Urea solution preparation device and method

Abstract

The invention relates to a urea solution preparation device and method, a material suction port of a gas-solid separation tank is used for sucking urea particles through a material suction pipeline, a discharge port of the gas-solid separation tank is connected with an inlet of a stock bin through a discharge pipeline, a discharge valve is arranged on the discharge pipeline, an exhaust port of the gas-solid separation tank is connected with a feed port of a jet device through a feeding pipeline, and a discharge port of the jet device is connected with a discharge port of the gas-solid separation tank. And a feeding valve is arranged on the feeding pipeline. An outlet of the stock bin is connected with an inlet of the feeder, an outlet of the feeder is connected with an inlet of the fluidization hopper, an outlet of the fluidization hopper is connected with a feeding port of the jet device through a feeding pipeline, and a feeding valve is arranged on the feeding pipeline. A liquid outlet of the jet device is connected with a liquid inlet of the buffer tank, a jet orifice of the buffer tank is connected with an inlet of the jet pump through a jet pipeline, an outlet of the jet pump is connected with a liquid inlet of the jet device through a liquid inlet pipeline, and a liquid conveying opening of the buffer tank is used for outputting a urea solution to the urea solution storage tank through a liquid conveying pipeline. The device can realize integration of urea feeding, storage and dissolution, and the labor cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of urea solution preparation, and in particular to a urea solution preparation device and method. Background Art

[0002] Commonly used reducing agents for flue gas denitrification include liquid ammonia, aqueous ammonia, and urea. Compared with the former two, there is a certain degree of danger. Urea has stable chemical properties, is non-toxic, has low danger, and is easy to transport and store. At present, the country is promoting the replacement of liquid ammonia and aqueous ammonia with urea to reduce dangerous sources in power plants. For this reason, urea will be used more and more as the preferred denitrification reducing agent in the future.

[0003] Urea purchased from outside is generally in granular form, and for ease of transportation, most of it is packed in bags. Therefore, the urea granules need to be dissolved to prepare urea solution.

[0004] The existing urea solution preparation process is as follows: first, a certain amount of desalted water is injected into the urea solution preparation tank, and the desalted water is heated to a set temperature by steam heating; the stirring device is turned on, and the bagged urea is manually transported to the bucket elevator, the bag is broken and poured into the hopper, and the bucket elevator is transported to the urea solution preparation tank for dissolution; during this period, it is necessary to pause the feeding according to the solution temperature and wait for the temperature to rise to a suitable temperature before continuing to feed; when the urea addition amount initially reaches the set value, the unloading pump is started for internal circulation, and the urea concentration is detected by a density meter; the urea solution concentration is adjusted to a designed concentration of about 50% by the urea feeding amount or desalted water; the circulation valve is closed to stop the circulation, and the delivery valve is opened to deliver the urea solution to the urea solution storage tank for use.

[0005] Therefore, there are at least the following problems in the existing urea solution preparation process: a large amount of manpower and material resources are required to carry out urea feeding work, which is time-consuming and laborious; the degree of automation in the preparation of urea solution is low and time-consuming, which leads to the equipment being easily hardened and corroded during the preparation process, and a large amount of ammonia odor is released, resulting in a poor working environment; the urea is not completely dissolved during the preparation of urea solution, and the solution concentration is not accurate. Summary of the invention

[0006] The object of the present invention is to provide a urea solution preparation device and method, which can reduce the manpower input in the urea solution preparation process, facilitate the rapid dissolution of urea granules, reduce the probability of equipment hardening and corrosion, and improve the solubility of urea granules, thereby improving the preparation efficiency and concentration accuracy.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0008] The present invention provides a urea solution preparation device, which comprises a gas-solid separation tank, a silo, an ejector, a feeder, a fluidizing hopper and a buffer tank;

[0009] The suction port of the gas-solid separation tank is used to suck urea particles through a suction pipeline, the discharge port of the gas-solid separation tank is connected to the inlet of the silo through a discharge pipeline, a discharge valve is provided on the discharge pipeline, and the exhaust port of the gas-solid separation tank is connected to the feed port of the ejector through a feed pipeline, and a feed valve is provided on the feed pipeline;

[0010] The outlet of the silo is connected to the inlet of the feeder, the outlet of the feeder is connected to the inlet of the fluidizing hopper, the outlet of the fluidizing hopper is connected to the feed inlet of the ejector through a feeding pipeline, and a feeding valve is provided on the feeding pipeline;

[0011] The liquid outlet of the ejector is connected to the liquid inlet of the buffer tank, the ejector port of the buffer tank is connected to the inlet of the jet pump through a jet pipeline, the outlet of the jet pump is connected to the liquid inlet of the ejector through an inlet pipeline, and the infusion port of the buffer tank is used to output urea solution to a urea solution storage tank through an infusion pipeline.

[0012] In some embodiments of the present application, the water supply port of the buffer tank is used to connect to the steam drain or hot water in the plant area through a water supply pipeline, and a water supply valve is provided on the water supply pipeline;

[0013] The inlet of the jet pump is also used to connect to the steam drain or hot water in the factory through a water injection pipeline, and a water injection valve is arranged on the water injection pipeline.

[0014] In some embodiments of the present application, the urea solution preparation device further includes a drain tank;

[0015] The water inlet of the drain tank is used to connect to the factory steam drain or hot water through the water inlet pipeline, and the water inlet pipeline is provided with a water inlet valve; the water outlet of the drain tank is connected to the water injection pipeline and the water replenishment pipeline through the water outlet pipeline, and the water outlet pipeline is provided with a flow meter.

[0016] In some embodiments of the present application, a heating element is provided in the drain tank.

[0017] In some embodiments of the present application, a delivery pump and a concentration meter are sequentially provided on the infusion pipeline.

[0018] In some embodiments of the present application, the first outlet of the infusion pipeline is used to output the urea solution to the urea solution storage tank through a delivery pipeline, and a delivery valve is provided on the delivery pipeline;

[0019] The second outlet of the infusion pipeline is connected to the reflux port of the buffer tank through a reflux pipeline, and a reflux valve is arranged on the reflux pipeline.

[0020] In some embodiments of the present application, a heater is provided in the buffer tank.

[0021] In some embodiments of the present application, a liquid level meter is also provided in the buffer tank.

[0022] The present invention further provides a method for preparing a urea solution, using the urea solution preparation device described in any of the above embodiments, the method for preparing a urea solution includes a urea granule feeding process and a urea solution preparation process:

[0023] Urea granule feeding process: inject hot water into the buffer tank until the liquid level reaches the set value, open the feeding valve and the jet pump, the hot water in the buffer tank passes through the jet pipeline and the liquid inlet pipeline into the ejector and then returns to the buffer tank, and forms a high negative pressure in the ejector, so that the feeding pipeline, the gas-solid separation tank and the suction pipeline generate suction, and the urea granules are sucked into the gas-solid separation tank for gas-solid separation. When the feeding in the gas-solid separation tank reaches the set value, close the feeding valve, open the discharge valve, and the urea granules in the gas-solid separation tank fall into the silo, completing the first cycle of gas-solid separation tank feeding and unloading.

[0024] After the unloading is completed, the unloading valve is closed, and the loading valve is opened to enter the next cycle of gas-solid separation tank loading and unloading. Through periodic operations until the loading is completed, the urea granules are stored in the urea granule silo for standby use;

[0025] Urea solution preparation process: After the liquid level and temperature in the buffer tank reach the set value, open the feeding valve and the jet pump, and the hot water in the buffer tank enters the ejector through the jet pipeline and the liquid inlet pipeline and then returns to the buffer tank, and forms a high negative pressure in the ejector, so that the feeding pipeline generates suction. The urea particles in the silo pass through the feeder and the fluidized hopper and are sucked into the ejector through the feeding pipeline to mix with the hot water to form a urea solution that enters the buffer tank. The buffer tank outputs the urea solution to the urea solution storage tank through the infusion pipeline.

[0026] It can be seen from the above technical solutions that the embodiments of the present invention have at least the following advantages and positive effects:

[0027] The urea solution preparation device of the embodiment of the present invention first has a urea granule feeding process, in which hot water is injected into the buffer tank until the liquid level reaches a set value, the feeding valve and the jet pump are opened, and the hot water in the buffer tank enters the ejector through the jet pipeline and the liquid inlet pipeline and then returns to the buffer tank, and forms a high negative pressure in the ejector, so that the feeding pipeline, the gas-solid separation tank and the suction pipeline generate suction, and the urea granules are sucked into the gas-solid separation tank for gas-solid separation. When the feeding in the gas-solid separation tank reaches the set value, the feeding valve is closed, and the unloading valve is opened, and the urea granules in the gas-solid separation tank fall into the silo, completing the first cycle of gas-solid separation tank feeding and unloading.

[0028] After the unloading is completed, the unloading valve is closed and the loading valve is opened to enter the next cycle of gas-solid separation tank loading and unloading. Through periodic operations until the loading is completed, the urea granules are stored in the urea granule silo for standby use.

[0029] The second is the urea solution preparation process. After the liquid level and temperature in the buffer tank reach the set value, the feeding valve and the jet pump are opened. The hot water in the buffer tank enters the ejector through the jet pipeline and the liquid inlet pipeline and then returns to the buffer tank, and forms a high negative pressure in the ejector, which generates suction in the feeding pipeline. The urea particles in the silo pass through the feeder and the fluidized hopper and are sucked into the ejector through the feeding pipeline to mix with the hot water to form a urea solution that enters the buffer tank. The buffer tank outputs the urea solution to the urea solution storage tank through the infusion pipeline.

[0030] Urea granule feeding, storage and dissolution preparation share a set of jet pump and ejector system. The high-pressure solution generated by the circulating jet pump passes through the ejector, forming a vacuum in the ejector contraction chamber, generating a strong suction force, and cooperating with the switching of the feeding valve and the feeding valve to realize different functions such as urea feeding storage and urea solution preparation, which greatly reduces the manpower input in the urea solution preparation process. After the urea granules are sucked into the ejector, they can be mixed and dissolved with hot water in the ejector, realizing dissolution as soon as they are fed, reducing the risk of equipment hardening and corrosion, and the solubility of urea granules in the ejector is improved, thereby improving the preparation efficiency and concentration accuracy.

[0031] The urea solution preparation method of the embodiment of the present invention adopts the above-mentioned urea solution preparation device, and reduces the manpower input in the urea solution preparation process through the urea granule feeding process and the urea solution preparation process, which is conducive to the rapid dissolution of urea, reduces the probability of equipment hardening and corrosion, and improves the solubility of urea granules, thereby improving the preparation efficiency and concentration accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various objects, features and advantages of the present invention will become more apparent by considering the following detailed description of preferred embodiments of the present invention in conjunction with the accompanying drawings. The accompanying drawings are merely exemplary illustrations of the present invention and are not necessarily drawn to scale. In the accompanying drawings, the same reference numerals always represent the same or similar parts.

[0033] in:

[0034] Figure 1 is a schematic structural diagram of a urea solution preparation device according to an exemplary embodiment.

[0035] The reference numerals are as follows: 1. gas-solid separation tank; 2. silo; 3. ejector; 4. feeder; 5. fluidizing hopper; 6. buffer tank; 61. heater; 7. drain tank; 71. heating element; 81. discharge valve; 82. loading valve; 83. feeding valve; 84. water supply valve; 85. water injection valve; 86. flow meter; 87. delivery pump; 88. concentration meter; 89. delivery valve; 90. return Flow valve; 91, suction pipeline; 92, unloading pipeline; 93, loading pipeline; 94, feeding pipeline; 95, jet pipeline; 96, liquid inlet pipeline; 97, liquid infusion pipeline; 98, water supply pipeline; 99, water injection pipeline; 100, water inlet pipeline; 101, water outlet pipeline; 102, delivery pipeline; 103, return pipeline; 104, water inlet valve; 105, controller; 106, jet pump. DETAILED DESCRIPTION

[0036] Although the present invention can be easily embodied in different forms of embodiments, only some of the specific embodiments are shown in the drawings and will be described in detail in this specification. It should be understood that this description should be regarded as an exemplary illustration of the principles of the invention and is not intended to limit the invention to that described herein.

[0037] Thus, a feature indicated in this specification will be used to illustrate one of the features of an embodiment of the present invention, rather than implying that each embodiment of the present invention must have the described feature. In addition, it should be noted that this specification describes many features. Although some features can be combined together to illustrate possible system designs, these features can also be used in other combinations that are not explicitly described. Thus, unless otherwise stated, the described combinations are not intended to be limiting.

[0038] In the embodiments shown in the drawings, the indications of directions (such as up, down, left, right, front and back) used to explain the structure and movement of various elements of the present invention are not absolute but relative. These descriptions are appropriate when these elements are in the positions shown in the drawings. If the description of the positions of these elements changes, the indications of these directions also change accordingly.

[0039] See also Figure 1 The urea solution preparation device mainly includes a gas-solid separation tank 1, a silo 2, an ejector 3, a feeder 4, a fluidizing hopper 5 and a buffer tank 6.

[0040] The suction port of the gas-solid separation tank 1 is used to suck urea particles through the suction pipeline 91, the discharge port of the gas-solid separation tank 1 is connected to the inlet of the silo 2 through the discharge pipeline 92, and the discharge pipeline 92 is provided with a discharge valve 81, and the exhaust port of the gas-solid separation tank 1 is connected to the feed port of the ejector 3 through the feeding pipeline 93, and the feeding pipeline 93 is provided with a feeding valve 82.

[0041] The outlet of the silo 2 is connected to the inlet of the feeder 4 , the outlet of the feeder 4 is connected to the inlet of the fluidizing hopper 5 , the outlet of the fluidizing hopper 5 is connected to the feed port of the ejector 3 through a feeding pipeline 94 , and a feeding valve 83 is provided on the feeding pipeline 94 .

[0042] The liquid outlet of the ejector 3 is connected to the liquid inlet of the buffer tank 6, the ejection port of the buffer tank 6 is connected to the inlet of the jet pump 106 through the jet pipeline 95, the outlet of the jet pump 106 is connected to the liquid inlet of the ejector 3 through the liquid inlet pipeline 96, and the infusion port of the buffer tank 6 is used to output urea solution to the urea solution storage tank through the infusion pipeline 97.

[0043] The method of using the urea solution preparation device is divided into two processes. The first is the urea granule feeding process. Hot water is injected into the buffer tank 6 until the liquid level reaches the set value, the feeding valve 82 and the jet pump 106 are opened, and the hot water in the buffer tank 6 enters the ejector 3 through the jet pipeline 95 and the liquid inlet pipeline 96 and then returns to the buffer tank 6, and forms a high negative pressure in the ejector 3, so that the feeding pipeline 93, the gas-solid separation tank 1 and the suction pipeline 91 generate suction, and the urea granules are sucked into the gas-solid separation tank 1 for gas-solid separation. When the feeding in the gas-solid separation tank 1 reaches the set value, for example but not limited to the feeding time reaching the set value, or the pressure in the gas-solid separation tank 1 reaches the set value, the feeding valve 82 is closed, and the discharge valve 81 is opened, and the urea granules in the gas-solid separation tank 1 fall into the silo 2, completing the first cycle of gas-solid separation tank 1 feeding and unloading.

[0044] After the unloading is completed, the unloading valve 81 is closed and the loading valve 82 is opened to enter the next cycle of gas-solid separation tank 1 loading and unloading. Through periodic operation until the loading is completed, the urea granules are stored in the urea granule silo 2 for standby use.

[0045] Next is the urea solution preparation process. After the liquid level and temperature in the buffer tank 6 reach the set value, the feed valve 83 and the jet pump 106 are opened, and the hot water in the buffer tank 6 enters the ejector 3 through the jet pipeline 95 and the liquid inlet pipeline 96 and then returns to the buffer tank 6, and forms a high negative pressure in the ejector 3, so that the feed pipeline 94 generates suction. The urea particles in the silo 2 pass through the feeder 4 and the fluidized hopper 5, and are sucked into the ejector 3 through the feed pipeline 94, mixed with the hot water to form a urea solution and enter the buffer tank 6. The buffer tank 6 outputs the urea solution to the urea solution storage tank through the infusion pipeline 97.

[0046] Urea granule feeding, storage and dissolution preparation share a set of jet pump 106 and ejector 3 system. The high-pressure solution generated by the jet pump 106 passes through the ejector 3, forming a vacuum in the contraction chamber of the ejector 3, generating a strong suction force, and cooperating with the switching of the feeding valve 82 and the feeding valve 83 to realize different functions such as urea feeding storage and urea solution preparation, greatly reducing the manpower input in the urea solution preparation process. After being sucked into the ejector 3, the urea granules can be mixed and dissolved with hot water in the ejector 3, realizing dissolution as feeding, reducing the risk of equipment hardening and corrosion, and the solubility of urea granules in the ejector 3 is improved, thereby improving the preparation efficiency and concentration accuracy.

[0047] The use of the ejector 3 to prepare the urea solution instead of the traditional manual feeding and mechanical stirring and dissolving device can greatly reduce the land occupation, investment cost and operating energy consumption of the urea solution precision preparation system, with a high degree of automation, and can realize the precise preparation of urea solution of the required concentration.

[0048] The water supply port of the buffer tank 6 is used to connect the steam drain or hot water in the plant area through the water supply pipeline 98. The water supply pipeline 98 is provided with a water supply valve 84. When the water supply valve 84 is opened, the steam drain or hot water in the plant area can be injected into the buffer tank 6 through the water supply pipeline 98. The water supply valve 84 can be a regulating valve, which can open or close the water supply pipeline 98 and adjust the flow rate of the water supply pipeline 98.

[0049] The inlet of the jet pump 106 is also used to connect the steam drain or hot water in the plant area through the water injection pipeline 99, and a water injection valve 85 is provided on the water injection pipeline 99. When the water injection valve 85 is opened, the steam drain or hot water in the plant area can be injected into the buffer tank 6 through the water injection pipeline 99. The water injection valve 85 can be a regulating valve, which can open or close the water injection pipeline 99 and adjust the flow rate of the water injection pipeline 99.

[0050] The urea solution preparation device also includes a drain tank 7, a water inlet of the drain tank 7 is used to connect to the factory steam drain or hot water through a water inlet pipeline 100, an inlet valve 104 is provided on the water inlet pipeline 100, and a water outlet of the drain tank 7 is connected to the water injection pipeline 99 and the water replenishment pipeline 98 through a water outlet pipeline 101, and a flow meter 86 is provided on the water outlet pipeline 101.

[0051] The drain tank 7 can store sufficient steam drain or hot water in the plant area to replenish water for the buffer tank 6 before loading, and provide water mixed with urea particles for the ejector 3 during loading. The flow meter 86 can measure the water flow on the water outlet pipeline 101.

[0052] A heating element 71 is provided in the drain tank 7. The heating element 71 is used to heat the water in the drain tank 7. The heating element 71 is used to heat the water in the drain tank 7 to increase the solubility of urea particles in water. A drain tank 7 liquid level gauge can also be provided in the drain tank 7.

[0053] The infusion pipeline 97 is provided with a delivery pump 87 and a concentration meter 88 in sequence. The delivery pump 87 is used to provide power for the infusion port of the buffer tank 6 to pump the urea solution outward. The concentration meter 88 can detect the concentration of the urea solution in real time.

[0054] The first outlet of the infusion pipeline 97 is used to output urea solution to the urea solution storage tank through the delivery pipeline 102, and the delivery valve 89 is provided on the delivery pipeline 102. The second outlet of the infusion pipeline 97 is connected to the reflux port of the buffer tank through the reflux pipeline 103, and the reflux valve 90 is provided on the reflux pipeline 103.

[0055] A heater 61 is provided in the buffer tank 6. The heater 61 is used to heat the liquid in the buffer tank 6. Urea has limited solubility in water and is prone to crystallization at low temperatures, so it is necessary to pay attention to the temperature of the urea solution in real time. Heating by the heater 61 is conducive to improving the solubility of urea particles in water. The heater 61 and the heating element 71 can be electrically heated or steam heated.

[0056] A liquid level meter is also provided in the buffer tank 6. The liquid level meter is used to measure the liquid level height in the buffer tank 6.

[0057] Based on the above embodiments, the urea granule feeding process and the urea solution preparation process of the urea solution preparation device can be specifically improved as follows.

[0058] Urea granule feeding process: open the water supply valve 84, and the hot water from the drain tank 7 enters the buffer tank 6 through the outlet pipe 101 and the water supply pipe 98. After the liquid level of the urea solution buffer tank 6 reaches the set value, close the water supply valve 84.

[0059] Open the feeding valve 82 and the jet pump 106, the hot water in the buffer tank 6 enters the ejector 3 through the jet pipeline 95 and the liquid inlet pipeline 96 and then returns to the buffer tank 6, and forms a high negative pressure in the ejector 3, so that the feeding pipeline 93, the gas-solid separation tank 1 and the suction pipeline 91 generate suction, and the urea particles are sucked into the gas-solid separation tank 1 for gas-solid separation. When the feeding in the gas-solid separation tank 1 reaches the set value, the feeding valve 82 is closed, and the unloading valve 81 is opened, and the urea particles in the gas-solid separation tank 1 fall into the silo 2, completing the first cycle of feeding and unloading of the gas-solid separation tank 1.

[0060] After the unloading is completed, the unloading valve 81 is closed and the loading valve 82 is opened to enter the next cycle of gas-solid separation tank 1 loading and unloading. Through periodic operation until the loading is completed, the urea granules are stored in the urea granule silo 2 for standby use.

[0061] Urea solution preparation process: After the liquid level and temperature in the buffer tank 6 reach the set value, the feeding valve 83 and the jet pump 106 are opened, and the hot water in the buffer tank 6 enters the ejector 3 through the jet pipeline 95 and the liquid inlet pipeline 96 and then returns to the buffer tank 6, and forms a high negative pressure in the ejector 3, so that the feeding pipeline 94 generates suction. The urea particles in the silo 2 pass through the feeder 4 and the fluidized hopper 5, and then are sucked into the ejector 3 through the feeding pipeline 94 to mix with the hot water to form a urea solution and enter the buffer tank 6.

[0062] The delivery pump 87 and the reflux valve 90 are turned on, and the urea solution forms a reflux through the delivery pipeline and the reflux pipeline, and the circulating turbulent water flow is used to further dissolve the small amount of undissolved urea particles that may exist. The concentration meter 88 is used to detect whether the concentration of the urea solution reaches the set value. When the concentration of the urea solution reaches the set value, the reflux valve 90 is closed, the delivery valve 89 is opened, and the buffer tank 6 outputs the urea solution to the urea solution storage tank through the delivery pipeline 97 and the delivery pipeline 102. The water injection valve 85 is opened synchronously, and the opening is adjusted so that the hot water flow reaches the set value.

[0063] During the preparation of the urea solution, the hot water flow rate remains basically unchanged, and is fine-tuned according to the changes in the concentration of the urea solution to ensure that the concentration of the prepared urea solution is stable. Specifically, in order to better control the concentration of the urea solution at a set value of about 50% during normal operation, the water inlet flow rate and the urea feed amount are generally kept unchanged during normal operation, that is, the opening of the water injection valve 85 and the feeder 4 remain unchanged. The opening of the water injection valve 85 is fine-tuned according to the changes in the concentration of the urea solution.

[0064] The system is provided with a controller 105, and automatic control is performed by setting relevant parameters through the controller 105, so that automatic interlocking control of relevant valves, equipment and instruments can be realized.

[0065] The device integrates urea feeding, storage and urea solution preparation. The device is highly integrated and has the advantages of low labor intensity in urea feeding operation, fast and continuous preparation of urea solution, precise and controllable concentration, and high degree of automation.

[0066] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A urea solution preparation device, characterized in that: It includes gas-solid separation tank, silo, ejector, feeder, fluidizing hopper and buffer tank; The suction port of the gas-solid separation tank is used to suck urea particles through a suction pipeline, the discharge port of the gas-solid separation tank is connected to the inlet of the silo through a discharge pipeline, a discharge valve is provided on the discharge pipeline, and the exhaust port of the gas-solid separation tank is connected to the feed port of the ejector through a feed pipeline, and a feed valve is provided on the feed pipeline; The outlet of the silo is connected to the inlet of the feeder, the outlet of the feeder is connected to the inlet of the fluidizing hopper, the outlet of the fluidizing hopper is connected to the feed inlet of the ejector through a feeding pipeline, and a feeding valve is provided on the feeding pipeline; The liquid outlet of the ejector is connected to the liquid inlet of the buffer tank, the ejector port of the buffer tank is connected to the inlet of the jet pump through a jet pipeline, the outlet of the jet pump is connected to the liquid inlet of the ejector through an inlet pipeline, and the infusion port of the buffer tank is used to output urea solution to a urea solution storage tank through an infusion pipeline.

2. The urea solution preparation device according to claim 1, characterized in that: The water supply port of the buffer tank is used to connect to the steam drain or hot water in the factory area through a water supply pipeline, and a water supply valve is provided on the water supply pipeline; The inlet of the jet pump is also used to connect to the steam drain or hot water in the factory through a water injection pipeline, and a water injection valve is arranged on the water injection pipeline.

3. The urea solution preparation device according to claim 2, characterized in that: The urea solution preparation device also includes a drain tank; The water inlet of the drain tank is used to connect to the factory steam drain or hot water through the water inlet pipeline, and the water inlet pipeline is provided with a water inlet valve; the water outlet of the drain tank is connected to the water injection pipeline and the water replenishment pipeline through the water outlet pipeline, and the water outlet pipeline is provided with a flow meter.

4. The urea solution preparation device according to claim 3, characterized in that: A heating element is arranged in the drain tank.

5. The urea solution preparation device according to claim 1, characterized in that: The infusion pipeline is provided with a delivery pump and a concentration meter in sequence.

6. The urea solution preparation device according to claim 1, characterized in that: The first outlet of the infusion pipeline is used to output the urea solution to the urea solution storage tank through a delivery pipeline, and a delivery valve is provided on the delivery pipeline; The second outlet of the infusion pipeline is connected to the reflux port of the buffer tank through a reflux pipeline, and a reflux valve is arranged on the reflux pipeline.

7. The urea solution preparation device according to claim 1, characterized in that: A heater is arranged in the buffer tank.

8. The urea solution preparation device according to claim 7, characterized in that: A liquid level meter is also provided in the buffer tank.

9. A method for preparing a urea solution, using the urea solution preparation device according to any one of claims 1 to 8, characterized in that: Including urea granule feeding process and urea solution preparation process: Urea granule feeding process: inject hot water into the buffer tank until the liquid level reaches the set value, open the feeding valve and the jet pump, the hot water in the buffer tank passes through the jet pipeline and the liquid inlet pipeline into the ejector and then returns to the buffer tank, and forms a high negative pressure in the ejector, so that the feeding pipeline, the gas-solid separation tank and the suction pipeline generate suction, and the urea granules are sucked into the gas-solid separation tank for gas-solid separation. When the feeding in the gas-solid separation tank reaches the set value, close the feeding valve, open the discharge valve, and the urea granules in the gas-solid separation tank fall into the silo, completing the first cycle of gas-solid separation tank feeding and unloading. After the unloading is completed, the unloading valve is closed and the loading valve is opened to enter the next cycle of gas-solid separation tank loading and unloading. Through periodic operations until the loading is completed, the urea granules are stored in the silo for standby use; Urea solution preparation process: After the liquid level and temperature in the buffer tank reach the set value, open the feeding valve and the jet pump, and the hot water in the buffer tank enters the ejector through the jet pipeline and the liquid inlet pipeline and then returns to the buffer tank, and forms a high negative pressure in the ejector, so that the feeding pipeline generates suction. The urea particles in the silo pass through the feeder and the fluidized hopper and are sucked into the ejector through the feeding pipeline to mix with the hot water to form a urea solution that enters the buffer tank. The buffer tank outputs the urea solution to the urea solution storage tank through the infusion pipeline.

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