VARIABILITY IN THERMAL STRATIFICATION IN A RESERVOIR1

ABSTRACT: The thermal stratification characteristics of a flow-augmentation reservoir, Round Valley Reservoir, New Jersey, and attendant driving conditions were documented and analyzed for portions of three years. Substantial differences in the thermal stratification regime of the reservoir occurred in response to the documented changes in meteorological, operating, and light penetration conditions. The features of stratification that were affected included: the depth of the upper mixed layer, the average temperature of the epilimnion, the temperature gradient in the metalimnion, and the average temperature in the hypolimnion.     

广东省火电厂烟气脱硫装置的经济技术分析

简要介绍了广东省7个火电厂现有的5种烟气脱硫技术装置：海水脱硫、荷电干式烟气脱硫、湿式石灰石／石膏法烟气脱硫、DCL燃煤固硫剂脱硫及烟气循环流化床脱硫技术，对它们的经济、技术性进行了分析比较。     

简易石灰石/石膏湿法烟气脱硫技术在连州电厂的应用

在介绍了连州电厂的广东省第一套简易石灰石／石膏湿法烟气脱硫（FGD）系统主要设计参数和工艺流程的基础上，重点对FGD系统在近2年的运动过程中出现的主要问题进行了分析，包括系统与锅炉的相互影响，烟道腐蚀问题，脱硫石膏与灰渣水的混排及吸收塔内搅拌器叶片的损坏等，同时从技术，经济两方面对该套FGD系统进行了总体的评价。     

Natural gas engine driven heat pump system – a case study of an office building

ABSTRACT

An eQUEST model was developed to conduct a simulation study of a natural gas engine-driven heat pump (GEHP) for an office building in Woodstock, Ontario, Canada. Prior to the installation of the GEHP, the heating and cooling demands of the office building were provided by rooftop units (RTUs), comprising of natural gas heater and electric air conditioner. Energy consumption for both GEHP and RTUs were monitored for operation in alternating months. These recorded energy consumptions along with weather data were used in the regression analysis. The developed eQUEST models were validated and calibrated with the regression analysis results with respect to the ASHRAE Guideline 14–2014. The eventual models were then applied to investigate the potential annual energy consumption, greenhouse gas (GHG) emission and energy cost savings achieved by using the GEHP in Woodstock, and other cities in Canada, particularly in Ontario.     

锚索拉断火花引爆瓦斯的实验研究

设计了锚索拉断火花引爆瓦斯实验装置 ,在瓦斯浓度为爆炸范围的环境中 ,对锚索拉断时产生火花规律及引起瓦斯爆炸的可能性进行了一系列实验研究。结果表明 :锚索拉断产生火花的概率为 5 0 % ,锚索钢绞线破断产生的火花不能引起瓦斯爆炸。采用红外热成象仪对锚索拉断火花温度的测试表明 ,锚索拉断产生的火花最高温度远小于瓦斯爆炸所需的最低点燃温度 6 5 0℃。     

污泥掺烧技术在煤粉炉上应用的试验研究

通过污泥掺烧技术在煤粉炉上的应用试验,得出污泥的含水率对锅炉制粉系统的影响.掺烧前后对炉膛温度没有大的影响,随着污泥比例的增加,燃烧效率下降,烟尘浓度和SO2浓度降低.     

An application of 3D gasdynamic modeling for the prediction of overpressures in vented enclosures

A three-dimensional gasdynamic model with constant burning rate is applied for the prediction of the maximum pressure rise from gaseous combustion in vented enclosures. A series of calculations for an enclosure with aspect ratio close to unity are presented. Both cases with and without obstacles in the enclosure are considered. Results of calculations are compared with a simple 0D solution for spherical vessels. It is shown that, in cases without obstacles, the 0D solution for the maximum reduced overpressures is close to the predictions of the detailed modeling. In cases with obstacles, the detailed simulation gives significantly higher overpressures than those from the 0D model. However, in all the cases the reduced pressures are correlated well with the maximum flame surface area.     

“Vybuchovy trojuhelnik”: A software tool for evaluation of explosibility of coal mine atmosphere

Rescue operations during mine fires or methane explosions are highly dangerous for rescue workers. The knowledge of the composition of the coal mine atmosphere and the calculations of its explosibility may help to increase the safety of the rescuers. In the Czech Republic, a system called “Mine Gas Laboratory” (DPL) has been used for these purposes. The DPL allows measurement of the composition of the mine atmosphere and transmits the data necessary for evaluation to the surface. Up to now the explosibility evaluation of the coal mine atmosphere has depended either on the rescuers’ experience or on software code calculation. The code called “Vybuchovy trojuhelnik” (explosion triangle) is a graphical computing system intended for fast assessment of explosibility of fuel–air mixture. This article introduces the code and describes two simple methods of explosibility evaluation. The first method is “explosion triangle analysis”—a graphical method based on empirical graphs transformed into equations. The second method uses thermodynamic calculation based on chemical balance dynamics and Gibbs and Helmholtz energy. According to the requirements of the Czech Bureau of Mining (CBU) and Central Mine Rescue Service (HBZS), the code solves the problems of explosion triangle for both standard and non-standard coal mine atmosphere compositions. Unfortunately, the atmosphere composition must be introduced manually due to the unknown format of the data transmitted from the old DPL model. On 1 September 2005, a project started to develop a new system for on-line monitoring and atmosphere explosibility evaluation. The system should be able to measure CO₂, O₂, CH₄, H₂ and CO concentrations as well as the wind speed, temperature and humidity. The “Vybuchovy trojuhelnik” code will be used as a basis for explosibility evaluation, and an on-line connection with the new model of DPL will be established.     

An easy method to design gas/vapor relief system with rupture disk

Tank discharge gas/vapor flow problems are frequently encountered in both practice and design. To perform this type of design calculation, the first step is to identify whether the flow is choked or not through a trial-and-error solution of an equation for adiabatic flow with friction from a reservoir through a pipe. Developing a direct method without any trial-and-error to identify a choking condition would be helpful for expediting the flow calculations. This paper presents an easy and quick method to identify the choking of gas flow for an emergency relief system consisting of a rupture disk and vent piping. This greatly simplifies the design calculations. The proposed method for validating the venting adequacy of existing ERS circumvents the iteration calculation and the use of Lapple charts. Three case studies for the design of vent piping for rupture disks support the proposed method.     

Gas flame acceleration in long ducts

In many practical situations, a flame may propagate along a pipe, accelerate and perhaps transform into a devastating detonation. This phenomenology has been known, more or less qualitatively, for a long time and mitigation techniques were proposed to try and avoid this occurrence (flame arresters, vents,...). A number of parameters need to be known and in particular the “distance to detonation” and more generally the flame acceleration characteristic scales. Very often, the ratio between the detonation run-up distance and the pipe diameter is used without any strong justification other that using a non-dimensional parameter (L/D). In this paper, novel experimental evidence is presented on the basis of relatively large scale experiments using 10 cm and 25 cm inner diameter duct with a length between 7 and 40 m. Homogeneous C₂H₄-air, CH₄-air, C₃H₈-air and H₂-air mixtures were used and different ignition sources. The interpretation suggests that the self-acceleration mechanism of the flame may be much better represented by flame instabilities than by turbulence build-up. One consequence would be that the maximum flame velocity and, following, the maximum explosion overpressure, would be rather linked with the run-up distance than with the L/D ratio.