Document 15Jok7e9MRbrMwJdKEbXYjOBX

Steam turbines are now driving gas compressors at Station No. 7 of the Transcontinental Gas Pipe Line Corp. This new plant has three steam generators, three turbine compressors, two turbine generators and auxiliaries to make up a compact package unit N. W. LASSITER, Compressor Stations Div., Transcontinental Gas Pipe Line Corp. COMPRESSOR STATION No. 7, located near Tylertown, Missis design engineers in a manner that was an unusual departure from the accepted sippi, is one of three Transcontinental transmission pipe line practice. Gas Pipe Line Corporation's steam-tur Possible advantages in such a design bine driven centrifugal compressor sta over she conventional reciprocating en tions that were rat into operation dur gine type compressor station are: (1) ing the summer of 1951. lower installation cost per horsepower While steam turbines have been uti through the elimination of massive en lized extensively during the last half gines ansi foundations for the prime century for utility and industrial in movers. (2) elimination of reciprocat stallations, they have never before been ing parts with resulting minimum employed as prime movers tor gas com wear, vibration and pulsating gas flow, pressor stations. At Staton No 7. and (3) reduced operating personnel. steam boiiers. cer.irilust.il compressors Although tuel gas consumption will be ansi .steam :urhu'.r< were 1 n>:a!led in the diglr.U ure.fer die s;;.-.m-turbine. Cen trifugal compressor station should be favorable from the standpoint of total operating and fixed charges. The compressor station is made up of two mam structures, the power plant and the compressor building. The power plant partially houses three auto matically fired boilers together with two S00 kw generators, which furnish current tor auxiliary equipment. The compressor building houses the three turbine-dmen blowers, each ot which *" car. develop approximately 5000 hp under full load. In. aer, mot to the two principal INDUSTRY AND i'OWYR Marsh RS-000133 1/17/02 mi iprtps 67 buildings, the station has a water-treat age unit and is provided with a hy the centrifugal compressor without ing building--which houses equipment draulic servomechanism through which harm, thus eliminating the need for capable of furnishing a maximum of the steam admission valves are oper gas scrubbers. The combination of 20 gpm demineralized water--meter ated. This hydraulic servomechanism compressor station characteristics... is and regulator building, a combination acts in response to either of two gov such that discharge gas temperature is office, shop and warehouse building, ernors. The primary governor consists not high enough to damage pipe coat cooling tower and water storage facil of discharge pressure regulator. The ing or cause undue stress in the pipe ities. secondary governor consists of an oil wall. Thus gas scrubbers and cooling Principal Equipment pump driven from the turbine shaft facilities that are required at recipro extension. The control system is de cating engine stations were eliminated Equipment consists of three boilers, signed so either the primary or second at this station. three multistage impulse condensing ary governor will control, depending steam turbines, driving three cen upon which governor is calling for the Lube System trifugal gas compressor units, with slower speed at the time. In addition Each turbine compressor unit has a horizontal, two pass condensers; two to the primary and secondary gover combination closed pressure oil system, horizontal shaft, multistage steam tur nors, each turbine is provided with a which actually comprises several inde bines driving a-c generators; one throttle trip valve and an overspeed pendent systems all interconnected. Oil 140,000 lb per hr spray type vertical governor. is normally fed to the various bearings shell deaerating feedwater heater; one water demineralizer; and a cooling Cooling Unnecessary and control devices by the main oil pump, which is driven from the tur tower. Compressors are identical in all re bine shaft extension. The oil rcscr Gas pumping equipment comprises spects. Each is a horizontal single voir is a covered 500 gal tank mountcc three identical turbine compressor units stage, single suction machine with a along the turbine under the flooi for series operation. Each unit consists 24 in. suction inlet and 20 in. discharge plates. One section of the tank is par of an overhung, single stage, centrif outlet. Dust particles and liquid en titioned off and baffled for degasify ugal compressor directly driven through trained in the gas are passed through ing oil returned from seal oil leakage a spacer type flexible coupling by the impulse turbine, which exhausts into the surface condenser. The condenser box structure forms the support for the turbine compressor components. Turbine generator Desuperheater Feed Pumps These three units are equipped with a common pressure control system that functions primarily to maintain con Air | removal\ eductor. stant station discharge pressure. It also serves to divide the load equally among the three units, thereby enabling each unit to operate in its most efficient range. With all three units operating, the station is designed for an inlet pres sure of approximately 520 psia and a discharge pressure of approximately 800. Design capacity' is 603.10 MM standard cu ft per day at 60 F and 14.73 Excess steam condenser C/eon condensate sump psia pressure base. Flow diagram of operation indicates that the system has an exception- Each turbine is designed as a pack ally good steam balance. Only one per cent makeup water is required os as-00013* INDUSTRY AND POWER ' March. 195 1/17/01 NUECES .i v Turbines are provided with a hydraulic servomechanism : that limits the steam through a proportioning valve These surface condensers acf as a structural founda tion for each of the turbine-compressor components An auxiliary oil pump sends oil from the reservoir through a. check valve into the discharge line of the ipain oil pump. Rotating speed is con trolled by a pressure governor, and an oil pressure of approximately 70 psi is maintained in the main oil system. At this pressure a sufficient amount of oil is passed through the accumula tor to lubricate the unit during starting and stopping operations. As soon as the main oil pump reaches a speed at which 75 psi pressure is developed in the main oil system, the pressure gov ernor shuts off the steam supply to the turbine driving the auxiliary oil pump. Should the main oil pump be shut down for any reason, the pressure gov ernor will admit steam to the turbine driven auxiliary oil pump so as to maintain pressure in the oil system. Overspeed Control Lubricating oil is also employed to shut down the turbines in case of over speed and to seal high pressure gas in side the cases of turbine blowers. Oil for sealing gas in the blower case is supplied by a separate motor driven gear pump, which takes suction from the lubricating oil system. This oil circulates through the seal and bearing nearest the impeller at a slightly higher pressure than that of the turbine blower gas. thus providing a positive control of blower leakage. Bearing Lube A turbine driven auxiliary centrif ugal oil pump is provided that sup plies oil to the various bearings and control devices whenever the delivery ot the main oil pump is insufficient for the operating requirements. The turbine wheel and pump impeller are mounted on a common shaft and the casings and supporting trame built one Boiler house control panel Indicating and recording Instru ments, which keep a constant record of all power generat ing data 411 the condenser water circulating pumps are turbine driven. Water cir culation is controll ed by constant pres sure instruments in these condensers INDUSTRY AND POWER March, 1932 RS-000136 1/17/02 NUECES 69 Oil cooler, left. Is part of o combination pressure oil unit for the turbine-compressor that operates at 75 psi into another so as to form a single unit. Boiler Capacity Each boiler is capable of delivering 48,000 lb of steam per hr for short period operation and 43,000 lb per hr for continuous operation at 625 psig and 750 F TT. Since demineralized feedwater is utilized, the designers made every effort to recover as much steam and condensate as possible. As a result, the total makeup for this sta tion is approximately one per cent of the boiler steam flow. This power plant was designed with as many automatic features as practical in order to minimize operating labor. Fuel gas and air supplied to toe fire box and feedwater supplied to toe boiler are automatically adjusted to varying load conditions in order to maintain constant steam pressures. Greater fuel economy can be achieved with this automatic control than by . hand operation. Steam Control An indicating pressure controller located in the outgoing steam supply line is the master instrument in this hookup. Any fluctuation in load con ditions is first indicated by a steam pressure change. Thus, the pressure controller performs the first step in adjusting boiler output to the load. For example, a sudden increase in load will cause a decrease in steam pressure. The instrument will auto matically increase the flow of fuel gas and air to the combustion chamber. Additional combustion causes increased pressure in the firebox, and the in duced-draft damper is automatically opened, allowing combustion products to flow' to the boiler stack. An auto matic valve allows more feedwater to flow to the boiler to compensate for Air ejector equip ment for each sur face condenser is Identical. All pri mary pumping units are driven by means of steam turbines increased steam demand. As more steam is generated, a controlled amount of water is fed to the de-superheater to maintain temperature. Thus the boiler automatically adjusts itself to the in creased load conditions. As a result of the extensive automatic design, only one man is required to operate the en tire power plant. These are some of the basic features of the first steam-turbine driven centrif ugal compressor installation in the natural gas pipe line industry. The sta tion has not operated for a sufficient length of time to evaluate the merits of this type of equipment as compared with other prime movers. Extensive studies are being made now and such comparative information will be avail able for publication in the future LIST OF PRINCIPAL EQUIPMENT Boilers. Gas compressor........................ Gas compressor steam turbine Gas compressor condenser Generator................................ Generator steam turbine Feedwater heater. Demineralizer . Cooling towers ... Gas pressure controls RS-000136 1/17/02 NUECES Riley SfoVer Corp. Dc Laval Steam Turbine Co. Do Laval Stesm Turbine Co. Allis-Cholmers Mfg. Co. Ideal Electric & Mfg. Co. De Lava! Steam Turbine Coi Elliott Co, Cochrane Corp, The Marley Co. Askania Regulator Col 70 INDUSTRY AND POWER March. 1952