If the direction of the switch of the smoke hood is wrong, you can reopen the eyes and then reinstall the switch. If you want to switch the wires on and off, there must be several wires to reinstall. Just take it offline and it will be normal
The smoke exhaust hood is a device installed at the flue gas outlet of the water heater. It is used to reduce the impact of backdraft on the combustion performance of the burner; it is beneficial to smoke exhaust and flue Facilitates the escape of smoke when blocked. [1]
The smoke exhaust hood is composed of the upper and lower parts of the cover body and the cover. The cover body is composed of three planes, and the cover is composed of four planes (front, rear, left and right) (or called baffle). plate) forms a cone.
Chinese name
Fume hood
Foreign name
Fume hood
Composition
< p>Cover body and coverThe cover body
is composed of three planes
The cover
is composed of front, rear and left , composed of four planes on the right
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Types and characteristics
Fume exhaust hood design
Requirements
Product Introduction
The smoke exhaust hood is composed of the upper and lower parts of the cover body and the cover. The cover body is composed of three planes, and the cover is composed of front, rear, left and right parts. Four flat surfaces, or baffles, form a cone. The lower end of the cone is connected to the cover body, and the upper end is connected to the range hood. The movable baffle is opened on the cover body or any side of the cover close to the window. The front baffle has a notch that is beautiful and delicate, and the range hood is thoroughly extracted without pollution. Environmentally friendly, conducive to human health, simple structure and low cost.
Schematic diagram of smoke exhaust hood
The schematic diagram of smoke exhaust hood is shown on the right.
The iron exhaust hood is just a rectangular iron cover with a hole on it to connect to the exhaust pipe and it is placed over the stove. The principle of rising hot air is used to naturally draw oil fumes out of the room. This type of smoke exhaust hood has simple technology and low cost, but the smoke exhaust effect is poor and is only suitable for small eating places with little smoke. Currently there is no final product, but it is made on-site according to the size of the stove. [2]
Types and characteristics
Umbrella exhaust hood
This kind of exhaust hood is mainly used for dishwashing sinks, dishwashers and small To remove hot and polluted gas from a single cooking equipment, it is usually installed above the equipment, and there is generally no filtering and purification device. The umbrella covers used in kitchens are mostly rectangular in cross-section. It is characterized by simple structure, easy manufacturing, and good exhaust effect when the air volume design is reasonable. It is a necessary equipment in the kitchen.
Oil mesh exhaust hood
This is the most commonly used type of exhaust hood in the kitchen. The horizontal projection surface of the hood is rectangular, and the cross section is like a half umbrella-shaped hood. . The length is determined by the number and placement length of the stoves. The height is 550 mm, the width is generally 1250 mm, and the total width of the front air supply device is about 1500 mm. One side of the cover is equipped with a labyrinth oil filter at a slope of 60°, which has a certain oil fume filtering ability and is often used in the kitchens of general restaurants.
The technical parameters of commonly used oil mesh exhaust hoods are shown in the following table:
Resistance/Pa
Fume hood/mm
Send Fresh air duct/mm
Applicable stove depth/mm
Fan power/kW
Length
Deep
High
Long
Deep
High
Wind Ball
<100
6000
1250
550
6000
550
350
< 1000
4
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Transporting water hood
The water with washing liquid is pressurized by the water pump and then sent to the hood The inside of the cover is sprayed in a fan shape, and the oily gas coming up from the bottom of the cover is decontaminated and purified in contact with the fan-shaped water surface, while the water is separated by the gas-liquid separation fan and flows back to the water tank. This is basically how a shisha hood works. The water hood has a complete automatic control system for sewage discharge, water addition, washing liquid addition, circulation, etc., which is very convenient to operate. The oil removal rate of the gas purified by this hood can reach about 90% and basically no longer pollutes the pipeline. Due to the isolation effect of water mist, this kind of hood also has a certain fire prevention function.
The technical parameters of commonly used water hoods are shown in the following table:
Resistance/Pa
Hood/mm
Fresh air duct /mm
Length
Depth
Height
Length
Depth
Height
Water pump
Power/kW
<120
<4600
1350
685
618
527
1950
Single
1.1
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Impact flow oil fume purification exhaust hood
This equipment is a patented product, which adopts the principle of impingement flow. Its core technical equipment is an active high-speed gas-liquid contact device. This equipment has the characteristics of high mass transfer coefficient, small size, high purification efficiency and low energy consumption. Its oil fume purification efficiency can reach more than 95%. The reaction box in the system has a gas-liquid contact mechanism without mechanical power and control devices. It is an oil fume purification device with higher purification efficiency, lowest operating cost and smallest volume among existing oil fume purification equipment. The technical data of the impact flow oil fume purification exhaust hood are shown in the following table:
Fume exhaust hood design
The exhaust hood using natural smoke exhaust is required to produce a certain amount of suction force so that it can Exhaust all smoke and surrounding air that should be exhausted. If the flue gas flow is unstable, or the density of the flue gas and the surrounding air is not much different, it is reasonable to use a natural exhaust hood.
(1) Determination of the shape and size of the exhaust hood for horizontal smoke emission sources
The cross-sectional shape of the exhaust hood opening should be as similar as possible to the horizontal projection of the smoke emission source.
The retraction angle of the smoke exhaust hood should be equal to or less than 60°, and the maximum should not be greater than 90°. In order to reduce the height of the smoke exhaust hood, the long sides of the rectangular smoke exhaust hood with longer sides can be set in sections.
The smoke exhaust hood should have a vertical edge (skirt) of a certain height, and the height of the vertical edge (is the area of ??the hood).
The cross-sectional dimensions of the mask mouth are calculated according to the following formula:
The picture on the right
The meaning of each symbol in the formula is shown in the picture on the right (a).
(2) Determination of the smoke emission source of the vertical furnace door and the size of the smoke hood'
The common form of installing a smoke exhaust hood above the vertical furnace door is shown in (b) on the right Show. The size A of the smoke exhaust hood can be determined according to the formula, but to determine the size B of the hood, the size b of the smoke emission source must first be determined. In addition to being determined based on empirical data in production practice, it can also be calculated and determined using theoretical methods.
As shown in the figure on the right, if rectangular coordinates are set along the outer surface of the furnace wall and the zero-pressure surface, then the coordinates of the plane of the exhaust hood are. There is a gas particle unit with a volume of dV, which is ejected out of the furnace. The starting point is A(h, 0). It is obvious that under the combined effect of horizontal ejection velocity and vertical upward buoyancy force, it will move to A'(h, L). Under the condition of neglecting the viscous force, the equation in the vertical direction can be listed to calculate the upward acceleration a ( ), and it can be simplified to:
In the formula, - the gravity of the surrounding air , ;
——The intensity of the smoke ejected, ;
g——The acceleration of gravity, .
When the particle unit moves to the A' position, the distance moved in the horizontal direction can be obtained by the following formula:
In the formula, L——when the particle unit reaches the smoke exhaust hood , the distance moved in the horizontal direction, m;
——Horizontal ejection speed, m/s;
——The distance from the smoke exhaust hood El plane to the zero pressure surface, m;
——The distance from point A to the zero pressure surface, m.
Substituting the formula into the formula, we can get:
The above formula shows that when the gas in the furnace is ejected by the geometric pressure head, the maximum ejection distance depends on the zero pressure surface to the exhaust hood distance from the mouth plane.
(3) Calculation of smoke exhaust volume
The smoke exhaust volume V ( ) of the smoke exhaust hood is calculated according to the following formula:
In the formula, F—— Cross-sectional area of ??the mask mouth, ;
——The average flow velocity on the cross-section of the mask mouth, m/s.
The following values ??are recommended:
Fume exhaust hood open on four sides: 1.05~1.25m/s;
Fume exhaust hood open on three sides: 0.9~ 1.05m/s;
The exhaust hood with two sides open: 0.75~0.9 m/s;
The exhaust hood with one side open: 0.5~0.75 m/s. [4]
Requirements
(1) The oil fume absorption rate should be greater than 95%, and the same diversion and enclosure device should be used.
(2) The enclosure structure should be equipped with hinged inspection doors to facilitate hygiene, cleaning and observation.
(3) The equipment is all made of stainless steel, and all connections are waterproof, steam-proof, and oil-smoke-proof.
(4) The air hood is embedded in the suspended ceiling, with a stainless steel decorative plate between them. It is made of stainless steel plate with a thickness of 1.2mm. It is easy to disassemble and has an embedded depth of ≥100mm.
(5) All cover bodies are made of stainless steel plates with a thickness greater than 1.0mm.
(6) The ventilation pipe is made of 1.0 galvanized sheet and is equipped with a stainless steel air volume regulating valve.
The above is to introduce you to some relevant knowledge about smoke hoods. If I mention it first, it will actually be of some benefit to you in our market life