Hydrothermal cracking liquid fertilizer concentration device and concentration method

Abstract

The invention discloses a concentration device and a concentration method for a hydrothermal cracking liquid fertilizer, belongs to the technical field of liquid fertilizer production, and aims to solve the problem of low concentration efficiency of the liquid fertilizer caused by application of an existing concentration device to liquid fertilizer concentration in the prior art. The concentration device comprises a preheating tank, a primary evaporation tank and a secondary evaporation tank which are sequentially connected in the flowing direction of the liquid fertilizer, a preheating pipe is arranged in the preheating tank, a primary heating pipe is arranged in the primary evaporation tank, and a secondary heating pipe is arranged in the secondary evaporation tank. In the concentration method, the liquid fertilizer is subjected to preheating, primary evaporation and secondary evaporation for the first time; when the concentration device is in a concentration mode, the preheating tank, the primary evaporation tank and the secondary evaporation tank are filled with liquid fertilizers, and the temperatures of the liquid fertilizers discharged from the preheating tank, the primary evaporation tank and the secondary evaporation tank are gradually increased; when the concentration device is in a dry burning mode, the preheating tank, the primary evaporation tank and the secondary evaporation tank do not contain the liquid fertilizer. The device can be used for concentrating the water thermal cracking liquid fertilizer.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid fertilizer production, and in particular relates to a concentrating device and a concentrating method for hydrothermal cracking liquid fertilizer. Background Art

[0002] It is an emerging technology that uses hydrothermal cracking to quickly and efficiently produce organic fertilizer using straw and manure as raw materials. It has the advantages of high efficiency, good quality and the ability to produce both solid and liquid fertilizers at the same time.

[0003] The hydrothermal cracking reaction is to hydrothermally crack the fully soaked organic matter (straw, manure, etc.) under the conditions of 1.0~2.45MPa and 180~245℃. The optimal moisture content of the reaction is 75-85%. After the reaction, some water will be lost in the exhaust steam discharge and the back-end drying and concentration. The solid fertilizer and liquid fertilizer produced by hydrothermal cracking have a solid-liquid ratio of 1:2 on the original weight. That is to say, a large amount of liquid fertilizer will be produced in the hydrothermal cracking stage. The liquid fertilizer needs to be concentrated to increase the effective ingredients per unit mass and solve the problem of liquid fertilizer storage and transportation.

[0004] However, since the composition of liquid fertilizer is relatively complex, it contains not only inorganic salts, but also a large number of organic macromolecules such as peptides, amino acids, humic acid, plant growth regulators, and plant stimulants, and contains a large number of micron and submicron organic particles. The existing concentration device is used for liquid fertilizer concentration. The concentration temperature is above 100°C. The temperature of the heating tube surface will be 30~50°C higher than the temperature of the liquid fertilizer, which is easy to form dirt, seriously affecting heat transfer, reducing efficiency, and even causing the concentration device to fail. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a concentration device and a concentration method for liquid fertilizer by hydrothermal cracking, so as to solve the problem that the existing concentration device in the prior art is applied to liquid fertilizer concentration, resulting in low concentration efficiency of the liquid fertilizer.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions.

[0007] The invention provides a concentrating device for hydrothermal cracking liquid fertilizer, comprising a preheating tank, a primary evaporating tank and a secondary evaporating tank which are sequentially connected along the flow direction of the liquid fertilizer, wherein the preheating tank is provided with a preheating tube, the primary evaporating tank is provided with a primary heating tube, and the secondary evaporating tank is provided with a secondary heating tube; the concentrating device has a concentrating mode and a dry burning mode; when the concentrating device is in the concentrating mode, the preheating tank, the primary evaporating tank and the secondary evaporating tank are filled with liquid fertilizer, and the temperature of the liquid fertilizer discharged from the preheating tank, the primary evaporating tank and the secondary evaporating tank gradually increases; when the concentrating device is in the dry burning mode, the preheating tank, the primary evaporating tank and the secondary evaporating tank are not filled with liquid fertilizer.

[0008] Furthermore, the primary evaporator and the secondary evaporator both include an evaporator body, and the primary heating tube and the secondary heating tube both include a top liquid inlet straight tube, a feed spiral tube, a bottom liquid inlet straight tube, a bottom liquid outlet straight tube, a discharge spiral tube and a top liquid outlet straight tube which are sequentially connected along the flow direction of the heating fluid; the top liquid inlet straight tube and the top liquid outlet straight tube both penetrate the top wall of the evaporator body and are arranged in parallel, and the bottom liquid inlet straight tube and the bottom liquid outlet straight tube are both located below the spiral liquid inlet tube and the spiral liquid outlet tube and are arranged in parallel.

[0009] Furthermore, a primary filtering tank is provided between the preheating tank and the primary evaporation tank; and / or a secondary filtering tank is provided between the primary evaporation tank and the secondary evaporation tank.

[0010] Furthermore, the primary filter tank and the secondary filter tank both include a filter tank body and a primary filter screen and a secondary filter screen arranged in the filter tank body. The primary filter screen and the secondary filter screen are arranged in sequence from bottom to top, and the filter tank body is provided with a filter liquid inlet, a sewage outlet, a thick slurry outlet and a clear liquid outlet.

[0011] Furthermore, the filtration liquid inlet and sewage outlet are located below the primary filter screen, the concentrated slurry outlet is located between the primary filter screen and the secondary filter screen, and the clear liquid outlet is located above the secondary filter screen.

[0012] Furthermore, the mesh size of the primary filter is larger than the mesh size of the secondary filter.

[0013] Furthermore, the primary filter tank and the secondary filter tank also include a check valve arranged at the filter liquid inlet.

[0014] Furthermore, the primary filter tank further comprises a primary backwash pipeline, the liquid inlet of the primary flush pipeline is connected to the liquid outlet of the preheating tank, the liquid outlet of the primary flush pipeline is connected to the primary filter tank, and the liquid outlet of the primary backwash pipeline is located above the secondary filter screen; The secondary filter tank also includes a secondary backwash pipeline, the liquid inlet of the secondary flushing pipeline is connected to the liquid outlet of the primary evaporation tank, the liquid outlet of the secondary flushing pipeline is connected to the secondary filter tank, and the liquid outlet of the secondary backwash pipeline is located above the secondary filter screen.

[0015] Furthermore, the concentrating device also includes a primary waste heat recovery pipe and a secondary waste heat recovery pipe arranged in the preheating tank, the primary waste heat recovery pipe and the secondary waste heat recovery pipe are arranged sequentially from top to bottom, the air inlet of the primary waste heat recovery pipe is connected to the air outlet of the primary evaporation tank, and the air inlet of the secondary waste heat recovery pipe is connected to the air outlet of the secondary evaporation tank.

[0016] Furthermore, the concentrating device also includes a driver and a ratchet and a pawl that cooperate with each other. The output shaft of the driver is connected to the top liquid inlet straight tube and the top liquid outlet straight tube, and is used to drive the feed spiral tube and the discharge spiral tube to rotate; the bottom liquid inlet straight tube and the bottom liquid outlet straight tube pass through the ratchet and are fixedly connected to the ratchet, and the pawl is arranged on the side wall of the evaporation tank body; when the primary heating tube and the secondary heating tube are used to heat the concentrated liquid fertilizer, the driver drives the primary heating tube and the secondary heating tube to rotate as a whole, and the pawl will not restrict the rotation of the ratchet; when the primary heating tube and the secondary heating tube are descaled, the driver drives the primary heating tube and the secondary heating tube to rotate in the opposite direction, and the setting of the pawl causes the rotation of the ratchet to be restricted, and the feed spiral tube and the discharge spiral tube are in a state of rotating at the top and fixed at the bottom.

[0017] The present invention also provides a method for concentrating liquid fertilizer by hydrothermal cracking, using the above-mentioned device for concentrating liquid fertilizer by hydrothermal cracking, and the concentrating method comprises the following steps: Step 1: supplying the heating fluid into the preheating tube, the primary heating tube and the secondary heating tube respectively, supplying the liquid fertilizer stock solution into the preheating tank, and the preheating tank preheats the liquid fertilizer stock solution to obtain preheated liquid fertilizer; Step 2: The preheated liquid fertilizer is supplied to a primary evaporation tank, which heats the preheated liquid fertilizer once, so that part of the water in the preheated liquid fertilizer evaporates to form water vapor, which is discharged from the primary evaporation tank to obtain liquid fertilizer after primary evaporation; Step 3: The liquid fertilizer after the primary evaporation is supplied to a secondary evaporation tank, which performs secondary heating on the liquid fertilizer after the primary evaporation, so that part of the water in the liquid fertilizer after the primary evaporation evaporates to form water vapor, which is discharged from the secondary evaporation tank to obtain liquid fertilizer after secondary evaporation.

[0018] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: A) The concentration device for liquid fertilizer by hydrothermal cracking provided by the present invention is provided with a preheating tank, a primary evaporation tank and a secondary evaporation tank. The liquid fertilizer is not concentrated in the preheating tank, but is only preheated for subsequent evaporation. The primary evaporation tank and the secondary evaporation tank form step-by-step low-temperature concentration, so that the liquid fertilizer can be efficiently concentrated at a relatively low temperature.

[0019] B) The concentration device for liquid fertilizer by hydrothermal cracking provided by the present invention can reduce the reaction between organic matter and inorganic matter due to the step-by-step low-temperature concentration, thereby reducing the generation of organic scale and ensuring the concentration efficiency of the concentration device.

[0020] C) In the concentration device for hydrothermal cracking liquid fertilizer provided by the present invention, the primary heating tube and the secondary heating tube are made of metal. After long-term use, a solid deposition layer will be attached to the outer wall of the primary heating tube and the secondary heating tube, that is, scaling. The components of the solid deposition layer include organic scale and inorganic scale, among which the organic scale is mainly. During the low-temperature dry burning process, the expansion coefficient of the primary heating tube and the secondary heating tube made of metal is greater than the expansion coefficient of the organic scale. After dry burning, the organic scale moves relative to the outer wall of the primary heating tube and the secondary heating tube, and the expansion of the primary heating tube and the secondary heating tube will cause cracks between the organic scales, so that the organic scale can fall off from the primary heating tube and the secondary heating tube. At the same time, the organic scale can also fall off from the primary heating tube and the secondary heating tube together with the inorganic scale, thereby achieving effective descaling.

[0021] D) The device for concentrating liquid fertilizer by hydrothermal cracking provided by the present invention filters the liquid fertilizer twice, thereby removing tiny suspended particles and a portion with a higher concentration in the liquid fertilizer, and retaining only the clear liquid for subsequent evaporation and concentration, thereby effectively reducing the amount of scaling of the primary heating tube and the secondary heating tube.

[0022] E) In the concentration device for liquid fertilizer by hydrothermal cracking provided by the present invention, the steam discharged from the primary evaporation tank and the secondary evaporation tank can enter the primary waste heat recovery pipe and the secondary waste heat recovery pipe, and the steam in the primary waste heat recovery pipe and the secondary waste heat recovery pipe can exchange heat with the liquid fertilizer in the preheating tank, thereby further improving the waste heat utilization rate of the concentration device.

[0023] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the embodiments of the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. In the entire drawings, the same reference symbols represent the same components; Figure 1 A schematic diagram of the structure of a device for concentrating liquid fertilizer by hydrothermal cracking provided in Example 1 of the present invention; Figure 2 A schematic diagram of the structure of a primary heating tube in a device for concentrating liquid fertilizer by hydrothermal cracking provided in Example 1 of the present invention; Figure 3 A schematic diagram of the structure of a primary filter tank in a concentration device for liquid fertilizer by hydrothermal cracking provided in Example 1 of the present invention; Figure 4A schematic diagram of the structure of a device for concentrating liquid fertilizer by hydrothermal cracking provided in the second embodiment of the present invention; Figure 5 A schematic diagram of the structure of a primary heating tube in a concentration device for liquid fertilizer by hydrothermal cracking provided in Embodiment 2 of the present invention; Figure 6 A schematic diagram of the connection of a ratchet, a pawl, a bottom liquid inlet straight pipe and a bottom liquid outlet straight pipe in a concentration device for hydrothermal cracking liquid fertilizer provided in Embodiment 2 of the present invention.

[0025] Reference numerals: 1-preheating tank; 2-primary evaporation tank; 3-secondary evaporation tank; 4-preheating tube; 5-primary heating tube; 51-top liquid inlet straight tube; 52-feeding spiral tube; 53-discharging spiral tube; 54-top liquid outlet straight tube; 55-bottom liquid inlet straight tube; 56-bottom liquid outlet straight tube; 6-secondary heating tube; 7-primary filter tank; 71-filter tank body; 72-primary filter screen; 73-secondary filter screen; 74-filter liquid inlet; 75-drainage outlet; 76-thick slurry outlet; 77-clear liquid outlet; 78-check valve; 79-primary backwash pipeline; 8-secondary filter tank; 9-primary waste heat recovery pipe; 10-secondary waste heat recovery pipe; 11-ratchet; 12-pawl. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0027] Embodiment 1 This embodiment provides a device for concentrating liquid fertilizer by hydrothermal decomposition, see Figure 1 , including a preheating tank 1, a primary evaporation tank 2 and a secondary evaporation tank 3 which are sequentially connected along the flow direction of the liquid fertilizer, the preheating tank 1 is provided with a preheating tube 4, the primary evaporation tank 2 is provided with a primary heating tube 5, the secondary evaporation tank 3 is provided with a secondary heating tube 6, and the concentration device has a concentration mode and a dry burning mode.

[0028] When the concentration device is in the concentration mode, the liquid inlet temperature of the preheating tube 4, the primary heating tube 5 and the secondary heating tube 6 is 110°C~120°C, the preheating tank 1, the primary evaporation tank 2 and the secondary evaporation tank 3 are filled with liquid fertilizer, and the temperature of the liquid fertilizer discharged from the preheating tank 1, the primary evaporation tank 2 and the secondary evaporation tank 3 gradually increases. Exemplarily, the temperature of the liquid fertilizer discharged from the preheating tank 1 is 75~85°C (for example, 80°C), the temperature of the liquid fertilizer discharged from the primary evaporation tank 2 is 98°C~102°C (for example, 100°C), and the temperature of the liquid fertilizer discharged from the secondary evaporation tank 3 is 103~107°C (for example, 105°C).

[0029] When the concentrator is in dry burning mode, the preheating tank 1, the primary evaporation tank 2 and the secondary evaporation tank 3 do not contain liquid fertilizer, and the liquid inlet temperature of the primary heating tube 5 and the secondary heating tube 6 is 180°C to 200°C.

[0030] Compared with the prior art, the concentration device for liquid fertilizer by hydrothermal cracking provided in this embodiment is provided with a preheating tank 1, a primary evaporation tank 2 and a secondary evaporation tank 3. On the one hand, the liquid fertilizer is not concentrated in the preheating tank 1, but is only preheated for subsequent evaporation. The primary evaporation tank 2 and the secondary evaporation tank 3 form step-by-step low-temperature concentration, thereby realizing efficient concentration of the liquid fertilizer at a relatively low temperature.

[0031] On the other hand, the use of step-by-step low-temperature concentration can reduce the reaction between organic and inorganic matter, thereby reducing the generation of organic scale and ensuring the concentration efficiency of the concentration device.

[0032] On the other hand, the primary heating tube 5 and the secondary heating tube 6 are made of metal. After long-term use, a layer of solid sedimentation layer, i.e., scale, will adhere to the outer walls of the primary heating tube 5 and the secondary heating tube 6. The components of the solid sedimentation layer include organic scale and inorganic scale, among which organic scale is mainly present. During low-temperature dry-burning, the expansion coefficient of the primary heating tube 5 and the secondary heating tube 6 made of metal is greater than the expansion coefficient of the organic scale. When the dry-burning temperature reaches 180-200°C, the organic scale moves relative to the outer walls of the primary heating tube 5 and the secondary heating tube 6, and the expansion of the primary heating tube 5 and the secondary heating tube 6 will cause cracks to form between the organic scales. The organic scale can fall off the primary heating tube 5 and the secondary heating tube 6. At the same time, the organic scale can also fall off the primary heating tube 5 and the secondary heating tube 6 together with the inorganic scale, thereby achieving effective descaling.

[0033] It should be noted that in the prior art, dry burning is an unfavorable situation and will cause damage to the equipment. In practical applications, it is usually necessary to avoid the occurrence of dry burning. However, this embodiment uses low-temperature dry burning to achieve the purpose of descaling.

[0034] In order to further reduce the scaling in the primary evaporation tank 2, a primary filter tank 7 is provided between the preheating tank 1 and the primary evaporation tank 2, that is, the liquid outlet of the preheating tank 1 is connected to the liquid inlet of the primary filter tank 7, and the liquid outlet of the primary filter tank 7 is connected to the liquid inlet of the primary evaporation tank 2. In this way, by providing the primary filter tank 7, the liquid fertilizer discharged from the preheating tank 1 can be filtered once, and the tiny suspended particles in the liquid fertilizer after preheating can be reduced, thereby reducing the structure in the primary evaporation tank 2.

[0035] Similarly, in order to further reduce the scaling in the secondary evaporation tank 3, a secondary filter tank 8 is provided between the primary evaporation tank 2 and the secondary evaporation tank 3, that is, the liquid outlet of the primary evaporation tank 2 is connected to the liquid inlet of the secondary filter tank 8, and the liquid outlet of the secondary filter tank 8 is connected to the liquid inlet of the secondary evaporation tank 3. In this way, by providing the secondary filter tank 8, the liquid fertilizer discharged from the primary evaporation tank 2 can be secondary filtered, and the tiny suspended particles in the liquid fertilizer after the primary evaporation can be reduced, thereby reducing the structure in the secondary evaporation tank 3.

[0036] It should be noted that the structures of the primary filter tank 7 and the secondary filter tank 8 are basically the same. Figure 3 , including a filter tank body 71 and a primary filter screen 72 and a secondary filter screen 73 arranged in the filter tank body 71. The primary filter screen 72 and the secondary filter screen 73 are arranged in sequence from bottom to top. The filter tank body 71 is provided with a filter liquid inlet 74, a sewage outlet 75, a concentrated slurry outlet 76 and a clear liquid outlet 77, wherein the filter liquid inlet 74 and the sewage outlet 75 are located below the primary filter screen 72, the concentrated slurry outlet 76 is located between the primary filter screen 72 and the secondary filter screen 73, and the clear liquid outlet 77 is located above the secondary filter screen 73. During implementation, the liquid fertilizer entering from the filter liquid inlet 74 reacts with the primary filter 72, and the primary filter 72 can filter out some tiny suspended particles, which are discharged from the sewage outlet 75. The filtered liquid fertilizer enters between the primary filter 72 and the secondary filter 73, and then acts with the secondary filter 73. The secondary filter 73 can filter out some concentrated slurry (rich in colloids), and the concentrated slurry is discharged from the concentrated slurry outlet 76. The clear liquid passes through the secondary filter 73 and is discharged from the filter tank 71 from the clear liquid outlet 77. In this way, the liquid fertilizer is filtered twice, which can remove the tiny suspended particles and the part with higher concentration in the liquid fertilizer, and only retain the clear liquid for subsequent evaporation and concentration, thereby effectively reducing the scaling amount of the primary heating tube 5 and the secondary heating tube 6.

[0037] Exemplarily, the mesh size of the primary filter 72 is larger than the mesh size of the secondary filter 73, thereby achieving double filtering of the liquid fertilizer.

[0038] In order to avoid the backflow of liquid fertilizer during the filtering process, the primary filter tank 7 and the secondary filter tank 8 also include a check valve 78 arranged at the filter liquid inlet 74. The check valve 78 can ensure that the flow of liquid fertilizer always flows into the filter tank body 71 to avoid the backflow of liquid fertilizer.

[0039] In actual applications, the primary filter 72 and the secondary filter 73 may become clogged after long-term use. Therefore, the above-mentioned primary filter tank 7 also includes a primary backwashing pipeline 79. The liquid inlet of the primary flushing pipeline is connected to the liquid outlet of the preheating tank 1, and the liquid outlet of the primary flushing pipeline is connected to the primary filter tank 7. The liquid outlet of the primary backwashing pipeline 79 is located above the secondary filter 73.

[0040] Similarly, the secondary filter tank 8 also includes a secondary backwash pipeline, the liquid inlet of the secondary flushing pipeline is connected to the liquid outlet of the primary evaporation tank 2, the liquid outlet of the secondary flushing pipeline is connected to the secondary filter tank 8, and the liquid outlet of the secondary backwash pipeline is located above the secondary filter screen 73.

[0041] It is worth noting that steam is generated during the primary evaporation and secondary evaporation of the liquid fertilizer, and the steam has a certain calorific value. In order to improve the waste heat utilization rate of the above-mentioned concentrating device, the above-mentioned concentrating device also includes a primary waste heat recovery pipe 9 and a secondary waste heat recovery pipe 10 arranged in the preheating tank 1. The primary waste heat recovery pipe 9 and the secondary waste heat recovery pipe 10 are arranged in sequence from top to bottom. The air inlet of the primary waste heat recovery pipe 9 is connected to the air outlet of the primary evaporation tank 2, and the air inlet of the secondary waste heat recovery pipe 10 is connected to the air outlet of the secondary evaporation tank 3. In this way, the steam discharged from the primary evaporation tank 2 and the secondary evaporation tank 3 can enter the primary waste heat recovery pipe 9 and the secondary waste heat recovery pipe 10, and the steam in the primary waste heat recovery pipe 9 and the secondary waste heat recovery pipe 10 can exchange heat with the liquid fertilizer in the preheating tank 1, further improving the waste heat utilization rate of the concentrating device.

[0042] Considering that the disturbance of the liquid fertilizer in the primary evaporation tank 2 and the secondary evaporation tank 3 increases, scaling will also be reduced. Therefore, the structures of the primary evaporation tank 2 and the secondary evaporation tank 3 are basically the same, and the structures of the primary heating tube 5 and the secondary heating tube 6 are basically the same. Specifically, the primary evaporation tank 2 and the secondary evaporation tank 3 both include an evaporation tank body, and the primary heating tube 5 and the secondary heating tube 6 both include a top liquid inlet straight pipe 51, a feed spiral pipe 52, a discharge spiral pipe 53 and a top liquid outlet straight pipe 54 connected in sequence along the flow direction of the heating fluid, see Figure 2 The top liquid inlet straight pipe 51 and the top liquid outlet straight pipe 54 both penetrate the top wall of the evaporation tank body and are arranged in parallel. The feed spiral pipe 52 and the discharge spiral pipe 53 are located in the evaporation tank body and are coaxially arranged, so that the two together form a spiral shape.

[0043] The above-mentioned concentrating device also includes a driver, the output shaft of which is connected to the top liquid inlet straight pipe 51 and the top liquid outlet straight pipe 54, and is used to drive the feed spiral pipe 52 and the discharge spiral pipe 53 to rotate.

[0044] In this way, through the setting of the driver and the spiral primary heating tube 5 and secondary heating tube 6, during the concentration process, the primary heating tube 5 and the secondary heating tube 6 are always in motion, which can not only increase the disturbance of the liquid fertilizer, but also reduce the deposition of organic matter and inorganic matter in the liquid fertilizer on the outer walls of the primary heating tube 5 and the secondary heating tube 6, thereby reducing scaling.

[0045] Since there is inevitably a gap between the top liquid inlet straight pipe 51 and the top liquid outlet straight pipe 54, which affects the sealing performance of the primary evaporation tank 2 and the secondary evaporation tank 3, the above-mentioned concentrating device also includes an elastic gasket and a first gear arranged on the upper end of the elastic gasket, a second gear is sleeved on the output shaft of the driver, the first gear is meshed with the second gear, the elastic gasket is provided with a top feed pipe hole and a top discharge pipe hole, the top liquid inlet straight pipe 51 passes through the top feed pipe hole, and the top liquid outlet straight pipe 54 passes through the top discharge pipe hole. In this way, through the provision of the elastic gasket, the top liquid inlet straight pipe 51 and the top liquid outlet straight pipe 54 can be effectively sealed and connected with the evaporation tank body.

[0046] Embodiment 2 This embodiment provides a device for concentrating liquid fertilizer by hydrothermal decomposition, and its structure is basically the same as that of the device for concentrating liquid fertilizer by hydrothermal decomposition provided in the first embodiment, except that: When the primary heating tube 5 and the secondary heating tube 6 are used for a long time and the scaling is serious, in order to remove the scaling which is difficult to remove, refer to Figures 4 to 5 The above-mentioned primary heating tube 5 and secondary heating tube 6 also include a bottom liquid inlet straight tube 55 and a bottom liquid outlet straight tube 56 which are connected in sequence along the flow direction of the heating fluid. The liquid inlet end of the bottom liquid inlet straight tube 55 is connected to the liquid outlet end of the liquid inlet spiral tube, and the liquid outlet end of the bottom liquid outlet straight tube 56 is connected to the liquid inlet end of the liquid outlet spiral tube. The bottom liquid inlet straight tube 55 and the bottom liquid outlet straight tube 56 are both located below the spiral liquid inlet tube and the spiral liquid outlet tube and are arranged in parallel.

[0047] The above-mentioned concentrating device also includes a ratchet 11 and a ratchet 12 which cooperate with each other, see Figure 6 A bottom feed pipe hole and a bottom discharge pipe hole are provided on the ratchet 11, a bottom liquid inlet straight pipe 55 passes through the bottom feed pipe hole and is fixedly connected to the ratchet 11, a bottom liquid outlet straight pipe 56 passes through the bottom discharge pipe hole and is fixedly connected to the ratchet 11, and a ratchet 12 is provided on the side wall of the evaporation tank body.

[0048] In this way, when the primary heating tube 5 and the secondary heating tube 6 are used to heat the concentrated liquid fertilizer, the driver drives the primary heating tube 5 and the secondary heating tube 6 to rotate as a whole, the pawl 12 will not limit the rotation of the ratchet 11, the ratchet 11 and the bottom liquid inlet straight tube 55 and the bottom liquid outlet straight tube 56 are in a free rotation state, and the liquid fertilizer in the evaporation tank body is stirred; when the primary heating tube 5 and the secondary heating tube 6 are descaled, the driver drives the primary heating tube 5 and the secondary heating tube 6 to rotate in the opposite direction, the setting of the pawl 12 causes the rotation of the ratchet 11 to be restricted, the ratchet 11, the bottom liquid inlet straight tube 55 and the bottom liquid outlet straight tube 56 are changed from a rotating connection to a fixed connection relative to the evaporation tank body, the top liquid inlet straight tube 51 and the top liquid outlet straight tube 54 are in a rotating connection relative to the evaporation tank body, the feeding spiral tube 52 and the discharging spiral tube 53 are in a state of top rotation and bottom fixation, and organic scale and inorganic scale cannot adapt to this deformation, so they will fall off from the outer wall of the feeding spiral tube 52 and the discharging spiral tube 53, thereby achieving the purpose of descaling.

[0049] Embodiment 3 This embodiment provides a method for concentrating liquid fertilizer by hydrothermal cracking, using the device for concentrating liquid fertilizer by hydrothermal cracking provided in Embodiment 1 or Embodiment 2, and the method comprises the following steps: Step 1: supplying a heating fluid (e.g., heat transfer oil, with a temperature of 110°C to 120°C) to the preheating tube 4, the primary heating tube 5, and the secondary heating tube 6 respectively, supplying a liquid fertilizer stock solution to the preheating tank 1, and the preheating tank 1 preheats the liquid fertilizer stock solution, so that the temperature of the liquid fertilizer stock solution rises to 75°C to 85°C (e.g., 80°C), thereby obtaining preheated liquid fertilizer; Step 2: The preheated liquid fertilizer is supplied to the primary evaporation tank 2, and the primary evaporation tank 2 heats the preheated liquid fertilizer once, so that the temperature of the preheated liquid fertilizer rises to 98° C. to 102° C., and part of the water in the preheated liquid fertilizer evaporates to form water vapor, which is discharged from the primary evaporation tank 2 to obtain the liquid fertilizer after the primary evaporation, thereby completing the primary concentration of the liquid fertilizer; Step 3: The liquid fertilizer after the primary evaporation is supplied to the secondary evaporation tank 3, and the secondary evaporation tank 3 performs secondary heating on the liquid fertilizer after the primary evaporation, so that the temperature of the liquid fertilizer after the primary evaporation rises to 103-107°C, and part of the water in the liquid fertilizer after the primary evaporation evaporates to form water vapor, which is discharged from the secondary evaporation tank 3 to obtain the liquid fertilizer after the secondary evaporation, thereby completing the secondary concentration of the liquid fertilizer.

[0050] Compared with the prior art, the beneficial effects of the method for concentrating liquid fertilizer by hydrothermal cracking provided in this embodiment are substantially the same as the beneficial effects of the method for concentrating liquid fertilizer by hydrothermal cracking provided in Example 1, and are not described in detail here.

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A device for concentrating liquid fertilizer by hydrothermal cracking, characterized in that: It comprises a preheating tank, a primary evaporation tank and a secondary evaporation tank which are sequentially connected along the flow direction of the liquid fertilizer, wherein the preheating tank is provided with a preheating pipe, the primary evaporation tank is provided with a primary heating pipe, and the secondary evaporation tank is provided with a secondary heating pipe; The concentrating device has a concentrating mode and a dry burning mode; when the concentrating device is in the concentrating mode, the preheating tank, the primary evaporating tank and the secondary evaporating tank are filled with liquid fertilizer, and the temperature of the liquid fertilizer discharged from the preheating tank, the primary evaporating tank and the secondary evaporating tank gradually increases; when the concentrating device is in the dry burning mode, the preheating tank, the primary evaporating tank and the secondary evaporating tank are not filled with liquid fertilizer.

2. The concentration device for hydrothermal cracking liquid fertilizer according to claim 1, characterized in that: The primary evaporation tank and the secondary evaporation tank both include an evaporation tank body, and the primary heating tube and the secondary heating tube both include a top liquid inlet straight tube, a feed spiral tube, a bottom liquid inlet straight tube, a bottom liquid outlet straight tube, a discharge spiral tube, and a top liquid outlet straight tube that are sequentially connected along the flow direction of the heating fluid; The top liquid inlet straight pipe and the top liquid outlet straight pipe both penetrate the top wall of the evaporation tank body and are arranged in parallel, and the bottom liquid inlet straight pipe and the bottom liquid outlet straight pipe are both located below the spiral liquid inlet pipe and the spiral liquid outlet pipe and are arranged in parallel.

3. The concentrating device for the hydrothermal cracking liquid fertilizer according to claim 1, characterized in that: A primary filtering tank is provided between the preheating tank and the primary evaporation tank; And / or, a secondary filtering tank is provided between the primary evaporation tank and the secondary evaporation tank.

4. The concentrating device for the hydrothermal cracking liquid fertilizer according to claim 3, characterized in that: The primary filter tank and the secondary filter tank both include a filter tank body and a primary filter screen and a secondary filter screen arranged in the filter tank body. The primary filter screen and the secondary filter screen are arranged in sequence from bottom to top. The filter tank body is provided with a filter liquid inlet, a sewage outlet, a thick slurry outlet and a clear liquid outlet.

5. The concentrating device for the hydrothermal cracking liquid fertilizer according to claim 4, characterized in that: The filtration liquid inlet and sewage outlet are located below the primary filter screen, the concentrated slurry outlet is located between the primary filter screen and the secondary filter screen, and the clear liquid outlet is located above the secondary filter screen.

6. The concentrating device for the hydrothermal cracking liquid fertilizer according to claim 4, characterized in that: The mesh aperture of the primary filter is larger than the mesh aperture of the secondary filter.

7. The device for concentrating liquid fertilizer by hydrothermal cracking according to claim 4, characterized in that: The primary filter tank and the secondary filter tank also include a check valve arranged at the filter liquid inlet.

8. The device for concentrating liquid fertilizer by hydrothermal cracking according to claim 4, characterized in that: The primary filter tank further comprises a primary backwash pipeline, the liquid inlet of the primary flush pipeline is connected to the liquid outlet of the preheating tank, the liquid outlet of the primary flush pipeline is connected to the primary filter tank, and the liquid outlet of the primary backwash pipeline is located above the secondary filter screen; The secondary filter tank also includes a secondary backwash pipeline, the liquid inlet of the secondary flush pipeline is connected to the liquid outlet of the primary evaporation tank, the liquid outlet of the secondary flush pipeline is connected to the secondary filter tank, and the liquid outlet of the secondary backwash pipeline is located above the secondary filter screen.

9. The device for concentrating liquid fertilizer by hydrothermal decomposition according to any one of claims 1 to 8, characterized in that: The concentrating device also includes a primary waste heat recovery pipe and a secondary waste heat recovery pipe arranged in the preheating tank, the primary waste heat recovery pipe and the secondary waste heat recovery pipe are arranged in sequence from top to bottom, the air inlet of the primary waste heat recovery pipe is connected to the air outlet of the primary evaporation tank, and the air inlet of the secondary waste heat recovery pipe is connected to the air outlet of the secondary evaporation tank.

10. A method for concentrating liquid fertilizer by hydrothermal cracking, characterized in that: Using the hydrothermal liquid fertilizer concentration device according to any one of claims 1 to 9, the concentration method comprises the following steps: Step 1: supplying the heating fluid into the preheating tube, the primary heating tube and the secondary heating tube respectively, supplying the liquid fertilizer stock solution into the preheating tank, and the preheating tank preheats the liquid fertilizer stock solution to obtain preheated liquid fertilizer; Step 2: The preheated liquid fertilizer is supplied to a primary evaporation tank, and the primary evaporation tank heats the preheated liquid fertilizer once, so that part of the water in the preheated liquid fertilizer evaporates to form water vapor, which is discharged from the primary evaporation tank to obtain liquid fertilizer after primary evaporation; Step 3: The liquid fertilizer after the primary evaporation is supplied to a secondary evaporation tank, and the secondary evaporation tank performs secondary heating on the liquid fertilizer after the primary evaporation, so that part of the water in the liquid fertilizer after the primary evaporation evaporates to form water vapor, which is discharged from the secondary evaporation tank to obtain liquid fertilizer after secondary evaporation.

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