Steam & Power Forum RSS Welcome to the steam & power forum, a bulletin board dedicated to power & heating plants, boilers, turbines, steam, HTHW, pressure vessels, HRSG, piping and condensate, combustion including ASME questions and more. 5/27/2018 7:43:15 AM Poppy at Steam & Power Forum RSS 64 150 Re: silica in condensate - By: Jim Watts [764] Your configuration implies a very high pressure boiler and turbine.<br />You do not say your silica after poishing is high at start of run or at end of run so I will assume it is continuous slippage.<br />Although it is possible to imagine multiple problems to cause this it is unlikely your operation would have more than one and it needs to supply silica and at the same time degrade your polisher.<br />I would check your regeneration acid and caustic has not had a change of quality and contains silica. <br />High slippage can also be due to organic fouling of the anion resin or poor mixing of the mixed bed but you should not have silica in the first place.<br />Checking silica before the mixed bed should confirm this.<br /> Mon, 21 May 2018 09:34:00 -0300 Re: silica in condensate - By: Murphy [21] It seems to me that if your condensate polisher is upstream of of your make up water then you have a leak. I think you are going to have to sample the water at each component or heater in the condensate system from the hot well to the condensate polisher to find the source of silica. Seems your infiltration of silica is from your brackish water, which I think you are located where salt water meets the mouth of a river.<br /><br />I also think you should be measuring the silica in the steam going to the steam turbine generators. It will be problem if you are loosing steam turbine thermal efficiency.<br /><br />Murphy Thu, 17 May 2018 08:54:00 -0300 Re: silica in condensate - By: Ross Burns [390] I am not sure what your makeup water arrangement looks like, but if you are using ACF -activated carbon filtration- then I can guess that you have a RO reverse osmosis unit inline with it too. As I expressed earlier I am not sure how the ACF applies, except you are either recycling effluent back into the plant for the boilers or you are drawing water from a river or body of water that needs pretreatment of the boiler makeup water because of what is in the water source. So, I can imagine that the source of your Silica SO2 or Silicates SO3 is from the same pretreatment sources. Of course this makes the assumption you have no leaks in your surface condenser if you have one.<br /><br />Basem Belal has asked a very good set of questions to take the guess work out of the answers. Maybe you can answer his questions.<br /><br />Ross Tue, 15 May 2018 09:04:00 -0300 Re: silica in condensate - By: Basem Belal [2194] better to tell us how much the silica in the steam? what is the purpose of your steam? is it for steam turbine? how much P &amp; T ? do you have one boiler or more? are they connected together by saturation steam in any line? <br />any details will help more. Mon, 14 May 2018 01:00:00 -0300 silica in condensate - By: Shareef luberef [2259] We have problem with silica 39PPB+ in condensate polishing package outlet. We use ACF and a mixed bed strong acid/base exchanger. Still silica level is high. can u suggest method to control the silica. We use Desalinated water conductivity 5us/cm max. feed to our DEMIN unit to produce demin. water conductivity 0.1 us/cm max.<br /><br />can u help me to find the source and control measures? Sat, 12 May 2018 21:48:00 -0300 Re: Centrifugal Pump on Subcritical Boiler forced circ - By: Ross Burns [390] The impeller on a centrifugal pump that you describe can produce a pressure head of 275kpa or 40-psi above the inlet pressure of the pump. So, if you have two-impellers in your centrifugal pump then 40-psi + 40-psi is 80-psi, so the centrifugal pump would pump out 2030-psi + 80-psi to equal 2110-psi. Likewise, if you had a inlet pressure of 1000-psi and the centrifugal pump produces a head of 40-psi then the output or discharge pressure will be 1040-psi. As Basem Belal explained well enough, the pump is to circulate and the 40-psi is to overcome the boilers circuit friction and a little more to move the water to ensure adequate boiler water convection flows for the heat absorbing surfaces. Unlike a Boiler Feedwater Pump a primary obstacle is to overcome the steam drum press.<br /><br />Ross Mon, 7 May 2018 12:19:00 -0300 Re: Centrifugal Pump on Subcritical Boiler forced circ - By: Basem Belal [2194] Circulation pump will take the pressurized water from boilers down-comer at 14000 Kpa and push it again through bottom header at 14275 Kpa to made forced flow in boiler tubes.<br />circulation pump will get 14000 Kpa at its suction and 14275 Kpa at its discharge.<br /> Sun, 6 May 2018 11:06:00 -0300 Centrifugal Pump on Subcritical Boiler forced circ - By: Power engineering [2258] Good day, I was hoping if you guys can help me better understand the follow paragraph about controlled circulation boiler. Its for my studies. <br /><br />A large controlled circulation boiler employs several circulating pumps tied into a common suction manifold and a common discharge header. Usually, vertical centrifugal pumps driven by constant speed motors are used. Single stage pumps are adequate as the required head is about 275 kPa -40 psi-. Although the pump may only be required to develop a head of about 275 kPa -40 psi-, this head is over and above the boiler pressure existing at the pump suction which may be 14 000 kPa -2030psi- or over.<br /><br />I dont quite understand what they mean by 275KPA -40psi- can be over and above 14000 KPA -2030psi-? Please help me understand. <br /><br />Thank you very much. Sat, 5 May 2018 23:50:00 -0300 Re: Increasing Turbine out Pressure and its effect - By: Jim Watts [764] Not a very enlightening response from the OEM.<br />Feasible is just about as low as you can go before saying impossible.<br />But if I were an OEM I would probably say the same as it prepares you to spend big to get what you want.<br /><br />You have not indicated the turbine manufacturer or age or anything other than feasible to support my opinion so its not worth much.<br /><br />However I would say from experience that turbines in the size you are using are all basically the same design built to cover a wide range of duty. Eg all good for 100psig exhaust just change the nameplate for the customer conditions if lower. The inlet nozzle would probably be optimised for the service but in your case is not much of a change. The sentinel valve would be set to suit the exhaust condition but the safety could be nearer to 100psi to be standard.<br />The two manual valves mentioned by Ross are to increase efficiency at low load by closing them fully one or two to reduce throttling on main governor. There is no monitoring required.<br />If they are closed under existing load you are in luck just open them to cater for extra flow which will be required. <br />I would be inclined to check the manufacturers range to see if what I suggest is likely then provided you believe the casing is good enough to take it just close the exhaust valve to increase pressure to 50 psi and see if performance satisfies you. If not you need new nozzles, or even a larger govenor valve if it is fully open. <br /> Mon, 23 Apr 2018 02:29:00 -0300 Re: Increasing Turbine out Pressure and its effect - By: Ross Burns [390] The backpressure steam turbine that dumps into the 27psi header can be exhausted to the 50psi header. The casing pressure rating needs validating to a higher pressure than 50psi so a new sential safety valve can be installed as you indicated. <br /><br /> If you do not do anything to the steam turbine nozzle then the worst is a power reduction because the mass flow through the back pressure steam turbine is restricted at the admission nozzle. Most small steam turbines will have one or two manual admission valves to achieve maximum power but these cant be left unattendent.<br /><br />I would think the OEM will install a larger diameter steam admission nozzle. They should lift the cover to determine casing integrity for higher pressure and measure clearences. The OEM is my choice.<br /><br />Ross Sat, 21 Apr 2018 09:11:00 -0300 Re: Increasing Turbine out Pressure and its effect - By: Oil and Gas [2256] <br />OEM response:<br /><br /><br />Power req: original 165 kW new condition: 165 kw<br />Design Speed: Orig: 3575 RPM new condition: 3575 RPM<br />Inlet pressure: 400 psig in both<br />Exhaust pressure: Orig: 27 psig New condition: 50 psig<br /><br />The up gradation is feasible.<br /> Fri, 20 Apr 2018 01:10:00 -0300 Increasing Turbine out Pressure and its effect - By: Oil and Gas [2256] Hi all. <br />We have two steam turbine 1 &amp; 2 with their discharge headers of 50 psig &amp; 27 psig respectively. The inlet header is same i.e. 400 psig. Now what we want to do is connect the 27 psig turbine outlet header to the 50 psig header, which will operate both turbines at 50 psig. My understanding is this that when we do this the load on turbine 2 will need to be increased in order to maintain the rpm and output power. Can you guys point out any issues with this arrangement. W.r.t to its inlet nozzles, governer valves setting, sentinel valve operation etc.<br /><br />Questions have been sent to the OEM of the turbine and below is the response.<br /><br /> Fri, 20 Apr 2018 01:07:00 -0300 Re: ph of feed water - By: pradeep [1918] Dear all<br />Thanks for your valuable inputs. I would welcome more inputs from you people.<br /><br />Regards<br />Pradeep Sun, 15 Apr 2018 13:24:00 -0300 Re: concrete chimney - By: Jim Watts [764] This is not a simple thing to specify as this link to a tender of a stack will show<br /> Mon, 9 Apr 2018 11:20:00 -0300 Re: concrete chimney - By: Basem Belal [2194] I mean brick lined concrete, <br />any information with details will help sir. Sun, 8 Apr 2018 10:58:00 -0300 Re: concrete chimney - By: Jim Watts [764] Do you mean cement for bricks or brick lined concrete Sun, 8 Apr 2018 10:40:00 -0300 Re: STEAM TURBINE BAD VACCUM AND HIGH CONDENSER TEMPER - By: Jim Watts [764] If you provide the turbine exhaust temperature the condensate temperature and the condenser absolute pressure it is possible to indicate if the cooling is insuffient or the turbine is too hot or there is an air in the condenser.<br /> Sun, 8 Apr 2018 10:37:00 -0300 Re: ph of feed water - By: Jim Watts [764] Although TSP has a small increase in PH it is dosed to prevent scaling as indicated by Ross.<br />However there is PH loss in the boiler drum due to the ammonia and morphaline solubility in the water being reduced at the higher temperature. After all they are dosed so that they leave the drum with the steam and condense with the steam in the condenser to protect the condensate system. Sun, 8 Apr 2018 10:31:00 -0300 Re: concrete chimney - By: Murphy [21] Understood. Here is a short classification of Portland Cements from ASTM. Type V is sulfur resistant. Concrete mix for chimneys may need a little more special attention like Type III is made for structure like a chimney that needs early strengthening to maintaining a rapid pace of chimney construction since cold joints are very undesirable, for once the pour starts interrupting it has to be minimized, My little list should confirm what you already know.<br /><br />Portland Cement<br />Classification Purpose<br />Type I General purpose<br />Type II Moderate sulfate resistance<br />Type III High early strength<br />Type IV Low heat of hydration or slow reacting<br />Type V High sulfate resistance<br />White White color<br /><br />Murphy Fri, 6 Apr 2018 14:17:00 -0300 Re: concrete chimney - By: basem belal [2194] Thanks Murphy,<br />I thought that, but I miss all details about that kind of cement and grade of concrete procedure for using. I hopped that some one had theses details.<br />thanks to all<br /> Fri, 6 Apr 2018 07:27:00 -0300