Ethanol fermentation and its inflammable and explosive problem prevention

As an important chemical substance, ethanol is not only widely used in industrial production, but also widely used in daily life as a fuel and solvent. Its production is usually done through the fermentation process, which is not only efficient and low cost, but especially environmentally friendly when using renewable resources such as molasses, glucose and other raw materials. However, as a flammable and explosive substance, ethanol requires special attention to safety protection in its production process to avoid fire or explosion caused by improper operation. This paper will discuss the fermentation process of ethanol and how to prevent flammable and explosive problems in the production process.

The fermentation process of ethanol

Ethanol (chemical formula: C₂H₅OH) is the product of converting sugar-containing substances into ethanol and carbon dioxide through biological fermentation. This process usually uses yeast (Saccharomyces cerevisiae) as the fermentation strain, which converts sugars into ethanol in the absence of oxygen. In industrial production, commonly used fermentation raw materials are glucose, corn, beet molasses and so on.

1. Selection of saccharification and fermentation raw materials

In the process of ethanol fermentation, it is first necessary to convert the sugar-containing raw materials into fermentable sugars through the saccharification reaction. Molasses, corn, beets, etc., are common raw materials. Molasses contains a large amount of sucrose, which is converted into glucose and fructose through the saccharification process, and these sugars become the basis of yeast fermentation.

2. Fermentation process

The core of fermentation is the addition of yeast in a sealed environment to convert sugars from raw materials into ethanol and carbon dioxide. The fermentation process is usually divided into the following steps:

Pretreatment: Clean and heat raw materials such as molasses and corn to remove impurities.

Saccharification: The conversion of complex sugars into simple sugars (e.g. glucose, fructose) by heating and the addition of enzymes.

Fermentation: The sugar solution is added to the yeast and fermented at a controlled temperature (usually around 30°C) and in an oxygen-free environment. Yeast breaks down sugar into ethanol and carbon dioxide.

In the fermentation process, the control of temperature and pH value is crucial. Too high a temperature will inhibit the activity of the yeast, too low will lead to reduced fermentation efficiency. In addition, the fermentation process releases a lot of carbon dioxide, so good ventilation is required.

3. Post-treatment and distillation

After fermentation is completed, the resulting fermentation liquid contains about 8%-15% ethanol, and most of the remaining water and other impurities. In order to extract higher purity ethanol, it is usually necessary to undergo a distillation process. In distillation, ethanol vapor is condensed into a liquid, a process that is repeated repeatedly to increase the concentration of ethanol.

Flammable and explosive properties of ethanol

Ethanol is a highly flammable liquid with a low flash point (about 13°C) and its vapors tend to form explosive mixtures when mixed with oxygen in air. Therefore, great care must be taken in the production, storage, transportation and use of ethanol, and necessary protective measures must be taken.

1. Flash point and explosion limit of ethanol

The flash point of ethanol refers to the lowest temperature at which flammable vapors from the liquid can be mixed with air to cause a spark or flame. Ethanol has a low flash point, which means that even at lower temperatures, ethanol may release flammable vapors that will burn when it encounters a fire source.

In addition, the explosion limit of ethanol means that the mixture of steam and air can explode when it meets the fire source within a certain concentration range. The explosive limit of ethanol is 3.3% to 19%. If the concentration of ethanol vapor is in this range, and it encounters an ignition source or a high-temperature object, it may cause an explosion.

2. Flammability risk

During the production of ethanol, especially during fermentation and distillation, ethanol vapors are often released into the air, which, if not discharged in time, may mix with oxygen in the air to form flammable gases. At this time, once there is an open flame or high temperature object, it may cause a fire or explosion.

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How to prevent inflammable and explosive problems

In order to ensure the safety of ethanol production process, a series of preventive measures must be taken to prevent the occurrence of flammable and explosive accidents. Here are some key precautions to take:

1. Explosion-proof design and equipment selection

Ethanol production facilities should be designed to ensure that all equipment that may come into contact with ethanol vapor is explosion-proof in design. Specific measures include:

•  explosion-proof electrical equipment: All electrical equipment (such as motors, switches, lighting fixtures, etc.) must be explosion-proof to avoid fire caused by sparks.
•  explosion-proof fans and ventilation system: ensure that explosion-proof fans are installed in the production area to discharge ethanol steam in time to prevent steam accumulation and avoid explosion danger.
•  Closed distillation system: Steam in the distillation process should be discharged through closed pipes to avoid mixing steam with air to form explosive gases.

2. Temperature control and fire source management

Ethanol evaporates at a low temperature, and controlling the temperature in the production process is essential to prevent fires:

•  Temperature monitoring systems: Distillation and fermentation equipment must be equipped with a high precision temperature control system to ensure that the temperature does not exceed the boiling point of ethanol (78.37°C), so that the temperature can not cause steam leakage or start a fire.
•  Avoid fire sources: In the ethanol production process, open flames must be strictly prohibited, and equipment and work areas must be kept away from fire sources. At the same time, the work area should not smoke, and set up obvious warning signs.

3. Ethanol concentration monitoring and control

•  Ethanol vapor concentration monitoring: During the production process, the ethanol vapor concentration in the air should be monitored in real time and measures should be taken to reduce the vapor concentration. When the concentration of ethanol vapor is too high, ventilation should be increased, or temporary steam recovery treatment should be adopted.
•  Explosion limit control: through reasonable design and operation, ensure that the ethanol concentration in the production environment will not reach the explosion limit. With proper ventilation and safety equipment, the ethanol vapor is diluted to reduce the risk of explosion.

4. Emergency response and fire fighting facilities

•  Fire extinguishing equipment: ethanol fire can not be put out with water, should be equipped with appropriate fire extinguishers, such as dry powder fire extinguisher, carbon dioxide fire extinguisher, etc. Adequate fire-fighting facilities should be set up in the production area and their effectiveness should be checked regularly.
•  Emergency plan: Develop a detailed emergency plan, employees should receive fire safety training, and regularly carry out fire drills. Rapid evacuation and fire extinguishing measures should be taken in case of emergency.

5. Regular inspection and maintenance

Ethanol production facilities need to be inspected and maintained regularly, especially for the tightness of equipment and the working condition of safety valves. Check pipes, valves, and distillation towers for leaks to avoid safety risks caused by aging or damage to equipment.

Conclusion

Ethanol fermentation is an efficient production process, but because of the flammable and explosive characteristics of ethanol, safety management must be strengthened in the production process. Through reasonable equipment selection, explosion-proof design, temperature control, ethanol concentration monitoring and emergency plan formulation, inflammable and explosive problems in ethanol production can be effectively prevented. Only comprehensive safety measures can ensure the smooth operation of the ethanol production process and minimize the risk of accidents.

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