RU2085259C1 - Bag filter - Google Patents

Abstract

FIELD: dedusting of gases in various industries. SUBSTANCE: bag filter is provided with additional gas line connected with contaminated and pure gas headers. Additional gas line is fitted with two cut-off valves with atmospheric valve between them. In firing up the furnace with furnace fuel, valve fitted in inlet branch pipe is shut off and contaminated gas escapes to atmosphere through additional gas line, thus excluding condensation of sulfur dioxide on filter bags. After firing up the furnace, filter is placed in operation. Contaminated gas is fed to filtering section. Atmospheric valve fitted in additional gas line opens and cut-off valves close creating excessive pressure between them, thus letting no dust-laden gas into pure gas passage. EFFECT: enhanced efficiency. 2 dwg

Description

 The invention relates to devices for cleaning gases from dust and can be used in metallurgical, chemical and other industries where complete dust removal is required.

 Known bag filter comprising a housing with filter bags, a hopper, collectors of dusty and purified gas, a dusty gas channel, an additional gas pipeline, valves.

 A disadvantage of the known device is a violation of the sealing of the valve located on an additional gas pipeline between the collectors of contaminated and clean gases, which leads to a sharp increase in the residual dust content. In addition, the known device does not provide a mode of kindling a cold furnace with heating oil, which leads to the destruction of the fabric of the sleeves by sulfur compounds (at a gas temperature below the dew point).

 The objective of the invention is to increase the efficiency of gas purification and increase the service life of the sleeves.

This goal is achieved by the fact that the third shut-off valve and atmospheric valve are installed on an additional gas pipeline, while the atmospheric valve is located between the first and third shut-off valves. The volume of supplied atmospheric air is determined by the cross section of the atmospheric valve and is sufficient to seal the gas pipeline and is equal to the amount of gas previously sucked through the valve leaks. The cross-section of the atmospheric valve is calculated by the formula S ₁ f • S ₂ , where S _{1 is} the opening area of the atmospheric valve, S _{2 is} the cross-sectional area of the additional gas pipeline.

 Figure 1 shows the proposed bag filter; figure 2 scheme of sealing an additional gas pipeline.

 The bag filter contains a housing with filter bags 1, a dust collector 2 connected to it, which is divided by a horizontal partition 3 into a dust gas channel 4, in which a second shut-off valve 5 is installed, and an additional gas pipe 6 with a first shut-off valve 7 and a third shut-off valve 8 and an atmospheric valve 9 connected to the purified gas manifold 10. The housing 1 is equipped with a dust bin 11.

 Bag filter is used as follows. When a cold furnace is fired up with heating oil to prevent fuel vapor from entering the filter baghouse, valve 5 and (poppet) atmospheric valve 9 are closed and valves 7 and 8 open, fuel vapor flows through the dusty gas manifold 2, additional gas pipe 6, valves 7 and 8 enter into the channel of the purified gas 10 and further into the atmosphere. After igniting the boiler, at the same time closing valves 7 and 8, valve 5 and valve 9 open, and dusty gas flows through the manifold 2, valve 5 enters the hose room and then into the purified gas channel 10. When the atmospheric valve 9 is activated, atmospheric pressure is maintained for valves 7 and 8 , which ensures complete exclusion of dusty gas entering the channel of the purified gas.

Из (1)

Для выполнения условия движения подсасываемого атмосферного воздуха только в направлении клапана 7 (с целью минимального поступления воздуха в систему очистки) необходимо P₂=P₃.The pressure drop (P ₀ P ₁ ) leads to the absorption of air through the opening of the atmospheric valve 8. The process in this case is described by the expression:

From (1)

To fulfill the conditions of movement of sucked-in atmospheric air only in the direction of valve 7 (with the aim of minimizing the flow of air into the cleaning system), P ₂ = P ₃ .

Из (3)

Необходимая S₁=f•S₂
Обозначения:
P₀ атмосферное давление,
P₁ разрежение в канале очищенного газа,
P₂ разрежение в полости дополнительного газопровода между отсечными клапанами,
P₃ разрежение в полости дополнительного газопровода,
S₁ площадь отверстия атмосферного клапана,
S₂ средняя площадь поперечного сечения дополнительного газопровода между отсечными клапанами,
ρ плотность газа,
x₁ коэффициент гидравлического сопротивления отсечного клапана, установленного перед атмосферным клапаном,
ξ₂ коэффициент гидравлического сопротивления атмосферного клапана,
U скорость истечения воздуха через отверстие атмосферного клапана,
f величина, определяющая соотношение S₁ и S₂

Целесообразно отметить, что за время прохождения загрязненного газа по дополнительному газопроводу 6 (при разжигании холодной топки) какое-то количество пыли проникает в атмосферу. Однако этот промежуток времени мал по сравнению с продолжительностью номинального режима работы топки.In this case, we obtain

From (3)

Required S ₁ = f • S ₂
Designations:
P ₀ atmospheric pressure
P ₁ depression in the channel of the purified gas,
P ₂ rarefaction in the cavity of the additional gas pipeline between the shut-off valves,
P ₃ rarefaction in the cavity of the additional gas pipeline,
S _{1 the} area of the opening of the atmospheric valve,
S _{2 the} average cross-sectional area of the additional gas pipeline between the shut-off valves,
ρ gas density
x ₁ coefficient of hydraulic resistance of the shut-off valve installed in front of the atmospheric valve,
ξ ₂ coefficient of hydraulic resistance of the atmospheric valve,
U the rate of air flow through the opening of the atmospheric valve
f value that determines the ratio of S ₁ and S ₂

It is advisable to note that during the passage of contaminated gas through an additional gas line 6 (when igniting a cold furnace), a certain amount of dust enters the atmosphere. However, this period of time is small in comparison with the duration of the nominal operating mode of the furnace.

Claims (1)

 A bag filter including a housing with filter bags, a hopper, dusty and purified gas collectors, a dusty gas channel, an additional gas pipeline, an atmospheric valve, three shut-off valves, one of which is mounted in an additional gas pipeline, and the second in a dusty gas channel, characterized in that the third shut-off valve and the atmospheric valve are installed on the additional gas pipeline, while the atmospheric valve is located between the first and third shut-off valves.

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