29485096 plant design biscuit manufacturing

8/2/2019 29485096 Plant Design Biscuit Manufacturing

1/45

DESIGN OF A PLANT TO PRODUCE ONE TONNE

OF BISCUIT PER DAY


2/45

EXECUTIVE SUMMARYA process plant to produce one thousand kilograms or one tonne per day on a single eight-hour shift basis has

been carried out with much precision and consideration given to the most optimum process route. An increase of 10%was given to the product so as to take care of losses along the production line and also to the plant producing undercapacity.

The materials needed for the production of the biscuit and their approximate percentages are: Flour-50%, water-30%, sugar-2%, salt -2%, baking powder-2%, additives-14%. The materials or equipment design are: one mixer, oneextruder and conveyor tunnel oven. Other equipments are sealing machines, water pump, filter, tables, pre-printed

nylon etc. 1492.96 kg of dough is mixed per day and 1000 kg of biscuit is the target to be produced with a 10%increase to account for losses in the production line. The heat generated over the whole production process is650358.92 kJ/hr. The profit at 75% and 100% capacities are N12.678m and N 17.7135 m respectively. Therecommended sales price is estimated at N3.60.

The feasibility and technological requirement for the production of a biscuit plant of total capacity of one tonneor 30000 thousands packs per day running only one eight hour shift. The approach used for the design of this processtechnology starts with the selection of the process route that will give optimum yield and low cost. The route waschosen after considering the existing routes industrially and modifying it to suite the capacity of this plant.

The equipment for the plant were also chosen based on their ability to carry out the expected functions of theplant, putting into consideration the working characteristics, capacity and area. They are also chosen based on thecharacteristics of the materials. The best were chosen and the process flow route with the equipment was determined.

The material and energy balance for the whole process units were done, to determine the flow of material in andout of the system and to determine the heat generated over the whole system. Each of the basic equipment like theoven, the extruder were selected or modified using the material and energy balance, and some design parameters fromdesign books and companies.

Analysis of the cash flow for profitability of the plant was then looked into using high expenditure ratio to lowrevenue rate of return. The analysis covers, the costing of machinery and equipments, the working capital, factory andbuilding cost, pre-operational expenses, contingency, cost of utilities and tax. The revenue generated at a selling rate of3.60 per pack was determined. The depreciation of equipments (20 years), office building and furniture (5 years each)and the trading profit was used to generate a good profit.

Site selection and plant location was also done, by looking into the market areas available to the product, thenature of competition, rate of consumption of the product, source of raw material, transportation of raw material and

product, availability of both skilled and unskilled labour, nature of utilities that will be needed for process andrecreation, environmental impact of process effluent (if any), climatic effect, topography, and strategic economicconsideration. Suggestion of the plant layout, safety of both material / product and man/machinery was also lookedinto, suggestion on waste management and services was done. After all the above consideration the resultsobtained during the study and design show some very interesting results for any investor. The type of biscuit chosenfor the production plant is the southern type biscuit (trade name) with a simple recipe of flour, sugar, salt, bakingpowder, additives and water with its own percentages by weigh. The ingredients are readily available in the marketlocally or by importation. This type of biscuit are already enjoying good acceptance in the market. The process routeselected is such that only one mixer is used and the paste or dough is poured into an extruder below, from where thedough is extruded through a mould, placed at the nozzles of the extruder which are then placed in trays for a two-in-one cutter stamp to cut and stamp the company logo. A conveyor then conveys these trays through a drying zone withthree compartments for the final drying (baking) of the biscuit. Products are then packed and sealed and cartooned forthe market.

The equipments for the plant are mainly the mixer, extruder and the oven, the choice of the mixer after carefulconsideration of material amount, characteristics and efficiency expected is the sigma z-blade which belongs to thedouble arm kneading mixing equipment group. It has good mixing action, readily discharges material, relatively easyto clean and does not allow sticking of material. By the nature of extruders, a total design is needed therefore, nochoice was made, however the design follows the basic principle. The choice of drying is the tunnel continuous dryerdue to the amount of heat expected to be generated and the nature of the product to be dried and also due to the natureof drying medium, steam. It is very suitable for materials that form bed with open structure. High drying rate isachieved, with good quality of product, high thermal efficiency, usage of steam as during medium as low as 1.5kg/kg of water for evaporation, and good recycle of steam, which gives cost effectiveness. The only disadvantagehere is the cost for mechanical belt maintenance for the conveyor. The source of heat is chosen to be steam, fromplant boiler and cooling water in the extruder nozzle as compared with electric heater which are expensive,difficult to maintain and heating which is not uniform. The capacity of the oven designed is 1m by 11.21m, theresident time in the drying/cooking zone is 15 min, the amount of material per day is 1,306 kg/day, heatgenerated as 99,990.82 kJ/hr and the process dynamic is subject to a pilot test. The capacity for the extruder designedis 0.1103 m , with the internal specification of 1m by 0.5 m long by 0.22 m high, resident time of 0.052 kg/s, theextrusion time is 0.141s, the amount of material extruded per hour is 186.6 kg/hr, heat generated is 469,800 kJ/hr,which is very high, about 70% of which is lost to the environment, thus adequate need for cooling water at the nozzle.The mixer capacity is designed to handle 622 kg/hr over 20 min of mixing for homogeneity, tank diameter is 0.622m, blade diameter is 0.25 m, the blade tip velocity is 1.44 m/s, the power consumption per unit volume is 118.225kN/m s, the design blade number is 2,700. The material in is also 186.6 kg/hr and the heat generated is80,568 kJ/hr, with a loss of 73, 641.28 kJ/hr. For every 1,492.8 kg of feed material 1.1 tonne of product isproduced which is estimated 10% above target to take care of losses of materials that may occur along process linee.g. burnt products or loss during mixing, extruding and cutting. The heat generated over the wholesystem is 650,358.82KJ/hr, most of which are lost, thus the mixer will be properly lagged and extrudercooled. The cooling water from the extrusion unit is sent to the boiler to generate treated water for oven i.e.conservation of energy.

The projected income and expenses evaluated is done with 75% capacity production for the startingyear, 2002 with 10% increase until the fourth year 2005. The total product for the first year of production is 210 tonneof biscuit, with a market sales of N 3.60 gives a revenue of N 22.50 million less than the yearly expenditure of N9.022 million and loan on interest at 0.8% gives a yearly net profit of N 12.678 million, and this increases as the plant

grows to operate at full capacity.Due to the market available for biscuit, the site of the plant should be close to the market within a reasonanorthern part and transported. Transportation by road and rail are safe. Other additives aremore concentrated in thewestern part.


3/45

C H A P T E R O N E

I N T R O D U C T I O N1.1 GENERAL

Biscuit like bread is a bakery wheat or wheat composite product of valuable foodnutrition. Biscuit came to Nigeria through the colonialists but have become popular amongour people, especially children of school age. Its acceptance is based on the ready forconsumption nature of the product. It can also be eaten alone or with other foods like milk,

tea, butter, stew, pap (ogi) etc (Adeniyi, 1998; Onyia, 1997).Biscuit is food and food is man's basic need. Being a food producer in a societywhere food is not only very expensive but scarce, it certainly has a ready market forinvestors. In the cities where there is little time for detailed cooking due to socio-economicfactors, ready-for-consumption foods like biscuits come to the rescue. This product is oftentaken as breakfast, or taken to offices or schools for lunch by children and adult alike. Theuse of biscuit for hospitality has become popular thereby creating huge demand for theproduct. The unit packaging available make it affordable even by the poor.

With a good quality publicity as well as price, biscuit production can be a goodprofit- earning business.

1.1.1 RAW MATERIALS

[1] FLOUR: This is the most important raw material, which can be made of wholewheat or composite from maize, cassava, millet etc. It takes not less than 50% of allingredients required. A small packet of biscuit of 30 g contains at least 15 g of flour.Wheat flour is produced locally (Ogunsola, 1999, Adeniyi, 1998).

[2] SUGAR: Sugar is essential for sweet taste which biscuit is known for. Sugar isproduced locally and allot is also imported to meet the huge national demand.Nevertheless, there are other natural sweeteners like honey, sweet potato and some nativeextracts that can be carefully incorporated as substitute or filler for sugar.

[3] ADDITIVES: These include flavouring, shortening, colourants and modifiers

like salt, eggs, milk, glucose, fat etc. They are added in very small quantities depending onthe type of biscuit needed.[4] WATER: Water is essential for mixing the ingredients to a workable level.

Water takes up to 30% of the components. This however, must be hygienic and clean.

6


4/45

[5] BAKING POWDER (AND/OR YEAST) : Baking powder or yeast isimportant, for biscuit making. Where fermentation is not done like in wafers, yeast is notneeded. The extent of swelling or rising of biscuits during production depends on thebaking powder or yeast as the case may be. All raw materials must of necessity be foodgrade and hygienic (Ogunsola, 1999, Adeniyi, 1998).

1.1.2 EQUIPMENT/TOOLS FOR PRODUCTION

The following equipment/tools are necessary for commercial production of biscuits(Crenan and Butter, 1990).

[1] OVEN (DRYER) : This can fired by wood, electricity or gas depending on thedesign.[2] MIXER: This can be manually operated or motorized to make mixing efficient.[3] MOULD/STAMP: The various designs that will appear on a biscuit depend on

the mould and stamp. There are manual and motorised types.[4] CUTTER: The cutter cuts mixed and flattened biscuit parts into the desired

sizes. It can be manual or motorized too.[5] Other tools such as wrapping and sealing machines, storage tanks, trolleys,

packing racks etc can be provided. These equipments and tools can be

fabricated locally to any desired standard.

1.2 DESIGN PROBLEM

The plant to be designed will have a capacity to produce one tonne (one thousandkilograms) of biscuit per day. The manufacturing operation is to comprise of the followingunits: mixing, extrusion, drying and packaging. The entire technological process is to be asemi continuous operation where materials are only manually operated during transferfrom the horizontal drier to the packaging. Services available are normal services withcooling water at a temperature of thirty degrees centigrade (30 C). A detailed chemical oengineering design is required with a flow diagram for the process accompanied with the

mass and energy balance for the equipments and units. At optimum operation thetechnology is to produce a minimum of thirty thousand packs (30,000 packs or 1 tonne) ofbiscuit per day or one for one eight our shift.

7


5/45

C H A P T E R T W O

M A N U F A C T U R I N G O P E R A T I O N S

2.1 INTRODUCTION

The process of making biscuit comprises of various unit operations. Following theformulation, the raw materials are carefully measured out and mixed in the dough mixer.The dough when formed is passed through the moulds. This is then stamped either before

or after cutting depending on the design of the plant. The dough pieces are taken to theoven where they are baked for at least 10-15 minutes at 200-250 C temperatures. This ohowever depends on the type and thickness of the biscuit to be produced. The bakedbiscuits are removed and sorted out. They are then packed in polyethylene or waxed paperpreviously printed and finally sealed on the sealing machine. The wrapped biscuits are inturns packed in cartons and taken to the market.

2.2 SELECTION OF PROCESS ROUTE

Basically, the technology of biscuit production involves the thorough mixing of thewheat four or other cereals (that can serve the same purpose) with other ingredients andadditives. After the mixing operation the dough is extruded and shaped to fancy, how be itwith some restriction in size and thickness. These shaped dough are then dried to reducethe water content and invariably browning. The biscuits are then packaged as desired andready for market (Crenan and Butter, 1990).

This process demand the following unit operations and auxiliary services:[1] Surface tanks [2] mixing equipment [3] extruder[4] Cutting equipment [5] stamping equipment [6] drying oven[7] Sealing machines [8] trays, rollers or conveyorThe flow of material through this equipment (units) is determined with the aim ofhaving optimum production cost and best quality of products. This influences the choice ofoptimum process route (Fig. 2.1). This route is chosen after answering the followingquestions:[1] Is the flow diagram logical, are the units compatible?[2] Is the technique feasible and logical?

8


6/45

[3] What are the possible flows, can they be corrected and controlled?[4] Which of the different kinds of the unit is the best considering cost, efficiency,durability, capacity, energy consumption?[5] Are the equipments readily available?[6] How safe are the units to operate?

2.3 CHOICE OF PROCESS ROUTE

The choice of process route for the biscuit plant is basically dependent on the sizeof the plant i.e. capacity. The basic process route (arrangement) of mixer, extruder, stamp,drying and packaging is universally well known and documented.

However, depending on plant capacity, the type of unit used becomes important.The use of other equipment such as pumps for supply of water to mixer, the need forcontinuous flow of materials, recycling e.t.c. are factors to be considered. Therefore in thedesign of the best process route, the route chosen should be seem to be at par with otherknown good techniques used in the biscuit industries, it is safe from both operational,human and environmental hazards, the technique is not technologically demanding. Theonly improvement may be the use of sophisticated equipment, which is not wiseconsidering the economy of the proposed plant capacity.

Therefore the choice of the optimum route has been done based on breaking downthe technology in unit operations. The choice of the required equipment was done afteranswering the questions stated above. Each unit is properly examined to choose the bestthat will be compatible with others. This is to ensure the optimal operation of theprocessing technique as shown on Fig 2.1 (Adeniyi, 1998).

Mixing Extruding Rolling Cutting Stamping

Packaging Cartooning Sealing Drying Trays

Fig. 2.1: Block diagram of biscuit production

9


7/45

2.4 PRODUCTION MACHINERY

A full list of the major production machinery needed for the production of onetonne of biscuit per day is presented in Appendix A.The department will require aminimum of one tonne of biscuit per day, per technological line. Water used for mixingmust pass through filters. The cooling system is necessary to avoid rapid evaporation ofwater as well as the blockage of the nozzle of extruder.

The dryer stage comprises of:1 horizontal oven with complete accessories.

Baking is a very important stage as it greatly determines the quality of the final products.The packaging department consist of:6 wooden silos6 weighing machinesNylon sealing machines

2.5 ANCILLARY OPERATIONS

In addition to the main production processes outlined above, several ancillary unitsmust be established for efficient operation of the factory. They include among others:

[1] QUALITY CONTROL UNIT:

A unit responsible for quality control at every stage of production will be set upto ensures compliance with set National Standards for food and beverages by the NationalAgency for Food, Drug Administration and Control (NAFDAC).

[2] MAINTENANCE UNIT:

A maintenance unit must be set up to ensure early fabrication of worn out parts Itshould be equipped with the necessary workshop machines. The workers are under theindirect production list, which is given in Appendix C.2.6 FACTORY PERSONNEL

Manning levels have been estimated fairly generously in comparison with those,which would be expected in a more developed industrial environment. The factory willoperate a single eight-hour shift system. The distribution of personnel along the

technological line is given in Appendix C under the direct production worker. It requires atotal of fifteen people. The indirect factory personnel are also given in Appendix C alsowith a total of fifteen people.

10


8/45

C H A P T E R T H R E E

M A S S A N D E N E R G Y B A L A N C E S

3.1 OVERALL BALANCE

The percentage compositions of the feed is known, what is not known is the massesof the feed but the masses of the product is 1000 kg of biscuit.

A detailed calculation is in Appendix B and a computer program has been written

to solve the material and energy balances. The computer program is in Appendix D(Adeniyi, 1998).

The percentage compositions of the feed materials are:[1] Flour 50% [2] Sugar 2.0%[3] Water 30% [4] Baking powder 2.0%[5] Additives/modif iers 16%Additives includes flavouring, shortening (about 14%), colourants and modifiers

includes salts (about 1.0%), eggs, milk, glucose and fat (They are added in very smallquantities depending on the types of biscuits)[Adeniyi, 1998, Ogunsola, 1999)]

3.1.1 MATERIAL BALANCE

From the material balance carried out it can be seen that to get a product of 1000 kg(1 tonne) of biscuit, a feed mass of 1357.15 kg of the raw material is required. This willrequire the following mass of feed:

[1] Flour 678.58 kg [2] Sugar 27.14 kg[3] Water 407.15 kg [4] Baking powder 27.14 kg[5] Addition/modifier 217.14 kg

3.1.2 HEAT BALANCE

At a moisture content of 30% the heat capacity of biscuit is estimated at 1.845kJ/kg C, the latent heat is 100.50 kJ/kg C. The heat required to bake 1kg of biscuit in the oo

oven is 715.97 kJ (kW). The heat required to bake 1357.15 kg of biscuit in the oven is1331960.46 kJ. The overall heat balance across the oven is calculated to be 1198766.35kJ,this is different from the heat required to bake 1357.15 kg because some moisture will

11


9/45

already be lost before the dough enters the oven. About 10% of moisture is expected to belost before the dough enters the oven and this amount to about 321.453 kg. Detailedcalculation of the heat balance is given in Appendix B. The results are summarised inTables 3.1-3.9.

Table 3.1: Overall material balance.Mass In Amount Amount Mass Out Amount Amount

(kg) (kg/hr) (kg) (kg/hr)Dry solid 1045.12 130.64 Solid (dough) 1045 130.63Water 447.84 55.98 Water 55 6.87

Losses 392.96 49.12Total 1492.96 186.62 Total 1492.96 186.62

Table 3.2: Unit material balance over the mixer.Mass In Amount Amount Mass Out Amount Amount

(kg) (kg/hr) (kg) (kg/hr)Dry solid 1045.12 130.64 Solid (dough) 1045.12 130.64

Water 447.84 55.98 Water 447.84 55.98

Total 1492.96 186.62 Total 1492.96 186.62

Table 3.3: Unit material balance over the extruder.Mass In Amount Amount Mass Out Amount Amount

(kg) (kg/hr) (kg) (kg/hr)Solid (dough) 1045.12 130.64 Solid (dough) 1045 130.63Water 447.84 55.98 Water 261.25 32.66


12


10/45

Table 3.4: Unit material balance over the dryer (oven).Mass In Amount Amount Mass Out Amount Amount

(kg) (kg/hr) (kg) (kg/hr)Dry solid 1045 130.63 Solid (biscuit) 1045 130.63Water 261.25 32.66 Water 55 6.87


Table 3.5: Overall energy balanceEquipment Heat load (kJ/hr)Mixer 80568Extruder 469800Dryer 99990.824Total 650358.824

Table 3.6: Unit energy balance over the mixerHeat generated Heat load (kJ/hr)

Heat load in dough 4226.72Heat loss in mixer 76341.28Total 80568

Table 3.7: Unit energy balance over the extruderHeat generated Heat load (kJ/hr)Heat load in dough 21283.2Heat loss in extruder 448516.8Total 469800

The unit energy balances across the dryer or oven is given in three zones namely: theheating zone, the constant rate zone and the falling rate zone.

13


11/45

Table 3.8: Unit energy balance over the dryer (oven)- Zone 1: Heating zoneHeat generated Heat load (kJ/hr)Heat load for dough 19725.13Heat load for liquid 13682.864Total 33407.994

Zone 2 is the constant rate change zone and the heat in is equal to the heat out which is

estimated as 40953.265 kJ/hr using the computer program developed (Appendix D).

Table 3.9: Unit energy balance over the dryer (oven)- Zone 3: falling rate zoneHeat generated Heat load (kJ/hr)Heat load in dough 3944.12Heat load in evaporated liquid 21109.32Heat loss in dryer 576.125Total 25692.565

Table 3.10: Total Heat balance over the Dryer (Oven)Heat generated Heat load (kJ/hr)Zone 1: Heating 33407.994Zone 2: Constant rate change 40953.265Zone 3: Falling rate 25629.565Total 99990.824

14


12/45

C H A P T E R F O U R

E Q U I P M E N T D E S I G N

4.1 CHOICE OF EQUIPMENT

In any production process, the choice of the equipment from the different types isvery important, so as to meet the production capacity target, ensure good quality ofproduct, maximise cost, durability, safety to life and property and cost of production.

Equipment are built with different sizes and shapes, they are designed on differentworking principle or operation, which are therefore characteristic of the use to which it willbe applied. It is therefore important to know the nature of the material in the process andthe equipment type that will serve ones purpose.

4.2 DOUGH AND PASTE

Dough and paste are mixed in machines, which have of necessity, to be heavy andpowerful. Because of the large power requirements, it is particularly desirable that themotor posses reasonable efficiency; as the power dissipated in the form of heat may causesubstantial heating of the product. Such machines may require jacketing mixer to removeas much heat as possible with cooling water (Richardson and Peacock, 1994).

The most commonly used mixers for these heavy material are the(1) Z-blade mixers(2) The pan mixers(3) The Kneader, which employs two contra rotating arms of special shape, which fold andshear the material across a cusp, or division, in the bottom

The blade of these mixers rotates at differential speeds, often in the ratio of 3:2.Mixing action of the Z-blade mixers combines shearing and kneading which is broughtabout by the specially shaped blades enabling it to mix, whip and knead materials rangingfrom low viscosity paste to stiff dough.

Other types of machines employ very heavy contra-rotating paddles, whilst amodern continuous mixers consist of an interrupted screw which oscillate with both rotaryand reciprocating motion between pegs in an enclosing cylinder. The important principle inthese machines is that the material has to be divided and folded and also displaced so thatfresh surfaces recombine as often as possible (Meyer, 1992; Perry and Green, 1997).

15


13/45

4.2.4 DESIGN OF MIXER

SPECIFICATIONN= Rotational speed s -1D=blade diameter mT=Tank diameter mP=Power Kgm /s 2 3e=density Kg/m 3=viscosity Kg/ms

U =Tip velocity m/st

N = Power numberp

V=volume m 31 =mixing (blending) time sN = Blend number

b

PHYSICAL DATA

Based on laboratory unit data and scale up exponent n see Appendix FN=108 s -1e=2200 kg/m 3

=200 Ns/s 2P=22.38 kgm /s 2 3v=0.1893 m 3L=laboratory unit dataDETERMINATION OF PARAMETERS

(1) SIZE OR CAPACITY

c=m/ 1where m= mass of dough1 =blend timec=622 kg/h(2) BLADE DIAMETER

D=sqr(PPL.NL .DL /PL..N ) 3 5 3 5D = 0.2549(3) TANK DIAMETER

16


14/45

T=sqr(TL .V/VL) 3 3T=0.622 m(4) TIP VELOCITY

Vt= ND=86.50 m/min=1.44 m/s(5) POWER PER UNIT VOLUME

P/V=118.23 kg/ms 3(6) POWER NUMBER

Np = P / eN3D5 = .1(7) BLEND NUMBER

NB=N 1=1620004.3 EXTRUDER

Extrusion is an operation in which a mass of plastic or semi soft material inside aheavy walled cylindrical container is forced to flow through an orifice (die or mould) atone end of the container as a result of pressure applied to the material by a piston (ram)acting at the other end of the container. The process is often successful on materials, whichare too brittle to work by other shaping methods such as rolling. The instruments for thisprocess are generally called extruders. They may come in many shapes and work with

different principles e.g. the extrusion mixer, presses the material via a kneader.Extrusion is well suited to producing long bars of constant cross section. The shape

of the cross section, which is determined by the die opening, may be quite complex. Theforce required for extrusion may be supplied by a hydraulic cylinder, which drives the ram.The material to be extruded must have sufficient plasticity so that it begins to flow throughthe die at a pressure less than the breaking point of the material. The ram pressure shouldnot be above 180,000lb/m . The die is another limiting feature of the process since it may 2lose its shape if pressure and temperature becomes excessive and abrasive wear may occur.

The pressure (force/area) required for extrusion is a function of the stiffness of thematerial, surface friction and changes in cross sectional are from the billet to the rod orshaped material (Perry and Green, 1997).

A useful expression is P = KlnR.Where R = Ratio of the initial to final cross sectional area

17


15/45

K = Constant which is a function of temperature

TABLE 4.1: EXTRUSION CONSTANT K OF SOME METALSMETAL TEMPERATURE K (lb/in ) 2

2S Aluminium 400 20,000600 12,000

800 8,500

1,000 7,500Iron 1,800 50,000

Powerful presses up to 15,000 tonnes capacity are used for extrusion, but the mostcommon size is about 2,500 tonnes. Suitable lubricants (ground nut oil) must be used toreduce extrusion force, increase die life and give better surface on the extruded product. Ingeneral the force required to overcome friction, even in well-lubricated operation is about

25% of total force (Richardson and Peacock, 1994).Extruded product are usually or sometimes used as extruded, but it is more

common practice to employ a subsequent cold working operation, such as drawing toimprove the surface finish and to get greater dimensional accuracy or desired thickness.

4.3.1 DESIGN OF EXTRUDER

SPECIFICATION

e=Density of dough kg/m 3m=mass dough kgU =Total volume of dough m 3

t

T=extrusion time sF=Force of extrusion NA=Area of piston m 2P=Pressure N/m 2V =Volume of dough extruded per sec m 3

E

U =velocity of piston m/st

H=height of extruder chamber mL=length of extruder surface m

18


16/45

W=thickness of extruded surface mDATA

e=2200 kg/m 3m=186.608 kgL=0.97 mW=0.40mH=0.05m

4.4 OVEN (DRYER)

Drying (baking) is the removal of volatile substances (moisture) by heat from amixture that yields a solid product (biscuit). Dryers are classified by:(1) HEATING METHOD : The manner whereby the moist material removes heat i.e. byconduction heating from the sheets or very wet material. Convective heating is the mostcommon, where mild heating is necessary to avoid heavy degraded product, and radiationdrying is used in the microwave oven (Macrea and Robbinson, 1997).(2) PROCESS CONDITION : The pressure and temperature of operation which areconstrained however by the nature of the materials to be dried. The thermal sensitivity ofthe material fixes the maximum temperature to which the material may be heated. The

temperature rises with the time the material is held in the dryer.(3) CONVEYING METHOD : The way the material is loaded or supported in the dryer.The outward appearance of the dryer depends largely upon the way the drying materialmoves through the equipment. Free flowing granules can be handled in many ways(conveyor, rolling, trays etc), but more awkward materials often require special techniques.Most modern dryers are operated continuously or semi-continuously over the working tray,as a continuous dryer will require less labour, fuel and floor space than the batch dryers.Certain factors are considered in the selection of dryer for particular purpose, they are:(1) Feed Condition: is it solid, liquid, paste powder, crystals etc.(2) Feed Concentration, the initial liquid content.(3) Product Specification, dryers required, physical form.

(4) Throughput Required.(5) Heat Sensitivity of The Product.(6) Nature of Vapour, toxicity and flow ability.

19


17/45

(7) Nature of the Solid: flammability (dust explosion hazard), toxicity.

4.4.1 CONVEYOR DRYERS(CONTINUOS CIRCULATION BAND DRYERS)

The conveyor dryer (oven) has been chosen for the production of one tonne ofbiscuit per day, because of the complete accessories it has to offer.

In this type the solids are fed onto the endless, perforated conveyor belt, throughwhich hot air is forced. The belt is housed in a long rectangular cabinet, which is divided

into zones, so that the flow pattern and temperature of the drying air can be controlled. Therelative movement through the dryer of the solids and drying air can be parallel or moreusually counter-current (Marcel and Dekkar, 1987).

This type of dryer is clearly only suitable for materials that form a belt with anopen structure. High drying rate can be achieved with good product quality control.Thermal efficiency are high and with steam heating, steam usage can be as low as 1.5 perKg of water evaporated.

4.4.2 DESIGN OF DRYERS (OVENS)

There may be more than one type of dryers suitable for a particular job, therefore

the choice based on optimal cost, fuel or power rating and space comes to mind during thedesign for a process dryer. The design Engineer chooses for a given dryer conditions whichenable the specified properties of the product to be obtained. In this way performancecharacteristics of alternative system can be expressed as a basis for the ultimate choice ofthe specified plant (Ulrich, 1986). Almost always some small scale are needed todetermine the materials drying characteristics required to predict the way which the shiftwill be in the commercial plant.

SPECIFICATION

A=Total surface area of dryer m 2

AH=surface area of heating zone m 2AC=surface area of concentred drying zoneAF=surface area of falling rate zone m 2DTMF= log. mean temperature difference in the falling rate zone C oDTMH= log. mean temperature difference in the falling zone C o

20


18/45

Ti= zone heating medium (steam) inlet temperatureTo=zone heating medium (steam) outlet temperatureti=zone in process material, inlet temperature in a zoneto=zone in process material, outlet temperature in a zone

DATA

THi=270K (543 C) oTHo=270K (543 C) o

tHi=80K (353 C)tHo=180K (453 C) oQH=33407.994 kJ/hQC=40953.265 kJ/hQF=25629.565 kJ/hUH = 142UC = 227.13UF = 852.2LH = 1LC = .8LF = .6

Moisture drying ratios25:40:155:8:3142:227.2:85.2DTMH = (543 - 453) - (543 - 353) / In((543 - 453) / (543 - 353))=183.83 =133.83DTMF = (543 - 513) - (543 - 453) / In((543 - 513) / (543 - 453))=39.15 =54.61AH=Q/UTL=33407.994/142x133.83x1=1.76m2AF=Q/UDTL=25629.565/85.2x54.61x.6=9.18AC=4953.265/227.13x(543-453)x0.8=0.267m2

21


19/45

C H A P T E R F I V E

E C O N O M I C S U R V E Y5.1 ECONOMIC ANALYSIS

5.1.1 ESTIMATED PROJECT COST

The following are the estimated costs of the project based on the prevailingeconomy of the country.

TABLE 5.1: ESTIMATED PROJECT COST

DESCRIPTION COST (N m)

MACHINERY & EQUIPMENT 4.90

FACTORY & OFFICE BUILDING 2.00

WORKING CAPITAL 2.00

AUXILIARY ITEMS (UTILITIES) 0.80

PRE-OPERATIONAL EXPENSES 0.30

GROSS TOTAL 10.00VALUE ADDED TAX (VAT, 5%) 0.50

NET TOTAL 10.50

The sales turnover is estimated at about thirty-million naira (N 30.0m) in the firstyear of operation while a profit margin of four million-naira (N 4.0m) is obtainable fromthe project.

The project can be financed through a mixture of equity contribution, term loan andoverdraft from commercial or merchant banks.

5.1.2 FIXED CAPITAL

Fixed capital refers to buildings, industrial plants, machinery and tools, motorvehicles, office equipment (Max and Klaus, 1973). The cost of machinery and equipment

22


20/45

is estimated at about five million naira (N 4.90 m) and that of factory space is estimated atabout two million (N 2.0m).

5.1.3 WORKING CAPITAL

Working capital is mostly referred to as circulating capital which are non-renewable goods, such as raw materials, fuel and the funds required to pay wages and otherclaims against the company ( Bauman, 1984; Ulrich, 1986). The estimated working capital

required for this project is two million naira (N 2.0m).The raw materials are estimated for four months requirements including goods-in-

transit already paid for. The salary for the personnel should also be enough for threemonths pay. Proper arrangement should also be made for contingencies.

TABLE 5.2: THE BREAKDOWN OF THE WORKING CAPITALITEM COST(N m)

4 MONTHS RAW MATERIALS 1.783 MONTHS SALARY 0.20

CONTINGENCIES 0.02TOTAL 2.00

5.1.4 NET COST

The net cost of the biscuit production plant including provision for working capitaland the value added tax (VAT) at 5% is estimated at about ten million naira (N 10.5 m).

5.2 COST OF PRODUCTION5.2.1 RAW MATERIALS

The main raw materials for the production of biscuit are flour, sugar, additives,water, baking powder and yeast. Wheat flour and sugar are produced locally and this willreduce the overall cost of production. Additives include; flavouring, shortening, colourantsand modifiers, which are also obtained locally while water, baking powder and yeast, arereadily available.

23


21/45

Most of these materials are locally produced (although most of them are stillimported to meet the demand of the populace) and thus help reduce the overall cost ofproduction and consequently produce biscuit at a cheaper rate, but putting intoconsideration that they must of necessity be good food grade and hygienic.

5.2.2 LABOUR COST

In estimating the labour requirement and cost for plant personnel, a one eight hour

shift was assumed for the direct production workers. The indirect production workers willalso operate a single shift for eight hours. The full labour requirement which are detailed inAppendix C are summarised below:

TABLE 5.3: LABOUR COSTDESCRIPTION NO.OF PEOPLE COST (N m)

DIRECT PRODUCTION WORKERS 15 840,000.00INDIRECT PRODUCTION WORKERS 15 1,548,000.00

TOTAL 30 2,388,000.00

5.2.3 OVERHEAD COST

The estimated overhead cost are enumerated in Appendix C. They are allocatedbetween production, administration and sales as follows:

TABLE 5.4: OVERHEAD COSTDESCRIPTION COST(N m)

PRODUCTION 1.012

ADMIN & SALES 0.280

TOTAL 1.292

5.3 DEPRECIATIONS

24


22/45

In estimating the depreciation charges, the plant and building were written off overa 20 years period, the equipment over 10 years, the office equipment and furniture over 5years. The charges arrived at are as follows:

TABLE 5.5: DEPRECIATIONASSETS VALUE DEPREC. ANNUAL DEP.

(N m) RATE % (N m)

OFFICE & FACTORY BUILDING 2.00 5 0.100PLANT & EQUIPMENT 4.90 5 0.245

OFFICE FURNITURE & EQUIPMENT 0.20 10 0.020TOTAL 0.365

5.4 PROJECTED INCOME AND EXPENSES STATEMENT (2002-2005)

Based on the production capacity of one tonne of biscuit per day, the total annualoutput (allowing 30 days for planned maintenance work) is 280 tonnes.

The average output of 210 tonnes has been estimated for the plant first year ofoperation (working at 75% capacity).

TABLE 5.6: PROJECTED INCOME AND EXPENSES STATEMENT

25


23/45

YEARS 2002 2003 2004 2005

TONNE 210 238 266 280CAPACITY, % 75 85 95 100

REVENUE

NET SALES (N m) 22.50 25.50 28.50 30.00

EXPENDITURE

RAW MATERIAL (N m) 5.34 6.24 7.16 7.72FACTORY LABOUR (N m) 2.39 2.42 2.62 2.82

DEPRECIATION (N m) 0.3650 0.3458 0.3277 0.3105

OVERHEAD (N m) 0.9270 1.0506 1.1742 1.2360TOTAL (N m) 9.0220 10.056 11.282 12.087

TRADING PROFIT

BEFORE INTEREST( N m) 13.4780 15.4436 17.2181 17.9135

LOAN INTEREST (N m) 0.8 0.6 0.4 0.2NET PROFIT (N m) 12.6780 14.8436 16.8181 17.7135

C H A P T E R S I X

S A F E T Y , S I T E & C O N C L U S I O N

26


24/45

6.1 SAFETY

6.1.1 SANITATION

In the biscuit industries, sanitation is the planned control of the productionenvironment, equipment and personnel to prevent or minimize loss, product contaminationand condition offensive to the aesthetic senses of the discriminating consumer and toprovide clean, healthful and safe working conditions.

Some of the broad areas of sanitation concern are(Meyer, 1992):[1] GOOD MANUFACTURING PRACTICES: This implies orderliness and

freedom from refuse in all areas.[2] RODENT ELIMINATION: It involves knowledge of rodent habits,

recognition of problems and permanent control through structural changes, removal ofharbourages and food supplies, and supplementary poisoning and trapping.

[3] INSECT EL IMINATION: Insect elimination from finished products andingredients in the factory requires recognition of serious or incipient infestations,identification and knowledge of habits and ecology. Control methods may involve changesin structure, equipment or process and safe use of insecticide chemicals.

[4] MICRO-ORGANISMS: The type and significance of which vary with productand type of operation, must often be controlled by process and equipment change, cleaningand sanitising chemicals.

Construction and maintenance of buildings and equipment are of major importancein sanitation. New units can be planned to simplify sanitation maintenance, reduce costsand eliminate the hazards of contamination and spoilage.

Cleaning of plant and equipment involves careful organisation, training, workscheduling and the use of the best available equipment, methods and materials. The trend isto clean processing equipment in place, without dismantling. This is done by an automaticsystem that circulates and sprays cleaning and sanitizing solutions inside equipment in timesequence.

Employment facilities, such as rest room, locker rooms, drinking water, eatingfacilities and working environment, must be well maintained for the comfort and safety ofthe workers if they are to remain happy and maintain production efficiency and product

quality.

27


25/45

Laboratory tests, of importance to the sanitation program in the biscuit plant, mustbe understood to be utilized to the best advantages.

Water supply quality and plant distribution systems, as well as waste treatment anddisposal, lighting and ventilation are often a part of sanitation.

Inspection techniques tailored to the specific sanitation situation must be taught,learned and applied for efficient functioning and adjustment of the sanitation program.

6.1.2 WASTE MANAGEMENTThis is a newer approach to cost-effective food-processing waste disposal. Through

waste management, modifications are applied to biscuit plant operation and manufacturingprocesses. These modifications reduce the amount of solid and liquid wastes, recover moreproduct and by-products, often reduce energy consumption and exhibit other benefits. Ingeneral, the principle is to convert waste liabilities into profitable assets.

One major objective of waste management is to eliminate or at least lessen thedependence upon end-of-the-pipe sanitary engineering methods. This is achieved byreducing both the amount of waste solids generated and the volume of the waste waterdischarged (Adeniyi, 1998).

The following are examples of modifications, which can be made to biscuit plant

operations:[1] Incorporating good manufacturing practices[2] collecting culls and other solid wastes into containers rather than discharging to thefloor drain,[3] recycling water[4] reusing spent process water in another plant operation and[5] using less or no water in plant operations that formerly used a fair to a large amount ofwater.

Good manufacturing practices that reduce water usage and waste require goodpersonnel management and employee awareness of conservation practices. Such practicesas needless use of water or overloading of containers, thereby causing spillage, should be

discouraged.Recycling of water in the same plant operation can be achieved by treating spent

process water with activated charcoal or sand filter or by ion- exchange columns, chemical

28


26/45

treatment, pH adjustment, temperature adjustment, pasteurisation, or a combination ofthese and other methods.

Counter currents water reuse systems can be established in many plant operations.For example, spent wash water can be used again to initiate wash down of dirty floors or toflume solid waste away from the process line.

6.1.3 HUMAN SAFETY

Any organisation has a legal and moral obligation to safeguard the health and

welfare of its employees and the general public safety is also good business; the goodmanagement practices needed to ensure safe operation will also ensure efficient operation.

The term "loss prevention" is an insurance term, the loss being the financial losscaused by an accident. This loss will not be the cost of replacing damaged plant and thirdparty claims but also the loss of earnings from lost production and lost sales opportunity.

Safety and loss prevention in biscuit industries can be considered under thefollowing broad headings;1) Identification and assessment of hazards.2) Control of the hazards.3) Control of the process. Prevention of hazardous deviation in process variables(pressure, temperature, flow), by provision of automatic control systems, interlocks,

alarms, trips together with good operating practices and management.4) Limitation of loss. The damage and injury caused if an accident occurs; pressure relief,plant layout, provision of fire fighting equipment.

6.1.4 THRESHOLD LIMIT VALUEThis is the most commonly used guide for controlling the long-term exposure of

workers to contaminated air. The threshold limit value is defined as the concentration towhich it is believed the average worker could be exposed to day to day, for eight hours aday, five days a week, without suffering harm (Odigure, 1995).

6.1.5 NOISE

29


27/45

Excessive noise is a hazard to health and safety. Long exposure to high noise levelcan cause permanent damage to hearing. At lower levels, noise is a distraction and causesfatigue. Excessive plant noise can lead to complains from neighbouring factories and localresidents. Due attention should be given to noise levels when specifying and when layingout equipment that is likely to be excessively noisy and such as compressors, fans, barriersand steam relief valves.

6.2 PLANT LOCATION AND SITE SELECTIONThe location of the plant can have a crucial effect on the profitability of a project,

and the scope for future expansion. The principal factors are:(1) Location with respect to the marketing area(2) Raw material supply(3) Transport facility(4) Availability of labour(5) Availability of utilities (water, fuel, power etc.)(6) Availability of suitable land(7) Environmental impact and effluent disposal(8) Climate

(9) Political and strategic consideration

6.2.1 MARKETING AREA

For a product such as biscuit in which case the product per tonne is low the plantshould be located close to the primary market.

6.2.2 RAW MATERIALS

The availability of suitable raw materials will often determine the site location. Aplant that will produce biscuit should be sited close to where the major raw materials are

available.

6.2.3 TRANSPORTATION

30


28/45

The transport of materials and products to and from the plant is an overridingconsideration in site location. The plant should be located close to at least two major formsof transport: road, rail, waterway (canal and river) or airport. Choosing at least two will bean added advantage for the two cannot be out of service at the same time.

6.2.4 AVAILABILITY OF LABOUR

Labour will be needed for construction of the plant and its operation. Skilled

workers will be brought in from outside the site area, but there should be an adequate poolof unskilled labour locally and labour suitable for training, to operate the plant. Skilledtradesmen will be needed for plant maintenance.

6.2.5 UTILITIES

A biscuit plant invariably requires large quantities of water for its operation(process and general use). Hence the plant must be located near a source of water ofsuitable quality. Process water may be drawn from borehole or purchased from localauthority. Electrical power will be needed for the plant production process (mixer, electricpumping machine, oven heater etc.) and also for lightings.

6.2.6 ENVIRONMENTAL IMPACT

Full consideration must be given to the difficulties and cost of disposal of biscuitplant's by-product.

6.3 LAND (SITE) CONSIDERATION

Sufficient suitable land must be available for the proposed plant and for futureexpansion, the land should be ideally flat, well drained and have suitable load bearingcharacteristics.

6.4 CLIMATE

Since weather in Nigeria is neither too hot nor too cold, the site consideration inform of climate can be neglected since the raw materials will not degrade in quality overthe little time for storage and production. Also the country is not situated within theearthquake region of the world.

31


29/45

6.5 POL ITICAL AND STRATEGIC CONSIDERATION

Capital grants and other inducement are often given by government to direct newinvestment to preferred area or locations such as high unemployment prone zone. Theavailability of such grants can be the overriding consideration in site selection.

6.6 SITE LAYOUT

The biscuit industry and ancillary building should be laid out to give the most

economical flow of material and personnel around the site. Consideration must also begiven to the future expansion of the biscuit factory. The ancillary buildings and servicesrequired on a site in addition to the main processing units (buildings) will include:(1) Storage for raw materials and products(2) Maintenance workshop(3) Stores for maintenance and operating supplies(4) Laboratory for process control(5) Fire station and other emergency services(6) Utilities (storage tank, cooling water, steam)(7) Effluent disposal plant(8) Offices for general administration

(9) Canteens, car park, security post etc.When roughing out the biscuit factory layout the process unit will normally be sited

first and arranged to give a smooth flow of material through the various processing steps,from raw material to final step.

The location of principal ancillary buildings should then be decided. They shouldbe arranged so as to minimize the time spent by personnel in travelling between buildings.

The sitting of the main process route will determine the layout of the plant roads,pipe alleys and drains. Access roads will be needed to each building for construction,operation and maintenance. Utility buildings should be sited to give the most economicalruns of pipes to and from the process units. The main storage area should be placedbetween the loading and unloading.

R E F E R E N C E SAdeniyi O.D. (1998) Design of a plant to produce one tonne of Biscuit per day Plant

32


30/45

Design Thesis, Federal University of Technology, Minna, pp. 1-63Bauman H.C. (1984) Fundamental of cost engineering in the chemical industry Reinhold

Publishing corporation, New York, pp. 16-67, 415-516Crenan J.G. and Butter J.R. (1990) Food engineering operation , George Godwin Inc.,

Vol. 3, London, pp. 571-603Macrea J.A. and Robbinson D.K. (1987) Drying principles and practice , Pergamon

Press, Oxford, pp. 14-21, 115, 231,412Marcel and Dekkar (1987) Handbook of industrial drying Munjar Inc., 4 edition, New th

York, pp. 393-412Max P. and Klaus D.T. (1973) Plant design and economics for chemical engineers

McGraw Hill Book company, New York, 3 edition, pp. 11-24 rdMeyers R.A. (1992) Encyclopaedia of physical science and technology vol. 15, 2 nd

Edition, academic press Inc., London, pp, 519-520Odigure J.O. (1995) General chemical engineering technology Jodigs and associate,

Minna, pp. 19-24, 129Ogunsola V. (1999) Food preparation recipes for Nigerians schools and homes Update

Media ltd., Ilorin, pp. 116-128Onyia C. (1997) Make your money producing biscuits Success digest magazine, LagosPerry R.H. and Peacock D.G. (1994) Coulson and Richardosn chemical engineering

Vol. 3, 3 edition, Pergamon Press, Great Britain, pp. 71-103 rdUlrich G.D. (1986) A guide to chemical engineering process design and economics

Wiley & sons company, New York, pp. 33,46,105

A P P E N D I X A

LIST OF PRODUCTION PLANT MACHINERY

33


31/45

A list of the production machinery needed for the production of one tonne ofbiscuit per day is (Adeniyi, 1998):[A] THE MIXING UNIT

(a) 2 water tanks(b) 1 mixer(c) 1 weighing machine(d) 1 measuring/regulating device for water(e) 1 water pump

[B] THE EXTRUDER UNIT(a) 1 extruder fitted with mould, cutting and stamping device

[C] THE DRYING UNIT

(a) 1 horizontal dryer with conveyor belt(b) 1 collection table(c) trays

[D] THE PACKAGING UNIT

(a) 6 wooden silos(b) 6 tables(c) 6 weighing machines(d) Nylon sealing machines

A P P E N D I X B

CALCULATION OF MASS & ENERGY BALANCE

34


32/45

B1.1 OVERALL BALANCE

The composition of the feed is as listed in chapter three. From the material balancecarried out it can be seen that to get a product of 1000 kg (1 tonne) of biscuit, a feed massof 1357.15 kg of the raw material is required. This will require the following mass of feed:


B1.1.1 MATERIAL BALANCE

Taking a basis of 1000 kg of feed; the masses of the feed based on the compositionis:

(a) Flour = 50%=500 kg(b) Sugar = 2.0%=20 kg(c) Water = 30%=300 kg(d) Baking powder = 2.0%=20 kg(e) Additives = 16%=160 kgInitial moisture content = 30%=300 kgFinal moisture content = 5% = 50kg

300 kg of moisture is associated with 700 kg of dough300 kg ---> 700 kg (i.e. 300 kg + 700 kg = 1000 kg)50 kg ---> 950 kg of dry matter (i.e. 50 + 950 =1000 kg)

==> (50 x 700)/950 =36.84 kg moisture associated with 700 kg1000kg of original matter must loss (300-36.84)=263.16 kg of moisture==> weight of dried matter leaving the dryer

=1000-263.16 =736.84 kgWorking backward,0.30T ---> 0.70T0.05T ---> 0.95TY=(0.05T x 0.70T) / 0.95T =0.0368T

x of the original matter must loss (407.15-49.998) = 357.15kg0.3T - 0.0368T = 357.15 kg

35


33/45

T(0.3-0.0368) = 357.15 kgT= 357.15/0.2632=1356.95 kg

The difference (1000-736.84) =263.16 kg of moisture lostThe difference (1356.95-357.15)= 999.8 kg of biscuit, this value is 0.2 short of theexpected 1000kg. This means that the original feed must be (1356.95 + 0.2)= 1357.15 kg.

B1.1.2 HEAT BALANCE

Heat capacity = ((4.19 P) +(0.84(100-P)))/100where P= moisture content of biscuit dough =30%

Heat capacity=((4.19x30)+(0.84(100-30)))/100=1.845 kJ/kg C oLatent heat = 335P/100= 335x30/100=100.50 kJ/kg C o

Heat required for 1kg original material:= Heat energy to raise temp. to 100 C + Latent heat to vaporise water = m Cp0 + m Lo

1 2

=1 x 1.845(100-30) + (357.17 x 2257)/1357.15 = 715.97 kJ (kW/s)The heat required in baking 1357.15kg= 1357.15x1.845(240-30) + 357.17 x 2257= 525827.77+806132.69 = 1331960.46 kJ

Since 10% of moisture is lost the overall heat balance over the oven is:m =(1357.15-(1357.15x10)/100 = 1221.44 kg1

=(357.17 - (357.17x10)/100 = 321.453 kgme

Heat = 1221.44 x 1.845 (240-30)+ 321.453x2257 =1198766.35 kJFrom the material balance carried out, to get a product of 1000kg (1 tonne) of

biscuit we will need to feed a mass of about 1492.96 kg of the raw material. This willrequire the following mass of feed:


The loss is estimated at 134.85 kg to make up to 1492.96 (1357.15 + 134.85)

B1.1.3 OVERALL MATERIAL BALANCE

In a hourly basis:

36


34/45


35/45

On a hourly basis:Water in = (447.84/8) = 55.98 kg/hrSolid in = (1045.12/8) =130.64 kg/hrMaterial in (total) =(55.98 + 130.64)= 186.62 kg/hrWater out = (261.25/8)= 32.66 kg/hrSolid out =(1045/8)= 130.63 kg/hr ; Losses = (186.71)/8=23.34 kg/hrTotal material out =32.66 + 130.63 = 163.29 kg/hr3.1.2.3 DRYER

Basis: 1000kg/hr of productWater in = 261.25 kgSolid in = 1045.00 kgTotal material in = (261.25 + 1045)=1306.25 kgWater out = 55 kgSolid out = 1045 kgTotal material out =(55+1045) = 1100 kgOn a hourly basis:Material in = 1306.25/8= 163.28 kg/hrMaterial out =1100/8= 137.50 kg/hrDry solid in = 1045/8=130.63 kg/hr

Dry solid out =1045/8=130.63 kg/hrWater in = 261.25/8= 32.656 kg/hrWater out =55/8= 6.875 kg/hr3.2 ENERGY BALANCE

3.2.1 OVERALL ENERGY BALANCE

HEAT GENERATED FOR THE MIXER + HEAT GENERATED FOR THEEXTRUDER + HEAT GENERATED FOR THE DRYER = TOTAL HEAT LOAD80568 + 469800 + 99990.824 = 650358.824 kJ/hr3.2.2 UNIT ENERGY BALANCES

Most of the energy balances were done using the computer program developed (AppendixD)

3.2.2.1 MIXERHeat in = 80568 kJ/hr

38


36/45

Heat load in dough = 4226.72 kJ/hrHeat loss in mixer = 76341.28 kJ/hr3.2.2.2 EXTRUDER

Heat in = Heat outHeat generated in extruder = Heat load in dough + heat loss in extruderHeat generated = 469800 kJ/hrHeat loss in extruder = 448516.8 kJ/hrHeat load in dough = 21283.2 kJ/hr

3.2.2.3 DRYERThe dryer zone has three zones:

Zone 1 (heating zone)Heat generated for solid = 19725.13 kJ/hrHeat generated for liquid = 13682.864 kJ/hrTotal heat load for zone 119725.13 + 13682.864 = 33407.994 kJ/hr

Zone 2 (constant rate change zone)Heat in = Heat outHeat generated = 40953.265 kJ/hrZONE 3 (falling rate zone)

Heat load for solid = 3944.12 kJ/hrHeat load for evaporated water = 21109.32 kJ/hr

Total heat load in the filling rate zone= Heat in solid + Heat in evaporated liquid

= 3944.12 + 21109.32 + 576.125= 25629.565 kJ/hr

Total load for the dryer = 33407.994 + 40953.265 + 25629.565= 99990. 824 kJ/hr

A P P E N D I X C

F I N A N C I A L E V A L U A T I O N

39


37/45

C1.0 LABOUR REQUIREMENT AND COST

The total labour requirements were estimated on the basis that the direct productionworkers will work one eight hour shift and the indirect production workers also a singleeight hours shift.C1.1 DIRECT PRODUCTION WORKERS

NUMBER UNIT COST TOTAL

(N m) COST(N m)

SUPERVISOR/ENGINEER 1 40,000.00 40,000.00MIXING UNIT 2 16,000.00 32,000.00

EXTRUSION UNIT 2 16,000.00 32,000.00

DRYER UNIT 4 20,000.00 80,000.00PACKAGING UNIT 6 16,000.00 96,000.00TOTAL 15 280,000.00

C1.2 INDIRECT PRODUCTION WORKERS

40


38/45

NUMBER UNIT COST TOTAL

(N m) COST(N m)

MANAGING DIRECTOR 1 70,000.00 70,000.00PRODUCTION MANAGER 1 56,000.00 56,000.00

ACCOUNTANT 1 52,000.00 52,000.00

ADM. MANAGER 1 52,000.00 52,000.00SALES MANAGER 1 52,000.00 52,000.00

CASHIER 2 24,000.00 48,000.00SECRETARY/TYPIST 1 22,000.00 22,000.00

SECURITY 4 20,000.00 80,000.00

QUALITY CONTROLTECHNICIAN 2 20,000.00 40,000.00

TECHNOLOGIST 1 44,000.00 44,000.00TOTAL 15 516,000.00

C1.3 OVERHEAD COST

41


39/45

PRODUCT- ADM. & SALES TOTAL

ION(N m) (N m) COST(N m)

FUEL,POWER & WATER 140,000 60,000.00 200,000.00MAINTENANCE 240,000 - 240,000.00

CONSUMABLE MATERIAL 120,000 - 120,000.00

GROUND RATE & RENT - 60,000.00 60,000.00INSURANCE 60,000 - 60,000.00

VEHICLE RUNNING 40,000 20,000.00 60,000.00TRAVELLING 12,000 40,000.00 52,000.00

POSTAGE & PHONE - 40,000.00 40,000.00

ADVERTISEMENT - 60,000.00 60,000.00DEPRECIATION 400,000 - 400,000.00

TOTAL 1,012,000 280,000.00 1,292,000.00

C1.4 PROJECTED INCOME AND EXPENSES STATEMENT

1 Tonne of biscuit/day, in 1 year = 1x365 tonnesLess 30 days of maintenance =365-30=326 tonnesLess 48 days of non-working days in a year = 326-48= 278 . 280Based on capacity the following tonnes are evaluated:(a) 75%=0.75x280=210 (b)85%=0.85x280=238(c) 95%=0.95x280=266 (d)100%=1.00x280=280

C1.4.1 REVENUETotal sales revenue of N30m is expected on 100% capacity. So for other capacities:

(a) 75%=0.75x30= N 22.50m (b) 85%=0.85x30= N 25.50m(c) 95%=0.95x30= N 28.50m (d) 100%=1.00x30= N 30.00mC1.4.2 Depreciation

1 year (2002)=0.365 st2 year (2003) nd

a. Factory= 0.1 (5/100 x 0.1)=0.0950b. Equipment= 0.245 (5/100 x 0.245)=0.2328

42


40/45

c. Furniture = 0.02 (10/100 x 0.02)=0.018Depreciation = 0.0950 + 0.2328 + 0.018 = 0.34583 Year (2004) rd

d. Factory= 0.0950 (5/100 x 0.0950)=0.0903e. Equipment= 0.2328 (5/100 x 0.2328)=0.2212f. Furniture = 0.018 (10/100 x 0.018)=0.0162

Depreciation = 0.0903 + 0.2212 + 0.0162 = 0.32774 Year (2005) th

g. Factory= 0.0903 (5/100 x 0.0903)=0.08579h. Equipment= 0.2212 (5/100 x 0.2212)=0.2101i. Furniture = 0.0162 (10/100 x 0.0162)=0.01458

Depreciation = 0.08579 + 0.2101 + 0.01458 = 0.3105C1.4.3 Overhead

Overhead = total depreciation1 year = 1.292 0.365= 0.927 st2 year = 0.927 x 85/75= 1.0506 nd3 year = 0.927 x 95/75 =1.1742 rd4 year = 0.927 x 100/75 = 1.2360 thC1.4.4 Trading profit

Trading profit before interest = revenue - expenditure1 year = 22.50 9.022= 13.478 st2 year = 25.50 10.0564 =15.4436 nd3 year = 28.50 11.2819 =17.2181 rd4 year = 30.00 12.0865 = 17.9135 thC1.4.6 Net profit : net profit = trading profit loan interest1 year = 13.478 0.8 = 12.6780 st2 year = 15.4436 0.6 = 14.8436 nd3 year = 17.2181 0.4 = 16.8181 rd4 year = 17.9135 0.2 = 17.7135 th

43


41/45

A P P E N D I X D

C O M P U T E R P R O G R A MA computer program was written in basic to solve the material and energy balance,

the program is listed below (Adeniyi, 1998):CLSLOCATE 2, 20: PRINT "PLANT DESIGN PROJECT"LOCATE 4, 2: PRINT "DESIGN OF A BISCUIT PLANT WITH 1 TONNE CAPACITYPER DAY"

LOCATE 6, 20: PRINT "COMPILED BY GROUP TWO"LOCATE 8, 20: PRINT "FEBRUARY 1998"'A$ = INPUT$(1)20 :INPUT "Mass of feed (Kg)"; FMA = .3 * FMB = .7 * FMC = .05 * FMD = .95 * FML = (MC * MB) / MDMM = MA - MLWB = F - MMHC = ((4.19 * 80) + (.84 * (100 - 80))) / 100LH = (335 * 80) / 100HR = ((100 - 80) * HC) + (.25 * 2257)HR2 = HR / 3600PRINT "OVERALL MATERIAL AND HEAT BALANCES"PRINT "Weight of moisture lost by wet dough in dryer="; MM; "Kg"PRINT "Weight of dried biscuit leaving the drier ="; WB; "Kg"PRINT "Heat capacity of biscuit ="; HCPRINT "Latent heat of biscuit="; LH; "KJ/Kg C"PRINT "Heat required to dry 1Kg of biscuit="; HR; "KJ"; "or"; HR2; "KW/h"HH = ((240 - 80) * HC * F) + (MM * 2257)PRINT "Heat required to dry"; F; " Kg ="; HH; "KJ"

44


42/45

PRINT "IS THE MATERIAL BALANCE SATISFACTORY"PRINT "THEN PRESS Y FOR YES AND N FOR NO"30 :A$ = INKEY$: IF A$ = "" THEN 30IF A$ = "Y" THEN 50IF A$ = "y" THEN 50IF A$ = "N" THEN 20IF A$ = "n" THEN 20

50 :WIN = .3 * FASIN = .7 * FTIN = WIN + AASINPRINT "MASS BALANCE OVER MIXER"PRINT "Weight of water in is equal to weight of water out="; WIN; "Kg"PRINT "Weight of solid in is equal to weight of dough out="; ASIN; "Kg"A$ = INPUT$(1)60 :AD = (.95 * WB) / .8WOUTD = .05 * WB

SOUTD = WB - ADASIND = .8 * ADWIND = .2 * AD

PRINT "MASS BALANCE OVER DRYER"PRINT "Weight of moisture entering dryer="; WIND; "Kg"PRINT "Weight of moisture leaving dryer="; WOUTD; "Kg"PRINT "Weight of dough entering dryer="; ASIND; "Kg"PRINT "Weight of dough leaving dryer="; SOUTD; "Kg"A$ = INPUT$(1)

70 :

45


43/45

WINE = .3 * FWOUTE = WINDWRE = WIN - WOUTEASINE = .7 * FSOUTE = .2 * ADPRINT "MASS BALANCE OVER THE EXTRUDER"PRINT "Weight of moisture entering extruder="; WINE; "Kg"PRINT "Weight of moisture leaving extruder="; WOUTE; "Kg"

PRINT "Weight of moisture removed from extruder="; WRE; "Kg"PRINT "Weight of dough entering extruder="; ASINE; "Kg"PRINT "Weight of dough leaving extruder="; SOUTE; "Kg"A$ = INPUT$(1)80 : HEE = 22.38 * 3600HLD = WRE * 1.57 * 15HLM = HLD - HEEPRINT "HEAT BALANCE OVER THE DRYER"PRINT "Heat load in dough="; HLD; "KJ/h"PRINT "Heat loss in extruder"; HEE; "KJ/h"90 :

PRINT "HEAT BALANCE OVER THE DRYER"PRINT "Balance is estimated over 3 zones of the dryer"PRINT "ZONE 1- HEATING ZONE"PRINT "Inlet temperature =80 C"PRINT "Outlet temperature=180 C"QHL = (WIND * 4.19 * 100) / 8QHS = (ASIND * 1.5 * 100) / 8QH1 = QHL + QHSPRINT "The heat load in liquid="; QHL; "KJ/h"PRINT "The heat load on dough="; QHS; "KJ/h"PRINT "The total heat load for zone 1="; QH1; "KJ/h"

A$ = INPUT$(1)PRINT "ZONE 2- CONSTANT RATE ZONE"

46


44/45

PRINT "Inlet temperature =180 C"PRINT "Outlet temperature=220 C"QC = 2257 * 18.145PRINT "The total heat load for zone 2="; QC; "KJ/h"A$ = INPUT$(1)PRINT "ZONE 3- FALLING RATE ZONE"PRINT "Inlet temperature =220 C"PRINT "Outlet temperature=240 C"

QFS = 130.6 * 1.51 * (240 - 220)QFE = 7.635 * (2769 - 4.19)QFV = 6.875 * 4.19 * (240 - 220)Q3 = QFS + QFE + QFVQT = Q1 + QC + Q3QM = 469800PRINT "The Heat load for the dough ="; QFS; "KJ/h"PRINT "The heat load for the evaporated liquid="; QFE; "KJ/h"PRINT "The heat load for the unevaporated liquid="; QFV; "KJ/h"PRINT "The heat load for zone 3="; Q3; "KJ/h"PRINT "The total heat load for the dryer= "; QT; "KJ/h"

PRINT "IS THE UNIT BALANCE SATISFACTORY"PRINT "THEN PRESS Y FOR YES AND N FOR NO"120 : A$ = INKEY$: IF A$ = "" THEN 120IF A$ = "Y" THEN 200IF A$ = "y" THEN 200IF A$ = "N" THEN 20IF A$ = "n" THEN 20200 : QQT = QT + HEE + QMPRINT "THE OVERALL HEAT GENERATED OVER THE WHOLE PROCESS=";QQT; "KJ/h"END

47


45/45

A P P E N D I X ETYPICAL SUPPLIED HORSEPOWER FOR SIGMA BLADE

Table E1: Typical supplied horsepower (Hp) for sigma blade

Size number Capacity (Gallon) Horsepower Floor space (ft ) 2Working Maximum (Hp)

4 0.7 1.0 1.0 1 x 3

6 2.3 3.5 2.0 2 x 38 4.5 4.0 5.0 3 x 411 10.0 15.0 15.0 5 x 612 20.0 30.0 25.0 6 x 614 50.0 75.0 30.0 6 x 815 100.0 150.0 50.0 8 x 1016 150.0 225.0 60.0 9 x 1117 200.0 300.0 75.0 9 x 1318 300.0 450.0 100.0 9 x 1420 500.0 750.0 150.0 11 x 1621 600.0 900.0 175.0 12 x 16

22 750.0 1125.0 225.0 12 x 1723 1000.0 1500.0 300.0 14 x 18

Conversion rating1 Gallon = 0.003785 m = 3.785 litres 21 ft = 0.3048 m1 Hp = 0.746 kW

48

29485096 plant design biscuit manufacturing

Documents