A combined regeneration method for a high-temperature gas-cooled reactor molecular sieve bed and a low-temperature activated carbon bed

Abstract

The present invention discloses a combined regeneration method for a molecular sieve bed and a low-temperature activated carbon bed in a high-temperature gas-cooled reactor. The present invention combines the characteristics of the molecular sieve bed regeneration process and the low-temperature activated carbon bed regeneration process, combining the two regeneration processes. During the cooling process of the molecular sieve bed, the two regeneration processes intersect. Low-temperature gas generated during the natural heating process of the low-temperature activated carbon bed is used to cool the molecular sieve bed. Simultaneously, the heated low-temperature gas enters the low-temperature activated carbon bed, causing the low-temperature activated carbon bed to rapidly heat up. By combining the cooling process of the molecular sieve bed with the heating process of the low-temperature activated carbon bed, the present invention improves the regeneration effect while also increasing regeneration efficiency, thus having strong and wide applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of reactor helium purification, and in particular to a combined regeneration method of a molecular sieve bed and a low-temperature activated carbon bed of a high-temperature gas-cooled reactor. Background Art

[0002] The helium purification system for a high-temperature gas-cooled reactor (HTGR) consists of two key purification units: a molecular sieve bed and a low-temperature activated carbon bed. After a period of operation, these beds reach saturation and require regeneration to restore their purification function. The molecular sieve bed is regenerated by supplying high-temperature helium gas through the regeneration system, which flows through and heats the molecular sieve adsorbent in the bed, desorbing and releasing water adsorbed by the molecular sieve. The water is then cooled and condensed in a regeneration water / helium cooler before being separated and discharged from a gas / water separator. CO2 adsorbed by the molecular sieve is also desorbed, with some of it transferred to an auxiliary molecular sieve for adsorption. This is then regenerated by vacuum desorption. The activated carbon bed in the low-temperature activated carbon bed is regenerated by supplying high-temperature helium gas to heat the activated carbon in the bed, releasing gaseous impurities adsorbed by the carbon. These impurities are then discharged along with the regeneration helium gas. The bed is then regenerated by vacuum desorption, achieving combined regeneration.

[0003] Currently, during the regeneration process of the purification system, the heat capacity is relatively large due to the large amount of molecular sieve adsorbent and activated carbon in the molecular sieve bed and the low-temperature activated carbon bed. Therefore, the temperature drops very slowly during the regeneration process. Due to the thermal insulation effect of the low-temperature activated carbon bed, the natural heating and desorption process before regeneration also lasts for a long time. These problems lead to the low regeneration efficiency of the high-temperature gas-cooled reactor helium purification system. Therefore, it is necessary to optimize the existing regeneration method to make the regeneration process more reasonable and improve the regeneration effect and efficiency. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, an embodiment of the present invention provides a combined regeneration method for a high-temperature gas-cooled reactor molecular sieve bed and a low-temperature activated carbon bed.

[0006] The present invention proposes a combined regeneration method for a high-temperature gas-cooled reactor molecular sieve bed and a low-temperature activated carbon bed, comprising the following steps:

[0007] (1) Connect the molecular sieve bed to the regeneration circuit and heat it until the water content of the gas at the outlet of the molecular sieve bed is ≤3000ppm and the liquid level of the gas-water separator does not rise significantly;

[0008] (2) exhausting the molecular sieve bed to atmospheric pressure and then connecting it to an auxiliary molecular sieve bed circuit for heating and regeneration until the water content of the gas at the outlet of the molecular sieve bed does not decrease significantly;

[0009] (3) After the molecular sieve bed is exhausted to normal pressure again, the molecular sieve bed, the low-temperature activated carbon bed and the regeneration circuit are connected, and the low-temperature gas in the low-temperature activated carbon bed flows through the molecular sieve bed to cool it. The heated low-temperature gas returns to the low-temperature activated carbon bed through the cooling of the regeneration circuit to heat it until the molecular sieve outlet gas temperature is ≤60°C, and then the molecular sieve bed is isolated from the low-temperature activated carbon bed and the regeneration circuit;

[0010] (4) The molecular sieve bed is evacuated and the low-temperature activated carbon bed is heated and regenerated.

[0011] In some embodiments, before step (1), the molecular sieve bed and the low-temperature activated carbon bed are further depressurized.

[0012] In some embodiments, the molecular sieve bed is exhausted to 0.5±0.1 MPa, and the low-temperature activated carbon bed is exhausted to atmospheric pressure.

[0013] In some embodiments, the molecular sieve bed is evacuated to a vacuum degree of ≤100 MPa in step (4), and the regeneration process of the molecular sieve bed is completed.

[0014] In some embodiments, the heating regeneration of the low-temperature activated carbon bed in step (4) is to connect the low-temperature activated carbon bed to the regeneration loop and heat it for 16-20 hours.

[0015] In some embodiments, after step (4), the low-temperature activated carbon bed and the regeneration circuit are jointly vacuumed. When the vacuum is evacuated to a vacuum degree of ≤100 MPa, the regeneration process of the low-temperature activated carbon bed is completed.

[0016] In some embodiments, after the regeneration process of the low-temperature activated carbon bed is completed, pure helium is filled into the low-temperature activated carbon bed and the regeneration loop, and the low-temperature activated carbon bed is cyclically cooled to an outlet gas temperature of ≤60°C.

[0017] In some embodiments, a cooler, the gas-water separator, a gas compressor and an electric heater are sequentially arranged on the regeneration loop along the gas flow direction, and the molecular sieve bed and the low-temperature activated carbon bed are connected to the pipeline between the cooler and the electric heater.

[0018] In some embodiments, the auxiliary molecular sieve bed is provided on a bypass between the gas-water separator and the gas compressor.

[0019] In some embodiments, the auxiliary molecular sieve bed is used to adsorb water vapor and carbon dioxide so that the molecular sieve bed achieves deep desorption.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention combines the process characteristics of molecular sieve bed regeneration and low-temperature activated carbon bed regeneration, and combines the two regeneration processes. During the cooling process of the molecular sieve bed, the two regeneration processes will cross each other. The low-temperature gas generated by the natural heating process of the low-temperature activated carbon bed is used to cool the molecular sieve bed. At the same time, the heated low-temperature gas enters the low-temperature activated carbon bed to quickly heat up the low-temperature activated carbon bed. The present invention combines the cooling process of the molecular sieve bed with the heating process of the low-temperature activated carbon bed, which improves the regeneration effect while improving the regeneration efficiency, and has strong and wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0023] Figure 1 This is a schematic diagram of the purification and regeneration system of the high-temperature gas-cooled reactor;

[0024] Figure 2 Schematic diagram of the combined regeneration process of the high-temperature gas-cooled reactor molecular sieve bed and the low-temperature activated carbon bed.

[0025] Description of reference numerals:

[0026] Molecular sieve bed 1, low-temperature helium heat exchanger 2, low-temperature activated carbon bed 3, electric heater 4, gas compressor 5, auxiliary molecular sieve bed 6, cooler 7, gas-water separator 8, first valve 9, second valve 10, third valve 11, fourth valve 12, fifth valve 13, sixth valve 14, seventh valve 15, eighth valve 16, ninth valve 17, tenth valve 18, eleventh valve 19, twelfth valve 20. DETAILED DESCRIPTION

[0027] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0028] The following describes a combined regeneration method for a high-temperature gas-cooled reactor molecular sieve bed and a low-temperature activated carbon bed according to an embodiment of the present invention with reference to the accompanying drawings.

[0029] The combined regeneration method of a high-temperature gas-cooled reactor molecular sieve bed and a low-temperature activated carbon bed of the present invention comprises the following steps:

[0030] (a) Exhaust and pressure reduction of molecular sieve bed and low-temperature activated carbon bed;

[0031] (b) molecular sieve bed heating regeneration;

[0032] (c) After the molecular sieve bed is exhausted, it is connected to the auxiliary molecular sieve bed for operation;

[0033] (d) Molecular sieve bed cooling;

[0034] (e) The molecular sieve bed is evacuated while the low-temperature activated carbon bed is heated and regenerated;

[0035] (f) vacuuming the low-temperature activated carbon bed;

[0036] (g) Low temperature activated carbon bed cooling.

[0037] Reference Figure 2 After the combined regeneration process of the molecular sieve bed 1 and the low-temperature activated carbon bed 3 begins, step (a) is first performed to vent and reduce the pressure of the molecular sieve bed 1 and the low-temperature activated carbon bed 3. Specifically, the molecular sieve bed 1 is vented to 0.5±0.1 MPa and then isolated from the helium purification system; the low-temperature activated carbon bed 3 is vented to atmospheric pressure to effectively reduce the amount of radioactive waste gas emitted during the regeneration of the low-temperature activated carbon bed 3, and then isolated from the helium purification system.

[0038] In step (b), the molecular sieve bed 1 is heated and regenerated by connecting the molecular sieve bed 1 to a regeneration circuit for heating and circulating until the water content of the gas at the outlet of the molecular sieve bed 1 is ≤3000 ppm and the liquid level of the gas-water separator 8 does not rise significantly.

[0039] Specifically, refer to Figure 1 The regeneration circuit is sequentially arranged along the gas flow direction, including a cooler 7, a gas-water separator 8, a gas compressor 5, and an electric heater 4. An auxiliary molecular sieve bed 6 is provided in the bypass between the gas-water separator 8 and the gas compressor 5. The molecular sieve bed 1 is connected to the regeneration circuit to form a closed loop. At this point, the tenth valve 18, the first valve 9, the twelfth valve 20, the sixth valve 14, the seventh valve 15, the eighth valve 16, and the ninth valve 17 are open, while the second valve 10, the third valve 11, the eleventh valve 19, the fourth valve 12, and the fifth valve 13 are closed. The gas compressor 5 compresses the helium in the circuit, and the helium, heated by the electric heater 4, circulates through the molecular sieve bed 1, heating it. During the heating process, water and carbon dioxide adsorbed by the molecular sieve are continuously desorbed. The desorbed water vapor is cooled in the regeneration circuit's cooler 7 and condensed and separated in the gas-water separator 8, while the carbon dioxide circulates within the system. The cyclic heating process is terminated when the water content of the gas exiting the molecular sieve bed 1 is ≤3000 ppm and the liquid level in the gas-water separator 8 does not rise significantly. The amount of impurities adsorbed by the molecular sieve varies under different operating conditions, and a single time indicator cannot cover all regeneration conditions of the molecular sieve bed 1. Therefore, the heating regeneration process of the molecular sieve bed 1 of the present invention no longer limits the heating time, but instead provides acceptance criteria for the end of the heating process, which has wide adaptability.

[0040] After the molecular sieve bed 1 is heated and regenerated, step (c) is performed, that is, the molecular sieve bed 1 is evacuated and then the auxiliary molecular sieve bed 6 is connected for operation.

[0041] Specifically, after the molecular sieve bed 1 is heated and regenerated, all gases within the molecular sieve and regeneration circuit are discharged to atmospheric pressure. Because the gas within the regeneration circuit contains a large amount of water and carbon dioxide after the molecular sieve bed 1 is heated and regenerated, the high partial pressures of water and carbon dioxide are not conducive to the continued desorption of impurities in the molecular sieve. Therefore, discharging the gas can improve the regeneration effect of the molecular sieve while reducing the loss of helium and appropriately shorten the regeneration time of the molecular sieve.

[0042] After the molecular sieve bed 1 is heated and regenerated and exhausted to normal pressure, the auxiliary molecular sieve bed 6 is connected to the regeneration circuit. Figure 1 At this time, the tenth valve 18, the first valve 9, the twelfth valve 20, the sixth valve 14, the fourth valve 12, the fifth valve 13, the eighth valve 16, and the ninth valve 17 are opened, while the second valve 10, the third valve 11, the eleventh valve 19, and the seventh valve 15 are closed. Pure helium is then introduced into the molecular sieve bed 1 and the regeneration circuit. The auxiliary molecular sieve bed 6 is then placed into the regeneration circuit, and the helium in the circuit is continuously heated to begin regeneration. Since the system is filled with pure helium, the impurities adsorbed in the molecular sieve are desorbed more quickly. Simultaneously, due to the adsorption effect of the auxiliary molecular sieve, the molecular sieve can achieve deep desorption. When the water content of the gas at the outlet of the molecular sieve bed 1 does not decrease significantly, the process is terminated, and the gas in the molecular sieve bed 1 and the regeneration circuit is discharged to atmospheric pressure.

[0043] After the molecular sieve bed 1 after deep desorption is evacuated to atmospheric pressure, the molecular sieve bed 1 cooling process of step (d) is carried out. After the molecular sieve bed 1 is evacuated to atmospheric pressure again, the molecular sieve bed 1, the low-temperature activated carbon bed 3 and the regeneration circuit are connected. The low-temperature gas in the low-temperature activated carbon bed 3 flows through the molecular sieve bed 1 to cool it. The heated low-temperature gas returns to the low-temperature activated carbon bed 3 through the cooling of the regeneration circuit to heat it until the molecular sieve outlet gas temperature is ≤60°C, and then the molecular sieve bed 1 is isolated from the low-temperature activated carbon bed 3 and the regeneration circuit.

[0044] Specifically, because molecular sieve bed 1 is filled with a large amount of molecular sieve, it absorbs a large amount of heat during the heating process in steps (b) and (c). Since the molecular sieve bed 1 is covered with insulation material, the natural heat dissipation process is very slow. There are two reasons for the cooling of molecular sieve bed 1. One is that the molecular sieve bed 1 will be evacuated later, and the vacuum pump inlet cannot withstand high temperatures. The other is that after the molecular sieve bed 1 is regenerated, it is connected to the helium purification system. Normal operation is at room temperature, so the molecular sieve bed 1 must be cooled. The low-temperature activated carbon bed 3 has a natural heating process before regeneration, because the low-temperature activated carbon bed 3 is immersed in liquid nitrogen during normal purification operation, and the temperature is extremely low. The low-temperature activated carbon bed 3 has cold preservation measures. Although the liquid nitrogen is discharged, its natural heating process is very slow. Therefore, in this step, the cooling of the molecular sieve bed 1 is combined with the heating of the low-temperature activated carbon, that is, the low-temperature gas generated by the natural heating process of the low-temperature activated carbon bed 3 is used to cool the molecular sieve bed 1, and at the same time, the heated low-temperature gas enters the low-temperature activated carbon bed 3, so that the low-temperature activated carbon bed 3 heats up rapidly. The present invention combines the cooling process of the molecular sieve bed 1 with the heating process of the low-temperature activated carbon bed 3, which saves energy while shortening the regeneration time and improving the overall regeneration efficiency.

[0045] Before the process begins, some of the impurities that have been desorbed from the low-temperature activated carbon bed 3 by heating are discharged. Then, the molecular sieve bed 1, low-temperature activated carbon bed 3, and regeneration circuit are connected. At this point, the sixth valve 14, seventh valve 15, eighth valve 16, ninth valve 17, tenth valve 18, second valve 10, third valve 11, and twelfth valve 20 are open; the first valve 9, eleventh valve 19, fourth valve 12, and fifth valve 13 are closed. The low-temperature gas in the low-temperature activated carbon bed 3 flows through the molecular sieve bed 1 to cool it. The heated low-temperature gas then returns to the low-temperature activated carbon bed 3 through the cooling circuit to heat it. This cycle continues until the gas temperature at the outlet of the molecular sieve bed 1 is ≤60°C. At this point, the low-temperature activated carbon bed 3 can also be heated to room temperature. The molecular sieve bed 1 is then isolated from the low-temperature activated carbon bed 3 and the regeneration circuit. At this point, the molecular sieve bed 1 is not connected to the regeneration circuit, while the low-temperature activated carbon bed 3 is connected to the regeneration circuit.

[0046] After the molecular sieve bed 1 is cooled, step (e) is performed to evacuate the molecular sieve bed 1 while heating and regenerating the low-temperature activated carbon bed 3.

[0047] Specifically, the molecular sieve bed 1 is connected to the vacuum pumping equipment, and the molecular sieve bed 1 is vacuumed. When the vacuum degree of the molecular sieve bed 1 is ≤100MPa, the vacuuming is terminated, and the regeneration process of the molecular sieve bed 1 is completed. While the molecular sieve bed 1 is vacuumed, the low-temperature activated carbon bed 3 is heated and regenerated. At this time, the low-temperature activated carbon bed 3 is connected to the regeneration circuit, the sixth valve 14, the seventh valve 15, the eighth valve 16, the ninth valve 17, the tenth valve 18, the second valve 10, the third valve 11 and the eleventh valve 19 are opened, and the first valve 9, the twelfth valve 20, the fourth valve 12 and the fifth valve 13 are closed. The helium heated by the electric heater 4 circulates through the low-temperature activated carbon bed 3 and heats the activated carbon. During the heating process, the impurities adsorbed by the activated carbon are continuously desorbed. After the heating time lasts for 16-20 hours, the heating regeneration process of the low-temperature activated carbon bed 3 is completed.

[0048] After the heating and regeneration process of the low-temperature activated carbon bed 3 is completed, step (f) is performed to evacuate the low-temperature activated carbon bed 3. Specifically, after the heating and regeneration of the low-temperature activated carbon bed 3 is completed, the radioactive waste gas in the loop is discharged to the waste gas treatment system until it reaches atmospheric pressure. Then, the low-temperature activated carbon bed 3 and the regeneration loop are jointly evacuated until the vacuum value of the low-temperature activated carbon bed 3 reaches ≤100 MPa, indicating that the regeneration process of the low-temperature activated carbon bed 3 is complete.

[0049] After the regeneration process of the low-temperature activated carbon bed 3 is completed, step (g) is performed to cool the low-temperature activated carbon bed 3. Specifically, pure helium is filled into the low-temperature activated carbon bed 3 and the regeneration circuit. The low-temperature helium heat exchanger 2 is connected to the low-temperature activated carbon bed 3. After the helium cools the low-temperature helium heat exchanger 2, it circulates to cool the low-temperature activated carbon bed 3 until the outlet gas temperature of the low-temperature activated carbon bed 3 is ≤60°C. After the low-temperature activated carbon bed 3 is cooled, it can be put back into purification system operation.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms may be directed to different embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0052] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A combined regeneration method for a high-temperature gas-cooled reactor molecular sieve bed and a low-temperature activated carbon bed, characterized in that: The following steps are involved: (1) Connecting the molecular sieve bed to a regeneration circuit for heating circulation until the water content of the gas at the outlet of the molecular sieve bed is ≤3000 ppm and the liquid level of the gas-water separator does not rise significantly, and sequentially disposing a cooler, the gas-water separator, a gas compressor and an electric heater on the regeneration circuit along the gas flow direction, and connecting the molecular sieve bed and the low-temperature activated carbon bed to a pipeline between the cooler and the electric heater; (2) After the molecular sieve bed is evacuated to atmospheric pressure, it is connected to an auxiliary molecular sieve bed circuit for heating and regeneration until the water content of the gas at the outlet of the molecular sieve bed does not decrease significantly, and the auxiliary molecular sieve bed is installed in the bypass between the gas-water separator and the gas compressor; (3) After the molecular sieve bed is exhausted to normal pressure again, the molecular sieve bed, the low-temperature activated carbon bed and the regeneration circuit are connected, and the low-temperature gas in the low-temperature activated carbon bed flows through the molecular sieve bed to cool it. The heated low-temperature gas returns to the low-temperature activated carbon bed through the cooling of the regeneration circuit to heat it until the molecular sieve outlet gas temperature is ≤60°C, and then the molecular sieve bed is isolated from the low-temperature activated carbon bed and the regeneration circuit; (4) The molecular sieve bed is evacuated and the low-temperature activated carbon bed is heated and regenerated.

2. The method according to claim 1, wherein Before step (1), the molecular sieve bed and the low-temperature activated carbon bed are further degassing and depressurizing.

3. The method according to claim 2, wherein The molecular sieve bed is exhausted to 0.5±0.1 MPa, and the low-temperature activated carbon bed is exhausted to normal pressure.

4. The method according to claim 1, wherein In step (4), the molecular sieve bed is evacuated to a vacuum degree of ≤100 MPa, and the regeneration process of the molecular sieve bed is completed.

5. The method according to claim 1, wherein In step (4), the low-temperature activated carbon bed is heated and regenerated by connecting the low-temperature activated carbon bed to the regeneration circuit and heating the bed for 16-20 hours.

6. The method according to claim 1, wherein After step (4), the low-temperature activated carbon bed and the regeneration circuit are jointly vacuumed. When the vacuum is evacuated to a vacuum degree of ≤100 MPa, the regeneration process of the low-temperature activated carbon bed is completed.

7. The method according to claim 6, wherein After the regeneration process of the low-temperature activated carbon bed is completed, pure helium is filled into the low-temperature activated carbon bed and the regeneration loop, and the low-temperature activated carbon bed is circulated and cooled until the outlet gas temperature is ≤60°C.

8. The method according to claim 7, wherein The auxiliary molecular sieve bed is used to adsorb water vapor and carbon dioxide so that the molecular sieve bed can achieve deep desorption.

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