Preheating temperature

The heat source for the preheater temperature is steam; in other words, the temperature is controlled by regulating the flow rate of steam.

How far does the early shift control extend? What about the middle grade? How much for the night shift? What is the maximum limit?

The preheating temperature is determined based on the melting point of the lubricant; it must not exceed that melting point. In winter, for lubricants like molybdenum disulfide, the preheating temperature is usually around 50 degrees

The lower limit of the preheating temperature is set to prevent water vapor in the gas from condensing and liquefying inside the pipes, thereby avoiding blockages. How is the upper limit of this temperature determined? If we were to determine it based on the melting point of molybdenum disulfide, as you said, its melting point is 1185 degrees – so why is the control set at only 50 degrees?

If the furnace gas is properly purified, there is no need for a very high preheating temperature

The main purpose of installing a preheater for coke oven gas is to prevent the precipitation of naphthalene in the gas from blocking pipes and orifice plates; a temperature range of 45 to 55 degrees is generally sufficient.

Calcium molybdenum disulfide-based grease: It is mainly used for lubricating the rolling bearings and areas that are prone to contact with water or moisture in various industrial and agricultural machinery, such as cars, tractors, water pumps, and small to medium-sized electric motors. Since calcium-based greases are mainly used inside compression cups, they are also referred to as “cup greases”. Rolling bearings with a temperature range of –10°C to 60°C and a rotational speed of below 3000 r/min can generally be used. Type 1# is suitable for centralized grease supply systems and friction grooves in vehicle chassis, with a maximum operating temperature of 55°C. Grade 2# is suitable for rolling bearings in general medium-speed, light-load applications in small and medium-sized machinery such as electric motors, water pumps, and blowers, as well as for lubricating components in vehicle and tractor hub bearings and clutch bearings, and for the corresponding lubrication parts in various agricultural machines. Its maximum operating temperature is 60°C. Type 3# is suitable for bearings in various medium-sized machines with moderate loads and speeds, with a maximum operating temperature of 65°C. Grade 4# is suitable for heavy mechanical equipment under heavy loads and at low speeds, with a maximum operating temperature of 70°C. 3. The characteristics of calcium-based greases are as follows: (1) Since calcium soaps form hydrates with water, it is only in the form of these hydrates that calcium soaps can create highly dispersed fibers within mineral oil. The hydrates of calcium soaps hydrolyze at around 100°C; this is why calcium-based greases gradually lose their viscosity above 100°C, which limits the temperature range in which they can be used. It generally should not exceed 60°C; if this temperature is surpassed, calcium-based lubricants will soften or even disappear, thus failing to provide proper lubrication. (2) Calcium-based greases have good water resistance; they do not become emulsified or deteriorated when exposed to water, making them suitable for lubricating mechanical components in humid environments or those that come into contact with water. (3) Calcium-based greases possess good shear stability and thixotropic stability; even after being stirred during use and then allowed to rest, they remain on the surface in contact with the components, providing a sealing effect that prevents them from spilling out. (4) Calcium-based greases have good pumpability, as their fibers are shorter and they possess a lower strength limit. When using the same mineral oil and achieving the same consistency, calcium-based greases are easier to pump than other soap-based (such as sodium-based or aluminum-based) greases. Although calcium-based greases are an old type of grease dating back to the 1930s, they are still widely used in China today. They can be employed to lubricate rolling and sliding bearings with moderate speeds and loads in applications such as small and medium-sized motors, water pumps, tractors, automobiles, as well as machinery in the metallurgy and textile industries. Calcium-based greases are primarily used inside compression cups, which is why they are called cup greases. Early calcium-based greases were commonly known as “butter”.