Regarding alcohol distillation

The pressure of the heating steam is too high, and that’s not useful at all; it doesn’t help with energy savings, and the temperature can’t be increased much either. Generally, it’s sufficient if there is a sufficient temperature difference for heat transfer.

Take a look at the design principles of distillation columns in chemical engineering!

Well, the diameter of the tower is relatively easy to determine; it can be calculated based on certain data related to the materials. However, the height of the tower must be determined taking into account factors such as the distillate components, the residue, the reflux ratio, and the properties of the materials. It’s a complex matter that cannot be explained in just one or two sentences; you’d better consult a book on principles of chemical engineering. The steam pressure you’re referring to seems to involve using high-pressure steam as a heating source; the pressure of the steam determines its temperature (there’s a table available for download online), and it also indicates the amount of heat carried by that steam. The data used is based on the heat required for distillation, and by performing a heat balance calculation to determine how much heat is needed, and then adding in the heat losses, you can figure out the steam pressure.

1# At the Yunhai First Line, the number of columns is determined based on the quality of the alcohol; the more columns there are, the better the quality of the alcohol. It depends on the specific standards you want to achieve. According to the GB10343-2002 standard for alcohol, there are three grades: top grade, premium grade, and ordinary grade. The number of columns is determined according to the required standards for alcohol quality, and vacuum distillation is more energy-efficient than distillation under normal pressure； The diameter of the tower is determined by the amount of alcohol produced; higher production requires a larger tower diameter, and vice versa. The height of the tower is determined by the desired alcohol concentration, the reflux ratio, as well as considerations related to energy efficiency. To remove water from the mature mash or weak liquor and achieve a certain ethanol concentration, a certain number of tray levels are necessary. Under these conditions, a shorter tower with a higher reflux ratio results in lower energy consumption but higher investment costs, while a taller tower with a lower reflux ratio requires more energy but has lower investment costs ； The column pressure is determined based on the column diameter, column height, and the amount of steam required for distillation. I hope that’s clear? If you don’t understand, feel free to ask again.

5# wwwccchhh May I ask, what books are good for reference when designing alcohol plants, especially when it comes to heat balance and material balance calculations?

Firstly, from a technical perspective: the energy obtained from differential pressure distillation in two towers can only be utilized once, while in three towers it can be used up to twice; multiple towers enable multi-stage utilization of heat, thus saving energy! Generally, steam pressure is sufficient for heat exchange with the towers, but if a siphon reboiler is used, a slightly higher steam pressure is required. Secondly, the more towers there are, the better the effect on removing impurities will be! When producing fuel alcohol, and if only the alcohol content is important, two-tower distillation is sufficient. In the design of ordinary alcohol fuel production plants, it is possible to switch between operation with two towers and operation with multiple towers. The tower diameter is related to the feed rate; generally, the maximum processing capacity per tray is similar. The larger the tower diameter, the greater the processing capacity, and correspondingly, the greater the heat source required. The height of the tower determines the alcohol content at each layer of trays; impurities can be concentrated on the corresponding trays only when the alcohol content reaches a certain level

Multi-column distillation is primarily used to improve the quality of alcohol; alcohol produced through three-column distillation meets standard quality levels, while that from four- or five-column distillation achieves premium quality standards, and alcohol obtained through six-column distillation reaches top-tier quality standards! Two-column distillation under atmospheric pressure can also achieve the ordinary grade, but it requires more trays; the rectifying column usually has 82 or more layers! Four-column distillation under atmospheric pressure can also meet the premium standards! Tower diameter is related to production volume, while tower height is related to the separation of impurities! You can take a look at the design specifications for alcohol plants! The 1996 version! The advantage of high steam pressure and temperature in distillation is energy savings! But it is unfavorable for saccharification cooking! If a common steam main is used, the steaming process can easily lead to carbonization!

Does anyone know where I can download \"Fundamentals of Alcohol Plant Design\"? Written by E.N. Bartenev; published by the Light Industry Publishing House. Or where can it be purchased?

In the two-tower process, whether vapor passes through the towers or liquid passes through them, only pharmaceutical alcohol can be obtained. It is very difficult to achieve the goal of obtaining distilled alcohol using the aforementioned process flow that consists only of concentration equipment. The three-tower process was developed to address these shortcomings. The three-column process consists of three columns: the first is the crude distillation column, and the second is the aldehyde removal column, also known as the fractionation column. This column is installed between the crude distillation column and the refined distillation column, and its function is to remove the primary impurities in the form of aldehydes and esters. Third is the distillation tower, which not only concentrates alcohol to increase its strength but also continues to remove impurities, thereby enabling the production of distilled alcohol. The three-tower process can be further divided into three categories based on the different ways in which the crude alcohol distilled from the crude distillation tower enters the aldehyde removal tower, and how the aldehyde-free alcohol from the aldehyde removal tower enters the rectification tower: the direct type, in which both the crude alcohol entering the aldehyde removal tower and the aldehyde-free alcohol entering the rectification tower are in gaseous state. In the semi-direct method, the crude alcohol enters the aldehyde removal tower as a gas, while the aldehyde-free alcohol enters the distillation tower in liquid form. In the indirect method, both the crude alcohol entering the aldehyde removal tower and the aldehyde-free alcohol entering the distillation tower are in liquid form. 1. Three-tower direct process: Since crude alcohol enters the aldehyde removal tower in vapor form and then enters the distillation tower as a gas, its efficiency in removing impurities is not high. It is also possible for trace amounts of mature mash present in the vapor from the crude distillation tower to be carried into the distillation tower, resulting in an unpleasant odor in the final product. Although this process is the most economical in terms of thermal energy, it has not been widely adopted due to the aforementioned drawbacks. 2. Semi-direct method: Although the heat energy consumption is higher than that of the direct method, it enables the production of products of relatively high quality; therefore, it is widely used in China’s alcohol industry. Its process is shown in Figure 1–44. 　 The matured mash is pumped from the mash tank, preheated in preheater 1, and then fed into the crude distillation tower 2. The alcohol vapor produced does not go directly into the distillation tower; instead, it first enters the aldehyde removal tower 3. The distillation coefficient for fatty aldehydes and other primary impurities is higher at lower ethanol concentrations; therefore, the concentration of the crude alcohol entering tower 3 should be between 35–40% (by volume). If the alcohol concentration is too high, some plants need to add water to dilute it. Aldehyde removal towers typically use a large number of tray levels (28–34) and condensers with a large condensing area, as well as a high reflux ratio, to increase the alcohol concentration at the top of the tower. Feeding is carried out at around layer 13 (counting from the bottom), with the top temperature of the tower controlled at 79°C. The alcohol content in the lipal alcohol is 95.8–96% (by volume), and the extraction rate of lipal alcohol is 1.2–3% of the final product. The dealdehyde liquor that enters the distillation tower from the bottom of the aldehyde removal tower has a concentration slightly lower than that of the crude alcohol derived from the crude distillation tower, due to the use of direct steam heating and the relatively high alcohol content in this liquor; it is generally between 30–35% (by volume). After entering distillation column 4, the residual aldehyde-type impurities rise along with the ethanol vapor; through condensers 7, 8, and 9, part of them is discharged into the atmosphere via the aldehyde exhaust pipe, while the rest enters industrial alcohol after passing through a cooler and an alcohol detector. In molasses distilleries, due to the large amount of ester-aldehyde distillates (which mainly contain acetaldehyde), these are sent back to the fermentation tank for further fermentation in order to increase the alcohol yield. The alcohol vapor distilled from the top of the distillation tower is condensed in condensers 7 and 8 and then returned entirely to the tower. The finished alcohol is obtained from the liquid phase on the trays at levels 2, 4, and 6 below the return pipe at the top of the tower. The extraction method for fusel oils is the same as that in the two-column process. 3. Indirect three-column process: Its product quality is higher than that of the semi-indirect process, and it can also produce high-purity alcohol. This is because the alcohol vapor distilled from the crude distillation tower is condensed into a liquid, providing an additional opportunity to remove impurities from the initial stage. Obviously, the production costs are higher. Distilled alcohol can be obtained using a semi-direct three-column process with either starch or molasses as the raw material; therefore, the indirect three-column process is not widely used at present.

What is the difference in waste liquid generation between atmospheric pressure and differential pressure production of (molasses alcohol)? (Found online) Distillation under atmospheric pressure results in the generation of 13–15 tons of waste liquid per ton of alcohol produced (an average of 14 tons), with a concentration of 8–12°BX. Using differential pressure distillation (or an atmospheric pressure distillation column with a reboiler), 11–13 tons of waste liquid are produced per ton of alcohol, with a Brix value of 15.50–16.80°BX; this represents a 21% reduction in the amount of waste liquid compared to atmospheric pressure distillation.