The sulfur-making combustion furnace is one of the core equipment of the sulfur recovery unit, where 60%-70% of the hydrogen sulfide is converted into elemental sulfur. It controls the process of converting 1/3 of hydrogen sulfide into sulfur dioxide and complete combustion with ammonia and hydrocarbons. It can be said to be the heart of the combined device. Therefore, the operation of the sulfur combustion furnace directly affects the sulfur recovery rate and sulfur dioxide emissions. One of the most direct factors affecting the performance of a sulfur furnace is the refractory lining of the furnace. The originally designed refractory layer was made of large corundum mullite bricks, and the thermal insulation layer was made of lightweight insulating castables. However, in the early stages of operation, the outer walls of the sulfur furnaces experienced varying degrees of over-temperature and even red heat.
The sulfur recovery and sulfur production system adopts the partial combustion method to introduce all the raw gas into the sulfur production combustion furnace. In the sulfur-making furnace, the air distribution ratio is strictly controlled according to the amount of oxygen required for complete combustion of 1/3 of hydrogen sulfide, ammonia, and hydrocarbons. The amount of sulfur dioxide generated after hydrogen sulfide is burned satisfies H2S/SO2 to be close to 2. About 60% to 70% of hydrogen sulfide and sulfur dioxide react at high temperatures in the furnace to form gaseous sulfur. The operation of the sulfur-making combustion furnace directly determines the sulfur recovery rate of the entire sulfur-making system and whether the exhaust emissions meet the standards. The components of raw sour gas are relatively complex, including H2S, CO2, H20, NH3, H2 hydrocarbons, etc. The chemical reactions that occur in the furnace are also relatively complex.
Conditions that Lining Refractory Materials Should Meet when Designing Sulfur Furnaces
Conditions that lining refractory materials should meet when designing sulfur furnaces. Able to withstand higher temperatures, the operating temperature of the sulfur furnace furnace is 1250~1400℃, which may reach 1600℃ under abnormal conditions. Since the supply of raw materials is unstable and most of them are corrosive, they must have strong corrosion resistance. There is no heating surface in the furnace, and the lining must have stable thermal shock resistance. It has stable thermal conductivity and the furnace wall temperature can be controlled to ≤300℃. For furnaces with excessively large diameters, the lining should have good high-temperature stability. It has a long service life and meets the requirements of full load and long-cycle operation. Has good volume stability. Masonry is convenient and the construction period is short.
Thickness of Refractory Material Lining Sulfur Furnace
The total thickness of the lining refractory material of the sulfur-making combustion furnace is designed to be 400mm. The refractory lining in the upper 1/2 part of the front cone section adopts a double-layer lining structure, 200mm alumina hollow ball castable + 200mm corundum refractory plastic. The acid gas inlet distribution ring bricks have a four-layer lining structure, namely 100mm lightweight insulating castable + 150mm corundum castable + 150 corundum mullite bricks + acid gas inlet distribution ring bricks. The rest of the structure is a double-layer lining structure, that is, 220mm corundum refractory plastic + 180mm lightweight heat-insulating castable. The anchoring system consists of anchor bricks with C-shaped hooks and V-shaped nails. The flower wall tiles, annular channel ring tiles, and acid gas inlet distribution ring tiles are all made of corundum mullite bricks. The anchor bricks are arranged on 2/3 of the furnace, and the center distance between adjacent anchor bricks is 400mm.
Construction of Lining Refractory Materials for Sulfur-Making Combustion Furnace
Construction method: The insulation layer is constructed by manual pounding. Use a forced mixer to mix the materials, and add water in strict accordance with the mix ratio. The mixing time is generally about 3 minutes, subject to uniform color. The mixed materials should be used within 10 minutes. It is strictly forbidden to add water to the hardened materials for reuse. The construction joints of the two layers of insulation should be staggered by more than 100mm. The insulation layer should be maintained in moisture, and the second layer of insulation or refractory plastic can be constructed only after at least 24 hours. When the entire ramming construction is completed, remove the formwork and trim the lining surface to the designed thickness. The expansion joint should be cut according to the drawing requirements, generally 60mm deep and 2-3mm wide. Horizontal and vertical expansion joints should be left at the junction of the furnace roof and furnace wall, and the joints should be filled with fiber cotton. After the lining has been trimmed, vent holes should be punched to allow moisture in the material to escape. Before and during the drying process, steam, water, oil and other impurities are not allowed to corrode the plastic. Corundum bricks should be cured naturally after being laid wet, and contact with water is strictly prohibited. The original expansion joint is widened to about 3mm, and then filled with zirconium-containing fiber blankets. The flower wall tiles and acid gas inlet distribution ring bricks are laid wet, with staggered joints, and the mortar fullness is greater than 90%. Refractory plastic is a pre-mixed and pre-pressed blank material. When using it, you only need to pound it tightly without stirring or adding binders. The construction is simple and the on-site operating conditions are good. At the same time, because plastic is a gas-thermohard material, no maintenance is required. The construction period is short and suitable for rapid repair operations of the lining. The lining structure has good thermal shock resistance and resistance to thermal stress. However, the continuity and consistency of construction must be ensured.
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