GB1603662A - Steam heated boilers - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO STEAM HEATED BOILERS (71) We, A. WILSON A/S, a company organized under the law of Denmark, of Soren Nymarksvej 19, DK 8270 Hoejbjerg, Denmark, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a steam heated boiler or a similar device.There is known a steam heated boiler comprising a treating chamber and, arranged in heat exchanging connection therewith, a substantially closed steam chamber having a boiling chamber in which heating means are provided for periodically causing a liquid in said boiling chamber to boil for supplying steam to said steam chamber, the steam chamber having adjacent its upper end a so-called steam valve, i.e. an air escape valve which is automatically closed by the occurrance of substantially pure steam therein, and moreover provided with a suction actuated air inlet valve which can be combined with said steam valve.Such boilers may take the form of commercial kitchen vessels, also known as kettles, of the type surrounded by a steam jacket, which is bottomwise in open connection with the said boiling chamber, in which is contained an amount of water and provided electric heating means, commonly a set of electrodes operable to heat and boil the water by current transmission through the water, whereby the generated steam ascends in the steam jacket to thereby heat the treating chamber of the kettle.

Normally such kettles are not used constantly, i.e. between their periods of use they are allowed to cool down to ambient temperature, whereby a vacuum is liable to be created inside the jacket; however in order to avoid such a vacuum the kettle is provided with a pressure equalization valve enabling air to be sucked into the jacket space while not generally allowing steam at overpressure to escape therefrom. On the other hand air escape valve means should be provided in order to enable the air in the jacket space to be exhausted each time the kettle is "started", since as well known the generated steam will not show the desired heating effect on the kettle as long as air is present in the jacket space.

Such air escape valves are well known in the art. They remain open as long as the outflowing medium consists mainly of air and close when it consists mainly or entirely of steam. This involves, however, that by each start of the heating of the kettle a certain volume of steam will escape before the air escape valve closes, and this in its turn means that upon a series of starts and stops of the operation of the kettle a considerable portion of the water in the lower water chamber will have disappeared.

Especially in connection with boiling kettles of the type in which the water heating means are constituted by electrodes operating to send a heating current directly through the water it is important that the water level in the water chamber be kept constant, and the said escape of steam, therefore, is disadvantageous in that from time to time it will require refilling of water into the water chamber in a well defined manner in order to reestablish the ideal water level therein.

Moreover, the water used should normally be specially prepared so its loss represents an expenditure, too.

It is the purpose of this invention to provide a device of the type referred to, in which the water shall not have to be frequently supplemented, i.e. which may operate during a long period of time by means of a preadjusted volume of preferably purified water not giving rise to problems as to precipitation of chalk or other minerals.

According to the present invention there is provided a steam heated boiler compris ing a treating chamber and, arranged in heat exchanging connection therewith, a substantially closed steam chamber having a boiling chamber in which heating means are provided for periodically causing a liquid in said boiling chamber to boil for supplying steam to said steam chamber, the steam chamber having valve means arranged to permit escape of air from a position adjacent the upper end of the steam chamber, and to close automatically when substantially pure steam is escaping therethrough, and said valve means also being arranged to allow air to enter the steam chamber in response to suction therein, and wherein the valve means is connected with a steam condenser for air escaping from the steam chamber to flow through the condenser and for condensate in the condenser to be returned to the steam chamber when air enters the steam chamber, the condenser including a network structure filling of material having good thermal conductivity and capacity and through the passages of which the air flows, whereby the condenser has sufficient condensing capacity to effect condensation of substantially all steam leaving the steam chamber through initial boiling up of the liquid.

Thus, with the boiler according to the invention the escaping steam is condensed and later returned as water, whereby the direct loss of water will be eliminated or at least be so small that refilling of water will be necessary only with very long intervals of time.

In the following the invention is described in more detail with reference to the accompanying drawing, in which: Figure I is a general side view, partly in section, of a boiler according to the invention, and Figure 2 is a detailed view of a preferred condenser arrangement on the kettle.

The boiler or kettle shown in Figure 1 is designated 2 as a whole. It comprises in conventional manner a kettle element 4 defining a treating chamber and mounted inside a jacket element 6, the latter being connected by welding to the kettle element 4 along an upper edge portion 8. A cylindric steam chamber or space 10 is formed between the outside of the kettle element 4 and the inside of the jacket 6, and underneath the kettle element this space is in open connection with a boiling chamber 12 including a boiler unit 14 in which electrodes are provided for heating an amount of water contained in the boiler chamber 12. All this being well known in the art it is deemed unnecessary to describe the arrangement in more detail. The kettle shown is of the tiltable type provided with opposed aligned tilt shaft portions 16 to be received in bearings of support posts (not shown).

Adjacent the top of jacket 6 there is mounted a valve 18 which acts as an air escape valve and as an air inlet valve. When the operation of the boiler unit 14 is started steam is generated, and the steam rises into the steam space 10, forcing air through the air escape valve 18. This valve, e.g. type "Spirax AV 10", is so adapted that it closes when it is subjected to an outflow of concentrated steam, i.e. when practically all air has been driven out from the steam space 10, whereafter the kettle is in real operation. Normally, however, some steam in admixture with air will have left through the valve before it closes, whereby the said loss of water is induced.

When this operation of the boiling unit 14 is stopped the steam generation will stop, and by natural cooling a vacuum will be created in the steam space 10, and the valve 18 opens so as to allow for introduction of external air into the steam space.

The outlet from the valve 18 to the atmosphere is let through a condenser 20 which is shown in more detail in Figure 2.

The condenser is a cylindric container mounted underneath the valve 18 and having one or more holes 22 adjacent its top end. The outlet opening of the valve 18 is connected with a tube 24 projecting into the condenser 20 to near the bottom thereof.

Outside the tube 24 (or even additionally inside the tube) is provided a loose filling consisting of small pieces 26 of sheet material of stainless steel.

When steam laden air is exhausted through the valve 18 prior to the closing thereof, in connection with each operational start of the kettle, the steam will condense on the walls of the tube 24 and condenser 20 as well as on the sheet pieces 26, these acting to ensure that all portions of the air/steam flow will meet a relatively cold material surface portion. Thus, the air will leave the condenser through the outlet 22 in a relatively dry condition, and the condensed water will be collected in the bottom portion of the condenser 20, as shown at 28.

At least after some starting periods the condensed water, seeping down to the condenser bottom even upon closing of the valve 18, will adopt a level above the lower end of the tube 24. When the boiling operation is stopped and the said vacuum is created inside the jacket 6 the water in the condenser bottom will be sucked into the jacket space through the tube 24 and the valve 18, and at least after some operation cycles (or if water is added beforehand in the condenser) an equilibrium will be obtained whereby during each starting period an amount of condensed water will be supplied to the condenser which is the same as the amount which is sucked from the condenser back to the jacket space by each stop of the kettle operation.

The condensed water should not necessarily be sucked upwardly through a tube 24, since the bottom portion of the condenser may be connected with the jacket space in a direct manner through a separate air inlet pipe including a check valve. Alternatively, by way of example, the outflow from the valve 18 can be directed upwardly through a condenser unit, whereby the water condensed therein will automatically return to the jacket space, part of it perhaps even before the valve 18 closes and the rest immediately upon the re-opening of the valve at the end of the operation period.

Generally the condenser should not need active cooling in order to condense the restricted amount of steam leaving the kettle before the valve 18 closes, but it will be within the scope of the invention, of course, to arrange for active cooling of the condenser.

A condenser 20 and a suitable water return pipe may even be arranged in connection with the pressure safety valve normally used with kettles of the type in question. It is customary to test the safety valve by lifting it manually from time to time, as at these accasions some steam will leave the kettle through the valve.

WHAT WE CLAIM IS: 1. A steam heated boiler comprising a treating chamber and, arranged in heat exchanging connection therewith, a substantially closed steam chamber having a boiling chamber in which heating means are provided for periodically causing a liquid in said boiling chamber to boil for supplying steam to said steam chamber, the steam chamber having valve means arranged to permit escape of air from a position adjacent the upper end of the steam chamber, and to close automatically when substantially pure steam is escaping therethrough, and said valve means also being arranged to allow air to enter the steam chamber in response to suction therein, and wherein the valve means is connected with a steam condenser for air escaping from the steam chamber to flow through the condenser and for cond nsate in the condenser to be returned to the steam chamber when air enters the steam chamber, the condenser including a network structure filling of material having good thermal conductivity and capacity and through the passages of which the air flows, whereby the condenser has sufficient condensing capacity to effect condensation of substantially all steam leaving the steam chamber through initial boiling up of the liquid.

2. A boiler according to claim 1, wherein the network filling consists of metal sheet pieces.

3. A steam heated boiler substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. each stop of the kettle operation. The condensed water should not necessarily be sucked upwardly through a tube 24, since the bottom portion of the condenser may be connected with the jacket space in a direct manner through a separate air inlet pipe including a check valve. Alternatively, by way of example, the outflow from the valve 18 can be directed upwardly through a condenser unit, whereby the water condensed therein will automatically return to the jacket space, part of it perhaps even before the valve 18 closes and the rest immediately upon the re-opening of the valve at the end of the operation period. Generally the condenser should not need active cooling in order to condense the restricted amount of steam leaving the kettle before the valve 18 closes, but it will be within the scope of the invention, of course, to arrange for active cooling of the condenser. A condenser 20 and a suitable water return pipe may even be arranged in connection with the pressure safety valve normally used with kettles of the type in question. It is customary to test the safety valve by lifting it manually from time to time, as at these accasions some steam will leave the kettle through the valve. WHAT WE CLAIM IS:

1. A steam heated boiler comprising a treating chamber and, arranged in heat exchanging connection therewith, a substantially closed steam chamber having a boiling chamber in which heating means are provided for periodically causing a liquid in said boiling chamber to boil for supplying steam to said steam chamber, the steam chamber having valve means arranged to permit escape of air from a position adjacent the upper end of the steam chamber, and to close automatically when substantially pure steam is escaping therethrough, and said valve means also being arranged to allow air to enter the steam chamber in response to suction therein, and wherein the valve means is connected with a steam condenser for air escaping from the steam chamber to flow through the condenser and for cond nsate in the condenser to be returned to the steam chamber when air enters the steam chamber, the condenser including a network structure filling of material having good thermal conductivity and capacity and through the passages of which the air flows, whereby the condenser has sufficient condensing capacity to effect condensation of substantially all steam leaving the steam chamber through initial boiling up of the liquid.

2. A boiler according to claim 1, wherein the network filling consists of metal sheet pieces.

3. A steam heated boiler substantially as herein described with reference to the accompanying drawings.