Water resources utilization and eco-environmental safety in Northwest China

Abstract

Northwest China includes Xinjiang Ugyur Autonomous Region, Qinghai Province, Gansu Province, Ningxia Hui Autonomous Region and Shaanxi Province, covering 308×10 4 km 2 . It is located in the warm-temperate zone and the climate is arid or semi-arid. Precipitation is very scarce but evaporation is extremely high. The climate is dry, the water resources are deficient, the eco-environment is fragile, and the distribution of water resources is uneven. In this region, precipitation is the only input, and evaporation is the only output in the inland rivers, and precipitation, surface water and groundwater change with each other for many times, which benefits the storage and utilization of water resources.The average precipitation in this region is 232 mm, the total precipitation amount is 7003×10 8 m 3 /a, the surface water resources are 1891×10 8 m 3 /a, the total natural groundwater resources are 1150×10 8 m 3 /a, the total available water resources are 438×10 8 m 3 /a, and the total water resources are 1996×10 8 m 3 /a and per capita water resources are 2278 m 3 /a. The water resources of the whole area are 5.94×10 4 m 3 /(a.km 2 ), being only one-fifth of the mean value in China. Now, the available water resources are 876×10 8 m 3 /a, among which groundwater is proximate 130×10 8 m 3 /a.

Effect of air bubbling on electroless Pd plating for the practical application of hydrogen selective membranes

“…The hydrogen recovery rate is affected by the ammonia feed flow rate and tends to decrease with increasing ammonia feed flow rate. 12,54,55 In this study, the ratio of feed flow rate (mL min −1 ) to membrane area (cm 2 ) (F/A ratio) was 11.4 mL cm −2 min −1 , i.e. , ∼70% of that in a previous study.…”

“…The hydrogen recovery rate is affected by the ammonia feed ow rate and tends to decrease with increasing ammonia feed ow rate. 12,54,55 In this study, the ratio of feed ow rate (mL min −1 ) to membrane area (cm 2 ) (F/A ratio) was 11.4 mL cm −2 min −1 , i.e., ∼70% of that in a previous study. 30 We achieved ∼99% ammonia conversion and 93.3% hydrogen recovery, which are higher values than those reported in a previous study.…”

Modeling-aided coupling of catalysts, conditions, membranes, and reactors for efficient hydrogen production from ammonia

“…Minimum α H 2 /NH 3 requirements to achieve H 2 purity higher than 99.9% are very similar. For most lab-scale studies reported for ammonia decomposition in a Pd-coated membrane reactor, α H 2 /NH 3 is not reported because no NH 3 is detected in the permeate side, 22,24,25,78 indicating that although there is a minimum requirement of α H 2 /NH 3 on the order of 10 3 , in most of the reported cases this value is easily achieved for common H 2 permselective materials. This is the case of the membrane studied in this work, for which pure H 2 is obtained in the permeate in all experiments.…”

Process Optimisation of In Situ H2 Generation From Ammonia Using Ni on Alumina Coated Cordierite Monoliths

“…This result suggests that the use of an intermediate step to eliminate the H 2 , or the use of a H 2 -selective membrane reactor, could be beneficial due to the reduction of the inhibition by H 2 and thus increasing the conversion per pass. The use of membrane reactors has been reported for NH 3 decomposition of diluted [33,34] or concentrated [35] ammonia streams, and it is claimed higher conversions to H 2 using membranes than without membranes.…”