Discharge hydrocarbon

What happens if water in the drum starts to go over with the hydrocarbon vapors into the plant vapor recovery system Add two motor operated valves to the overhead system and a water detector sensor. When the drum starts to fill, the detector will sense water vapor trying to go overhead with the hydrocarbon vapors. It will close the hydrocarbon overhead line to vapor recovery and open the other motor operated valve discharging hydrocarbon vapors and water to a blowdown drum. 

ILLUSTRATIVE EXAMPLE 21.1 In order to meet recently updated environmental regulations for discharging hydrocarbons to the atmosphere, a gas stream must be reduced by 99.5% of its present hydrocarbon concentration. Due to economic considerations, it is proposed to meet the above requirement by combusting the hydrocarbons in an incinerator operating at 1500°F. The gas and methane (fuel) are to be fed to the incinerator at 80°F and 1 atm. Design the proposed incinerator using kinetic principles. 

Secunda discharges no process water effluents. AU. water streams produced are cleaned and reused in the plant. The methane and light hydrocarbons in the product are reformed with steam to generate synthesis gas for recycle (14). Even at this large scale, the cost of producing fuels and chemicals by the Fischer-Tropsch process is dominated by the cost of synthesis gas production. Sasol has estimated that gas production accounts for 58% of total production costs (39). 

Electric Discharge Processes. The synthetic mbber plant built by the 1. G. Farbenindustrie during World War 11 at Hbls, contained the first successful commercial instaUation for the electric arc cracking of lower hydrocarbons to acetylene. The plant, with a capacity of 200 t/d, was put into operation in August 1940. 

The electric discharge processes can supply the necessary energy very rapidly and convert more of the hydrocarbons to acetylene than in regenerative or partial combustion processes. The electric arc provides energy at a very high flux density so that the reaction time can be kept to a minimum (see... 

The carbon black (soot) produced in the partial combustion and electrical discharge processes is of rather small particle si2e and contains substantial amounts of higher (mostly aromatic) hydrocarbons which may render it hydrophobic, sticky, and difficult to remove by filtration. Electrostatic units, combined with water scmbbers, moving coke beds, and bag filters, are used for the removal of soot. The recovery is illustrated by the BASF separation and purification system (23). The bulk of the carbon in the reactor effluent is removed by a water scmbber (quencher). Residual carbon clean-up is by electrostatic filtering in the case of methane feedstock, and by coke particles if the feed is naphtha. Carbon in the quench water is concentrated by flotation, then burned. 

Some vent streams, such as light hydrocarbons, can be discharged directly to the atmosphere even though they are flammable and explosive. This can be done because the high-velocity discharge entrains sufficient air to lower the hydrocarbon concentration below the lower explosive limit (API RP 521, 1997). Toxic vapors must be sent to a flare or scrubber to render them harmless. Multiphase streams, such as those discharged as a result of a runaway reaction, for example, must first be routed to separation or containment equipment before final discharge to a flare or scrubber. 

At the central platform, water and hydrocarbon liquids are first removed in knockout drums. Then saturated natural gas, free of any liquid droplets, enters the twin expanders. The gas is cooled below its dewpoint, allowing heavy hydrocarbon components and water vapor to condense in the discharge stream. Turboexpanders were chosen for two main reasons They are more compact than competing methods of controlling the dewpoint and their operating costs are typically lower than those of many alternatives. 

Coke oven discharging (pushing) Hydrocarbons, coke dust Hoods to fans and venturi scrubbers, low-energy scrubbers followed by ESPs (may use water spray at oven outlet)... 

When one takes a sample at the rate of 0.3 liter min from a stack discharging 2000 m min to the atmosphere, the chances for error become quite large. If the sample is truly representative, it is said to be both accurate and unbiased. If it is not representative, it may be biased because of some consistent phenomenon (some of the hydrocarbons condense in the tubing ahead of the trap) or in error because of some uncontrolled variation (only 1.23 gm of sample was collected, and the analytical technique is accurate to 0.5 gm) (1). 

A compressor surges at certain conditions of low flow, and the compressor map, a plot of head versus flow, has a surge line defining the limits. Surge controls help the machine avoid surge by increasing flow. For an air compressor, a simple spill to the atmosphere is sufficient. For a hydrocarbon compressor, recirculation from discharge to suction is used. 

The gaseous component typically contains hydrocarbons, hydrogen sulfide, ammonia, mercaptans, solvents, and other constituents, and is either discharged directly to the atmosphere or is combusted in a flare. The major air emissions from blowdown systems are hydrocarbons in the case of direct discharge to the atmosphere and sulfur oxides when flared. 

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