Zero-pollution wastes disposal and energy generation

Abstract

A zero-pollution wastes disposal and clean-energy generation system is improved by introducing to it a catalyst to lower down the gasification temperature and to prolong the life of the gasification reactor, a simultaneous direct and indirect heat transfer to supply the heat required for carbon-steam reaction and a means for extracting clean water from raw sewage sludge to supply the steam required by carbon-steam reaction. These improvements increase the efficiency and economy of the system and promote the smoothness of its operation.

I claim:  
     
         1 . A method for improving the economy, efficiency and promoting a smoother operation of the system of zero-pollution wastes disposal and clean energy generation by introducing a catalyst into the integrated process of gasification of coal municipal solid wastes and sewage sludge. 
 (a) The said catalyst mentioned in    claim 1    consists of salts of two metals to lower the optimal temperature of the carbon-steam reaction by about 100° C. and to prolong the life of the reactor.    (b) The catalyst defined in    claim 1   (a) consists of two parts. 
 The first part I is selected from one of the salts of chlorides, sulphates, carbonates of sodium or potassium:  
 Part II is taken from one of salts of the chlorides, sulfates, or carbonates of iron or chromium.  
   (c) In the said catalyst defined in    claim 1   (a) and  1 (b), the atomic ratio of metal I (sodium or potassium) to metal II (iron or chromium) lies between 1:50 to 50:1.    (d) The quantity of the said catalyst defined in claims  1 (a) to  1 (c) recycling in the system between the gasifier and preheater-combustor, back and forth, is between 0.05 to 5% of the total weight of feed to the gasifier.    (e) The said catalyst defined in claims  1 (a) to  1 (c) is depleted continuously in the system by various losses. The depletion is made up continuously or intermittently by adding fresh catalyst into the gasifier. Alternative, it is added into the system through the pyrolyzer. In the latter case, the quality of the pyrolyzed gas is improved.    
     
     
         2 . A method of improving the system of zero-pollution wastes disposal and clean energy generation by supplying the heat required by carbon-steam reaction in the gasifier through using both the direct and indirect heat transfer simultaneously. 
 (a) The said indirect method of supplying heat in    claim 2    consists of burning a fuel gas outside the walls of the gasifer in a kiln or a furnace designed for this purpose. The said direct method of heat transfer defined in    claim 2    is to utilize the heat from the reaction between carbon dioxide and the calcined lime in the gasifier.    (b) In the simultaneous heat transfer as defined in    claim 2   , the amount of heat transferred by direct means to that by indirect transfer through the walls of the gasifier varies from 1:4 to 4:1.    
     
     
         3 . A method of improving the economy, efficiency and promoting a smoother operation of the system of zero-pllution wastes disposal and clean energy generation by extracting clean steam from raw sewage sludge to support carbon-steam reaction, which comprises of: 
 (a) passing the raw sludge into a series of steam jacketed screw-conveyor type sludge-solid-content removers. The separation of the solids and water components of the sludge is carried out under the combined influence of mechanical shears, electrolytes and heating.    (b) Removing the remaining solid contents of the water coming out of sludge-solids-removers further by a filter.    (c) Feeding the water passing through the filter and one or series of ion-exchanger to a boiler to generate clean steam which is utilized for supporting carbon-steam reaction.