WO1989008227A1 - Central heating system with arrangement and application for eliminate oxygen from water - Google Patents

Abstract

A central heating installation for heating rooms in buildings comprising a boiler for heating water and pumping means for driving the heated water from the boiler through flow conduits and heat emitting radiators, which at least partially are made of iron or steel, and back to the boiler. To prevent corrosion of the iron and steel components of the installation, as well as loss of substance and resulting sludge generation, the installation is furnished with a dosage device (B, D) for the supply of hydrogen to the water in sufficient quantities to reduce the amount of dissolved oxygen contained in the water reaction, preferably in the presence of a catalyzer (K), with the hydrogen producing water, to a level at which said corrosion and sludge generation to a large extent is prevented. The dosage device is made up of a hydrogen container (B) for appropriate dosing of hydrogen via a nozzle valve (D) into a flow conduit (S) of the installation, and the hydrogen container (B) being dimensioned in such a way that the quantity of hydrogen supplied to the water, within an adequate safety margin, never can be so large that explosion hazardous free hydrogen may exist within the installation, even if the total amount of hydrogen in the container is let out at the same time.

Description

Central heating system with arrangement and application for eliminate oxygen from water.

This invention relates to central heating installations for heating rooms in buildings and, in particular, to means for avoiding corrosion or sludge generation by iron or steel components in the installation. The causes of these un¬ favourable damages are well known, namely the fact that oxygenous water attacs the said materials. The loss of substance from pipes and radiators can be substantial, which may lead to penetrating pitting and leakages, and also to the generation of magnetite sludge (Fe2θ4) depositing in radiators, radiator valves and similar parts. By then, these circumstances usually result in interrupts to the operation and reduced performance of the installation. In turn this gives rise to increased capital and operational costs.

Therefore, it is obviously important to prevent oxygen from entering the flow system, but there will always be a loss of water, and even in properly operated installations there may be a monthly loss of about 1 - 2 % of the installation volume. The replenishment to compensate for the water loss is nearly always done with unprepared water from the mains water supply, which, as a rule in this country (Norway) , is surface water and hence contains a lot of dissolved oxygen.

However, experience has shown that if the water loss is no higher than that mentioned above (1 - 2 % per month) , the corrosion, to some reasonable extent, may be kept in check. Then the amount of oxygen entering during replenishment is so small that it reacts with the ferruginous components and creates sludge and some corrosion locally (usually at the boiler where the replenishment takes place) .

On the other hand, it is evident that in installations requiring large replenishments, corrosion and sludge generation take place to a considerable extent in connection with components of iron. This is also the case in installa- tions with open expansion vessels, and when plastic tubes that do not prevent diffusion, are being used. This is the case with most types of plastic tubes used in central heating installations, and therefore the use of such tubes does not resolve the problems of corrosion and sludge at the ferru- genious components that still are present in the installa¬ tion.

On this basis, an object of this invention is therefore to overcome the problems described above and to provide a central heating installation of the type indicated above, in which the oxygen contents of the circulated water lies far below the values mentioned above, thus ensuring corrosion- and sludgeless operation of the installation.

Thus, the invention relates to a central heating installation for heating rooms in buildings comprising a boiler for heating water and pumping means for driving the heated water from the boiler through flow conduits and heat emitting radiators, which at least partially are made of iron or steel, and back to the boiler.

On this background of fundamentally known prior art, the installation according to the invention, has the unique feature of comprising dosage means for supply of hydrogen to the water in sufficient quatities to reduce the amount of dissolved oxygen in the water through reaction with said hydrogen to produce water, to a level at which no substantial loss of substance from said iron or steel can take place by corrosion or sludge generation, but not in such large quantities that explosion hazardous free hydrogen may appear within the installation.

Preferably, the dosage means is disposed for supplying hydrogen to the flow conduit form the boiler to the radia¬ tors, and a catalyzer is disposed in the water in the downstream direction from the place of the hydrogen supply. To the purpose, the dosage means may comprise a hydrogen container and a nozzle valve disposed for opening and closing automatically or manually according to a predetermined programme for discharge of a given quantity of hydrogen into the water.

Since the quantity range for the supply of hydrogen to the water, as quoted above, is quite broad, and thus the hydrogen contents present in water at any time not being critical, the dosage means may be made quite simple, and continuous and exact monitoring of the hydrogen discharge will be super¬ fluous. To ensure that the upper limit of the amount of hydrogen in the water, as given above, is not exceeded after all, the hydrogen container, according to the invention, by preference is dimensioned so that the quantity of hydrogen added to the water, within an adequate safety margin, never can be so large that said explosion hazardous free hydrogen may exist within the installation, even if the total amount of hydrogen in the container is let out at the same time through the nozzle valve into the water.

However, since the quantity of hydrogen required to ensure a corrosion- and sludgeless installation is extremely small, such a dimensioning does nevertheless not imply that the hydrogen container needs to be exchanged more often than at intervals of one or more months.

Below the invention is explained is greater detail by way of an embodiment example and by reference to the attached drawning, showing only one figure, namely that of a dosage means for supplying hydrogen to a central heating installa¬ tion according to the invention.

The drawing, shows a section S of the flow conduit carrying water from the boiler (not shown) to the heat emitting radiators (not shown) in a central heating installation according to the present invention. A catalyzer K, preferably of the kind in which palladium makes up the active ingredient, is disposed in this section S of the flow conduit. At the inlet side of the catalyzer the heated water from the boiler runs through a filter F and, between the filter and the catalyzer, a dosage means is coupled to supply doses of hydrogen into the section S of the flow conduit. This dosage means is made up of a hydrogen container B, connected through a dirigible nozzle valve to the flow conduit. The nozzle valve is controlled by a concentration controller C by means of a motor M, and this controller receives control signals from av concentration gauge T coupled to the flow conduit at the outlet side of the catalyzer K. Thereby this concentration gauge senses the contents of dissolved oxygen in the running water in the flow conduit S and issues corresponding control signals via the line L to the concentration controller C. In turn, by means of the motor M, the controller C will provide for the opening and closing of the nozzle valve D in accordance with the received control signals, so that the dosage of the hydrogen to the running water in the flow conduit S takes place on the basis of the sensed oxygen contents of the water at the outlet side of the catalyzer and in accordance with a predetermined control pattern.

Thence, this control sees to that, at any time, the amount of dissolved oxygen in the water by reaction with hydrogen producing water, lies below a level at which no substantial loss of substance can take place by corrosion or sludge generation. At the same time the control sees to that, within an ample safety margin, such large quantity of hydrogen never is being dosed as to make explosion hazardous free hydrogen occur in the installation. Since the quantity range for the appropriate hydrogen supply to the water is quite broad, and thus hydrogen dosage not being critical, it is in many cases not necessary to have the above mentioned closes loop control and considerably simpler equipment for the supply of hydrogen may be employed, by omitting the control loop T, L, C. The nozzle valve D may possibly be opened and closed by a timing control, via the motor M, according to a suitable predeter¬ mined timing programme, or it may possibly be opened and closed manually by an operator reading the oxygen concentra¬ tion in the water from an indicator R at the outlet side of the catalyzer and also reading the pressure in the hydrogen container from a pressure indicator P.

To ensure the upper limit for the amount of hydrogen in the water, as noted above, never to be exceeded, the hydrogen container may be dimensioned in such a way that even if the total contents of hydrogen in the container unintentionally should be let out at the same time into the water, the amount of hydrogen in the water would not be so large that explosion hazardous free hydrogen appears within the installation. However, since the quantity of hydrogen needed to neutralize the amount of dissolved oxygen existing in the water, usually is very small, the hydrogen container may still take a size sufficient to allow the hydrogen container be exchanged at fairly long intervals, e.g. one or more months.

In a central heating installation according to the present invention, the oxygen contents of the water may be kept at a level which is far below that which is usual with common installations, where 1 - 2 % of the water is replenished every month. While the 02~level in common installations is in the range of ppms (parts per million) , it may be brought down to about 2 ppbs (parts per billion) in an installation in accordance with the invention.

Claims

PATENT CLAIMS

1. A central heating installation for heating rooms in buildings comprising a boiler for heating water and pumping means for driving the heated water from the boiler through flow conduits and heat emitting radiators, which at least partially are made of iron or steel, and back to the boiler, the installation also comprising means of reducing the oxygen contents of the water by feeding hydrogen into the water in a flow conduit (S) leading from the boiler to the radiators, and a catalyzer (K) disposed in the downstream direction from the place of the hydrogen supply to the water, c h a r a c t e r i z e d in that said means is made up of dosage means comprising a concentration gauge (T) disposed for sensing the oxygen contents of the water at the down¬ streams side of the catalyzer ( ) , and also a concentration controller (C) disposed for opening and closing a nozzle valve (D) according to the sensed oxygen contents of the water by said gauge, said nozzle valve being included in a gas pipeline between a hydrogen container (B) and the flow conduit to which the hydrogen is supplied, and set so that hydrogen is fed to the water in sufficient quantities to reduce the amount of dissolved oxygen in the water through reaction with said hydrogen to produce water, to a level at which no substantial loss of substance from said iron or steel can take place by corrosion or sludge generation, but not in such large quantities that explosion hazardous free hydrogen may appear within the installation.

2. A central heating installation according to claim 1, c h a r a c t e r i z e d in that the hydrogen container (B) is dimensioned in such a way that the quantity of hydrogen supplied to the water, within an adequate safety margin, never can be so large that said explosion hazardous free hydrogen may exist within the installation, even if the total amount of hydrogen in the container is let out at the same time through the nozzle valve (D) into the water.

3. A central heating installation according to claims 1 and 2, c h a r a c t e r i z e d in that the catalyzer (K) is a metal in group VIII of the periodic system, e.g. palladium.

4. Use of means for the supply of hydrogen into water in conjunction with central heating installations for heating rooms in buildings and having of a boiler for heating water and pumping means for driving the heated water from the boiler through flow conduits and heat emitting^• radiators, which at least partially are made of iron or steel, for the purpose of reducing the oxygen contents of the water by feeding hydrogen into the water in a flow conduit (S) leading from the boiler to the radiators, and in cooperation with a catalyzer (K) disposed downstream of the hydrogen supply input, to promote the reaction of the hydrogen with the oxygen contents of the water, producing water and hence reducing the corrosion of said iron or steel.