Urea preparation system based on SCR (Selective Catalytic Reduction) catalytic system

Abstract

The utility model relates to the field of environmental protection, and discloses a urea preparation system based on an SCR (Selective Catalytic Reduction) catalytic system, which comprises a urea dissolving unit, a urea storage unit and a heat exchange unit, a urea solution prepared by the urea dissolving unit is output to the urea storage unit for storage; the urea dissolving unit comprises a urea dissolving tank, and a first heating pipeline and a second heating pipeline are arranged in the urea dissolving tank; a heat source of the first heating pipeline is water vapor; the heat exchange unit comprises a heat exchanger and a fan, the fan is used for injecting air into a tube pass of the heat exchanger, and the heat exchanger is arranged at a flue outlet of the SCR catalysis unit; and an outlet of the heat exchanger is connected to the second heating pipeline. According to the system, high-temperature flue gas at the flue outlet of the SCR catalysis unit is used for heating air, heat is supplied to the urea dissolving process through the air, and the consumption of water vapor is effectively reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to environmental protection equipment technical field, concretely relates to a urea preparation system based on SCR catalytic system. BACKGROUND

[0002] Patent application publication number CN115650252A, subject is a kind of heat ladder utilization system and method for preparing ammonia by hydrolysis of denitration urea, it is disclosed to prepare urea using urea dissolving tank, urea solution storage tank.The dissolution of urea is an endothermic process.The process of urea dissolving in water includes two stages of diffusion and hydration.The diffusion process is endothermic, while the hydration process is exothermic.However, when urea dissolves, the heat absorbed by the diffusion process is greater than the heat released by the hydration process, so the overall process is endothermic.

[0003] In the production process, it requires a lot of energy to dissolve urea and control urea in a constant temperature state. The traditional method uses water vapor heating to provide heat for the urea dissolution process. This method is not energy efficient. UTILITY MODEL CONTENT

[0004] The utility model aims at solving above-mentioned problem, provides a kind of urea preparation system based on SCR catalytic system, the high-temperature flue gas of the flue outlet of the SCR catalytic unit is used to heat air in the system, air is used to heat urea dissolution process, effectively reduce the consumption of water vapor.

[0005] To achieve the above object, the utility model provides the following technical scheme:

[0006] A urea preparation system based on SCR catalytic system, comprising a urea dissolving unit, a urea storage unit and a heat exchange unit. The urea solution prepared by the urea dissolving unit is output to the urea storage unit for storage. The urea dissolving unit comprises a urea dissolving tank, which is provided with a first heating pipeline and a second heating pipeline. The heat source of the first heating pipeline is water vapor. The heat exchange unit comprises a heat exchanger and a fan, which is used to inject air into the tube side of the heat exchanger. The heat exchanger is placed at the position of the flue outlet of the SCR catalytic unit. The outlet of the heat exchanger is connected to the second heating pipeline.

[0007] The utility model uses two sets of heat sources to heat the urea dissolving unit. One of the heat sources is derived from the flue gas of the flue outlet of the SCR catalytic unit. Since the residual heat of the flue gas is large, and the amount of urea solution preparation process and flue gas is relatively small, the use of limited heat of flue gas can quickly prepare urea solution without significantly causing the fluctuation of flue gas at the flue outlet of the SCR catalytic unit.

[0008] During the trial operation, good energy-saving effect is achieved.

[0009] In the urea preparation system based on the SCR catalytic system, the first heating pipeline and the second heating pipeline are both coil pipes; the first heating pipeline is located outside the second heating pipeline or the first heating pipeline is located inside the second heating pipeline.

[0010] In the urea preparation system based on the SCR catalytic system, a stirrer is further arranged in the urea dissolving unit; a water injection port and a urea injection port are arranged on the urea dissolving unit.

[0011] In the urea preparation system based on the SCR catalytic system, the urea injection port is connected with a bucket elevator for injecting urea.

[0012] In the urea preparation system based on the SCR catalytic system, a water adding pipeline is further arranged, a urea dissolving pump is arranged between the urea dissolving unit and the urea storage unit; the water adding pipeline is connected to the water injection port and the outlet of the urea dissolving pump; a first valve is arranged on the water adding pipeline to control the water amount entering the outlet of the urea dissolving pump.

[0013] In the urea preparation system based on the SCR catalytic system, a first discharge pipeline is arranged at the inlet of the urea dissolving pump, and a second discharge pipeline is arranged at the bottom of the urea dissolving tank; the first discharge pipeline and the second discharge pipeline are connected to an external sewage treatment system; a circulation pipeline is arranged between the outlet of the urea dissolving pump and the urea dissolving tank.

[0014] In the urea preparation system based on the SCR catalytic system, the urea storage unit comprises one or more urea storage tanks, and a third heating pipeline is arranged in each urea storage tank; the heat source of the third heating pipeline is water vapor or tail gas output by the second heating pipeline.

[0015] In the urea preparation system based on the SCR catalytic system, a urea concentration detection module is arranged in the urea storage unit, and the urea concentration detection module is linked with the first valve.

[0016] Compared with the prior art, the urea preparation system based on the SCR catalytic system has the following beneficial effects:

[0017] The urea dissolving unit is heated by two sets of heat sources, one of which is derived from the flue gas at the outlet of the SCR catalytic unit, and the other is derived from the tail gas at the outlet of the second heating pipeline; the amount of the flue gas is relatively small compared with the amount of the tail gas, and the limited heat of the flue gas can be used to quickly prepare the urea solution without causing significant fluctuations in the flue gas at the outlet of the SCR catalytic unit. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a structural diagram of Example 1. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all the other embodiments obtained by the ordinary skilled in the art without creative labor belong to the protection scope of the utility model.

[0020] Example 1

[0021] Reference Figure 1 A urea preparation system based on an SCR catalytic system, comprising a urea dissolving unit 1, a urea storage unit 2, and a heat exchange unit 3. The urea solution prepared by the urea dissolving unit 1 is output to the urea storage unit 2 for storage. The urea dissolving unit 1 comprises a urea dissolving tank 11, which is provided with a first heating pipeline 12 and a second heating pipeline 13. The heat source of the first heating pipeline 12 is water vapor. The heat exchange unit 3 comprises a heat exchanger 31 and a fan 32. The fan 32 is used to inject air into the tube side of the heat exchanger 31. The heat exchanger 31 is arranged at the position of the flue outlet of the SCR catalytic unit 4. The outlet of the heat exchanger 31 is connected to the second heating pipeline 13.

[0022] The urea dissolving unit 1 is heated by two sets of heat sources. One of the heat sources is derived from the flue gas at the flue outlet of the SCR catalytic unit 4. Since the residual heat of the flue gas is large, and the amount of the flue gas is relatively small compared with the preparation process of the urea solution, the urea solution can be quickly prepared by using the limited heat of the flue gas, and the fluctuation of the flue gas at the flue outlet of the SCR catalytic unit 4 is not obvious. In the trial operation process, good energy-saving effect is achieved.

[0023] In the production process, the power of the fan 32 is controlled to control the flow speed of the hot gas in the second heating pipeline 13. After heat exchange by the heat exchanger 31, the temperature of the air can reach 200℃ or above, which is a relatively high-quality heat source. In the dissolving process, the air flow is controlled. The flow control is to maintain the temperature of the urea solution in the urea dissolving unit 1 at 55±5℃. The whole preparation process is a continuous process accompanied by stirring. The prepared urea solution is pumped into the urea storage unit 2 by a urea pump. The urea storage unit 2 also needs auxiliary heating to control the constant temperature.

[0024] In the normal production process, the second heating pipeline 13 is mainly used for heating; the first heating pipeline 12 is used for heating before the balance of the SCR catalytic unit 4 itself is established; and the first heating pipeline 12 and the second heating pipeline 13 are used for heating simultaneously in the case that the urea production requirement is high.

[0025] Preferably, the first heating pipeline 12 and the second heating pipeline 13 are both coils; the first heating pipeline 12 is located outside the second heating pipeline 13 or the first heating pipeline 12 is located inside the second heating pipeline 13.

[0026] The above-mentioned coil is a spiral coil, and the first heating pipeline 12 and the second heating pipeline 13 are arranged in the form of inside and outside nesting, which is beneficial to installation and maintenance. In the embodiment, the second heating pipeline 13 is arranged outside the first heating pipeline 12, which has a larger contact area.

[0027] Preferably, the urea dissolving unit 1 is further provided with a stirrer 14; the urea dissolving unit 1 is provided with a water injection port 15 and a urea injection port 16, the urea injection port 16 is connected with a bucket elevator 17 for adding urea, and further comprises a water adding pipe 18, the urea dissolving unit 1 and the urea storage unit 2 are provided with a urea dissolving pump 19; the water adding pipe 18 is connected to the water injection port 15 and the outlet of the urea dissolving pump 19; the water adding pipe 18 is provided with a first valve 10 to control the amount of water entering the outlet of the urea dissolving pump 19.

[0028] The water adding pipe 18 is mainly used for supplying water to the urea dissolving tank 11, and the water supply process is a continuous water supply process; in addition, the water adding pipe 18 also needs to be responsible for supplying water to the outlet of the urea dissolving pump 19, which can be continuous or intermittent, and is used to regulate the concentration of the urea solution in the urea storage unit 2; more specifically, the urea storage unit 2 comprises one or more urea storage tanks 21, the urea storage tank 21 is provided with a third heating pipeline 22; the heat source of the third heating pipeline 22 is water vapor or tail gas output by the second heating pipeline 13; the urea storage unit 2 is provided with a urea concentration detection module 23, and the urea concentration detection module and the first valve 10 are linked.

[0029] In the embodiment, the heat source of the third heating pipeline 22 is preferably the tail gas output by the second heating pipeline 13; in a more preferred scheme, two third heating pipelines 22 are arranged in parallel in the urea storage tank 21, one of which uses water vapor for heating, and the other uses tail gas output by the second heating pipeline 13 for heating, and in actual operation, the latter is mainly used for heating.

[0030] Preferably, the inlet of the urea dissolving pump 19 is provided with a first discharge pipe 100, the bottom of the urea dissolving tank 11 is provided with a second discharge pipe 110; the first discharge pipe 100 and the second discharge pipe 110 are connected to a sewage treatment system outside; a circulation pipe 120 is arranged between the outlet of the urea dissolving pump 19 and the urea dissolving tank 11.

[0031] The above merely describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements or modifications without departing from the principles of the present application, and these improvements or modifications should also be considered as the protection scope of the present application.

Claims

1. A urea preparation system based on an SCR catalytic system, comprising a urea dissolution unit, a urea storage unit, and a heat exchange unit, wherein the urea solution prepared by the urea dissolution unit is output to the urea storage unit for storage; characterized in that, The urea dissolving unit includes a urea dissolving tank, which is equipped with a first heating pipe and a second heating pipe. The heat source for the first heating pipe is steam. The heat exchange unit includes a heat exchanger and a fan. The fan is used to inject air into the tube side of the heat exchanger. The heat exchanger is located at the flue outlet of the SCR catalytic unit. The outlet of the heat exchanger is connected to the second heating pipe.

2. The urea preparation system based on an SCR catalytic system according to claim 1, characterized in that, Both the first heating pipe and the second heating pipe are coils; the first heating pipe is located outside the second heating pipe or inside the second heating pipe.

3. The urea preparation system based on an SCR catalytic system according to claim 1, characterized in that, The urea dissolving unit is also equipped with a stirrer; the urea dissolving unit is equipped with a water inlet and a urea injection port.

4. The urea preparation system based on an SCR catalytic system according to claim 3, characterized in that, The urea filling port is connected to a bucket elevator for filling urea.

5. The urea preparation system based on an SCR catalytic system according to claim 3, characterized in that, It also includes a water inlet pipe, and a urea dissolving pump is provided between the urea dissolving unit and the urea storage unit; the water inlet pipe is connected to the water inlet and the outlet of the urea dissolving pump; a first valve is provided on the water inlet pipe to control the amount of water entering the outlet of the urea dissolving pump.

6. The urea preparation system based on an SCR catalytic system according to claim 5, characterized in that, The urea dissolving pump has a first discharge pipe at its inlet and a second discharge pipe at the bottom of the urea dissolving tank; the first discharge pipe and the second discharge pipe are connected to an external sewage treatment system; a circulation pipe is provided between the outlet of the urea dissolving pump and the urea dissolving tank.

7. The urea preparation system based on an SCR catalytic system according to claim 5, characterized in that, The urea storage unit includes one or more urea storage tanks, and a third heating pipe is provided inside the urea storage tank; the heat source of the third heating pipe is steam or exhaust gas output from the second heating pipe.

8. The urea preparation system based on an SCR catalytic system according to claim 7, characterized in that, The urea storage unit is equipped with a urea concentration detection module, which is linked to the first valve.

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