US3126875A

US3126875A - Supply of cold water to the low-pressure side of hot water pumps

Info

Publication number: US3126875A
Authority: US
Publication date: 1964-03-31
Anticipated expiration: 1981-03-31

Description

March 31, 1964' H. VOGLER 3,126,875

SUPPLY OF COLD WATER TO THE LOW-PRESSURE SIDE OF HOT WATER PUMPS Filed Aug. 16, 1960 2 Sheets-Sheet 1 Jnvenlor:

Hons Vogler BY ATTORNEYS March 31, 1964 I H. VOGLER 3,126,875

SUPPLY OF COLD WATER TO THE LOW-PRESSURE SIDE OF HOT WATER PUMPS Filed Aug. 16, 1960 2 Sheets-Sheet 2 Jnvenfor:

Hons Vogler BY P MWE-XW (f tn ATTORNEYS United States Patent This invention relates to a device for supplying cold water to the low-pressure or suction side of pumps in hot water systems having a control valve for the cold water feed.

The injection of cold water on the suction side of hot water pumping systems is a known procedure for eliminating the risk of water evaporation in the pump due to pressure drops or similar disturbances. When using this known procedure, the cold water feed is controlled by a control valve included on the suction side of the pump that is responsive to both the temperature and the pressure of the hot water being circulated by the pump. However, this arrangement is cumbersome since a reference pressure must be maintained at all times.

By contrast, my novel system provides for the control valve for the cold water feed to be responsive to impulses derived from transient pressure variations or rate of pressure variations occurring on the suction side of the pump. My new system is simpler than the conventional systems in that it is controlled as a function of but one operating variable. The operating temperature variable need not be determined since whatever disturbances may occur are due only to rapid pressure drops. Moreover, my new system permits greater freedom in selecting the point where the pressure variation determining the impulse actuating the control valve may be positioned than when the conventional system is used, where the connecting point for the temperature-sensitive element, and consequently for the control valve, must be accurately positioned.

Referring to the drawings which illustrate two preferred embodiments of my invention,

FIG. 1 illustrates diagrammatically a hot water pumping system incorporating a cold water feed control valve responsive to rate of pressure variations occurring on the suction of the pump; and,

FIG. 2 illustrates diagrammatically a slightly different embodiment than that shown in FIG. 1 wherein the control valve is also responsive to load of a steam generator.

Referring to the drawings wherein similar parts have the same reference numeral, and in particular to FIG. 1, the numeral 1 denotes a hot Water tank, and 2 a hot water feed line connecting hot water tank 1 with the suction side of pump 3. Hot water is stored in hot water tank 1 under steam pressure, and condensate is delivered to it through a line 10.

In addition to line 2, a line 11 is connected to tank 1 and leads to a pressure-differential measuring device 4 comprising a diaphragm 12. A line 13 branches off line 11 ahead of the point Where line 11 passes into the casing of the pressure-diiferential measuring device 4. Line 13 has therein a throttling member 7 and the line discharges into a vessel, designated by V, of any desired shape and having a considerably larger volume than the chamber of the device 4 into which line 11 passes and the section of line 11 between line 13 and the casing of the device 4. A line 14 leads from vessel V to the casing of pressurediiferential measuring device 4, passing, however, into a chamber that is separated by diaphragm 12 from the chamber into which line 11 passes.

A valve stem 15 is attached to diaphragm 12 and forms part of a control valve 5 in a cold water feed line 16 through which cold Water is supplied to the system. Downstream from control valve 5 in the direction of flow of the cold water, line 16 is divided into four parallel branches 6, in each of which a controllable branch throttling element 8 is provided. Branches 6 discharge into the hot water feed line 2 between tank 1 and pump 3.

The principle of operation of the system according to FIG. 1 is as follows: Normally, pump 3 draws hot water from tank 1 through line 2 and delivers it in the direction of arrow 17to a steam generator, for example. When the pressure in tank 1 drops with attendant danger of evaporation of the water in pump 3, control valve 5 is opened by means of pressure-differential measuring device 4, and cold water flows through cold water feed line 16 and its branches 6 into the hot water feed line 2.

The opening of control valve 5 is brought about by the fact that in the case of a pressure drop on the suction side of the pump, the pressure on the right-hand side (in FIG. 1) of diaphragm 12 drops more rapidly than on the left-hand side of the diaphragm since, due to throttling member 7 and vessel V, the relatively high pressure on the left-hand side of the diaphragm is maintained for a short period of time. Pressure will then drop gradually in the chamber on the left-hand side of the diaphragm until it is equal to that in the chamber on the right-hand side of the diaphragm. The sensitivity of pressure-differential measuring device 4, and with it the sensitivity of its responsive action upon control valve 5, may be varied by adjustment of throttling member 7. Controllable branch throttling elements 8 in branches 6 permit the distribution of the cold water over the length of hot water feed line 2 to be varied with respect to location and quantity.

Referring to FIG. 2, it is seen that the embodiment shown in FIG. 1 is modified in that throttling elements 7 and 8' are controlled as a function of the load of a steam generator (not shown). For this purpose, a control box 18 is provided in which a shaft 19 is supported. The left end of shaft 19 (in FIG. 2) projects from the box and is linked through a lever 20 and a rod 21 to a load-control device (not shown) of the steam generator. Four disk cams 22 are mounted on shaft 19 and along with rollers 25 and push rods 23 control the associated throttling elements 8'.

There is further mounted on shaft 19, a disk cam 24 which acts through a roller 26 on a push rod 27 and through a bell crank 28, upon throttling element 7' in line 13. In addition, shaft 19 carries a disk cam 30 which, through a roller 32 on a push rod 31 and through a bell crank 33, actuates a member 34 controlling the pressure of the cold water. Member 34 comprises a cylinder 35 which connects through a pipe 36 to cold water feed line 16. A piston 37 slides in cylinder 35 with its rod 38 being attached to one end of a two-armed lever 39. Piston rod 38 passes through a bushing 40 which on one side is positively connected to bell crank 33 and on the other side abuts on a spring 41 which in turn bears on piston 37. The other end of lever 39, pivoted at 42, is linked through a rod 43 with a valve 44 in the cold water feed line which is located upstream in the direction of flow of the cold water of pipe 36.

Member 34, along with valve 44, permits variation of the cold water pressure ahead of control valve 5, and therefore allows variation of the quantity of cold water to be fed to the hot water pumping system to be a function of the load of the steam generator. This regulation of cold water feed is in addition to that regulation by control valve 5.

By proper design of the

disk cams

22, 24 and 30 it is possible to fix with cams 22 the location and quantity of the individual injections through the branches 6, to fix with cam 30 the cold water pressure upstream of valve 5 and hence the entire quantity injected, and with cam 24 to fix the stroke of the valve stem 15, all for specified loads of the steam generator. Forexample, disk earns 22 may be designed so that at 30 percent steam-generator load only the upper two branch pipes 6 will inject water while throttling elements 8' of the lower two branches are closed; and the quantity of water to be injected through the upper two branch pipes may further ditfer as between the two branches. At 60 percent load, for example, water may be injected through three or all four branch pipes; and in this case also, the quantity of water injected through the individual branch pipes may be graduated as desired.

While there have been illustrated and described two embodiments of my invention, no limitations are necessarily made to the precise details shown and changes and modifications falling within the scope of the appended claims may be resorted to without departing from the spirit or scope of this invention.

I claim:

1. Apparatus for the supply of hot water comprising a hot water feed line, a pump connected at its low pressure side to said feed line, a cold water feed line connecting into said hot water feed line upstream of said pump, a valve in said cold water feed line, means to measure the time rate of drop of pressure in said hot water feed line, and means to vary the opening of said valve directly with said time rate of drop of pressure.

2. Apparatus according to claim 1 wherein said means for measuring time rate of drop of pressure comprise a chamber, a diaphragm dividing the interior of said chamber into two portions, and unlike conduits connecting the interior of said chamber on opposite sides of said diaphragm to the low pressure side of said pump, and wherein said means to vary the opening of said valve comprise means coupling said diaphragm to said valve.

3. Apparatus according to claim 1 wherein said means for measuring time rate of drop of pressure comprise a chamber, a diaphragm dividing the interior of said chamber into two portions, and conduits of unlike volume connecting the interior of said chamber on opposite sides or" said diaphragm to the low pressure side of said pump,

and wherein said means to vary the opening of said valve comprise means coupling said diaphragm to said valve.

4. Apparatus according to claim 2 wherein one of said conduits includes a throttling device.

5. Apparatus according to claim 4 wherein said cold water feed line includes downstream of said valve a plurality of branches connecting into said hot water feed line at distinct points adjacent said pump, and a separate throttling device in each of said branches.

6. Apparatus according to claim 5 in which the outlet of said pump leads to a steam generator, said apparatus further including steam generator load responsive means coupled to each of said throttling devices.

7. Apparatus according to claim 6 further including a throttling device in said cold water feed line upstream of said valve, and means coupling said last-named throttling device to said steam generator load responsive means.

8. Apparatus for the supply of hot water comprising a hot water tank, a pump for pumping hot water from said tank to a point of use, a hot Water feed line leading from said tank to the low pressure side of said pump, a cold water feed line communicating with said hot water feed line, a valve in said cold water feed line, means to measure the time rate of drop of pressure in said tank, and means to vary the opening of said valve directly with said time rate of drop of pressure.

9. Apparatus according to claim 8 wherein said means to measure the time rate of pressure drop comprise a chamber having a diaphragm therein, a conduit connecting said chamber on one side of said diaphragm with said tank, and a branch conduit connecting said first-named conduit with the said chamber on the other side of said diaphragm, the volume of said branch conduit being unequal to the volume of said first conduit between said branch conduit and said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,489,345 Welch Nov. 29, 1949 FOREIGN PATENTS 1,070,497 Germany DecT5,l9S9