Raw Materials And Manufacture Engineering Essay

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Smurfit Kappa Group (SKG) is a multinational cooperation specialising in paper-based packaging. The group operates in 30 different countries (21 in Europe and 9 in Latin America) with 38,000 employees and 343 operating facilities. In 2009 the group's turnover was €6 billion. They are well known as world leader especially in Europe in manufacture of containerboard, solidboard, graphic board, sack paper, bag-in-box as well as corrugated and solidboard packaging.

SKG comprises into 4 divisions

Smurfit Kappa Corrugated- producing 4.8 million tonnes of corrugated packaging.

Smurfit Kappa Paper- 4.9 million tonnes production of container board.

Smurfit Kappa Specialities- 1.6 million tonnes.

Smurfit Kappa Latin America- 1.3 million tonnes (2009 facts and figures)

SKG is also the industry leader in recycling in Europe, sourcing approximately 5 million tonnes of recovered paper as raw material for the group's mills.

The Birmingham based Plant which is -a paper mill for 130 years- is a part of Smurfit Kappa plc. The plant produces 190,000 t/yr of recycled based Testliners (2&3) and Fluting. Below are the types of Testliners with various widths and weights (in gsm)

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Main Grammages

Unit

120

135

150

170

200

220

Burst

kPa

324

351

390

442

450

500

SCT CD

kN / m

1.80

2.09

2.33

2.55

3.02

3.41

Moisture

%

7.5

7.5

7.5

7.5

7.5

7.5

Raw materials and Manufacture

Recovery of used paper and cardboard is a prime raw material for all solid board mills and most container mills. This is because it is a valuable source for fibre that can be recycled into new paper and packaging materials, which in this case is fluting and TL 2&3.

The paper machine consists of four main sections- wet end, wet press section, dryer section and Finishing/ calendaring.

To start off the wet end; the stock preparation takes place in a vessel called the 'headbox' (Twin wire Fourdrinier machine, 40,000 m/min) containing an agitator with perforated plate at the bottom. The agitator speed is the key parameter for a perfect desired mixture. Too fast and the mixture would be less viscous whereas, too slow means the mixture would be more viscous for the same amount of water being putted in. The pulp is refined by removing waste materials for instance plastic or metals, such that they attach to the rope suspended in the centre of the headbox which is then being pulled mechanically from the headbox. However, on the way to the headbox the pulp passes through set of cleaners (centrifugal), removing heavy impurity such as sand or screens which causes fibre clumps to break. The headbox is a CSTR tank with mean residence time of about 80lbs/min of recovered paper. The pulp is further blended to give a stock dilution of 1% fibre and 99% water. Once the appropriate proportion is achieved, the fibre is then forced through a rectangular opening called the slice, where Base ply wire is introduced which is a moving permeable fabric. This helps to control the consistency of the fibre.

The second section of PM4 is the Wet Press section, which has two presses operating at 5 bars which reduce water content to about 60%. Whereas, the third press known as Extended Nip Press (ENP) further reduces water content to about 47%. ENP operates at 68 bars using hydraulic pressure using Polymethane belt which prevents friction during pressing.

In Dry section, the paper is dried by a series of 54 internally steam heated cylinders that evaporate the moisture off the paper. Fresh dry warm air forced below the cylinders, passing over the cylinders, leaving moist air to evaporate from the top, as shown on the sketch. At the same time, flow mixer is used to mix the slurry (starch) with steam to produce starch solution which then enters the reaction line where the mixture becomes more viscous. Water and hydrogen peroxide is used to reduce viscosity and cut the polymer chains (fibres) for required length. The starch solution is then sprayed over the paper by means of jets to ensure the end-product with 7-8% fibre. Furthermore, the Grammages and even distribution of fibre along the paper is controlled using Beta rays.

Finishing is the final section in PM4 where the web has a moisture content of 6%. The Paper leaving the machine is then rolled onto a reel and taken away for further processing.

Dirty water treatment using Heat exchanger

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At Smurfit Kappa, the recycling process produces 3m3 of water effluent per tonne of paper that is produced. This waste water is treated in their newly build waste water treatment plant.

The plant removes COD (Chemical Oxygen Demand) through anaerobic digestion, with a heat exchanger removing the excess heat and using it in other parts of the plant as well as determining the amount of dissolved oxygen needed by aerobic biological organisms by means of a chemical procedure called BOD (Biological Oxygen Demand). The procedure is carried out at a constant temperature of 37oC, 10oC less than the temperature of recycled waste water.

Heat exchanger system is used to remove the excess heat, which is then can be used in other parts of the process. There are two Heat exchangers, wide gap plated and thin gap plated. Prior to Heat exchanger, automatic filtration system is installed, which uses Dissolved Air Flotation (DAF) principle to remove plastics and larger contaminants from the flow. Similarly, another filtration system removes the remaining particulates by down filtering down to 1mm. The system is automatic, self cleaning by means of shells placed in the tube which produces eddies and turbulence in the flow due to high velocity. This means it filtration process can operate continually without the need of maintenance.

Control system

The control system at Smurfit kappa is highly sophisticated and fully live automated system. Which means it can be monitored live by authorised personnel outside the plant. During paper process, there are more than 2500 parameters which are controlled and monitored by the control system at a time. Some of the control parameters are listed below;

The speed of rollers and cylinders must be consistent and is thus controlled at all times throughout the process to avoid paper breakage, otherwise process termination will occur.

Furthermore, cameras are set in place at the press section that take digital pictures of the paper for any holes or tears (during vacuum pressing) and forwards it to the central control room.

Moisture content is monitored at the dry end to ensure the 7-8% fibre at end product. Negative feedback was in place to send signal at the Wet end to increase/decrease the fibre composition in paper accordingly.

Beta radiation is used to monitor the Grammages. Once again negative feedback is used to maintain the desired level.

The speed of agitator in the headbox as well the mean residence time and the flow rate through the perforated plate at the bottom of headbox are all maintained and controlled by highly complex control system.

Furthermore, variable such as the pH, temperature, viscosity and velocity of the pulp in the headbox, energy input are all being monitored constantly and displayed near necessary equipment as well as in the control room for ease of reference.

If these variables change, the respective buzzer sounds as a warning. The system is then in need of attention to rectify the problem, however, the process does not come to a stop unless the warning is severe or there is an emergency. In sight of an emergency, sirens will go off, equipment will shut down and exits will open for staff to evacuate.

There are 8-9 operators working at a time. 1 in the warehouse controlling robots and loading products in order to be dispatched. 2 in the stock preparation control room. 2 at the wet/dry-press section. 2 at the quality control unit and a technician.

Safety Procedures and PPE

To ensure Health & Safety of employees around the plant; 12 must have things were in place, listed as follows:-

All plant must have an annual safety action plan regularly updated and communicated to all employees.

Plant safety meeting should be held a minimum of ten times a year and be minuted with clear action points including times lines and responsibilities.

Plant accidents must be analysed collectively and conclusions communicated to all employees.

Plant must have systems to report and analyse near misses and conclusions communicated to all employees.

Notice boards including number of safe calendar days and record of safe calendar days must be visible for all employees and visitors when entering the plant.

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Every Smurfit kappa employee must wear safety shoes when circulating in manufacturing areas and every person must wear ear protections in all areas where the noise level is above 850dB.

High visibility jackets must be worn by all pedestrians in warehouses and loading/ unloading areas.

All walkways must be respected at all times.

All lift trucks restraints (such as seat belts and doors) must be used at all times.

Lift truck drivers must drive backwards when carrying loads unless for specific cases, safe systems of work based on a risk assessment are defined.

Storage and stacking of any loads must be steadied everywhere.

All guarding systems must be in place and active when machines are producing.

Similarly, other rules and procedures that were observed around the plant are as follows:-

Access to the machine was restricted to authorise personnel only, having been provided with ID cards. Barriers are in place on all sides of machine, headbox, heat exchangers and water treatment plants in order to prevent anyone from entering without consent.

Visitors (such as students) are given temporary ID cards with limited and accompanied access to the process plant. Visitors' entries are being recorded on the database.

Process lines were laid around the paper machine to restrict any physical contacts.

A white footpath was laid around the site as a form of traffic to avoid any conjunction to machinery and vessels

Health & safety as well as hazard awareness signs were posted throughout the site.

Heat and Mass Transfer

The overall process of drying paper consists of three phases; heating up the sheet, constant-rate drying and falling-rate drying. Heat (Steam) can be conducted from inside of the drying roller, through various resistances and out to the sheet. However, there are some factors that limit the rates of Heat and Mass Transfer. For instance; the air layer on inside and outside of the roll, the steel shell of the roll and the paper itself.

During heat transfer, the overall heat coefficient decreases. This is because the heat flow between the paper and steam is reduced due to the build up of deposits on the inner surface of drying roll.

To increase heat transfer to the paper; felts are used which press the paper closer to the drying roller. As the dry warm air from bottom is forced upwards; the moisture from the paper evaporates. However, a boundary layer of water and vapour is formed over the surface of the roll. As we know that boundary layer affect (reduces) the heat transfer. Therefore, tension is applied to the felt to avoid boundary layer formation by great extent. The downside to this strategy is it usually causes an increase in the drying capacity. To compensate this problem; a movable

Stretcher roll is placed, which adjusts the tension on the felt as required. This is done through an automatic control mechanism.