Fluidized bed supercritical water oxidation treatment device and method

Abstract

The present invention discloses a fluidized bed type supercritical water oxidation treatment device and method. The device comprises: a fluidized bed reactor and an online dosing system; the fluidized bed reactor comprises a straight section and an expanded section located above the straight section, the straight section and the expanded section are connected by a transition section; the inner wall of the straight section is covered with an inner lining layer, and micropores are arranged on the inner lining layer. The online dosing system comprises a dosing tank and a dosing tank, the dosing tank is respectively connected to the bottom of the fluidized bed reactor and the liquid product outlet of the fluidized bed reactor, and the dosing tank is respectively connected to the oxidant pipeline and the straight section of the fluidized bed reactor. The present invention can effectively avoid the adhesion and deposition of salt substances on the wall of the vessel and the like through the design of the fluidized bed reactor and the online dosing system, and significantly prolong the service life of the device.

Description

Technical Field

[0001] The invention belongs to the field of environmental protection and chemical industry, and specifically relates to a treatment method for eliminating organic matter and inorganic salts in polluted wastewater. Background Art

[0002] Supercritical water oxidation technology (SCWO) uses supercritical water as the reaction medium. In the presence of oxidants (such as oxygen, air or hydrogen peroxide, etc.), organic matter is oxidized and decomposed into CO2, H2O, N2 and other harmless small molecules through free radical reactions under high temperature and high pressure. The advantages of SCWO in treating organic waste include: high organic pollutant removal rate (usually greater than 99%) and thorough decomposition; inorganic salts have extremely low solubility in supercritical water and are easy to separate; the oxidation reaction is a homogeneous reaction with a fast reaction speed, a residence time generally not exceeding 1 minute, and high treatment efficiency; the reaction system is completely closed and there is no secondary pollution; the reaction is an exothermic reaction, and self-heating can be achieved in the case of low organic matter concentration, saving energy.

[0003] However, the commercialization of this technology is limited by two major problems: reactor corrosion and blockage caused by salt precipitation. On the one hand, the sources of high-concentration saline wastewater are diverse. In addition to organic matter such as alkanes, aromatic hydrocarbons, and lipids, wastewater usually contains a large amount of chlorides, sulfides, etc. These chlorides and sulfides are easy to form HCL and H2SO4 during the treatment process, and generate hydrochloric acid and sulfuric acid when they come into contact with water, causing serious corrosion to the equipment; on the other hand, during the supercritical oxidation treatment of high-salt organic wastewater, the solubility of inorganic salts is reduced, causing salts to precipitate and crystallize, and continuously deposit on the inner surface of the reactor, increasing the reactor pressure drop and worsening the heat transfer, which eventually leads to reactor blockage, seriously affecting the reliability and economy of the SCWO device. The superposition of multiple factors has caused the current SCWO devices to generally have a short operating time, and most of them are intermittent operation, which has brought difficulties to the large-scale treatment of high-concentration saline wastewater, and also brought inconvenience to the promotion and application of supercritical water oxidation technology.

[0004] In response to the situation where salt substances precipitate under supercritical conditions and cause reactor blockage and corrosion, the industry has developed different types of reactor structures, mainly the following: 1) Countercurrent kettle reactor, the upper part of the reactor is the supercritical zone in the vertical direction, and the lower part is the subcritical zone. The salt precipitated under supercritical conditions relies on gravity, inertia and other effects to settle to the subcritical zone at the bottom of the reactor and dissolve again, and then is discharged from the bottom outlet of the reactor. The desalinated reaction fluid flows out from the top outlet of the reactor in a countercurrent, thereby achieving the purpose of desalination in the reactor. However, due to the low sedimentation rate of fine-grained salt and the strong vertical disturbance in the reactor, the salt may agglomerate in the supercritical zone at the top of the reactor; 2) Centrifugal reactor. The feed is injected into a high-speed centrifuge, which rotates at high speed to generate supercritical pressure, and then is heated to a supercritical state. The oxidant is injected and the reaction begins, and the salt generated by the reaction or the salt originally contained in the feed is separated by centrifugation. This type of reactor is not conducive to the rapid and uniform mixing and reaction of the feed. If the components (water, materials, oxidants, fuel) are not fully preheated or are mixed after being preheated separately, the concentration distribution will be uneven, and it will be difficult to achieve uniform mixing of the feed in the rotating centrifugal reactor, which will inhibit the homogeneous reaction and cause incomplete oxidation reaction.

[0005] Patent CN108862698A introduces a fluidized bed reaction system for supercritical water oxidation of high-concentration and high-salt organic wastewater. High-concentration and high-salt organic wastewater contacts air and catalyst in a fluidized bed reactor to undergo supercritical water oxidation reaction. The logistics is fluidized under the action of supercritical fluid, and then the gas-solid and solid-liquid separation of the reacted fluid is carried out by means of a combination of a high-temperature cyclone separator, a return valve and a hydrocyclone. This patent application uses a solid particle catalyst. The key to the solid particle catalyst to function is to have sufficient contact area with the reaction material. This patent application does not take into account the adverse effects of inorganic salt precipitation and deposition on the catalyst surface on the reaction effect; in addition, in terms of online operation of the fluidized bed reactor, the fluidized bed technology is similar to the suspended bed technology. The catalyst and inorganic salt need to flow out of the reactor together with the reaction fluid. A combination of a cyclone separator, a hydrocyclone and multiple blowers is adopted to realize the catalyst backfilling to the reactor. The process is complicated and the energy consumption is high.

[0006] Regarding corrosion prevention, the document "Research Progress in Treatment of Industrial Wastewater by Supercritical Water Oxidation Technology" published by Liu Chunming et al. introduces an evaporation wall reactor. The reactor consists of a pressure-bearing wall and a porous evaporation wall. Clean water is pumped into the interlayer to form a protective water film on the inner surface of the porous evaporation wall, which flushes, dilutes or dissolves the salt particles precipitated under supercritical conditions, thereby preventing salt from depositing on the inner wall of the reactor and solving the problem of engineering blockage caused by salt deposition. At the same time, corrosive substances can be prevented from contacting the inner wall of the reactor, reducing the corrosion rate of the reactor. However, the introduction of evaporation wall water will reduce the temperature of the reaction fluid, dilute the reaction fluid, have a significant impact on the reaction temperature and reaction temperature, reduce the processing capacity of the reactor, and lead to low energy recovery efficiency of the system; in addition, the introduction of clean water will increase the amount of sewage treatment, increase the treatment cost of the device, and the energy consumption of the whole process is relatively high. Summary of the invention

[0007] At present, when supercritical water oxidation technology is used to treat high-concentration saline wastewater, there are problems such as solid salts precipitated causing blockage of the reactor wall or pipeline, and equipment corrosion during the removal of heteroatoms such as Cl, S and other compounds in the wastewater, as well as complex processes and high energy consumption in returning the regenerated catalyst to the reactor. In view of the above problems, the present invention aims to provide a device and a treatment process to avoid the deposition and blockage of salt substances on the reactor wall, and to overcome the corrosion problem of the reactor wall during the oxidation of organic matter such as sulfur and chlorine. At the same time, low-cost continuous operation is achieved.

[0008] To achieve the above-mentioned object, the first aspect of the present invention is to provide a fluidized bed supercritical water oxidation treatment device, comprising a fluidized bed reactor and an online dosing system; wherein:

[0009] The fluidized bed reactor comprises a straight section and an expansion section located above the straight section, and the straight section and the expansion section are connected by a transition section; an inner lining layer is covered on the inner wall of the straight section, and micropores are arranged on the inner lining layer;

[0010] The online dosing system includes a dosing tank and a dosing tank. The dosing tank is connected to the bottom of the fluidized bed reactor and the liquid product outlet of the fluidized bed reactor respectively, and the dosing tank is connected to the oxidant pipeline and the straight section of the fluidized bed reactor respectively.

[0011] Furthermore, in the above technical solution, the inner lining layer covers the inner wall of the straight tube section, the thickness of the inner lining layer is 1.5-2.5 mm, and the gap between the inner lining layer and the inner wall of the straight tube section is 1.0-1.5 mm. The inner lining layer can be made of any suitable material such as one or more of a ceramic film, a common alloy material, a stainless steel material, etc.

[0012] Furthermore, in the above technical solution, the size of the micropores ranges from 10 to 1000 μm, preferably from 50 to 500 μm.

[0013] Furthermore, in the above technical solution, the ratio of the height of the straight tube section to the height of the enlarged section is 8:1 to 10:1.

[0014] Furthermore, in the above technical solution, the angle between the outer wall of the transition section and the horizontal line is 30-60°, and the vertical height of the transition section accounts for 5%-8% of the total height of the straight tube section.

[0015] Furthermore, in the above technical solution, a dense phase reaction zone is provided at the lower part of the straight tube section, and a dilute phase reaction zone is provided at the upper middle part. The dense phase reaction zone accounts for 60% to 80% of the straight tube section, and the rest is the dilute phase reaction zone.

[0016] Furthermore, in the above technical solution, the dense phase reaction zone is filled with fillers and / or adsorbents, preferably large particles of high pore volume fillers and / or adsorbents, and the dilute phase reaction zone is filled with catalysts with denitrification function. The fillers and / or adsorbents have a particle size range of 1.0 to 2.0 mm, and the denitrification catalyst has a particle size range of 0.8 to 1.5 mm.

[0017] Furthermore, in the above technical solution, a gas-liquid redistribution plate is arranged between the dense phase reaction zone and the dilute phase reaction zone, and a distributor is arranged on the distribution plate. The distributor has a non-return function, which can ensure that the catalyst in the dilute phase zone will not fall into the dense phase zone on the one hand, and can also realize gas-liquid redistribution on the other hand.

[0018] Furthermore, in the above technical solution, a baffle and an umbrella-shaped guide internal part are arranged in the expanded section, the baffle is arranged parallel to the inner wall of the expanded section, and the space restricted by the baffle and the inner wall of the expanded section is the guide section; the umbrella-shaped guide internal part is arranged in a non-contact manner above the baffle.

[0019] Furthermore, in the above technical solution, the baffle is designed to be cylindrical, forming an inner sleeve; the inner diameters of the straight section, the enlarged section, the inner sleeve and the umbrella-shaped guide inner part are respectively recorded as D1, D4, D2 and D3, wherein D4 = 1.5D1 ~ 1.6D1,

[0020] D2=1.2D1~1.3D1, D3=1.3D1~1.4D1.

[0021] Furthermore, in the above technical solution, the filler is a porous material, which can be activated carbon or other porous materials. The appearance of the adsorbent such as activated carbon can be spherical, elongated, clover-shaped, four-leaf clover-shaped or other irregular shapes. The adsorbent is required to have a certain pore size and pore size distribution, including macropores (>

[0022] The pores are of three forms: pores with a pore size of 100 nm or more, transitional pores (100-200 nm) and micropores (<100 nm). The pore volume of pores with a pore size of 100 nm or more accounts for more than 85% of the total pore volume, and the pore volume of pores with a pore size of <100 nm accounts for less than 15% of the total pore volume. The adsorbent filled in the dense phase region has a large pore volume and pore size. The salt substances precipitated due to the reduction of solubility in the supercritical state enter the pores of the adsorbent or adhere to the surface of the adsorbent, avoiding the deposition of salt substances on the reactor wall and covering interference with the catalyst in the dilute phase region.

[0023] Furthermore, in the above technical solution, the denitrification conversion catalyst uses manganese and cerium as the main active components, wherein the molar ratio of manganese to cerium in terms of elements is 1:0.5 to 1:2. The active metal can be prepared according to different molar ratios of manganese and cerium, and the coprecipitation method is adopted. The specific method is as follows: Mn(NO3)2 and Ce(NO3)3.6H2O are prepared into a mixed solution in a certain proportion, and ammonia water is used as a precipitant. The coprecipitation reaction is carried out under the condition of parallel feeding at 60 to 120°C. The mother liquor is aged for 2 to 5 hours, and the supernatant is discarded. The precipitate is washed three times with deionized water, and the precipitate is filtered and the precipitate is heated at 100°C.

[0024] The mixture is dried at 120°C for 4h to 6h, calcined at 550°C to 600°C for 2h to 4h, and the final powder is tableted, ground and formed at 25MPa to 35MPa.

[0025] Furthermore, in the above technical scheme, fresh (or regenerated) adsorbent or catalyst addition ports are provided at the top of the fluidized bed reactor and the top distribution plate of the dense phase zone of the reactor, and adsorbent or catalyst unloading ports are provided at the bottom of the fluidized bed reactor and the bottom distribution plate of the dilute phase zone inside the reactor. When the adsorbent or catalyst in the fluidized bed reactor reaches a certain limit of its own carrying capacity or activity, the specific carrying capacity range is 30% to 80%, and the preferred range is: 50% to 70%, the adsorbent or catalyst is unloaded through the unloading port, and then the subcritical state purified sewage obtained by heat exchange and decompression is introduced to dissolve the salts on the adsorbent to obtain high-concentration salts and regenerated fillers.

[0026] The second aspect of the present invention is to provide a fluidized bed supercritical water oxidation treatment method, comprising the following steps:

[0027] 1) Salt-containing wastewater enters the reactor through the bottom of the fluidized bed reactor, and the gas-phase oxidant is divided into three routes, namely, oxidant 1, oxidant 2 and oxidant 3, wherein oxidant 1 is mixed with salt-containing wastewater and enters the reactor through the bottom of the fluidized bed reactor, oxidant 2 enters the fluidized bed reactor through the micropores on the inner lining of the fluidized bed reactor, and oxidant 3 enters the unloading tank as a transport power for regenerated or fresh adsorbent and / or filler;

[0028] 2) The salt-containing wastewater and the gas-phase oxidant undergo salt precipitation and organic matter oxidation and impurity removal reactions in the reactor under supercritical water oxidation conditions in the presence of an adsorbent and / or filler and a catalyst, and the purified wastewater and gas are discharged from the reactor from the top of the reactor as supercritical water oxidation reaction effluents;

[0029] 3) When the carrying capacity of the adsorbent and / or filler in step 2) cannot meet the production requirements, online unloading and adding operations are performed, and the adsorbent and / or filler that needs to be unloaded is unloaded into the unloading tank, and the fresh or regenerated adsorbent and / or filler enters the fluidized bed reactor through the adding tank to continue the reaction.

[0030] Furthermore, in the above technical scheme, the supercritical water oxidation conditions in step 2) are: reaction temperature 450-600°C, reaction pressure 24-30MPa, volume ratio of saline wastewater to oxidant one 1:300-1:1500, residence time 30-250s, and preferred supercritical water oxidation conditions are: reaction temperature 500-550°C, reaction pressure 25-27MPa, volume ratio of saline wastewater to oxidant one 1:500-1:1200, residence time 50-200s.

[0031] Furthermore, in the above technical solution, the saline wastewater and the oxidant are heat exchanged in a heat exchanger and heated in a mixed phase furnace before entering the reactor. The saline wastewater is preferably heat exchanged with the liquid phase effluent of the supercritical water oxidation reaction. The oxidant, such as air or oxygen, is pressurized by a booster pump and enters a gas phase heat exchanger to exchange heat with the gas phase after the supercritical water oxidation reaction.

[0032] Furthermore, in the above technical solution, the distribution ratio of oxidant 1 to oxidant 2 is 10:1 to 1:1, preferably 4:1 to 1:1. The volume ratio of oxidant 3 to supplementary adsorbent or catalyst is 300:1 to 1500:1, preferably 500:1 to 800:1.

[0033] Furthermore, in the above technical solution, the pressure of the salt-containing wastewater and the oxidant 1 before entering the reactor is not less than 22.1MPa, preferably 24-30MPa; the temperature is not higher than 374°C, preferably 250-350°C. The gas phase pressure of the oxidant 2 entering the gap between the inner wall and the inner lining of the reactor is slightly higher than the pressure inside the reactor; the difference between the gas phase pressure in the gap and the pressure inside the reactor is determined by the pressure drop on the gas-liquid mixed phase pipeline after the heating furnace and the pressure drop at the distributor at the bottom of the fluidized bed reactor.

[0034] Furthermore, in the above technical solution, the difference between the gas phase pressure in the gap between the inner wall of the reactor and the inner liner and the pressure inside the reactor is generally not less than 0.5 MPa. Under the action of the pressure difference, the gas phase penetrates into the reactor cavity through the micropores on the inner liner. The micropores on the inner liner are small in size and densely arranged, and a gas phase film or cushion layer is formed on the inner side of the inner liner, isolating the reaction products in the reactor from contacting the reactor inner liner or even the inner wall, thereby preventing the reaction products from corroding the equipment.

[0035] Furthermore, in the above technical solution, the saline wastewater described in step 2) can come from the petroleum refining process or other fields such as coal chemical wastewater and printing and dyeing industry wastewater. The wastewater can contain salts such as NaCl, KCl, Na2SO4, K2SO4, and organic matter such as lipids, aromatic hydrocarbons, alkanes, etc. The organic matter concentration in the raw material saline wastewater is 1.0wt% to 10wt%, and the preferred concentration range is 3.0wt% to 7.0wt%.

[0036] Furthermore, in the above technical solution, the salt-containing wastewater and the gas-phase oxidant in step 2) pass through the dense phase reaction zone and the dilute phase reaction zone of the bed layer of the fluidized bed reactor in sequence, and salt precipitation and organic matter oxidation and impurity removal reactions occur in sequence. The purified wastewater and gas are guided by the top guide structure of the fluidized bed reactor and exit the reactor from the liquid phase extraction port and the gas phase extraction port respectively; the catalyst and the adsorbent are retained in the reactor and continue to participate in the salt precipitation and denitrification oxidation reaction.

[0037] Furthermore, in the above technical solution, the oxidant described in step 1) can be air, oxygen, or other oxidants such as H2O2, etc., preferably air.

[0038] Furthermore, in the above technical solution, the carrying capacity of the adsorbent and / or filler in step 3) cannot meet the production requirements, which means: controlling the carrying capacity of the adsorbent and / or filler and the catalyst in the fluidized bed reactor, when the carrying capacity reaches 50% to 70% and cannot meet the production requirements, starting online unloading, regeneration and online replenishment operations. While achieving the stability of the activity of the adsorbent and catalyst in the fluidized bed reactor, ensure the long-term stable operation of the device.

[0039] Furthermore, in the above technical scheme, clean water or the liquid effluent of the supercritical water oxidation reaction after heat exchange with the saline wastewater is introduced into the unloading tank of step 3) to dissolve the salts deposited on the adsorbent and / or filler, thereby obtaining concentrated saline wastewater and regenerated adsorbent and / or filler, and the concentrated saline wastewater is discharged.

[0040] Furthermore, in the above technical solution, the adsorbent or catalyst is supplemented by a dosing tank. The regenerated or fresh adsorbent or catalyst is first transported from the storage tank to the dosing tank, and then the dosing tank is pressurized with the fresh oxidant after heat exchange and pressurization. When the pressure of the dosing tank reaches 0.5-1.0MPa higher than that of the fluidized bed reactor, the control valve between the dosing tank and the fluidized bed reactor is opened, and the adsorbent or catalyst enters the corresponding reaction zone of the fluidized bed reactor to participate in the reaction under the action of the pressure difference.

[0041] Furthermore, in the above technical solution, when online supplementation is performed to the fluidized bed reactor, the mixing ratio of the regeneration agent to the fresh agent is 1:2 to 1:10, preferably 1:4 to 1:8.

[0042] Furthermore, in the above technical solution, a gas delivery method is adopted when online replenishment is carried out to the fluidized bed reactor, and fresh oxidant gas after heat exchange and pressurization is introduced as the delivery power. The pressure difference between the fresh oxidant gas and the internal pressure of the reactor is controlled to be 0.3-1.0 MPa, preferably 0.5-0.8 MPa.

[0043] Advantages of the present invention:

[0044] 1. Aiming at the serious acid corrosion problem of the equipment in the process of supercritical oxidation treatment of traditional high-concentration saline wastewater, the present invention provides a low-cost and efficient reactor protection form. By setting an air or oxygen gap layer on the inner wall of the reactor, the contact between the corrosive substances and the inner wall is isolated. It can play a good protective role without increasing energy consumption, reducing the cost of reactor production and significantly extending the service life of the device;

[0045] 2. In view of the problem of catalyst deactivation caused by salt deposition on the catalyst surface in the traditional supercritical oxidation reaction system, the present invention sets a dense phase reaction zone and a dilute phase reaction zone in the fluidized bed reactor, wherein the dense phase reaction zone provides an area for salt deposition, and the dilute phase reaction zone provides a reaction space for removing impurities. The dense phase reaction zone intercepts high-salt substances and purifies the feed of the dilute phase reaction zone, providing a prerequisite for the activity of the catalyst;

[0046] 3. In view of the serious problem of salt deposition in traditional supercritical oxidation reaction systems, the method of the present invention arranges large-particle, high-pore-volume adsorbents in the dense phase reaction zone, which can serve as crystallization nuclei for salt deposition, provide attachment points for salt deposition and growth, avoid the attachment and deposition of salt substances on the wall of the device, etc., and help to extend the long-term operation of equipment such as reactors.

[0047] 4. Traditional supercritical oxidation treatment devices for high-concentration saline wastewater are mainly intermittently operated or short-term operated, which cannot meet the requirements of long-term large-scale treatment of the device. The patent of this invention changes the process settings and controls the carrying capacity of the adsorbent and / or filler in the reactor to set up an online addition and discharge process. That is, when the adsorbent and / or filler and catalyst in the reactor reach the carrying requirements, the online addition and unloading process is started to ensure continuous online operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of an implementation of the fluidized bed supercritical water oxidation treatment device and method of the present invention.

[0049] 1 buffer tank, 2 fresh oxidant, 3 liquid phase heat exchanger, 4 gas phase heat exchanger, 5 liquid phase heating furnace, 6 gas phase heating furnace, 7 oxidant 1, 8 oxidant 2, 9 mixed material, 10 dense phase reaction zone, 11 dilute phase reaction zone, 12 fluidized bed liquid phase product, 13 fluidized bed gas phase product, 14 subcritical purified water, 15 adsorbent or catalyst reaching carrying capacity, 16 unloading tank, 17 regenerated adsorbent, 18 salty sewage, 19 discharged wastewater, 20 oxidant 3, 21 fresh adsorbent, 22 dosing tank DETAILED DESCRIPTION

[0050] The present invention is further described below through specific implementation modes, but the protection scope of the present invention is not limited thereto.

[0051] like Figure 1 As shown, the fluidized bed supercritical water oxidation treatment reactor of the present invention comprises a straight section and an expanded section, wherein the lower end and the middle upper part of the straight section are respectively provided with a dense phase reaction zone 10 and a dilute phase reaction zone 11, the area from the bottom of the fluidized reactor to 60% to 80% of the height of the straight section is defined as the dense phase reaction zone, and the remaining space of the straight section is the dilute phase reaction zone. A baffle and an umbrella-shaped flow guide inner part are arranged in the expanded section, the baffle is arranged parallel to the inner wall of the expanded section, and the space restricted by the baffle and the inner wall of the expanded section is the flow guide section; the umbrella-shaped flow guide inner part is arranged above the baffle in a non-contact manner; a gas phase extraction port and a liquid phase extraction port are arranged at the top of the reactor for extracting the fluidized bed gas phase product 13 and the fluidized bed liquid phase product 12. The baffle is a cylindrical structure, forming an inner sleeve, wherein the inner diameters of the inner sleeve and the umbrella-shaped flow guide inner part formed by the straight section, the enlarged section, the baffle are respectively recorded as D1, D4, D2 and D3, wherein the relationship D4 = 1.5D1, D2 = 1.2D1, D3 = 1.3D1. There is a transition section between the straight section and the enlarged section, the angle between the outer wall of the transition section and the horizontal line is 45°, and the vertical height of the transition section accounts for 6% of the height of the straight section.

[0052] like Figure 1 As shown, the supercritical water oxidation treatment method of the present invention includes the following contents:

[0053] High-concentration salt-containing wastewater is transferred from the buffer tank 1 through a high-pressure feed pump and respectively passes through the liquid phase heat exchanger 3 to exchange heat with the liquid phase reaction product of the fluidized bed, and then heated by the liquid phase heating furnace 5. Part of the liquid phase product after heat exchange is discharged from the device as external wastewater 19, and part enters the unloading tank 16 as washing water. The fresh oxidant 2 is pressurized by the compressor and passes through the gas phase heat exchanger 4 to exchange heat with the gas phase product 13 of the fluidized bed, and then heated by the gas phase heating furnace 6. One gas phase (oxidant 2 8) directly enters the jacket on the inner wall of the reactor through the micropores on the side wall of the fluidized bed reactor, and gas is injected into the inside of the reactor through the micropores on the jacket to form an air cushion layer on the inside of the reactor. Another gas phase (oxidant 3) 20 enters the catalyst unloading tank and carries the regenerated adsorbent into the dosing tank 22; the third gas phase (oxidant 1 7) is evenly mixed with the heated liquid phase material through a pipeline mixer to obtain a mixed material 9, which enters the fluidized bed reactor from the bottom of the reactor. Supercritical water oxidation reaction is carried out in the dense phase reaction zone 10 and the dilute phase reaction zone 11 respectively to precipitate salts and organic matter. The fluidized bed gas phase product 13 and the fluidized bed liquid phase product 12 are heat exchanged with the corresponding fresh feed respectively. The adsorbent or catalyst 15 that reaches the carrying capacity enters the corresponding unloading tank 16, and then a subcritical purified water 14 after heat exchange is introduced for dissolution to obtain high-concentration salt-containing sewage 18 and regenerated adsorbent 17. The regenerated adsorbent 17 enters the dosing tank 22 under the carrying action of the gas phase oxidant, is mixed with a certain proportion of fresh adsorbent 21, and enters the fluidized bed reactor under the action of pressure difference to continue the reaction.

[0054] The adsorbent used in the fluidized bed reactor in the embodiments and comparative examples of the present invention is high specific surface area activated carbon, the impurity removal catalyst is a catalyst with manganese cerium as the active component, wherein the activated carbon particles have a four-leaf clover shape, the particle equivalent direct range is 1.3-1.7 mm, wherein macropores (>200 nm) account for 55%, mesopores (100-200 nm) account for 35%, and micropores (<100 nm) account for 10%; the denitrification catalyst uses manganese cerium as the main active component, and the active metal solution is prepared according to the molar ratio of manganese to cerium of 5:5, and is prepared by the co-precipitation method commonly used in the industry, using ammonia water as a precipitant, and Mn(NO3)2 and Ce(N O3)3.6H2O are prepared into a mixed solution in a certain proportion (converted according to the metal molar ratio of 4:6), and a co-precipitation reaction is carried out under the condition of parallel feeding at 95°C. The mother liquor is aged for 3.0 hours and the supernatant is discarded. The precipitate is washed three times with deionized water, and the precipitate is filtered and dried at 108°C for 5.0 hours and calcined at 535°C for 2.3 hours. The final powder is pressed and ground at 28MPa to prepare a toothed spherical shape with an equivalent particle size range of 1.2 to 1.4mm (wherein the main particle size with an equivalent diameter of 1.2 to 1.4mm accounts for >80%, and the catalyst with an equivalent diameter of <1.0mm and >1.4mm accounts for <20%).

[0055] In the embodiments and comparative examples of the present invention, in order to reflect the effects of different technical solutions, printing and dyeing wastewater and coal chemical wastewater are mixed in a certain proportion, and the reactor materials of the comparative example and the embodiment are exactly the same. The specific properties of the organic wastewater are shown in Table 1, and air is used as the oxidant.

[0056] Table 1 Properties of organic mixed wastewater

[0057]

[0058] Example 1

[0059] Example 1 The organic mixed wastewater listed in Table 1 is used as raw material, and the fluidized bed supercritical water oxidation reactor described in the present invention is adopted. The separation point of the dense phase reaction zone and the dilute phase reaction zone is 65% of the straight tube section distance from the inlet of the fluidized bed reactor. The dense phase reaction zone is filled with activated carbon adsorbent, and the dilute phase reaction zone is filled with manganese cerium catalyst. The pressure before the salt-containing wastewater and the oxidant enter the reactor is 26MPa and the temperature is 260°C. The inner wall of the reactor is provided with an inner lining layer composed of a ceramic membrane, and micropores are provided on the inner lining layer. The thickness of the inner lining layer is 1.5mm, and the gap range between the inner lining layer and the inner wall of the straight tube section is 1.0mm. The size of the micropore is 500μm, and an online dosing and discharge system is provided.

[0060] The operating conditions of the supercritical oxidation reactor are: reaction temperature 515°C, reaction pressure 25.0 MPa, volume ratio of sewage to oxidant 1 1:800, residence time 50 s. See Table 2 for specific reaction results.

[0061] Example 2

[0062] Example 1: The organic wastewater listed in Table 1 is used as raw material, and the fluidized bed supercritical water oxidation reactor described in the present invention is adopted. The separation point between the dense phase reaction zone and the dilute phase reaction zone is 65% of the straight tube section distance from the inlet of the fluidized bed reactor. The dense phase reaction zone is filled with activated carbon adsorbent, and the inner wall of the reactor is provided with an inner lining layer made of stainless steel material, and micropores are provided on the inner lining layer. The thickness of the inner lining layer is 1.5mm, the gap range between the inner lining layer and the inner wall of the straight tube section is 1.0mm, and the size of the micropores is 100μm. The dilute phase reaction zone is filled with manganese cerium catalyst. The pressure before the salt-containing wastewater and the oxidant enter the reactor is 30MPa and the temperature is 350℃, and an online dosing and discharge system is set.

[0063] The operating conditions of the supercritical oxidation reactor are: reaction temperature 525°C, reaction pressure 26.5MPa, volume ratio of sewage to oxidant 1 1:1100, residence time 100s. See Table 2 for specific reaction results.

[0064] Example 3

[0065] The same as Example 1, except that the inner diameters of the straight section, the enlarged section, the inner sleeve and the umbrella-shaped flow guide inner member in the fluidized bed reactor are D4=1.6D1, D2=1.25D1, and D3=1.35D1. The angle between the outer wall of the transition section and the horizontal line is 60°, and the vertical height of the transition section is 6% of the height of the straight section.

[0066] Example 4

[0067] Same as Example 1, except that the thickness of the inner lining layer is 2.5 mm, the gap between the inner lining layer and the inner wall of the straight tube section is 1.5 mm, and other conditions are the same as Example 1, wherein the ratio of oxidant 1 to oxidant 2 is 5:1, and the vertical height of the transition section is 8% of the height of the straight tube section. Other conditions are the same as Example 1.

[0068] Comparative Example 1

[0069] Comparative Example 1 The organic wastewater listed in Table 1 was used as raw material, and a conventional trickle bed supercritical water oxidation reactor was used. The reactor was not partitioned and only loaded with a manganese-cerium catalyst. There was no air cushion layer on the inner wall of the reactor, and there was no online dosing system. The operating conditions of the supercritical oxidation reactor were: reaction temperature 515°C, reaction pressure 25.0MPa, volume ratio of sewage to oxidant 1:800, and residence time 50s. See Table 2 for specific reaction results.

[0070] Comparative Example 2

[0071] Comparative Example 2 The organic wastewater listed in Table 1 is used as a raw material, and the fluidized bed supercritical water oxidation reactor of the present invention is used. The reactor is not partitioned, and a mixed catalyst of an adsorbent and a manganese-cerium catalyst is loaded. The inner wall of the reactor is not provided with an air cushion layer, and there is no online dosing system. The operating conditions of the supercritical oxidation reactor are the same as those of Example 2, namely: reaction temperature 525°C, reaction pressure 26.5Mpa, volume ratio of sewage to oxidant 1:1100, and residence time 100s. See Table 2 for specific reaction results.

[0072] Table 2 Reaction effects of different embodiments and comparative examples

[0073]

[0074] Through the comparison results of the above embodiments and comparative examples, it can be found that the fluidized bed type supercritical water oxidation reactor containing an air cushion layer lining described in the present invention is significantly superior to the traditional supercritical water oxidation reactor without a liner in terms of device operation cycle, denitrification rate, inner wall corrosion resistance, etc., and the fluidized bed type supercritical water oxidation reactor containing an air cushion layer lining described in the present invention has a simple structure and low production cost, and is a good technical means for supercritical oxidation treatment of high-concentration wastewater. In addition, the setting of the continuous online dosing system can ensure the long-term stable operation of the device and realize batch treatment of high-concentration organic wastewater.

Claims

1. A fluidized bed supercritical water oxidation treatment device, characterized in that: It includes a fluidized bed reactor and an online dosing system; wherein: The fluidized bed reactor comprises a straight section and an expansion section located above the straight section, and the straight section and the expansion section are connected by a transition section; an inner lining layer is covered on the inner wall of the straight section, and micropores are arranged on the inner lining layer; a dense phase reaction zone is arranged in the middle and lower part of the straight section, and a dilute phase reaction zone is arranged in the upper part; wherein the dense phase reaction zone is filled with fillers and / or adsorbents, and the dilute phase reaction zone is filled with catalysts having a denitrification function; The online dosing system includes a dosing tank and a dosing tank. The dosing tank is connected to the bottom of the fluidized bed reactor and the liquid product outlet of the fluidized bed reactor respectively, and the dosing tank is connected to the oxidant pipeline and the straight section of the fluidized bed reactor respectively.

2. The device according to claim 1, characterized in that The inner lining layer covers the inner wall of the straight tube section, the thickness of the inner lining layer is 1.5-2.5 mm, and the gap between the inner lining layer and the inner wall of the straight tube section is 1.0-1.5 mm.

3. The device according to claim 1, characterized in that The size of the micropores ranges from 10 to 1000 μm.

4. The device according to claim 1, characterized in that The ratio of the height of the straight tube section to the height of the enlarged section is 8:1 to 10:

1.

5. The device according to claim 1, characterized in that The angle between the outer wall of the transition section and the horizontal line is 30-60 degrees, and the vertical height of the transition section accounts for 5%-8% of the total height of the straight tube section.

6. The device according to claim 1, characterized in that The dense phase reaction zone accounts for 60% to 80% of the straight tube section, and the rest is the dilute phase reaction zone.

7. The device according to claim 1, characterized in that The filler and / or adsorbent has a particle size range of 1.0 to 2.0 mm, and the catalyst having a denitrification function has a particle size range of 0.8 to 1.5 mm.

8. The device according to claim 6, characterized in that A gas-liquid redistribution plate is arranged between the dense phase reaction zone and the dilute phase reaction zone, and a distributor is arranged on the distribution plate. The distributor has a check function, which can ensure that the catalyst in the dilute phase zone will not fall into the dense phase zone on the one hand, and can also realize gas-liquid redistribution on the other hand.

9. The device according to claim 1, characterized in that A baffle and an umbrella-shaped guide inner part are arranged in the expansion section. The baffle is arranged parallel to the inner wall of the expansion section. The space restricted by the baffle and the inner wall of the expansion section is the guide section. The umbrella-shaped guide inner part is arranged above the baffle in a non-contact manner.

10. The device according to claim 9, characterized in that The deflector is designed to be cylindrical, forming an inner sleeve; the inner diameters of the straight section, the expanded section, the inner sleeve and the umbrella-shaped guide inner part are respectively recorded as D1, D4, D2 and D3, among which D4 = 1.5D1 ~ 1.6D1, D2 = 1.2D1 ~ 1.3D1, and D3 = 1.3D1 ~ 1.4D1.

11. A fluidized bed supercritical water oxidation treatment method using the device according to any one of claims 1 to 10, characterized in that: The steps include: 1) Salt-containing wastewater enters the reactor through the bottom of the fluidized bed reactor, and the gas-phase oxidant is divided into three routes, namely, oxidant 1, oxidant 2 and oxidant 3, wherein oxidant 1 is mixed with salt-containing wastewater and enters the reactor through the bottom of the fluidized bed reactor, oxidant 2 enters the fluidized bed reactor through the micropores on the inner lining of the fluidized bed reactor, and oxidant 3 enters the unloading tank as a transport power for regenerated or fresh adsorbent and / or filler; 2) The salt-containing wastewater and the gas-phase oxidant undergo salt precipitation and organic matter oxidation and impurity removal reactions in the reactor under supercritical water oxidation conditions in the presence of an adsorbent and / or filler and a catalyst, and the purified wastewater and gas are discharged from the reactor from the top of the reactor as supercritical water oxidation reaction effluents; 3) When the carrying capacity of the adsorbent and / or filler in step 2) cannot meet the production requirements, online unloading and adding operations are performed, and the adsorbent and / or filler that needs to be unloaded is unloaded into the unloading tank, and the fresh or regenerated adsorbent and / or filler enters the fluidized bed reactor through the adding tank to continue the reaction.

12. The method according to claim 11, characterized in that Step 2) The supercritical water oxidation conditions are: reaction temperature 450-600° C., reaction pressure 24-30 MPa, volume ratio of saline wastewater to oxidant 1 1:300-1:1500, residence time 30-250 s.

13. The method according to claim 11, characterized in that The pressure of the saline wastewater and the oxidant before entering the reactor is not less than 22.1MPa; the temperature is not higher than 374℃.

14. The method according to claim 11, characterized in that The difference between the gas phase pressure in the gap between the inner wall of the reactor and the inner lining layer and the pressure inside the reactor is not less than 0.5 MPa.

15. The method according to claim 11, characterized in that In step 2), the salt-containing wastewater and the gas-phase oxidant sequentially pass through the dense phase reaction zone and the dilute phase reaction zone of the fluidized bed reactor, and salt precipitation and organic matter oxidation and impurity removal reactions occur sequentially.

16. The method according to claim 11, characterized in that In step 3), the carrying capacity of the adsorbent and / or filler cannot meet the production requirements, which means: controlling the carrying capacity of the adsorbent and / or filler and the catalyst in the fluidized bed reactor, when the carrying capacity reaches 50% to 70% and cannot meet the production requirements, starting online unloading, regeneration and online replenishing operations.

17. The method according to claim 11, characterized in that Clean water or the liquid effluent of the supercritical water oxidation reaction after heat exchange with the saline wastewater is introduced into the unloading tank of step 3) to dissolve the salts deposited on the adsorbent and / or filler to obtain concentrated saline wastewater and regenerated adsorbent and / or filler, and the concentrated saline wastewater is discharged.

18. The method according to claim 16, characterized in that When online replenishment is carried out to the fluidized bed reactor, the mixing ratio of the regeneration agent to the fresh agent is 1:2 to 1:

10.

19. The method according to claim 16, characterized in that When online replenishment is carried out to the fluidized bed reactor, a gas delivery method is adopted, and fresh oxidant gas after heat exchange and pressurization is introduced as the delivery power. The pressure of the fresh oxidant gas is controlled to have a pressure difference of 0.3 to 1.0 MPa with respect to the internal pressure of the reactor.

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