US2319223A - Method and apparatus for temperature regulation - Google Patents

Description

y 1943 M. FRISCH, 2,319,223

METHOD AND APPARATUS FOR TEMPERATURE REGULATION 7 Filed Oct. 11, 1940 &

INVENTOR M4,? r/N fie/50 ATTORNEY Patented May 18, 1943 METHOD AND APPARATUS FOR TEDIPERA- TURE REGULATION Martin Frisch, New York, N. ifi, assignor to Foster 7 Wheeler Corporation; New York, N. Y., a corporation of New York Application October 11,1940, Serial No. 360,825

9 Claims. (01.122-479) i2 and by.a group of steam circulator tubes l3.

This invention relates to temperature regulation, and more particularly pertains to the control of the temperature of superheated vapor.

In accordance with the invention, the temperature of the superheated vapor is-controlled by varying the amount of moisture present in the vapor at the superheater inlet. This is accomplishedby condensing a portion of the puri-' fled vapor before its admission to the super-' heater. The mixture of the condensed and uncondensed vaporthus produced is delivered to the superheater and a part of the'heat input to the superheater is utilized to evaporate the condensed vapor. Thus the final vapor temperature maybe controlled, or it may bemaintain'ed constant, under varying loads imposed on the generator, by controlling the amount of condensed vapor delivered to the superheater.

The invention will be disclosed as applied to the control of temperature of superheated steam,

but it will be understood that the invention is capable of application to the temperature control of vapors generally.

Heretofore, the temperature of superheated steam has been controlled by injecting feed water into the superheater, but since all feed water contains considerable amounts of impurities, the injection of such water has always been considered undesirable because some of the solids in the water are left in the superheater on evaporation and eventually cause damage because of the-formation of scale on the inner surfaces of the superheater tubes which results in overheating of the tubes. The remaining solids which go through the superheater may cause valves and turbines to foul causing outage and' 'loss of capacity. With the present invention the Water introduced to the superheater does not come from an outside source, but is condensed steaminormally flowing to the superheater from the steam source. Consequently, this water is chemicallytpur-and' does not carry into the superheater tubes any additional solids or impuritiestwhich would ordinarily be present in feed water. g

The invention will be understood from the following'descrlption when considered in connection with the accompanying drawing in which the single figure is a more or less diagrammatic representation of 'a steam generator, in partial vertical section, embodying a preferred form of the invention.

Referring to the drawing, a main upper steam and water drum I0 is connected to another upper drum H by a group of water circulator tubes nected with-feed line H.

steam purifying devices such as a steam washer Steam generating tubes H are connected at their upper ends to the drum), and steam generating tubes iii are connected to the drum ll. Although not shown in the drawing, it will be understood that the steam generating tubes are suitably connectedf t their lower ends in the circulatory system of the unit, which also includes the necessary downcomer tubes, not shown. Feed water is introduced to the drum l0 through a feed water distributing pipe I6 which is con- In the form shown,

i8 and a drier iii, are disposed within the steam space of the drum l0; 'A-superheater l9 which, is provided with inlet and outlet headers and 2i respectively, is positioned within a gas pass or heating zone which is bounded in part by the groups of steam generating tubes M and I5, and the circulating tubes i2, in the form shown, Saturated steam after having been purifled by the devices l8 and i8 is conducted from the drum it to the superheater inlet header 20 by'steam line 22. Within the header 20 is a condensing coil 23 which is supplied with cooling water through line 24 which is'joined with the feed water inlet line I! by 'a T-connection 25. The cooling water leaves the coil 23 and flows to the drum it through elbow 26 and T-connection 21 in the line 81. superheated steam is discharged from the outlet header 2| and is conducted to a point of use by conduit 28.

Disposed within conduit 28 is a steam temperature measuring device 29 of any suitable type, such as a thermostat, which is connected by line 30 to'a temperature regulating device or controller, presently to be described. A feed water regulating valve 32 is operated in response to the saturated steam output through a differential pressure responsive controller 'having a diaphragm' 56 which is urged downwardly, as shown by a coil spring 51. Opposite sides of the diaphragm 56 are connected to opposite sides of an orifice 58 in steam line 22, by conduits 59 and 6B. Diaphragm 56 operates a rod H which is connected through alink 62 to a lever 63 one end of which is pivoted to a fixed point and the other end of which is pivotally connected valve 32 will open wider to permit the delivery of a greater quantity or feed water to the drum l0, and whenthe steam output diminishes, the valve 32 will be moved toward or to closed position to reduce, or cut oil, the supply of water to the drum l9. Another feed water regulating valve 5i disposed on the other side of the 'r-connection 25 from valve 32 in the line H, is operated in response to variations in the water level in the drum it, through a float controller 33, the float 34 of which operates a link 35 connected to lever 52 which operates the valve -5l.

When the water level in the drum l falls below the predetermined desired level, the float 34 will open valve or 'open it wider, and when I the water level rises above the predetermined level, the valve 9| will close or will move toward closed position.

Temperature changes in the superheated steam leaving the superheater, are transmitted through line to a Sylphon bellows 39 connected to one end of a lever arm 39 which operates a pilot valve 40. The other end of the lever arm 39 is connected by links 4| and 42 to the rod 43 of a piston 44 which moves in a relay cylinder 45. A fluid such as oil, which normally fllls the relay cylinder, is led to pilot valve through a feed tube 49 and is permitted to flow from the valve either through tube 41 to the upper portion of the relay cylinder above the piston, or through tube 48 to the lower portion of the cylinder, the different paths of flow being controlled by the position of the valve 49. A flow regulating valve 49 in line 24 which conducts cooling water to the condensing coil 23, is connected to piston rod 43 through a lever arm 59.

In operation, steam entering the drum It will be purified by passing through the steam washer l3 and the drier I9 andwill be conducted through line 22 to the header 29 wherein it will pass over the condenser 23, and part or the steam will be condensed by indirect contact with feed water mined value. In this way the temperature of the steam is controlled by controlling the amount or steam condensed, and the quantity or steam condensed is varied automatically by varying the amount or water passing through the condenser.

During operation, teed-water is always available in adequate quantities through line H, irrespective oi! variations in load on the generator.

With this arrangement and method, it will be perceived that the desired superheat temperature may be maintained substantially constant automatically during operation of the generator, while at the same time the steam is kept free of solids or impurities additional to those already present in the steam. The temperature measuring device may be set as desired to regulate the temperature oi. the steam leaving the superheater. This arrangement and method is economical in first cost and in operation, the apparatus is compact, and a minimum heat exchange surface is required because of the relatively high rate of heat-transfer from water to condensing steam.

Any suitable type or condenser or condensing equipment may be utilized. Moreover, the inven tion is not limited in its application to any particular type oi steam or vapor generator.

flowing to the condenser through pipe 24. The

mixture of steam and substantially all of the condensate will flow into the superheater elements 19. Part of the heat input to the superheater is utilized to evaporate the condensed steam flowing into the superheater, so that the final steam temperature may thereby be controlled. The amount of steam. condensed in the header 29 is controlled by controlling the amount of feed water that is passed through the condenser 23 in response to the temperature oi. the

steam flowing from the superheater. When the temperature of the steam leaving the superheater outlet header 2| exceeds a predetermined value, the temperature measuring device 29 causes the Sylphon 39 to expand downwardly to connect the oil flow path 48 with th feed tube 46 and to connect the flow path 41 with the valve discharge. This changes the balance in the relay cylinder with the result that the piston 44 and rod 43 will move upwardly, thereby opening the valve 49. An additional amount of cooling water then will flow to the condensing coil 23, and a greater amount of steam will be condensed in the superheater in let header 20, with the result. that the flnal temsteam falls below the predetermined value, the

operation will be reversed, i. e. the temperature controller will operate to close valve 49 or to move it toward closed position, until the temperature of the steam has been increased to the predeter- Inasmuch as various changes may be made in the particular form, location and arrangement of the parts of the apparatus .disclosed and in the steps oi the process and their sequence as disclosed without departing 1mm the principles of the invention, it will be understood that the invention is not to be limited excepting by the scope of the appended claims.

What is claimed is:

l. The method or superheating vapor which comprises passing unsuperheated vapor from a vapor generating zone and without further heat treatment to a condensing zone, condensing part or the unsuperheated vapor in the condensing zone by indirect contact with a condensing medium, introducing the unsuperheated vapor in admixture with substantially all of the condensate produced in the condensing zone into a superheating zone wherein the condensate is vaporized, and controlling the quantity of vapor condensed to control the final temperature oi. the vapor.

2. The method of superhealting vapor which comprises passing saturated vapor from a saturated vapor generating zone and without further heat treatment to a condensing zone, condensing part of the saturated vapor in the condensing zone by indirect contact with a condensing medium, introducing the saturated vapor in admixture with the substantially all of the condensate produced in the condensing zon into a superheating zone wherein the condensate is vaporized, and controlling the quantity of condensing medium brought into contact indirectly with the vapor direct heat exchang relationship with feed liquid for the generator in the condensing zone to condense part of the vapor, thereafter passing the saturated vapor in admixture with substantially all of the condensate produced in the condensing zone through asuperheating zone wherein the condensate is vaporized, and controlling the quantity of feed water passed through the condensing zon to control the final temperature of the vapor.

4. The method of superheating vapor in a vapor generator which comprises introducing saturated vapor without further heattreatmenrt into a condensing zone, passing the saturated vapor in indirect heat exchang relationship with feed liquid for the generator in the condensing zone to condense part of the vapor, thereafter passing the saturated vapor in admixture with substantially all of the condensate produced in the condensing zone through a superheating zonewherein the condensate is vaporized, and controlling the quantity of feed water passed through the condensing zone in response to the temperature of the vapor after superheating to control the final.

temperature of the vapor.

5. Apparatus for superheating vapor comprising a superheater, means for heating the superheater, a condenser, means for supplying a cooling medium to the condenser, means for passing unsuperheated vapors from a vapor generator and out of heat exchange relationship with a heating medium :to the condenser and in heat exchange relationship with the condenserto condense part of the vapor prior to superheating,

means for introducing the unsuperheated vapor in admixture with substantially all of the condensate produced in the condenser into the superheater, and means for controlling the quantity of vapor condensed.

6. Apparatus for superheating vapor comprising a superheater having tubular members, means for heating the suprheater, a condenser having a condensate outlet, means for supplying a cooling medium to the condenser, means for passing unsuperheated vapor from a vapor generator and out of heat exchange relationship with a heating '7. A vapor generator comprising a vapor gen-' I the condenser, means causing the saturated vapor from the generating section to flow out of heat exchange relationship with a heating medium and into heat exchange relationship with the condenser to condense part of the vapor, means for introducing the saturated vapor in admixture with substantially all of the condensate produced in the condenser into the superheater, and means for controlling the quantity of vapor produced.

8. A vapor generator comprising a vapor gen erating section, a superheater, a condenser, means for introducing feed liquid for the generator into the condenser, means causing the saturated vapor from the generating section to flow out of heat exchange relationship with a. heating medium and into heat exchange relationship with the condenser to condense part of the vapor, means for introducing the saturated vapor in admixture with substantially all of the condensate produced in the condenser into the superheater, and means for controlling the quantity of feed liquid introduced to the condenser in response to the temperature of the vapor after superheating to thereby control the temperature of the superheated vapor.

9. A steam generator comprising a steam generating section including a steam drum, a superheater comprising an inlet and an outlet header and superheater tubes connecting the headers, means for passing steam from'the steam drum out of heat exchange relationship with a heating medium to the inlet header, a condenser in the superheater inlet header, means for supplying a condensing medium to the condenser, and means for controlling the quantity of condensing medium supplied to the condenser to control the quantity or steam condensed in the inlet header,

the inlets of the superheater tubes communicating with the lower portion of the inlet header so that the steam in admixture with substantially all or the condensate produced by the condenser flows into the slmerheater to thereby control the temperature to which the-steam is superheated.

MARTIN FRISCH.

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