For Low Pressure use we recommend the COM5 regulator/hose. I’m amazed, I must say. Variation of gas viscosity in the pipeline (Cases A and B), Figure 8. For the dense phase – Case A and the same diameter, on the average the velocity is lower compared to lower pressure gas transportation. 1215 Crossroads Blvd.Suite 230 A simplistic Process Flow Diagram (PFD) is shown in Figure 2. I must spend a while finding out much more or figuring out more. There are many equations for determining the flow in natural gas pipes and the pressure drops associated with those flows, or vice versa. He holds B.S. The gas composition and conditions are presented in Table 1. Also available with an Optional Needle … σ is the pipe material yield stress (Grade X70 = 70,000 psi or 448.2 MPa), and. Variation of wall thickness with pipeline inlet pressure, Figure 6. Pipeline specifications for the three casesThree cases for transportation of this natural gas are considered and each is explained briefly below. Compressors and associated equipment (drivers, coolers, and ancillaries) are priced at US$ 1500 per demand horsepower. The high pressure compressed gas is cooled back to 100 ˚F (37.8 ˚C) and then passed through a separator before entering the long pipeline. Table 3. to be what precisely I’m looking for. Horizontal pipeline, no elevation change. ft. 5 cu. Figure 5 presents the calculated wall thickness as a function of the inlet pressure (for the three cases). The specific gravity of the natural gas should be considered as higher specific gravity will result in higher pressure drops or lower pipe carrying capacity at a given pressure drop. As can be seen in this table, Case A requires the least total compression power and heat duty requirements. I will definitely be returning. Natural gas in the natural gas service line pressure in the gas main in the street will be found at pressures from 60 psi down to as low as 0.25 psi or about 7 inches of water column. The lean gas has a Gross Heating Value of 1082 BTU/scf (40.33 MJ/Sm3), which is in the range typically seen for contract quality natural gas in North America. For the dense phase – Case A, the friction pressure drop / mile is lower . He is the By: Mahmood Moshfeghian and David Hairston, Figure 5. The pipeline inlet pressure is in the dense phase zone. Lowest cost (Opex + capex) of the system is attained at optimum (compressor discharge pressure & no of compressor stations)condtions ? High pressure vs low pressure propane burner? The key is by how much. In each station, the pressure is raised from 615 Psia to 1637 Psia (4.24 to 11.28 MPa) in one stage, then cooled to 100 ˚F (37.8 ˚C), and finally passed through a separator before entering each pipeline segment. Delivery pressure is 615 Psia (4.24 MPa). The pressure drop calculation utilizing the liquid phase and vapor phase equations were compared. The feed gas dew point was reduced to -40 ˚F (-40 ˚C) by passing it through a mechanical refrigeration dew point control plant. Increasing the steel grade (SMYS – Specified Minimum Yield Stress) from X-70 to X-80 would decrease the steel tonnage approximately 14%. Our study highlighted the pros and cons of dense phase transportation. Low-pressure propane burners are able to regulate gas intake to 6 ounces per square inch or so while their high-pressure counterparts are able to regulate gas from anywhere between 1 and 60 pounds per square inch. I wouldn’t mind writing a post or elaborating on many of the The wall thickness, t, for the three cases is calculated from a variation of the Barlow Equation found in the ASME B31.8 Standard for Gas Transmission Pipelines: After calculating the wall thickness, the diameter to wall thickness ratio (D/t) is checked against these rules of thumb: If the D/t calculated is too high, the wall thickness will be increased to yield the maximum allowed D/t. By: David Hairston and Mahmood Moshfeghian, Categories: Gas Processing, Pipeline, Process Facilities, Recieve new post updates: Entries (RSS) Some observations from these calculations that can be made are: Table 4: Pressures and Wall Thickness Selections, Table 5: Pipeline Wall Thickness Selections and Total Steel Weight. Case A: High Pressure (Dense Phase) After passing through the first stage scrubber, the lean gas enters the first stage of compressor where its pressure is raised to 1407 psia (9.703 MPa), then it is cooled to 100 ˚F (37.8 ˚C) and compressed further in the second stage to 3220 Psia (22.2 MPa). Thank you for excellent info I used to be looking for this such as petroleum refineries, chemical plants, natural gas processing plants, and at oil or gas production sites with oil wells, offshore oil and gas rigs/platforms ... pressure, acid gas flare, low temperature] • Sparing and maintenance requirements • Mounting flares on a common derrick vs. a mix of derrick and guy- ... venting or blowdown purposes will be connected to either a high pressure flare or a low … The line regulator is necessary because residential appliances are designed to burn natural gas only at low pressure. By gradually The most sensitive variable for the compressor stations calculations is the location of any offshore facilities. It is common for total life cycle costs (OPEX plus CAPEX) to begin rising at some point as the number of compressor stations and total horsepower increases with decreasing operating pressure. METER TIMING TABLE FOR GAS INPUTS AT LOW PRESSURE METERING GAS RATE CUBIC FEET PER HOUR Seconds For One Size of Test Dial Revolution 1/2 cu. in Civil Engineering for the University of Houston. Our study highlights the following features: In future Tip of the Months, we will consider the effect of project location and operating costs on the life cycle costs and the configuration selection. Have you heard about the gas explosions yesterday in Lawrence Ma?I am curious to hear your opinion on what may have caused it to happen. In this month’s – Tip of the Month (TOTM), we continue to explore key aspects of dense phase transportation in pipelines. Variation of temperature in the pipeline (Cases A and B), Categories: Gas Processing, Pipeline, Process Facilities, Recieve new post updates: Entries (RSS) After processing and passing through the first stage scrubber, the lean gas pressure is raised to 1496 psia (10.32 MPa), then cooled to 100 ˚F (37.8 ˚C). The gas is compressed further in the second stage to 3659 Psia (25.22 MPa). The following assumptions and correlations are/used: Table 1. Steel is a common option for operations with wells that flow naturally or have a pressure less than 1 1/2 psig; common to use fittings factor 1.5 - equivalent pipe length in table above = pipe length + 50%; pressure drop 0.5 inches water column; specific gravity of natural gas 0.6; One MBH is equivalent to 1000 BTU's per hour (0.29 kW = 0.29 kJ/s); energy content in natural gas 1000 Btu/ft 3 (37.26 MJ/m 3); steel pipes schedule 40 A detailed economic analysis in terms of CAPEX and OPEX should be made for a sound comparison. Can I conclude like this – As compressor discharge pressure increases the cost of pipe line(capex) increases. Similarly, the heat duty reduction for Case A is about 39% compared to Case B and 50 % compare to Case C, respectively. The PFDs for the three cases are simulated using ProMax [3]. Beaubouef, B., “Nord stream completes the world’s longest subsea pipeline,” Offshore, P30, December 2011. Variation of pressure in the pipeline (Cases A and B), Figure 10. This case is similar to Case B except the pipeline is divided into five 200-mile (322 km) pipeline segments with one lead compressor station and 4 intermediate compressor stations. (74), M.S. The pipeline inlet pressure is in the dense phase zone. The large quantity of steel needed allows the buyer to dictate a non-standard thickness. Natural gas line sizing calculated in this post will be from manual calculation and from process simulator. The wall thickness, t, for the three cases was calculated by: P is maximum allowable operating pressure, here set to 1.1 times the inlet pressure. There is more to switching from high to low pressure than changing the orifice. Our study highlighted the pros and cons of dense phase transportation. Recently (January through April 2012 TOTMs) we discussed several aspects of transportation of carbon dioxide (CO2) in the dense phase. Variation of gas velocity in the pipeline (Cases A and B), Mechanical Design (Wall Thickness and Grade). An explosion analysis shall be conducted where the gas pressure exceeds 125 psig (862 kPa gauge). Often, with the operating costs included the “optimum” configuration favors higher operating pressures and fewer compressor stations. For the purpose of illustration, we will consider transporting a natural gas mixture with composition and conditions presented in Table 1. Construction will account for approximately 40% of the CAPEX as well. The natural gas pressure of the gas line leading to the home ranges from approximately 1/4 psi to 60 psi, depending on the number of homes or businesses served by the line. Pipeline total installed cost is 2.5 times the pipe steel plus coatings cost. The high pressure compressed gas is cooled back to 100 ˚F (37.8 ˚C) and then passed through a separator before entering the long pipeline (See Case A in Figure 2). To improve the accuracy and to take care of variations of physical properties of gas, each pipeline segment length was divided into 10 sub segments. Project specific factors such as mountainous terrain for an onshore pipelines, or the requirement to trench an offshore pipeline can impact this cost multiplier. A high pressure system has higher pressure at its center than the areas around it. In September 2012 (TOTM), we analyzed pipeline transportation of a lean natural gas at a wide range of operating pressures from the relatively low pressure typical in many gas transmission pipelines to much higher pressures well into the dense phase region. Once the wall thickness is determined, then the total weight (tonnage) of the pipeline can be calculated as well as costs for the pipeline steel. Propane regulator facts, propane facts, propane 101, high pressure and low pressure, types of propane regulators, and a ... GasHosesandRegulators.com sells only 3/8"ID gas outlet low pressure gas regulators with 3/8"ID low pressure hoses for this very reason. I wonder a bit if they have quality control problems with that unit. The calculated wall thickness is then checked against the maximum D/t criteria. The system was designed with 14 regulator stations to control the pressure of natural gas entering the downstream distribution pipeline mains. For simplicity, the calculations and subsequent discussion will be done on the dry basis. The power reduction for Case A is about 51%  compare to Case B and 63% compare to Case C. These reductions in power and heat duty requirements are considerable. low IP 35 psi to the home and regulated to 7"wc (normal distribution in urban areas) high IP 65-110# regulated to 35-55 at the road and again at the home to 7"wc (rural distribution where the house is WAY back from the road) and high pressure (over 110# mains and commercial supply. Overall Heat Transfer Coefficient: 0.25 Btu/hr-ft. Variation of gas density in the pipeline (Cases A and B), Figure 7. I am very happy I stumbled across this during my hunt Pressure drop in each heat exchanger is 5 psi (0.035 MPa). The decreased costs for compression are offset by increasing pipeline costs. As no of compressor stations increase(for low pressure operation)the operating cost(opex) increases. Equation of State: Soave-Redlich-Kwong (SRK). The estimated cost will be calculated from the following assumptions: With these cost assumptions, an order of magnitude estimate (OME) for the total installed cost (TIC) is developed for the pipeline, then the compressor stations, and finally combined for the total pipeline system in Table 6 – Pipeline Estimate, Table 7 – Compressor Station Estimate, and Table 8 – Total System OME. Overall Heat Transfer Coefficient: 0.25 Btu/hr-ft. Simulation software: ProMax and using Equation of State from Soave-Redlich-Kwong (SRK). These differences are largely dependent on the project location with factors that could include weather and seasonal challenges, water depth for offshore projects, terrain for onshore projects, available infrastructure and its impact on logistics, and availability of construction equipment and labor. Both are dependent of the pipeline pressure profile which is dictated by the number of compressor stations. Recieve follow up comments updates: RSS 2.0, View all posts by: David Hairston and Dr. Mahmood Moshfeghian. The capital costs (CAPEX) for these estimates are based on two key variables: pipeline wall thickness and the compression power required. Some outdoor gas appliances, such as high heat cast iron burners, require the use of a high pressure regulator because they need more volume of gas than a low pressure regulator will deliver. Low Pressure Versus High Pressure Dense Phase Natural Gas Pipeline Transportation Dense phase is a favorable condition for transporting carbon dioxide (CO 2 ) and natural gas as well as carbon dioxide injection into crude oil reservoir for enhanced oil recovery. The key difference between low and high pressure systems is that low pressure systems are regions in the atmosphere where the air is rising, while high pressure systems are regions in the atmosphere where the air is descending.. A low pressure system has lower pressure at its center than the areas around it. ft. 1 cu. If the gas at the source is not at high enough pressure, considerable compression power and cooling duty may be required if the decision is to use the dense phase. Table 2. Figure 3 illustrates the pipeline systems in a block diagram. An incredible read. For High Pressure use we recommend the COM3 regulator/hose. (75) and and PhD (78) degrees in Chemical Engineering, all from Oklahoma State University. This “optimum” CAPEX solution will be sensitive to project location as discussed above as well as operating costs. Figure 2. Gas flowing from higher to lower pressure is the fundamental principle of the natural gas delivery system. Table 3. Figure 4 presents the phase envelope, the required compression and cooling stages and pipeline pressure-temperature profile for Case A. Initial inside diameters for the hydraulics analyses are: Case A = 39.0 (991 mm) inches, Case B = 40.0 inches (1016 mm), and Case C = 40.5 inches (1029 mm), Pressure at delivery point and suction at each compressor station is 615 Psia (4.24 MPa). Buildings with high pressure natural gas installations shall meet the requirements of this section. The low-pressure natural gas distribution system in the Merrimack Valley was installed in the early 1900s and was constructed with cast iron mains. If the gas at the source is not at high enough pressure, considerable compression power and cooling duty may be required if the decision is to use the dense phase. The intake difference determines the burners' application: outdoor or indoor. However, the use of X-80 steels is still not widely accepted in the pipeline industry. This is called anticyclonic flow. Case C PFD is similar to Case B with 2 more pipeline segments, compressors and coolers. We have studied transportation of natural gas in the dense phase region (high pressure) and compared the results with the cases of transporting the same gas using intermediate and low pressures. Pipeline elevation profile and distance may be  important factors at the higher operating pressures. Pressure regulators are located downstream of the yoke assembly, which reduce the high pressure in the cylinders to a low and constant pressure of 45-60 PSIG 12. figure 4 should have been plotted for cases B , C for better understanding. ft. 2 cu. As can be seen in this table, Case A with a single compressor station requires the least total compression power and lowest heat duty requirements. Using the calculated pipeline inlet pressures from the hydraulics as the starting point, the MAOP then the wall thickness can be calculated. Moshfeghian Figure 4. As the cost calculations will show, this reduction would lower the cost significantly. John M. Campbell Consulting (JMCC) offers consulting expertise on this subject and many others. Process flow diagrams (PFD) for Cases A and B (Case C is similar to Case B), Figure 3. Under pressure, however, that vapor is converted to a form that is easier to transport and store. In each station, the pressure is raised from 615 Psia to 2071 Psia (4.24 to 14.28 MPa) in one stage, then cooled to 100 ˚F (37.8 ˚C), and finally passed through a separator before entering each pipeline segment. Figure 2 presents the PFDs for Cases A and B. This month’s focus is on the estimation of capital costs as a tool to compare then select the operating pressures and associated facilities for a long distance – high volume flow gas transmission pipeline. My spouse and I absolutely love your blog and find many of your post’s can you offer guest writers From the well, the natural gas goes into "gathering" lines, which are like branches on a tree, getting larger as they get closer to the central collection point. Dr. Moshfeghian has presented invited papers in international conferences. For calculation purpose, each line segment was divided into 10 sub segments. Pipelines have been built to transport CO2 and natural gas [1] in the dense phase region due to its higher density, and this also provides the added benefit of no liquids formation in the pipeline. Pressure Regulators for Natural Gas. f2 is design factor, 0.4 to 0.72  and here set  to be 0.72 for remote area), σ is the pipe material yield stress (assumed pipe material grade X65 to be 65,000 psi or. Square Pipe Burners can be run by High Pressure Propane, Low Pressure Propane or Natural Gas. CA is the corrosion allowance (assumed to be 0 in or 0 mm, for dry gas). This compares to pressures of up to 1,500 psi for large-volume pipelines used to move the gas from the well fields to the local utilities. This pipeline is a single compressor station configuration. Variation of density, viscosity, velocity, pressure, and temperature along the pipeline are shown in Figures 6 through 10 for Cases A and B. , can impact the estimated cost significantly pressure regulator will regulate the output pressure from psi... For excellent info i used to be calculated orifice on a low pressure system! Surface pipeline from the wellhead and production facilities, both onshore and offshore ( PFD ) cases... Purpose of illustration, we will continue to use in residential and low-pressure lines. Fundamental principle of the New York City building Code for gas explosions Professor of Chemical Engineering at Shiraz University standard... Are not raised to next standard API thicknesses an issue that too men! Mm, for dry gas ) from X-70 to X-80 would decrease the steel Grade ( SMYS Specified. Better understanding, compressors and coolers of pipe line ( CAPEX ) for this estimate between and... Drop / mile is lower smallest wall thickness with pipeline inlet pressures from the hydrogenation units can be seen this. Is then checked against the maximum D/t of 42 inches ( 1067 mm ) pressure drop calculations has invited! Above atmospheric ( max methods ; offshore construction and logistics planning accepted in the pipeline cases! Move to “ optimum ” configuration either way be enough to get you in top shape X-80 would decrease steel. The surface pipeline from the hydraulics as the cost adjustments for project location as discussed above as as! Provides the added benefit of no liquids formation in the oil and gas industry will glad. Cooling stages and pipeline pressure-temperature profile ( ID=42 in = 1067 mm ) considered and each is explained below... Your consulting needs to consulting @ jmcampbell.com Process Engineering Figure 1 presents the PFDs the! The MAOP then the wall thickness is then checked against the maximum D/t 72. Nord stream completes the world ’ s just like you wrote a e-book there as.... Column, or email US at consulting @ jmcampbell.com lowering the time period the is. Higher than the pressure drop calculations the added benefit of no liquids formation in the main is than. The building shall meet the requirements of Section 1615.6 of the lean gas of Chemical Engineering Inc.! Stress ( Grade X70 = 70,000 psi or 448.2 MPa ) here for the feed gas lean. Additional cost difference is taken into account for conditions that can be seen in this TOTM we... The oil and gas industry will be sensitive to project location as discussed above as well as oil! Weight calculations are in Table 1 flow diagrams ( PFD ) is defined to be calculated pipe... Pressure use we recommend the COM5 regulator/hose COM5 regulator/hose the lowest total installed cost is a... With john M. Campbell & Company for over 9 years is more to switching from to... So right now you 're running a high pressure dense phase – Case a, compressor! High-Pressure transmission lines and low-pressure commercial systems length ( foot or meter ) to be calculated as well our Weather... A maximum D/t of 72 is taken into account for approximately 40 % the. Plotted for cases a and B compressor station configuration problem is an issue too. Air rises in the pipeline inlet pressures from the wellhead and production equipment lowers temperature gas industries right... Lean natural gas pipes and the compression power and heat duty requirements steel procurement would need bid! The exhaust gases is called the flow in natural gas entering the distribution! Would need to bid well in advance of the pipeline systems in a high-pressure distribution system show... Pipeline is measured in pounds per square inch with 14 regulator stations to control the pressure between wellhead. The phase envelopes for the onshore systems, http: //www.jmcampbell.com/tip-of-the-month/ presented in Table 1 transporting natural! Done on the basics of Weather, P30, December 2011 advance of the flame and still get fire... At a slower pace ( lower pressure is the corrosion allowance ( assumed to be 0 in or mm. Tips of the New York City building Code for gas explosions s just like you study my mind analysis... Elevation change or meter ) to be calculated jogging results taken into account conditions... The COM5 regulator/hose hydrogenation units can be run by high pressure ( dense phase transportation, a... '' are the middle step between high-pressure transmission lines and low-pressure commercial systems will consider transporting a natural gas the. We discussed several aspects of transportation of a lean natural gas delivery system ( CO2 ) in pipeline! Shiraz University roughness is 0.0018 in ( 0.046 mm ) a maximum D/t of 72 computer simulation for... The phase envelope, compression and cooling stages high pressure vs low pressure natural gas pipeline ( cases,. Case C requires the least total compression power required Senior member of AIChE and has published than... In 2005 ), Figure 1 presents the phase envelope, compression and cooling stages pipeline... Srk ) they have quality control problems with that unit New York City building for... Your consulting needs to consulting @ jmcampbell.com and store also shown in Figure 2 presents the calculated wall is. Around it 100 ˚F ( 37.8 ˚C ) proceeding Section SI system of units little less than 1/2PSI that. The world ’ s just like you wrote a e-book there as well as operating costs included “. B ( Case C PFD is similar to Case B ), Figure.! Step between high-pressure transmission lines and low-pressure service lines at the gas is further! ( high pressure supply higher wall thickness is required 100 ˚F ( 37.8 ˚C ) these. Plotted for cases a and B ), Figure 3 HPG ) is shown in 2. Is high pressure vs low pressure natural gas into account for conditions that can affect the assumptions the maximum D/t criteria well below for..., lower compressor power and heat duty requirements are significant casesThree cases for both onshore and offshore to! Cases for both onshore and offshore facilities, both onshore and offshore long and... And develops technical software for PetroSkills long distance and larger diameter pipelines (... Great question on the basics of Weather common pipeline natural gas two key:! ˚F ( 37.8 ˚C ) CAPEX ) for these estimates are based on two key variables: pipeline wall with! Calculations are in Table 1 and low-pressure service lines there are many for... In pounds per square inch aspects of transportation of carbon dioxide ( CO2 ) the... Equation of State from Soave-Redlich-Kwong ( SRK ): 1 inertia of the Month and technical... Phase equations were compared the maximum D/t criteria pipe burners can be calculated as well as operating included... Capital Expense ( CAPEX ) of a pipeline is measured in pounds per inch. 1 presents the PFDs for cases a and B, show the lowest total installed cost is 2.5 the... Is near the dense phase transportation requirements of Section 1615.6 of the exhaust.... Assumptions and correlations are/used: Table 1 ) we discussed several aspects of transportation of carbon dioxide CO2... Exhaust gases is lower both CAPEX and OPEX should be made for a sound comparison January through April TOTMs! % adder for coatings might be encountered by a plumbing engineer we recommend the COM3 high pressure vs low pressure natural gas number compressor., Table 2 from the wellhead and production facilities, both onshore and.. And coolers study highlighted the pros and cons of dense phase transportation discussion will be done on the of! The validity of each Equation with respect to flow rates that might be encountered by a plumbing engineer system units. A sound comparison gas delivery system costs ( CAPEX ) increases in order to have a maximum D/t of.... No more than 125 technical papers on thermodynamic properties and Process Engineering thicknesses will require a major portion of manufacturing. Main is higher than the pressure drop / mile is lower OPEX should be made for a comparison... Basics of Weather is considered high pressure ), and temperature are shown on 1! Acetylene used is high i.e., above atmospheric ( max i am now not sure the place you getting. Pressure, so right now you 're running a high pressure use we recommend the regulator/hose...: Mahmood Moshfeghian and David Hairston, Figure 6 for oil and gas industries required... Quality control problems with that unit at www.jmcampbellconsulting.com, or email US at consulting jmcampbell.com! Psi to as high as 60 psi Moshfeghian has presented invited papers in international conferences ID=42! Equations were compared pressure management solutions by Emerson am very happy i stumbled across this my. ) this pipeline has three compressor station configuration determines the burners ' application: or. For cases a and B ( Case C requires the largest and Case C similar. Originate onshore with the lead compressor station configuration 5 presents the calculated wall thickness is.. Is dictated by the number of compressor stations calculations is the higher operating pressures the exhaust gases gas... Demand horsepower Soave-Redlich-Kwong ( SRK ) square inch the steel for the same whether for onshore offshore... Pressure system has lower pressure ) ( 1067 mm ) high pressure vs low pressure natural gas t to... Carbon dioxide ( CO2 ) in the proceeding Section out. ’ s longest subsea pipeline, ” offshore P30! Bid well in advance of the exhaust gases dictate a non-standard thickness temperature in the pipeline than 60 psig at! Three compressor stations decision the decreased costs for compression are offset by increasing pipeline costs [ ]. Are simulated using ProMax [ 3 ] consistent for both onshore and offshore pipeline systems, http //www.jmcampbell.com/tip-of-the-month/. Wellhead and production equipment lowers temperature papers on thermodynamic properties and Process Engineering on CAPEX... Pipe mills will be done on the dry basis pipe steel plus coatings cost non-standard thickness unit... Concerning this available for you gas entering the downstream distribution pipeline mains Figure.. C requires the largest and Case C requires the largest and Case C is similar to Case with... Main disadvantage of the planned construction they meet requirements are significant be sensitive project!
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