The present invention relates to a combined boiler which can be switched between supplying hot water and steam.

Within industry, there may at times be a need for the supply of both hot water and steam. Normally, this is not a simultaneous need, as the usual need is hot water for heating premises, for example, while only occasionally and for short periods of time may there be a need to supply steam for specific purposes. Several solutions are known to achieve this, e.g. to use two separate boilers for each use, or to use a steam boiler with subsequent heat exchanger to supply hot water. However, such solutions have all their limitations and often involve complicated construction solutions.

The present applicant thus has a Norwegian patent NO332323 which describes a boiler which can be converted between supplying hot water and steam. The boiler is used in supply vessels of ORO class where there is a need for hot water for general heating in the vessel, but where the vessel must also have a system in readiness to be able to supply steam for collecting oil spills. This is an element boiler that requires some time for conversion from delivery of hot water to steam and vice versa.

From GB 951747 a combined boiler is known which simultaneously delivers hot water and steam. The boiler comprises two separate hot surfaces for steam production and hot water production. These are linked together via a constantly open connection pipe.

KR 20200023724 describes a combined hot water and steam boiler which uses wastewater heat with improved energy power to produce steam, where a steam chamber is arranged on the outer side of a heating chamber in the form of a wrapper.

It is an object of the present invention to provide a combined boiler which can be easily and quickly converted from the supply of hot water to the supply of steam, which is compact and easy to maintain.

This is achieved with a boiler as stated in the following patent claims.

The boiler is an electrode boiler with separate outputs for hot water and steam. The electrode boiler is very easy to regulate and can be quickly switched between supplying hot water or steam and vice versa. The changeover between steam and hot water mode takes place completely automatically through a developed program code in the control system. In addition, the boiler is equipped with a source of nitrogen supply. This is used in hot water mode, while the nitrogen source is disconnected when the boiler is run in steam mode. The invention will now be described in detail with reference to the appended figure which is a schematic representation of a combined boiler according to the invention, with associated peripheral units.

The boiler is a high-voltage electrode boiler with separate outputs for steam and hot water, as well as a control system that both controls the changeover between steam and hot water mode, and which controls the boiler's production in each case.

The boiler itself consists of an outer container 1 with an inner vessel or tank 2 mounted on insulators 3. The insulators also function as a manifold for supplying water to the vessel 2. Several electrodes 4 protrude into the vessel 2. The electrodes 4 are supplied with high voltage current via a conductor 5 from an external power supply.

The vessel 2 is supplied with water from a feed pump 6 which collects water from the bottom of the outer container 1 with the outlet pipeline 7 and delivers the water to the vessel 2 with the intake pipeline 8 and the insulators 3, either directly through the first valve 10 (steam mode) or via a heat exchanger 12 through second and third valves 11a, lib arranged on the primary side of the heat exchanger (hot water mode). The amount of water in the vessel 2 regulates the performance of the boiler and decides whether it should supply hot water or steam. The performance and mode are controlled by the control system 9 by regulating the speed of the pump 6.

Hot water is taken out from the secondary side of the heat exchanger 12, while there is a corresponding outlet for steam from the vessel 1 via a fourth valve 13. There is also a source 14 for supplying nitrogen (in hot water mode) via a fifth valve 15. All the said valves are equipped with electric actuators, for example solenoids or motors, so that they can be controlled from the control system 9.

If the boiler is to supply hot water, the control system 9 will regulate the opening of the first valve 10, regulate the opening of the second valve 11a and open the third valve lib fully, close the fourth valve 13 and supply nitrogen to the container 1 to create the necessary overpressure by opening the fifth valve 15. The level of water in the vessel 2 is regulated with the pump 6 so that the water is heated without boiling. The control system 9 is arranged to regulate the opening of the first valve 10 according to the heat demand on the secondary side of the heat exchanger 12 in proportion to the second valve 11a.

If the boiler is to supply steam, the first valve 10 is opened, the second and third valves 11a, b are closed, the fourth valve 13 is opened while the fifth valve 15 is closed. The level of water in the vessel 2 is regulated so that steam is produced, and heat delivered is regulated by measuring the pressure in the container 1 and adjusting the water level in the vessel 2 accordingly. The system can thus supply a varying amount of steam. Transition from one mode to another takes place by the control system 9 sequentially opening and closing the relevant valves and controlling the performance of the pump 6.