Outside the battery limits

For the same production capacity, the oxygen-based process requires fewer reactors, all of which operate in parallel and are exposed to reaction gas of the same composition. However, the use of purge reactors in series for an air-based process in conjunction with the associated energy recovery system increases the overall complexity of the unit. Given the same degree of automation, the operation of an oxygen-based unit is simpler and easier if the air-separation plant is outside the battery limits of the ethylene oxide process (97). 

The above factors apply to those items normally classified as building services. They do not include (1) services located outside the building such as substations, outside sewers, and outside water lines, all of which are considered to be outside the battery limit as well as outside the building and (2) process services. 

For fire protection purposes, drainage systems that may contain flammable vapors should be sealed and vented both inside the battery limit and outside the battery limit. In the absence of these provisions, flammable or toxic vapors and gases may migrate into an area well away from where the release occurred, thus spreading the hazard. 

Outside battery limit (OSBL) defines the work and responsibilities outside the battery limit. The OSBL includes auxiliaries required for the chemical process unit, including tank storage for feedstock and refined products, waste treatment, cooling towers, flares, and utilities that are not included in the battery limit but are required for the unit. Also included are the pipeways, racks, and sleepers, which are used to convey all of the utility s interconnecting process piping to and from the processing facility... 

The capital cost required for the provision of utilities and other plant services will depend on whether a new (green field) site is being developed, or if the plant is to be built on an existing site and will make use of some of the existing facilities. The term battery limits is used to define a contractor s responsibility. The main processing plant, within the battery limits, would normally be built by one contractor. The utilities and other ancillary equipment would often be the responsibility of other contractors and would be said to be outside the battery limits. They are often also referred to as off-sites . 

What-if there is an impact from outside the battery limits ... 

Figure 6.3 Evaluation of economic sustainability. OSBL, Outside the battery limits WC, working NPV, net present value FCI, fixed capital investment DPBP, discounted payback period DCFROR, discounted cash flow rate of return.

If utilities are generated inside the facility, such as cooling water, the capital cost for outside the battery limits facilities are evaluated by APEA. Using the specified indirect cost, discount rate, tax, and interest, the discounted cash flow and the economic indicators are generated by APEA with the method described in Section Economic Sustainability Analysis. Parameters for economic evaluations and prices of the raw materials and products are shown in Table 6.8. Utility costs for electricity, steam, and... 

UEL, upper explosive limit LEL, lower explosive limit TLtJ threshold limit value ISBL, inside the battery limits OSBL, outside the battery limits. 

Multielevation piperacks are usually needed to handle all the required services for piping, electrical, utilities, and instmmentation. The two-level rack is one of the most common but three-level ones are also used. The utility lines are usually mn in the upper level and the process lines in the lower levels. The larger-diameter lines are located to the outside of the rack to be closest to the column supports. Access platforms are required at the battery limit to provide operators access to the block valves and blinds. If long mns of hot pipe are required, a portion of the pipe rack needs to be dedicated to an expansion loop. A horizontal space in the piperack is provided for a set of lines to be flat-turned into a set of expansion loops with the large pipes located on the outside. AH of the pipe turns are in the same horizontal plane, which is an exception to normal piping practice. A flat turn takes up and blocks space for other pipes. Flat turns are generally only made from the outside of the rack to minimize this blockage. 

In addition to the investment within the battery limits, investment is also required for the structures, equipment and services outside of the battery limits that are required to make the process function. 

Isolation valves may be located near the property line, the edge of a process unit, or the liquid outlet of a vessel. Valves should be installed on all hazardous materials lines entering or leaving the facility to ensure the facility can be isolated in the event of a spill or fire. Similarly, valves should be located at or near the battery-limit of each unit or outside dike walls for the same reasons and for safety and ease of access. 

The common mistake observed is the capital cost estimate for a retrofit project being too low compared with reality. The main reason is that it does not include installation and the outside system battery limit (OSBL) cost, which could be as expensive as the inside system battery limit (ISBL) cost. This topic is discussed in Section 22.6. 

Figure 2.30 is nearly silent on a significant requirement — the need to treat the substantially greater volume of exhaust air which is presumably saturated with solvent vapors (note the top of Figure 2.30). The near silence is because this requirement must be met, but is done so outside of the battery limits of the enclosed vapor degreaser. 

The cells can be operated with success at elevated temperatures. When operated at very high currents outside the recommended limits, the cells may produce heat and high internal gas pressures and these conditions should be avoided. The cells are, however, an excellent source for high pulse currents. Multi-cell batteries contain additional insulation as well as a fuse for protection from mishandling such as short-circuits. 

Capital investment costs can be divided into two categories (1) costs that are independent of the location (Inside Battery Limits, ISBL), and (2) costs that are dependent on the location (Outside Battery Limits, OSBL). 

For the Equipment Safety Subindex the process plant area is divided into two different areas, which have different safety properties. The onsite area is the area where the raw materials are converted into the products. This is referred as the inside battery limits area (ISBL). This area is characterized by large number of equipment and piping located in a concentrated way in a small area. The rest of the plant is referred as the offsite or outside battery limits area (OSBL). The offsite area is characterized by large inventories of fluids, which are often flammable and/or toxic. The number of equipment in OSBL area is smaller but their size larger than in the ISBL area. The layout is much more scattered in OSBL than in ISBL which is to enhance safety. 

Because of the wide availability of chlor-alkali technology, it was decided to tender for fixed-price contracts for engineering, procurement and construction of the two chlor-alkali plants. The other areas - namely Outside Battery Limits for both plants and the chlor-paraffin plant in Melbourne - were managed by Orica under separate contracts. The chlor-paraffin plant process design (batch chlorination of paraffin oil and wax) was carried out in-house by Orica. 

Subsequent to awarding the contract for the two chlor-alkali plants to Kvaerner Chemetics, Orica contracted with Kvaerner Process Australia to provide services for the chlor-paraffin plant and Outside Battery Limits activities associated with the new Melbourne site, as this would bring synergies to the total project as well as potential cost savings. 

This is a multiplier , which when applied to the purchase prices of major pieces of chemical process equipment, provides an estimate of the installed cost of the chemical process. b ISBL, inside battery limit. c OSBL, outside battery limit. 

Manholes outside of process area battery limits should be vented at least 12 ft (3.7 m) above grade 2 in (5 cm) diameter vent pipes are normally adequate. The vent pipes should be located well away from roads and ignition sources and pointed straight up to disperse vapor. 

Storage tanks are regarded as outside the process battery limits, on tank farms. Their sizes am measured in units of the capacities of connecting transportation equipment 34.500 gal tank cars, 8000gal tank trucks, etc., usually at least 1.5 times these sizes. Time variations in the supply of raw materials and the demand for the products influence the sizes and numbers of storage tanks. 

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