US1405483A - Evaporator system - Google Patents

Description

S. BROWN.

EVAPORATOR SYSTEM.

APPucATloN FILED JAN. 26, 1920.

Patented Feb. 7, 1922.

,www

STE@ STATES raraur certes.

STANLEY BROWN, OF GARDEN CITY, NEW YORK, ASSIG-NOR T0 THE GRISCOM RUSSELL COMPANY, 0F NEW YORK, N. Y.,

A. CORPORATION OF DELAWARE.

EVAPORATOR SYSTEM.

Specication of Letters Patent.

Patented Feb. 7, 1922.

Application flledrJ'anuary 26, 1920. Serial No. 354,000.

To all whom t may oon/cem:

Be it known that I, STANLEY BROWN, a citizen of the United States' residing at Garden City, in the county of Nassau, State of New York, have invented certain new and useful Improvements in Evaporator Systems; and I do hereby declare the following to be a full, clear, and exact descr1ption of the invention, such as will enable others skilledv in the art to which it appertains to make and use the same.

This invention relates to improvements 1n evaporator systems, and particularly to a feed water heater whereby the heat usually lost in the blow-down of an evaporator plant may be conserved without the addition of costly auxiliary apparatus to the plant.

A further object of the invention is to provide an apparatus for heating the feed water of an evaporator plant in which the concentrated solution constituting the blow-down does not come in contact with any heat transferring surface which would be corroded or scaled by the solution.

In the accompanying drawing I have shown in Fig. l an evaporator layout containing a feed water heater embodyin my invention, and in Fig. 2 a slight modification.

In the drawing, which is largely diagrammatic, 1 indicates the first unit of the evaporator plnant, here shown as a double effect plant of which the second unit 2 has its heating coils 3 connected to th'e vapor line 4. 'of the first unit.

The steam coils of the first effect will be connected to a suitable source of live steam (not shown) and the drain from the heating coils of both effects will be led to the. hot Well of the plant or otherwise disposed of.

In an apparatus of this kind it is frequently desirable to deliver the vapor from the apparatus at a comparatively high temperature, particularly where the apparatus isl used to supply the boiler make-up for high pressure steam plants, and as the temperature of the vapor delivered from the last effect determines the temperature of the blow-down, there would be considerable heat lost were the blow-down discharged directly as waste from the evaporator.

a feed pipe 7 at the desired water level in the evaporator, a trap 8 being interposed in the line 7 to hold the first effect at the desired operating pressure which must of course be higher than the pressure of the second effect.

It is customary to heat the feed water by means of the .exhaust steam from the auxihary apparatus used in connection with thel plant, for instance on shipboard, the steam used for the hoisting engines and similar purposes is used in the evaporator feed heater, and in carrying my invention into effect. I use the exhaust steam through the auxlllary steam line 12 for heating the raw Water which enters the evaporator feed heater through the pipe 14 and is fed to .the evaporator by the pump 6, a separator Aplants of this character, as usually operated,

the volume of feed is maintained at such point with relation to the rate of the evaporation in the plant that the overflow through the blow-down is a material portionof the feed for instance for sea-water operation the blow-down will equal about onethird the volume of the feed, that is, thel blow-down is concentrated to three times the salinit of the normal'sea water. This. amount of water at the high temperature of the vapor discharge represents a considerable vquantity of heat and if discharged directly as waste, would materially reduce the efficiency of the plant as a whole. In carryingout the invention of the present application the' blow-down discharge pipe 9 leads to a trap 11 and from the chamber or vapor space .of the trap aLpipe 15 leads ao/the exhaust steam line 12 which is usually at about atmospheric pressure, thereby relieving the pressure on the blow-down so thatthe extra heat represented by the tempera- `ture above 212 degrees will be converted into latent heat, producing a quantity of steam, the proportion of the steam to .the water depending upon the temperature of .the blow-down. Thus, if the blow-down is at 50 lbs; gauge, the temperature equiyalent of which is 297 degrees F. for each" pound of water, there will be 297 minus 212, or 85 B.T.U. of heat available for flash.

As the latent heat of vaporization at 212 degrees is 966 B.'l`.U. over 9% of the blowdown will be vaporized and w1ll be available for heating the feed water.

There is no danger of causing impurities in the water by this arrangement, for the reason that while the blow-down is loaded with impurities, the vapor from 1t w1ll be comparatively clean and contain a lower per cent of impurities than the raw water into which it is delivered in the open heater 13. t

In Fig. 2 a different arrangement 1s shown for accomplishing the same result. Instead of using the trap 11 an S-bend 11 is 1nstalled in the blow-down pipe 9 and above the S-bend an upwardly inclined pipe 15 leads to the exhaust steam line. The S-bend is long enouh to cause a back pressure in the blow-dnown pipe beyond the connection of the pipe 15 lfor the flash to pass through the pipe 15 to the heater, so that only concentrated dirty water at low temperature is thrown away.

A heat exchanger of ordinary construction cannot be economically used for conserving `the heat from the blow-down, for it would require an extensive heating surface to absorb any considerable per cent ofthe heat, and in view of the extreme impurlties in the blow-down the heating surface would not be efficient and would require cleaning and repairs to such an extent as to largely offset the heat-saving effected by its use.. "With the apparatus shown in the drawing, the only addition to the ordinary evaporator plant is the trap or S-bend which is of negligib-le cost and requires no upkeep whatsoever.

ln the accompanying drawings l have shown the evaporator units arranged for series feed, that is, all the raw water is fed to the first effect and all the blow-down is from the last effect which is at the lowest temperature. When the several effects are connected for parallel feed with a blowdown for each effect discharging into a common blow line an even greater quantity of heat will be saved by the invention of this application for the resulting temperature of the blow-down from all the effects will obviously be higher than from the las-t effect alone.

l claim:

1. ln an evaporator system, the combination of a feed heater, an evaporating unit said solution in excess of that contained at atmospheric pressure.

8. ln an evaporator system, the combination of a feed heater, an 'evaporating unit comprising means for discharging the conatmosphericboiling point of the solution, means for converting the sensible heat contained in said solution in excess of that contained at atmospheric pressure into latent heat of vaporization at atmospheric pressure, and means for utilizing the vapor thus formed in said feed heater.

4. ln an evaporator system, the combination of a feed heater having an independent source of vapor for heating the same, an evaporating unit comprising means for discharging the concentrated solution at a temperature above atmospheric boiling point of the solution being evaporated and means for utilizing in said feed heater the sensible heat contained in said discharged solution in excess of that contained at atmospheric press-ure.

5. In an evaporator system, the combination of a feed heater, an evaporating unit comprising means for discharging the concentrated solution at a temperature higher than the vaporizing temperature corresponding to the pressure in said heater, and means for utilizing in said heater the excess of sensible heat conta-ined in said discharged solution above that contained at the pressure in said heater.

6. In an evaporator system, `the combination. of a feed heater, an evaporating unit comprising means for discharging the con.

centrated solution at a temperature higher than the vaporizing temperature corresponding to the pressure in said heater, means for converting the excess of sensible heat contained in said discharged solution above that contained at the pressure in said heater into latent heat of vaporization at the pressure of said heater, and means for condensing the vapor thus formed in the feed heater.

lin testimony whereof l' affix my si nature.

. STANLEY BR WN.

vcent-rated solution at a temperature above

Images