Compressor Management

Digital control methodologies similar to the Elliott Digital System program evolved from successful and proven reliable high-speed air compressor management and control approaches. 

The current cycle of Figs. 7.42, 7.43, and 7.44 can be utilized to verify the stack-compressor interaction in higher dynamic conditions. Figure 7.47a, b reports the results obtained with a ramp of 50 A/s and the compressor management strategy N.2 (Fig. 7.40), corresponding to a constant air flow rate of 24 Nm /h,... 

The results reported above show that the compressor management strategy adopted during the dynamic operations tested clearly affects both individual cell voltage regularity (and then stack reliability) and FCS efficiency. In fact, although... 

Below the minimum throughput an equipment item such as a gas compressor will not function. The process must therefore be managed in a way which keeps production above that of the minimum throughput item. 

When combining compressors, expanders, and turbines, the speeds, thermal expansions, and thrust loads on shaft systems exist at different magnitudes and directions. These must be managed and accommodated with skill and experience. 

The explosion and fire (May 1,1990) caused eight deaths (including a vice-president and site manager), 120 injuries, extensive damage to buildings in the area, and evacuation of an entire small town. The cause of the explosion, at the Angus Chemicals Plant, was the blowout of a compressor line on the nitroparaffin unit. 

This chapter examines the need for lubrication and the types of lubricant available. Various applications are considered, including engines gears, hydraulic equipment, machine tools, metal cutting and working fluids, compressors, turbines and electrical oils. The care of lubricants on-site, application of planned lubrication and inclusion within overall maintenance management are examined. 

A small amount of nickel in the FCC feed has a significant influence on the unit operation. In a clean gas oil operation, the hydrogen yield is about 40 standard cubic feet (scf) per barrel of feed (0.07 wi /r ). This is a manageable rate that most units can handle. If the nickel level increases to 1.5 ppm, the hydrogen yield increases up to 100 scf per barrel (0.17 wt%). Note that in a 50,000 barrel/day unit, this corresponds to a mere 16 pounds per day of nickel. Unless the catalyst addition rate is increased or the nickel in the feed is passivated (see Chapter 3), the feed rate or conversion may need to be reduced. The wet gas will become lean and may limit the pumping capacity of the wet gas compressor. 

Volvo is also a partner in another European project, the Capril project, which is managed by Volkswagon. A fuel cell VW Golf was built to run on methanol. Volvo developed the compressor, power converter and energy control system. 

Recuperation. A recuperator is used to exchange heat between the turbine exhaust and compressor exit air. As in the case for the heat of compression, fuel cell AT is managed via the compressor air mass flow. In the simulations, the recuperator was not able to provide all of the heat necessary to preheat the cathode flow to the desired temperature. Methods for adding additional heat to the system are supplementary fuel added to a combustor before the fuel cell or after, or cathode recycle can also be used to make up the difference. Here, supplementary fuel was added after the fuel cell, to the post-combustion system. 

In the PCU and primary system, however, there is only one compressor to manage mass flow rate while there are several different circuits. To achieve the desired control of helium mass flow rate compressor control provides little flexibility. Rather inventory control is used to obtain a flow rate proportional to heat exchanger power. Because density is proportional to pressure for fixed temperature, by varying pressure and maintaining constant speed turbo-machinery, gas velocity remains constant and mass flow rate (proportional to the product of density and velocity) is linear with pressure. Thus, pressure is manipulated through coolant mass inventory so that it is proportional to heat exchanger power so that in turn mass flow rate is proportional to heat exchanger power. Results obtained for this control scheme are described below. 

In one reported case, a construction manager reviewed the drawings of a gas compressor building before construction. He observed that very weak clips were specified to secure the plastic sheets to the structure. He apparently did not understand the concept, because he decided they were too weak and replaced the specified clips with more robust clips. 

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