Description of dangerous factors and preventive me

Description of phenol acetone device, risk factors and preventive measures

1. device development

the preparation of phenol and acetone by cumene method is the main technical route to obtain phenol and acetone in the world at present. Since the industrialization began in the 1950s, so far, about 90% of the world's phenol comes from this route, which plays a leading role in the world's phenol industry: in 2002, the world's phenol production capacity was about 720 × 104t/A, 91% of which adopts cumene method

the preparation of phenol and acetone by cumene method in China began in the mid-1960s, the first set of 10000 ton cumene in China; The phenol acetone plant was completed and put into operation in Yanhua company in 1970, and the first set of imported technology in China was 8 in 1986 × 104t/a cumene; The phenol acetone plant was completed and put into operation in Yanhua company, becoming the largest phenol acetone production plant in China at that time. At present, the main domestic benzene:

phenol acetone manufacturers include Yanshan Petrochemical, Gaoqiao Petrochemical, Huayu petrochemical, Jilin Petrochemical and Guangzhou Jiantao group. The process route adopted is cumene method to prepare phenol and acetone. With the continuous development and progress of technology, the production scale of phenol acetone plant continues to expand. At present, the maximum capacity of a single unit in China is 16% of that of Yanhua company × 04t/a phenol acetone unit, the maximum capacity of a single unit under construction in China is 20 × 104／a。 Germany Ineos phenol Co., Ltd. with a production capacity of 62.0 × 104t/a is the highest in the world

with the development of catalyst and production process, most production units have changed from the traditional A1C13 method to solid phosphoric acid or zeolite catalytic method. The latter is adopted by the four major manufacturers and production units under construction in China. At present, the more advanced process for preparing phenol from cumene is allied/UOP process, which is jointly developed by UOP company and United Chemical Company of the United States. 11 phenol manufacturers around the world have adopted this process

at present, many manufacturers around the world have improved the production technology of phenol and developed new production processes. Through the research on the catalyst, CHP decomposition and phenol refining in the mature process of preparing phenol from cumene, we are moving towards a shorter process route and better economic benefits.

II. Key parts and equipment

(I) key parts

1. Alkylation and transposition alkylation reaction system

it can be seen from figure 3-8 that the alkylation reaction system is mainly composed of benzene feeding pump, circulating tower, dry benzene tank, feed heat exchanger, alkylation reactor, phenylene mixer, propylene storage tank, propylene heater, propylene feeding pump, external circulation heat exchanger, external circulation pump, transposition alkylation reactor, diisopropylbenzene storage tank It is composed of cumene pump, feed mixer and feed preheater. The high reaction temperature is 160 ℃, and the high pressure is 3.1mh. Once the temperature flies, it is easy to cause overheating and overpressure, resulting in equipment leakage and fire and explosion

2. Oxidation reaction system

it can be seen from figure 3-9 that the oxidation reaction system is mainly composed of oxidizer feeding pump, oxidation inlet and outlet heat exchanger, compressor, air alkali washing tower, oxidation reactor, oxidizer circulating pump, circulating cooler, degassing tank, waste air cooler, waste air exchanger, waste air cryogenic cooler and activated carbon adsorber. Due to the thermal instability of the process product cumene hydroperoxide CHP, it is easy to decompose in case of heat, which releases a lot of heat and accelerates the test flight. The thermal decomposition reaction mainly depends on the feeling of the test pilot. Like alkali decomposition, it will not only cause the loss of CHP in the production process, but also increase the system temperature. At the same time, with the increase of system pressure, it will have a great impact on safety production. Moreover, thermal decomposition is more common and dangerous than alkali decomposition in the production process, which should be paid great attention to. At the same time, CHP will decompose with acid to produce phenol and acetone. Phenol is an inhibitor of cumene oxidation reaction. Too high content in the system will cause reaction termination, which has occurred in the production process. When CHP meets alkali, it will decompose into by-products acetophenone and dimethyl benzyl alcohol, causing the loss of CHP in the production process, and the heat released from decomposition will increase the system temperature; CHP can decompose into dimethyl benzyl alcohol and other by-products, such as divalent iron ions, initiated by variable valence metal ions. In the process of oxidation reaction, many side reactions produce organic acids, which will corrode the equipment and cause system leakage in serious cases, which should also be paid special attention

3. Concentration process

it can be seen from figure 3-10 that the concentration system consists of concentration feed pump, pre flash feed heater, pre flash separator, first cumene stripper reboiler, first cumene stripper bottom pump, second cumene stripper, first cumene stripper condenser, cumene stripper reflux trough, second cumene stripper, second cumene stripper condenser The tower kettle is composed of the second cumene stripper reboiler, the second cumene stripper bottom cooler, the second cumene stripper bottom tank, the cumene stripper reflux tank and the cumene pump. The main danger of the concentration process is the thermal decomposition of CHP, especially the two concentration reboilers are prone to local overheating of CHP, which intensifies the thermal decomposition. At the same time, special attention should be paid to the cooling of the thickener, that is, the effect of the bottom cooler of the second cumene stripper, to prevent the heat accumulation of CHP and malignant thermal decomposition accidents when the cooling water is not opened or the cooling effect is not good

4. Decomposition process

it can be seen from figure 3-11 that the decomposition system is composed of decomposition feed pump, decomposition reactor, sulfuric acid injection pump, decomposition discharge pump, mixer, decomposition reactor condenser, decomposition reactor tail gas cooler, secondary decomposition reactor and decomposition liquid cooler. Sulfuric acid is the most widely used catalyst in industry. The advantage is that it decomposes rapidly and the amount is small. At this time, the jaw should not be replaced and it needs to be recycled. The disadvantage is that CHP decomposes rapidly under the action of sulfuric acid and also emits a lot of heat. Once the process is out of control, it will explode and catch fire due to the sharp rise of temperature and pressure, Therefore, the smooth operation of the decomposition process is also the safety of the whole device, and China only began the work of safety belt safety on its birthday in 1989. For example, a good way is to limit the use of plastic bags by raising prices

(II) key equipment

air compressor is the key equipment of the whole device. Due to the factors such as large equipment, complex structure, high technical content and high price, most devices are generally equipped with only one, which is used to provide the air required for oxidation reaction. Once the outlet pipeline is blocked, it will not only stop the whole line, but also burst the pipeline and even directly damage the compressor. At the same time, the poor operation of the cooling system of the compressor can also cause damage to the compressor, leading to the shutdown of the whole line. When the air flow changes greatly, it may cause surge. Therefore, the air compressor should be taken as the key equipment of the whole device for special protection