Reflection on the "fatal" dust of feed factory in Jilin poultry enterprise explosion case

Introduction: before cleaning, the liquid ammonia in the pipeline must be drained out first, because the oil in the emptying pipeline needs to be pressurized with hot air When the hot air meets the liquid ammonia in the pipeline, the liquid ammonia will be gasified into a gas more than ten times and twenty times, forming a high pressure, which will burst the pipeline OA show ('918 '); June 3 (Sun Liang, Jiang Yongqiang, Southern Rural daily) on June 3, Jilin baoyuanfeng poultry industry Co., Ltd had a major fire accident, which is said to be related to the explosion of liquid ammonia According to the fire scene rescue headquarters, as of 4:25 p.m., 119 people had been killed in the accident It is understood that Jilin baoyuanfeng poultry industry Co., Ltd was completed and put into operation in September 2009, with more than 1200 employees The company is an agricultural industrialization enterprise integrating feed, chicken breeding, chicken hatching, broiler stocking and recovery, slaughtering and processing, deep processing and sales In the production of animal husbandry and feed industry, the hidden danger of fire safety is widespread How to do a good job in daily management and eliminate the hidden danger at the source is a major problem for enterprise managers The reporter of Southern Rural daily of xinmu.com specially interviewed and understood the fire hidden danger and its causes in the main links of livestock breeding industry TDB TDB food processing plant  TDB liquid ammonia is easy to explode due to nonstandard operation TDB according to the reporter of the southern rural newspaper of xinmu.com, ammonia is the "magic weapon" of refrigeration for most of the frozen food enterprises of xinmu.com: the cheapest and energy-saving, the refrigeration effect is also ideal, and liquid ammonia cold storage is widely used by poultry enterprises Whenever the outbreak of avian influenza comes, chicken companies will store unsalable chickens in frozen warehouses, and then sell them when the price is a little better, which has become the industry practice TDB has been affected by h7n9 avian influenza since the end of March this year Many poultry enterprises of certain scale rely on this magic weapon "At present, there are only a few goods left These chickens are required to be kept below 0 ℃, and the stock of chicken in each cold store is about 60% - 70%," said Zhang Dali, vice president of Guangdong Tiannong Food Co., Ltd., a leading chicken enterprise in Qingyuan When TDB entered June, the highest temperature in many areas once reached 36.6 ℃ It became more difficult to cool down, and the refrigerators basically operated at full load According to Li Jianhua, Deputy Secretary General of cold chain logistics professional committee of Guangdong Logistics Industry Association, for refrigerators, the performance of liquid ammonia is undoubtedly the best, and it is more flexible Farms can prepare by themselves, and many large and medium-sized farms use liquid ammonia to build traditional refrigerators In addition, liquid ammonia is also considered to be more environmentally friendly, because freon, which is also a refrigerant, will destroy the ozone layer Compared with Freon, the theoretical use of liquid ammonia refrigerant can save 23% - 25% of electric energy, and even 30% - 40% in actual operation TDB, however, in fact, liquid ammonia is not perfect Li Xianguang, Deputy Secretary General of Guangdong Refrigeration Institute of xinmu.com, also acknowledges this The most common problem in the use of refrigerators is the decrease of refrigeration effect, because after the refrigerators are used for a long time, some oil will enter the pipeline, which will seriously affect the refrigeration effect In addition, due to process and other reasons, the refrigerator loses about 1% - 2% of liquid ammonia every year, so the normal maintenance of the refrigerator requires that the pipeline should be cleaned every one or two years However, the proficiency of the installation personnel directly determines the safety of the refrigerator in the future, and accidents caused by misoperation are not uncommon in these years TDB "before cleaning, it is necessary to exhaust the liquid ammonia in the pipeline first, because the oil in the emptying pipeline needs to be pressurized with hot air When the hot air meets the liquid ammonia in the pipeline that is not evacuated, the liquid ammonia will be gasified into tens to twenty times of gas in an instant, forming a high pressure, which will burst the pipeline." According to Li Xianguang's experience, in addition to the accidents caused by compressor failure, 70% of the explosions are caused by the ammonia leakage explosion caused by the operator's irregular cleaning of the pipeline In February 2013, a frozen reservoir in Baiyun District of Guangzhou city caused nitrogen leakage, which made many nearby residents uncomfortable TDB feed factory TDB "deadly" dust TDB surface, feed factory is the safest place, the location is open, the place is spacious, even the workshop door, are many times larger than other factories But if a small dust in it collides with a Mars, it may cause an unfortunate safety accident As early as a few years ago, there were explosions in feed factories in some places, many of which were directly related to dust TDB, as the main raw material of corn, can only enter the reprocessing process after being crushed Feed factory is the "concentration area" of a large amount of dust After the dust in the feed factory is heated in the silo, the particles on the surface of the dust will decompose or the combustible gases from the retort will be distributed around These combustible gases will mix with the air to form a combustible mixture, and then the combustion phenomenon will occur TDB dust which can be oxidized will explode under certain conditions Feed dust is a kind of food raw material, which is easy to oxidize It is understood that the lower explosion limit of general industrial combustible dust is between 20-60g / m3, and the upper explosion limit is between 2-6kg / m3 TDB "the most likely place for dust explosion in feed factory is the batching bin and the post crushing process" Zhang Qingyi, chairman of Foshan Gaoming Guwei feed Biotechnology Co., Ltd., told Nanfang rural daily xinmu.com that these two sections are places where a large amount of dust is concentrated and the space is relatively closed, so they have the conditions of "limited volume" TDB "must empty the silo and remove dust before welding and other operations, and at the same time, strictly isolate the silo and welding equipment to avoid the entry of sparks", Zhu Shaohua, deputy general manager of Guangdong Wang told Nanfang rural daily In this respect, the feed factory generally has strict preventive measures After welding, the field personnel of feed enterprise will carry out multiple inspections TDB general feed plants are equipped with special dedusting equipment, so there is little possibility of accidents in the production process It is understood that most dust explosion accidents are easy to occur in the process of equipment maintenance and production line modification in feed factory "Electric welding and other equipment are usually used for maintenance If strict measures are not taken, electric sparks may enter the batching bin during the welding process," said Zhang Qingyi Feed dust first catches fire, then generates a large amount of energy, releases a large amount of energy in a limited volume and a very short time, leading to dust explosion TDB is also very particular in using fire-fighting equipment to put out the fire caused by dust explosion In fact, many feed factories don't know that Zhu Shaohua told reporters, "fog water is the best extinguishing agent for dust accidents" It can extinguish the fire and damp the unburned dust, disperse and eliminate the suspended dust and reduce the air concentration However, it is not advisable to use the dry powder, two carbon dioxide and 1211 extinguishing agent to prevent the deposition of dust from causing two explosions due to impact TDB in addition, for the full price material plant, the boiler, electrical equipment and other equipment are also relatively high accident areas, "if you do not do regular scale cleaning and other maintenance, the boiler is like a time bomb." Zhang Qingyi said that safety production is more like a system engineering, which often occurs in the most easily ignored places In recent years, as one of the means of environmental protection, biogas digester is becoming more and more common in large-scale farms It can not only deal with farm manure, but also produce gas as fuel Methane, the main component of biogas, is an "unstable molecule" When the concentration of methane in the air reaches 7% - 26%, it will explode when encountering open fire TdB It is understood that the main reasons for the explosion of the biogas digester are as follows: first, after the new biogas digester is loaded, the ignition test is not conducted correctly on the air duct, causing backfire, which causes the gas in the digester to expand violently and the tank body to rupture due to explosion; second, the biogas digester is discharged too much at one time, forming a negative pressure in the tank, when the ignition gas is used, the phenomenon of internal absorption is easy to occur, resulting in the flame entering the digester and explosion On April 17, 2011, an explosion occurred in Fengqiao town, Nanhu District, Jiaxing City, Zhejiang province TDB therefore, when checking whether biogas is produced in the new biogas digester, the biogas shall be led to the cooker by the gas transmission pipe for test, and direct ignition test on the gas transmission pipe is strictly prohibited When there is a large amount of feed and discharge at one time, the gas transmission switch shall be opened to avoid negative pressure and damage to the pool The change of pressure gauge should be observed frequently If there is negative pressure in the tank, the ignition and gas should be stopped temporarily, and the fermentation raw material should be added immediately, and then it can be used after the positive pressure occurs In the process of using biogas, TDB is absolutely not allowed to use oil lamp, candle, match, lighter and other open fire at the outlet, feed inlet and air duct of the biogas digester, and is not allowed to smoke nearby or in the digester; if lighting is needed, only flashlight or explosion-proof lamp can be used "In order to prevent such accidents, we have sealed the import and export of biogas digesters and strictly controlled the entry and exit of personnel," said Chen Mingxin, a farmer in Panyu Methane poisoning caused by TDB cleaning process is also a common thing After long-term use, the gas production of the biogas digester will obviously decrease, resulting in insufficient gas supply On May 19, 2010, Xianfeng County, Hubei Province, because of cleaning the biogas digester, before entering the digester, there was no small animal experiment and any safety protection measures, a total of 5 people died before and after "It's very dangerous to go directly down to the biogas digester for cleaning It's easy to get poisoned." He Mou, a farmer in Lianjiang City, said, "therefore, we directly use a slag extractor to extract the biogas liquid from the biogas digester, and no one is allowed to go down." Before TDB enters into the pool, it is necessary to conduct animal experiments in vivo and observe for 15-30 minutes If the animals are in normal activity, people can enter the pool The personnel in the lower pool shall be equipped with strong safety rope under the armpit There shall be more than 2 people outside the pool for protection The new animal husbandry net shall pay attention to observe the safety situation of the personnel in the lower pool If there is poisoning, rescue immediately No open fire shall be lit at the entrance of the pool before entering the pool, and the personnel in the pool shall not use open fire for lighting and smoking TdB