Smoke exhaust in small restaurants

Problem 1: In kitchen ventilation engineering, smoke exhaust fans and fume purification equipment consume a lot of electricity, and the exhaust effect of fans is not good. Reason: All the pipes of the range hood in the whole kitchen are finally concentrated in a large air duct system, which is discharged by a large oil fume purification device and a large fan. As a result, as long as there is a stove in the kitchen, the exhaust fan and the lampblack purifier have to be turned on. In this way, not only the exhaust effect of the fan is not good, but also the power consumption is very high. In high-end hotels, the electricity consumption of kitchen ventilation accounts for about 2.8% of the total electricity consumption in the whole year. Solution: Divide it into two or three systems according to the specific situation, or adopt variable speed fan, which is fully open at peak load. The peak use time of kitchen stoves is about 4~5 hours, and the rest time is processing preparation or sanitation time, so there is no need for large exhaust volume.

Question 2: The air supply system of the hotel kitchen adopts the following modes: 1, and the air treatment mode adopts partial return air; 2. Adopt fan-coil unit; There is no air supply system in the kitchen, only one air cooler. After less than one year's use, the efficiency is greatly reduced, which leads to the high temperature in the kitchen. Reason: These equipments have their own water-cooled surface coolers or direct evaporative surface coolers. The air in the kitchen is in direct contact with the cooler, and the oil mist will soon pollute and block the gaps between the fins on the surface cooler, which will greatly reduce the air volume and cause the kitchen temperature to be too high and the effect is not good. Solution: Return air cannot be used in the fresh air supply system of the kitchen. Only DC system can be used. According to outdoor conditions, DC air conditioning system or DC air supply system can be used. Window or cabinet air conditioners are not suitable for use in the kitchen.

Problem 3: Cooling failure of fan coil in kitchen. The kitchen is equipped with a stove exhaust system, a fresh air supplement system and a fan-coil refrigeration system. When it was first put into production, the effect was quite good. After a year, the temperature can't drop, sometimes reaching above 35℃, which is unbearable for the staff. Reason: After inspection, it was found that there were a lot of oil mist and water vapor in the kitchen, especially the oil fume after gas combustion attached to the surface of the coil, which greatly reduced its heat transfer coefficient and the refrigeration effect became worse and worse. Solution: Insert the fan coil into the air return opening of the kitchen, and then lead the air from the restaurant as the return air of the fan coil in the kitchen with pipes, while reducing the outdoor air volume. (Fan coil system cannot be used in kitchen design)

Question 4: The flame of the kitchen gas stove is sprayed out of the oven door, which affects the normal use. Cause: Improper proportion of air intake and exhaust in the kitchen leads to high negative pressure in the kitchen. Solution: Kitchen with mechanical exhaust system should consider supplementary air intake. The kitchen negative pressure value shall not be greater than 0.5 mm water column. If the negative pressure is too large, the furnace will be downwind, that is, the seedlings will be ejected. To achieve this goal, generally speaking, the air supply volume should be 85%~95% of the exhaust air volume.

Question 5: Interrogation between the kitchen operation room and the dining room. The kitchen is adjacent to the restaurant, which makes people feel uncomfortable and makes the environmental quality of high-end restaurants not fragrant enough and elegant enough. Reason: The air distribution in the kitchen and dining room is not good, which should be negative pressure in the kitchen and positive pressure in the dining room. Sometimes, because the windows are open in the kitchen, the air in the kitchen will flow into the restaurant, so that there is an unpleasant smell between them. Solution: In order to prevent the backflow of kitchen odor, besides setting aisle transition between the kitchen and the dining room, 60% of the kitchen exhaust volume should be supplemented by the dining room. That is, 60% of the air supply from the kitchen is sent to the restaurant, and then flows from the restaurant to the kitchen. However, it should be noted that the wind speed of the airflow entering the kitchen from the restaurant should not be greater than 1m/s when passing through the dining opening.

Question 6: The conference hall of a high-class hotel smells like cooking in the kitchen. Reason: The air outlet of the kitchen is close to the outdoor air inlet of the air conditioner, and the air inlet is located in the downwind direction of the air outlet. The air intake is not clean, and the smell of the kitchen is sent into the building, causing "odor". Solution: The fresh air inlet should be located in a clean place, on the windward side of the exhaust port and below the exhaust port. Civil buildings should try to avoid the same direction of air inlet and kitchen exhaust outlet.

Question 7: The accumulated water in the kitchen exhaust sleeve will freeze, which will affect the use. Cause: In cold and cold areas, the exhaust fan of the kitchen is located outdoors. In winter, water vapor and oil mist in waste gas condense and turn into ice at night. The next day, when the kitchen was working, the exhaust fan couldn't start, and even the stove couldn't vent, and it was dripping down. Solution: (1) Pay attention to the direction of the fan and try to choose the centrifugal fan with horizontal outlet. If it is necessary to choose a fan with an upper outlet, a drain pipe should be installed at the bottom of the fan housing to discharge fashionable water. The outdoor part of the fan is insulated from the air duct. (2) The horizontal pipeline shall have a slope greater than 2%, and the slope shall be in the direction of the exhaust hood. (3) The speed in the exhaust pipe is generally about10m/s (4) The fan should be located in the exhaust room, not outdoors.