WO1992016805A1

WO1992016805A1 - Air conditioning system for pasta and the like

Info

Publication number: WO1992016805A1
Application number: PCT/EP1992/000284
Authority: WO
Inventors: Pier Luigi Conselvan; Gastone DIDONÈ
Original assignee: Pavan Mapimpianti SpA
Current assignee: Pavan Mapimpianti SpA
Priority date: 1991-03-21
Filing date: 1992-02-10
Publication date: 1992-10-01
Anticipated expiration: 1993-09-21
Also published as: IT1249511B; ITVE910017A0; ITVE910017A1

Abstract

The system comprises: a tunnel (2), along which the pasta to be treated is fed, two banks (8, 8') of fins extending longitudinally within said tunnel (2) and traversed in a single direction by a thermal fluid, one bank (8) being traversed by heating fluid introduced at that end of the tunnel from which the pasta leaves, the other bank (8') being traversed by cooling fluid introduced, at a temperature less than the dew point, at that end of the temperature in which greatest condensation is desired, a pair of sensors (22, 24) associated with the bank of fins (8) traversed by the heating fluid, to measure the air temperature at the two ends of the tunnel, a pair of sensors (22', 24') associated with the bank of fins (8') traversed by the cooling fluid, to measure the air humidity at the two ends of the tunnel, a sensor (20') positioned in the cooling fluid entry pipe (10') to measure its temperature, and at least one temperature controller (18, 18') connected to said sensors (22, 22', 24', 20') to control, by regulator means (14, 14', 16, 16'), the temperature of the thermal fluids and their flow rate in order to obtain a predetermined temperature difference between the entry and exit of each bank (8, 8').

Description

Air conditioning system for pasta and the like

This invention relates to an air conditioning system for pasta and the like.

Production processes for pasta and the like generally comprise a final drying stage in which the water content of the pasta is reduced to an average .of 10-13% by weight, to ensure a long product shelf life.

With current methods, this operation is carried out under strongly drying conditions while the moisture content of the pasta is still high enough to keep it substantially plastic and hence able to accept a high drying rate without undergoing excessive stressing, after which gradually lessening drying conditions are used.

As the drying process is generally carried out at higher than ambient temperature, the pasta has firstly to be raised to the temperature required for commencing the drying cycle, after which it has to be reduced to ambient.

In heating the pasta with hot air, the moisture in the air in contact with the colder pasta can condense onto its surface, so causing it to stick together and suffer deterioration.

The subsequent cooling of the hot pasta with cold air can result in the heating of the cold air which grazes the surface of the hot pasta, to reduce the air humidity to a value which is too low, such as to cause excess drying.

Because of this it is important to be able to separately control these two parameters, ie temperature and humidity, in order to be able to heat the pasta without wetting it and to cool the pasta without drying it.

Up to the present time this has been achieved by subjecting the pasta under treatment to different climates achieved either in separate environments or in separate regions of the same environment. If operating in different environments, the pasta to be treated is transferred, for example by conventional conveyor belts, into the various environments in which suitable control systems maintain the desired climate. This method allows good control of the air conditioning process, but involves high plant and operating costs. If operating in separate regions of the same environment, and in particular in a tunnel divided longitudinally into several regions in which different climates are created, the plant and operating costs can be kept lower, but it is more difficult to control "the individual climatic regions because of the lack of physical separation between them.

In addition, in both cases the climate variations in passing from one region to another take pace not continuously but step-wise, ie in a form which does not ensure optimum treatment of the product.

An object of the invention is to achieve a climate which varies with substantial continuity within a continuous pasta drying process, hence overcoming .the drawbacks of known processes.

This and further objects which will be apparent from the ensuing description are attained, according to the invention, by an air conditioning system for pasta and the like, as described in claim 1.

A preferred embodiment of the present invention is described hereinafter with reference to the accompanying drawings in which:

Figure 1 is a schematic longitudinal section through a system of the invention; and

Figure 2 is a schematic cross-section therethrough.

As can be seen from the figures, the device of the invention comprises a tunnel 2 traversed longitudinally by a conveyor belt 4, on which the pasta 6 to be treated is placed.

The tunnel 2 is traversed longitudinaly by two banks of fins 8,8', each of which is provided with a pipe 10,10' for the unidirectional circulation of the thermal liquid, usually water, through the tunnel. The pipe 10,10' extends to the outside of the tunnel 2 to form a hydraulic circuit connected to a heat exchanger 12,12'. As described hereinafter, the hydraulic circuit comprises a three-way valve 14,14' for controlling the flow rate through the pipe 10,10' and a two- way control valve 16,16'. Both the valve 14,14' and the valve 16,16' are controlled by a temperature controller 18,18' fed by suitable sensors.

Specifically, with each bank of fins there is associated a probe 20,20' inserted into the pipe 10,10' to measure the temperature of the fluid entering the bank and a pair of air probes 22,22' and 24,24' positioned at the two ends of the bank and arranged to measure respectively the temperature and humidity of the air at the two ends of the tunnel 2. The six probes 20,20',22,22',24,24' are connected to the temperature controllers 18,18', which preferably consist of a single computer or any other apparatus able to make mathematical calculations and be interfaced with the sensors and with the control members 14,14',16,16'. The operation of the system according to the invention is as follows: if it is to be used for increasing the temperature and/or humidity of the environment, and hence for preparing the pasta for the drying cycle, the temperature of the fluid circulating through the bank of fins 8 is firstly controlled at the required value. In this control procedure, under the command of the temperature controller 18 the control valve 16 which regulates the temperature of the heating fluid is opened to a greater or lesser extent such that the temperature of the air at one of the two probes 22 or 24 corresponds to the preset value. The temperature controller 18 then also acts on the three-way valve 14 and hence on the flow rate of the heating fluid such that the temperature difference between the air at the two probes 22,24 is such as to cause the air at the other probe 24 or 22 to also reach the preset value. To control the humidity, the temperature controller 18' firstly acts on the control valve 16' to adjust the temperature of the fluid traversing the bank of fins 8' to such a value that the excess moisture condenses on this bank until the preset humidity is attained at one of the two probes 22' or 24' installed at the two ends of the tunnel 2. Said controller 18' then acts on the three-way valve 14' to vary the flow rate of the fluid through the pipe 10' until the temperature at the other end is such as to condense the required quantity of moisture to attain the set humidity also at thye other probe 24' or 22'.

In this manner when these adjustments have been effected and the system operates under the required conditions, the pasta 6, which enters the tunnel 2 with a temperature and water content depending on the process from which it originates, passes through the tunnel 2 subjected to a climate which is continuously variable in terms of temperature and humidity. Specifically, the temperature varies continuously from the entry to the exit of the tunnel and the humidity varies continuously in a manner independent of the temperature, so as not to subject the pasta to an excessively drying climate which could damage it.

The pasta leaving the tunnel 2 can then be fed to subsequent treatment. The system of the invention is also suitable for creating within the tunnel 2 a climate which is continuously variable in the opposite direction, ie presenting a continuous temperature reduction and a continuous humidity variation, for example to reduce the temperature of the pasta leaving the drying stage still at high temperature to close to ambient temperature without this temperature reduction continuiing to dry the pasta to an undesirable extent.

It should be noted that it is not generally necessary to cool the pasta to ambient temperature, it being sufficient to halt cooling at a temperature of 10-20°C higher than ambient, as the product can already be considered stable at that temperature. For this reason, any further cooling would be only for safety reasons and in order not to disperse the heat into the storage environment.

Claims

C L A I M S 1. An air conditioning system for pasta and the like, characterised by comprising:

- a tunnel (2) , along which the pasta to be treated is fed, - two banks (8,8') of fins extending longitudinally within said tunnel (2) and traversed in a single direction by a thermal fluid, one bank (8) being traversed by heating fluid introduced at that end of the tunnel from which the pasta leaves, the other bank (8') being traversed by cooling fluid introduced, at a temperature less than the dew point, at that end of the temperature in which greatest condensation is desired,

- a pair of sensors (22,24) associated with the bank of fins (8) traversed by the heating fluid, to measure the air temperature at the two ends of the tunnel,

- a pair of sensors (22',24') associated with the bank of fins (8') traversed by the cooling fluid, to measure the air humidity at the two ends of the tunnel,

- a sensor (20') positioned in the cooling fluid entry pipe (10') to measure its temperature, and

- at least one temperature controller (18,18') connected to said sensors (22,22' ,24',20') to control, by regulator means (14,14' ,16,16') , the temperature of the thermal fluids and their flow rate in order to obtain a predetermined temperature difference between the entry and exit of each bank (8,8').

2. A system as claimed in claim 1, characterised by also comprising a temperature sensor .(.20) positioned in the heating fluid entry pipe (10) and connected to said temperature controller (18) .

3. A system as claimed in claim 2, characterised in that in each circuit of which the pipes (10,10') form part there is provided a three-way valve (14,14') operated by the temperature controller (18,18') and acting in the sense of controlling the flow rate of the fluid circulating through the pipe.

4. A system as claimed in claim 2, characterised in that in each circuit of which the pipes (10,10') form part there is provided a control valve (16,16') operated by the temperature controller (18,18') and acting in the sense of controlling the introduction of fluid from outside the circuit in order to vary the temperature of the fluid circulating through the pipe.

5. A system as claimed in claim 1, characterised in that the two temeprature controllers consist of a single processor.