A system and method for separating water vapor from urea hydrolysis product gas

Abstract

This disclosure relates to a system and method for separating water vapor from urea hydrolysis product gas. The method includes the following steps: the product gas after urea hydrolysis is fed into a water vapor separator through a product gas channel for separation treatment, yielding water vapor and separated gas; the water vapor is condensed and recovered; the separated gas is fed into an ammonia mixed gas distributor through a separated gas channel for flue gas denitrification. The system of this disclosure uses a hydrophobic microporous filter membrane for water vapor separation in the product gas. Using this system, continuous separation of the product gas can be achieved, with stable separation effect, high separation efficiency, and high separation purity, which is beneficial for improving the utilization efficiency of ammonia. The system of this disclosure has a simple structure, is easy to operate, has low separation energy consumption, and saves energy and costs.

Description

Technical Field

[0001] This disclosure relates to the technical field of chemical product separation, specifically to a system and method for separating water vapor from urea hydrolysis product gas. Background Technology

[0002] Currently, over 95% of coal-fired power generating units in China use Selective Catalytic Reduction (SCR) flue gas denitrification technology to reduce NOx emissions. The reducing agent is ammonia, which mainly comes from ammonia water, liquid ammonia, and urea. In existing thermal power generating units, the ammonia reducing agent for SCR denitrification primarily comes from liquid ammonia. However, my country currently classifies liquid ammonia storage exceeding 10 tons as a major hazard source, and the on-site storage generally exceeds 10 tons, making the ammonia station the sole major hazard source in the power plant, leading to stricter control measures. SCR flue gas denitrification processes can be categorized according to the storage and preparation methods of the reducing agent: liquid ammonia method, urea pyrolysis method, and urea hydrolysis method. Among these, the urea hydrolysis method, which uses steam as a heating source, offers better operational economy and higher safety, and is therefore gaining increasing attention. Consequently, the previously widely used liquid ammonia denitrification method has been largely replaced by the urea hydrolysis method for ammonia production. The reaction equations for the hydrolysis of urea are as follows, which involve two steps: CO(NH2)2 + H2O = NH2COONH4, NH2COONH4 = 2NH3 + CO2.

[0003] Urea hydrolysis requires reaching a certain temperature within the hydrolyzer to proceed, producing NH3 and CO2. This reaction is reversible. The typical conditions for urea hydrolysis include a temperature of 130–180℃ and a pressure of 0.30–0.6 MPa. The resulting mixed gas is called "product gas," which contains a large amount (nearly half) of water and carbon dioxide. These "useless" products, when injected into the flue gas duct, will have a series of adverse effects: lowering the temperature of the high-temperature flue gas, reducing its heat release capacity, decreasing the efficiency of the air preheater, and increasing exhaust heat loss; increasing the flue gas volume and increasing the power consumption of the induced draft fan; downstream in the flue gas duct, as the flue gas temperature decreases, the increased moisture content of the flue gas increases, increasing corrosion of equipment along the process path, especially low-temperature corrosion; simultaneously, for low-temperature electrostatic precipitators, it increases the risk of ash accumulating on the electrodes and plates, affecting the electrostatic precipitator's discharge capacity and thus reducing its dust collection capacity. This reduces boiler thermal efficiency, increases losses, and overall reduces energy utilization efficiency. In addition, the product gas outlet temperature of the hydrolysis reactor is 130℃~160℃. When the temperature of the product gas drops to a certain level, water vapor condensation and reverse reaction crystallization will occur. Water vapor condensation will aggravate pipe corrosion, and the aminomethylamine produced by the reverse reaction will clog pipes, valves, instruments, etc., causing the system to malfunction.

[0004] Currently, the main technologies for separating water vapor include condensation, rotary evaporation, and adsorption. These separation technologies have drawbacks such as high energy consumption, complex equipment, unstable separation effect, low separation purity, and inability to perform continuous separation. Summary of the Invention

[0005] The purpose of this disclosure is to overcome the technical problems of existing water vapor separation technology, such as high energy consumption, complex equipment, unstable separation effect, low separation purity, and inability to perform continuous separation, and to provide a water vapor separation system and method for urea hydrolysis product gas.

[0006] To achieve the above objectives, the first aspect of this disclosure provides a water vapor separation system for urea hydrolysis product gas, the water vapor separation system comprising a product gas channel, a water vapor filtration unit, and a separated gas channel; the water vapor filtration unit includes a water vapor separator.

[0007] The water vapor separator includes a separator shell, on the outer surface of which a first heat insulation layer is provided; inside the separator shell are a first distributor and a second distributor arranged vertically, and a filter membrane arranged horizontally; the inlet of the filter membrane is connected to the product gas outlet of the first distributor, and the outlet of the filter membrane is connected to the separation gas inlet of the second distributor.

[0008] The product gas inlet of the first distributor of the water vapor separator is connected to the product gas outlet of the urea hydrolysis unit through a product gas channel; the outlet of the second distributor of the water vapor separator is connected to the inlet of the ammonia air mixer of the denitrification system through a separation gas channel.

[0009] Optionally, multiple filter membranes are provided, each filter membrane having a processing capacity of 10-20 Nm³. 3 / h; preferably, when the product gas flow rate is 100-200 Nm 3 When the filter membrane is used, the number of filters is 5-20 per hour.

[0010] Optionally, each of the first distributors is provided with a plurality of product gas outlets, preferably 5-20; each of the second distributors is provided with a plurality of separation gas inlets, preferably 5-20.

[0011] Optionally, the filter membrane is a hydrophobic microporous membrane; preferably, the filter membrane is selected from spiral wound GORE-TEX membrane or superhydrophobic polyimide fiber membrane.

[0012] Optionally, the water vapor filtration unit further includes a water vapor exhaust channel and a water vapor condenser; the water vapor exhaust channel includes a channel shell, the top of which is connected to the bottom of the separator shell, and the water vapor outlet at the bottom of the separator shell is connected to the water vapor inlet at the top of the channel shell, so that the water vapor separated in the water vapor separator enters the water vapor exhaust channel; the bottom of the channel shell is connected to the top of the water vapor condenser, and the water vapor outlet at the bottom of the channel shell is connected to the water vapor inlet at the top of the water vapor condenser, so that the water vapor in the water vapor exhaust channel enters the water vapor condenser; the condenser is provided with a cooling medium pipeline for condensing water vapor into water; the top and side walls of the channel shell are each independently provided with a second insulation layer.

[0013] Optionally, a vacuum pump is provided at the bottom of the channel housing.

[0014] Optionally, the outer wall of the product gas channel is provided with a product gas insulation layer, and a first hygrometer, a first thermometer, and a first pressure gauge are sequentially arranged on the product gas channel along the direction of product gas flow. The first hygrometer, the first thermometer, and the first pressure gauge are used to measure the humidity, temperature, and pressure of the gas in the product gas channel, respectively, and the temperature of the product gas insulation layer is adjusted according to the temperature signal measured by the first thermometer. The outer wall of the separation gas channel is provided with a separation gas insulation layer, and a second thermometer, a second pressure gauge, and a second hygrometer are sequentially arranged on the separation gas channel along the direction of separation gas flow. The second thermometer, the second pressure gauge, and the second hygrometer are used to measure the temperature, pressure, and humidity of the mixed gas in the separation gas channel, respectively, and the temperature of the separation gas insulation layer is adjusted according to the temperature signal measured by the second thermometer.

[0015] The second aspect of this disclosure provides a method for separating water vapor from urea hydrolysis product gas using the system described in the first aspect. The method includes the following steps: allowing the product gas after urea hydrolysis to enter a water vapor separator through a product gas channel for separation treatment to obtain water vapor and separated gas.

[0016] Optionally, the separation process is carried out at a temperature of 130-160℃.

[0017] Optionally, the method further includes: allowing the separated gas to enter the ammonia-air mixer of the denitrification system through the separated gas channel for flue gas denitrification; and allowing water vapor to enter the water vapor condenser through the water vapor exhaust channel to condense the water vapor into water.

[0018] The present disclosure has the following beneficial effects through the above technical solution:

[0019] (1) The water vapor separation gas of the system disclosed herein adopts a hydrophobic microporous filter membrane. Using this system, continuous separation of product gas can be achieved, the separation effect is stable, the separation efficiency is high, and the separation purity is high, which is conducive to the recovery and utilization of ammonia.

[0020] (2) The system disclosed herein has a simple structure, is easy to operate, is green and environmentally friendly, has low separation energy consumption, and saves energy and costs.

[0021] Other features and advantages of the present disclosure will be described in detail in the following detailed description. Attached Figure Description

[0022] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of one implementation of a water vapor separation system for urea hydrolysis products.

[0024] Figure 2 This is a schematic diagram of the structure of a water vapor separator in one implementation method.

[0025] Figure 3 This is a schematic diagram of the structure of a steam exhaust channel and a steam condenser in one embodiment.

[0026] Explanation of reference numerals in the attached figures

[0027] 1. Separator housing; 2. First distributor; 3. Second distributor

[0028] 4. Filter membrane; 5. Channel housing; 6. Water vapor condenser

[0029] 7 First humidity meter 8 First temperature gauge 9 First pressure gauge

[0030] 10 Second thermometer 11 Second pressure gauge 12 Second humidity meter

[0031] 13 Ammonia-air mixer 14 Vacuum pump Detailed Implementation

[0032] The following describes the specific embodiments of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0033] In this disclosure, unless otherwise stated, directional terms such as "top" and "bottom" are used in the context of the system's normal operating state.

[0034] like Figure 1 and2 As shown, the first aspect of this disclosure provides a water vapor separation system for urea hydrolysis product gas, the water vapor separation system including a product gas channel, a water vapor filtration unit, and a separation gas channel; the water vapor filtration unit includes a water vapor separator;

[0035] The water vapor separator includes a separator housing 1, on the outer surface of which a first heat insulation layer is provided; inside the separator housing 1, there is a first distributor 2 and a second distributor 3 arranged in a vertical direction, and a filter membrane 4 arranged in a horizontal direction; the inlet of the filter membrane 4 is connected to the product gas outlet of the first distributor 2, and the outlet of the filter membrane 4 is connected to the separation gas inlet of the second distributor 3.

[0036] The product gas inlet of the first distributor 2 of the water vapor separator is connected to the product gas outlet of the urea hydrolysis unit through a product gas channel; the outlet of the second distributor 3 of the water vapor separator is connected to the inlet of the ammonia air mixer 13 of the denitrification system through a separation gas channel.

[0037] This disclosed system utilizes the hydrophobic properties of a filter membrane, allowing water vapor to pass through and enter the permeate side, while ammonia and carbon dioxide in the product gas are retained on the stagnation side, thus separating the water vapor from ammonia and carbon dioxide in the product gas. This disclosure incorporates a first insulation layer on the outer surface of the separator shell, creating a temperature and pressure difference between the permeate and stagnation sides of the filter membrane. Simultaneously, it minimizes the temperature drop of the product gas within the separator (referring to the temperature drop of the product gas entering the water vapor separator from the urea hydrolysis unit), preventing water vapor condensation within the separator. This allows the water vapor in the product gas to continuously move towards the permeate side, achieving continuous and stable separation of water vapor in the product gas. The separation effect is stable, with high separation efficiency and high purity, which is beneficial for improving ammonia utilization efficiency. Furthermore, this disclosed system has a simple structure, is easy to operate, and has low separation energy consumption, saving energy and costs. Using the ammonia gas separated by the system disclosed herein for flue gas denitrification effectively avoids the corrosion of pipes by water vapor, avoids the impact of the aminomethylamine produced by the reverse reaction on pipelines, valves, instruments, etc., reduces resource waste and improves energy utilization.

[0038] In this disclosure, the first insulation layer can be of the type commonly used by those skilled in the art, such as an electric heat tracing insulation layer or a steam heat tracing insulation layer, and the temperature of the insulation layer can be adjusted.

[0039] In one embodiment, multiple filter membranes 4 are independently provided, and each filter membrane 4 has a processing capacity of 10-20 Nm³. 3 / h, preferably 10Nm 3 / h.

[0040] According to this disclosure, the system does not specifically limit the arrangement of the filter membranes. For example, multiple filter membranes can be arranged in parallel or in a circular arrangement, as long as there is space between the membranes for water vapor retention. Each filter membrane has only one inlet and one outlet. The number of product gas outlets in the first distributor and the number of separation gas inlets in the second distributor are determined by the number of filter membranes, with each filter membrane corresponding to one product gas outlet and one separation gas inlet. The water vapor separator of this disclosure uses multiple filter membranes, which increases the flow rate of product gas, reduces pressure loss, and improves the separation efficiency of product gas.

[0041] In the above embodiments, the processing capacity refers to the flow rate of product gas that a filter membrane can process per hour. For example, when the flow rate of the product gas is 100-200 Nm³ / h. 3 When the flow rate is 100 Nm³ / h, the number of filter membranes 4 is 5-20; preferably, when the flow rate of the product gas is 100 Nm³ / h... 3 At a rate of / h, the number of filter membranes 4 is 10.

[0042] In one embodiment, each of the first distributors 2 is provided with a plurality of product gas outlets, preferably 5-20; each of the second distributors 3 is provided with a plurality of separation gas inlets, preferably 5-20.

[0043] In one embodiment, the filter membrane 4 is a hydrophobic microporous membrane; wherein, the hydrophobic microporous membrane can utilize the temperature difference and vapor pressure difference across the membrane to achieve selective permeability of water vapor, and the liquid water cannot pass through the membrane. The hydrophobic microporous membrane has the properties of water release, air permeability, and windproofing, allowing water vapor to pass through easily. Preferably, the filter membrane 4 is selected from spiral wound GORE-TEX membranes or superhydrophobic polyimide fiber membranes.

[0044] like Figure 3 As shown, in one embodiment, the water vapor filtration unit further includes a water vapor exhaust channel and a water vapor condenser 6.

[0045] The water vapor exhaust channel includes a channel housing 5, the top of which is connected to the bottom of the separator housing 1. The water vapor outlet at the bottom of the separator housing 1 communicates with the water vapor inlet at the top of the channel housing 5. In this disclosure, the bottom of the separator housing and the top of the channel housing each have multiple through holes independently provided, and the through holes at the bottom of the separator housing and the through holes at the top of the channel housing are interconnected, allowing the water vapor separated in the water vapor separator to enter the water vapor exhaust channel. This disclosure does not specifically limit the size or number of through holes, as long as water vapor can enter the water vapor exhaust channel.

[0046] In a preferred embodiment, the top and side walls of the channel housing 5 are each independently provided with a second insulation layer. In this disclosure, the second insulation layer ensures that the water vapor in the connection area between the bottom of the separator housing and the top of the channel housing remains within a similar temperature range, preventing water vapor from condensing into water in the separator due to cooling. This facilitates the continuous and stable operation of the separation system. The second insulation layer can be of a type commonly used by those skilled in the art, such as an electric heating insulation layer or a steam heating insulation layer, and the temperature of the insulation layer can be adjusted.

[0047] In one embodiment, the bottom of the channel housing 5 is connected to the top of the water vapor condenser 6, and the water vapor outlet at the bottom of the channel housing 5 is connected to the water vapor inlet at the top of the water vapor condenser 6, so that the water vapor in the water vapor exhaust passage enters the water vapor condenser 6; the condenser is provided with a cooling medium pipeline to condense the water vapor into water.

[0048] This disclosure allows water vapor to condense into water through counter-current heat exchange via cooling medium pipelines. The condenser can be any commonly used device by those skilled in the art; for example, it can have multiple cooling medium pipelines, and the cooling medium can be water. The condensed water can be discharged through a condensate outlet located at the bottom of the channel housing 5. The flow rate of the cooling medium can be adjusted according to the flow rate of the product gas and the flow rate of water vapor entering the condenser.

[0049] In one embodiment, a product gas insulation layer is provided on the outer wall of the product gas channel. A first hygrometer 7, a first thermometer 8, and a first pressure gauge 9 are sequentially arranged on the product gas channel along the direction of product gas flow. The first hygrometer 7, the first thermometer 8, and the first pressure gauge 9 are used to measure the humidity, temperature, and pressure of the gas in the product gas channel, respectively. The product gas insulation layer is connected to the first thermometer 8 and its temperature is adjusted according to the temperature signal measured by the first thermometer 8. This ensures the temperature of the product gas entering the filter membrane retention side of the water vapor separator, creating a pressure difference with the permeation side. The outer wall of the separation gas channel is provided with a separation gas insulation layer. A second thermometer 10, a second pressure gauge 11, and a second humidity meter 12 are sequentially arranged in the separation gas channel along the direction of gas flow. The second thermometer 10, the second pressure gauge 11, and the second humidity meter 12 are used to measure the temperature, pressure, and humidity of the mixed gas in the separation gas channel, respectively. The separation gas insulation layer is connected to the second thermometer 10 and its temperature is adjusted according to the temperature signal measured by the second thermometer 10 to ensure the temperature of ammonia in the separation gas and prevent ammonia from entering the SCR denitrification ammonia injection system, which would lower the temperature of the flue gas and affect the denitrification reaction.

[0050] In the above embodiments, the product gas insulation layer and the separation gas insulation layer can be those conventionally used by those skilled in the art, such as electric heat tracing insulation layers or steam heat tracing insulation layers, and the temperature of the insulation layers can be adjusted. The first hygrometer, first thermometer, first pressure gauge, second thermometer, second pressure gauge, and second hygrometer of this disclosure can realize real-time detection of pressure, temperature, and humidity without causing environmental pollution.

[0051] In this disclosure, a first pressure gauge is used to measure the product gas pressure inside the product gas channel, and a second pressure gauge is used to measure the separation gas pressure inside the separation gas channel. The pressure difference is calculated by combining the data from the first and second pressure gauges. This pressure difference can be used to monitor whether the filter membrane is clogged. For example, clogging of the permeate membrane may cause a decrease in permeability, and the pressure difference may change. By analyzing the changes in the pressure difference, the effectiveness of the water vapor separator in removing water vapor can be determined. If the water removal effect deteriorates, it indicates that the filter membrane has failed and needs to be replaced. Humidity and pressure monitoring serve the same function as pressure monitoring. A first humidity meter is used to measure the water vapor content in the product gas inside the product gas channel, and a second humidity meter is used to measure the water vapor content in the separation gas inside the separation gas channel. Based on the data from the first and second humidity meters, the separation effect of the water vapor separator on water vapor is determined, allowing for the replacement of the filter membrane and ensuring the purity of ammonia and carbon dioxide in the separated gas.

[0052] In this disclosure, the exhaust gas after sampling and measurement by the first humidity meter is discharged downstream of the second humidity meter, and the exhaust gas after sampling and measurement by the second humidity meter is discharged downstream of the ammonia-air mixer. This allows the product gas to flow from the product gas channel to the separation gas channel under the pressure difference, and also avoids the exhaust gas after sampling by the humidity meter being discharged into the atmosphere, thus preventing environmental pollution.

[0053] The system disclosed herein can have a vacuum pump 14 installed at the bottom of the channel housing 5. This allows a vacuum system to be established before system operation. When the condensation process is running continuously and the system can achieve efficient condensation through its own self-established vacuum, the vacuum pump can be shut down. Preferably, the vacuum pump can be configured with one operating and one standby pump for easy maintenance. If there is a sudden increase in non-condensable gas, it can be restarted to maintain a good condensation recovery process. This vacuum pump can also be used to extract uncondensed gas from the water vapor condenser 6 to maintain the condensation effect.

[0054] The second aspect of this disclosure provides a method for separating water vapor from urea hydrolysis product gas using the system described in the first aspect. The method includes the following steps: allowing the product gas after urea hydrolysis to enter a water vapor separator through a product gas channel for separation treatment to obtain water vapor and separated gas.

[0055] In this disclosure, the product gas can be separated from water vapor, ammonia, and carbon dioxide by passing through a filter membrane in a water vapor separator, avoiding the addition of chemical reagents, achieving pollution-free emissions and recycling of high-purity ammonia.

[0056] In one embodiment, the separation process temperature is 130-160°C. In the above embodiment, "separation process temperature" refers to the temperature on the permeate side of the filter membrane.

[0057] In one embodiment, the method further includes: allowing the separated gas to enter the ammonia-air mixer 13 of the denitrification system through the separated gas channel for flue gas denitrification; and allowing water vapor to enter the water vapor condenser 6 through the water vapor exhaust channel to condense the water vapor into water.

[0058] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0059] Example 1

[0060] like Figure 1-3 As shown, this embodiment is used for a water vapor separation system in urea hydrolysis product gas, including a product gas channel, a water vapor filtration unit, and a separation gas channel; the water vapor filtration unit includes a water vapor separator;

[0061] The water vapor separator includes a separator shell 1, and a first heat insulation layer is provided on the outer surface of the separator shell 1; inside the separator shell 1, there is a first distributor 2 and a second distributor 3 arranged in a vertical direction, and a filter membrane 4 arranged in a horizontal direction; the inlet of the filter membrane 4 is connected to the product gas outlet of the first distributor 2, and the outlet of the filter membrane 4 is connected to the separation gas inlet of the second distributor 3.

[0062] The product gas inlet of the first distributor 2 of the water vapor separator is connected to the product gas outlet of the urea hydrolysis unit through the product gas channel; the outlet of the second distributor 3 of the water vapor separator is connected to the inlet of the ammonia air mixer 13 of the denitrification system through the separation gas channel.

[0063] There are 10 filter membranes 4. Each first distributor 2 has 10 product gas outlets; each second distributor 3 has 10 separation gas inlets.

[0064] Filter membrane 4 is a spiral wound GORE-TEX membrane.

[0065] The steam filtration unit also includes a steam exhaust channel and a steam condenser 6. The steam exhaust channel includes a channel housing 5, the top of which is connected to the bottom of a separator housing 1, and the steam outlet at the bottom of the separator housing 1 is connected to the steam inlet at the top of the channel housing 5. The bottom of the channel housing 5 is connected to the top of the steam condenser 6, and the steam outlet at the bottom of the channel housing 5 is connected to the steam inlet at the top of the steam condenser 6. A set of cooling water pipes is installed inside the condenser; the top and side walls of the channel housing 5 are each independently provided with a second insulation layer.

[0066] A vacuum pump 14 is installed on the channel housing.

[0067] The outer wall of the product gas channel is provided with a product gas insulation layer. A first humidity meter 7, a first temperature meter 8 and a first pressure gauge 9 are sequentially arranged on the product gas channel along the direction of product gas flow. The product gas insulation layer is connected to the first temperature meter 8 and adjusts the temperature of the product gas insulation layer according to the temperature signal fed back by the first temperature meter 8.

[0068] The outer wall of the gas separation channel is provided with a gas separation insulation layer. A second temperature gauge 10, a second pressure gauge 11, and a second humidity meter 12 are sequentially arranged in the gas separation channel along the direction of gas flow. The gas separation insulation layer is connected to the second temperature gauge 10 and the temperature of the gas separation insulation layer is adjusted according to the temperature signal fed back by the second temperature gauge 10.

[0069] The product gas from urea hydrolysis is fed into a water vapor separator through a product gas channel for separation, yielding water vapor and separated gas. The separated gas then passes through a separated gas channel into an ammonia air distributor 13, yielding ammonia and carbon dioxide. The water vapor is then fed into a water vapor condenser 6 through a water vapor exhaust channel, where it condenses to form water.

[0070] The separation process is carried out at a temperature of 130℃-160℃.

[0071] In summary, the system disclosed herein for separating water vapor from product gas not only boasts high separation efficiency but also yields ammonia and carbon dioxide with high purity. The urea hydrolysis reaction to produce ammonia is a reversible reaction. This disclosure, by separating water vapor from the product gas, disrupts the conditions for the reversible reaction, reduces the amount of water vapor, decreases the formation of intermediate products, avoids corrosion of valves and pipelines, prevents jamming and other problems, and significantly reduces its impact on the system. The water vapor separation system of this disclosure significantly reduces the hazards posed by product gas during transmission, improving the reliability and safety of system operation.

[0072] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0073] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0074] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A system for separating water vapor from urea hydrolysis product gas, characterized in that, The water vapor separation system includes a product gas channel, a water vapor filtration unit, and a separated gas channel; the water vapor filtration unit includes a water vapor separator. The water vapor separator includes a separator shell (1), on the outer surface of which a first heat insulation layer is provided; inside the separator shell (1) are a first distributor (2) and a second distributor (3) arranged in a vertical direction, and a filter membrane (4) arranged in a horizontal direction; the inlet of the filter membrane (4) is connected to the product gas outlet of the first distributor (2), and the outlet of the filter membrane (4) is connected to the separation gas inlet of the second distributor (3); The product gas inlet of the first distributor (2) of the water vapor separator is connected to the product gas outlet of the urea hydrolysis unit through the product gas channel; the outlet of the second distributor (3) of the water vapor separator is connected to the inlet of the ammonia air mixer (13) of the denitrification system through the separation gas channel. The outer wall of the product gas channel is provided with a product gas insulation layer. A first humidity meter (7), a first temperature meter (8) and a first pressure meter (9) are arranged sequentially on the product gas channel along the direction of product gas flow. The first humidity meter (7), the first temperature meter (8) and the first pressure meter (9) are used to measure the humidity, temperature and pressure of the gas in the product gas channel, respectively, and adjust the temperature of the product gas insulation layer according to the temperature signal measured by the first temperature meter (8). The outer wall of the gas separation channel is provided with a gas separation insulation layer. A second thermometer (10), a second pressure gauge (11), and a second humidity meter (12) are sequentially arranged on the gas separation channel along the direction of gas separation flow. The second thermometer (10), the second pressure gauge (11), and the second humidity meter (12) are used to measure the temperature, pressure, and humidity of the mixed gas in the gas separation channel, respectively, and the temperature of the gas separation insulation layer is adjusted according to the temperature signal measured by the second thermometer (10).

2. The water vapor separation system according to claim 1, characterized in that, Multiple filter membranes (4) are provided, and each filter membrane (4) has a processing capacity of 10-20 Nm. 3 / h.

3. The water vapor separation system according to claim 2, characterized in that, When the product gas flow rate is 100-200 Nm 3 When the number of filter membranes (4) is 5-20 per hour, the number of filter membranes (4) is 5-20 per hour.

4. The water vapor separation system according to claim 2, characterized in that, Each of the first distributors (2) is provided with multiple product gas outlets; Each of the second distributors (3) is provided with a plurality of the separated gas inlets.

5. The water vapor separation system according to claim 4, characterized in that, Each of the first distributors (2) is provided with product gas outlets 5-20; Each of the second distributors (3) is provided with the separation gas inlets described in 5-20.

6. The water vapor separation system according to claim 5, characterized in that, The filter membrane (4) is a hydrophobic microporous membrane; The filter membrane (4) is selected from spiral wound GORE-TEX membrane or superhydrophobic polyimide fiber membrane.

7. The water vapor separation system according to claim 1, characterized in that, The steam filtration unit also includes a steam exhaust channel and a steam condenser (6); The water vapor exhaust channel includes a channel housing (5), the top of which is connected to the bottom of the separator housing (1), and the water vapor outlet at the bottom of the separator housing (1) is connected to the water vapor inlet at the top of the channel housing (5), so that the water vapor separated in the water vapor separator enters the water vapor exhaust channel. The bottom of the channel housing (5) is connected to the top of the water vapor condenser (6), and the water vapor outlet at the bottom of the channel housing (5) is connected to the water vapor inlet at the top of the water vapor condenser (6), so that the water vapor in the water vapor exhaust passage enters the water vapor condenser (6); the condenser is provided with a cooling medium pipeline to condense the water vapor into water. The top and side walls of the channel housing (5) are each independently provided with a second insulation layer.

8. The water vapor separation system according to claim 7, characterized in that, A vacuum pump (14) is provided at the bottom of the channel housing (5).

9. A method for separating water vapor from urea hydrolysis product gas using the water vapor separation system according to any one of claims 1-8, characterized in that, The method includes the following steps: the product gas after urea hydrolysis is fed into a water vapor separator through a product gas channel for separation treatment to obtain water vapor and separated gas.

10. The method according to claim 9, characterized in that, The separation process is carried out at a temperature of 130-160℃.

11. The method according to claim 9, characterized in that, The method further includes: allowing the separated gas to enter the ammonia-air mixer (13) of the denitrification system through the separated gas channel for flue gas denitrification; and allowing water vapor to enter the water vapor condenser (6) through the water vapor exhaust channel to condense the water vapor into water.

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