Cooling water Venting

Vented risers should be provided on most cooling towers to release only light hydrocarbon leakage from the cooling water before the spray header. No ignition or source of spark should be within 30 m of the vented riser. 

Most refinery process units and equipment are manifolded into a collection unit, called the blowdown system. Blowdown systems provide for the safe handling and disposal of liquids and gases that are either automatically vented from the process units through pressure relief valves, or that are manually drawn from units. Recirculated process streams and cooling water streams are often manually purged to prevent the continued buildup of contaminants in the stream. Part or all of the contents of equipment can also be purged to the blowdown system prior to shutdown before normal or emergency shutdowns. 

NOTE The datasheet allows selection of this option for vent, cooling water and drain connections. 

Quite clearly, this discussion will raise many points for the designers to consider. Similarly, each of the other hazard prompts can be addressed. They will undoubtedly raise questions about the design of the venting system (toxic and flammable emissions), how to deal with a failure of the cooling water supply to the condenser, how to control and monitor the effluent discharge even under conditions of plant malfunction, instrument failure, loss of other services such as electrical supply and steam, human error, ease of safe maintenance and so on. The prompt internal fire may lead to a debate on the start-up of the system, when acetone vapour and air will be present initially. 

The available energy flou through five major sections of sulphuric acid plant is given in figure 2. The major inputs to this system are sulphur and pouer, with demineralised (DM) water uet air, process water and cooling water from environment. The useful outputs from the system are sulphuric acid and steam. Losses to environment include heat losses from various equipments blowdown water steam from deaerator vent warm water and stack gas. 

Controls Cooling-water rare controlled by vapor temperature in vent line ... 

Step 2. There are 26 control degrees of freedom in this process. They include three feed valves for oxygen, ethylene, and acetic acid vaporizer and heater steam valves reactor steam drum liquid makeup and exit vapor valves vaporizer overhead valve two coolers and absorber cooling water valves separator base and overhead valves absorber overhead, base, wash acid, and liquid recirculation valves gas valve to CO removal system gas purge valve distillation column steam and cooling water valves column base, reflux, and vent valves and decanter organic and aqueous product valves. 

The autoclave was pressurized with hydrogen (400 kPa) and heated to 250 C for 16 h before cooling and venting. The clay was collected by centrifugation and washed repeatedly with water to remove ionic impurities. 

Make specific allowances for distribution systems within the process area for the various utilities cooling water, high/low pressure steam/condensate, service water/air, nitrogen, instrument air, vent collection systems, etc. Lengths and sizes must be determined based on arrangement and flows. Allow at least 30 ft. of pipe from distribution system to each individual user. 

The Eederal Clean Air Act requires the U.S. Environmental Protection Agency to establish hazardous air pollutant emission criteria per unit of production. These standards have been promulgated and range from 0.2 to 0.25 kg for 100 kg of oilseeds processed, for specihc categories of extraction and oilseed type. Attainment of this hgure requires a properly designed vent and cooling water system with minimal intermptions to the operations. 

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