Sulfur Recovery Unit Troubleshooting

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Sulfur Recovery Unit Troubleshooting in SRU Plant

What are the Effects of Sulfur Recovery Unit Failure?

  1. The failure of the sulfur recovery unit will cause the elemental sulfur to not be recovered normally, resulting in a sharp increase in SO2 emissions and causing environmental pollution.
    The sulfur recovery unit is the main recovery device of SRU plant and chemical plant, used to recover sulfide produced in the industrial production process. The combination of sulfur recovery unit and tail gas treatment unit can effectively reduce industrial waste gas emissions. Once the sulfur recovery unit troubleshooting is not eliminated in time, the elemental sulfur in the sulfide will not be recovered normally, which will disrupt the normal progress of the SRU process.
  2. Failure of the sulfur recovery unit will cause the shutdown of upstream industrial units and cause economic losses.
    The sulfur recovery device is directly connected to the industrial production link. If the sulfur recovery unit troubleshooting is not eliminated in time, the output of the upstream section will be reduced, and in severe cases, it may even stop work. This will bring immeasurable economic losses to the SRU plant.

Failure to troubleshoot the sulfur recovery device in a timely manner will bring about a series of serious impacts. Therefore, the sulfur recovery device and tail gas treatment device should be regularly overhauled, and problems should be dealt with in time. Ensure the normal operation of sulfur recovery equipment as much as possible. The following is a detailed description of the common problems and countermeasures of the sulfur recovery device.

High System Pressure Drop

SRU equipment maintenance
SRU equipment maintenance

The pressure of the entire system of the sulfur recovery and tail gas treatment device is very low, and the maximum allowable pressure value is only 0.05MPa (the pressure of the wind line in front of the reactor). From the perspective of equipment design, the pressure drop is mainly generated in the tube bundles of the waste heat boiler and sulfur condenser. From the actual production point of view, the pressure drop is mainly generated in the trap wire mesh, packed tower, leaked cold exchange equipment, and easy to form The location of the salt, the reactor where the carbon, sulfur, or salt deposits on the upper part of the bed, the liquid sulfur system, etc. The greater the pressure drop of the sulfur plant, the smaller the acid gas processing capacity.

To solve the problem of large system pressure drop, we should start with the following countermeasures.

  • The flow rate in the tube should be selected reasonably during the design of the exhaust gas boiler and sulfur condenser;
  • The sulfur-making supply fan should be selected as a centrifugal blower with high output air pressure, such as 0.08MPa;
  • The packed tower should be of a type that is not easy to be corroded and not
  • Optimize the operation plan, strictly control the SRU process indicators, and prevent the pressure drop of the system from increasing due to the leakage of carbon, salt, and sulfur.

Acid Gas Carrying Hydrocarbon

During the sulfur recovery process, sour gas carries hydrocarbons, which will cause over-temperature of the sulfur-making reactor, system blockage or increase of system pressure, reduction of catalyst activity, and unqualified black sulfur produced due to carbon evolution. In severe cases, it may even cause the upper part of the reactor or the trap screen to be sealed by dense carbon, preventing the process gas from passing through the reactor or trap.

Sulfur recovered by sulfur recovery system
Sulfur recovered by sulfur recovery system

To fundamentally solve the problem of carrying hydrocarbons, the operation of the upstream device should be stabilized.

Sour gas with hydrocarbons has the following performance in operation. The temperature of the sulfur-making reactor rises, and the gas-to-air ratio of the furnace air distribution to the sour gas is significantly increased, and the oxygen demand of the H2S/SO2 online analyzer still shows insufficient air supply. This is to discharge the acid gas partly to the torch or require the acid gas with a hydrocarbon device to discharge the acid gas to the torch by itself until the stove can add air, and ensure that the temperature of the sulfur-making reactor does not exceed the standard.

In this way, although a small part of the acid gas is temporarily flared, the sacrifice is much smaller than the ignorance of the impact of the acid gas with hydrocarbons on the sulfur plant, which will eventually lead to a long-term suspension of sulfur recovery, which has serious consequences for overall production.

Equipment Corrosion

Due to the characteristics of the sulfur production process in the SRU plant, the equipment and equipment mainly have high-temperature corrosion, dew point corrosion, acid corrosion, and stress corrosion.

The following methods can effectively avoid corrosion.

The way to avoid high-temperature corrosion is to reduce the temperature of the high-temperature corrosion part as much as possible. For example, reduce the contact area between the high-mix valve and high-temperature gas, and increase the cooling system for the high-mix valve core. The inlets of waste heat boilers and sulfur condensers must have protective pipes and heat-resistant linings.

The measure to avoid dew point corrosion is to ensure that the temperature of the parts prone to dew point corrosion is above the dew point temperature of water and sulfur. For example, the shutdown device keeps the steam warm, and the system is charged with N2 protection. Exhaust gas and degassing pipelines are designed to avoid excessively long and ensure uniform and sufficient heating.

The operation method to avoid acid corrosion is to strictly distribute the air to prevent excessive SO2 gas from being generated, and improve the configuration of H2S/SO2, H2, and PH value online analyzer.

Summary

The sulfur recovery unit troubleshooting should be timely and efficient. The daily production should be inspected in time, and we strive to find problems early and deal with them correctly. Only in this way can the normal and stable operation of the sulfur recovery system be guaranteed.

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