EP1701098A2

EP1701098A2 - Improvements in a solar boiler

Info

Publication number: EP1701098A2
Application number: EP06425165A
Authority: EP
Inventors: Antonio Bee; Luigi Rizzo
Original assignee: COSTRUZIONI SOLARI Srl
Current assignee: COSTRUZIONI SOLARI Srl
Priority date: 2005-03-11
Filing date: 2006-03-10
Publication date: 2006-09-13
Also published as: ITRM20050031U1; EP1701098A3

Abstract

A solar boiler provided with means for absorbing the volume changes of the thermal carrier fluid caused by the expansion of the latter and inlet means of the thermal carrier fluid which has been discharged under overpressure and/or high-temperature conditions.

Description

The present finding relates essentially to thermal installations for the utilization of solar power.
Widespread problems of the known solar installation are damages, wrong operations, and loss of mechanical resistance of the components caused by high temperatures and overpressures reached during summer.
To overcome these problems safety devices have been proposed which discharge to the outside the fluid exceeding the maximum pressure allowed in case the inner pressure of the system exceeds the predetermined limits.
Although these systems avoid effectively structural damages to the installation, the latter needs a periodic maintenance at least to save the fluid which has been discharged in case of overpressure.
The main object of the present invention is to reduce to a minimum the need of maintenance of the solar installations.
This has been accomplished according to the finding by providing a solar boiler which is provided with means able to absorb the volume variations of the thermal carrier fluid caused by the expansion of the latter and to let into the system the thermal carrier fluid which has been discharged in case of overpressure and/or high temperatures.
A better understanding of the finding will result from the following detailed description with reference to the accompanying drawings that show a preferred embodiment thereof and a simplified variation only by way of a not limiting example.
In the drawings:

Figure 1 shows schematically the main parts of a solar boiler according to the finding;
Figure 2 shows schematically the main parts of the means for the recovery and inlet of the thermal carrier fluid again according to the present finding.

According to the finding, the installation of the solar boiler has a circuit for the recovery of the thermal carrier fluid which is discharged under overpressure and/or high-temperature conditions, and for the following inlet into the system again as such conditions assume the normal operation values.
With reference to figure 1, as the temperatures reached inside the solar circuit and the accumulation circuit are too high, the thermal carrier fluid expands until the limits allowed by the safety devices 23 of the known type, such as an expansion tank.
Over such pressure limits, the fluid is discharged from the safety valve 13, however, it does not go lost but recovered by a suitable collecting device into a suitable vessel 17. Said thermal carrier fluid the composition of which is unchanged (for example, a water/glycol mixture) is then recovered from the above vessel 17 for its inlet into the solar circuit again. Before such inlet which takes place through autoclave 19 provided with a device 20 which detects a pressure difference at its ends (known on the market with the name of "electronic regulation means for motor-driven pump"), the fluid crosses an automatic loading assembly which acts as a pressure regulation means 22 allowing the previously discharged thermal carrier fluid to be reintegrated into the circuit, thus keeping the predetermined pressure unchanged.
According to the finding it is also possible to provide check means of the minimum level of the thermal carrier fluid (reached only in extraordinary events) inside the collecting vessel 17. In the embodiment shown said check means includes a couple of level probes 27 (forming an electric circuit closed by the water/glycol solution as electrolyte), a minimum-level detector 28 and sound and/or light signalling means 29 in order to allow the manual inlet of the fluid into the circuit again.
In a preferred embodiment of the present finding a solar boiler provided with the automatic recovery of the thermal carrier fluid disclosed above includes the following components (fig. 1):

A) A two-layer accumulation boiler 1 of 500 litres of china glass or teflon with two fixed heat exchangers or with outside plate exchanger and relative circulation apparatus for the thermal exchange;
B) An automatic collecting and filling assembly comprising manifold for expansion liquid 15, collecting and filling vessel 17, autoclave 19, electronic regulating means for motor-driven pump 20, pressure gauge 21, automatic loading assembly 22, and minimum-level detecting 27, 28 and signalling 29 devices;
C) Safety devices of solar circuit comprising expansion tank 23 and safety valve 13;
D) A solar circulator 25 for transmitting the thermal carrier fluid from solar panel to boiler;
E) A water filling safety assembly comprising further check valve 12, second expansion tank 11, and second safety valve 13;
F) Boiler integration circuit regulation means comprising a valve 10 electrically controlled by a temperature probe (SC) 4 of the same integration circuit;
G) An electronic control panel 26;
H) Distribution board of the system with switches;
I) Dimensions: height 179 cm; width 81 cm; depth 106 cm.

The solar boiler disclosed above can be installed both at the inside and outside.
Advantageously, the assembling of the whole hydraulic components of the integration parts consisting of boiler or heat pump, solar circuit, power supply and water distribution is made in factory. This allows all tests necessary to guarantee the full operation of the system to be carried out.
As a result, the installation of the finding is extremely easy: it is sufficient to connect the water pipes, the pipes of the solar circuit and the boiler integration circuit to the different manifolds located on the outside walls of the disclosed device to make up the boiler.
A further advantage of the present finding is to avoid any mistake during the installation and to reduce cost and time.
As mentioned above, the boiler is provided with means including an automatic loading circuit which allows the thermal carrier liquid discharged by the safety valve of the solar circuit during the maximum expansion step to be recovered, thus ensuring the full operation of the solar power system and its capability of matching the different operation conditions over time.
The control panel with electronic exchange for the automatic control of the whole system sends drive signals to the solar circuit and the boiler according to the signals received from the several temperature probes located at different heights inside the boiler.
The finding disclosed above can be produced and assembled according to a wide range of size: for example, from a small-size model comprising an accumulation tank of 200 litres designed for a two-solar-panel system to a large-size model comprising an accumulation tank of 5000 litres designed for a fifty-solar-panel system.
Referring to figure 1 the components of the solar system with relative reference numerals are drawn up in the following list:

1 accumulation boiler (500 litres)
2 hot water outlet
3 boiler delivery
4 SC boiler integration probe
5 backflow to boiler
6 solar circuit delivery
7 SS solar exchanger probe
8 backflow to solar circuit
9 cold water supply
10 local valve, motor-drive valve
11 expansion tank for cold water supply
12 check valve
13 6 atm safety valve
14 locking key
15 manifold for expansion liquid
16 delivery to automatic filling vessel
17 automatic collecting and filling vessel
18 backflow from automatic filling vessel
19 autoclave
20 electronic regulation apparatus for motor-driven pump
21 pressure gauge
22 automatic loading assembly
23 solar-circuit expansion tank
24 solar-circuit loading-unloading valve
25 solar-circuit circulation means
26 control panel and electronic exchange
27 level probe
28 minimum level detector
29 remote signalling means.

A simplified variation of the finding (fig. 2) providing the same advantages disclosed above and to be applied to the already existing solar boilers includes means for the collection of the thermal carrier fluid in case of overpressure and/or high temperatures, and means for the automatic filling of the solar circuit as the pressure and/or temperature conditions assume the normal operation values again.
In other words, said simplified variation consists essentially of the automatic collection and filling assembly comprising expansion liquid manifold 15, filling vessel 17, autoclave 19, electronic regulation means for motor-driven pump 20, pressure gauge 21, automatic loading assembly 22, and minimum-level detecting and signalling devices 27, 28 and 29, respectively.
It should be now appreciated that the installation of such simplified variation of the finding only requires to check the safety valve 13 of the solar circuit by a suitable thermal carrier fluid recovery manifold 15 as well as the backflow pipe from said solar circuit for the following inlet of said fluid again into the circuit from which it has been discharged.
At last the electronic regulation apparatus for motor-driven pump 20 should be connected to control panel 26 provided with electronic control exchange of the solar boiler.
The present finding has been described and illustrated according to a preferred embodiment and a variation thereof, however, it is self-evident that anyone skilled in the art can make technically and/or functionally equivalent modifications and/or replacements without departing from the scope of the present industrial invention.
For example, the simplified variation can be effectively used without essential modifications and with the same advantages disclosed above in all solar installations in which a thermal carrier fluid is used.

Claims

An apparatus for absorbing the volume variations of the thermal carrier fluid of a solar installation, characterized in that there is provided in combination means for the recovery of the thermal carrier fluid which is discharged in a known manner under overpressure and/or high-temperature conditions, and means for the following automatic inlet into the system again as such conditions assume the normal operation values again.
The apparatus according to the preceding claim, characterized in that there is provided in combination: manifold for the recovery of the thermal carrier fluid (15), collecting or filling vessel (17), autoclave (19), electronic regulating means for motor-driven pump (20), automatic loading assembly (22), said thermal carrier fluid being collected in filling vessel (17) from which it is taken for its inlet into the solar circuit again.
The apparatus according to the preceding claim, characterized in that means to check the minimum level in the filling vessel is provided comprising level detecting means (27, 28) and minimum-level signalling means (29).
The apparatus according to claim 2 or 3,
characterized in that a pressure gauge (21) is further provided.
The apparatus according to claims from 2 on, characterized in that said manifold (15) for the recovery of the thermal carrier fluid is able to check the output of a safety valve (13) of the solar circuit.
The apparatus according to any preceding claim, characterized in that the thermal carrier fluid is input again into the backflow pipe of the solar circuit.
The apparatus according to claim 3, characterized in that said minimum-level detecting means of the collecting vessel (17) includes one or more level probes 27, a minimum-level detector 28 and sound and/or light signalling means (29), thus providing a signal for the manual inlet of the fluid into the circuit again.
A solar boiler, characterized in that an apparatus according to one or more preceding claims is provided for the automatic recovery and refilling of the thermal carrier fluid which is discharged in a known manner in case of overpressure and/or high temperatures.
The solar boiler according to the preceding claim, characterized in that there are provided the following components:
A) A two-layer accumulation boiler (1) of china glass or teflon with two fixed heat exchangers or with outside plate exchanger and relative circulation apparatus for the thermal exchange;

B) An automatic collecting and filling assembly comprising manifold for expansion liquid (15), collecting and filling vessel 17, autoclave (19), electronic regulating means for motor-driven pump (20), pressure gauge (21), automatic loading assembly (22), and minimum-level detecting (27, 28) and signalling (29) devices;

C) Safety devices of the solar circuit comprising expansion tank (23) and safety valve (13);

D) A solar circulator (25);

E) A water filling safety assembly comprising further check valve (12), second expansion tank (11), and second safety valve (13);

F) Boiler integration circuit regulation means comprising a valve (10) electrically controlled by a temperature probe (4) of the same integration circuit;

G) An electronic control panel (26);

H) Distribution board of the system with switches and wiring;
The solar boiler according to the preceding claim, characterized in that control panel (26) with electronic exchange for the automatic control of the whole system sends drive signals to the solar circuit and the boiler according to the signals received from the several temperature probes located at different heights inside the boiler.
The solar boiler according to the preceding claim, characterized in that there is provided an accumulation tank with a capacity of 200 litres for a two-solar-panel system to 5000 litres for a fifty-solar-panel system.
An apparatus for absorbing the thermal carrier fluid volume changes of a solar installation as essentially disclosed and illustrated in the present description and the appended claims.
A solar boiler able to absorb the thermal carrier fluid volume changes of a solar installation as essentially disclosed and illustrated in the present description and the appended claims.