US2956784A

US2956784A - Apparatus for condensing and deaerating

Info

Publication number: US2956784A
Application number: US746185A
Authority: US
Inventors: Russell W Parkinson
Original assignee: MARYLAND SHIPBUILDING AND DRYDOCK Co
Current assignee: MARYLAND SHIPBUILDING AND DRYDOCK Co
Priority date: 1958-07-02
Filing date: 1958-07-02
Publication date: 1960-10-18
Anticipated expiration: 1977-10-18

Description

Oct. 1s, 1960 R. w. PARKlNsoN APPARATUS FQR co'NDENsING AND DEAERATING Filed July 2'. 1958 5 sheets-sheet 1 ATTORNEY Oct. 18, 1960 R. w. PARKlNsoN APPARATUS FOR CONDENSING AND DEAERATING Filed July 2. 1958 S sheets-sheet 2 ooo o@ 00% Je o@ INVENTOR BY Q6/WM @m ATTORNEY 5 Sheets-Sheet 5 INVFNTOR L?? 1? BY Oct. 18, 1960 R. w. PARKINSON APPARATUS FOR CONDENSING AND DEAERATING y Filed July 2. 195e 5 Sheets-Sheet 4 INVENTOR ATTORNEY Oct. 18, 1960 R, w. PARKlNsoN APPARATUS FOR CONDNSING AND DEAERATING l Filed July 2, 195s' 5 Sheets-Sheet 5 1N VENTOR BY ATTORNEY United States Patent VC) APPARATUS FOR CONDENSING AND DEAERATING Russell W. Parkinson, Jackson, Mich., assignor to Maryland Shipbuilding and Drydock Company, Baltimore, Md., a corporation of Maryland Filed July 2, 1958, Ser. No. 746,185

2 Claims. (Cl. 257-43) My invention relates to a deaerating condenser for steam from mechanism such as turbines and other power devices, and to the process carried out in the apparatus. The problem of getting the gases out of the condensed water Iis important because the oxygen in the condensed water `when reused in the boiler is particularly corrosive to metallic parts of the boiler, turbine or other mechanism. In lthe condensed liquid there will be gases which comprise oxygen as well as nitrogen and rare gases, but it is the oxygen content that is the most objectionable.

Heretofore, in a condenser of the type illustrated herein the average performance would leave Iabout .03 cubic centimeter of oxygen per liter of condensate. This iigure is too high for commercial use and so refinements were yadded to reduce this in certain cases to .01 cubic centimeter of oxygen in a liter of condensate. To go below this latter ligure was exceedingly ditlicult and re-` quired additional steps and expensive apparatus. I can achieve a reduction in the oxygen content of the liquid condensed to about .005 or less per liter of condensate. This is low enough for most practicable purposes. Moreover, this reduction in oxygen content can be accomplished without greatly increased cost, and in the simple appara-tus illustrated in the drawings without the addition of further steps.

In my system reduction of oxygen in the last stage is accomplished by flashing the condensate from the reheating hot well stage in a sealed hot Well stage. This degree of flash can be maintained nearly const-ant with only slightly decreased back pressure and is only slightly decreased at lower loads. In general the device consists of a chamber in the condenser which is connected to the exhaust of the turbine or other engine. Steam passes first to a shell in which are located the tubes which form the condensing phase of the deaerating condenser. The main tubes condense the steam and the liquid drips from the tubes towards the bottom of the condenser. It -is desirable to have a good circulation of steam throughout the entire enclosure in which the condensing tubes are located, and this I accomplish among other things by placing the tubes so that there is no undue obstruction at any point so as to minimize concentrations of steam or vapor by eliminating stagnant or low velocity areas.

Below the main `condenser is a section called the reheating hot well zone. The condensate from the main condenser is caught in a collector tray for the main section of the condenser tubes. There is provided a baille at the side of this tray which directs Ithe steam against the tubes above it to prevent concentration of the ilow of steam and gases in directions which are not profitable to the operation. Below the balile and displaced laterally from this collector 4tray there is located a control tray which is divided into yan inside and outside section. The outside section is in a reheating hot well zone which zone receives the discharge from the collector tray for the main section. In the reheating hot well zone is a collector tray for that zone which collects the condensate,

ice,

partially deaerates it, and passes it to a `sealed hot Well zone located below. The inside section of the control tray yis likewise in the sealed hot well zone -irrwhich is collected the finally deaerated liquid for return to the boiler. In this last zone, the sealed hot well zone, the condensate is flashed to reduce the gaseous content. The liquid has been sufficiently cleansed from its oxygen content in the reservoir that receives the condensate from the reheating hot well zone -to be capable of use without further treat-ment. p

Control is effected so that the sealed hot ,well zone operates at a slightly diierent and lower pressure than` the reheating hot well zone. The steam comes in to the reheating hot well zone -and circulates around the baille of thegcollector tray for the main section of the condenser tubes, and over the outside elements of the control tray and the collector tray for the reheatinghot well, and the vapor or steam which'together with the entrained and released gases from the condensate pass upwardly through Ia bank of tubes and into the outside main air cooler which is located in a hood and consists of a series of water cooled tubes. Y

There is a iiow Vof liquid between the inside and the outside sections of the control tray, and there is a different water level in the inside control tray from the outside. This water level is determined by `the control of4 the pressure-gradient between the inside and outside sections -of the control tray, and this `diilerence in liquid level is also a function ofl-the resistance of the ow.

of steam and gases through thetube bank of the inside air cooler section for venting the gases from the sealed hot well and the resistance of the mainCondenser tube bank and the outside air cooler section.. for collecting and cooling the gasesand entrained vapor is effected by reason of yan adjustable weir located inV the outside section of the control tray, and this in combination with the control of the vacuum caused by difference in resistance to steam and gas iiow between the main condenser Iand air cooler deaerating section for the outside mainv air cooler for the reheating hot well and the inside air cooler for the sealed hot well determines the degree of dilerence of pressure between these twol sections. The condensed liuid flows into the sealed hot well zone in 4small streams to etect maximum flashing before making direct Contact with the stored condensate which is for recirculation back to the boilers and there is practically no communication between the reheating hot well zone and the sealed hot well zone, except for the passage of liquid. There is, however, a small venting of vapors and gases between the two zones which is maintained in order to produce a sutciently high velocity to prevent buildup of air or gas in the sealed hot well section. This communication between the two zones is of small magnitude and the statement can be made that the sealed hot well zone and the reheating h ot well zone are separated from each other and not in free and uni-mpeded communication.

In the drawings: Fig. l is a view in side elevation of my condenser deaerator apparatus attached to the exhaust of a turbine.

Fig. 2 is a View partly in diagram of a vertica-l section of my condenser deaerator apparatus, showing the gas and vapor ow.

Fig. 3 is an enlarged view partly in diagram of the reheating and sealed hot well and the air cooler sections for both wells.

Fig. 4 is an enlarged fragmentary view of the hot well zone of my condenser deaerator.

Fig. 5 is a detailed view of a modification of the apparatus.

There is shown in the drawings in phantom a turbine 100 connected to a suitable source of steam 101. The exhaust from turbine 100 is connected to a condenser deaerator 102 which has a steam dome 103. The steam dome is somewhat narrower in dimension at its top and is expanded outwardly and downward and is attached through a steam inlet flange 104 to a ange 105 integral to the turbine exhaust. The steam dome 103 transitions to the main body of my condenser deaerator y106 which is integral with a low reservoir 115 as indicated at the position 107 in Fig. 1. The condensate in -the hot well in Figs. 2, 3 and 4 is indicated at 115. Cooling water enters through conduit 108 and into Water inlet header 109, then through the condenser tubes 121 where it passes to outlet header 110 to be discharged through conduit 111. There are shown sections of the apparatus indicated by horizontal and vertical dotted lines in Fig. 1. These lines 113 are support plates for the condenser tubes and line 114 indicates sections of apparatus as will be later described in greater detail.

Deaerated hot water is gathered in a hot well 115 formed in the bottom of the casing 107. This deaerated hot water is removed through condensate outlets 116 and is sent back to the boilers for forming steam to run the turbine. Since there is a certain amount of loss of Water by the system make up water is added by make up water inlet 117. The absorbed gases in the steam are removed through air take off 118.

There is shown in the drawings Fig. 2 a construction in which the deaerator condenser is divided into two parts. This is for the purpose of permitting one part to be cleaned while the other part is operated. Each part is connected to the steam dome 103 and the condenser has a vertical strong back 119. There is in the construction a division which proceeds to the bottom of the deaerating condenser, as will be apparent from the ensuing description. Thus, the condenser can be easily cleansed while one half is still in operation.

The air take off 118 is adapted to be connected to some air exhausting apparatus to create a vacuum under which the condenser operates. The vacuum can be accomplished by any of the well known methods such as a vacuum pump, la steam jet air ejector, or some other form of exhausting apparatus. This condenser deaerator is adapted to operate at a high vacuum, approximately 29 inches of vacuum. The cooling tubes in which the cooling water is circulated can have the water passed to another section not shown in the drawings.

As before stated this one piece of apparatus will give good enough results to dispense with expensive after treatment. Heretofore, similar types of apparatus gave only a reduction to .03 cc. of oxygen per cubic liter of condensate in standard practice. By refinements of the former apparatus it was possible -to achieve .01 cc. per liter of condensate at relatively high loads and high operating temperatures. By my improved process and apparatus the oxygen content of the condensate can be reduced to .005 or less cubic centimeter per cubic liter of condensate over a much wider range of conditions of load and operating temperatures.

The steam being condensed is passed thru the banks of tubes through main condensing zones 120 and 120' over the main condenser tubes 121. The flow of steam from the steam dome 103 is indicated by unbroken arrows 122. It is desirable that steam ow unimpeded through all the various sections of the tubes, and to that end the interior Qf the tube sheet 123 for the condenser is built to arrange the shape of the tube bundle with rounded corners as ind-icated 123. Throughout the description of the operation and in order to clarify the passage of the steam I have illustrated the stem as formed by solid arrows 122. Where steam and air are in a mixed condition I have indicated this by combining the solid arrow for the steam with a dotted arrow 122 for the air. Again where the great percentage of the moving duid is air I have indicated this by dotted arrows alone. It is to be understood that there can be no exact dividing line where steam stops and air starts but there is in actual practice a somewhat undefined ratio of the mixture of air and steam. However, for purposes of description the use of the solid and dotted arrows will give a fair understanding of the operation of the system.

It will be noted that steam circulates along the outside of the banks of the main condenser tubes 121, see Fig. 2, and this enables the steam to reach the bottom of the apparatus where it performs a very necessary function in assisting in reheating and deaerating the condensed liquid.

Steam is passed through the main banks of condenser tubes in the main condenser zone and the lower section 120 of that main condenser zone. Steam then passes also through a reheating hot well zone 124. It will be noted that in the reheating hot well zone there is not only steam but by this a considerable amount of liberated gas and air which has been removed from the condensed uid. The condensate from the main

condenser tube banks

120 and 120 flows over a tray 125 in which is caught the greatest percentage of the condensate which has dripped from the surface of the main condenser tubes 121. Some of this steam is deected by a bathe 126 upward and thence towards air cooler section 127 which I have generally indicated by this number and which comprises a hood in which are located banks of cooling tubes for air cooling. It will be noted that there are located baies 129 to prevent the ow of the steam directly to the main air cooling section of the apparatus.

Condensate is caught in tray and passes out through apertures 130 formed on the bottom of the tray 125 and into the reheating hot well zone 124.

Also, some of the condensate from the

main condenser section

120 and 120 drips from the tubes into an upper outside section 131 of a tray arrangement indicated gen erally by the numeral 132.

Let us follow the passage of condensate and vapors; some condensate drips from the tubes above it into the upper outside section 131 of the tray arrangement 132 and condensate falls into the lower outside control section of the control tray 135 through holes 134. The overflow is at 134' which comprise V notches on the edge of the tray. Again some of the condensate and entrained gas from the lower outside section 131 of control tray 135 passes downwardly through apertures 139 as indicated 139 into the tray 136 located above the sealed hot well 137. The outside section 133 of control tray 135 is provided with the adjustable Weir 138 over which is discharged condensate and entrained gas into tray 136. This weir is used to maintain the desired water level in the out side of the control tray.

Tray 136 discharges condensate through apertures 141 into the hot Well 115 condensate immediately below and in contact with the sealed hot well zone 137. Also a stream of condensate as indicated at 142 is discharged into 115, through an aperture 143 formed in a border plate 144 of the tray 136. Adjacent the border plate 144 is a depressed section 145 of the tray 136 adapted to receive a downwardly projecting member 146 attached at its upper end to the bottom of control tray 135. This depressed section 145 with the liquid in control tray 135 and downwardly projecting member 146 forms a seal preventing gas or vapor from passing from reheating hot well section 124 into sealed hot well section or zone 137. There is no direct communication with the steam from the exhaust of the turbine to the sealed hot well zone or section 137 except for a minor venting between the hot Well sections through vents 147 and 201` Tray arrangement 132 on its inner side 150 has projecting into it a downwardly projecting element 153 that divides inner section 150 of the control tray 135 from the outer section 133 of the control tray 135. It will be noted that the condensate level in section 150 is different from that of 133 because of the difference in absolute pressure between the reheating and deaerating hot well zone 124 and the sealed hot well zone 137. Communication of zone 137 with the air-cooler section 127 for the sealed hot well is over the surface of the condensate in section 150 of the control tray 135 through apertures 152 in an element 153. -Apertures 152 may be formed by scalloping the lower edge of 153. The size of the apertures through member 153 will be dependent on the height of the condensate in section 150 of the control tray 135 which is controlled by the absolute differential pressure between the sealed hot well section and the reheating and deaerating hot well section.

Gases can pass over the surface of the liquid in section 150 of the control tray 135 into a channel 154 and there into a central evacuation column 155 past a splitter 156 on each side of which are cooling tubes 160 in air cooler section 127 at the upper end and into a plenum chamber 161 from which the gases are exhausted by suitable means not shown as before stated connected to the plenum chamber 161. The apertures 162 vent the air cooler section 127 for the sealed'deaerating hot well 137 and apertures 163 vent the main air cooler 12 for the reheating and deaerating hot well 124. Apertures 162 are smaller than 163 since the volume of vented gas is considerably smaller.

There is provided a center plate 165 to divide the plenum chamber to enable one half of the condenser to be cleaned Without shutting down the operation. This division is to enable proper operation to proceed through one half of the apparatus while cleaning the other half.

' In operation the exhaust from the turbine passes into the condenser where the co'ol water in the cooling blanks of tubes causes it to condense and fall into tray 125. But this condensate has dissolved therein an undesirable amount of soluble gases, principally oxygen and nitrogen, of which oxygen is in general the undesirable factor since it will tend to corrode metallic parts. By my apparatus and process I can reduce the oxygen content of the condensate to as low as .005 or less cubic centimeter per liter of condensate over a very wide range of operating loads and back pressures, which is suiciently low for practical purposes.

From tray 125 the condensate and entrained gases flow out of apertures 130 into the reheating and deaerating hot well zone 124 and the condensate falls into tray 136 being reheated and partially deaerated by the bypassed steam. Into tray 136 also condensate falls back from the tubes of the main air cooler 127" for the -reheating and ydeaerating hot well zone 124. Most of this condensate is either caught by bale 126 and directed to tray 125 or falls past the baille 126 into the upper outside section 131 of arrangement tray 132.

Upper outside section 131 of tray arrangement 132 either discharges in a stream to tray V136 located above the sealed hot well zone 137 or into outside section 133 of control tray 135 and thence drains into depressed section 145 of tray 136. By regulating the height of weir 138 the pressure diiferential between

zone

124 and 137 can be regulated.

The reason that the absolute pressure is higher in the main air cooler section 127'l than in the air cooler section 127' used for the sealed hot well 137 is because there are fewer tubes in the sealed hot well air cooler than in the main air cooler section 127", moreover in the air cooler section for the sealed hot Well these tubes may have a square pitch and the flow is laminar. Now contrast that with the main air cooler section 127" there are more tubes there, greater depth of bank, flow is turbulent; the tubes may be on triangular pitch and there 6 Also there is a pressure drop It is not is higher mass velocity. thru the main tube bank of the condenser.

necessary to relay on variations in the turbulence, or on f diterences between laminar and turbulent flow, `for the same results can be obtained by many various means; the main desirable -result being that difference in pressure between the zones is achieved. y The ydesired ash to deaerate the condensate is produced Vby the differencein pressure between the sealed hot well and the reheating

hot well

137 and 124, respec-l tively, thecondensate being at practically saturated temperature corresponding to the pressure in each section. This diiference'in pressure is produced by gases removed from lthe .sealed hotwell through the orifice 152 on the element 153 of the control tray. 'Ihe area o-f orifices 152 is varied according tothe water level on the inside 150 of control tray 135. It is contemplated that the water level will be held practically constant in the outside section of the control tray by the adjustable Weir 138; so the level on the inside section 150 is proportional to the difference in absolute pressure between the sealed hot well and the reheating and deaerating hot well. All this is apparent from the following; increase in pressure differential raises water level in section of the control tray and reduces orice area at 152, this reduces gas flow and vented steam ow which in turn reduces pressure differential until a balance is achieved.

The vented steam flow to the sealed hot well zone 137 takes place through apertures 147 in the sealing member 146. The velocity of this Vented steam will assist in preventing pocketing of ash gases in zone 137, but its main purpose is to vent the pocket under the control tray 135 in the reheating hot well section.

All this description shows that there is a more constant degree of flash than has been achieved in the prior art for this degree of flash is only slightly increased by lower loads or by higher back pressures. To produce more flash than needed results in a waste of heat.

In further explanation the operation can be seen yfrom reference to arrows indicating the passage of steam and vapor and gases through the system.

The solid arrows 122 indicate that the uid passing down and into the system and through the various parts of the apparatus therein is in the form of a steam vapor. Where a double arrow is used it indicates that there is a steam vapor and also gases in mixture. Where the dotted arrows 122 alone are used it indicates that the material is largely gases extracted from the condensate. This explanation of the use of the arrows in Figs. 2 and 4 is accurate sufficiently for the purpose of explanation though it is to -be understood that there is no denite time at which the vapor becomes a mixture with gases and where the gases have no entrained vapor in them.

Now referring to Figs. 2 and 3 and 4 it will be seen that the steam from the steam dome enters the condenser and flows in the direction of the arrows down into the main condenser section Where the condensate is caught in the tray 125. Some of the steam passes downwardly on the side of the enclosure next to the tubes as indicated at the lower right hand corner of Fig. 2. From the tray 125 the mixture of steam and the liberated gases is passed upwardly as indicated by the double arrows into the outside ar cooler section 127 for the reheating and deaerating hot well. Condensate falls down from the tubes in the section 127" and into upper outside tray 131 of tray arrangement 132 and thence into lower outside section 133 of control tray 135 to be discharged Iinto tray 136. From tray 136 it again passes downwardly into the sealed hot well zone thru apertures 141 in tray 136. The gases and steam pass in the direction of the double arrows. There is a passage of condensate to the sealed hot well section which is llashed under tray 136 and also as indicated where the word ash is written on the drawings. The ow to the cooling tubes 127' for the sealed hot well section 137 shows by the dotted arrows 122 that the mixture is now richer in gases which have been extracted. These gases will have some vapor in them which is condensed and falls back into yinside sections 150 of the control tray 135 and then into tray 136 to be deaerated as it is passed to the collector pool 115 for the deaerated condensates.

The main body ofthe condensed fluid at the bottom of the apparatus is now practically completely degasified condensate, and this is recirculated to the steam generator.

In the modified form of my apparatus illustrated in Fig. I have shown `a construction in which there are provided additional apertures admitting steam to the sealed hot well to create suicient velocity ahead of the flash streams in order to move the oxygen and non-condensables to the variable orifice, and to prevent air blanketing just above the surface of the condensate.

Note in Fig. 5 at the lower left hand of the drawing there is indicated a venting construction which is adapted to lie between two similar constructions, only one being shown. The tray 136 is extended into the adjacent section (not shown). It is inclined upwardly and bent into a form shown in cross-section as an inverted U--see 200 of the drawing. The steam comes downwardly past the tube banks over 200 and through apertures 201 and thence passes into the sealed hot well. The amount of venting is sufficient to create the desired velocity ahead of the flash streams. Care should be taken not to admit an excessive amount of steam at this point to the sealed hot well, else the devised equilibrium of the operation will be destroyed. Though I do not wish to be limited to delinite figures a velocity of in the neighborhood of 3 feet per second of the steam ahead of the ash streams is desirable.

While I have shown a form of my process and apparatus I desire that my invention be limited solely by the scope of the appended claims and the showing of the prior art.

I claim:

1. An apparatus for condensing and for deaerating liquids condensed comprising a source of condensed liquid at relatively high temperatures and high content of dissolved gases, means for reducing the gaseous content of the condensed liquid comprising a chamber, means to exhaust gases from the chamber to create a vacuum therein, a rst conduit connected to the chamber in an upper zone of said chamber, a main bank of cooling tubes in the first conduit, a tray to catch condensate from the bank of tubes, a second conduit connected to the chamber in the lower zone of said chamber, a second tray for condensate in communication with the second conduit, said second tray being in communication with the rst tray, a liquid lock in said communication, a second bank of cooling tubes in the second conduit, the cooling tubes in the rst conduit providing resistance to flow of fluid in the first conduit greater than that in the second conduit whereby liquid in the second tray is subjected to deaeration at lower pressure than in the first tray.

2. An apparatus for condensing liquid from steam and for deaerating the liquid condensed, comprising a chamber in which the steam is delivered, a main condenser therein, at least one high pressure reheating hot well beneath the condenser into which is delivered condensate from the main condenser, at least one low pressure sealed hot well beneath the reheating hot well to which the reheating hot well delivers condensate in exposed streams for dashing thereof, flow impeding control means for maintaining the reheating hot well at higher absolute pressure than the sealed hot well, including individual cooler sections communicant with said reheating hot well and said sealed hot well, the cooler section which cornmunicates with the reheating hot well having means providing a greater resistance to ow than the cooler section which communicates with the sealed hot well, whereby iiashing of the condensate in the sealed hot well results in condensate deaeration.

References Cited in the tile of this patent UNITED STATES PATENTS 1,855,231 Grace Apr. 26, 1932 1,962,183 Ehrhart June 12, 1934 2,542,873 Karr Feb. 20, 1951 2,791,400 Riehl May 7, 1957