Ignition Risks of Biomass Dust on Hot Surfaces

Combustible biomass dusts are formed at various handling stages, and accumulations of these dusts can occur on hot surfaces of electrical and mechanical devices and can pose fire risks. This study evaluates the ignition characteristics of dust from two types of biomass commonly used in the U.K. power stations: herbaceous miscanthus and woody pine. The ignition risks of the individual biomass and their blends in two different weight ratios, 90 wt % pine to 10 wt % miscanthus and 50 wt % pine to 50 wt % miscanthus, were investigated. Biomass–biomass blends represent the power plant scenario where a number of biomass are fired under daily operation, and thus, dust sedimentation could consist of material blends. The influence of washing pretreatment (particularly to remove catalytic potassium) on the ignition behavior of these dusts was investigated. Fuel characterization via proximate and ultimate analyses was performed on all fuels and combustion characteristics via thermogravimetric analysis (TGA). The risk of self-ignition propensity of both untreated and washed biomass was ranked graphically using the activation energy (Ea) for combustion and the temperature of maximum weight loss (TMWL) determined from the derivative TGA (DTG) curve. It was found that the TMWL and Ea of washed biomass were higher than those of the untreated biomass, implying a lower self-ignition risk. Similar analyses were performed on untreated and washed blends, and comparable results were observed. The ignition characteristics were studied following the British Standard test methods for determining the minimum ignition temperature of a 5 mm dust layer on a heated surface. It was found that the washed individual biomass and their blends revealed slightly higher dust ignition temperatures than their respective untreated counterparts, a 20 and 10 °C difference for individual biomass and blends, respectively. The effect of washing on the ignition delay time was more obvious for pine than for miscanthus, but the time difference between the untreated and washed biomass never exceeded 4 min for all biomass and blends. The biomass pretreatment method of washing did change the combustion and self-ignition characteristics of biomass dust, and there was evidence of potassium being leached from the fuels upon washing (particularly miscanthus). This is considered the main reason for the increase in the minimum ignition temperature. While the washed biomass is found to have a lower ignition risk, it should be noted that the result (validated for up to 5 mm thickness) is not significant enough to influence plant operations for the ignition risk from thin dust layers according to the National Fire Protection Association (NFPA) standard

Determination of the Rate of Ignition of Nitrocellulose by Resistance Wire for the Igniter of KV 150 M2

STN EN 14034 Standard defines the requirements of an igniter for the determination of the explosion characteristics of dust clouds. In order to allow the correct adjustment of the triggering of the igniter (filled with nitrocellulose) by a resistance wire, measurement of the time from the instant of triggering of a real igniter of nitrocellulose were performed by high-speed movie camera recording. This article describes the parameters and results of this igniter

Patient safety devices, security of premises and attendance management of employees for a therapeutic day care centre

International audienceThe "Soins et Santé" (Care & Health) association is non-profit medical structure. Its mission is to maintain and improve the quality of life for patients at home. The structure is divided into three services: a care centre providing home care or institutional care, a department of nursing at home for the elderly which provides care for people over 60 years dependent and / or chronically ill, and a therapeutic day care center for old people with cognitive disabilities living at home. This helps people to maintain social links, by stimulating therapeutic activities adapted to slow down the effects of the disease and also relieve the family by providing periods of respite. The therapeutic day care offers many activities such as memory, gymnastics, gardening, and multi-sensory stimulation workshops to help patients find their way into space and maintain their independence. Within the medical and social structures, directors have the duty to organize the safety of patients they serve. If damage is caused to a patient and results from carelessness or negligence of staff or access to unsuitable premises, the responsibility of the head of institution is directly engaged. To assure this surveillance, some structures make use of wireless systems. Demented patients carry with them a device (jewelry, bracelet, pendant...) that causes an alarm on detection of the patient in a non-authorized zone. However, every act of assistance that may be offered even to a cognitive impaired person has to be done with the full consent of the person. Therefore "Soins et Santé" association has chosen to implement technical solutions enabling the secure monitoring of patients through indirect control of the employees. A disposal for patient safety has been established for simultaneously securing sensitive premises (offices, treatment rooms and utensils and care products storage places) and the timetable attendance of the employees. The goal is to allow safe and non-controlled natural ambulation of the patients, respecting their integrity, and thus defending the values of respect for the human person. The use of proximity card readers now combines convenience and traceability. The project was custom made in collaboration with Legrand, the worldwide electrical building infrastructure manufacturer. With the new system, monitoring of staff and establishment of forms of activity is continuous and automatic, thus freeing the staff of a heavy workload with benefit for the patients

Using code of colors through ICT and home automation technologies in the housing environment context for persons with loss of autonomy

International audiencehe appropriation process of the environmental space parameters by elders can be done through the use of color codes that are meaningful to the persons with loss of autonomy. This approach is based upon the natural interpretation of communicating signs and signals by the brain that helps to answer more quickly to critical situation at different degrees. We illustrate first with the transposition of the color codes used in the automobile domain to the housing environment. By extension, we show that intelligent furniture can be designed through ICT and home automation to assist persons with cognitive troubles or motor disability. Finally, we describe the application done in a dare care center for persons with cognitive troubles. Colors of the rooms have been chosen to allow the patients to naturally identify the role of each room