(a) General Discussion.-The distilling plant is a low-pressure, double-effect, single-shell, submerged-tube type with a rated capacity of 12,000 gal. per day of distillate having a chlorine content not exceeding one-fourth grain per U.S. gallon with first-effect steam at a pressure not exceeding 5 p.s.i. gage, distilling condenser vacuum 26 inch Hg., and brine overboard discharge density 1 1/2 thirty-seconds. The double-effect unit consists of a horizontal cylindrical shell containing the evaporating units, vapor feed heater, distilling condenser, baffles, vapor separator and associated fittings. A vertical wall divides the two chambers. The first-effect chamber contains the first-effect evaporating unit, the vapor feed heater and a vapor separator. The second-effect chamber contains the second-effect unit, the distilling condenser and a vapor separator. Distilling condenser vacuum is maintained by a single-stage air ejector discharging into a condenser cooled by evaporator feed. Automatic control of the tube drains is maintained by externally mounted drain regulators.
(b) Cycle of Operation.-The distilling condenser circulating pump takes a sea suction and discharges through a distillate cooler to the cooling passes of the distilling condenser and then overboard. The evaporator feed pump takes its suction from the overboard discharge line and discharges the feed through the heating passes of the distilling condenser, through the air ejector condenser, vapor feed heater and to the first-effect chamber. The pressure differential between the first- and second-effect chambers allows the feed to flow from first to second effect. The brine is continually discharged overboard from the second effect by the brine discharge pump. Steam for the first-effect tubes is obtained from the auxiliary exhaust line through a reducing valve. The first-effect tubes drain through a drain regulator to either the ship's condensate system or to the L.P. drain tank. Vapor from the first-effect passes through a series of baffles and a vapor separator to the vapor feed heater, and through an external
pipe to the second-effect tubes. Second-effect tubes drain through a drain regulator to a flash chamber where its pressure is reduced to that of the distilling condenser. The resulting flash vapor discharges to the distilling condenser, and the remaining distillate drains to the evaporator condensate pump. Vapor from the second-effect passes through baffles and separator to the distilling condenser. Distillate from the condenser combined with the flash chamber drains goes to the condensate pump which discharges it through
the distillate cooler to the test tank from which it is pumped to feed or ship's tanks. The first and second-effect tube nests have vent connections through controlling valves to the second-effect shell. Electrical salinity cells are fitted in the first and second-effect tube nest drain lines, the distilling condenser drain, the fresh water pump discharge and in the air ejector condenser drain. Following is a brief description of the major units in the distilling plants:
(e) Evaporator.-Tube bundles are of five-eighths-inch outside diameter tubes arranged for two passes of the heating steam. Expansion of the tube nest is provided for by supporting the back tube sheet and the intermediate supporting plate on rails in the shell.
(d) Vapor Feed Heater.-The vapor feed heater is of the straight tube type with five-eighths-inch outside diameter tubes expanded into a tube sheet at each end and supported by an intermediate support plate.
(e) Distilling Condenser.-The distilling condenser is of the straight tube type with five-eighths-inch outside diameter tubes. A portion of the distilling condenser is arranged by means of a suitable baffle to serve as a precooler for the air going through the air ejector suction. The circulating water makes two passes through the condenser before discharging overboard. The portion of the circulating water needed for feed is pumped from the overboard line by the feed pump and discharged through a separate connection back to the condenser where it makes three more passes before discharging to the air ejector condenser.
SOLOSHELL LOW PRESSURE DISTILLING PLANT
(f) Air Ejector Condenser.-The air ejector condenser is of the straight tube, counterflow type with five-eighths-inch outside diameter tubes. The air ejector steam makes five passes through the shell, and the feed makes three passes through the tubes.
(g) Air Ejector.-Two air ejectors are provided, one for operation and one for spare. The ejectors are of the single-stage type with the gases entering the inlet of the ejector at the mixing chamber being entrained with the steam from the nozzle and being carried through the diffuser where they are compressed to atmospheric pressure. From the diffuser the gases are discharged into the after condenser in which the heat is absorbed by the evaporator feed.
(h) Flash Chamber.-The flash chamber is a receptacle in which the second-effect drains are reduced to a pressure and temperature corresponding to the distilling condenser vacuum. It is attached to the second-effect side of the evaporator shell.
(i) Tube Nest Drain Regulator.-The first-effect tube nest drain regulator is of the external valve, ball float type. The valve is located in the discharge line of the drain pump and is provided with a bypass valve for operation if the regulator becomes inoperative. The tube nest drain regulator for the second-effect is of the piston type balanced valve with ball float. The regulator can be locked open and manual control of the drain level is then accomplished.
(j) Distillate Cooler.-The distillate cooler is of the straight-tube type with five-eighths-inch outside diameter tubes. The distilling condenser circulating water serves as the cooling medium for the condensate.
(k) 4,000 Gallons Per Day Plant.-In addition to the 12,000 gallons per day distilling plant in the forward engine room, the D1D692 class ships have a 4,000 gallons per day plant installed in the after engine room. This plant is similar in all respects to the 12,000 gallons per day plant described, differing only in size and capacity.
(l) Corn Starch-Boiler Compound Injection System.-By Shipalt DD447 the installation of a cornstarch-boiler compound injection system and a fixed internal spray pipe in the first-effect shells (for cold shocking the coils) was authorized for all destroyer distilling plants.
2. REFRIGERATING PLANT
The refrigerating cycle is essentially composed of four steps: (a) compression of Freon gas by
a motor-driven compressor, (b) condensation of the gas by water-cooled condenser, (c) expansion of liquid refrigerant by thermal expansion valve, and (d) evaporation of low-pressure liquid refrigerant by absorption of heat in evaporators. The compression of the refrigerant gas permits condensation at the temperature of the condensing water. The refrigeration is accomplished by expanding and evaporating this liquid refrigerant. The absorbed latent heat of evaporation and superheat is removed from the refrigerant gas by again compressing and then condensing to the liquid state. The process is repeated continuously. Freon is a noncombustible, nontoxic, nonirritating, nonexplosive, noninflammable, noncorrosive refrigerant which is a liquid when under a 75 p.s.i. pressure. It is shipped as a liquid under pressure in steel cylinders. The refrigerating equipment consists of three essential parts:
(a) Compressors.-Two Carrier 7H5 Freon compressors, either of which can carry the entire load, are installed. The other compressor is used as a spare. They are vertical, reciprocating, single-acting, multiple V-belt driven by a two-speed 7 h. p. motor. Each compressor has a capacity of 2 tons of refrigeration per 24 hours.
(b) Condensers.-Each compressor is provided with a separate water-cooled Freon condenser. A separate refrigerant receiver is provided for each condenser, and these receivers serve as a reservoir for load surges. A water regulating valve is provided in the condenser water inlet and is actuated by the Freon head pressure in the refrigerant inlet line to the condenser. This automatically regulates the flow of condensing water to the condenser. A water pressure failure switch is provided in the condenser water inlet line to the condenser which stops the compressor in case of a failure in condenser water supply and permits the compressor to start again when water pressure is restored.
(c) Evaporators.-The refrigerated compartments are provided with 1 5/8 inches outside diameter copper tubing coils which contain sufficient cooling surface to maintain the following temperatures:
Meat room, 15 degrees.
Butter-Egg, 32 degrees F.
Fruit-Vegetable, 40 degrees F.
Vestibule, 40 degrees F.
Ice Set, 15 degrees F.
ELECTRO-HYDRAULIC STEERING GEAR
Separate circuits are provided so that all any one circuit may be cut out without interfering with the remainder. The refrigerant cycle operates in general as follows: The compressor withdraws the gaseous refrigerant from the evaporators and delivers it to the condensers which extract heat from the refrigerant and condense it to a liquid. The cooled liquid under pressure flows to the refrigerated compartments in which a reduced pressure is maintained in the coils, which causes the liquid to evaporate and to absorb heat from the air or bring it in contact with the cooling coils. The liquid refrigerant is passed through a thermal expansion valve before entering the cooling coils. The thermal expansion valves control the quantity of liquid refrigerant that passes to each circuit and maintain a constant degree of superheat of the gas leaving the evaporators. thus preventing liquid refrigerant from surging back to the compressor. The solenoid refrigerant valves actuated by temperature control switches cut off the supply of liquid refrigerant to the thermal expansion valves when the refrigerated compartments reach
the desired temperature. Suction pressure regulating valves are used in the compressor suction lines from the 32 degrees F. and 400 F. rooms to prevent excessive difference in temperature between the compartment and the refrigerant in the evaporators which would result in dehydration of the materials stored. Other features of the refrigerating system include high- and low-pressure control switches, strainers, dryers, and an external relief valve.
3. STEERING ENGINE
The steering gear is of the hydroelectric, Rapson slide and follow-up type. It is equipped with a full storage motion control unit. In consists essentially of a ram working in two cylinders, and connects hydraulically to two variable-stroke Waterbury pimps either of which may be in operation. The ram operates the rudder through a tiller fitted with sliding blocks. Remote control of the steering gear is accomplished by a Westinghouse Electric transmission system. The steering stand in the pilot house includes a synchronous control transmitter to control a synchronous
receiver located in the steering gear room and geared to the pump stroke control rods. The receiver is geared to, and actuates one end of the differential control unit, the other end of which is operated by the movement of the rudder. This movement is taken from the tiller through gears. and is uniform at all rudder angles. Direct local steering control is provided in the steering engineroom by a disk type trick wheel. It is the differential control unit which establishes a single and common control of the follow-up, full storage motion type for the pumps so that the stroke of each may be varied locally and remotely. The full storage motion feature allows the control to lead the rudder by the full amount of rudder travel from hardover to hardover, or, in other words, makes it possible for the rudder and control to be out of step by the full rudder travel without damage to either the control or follow-up. Each power plant consists of a continuously running Westinghouse gear motor connected through a flexible coupling to a Waterbury variable stroke hydraulic pump. Emergency steering is accomplished by means of two hand cranks. These cranks drive the port pump by means of gears and roller chains. When the cranks are in use, steering control is accomplished in two ways, one of which is by use of the trick wheel while the cranks are being turned continually over the top toward the plunger unit. The other results from putting the pump on a fixed stroke and turning the cranks in either direction according to the rudder motion desired. A pump control hand lever (keyed to the pump control shaft which in turn carries levers controlling the pump stroke) is normally pinned to the differential control lever. To put the pump on a fixed stroke the locking pin is drawn and used to lock the lever to a fixed quadrant on the other side of the shaft at 20, 40, or 60 percent of the full stroke of the pump. A six-way plug cock installed in the pressure piping between the pumps and the cylinders and controlled by a hand lever permits hydraulic connection between the cylinders and the pump in service and automatic by passing of the idle pump. Lugs on the plunger contact renewable copper crushing pieces on the tie rods when the rudder reaches the 35 1/4 degrees angle and cushion the shock before contact is made with positive steel stops which limit the angle to 36 1/2 degrees. The steering gear is protected from abnormal stresses by a relief valve set for an oil pressure 10 percent plus 50 p.s.i. higher than the maximum
normal. A shuttle valve, the double function of which is to vent the hydraulic system and also act as a means of replenishing the oil supply, is installed at the highest point in the pressure piping. It is connected to the expansion tank which in turn has connections to the main pumps for the purpose of oil circulation and also to a hand pump for filling the system from the storage tank. The motors, pumps, differential control unit, synchro-tie receiver, hand crank stands, trick wheel stand, transfer valve, shuttle valve, expansion tank, and their respective assemblies are mounted on a common bedplate which is so constructed as to make an oil storage and drain tank for the hydraulic system.
DD692 Class.-Since the DD692 class is equipped with a double rudder, the connection of the ram to the tillers of the rudders is different from that shown for the DD445 class. Two tie rods lead from the rain cross head to each of the tillers which are located outboard of each end of the ram. Thus, a motion of the cross head is transmitted simultaneously to both tillers.
4. EMERGENCY DIESEL GENERATOR
The emergency Diesel generator set includes a 2-cycle, 3-cylinder General Motors Diesel engine; a 100-kw. 0.60 or 0.80 p.f. 450-volt, 3-phase, 3-wire, 60-cycle, 1,200 r.p.m. A. C. generator; a 2.25-kw., 120-volt, 1,200-r.p.m. D.C. exciter, directly connected to the generator; a voltage regulator for regulating the voltage of the A. C. generator; a generator field discharge resistor; an exciter field rheostat, and one engine starting motor control equipment. The 6 1/2 x 7 Diesel engine has a unit injector, a self-contained hydraulic governor, and four attached pumps, namely: A Northern fuel oil pump delivering 0.8 gallon per minute at 1.906 r.p.m., and 40-50 p.s.i. discharge pressure, a General Motors lubricating oil pump delivering 24 gallons per minute at 1,200 r.p.m.. and 35-40 p.s.i. discharge pressure; an Ingersoll Rand pump delivering 85 gallons per minute of sea water at 2,492 r.p.m.; and an Ingersoll Rand fresh water pump delivering 50 gallons per minute at 2,492 r.p.m. Following are some of the more important features of the Diesel engine: The injector is of the unit injector type in which the spray valve and pump are made up into a single, compact unit, and each engine cylinder is provided with a complete and independent injection system. The injector is seated in a tapered hole
in the lower deck plate of the cylinder head and is guided in the upper deck plate by a short land on the spray valve nut. A holding-down clamp secures the injector in the cylinder head. The cylinder load is controlled by a rack which extends horizontally from a guide bore in the injector body. A rack adjustment on an injector control link connection permits regulating the load of each cylinder while the engine is running. The injector plunger is operated through a constant stroke by a rocker lever from the injection cam on the main cam shaft. The engine speed is held uniform for any setting of the governor. The movements of the governor power mechanism are transmitted through lever and link connections to an injector control shaft. When the engine speed becomes excessive, an overspeed trip mechanism stops the injection of fuel oil into the combustion chambers. The camshaft gear is fitted with a spring loaded flyweight. Centrifugal force moves the flyweight against the spring, until at the overspeed the flyweight trips a latch, releasing a spring-actuated injector lock shaft in the cam pocket. The overspeed trip is manually reset with a hand lever. A long shaft through the crankcase transmits power from the camshaft drive to another gear train which drives the blower, the two cooling water pumps and the lubricating oil pump. The engine blower consists of a pair of toothed rotors revolving together in a closely fitted housing. The air enters the housing at one side and is carried around the cylindrical sides of the housing and is discharged under pressure at the other side through a discharge manifold into the air chamber of the engine. The two centrifugal water pumps are mounted below the blower. One pump forces jacket water through the closed cooling system of the engine. The other of the two pumps forces sea water through the lube oil cooler and then through the jacket water cooler. Water is delivered to this sea water pump either from the booster pump located in the ice machine room or from the fire main through a thermally operated valve. This thermally operated valve is actuated by the jacket cooler temperature and thereby supplies water from the fire main in case the normal supply fails and the cooler temperature rises. The flow of fresh water to the jacket from the fresh water pump is controlled by a temperature regulating valve which maintains a constant temperature in the jacket. Fuel oil is supplied under pressure to the injectors by a pump which is of the positive
displacement type with spur gear rotors and is driven from the camshaft gear train. The pump draws fuel from a supply tank, forces it through a filter to the fuel supply manifold, and delivers it through individual cylinder filters to the injector where surplus fuel is bypassed. Injector drainage returns to a separate manifold in the multiple oil pipe assembly. A constant pressure is maintained in the fuel supply manifold. The lubricating oil pump is of the positive-displacement, helical spur gear rotor type, and draws hot oil from the oil pan and delivers it through a strainer, relief valve, filter, and cooler to the engine lubrication system. The engine is automatically started when the voltage of the ship's service supply falls below 350 volts in the DD445 class or 290-volts in the DD692 class. When the engine starts firing the starting motor is unloaded and is disconnected from the battery. Normal operating conditions call for lubricating oil temperature of 165 degrees F., a jacket water temperature of 160 degrees F., and cylinder temperatures of 660 degrees F. at 100 percent load and 750 degrees F. at 125 percent load.
The emergency Diesel generator must be lined up at all times to start automatically when the normal power voltage on both ship's service switchboards falls to 350 volts in the PD-MS class or 290 volts in the DD692 class. Under all circumstances the salt water booster pump, connected with the engine, should be lined up to start automatically as soon as the switchboard is energized. The fire main should never be depended upon to furnish salt water service except in case of a casualty to the booster pump. It should be established routine to start the Diesel generator automatically at least twice a week. When this is done it must be insured that the salt water booster pump is NOT primed from the fire main.
DD692 Class.-The DD692 class is furnished with two of these Diesel generators, one located forward and the other aft. The forward one is connected for automatic starting to the forward ship's service hoard, and the after one to the after board. A description of the electrical hookup for both classes appears in section XII. The after Diesel generator in this class is equipped with a salt water booster pump similar to that in the DD445 class, but the forward Diesel generator is equipped with a Nash type self-priming pump in lieu of the salt water booster pump.