DESIGN OF A PLANT TO PRODUCE ONE TONNE OF BISCUIT PER DAY
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 under capacity. 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, one extruder 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 is 650,358.92 kJ/hr. The profit at 75% and 100% capacities are N12.678m and N 17.7135 m respectively. The recommended sales price is estimated at N3.60. The feasibility and technological requirement for the production of a biscuit plant of total capacity of one tonne or 30,000 thousands packs per day running only one eight hour shift. The approach used for the design of this process technology starts with the
selection of the process route that will give optimum yield and low cost. The route was chosen 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 the plant, putting into consideration the working characteristics, capacity and area. They are also chosen based on the characteristics 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 and out of the system and to determine the heat generated over the whole system. Each of the basic equipment like the oven, the extruder were selected or modified using the material and energy balance, and some design parameters from design books and companies. Analysis of the cash flow for profitability of the plant was then looked into using high expenditure ratio to low revenue rate of return. The analysis covers, the costing of machinery and equipments, the working capital, factory and building cost, pre-operational
expenses, contingency, cost of utilities and tax. The revenue generated at a selling rate of 3.60 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, the nature 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 and recreation, environmental impact of process effluent (if any), climatic effect, topography, and strategic economic consideration. Suggestion of the plant layout, safety of both material/ product and man/machinery was also looked into, suggestion on waste management and services was done. After all the above consideration the results obtained during the study and design show some very interesting results for any investor. The type of biscuit chosen for the production plant is the southern type biscuit (trade name) with a simple recipe of flour, sugar, salt, baking powder, additives and water with its own percentages by weigh. The ingredients are readily available in the market locally or by importation. This type of biscuit are already enjoying good acceptance in the market. The process route selected is such that only one mixer is used and the paste or dough is poured into an extruder below, from where the dough 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 with three compartments for the final drying (baking) of the biscuit. Products are then packed and sealed and cartooned for the market. The equipments for the plant are mainly the mixer, extruder and the oven, the choice of the mixer after careful consideration of material amount, characteristics and efficiency expected is the sigma z-blade which belongs to the double arm kneading mixing equipment group. It has good mixing action, readily discharges material, relatively easy to clean and does not allow sticking of material. By the nature of extruders, a total design is needed therefore, no choice was made, however the design follows the basic principle. The choice of drying is the tunnel continuous dryer due to the amount of heat expected to be generated and the nature of the product to be dried and also due to the nature of drying medium, steam. It is very suitable for materials that form bed with open structure. High drying rate
is achieved, with good quality of product, high thermal efficiency, usage of steam as during medium as low as 1.5 kg/kg of water for evaporation, and good recycle of steam, which gives cost effectiveness. The only disadvantage here is the cost for mechanical belt maintenance for the conveyor. The source of heat is chosen to be steam, from plant 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, the resident time in the drying/cooking zone is 15 min, the amount of material per day is 1,306 kg/day, heat generated as 99,990.82 kJ/hr and the process dynamic is subject to a pilot test. The capacity for the extruder designed is 0.1103 m3, with the internal specification of 1m by 0.5 m long by 0.22 m high, resident time of 0.052 kg/s, the extrusion 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 0.622 m, blade diameter is 0.25 m, the blade tip velocity is 1.44 m/s, the power consumption per unit volume is 118.225 kN/m2s, the design blade number is 2,700. The material in is also 186.6 kg/hr and the heat generated is 80,568 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 is produced which is estimated 10% above target to take care of losses of materials that may occur along process line e.g. burnt products or loss during mixing, extruding and cutting. The heat generated over the whole system is 650,358.82KJ/hr, most of which are lost, thus the mixer will be properly lagged and extruder cooled. 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 starting year, 2002 with 10% increase until the fourth year 2005. The total product for the first year of production is 210 tonne of biscuit, with a market sales of N 3.60 gives a revenue of N 22.50 million less than the yearly expenditure of N 9.022 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 reasonable radius. The raw material, flour can be sourced locally from the
northern part and transported. Transportation by road and rail are safe. Other additives are more concentrated in the western part.
CHAPTER ONE INTRODUCTION1.1 GENERAL Biscuit like bread is a bakery wheat or wheat composite product of valuable food nutrition. Biscuit came to Nigeria through the colonialists but have become popular among our people, especially children of school age. Its acceptance is based on the ready for consumption 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 society where food is not only very expensive but scarce, it certainly has a ready market for investors. In the cities where there is little time for detailed cooking due to socio-economic factors, ready-for-consumption foods like biscuits come to the rescue. This product is often taken as breakfast, or taken to offices or schools for lunch by children and adult alike. The use of biscuit for hospitality has become popular thereby creating huge demand for the product. 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 good profit-earning business.
1.1.1 RAW MATERIALS  FLOUR: This is the most important raw material, which can be made of whole wheat or composite from maize, cassava, millet etc. It takes not less than 50% of all ingredients 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).  SUGAR: Sugar is essential for sweet taste which biscuit is known for. Sugar is produced locally and allot is also imported to meet the huge national demand. Nevertheless, there are other natural sweeteners like honey, sweet potato and some native extracts that