STEAM GENERATOR

Abstract: A steam generator primarily intended for intermittent operation comprises a body (1), in which a water-conducting passageway (3) and hollow spaces (8, 9, 10) for electric resistance elements (7) are located. According to the invention, the body (1) is cylindric and homogenous, and said passageway is located axially and symmetrically, from which passageway one or more radial passageways (4, 5) extend out of the body (1). The body (1) is externally provided with a heat insulating material (11), which is enclosed in a casing (12) of a material, at least the inner surface of which is reflective.

Description: Steam'-generator This invention relates to a steam generator intended to generate steam, for example,for dish washers in hospitals and industrial premises. 5 At dish washers, for which high temperatures are desired, steam is used by injecting it into the device in quest¬ ion. The present invention primarily relates to small-size dish washers and disinfection apparatuses of the type use"d, for 0 example,in nursing departments in hospitals. One problem with known steam generators for this purpose lies in their intermittent operation. After having been in use, a period of several hours may pass before it is used again. At present, therefore, maintenance heat is used for hold¬ ing hot water available all the time. According to calc¬ ulations, of the energy consumption for a water heater for said purpose up to about β0% is used for maintaining water hot during periods in which hot water is not in demand. The reason why water is maintained hot is, because it takes an unacceptably long time to heat water from room temperature until the necessary amount of hot water at the required temperature is produced. The present invention solves the aforesaid problem. The present invention, thus, relates to a steam generator, • which is primarily intended for intermittent use, and which comprises a body, in which a water-conducting " passageway and hollow spaces for electric resistance elements are located, and which is characterized, in that the body is cylindric and homogenous, that said passageway is * located axially and s-.ymetrically, and one or more radial passageways extend therefrom out of the body, and that the body externally is provided with a heat insulating material, which is enclosed in a casing of a material, of which at least its inner surface is reflective. OΛ1PI Yλ, The invention is described in greater detail in the foll¬ owing, with reference to the accompanying drawing, in which an embodiment of the invention is shown by way of example, and in which Fig. ' l is-a longitudinal section of a steam generator according to the invention, and fig. " 2 is a cross-section along the line A-A in Fig. 1. In Fig. 1 a steam generator according to the invention is given the general designation 1 and comprises a body 2 with a water-conducting passageway 3 extending axially therein. One or more radial passageways 4,5 are provided to conduct steam out of said body 1 as indicated by the arrows 6. Electric resistance elements 7 of cylindric shape are inserted in expedient hollow spaces 8,9,10 in the body 1, which hollow spaces are located in parallel with the axial passageway 3. Said body 1 is homogenous and made of a material with good thermal conductivity, preferably aluminium. The body 1 is externally provided with a heat insulat- ing material 11, which is enclosed in a casing 12 of a material, at least the inner surface of which is reflect¬ ive. According to a preferred embodiment, the heat insul¬ ating material is mineral wool. The casing 12, according to a preferred embodiment, is made of aluminium sheet metal. The heat insulating material has a substantial thickness, i.e. of the same magnitude as the radius of the body 1. The steam generator operates as follows. The body 1 is heated by means of the resistance elements to a temperature above the steam-forming temperature for water, for example 120 C-200 C, but temperatures even up to 300 C can be of interest. When the body has assumed a temperature of about l6θ°C, cold water is led into the passageway 3, as indicated by arrow 13, by action of a magnet valve 14, which also can act as a stop valve. The water is vaporized via a nozzle 15 and a lime filter and flows out as steam through the passageways 4,5. The nozzle 15 is provided to atomize the water before its vaporization. According to a preferred embodiment, a device for atomiz¬ ing the water consists of a nozzle, which extends along at least the greater part of the length of the passageway 3 and sprays atomized water against the walls of the pass¬ ageway 3- The extended nozzle (not shown) according to one embodiment comprises a pipe coaxial with the passage¬ way 3 and provided with a great number of small apertur¬ es in its shell surface. The number of apertures and their location are adjusted so that the water is distributed uniformly against the passageway walls. The apertures have a small diameter, preferably below 1 mm,whereby each aperture atomizes the water penetrating outward there¬ through. The pipe is located radially spaced from the passageway walls. The outer diameter of the pipe 3 of course, is smaller than the inner diameter of the pass¬ ageway and can be about half said diameter. The extended nozzle is connected to the passageway 3 in the same way as the nozzle 15 shown. As a result thereof, the greater part or all of the walls of the passageway 3 is met by atomized water, which is instantaneously vaporized. Therefore, between the extended nozzle and the passageway wall water in liquid state is present only to a very small extent or not at all. The length of the body may be, for example, 400 mm, its diameter 120 mm, and the insulation layer may have a thickness of 0 mm. The body, at such an embodiment, can be heated from room temperature to a temperature of 300 C in about 30 min- utes.by choosing a suitable effect of the resistance elements. When the body has been heated to a temperat¬ ure of 120 C to iβO C, the body cools during a normal working day, without energy supply, only to 70°C to 8θ°C, owing to the heat insulating material 11 and casing 12. The great advantage is to be seen in the fact that the body is maintained relatively warm, although the resist¬ ance elements 7 are not switched on. This implies, that the body can be heated from 70°C to 120-lβ0°C in about 30 seconds and thereby produce steam. These properties are utilized in such a way, that the body is heated at the beginning of a working day, for example, to 300 C, and the resistance elements are then switched off. When thereafter steam is desired, the resistance elements must be switched on only for a short period, for example 30 seconds, in order to obtain steam. The steam generator according to the present invention, thus, is extremely well suitable for intermittent use, especially for the purposes referred to above in the introductory portion, because it requires additional energy supply substantially only during the steam prod¬ uction periods. The steam generator, of course, can be designed in a way different of that shown at the above embodiment. The invention, thus, must not- be regarded restricted to this embodiment, but can be varied within the scope defin¬ ed in the attached claims.

Claims: Claims 1. A steam generator primarily intended for intermitt¬ ent operation, comprising a body (1), in which a water- -conducting passageway (3) and hollow spaces (8,9,10) for electric resistance elements (7) are located, c h a r ¬ a c t e r i z e d i n that the body (1) is cylindric and homogenous with said passageway (3) axially and symmetrically positioned therein, from which passageway one or more radial passageways (4,5) extend out of the body (1), and that the body (1) externally is provided with a heat insulating material (11), which is enclosed in a casing (12) of a material, at least the inner surf¬ ace of which is reflective. 2. A steam generator as defined in claim 1, c h a r - a c t e r i z e d i n that the heat insulating mat¬ erial (7), which preferably is mineral wool, is enclos¬ ed in a casing (12) of aluminium sheet metal. 3. A steam generator as defined in claim 1 or 2, c h a r a c t e r i z e d i n that said electric resistance elements (7) are cylindric and located in said hollow spaces (8,9,10), which extend in parallel with said axial passageway (3). 4. A steam generator as defined in claim 1, 2 or 3, c h a r a c t e r i z e d i n that a nozzle (15) is located in said passageway (3). 5. A steam generator as defined in claim 4, c h a r ¬ a c t e r i z e d i n that the nozzle consists of a pipe located in the passageway (3) along at least the greater part of the length of the passageway (3) and radially spaced from the walls of the passageway (.3), which pipe is provided with a great number of small apertures for effecting a uniform spray of atomized wat¬ er against the passageway walls.

Inventors: HOEGFELDT CARL-ERIK, HOEGFELDT, CARL-ERIK (DECEASED)
Applicants: ACELA PUMP AB, HOEGFELDT BIRGITTA LEGAL REPRE, HOEGFELDT, BIRGITTA (LEGAL REPRESENTATIVE OF HOEGFEL
Application year: 1983
Main classification: F22B1
IPC codes: F22B1