Diesel Engine Runaway The risks revealed by Test Results

Transcription

1 Diesel Engine Runaway The risks revealed by Test Results Presenter: Stephen Gale Educating industry professionals on diesel engine safety for over 17 years. Presentations Given: Texas City Safety Council ASSE (American Society of Safety Engineers) Kuwait Qatar Safety Symposium IADC (International Assoc. of Drilling Contractors)

2 O&G Operations: Risky Business 85 Fatalities associated with fire & explosions Fatalities where mobile engine was the ignition source % Falls 6% Chemical Exposure 15% Fires & Explosions 55% Struck by 7 Fatalities were due to combustion of vapors, gases, or fluids where the ignition source was diesel power equipment 2014 OSHA Fatalities in Upstream O&G

3 Typical Well Site

4 Diesel Engine Principle 1. Compression Ignition No spark plugs! 2. Fuel is metered to govern speed. 3. Methods to Shutoff Engine: Remove Fuel Supply Remove Air Supply

5 Diesel Runaway Explained Normal Running Dual Fuel Running Consumed gas A B C adds energy causing diesel fuel to reduce Gas as Fuel Running Consumed gas adds energy causing speed to increase Engine races at RPM above its red Flashback with flames through D E F line - the inlet and exhaust valves will be unable to seat effectively. manifolds Engine Explosion

6 Low event probability but very high consequences (death, site destruction) Diesel Runaway

7 Proven U.S. Diesel Engine Runaway Accidents

8 Refinery Explosion Texas City, TX March 23, Fatalities 180 Injuries Refinery Explosion A vapor cloud is ignited by an idling diesel pickup truck that witnesses reported hearing race when the vapor reached the truck

9 Waste Disposal Facility Rosharon, TX October 30, Fatalities 4 Injuries Refinery Explosion A vapor cloud is drawn into the engines of two vacuum trucks delivering waste product to the facility. They rev up and one explodes.

10 IEC & MTU Test Program Runaway is No Longer a Theory IEC & MTU validated that a diesel engine runaway can occur in a lab environment Critical speed for automatic air intake shutdown is 2070 rpm = controlled for safety by AISOVs* *AISOV = Air Intake Shut Off Valve The following data was measured 1. Gas % versus time (0 to 5.5% max) 2. Injection fuel volume rate vs time 3. Engine speed (1800rpm & up) vs time 4. Same tests - without a turbo (so 600 kw) Also recorded but not shown here: 1. Charge air pressure vs time 2. Air fuel ratio (Lambda) vs time

11 IEC & MTU Test Program Runaway is No Longer a Theory

12 Scenario #1 Full Load Delayed Runaway: Then More Rapid Explosion It begins Safe 2070 trip Gas % Diesel Injection Speed Time (seconds) 12

13 Scenario #2 Low Load (7%)/ Idle Rapid Runaway & Delayed Explosion It begins Safe 2070 trip Gas % Diesel Injection 3 Speed Time Photo of truck from explosion in Texas City

14 That seems very fast? = It is! In Comparison Usain Bolt WR 100m time is 9.58 seconds Runaway can begin within 3 9 seconds of low concentration gas being sucked in At zero or low load, these tests show runaway begins at 22% - 28% of LEL The gas detectors might alarm at 10% and request shutdown at 20% There is little margin of error if human intervention is the safety plan

15 Possible Preventive Measures Turning off Ignition Gas detectors Traffic Rules Manual valves Automatic Air Intake Shutoff valve Engine is using vapor as a fuel source Success depends on location of detector and of personnel Must be followed and enforced to be effective Create a false sense of security and hazard for operator Proven method to cut off air supply to engine, effectively stopping runaway Unsafe Proven Marginally Safe

16 Manual Air Intake Valves Not a Good Idea Attendant must be close enough to activate valve before runaway occurs

17 Automatic Air Intake Valves The Solution

18 Air Intake Shutoff Devices The Solution

19 North American Regulations & Industry Practices Alberta, Canada: Regulation Inside of 25 meters from well the following are prohibited : Diesel engines without air shutoff valves Gasoline engines Other ignition sources

20 OSHA Wyoming Workforce Services Department (053) Oil & Gas Well Drilling (0011) Chapter 6 (Facilities), Section 8 Ref. No (c) Facilities and Equipment. (ii) Emergency shut-down device(s) that will close off the combustion air shall be properly installed and identified on all diesel engines that are an integral part of the drilling rig or are operated as a stationary or mobile engine of a drilling rig within the radius of the rig anchors or within seventy five (75) feet of the well bore, whichever is greater.

21 OSHA California Petroleum Safety Orders Div 1, Chapter 4, Subchapter 14 Article 6, Section (a) In order to prevent diesel engine runaway as defined in Section 6505, no employer shall operate a stationary, vehicular or mobile diesel engine within 50 feet of the open well bore or other source of ignitable gas or vapor, unless the employer complies with subsection (b) through (f).

22 Other Regulations & Industry Practices API RP 54 Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations Emergency shut-down devices that will close off the combustion air should be installed on all diesel engines. BSEE CFR b You must equip diesel engine air intakes with a device to shut down the diesel engine in the event of a runaway.

23 In Summary 1. Diesel runaway occurs when an ungoverned fuel (vapor) enters the air intake system of an engine 2. This creates a potential ignition source which poses a serious threat to workers on oil & gas well servicing & drilling sites 3. Most reliable way to prevent runaway is by installing automatic air intake shutoff devices

24 What can we do to reduce accidents? 1. Education & training of employees 2. Perform a risk assessment of your operation 3. Inspect equipment for diesel engine overspeed systems 4. Implement an inspection & maintenance schedule of these safety systems

25 Questions? Thank you Questions are welcome Stephen Gale

26 Up Next Wednesday Break & Exhibits Open - 2:45pm to 3:15pm in the Exhibit Hall Featured Speaker - Grand Ballroom 3:15pm 4:30pm - Speaker: David Teater, President/Founder, FocusDriven LLC - Conference Closing & Recognition CEUs - Receive 1.3 CEUs (13 hours) for attending conference - Submit form at Customer Service Desk at the conclusion of the conference Survey - Please complete the survey you will receive after the conference