MURTAGH & ASSOCIATES

ALCOHOL PRODUCTIONS CONSULTANTS

3409 BRIARCREST DRIVE

EAU CLAIRE, WI 54701, U.S.A.

TELEPHONE (715) 831-8151

FAX (715) 831-8151



Description of Operating Process

Tavda Hydrolysis Plant

November 1997.

 

 

 

1. History and background.

 

The Tavda Hydrolysis Plant is located in the town of Tavda, on the western side of the Siberian Lowlands, in Sverdlovsk Oblast, about 300 km northeast of the oblast capital Yekaterinburg, and about 1700 km east of Moscow.

 

The Tavda Hydrolysis Plant was established in 1943, with an initial production capacity of 5 million litres of ethanol per year. In 1955, the production capacity was increased to 8 million litres per year. In 1970, the plant was reconstructed, to give a design production capacity of 13.5 million litres per year.

 

Currently, the plant produces approximately 36,000 litres of ethanol per day, and operates 345 days per year, for an overall output of approximately 12.4 million litres per year. About 70% of the ethanol production is derived from wood-cellulose hydrolysate, together with 20% derived from wheat-starch hydrolysate and 10% from beet molasses. (All three feedstocks are combined in a single fermentation process.)

 

 

2. Feedstock processing. (See attached flowdiagram.)

 

2.1 Wood.

 

The plant uses about 450m (180 tonnes) of wood per day, usually made up of a mix of about 70% coniferous wood, and about 30% non-coniferous (mainly birch) wood.

 

Wood is brought in as logs, by rail, from up to 300 km away, for chipping on site. Woodchips and sawdust are also brought in by truck from mills up to 100 km away. In the past, the plant also received woodchips and sawdust by conveyor belt from a neighboring lumber mill, but it has now ceased operating.

 

A mixture of about 80% woodchips and 20% sawdust are processed in a "downward-percolation dilute-acid hydrolysis process", (somewhat similar to the German "Scholler Process," the U.S. "Madison Process" and the "New Zealand Forest Research Institute Process".)

 

The plant has 18 hydrolysis reactors which operate batchwise, in parallel. Only 7 are actually in use at any time.

 

The reactors each have a total capacity of 40m, and a working capacity of about 37m. The reactors are made of carbon steel, with an interior layer of cement and a lining of acid-resistant tiles, and are mounted on weighing scales.

 

The hydrolysis process is commenced by filling a reactor with 4.5 to 5 tonnes of woodchips and sawdust. (The wood weights are calculated on an absolutely-dry basis). This represents 11 - 12 m of wood in its original solid state. The wood loading, (from a conveyor belt passing over the tops of the reactors), takes 25 minutes.

 

About 11.5m of water containing about 55 litres of concentrated sulphuric acid are added into the reactor over a period of 20 minutes. This gives an acid concentration of 0.75 w/v.

 

The reactor is then sealed, and heated with high-pressure steam at 250C, over a period of 40 minutes. During this time there are two purges of about 5 minutes each, to vent air and other gases to the atmosphere via a vent chamber. First, when the reactor pressure reaches 3 atmospheres, it is vented back to 1 atmosphere, and then the vent is reclosed, and steaming recommenced. Next, when the pressure reaches 5 atmospheres, the vent is reopened, to drop the pressure down to 2 atmospheres. Then, the vent is reclosed, and the steaming is recommenced, to take the pressure up to 6 atmospheres.

 

At this point, the vertical percolation is commenced. Over the next 20 minutes, as the pressure is raised to 7 atmospheres, 13m of water containing 40 litres of concentrated sulphuric acid (0.5% of acid) are added to the top of the reactor while a corresponding amount of liquid is withdrawn from the bottom of the reactor.

 

Then, while the pressure is raised to 9 atmospheres, over another 20-minute period, 12m of water containing 35 litres of concentrated sulphuric acid (0.46% of acid) are added to the top of the reactor, and a corresponding amount of liquid is withdrawn from the bottom.

 

In the next 20-minute period, in which the pressure is raised to 12 atmospheres, 10m of water containing 30 litres of concentrated sulphuric acid (0.48% of acid) are added to the top and the same volume of liquid is withdrawn from the bottom of the reactor.

 

This acid-addition and liquid-withdrawal process is repeated with the same volumes over the next 20-minute period, while the pressure is raised to 12.5 atmospheres.

 

Then, with the pressure held at 12.5 atmospheres, 10m of water containing 20 litres of concentrated acid (0.32%) are added over the ensuing 20-minute period.

 

After a total of 100 minutes, the percolating is discontinued, and the reactor is rinsed with 5m of water, over a 10-minute period, while holding the pressure at 12.5 atmospheres. The water and steam are then shut off, and the liquid is drained over a period of 30 minutes, reducing the load in the reactor from 24 tonnes to 9 tonnes, and reducing the pressure to 7 atmospheres.

 

Then, a quick-acting valve on the base of the reactor is opened, to cause the remaining solids to be blown into a cyclone tank over a period of 5 minutes, while the liquid flashes as vapor, to the atmosphere. The solids dry down to about 8 tonnes, which is about 65% lignin at 60 - 80% moisture. It is discharged into three trucks, to be taken to a specially prepared dumpsite about 10 km away.

 

The reactor operating conditions may be varied, depending on the mix of coniferous and non-coniferous wood. For example, if there is more than 30% non-coniferous wood, the maximum pressure in the reactor may be 12 atmospheres or less.

 

Previously the lignin residue was dried to about 40% moisture, and burnt in a boiler. This involved sending the residue through a pipeline of about 700 - 800 metres in length. In the 1980's it was concluded that this procedure of drying and burning was uneconomical, so the dumping was commenced. At that time, there were no "ecological penalties" or charges for such dumping. Now, however, there is a charge paid to the oblast (county), equivalent to $24 per dry tonne of residue. With an annual output of approximately 60,000 dry tonnes of residue and a total annual charge of about $1.4 million, the disposal economics are being reassessed. (It is reported that it would cost about $500,000 to refurbish and reinstate the original, vertical, oil-fired, hot-air dryer system, which was susceptible to catching fire. So other uses of lignin are being sought. For any commercial purposes, the lignin would probably have to be dried to 5 - 10% moisture.)

 

A problem of accumulation of tarry caramel deposits occurs in the bottom of the reactor and in the piping from it. This necessitates special cleaning every 300 usage cycles. The tarry caramel scale is removed from the bottom of the reactor by scraping by hand, while the copper pipes have to be dismantled and cleaned by hand and with a water hose at 5 atmospheres pressure.

 

The acidic liquid drawn off from the reactor is piped to two flash-tanks which operate in series, to serve as evaporators. The liquid contains pentoses from the hydrolysis of the wood hemicellulose, some furfural and dissolved, partially-hydrolysed cellulose. (When grain is being processed, the grain-starch hydrolysate also joins the liquid flow to the flash tanks, as described in section 2.2.)

 

The two flashtank-evaporators are each 16m in capacity and operate in series. With the drop in pressure from the reactor into the flashtanks, about 10% of the liquid volume flashes off as steam, together with most of the furfural. (No attempt is made to recover the furfural, as the concentration is low, and the recovery costs are reported to be very high. Some other hydrolysis plants do, however, recover furfural for various uses, including the production of rocket fuel). The degree of removal of furfural in the flash tanks is of importance, as it can inhibit the subsequent fermentation.

 

The concentrated liquid from the second flash tank is pumped to a 1000m inverter tank, where it is held for 4.5 hours at 105C, to complete the hydrolysis of the cellulose to glucose and other hexoses, including galactose, raffinose, and mannose. The hydrolysate emerges from the inverter at about pH 1.6, and is sent to the neutralization tanks.

 

There are 7 neutralization tanks, 5 having capacities of 34m and two having capacities of 100m All are fitted with vertically mounted agitators. (Normally, two of the 34m tanks are kept on standby.) The tanks are operated in various combinations to suit the rate of hydrolysate flow, which is normally about 130m per hour. The hydrolysate enters the first neutralization tank, where it is mixed with milk of lime (a suspension of calcium hydroxide in water), to raise the pH to 3.2. It is then transferred to a holding tank, where it is agitated, before going to a second neutralization tank. There, it is mixed with ammonium hydroxide, to raise the pH to 3.8 - 4.0. Ammonium phosphate and a mixture of ammonium and potassium salts are added, to provide nutrients for the subsequent fermentation. The liquid is then transferred to one of five shallow precipitator tanks which are of 285m capacity, and have a liquid surface area of 113m. (They resemble sewage-plant clarifier tanks, having a very slow moving sludge agitator, and an overflow channel around the top circumference).

 

The solids from the bottom of the precipitator are composed to about 70% calcium sulphate, with the remainder being mostly tars, lignin and some sand. They are drawn off at a concentration of 400 - 600 grams per litre, to go to a 20m precipitate-holding tank, from which they are fed to a vacuum belt filter. The liquid drawn off from the filter, which represents about 30% of the original volume, is recycled to the precipitator, while the solids are loaded onto trucks, to be sent to the lignin-waste dumpsite.

 

The supernatant liquid which is drawn off from the top of the precipitator at 80 - 100C, goes into a 40m holding tank, from where it is pumped through a 4-stage vacuum cooler, to be cooled down to 32 - 34C. (Much of the furfural remaining in the hydrolysate is drawn off into the water jet used to pull the vacuum). The cooled hydrolysate, now referred to as "wort", then goes into a holding tank of 160m capacity. A small amount of mostly organic sludge is discarded from the cone-bottom of the holding tank, while the main flow of wort goes to a 30m "yeast-activator" tank. Here, the wort is mixed with centrifuged yeast recycled from the continuous fermentation system. The wort is dosed with ammonium phosphate. A stream of 3.5m per hour of diluted molasses may also be added to the activator tank (as described in section 2.3), to give a mixture of about 2.7 - 3.0% fermentable sugars. There is provision for aeration of the activator, but it has not been considered necessary to use it in recent years.

 

2.2 Grain.

Local wheat, containing 48 - 52% starch, is processed by acid hydrolysis, in batches, in either of two of the 18 reaction vessels, which are otherwise used for cellulose hydrolysis.

 

The wheat is dumped from the delivery trucks onto the floor of the storage building. There, it is sampled and then checked in the laboratory for moisture content, trash and starch content. (These parameters are taken into account in calculating the wheat purchase price.)

 

The wheat is lifted by clamshell bucket to feed directly into a hammermill. The feedrate is regulated by adjusting the degree of opening of the clamshell, and the grain drops through a chicken-wire screen with holes of about 2 cm in diameter, to remove any large pieces of trash. The hammermill is also fitted with a magnet, to remove any tramp iron.

 

The hammermill has a grinding capacity of 4 tonnes of wheat per hour, using a 6mm-diameter round-hole screen. The meal is then blown up to a cyclone to feed into a mash-mix tank. The meal has a wide range of particle sizes, together with some whole grains and some large pieces of chaff. The only other screen available for the hammermill has 3mm holes, and produces a meal which is too finely ground. No sieve analysis is performed on the meal.

 

There is a roller mill which serves as a standby for milling. It is mounted on top of a mash-mix tank, to feed meal directly into the tank.

 

The mashing water comes from the cellulose-hydrolysis building. It is heated to about 90C and pumped backwards through the mash line to the mash-mix tank in the grain-mashing building, to flush out any mash solids left in the line. (In summer, the water is replaced with waste liquid from fodder-yeast production. It is heated to 80C before pumping to the grain-mashing building.)

 

Three tonnes of wheat meal are added to one of two 20m mash-mix tanks containing 15m of water at about 80C. The addition of the meal lowers the temperature to about 75C, and the mixture, which is agitated mechanically by a top-mounted, vertical agitator, is held at that temperature for about one hour, to gelatinize the starch.

 

The mixture is then pumped into acid-hydrolysis reactor 9 or 10, to which 95 litres of concentrated sulphuric acid are added, to give an acid concentration of 0.8%. (The mash transfer takes 10 - 15 minutes.) The reactor is then sealed, and heated by the injection of high-pressure steam, to a pressure of 4 atmospheres. The vent is then opened, to purge air, and to mix the contents, (as the reactor has no agitation). When the pressure has dropped to about 1.5 atmospheres, the vent valve is closed again, and steaming is recommenced, to take the pressure up to 7.5 atmospheres.

 

At this point, after about 60 - 70 minutes in the reactor, the steaming is stopped, and the hydrolyzed grain mash is discharged into the pipe which conveys cellulose hydrolysate from the other reactors to the flashtank evaporators.

 

Usually 4 grain batches are cooked in an 8-hour shift. The starch hydrolysate contains about 8 - 10% of sugars.

 

The alcohol production from wheat reportedly averages about 250 litres per tonne.

 

2.3 Molasses.

 

Beet molasses is obtained from sugar mills in the vicinity of Kazan, in Tartarstan, about 900 km to the west of Tavda. The molasses has a total dry matter of 73% - 80%, and contains 43 - 51% sugars. (The term Brix is not used in the plant to refer to molasses concentrations.)

 

The molasses is diluted with water to 15% total dry matter, and acidified with sulphuric acid to a pH range of 4 - 5. Then 3 - 5m of the diluted molasses are pumped into the yeast activator, to mix with each 120m of hydrolysate coming from the cellulose and grain processing units.

 

 

3. Fermentation.

 

The mixture of cellulose hydrolysate, wheat-starch hydrolysate and diluted molasses, which is referred to as "wort", is pumped together with recycled yeast, at a rate of about 120m per hour, from the activator tank, into the first of a pair of continuous fermentation vessels which are operated in series. There are 5 primary fermenters, each of 170m capacity, and one secondary fermenter of 110m capacity. None of the vessels has any agitation or aeration. The number of primary vessels in use at any time is adjusted to match the feed flow rate, to give a total fermentation time in the primary and secondary vessel of 6 - 8 hours.

 

The wort is fed in at the top of the primary fermenter, and continuously pumped from the bottom, into the top of the secondary fermenter. The temperature in the fermenters is controlled at a maximum of 34 - 35C, by adjusting the temperature of the feed from the 4-stage vacuum cooler. The fermenters do not have any other means of temperature control.

 

The yeast used in the fermentation is a strain of the fission yeast Schizosaccharomyces, which is propagated from slants in the laboratory, and through a series of propagation vessels in the plant.

 

Carbon dioxide is drawn off from the fermenters, and is piped to a processing unit for scrubbing and compression to a liquid product.

 

Fermented wort, known as beer (or brew) (or "brazhka"), is drawn off continuously from the bottom of the single secondary fermenter, and is pumped to a battery of 10 Russian Laval vertical centrifuges, which separate the beer from the yeast, which is sent back to the activator tank. (Normally, only 5 or 6 centrifuges are in use at any time.)

 

The centrifuged beer contains about 1.3% alcohol, if it is derived solely from cellulose hydrolysate, or about 1.6% alcohol, if grain and molasses have also been used. The beer is pumped to a holding tank of 70m capacity, from where it is pumped to the distillation unit.

 

 

4. Distillation.

 

The objective of the distillation is to produce a fairly high quality alcohol for industrial uses.

 

4.1 Equipment.

 

The distillation equipment, (as shown in the attached flowdiagram) consists of:-

 

(a) Four beer-stripping columns. All are 2 metres in diameter, with 2cm-thick cast-iron shells and 19 titanium-alloy trays. Three of the columns have perforated trays, similar to a Nutter design), while the fourth has bubble-cap trays. Only 2 of the columns are in operation at any time. Each column has its own beer-preheater/condenser, and all share a common, vertical, second condenser of 15m and a final horizontal vent condenser of 7m.

 

(b) An "epuration" (aldehyde) column, of 2.2 metres in diameter, fabricated entirely of stainless steel, with 40 bubble-cap trays. It has a 150m primary condenser, and a 7m vent condenser. It is heated via a 38m external reboiler.

 

(c) A "spirits" (rectification) column of 2.2 metres in diameter, fabricated entirely of stainless steel, with 72 bubble-cap trays. It has a 150m primary condenser, and a 57m vent condenser.

 

(d) A "methanol" (demethylizing) column of 2.14 metres in diameter, fabricated entirely of copper, with 70 bubble-cap trays. It has four horizontal condensers and two vertical condensers, arranged in series. It is fitted with an external 38m reboiler, for indirect heating.

 

(e) A heads-and-esters concentration column (no longer in use.) It is 60 centimetres in diameter, has 30 bubble-cap trays, and is fabricated entirely of stainless steel.

 

(f) An old methanol column (dating from the 1950's), which is being refurbished and reinstalled, to replace the existing methanol column. It is approximately 2.5 metres in diameter, and has a total of 72 trays. The lower 44 trays and their shell are fabricated of stainless steel, while the upper 28 trays and their shell are fabricated of copper. Note: The objective in replacing the existing methanol column is to be able to increase the distillation and rectification capacity from the present level of 36,000 - 40,000 litres per day, to 60,000 litres per day. (The existing methanol column was originally designed to operate at 30,000 litres per day, and is reported to be the main bottleneck in the system at present.)

 

4.2 Mode of Operation.

4.2.1 Beer distillation.

 

There are 4 beer-distillation columns, but normally only 2 are in operation (in parallel), at any time. They all share in common their second and third condensers, so their outputs are mingled together. Each of the 3 beer columns which have perforated trays, has a feed capacity of 90m per hour, while the column with bubble caps has a feed capacity of 50m per hour. The combined feed rate to the two columns in operation varies, but averages about 120m per hour.

 

Beer containing about 1.6% alcohol is first preheated by the overhead vapors in the dephlegmator-preheater, and is then introduced into the 19-tray column on tray 18. Live steam is introduced at the base of the column, and distills the alcohol out of the descending stream of beer. The alcohol vapors rise up into the overhead dephlegmator and condensers. All of the condensate from the dephlegmator is refluxed to the top of the column, while all of the condensate from the other two condensers, at 10 - 15% alcohol, goes down into a 75cm-diameter horizontal collector pipe. From there it is raised by a steam-lift system, to feed the epuration column.

 

The beer distillation columns can operate for up to 3 months between cleanings, when operating solely on cellulose feedstock, but the cleaning has to be more frequent when molasses is used.

 

4.2.2. Rectification.

 

The 10 - 15% alcohol feed enters the 40-tray epuration (aldehyde) column on tray 30. The column is heated indirectly through a reboiler at the base. (No dilution water is added to the column.) The ethanol portion of the feed tends to go down the column, while the more volatile aldehydes and esters rise into the overhead condensers. A heads purge, amounting to about 0.5% of the alcohol feed volume, is drawn off from the condenser reflux loop, to be sold as low-grade industrial alcohol.

 

The alcohol descending to the bottom of the epuration column is pumped to the 72-tray spirits (rectification) column, entering on tray 15. The column is heated by live steam at the base. There are fusel-draw valves on each tray, from No. 10 to No. 19. A fusel draw is taken from several of the valves, to give an average alcohol concentration of about 35 - 40C. It goes to a decanter, and the decanted oil is sent to the drain, while the alcohol-water portion, at 12 - 16% alcohol, is returned to the beer tank. The temperature is monitored at tray 22, and near the top of the column. A 4% solution of caustic soda is introduced into the column at tray 26, at a rate which is varied with the acidity of the product. The alcohol product is drawn off from tray 68, while an aldehyde heads purge is taken from the reflux loop at a rate of about 0.5% of the feed, to be sold as low-grade industrial alcohol ("methanol, esters and aldehydes fraction").

 

The alcohol flow from the spirits column at <96.2% is fed to the 70-tray methanol column, entering on tray 40. The methanol column is heated indirectly, via a reboiler on the base. The methanol portion of the feed tends to fractionate upwards, to be drawn off at a rate of 0.5% of the feed volume. (It normally contains 70 - 90% methanol, and may be used for subsequent denaturation of products.) The final product is drawn off from the base of the methanol column and is passed through a cooler and a filter. If denatured alcohol is being produced, the product is diluted with steam condensate to 93.5 - 94%, before going through a metering system. If "extra" quality industrial is being produced, there is no dilution.

 

4.3 Product specifications.

 

The two types of final product are required to meet the following state specifications: -

 

A. "Extra" rectified industrial alcohol.

 

1. Appearance:Transparent, colorless liquid,

without extraneous matter.

2. Odor:Odor characteristic of rectified ethanol,

without extraneous odors.

3. Ethanol content by volume: Greater than 96.2%.

4. Purity test. (Absence of color change

on heating with sulphuric acid.) Passes the test.

5. Permanganate time: >15 minutes.

6. Aldehyde content in mg per litre

of absolute alcohol. <4 (ppm)

7. Fusel content in mg per litre: <4 (ppm)

8. Acid content (as acetic acid) in mg per litre: <10 (ppm)

9. Ester content in mg per litre: <25 (ppm)

10. Methanol content in volume percent: <0.03% (300 ppm)

11. Furfural test: Not detected.

12. Solid residue on evaporation, in mg per litre: <1 (ppm)

13. Alkali content by weight, as sodium hydroxide: Not detected.

14. Electrical resistance, in ohm.cm: >1.3x106

B. Denatured industrial alcohol. ("Multi-component industrial liquid mixture")

1. Appearance: Transparent, colorless liquid,

without extraneous matter.

2. Density at 20C, in grams per cm: 0.829-0.816

3. Refractive index: 1.3630-1.3655

4. Permanganate time: > 15 minutes

5. Aldehyde content in mg per litre: <4 (ppm)

6. Content of propyl, butyl and amyl alcohols,

in mg per litre: <4 (ppm)

7. Acid content (as acetic acid), in mg per litre: <10 (ppm)

8. Ester content in mg per litre: <25 (ppm)

9. Methanol content as volume percent: <0.2% (2000 ppm)

10. Furfural test: Not detected.

11. Solid residue on evaporation, in mg per litre: <4 (ppm)

12. Arsenic content: in mg per litre: <0.2 (ppm)

13. Copper content: in mg per litre: <5 (ppm)

14. Mercury content: in mg per litre: <0 5 (ppm)

15. Lead content: in mg per litre: <0.03 (ppm)

16. Cadmium content: in mg per litre: <0.03 (ppm)

17. Zinc content: in mg per litre: <10 (ppm)

18. Benzene content: Not detected.

 

Note: The state regulations on denatured alcohol appear to be a little vague. The product should be denatured to a maximum level of 0.2% methanol. There is, however, no clearly stated minimum, but if the methanol concentration is less than 0.05%, the product will be subject to excise tax. In practice, it is assumed that the required minimum level of methanol is 0.1%, and the product is denatured to about 0.12% methanol, using the heads fraction from the methanol column.

 

4.4 Energy usage.

The beer columns are reported to use 140 kg of steam per 1000 litres of beer distilled. On the basis of an alcohol content of 1.6%, this represents 8.75 kg of steam per litre of alcohol distilled.

 

The epuration (aldehyde) column is reported to use 2.3 kg of steam per litre of alcohol.

 

The spirits (rectification) column is reported to use 1.8 kg of steam per litre of alcohol.

 

The methanol (demethylizing) column is reported to use 1.4 kg of steam per litre of alcohol.

Thus, the total steam usage for distillation and rectification amounts to 14.25 kg per litre of alcohol.

 

Converted to U.S. terms, for purposes of making a direct comparison with the steam usage in U.S. plants, this amounts to 118.75 lbs of steam per U.S. gallon of alcohol distilled to 192 proof. The beer distillation consumes 72.9 lbs. of steam per U.S. gallon of alcohol, while the three-column rectification system utilizes 45.85 lbs. of steam per U.S. gallon. (This does not include any reprocessing of heads fractions.)

 

Steam usage is reported to represent 35 - 40% of the overall production costs.

 

4.5 Product cost structure.

 

Tavda's overall production cost for cellulose-hydrolysis spirit is reported to be in the range of 6000 to 9000 roubles per litre (which, at an exchange rate of 6000 roubles per US$, is equivalent to US $3.78 to $5.67 per U.S. gallon.

 

The breakdown of production costs, on a percentage basis, for the month of October 1997 was:-

 

1. Raw materials 35.5%

2. Auxiliary materials (chemicals etc.) 6.0%

3. Fuel 35.1%

4. Labor 1.5%

5. Equipment maintenance 5.4%

6. Direct overheads 2.3%

7. "Other expenses" 3.6%

8. General overheads 10.4%

9. "Non-production costs" 0.2%

 

TOTAL 100%

 

 

4.6 Products, markets and prices.

 

About 10% of the alcohol output is sold as undenatured "extra rectified industrial alcohol" at a minimum concentration of 96.2% alcohol by volume, while the remaining 90% of output is sold as "denatured industrial alcohol" at 93.5 - 94.0% alcohol by volume.

 

The "extra" grade product sells at a price of 30,000 roubles per litre inclusive of excise and value-added taxes, from which the producer receives a net 12,000 roubles per litre (approximately US$2 ).

 

The denatured industrial alcohol sells at a price of 11,500 roubles per litre, and is exempt from excise taxes. It is only denatured with about 0.12% methanol, (which is less than usually naturally present in tequila, grappa and some other beverages) and does not contain any colorant, Bitrex or other, similar taste or odor modifier, so it is suitable for a wide range of uses.

 

Currently, beverage-grade neutral spirit sells for a net price of 3000 - 4000 roubles per litre, but its production and sale is limited by government quotas.

 

 

5. Stillage utilization.

 

The stillage from the beer distillation contains 0.85 to 1.1% of pentose sugars, mainly xylose and arabinose, from the hydrolysis of the hemicellulose in the wood.

 

The stillage is used as a feedstock for the production of a torula fodder yeast, using a strain of Candida scotti. The product is sold both in powder and pellet form, for use as a protein supplement in animal feeds.

 

 

6. Utilities, etc.

 

6.1 Steam and electricity.

 

There are 4 boilers, each capable of producing 75 tonnes of steam per hour, at a pressure of 40 atmospheres, fired by coal or fuel oil. Only two boilers are in operation at any time, and two are on standby. The high-pressure steam is passed through a 6.2-megawatt electricity cogeneration turbine, to give low-pressure steam for most process applications, at 5 atmospheres.

 

A major use of energy is the district-heating system. The plant supplies hot water for heating the homes of about 60% of the town's population of 40,800. This means that the steam demand is much greater in winter than in summer, with a consequent change in electricity cogeneration. Thus, the plant produces only 20% of its electricity requirements in summer, and about 90% in winter. The remainder of the electricity requirement comes from the public supply grid.

 

6.2 Water.

 

Process water is taken from the nearby Tavda River, and is filtered and treated. Cooling water is also taken from the Tavda River, but it is unfiltered, and is discharged back into the river after use. Thus, there is no need for cooling towers.

 

6.3 Lime Kilning.

The plant operates a lime kiln, to burn calcium carbonate limestone, by coke firing. (The resultant calcium oxide is used for neutralizing the cellulose hydrolyzate.) Currently, the lime throughput is 16 tonnes per day, but the unit has a maximum capacity of 35 tonnes per day.

 

6.4 Waste treatment.

 

Apart from the lignin and other solid wastes which are taken to a special dumpsite, the plant has a large liquid effluent treatment system, to handle a flow of about 800 m per hour, much of which comes from the fodder- yeast production unit.

 

The waste-treatment system has 18 precipitation tanks, each of 18 metres in diameter, a 25,000 m aerated tank, and two lagoons, each of 100 metres square.

 

The B.O.D. of the effluent entering the system is reported as 1,500 mg per litre, while at the discharge, it is about 500 mg per litre. The plant is required to bring the B.O.D. at the discharge down to about 60 - 100 mg per litre, and ozonation is currently being considered. It is recommended that the possibility of using floating aerators be investigated, as an alternative system for lowering the B.O.D.

 

The waste-treatment operating costs are currently about 1 billion roubles per month, excluding labor. This is equivalent to US$2 million per year.

 

 

7. Employment.

 

The plant currently employs a total of 1341 persons. The distribution is:-

 

A. Administration Departments

 

Department

Managerial

Non-

Managerial

Total

1.

Director General

1

-

1

2.

Chief Engineer

1

-

1

3.

Deputy Director General

1

-

1

4.

Deputy Director General, Economics

1

-

1

5.

Chief Technologist

1

-

1

6.

Legal Department

1

1

2

7.

Capital Construction

1

1

2

8.

Chief Mechanical Engineer's Department

1

3

4

9.

Chief Energy Engineer's Department

2

2

4

10.

Planning and Economics

1

3

4

11.

Safety Department

1

2

3

12.

Personnel Department

1

3

4

13.

Facilities and Community Department

2

3

5

14.

Supplies

2

4

6

15.

Marketing

2

4

6

16.

Production Department

1

3

4

17.

Environmental Protection

1

2

3

18.

Design Department

1

4

5

19.

Accounting

3

11

14

20.

Computerization

1

2

3

Total

26

48

74

 

 

B. Plant and General Services.

 

Department

Managerial

Non-

Managerial

Total

1.

Administration

12

4

16

2.

Laboratory

8

14

22

3.

Hydrolysis

10

129

139

4.

Yeast

8

71

79

5.

Carbon Dioxide

1

15

16

6.

Raw Materials

9

117

126

7.

Heating and Power

19

168

187

8.

Truck Transportation

10

133

143

9.

Rail Transportation

7

56

63

10.

Mechanical Maintenance

3

65

68

11.

Electrical Maintenance

2

33

35

12.

Control and Instrumentation

4

35

39

13.

Lime Kilning

1

17

18

14.

OI3 (?)

11

1

12

15.

Stores

-

13

13

16.

Salt, Minerals

1

27

28

17.

Purification Works

5

56

61

18.

Repairs and Construction

1

39

40

Total

102

1003

1105

 

 

 

 

C. Employee and Community Services.

 

Department

Managerial

Non-

Managerial

Total

1.

Communal and Housing

10

63

73

2.

Nursery

18

29

47

3.

Sports Facilities and Medical Centre

18

4

22

4.

Club

3

5

8

5.

Hostel and Hotel

2

10

12

Total

51

111

162

 

 

 

Overall Totals: Managerial Non-Managerial Total

179 1,162 1,341

 

 


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