Refractory Materials for Chemical Hazardous Waste Furnaces

In hazardous waste incineration devices, rotary kilns are usually built with chrome-zirconium-corundum, chrome-corundum, corundum, and corundum-mullite refractory bricks, and only castables are used at both ends of the kiln. The commonly used refractory bricks are mainly chrome-zirconium-corundum, chrome-corundum, corundum, corundum-mullite refractory bricks, mullite bricks, high-alumina bricks, etc., and the castables are mainly corundum and corundum-mullite refractory castables.
Refractory materials for hazardous waste incineration rotary kilns should have the following characteristics:
(1) High temperature resistance, low thermal expansion coefficient, high thermal conductivity, good thermal vibration resistance, high high temperature strength, acid, alkali and salt corrosion resistance, no wetting by metals and slag, and light weight. Refractory materials are suitable for the complex kiln environment of hazardous waste rotary kilns and can operate for a long time in a high temperature environment above 800℃.
(2) High strength and good wear resistance. The refractory materials used for rotary kiln lining need to have a certain mechanical strength to withstand the expansion stress at high temperature and the stress caused by the deformation of the rotary kiln shell. At the same time, because hazardous waste and dust in the flue gas will cause wear on the kiln lining, it is required to have strong wear resistance.
(3) Good chemical stability to resist the erosion of chemical substances in the flue gas. The greatest impact on the quality of refractory materials is alkali (potassium, sodium), halogen (chlorine, fluorine) and sulfur compounds.
(4) Good thermal shock resistance, able to withstand the alternating thermal stress of the incineration state. When the furnace is stopped, started, and the rotation condition is unstable, the temperature change in the kiln is relatively large, which requires that the refractory materials should not crack or peel off when the temperature changes drastically.
(5) Good high-temperature volume stability. Although the thermal expansion coefficient of the rotary kiln shell (usually carbon steel plate) is greater than that of the rotary kiln refractory material, the shell temperature is generally around 150-300°C, while the temperature of the refractory material is generally above 800°C. This may cause the refractory material to have a larger thermal expansion than the rotary kiln shell and be easy to peel off.
(6) Low porosity. If the porosity is high, the flue gas will penetrate into the refractory material and corrode the refractory material.

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Description

It has characteristics of erosion resistance, high strength, good thermal shock resistance, heat insulation and soon.When used in chemical industry waste incinerator, it overcome previous poor corrosion resistance ,wear resistance and thermal shock stability.lt improve the resistance to spalling with Increasing the service life from 3~7months to more than 12 months.

"Research on the allocation of refractory materials for chemical hazardous waste rotary kiln" has been listed as the key project of innovation and development in Zibo city.In 2018, "Research on corundum mullite composite bricks for hazardous waste rotary kiln in chemical industry" was appraised as the international advanced level through provincial appraisal, and won the first prize of metallurgical science and technology progress of Shan-dong province.

Refractory materials for chemical hazardous waste treatment (refractory materials for rotary kiln)

1: Selection of refractory materials for lining of chemical rotary kiln system

(1) The furnace temperature of chemical rotary kiln is high. The working temperature is 1100~1450℃, which is a furnace with relatively high working temperature. In occasional working conditions, the furnace temperature may reach 1600℃ or higher.

(2) There are many corrosive components such as H2O, H2S, SO3, SO2 and S vapor in the furnace of chemical rotary kiln. H2S has reducing properties, which imposes strict restrictions on certain impurity components in the furnace lining materials.

(3) Chemical rotary kiln is an acid gas combustion furnace. There is no heat extraction surface inside the furnace. Any large fluctuation under combustion conditions means a thermal shock to the furnace lining. Therefore, the furnace lining is required to have good thermal vibration resistance.

(4) Chemical rotary kiln combustion furnace has strict requirements on wall temperature, which requires the furnace lining material to have good thermal conductivity.

Products Description

2: Selection of refractory materials for the lining of the chemical rotary kiln system

2.1 Corundum castable material

The lining material of the acid gas reactor of the chemical rotary kiln unit is generally made of corundum castable lining. The reason is that the corundum castable lining not only has a high refractory temperature, but also has good wear resistance. However, due to its poor thermal vibration resistance, it may have problems such as peeling and falling off in a short period of time.

2.2 High alumina brick + corundum brick material

The lining material of the original acid gas combustion furnace of the chemical rotary kiln is high alumina brick + corundum brick material. Its brick joints are one of the weakest links. Due to the damage of the brick joints, the overall deformation and collapse of the masonry often occur. On the other hand, high alumina bricks and corundum bricks are difficult to process and manufacture, and it is difficult to fit some special-shaped parts, and the cost is also high.

2.3 Steel fiber castable material

Steel fiber castable has good fire resistance and has achieved good results. However, in the case of acid gas combustion furnace, this material is prone to problems such as agglomeration and deep cracks.

2.4 Combination of castable and prefabricated parts

The combination of chemical rotary kiln castable and prefabricated parts is a very good solution with the following significant features: ① High temperature resistance (up to 1200-1800℃) and high strength. ② The furnace wall support is hanging type, not easy to deform or fall off. ③ The insulation layer is poured and the working layer is rammed. It can be made into any shape (especially in special shapes). It is easy to construct, and its combined structure is dense and solid, and there is no gap in the kiln wall. ④ When the lining is supported by anchors, the furnace wall can withstand peeling and protrusion, and maintenance is convenient. ⑤ The lining material has good anti-peeling properties and will not embed foreign matter. ⑥ The furnace baking time is short, and the construction is fast and economical.

Brand ltem	GAM-85 Corundum mullite composite brick		SGA-85 Cylon combined corundum composite brick		(GGA-80)Chrome corundum composite brick		(GGZ-80) Chrome zirconium corundum composite brick		MSL75 Corundum mullite wear resistant castable		GGAL80 Corundum wear resistant castable
Brand ltem	Heavy part	Light part	Heavy part	Light part	Heavy part	Light part	Heavy part	Light part	MSL75 Corundum mullite wear resistant castable		GGAL80 Corundum wear resistant castable
Al₂O₃ %	≥84	≥60	≥85	≥60	≥80	≥60	≥80	≥60	≥75		≥75
Cr₂O₃ %			SI4N3+ALS-ION≥3%				≥3
ZrO₂ %							≥3
Fe₂O₃ %	≤0.35	≤1	≤0.35	≤1	≤0.35	≤1	≤0.35	≤1	≤1		≤1
g/cm³ Bulk Density	2.95	≤2	2.9	≤2	3.1	≤2	3.1	≤2	110℃*24h≥2.9		110℃*24h≥3
MPa Cold Crushing Strength	≥120	≥20	≥120	≥20	≥130	≥20	≥120	≥20	110℃*24h≥90	1300℃ after burning ≥80	110℃*24h≥100
T2℃Refractoriness Under Load	≥1700		≥1700		≥1700		≥1700
Thermal shock stability (DIN standard) (950℃, full water cooling) times	≥30		≥30		≥30		≥30
% Permanent Linear Change	1300℃*2h±0.2		1300℃*2h±0.2		1300℃*2h±0.2		1300℃*2h±0.2		1100℃*2h±0.3		1100℃*2h±0.3
Application	Front and rear ends of rotary kiln		Rotary kiln high temperature section		Rotary kiln high temperature section		Rotary kiln high temperature section		Rotary kiln front end and kiln head cover		Rotary kiln tail

Brand/ltem	MS70 Mullite	MSL70 Corundum mullite wear resistant castable		GGAL75 Chrome corundum wear resistant castable	Acid proof castable
Al₂O₃ %	≥70	≥70		≥75	≥25
Cr₂O₃ %				≥3	SIO2≥65
Fe₂O₃ %	≤1	≤1		≤1
g/cm³ Bulk Density	≥2.55	110℃*2h≥2.9		110℃*2h≥2.9	110℃*2h≥2.9
MPa Cold Crushing Strength	≥80	110℃*24h≥90	1300℃ after burning ≥80	110℃*2h≥100	110℃*2h≥25
Refractoriness Under Load T2℃	≥1550				Acid resistance ≥98
Thermal shock stability (DIN standard) (950℃, full water cooling) times	≥20
% Permanent Linear Change	1300℃*2h±0.3	1100℃*2h±0.2		1100℃*2h±0.2
Application	Middle of the secondary combustion chamber	Upper part of secondary combustion chamber, pipeline		Second combustion chamber lower part	Quenching tower

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