Hi guys, i would like to ask how to build up a Condensing CHP in my model for steelworks.
My questions are:
1. Is it good approach to have BOILERS producing only energy carrier "DIRECTSTEAM" which input to other processes and also as a "fuel" for Condensing turbine producing ELECTRICITY and another kind of STEAM "INDIRECTSTEAM" with different parameters in contrast with "DIRECTSTEAM" ? It is necessary to distinguish these two "STEAMS".
2. Parameters CHPR~UP and CHP~LO could be computed = MAX. Heat production activity data / MAX. Electricity production activity data = CHPR~UP ?
= MIN. Heat production activity data / MIN. Electricity production activity data = CHPR~LO ?
3. CEH parameter computed as ( ETAel – ETAelBP) / ETAthBP)
ETAelBP is electrical efficiency ? ETAthBP is heat efficiency ? ETAel electrical efficiency at condensing point ? How to get these efficiencies ?
Briefly, electricity can be delivered into facility via Grid, but "STEAMS" can not, it can be only produced in facility.
Please see attached.
CHP processes are normally modelled as technologies consuming fuels and producing electricity and heat. See illustration below. I would say it would be a very unusual approach to split the process into a steam boiler and a turbine-generator process.
As described in the documentation, you should choose the basis for the activity; a typical choice would be "electricity in condensing mode". In that case the fuel efficiencies η(i) for each input fuel i should all be specified for the condensing mode, and the capacity would thus represent the full electrical capacity in condensing mode.
Yes, the NCAP_CEH parameter can then be computed as NCAP_CEH = ( ETAel – ETAelBP) / ETAthBP), where ETAelBP is electrical efficiency in CHP mode, ETAthBP is heat efficiency in CHP mode, and ETAel is electrical efficiency in condensing mode. To say that differently, NCAP_CEH = (ElCond – ElCHP) / HeatCHP, where ElCond is the electrical output in condensing mode, ElCHP is the electrical output in CHP mode, and HeatCHP is the heat output in CHP mode, all at the same level of activity (on the line of constant fuel input). Surely you should know these if you have the technology data.
NCAP_CHPR(UP) must be defined according to the maximum heat-to-power ratio in the CHP mode. NCAP_CHPR(LO) is optional, the minimum heat output at each timeslice is zero by default (= full condensing mode).
(07-10-2021, 02:30 PM)Antti-L Wrote: CHP processes are normally modelled as technologies consuming fuels and producing electricity and heat. See illustration below. I would say it would be a very unusual approach to split the process into a steam boiler and a turbine-generator process.
As described in the documentation, you should choose the basis for the activity; a typical choice would be "electricity in condensing mode". In that case the fuel efficiencies η(i) for each input fuel i should all be specified for the condensing mode, and the capacity would thus represent the full electrical capacity in condensing mode.
Yes, the NCAP_CEH parameter can then be computed as NCAP_CEH = ( ETAel – ETAelBP) / ETAthBP), where ETAelBP is electrical efficiency in CHP mode, ETAthBP is heat efficiency in CHP mode, and ETAel is electrical efficiency in condensing mode. To say that differently, NCAP_CEH = (ElCond – ElCHP) / HeatCHP, where ElCond is the electrical output in condensing mode, ElCHP is the electrical output in CHP mode, and HeatCHP is the heat output in CHP mode, all at the same level of activity (on the line of constant fuel input). Surely you should know these if you have the technology data.
NCAP_CHPR(UP) must be defined according to the maximum heat-to-power ratio in the CHP mode. NCAP_CHPR(LO) is optional, the minimum heat output at each timeslice is zero by default (= full condensing mode).
Thank you Antti but what would you do if there is demand for two kinds of STEAM ? Would you create new HP process only parallel with CHP - electricity in Condensing mode ?
Sorry, but I don't quite understand what you mean by "create new HP process only parallel with CHP - electricity in Condensing mode".
But if a CHP process should produce two types of steam, one could add a second steam output for it, and add bounds for the output shares.
(07-10-2021, 03:07 PM)Antti-L Wrote: Sorry, but I don't quite understand what you mean by "create new HP process only parallel with CHP - electricity in Condensing mode".
But if a CHP process should produce two types of steam, one could add a second steam output for it, and add bounds for the output shares.
Antti i will back to you after consultation this issue with energy consultant for steelwork.
(07-10-2021, 03:07 PM)Antti-L Wrote: Sorry, but I don't quite understand what you mean by "create new HP process only parallel with CHP - electricity in Condensing mode".
But if a CHP process should produce two types of steam, one could add a second steam output for it, and add bounds for the output shares.
Hi Antti, i talked to our energy consultant for Steel production.
Please see attached (scheme).
First process is 9 MPa High Pressure Steam which is delivered via pipeline to TG - Turbo generators, 2 of them are Back pressure ganerator, 3 are Condensing extraction generator. All of them produce ELECTRICITY, DIRECTSTEAM - 9MPa, and inDIRECTSTEAM - 9MPa but this one (inDIRECT) is transformed to another kind of energy carrier, while DIRECT is use without transforming.
I am no expert on these kind of industrial process steam systems modeling designs. But you have the experts helping you − so I think you should be able to decide. Possibly some other industrial process modelers on the Forum may also be able to give you their insights.
(07-10-2021, 10:46 PM)Antti-L Wrote: I am no expert on these kind of industrial process steam systems modeling designs. But you have the experts helping you − so I think you should be able to decide. Possibly some other industrial process modelers on the Forum may also be able to give you their insights.
Hi Antti . I have created excel file with Condensing CHP in it. I have decided that input energy carrier will be Fuel Mix insead of HPSTEAM as last time. But RESULTS really did not meet my expectations. CEH parameter needs to be 0 because if its not DUMMY Inport NRG appears in Results.
08-10-2021, 10:08 PM (This post was last modified: 08-10-2021, 10:22 PM by Antti-L.)
You have not understood it well. Please read the documentation, section 4.1 Combined heat and power.
NCAP_CEH absolutely must be specified with a reasonable non-zero value if NCAP_CHPR(UP) is used. This is so because for the flexible operation range, the efficiencies are only valid for one point on the constant fuel line, and if you do not specify NCAP_CEH or set NCAP_CEH=0, then the efficiency would be constant on that line, which makes no sense.
You claim in the Excel file that the process should consume 23.20701 units of input in 2018. But that would be true only if the CHP process would be a fixed CHPR back-pressure technology! I just tested with exactly with the parameters you show in your Excel file, but with a fixed CHPR=3.1663266, and indeed I got 23.20701 in the results for the input fuel, just like you expected. The total CHP efficiency is then only 68.3%.
What you don't seem to understand is that a pass-out condensing turbine CHP works differently, and you are specifying a much higher CHPR(UP)=5.287, and NCAP_CEH=0, which means that your CHP mode efficiency is as high as 103%, simply because the electrical efficiency is 16.4% and the full CHP mode output is 6.287 times the electrical output. This should have been be quite obvious to you, and so I can only suggest to read once again the documentation, section 4.1 Combined heat and power.
BTW: I tested exactly with the parameters you show in your Excel file, but I cannot reproduce your results. Therefore, it seems that the results you showed are not even based on the same input data. Anyway, I am not getting any dummy imports. So, I cannot confirm any of your findings.
08-10-2021, 11:23 PM (This post was last modified: 09-10-2021, 07:10 PM by JozefO.)
(08-10-2021, 10:08 PM)Antti-L Wrote: You have not understood it well. Please read the documentation, section 4.1 Combined heat and power.
NCAP_CEH absolutely must be specified with a reasonable non-zero value if NCAP_CHPR(UP) is used. This is so because for the flexible operation range, the efficiencies are only valid for one point on the constant fuel line, and if you do not specify NCAP_CEH or set NCAP_CEH=0, then the efficiency would be constant on that line, which makes no sense.
You claim in the Excel file that the process should consume 23.20701 units of input in 2018. But that would be true only if the CHP process would be a fixed CHPR back-pressure technology! I just tested with exactly with the parameters you show in your Excel file, but with a fixed CHPR=3.1663266, and indeed I got 23.20701 in the results for the input fuel, just like you expected. The total CHP efficiency is then only 68.3%.
What you don't seem to understand is that a pass-out condensing turbine CHP works differently, and you are specifying a much higher CHPR(UP)=5.287, and NCAP_CEH=0, which means that your CHP mode efficiency is as high as 103%, simply because the electrical efficiency is 16.4% and the full CHP mode output is 6.287 times the electrical output. This should have been be quite obvious to you, and so I can only suggest to read once again the documentation, section 4.1 Combined heat and power.
BTW: I tested exactly with the parameters you show in your Excel file, but I cannot reproduce your results. Therefore, it seems that the results you showed are not even based on the same input data. Anyway, I am not getting any dummy imports. So, I cannot confirm any of your findings.
Problem is that i not able to get correct CEH parameter for passout condensing turbine at the moment. Could you post here your tets file please ?
I have looked at documentation. Soo for better clarification:
"1. Back pressure turbines are systems in which the ratio of the production of electricity and heat is fixed, so that the electricity generation is directly proportional to the steam produced. In a real system, a back pressure turbine is defined using the electrical efficiency, the thermal efficiency, and the load utilization. The CHPR attribute is then fixed (FX), so the production of electricity and heat is in a fixed proportion, but one could also use a (LO) CHPR for defining the back-pressure point, if so desired (to allow bypassing the turbine to produce more heat). CEH can be either 0 (or missing) or 1: If it is 0 (or missing) as in this example, the activity represents the electricity generation and the capacity represents the electrical capacity; If it is 1, the activity represents the total energy output and the capacity represents the total capacity (electricity + heat). "
My questions are : Let´s say i want to model only Back pressure turbine process producing ELC and STEAM. Parameters i need to use are electrical efficiency, CHPR FX (Fixed) or LO ?, load utilization and CEH. BP Turbines with fixed proportion is clear to me, only usage of CHPR LO make me little bit confused. How it looks like mathematically FX and LO ?
CEH would be 0 soo the activity VAR_Act of process will be represented by electricity generation (output) and Capacity NCAP_PASTI or STOCK is represented by electrical capacitynot thermal + electical because CEH = 0 and CHPR FX fixed proportion i.e its back pressure turbine.
But one could use CHPR LO for bypassing the trubine to produce more STEAM soo in symplified way, it´s mean more heat production (when its´s needed) and decreas of electricity production ? Or there will be higher fuel consumption to satisfy demand of ELC and HEAT-"STEAM" ? Equation for CHPR~FX = ETAthBP/ETAelBP Equation for CHPR~LO use same parameters but with minimal el/th PB efficiencies ?.
2. The condensing pass-out or extraction turbinesdo not have to produce heat, permitting electricity only to be generated, and permitting the amount of heat generated to be directly adjusted to the heat demand, while the electricity generation is reciprocally proportional to heat generation (electricity losses because of heat extraction). They are thus described differently:
1. Coefficient of electricity to heat, via attribute CEH such that: a) <= 1: electricity loss per unit of heat gained (moving from condensing to backpressure mode), indicating that activity is measured in terms of electricity, or b) >= 1: heat loss per unit of electricity gained (moving from backpressure to condensing mode), indicating that activity is measured in terms of total output (electricity plus heat).
2. Efficiencies, according to 1: a) are specified for the condensing point, or b) are specified for backpressure point.
3. Costs, according to 1 are specified based: a) according to condensing mode, or b) on total electricity and heat output at backpressure point.
4. Ratio of heat produced to electricity produced (CHPR): Ratio of heat to power at backpressure point; at least a maximum value is required, but in addition also a minimum value may be specified.
: Is difference between Public CHP where demand for Heat and electricity changes during year. Heat demand is higher during winter seasons and Electricity has more or less constant demand for entire year. In Industrial processes is consumption of ELC and HEAT constant for all year. But i think if there is cheaper alternative for ELECTRICITY, model should decided to use it and in our case it could be delivered via GRID soo CHP would produce less Electricity but there is no alternative for HEAT delivery from GRID thats why CONDENSING PASS OUT turbines are use they are more flexible.
So: a) if CEH <=1 electricity loss per unit of heat gained, indicated VAR_Act is measured in terms of Electricity. VDA_CEH = ( ETAel – ETAelBP ) / ETAthBP b) if CEH >=1 heat loss per unit of electricity gained, indicatedVAR_Actis measured in terms of Electricity + heat total. I have only ELC efficiency= 0.1638 and HEAT efficiency= 0.7024 computed for year 2018, (Produced ELC / Total fuel input and Produced HEAT / Total fuel input) Have no clue if its ETAel at condensing point or ETAel at BACK Pressure point or ETAth at BACK Pressure piont. I guess our experts should know this parameters. Or it could be computed whith some other activity data? Should be CHP divided to Back Pressure CHP and Condensing CHP separately ?
Computed value of CEH determin VAR_Act terms (electricity or electricity + heat ?
EFF = CEH lower than 1 determin Electrical Efficiency ? EFF = CEH higher than 1 determin Electrical + Heat Efficiency ? 2. Efficiencies, according to 1: a) are specified for the condensing point, or b) are specified for backpressure point : Please could you clarify it ? Alternatively, if it would seem more convenient to define both the condensing mode efficiency and the full CHP efficiency, that can be done by using the parameters NCAP_CDME (condensing mode efficiency) and NCAP_BPME (back-pressure mode efficiency). When these two parameters are used, the NCAP_CEH and ACT_EFF parameters should then not be used at all ?
But CHPR UP = Maximum value CHPR~UP = ETAthBP / ETAelBP still necessary ?
09-10-2021, 08:50 PM (This post was last modified: 09-10-2021, 09:04 PM by Antti-L.)
I advised you to read the documentation, Part II, section 4.1 Combined heat and power. See Part II.
You have apparently been reading Part IV, which I have never read myself. It is a VEDA documentation, not TIMES. So, once again, please just read Part II, and everything should become clear.
Some comments to your remarks, which were apparently based on reading Part IV:
>Back pressure turbines [...] The CHPR attribute is then fixed (FX), so the production of electricity and heat is in a fixed proportion, but one could also use a (LO) CHPR for defining the back-pressure point, if so desired (to allow bypassing the turbine to produce more heat).
Correct, you should use CHPR(FX) for back pressure turbines, and CEH=0 or unspecified. The CHPR(LO) option (instead of FX) would allow the process to produce also purely heat, with the same overall efficiency. That might indeed be also reasonable in some systems.
>My questions are : Let´s say i want to model only Back pressure turbine process producing ELC and STEAM. Parameters i need to use are electrical efficiency, CHPR FX (Fixed) or LO ?, load utilization and CEH.
No. You should not use CEH for a back pressure turbine, as you can see by reading section 4.1 Combined heat and power, and especially subsection 4.1.2.1 Back-pressure turbine systems.
>I have only ELC efficiency= 0.1638 and HEAT efficiency= 0.7024 computed for year 2018, (Produced ELC / Total fuel input and Produced HEAT / Total fuel input)
I don't quite understand, have your numbers changed again? In your Excel file, your expected HEAT efficiency was only 0.518777 (the total heat output was 12.0393 and total fuel input was 23.207, as calculated by you). But the ELC efficiency 0.1638 does match with your Excel.
(09-10-2021, 08:50 PM)Antti-L Wrote: I advised you to read the documentation, Part II, section 4.1 Combined heat and power. See Part II.
You have apparently been reading Part IV, which I have never read myself. It is a VEDA documentation, not TIMES. So, once again, please just read Part II, and everything should become clear.
Some comments to your remarks, which were apparently based on reading Part IV:
>Back pressure turbines [...] The CHPR attribute is then fixed (FX), so the production of electricity and heat is in a fixed proportion, but one could also use a (LO) CHPR for defining the back-pressure point, if so desired (to allow bypassing the turbine to produce more heat).
Correct, you should use CHPR(FX) for back pressure turbines, and CEH=0 or unspecified. The CHPR(LO) option (instead of FX) would allow the process to produce also purely heat, with the same overall efficiency. That might indeed be also reasonable in some systems.
>My questions are : Let´s say i want to model only Back pressure turbine process producing ELC and STEAM. Parameters i need to use are electrical efficiency, CHPR FX (Fixed) or LO ?, load utilization and CEH.
No. You should not use CEH for a back pressure turbine, as you can see by reading section 4.1 Combined heat and power, and especially subsection 4.1.2.1 Back-pressure turbine systems.
>I have only ELC efficiency= 0.1638 and HEAT efficiency= 0.7024 computed for year 2018, (Produced ELC / Total fuel input and Produced HEAT / Total fuel input)
I don't quite understand, have your numbers changed again? In your Excel file, your expected HEAT efficiency was only 0.518777 (the total heat output was 12.0393 and total fuel input was 23.207, as calculated by you). But the ELC efficiency 0.1638 does match with your Excel.
Correct, you should use CHPR(FX) for back pressure turbines, and CEH=0 or unspecified. The CHPR(LO) option (instead of FX) would allow the process to produce also purely heat, with the same overall efficiency. That might indeed be also reasonable in some systems.
*** CHPR FX can be used parallelly with CHPR LO or only one has to be ?
No. You should not use CEH for a back pressure turbine, as you can see by reading section 4.1 Combined heat and power, and especially subsection 4.1.2.1 Back-pressure turbine systems.
*** I m not claiming that. Documentation says: If its 0 or nothing its correct for BACK PRESSURE TURBINE to have 0 or nothing.
I don't quite understand, have your numbers changed again? In your Excel file, your expected HEAT efficiency was only 0.518777 (the total heat output was 12.0393 and total fuel input was 23.207, as calculated by you). But the ELC efficiency 0.1638 does match with your Excel.
*** Obviously there are mistakes in the activity data But ELC efficiency is correct 0.1638 in EXCEL - CHP what i attached here. Heat efficiency and Heat production are wrong numbers, its my bad. 0.7024 is Heat eff and Produced Heat is 20.103 PJ but 7.854 PJ of Produced HEAT was used for Electricity production.
Can I ask, would you or someone else add here some examples for CHP technologies in VT_files Please ? There is no examples in VT_Demo files or even in VT_STARER.
11-10-2021, 03:13 PM (This post was last modified: 11-10-2021, 03:37 PM by JozefO.)
(09-10-2021, 10:30 PM)Antti-L Wrote: Hmm... what are these example technologies in the VT-Starter model then, if they are not CHP?
And why do you say there is no CHP example VT_Demo files? Isn't the SubRES_New-CHP-DH all about that?
Concerning CHPR, no-one has suggested using both FX and LO at the same time; FX would override any UP and LO.
Done reading documentation and i have created tabels for our experts for energetical processes. In excel file attached here are needed technical parameters marked in yellow.
Could you take a quick look in to it? And last question today: Fuel input (PJ) = VAR_Act = Electricity net produced / Electrical EFF - If its FIXED CHP.
How equation will looks if its PASS OUT or Extraction technology with CEH and CHPR UP ?
11-10-2021, 05:00 PM (This post was last modified: 11-10-2021, 05:06 PM by Antti-L.)
>Done reading documentation and i have created tabels for our experts for energetical processes.
That's good.
>And last question today: Fuel input (PJ) = VAR_Act = Electricity net produced / Electrical EFF - If its FIXED CHP. How equation will looks if its PASS OUT or Extraction technology with CEH and CHPR UP ?
That's not so good. You have already read the documentation, which says that for back-pressure turbine technologies (CHPR(FX)) the activity is the electrical output. And ACT_EFF defines the efficiency between the input fuel(s) and the activity. So, you already know that for back-pressure turbine technologies:
And you have already read the documentation, which says that for pass-out turbine systems (CHPR(UP)) the activity is either of:
● Max. electrical output (–1<CEH≤0)
● Electricity output in full condensing mode (0≤CEH<1)
● Total energy output in full CHP mode (CEH ≥ 1)
And so, assuming you use 0≤CEH<1, you have
VAR_ACT(ts) = ACT_EFF(ts) × VAR_FLO(Fuel,ts)
VAR_ACT(ts) = Electricity output in full condensing mode, in ts
And from Figure 10 you can immediately see how the electricity output changes as a function of the heat output.
Yet, you are still asking me about these relations?
But you have the experts helping you − so I think you should be able to decide. Possibly some other industrial process modelers on the Forum may also be able to give you their insights.
