Heat reclaim

Refrigeration Control Valves for Heat Reclaim, Heating/ Piping/Air Conditioning, p. 81, March (1979). 

Refrigerant condenser coils of heat pump or heat reclaim systems Figure 24.1 shows the sensible heating of air. 

The heat reclaim packaged unit system comprises water-cooled room units with reverse cycle valves in the refrigeration circuits. The water circuit is maintained at 21-26°C, and may be used as a heat source or sink, depending on whether the individual unit is heating or cooling. (See Figure 28.11.)... 

Figure 28.11 Heat reclaim system, (a) Unit cooling.

FIG. H-8 Heat reclaim optlons/opportunities. (Source Enertran.)... 

In the Reclaimator, a high pressure extmder, fiber-free mbber is heated to 175—205°C with oils and other ingredients. High pressure and shear between the mbber mixture and the extmder barrel walls effectively devulcanize the mixture in one to three minutes. In the Lancaster-Banbury method, high temperature, pressure, and shear are appHed to the mbber in a batch process that is otherwise similar to the Reclaimator process. In another high pressure process, scrap mbber is devulcanized at 5.5—6.9 MPa (54—68 atm) for ca five minutes. The product is milled, baled, or pelletized as in other processes. 

Tire disposal costs are 0.10—3.00 per tire. Cost for incineration without heat recovery is 0.35—0.70 per tire. Transportation of discarded tires can cost 0.04/kg, and size reduction can cost 0.20—0.60/kg. Distribution of passenger car tires is landfill, 85% retreaded, 10% and reclaimed, burned for fuel, and spht, 5%. 

Other components in the feed gas may react with and degrade the amine solution. Many of these latter reactions can be reversed by appHcation of heat, as in a reclaimer. Some reaction products cannot be reclaimed, however. Thus to keep the concentration of these materials at an acceptable level, the solution must be purged and fresh amine added periodically. The principal sources of degradation products are the reactions with carbon dioxide, carbonyl sulfide, and carbon disulfide. In refineries, sour gas streams from vacuum distillation or from fluidized catalytic cracking (FCC) units can contain oxygen or sulfur dioxide which form heat-stable salts with the amine solution (see Fluidization Petroleum). 

Many grades of recycled rubber produced from grinding and heating of vulcanized rubber products such as tyres, baby bottle nipples and other goods are also available. Although reclaimed rubber offers some processing advantages, its use has declined in recent years because of the extensive use of blended polymers. 

The normal regeneration temperature in the still will not regenerate heat-stable salts or oxazolidone-2. Therefore, a reclaimer is usually included to remove these contaminants. A side stream of from 1 to 3% of the MEA circulation is drawn from the bottom of the stripping column, This stream is then heated to boil the water and MEA overhead while the heat-stable salts and oxazolidone-2 are retained in the reclaimer. The reclaimer is periodically shut in and the collected contaminants are cleaned out and removed from the system. However, any MEA bonded to them is also lost. 

When MEA is used in the presence of COS and CS2, they react to form heat-stable salts. Therefore, MEA systems usually include a reclaimer, The reclaimer is a kettle-type reboiler operating on a small side stream of lean solution. The temperature in the reclaimer is maintained such that the water and MEA boil to the overhead and are piped back to the stripper. The heat-stable salts remain in the reclaimer until the reclaimer is full. Then the reclaimer is shut-in and dumped to a waste disposal. Thus, the impurities are removed but the MEA bonded to the salts is also lost. 

Warm water or low-, medium- or high-temperature hot water systems are categorized in Table 27.8. Warm water systems may use heat pumps, fully condensing boilers or similar generators, or reclaimed heat. In many cases the system design may incorporate an alternative heat generator for standby purposes or for extreme whether operation. Under such circumstances the system may continue to function at warm water temperatures or could operate at more conventional LTUW ones. 

This is the vessel where the refrigerant rejects its heat to waste or reclaim, turning back to liquid in the process. Sub-cooling is practiced by the removal of further heat. This prevents liquid flashing back to vapor on return to the evaporator. 

Plating is carried out in a closed system whose atmosphere is adjusted to contain the metal-gas and a second gas which may be an inert diluent or a reactive gas (as in 1 above). is heated, for example by high frequency, and this then initiates deposition of M, by one of the above steps. Spent reaction products are exhausted and where possible reclaimed and recycled. 

In the unit dehumidifier process, all or part of the condenser heat is used to re-heat the air leaving the evaporator (see Figure 29.1a). Since the moisture in the air has given up its latent heat in condensing, this heat is reclaimed and put back into the outlet air. In a typical application, air at 25°C dry bulb and 60% saturation can be dried and re-heated to a condition of 46°C dry bulb and 10% saturation (see Figure 24.13). In this state, it is hot enough to provide the necessary latent heat to dryout the load product. The entire system is in one unit, requiring only an electrical supply and a water drain, so there is no constraint on location. 

Distillation retorts and furnaces are used either to reclaim zinc from alloys or to refine crude zinc. Bottle retort furnaces consist of a pear-shaped ceramic retort (a long-necked vessel used for distillation). Bottle retorts are filled with zinc alloys and heated until most of the zinc is vaporized, sometimes for as long as 24 h. Distillation involves vaporization of zinc at temperatures from 980 to 1250°C (1800 to 2280°F), and condensation as zinc dust or liquid zinc. Zinc dust is produced by vaporization and rapid cooling, and liquid zinc results when the vaporous product is condensed slowly at moderate temperatures. 

The product resulting from the treatment of waste rubber (flash, used tyres, etc.) by heat and chemical agents, which effect sufficient break down and softening so that the reclaim may be used as a compounding ingredient in fresh compound without excessive degradation of physical properties. 

Contaminated feedstock is heated in an indirectly fired rotary dryer. The vapors are then transported to a gas treatment system via an inert gas such as nitrogen where they are scrubbed and cooled to condense the organics. The carrier gas is reheated and recycled to the dryer. The recovered organics can be reclaimed, used on-site or off-site as fuel, or incinerated. The technology is available in laboratory-, pilot-, and full-scale systems. 

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