A concentration device and method for hydrothermal cracking liquid fertilizer

Abstract

The present invention discloses a concentration device and a concentration method for hydrothermal cracking liquid fertilizer, belonging to the technical field of liquid fertilizer production, and is used to solve the problem that the existing concentration device in the prior art has low concentration efficiency for liquid fertilizer when applied to the concentration of liquid fertilizer. The concentration device of the present invention includes a preheating tank, a primary evaporation tank, and a secondary evaporation tank connected in sequence along the flow direction of the liquid fertilizer. A preheating pipe is provided in the preheating tank, a primary heating pipe is provided in the primary evaporation tank, and a secondary heating pipe is provided in the secondary evaporation tank. In the concentration method of the present invention, the liquid fertilizer undergoes preheating, primary evaporation, and secondary evaporation in sequence; when the concentration device is in the concentration mode, the preheating tank, the primary evaporation tank, and the secondary evaporation tank are filled with liquid fertilizer, and the temperature of the liquid fertilizer discharged from the preheating tank, the primary evaporation tank, and the secondary evaporation tank gradually increases; when the concentration device is in the dry burning mode, the preheating tank, the primary evaporation tank, and the secondary evaporation tank are not filled with liquid fertilizer. The present invention can be used for the concentration of hydrothermal cracking liquid fertilizer.

Description

Technical Field

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

[0002] Adopting the hydrothermal cracking method to rapidly and efficiently produce organic fertilizers from straw manure as raw materials has the advantages of high efficiency, good quality, and simultaneous production of solid fertilizers and liquid fertilizers. It is a new technology.

[0003] The hydrothermal cracking reaction is carried out under the conditions of 1.0~2.45 MPa and 180~245 °C. The fully wetted organic matter (such as straw and manure) is subjected to hydrothermal cracking. The optimal moisture content of the reaction is 75 - 85%. After the reaction, the discharged steam and the subsequent drying and concentration will lose a part of the water. The solid-liquid ratio of the solid fertilizer and the liquid fertilizer produced by hydrothermal cracking is 1:2 in the original weight. That is to say, a large amount of liquid fertilizer will be produced in the hydrothermal cracking stage, and the liquid fertilizer needs to be concentrated to improve the effective components per unit mass and solve the problems of storage and transportation of the liquid fertilizer.

[0004] However, due to the complex composition of the liquid fertilizer, it not only contains inorganic salts, but also is rich in a large number of organic macromolecules such as polypeptides, amino acids, humic acids, plant growth regulators, and plant stimulants, and contains a large number of organic matter particles at the micron and sub-micron scales. The existing concentration devices are applied to the concentration of liquid fertilizer. The concentration temperature is above 100 °C, and the temperature on the surface of the heating tube will be 30~50 °C higher than the temperature of the liquid fertilizer, which is easy to form dirt, seriously affect heat transfer, reduce efficiency, and even cause 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 hydrothermal cracking liquid fertilizer to solve the problem of low concentration efficiency of liquid fertilizer caused by the application of the existing concentration device in the prior art.

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

[0007] The present invention provides a concentration device for hydrothermal cracking liquid fertilizer, which includes a preheating tank, a primary evaporation tank, and a secondary evaporation tank connected in sequence along the flow direction of the liquid fertilizer. A preheating tube is provided in the preheating tank, a primary heating tube is provided in the primary evaporation tank, and a secondary heating tube is provided in the secondary evaporation tank; the concentration device has a concentration mode and a dry-burning mode; when the concentration device is in the concentration mode, the preheating tank, the primary evaporation tank, and the secondary evaporation tank are filled with liquid fertilizer, and the temperature of the liquid fertilizer discharged from the preheating tank, the primary evaporation tank, and the secondary evaporation tank gradually increases; when the concentration device is in the dry-burning mode, the preheating tank, the primary evaporation tank, and the secondary evaporation tank are not filled with liquid fertilizer.

[0008] Furthermore, both the primary evaporation tank and the secondary evaporation tank include an evaporation tank body. Both the primary heating pipe and the secondary heating pipe include a top liquid inlet straight pipe, a feed spiral pipe, a bottom liquid inlet straight pipe, a bottom liquid outlet straight pipe, a discharge spiral pipe, and a top liquid outlet straight pipe 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. 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.

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

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

[0011] Furthermore, the filtration liquid inlet and the sewage discharge port are located below the primary filter screen, the thick slurry liquid 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 pore size of the primary filter screen is larger than that of the secondary filter screen.

[0013] Furthermore, both the primary filtration tank and the secondary filtration tank further include a check valve provided at the filtration liquid inlet.

[0014] Furthermore, the primary filtration tank further includes a primary backwashing pipeline. The liquid inlet of the primary backwashing pipeline is connected to the liquid outlet of the preheating tank, the liquid outlet of the primary backwashing pipeline is connected to the primary filtration tank, and the liquid outlet of the primary backwashing pipeline is located above the secondary filter screen;

[0015] The secondary filtration tank further includes a secondary backwashing pipeline. The liquid inlet of the secondary backwashing pipeline is connected to the liquid outlet of the primary evaporation tank, the liquid outlet of the secondary backwashing pipeline is connected to the secondary filtration tank, and the liquid outlet of the secondary backwashing pipeline is located above the secondary filter screen.

[0016] Furthermore, the concentration device further includes a primary waste heat recovery pipe and a secondary waste heat recovery pipe provided in the preheating tank. The primary waste heat recovery pipe and the secondary waste heat recovery pipe are sequentially arranged 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.

[0017] Further, the concentration device further includes a driver, as well as a ratchet and a pawl that cooperate with each other. The output shaft of the driver is connected to the top liquid inlet straight pipe and the top liquid outlet straight pipe, and is used to drive the feed spiral pipe and the discharge spiral pipe to rotate; the bottom liquid inlet straight pipe and the bottom liquid outlet straight pipe penetrate 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 pipe and the secondary heating pipe are used to heat and concentrate the liquid fertilizer, the driver drives the primary heating pipe and the secondary heating pipe to rotate as a whole, and the pawl will not restrict the rotation of the ratchet; when descaling the primary heating pipe and the secondary heating pipe, the driver drives the primary heating pipe and the secondary heating pipe to rotate in the reverse direction, and the setting of the pawl causes the rotation of the ratchet to be restricted, and the feed spiral pipe and the discharge spiral pipe are in a state of rotating at the top and fixed at the bottom.

[0018] The present invention also provides a method for concentrating a hydrothermal cracking liquid fertilizer, which adopts the above-mentioned concentration device for hydrothermal cracking liquid fertilizer. The concentration method includes the following steps:

[0019] Step 1: Supply the heating fluid into the preheating pipe, the primary heating pipe and the secondary heating pipe respectively, and supply the original liquid fertilizer into the preheating tank. The preheating tank preheats the original liquid fertilizer to obtain the preheated liquid fertilizer.

[0020] Step 2: Supply the preheated liquid fertilizer into the primary evaporation tank. The primary evaporation tank performs primary heating on the preheated liquid fertilizer, so that part of the water in the preheated liquid fertilizer evaporates to form water vapor and is discharged from the primary evaporation tank to obtain the liquid fertilizer after primary evaporation.

[0021] Step 3: Supply the liquid fertilizer after primary evaporation into the secondary evaporation tank. The secondary evaporation tank performs secondary heating on the liquid fertilizer after primary evaporation, so that part of the water in the liquid fertilizer after primary evaporation evaporates to form water vapor and is discharged from the secondary evaporation tank to obtain the liquid fertilizer after secondary evaporation.

[0022] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0023] A) The concentration device for hydrothermal cracking liquid fertilizer 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 only preheats the liquid fertilizer for subsequent evaporation. The primary evaporation tank and the secondary evaporation tank form a step-by-step low-temperature concentration, so that the high-efficiency concentration of the liquid fertilizer can be realized at a lower temperature.

[0024] B) The concentration device for hydrothermal cracking liquid fertilizer provided by the present invention, due to adopting step-by-step low-temperature concentration, can reduce the reactions occurring between organic matter and inorganic matter, thereby reducing the generation of organic scale and ensuring the concentration efficiency of the concentration device.

[0025] C) In the concentration device of the hydrothermal cracking liquid fertilizer provided by the present invention, the primary heating pipe and the secondary heating pipe are made of metal. After long-term use, a solid deposition layer, that is, scale, will adhere to the outer walls of the primary heating pipe and the secondary heating pipe. The composition of this solid deposition layer includes organic scale and inorganic scale, among which the organic scale is the main component. During the low-temperature dry-burning process, the expansion coefficient of the primary heating pipe and the secondary heating pipe made of metal is greater than that of the organic scale. After dry-burning, the organic scale moves relative to the outer walls of the primary heating pipe and the secondary heating pipe, and the expansion of the primary heating pipe and the secondary heating pipe will cause cracks to occur between the organic scales. The organic scale can fall off from the primary heating pipe and the secondary heating pipe. At the same time, the organic scale can also cause the inorganic scale to fall off from the primary heating pipe and the secondary heating pipe, achieving effective scale removal.

[0026] D) The concentration device of the hydrothermal cracking liquid fertilizer provided by the present invention filters the liquid fertilizer twice, which can remove the tiny suspended particles and the part with a higher concentration in the liquid fertilizer, and only the clear liquid is retained and enters the subsequent evaporation and concentration, thereby effectively reducing the scale formation amount on the primary heating pipe and the secondary heating pipe.

[0027] E) In the concentration device of the hydrothermal cracking liquid fertilizer 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. 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, further improving the waste heat utilization rate of the concentration device.

[0028] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be made obvious from the description, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the examples in the description and the content specifically pointed out in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings are only used for the purpose of showing specific embodiments, and are not considered as a limitation to the present invention. Throughout the drawings, the same reference signs represent the same components;

[0030] Figure 1 It is a schematic structural diagram of the concentration device of the hydrothermal cracking liquid fertilizer provided in Embodiment 1 of the present invention;

[0031] Figure 2 It is a schematic structural diagram of the primary heating pipe in the concentration device of the hydrothermal cracking liquid fertilizer provided in Embodiment 1 of the present invention;

[0032] Figure 3 It is a schematic structural diagram of the primary filtration tank in the concentration device of the hydrothermal cracking liquid fertilizer provided in Embodiment 1 of the present invention;

[0033] Figure 4 The structural schematic diagram of the concentration device for the hydrothermal cracking liquid fertilizer provided in the second embodiment of the present invention;

[0034] Figure 5 The structural schematic diagram of the primary heating pipe in the concentration device for the hydrothermal cracking liquid fertilizer provided in the second embodiment of the present invention;

[0035] Figure 6 The connection schematic diagram of the ratchet, pawl, bottom liquid inlet straight pipe and bottom liquid outlet straight pipe in the concentration device for the hydrothermal cracking liquid fertilizer provided in the second embodiment of the present invention.

[0036] Reference numerals:

[0037] 1 - Preheating tank; 2 - Primary evaporation tank; 3 - Secondary evaporation tank; 4 - Preheating pipe; 5 - Primary heating pipe; 51 - Top liquid inlet straight pipe; 52 - Feed spiral pipe; 53 - Discharge spiral pipe; 54 - Top liquid outlet straight pipe; 55 - Bottom liquid inlet straight pipe; 56 - Bottom liquid outlet straight pipe; 6 - Secondary heating pipe; 7 - Primary filtration tank; 71 - Filtration tank body; 72 - Primary filter screen; 73 - Secondary filter screen; 74 - Filtration liquid inlet; 75 - Drain port; 76 - Thick slurry liquid outlet; 77 - Clear liquid outlet; 78 - Check valve; 79 - Primary backwashing pipeline; 8 - Secondary filtration tank; 9 - Primary waste heat recovery pipe; 10 - Secondary waste heat recovery pipe; 11 - Ratchet; 12 - Pawl. Detailed implementation manners

[0038] The following will specifically describe the preferred embodiments of the present invention with reference to the accompanying drawings. The accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention, rather than to limit the scope of the present invention.

[0039] Embodiment 1

[0040] This embodiment provides a concentration device for hydrothermal cracking liquid fertilizer. Refer to Figure 1 , which includes a preheating tank 1, a primary evaporation tank 2 and a secondary evaporation tank 3 connected in sequence along the flow direction of the liquid fertilizer. A preheating pipe 4 is provided in the preheating tank 1, a primary heating pipe 5 is provided in the primary evaporation tank 2, and a secondary heating pipe 6 is provided in the secondary evaporation tank 3. The concentration device has a concentration mode and a dry burning mode.

[0041] When the concentration device is in the concentration mode, the inlet liquid temperatures of the preheating pipe 4, the primary heating pipe 5, and the secondary heating pipe 6 are 110°C to 120°C. The preheating tank 1, the primary evaporation tank 2, and the secondary evaporation tank 3 are filled with liquid fertilizer. The temperatures of the liquid fertilizer discharged from the preheating tank 1, the primary evaporation tank 2, and the secondary evaporation tank 3 gradually increase. Exemplarily, the temperature of the liquid fertilizer discharged from the preheating tank 1 is 75 - 85°C (e.g., 80°C), the temperature of the liquid fertilizer discharged from the primary evaporation tank 2 is 98°C to 102°C (e.g., 100°C), and the temperature of the liquid fertilizer discharged from the secondary evaporation tank 3 is 103 - 107°C (e.g., 105°C).

[0042] When the concentration device is in the dry burning mode, the preheating tank 1, the primary evaporation tank 2, and the secondary evaporation tank 3 are not filled with liquid fertilizer, and the inlet liquid temperatures of the primary heating pipe 5 and the secondary heating pipe 6 are 180°C to 200°C.

[0043] Compared with the prior art, in the concentration device for hydrothermal cracking liquid fertilizer provided in this embodiment, there are 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 only preheated for subsequent evaporation. The primary evaporation tank 2 and the secondary evaporation tank 3 form a step-by-step low-temperature concentration, so that the efficient concentration of the liquid fertilizer can be achieved at a lower temperature.

[0044] On the other hand, due to the step-by-step low-temperature concentration, the reactions between organic matter and inorganic matter can be reduced, thereby reducing the formation of organic scale and ensuring the concentration efficiency of the concentration device.

[0045] On the other hand, the materials of the primary heating pipe 5 and the secondary heating pipe 6 are metals. After long-term use, a solid deposition layer, that is, scale, will adhere to the outer walls of the primary heating pipe 5 and the secondary heating pipe 6. The composition of this solid deposition layer includes organic scale and inorganic scale, among which the organic scale is the main component. During the low-temperature dry burning process, the expansion coefficient of the primary heating pipe 5 and the secondary heating pipe 6 made of metal is greater than that 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 pipe 5 and the secondary heating pipe 6, and the expansion of the primary heating pipe 5 and the secondary heating pipe 6 will cause cracks to appear between the organic scales, and the organic scale can fall off from the primary heating pipe 5 and the secondary heating pipe 6. At the same time, the organic scale can also cause the inorganic scale to fall off from the primary heating pipe 5 and the secondary heating pipe 6 together, achieving effective scale removal.

[0046] It should be noted that in the prior art, dry burning is an adverse situation that will cause damage to the equipment. In actual applications, dry burning usually needs to be avoided. However, in this embodiment, low-temperature dry burning can be used to achieve the purpose of scale removal.

[0047] In order to further reduce the scale formation in the primary evaporation tank 2, a primary filter tank 7 is provided between the above-mentioned preheating tank 1 and the primary evaporation tank 2. That is to say, 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, through the setting of the primary filter tank 7, the liquid fertilizer discharged from the preheating tank 1 can be filtered once, reducing the tiny suspended particles in the preheated liquid fertilizer, and further reducing the scale in the primary evaporation tank 2.

[0048] Similarly, in order to further reduce the scale formation in the secondary evaporation tank 3, a secondary filter tank 8 is provided between the above-mentioned primary evaporation tank 2 and the secondary evaporation tank 3. That is to say, 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, through the setting of the secondary filter tank 8, the liquid fertilizer discharged from the primary evaporation tank 2 can be filtered twice, reducing the tiny suspended particles in the liquid fertilizer after the first evaporation, and further reducing the scale in the secondary evaporation tank 3.

[0049] It should be noted that the structures of the primary filter tank 7 and the secondary filter tank 8 are basically the same. Specifically, see Figure 3 , which includes a filter tank body 71, 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. A filter liquid inlet 74, a sewage discharge port 75, a thick slurry outlet 76 and a clear liquid outlet 77 are opened on the filter tank body 71. Among them, the filter liquid inlet 74 and the sewage discharge port 75 are located below the primary filter screen 72, the thick 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 acts on the primary filter screen 72. The primary filter screen 72 can filter out some tiny suspended particles, and the tiny suspended particles are discharged from the sewage discharge port 75. The filtered liquid fertilizer enters between the primary filter screen 72 and the secondary filter screen 73, and then acts on the secondary filter screen 73. The secondary filter screen 73 can filter out some thick slurry (rich in colloid), and the thick slurry is discharged from the thick slurry outlet 76. The clear liquid passes through the secondary filter screen 73 and is discharged from the clear liquid outlet 77 out of the filter tank body 71. In this way, by filtering the liquid fertilizer twice, the tiny suspended particles and the higher-concentration part in the liquid fertilizer can be removed, and only the clear liquid is retained to enter the subsequent evaporation and concentration, so as to effectively reduce the scale formation amount of the primary heating pipe 5 and the secondary heating pipe 6.

[0050] Exemplarily, the pore diameter of the primary filter screen 72 is larger than the pore diameter of the secondary filter screen 73, so as to realize the two-stage filtration of the liquid fertilizer.

[0051] To avoid the backflow of liquid fertilizer during the filtration process, the above-mentioned primary filtration tank 7 and secondary filtration tank 8 further include a check valve 78 provided at the filtration liquid inlet 74. Through the check valve 78, it can be ensured that the flow of liquid fertilizer is always into the filtration tank body 71, avoiding the occurrence of backflow of liquid fertilizer.

[0052] In practical applications, the primary filter screen 72 and the secondary filter screen 73 may become blocked after long-term use. Therefore, the above-mentioned primary filtration tank 7 further includes a primary backwash pipeline 79. The liquid inlet of the primary backwash pipeline is connected to the liquid outlet of the preheating tank 1, the liquid outlet of the primary backwash pipeline is connected to the primary filtration tank 7, and the liquid outlet of the primary backwash pipeline 79 is located above the secondary filter screen 73.

[0053] Similarly, the secondary filtration tank 8 further includes a secondary backwash pipeline. The liquid inlet of the secondary backwash pipeline is connected to the liquid outlet of the primary evaporation tank 2, the liquid outlet of the secondary backwash pipeline is connected to the secondary filtration tank 8, and the liquid outlet of the secondary backwash pipeline is located above the secondary filter screen 73.

[0054] It should be noted that steam is generated during the primary evaporation and secondary evaporation of liquid fertilizer, and the steam has a certain calorific value. In order to improve the waste heat utilization rate of the above-mentioned concentration device, the concentration device further includes a primary waste heat recovery pipe 9 and a secondary waste heat recovery pipe 10 provided 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 concentration device.

[0055] Considering that the disturbance of the liquid fertilizer in the primary evaporation tank 2 and the secondary evaporation tank 3 increases, which will also reduce scaling. Therefore, the structures of the above-mentioned primary evaporation tank 2 and secondary evaporation tank 3 are basically the same, and the structures of the above-mentioned primary heating pipe 5 and secondary heating pipe 6 are basically the same. Specifically, both the primary evaporation tank 2 and the secondary evaporation tank 3 include an evaporation tank body, and both the primary heating pipe 5 and the secondary heating pipe 6 include a top inlet straight pipe 51, a feed spiral pipe 52, a discharge spiral pipe 53, and a top outlet straight pipe 54 that are sequentially connected along the flow direction of the heating fluid. See Figure 2 wherein, both the top inlet straight pipe 51 and the top outlet straight pipe 54 penetrate the top wall of the evaporation tank body and are arranged in parallel, and the feed spiral pipe 52 and the discharge spiral pipe 53 are arranged coaxially inside the evaporation tank, so that the two together form a spiral shape.

[0056] The above concentration device further includes a driver, the output shaft of the driver 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.

[0057] In this way, through the setting of the driver and the spiral primary heating pipe 5 and secondary heating pipe 6, during the concentration process, the primary heating pipe 5 and the secondary heating pipe 6 are always in a moving state, 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 pipe 5 and the secondary heating pipe 6, and thus can reduce scale formation.

[0058] Since there will inevitably be 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, therefore, the above concentration device further includes an elastic gasket and a first gear provided at the upper end of the elastic gasket. A second gear is sleeved on the output shaft of the driver, the first gear meshes 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 setting of the elastic gasket, the sealed connection between the top liquid inlet straight pipe 51 and the top liquid outlet straight pipe 54 and the evaporation tank body can be effectively realized.

[0059] Embodiment Two

[0060] This embodiment provides a concentration device for hydrothermal cracking liquid fertilizer, and its structure is basically the same as that of the concentration device for hydrothermal cracking liquid fertilizer provided in Embodiment One, the difference being:

[0061] When the primary heating pipe 5 and the secondary heating pipe 6 are used for a long time and scale formation is relatively serious, in order to remove this difficult-to-remove scale, refer to Figures 4 to 5 , the above primary heating pipe 5 and secondary heating pipe 6 both further include a bottom liquid inlet straight pipe 55 and a bottom liquid outlet straight pipe 56 that are sequentially connected along the flow direction of the heating fluid. The liquid inlet end of the bottom liquid inlet straight pipe 55 is connected to the liquid outlet end of the liquid inlet spiral pipe, the liquid outlet end of the bottom liquid outlet straight pipe 56 is connected to the liquid inlet end of the liquid outlet spiral pipe, and both the bottom liquid inlet straight pipe 55 and the bottom liquid outlet straight pipe 56 are located below the spiral liquid inlet pipe and the spiral liquid outlet pipe and are arranged in parallel.

[0062] The above concentration device further includes a ratchet 11 and a pawl 12 that cooperate with each other, refer to Figure 6 , the ratchet 11 is provided with a bottom feed pipe hole and a bottom discharge pipe hole, the bottom liquid inlet straight pipe 55 passes through the bottom feed pipe hole and is fixedly connected to the ratchet 11, the bottom liquid outlet straight pipe 56 passes through the bottom discharge pipe hole and is fixedly connected to the ratchet 11, and the pawl 12 is provided on the side wall of the evaporation tank body.

[0063] In this way, when the primary heating pipe 5 and the secondary heating pipe 6 are used to heat and concentrate the liquid fertilizer, the driver drives the primary heating pipe 5 and the secondary heating pipe 6 to rotate as a whole. The pawl 12 will not restrict the rotation of the ratchet 11. The ratchet 11, the bottom liquid inlet straight pipe 55, and the bottom liquid outlet straight pipe 56 are in a free rotation state to stir the liquid fertilizer in the evaporation tank. When descaling the primary heating pipe 5 and the secondary heating pipe 6, the driver drives the primary heating pipe 5 and the secondary heating pipe 6 to rotate in the reverse 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 pipe 55, and the bottom liquid outlet straight pipe 56 change from a rotational connection to a fixed connection relative to the evaporation tank body. The top liquid inlet straight pipe 51 and the top liquid outlet straight pipe 54 are in a rotational connection relative to the evaporation tank body. The feed spiral pipe 52 and the discharge spiral pipe 53 are in a state of rotating at the top and fixed at the bottom. Organic and inorganic scales cannot adapt to this deformation, so they will fall off from the outer walls of the feed spiral pipe 52 and the discharge spiral pipe 53, achieving the purpose of descaling.

[0064] Embodiment III

[0065] This embodiment provides a method for concentrating hydrothermal cracking liquid fertilizer, using the hydrothermal cracking liquid fertilizer concentration device provided in Embodiment I or Embodiment II. This concentration method includes the following steps:

[0066] Step 1: Supply the heating fluid (for example, heat-conducting oil with a temperature of 110°C to 120°C) into the preheating pipe 4, the primary heating pipe 5, and the secondary heating pipe 6 respectively. Supply the liquid fertilizer stock solution into the preheating tank 1. The preheating tank 1 preheats the liquid fertilizer stock solution so that the temperature of the liquid fertilizer stock solution rises to 75 - 85°C (for example, 80°C) to obtain the preheated liquid fertilizer.

[0067] Step 2: Supply the preheated liquid fertilizer into the primary evaporation tank 2. The primary evaporation tank 2 conducts primary heating on the preheated liquid fertilizer so that the temperature of the preheated liquid fertilizer rises to 98°C to 102°C. Part of the water in the preheated liquid fertilizer evaporates to form water vapor and is discharged from the primary evaporation tank 2 to obtain the liquid fertilizer after primary evaporation, completing the primary concentration of the liquid fertilizer.

[0068] Step 3: Supply the liquid fertilizer after primary evaporation into the secondary evaporation tank 3. The secondary evaporation tank 3 conducts secondary heating on the liquid fertilizer after primary evaporation so that the temperature of the liquid fertilizer after primary evaporation rises to 103 - 107°C. Part of the water in the liquid fertilizer after primary evaporation evaporates to form water vapor and is discharged from the secondary evaporation tank 3 to obtain the liquid fertilizer after secondary evaporation, completing the secondary concentration of the liquid fertilizer.

[0069] Compared with the prior art, the beneficial effects of the hydrothermal cracking liquid fertilizer concentration method provided in this embodiment are basically the same as those of the hydrothermal cracking liquid fertilizer concentration method provided in Embodiment I, and will not be elaborated here one by one.

[0070] As described above, it is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art 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 contain 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 do not contain liquid fertilizer; 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 that are sequentially connected along the flow direction of the heating fluid, the liquid inlet end of the bottom liquid inlet straight tube is connected to the liquid outlet end of the feed spiral tube, and the liquid outlet end of the bottom liquid outlet straight tube is connected to the liquid inlet end of the discharge spiral tube; The concentrating device also includes a driver, the output shaft of the driver is connected to the top liquid inlet straight pipe and the top liquid outlet straight pipe; The concentrating device also includes a ratchet and a pawl that cooperate with each other. The ratchet is provided with a bottom feed pipe hole and a bottom discharge pipe hole. The bottom liquid inlet straight pipe passes through the bottom feed pipe hole and is fixedly connected to the ratchet. The bottom liquid discharge straight pipe passes through the bottom discharge pipe hole and is fixedly connected to the ratchet. The pawl is arranged on the side wall of the evaporation tank body. The primary heating tube and the secondary heating tube are used for heating and concentrating the liquid fertilizer. The driver drives the primary heating tube and the secondary heating tube to rotate as a whole. The ratchet and the bottom liquid inlet straight pipe and the bottom liquid discharge straight pipe are in a free rotation state to stir the liquid fertilizer in the evaporation tank body. 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. The ratchet, the bottom liquid inlet straight pipe and the bottom liquid discharge straight pipe are changed from a rotational connection to a fixed connection relative to the evaporation tank body. The top liquid inlet straight pipe and the top liquid discharge straight pipe are in a rotational connection relative to the evaporation tank body.

2. The concentration device for hydrothermal cracking liquid fertilizer according to claim 1, characterized in that: 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 concentration device for the hydrothermal cracking liquid fertilizer 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 backwash pipeline is connected to the liquid outlet of the preheating tank, the liquid outlet of the primary backwash 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 backwash pipeline is connected to the liquid outlet of the primary evaporation tank, the liquid outlet of the secondary backwash 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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