WO1988000673A1

WO1988000673A1 - Apparatus for adding water to fuel oil

Info

Publication number: WO1988000673A1
Application number: PCT/GB1987/000502
Authority: WO
Inventors: Stephen Goben
Original assignee: Stephen Goben
Priority date: 1986-07-15
Filing date: 1987-07-15
Publication date: 1988-01-28
Also published as: AU7704987A; GB2193347B; GB2193347A; GB8617241D0

Abstract

Apparatus for adding water to fuel oil comprises five flow control valves (6$i(a), 6$i(b), 6$i(c), 6$i(d) and 6$i(e) each comprising a needle valve (7) and a solenoid (8) operative to move the needle valve between open and closed positions. The flow control valves (6$i(a) to 6$i(d)) are each operative, when open, to deliver water at different flow rates in the ratio 1:2:4:8, specifically 5, 10, 20 and 40 litres per hour, whilst the flow control valves (6$i(e)) is operative to deliver water at a low flow rate of 5 litres per hour. The apparatus comprises an output device operative to generate an output signal proportional to the rate of flow of fuel oil in the burner system, the output signal being delivered to a flow control device (16, 18, 20, 22) which controls the solenoid (8) of the five flow control valves in accordance with the output signal.

Description

TitIe:"Appαrαtυs for adding water to fuel oil"

Suggestions have been made to add water to fuel oil prior to delivery thereof to a burner, this operation theoretically being capable of providing the following advantages:

(a) a reduction in fuel consumption;

5 (b) a reduction in the acid products of combustion;

(c) a reduction in stack emissions;

(d) a reduction in burner and associated equipment maintenance;

(e) an increase in burner flame temperature.

Difficulty is however encountered in carrying out this operation, in that I Q it is essential that water is delivered at an appropriate rate to a high degree of accuracy, and unless that accuracy is reliably maintained, damage may be caused.

According to this invention there is provided an apparatus for adding water to fuel oil comprising: | c (a) a plurality of flow control valves each operative selectively to control the flow of water to a burner;

(b) an output device operative to generate an output signal proportional to the rate of flow of fuel oil to the burner; and

(c) a control device operative to control the flow control valves in response o to the output signal.

Preferably the flow control valves are each selectively movable between open and closed conditions, water under pressure being delivered to the flow control valves and from which water under pressure may flow at a predetermined rate. 5 The output signal generated by the output device may be directly porportional to the rate at which fuel oil is fed to the burner, such as by the use of means to measure the flow rate, or indirectly proportional as may be effected by the generation of a signal determined by the rate of operation of a pump for the fuel oil. The apparatus preferably comprises a constant pressure water delivery system by which water at constant pressure is delivered to the flow control valves, the delivery system preferably being of the constantly circulating type. Preferably the flow control valves are each movable between open and closed conditions, in which open condition water delivered thereto flows via a delivery line to a mixing chamber, at which the water is mixed with the fuel oil prior to injection into a burner.

Preferably the flow control valves are bi-stable, being capable of normally adopting only fully open or fully closed conditions. Advantageously each flow control valve comprises a needle valve, together with a solenoid device for moving the needle valve between open and closed positions.

Advantageously the control valves are each operative, when in their open conditions to deliver water at different flow rates. Preferably the control signal is a voltage signal, the magnitude of which determines the number and/or which, flow control valves are opened.

Preferably the control signal is an analogue signal proportional to the rate of fuel oil flow, and the control device is operative to -convert tele^¬ control signal to digital signals, the number of which is dependent upon the magnitude of the control signal, and the number of digital signals is used to determine the state of the flow control valves.

Preferably the flow control valves are each operative to supply water at differing rates, that operating at the lowest rate providing the lowest flow rate of water, the highest flow rate of water being provided by the total of the delivery rates of all the flow control valves.

For example there may be four control valves, operative to feed water in the ratio 1 :2:4:8, whereby, on selection, any numerically integral flow rate between I and 15 may be obtained.

Preferably however the flow control valves comprise an additional flow control valve ^"operative to delivery water at a relatively low rate (e.g. the rate of the lowest existing flow control valve) which may be utilised to act as a booster.

There will now be given a detailed description, to be read with reference to the accompanying drawings, of an apparatus for adding water to the fuel oil, which apparatus has been selected for the purposes of illustrating the invention by way of example. In the accompanying drawings: FIGURE I is α schematic view of the apparatus which is the preferred embodiment of the invention;

FIGURE 2 is a schematic view of a mixing or defusion chamber thereof;

FIGURE 3 is a view of an alternative construction of mixing chamber; and

FIGURE 4 is a circuit diagram of a control device of the preferred embodiment.

The apparatus which is the preferred embodiment of this invention comprises a plurality, specifically 5, flow control valves 6a, 6b_, 6c, 6d, 6e,

I ff: each comprising a needle valve 7 and a solenoid 8 operative to move the needle valve between open and closed positions. The flow control valves 6a to 6d are each operative, when open, to deliver water at different flow rates in the ratio 1 :2:4:8, specifically 5, 10, 20 and 40 litres per hour, whilst the flow control valve 6e is operative to deliver water at a low flow rate of 5 15 litres per hour.

Water is delivered to the flow control valves at constant pressure in a recirculating water delivery system, comprising an inlet 4, which is connected to a supply of pressurised water, a water filter 10, and a f low sensor 1 2, operative to ensure that the pressure of the water delivered to the 20 flow control valves is maintained constant irrespective of the state of the flow control valves, surplus water being returned via a recirculation line 5 back to the inlet 4.

The apparatus comprises an output device operative to generate an output signal proportional to the rate of flow of fuel oil in the burner system,

23. said output signal being in the form of DC analogue voltage signal variable through the range 0.013 VDC to I 1.85 VDC, according to the setting of the oil control valve. The output signal is delivered to a flow control device 1 6, comprising a means 18 for converting the analogue control signal to a series of digital signals, the number of which being directly proportional to the

30 value of the control, analogue signal. The digital signals are fed to a digital control device 20, at which the signals are counted and recorded, the number of the signals being applied to a relay driver output 22 which controls the solenoid 8 of the five flow control valves in accordance with the number of digital pulses. 5 The circutry by which this is accomplished is shown in Figure 4. If the burner is at a minimum setting, and the value of the analogue signal is such as to indicate a theoretical water supply rate which is lower than 5 litres per hour, the relay driver output 22 retains all five of the flow control valves closed. As the flow rate of fuel oil in the system increases, the number of digital signals produced in the digital control system 20 reaches a first threshold, the effect of which is to cause the relay driver output 22 to open the first flow control valve 6a, to cause water to be delivered through the outlet 14 at the rate of 5 litres per hour. This level is maintained as the rate of fuel oil feed, and hence the value of the analogue control signal, increases towards a second threshold, at which point the relay driver output 22 closes the flow control valve 6a and opens the flow control valve 6b, causing the rate of water feed to be increased to 10 litres per hour. Similarly this rate is maintained until a third threshold value is reached, at which the relay driver output 22 opens the flow control valve 6a whilst maintaining the flow control valve 6b_ in its open condition, thus increasing the water flow rate to 15 litres per hour.

It will thus be appreciate that the maximum rate at which water may be delivered by the use of the apparatus is equal to the sum total of all the flow control valves, which for the flour control valves 6<3 to 6d is 75 litres per hour, this being selected as the maximum normal rate at which it is desired to deliver water to the burner system, when the burner is operating at a maximum fuel oil feed rate.

Desirably the apparatus additionally comprises sensing means operative to sense other burner parameters, producing additional control signals which may reflect one or more of the following:

(a) flame temperature;

(b) burner temperature;

(c) oxygen/carbon dioxide content;

(d) sulpher dioxide content of exhaust material. These additional control signals may be applied to the relay driver output to modify the manner in which the relay driver output effects control of the flow control valves 6, in response to the output from the digital control system 20.

Thus, when the burner is initially switched on, and the temperature of the burner is at a low rate, the control signal which is produced and which is dependent upon the burner temperature may modify the relay driver output ^' 5 -

control to prevent the opening of any of the control valves 6, to prevent the delivery of water to the burner, until an optimum minimum temperature has been obtained, or to at least reduce the rate at which water is so fed to a rate less than the optimum. Similarly the water delivery rate may be reduced or increased, as may be desirable to ensure optimum burning efficiency and/or a minimum emission of noxious fumes.

Thus, when the signals applied to the relay driver output are recognised as indicating that the burner is operating at full rate and at maximum theoretical efficiency, the fifth flow control valve 6e may be caused to be opened, to delivery a small additional quantity water to the burner, specifically increasing the flow rate from 75 to 80 litres per hour, as a "booster" delivery.

Water is delivered via the pipe 14 to a defusion chamber 24, to which oil is also admitted via inlet 26. The defusion chamber can be of a variety of types, and two such chambers are il lustrated in Figures 2 and 3.

In Figure 2 a defusion chamber is shown which is divided into two compartments 30 and 32 by a ^" central wal l 34, a transfer duct 38 interconnecting the two compartments. The compartment 32 is defined in part by a part-spherical wal l 36, against which both water and oil flows are directed, in opposite directions to cause maximum turbulence at the point of contact and prior to entry into the transfer tube, whilst a part-spherical baffle 40 is provided in the compartment 30, and against which the mixture of water and oil is directed as it flows from the compartment 32. The swirling caused, in the compartment 32 and both at entry into the compartment 30 and prior to exit from the compartment 30 (such as into an outlet 28 extending towards the burner) is effective to cause a considerable degree of emulsification of the water in the oil.

The alternative construction shown in Figure 3 is simpler, the water and oil inlets being directed in a generally opposed manner into a chamber 24a, baffles 44 being provided to cause turbulence and emulsification of the mixture prior to exist through the outlet 28.

Claims

CLAI S:

1. Apparatus for adding water to fuel oil comprising:

(a) a plurality of flow control valves each operative selectively to control the flow of water to a burner;

(c) a control device operative to control the flow control valves in response to the output signal.

2. Apparatus according to Claim I wherein the flow control valves are each selectively movable between open and closed positions, water under pressure being delivered to the flow control valves and from which water under pressure may flow at a predetermined rate.

3. Apparatus according to Claim I wherein the output signal generated by the output device is directly porportional to the rate at which fuel oil is fed to the burner. ^' •

4. Apparatus according to Claim 1 wherein the output signal generated by the output device is indirectly proportional to the rate at which fuel oil Is fed to the burner.

5. Apparatus according to Claim I wherein the flow control valves are movable between open and closed conditions, in which open condition water delivered thereto flows via a delivery line to a mixing chamber, at which water is mixed with the fuel oil prior to injection Into a burner.

6. Apparatus according to Claim I wherein the control signal is a voltage signal, the magnitude of which determines the number and/or which flow control valves are opened.

7. Apparatus according to Claim 1 wherein the control signal is an analogue signal proportional to the rate of fuel oil flow, and the control device is operative to convert the control signal to digital signals, the number of which is dependent upon the magnitude of the control signal, and the number of digital signals is used to determine the state of the flow control valves.

8. Apparatus according to Claim I comprising four control valves operative to feed water in the ratio 1 :2:4:8, whereby, on selection, any numerically integral flow rate between I and 15 may be obtained.

9. Apparatus according to Claim I comprising an additional flow control valve operative to deliver water at a relatively low rate which may be utilised to act as a booster.

10. Apparatus according to Claim I comprising sensing means operative to sense other burner parameters, and operative to produce additional control signals which may reflect one or more of: (a) flame temperature;

(b) burner temperature;

(c) oxygen/carbon dioxide contents;

(d) sulphur dioxide content of the exhaust material, said additional control signals being applied to the control device to vary the reponse of the apparatus to the output signal.