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. 7/20/2018 10:10:16 PM Poppy at Steam & Power Forum RSS 64 150 Re: Turbine shaft permanent bending... - By: Jim Watts [764] It is very unlikely the GSC will fill from the condenser as the condenser would need to be up to the level of the turbine shaft.<br />If you are getting water into the turbine glands it is most probable coming from the steam to glands system. When the turbine is operating the HP gland leakage supplies the gland steam header and the startup gland steam supply is no longer used. This gives the possibility this line will cool and fill with water if it has faulty steam traps. When the turbine trips the gland steam tries to come from the startup header and if it is water you will cool the bottom of the turbine and fill the gland steam condenser till it runs steam again. Thu, 19 Jul 2018 09:26:00 -0300 Re: economizer feed water temperature - By: Greg Burns [1953] This is true but you must also mention that in most facilities that have cogeneration, it is economical to run with a higher feedwater temperature as it increases cogeneration. Wed, 18 Jul 2018 15:46:00 -0300 Re: Turbine shaft permanent bending... - By: anynomous [2257] The check valve will prevent the backflow of water/steam from condenser onto the GSCgland steam condenser. Or is/are there any valve or instrument that will prevent the backflow? Mon, 16 Jul 2018 08:27:00 -0300 Turbine shaft permanent bending... - By: Anonymous [2257] Ive noticed that every blockout of our unit, the gland steam condenser goes high. we all knew that gland steam condenser is connected to every gland of the turbine HP,IP and LP and its normal drain is connected to the condenser. shaft bending maybe caused by water ingress into the turbine. One incident or blockout happened and the rupture disc was not broken. the GSC level goes high. turbine proper drain headers temperature becomes colder. the level of the condenser goes high. the vacuum break valve was opened but im not sure if the condenser pressure goes high because the maximum can read on our transmitters is only 100.9 kPa. Is that possible that the reason of the water ingress is due to the level of condenser? Any recommendation/s on how to prevent high level of GSC whenever theres a block-out? im thinking if its possible to put a check valve between the the GSC and the condenser. Sun, 15 Jul 2018 10:08:00 -0300 Re: pH Measurement - By: Jim Watts [764] In steam cycle power plant it is not useful to have a PH number that is not accurate so the methods used are intended to get accuracy.<br />A PH meter is accurate. Its only problem is that it needs to be calibrated and carefully operated if used for different samples. On line instruments are no different to any other QMI.<br />The PH meter works by measuring the voltage produced between electrodes and is basically just checking how good a battery you can make with the solution.<br />The reading varies with the Hydrogen ion concentration of the solution and the less ions there are the more sensitive the result and the more likely poor lab technique will give an error.<br /><br />This is where inferred PH comes in.<br /><br />Inferred PH avoids the PH meter problem by not measuring the PH at all. <br />It is possible to calculate the PH if you know the number of Hydrogen Ions in the water.<br />A simple way to know the Total number of Ions is to measure the conductivity but it only works if there is only one type of Ion and you know its Conductivity to TDS ratio.<br />With very pure water dosed only with Ammonia you are very close to knowing this except there may be contaminants. A trick is to also measure the Cation Conductivity which causes the Ammonia to be exchanged for H20 so that the conductivity represents the non Ammonia TDS. You subtract the cation TDS from the Total TDS and you then use to Calculate PH.<br />This method cannot be used when the Non Ammonia Ions vary to much in their conductivity to TDS ratio as the inacuracy is worse than measuring PH with a meter.<br /><br /> Sat, 7 Jul 2018 20:03:00 -0300 Re: pH Measurement - By: Ross Burns [390] This is not an easy question, but a good one. Presently, there are 3-methods of pH measurement instruments. All of them require programing calculations, but the simplest needed some calculation too as some point when developing it. Just know there is no-direct measurement method to determine pH, for they all have to be determined based on conductivity. <br /><br />Of the 3-conductivity pH instruments, none are not based on type of Boiler or even pressure steam drums like LP, IP and HP steam drum. However, what is a decison to use which on is based on continuing operating cost and installation costs as well as the decision for the need for accuracy, which is likely to come from one of the three TSP tri-sodium-phosphates water treatment programs as well as for continuous readings like steam sampling.<br /><br />Most steam plants that are stable such as moderate degree of daily swing loads probably does not need continuous pH monitoring, except of perhaps steam sampling, but there maybe some special cases too.<br /><br />The simplest pH instrument is a handheld and called a Colorimetric slide. This works off of titration. It is accurate for many applications, but not used much today,<br /><br />The most common is glass electrode instrument and it is accurate enough for your HRSG or as Mr.MW MEGA-Watt said his BioMass high-pressure boilers.<br /><br />The most advanced is the a cation -acid- based conductivity instrument. It can be in-stream that is to say shunted to the main steam. It is very expensive but very-sensitive after some ion conditioning in the instrument. It is so sensitive that it accommodates the super-cleanliness waters being sampled.<br /><br />Allow me to basically explain the inherited problem of super clean, relatively speaking, rankine cycle waters. The problem is pH will swing dramatically and rapidly in real world without a buffer to dampen the the OH hydroxyl ion. This is because when there is little alkaline conditioning to buffer the pH because the constant chemical reactions of boiler or condensate waters produce less alkaline conditions. that is why we like to see sufficient alkalinity in most boilers. So, when using the cation conductivity instrument to determine pH you are seeing the hard swings of ups and downs in the pH, but probably just swinging within a tolerance, but very-accurate and if you are running your TSP on the edge then you will need it. But this maybe too accurate for some water treatment specialists, since it can be meaningless too. <br /><br />When using a glass electrode conductivity probe you tend to get a spot reading that is practical in most applications.<br /><br />Seems to me you are asking a real good question, which I did not answer directly, but it may give better understanding of the issues of determining and applying pH instruments.<br /><br />Ross Sat, 7 Jul 2018 15:38:00 -0300 Re: pH Measurement - By: MW [2231] We use electrode measurements here 160mw biomass plant. All other plants I have visited here in UK of varying size and fuel sources have also used pH electrode Wed, 4 Jul 2018 11:15:00 -0300 Re: HRSG Boiler Drum Inspection - By: Vangel [2265] We use High-pH AVTO with O2 at about 25 ppb at condensate pumps discharge and 0 ppb at LP Drum. We also add TSP at IP Drum. All of our drums are red because of a constant hematite layer Wed, 4 Jul 2018 10:15:00 -0300 pH Measurement - By: Vangel [2265] How do you measure the pH ? With electrode or calculated from EC and CC measurements?<br />At our gas fired combined cycle power plant it seems that calculated pH at condensate, LP Drum and HP Drum we have only ammonia, we cant calculate pH for IP drum where TSP is added is more stable and reliable than electrode measurements. We measure EC and CC online and then calculate the pH according to VGB -S-006-00-2012-09-EN standard. Wed, 4 Jul 2018 10:03:00 -0300 Re: water treatment in closed loop - By: Anthimos [2265] Do you measure also NO3- , total Fe and total Cu ? Wed, 4 Jul 2018 09:30:00 -0300 Re: One question regarding heating of water. - By: Ross Burns [390] Hi PI,<br /><br />Can I suggest you consider the practical application of a Mollier Chart or also known as a Heat Entropy Chart. This chart is real world and with no theory.<br /><br />Mr. Watts is spot-on and I agree with Mr. Belal.<br /><br />Ross<br /><br /> Mon, 18 Jun 2018 09:40:00 -0300 Re: One question regarding heating of water. - By: Basem Belal [2194] Agree with you Mr. Jim Watts Mon, 18 Jun 2018 01:43:00 -0300 Re: One question regarding heating of water. - By: Jim Watts [764] I am sorry to tell you but you are the only one likely to believe any of the things you mention in your question because they are all wrong.<br />Steam does not exist below saturation temperature even if you say so.<br />The steam leaving a turbine having travelled all the way through is either still superheated or in the case of a condensing turbine is at saturation temperature with at most 10 percent water also at saturation temperature. Otherwise the turbine will erode.<br />This will be around 55 degrees for a condensing turbine and this temperature and pressure will stay the same till the other 90 percent is all condensed to water over the condenser tubes and it is then pumped away to the boiler.<br />You can also assume the water will remain at saturation temperature while it all boils away to steam at whatever pressure exists in the boiler.<br /> Fri, 15 Jun 2018 01:05:00 -0300 One question regarding heating of water. - By: P I [1983] We all know here that when steam comes of out of a turbine, even if the temperature is below 100&#194;&#176;C and the pressure is 1 barA all the steam hasnt been converted into water. Slowly the steam began to cool and part of it is converted into water in accordance with the steam pressure at that temperature. As for example, when the temperature will fall to 80&#194;&#176;C, then nearly 54% of steam is converted into water and 46% remain as steam. And such process continues till the temperature comes to ambient level.<br />Now, we can assume the opposite when water is heated from ambient level. But what happens in reality? Mon, 11 Jun 2018 10:02:00 -0300 Re: silica in condensate - By: MW [2231] Please also tell us:<br /><br />Silica in boiler water<br />Silica in feed water<br />Source of condensate<br />Silica in steam for turbine<br />Steam pressure / temperaure<br />Temperature of caustic for regeneration Wed, 30 May 2018 10:53:00 -0300 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