| Abstract |
The problem of increasing effectiveness of high temperature hydrothermal fluid usage is considered. It is shown that it is possible to achieve considerable increase of usage effectiveness at the temperature in reservoir of 250-300 C at the expense of the control for the speed of growth of solid deposits of silica in wells, pipelines and thermal equipment of geothermal power plants and geothermal heat plants. Growth of solid deposits is going on due to mass transfer in water flow of colloidal particles of silica. Colloidal silica is formed in oversaturated hydrothermal solution while rising up to the surface in productive wells because of the decrease of pressure, temperature and partial evaporation. Growth of solid deposits leads to the necessity of reinjection of spent separate at increased temperature of 140-160 C which restricts production of electric energy and heat. Modern methods of control for the speed of growth of silica deposits are analyzed. The methods are divided into two types: 1. extracting silica from separate solution; 2. inhibition of deposits growth not extracting silica. The results of the experiments on investigation of polymerization processes of silicic acid with forming of silica colloidal particles and of experiments on coagulation and concretion of colloidal silica from the separate of Upper-Mutnovsky GeoPP. The experiments on concretion of silica are carried out adding coagulants of various types. The estimate of coagulants processing cost, that is necessary to choose optimal modes of concretion, is made. The following economic principles of increasing hydrothermal fluid usage effectiveness due to silica concretion are grounded on the basis of implemented experiments: 1. elimination of the expenses for drilling reinjection wells in case of their filling with solid deposits; 2. decrease of separate reinjection temperature and getting of additional electric power in binary units with low-boiling working fluid; 3. getting of mineral raw materials in the form of amorphous silica that is used in chemical and silicate industry; 4. extraction of valuable chemical compounds (lithium, boron, arsenic etc.). |