Bleed Rates of Controllers

Meta-Protocol for Oil and Gas Emission Reduction Projects:

High-Bleed to Low-Bleed Conversion of Pneumatic Controllers

Developed by Blue Source Canada for the Pacific Carbon Trust March 2011 Version 1.1

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Table of Contents

1. Project Scope and Description .......................................................................... 1

2. Module Scope and Description ........................................................................ 1 2.1. Module Approach ............................................................................................. 2 2.2. Module Applicability ......................................................................................... 2 2.3. Module Flexibility ............................................................................................. 3

3. Project Reporting .............................................................................................. 5

4. Glossary of New Terms ..................................................................................... 7

5. Quantification Development and Justification ................................................. 8 5.1. Identification of Sinks and Sources in the Project Condition ........................... 8 5.2. Identification of the Baseline Condition ......................................................... 10 5.3. Selection of Relevant Project and Baseline SSRs ............................................ 11 5.4. Quantification of Reductions, Removals, and Reversals of SSRs ................... 13

5.4.1. Quantification Approach ........................................................................... 13 5.4.2. Accuracy .................................................................................................... 17

List of Appendices Appendix A: Flexibility Mechanism Appendix B: Bleed Rate Quantification Appendix C: Device Inventory Appendix D: Contingent Data Collection Appendix E: Reference Controller Bleed Rates List of Tables Table 3.1: Key Data Project Reporting Table ...................................................................... 6 Table 5.1: Project SSRs ........................................................................................................ 9 Table 5.2: Baseline SSRs .................................................................................................... 10 Table 5.3: Comparison of SSRs .......................................................................................... 12 Table 5.4: Quantification Procedures ............................................................................... 14 List of Figures Figure 2.1: Process Flow Diagram for Project Condition .................................................... 4

Figure 2.2: Process Flow Diagram for Baseline Condition .................................................. 4

Figure 5.1: Project Element Lifecycle Chart ........................................................................ 8

Figure 5.2: Baseline Element Lifecycle Chart .................................................................... 10

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This module is an adaptation of the American Carbon Registry Protocol for Emission Reduction Measurement and Monitoring Methodology for the Conversion of High-Bleed Pneumatic Controllers in Oil and Natural Gas Systems. It is meant to be used in conjunction with the Meta-Protocol Introduction and is not a standalone document.

1. Project Scope and Description

Pneumatic controllers use pressurized gas (typically natural gas) for applications in the oil and gas production industry to regulate process variables such as pressure, flow rate and liquid level. Most pneumatic instruments and controllers in the natural gas industry are powered by natural gas, and these controllers are designed to discharge methane to the atmosphere as a part of normal operations. Pneumatic controllers can be designed at both high- and low-bleed rates. In addition, controllers may be self-contained and release gas into the downstream pipeline instead of venting to the atmosphere. Before 1990, all controllers were designed with generally high-bleed rates. It has now become standard practice to use low-bleed pneumatic controls in new construction in the oil and gas industry. Despite the existence of low-bleed technology as well as retrofit solutions, conversions of existing high-bleed controllers are uncommon. The opportunity for generating carbon offsets with this module arises from the direct and indirect reduction of greenhouse gas emissions resulting from the conversion of high-bleed pneumatic controllers to low-bleed/self-contained pneumatic controllers.

2. Module Scope and Description

This module is applicable to the conversion of high-bleed pneumatic controllers to low-bleed/self-contained pneumatic controllers, where operating conditions and requirements permit such conversions. Both snap-acting and throttle acting high-bleed pneumatic controllers are addressed in this module. In some operational applications, such as the control of very large valves that require fast or precise process changes, high-bleed controllers should not be replaced with low-bleed/self-contained controllers. A process flow diagram for a typical project converting high-bleed controllers to low-bleed/self-contained controllers is shown in Figure 2.1. Note that self-contained controllers may be included under the low-bleed controller SSR. The dashed arrows show that pneumatic controllers may or may not be used at each stage of natural gas processing, extraction, and transportation as many different process control configurations are possible.

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2.1. Module Approach

The baseline scenario is the continued use of high-bleed pneumatic controllers. Baseline emissions are comprised of the natural gas vented to the atmosphere from these high-bleed controllers. Manufacturer’s data for bleed rates of controllers are established under laboratory operating conditions and are not reflective of field operating conditions.1 Therefore, emissions in the baseline condition will be determined through site-specific monitoring of a representative sample of the population of high-bleed controllers to be retrofitted. Baseline emissions will be projected from project operating hours. Project bleed rates will also be extrapolated from a series of representative sample measurements of the population of low bleed devices. Further information on the measurement and calculation of emissions can be found in Appendix B. A typical baseline process flow diagram is shown in Figure 2.2. The dashed arrows show that pneumatic controllers may or may not be used at each stage of natural gas processing, extraction, and transmission, because many different process control configurations are possible.

2.2. Module Applicability

To demonstrate that a project meets the requirements under this module, the project developer must supply sufficient evidence to demonstrate that:

1. The project involves the conversion of existing high-bleed controllers to low-bleed controllers and does not involve end of life replacements or new installations. This may be demonstrated by facility process flow diagrams and/or accounting records, work orders, invoices or other vendor/third party documentation/evidence. See Appendix B of the Meta-Protocol Introduction for more details on establishing end of life.

2. In certain applications, controllers may reach the end of their useful lives during

the crediting period for the project. To determine if any controller included in the project would normally have been replaced with a low-bleed alternative during the crediting period for a reason other than the project activity, the project proponent should provide the following information. More detail on establishing end of life can be found in Appendix B of the Meta-Protocol Introduction.

a. The project proponent should describe current practice for routine refurbishment of controllers and should provide to the verifier the

1 CAPP Fuel Gas Best Management Practices: Efficient Use of Fuel Gas in Pneumatic Instruments. May

2008.

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standard operating procedure, if any, for routine refurbishment of pneumatic controllers, including replacement specifications published by the controller’s manufacturer if available.

b. Any controllers which would have been so replaced during the crediting period should be identified with the expected date of such replacement stated, and no emission reductions credited for that controller after that date.

3. To facilitate verification and allow for changes in the facility, the proponent will

develop an inventory of devices to be maintained annually. Any changes to the inventory, i.e. low-bleed controllers added, will impact net offsets claimed. A sample inventory tracking sheet can be found in Appendix C.

2.3. Module Flexibility

Flexibility in applying the quantification protocol is provided to project developers in the following ways. If applicable, the proponent must indicate and justify why flexibility provisions have been used.

1. If necessary, proponents may use a sample size greater than 30 controllers to determine bleed rates for high-bleed and low-bleed controllers, for greater accuracy in estimating controller population bleed rates.

2. In facilities that have already converted from high bleed controllers, the project developer may claim carbon offsets if the project implementation was after November 29th, 2007. Quantification guidance for retroactive credits can be found in Appendix A.

3. If annual measurements of project pneumatic controllers are not performed, a

discount factor may be applied to adjust the baseline and project emissions. Refer to Appendix A for details.

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Figure 2.1: Process Flow Diagram for Project Condition

Figure 2.2: Process Flow Diagram for Baseline Condition

P4 Low-Bleed Pneumatic Controllers

P6 Raw Gas

Production

P9 Processed Gas Distribution

and Sale

P8 Raw Gas

Processing

P7 Raw Gas

Transportation

P5 Fuel Gas for

Facility

B4 High-Bleed Pneumatic Controllers

B6 Raw Gas

Production

B9 Processed Gas Distribution

and Sale

B8 Raw Gas

Processing

B7 Raw Gas

Transportation

B5 Fuel Gas for

Facility

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3. Project Reporting

The project reporting table provided below is meant to assist validators and verifiers in identifying key project data monitoring requirements. These are the minimum monitoring requirements necessary to quantify emissions. In no way does Table 3.1 purport to provide a complete summary of monitoring requirements. It is the responsibility of project proponents to correctly quantify emissions reductions using the methods set out in this module. In addition, the following checklist serves as a summary of module applicability requirements that may be reviewed to ensure that each project meets the requirements of this module. It is the responsibility of project proponents to correctly assess applicability requirements as laid out in this module. Applicability Checklist Low-bleed controllers are installed as a retrofit and not installed on brand new

instruments at a new facility. Offsets are not generated for end-of-life replacements of high-bleed controllers. An inventory is used to keep track of replaced controllers, equipment types, etc.

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Table 3.1: Key Data Project Reporting Table

High-Bleed to Low-Bleed Controller Conversion Reporting Table

Installation ID:

Yearly Monitoring Requirements Date of Fuel

Gas Analysis

Basin/ Site Location of

Fuel Gas Analysis

CH4 Content of Gas

CO2

Content of Gas

Project Hours of

Operation

Bleed Rate Project

Bleed Rate Baseline

Actuation Percent*

Total Emission Reductions

- - % % hours m3/hour m3/hour % time t CO2e

*Only necessary for snap acting controllers to calculate actuating time. For a more information, see Appendix B.

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4. Glossary of New Terms

Bleed Rate: Rate at which a device uses air or natural gas due to design requirements. Rates may be continuous or intermittent and may vary in the field due to changing conditions.

High-Bleed Pneumatic Controllers: A device used commonly in the oil and gas

industry for process control, which has a

bleed rate in excess of 0.17 m3/h (6 ft3/h).

Low-Bleed Pneumatic Controllers: A device used commonly in the oil and gas

industry for process control, which has a

bleed rate less than 0.17 m3/h (6 ft3/h).

Snap-Acting Pneumatic Controllers: These controllers only vent gas when a

process change is required. This device

either actuates fully or not at all - in other

words, it is either “on” or “off” with no

proportionality. Typically, Snap-Acting

Controllers are used for level control or

emergency shutdown procedures.

Self-Contained Pneumatic Controllers: A device used commonly in the oil and gas

industry for process control, which does not

bleed to the atmosphere but captures vent

gases and reintroduces them into the

downstream pipeline.

Throttle-Acting Pneumatic Controllers: These controllers are designed for steady-

state operation. They require constant

supply and venting of gas, and therefore

bleed continuously. They are used to

control flow, pressure, temperature, and

liquid level.

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5. Quantification Development and Justification

5.1. Identification of Sinks and Sources in the Project Condition

SSRs were identified for the project by reviewing the seed documents and relevant process flow diagrams pertaining to the operation of natural gas processing facilities. This process confirmed that the SSRs in the process flow diagrams covered the full scope of eligible project activities under the methodology.

Based on the process diagrams provided in Figure 2.1, the project’s SSRs were organized into lifecycle categories in Figure 5.1. A description of each of the SSRs and their classification as controlled, related or affected is provided in Table 5.1. Note that SSRs previously defined in the Meta-Protocol Introduction are excluded from Figure 5.1 and Table 5.1 for brevity.

Figure 5.1: Project Element Lifecycle Chart

Upstream SSRs During Project

Upstream SSR Before Project

SSRs During Project

Downstream SSR After Project

Downstream SSRs During Project

P9 Processed Gas Distribution

and Sale


P8 Raw Gas

Transportation

P7 Raw Gas

Transportation

P6 Raw Gas

Production

P5 Fuel Gas for

Facility

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Table 5.1: Project SSRs 1. SSR 2. Description 3.Controlled,

Related, or Affected

Upstream SSRs During Project Operation

P6 Raw Gas Production

The raw gas is collected from a group of adjacent wells where moisture content is reduced by removing water and condensate. Condensate is transported to oil refineries for further processing and wastewater is disposed. Leaks may be present in the production facility.

Related

P7 Raw Gas Transportation

The raw gas is piped to a natural gas processing plant. Leaks may also be present in the pipeline.

Related

P8 Raw Gas Processing

Processing of raw gas is required to remove hydrogen sulphide, carbon dioxide, water vapour, and heavier hydrocarbons. Clean gas is ready to be distributed and sold. Heavier hydrocarbons are also removed and transported to oil refineries.

Related

P5 Fuel Gas For Facility Processes

Many processes in the facility require clean gas to function. This clean gas, also referred to as fuel gas, is drawn from the processed gas that will be sold. Equipment in the processes includes compressors, boilers, heaters, engines, glycol dehydrators, refrigerators, and chemical injection pumps (CIP). The methane and carbon dioxide content of the processed gas would need to be tracked. Leaks may also be present in the production facility.

Related

Onsite SSRs During Project Operation


Process control for temperature, pressure, flow, emergency shutdown, etc., may be required for raw gas production, processing, and distribution. Emissions in the project are attributed to the venting associated with Low-Bleed Pneumatic Controller operation. Self-Contained Pneumatic Controllers are also included under in this SSR. Emissions from project controllers may be continuous, intermittent, or zero, depending on controller design. Only controller retrofits are included here. Operating hours of the controller should be tracked.

Controlled

Downstream SSRs During Project Operation

P9 Processed Gas Distribution and Sale

Natural gas and other commercially viable NGL products may be sent to a pipeline system or transported by rail or truck to customers at another point. Greenhouse gas emissions are avoided from the conservation of fuel gas that was supplied to the control instrumentation in the baseline. It is assumed that the most likely use of avoided fuel gas consumption would be controlled combustion to produce carbon dioxide.

Related

Other

N/A

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5.2. Identification of the Baseline Condition

The selected baseline scenario was a projection based approach. In this method of quantification, the operating hours of low-bleed controllers in the project condition represent an equivalent amount of operating hours in the baseline condition, thus establishing functional equivalence between the baseline and the project condition. Baseline emissions are determined by using different bleed rates for each type of high-bleed technology. Bleed rates will be extrapolated from a series of representative sample measurements from the baseline population. Appendix B details quantification methods for this bleed rate. Figure 5.2: Baseline Element Lifecycle Chart

Upstream SSRs During Baseline

Upstream SSR Before Baseline

SSRs During Baseline

Downstream SSR After Baseline

Downstream SSRs During Baseline

Table 5.2: Baseline SSRs 1. SSR 2. Description 3.Controlled,

Related, or Affected

Upstream SSRs During Baseline Operation

B6 Raw Gas Production

The raw gas is collected from a group of adjacent wells where moisture content is reduced by removing water and condensate. Condensate is transported to oil refineries for further processing and wastewater is disposed. Leaks may be present in the production facility.

Related

B7 Raw Gas Transportation

The raw gas is piped to a natural gas processing plant. Leaks may also be present in the pipeline.

Related

B8 Raw Gas Processing

Processing of raw gas is required to remove hydrogen sulphide, carbon dioxide, water vapour, and heavier hydrocarbons. Clean gas

Related

B9 Processed Gas Distribution

and Sale

B4 Low-Bleed Pneumatic Controllers

B5 Fuel Gas for

Facility

B8 Raw Gas

Transportation

B7 Raw Gas

Transportation

B6 Raw Gas

Production

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1. SSR 2. Description 3.Controlled, Related, or Affected

is ready to be distributed and sold. Heavier hydrocarbons are also removed and transported to oil refineries.

B5 Fuel Gas For Facility Processes

Many processes in the facility require clean gas to function. This clean gas, also referred to as fuel gas, is drawn from the processed gas that will be sold. Equipment in the processes includes compressors, boilers, heaters, engines, glycol dehydrators, refrigerators, and chemical injection pumps (CIP). The methane and carbon dioxide content of the processed gas would need to be tracked.Leaks may also be present in the production facility.

Related

Onsite SSRs During Baseline Operation

B4 High-Bleed Pneumatic Controllers

Process control for temperature, pressure, flow, emergency shutdown, etc., may be required for raw gas production, processing, and distribution. Emissions in the baseline are attributed to the venting associated with High-Bleed Pneumatic Controller operation. Emissions from high-bleed controllers may be continuous or intermittent, depending on controller design. Only high-bleed controllers which have been retrofitted are included here.

Controlled

Downstream SSRs During Baseline Operation

B9 Processed Gas Distribution and Sale

Natural gas and other commercially viable NGL products may be sent to a pipeline system or transported by rail or truck to customers at another point. Greenhouse gas emissions are avoided from the conservation of fuel gas that was supplied to the control instrumentation in the baseline. It is assumed that the most likely use of avoided fuel gas consumption would be controlled combustion to produce carbon dioxide.

Related

Other

N/A

5.3. Selection of Relevant Project and Baseline SSRs

Each of the SSRs from the project and baseline condition were compared and evaluated as to their relevancy in quantification of greenhouse gas emissions and reductions using ISO 14064-2:2006. SSRs were identified as controlled, related or affected and included or excluded for quantification. The justification for the exclusion or conditions upon which SSRs may be excluded is provided in Table 5.3 below.

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Table 5.3: Comparison of SSRs

1. Identified SSR 2. Baseline (C, R, A)

3. Project (C, R, A)

4. Include or Exclude from Quantification

5. Justification for Exclusion

Upstream SSRs

P6 Raw Gas Production

N/A Related Excluded The production of raw gas is negligibly impacted by the implementation of the project. Conservation of fuel gas in the project condition reduces project emissions. Conservativeness is increased by the exclusion of this SSR.

B6 Raw Gas Production Related N/A Excluded

P7 Raw Gas Transportation

N/A Related Excluded The transportation of raw gas is negligibly impacted by the implementation of the project. Conservation of fuel gas in the project condition reduces project emissions. Conservativeness is increased by the exclusion of this SSR.

B7 Raw Gas Transportation

Related N/A Excluded

P8 Raw Gas Processing

N/A Related Excluded The processing of raw gas is negligibly impacted by the implementation of the project. Conservation of fuel gas in the project condition reduces project emissions. Conservativeness is increased by the exclusion of this SSR.

B8 Raw Gas Processing Related N/A Excluded

P5 Fuel Gas For Facility

N/A Related Excluded Production, processing, and transportation operations are not impacted by the retrofit. Therefore, any incremental reduction in fuel gas use in the project condition can be directly attributed to reduced venting. Emissions from reduced venting are already accounted for in P4 Vented Emissions and B4 Vented Emissions.

B5 Fuel Gas for Facility Related N/A Excluded

Onsite SSRs

P4 Low-Bleed Pnuematic Controllers

N/A Controlled Included N/A

B4 High-Bleed Pnuematic Controllers

Controlled N/A Included N/A

Downstream SSRs

P6 Downstream Fluid Processing

N/A Related Excluded Excluded as downstream fluid processing is not impacted by the implementation of the project and as such the baseline and the project conditions will be functionally equivalent.

B6 Downstream Fluid Processing

Related N/A Excluded

Other

N/A

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5.4. Quantification of Reductions, Removals, and Reversals of SSRs

5.4.1. Quantification Approach

Quantification of the reductions, removals and reversals of relevant SSRs for each of the greenhouse gases will be completed using the methodologies outlined in Table 5.4, below. These calculation methodologies serve to complete the following three equations for calculating the emission reductions from the comparison of the baseline and project conditions. The general approach is to calculate the offsets as follows:

Where:

Emissions Baseline = sum of the emissions under the baseline condition. Emissions Vented Emissions = emissions under SSR B4 High Bleed Pneumatic Controllers

Emissions Project = sum of the emissions under the project condition. Emissions Vented Emissions = emissions under SSR P4 Low Bleed Pneumatic Controllers

Emissions Baseline = Emissions High Bleed Pneumatic Controllers

Emissions Project = Emissions Low Bleed Pneumatic Controllers

Emission Reduction = Emissions Baseline – Emissions Project

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Table 5.4: Quantification Procedures

1. Project / Baseline SSR

2. Parameter / Variable

3. Unit 4. Measured / Estimated

5. Method 6. Frequency

7. Justify measurement or estimation and frequency

Project SSRs

P4 Low Bleed Pneumatic Controllers

2

Emissions Low-Bleed = Σ (Bleed Rate Low-Bleed,i × Op.Hours i × %CH4 × ρCH4 × GWPCH4); Σ (Bleed Rate Low-Bleed,i × Op.Hours i × %CO2 × ρCO2)

Emissions Vented from Low-Bleed Controllers /Emissions High Bleed

kg of CO2e N/A N/A N/A Quantity being calculated in aggregate form.

Bleed Rate of Low Bleed Controller i/Bleed Rate Low-Bleed i

m3/h Measured

Direct measurement; See Appendix B.

Annually Annual sampling prior to verification will give a high degree of accuracy.

Operating Hours of Controller i /Op. Hours i

h Estimated Data taken from facility operating records

Monthly

Monthly reconciliation of operating records will provide a high degree of assurance.

Percentage of CH4 in vented gas by volume/%CH4

% volume Measured Direct measurement Annually Fuel gas composition should remain relatively stable.

Percentage of CO2 in vented gas by volume/%CO2

% volume Measured Direct measurement Annually Fuel gas composition should remain relatively stable.

Density of CH4 / ρCH4

kg/m3

Constant

0.678 kg/m3 at 15°C and

101.3 kPa, the standard reference conditions used by the natural gas industry.

Reference Value

N/A

Density of CO2 / ρCO2

kg/m3

Constant

1.86 kg/m3

at 15°C and 101.3 kPa, the standard reference conditions used by the natural gas industry.

Reference Value

N/A

2 Actuation time has been excluded to increase the conservativeness of the estimate.

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Global Warming Potential of CH4/ GWPCH4

kg CO2e/kg CH4 Estimated IPCC Annually

The GWP of CH4 is 21, as per Intergovernmental Panel on Climate Change (IPCC) and International Standards Organization (ISO).

Baseline SSRs

B4 High Bleed Pneumatic Controllers

Emissions High-Bleed = Emissions Snap-Acting + Emissions Throttle

The following equation is used to determine vented emissions from snap-acting controllers. Emissions Snap-Acting = Σ (Bleed Rate Snap-Acting,i × Op.Hoursi × %CH4 × ρCH4 × (1 - ATi) × GWPCH4 );

Σ (Bleed Rate Snap-Acting,i × Op.Hoursi × %CO2 × ρCO2 × (1 - ATi) )

The following equation is used to determine vented emissions from throttle controllers. Emissions Throttle = Σ (Bleed Rate Throttle i × Op.Hoursi × %CH4 × ρCH4× GWPCH4);

Σ (Bleed Rate Throttle i × Op.Hoursi × %CO2 × ρCO2)

Emissions Vented from High-Bleed Controllers /Emissions High Bleed


Emissions Vented from Snap-Acting Controllers /Emissions Snap-Acting


Emissions Vented from Throttle Controllers /Emissions Throttle

kg of CO2e N/A N/A N/A

Quantity being calculated in aggregate form.

Bleed Rate of Snap Acting Controller i/Bleed RateSnap-Acting i m

3/h Measured

Direct measurement; See Appendix B

Once

Annual sampling of a representative sample of the population size with a 95% confidence interval gives a high level of assurance.

Bleed Rate of Throttle Controller I /Bleed Rate Throttle i m

3/h Measured

Direct measurement; See Appendix B

Once

Annual sampling of a representative sample of the population size with a 95% confidence interval gives a high level of assurance.

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Operating Hours of Controller i /Op. Hours

h Estimated

Equal to operating hours of low-bleed controller

which replaced high-bleed controller

Monthly

Monthly reconciliation of operating records will provide a high degree of assurance.


% volume Measured Direct measurement Annually Annual sampling prior to verification will give a high degree of accuracy.


% volume Measured Direct measurement Annually Annual sampling prior to verification will give a high degree of accuracy.

Density of CH4 / ρCH4

kg/m3

Constant

0.678 kg/m3 at 15°C and

101.3 kPa, the standard reference conditions used by the natural gas industry.

Reference Value

N/A

Density of CO2 / ρCO2

kg/m3

Constant

1.86 kg/m3

at 15°C and 101.3 kPa, the standard reference conditions used by the natural gas industry.

Reference Value

N/A

Global Warming Potential of CH4/ GWPCH4

kg CO2e/kg CH4 Estimated IPCC Annually

The GWP of CH4 is 21, as per Intergovernmental Panel on Climate Change (IPCC) and International Standards Organization (ISO).

Percentage of Actuation Time (No Vent Gas Flow) to Total Time for Controller i/ ATi

% time Measured See Appendix B Annually

Sampling a representative sample of the population size with a 95% confidence interval gives a high level of assurance.

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5.4.2. Accuracy

The bleed rates of controllers are highly variable. This uncertainty is addressed by using a statistical analysis to determine the upper and lower bound within which the average controller operates with 95% certainty. By using the upper bound in the baseline condition and the lower bound in the project condition, a conservative estimate of bleed rates is established to reduce the uncertainty associated with controller bleed rates. Actuation time has a medium level of uncertainty. To ensure a conservative estimate of emissions reductions are given, actuation time has been excluded in the project condition (i.e. all snap acting controllers are assumed to be bleeding 100% of the time). Other parameters such as operating hours and concentration of methane and carbon dioxide in fuel gas can be determined with a high level of accuracy.

APPENDIX A: FLEXIBILITY MECHANISM QUANTIFICATION

A-I |

A.1 Retroactive Credits Retroactive credits may be claimed where facilities have already converted high bleed controllers to low bleed/self contained controllers. To determine the bleed rate of high-bleed controllers, two options are available. The preferred method is to reinstall high bleed devices or to take measurements at other sites that have the same makes and models of high bleed devices as outlined in Appendix B. Where this is not possible, bleed rates may be estimated using manufacturer’s specifications. Bleed rates for low bleed controllers should be determined as outlined in Appendix B. Bleed rates can be used retroactively for a period of two years. For example, if the samples for the bleed rate were taken on April 2nd, 2011, they may be used in emission reductions calculations for retroactive credits up to April 1st, 2009. This flexibility mechanism does not apply in cases where annual measurements of project controllers were missed.

A.2 Discount Factor for Missed Annual Bleed Rate Monitoring Where annual measurements of project controllers were missed, emission reductions may be calculated using bleed rates from the previous year of monitoring. A discount factor is applied to the total emissions reductions, based on the number of years since Bleed Rates have been monitored. A 5% discount factor is applied per year. Table A1 shows the discount factor used for the number of missed annual measurements. Table A1: Discount Factor for Missed Annual Bleed Rate Monitoring3

Number of Years Since Last Bleed Rate

Sampling

Discount Factor

≤1 N/A

>1 5%

2 10%

3 15%

3 According to the EPA, Leaks increase by 25% for equipment which has not been serviced in the past 5 to 10 years.

Therefore, it is assumed that equipment may leak an additional 5% per year. The repair of this equipment would result in a 5% decrease in bleed rate, and therefore a 5% decrease in emission reductions. See EPA Gas Star Lessons Learned: Convert Gas Pneumatic Controllers to Instrument Air, available at http://www.epa.gov/gasstar/documents/ll_instrument_air.pdf

APPENDIX B: BLEED RATE QUANTIFICATION

B-I

B1 Bleed Rate of Controllers Sampling Procedure For any make and model of device (High or Low Bleed), sample bleed rates will be taken from a minimum of 30 controllers of the population (unless there are less than 30), the estimated number samples required for statistical relevance. From these samples, bleed rates will be established for each model of controller. For example, the population of Model R100 Snap-Acting high-bleed controllers will use a different bleed rate than the population of Model X99 Snap-Acting high-bleed controllers. Flow rate or totalizing meters, or calibrated bags, may be used to monitor bleed rate. Project proponents should ensure that monitoring of snap-acting controllers captures at least one dump cycle. Confidence Intervals In order to quantify the average bleed rate of various controllers through sampling, a brief explanation of the confidence intervals follows. In statistics, a confidence interval estimates the likelihood of finding a sample within an upper and lower bound. For example, one could state there is a 90% probability that a Canadian adult is between 5 feet and 6 feet tall. In this case, the lower and upper bounds are 5 feet 6 feet respectively. The sample size is the adult population of Canada and the confidence level is 90%. Establishing Bleed Rate from Sample Data To determine the confidence interval the following equation is used. A confidence level of 95% should be used with n-1 degrees of freedom to determine the t statistic, which can be looked up in most student statistics textbooks.

Equation A1

µ = x ± t [σ/n(1/2)] Where

μ = confidence interval t = statistical constant based on confidence level and sample size n = is the sample size x = sample mean σ = sample standard deviation

The standard deviation can be calculated using the following equation.

σ = [Σ (FCi – x)2 / (n-1)] (1/2)

Equation A2

B-II

Where FC = Fuel consumption rate

x = Sample mean n = number of samples taken.

For the purposes of estimating Bleed Rates, a confidence level of 95% is used with a sample size of 30 controllers or greater. A bleed rate will be needed for each different low-bleed and high-bleed make and model. When estimating the baseline bleed rate, the upper bound will be used. When estimating the project bleed rate, the lower bound will be used. This ensures the conservativeness of the estimate. A sample calculation for the baseline condition is shown using data from a project with Invalco. Project data is presented in Table B1. Table B1 High-Bleed Pneumatic Controllers from Invalco

Manufacturer Model Bleed Rate (scfd) Data Source

Invalco Throttling 518.1 Producer 1

Invalco Snap-Acting 274.3 Producer 1

Invalco CTS-215 655.0 EPA

Invalco CTU-215 1052.2 Producer 2






Invalco CTU 540.0 Producer 3








From this sample data, using a 95% confidence level,

t = 2.120 (constant available in most statistics textbooks) σ = 237.9 n = 17 x = 628.9 µ = x ± t [s/n(1/2)] = 628.9 ± 2.120[237.9/17(1/2)] = 628.9 ± 122.3 = (506.6, 751.2)

B-III

Therefore, the bleed rates of this equipment falls between 506.6 scfd and 751.1 scfd 95% percent of the time. For the baseline condition, the lower bound, 506.6 scfd, will be used in calculations for conservativeness.

B2 Actuation Time of Snap Acting Controllers When snap-acting controllers are operating and conducting their intended function, natural gas is run through the device and is thus not bled to the atmosphere. This period of functioning, when no bleeding occurs, is called actuation. Only in their “inactive” state are snap-acting controllers – whether high-bleed or low-bleed – bleeding gas. Most snap-acting controllers are inactive, and thus bleeding, the vast majority of the time (greater than 95%). However, the project proponent should still take into account the time the device is active and not bleeding gas, so this time can be discounted from overall baseline emissions. For this methodology, the project proponent will develop a default actuation rate to apply to the snap-acting controllers in the project boundary. The default will be based on gathering data from all controllers to be retrofitted and should provide the most conservative result for each distinct facility included in the project boundary. For the production sector4 a basin-by-basin approach is necessary because the actuation rates are directly related to liquid production volumes and therefore tend not to vary much across a basin, but may differ significantly between different basins. For the transmission sector5 a facility by facility approach (e.g. each compressor station) is necessary because actuation rates could vary significantly between facilities depending on where in the transmission process the facility is positioned. The percentage of time the actuator is operating daily (AT) and the snap-acting controller is NOT bleeding can be expressed as:

Equation A2

ATs,j = (BPC / LC) where

ATs,j = the default actuation rate in facility j for snap-acting s controllers (%) BPC = barrels of production per controller (barrels/day or m3/day) LC = liquid capacity (barrels/day or m3/day)

4 The equipment, operations, and processes involved in the production of natural gas. This involves the

wells and processing systems before transmission. See process flow diagram at: http://www.gastool.methanetomarkets.org/m2mtool/gas.html 5 The equipment, operations, and processes involved in the transport (usually by cross-country pipelines)

of natural gas at high pressure from producing areas to consuming areas. Source: ttp://www.gastool.methanetomarkets.org/m2mtool/glossary.aspx?diagramblock=Gas%20Transmission

B-IV

Barrels of Production per Controller (BPC): The project proponent will determine the 30-day average combined (oil or water) production per day for the well sites with controllers to be retrofitted. The 30-day averages will be added together to determine the total combined average volume per day per type of snap-acting controller, across all of the controllers to be retrofitted. Any controller for which 30 days worth of production data is not available should be excluded from the calculation of the actuation rate. Liquid Capacity: The project proponent will determine the liquid capacity (LC) from the valve manufacturer using the lowest differential pressure (DP) and smallest port size to increase the conservativeness of the estimate. The lowest differential pressure (DP) will be determined across the snap-acting control valves within the population to be retrofitted. A common example of this is the pressure drop across a dump valve dumping from separator pressure down to storage tank pressure. Port size can be determined by physical inspection and should conform to manufacturers’ standard port sizes. The manufacturer of the valve should provide the liquid capacity (sometimes in a chart called the Liquid Capacity Chart) in its literature, based on port size and differential pressure. LC should be expressed in barrels per day of water flow rate. By using barrels per day of water, and NOT correcting for oil gravity, the calculations will remain conservative since water is denser than oil and will result in slightly longer actuation times. As an example, a company may have a Kimray valve located in an area where the DP is 200 psi and the port size is 1/4 inch. According to Kimray, in this case, the liquid capacity would be 650 barrels per day.

APPENDIX C: DEVICE INVENTORY

C-I

Table C1: Sample Device Inventory

High Bleed Controller (Baseline) Low-Bleed Controller (Project)

Facility Controller

I.D. #

Controller

Make/Model

Expected

Replacement

Date

Snap-Acting controllers only Controller

I.D. # Make/Model

Date of

Retrofit Port

Size

Differential

Pressure

Barrels of

Production

APPENDIX D: CONTINGENT DATA COLLECTION

D-I

Contingent means for calculating or estimating the required data for the equations outlined in section 5 are summarized in Table D1, below.

Table D1: Contingent Data Collection Procedures

1. Project / Baseline SSR 2. Parameter / Variable

3. Unit 4. Measured / Estimated

5. Method 6. Frequency 7. Justify measurement or estimation and frequency

Project SSRs

P4 Low Bleed Pneumatic Controllers

Operating Hours of Controller i /Op. Hours i

hours Estimated From historical averages of facility operation records

Monthly

Estimating operational hours from historical records is accurate where operations are consistent, when a more reasonable method cannot be used.


% volume Measured/ Estimated

Interpolation of previous and following measurements taken, or from fuel analysis of gas composition within the same basin.

Annually

Provides reasonable estimate of the parameter, when the more accurate and precise method cannot be used.




Annually


Baseline SSRs

B4 High Bleed Pneumatic Controllers

Operating Hours of Controller i /Op. Hours

hours Estimated From historical averages of facility operation records

Monthly

Estimating operational hours from historical records is accurate where operations are consistent, when a more reasonable method cannot be used.

D-II




Annual





Annual


Actuation Time/AT

% time Estimated

If it is not possible to determine the actuation time using manufacturer’s data and compiled data, the conservative estimate of 10% will be used.

N/A

Provides conservative estimate of the parameter when the more accurate and precise method cannot be used. Typically actuation time <5%.

APPENDIX E: REFERENCE CONTROLLER BLEED

RATES

E-I

The following table has been provided for validators and verifiers as a means of assessing the accuracy of bleed rate estimates. Table E1: Bleed rates of Controllers6

Controller Model Signal Pressure (psi)

Manufacturer Data (scfh)

Field Data (scfh)

Number in Field

Throttling or snap

PRESSURE CONTROLLERS

Ametek Series 40 20 6 N/A low throttling

35 6 N/A low throttling

Bristol Babcock Series 5453-Model 10F

20 3 20 - 30 low throttling


Bristol Babcock Series 5455 Model 624-III



Bristol Babcock Series 502 A/D (recording controller)

20 <6 N/A low throttling


Fisher 4100 Series (large orifice)

20 50 47 low throttling

35 50 54 low throttling

Fisher 4150 and 4160 20 10-35 11 - 35 high throttling

35 10-42 24 - 65 high throttling

Fisher 4194 (differential pressure)

20 3.5 12 - 14 moderate throttling

35 5 13-18 moderate throttling

Fisher 4195 20 3.5 13-18 moderate throttling


Foxboro 43AP 20 18 N/A moderate throttling

35 18 N/A moderate throttling

ITT Barton 338 20 6 20 - 30 moderate throttling

35 6 20 - 30 moderate throttling

ITT Barton 335P 20 6 18 - 30 low throttling


Natco CT 20 35 N/A low throttling


TRANSDUCERS

Bristol Babcock Series 9110-00A

20 0.42 N/A

35 0.42 N/A

Fisher 546 20 15 - 40 high throttling

6 CAPP Fuel Gas Best Management Practices: Efficient Use of Fuel Gas in Pneumatic Instruments (Module

3). CETAC West. May 2008.

E-II



Field Data (scfh)

Number in Field

Throttling or snap

35 30 35 - 60 high throttling

Fisher 646 20 <1 N/A

35 <1 N/A

Fisher 846 20 <1 N/A

35 <1 N/A

LEVEL CONTROLLERS

Fisher 2900 20 23 22-51 moderate throttling

Fisher 2900 (Continued)

20 23 18-127 moderate snap


35 23 27-153 moderate snap

Fisher 2500 Series 20 42 N/A moderate throttling


Fisher 2660 Series 20 1 N/A moderate

35 1 N/A moderate

Fisher 2100 Series 20 <1 N/A low

35 <1 N/A low

Fisher 2680 20 <1 N/A moderate

35 <1 N/A moderate

Invalco CT Series 20 N/A low throttling

35 40 34-88 low throttling

Norriseal 1001 20 N/A N/A moderate

35 N/A N/A moderate

Norriseal 1001 (A) 20 0.007 N/A high throttling

20 0.2 N/A high snap

35 0.007 N/A high throttling

35 0.2 N/A high snap

Wellmark 2001 20 0.007 N/A low throttling

20 0.2 N/A low snap

35 0.007 N/A low throttling

35 0.2 N/A low snap

POSITIONERS

Fisher 3582 20 14 22 high throttling

35 18 24 high throttling

Fisher 3661 20 8.8 N/A moderate throttling

35 12.1 N/A moderate throttling

Fisher 3590 (electro-pneumatic)

20 24 N/A high throttling

35 36 N/A high throttling

Fisher 3582i (electro-pneumatic)



E-III



Field Data (scfh)

Number in Field

Throttling or snap

Fisher 3620J (electro-pneumatic)



Fisher 3660 20 6 N/A moderate throttling


Fisher Fieldvue Digital 20 14 N/A moderate throttling

35 49 moderate throttling

Masoneilan 4600B Series

20 low throttling

35 18-30 low throttling

Masoneilan 4700B Series

20 low throttling

35 18-30 low throttling

Masoneilan SVI Digital

20 <1 low throttling

35 <1 low throttling

Masoneilan 7400 Series

20 24-50 N/A low throttling

Moore Products – Model 750P

20 N/A low throttling


Moore Products 73N-B PtoP


PMV D5 Digital 20 <1 N/A low throttling


Sampson 3780 Digital 20 <1 N/A low throttling


VRC Model VP700 PtoP

20 <1 N/A low

35 <1 N/A low

Bleed Rates of Controllers

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