Question

Draw the flow chart of the extra neutral ethyl alcohol to be produced for use in the production of acetic acid, detailing the pretreatments to be applied on the raw material you choose. Process the feed, product, by-product and waste lines entering and leaving the boxes and the elements they contain. Show the processes where by-products and wastes are processed on the flow chart. In the box-laying, enter the process name and the list of equipment to be used for this purpose in the boxes.

Answer 1

Extra Neutral Alcohol(ENA) is produced from molasses, the bye product in the sugar,glucose industry through two basic operations such as fermentation and distillation.

Fermentation Process

• Initially 3 to 4 tons of molasses is taken in pre-fermentor of capacity 50KL through diluter to setup a gravity 1.050.
• Then 10kg ofyeast,10kg of urea and 100 grams of enzyme is added into it.In this process yeast propagation is allowed for 8hrs and yeast cell count reaches to about 350 to 400x106 cells/ml
• .Fermentation is carried out batchwise in each fermentor.25% of the diluted mix of molasses and yeast is transfered from prefermentor to the main fermentor.
• Then chemicals like urea(25kg),enzyme (900grams),sulphiric acid(20kg) and sodium meta sulphate(10kg) is added into it.
• The molasses and water is pumbed into the fermentor such its specific gravity become 1.090.When the specific gravity falls,the predetermined quantity of molasses with water will be pumbed and preparation of wash completed.
• Once the specific gravity reaches 1.040 to 1.045 fermentation gets completed.
• During fermentation initially the sucrose get converted to glucose and fructose by the actyion of the enzyme invertase.
• Then glucose and fructose get converted into ethyl alcohol.
• The fermentation process takes about 24hrs.
• The fermented wash containing 9 to 10 % of alcohol is then taken from fermentor and passed through sludge settling tank.
• Sludghe is collected from the cone portion of the tank and is pumped to decanter to seperate thick sludge and clear wash.
• Thick sludge is collected ,dried and composted with press mud and used as manure.

Distillation Process

Detailed explanation of the flow chart is given below.

• The fermented wash containing alcohol is preheated in the beer heater using rectifier weapons and in the PHE using spent wash.
• The preheated is the passed through degassifying column to remove residual volatiles in it.
• The wash is then passed through analyzer column and alcohol is seperated from the mother liquor washby distillation process.
• Part of the liquid from degassifying column is transfered to aldehyde column.
• Vapours apart from the ethyl alcohol,also containing higher alcohol,esters,aldehydes and ketones in the wash are seoeratedthrough hydro extractive column,aldehyde column and diffusel column through distillation.
• Finally alcohol having 96% concentration is collected in the rectifier 2 column and extra neutral alcohol(ENA) is drawn and transfered to refining column.
• In refining column the traces of sulphur compounds are removedand final alcohol is cooled ain a condenser and stored as Extra Neautral Alcohol(ENA).

The temperature and pressure at different stages are given in the flow chart given above.