Standard test procedure to characterise different filter media under energy consideration

Abstract

In the context of increasing energy prices and the imperative of reducing CO 2 emissions, the energy consumption also related to dust separators has become the focus of attention. Further, new stricter regulations for the particle concentration in the environmental air (PM10 PM2.5) require the improvement of existing dust separators. The improvement of the separation efficiency of dust separators is always associated with a higher energy input, in case of a filtering device with an increase of the pressure drop and other energy inputs during the filtration procedure. Especially for air depth-filters, used for applications with low dust concentrations (e.g. ventilation of living and working spaces), a new guideline "EUROVENT 4/11" [1] for energy efficient operation has already been developed. With this method a classification of different filter media concerning their energy consumption and their separation efficiency in relation to each other can be done.For applications with high dust concentrations (e.g. waste gas cleaning of combustion or cement plants), where so called cleanable dust filter media are in use, a classification of different cleanable dust filter media can be done by the standards ISO11057:2011 [2] and VDI 3926 [3]. But these standards make no statement to their relative energy consumption. In this work an approach was made to classify different filter media concerning their relative energy consumption in connection with their separation efficiency.With a special test rig, which are also used in ISO11057:2011 [2], a total energy consumption value [Wh/m³] related to the air volume throughput and the corresponding separation efficiency was evaluated over 30 filtration cycles. This energy value comprises all relevant energy consumption parts (fan energy and cleaning energy) by a single value. Determining this value and also the associated separation efficiency for each filter medium, different filter media can be classified concerning their quality.

Operating Behavior of Pulse Jet‐Cleaned Filters Regarding Energy Demand and Particle Emissions – Part 1: Experimental Parameter Study

“…Höflinger et al proposed a method to evaluate filter media based on energy criteria in a filter test rig based on DIN ISO 11057 38. They took into account the differential pressure across the filter medium as well as the consumption of pressurized air from the jet pulse by applying the following equation in order to calculate the total power consumption of filter operation P Filter (equation modified from 10, 20): …”

“…The biggest contributors regarding power consumption of filter operation are the consumption of pressurized air P reg for filter regeneration and the fan power P fan caused by the differential pressure due to the flow through the filter medium and the filter cake 10, 20, 21. Both of these contributions are dependent on each other.…”

“…The operation of filters often follows a strict framework (e.g., Δ p ‐ or Δ t ‐controlled criterion for filter regeneration) 9 and a re‐evaluation of filter operation regarding energy aspects has the potential to improve process efficiency in the future 10. While the research foundations for pulse jet‐cleaned filters have been laid in the past by, e.g., Löffler 11 or Leith and Ellenbecker 12, present filter operation under demanding conditions still poses its individual challenges 13.…”

Operating Behavior of Pulse Jet‐Cleaned Filters Regarding Energy Demand and Particle Emissions – Part 2: Modeling

“…Longer time intervals between regenerations enable lower average dust emissions at the trade‐off of larger differential pressures. Shorter time durations can lower the differential pressure level, where a higher consumption of pressurized air and increased emissions have to be taken into account 2, 9.…”

“…In part 1 of this study, experiments were performed in a small‐scale baghouse filter with nine filter bags in order to identify feasible operation points regarding the power requirement for filter operation and the corresponding dust emissions 2. The total power for filter operation was determined as the sum of the fan power and the compression energy for the consumption of pressurized air, according to equations shown by Höflinger and Laminger 9. The optimal cycle times in order to operate at the power minimum were identified for various parameters (filter face velocity, raw‐gas concentration, tank pressure).…”