Abstract: A self-starting, fuel fired, air heating system including a fuel burner fired vapor generator, a turbine, and a condenser connected in a closed circuit such that the vapor output from the vapor generator is conducted to the turbine and then to the condenser where it is condensed for return to the vapor generator. The turbine drives an air blower which passes air over the condenser for cooling the condenser and heating the air. Also, a condensate pump is driven by the turbine. The disclosure is particularly concerned with a method and apparatus which on start-up prevents the vapor generator's vapor output from being conducted to the turbine until a predetermined pressure differential has been achieved. However, after the vapor flow is once permitted, it cannot again be prevented until after the fuel burner has been shut off and restarted.

Abstract: Apparatus for separating an undesired foreign fluid, such as water, from the working fluid, such as ammonia, in a low temperature difference power plant which includes an evaporator and a condensor. A flash separator unit vaporizes the working fluid and separates it from the undesired foreign fluid. The vaporized working fluid is condensed in the condensor. The undesired foreign fluid is accumulated in the evaporator from which it can then be removed. In an alternative embodiment, the separated foreign fluid and liquid ammonia collected in the flash separator unit are not returned to the evaporator, but instead, are coupled back into the flash separator where the separated foreign fluid accumulates so that at the end of the separation process, the undesired foreign fluid can be removed from the flash separator. An alternative embodiment enables the power generating system to continue in operation, although with a decreased capacity during the fluid separation process.

Abstract: Control apparatus is disclosed for limiting overspeed in a steam turbine following a sudden loss in load. The apparatus includes at least one valve disposed in the steam conduit interconnecting higher and lower pressure sections of the turbine and an actuator for controlling operation of the valve between a fully open position and a pressure-relief position wherein the valve functions as a pressure relief valve. During normal operation, the valve is maintained in the fully open position. On receipt of a turbine overspeed signal, the valve is actuated to the pressure relief position and a volume of steam at a preselected pressure, necessary to open the valve, is held back within the turbine stages, crossovers, and so forth. This retained steam is thus prevented from adding energy to increase the speed of the turbine rotor.

Abstract: A steam extraction turbine including a steam extraction section from which steam may be extracted from the turbine for external use prior to the low pressure section of the turbine. In order to avoid overheating of the low pressure section when the amount of extracted steam is high, there is provided a cooling steam stage immediately upstream of the low pressure section through which steam is applied to the low pressure section to prevent overheating. The cooling steam stage includes blades of the rotor and thus permits energy to be extracted from the steam applied to prevent overheating of the low pressure section, the extracted energy being used to drive the turbine thereby increasing turbine efficiency.

Abstract: A method of and apparatus for recovering exhaust gas from a boiler 2 of a thermal electric power generating device 1 are disclosed. The exhaust gas from the boiler 2 is fed through a conduit 30 to a preheat section 21 of a powder raw material treating device 20. The heat of the exhaust gas is recovered as a heat source for preheating the powder raw material. The ash contained in the exhaust gas is recovered as part of the powder raw material at the preheat section. The sulfur oxides in the exhaust gas react with the desulfurizing component of the power raw material at the preheat section, and its reaction product is recovered as part of the powder raw material.

Abstract: A power plant may include a steam generator and a steam turbine wherein the steam generator provides steam to the turbine for driving the turbine and exhausted steam from the turbine is condensed in the turbine condenser to be pumped back to the steam generator as feedwater. In order to maintain minimum feedwater pump flows and to provide an alternative flow path should the steam generator require less than the available feedwater flow, a recirculation loop is provided for returning a portion of the feedwater to the turbine condenser. According to the present invention, this return flow to the condenser may be used for deaeration of condensate and for the attemperation of bypass steam.

Abstract: A power plant forced-flow boiler operative with water letdown wherein the letdown water is arranged to deliver heat to partly expanded steam passing through a steam reheater connected between two stages of a prime mover. The heating of steam in the reheater by letdown water will partly or wholly replace the use of live steam for such purpose so that the live steam will be available for driving the prime mover.

Abstract: A turbine system which includes a reheater upstream from a low pressure turbine which is subject to corrosive salt depositions from the steam. Conductance probes are inserted at predetermined positions within the low pressure turbine and based on the conductance signals the reheat temperature or load is varied so as to move the corrosive salt deposition zone away from a rotating blade stage of the low pressure turbine.

Abstract: Vaporized working fluid is supplied only to the condenser of a power plant of the type described when the power plant is cold started allowing condensate to lubricate the bearings of the prime mover before the latter begins to move. When the power plant is in steady-state operation, vaporized working fluid is supplied only to the prime mover.

Abstract: A self-starting, fuel-fired, air heating system including a vapor generator, a turbine, and a condenser connected in a closed circuit such that the vapor output from the vapor generator is conducted to the turbine and then to the condenser where it is condensed for return to the vapor generator. The turbine drives an air blower which passes air over the condenser for cooling the condenser. Also, a condensate pump is driven by the turbine. The disclosure is particularly concerned with the provision of heat exchanger and circuitry for cooling the condensed fluid output from the pump prior to its return to the vapor generator.

Abstract: A steam cycle for a nuclear power plant having two optional modes of operation. A once-through mode of operation uses direct feed of coolant water to an evaporator avoiding excessive chemical concentration buildup.A recirculation mode of operation uses a recirculation loop to direct a portion of flow from the evaporator back through the evaporator to effectively increase evaporator flow.

Abstract: Condensation system for use in a power plant. The condensate system includes side stream condenser defining therein first and second hot wells. Condensate is delivered from the first to second hot well through a condensate feed line. Condensate is introduced from the condensate feed line into a tank through a first spill-over line. Condensate is supplied from the second hot well to the power plant through a main condensate feed line. Condensate is introduced from the main condensate feed line into the tank through a second spill-over line. Actuator is operative in response to signal from a level detector detecting level of condensate in the first hot well, to regulate opening degree of a supplementary feed valve in the supplementary feed line, to close one of first and second spill-over valves in the first and second spill-over lines, respectively, and to open the other spill-over valve.

Abstract: The condensate of a closed cycle power plant that uses an organic working fluid for lubricating the bearings of the turbine is cooled to a temperature below the condenser temperature by an auxiliary cooler before being supplied to the bearings. This subcooling of the lubricating liquid increases its viscosity to a value which causes the minimum thickness of the lubricating film in the bearings to be increased significantly. By increasing the minimum film thickness, the filtering demands on the lubricating condensate are reduced and the surface finish of the journals and bearings is less critical permitting the journals and bearing to be finished by standard precision grinding techniques. In a specific embodiment of the invention, a cannister housing the turbine/generator is provided with a sump for collecting liquid working fluid which is delivered to the bearings through a cooler.

Abstract: A Rankine cycle turbine drives an electric generator and a feed pump, all on a single shaft, and all enclosed within a hermetically sealed case. The shaft is vertically oriented with the turbine exhaust directed downward and the shaft is supported on hydrodynamic fluid film bearings using the process fluid as lubricant and coolant. The selection of process fluid, type of turbine, operating speed, system power rating, and cycle state points are uniquely coordinated to achieve high turbine efficiency at the temperature levels imposed by the recovery of waste heat from the more prevalent industrial processes.

Abstract: A crossover conduit structure for transmitting steam from a first to a second turbine section having a conduit disposed between an exhaust portion of the first turbine section and an inlet portion of the second turbine section and a moisture removal structure situated downstream from the inlet portion axially along the conduit. The conduit's longitudinal axis is arranged generally perpendicular to the inlet portion's longitudinal axis with the moisture removal structure being disposed axially downstream from the inlet portion in the direction of the steam flow through the crossover conduit. The moisture removal structure includes a tapered transition section having first and second ends which are respectively disposed relatively adjacent and remote from the inlet portion, a pipe attached to the second end of the tapered portion, and an orifice or other means for regulating water and steam flow through the condensate pipe.

Abstract: Control device for a steam turbine having a high-pressure and a medium or low-pressure turbine part, includes a reheater, at least one live steam control valve disposed upstream of the high-pressure turbine part, at least one intercept control valve disposed upstream of the medium or low-pressure turbine part and downstream of the reheater, a control device having at least one turbine controller for simultaneously acting on the live steam control valve in accordance with a predetermined live steam valve characteristic and acting on the intercept control valve in accordance with a predetermined intercept valve characteristic, the live steam control valve and the intercept control valve having a normal characteristic correlation therebetween determining a correlation of high-pressure and medium or low-pressure steam mass flow, a limit detecting device associated with the high-pressure turbine part for responding when a predetermined thermal stress is reached in the high-pressure turbine part, and a positioning

Abstract: A side stream type condenser which has a first hot well for condensing steam exhausted from a turbine and storing the condensed water and a second hot well for storing the purified condensed water to prepare for water feed to a main system includes a partition plate for defining the two hot wells. The partition plate is formed with a weir portion so that part of the condensed water in the second hot well may overflow to keep a fixed water level. The weir portion is constructed in the shape of a labyrinth and is formed with a passage normally filled up with the condensed water, and a space in the upper part of the second hot well communicates with the upper space of the first hot well through this passage only. The condensed water in the first hot well is fed to a purifying system disposed outside, and is purified therein.

Abstract: A solution to the problem of excessive rotation loss heating in a bypass steam turbine has been provided by the introduction of a reverse flow of steam to the high-pressure section of the turbine during those operating periods in which such heating is of concern. The present invention is directed to a control system for automatically selecting either the forward or reverse steam flow regime as is most appropriate, depending on turbine and other related operating conditions. In a preferred embodiment, the control system includes means for selecting either a forward or reverse flow control signal to govern the steam admission control valves; means for controlling the reverse flow valve and having decisional logic for determining whether the reverse flow valve shall be open or closed; and means for controlling the ventilator valve and having decisional logic for determining whether the ventilator valve shall be open or closed.

Abstract: In a multicylinder steam engine, separate steam feed conduits between a steam distributor and steam inlet valves of the cylinders and a large volume steam chamber adjacent to an inlet of the inlet valves respectively to suppress a pressure pulsation in the feed conduits.

Abstract: In a power plant, a deaerator is a feedwater conditioning device which provides direct contact feedwater heating as well as providing for oxygen removal to inhibit corrosion. Under some conditions, called transients, rapid depressurization could occur in the deaerator which might result in damage to internal deaerator parts. By limiting the condensate flow into the deaerator, the rate of depressurization can be reduced. A control system is described which will react to a reduction in turbine load by reducing the flow of condensate to the deaerator.

Abstract: A butterfly valve is disclosed for use in controlling the flow of gaseous fluid under high temperature, high pressure conditions. The interior of the valve body has non-overlapping semi circular valve seats spaced to either side of the shaft for the valve disc. The valve disc is rigid and inflexible throughout and, when closed, its periphery terminates close to the interior of the valve body under all operating temperatures. When the disc is closed, the semi-circular valve seats cooperate with the recessed rigid periphery of the disc to form a chamber chargeable with purging fluid at a higher pressure than the fluid on the upstream side of the valve and effective to prevent flow of the latter past the valve disc.

Abstract: In a Rankine-cycle-engine-driven cooling-and-heating system comprising a power generating cycle including at least an expander, an oil separator, a condenser and a generator and a cooling-and-heating cycle including at least a compressor, an oil separator, a condenser, an expansion means and an evaporator, the housings of the expander and the compressor are so securely joined that a hermetically sealed space may be defined between them. This space is used as an oil separator which is common to both the cycles and is communicated with the outlet port of the expander and the discharge port of the compressor. As a result, the system can be made considerably compact in size as compared with the prior art systems in which the oil separator is disposed outside of the expander and the compressor.

Abstract: Improved method and apparatus for controlling thermal stress on component parts of a steam turbine while providing maximum loading and unloading rates during startup, shutdown, and other periods of load change. From monitored and derived quantities, a loading rate is calculated for each of a plurality of preselected turbine component parts and the lowest rate is selected for control. Simultaneously, and in concert with load change calculation and execution, the steam admission mode of the turbine is automatically directed to either the partial arc mode or the full arc mode as necessary to reduce stress as compared with a preselected and adaptive stress reference value.

Abstract: In starting a steam turbine plant of a combined plant including a gas turbine plant in addition to the steam turbine plant, a condensation system is controlled in such a manner that water retained in a deaerated water tank used in the steam turbine plant is fed to a gas turbine waste heat recovery boiler at steam turbine plant start-up, and the condensate recovered from the boiler is stored in a condenser and a condensate tank. Feeding of water from the condenser to a deaerator is initiated when the deaerator functions satisfactorily by using as a heat source the water at the outlet of a fuel economizer of the boiler.

Abstract: Method and apparatus to limit and control rotational loss heating such as occurs in a large steam turbine in the bypass mode of operation under no-load and low-load operating conditions. According to the invention, a portion of the high pressure bypass steam is admitted to the lower pressure sections of the turbine to provide motive fluid for driving the turbine while, simultaneously, a second portion of the high-pressure bypass steam is admitted to the high-pressure section of the turbine in a reverse-flow direction to pass backwards therethrough and limit the rotational loss heating. The two flows may be proportioned to control rotational loss heating in both the high-pressure and lower pressure sections of the turbine. A reverse-flow valve and a ventilator valve are provided for routing the reverse-flow of steam.

Abstract: Pollutants are removed from a hot industrial effluent after which enthalpy is recovered from the hot effluent by converting a working fluid into a foam in a flashing unit and using the foam to propel a turbine. For liquid effluents the effluent itself serves as the working fluid. For gaseous effluents the scrubbing fluid used to remove pollutants is used as the working fluid.

Abstract: A power generation system and method of operation for generating electricity by utilizing temperature differences inherently present in the ocean between water near the surface and water from the ocean's depths. A pump provides relatively warm, surface ocean water to a flash evaporator where a portion of the water is flashed into steam. The steam is expanded through a subatmospheric pressure range turbine which exhausts into a condensing enclosure. The steam exhausting into the enclosure is condensed by relatively cold ocean water pumped thereinto. The turbine drives a generator and thus produces the electricity. The turbine speed and generator output are controlled by selectively introducing atmospheric air and relatively warm water into the exhausted motive steam flow. Such selective introduction into the exhausted steam flow of air and/or relatively warm water increases the absolute pressure at the turbine's exhaust end and thus reduces steam flow through the turbine.

Abstract: This is a description of solar power plant having a plurality of modular units, which form improved heat exchangers by enhancement of heat transfer surfaces, through the action of wipers and the draining down of transfer surfaces. The whole structure is insulated by a film of lubricant, and a solar heater booster provides additional heating capabilities.

Abstract: An engine assembly that is powered by high pressure vapor from a volatile liquid that has a boiling point substantially below the minimum ambient temperature in the geographical location in which the engine assembly will be used. Heat for volatilizing the liquid may be withdrawn from the ground, naturally occurring sources of water, as well as from sunlight and waste heat from industrial installations. Although the engine assembly is capable of being used to produce power for any desired purpose, it is particularly adapted for use in pumping water from a well, with the pumped water not only being used for irrigation purposes and the like, but also to effect an initial cooling of the low pressure vapor discharged from the engine assembly prior to the vapor being further cooled and pressurized to return to the liquid state whereupon it is heated and recycled through the engine assembly.

Abstract: A steam power plant includes a nuclear reactor for generating a supply of steam. The steam is conducted to a first turbine which forms a high pressure stage of the steam power plant. A second turbine which is located downstream of the first turbine forms an intermediate pressure stage. Additional turbines may be arranged so as to provide still lower pressure stages for the power plant. To prevent corrosion, hydrogen peroxide is added to the steam immediately upstream of the first turbine. Additional hydrogen peroxide may be added immediately upstream of subsequent turbines. The hydrogen peroxide is added by spraying and is preferably supplied in a concentration of 25 to 50 parts per billion of steam. Preferably, the hydrogen peroxide is in a concentration of 1% to 5% prior to spraying.

Abstract: In a steam generating apparatus comprising a shell containing feed water introduced thereinto, and heating pipes submerged in the feed water contained in the shell for permitting a heating fluid of high temperature to flow therethrough, indirect heat exchange being effected between the heating fluid and the feed water in the shell through the heating pipes so as to evaporate the feed water, spray means for supplying condensate in atomized particles to the shell and means for separating moisture from the generated steam are mounted in a space above the feed water level within the shell.

Abstract: Steam flow and pressure conditions needed in a turbine to satisfy the speed and load demand of an electric power generating system are controlled by a programmed digital computer system during start-up, synchronization and load operation. Manual backup control is provided for the computer control. Throttle valve tests are provided under digital control and transfers are made to manual backup control if predetermined task errors occur.

Abstract: A process of removing water-soluble impurities from the working medium of a steam power plant is disclosed. Steam is bled from a high-pressure turbine downstream of the Wilson Line region. The steam is partially condensed, so that impurities in the steam are carried by the condensate. Moisture separators are disposed in the feed lines connecting the bleed lines with various heaters and the like. The bleed steam is supplied to the various heaters to heat the boiler feedwater and the working fluid of the turbine. The drains of the moisture separator are connected to a purification tank to remove the impurities from the condensate.

Abstract: The invention provides a method for operating a power generating assembly which assembly comprises a steam generator and a turbine, and said method comprises controlling the quantity of heat released by the steam generator by a signal which is representative of the difference between the predicted stresses which will exist at the instant to+T on that part of the turbine which undergoes the greatest thermal stress and the maximum permissible stress on this same part at the same instant, to being the present instant and T being a period of time close to the time constant of the power production assembly.

Abstract: This invention relates to a steam turbine system which utilizes a unique heat-absorbing lens-shaped heating plate and boiler for the production of steam.

Abstract: A small power plant utilizing waste heat wherein:an intermediate heat transfer medium being thermally stable and capable of lubricating bearings is interposed between a heat source and a turbine operating medium;heat of said intermediate heat transfer medium is taken off through a direct contact heat exchanger to change said turbine operating medium in phase from a liquid state to a gaseous state; anda portion of said intermediate heat transfer medium is supplied as the lubricant for the bearings of the turbine and generator.

Abstract: Radioactive emissions by reason of primary-liquid-to-secondary-liquid leakage in the steam generator of pressurized water reactor power plants are reduced by a demineralizer in the discharge from the blowdown tank and also by transmitting blowdown venting vapor to the condenser. For major failures resulting in power blackout an auxiliary turbine is provided. This turbine is connected to be energized by vapor (steam) by-passed from the main steam line. The auxiliary turbine drives the pumps which pump the cooling water for the condenser. The steam which drives the auxiliary turbine is also discharged to the condenser. The condensed water flows back into the steam generators where it is discharged through the blowdown tank.

Abstract: The invention comes within the field of heat engines which operate by means of a fluid which flows in a closed circuit. A device characterized by the fact that the engine is placed in a sealed chamber and that its output shaft is coupled to a transmission shaft which does not undergo any bending stress, having a seal where the transmission shaft passes through the chamber, the seal being permanently in contact with a lubricant during operation and when the engine is stopped. The invention applies in particular to isolated low or medium power engine installations which require only slight supervision.

Abstract: Apparatus and method for automatically determining and indicating that the rotor of a steam turbine has attained a predetermined minimal temperature. Means are utilized for measuring axial dimensional changes of the steam turbine cylinder and rotor due to an increased temperature and summing pertinent axial dimensional changes thereby determining the axial expansion of the rotor which in turn, through known physical properties of the rotor material, corresponds to a temperature increase. This increase of the temperature added to the initial temperature of the rotor provides the total temperature, and upon the total temperature reaching a predetermined value, the steam turbine is available to be brought up to speed and loaded.

Abstract: A control loop for regulating the magnitude of a variable quantity of an apparatus to a reference value, for example the steam pressure in the output line from a boiling water reactor, wherein the instantaneous magnitude of the steam pressure is compared with a reference value and the difference therebetween is used to regulate a valve in the steam line in such manner as to eliminate the difference. The control loop also includes one resonance filter for the regulating medium whose resonant frequency coincides with the frequency at which the control loop, in the absence of such a filter, would become unstable.

Abstract: The invention concerns a feedback control method for controlling the starting of a steam turbine unit comprising a reheater, a turbine by-pass system consisting of a HP-by-pass system and a LP-by-pass system, at least one regulating valve for the HP-by-pass system, at least one regulating valve for the LP-by-pass system, at least one inlet valve for the HP-turbine, at least one intercept valve for the MP/LP-turbine and a governing device to regulate the turbine speed or power output, according to which method during no-load and low-load operation and up to a predetermined partial load the pressure within the reheater is regulated by a first feedback control device with the LP-by-pass regulating valve acting as positioning element in such manner that a greater quantity of steam will flow through the HP-turbine than through the MP-turbine, and a smaller quantity of steam through the HP-by-pass system than through the LP-by-pass system, whereby a maximum permissible HP-exhaust steam temperature will not be excee

Abstract: An improved high-water-level trip control for a steam turbine is disclosed. Instead of causing a trip of the turbine (or reactor) based merely on the water level in the steam generator, the present invention generates a trip command that is based on a function of more than one parameter. Such a function more accurately indicates the quantity of water droplets in the steam leaving the steam generator than a function of a single parameter does. In particular, it is disclosed to trip the turbine when the water level exceeds a variable reference that increases as steam velocity decreases; this takes into account the effect of steam velocity on the entrainment of water droplets by the steam.

Abstract: At the point of time to when the turbine speed has come up to a first speed N.sub.1, a thermal stress expected in the turbine when the speed is increased to a second speed N.sub.2 at a rate .alpha..sub.1 is presumed. Thermal stress .sigma..sub.s(t) -.sigma..sub.sT1 at the point of time t.sub.o1 for commencing acceleration to the second speed N.sub.2 is then obtained, which point of time t.sub.o1 would never cause the maximum value of the presumed thermal stress to exceed a predetermined limit .sigma..sub.sl of the thermal stress when the turbine speed is increased at that rate. Then, a length of time T.sub.w1, referred to as a warming time, is determined which is required for the thermal stress .sigma..sub.s(t) to decrease to the level of (.sigma..sub.s(t) -.sigma..sub.sT1) when the warming is continued after the point of time t.sub.o. Subsequently, a length of time (N.sub.2 -N.sub.1)/.alpha..sub.1 required for increasing the turbine speed from N.sub.1 to N.sub.2 at the rate .alpha..sub.1 is calculated.

Abstract: A vapor generating system for use in a power plant having a steam turbine and a condenser connected in a series flow relationship, in which a vapor generating section receives a heat exchange fluid and passes the fluid in a heat exchange relation to a source of heat to raise the temperature and pressure of the fluid to predetermined values. The vapor generating section operates at substantially constant pressure during start-up and a pressure control station is provided which includes one or more relatively small bore tubes, a first conduit having control means disposed therein, and a second conduit, through which fluid passes before it is passed to a plurality of separators in the main flow path which receives the fluid and separates same into a liquid and a vapor. The separators are connected to a vapor circuit and to a liquid circuit for passing the vapor and liquid to the turbine and heat recovery or condenser, respectively. A method of starting up a vapor generating system in a power plant.

Abstract: A steam turbine control system comprising a primary and an auxiliary manual turbine controller, each said turbine controller including a set of valve position setpoint controllers for close-loop control of the turbine steam admission valves, is disclosed. Each valve position setpoint controller operates, at times, on a position error signal to generate a valve position control signal which controls the rate of valve position movement of a corresponding turbine steam admission valve. The steam admission valves are closed-loop controlled by a selected set of said primary and auxiliary valve position setpoint controllers. The set of valve position control signals corresponding to the selected set of position setpoint controllers are coupled to their respective turbine steam admission valves for controlling the rate of position movement therein. The valve position error and position control signals of the unselected set of said controllers are maintained at approximately zero potential.

Abstract: In the improved supply circuit, provision is made for a "start-up" storage tank placed at a higher level than the heat exchanger and connected to a secondary circuit in portion of this latter which is located between the solar engine and the feed pump and includes the evaporator. The storage tank is equipped with heating means for bringing the fluid contained therein to a temperature which is lower than the temperature of the fluid within the evaporator.

Abstract: A gear is mounted to a turbine shaft and a pin disposed on a vertical link for engaging the gear when the link is pulled up for breaking loose a turbine shaft or other machine shaft which has been at a standstill.

Abstract: A geothermal energy recovery system of improved life duration makes use of thermal energy stored in hot, solute-bearing well water as it is pumped upward to the earth's surface through an extended heat exchange element for continuously heating a downward flowing organic working fluid to a supercritical state. Some of the energy of the latter fluid is used within the well for operating a turbine-driven pump for pumping the hot well water at high pressure and always in liquid state to the earth's surface, where it is reinjected into the earth in a second well. After driving the deep-well turbine-driven pump, the organic fluid still in supercritical state arises toward the earth's surface in a thermally insulated conduit; at the earth's surface, vapor turbine electrical power generation equipment is driven by the ascending organic fluid, after which it is returned into the well for re-heating in the extended heat exchanger.

Abstract: In an ocean thermal energy conversion system utilizing solar energy stored as heat in tropical waters to generate electricity, the evaporating and condensing functions of the heat exchangers are interchanged in order to prevent the accumulation of micro-organisms on their surfaces. The surfaces of the heat exchangers are also mechanically brushed or scraped so as to remove any thin films of microbial slime. In order to remove additional micro-organisms from the surfaces of the heat exchangers, the flow of hot and cold sea water through each of the heat exchangers is interchanged preferably on a daily basis. Thus, micro-organisms from the warm surface waters that attach themselves to one heat exchanger surface will be destroyed by the cold water that flows through that heat exchanger on the next day. On the other hand, the organisms that live in the cold water at great depths cannot survive the next day's warm water environment which is caused by alternating the flow to the two heat exchangers.

Abstract: A method and apparatus for testing the movability of a valve plug. The invention provides for movement of the valve plug from a first to a second position, from the second to a third position in an opposite direction, and again in the first direction to the first position. Indicators are provided to ascertain if such movements have occurred. Alarm signals are generated if any of the movements do not occur. The magnitude of the motions of the plug is normally small relative to the full valve stroke. Size of stroke and time at each position are chosen to minimize any disturbance to the power system.