Design and Analysis of a High Temperature Particulate Hoist for Proposed Particle Heating Concentrator Solar Power Systems

Abstract

The central receiver power tower (CRPT) with a particle heating receiver (PHR) is a form of concentrating solar power (CSP) system with strong potential to achieve high efficiency at low cost and to readily incorporate cost-effective thermal energy storage (TES). In such a system, particulates are released into the PHR, and are heated to high temperature by concentrated solar radiation from the associated heliostat field. After being heated, the particles will then typically flow into the hot bin of the TES. Particulates accumulated in the hot bin can flow through a heat exchanger to energize a power generation system or be held in the hot TES storage bin for later use such as meeting a late afternoon peak demand or even overnight generation. Particles leaving the heat exchanger are held in the low temperature bin of the TES. A critical component in such a PHR system is the particle lift system, which must transport the particulate from the lower temperature TES bin back to the PHR. In our baseline 60 MW-thermal (MW-th) design, the particulate must be lifted around 70 m at the rate of 128 kg/s. For the eventual commercial scale system of a 460 MW-th design the particulate must be lifted around 138 m at the rate of 978 kg/s. The obvious demands on this subsystem require the selection and specification of a highly efficient, economical, and reliable lift design. After an apparently exhaustive search of feasible alternatives, the skip hoist was selected as the most suitable general design concept. While other designs have not been dismissed, our currently preferred somewhat more specific preliminary design employs a Kimberly Skip (KS) in a two-skip counterbalanced configuration. This design appears to be feasible to fabricate and integrate with existing technology at an acceptably low cost per MW-th and to promise high overall energy use efficiency, long service life, and low maintenance cost. A cost and performance model has been developed to allow optimization of our design and the results of that study are also presented. Our developed design meets the relevant criteria to promote cost effective CSP electricity production.

Concentrating Solar Power Gen3 Demonstration Roadmap

“…Conventional industrial and mining applications of skip hoists straddle the proposed lift height, but have more than sufficient lift capacity [86]. The proposed temperatures, 300°C-550°C for a subscale prototype suitable for a 10-MW e plant and perhaps over 600°C for a commercial-scale plant go beyond current capabilities.…”

“…Because the particles are lifted by friction between the particles and the rotating casing, the lift efficiency (defined as the potential energy gained divided by the electrical energy required) is low (~5%). For larger-scale systems, an insulated skip-hoist system was designed that can achieve ~80% lift efficiency with a parasitic power consumption less than 1% of the rated electrical output of the CSP plant [86].…”

“…Repole and Jeter [86] recommend a Kimberly Skip with a Double Drum hoist ( Figure 25). The Kimberly Skip is top loading and dumping, which is selected for simplicity and limiting particle loss.…”

Solar tower system temperature range optimization for reduced LCOE

“…Vertical Particle Transport A mine hoist system is foreseen for the vertical particle transport. Repole et al [11] have made a conceptual design for a hoist for a solar demonstration system with a thermal capacity of 60MWth. Since the selected solar tower module size is close to this capacity, this mine hoist design was taken as base value for the calculation of the cost for the specific configuration.…”

“…Scaling factors are applied for conditions differing from the original design values. The used correlation is (after currency conversion from $ to €): (11) The scaling factors are selected as kT = 0.1, km = 0.5 and kH = 0.2.…”