FR2733583A1 - Boiler with banked water-tube frames independently controlled - Google Patents

Abstract

Typically the boiler has several tubular frame heat-exchangers, individually connected to flow (4) and return (3) collector pipes, banked together, using long bolts (5), to enclose a central combustion chamber between end-shields, with replaceable insulating gaskets (2), which contain the burner and flue components. The flow connections in each frame have thermally operated valves (10) opening at adjustable setting temperatures. Opt., frames are interconnected laterally at top and bottom via similar valves, obviating the need for collectors. The external structure opt. includes a hot-water cylinder mounted on vertical standards. Drain, safety and filling valves follow normal practice. By omitting one thermostatic valve some circulation is always permitted, reducing pump wear.

Description

HEATER WITH EXCHANGERS
THERMOREGULATED FLOW RATE
Boilers with heat transfer fluid and with liquid, solid, gaseous or electric fuel generally consist of two distinct parts: - The burner or hearth, whose function is to produce a flame from a fuel, - The exchanger body, of which the function is to allow the heat exchange between the flame and the combustion gases with the heat transfer fluid (often water) to be heated, and this by means of a conductive wall of variable shape according to the types of exchangers.

This shape is generally complex in order to provide a large exchange surface in a reduced volume.

Among the types of boilers currently existing, we particularly know: - The heating body made up of several exchanger elements tight against each other (this is generally the case with boilers with cast iron elements), that is to say where the water flows from one to the other element. They require devices for distributing the fluid flow, generally an internal distribution tube.

the blind hearth technique implies that the first exchanger element "sees" all of the combustion gases pass at their maximum temperature, the element following all the gases at a lower temperature (effectively, there was an exchange with the first element) and so on, the gases gradually decreasing in temperature as the various exchanger elements pass, until the heater leaves the chimney.

One solution to address this disparity in heat exchange capacity has been to distribute the flow rates of the heat-transfer fluid by means of an internal distribution tube (the most stressed element has a greater flow rate than one of the less stressed ones). This distribution results in more or less large calibrated openings (for a given flow rate), distributed over the length.

This distribution is unfortunately not constant due to variations in flow in the heat transfer circuit (presence of 3 or 4-way motorized valves in regulation).

On the other hand, the boiler exchanger bodies are increasingly designed to allow use at very low temperatures, an energy-efficient configuration. This design makes it possible, with very low heating returns and starts, to avoid the phenomena of condensation of the combustion gases on the walls of the hearth and thus to reduce the risks of corrosion.

Different systems exist for operating at very low temperatures: - Starting the heating circulation pump as soon as the temperature of the hearth has reached a set temperature (in fact, the water does not circulate in the exchanger as long as the temperature in it is too cold), - Design of the heating body with internal thermosyphon circuit, - Presence of a thermostatic valve in the heating body (generally in single steel or cast iron heating bodies), - Heat exchange function of the contact between expanding walls, etc ...

The present invention allows, whatever the geometry of the exchanger (gas path and hydraulic path), the hearth mode (blind, open) and regulation on the installation, to allow an optimum and homogeneous heat exchange over the exchanger element or elements of the heating body.

This results in an internal flow regulation specific to each exchanger element or circuit equipped with a thermostatic valve.

Figures 2 and 5 show an advantageous mode of construction of this boiler, the figured geometry is not limiting.

Figure I shows the boiler in section,
Figures 2 and 5 show the boiler with the exchanger elements (1).

Figure 3 shows an insertion of the thermostatic valve in the exchanger element (1).

Figure 4 shows the addition of a domestic hot water tank (23).

The boiler is placed on the heat transfer fluid circuit. A circulation pump is used to irrigate the circuit.

When the installation starts, the heat transfer fluid is cold. The thermostat requests the rise in temperature of the fluid by authorizing the start-up of the burner.

The thermostatic valve or valves (11) with autonomous regulation are closed, because the temperature of the fluid in the exchanger element concerned is lower than the preprogrammed opening instruction of the thermostatic valve (11).

As soon as the heat transfer fluid, under the influence of the burner, reaches the set temperature for opening the valves (11), the fluid, under the pressure of the circulation pump, therefore begins to circulate in the boiler and gradually irrigates, and not necessarily simultaneously, the exchanger elements (1).

It therefore turns out that the heat transfer fluid flow will start in the exchanger element where the heat exchange will have been the fastest! (in this case, the valves all have the same opening instruction).

As the temperature increases in the different exchangers (1), each of the valves (II) opens and thus allows a flow rate suitable for local heat exchange in all the exchanger elements (1) equipped with said thermostatic valve. (11).

A variant is to be able to give an exchange priority scale to the heat exchanger elements by equipping them with thermostatic valves with different setpoints (for example, one opens at 60 ° C, another at 65 ° C, etc ... ).

The thermostatic valve (11) is positioned in the opening (10) of the exchanger element and is held in place by means of a centering device (12), lug or hole in the inner wall of the exchanger element (fig 3.1). The hose (or nut) abuts on the valve and holds it in place.

We also note the possibility of having an exchanger element (nest) (the last one if possible on the smoke path) not fitted with this thermostatic valve (11). This configuration makes it possible to maintain minimal circulation on the installation and prevents deterioration of the circulator. Likewise, this allows the last exchanger (nest) to operate in condenser mode if the heating returns are below the dew point, condensates (fig. 5 and 6) collected in the receptacle (20) and evacuated in (19) . It turns out that the boiler outlet temperature will change over a wide range of temperatures, from the return temperature of the heating circuit to the weighted average temperature of the thermostatic valves (11) open.

Another possibility is to have all the heat exchanger elements of the heating body equipped with the thermostatic valve and to have, between the return collectors (3) and the departure (4) a pipe (26) flexible or not, (this bypass is included in the construction of the boiler). This diagram allows operation at very low temperatures.

Conversely, if none of the exchanger elements has a thermostatic valve, it is possible to condense on all the elements provided that the temperature of the fluid is sufficiently low (and that the boiler is equipped with a casing (20) condensate collection).

Another configuration makes it possible to have traditional exchanger elements (fig. 5), connected to each other by niples (13) which provide the hydraulic connection from one to the other of the elements (1). A thermostatic valve (11) can be inserted in one of the niples (13), preferably on the starting route and thus allows the delay in irrigation of the elements concerned.

These construction schemes differ from the classic scheme of current very low temperature steel boilers, because the latter have a direct heat exchange between the primary and secondary circuit internally with a primary circuit which ensures heat exchange with the burner flame on the entire length of the fireplace.

Boiler returns and departures have isolation valves (16) and (17) which allow draining (18) of the boiler without having to drain the entire installation
The taps (16) and (17j are useful for preventing frost. Indeed, on the manifold leaving the boiler is an opening (15) on which is fixed, in a removable manner, a plug (or a trap Currently, when you want to add an additive (anti-freeze for example) to the circuit, it is often necessary to drain the installation and introduce (in current boilers), in a way often impractical,
The additive which will dilute with the water already present in the circuit.

With this opening (15) at the top point of the boiler (on the manifold or on the element itself), it suffices to close the two taps (16 and 17) and to empty the boiler through the tap (18). When the boiler is empty, the cap (15) is opened and the additive is introduced through the opening, a liquid which will therefore be found in the bottom collector (3) by gravity, via the exchanger elements (1). After closing (15), the isolation valve (16) is placed at the lowest point (the return in general), the boiler is filled from bottom to top by residual pressure of the water in the heating circuit (I the air escapes through the automatic air vent) and thus avoids air leakage in the pipes and the bleeding of the radiators which generally follows.The isolation valve (17) on the high point of the boiler (flow) is reopened, circulation in the boiler resumes its normal cycle, general water topping up can be carried out if necessary.

It is also possible, due to the isolation of the boiler by the taps (16 and 17) to fill in addition by the opening (15) (plug removed) the heating body, the water descending into the lower collector (3).

There may be on the top collector (4) or on the element itself a safety thermal switch (14) at the start of the exchanger elements (1), in the event of a failure of the heat-deformable element . A leak rate exists to avoid the formation of an air pocket in the element.

Another characteristic of this boiler is to have insulators (2) at the end of removable paths, and not integral with any element of the construction. This solution allows rapid change of the insulation (2) when it is damaged. It is by tightening the tie rods (5) that the parts (6) and (7) (or the envelope) come to press the insulators (2), and thus ensure the tightness of the smoke circuit (we note that the tie rods ( 5) can support the elements (1) by hooks (10)). These insulators (2) can simply be supported by the tie rods (5) located in the lower part (fig. 4.1)
This boiler has the particularity, apart from its multiple construction arrangements, to be able to receive (fig. 4) a domestic hot water tank (23) placed above the heating body, without resting on it. Indeed, an advantageous construction method (fig. 4), by fitting the boiler on the basis of two uprights (24) brackets (vertical uprights which can be telescopic) allows to hang a wall balloon (23) (standard or no) on these (25).

This feature makes it possible to fix, above the boiler and not on the wall, an electric sanitary hot water tank (or dual energy), which helps to save space in the boiler room and standardize the product.

These brackets allow the maintenance of the bottom plate (7) and, by fitting a tube (25) (preferably square) the support of the domestic hot water tank (23). This therefore makes it simple to add a balloon.

Claims (9)

 I - Boiler with circulation of fluid and with liquid, gaseous, solid fuel or electrical energy and such that the heating body is constituted by juxtaposition of several exchanger elements, and characterized in that at least one of these exchanger elements (1 ) includes a thermostatic valve (11). 2 - Boiler according to claim 1 and such that the heating body is constituted by several exchanger elements assembled by nipples, and characterized in that at least one of these nipples (13) comprises a valve (11) thermostatic. 3 - Boiler according to any one of the preceding claims and characterized in that at least one exchanger element has a device for centering the thermostatic element (11), device produced by cavity or lug (12) on the inner wall of the exchanger element. 4 - Boiler according to any one of the preceding claims and characterized in that each element.exchanger outlet fitted with a thermostatic valve (11) can be controlled by a safety temperature contact (14). 5 - Boiler according to any one of the preceding claims, having a thermal insulation between the heating body and the end walls and characterized in that this insulator (5) is removable and not integral with any building element of the boiler . 6 - Boiler according to any one of the preceding claims and characterized in that it can receive two uprights (24) brackets which allow the support of a tank (23) of domestic hot water, bases of the uprights (24) on which the boiler (Ic) is installed. 7 - Boiler according to claim 6 and characterized in that the uprights (25) of the balloon supports can be attached by fitting or fixing on the brackets (24) existing supports. 8 - Boiler according to any one of the preceding claims and characterized in that the flow manifold has a closable opening on its upper part allowing filling from above the heating body. 9 - Boiler according to any one of the preceding claims and characterized in that at least one of the exchanger elements has an opening (15) closable on its upper part allowing filling from above the heating body.