Thermocouple type-K

Temperature thermocouples (Type-K 1 mm) at ten vertical positions in the bed (Figure 10). 

BS 4937 Part 4 1973. British Standard 4937 (British Standards Institution, London). Nickel-chromium/nickel-aluminium thermocouples. Type K. 

Figure 1. Supercritical flow reactor. Key (I) Mettler balance (2) flask with 1 0 (filtered and deaerated) (3) HPLC pump (4) bypass (three-way) valve (5) feed cylinder (6) weather balloon with feed solution (7) probe thermocouple (type K) (8) ceramic annulus (9) Hastelloy C-276 tube (10) entrance cooling jacket (11) entrance heater (12) furnace coils (13) quartz gold-plated IR mirror (14) window (no coils) (15) guard heater (16) outlet cooling jacket (17) ten-port dualloop sampling value (18) product accumulator (19) air compressor (20) back-pressure regulator and (21) outflow measuring assembly.

The temperature inside the reactor is measured with seven thermocouples (Type K). To avoid channelling, the thermocouples are placed only 5 mm into the bed. The temperature inside the manifold is also measured, as well as at several points at the outlet pipe. The pressure in the manifold and inside the reactor is also measured with the help of pressure transducers. In order to take gas samples, a sample line has been built (Fig. 4). It consists of a steel condenser and three glass bottles in an ice bath, a moisture filter (silica gel), a pump and a gas flowmeter. A sample of O.S ml is taken from the gas sample line with a syringe and inserted into a gas chromatograph from SRI Instruments equipped with a TCD detector and a Supelco column (Carboxen I0(X)). 

The large rig is of the same size as a domestic boiler. The design is chosen to ensure well-defined start- and boundary conditions for the fuel bed. The rig is equipped to measure airflow, weight loss and bed height. Temperatures can be measured upstream, in and downstream of the fuel bed and in the grate by shielded 1-mm thermocouples (type K), mounted both from the side (orthogonal to the movement of the ignition... 

Raw shale contained in the top furnace and reactor was retorted at a linear heating rate. Gases and vapors evolved during retorting passed through the second reactor at 504 to 610°C where the oil was thermally cracked. Temperatures were measured at the center of the bottom reactor by a stainless-steel-sheathed thermocouple (Type K). Temperature variation across the reactor was less than 3°C. To simulate conditions inside a shale block, the bottom reactor contained pieces of shale. We used burnt shale (mostly silicates and MgO) in most of the experiments because it is thermally stable above 500°C. In two experiments, we used retorted shale (2.7% organic carbon, 24.4% acid-evolved CO2) and no shale, respectively. 

The insertion of the electroconductor wire as a sensing element (yam-based sensor) into a textile auxiliary wall was carried out during the weaving process. A number of thermocouples (type k constantan (Cn)/copper (Cu)) formed a thermopile, created with a posttreatment (Fig. 19.7(a)). This thermopile is judiciously disposed on both sides of the textile auxiliary wall to measure the temperature gradient (Fig. 19.7(b)). 

The microreactor system characteristics have been careftilly studied in order to confirm that the temperature-time profile could really approach the ideal "square wave" shape. A number of experiments have been performed to study these profiles, utilizing micro-thermocouples (type K 25 nm diameter) spot welded onto each wire, so that oscilloscope traces of the actual profiles, upon activation of the pyrolysis system, could be obtained (Fairburn, 1988). In all cases, the... 

AU Fe Thermocouples Type E Thermocouples Type T Thermocouples Type K Thermocouples Platinum Resistance Rh-Fe Resistance Silicon Diode Carbon-glass Resistance Germanium Resistance Carbon Resistance O2 Vapor Pressure N2 Vapor Pressure Ne Vapor Pressure H2 Vapor Pressure He Vapor Pressure He Gas... 

The Type K thermocouple (Table 11.59) is more resistant to oxidation at elevated temperatures than the Type E, J, or T thermocouple, and consequently finds wide application at temperatures above 500°C. It is recommended for continuous use at temperatures within the range — 250 to 1260°C in inert or oxidizing atmospheres. It should not be used in sulfurous or reducing atmospheres, or in vacuum at high temperatures for extended times. 

The Type N thermocouple (Table 11.60) is similar to Type K but it has been designed to minimize some of the instabilities in the conventional Chromel-Alumel combination. Changes in the alloy content have improved the order/disorder h ansformations occurring at 500°C and a higher silicon content of the positive element improves the oxidation resistance at elevated temperatures. 

TABLE 11.59 Type K Thermocouples Nickel-Chromium Alloy vs. Nickel-Aluminum Alloy... 

Thermocouples are primarily based on the Seebeck effect In an open circuit, consisting of two wires of different materials joined together at one end, an electromotive force (voltage) is generated between the free wire ends when subject to a temperature gradient. Because the voltage is dependent on the temperature difference between the wires (measurement) junction and the free (reference) ends, the system can be used for temperature measurement. Before modern electronic developments, a real reference temperature, for example, a water-ice bath, was used for the reference end of the thermocouple circuit. This is not necessary today, as the reference can be obtained electronically. Thermocouple material pairs, their temperature-electromotive forces, and tolerances are standardized. The standards are close to each other but not identical. The most common base-metal pairs are iron-constantan (type J), chomel-alumel (type K), and copper-constantan (type T). Noble-metal thermocouples (types S, R, and B) are made of platinum and rhodium in different mixing ratios. 

The measurement ranges for the base-metal thermocouples are 0 to +750 °C (type J), -200 to +1200 °C (type K), and -200 to +350 °C (type T). The noble-metal thermocouples can be used at higher temperatures up to 1700 °C. The dynamic response of sheathed thermocouples is not very fast however, a probe made from bare, thin wires can have very fast dynamic properties. One of the best features of thermocouples is the simplicity of making new probes by soldering or welding the ends of two wires together. 

An Omega model HH22 type J-K digital thermometer, connected to a type K thermocouple probe inserted directly into the flask, was used to measure the temperature. 

Gulton-Rustrak Quartel Data Logger - Model 58-100 with - Type K thermocouple pod-58-124... 

The output of the system was calibrated against a conventional type K thermocouple and a calibration curve, resulting from using such a laser diode with a 670-nm... 

B024 Containment shell CON SHELL c 1 A Type J thermocouple B Type K thermocouple C RTD Z other... 

Spaces between the coal block and the reactor walls are filled with refractory cement to prevent accumulation of combustible gases, and leaks are exhausted from the outer casing. Temperatures are measured with 1/8" Type K SS sheathed thermocouples, which are cemented Into the block at predetermined locations. 

As was shown in Figure 3.159, cryogenic temperatures can be detected by integrated circuit diodes types K, T, and E thermocouples (TCs) class A and B resistance temperature detectors (RTDs) acoustic and ultrasonic thermometers germanium and carbon resistors and paramagnetic salts. As TCs and RTDs will be discussed in separate subsections, here the focus will be on the other sensors. 

Table 2.2 shows various standardized thermocouple types commonly available. Each is optimal for a given set of conditions. For example, type K wire is used for lower temperature ( 1100°C max) furnaces and type S thermocouples for higher temperature furnaces ( 1500°C max). Type K is much less expensive than 5, has a higher (voltage) output, but is less refractory. The two alloys in type K can be distinguished since alumel is magnetic and chromel is not. The rhodium content of... 

Junction beads can be made for platinum-based thermocouples, such as types R, S, or B, by welding with a high-temperature flame (e.g. oxy-acetylene). Using a flame for junction formation in alloy-based (e.g. K- or 2 -type) thermocouples does not work well since the wires tend to oxidize rather than fuse. Beads are more effectively made by electric arc for these thermocouple types. 

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