A sulfur blowing passivation method for a sulfur recovery unit

Abstract

The present invention discloses a sulfur blowing passivation method for a sulfur recovery unit, comprising the following steps: first, simultaneously introducing methane gas, air and low-pressure steam into the air inlet of a Claus furnace to perform sulfur blowing treatment on the sulfur recovery unit; wherein the temperature in the Claus furnace is maintained at 1100°C to 1200°C; the flow rate of the methane gas is 550 Nm 3 / h~700 Nm 3 / h; the flow rate of low-pressure steam is 4.5t / h to 7t / h; Step 2: Stop the low-pressure steam flow and continue to introduce methane gas and air into the Claus furnace inlet, maintaining the Claus furnace temperature at 1100°C to 1200°C. Simultaneously, the volume ratio K of methane gas to air per unit time is controlled, starting from K=10 and increasing by 0.3 to 1.2 every 0.5h to 1h until K=≥20 and the catalyst bed temperatures of the first and second catalytic converters do not change significantly, completing the passivation treatment. The entire process ensures thorough sulfur blowing, prevents temperature runaway during the passivation process, and offers strong controllability, making it easy to promote.

Description

Technical Field

[0001] The invention relates to the technical field of sulfur blowing passivation process, and in particular to a sulfur blowing passivation method of a sulfur recovery unit. Background Art

[0002] A conventional sulfur recovery unit primarily consists of a Claus furnace, a primary catalytic converter, a secondary catalytic converter, a condenser, and a liquid sulfur tank, all interconnected. After the sulfur recovery unit is shut down, residual gaseous sulfur within each component must be thoroughly purged, and the catalyst beds of the primary and secondary catalytic converters must be passivated. This sulfur blowing and passivation process is a crucial operation within the sulfur recovery unit.

[0003] However, during the sulfur blowing passivation process of the prior art sulfur recovery unit, the sulfur blowing is often incomplete and the passivation temperature rises, causing certain damage to the equipment. Summary of the Invention

[0004] The purpose of the present invention is to provide a sulfur blowing passivation method for a sulfur recovery unit in view of the problems of incomplete sulfur blowing and temperature runaway in the sulfur blowing passivation process of the prior art sulfur recovery unit. The sulfur blowing passivation method has high sulfur blowing thoroughness, no temperature runaway phenomenon occurs during the passivation process, strong controllability, and is easy to promote.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A sulfur blowing passivation method for a sulfur recovery unit, wherein the sulfur recovery unit comprises a Claus furnace, a first catalytic converter, a second catalytic converter, a condenser, and a liquid sulfur pool connected in sequence; the method comprises the following steps:

[0007] Step 1: First, methane gas, air and low-pressure steam are introduced into the air inlet of the Claus furnace at the same time, and the sulfur recovery unit is subjected to sulfur blowing treatment until there is no new liquid sulfur in the liquid sulfur pool; wherein, during the sulfur blowing treatment, the temperature in the Claus furnace is maintained at 1100° C. to 1200° C.; the volume ratio of the air to the methane gas per unit time is K=10; the flow rate of the methane gas is 550 Nm 3 / h~700Nm 3 / h; the flow rate of low-pressure steam is 4.5t / h~7t / h;

[0008] Step 2: Stop the introduction of low-pressure water vapor, continue to introduce methane gas and air into the air inlet of the Claus furnace, maintain the temperature of the Claus furnace at 1100° C. to 1200° C., and adjust the volume ratio K of the methane gas and air per unit time. The K value starts from 10 and increases by 0.3 to 1.2 every 0.5 h to 1 h until the K value is ≥ 20 and the catalyst bed temperature of the first catalytic converter and the catalyst bed temperature of the second catalytic converter do not change significantly, thereby completing the passivation treatment.

[0009] The sulfur blowing passivation method for the sulfur recovery unit disclosed in the present invention first adopts methane gas, air and low-pressure water vapor to be introduced into the Claus furnace simultaneously for sulfur blowing. On the one hand, the addition of low-pressure water vapor can effectively control the temperature of the fuel gas, facilitate the sulfur blowing effect by the heat of fuel gas combustion, and increase the controllability of the sulfur blowing process; on the other hand, the three gases enter the Claus furnace at the same time, and by controlling the flow rate of the three gases, it can prevent the problems of low pressure, gas phase flow shortcuts and poor gas phase flow in some areas, effectively ensuring the thoroughness of the sulfur blowing treatment and avoiding the occurrence of flashback temperature rise in the later passivation process. Secondly, after the sulfur blowing treatment is completed, the addition of low-pressure water vapor is stopped. By controlling the ratio of methane gas and air, quantifying the single increase ratio of combustion air, and controlling the time interval of increasing combustion air, the occurrence of temperature rise in the catalyst bed during the passivation process can be effectively avoided.

[0010] Furthermore, the pressure of the low-pressure steam is 0.35-0.4 MPa, and the temperature is 120-150° C. During the sulfur blowing process, if the temperature is not controlled by low-pressure steam, it is difficult to control the thoroughness of the sulfur blowing and the occurrence of the catalyst bed temperature runaway phenomenon.

[0011] Furthermore, in step 1, the flow rate of methane gas is 550 Nm 3 / h~650Nm 3 / h; the flow rate of low-pressure steam is 4.5t / h~5.5t / h. The flow rates of the three gases are key factors to ensure the thoroughness of sulfur blowing. Within the appropriate flow rate range, the total amount of low-pressure steam can be effectively reduced. Preferably, in step 1, the flow rate of methane gas is 600Nm 3 / h~650Nm 3 / h; the flow rate of low-pressure steam is 5.0t / h~5.5t / h. Within the appropriate gas flow range, it is not only possible to ensure the thoroughness of sulfur blowing, but also to effectively reduce the amount of low-pressure steam and the sulfur blowing time.

[0012] Furthermore, in the step 1, the wind speed on the catalyst bed in the first catalytic converter and the catalyst bed in the second catalytic converter is 0.2m / s to 0.25m / s. Through a large number of experimental explorations by the inventors, it was found that during the sulfur blowing process, the wind speed on the catalyst bed is an important influencing factor to ensure the thoroughness of sulfur blowing. If the wind speed is too large or too small, it will cause the incompleteness of sulfur blowing, resulting in the occurrence of passivation temperature rise phenomenon in the later stage. Preferably, the wind speed on the catalyst bed in the first catalytic converter and the catalyst bed in the second catalytic converter is 0.22m / s to 0.25m / s. Studies have found that within a suitable wind speed range, not only can the thoroughness of the sulfur blowing effect be guaranteed, but also the sulfur blowing time can be effectively reduced and the rapidity of sulfur blowing can be improved.

[0013] Furthermore, in step 2, the K value starts at 10 and increases by 0.3 to 0.9 every 0.5 to 10 hours until the K value is ≥ 20. The K value is gradually increased by controlling the appropriate single increase amount to effectively control the passivation effect of the catalyst bed and avoid the occurrence of temperature runaway.

[0014] Furthermore, in step 2, the K value starts at 10 and increases by 0.6 to 0.9 every 0.5 to 10 hours until the K value is ≥ 20 and the catalyst bed temperature of the first catalytic converter and the catalyst bed temperature of the second catalytic converter do not increase within 24 hours, thereby completing the passivation treatment.

[0015] Furthermore, in step 2, during the passivation process, the maximum temperature of the catalyst bed in the first catalytic converter and the catalyst bed of the first catalytic converter does not exceed 280° C. Due to incomplete sulfur blowing, FeS, sulfur, and carbon deposits may remain in the bed. During the passivation process, these residual materials will rapidly burn due to the large amount of excess oxygen, resulting in a significant temperature rise in the catalytic converter, a bed combustion runaway, and damage to the catalyst and equipment.

[0016] Furthermore, the method further includes step 3, simultaneously reducing the gas flow rates of air and methane gas to cool the catalyst.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] The sulfur blowing passivation method of the sulfur recovery unit disclosed in the present invention first adopts methane gas, air and low-pressure water vapor to be introduced into the Claus furnace at the same time for sulfur blowing. On the one hand, the addition of low-pressure water vapor can effectively control the temperature of the fuel gas, facilitate the sulfur blowing effect by the combustion heat of the fuel gas, and increase the controllability of the sulfur blowing process; on the other hand, the three gases enter the Claus furnace at the same time, and by controlling the flow rate of the three gases, it can prevent the problems of low pressure, gas phase flow taking shortcuts and poor gas phase flow in some areas, effectively ensuring the thoroughness of the sulfur blowing treatment and avoiding the occurrence of tempering and temperature rise phenomenon in the later passivation process. Secondly, after the sulfur blowing treatment is completed, the addition of low-pressure water vapor is stopped. By controlling the introduction ratio of methane gas and air, quantifying the single increase ratio of combustion air and controlling the time interval of increasing combustion air, the occurrence of temperature rise phenomenon in the catalyst bed during the passivation process can be effectively avoided. The method is simple, easy to control and highly safe. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] Example 1

[0021] A sulfur recovery unit includes a Claus furnace, a first catalytic converter, a second catalytic converter, a condenser and a liquid sulfur pool which are connected in sequence.

[0022] After stopping the natural gas feed gas supply, the sulfur recovery unit is subjected to sulfur blowing passivation treatment:

[0023] The following steps are involved:

[0024] Step 1: First, methane gas, air, and low-pressure steam are introduced into the air inlet of the Claus furnace simultaneously, and the sulfur recovery unit is subjected to sulfur blowing treatment until there is no new liquid sulfur in the liquid sulfur pool; wherein, during the sulfur blowing treatment, the temperature in the Claus furnace is maintained at 1150°C; the volume ratio of the air to the methane gas per unit time is K=10; the flow rate of the methane gas is 620Nm 3 / h; the flow rate of low-pressure steam is 5t / h; the pressure of the low-pressure steam is 0.35Mpa and the temperature is 120°C. The wind speed on the catalyst bed in the first catalytic converter and the catalyst bed in the second catalytic converter is 0.25m / s.

[0025] Step 2: Stop the introduction of low-pressure water vapor, and continue to introduce methane gas and air into the air inlet of the Claus furnace, maintain the temperature of the Claus furnace at 1200° C., and control the volume ratio K of methane gas to air per unit time, starting from K=10 and increasing by 0.3 every 0.5 hour until K value is ≥20 and the catalyst bed temperature of the first catalytic converter and the catalyst bed temperature of the second catalytic converter do not increase within 24 hours, thereby completing the passivation treatment.

[0026] Step 3: Reduce the air and methane gas flow rates simultaneously to cool the catalyst.

[0027] Example 2

[0028] Example 2 The same sulfur recovery unit as in Example 1 was subjected to sulfur blowing passivation treatment.

[0029] The following steps are involved:

[0030] Step 1: First, methane gas, air and low-pressure steam are introduced into the air inlet of the Claus furnace at the same time, and the sulfur recovery unit is subjected to sulfur blowing treatment until there is no new liquid sulfur in the liquid sulfur pool; wherein, during the sulfur blowing treatment, the temperature in the Claus furnace is maintained at 1100°C; the volume ratio of the air to the methane gas per unit time is K=10; the flow rate of the methane gas is 580Nm 3 / h; the flow rate of low-pressure steam is 5.5t / h; the pressure of the low-pressure steam is 0.4Mpa and the temperature is 150°C. The wind speed on the catalyst bed in the first catalytic converter and the catalyst bed in the second catalytic converter is 0.22m / s.

[0031] Step 2: Stop the introduction of low-pressure water vapor, and continue to introduce methane gas and air into the air inlet of the Claus furnace, maintain the temperature of the Claus furnace at 1100° C., and control the volume ratio K of methane gas to air per unit time, starting from K=10 and increasing by 0.6 every 0.75 h until K value is ≥20 and the catalyst bed temperature of the first catalytic converter and the catalyst bed temperature of the second catalytic converter do not increase within 24 h, thereby completing the passivation treatment.

[0032] Step 3: Reduce the air and methane gas flow rates simultaneously to cool the catalyst.

[0033] Example 3

[0034] Example 3 The same sulfur recovery unit as in Example 1 was subjected to sulfur blowing passivation treatment.

[0035] The following steps are involved:

[0036] Step 1: First, methane gas, air and low-pressure steam are introduced into the air inlet of the Claus furnace at the same time, and the sulfur recovery unit is subjected to sulfur blowing treatment until there is no new liquid sulfur in the liquid sulfur pool; wherein, during the sulfur blowing treatment, the temperature in the Claus furnace is maintained at 1200°C; the volume ratio of the air to the methane gas per unit time is K=10; the flow rate of the methane gas is 550Nm 3 / h; the flow rate of low-pressure steam is 7t / h; the pressure of the low-pressure steam is 0.384Mpa, and the temperature is 130°C. The wind speed on the catalyst bed in the first catalytic converter and the catalyst bed in the second catalytic converter is 0.2m / s.

[0037] Step 2: Stop the introduction of low-pressure water vapor, and continue to introduce methane gas and air into the air inlet of the Claus furnace, maintaining the temperature of the Claus furnace at 1200° C. At the same time, control the volume ratio K of methane gas to air per unit time, starting from K=10 and increasing by 0.9 every hour until K value is ≥20 and the catalyst bed temperature of the first catalytic converter and the catalyst bed temperature of the second catalytic converter do not increase within 24 hours, thereby completing the passivation treatment.

[0038] Step 3: Reduce the air and methane gas flow rates simultaneously to cool the catalyst.

[0039] Example 4

[0040] Example 4 The same sulfur recovery unit as in Example 1 was subjected to sulfur blowing passivation treatment.

[0041] The following steps are involved:

[0042] Step 1: First, methane gas, air, and low-pressure steam are introduced into the air inlet of the Claus furnace simultaneously, and the sulfur recovery unit is subjected to a sulfur blowing treatment until there is no new liquid sulfur in the liquid sulfur pool; wherein, during the sulfur blowing treatment, the temperature in the Claus furnace is maintained at 1180°C; the volume ratio of the air to the methane gas per unit time is K=10; and the flow rate of the methane gas is 700Nm 3 / h; the flow rate of low-pressure steam is 4.5t / h; the pressure of the low-pressure steam is 0.36Mpa and the temperature is 140°C. The wind speed on the catalyst bed in the first catalytic converter and the catalyst bed in the second catalytic converter is 0.2m / s.

[0043] Step 2: Stop the introduction of low-pressure water vapor, and continue to introduce methane gas and air into the air inlet of the Claus furnace, maintain the temperature of the Claus furnace at 1200° C., and control the volume ratio K of methane gas to air per unit time, starting from K=10 and increasing by 1.2 every 0.5 hour until K value is ≥20 and the catalyst bed temperature of the first catalytic converter and the catalyst bed temperature of the second catalytic converter do not increase within 24 hours, thereby completing the passivation treatment.

[0044] Step 3: Reduce the air and methane gas flow rates simultaneously to cool the catalyst.

[0045] Comparative Example 1

[0046] Comparative Example 1: The same method as in Example 1 was used to perform sulfur blowing passivation treatment on the same sulfur recovery unit as in Example 1. Compared with Example 1, Comparative Example 1 changed the fuel gas flow rate, steam flow rate and wind speed during the sulfur blowing process. The other process parameters and processes of the sulfur blowing process and the steps and parameters of the passivation process were the same as those in Example 1.

[0047] Comparative Example 2

[0048] In Comparative Example 2, the same method as in Example 1 was used to perform sulfur blowing passivation treatment on the same sulfur recovery unit as in Example 1. Compared with Example 1, Comparative Example 2 changed the fuel gas flow rate, steam flow rate and wind speed during the sulfur blowing process. The other process parameters and processes of the sulfur blowing process and the steps and parameters of the passivation process were the same as those in Example 1.

[0049] Comparative Example 3

[0050] Comparative Example 3 uses the same method as Example 1 to perform sulfur blowing passivation treatment on the same sulfur recovery unit as Example 1. The sulfur blowing process and process parameters of Comparative Example 3 are the same as those of Example 1, except that the single increase amount of the K value in Example 1 is changed in Comparative Example 3. Other passivation processes and parameters are the same as those of Example 1.

[0051] As shown in Table 1, the process parameters, sulfur blowing effects and time conditions in Examples 1-4 and Comparative Examples 1-3 are recorded.

[0052] As shown in Table 2, the process parameters and passivation effects in Examples 1-4 and Comparative Examples 1-3 are recorded.

[0053] Table 1

[0054]

[0055] Table 2

[0056]

[0057] As can be seen from Tables 1 and 2, the sulfur blowing passivation method for the sulfur recovery unit disclosed in this application first employs methane gas, air, and low-pressure steam to be simultaneously introduced into the Claus furnace for sulfur blowing. On the one hand, the addition of low-pressure steam can effectively control the temperature of the fuel gas, facilitate the sulfur blowing effect by utilizing the heat of the fuel gas combustion, and increase the controllability of the sulfur blowing process. On the other hand, the simultaneous entry of the three gases into the Claus furnace, by controlling the flow rates of the three gases, can prevent problems such as low pressure, gas phase flow shortcuts, and poor gas phase flow in some areas, effectively ensuring the thoroughness of the sulfur blowing treatment and avoiding the occurrence of flashback temperature spikes during the later passivation process. Secondly, the addition of low-pressure steam is stopped after the sulfur blowing treatment is completed. By controlling the ratio of methane gas to air, quantifying the single increase in the ratio of combustion air, and controlling the time interval between combustion air additions, the occurrence of temperature spikes in the catalyst bed during the passivation process can be effectively avoided. The method is simple, easy to control, and highly safe.

[0058] Studies have found that burning excessive fuel gas will reduce furnace temperature but increase carbon deposits in the catalyst bed. When the fuel gas and air mixture burns at the chemical equivalence point (no excess oxygen), the flame temperature reaches its highest point, requiring steam injection to control the temperature. If there is excessive air during combustion, the sulfur deposits on the catalyst bed will begin to burn rapidly, generating high temperatures that damage the catalyst and equipment. If the sulfur blowing air volume is controlled too low, it is easy to cause sulfur to be biased and the sulfur blowing time to be long. If the sulfur blowing air volume is too large, more fuel gas will be consumed and carbon deposits will be formed on the catalyst bed, resulting in a temperature runaway phenomenon.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A sulfur blowing passivation method for a sulfur recovery unit, characterized in that: The sulfur recovery unit includes a Claus furnace, a first catalytic converter, a second catalytic converter, a condenser and a liquid sulfur pool connected in sequence; and includes the following steps: Step 1: First, methane gas, air, and low-pressure steam are introduced into the air inlet of the Claus furnace simultaneously, and the sulfur recovery unit is subjected to a sulfur blowing treatment until there is no new liquid sulfur in the liquid sulfur pool; wherein, during the sulfur blowing treatment, the temperature in the Claus furnace is maintained at 1100°C to 1200°C; the volume ratio of the air to the methane gas per unit time is K=10; the flow rate of the methane gas is 550 Nm 3 / h~700 Nm 3 / h; the flow rate of low-pressure steam is 4.5t / h to 7t / h; the wind speed on the catalyst bed in the first catalytic converter and the catalyst bed in the second catalytic converter is 0.2m / s to 0.25m / s; Step 2: Stop the introduction of low-pressure water vapor, continue to introduce methane gas and air into the air inlet of the Claus furnace, maintain the temperature of the Claus furnace at 1100° C. to 1200° C., and adjust the volume ratio K of methane gas and air per unit time. Starting from a K value of 10, increase the ratio by 0.3 to 1.2 every 0.5 h to 1 h until the K value is ≥ 20 and the catalyst bed temperature of the first catalytic converter and the catalyst bed temperature of the second catalytic converter do not change significantly, thereby completing the passivation treatment.

2. The sulfur blowing passivation method of the sulfur recovery unit according to claim 1, characterized in that: The pressure of the low-pressure water vapor is 0.35-0.4 MPa.

3. The sulfur blowing passivation method of the sulfur recovery unit according to claim 2, characterized in that: The temperature of the low-pressure steam is 120°C to 150°C.

4. The sulfur blowing passivation method of the sulfur recovery unit according to claim 1, characterized in that: In step 1, the flow rate of methane gas is 550 Nm 3 / h~650 Nm 3 / h; the flow rate of low-pressure water vapor is 4.5t / h~5.5t / h.

5. The sulfur blowing passivation method of the sulfur recovery unit according to claim 4, characterized in that: In step 1, the flow rate of methane gas is 600 Nm 3 / h~650 Nm 3 / h; the flow rate of low-pressure water vapor is 5.0t / h~5.5t / h.

6. The sulfur blowing passivation method of the sulfur recovery unit according to claim 1, characterized in that: In step 1, the wind speed on the catalyst bed in the first catalytic converter and the catalyst bed in the second catalytic converter is 0.22 m / s to 0.25 m / s.

7. The sulfur blowing passivation method of the sulfur recovery unit according to claim 1, characterized in that: In step 2, starting from K=10, the value is increased by 0.3 to 0.9 every 0.5 to 10 hours until the value of K is ≥20.

8. The sulfur blowing passivation method of the sulfur recovery unit according to claim 7, characterized in that: In step 2, starting from K=10, the temperature is increased by 0.6-0.9 every 0.5h-10h until the K value is ≥20 and the catalyst bed temperature of the first catalytic converter and the catalyst bed temperature of the second catalytic converter do not increase within 24h, and the passivation treatment is completed.

9. The sulfur blowing passivation method of the sulfur recovery unit according to claim 8, characterized in that: In step 2, during the passivation treatment, the maximum temperature of the catalyst bed in the first catalytic converter and the catalyst bed of the first catalytic converter does not exceed 280°C.

10. The sulfur blowing passivation method of a sulfur recovery unit according to any one of claims 1 to 9, characterized in that: The method further includes step 3 of simultaneously reducing the gas flow rates of air and methane gas to cool the catalyst.

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