JPH0240245A - Method and device for preventing dew condensation of waste gas from precrushing mill - Google Patents

Abstract

PURPOSE:To reduce the input of heat energy from the outside when waste gas is treated by heating the waste gas from a precrushing mill to a temp. higher than its dew point by the waste gas from a secondary crushing mill, and connecting the secondary waste gas passage to the precrushing mill or its waste gas passage. CONSTITUTION:A conveyor 3 for supplying a raw material is provided above the raw material charging port 2 of the precrushing mill 1. The raw material is crushed by the mill 1, then sent to the secondary crushing mill 4, and pulverized. The waste gas passage 5 of the mill 4 is connected to the mill 1 through the charging port 2, the passage 5 is branched, the branch passage 6 is connected to the waste gas passage 7 of the mill 1, and the opening degree can be adjusted by the damper 8 of the passage 6. The supply ore crushed by the mill 1 is sent to the mill 4, and further crushed. The driving energy and mechanical frictional force are converted into heat energy in the mill 4, hence the mill 4 is heated, and the waste gas from the mill 4 is heated to about 400 deg.C. Accordingly, if 70% of the waste gas from the mill 4 is introduced into the passage 7 and 30% into the mill 1, the dew-point temp. of the evaporated moisture in the secondary waste gas in the mill 1 is held at about 60 deg.C.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method and apparatus for preventing condensation of pre-pulverizing mill exhaust gas when a mixed raw material such as cement is pulverized in two stages using a pre-pulverizing mill and a secondary pulverizing mill. It is.

[Prior Art] For example, when manufacturing a pulverized mixed product such as cement, calcined bone-dry tarinka, gypsum and limestone containing 10 to 20% water are mixed and pulverized in a mill.

In addition, dust is removed from the exhaust gas from the mill using a filter to prevent pollution.

[Problems to be Solved by the Invention] However, the dust in the exhaust gas has a composition of cement and road gaps, and also contains water vapor, so when the temperature of the exhaust gas drops below the dew point of water vapor, it will condense. When the water comes into contact with the cement and road-composition dust trapped in the filter, the dust hardens and the filter function is rapidly impaired.

Further, even if the dust does not have the same composition as cement, the filter becomes sticky due to condensed water and the dust collection function deteriorates.

In order to prevent this, the temperature of the exhaust gas must be raised to a temperature higher than the dew point of water vapor, consuming a large amount of thermal energy.

The present invention has been made for the purpose of reducing the input of external thermal energy during pre-pulverization mill exhaust gas treatment.

[Means for Solving the Problems] The present invention provides a method for preventing dew condensation of pre-pulverizing mill exhaust gas, which is characterized by raising the temperature of pre-pulverizing mill exhaust gas above the dew point by secondary crushing mill exhaust gas, and a secondary grinding mill. This invention relates to a device for preventing condensation of pre-pulverizing mill exhaust gas, characterized in that an exhaust gas passage is connected to at least one of the pre-pulverizing mill and the exhaust gas passage.

[Function] The temperature of the pre-pulverizing mill exhaust gas containing a relatively large amount of water vapor is raised by the relatively high-temperature secondary crushing mill exhaust gas, and dust can be removed without condensation.

By flowing all or part of the secondary grinding mill exhaust gas, which has a relatively high temperature, into the pre-grinding mill or the pre-grinding mill exhaust gas flow path, the temperature of the pre-grinding mill exhaust gas is increased.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a conveyor 3 for supplying raw materials is provided above the raw material input port 2 of a pre-pulverizing mill 1, and the raw material pulverized by the pre-pulverizing mill 1 is transferred to a secondary pulverizing mill 4. Then send it to grind it even more finely. The exhaust gas flow path 5 of the secondary grinding mill 4 is connected to the pre-grinding mill I via the raw material inlet 2, the secondary grinding mill exhaust gas flow path 5 is branched, and the branch flow path 6 is connected to the pre-grinding mill I through the raw material inlet 2. It is connected to the exhaust gas flow path 7 of the mill 1, and a damper 8 is provided in the branch flow path 6 to enable the opening degree to be adjusted. In the figure, 9 indicates a dust remover, and 10 indicates a fan.

With the above configuration, for example, if the supplied ore containing about 1% water is supplied to the pre-pulverizing mill l from the raw material input port 2 at a flow rate of 150 tons per hour and is crushed by the pre-pulverizing mill 1, the pre-pulverizing mill The evaporated water in l is as follows.

The feed ore crushed by the preliminary crushing mill 1 is sent to the secondary crushing mill 4, where it is further crushed.

In the secondary grinding mill 4, driving energy and mechanical friction force are converted into thermal energy and the temperature rises, so that the exhaust gas discharged from the secondary grinding mill 4 reaches approximately 100°C and is emitted at 1000 nf/min. . Note that the evaporated water in the secondary grinding mill exhaust gas contains approximately the same amount of water as the conveying air of the preliminary grinding mill 1.

Therefore, 70% of the secondary grinding mill exhaust gas is
When 30% of is passed through the pre-grinding mill exhaust gas passage 7 and 30% is introduced into the pre-grinding mill l, the evaporated moisture in the secondary grinding mill exhaust gas introduced into the pre-grinding mill l is as follows.

The pre-pulverizing mill exhaust gas is approximately 100°C and 3 unf/ml, and the evaporated water is the total amount of evaporated water from the feed ore and the evaporated water in the introduced secondary crushing mill exhaust gas, that is, 40 n.
f/sin, and the dew point temperature becomes approximately Bθ°C. As a result, the pre-grinding mill exhaust gas is sent to the dust remover 9 without condensing in the pre-grinding mill exhaust gas flow path 7, and is further sent from the branch flow path B to the preliminary Together with the secondary grinding mill exhaust gas of about 100° C. and 700 r1f/l1in introduced into the grinding mill exhaust gas passage 7, the dust is removed by the dust remover 9 without fear of condensation.

FIG. 2 shows another embodiment of the present invention, in which the secondary grinding mill exhaust gas flow path 5 is connected to the preliminary grinding mill exhaust gas flow path 7 in substantially the same configuration as the previous embodiment. In the figure, the same reference numerals as in FIG. 1 indicate the same parts.

In the case of this embodiment, the entire amount of the secondary grinding mill exhaust gas at about 100°C is introduced into the preliminary grinding mill exhaust gas flow path 7 via the secondary grinding mill exhaust gas flow path 5, and the temperature as a whole is higher than the dew point temperature of water vapor. Then, the dust is removed by the dust remover 9 without fear of condensation.

It should be noted that the method and device for preventing condensation of pre-pulverizing mill exhaust gas of the present invention is not limited to the above-mentioned embodiments, and the entire amount of secondary-pulverizing mill exhaust gas may be introduced into the pre-pulverizing mill. Of course, various changes can be made without departing from the gist of the invention.

[Effects of the Invention] As explained above, according to the method and device for preventing dew condensation of pre-pulverization mill exhaust gas of the present invention, various excellent effects as described below can be achieved.

The high-temperature exhaust gas from the secondary crushing mill raises the temperature of the preliminary crushing mill exhaust gas above the dew point temperature, so that dust can be removed without fear of condensation.

Therefore, it is not necessary to input new thermal energy for preventing dew condensation, or it becomes extremely small, resulting in energy saving.

By providing an exhaust gas flow path for guiding the secondary grinding mill exhaust gas to the pre-grinding mill and/or the pre-grinding mill exhaust gas flow path, the thermal energy naturally generated by the secondary grinding mill can be effectively utilized with simple equipment. , stable operation can be performed without the risk of deterioration of the function of the dust remover due to dew condensation.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the apparatus of the present invention, and FIG. 2 is an explanatory diagram of another embodiment of the apparatus of the present invention. ■ is a preliminary grinding mill, 4 is a secondary grinding mill, a secondary grinding mill exhaust gas flow path, 6 is a branch flow path, a preliminary grinding mill exhaust gas flow path, 8
indicates a damper and a dust collector.

Claims (1)

[Scope of Claims] 1) A method for preventing dew condensation of pre-pulverizing mill exhaust gas, which comprises raising the temperature of pre-pulverizing mill exhaust gas above the dew point using secondary crushing mill exhaust gas. 2) A device for preventing condensation of pre-pulverizing mill exhaust gas, characterized in that a secondary grinding mill exhaust gas flow path is connected to at least one of the pre-pulverizing mill and the pre-pulverizing mill exhaust gas flow path.