlled at 0.6MPa and the temperature is 150~160℃. The high-temperature steam at the outlet of the vapor-liquid separator is divided into two paths. One path is fed into the steam-water mixer to mix with the raw water, and the other path is connected to the external steam pipeline. The liquid pure water obtained by the high-temperature steam passing through the vapor-liquid separator and the liquid pure water condensed in the steam generator are recycled into the steam generator through the falling film circulation pump. (3) Cooling oxidation water is introduced into a gas-liquid separator to separate liquid treatment water and waste gas. The waste gas is introduced into an absorption tower for treatment, and the liquid treatment water is post-treated or discharged according to the treatment status of the wastewater.

[0067] Using the above process, the continuous operation time of this system reaches 2 months, eliminating the need for frequent shutdowns for cleaning, thus greatly extending the operating cycle and saving cleaning costs. The system also generates additional economic benefits by producing steam at a pressure of approximately 1500 kg / h through the steam generator's byproduct steam.

Claims

1. A catalytic wet oxidation reaction system, characterized in that... It includes an oxidation tower, a steam generator, a vapor-liquid separator, a falling film circulating pump, a gas-liquid separator, a pre-oxidation tower, a booster pump, and a steam-water mixer; The oxidation tower is equipped with an oxidation water outlet and a wastewater inlet. The steam generator is equipped with an oxidation water inlet, a first pure water inlet, a second pure water inlet, a cooling oxidation water outlet, a first high-temperature steam outlet, and a first liquid pure water outlet. The oxidation water and pure water in the steam generator exchange heat. The pure water is heated and pressurized to generate high-temperature steam, and the oxidation water is cooled. The first pure water inlet is connected to external cold pure water. The oxidation water outlet is connected to the oxidation water inlet of the steam generator; The vapor-liquid separator is provided with a first high-temperature steam inlet, a second liquid pure water outlet, and a second high-temperature steam outlet; the first high-temperature steam inlet is connected to the first high-temperature steam outlet of the steam generator. The falling film circulation pump is equipped with a liquid pure water inlet, and the first liquid pure water outlet of the steam generator and the second liquid pure water outlet of the vapor-liquid separator are both connected to the liquid pure water inlet; the outlet of the falling film circulation pump is connected to the second pure water inlet of the steam generator. The steam-water mixer is equipped with a second high-temperature steam inlet and a raw water inlet, which mixes the high-temperature steam and raw water to preheat the raw water; The second high-temperature steam inlet is connected to the second high-temperature steam outlet of the vapor-liquid separator; The raw water inlet is connected to the raw water pipeline; The steam-water mixer is equipped with a mixed raw water outlet, and the pre-oxidation tower is equipped with a mixed raw water inlet and a pre-oxidized water outlet. The mixed raw water outlet is connected to the mixed raw water inlet. The pre-oxidized water outlet is connected to the wastewater inlet of the oxidation tower via a booster pump.

2. The catalytic wet oxidation reaction system as described in claim 1, characterized in that... The gas-liquid separator is used to separate the cooled oxidized water into liquid water and waste gas. The gas-liquid separator is equipped with a cooling oxidized water inlet, a tail gas outlet and a treated water discharge outlet. The cooling oxidized water inlet is connected to the cooling oxidized water outlet of the steam generator, and the tail gas outlet is connected to the absorption tower.

3. The catalytic wet oxidation reaction system as described in claim 1, characterized in that... The second high-temperature steam outlet is divided into two paths: one path is connected to the second high-temperature steam inlet, and the other path is connected to an external steam pipeline.

4. The catalytic wet oxidation reaction system as described in claim 3, characterized in that... A valve for controlling the flow rate of high-temperature steam is installed before the second high-temperature steam inlet.

5. The catalytic wet oxidation reaction system as described in claim 1, characterized in that... The oxidation tower is equipped with an oxygen inlet and is connected to an oxygen tank.

6. The catalytic wet oxidation reaction system as described in claim 1, characterized in that... The oxidation tower is equipped with a temperature sensor and an electric heating device to control the reaction temperature inside the oxidation tower.

7. The catalytic wet oxidation reaction system as described in claim 1, characterized in that... The oxidation tower is equipped with a catalyst inlet, and the catalyst storage tank is connected to the catalyst inlet through a catalyst metering pump to control the amount of catalyst used in the tower.

8. The catalytic wet oxidation reaction system as described in claim 1, characterized in that... The steam generator includes a heat exchange section and a water vapor separation section located below the heat exchange section. The heat exchange section is provided with a pure water pipeline and an oxidation water pipeline. A first pure water inlet and a second pure water inlet are located at the top of the heat exchange section of the steam generator and are connected to the pure water pipeline inlet. The pure water pipeline outlet is located at the bottom of the heat exchange section and is connected to the water vapor separation section. The oxidation water inlet is located at the upper part of the heat exchange section of the steam generator and is connected to the oxidation water pipeline inlet. The oxidation water pipeline outlet is the cooling oxidation water outlet, located at the lower part of the heat exchange section of the steam generator. The pure water pipeline and the oxidation water pipeline are in the same direction and exchange heat in the heat exchange section of the steam generator. The oxidation water is cooled to obtain cooled oxidation water, and the pure water is heated and pressurized to generate high-temperature steam, which enters the water-steam separation section from the outlet of the pure water pipeline. The first high-temperature steam outlet is located in the upper part of the water-vapor separation section, and the first liquid pure water outlet is located at the bottom of the water-vapor separation section.

9. The catalytic wet oxidation reaction system as described in claim 1, characterized in that... The system includes a raw water feed pump, and the raw water pipeline is connected to the raw water inlet of the steam-water mixer through the raw water feed pump.

10. The catalytic wet oxidation reaction system according to claim 1, characterized in that... The vapor-liquid separator is equipped with a pressure gauge and valves to regulate and control the vapor pressure inside the separator.

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