Objective
The project has three main objectives:
a. to improve the quality of the product, which must be acceptable to consumers who do not follow the normal methods of preparing the food. This refers to the cooking of the pasta in countries where it has only recently become a common foodstuff and is not cooked in the "traditional" manner;
b. to reduce the drying time and increase the productivity of the production line;
c. to save energy by producing it in a different way and recovering any waste.
For the purposes of the demonstration project, only the third objective is of interest, but that objective cannot be achieved without the other two.
The project aims to demonstrate the economics of a new plant for manufacturing long pasta, which has the following innovative elements:
- high-speed, counterflow dryer;
- a dual-fuel co-generator;
- a press with heat recovery.
With the conventional situation the total consumption of the plant is 32,88 x 10-3 TOE/h. For the demonstration project, taking the consumption of electricity to be more or less the same, the innovative situation provides only for the consumption of methane for the cogenerator (23.37 Nm3/h, PCI = 8,500 kcal/Nm3), amounting to: 19.86 x 10-3 TOE/h.
The saving is about 40% which could be increased still further by better design of the dryer.
With an estimated operation time of 5.500 h/y, and the cost of the installation around 600 million lire, the investment payback period of the demonstration project is about 9 years.
The investment also includes the cost of the new dryer, i.e. in the technological part of the plant.
This is an important factor in terms of the "repeatability" of the project, since, where a dryer is needed for a pasta-manufacturing line, the cost of the new type of dryer for a new plant would not fall completely under investment cost.
Furthermore, the new type of dryer costs approx. half that of a conventional one. The payback period on a new plant would therefore drop to 5-6 years.
The plant consists of two parts: one where primary energy is converted and/or exploited and one for actual production.
The primary energy part consists of:
- a dual-fuel diesel engine (operating on gasoil or methane or a mixture of the two) fitted with special oil cooling. The engine is connected to an alternator for electricity requirements and delivers heat energy using the cooling fluid and combustion fumes as vectors. At present the engine burns methane;
- oil/water exchanger where the oil heats the water which carries heat to the dryer;
- fumes/water exchanger where water heating is completed.
The production part of the plant consists of the conventional machinery for kneading, pressing, forming, stretching and extracting the long pasta. Incorporated amongst these machines are:
- a pasta forming press, where heat is recovered (set-screw) to be fed to the water used for kneading;
- a rapid, high-temperature counterflow dryer with internal recirculation of the damp air produced.
Finally, downstream of the dried pasta drying unit there is:
- a water/air exchanger where the cooling water from the dried product heats the air for ventilating the pressed product.
The plant is completed by control and regulation systems.
The spaghetti production line, operating 5,500 hours a year, has a capacity of 4,000 tonnes per year, which was not achieved in the course of the project
(485 kg/h or approx. 2,670 t/y).
The pasta-forming press is the first innovation. It gives maximum production with the minimum number of set screw turns and has the following positive effects:
On the product: it does not get as hot during manufacture;
On the productivity: overflow is reduced to a minimum;
On energy: the set screw is cooled only with the water needed for kneading
The new dryer operates at higher temperatures (85-95 deg. C.) than the conventional ones and has, in turn, the following positive effects:
On the product: reduction in negative effects due to the enzyme action of alphamilase and the Maillard reaction: better cooking properties;
On productivity: reduction in drying time (only 3-4 hours for spaghetti) which is three times as long in normal processes; little space taken up by the plant;
On energy; less consumption of electric energy; less consumption of heat energy;
- recovery from the recycling of the damp air.
The areas of heat recovery are:
- cogenerator, the cooling oil and combustion fumes giving rise to "non-process" heat recovery;
- recycling of damp air, making use of the latent heat of condensation and the sensible cooling heat of the condensate;
- recycling the cooling water from the dried product;
- the set screw of the forming press.
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DEM - Demonstration contractsCoordinator
33170 Pordenone
Italy