TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The alcohol synthesis reactor comprises a catalyst in fluid communication with the syngas compressor and configured to take a portion of the compressed gas stream as an input and produce an effluent comprising unconverted syngas and a mixture of reaction products including alcohols and water. The purification unit: is configured to separate a portion of the effluent and first mixed-alcohol stream into a number of streams that comprise an ethanol stream having primarily ethanol, a water stream having primarily water, a methanol stream having primarily methanol, and a heavy alcohol stream having primarily propanol and heavier alcohols; and comprises a unit for mixing a methyl acetate stream with the heavy alcohol stream for creating the oil recycle stream, a methanol-ethanol/heavies separator, a propanol/water separator, a methanol/ethanol separator, a methanol/methyl acetate separator and a unit for mixing a methyl acetate stream with the heavy alcohol stream for creating the fusel oil recycle stream. The methanol-ethanol/heavies separator is configured to separate the portion of the mixed alcohol stream into (A) a methanol-ethanol stream comprising methanol and ethanol, and (B) heavies stream comprising propanol, other heavy alcohols, and water. The propane/water separator is configured to separate the heavies stream into (A) the heavy alcohol stream, and (B) the water stream. The methanol/ethanol separator is configured to separate the methanol-ethanol stream into (A) a methanol-methyl acetate stream comprising methanol and methyl acetate, and (B) the ethanol stream. The methanol/methyl acetate separator is configured to separate the methanol-methanol acetate stream into (A) the methyl acetate stream comprising methyl acetate, and (B) the methanol stream. The quench recycle loop comprises the unit for conveying the primary syngas to the waste heat recovery system, which comprises a mixing point upstream of the waste heat recovery system, the waste heat recovery system, a quench recycle unit for conveying to the mixing point a first portion of a quench recycle stream consisting of a portion of the cooled primary syngas stream or a portion of the scrubbed syngas stream, a quench recycle compressor of sufficient power to circulate syngas gas through the quench recycle loop, and the syngas scrubbers but not the mercury-lead separator. The quench recycle compressors are arranged in parallel. The valve is configured to regulate flow through the first and second portions of the quench recycle unit. The temperature sensor is configured to measure the temperature of the syngas downstream of the mixing point. The controller is configured to control the valve in response to the reading of the: temperature sensor to maintain the temperature near a predetermined temperature value of 760 degrees C; and pressure sensor to maintain the pressure near a predetermined pressure value of is less than 1 bar above atmospheric pressure. The pressure sensor is configured to measure the pressure of the syngas downstream of the mixing point. The mercury-lead separator is configured to remove mercury or lead or both mercury and lead from a mercury-lead separator inlet stream having a portion of syngas downstream of the waste heat recovery system. The quench recycle stream consists of a second portion of the scrubbed syngas. The main gas recycle loop comprises a gas recycle compressor of sufficient power to circulate gas through the main gas recycle loop, an alcohol synthesis reactor having a sulfide catalyst in fluid communication with the syngas compressor and configured to take a reactor inlet stream comprising a portion of a combined recycle gas stream as an input and produce an effluent comprising unconverted syngas and a mixture of reaction products including alcohols and water, a recycle separator configured to separate the effluent into a first mixed alcohol stream rich in water and alcohols, a gas recycle stream rich in unconverted syngas, and a unit for mixing a portion of the gas recycle stream with a portion of the compressed syngas to create the combined recycle gas stream, a heat exchanger configured to transfer heat from the effluent to a stream within the main gas recycle loop downstream of the mixing unit and upstream of the alcohol synthesis reactor, a carbon dioxide separator configured to separate carbon dioxide from the recycle loop stream at a location downstream of the mixing unit and upstream of the alcohol synthesis reactor, a combustion turbine and generator, a unit for conveying a minor portion of the gas within the main gas recycle loop to be burned in the combustion turbine, and a generator for generating electricity from the mechanical energy of the combustion turbine. The control unit is configured to control the power of the gas recycle compressor to maintain the pressure of the reactor inlet stream near a predetermined value of 95-155 bar, and ensure that the sulfiding agent is approximately at a predetermined level within the syngas entering the alcohol synthesis reactor. The continuous injection unit is located downstream of the mixing unit and upstream of the alcohol synthesis reactor for injecting a sulfiding agent. The mixed-alcohol degassing separator is operated at a lower pressure than the pressure of the recycle separator and is configured to separate the first mixed-alcohol stream into a low-pressure gas recycle stream rich in unconverted syngas and a second mixed alcohol stream rich in water and alcohols. The lower pressure is half the pressure of the pressure within the recycle separator and is less than 2 bar absolute pressure. The unit comprises a unit for decreasing the pressure of the portion of the first mixed-alcohol stream. The heat exchanger is configured to transfer heat from the first mixed-alcohol stream to a stream comprising a first portion of the water stream where the mixed-alcohol degassing separator comprises a water absorption column. The water used for absorption comprises a portion of the first portion of the water stream. The recycle separator or separators: are configured to separate the effluent into a mixed alcohol stream rich in water and alcohols; and comprises an outlet and a water absorption column, where the water used for absorption comprises a portion of the water stream. The gas recycle streams are rich in unconverted syngas. The unit for conveying a methanol recycle stream comprises a portion of the methanol stream to a mixing point upstream of or within the alcohol synthesis reactor for recycling the methanol recycle stream. The alcohol synthesis reactor comprises a first reaction zone, a second reaction zone in fluid communication with the first reaction zone, and a space between the first reaction and second reaction zones. The space comprises the mixing point. The first reaction and second reaction zones are contained within separate reactor units. The methanol recycle stream is in the gas phase. The unit within the gasification unit comprises a thermal residence chamber. The predetermined level is 25-150 ppm on a volumetric basis.