GB2215640A - Magnetic separators - Google Patents

Abstract

A magnetic separator for separating black iron oxide from water circulating in a flow system such as a central heating system or a chilled water system comprises a cylindrical chamber 16 downwards into which projects a tubular battle 18, one end of the armature 21 of an electromagnet being disposed in the bottom of the chamber. Water flows tangentially into the upper end of the chamber 16, downward about the baffle 18, radially inward past the end of the armature 21 and upward through the baffle 18 to an outlet. Valves 11 and 14 are provided in the pipes 10 and 13 connecting the inlet and outlet of the separator to the external flow circuit, and means is provided through which a known quantity of flushing water can be passed to remove oxide collected in the lower end of the chamber. <IMAGE>

Description

MAGNETIC SEPARATORS This invention relates to magnetic separators and is more particularly concerned with magnetic separators for separating black iron oxide entrained in water circulating in a fluid flow system, e.g. a central heating or chilled water system.

According to this invention there is provided a magnetic separator comprising a cylindrical chamber having adjacent one end thereof a substantially cylindrical baffle disposed coaxially within the chamber which baffle extends from one end of the chamber and terminates short of the other end of the #harnber, an inlet to the annular space surrounding the baffle which inlet is directed tangentially of the cylinder and is spaced from said other end of the chamber, an outlet from the cylinder space within the baffle which outlet is spaced from said other end of the chamber, an electromagnet at said other end of the chamber, and a valve-controlled drain passage opening to said other end of the chamber, whereby when the electromagnet is deenergised and flow through said drain passage is permitted by the valve, a flow of fluid from the chamber can flush away through the drain passage magnetic particles separated from the fluid by the electromagnet.

According to a preferred feature of the invention, the drain passage opens to the chamber coaxially therewith and extends centrally through the electromagnet.

According to another preferred feature of the invention there is provided a valve-controlled inlet for flushing fluid at the end of the space within the baffle remote from said other end of the chamber.

According to yet another preferred feature of the invention, the armature of the electrom#agnet is annular and has one end thereof welded in an aperture in a nonmagnetic end plate of the chamber, the other end of the armature being magnetically connected to a magnetic member which defines at least the end portion of the chamber adjoining said end plate.

One embodiment of the invention will now be described by way of example, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic illustration of part of a fluid flow system incorporating a magnetic separator according to the invention, and Figure 2 shows the magnetic separator of Figure 1 in axial section and on a larger scale.

Referring t tht drawings, a proportion of the full flow of water circulating in a fluid flow system e.g. a central heating or chilled water system is directed through a pipe 10 controlled by a solenoid valve 11 into a magnetic separator 12 and leaves the separator by way of an outlet pipe 13 controlled by a solenoid valve 14.

In passing through the separator black iron oxide entrained in the water is retained in the separator.

The separator 12 is shown in more detail in Figure 2 to which reference is now made. The separator is a hollow cylindrical body 16 defining a cylindrical space within it. The body 16 has an annular top wall 17 through which a tubular baffle 18 projects downward concentrically within the body 16 terminating a short distance above the lower end of body 16. The bottom end of body 16 has an outwardly directed bolting flange 19 welded to it. An annular gunmetal flange 20 having a rebate about the upper end of its central aperture has the upper end of the annular armature 21 of an electromagnet secured in the aperture by welding, an end flange 22 of the armature being accommodated in the rebate. The flange 20 and annular armature 21 jointly provide the bottom wall of the chamber and are secured to the flange 19 by nuts engaged on bolts 23 extending through the flanges 19 and 20.The lower portions of the armature 21 are encircled by the coil 24 of the electromagnet, and the coil is enclosed by a fabricated annular enclosing member 25 of inverted top hat form.

Bolts 23 extend through holes in the peripheral flange of the coil enclosing member 25 and have second nuts 26 engaged on them to secure the member.

Pipe 10 is directed tangentially of the body 16 so that the incoming water with entrained iron oxide particles flows downward in a spiral path between the body and the baffle 18, and the outgoing water flows upward thro the tubular baffle 18 and thence through the outlet pipe 13 of the system. The upper end of the tubular baffle is closed off by an annular plate 28 having welded to it the lower end of a pipe 29 leading downward from a tundish 30, see Figure 1. Pipe 29 contains a solenoid valve 31 and has connected to it below the valve a branch pipe 32 containing an automatic air vent valve 33.

A pipe 35 is connected to the lower end of the armature 21 and leads by way of a solenoid valve 36 to a collection tank 37 having a sampling connection 38 controlled by a manually operated valve 39, and an overflow pipe 40 leading via a tundish to a drain 41.

A pipe 44 containing a solenoid valve 45 is connected to the upper end of the space within the tubular baffle and permits make-up water to be fed into the separator. A dosing pump 46 may be arranged to feed rust inhibitors and other water treatment chemicals into a tank from which water is fed into the separator via pipe 44.

In normal operation of the apparatus, the coil 24 of the electromagnet is energised and all of the solenoid valves are closed except the inlet and outlet valves 11 and 14. Water flowing through the tangential inlet pipe 11 spirals downward about baffle 18, through the magnetic field adjacent the armature 21, upward through the baffle 18 and out through pipe 13.

A strong magnetic field is created between the flange 22 at one end of the armature 21 and the flange 19 and bottom portion of the tubular body 16and baffle 18, which are magnetically connected via magnetic member 25, and steel bolts 23 to the other end of the armature, and in consequence any iron oxide entrained in the incoming water becomes magnetically attached to one or other of the magnetised surfaces. After a selected time interval, valve li and 14 are closed, the electromagnet is de-energised, and valves 31 and 36 are opened. The water contained in the tubular baffle and body 16 flows out through pipe 35 into the collection tank 37 and carries with it the iron oxide which has collected in the region of the armature.An aperture 50 is provided in the tubular baffle at a point just below annular plate 17 to prevent any air-lock forming between the baffle and the body 16. When flushing is complete, valves 36 and 31 are closed and valve 45 is opened to enable the separator to refill with water from tank 47 to which the required additives are added via pump 46. Air in the separator chamber escapes through the automatic vent valve 33 as the chamber is refilled.

When refilling is complete, valve 45 is closed, the coil 24 of the electromagnet is energised, and valves 11 and 14 are opened to enable the system to be brought into operation again.

The illustrated apparatus is particularly advantageous allowing only the fixed volume of water contained between valves 11, 14 and 45 to be used for flushing away the iron oxide sludge so that the said fixed volume of water is the maximum that need be lost from the circulating water. Also a volume of make-up water and additives equal to the fixed volume is the maximum that needs to be added to the system after flushing, so keeping to a low value the amount of oxygen-containing water added to the system and the renewed capacity of the circulating water to form more iron oxide. The illustrated separator is also advantageous in having no fixing bolts or other nonwelded items in the part of flange 20 which seals the bottom of the chamber within the body 16, thus reducing the risk of leakage at this point.

The whole of the previously described operation is carrie@ out under the control of anelectronic timer/controller.

The separator can additionally be manually flushed and closed via tundish 30.

The purpose of collecting tank 37 is to provide a means of assessing the degree of black iron oxide corruption and thus provide a yardstick for setting the separator collecting time.

Claims (5)

1. A magnetic separator comprising a cylindrical chamber having adjacent one end thereof a substantially cylindrical baffle disposed coaxially within the chamber which baffle extends from one end of the chamber and terminates short of the other end of the chamber, an inlet to the annular space surrounding the baffle which inlet is directed tangentially of the cylinder and is spaced from said other end of the chamber, an outlet from the cylinder space iti te baffle which outlet is spaced from said other end of the chamber, an electromagnet at said other end of the chamber, and a valve-controlled drain passage opening to said other end of the chamber, whereby when the electromagnet is deenergised and flow through said drain passage is permitted by the valve, a flow of fluid from the chamber can flush away through the drain passage magnetic particles separated from the fluid by the electromagnet.

2. A magnetic separator as claimed in claim 1, wherein the drain passage opens to the chamber coaxially therewith and extends centrally through the electromagnet.

3. A magnetic separator as claimed in claim 1 or claim 2, wherein there is provided a valve-controlled inlet for flushing fluid at the end of the space within the baffle remote from said other end of the chamber.

4. A magnetic separator as claimed in any one of the preceding claims, wherein the armature of the electromagnet is annular and has one end thereof welded in an aperture in a non-magnetic end plate of the chamber, the other end of the armature being magnetically connected to a magnetic member which defines at least the end portion of the chamber adjoining said end plate.

5. A magnetic separator substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.