Strength and Service Life of a Steam Turbine Stop and Control Valve Body

The stability of operation of steam turbines depends (along with other factors) on the reliable operation of their steam distribution systems, which are based on stop and control valves. This paper considers the strength of the elements of the K-325-23.5 steam turbine valves, in whose bodies, after 30 thousand hours of operation, cracks came to be observed. Previously determined were the nature of gas-dynamic processes in the flow paths of the valves and the temperature state of the valve body in the main stationary modes of operation. To do this, a combined problem of steam flow and thermal conductivity in stop and control valves was solved in a three-dimensional formulation by the finite element method. Different positions of the valve elements were considered taking into account the filter sieve. The assessment of the thermal stress state of the valve body showed that the maximum stresses in different operating modes do not exceed the yield strength. Therefore, the assessment of the creep of the valve body material is important to determine the valve body damage and service life. Modeling the creep of the stop and control valves of the turbine was performed on the basis of three-dimensional models, using the theory of hardening, with the components of unstable and steady creep strains taken into account. The creep was determined at the maximum power of the turbine for all the stationary operating modes. The maximum calculated values of creep strains are concentrated in the valve body branch pipes before the control valves and in the steam inlet chamber, where in practice fatigue defects are observed. However, even for 300 thousand hours of operation of the turbine (with a conditional maximum power) in stationary modes, creep strains do not exceed admissible values. The damage and service life of the valve bodies were assessed by two methods developed at A. Pidhornyi Institute of Mechanical Engineering Problems of the NAS of Ukraine (2011), and I. Polzunov Scientific and Design Association on Research and Design of Power Equipment. (NPO CKTI) – 1986. The results of assessing the damage and the turbine valve body wear from the effects of cyclic loading and creep of the turbine in stationary modes for 40, 200 and 300 thousand hours show that the thermal conditions of the body in the steam inlet chamber are not violated (without taking into account possible body defects after manufacture). The damage in valve body branch pipes after 300 thousand hours of operation exceeds the admissible value, with account taken of the safety margin. At the same time, the damage from creep in stationary operating modes is about 70% of the total damage. The maximum values of damage are observed in the areas of the body where there are defects during the operation of the turbine steam distribution system. The difference between the results of both methods in relation to their average value is ~20%.

Tackling the Methane Quandary: Curbing Emissions from Control Valves

In the wake of Eni's strategy to curb fugitive emissions - in particular methane – an innovative control valve (Clarke Shutter Valve) has been deployed and tested in an Italian Eni facility. This shutter type valve is capable of reducing the fugitive emissions by more than 90%, as well as greatly curbing purchase costs, thanks to an innovative design in bonnet and regulating mechanism. In order to assess the real potentiality of the innovation, four Fisher globe valves and one Fisher V-ball were substituted with the Shutter Valves on different hydrocarbon streams of the Trecate facility (Piedmont), in particular on streams containing oil, gas and corrosive fluids. The valves were monitored for more than a year and fugitive emissions tests have been performed to detect and estimate methane leak rates. Since this represented a first deployment of this technology in Europe, a thorough analysis and technology validation of the valves has been performed. A successful installation and start-up were performed in 3 days by Eni's staff at in February of 2020. The valves were fully operational after the installation and to date no issues have been reported. In order to monitor the valves performances of flow control, continuous data collection on each valve has been implemented, and the analysis performed showed that all valves behave correctly as to Eni's standards. A fugitive emission test that has been performed at the end of 2020 with a certified portable FID/PID analyzer displayed that no methane emissions were detected from the valves. Lastly the one year and half long technology validation concluded that the Shutter Valves are a valid technology for curbing methane emissions from the Oil and Gas plants, and that suggested to qualify the company as Eni partner for control valves. This deployment and field tests, as well as the technological assessment performed by Eni's professionals showed the potentiality of this new type of valves in reducing the methane emissions from the petroleum industry. Understanding the potentiality of intrinsically carbon neutral technology is a crucial step for the mitigation of greenhouse gases emissions and towards the creation of a more environmentally friendly industry.

A Review of Capillary Pressure Control Valves in Microfluidics

Microfluidics offer microenvironments for reagent delivery, handling, mixing, reaction, and detection, but often demand the affiliated equipment for liquid control for these functions. As a helpful tool, the capillary pressure control valve (CPCV) has become popular to avoid using affiliated equipment. Liquid can be handled in a controlled manner by using the bubble pressure effects. In this paper, we analyze and categorize the CPCVs via three determining parameters: surface tension, contact angle, and microchannel shape. Finally, a few application scenarios and impacts of CPCV are listed, which includes how CPVC simplify automation of microfluidic networks, work with other driving modes; make extensive use of microfluidics by open channel, and sampling and delivery with controlled manners. The authors hope this review will help the development and use of the CPCV in microfluidic fields in both research and industry.

Innovative Method to Optimize Down Hole Control Valves by Well Modeling

The revolution of smart well completions has been significantly enhancing the oil & gas industry in the recent years, The completions allow for higher PIs, better sweep, longer well life, longer reservoir contact and better water management. These effects came into play and needed once O&G industry moved to drilling multi-lateral wells. This paper represents a tri-lateral well that was drilled with high reservoir contact. The production optimization was completed to evaluate the contribution of each lateral and decide on the future production strategy for the well. This evaluation also allowed to test the functionality of the Down Hole Flow Control Valves (DHFCVs). Further, determining this functionality allowed identifying cross flow between the ICVs and the laterals. The optimization included multi-stage testing of each lateral to ascertain the high oil & water contributors. The water contribution was recorded across each lateral to optimize the water production and enhance the well productivity. The productivity index was calculated using IPR modeling utilizing Pipe-Sim software based on the commingled multi-rate tests. To further plan the way forward on the well production, a flowchart was established during the optimization operation to guide through the optimization process, identify each lateral water contribution, and production strategy after the operation. This optimization has resulted in a significant cost avoidance, avoiding coil tubing horizontal logging intervention operations in all the three laterals. The details of the testing stages scenarios and the recommendations of the production strategies will be shared in this paper.

Well Cleanup Utilizing Smart Well Completion and Zero Flaring Technology

In an oil field, openhole multilateral maximum reservoir contact (MRC) wells are drilled. These wells are typically equipped with smart well completion technologies consisting of inflow control valves and permanent downhole monitoring systems. Conventional flowback techniques consisted of flowing back the well to atmosphere while burning the hydrocarbon and drilling fluids brought to surface. In an age of economic, environmental and safety consciousness, all practices in the petroleum industry are being examined closely. As such, the conventional method of flowing back wells is frowned upon from all aspects. This gives rise to the challenge of flowing back wells in an economic manner without compromising safety and the environment; all the while ensuring excellent well deliverability. By utilizing subsurface smart well completion inflow control valves, individual laterals are flowed to a separator system whereby solid drill cuttings are captured and discharged using a solids management system. Hydrocarbons are separated using a separation vessel and measured before being sent to the production line toward the field separation facility. Permanent downhole monitoring systems are used to monitor pressure drawdown and subsequently control the rate of flow to surface to ensure reservoir integrity. Following the completion of the solids and drilling fluid flowback from the wellbore, comprehensive multi-rate measurements at different choke settings are obtained to quantify the well performance. This paper looks at the economic and environmental improvements of the adopted zero flaring cleanup technology and smart well completions flowback techniques in comparison to conventional flowback methods. This ensures that oil is being recovered during well flowback and lateral contribution to overall flow in multilateral wells. In addition, it highlights the lessons learned and key best practices implemented during the cleanup operation to complete the job in a safe and efficient manner. This technique tends to set a roadmap for a better well flowback that fulfills economic constrains and protects the environment.