Key points in designing commercial kitchen exhaust systems and solutions to ventilation problems

Anyone who has done commercial kitchen decoration knows that if the kitchen exhaust system and exhaust pipe are not designed and installed reasonably, it will cause poor kitchen exhaust and make the kitchen smoky, which will directly affect the use of the oil fume purifier. The main reason for the problem of poor ventilation in commercial kitchen design is, on the one hand, the lack of coordination between the kitchen process design profession and the ventilation design profession, and on the other hand, due to the lack of experience in kitchen design in my country, the design lacks rationality. Below Shinelong will take you to understand how to design the exhaust system of commercial kitchens. Ventilation problems of commercial kitchen equipment 1. The ventilation area of ​​the main exhaust pipe is small and the gas flow rate is too large. According to engineering experience, the wind speed in the main exhaust pipe cannot exceed 15m/s. Otherwise, after a period of operation (such as one year later), the exhaust system will be blocked. In the operation practice of the oil fume purifier, most cases are caused by insufficient ventilation area of ​​the exhaust pipe, and the gas flow rate in the pipe is above 15m/s. 2. The exhaust pipe has to pass through the building beam, which makes the ventilation cross-sectional area of ​​the pipe smaller, and the resistance on the cross section increases, resulting in poor airflow. 3. When the exhaust pipe passes through the building beam or avoids other equipment pipes, a section of the exhaust pipe will be lower than the plane of the overall exhaust pipe. After a period of use, the oil-water mixture will accumulate in the lower section of the exhaust pipe, which directly affects the smooth exhaust. 4. The kitchen fumes on different floors are discharged through the same main pipe. The exhaust effect of the kitchen on the floor close to the exit is better, while the exhaust of the kitchen on the lower floor is not smooth. Design points of exhaust system engineering 1. Local exhaust position and requirements, Chinese kitchen: The calorific value and exhaust volume of its cooking are generally large, and the exhaust volume is also large. The exhaust hood generally uses a range hood. In order to reduce the impact of oil smoke on the environment, a decontamination and washing hood can be selected. Cooking room: The requirements for fresh air here are lower, but the exhaust effect must be good, otherwise, the steam will fill the entire workshop and affect the chef's work. The exhaust is mainly water vapor, and it can be discharged directly without purification devices. Western kitchen: The cooking volume is not large, but it requires more and more complete equipment, and the exhaust volume is smaller than that of Chinese kitchen. Dishwashing room: requires a larger exhaust volume. 2. Requirements for kitchen air supply. For buildings with centralized air conditioning systems, the working environment of the kitchen can be guaranteed, and its air supply is mostly orderly air supply, which is also more flexible. In the current kitchen ventilation system, there are mostly the following three air supply methods: (1) The restaurant air conditioning is a fresh air direct current air conditioning system. The conditioned fresh air is first sent to the restaurant, then flows into the kitchen and is discharged to the outside through the exhaust system. This method requires less investment and has good heating and ventilation effects in the restaurant. The disadvantage is that a large amount of conditioned air will be directly discharged, and the fresh air energy consumption is large, which is not conducive to energy saving. (2) Part of the fresh air of the combined air conditioning unit is directly supplied to the kitchen, and part is sent to the restaurant, and then returned to the air conditioner through the return fan. This can partially solve the problem of high fresh air energy consumption, and at the same time it is more flexible to use. A pressure measuring device can be installed in the kitchen. When all the kitchen exhaust fans are working, the negative pressure increases, the return air electric valve is closed, the return air fan stops, and the restaurant air is supplied to the kitchen in large quantities; when a small number of exhaust fans are turned on or the exhaust fans are not working, the negative pressure is not very large, the return air electric valve is opened, and the return air fan is started to prevent all the air conditioning air from being discharged. (3) Use two units to serve the restaurant and kitchen respectively. The kitchen is a fresh air direct current system, which directly supplements the exhaust of the kitchen stove, while the restaurant is a single return fresh air system. This solution can ensure the air conditioning effect of the restaurant and kitchen, and the kitchen and restaurant systems do not interfere with each other. The disadvantage is that the initial investment is large. 3. System layout, the horizontal section of the kitchen exhaust duct should not be too long. Generally, the longest horizontal distance should not exceed 15m and there should be a slope of more than 2%. A flexible joint is set at the horizontal end to facilitate the cleaning of grease. According to the specification, the exhaust speed shall not be less than 10m/s to prevent the wind speed from being too low and causing oil to adhere to the flue. The branch pipe connected to the exhaust hood should be equipped with an air volume regulating valve. The air supply system should be a direct current mode. The ventilation system of the kitchen should use a variable speed fan or an associated fan for air supply and exhaust. The layout of the air supply and exhaust outlets in the kitchen should be considered according to the specific location of the stove. Do not let the air supply jet disturb the exhaust performance of the stove. When determining the outlet wind speed of the air supply outlet, the regional wind speed of 0.25m/s at about 2m from the ground is ideal. The air supply outlet should be arranged along the direction of the exhaust hood, leaving the front of the hood at least 0.7m, and the exhaust outlet is as far away from the exhaust hood as possible. Each cooking kitchen must have a post air supply. Arrangement of the machine room, fan and air duct The kitchen exhaust fan should be located in the upper part of the kitchen. When the kitchen is part of a public building, its exhaust fan should be located on the roof layer, which can keep the air duct in a negative pressure state and avoid odor overflow. The kitchen exhaust fan should generally use a centrifugal fan, and the kitchen exhaust duct should try to avoid excessively long horizontal air ducts. The kitchen exhaust duct should try to avoid excessively long horizontal air ducts. The kitchen exhaust shaft is best placed close to the smoke exhaust duct to increase the suction force. 4. Fire prevention, smoke exhaust, and kitchen exhaust systems should be divided according to fire protection zones. Try not to pass through fire walls. Fire dampers should be installed when passing through. The pipes of the kitchen ventilation system should be made of non-combustible materials. Keywords: Guangzhou kitchen equipment, stainless steel kitchen equipment.